CN118398618B - Shielded gate power device with low leakage and fast recovery capability - Google Patents

Abstract

The present invention relates to a shielded gate power device, in particular to a shielded gate power device with low leakage and fast recovery capability. According to the technical solution provided by the present invention, a shielded gate power device with low leakage and fast recovery capability, the shielded gate power device comprises: a semiconductor substrate, which is of a first conductive type; an active region, distributed in the central area of the semiconductor substrate, including a number of SGT cells and at least one Schottky-like diode, wherein the Schottky-like diode is a trench-type Schottky-like diode, and the Schottky-like diode includes a diode-like trench located in the active region; in the active region, the trench depth of the diode-like trench is greater than the trench depth of the cell trench of any SGT cell. The present invention can effectively reduce the leakage current of the shielded gate power device, enhance the avalanche capability, and improve the stability and reliability of the SGT power device during operation.

Description

Shielded gate power device with low leakage and fast recovery capability

Technical Field

The invention relates to a shielded gate power device, in particular to a shielded gate power device with low leakage and fast recovery capability.

Background Art

SGT (Shield Gate Trench) power devices are a new type of power semiconductor devices, which have the advantages of low conduction loss and low switching loss compared with traditional power semiconductor devices. SGT power devices can include SGT MOSFET devices and SGT IGBT (Insulated Gate Bipolar Transistor) devices. Among them, SGTMOSFET (Metal-Oxide- Semiconductor Field-Effect Transistor) devices are widely used as switching devices and can achieve excellent power control effects.

The cell of the existing SGT power device is generally composed of two parts: a shield gate and a control gate. When the SGT power device is turned on, the drain current follows the longitudinal sidewall of the SGT trench to form an inversion layer channel on the surface of the body region. When the source is positively biased, electrons are transmitted from the source region to the drain region along the inversion layer channel. After passing through the channel from the source region, the electrons enter the epitaxial region at the bottom of the trench gate and then expand across the width of the entire active region.

In order to improve the reverse recovery efficiency and reverse recovery capability of SGT power devices, Schottky-like diodes are currently integrated in the active region. However, after the Schottky-like diodes are integrated in the active region, it is easy to cause electric field concentration, which further leads to large leakage and low avalanche capability, which will reduce the reliability of SGT power devices.

Summary of the invention

The purpose of the present invention is to overcome the deficiencies in the prior art and provide a shielded gate power device with low leakage and fast recovery capability, which can effectively reduce the leakage current of the shielded gate power device, enhance the avalanche capability, and improve the stability and reliability of the SGT power device during operation.

According to the technical solution provided by the present invention, a shielded gate power device with low leakage and fast recovery capability comprises:

A semiconductor substrate having a first conductivity type;

The active region is distributed in the central area of the semiconductor substrate and includes a plurality of SGT cells and at least one Schottky-like diode, wherein:

The Schottky-like diode is a trench-type Schottky-like diode, and the Schottky-like diode includes a diode-like trench located in an active region;

In the active region, the trench depth of the diode-like trench is greater than the trench depth of the cell trench of any SGT cell.

The Schottky-like diode comprises a diode electrode body filled in the diode-like trench, wherein:

The diode electrode body comprises a first electrode body in the groove and a second electrode body in the groove corresponding to the first electrode body in the groove, and the second electrode body in the groove is adjacent to the groove opening of the diode groove;

The first electrode body in the groove includes a first region of the first electrode body in the groove that enters into the second electrode body in the groove and a second region of the first electrode body in the groove that is located below the second electrode body in the groove, wherein:

The first region of the first electrode body in the groove is separated from the second electrode body in the groove by the electrode body isolation dielectric layer, and the second region of the first electrode body in the groove is insulated and isolated from the bottom wall and the corresponding side wall of the diode trench by the field oxide layer in the groove;

The second electrode body in the groove is insulated and isolated from the sidewall of the diode groove by the gate oxide layer in the groove, the thickness of the gate oxide layer in the groove is less than the thickness of the field oxide layer in the groove, and the gate oxide layer in the groove contacts the field oxide layer in the groove;

The first electrode body in the groove and the second electrode body in the groove are both electrically connected to the first electrode metal of the device above the semiconductor substrate, wherein:

The first electrode metal of the device also makes ohmic contact with the first conductive type source region of the diode corresponding to the outer side of the diode-like trench and the second conductive type base region that traverses the active region.

The first conductive type source region and the second conductive type base region of the diode are both in contact with the outer sidewall of the diode-like trench.

In the diode-like trench, the width of the second electrode body in the trench is greater than the width of the first electrode body in the trench;

The width of the first region of the first electrode body in the groove is smaller than the width of the second region of the first electrode body in the groove;

The end surface of the first region of the first electrode body in the groove is located above the bottom surface of the second conductive type base region;

The end surface of the second electrode body in the groove adjacent to the bottom of the diode-like groove is not higher than the bottom surface of the second conductive type base region.

In the active area, a self-isolation unit is provided at least on one side of the Schottky-like diode, wherein:

The self-isolation unit comprises a self-isolation trench and an isolation unit electrode body filled in the self-isolation trench;

The isolation unit electrode body is insulated and isolated from the sidewalls and bottom wall of the self-isolation trench where it is located by an oxide layer in the isolation trench;

The isolation unit electrode body is electrically connected to the first electrode metal of the device.

In the active area, the trench depth of the self-isolation trench is consistent with the trench depth of the diode-like trench;

The height of the isolation unit electrode body is consistent with the height of the first electrode body in the groove, and the second end of the isolation unit electrode body is flush with the end of the first region of the first electrode body in the groove;

The first end of the isolation unit electrode body is adjacent to the bottom of the self-isolation trench.

The self-isolation unit further includes an isolation unit first conductivity type source region located outside the self-isolation trench, wherein:

The first conductive type source region of the isolation unit is located in the second conductive type base region outside the self-isolation trench, and both the first conductive type source region and the second conductive type base region of the isolation unit are in contact with the outer side wall of the self-isolation trench;

The first electrode metal of the device is also electrically connected to the first conductivity type source region and the second conductivity type base region of the isolation unit.

The self-isolation unit further includes an isolation unit second conductivity type injection region disposed outside the self-isolation trench and an isolation unit external contact hole corresponding to the isolation unit second conductivity type injection region, wherein:

The second conductive type injection region of the isolation unit penetrates the second conductive type base region outside the isolation trench, the doping concentration of the second conductive type injection region of the isolation unit is greater than the doping concentration of the second conductive type base region, and the bottom of the second conductive type injection region of the isolation unit is located below the bottom surface of the second conductive type base region;

The second conductive type implantation region of the isolation unit contacts the corresponding outer sidewall of the self-isolation trench, and the second conductive type implantation region of the isolation unit is in ohmic contact with the first electrode metal of the device filled in the external contact hole of the isolation unit.

On the cross section of the shielded gate power device, the isolation unit external contact hole is in a trapezoidal shape, wherein:

The width of the first end of the isolation unit external contact hole is smaller than the width of the second end of the isolation unit external contact hole, wherein the first end of the isolation unit external contact hole is located below the notch of the self-isolation trench;

The width of the second end of the isolation unit external contact hole is greater than the width of the second conductivity type implantation region of the isolation unit, so that the second end of the isolation unit external contact hole enters the notch region of the self-isolation trench.

For any SGT cell, an SGT structure is provided in the cell groove of the SGT cell, wherein:

When the SGT structure adopts a top-bottom structure, the SGT structure includes a cell bottom electrode body and a cell top electrode body, the cell top electrode body is located above the cell bottom electrode body, and the cell top electrode body is insulated and isolated from the cell bottom electrode body;

The cell upper electrode body is insulated and isolated from the sidewall of the cell trench through the cell gate oxide layer;

The thickness of the cell gate oxide layer is greater than the thickness of the gate oxide layer in the trench;

The upper electrode body of the cell is electrically connected to the second electrode metal of the device above the semiconductor substrate, and the lower electrode body of the cell is electrically connected to the first electrode metal of the device.

In the active area, a number of source area contact hole units are arranged, wherein:

The source region contact hole unit is distributed at least between two adjacent SGT cells;

The source contact hole unit includes a source contact hole and a second conductive type implantation region under the contact hole located directly below the source contact hole, wherein:

The doping concentration of the second conductive type injection region under the contact hole is greater than the doping concentration of the second conductive type base region, and the second conductive type injection region under the contact hole is located below the second conductive type base region and contacts the corresponding second conductive type base region;

The first electrode metal of the device is filled in the source contact hole, and the first electrode metal of the device is in ohmic contact with the second conductivity type injection region under the contact hole, the second conductivity type base region, and the first conductivity type source region of the cell on both sides of the filled source contact hole;

The first conductive type source region of the cell contacts the outer sidewall of the corresponding cell trench.

The advantages of the present invention are as follows: when the fast recovery capability of the shielded gate power device is improved by arranging a Schottky-like diode in the active region, the depth of the diode-like groove of the Schottky-like diode can be configured, and the self-isolation unit and/or the source region contact hole unit can be increased to avoid leakage breakdown from occurring at the gate oxide layer in the groove of the Schottky-like diode, thereby reducing the leakage of the shielded gate power device, improving the withstand voltage of the shielded gate power device, and enhancing the avalanche capability of the shielded gate power device.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a structural cross-sectional view of a first embodiment of the present invention.

FIG. 2 is a structural cross-sectional view of a second embodiment of the present invention.

FIG3 is a structural cross-sectional view of a third embodiment of the present invention.

FIG. 4 is a structural cross-sectional view of a fourth embodiment of the present invention.

FIG5 is a structural cross-sectional view of a fifth embodiment of the present invention.

Description of the accompanying drawings: 1-substrate, 2-epitaxial layer, 3-cell trench, 4-diode-type trench, 5-cell field oxide layer, 6-cell lower electrode body, 7-P-type base region, 8-cell upper electrode body, 9-interlayer oxide layer, 10-cell gate oxide layer, 11-notch oxide layer, 12-cell N+ source region, 13-contact P+ injection region, 14-field oxide layer in the groove, 15-first electrode body in the groove, 16-gate oxide layer in the groove, 17- 7-the second electrode body in the groove, 18-the electrode body isolation dielectric layer, 19-the self-isolation groove, 20-the oxide layer in the isolation groove, 21-the isolation unit electrode body, 22-the diode electrode body contact hole, 23-the P+ injection region under the contact hole, 24-the isolation unit P+ injection region, 25-the isolation unit external contact hole, 26-the isolation unit internal contact hole, 27-the source region contact hole, 28-the diode N+ source region, 29-the isolation unit N+ source region.

DETAILED DESCRIPTION

The present invention will be further described below in conjunction with specific drawings and embodiments.

In order to effectively reduce the leakage current of the shielded gate power device, enhance the avalanche capability, and improve the stability and reliability of the SGT power device during operation, the present invention provides a shielded gate power device with low leakage and fast recovery capability. Taking the first conductive type as N type as an example, specifically, the shielded gate power device includes:

A semiconductor substrate having an N conductivity type;

The active region is distributed in the central area of the semiconductor substrate and includes a plurality of SGT cells and at least one Schottky-like diode, wherein:

The Schottky-like diode is a trench-type Schottky-like diode, and the Schottky-like diode includes a diode-like trench 4 located in the active area;

In the active region, the depth of the diode-like trench 4 is greater than the depth of the cell trench 3 of any SGT cell.

It can be understood that the shielded gate power device can be the SGT MOSFET device, SGT IGBT device or other types of power devices mentioned above, and the type of the shielded gate power device can be selected as needed to meet the actual application requirements. For shielded gate power devices, they generally include a semiconductor substrate, that is, the power device is generally prepared on a semiconductor substrate, and the conductivity type of the semiconductor substrate is N-type. Figures 1 to 5 show an embodiment of a semiconductor substrate. In the figure, the semiconductor substrate includes a substrate 1 and an epitaxial layer 2 located on the substrate 1. At this time, the conductivity types of the substrate 1 and the epitaxial layer 2 are both N-type. Generally, the doping concentration of the epitaxial layer 2 is less than the doping concentration of the substrate 1, and the thickness of the epitaxial layer 2 is greater than the thickness of the substrate 1. The conditions of the substrate 1 and the epitaxial layer 2 are consistent with the existing semiconductor substrates and will not be repeated here.

For shielded gate power devices, they generally include an active area and a terminal area located on the outer circle of the active area. The terminal area generally surrounds the active area. The terminal area can be used to improve the voltage resistance of the active area. The distribution of the active area and the terminal area on the semiconductor substrate, as well as the specific coordinated working methods are consistent with the existing ones and will not be repeated here.

The shielded gate power device of the present invention includes a plurality of SGT cells in the active region, and the SGT cells in the active region are connected in parallel as a whole. The number of SGT cells in the active region can be selected according to actual scenarios to meet actual needs.

In order to improve the reverse recovery efficiency and reverse recovery capability of the shielded gate power device, it can be seen from the above description that at least one Schottky-like diode can be set in the active area, that is, the reverse recovery efficiency and reverse recovery capability of the shielded gate power device can be improved by using the Schottky-like diode set. At the same time, after setting the Schottky-like diode in the active area, the leakage current of the shielded gate power device will increase and the avalanche capability will be reduced. It can be understood that after the Schottky-like diode is set, the area where leakage occurs is the area where the Schottky-like diode is located.

In order to reduce the leakage current of the shielded gate power device and enhance the avalanche capability, in one embodiment of the present invention, the Schottky-like diode is selected as a trench-type Schottky-like diode. Therefore, the Schottky-like diode at least includes a diode-like groove 4 located in the active area. Of course, a corresponding Schottky-like diode structure needs to be prepared in the diode-like groove 4. The Schottky-like diode structure will be described in detail below.

In one embodiment of the present invention, the groove depth of the diode-like groove 4 is greater than the groove depth of the cell groove 3 of any SGT cell. FIG. 1 to FIG. 5 show a distribution embodiment of the diode-like groove 4 and the cell groove 3. In the figure, the notch of the diode-like groove 4 and the notch of the cell groove 3 are both located on the surface of the epitaxial layer 2, and the groove bottom of the diode-like groove 4 and the groove bottom of the cell groove 3 are both located in the epitaxial layer 2. Generally, all the cell grooves 3 in the active area can have the same groove depth. Of course, the cell grooves 3 in the active area can also have different groove depths, which can be selected according to needs to meet actual needs. FIG. 1 to FIG. 5 show an embodiment in which all the cell grooves 3 in the active area have the same groove depth.

In a specific implementation, the groove depth of all the cell grooves 3 in the active area is less than the groove depth of the diode-like groove 4, wherein when the groove depth of the diode-like groove 4 is greater than the groove depth of the cell groove 3, the groove bottom of the diode-like groove 4 is located below the groove bottom of the cell groove 3. It can be seen from the above description that when a Schottky-like diode is set in the active area, the area where the leakage current increases will occur in the area where the Schottky-like diode is located. When the groove depth of the diode-like groove 4 is greater than the groove depth of the cell groove 3, the withstand voltage of the area where the Schottky-like diode is located can be increased, so that when the shielded gate power device is reversely turned off, the breakdown area occurs as much as possible in the area where the SGT cell is located, thereby reducing the leakage current of the shielded gate power device when it is reversely turned off and enhancing the avalanche capability.

In one embodiment of the present invention, the Schottky-like diode comprises a diode electrode body filled in the diode-like trench 4, wherein:

The diode electrode body includes a first in-groove electrode body 15 and a second in-groove electrode body 17 corresponding to the first in-groove electrode body 15, and the second in-groove electrode body 17 is adjacent to the notch of the diode trench 4;

The first in-slot electrode body 15 includes a first in-slot electrode body first region entering into the second in-slot electrode body 17 and a second in-slot electrode body second region located below the second in-slot electrode body 17, wherein:

The first region of the first electrode body in the groove is separated from the second electrode body 17 in the groove by the electrode body isolation dielectric layer 18, and the second region of the first electrode body in the groove is insulated and isolated from the bottom wall and the corresponding side wall of the diode trench 4 by the field oxide layer 14 in the groove;

The second electrode body 17 in the trench is insulated and isolated from the sidewall of the diode trench 4 in which it is located by the gate oxide layer 16 in the trench, the thickness of the gate oxide layer 16 in the trench is less than the thickness of the field oxide layer 14 in the trench, and the gate oxide layer 16 in the trench is in contact with the field oxide layer 14 in the trench;

The first electrode body 15 in the groove and the second electrode body 17 in the groove are both electrically connected to the first electrode metal of the device above the semiconductor substrate, wherein:

The first electrode metal of the device also makes ohmic contact with the corresponding diode N+ source region 28 outside the diode-like trench 4 and the P-type base region 7 that traverses the active region.

The diode N+ source region 28 and the P-type base region 7 are both in contact with the outer sidewall of the diode-like trench 4 .

Figures 1 to 5 all show an embodiment of setting up a Schottky-like diode, that is, an embodiment of a Schottky-like diode structure in a diode-like groove 4. In the figure, the Schottky-like diode also includes a diode electrode body filled in the diode-like groove 4, that is, the diode electrode body is located in the diode-like groove 4; in addition, the figure shows an embodiment in which the diode electrode body includes a first electrode body 15 in the groove and a second electrode body 17 in the groove. The first electrode body 15 in the groove and the second electrode body 17 in the groove can generally be selected as existing commonly used conductive polysilicon. Of course, other commonly used electrode body materials can also be used. The corresponding materials of the first electrode body 15 in the groove and the second electrode body 17 in the groove can be selected according to actual needs, so as to meet the actual application requirements.

In Fig. 1 to Fig. 5, in the diode-like groove 4, the second electrode body 17 in the groove is adjacent to the groove opening of the diode-like groove 4, the length direction of the first electrode body 15 in the groove is consistent with the length direction of the diode-like groove 4, the lower end of the first electrode body 15 in the groove is adjacent to the groove bottom of the diode-like groove 4, and the upper end of the first electrode body 15 in the groove corresponds to the second electrode body 17 in the groove. Specifically, the first electrode body 15 in the groove includes a first region of the first electrode body in the groove that enters the second electrode body 17 in the groove and a second region of the first electrode body in the groove that is located below the second electrode body 17 in the groove. Fig. 1, Fig. 2, Fig. 4 and Fig. 5 show an embodiment in which the first region of the first electrode body in the groove is smaller than the height/thickness of the second electrode body 17 in the groove, and Fig. 3 shows an embodiment in which the first region of the first electrode body in the groove is the same as the height/thickness of the second electrode body 17 in the groove.

In Figures 1 to 5, the first region of the first electrode body in the groove is separated from the second electrode body 17 in the groove by an electrode body isolation dielectric layer 18, and the electrode body isolation dielectric layer 18 can be a silicon dioxide layer, and the electrode body isolation dielectric layer 18 is coated on the first region of the first electrode body in the groove; wherein, in Figure 3, the end surface of the first region of the first electrode body in the groove can be covered by other isolation dielectric layers in the diode-like groove 4. In Figures 1, 2, 4 and 5, the electrode body isolation dielectric layer 18 can fully cover the first region of the first electrode body in the groove.

The second region of the first electrode body in the groove is also the lower region of the first electrode body 15 in the groove. The second region of the first electrode body in the groove is insulated and isolated from the bottom wall and the corresponding side wall of the diode trench 4 in which it is located by the field oxide layer 14 in the groove. The second electrode body 17 in the groove is insulated and isolated from the side wall of the diode trench 4 in which it is located by the gate oxide layer 16 in the groove. Therefore, the gate oxide layer 16 in the groove is also adjacent to the groove opening of the diode trench 4 in which it is located. The height of the gate oxide layer 16 in the groove is generally smaller than the height of the second electrode body 17 in the groove, wherein the height is the dimension along the length direction of the diode trench 4 in which it is located.

The gate oxide layer 16 in the groove contacts the field oxide layer 14 in the groove, so that the inner wall and the bottom wall of the diode-like groove 4 are covered with an oxide layer. Optionally, the thickness of the electrode body isolation dielectric layer 18 is consistent with the thickness of the gate oxide layer 16 in the groove; of course, the thickness of the electrode body isolation dielectric layer 18 can also be different from the thickness of the gate oxide layer 16 in the groove, which can be selected according to needs. When the electrode body isolation dielectric layer 18 and the gate oxide layer 16 in the groove have the same thickness and are both silicon dioxide layers, the electrode body isolation dielectric layer 18 and the gate oxide layer 16 in the groove can be prepared and formed by the same thermal oxidation process.

In specific implementation, the first electrode body 15 in the groove and the second electrode body 17 in the groove are electrically connected to the first electrode metal of the device above the semiconductor substrate, wherein the first electrode metal of the device is not shown in Figures 1 to 5. It can be understood that the first electrode metal of the device can form the first electrode of the shielded gate power device. When the shielded gate power device is an SGT MOSFET device, the first electrode is the source electrode; when the shielded gate power device is an SGT IGBT device, the first electrode is the emitter. When the shielded gate power device is of other types, the type of the first electrode formed based on the first electrode metal of the device can be determined, and examples will not be given one by one here.

It is understandable that the first electrode body 15 in the groove and the second electrode body 17 in the groove can be led out in an existing commonly used manner to achieve electrical connection with the first electrode metal of the device after being led out. When the first electrode body 15 in the groove and the second electrode body 17 in the groove are made of conductive polysilicon, the electrical connection between the first electrode body 15 in the groove and the second electrode body 17 in the groove and the first electrode metal of the device specifically refers to forming an ohmic contact with the first electrode metal of the device; when the first electrode body 15 in the groove and the second electrode body 17 in the groove are made of other materials, a specific state of electrical connection with the first electrode metal of the device can be obtained, which will not be explained one by one here.

It should be noted that a P-type base region 7 is also provided in the active region, wherein the P-type base region 7 generally traverses the active region, that is, the P-type base region 7 is distributed throughout the active region, and the bottom of the cell trench 3 and the corresponding bottom of the diode-like trench 4 are both located below the P-type base region 7. In order to form a conductive channel on the sidewall of the diode-like trench 4, a diode N+ source region 28 needs to be provided on the outside of the diode-like trench 4. The diode N+ source region 28 is generally located in the region of the P-type base region 7 that contacts the diode-like trench 4. As shown in FIGS. 1 to 5 , the diode N+ source region 28 contacts the corresponding sidewall of the diode-like trench 4, and the junction depth of the diode N+ source region 28 is less than the junction depth of the P-type base region 7.

In specific implementation, the first electrode metal of the device is also electrically connected to the diode N+ source region 28 and the P-type base region 7 outside the diode-like groove 4, wherein the first electrode metal of the device is generally in ohmic contact with the diode N+ source region 28, and the first electrode metal of the device can be in ohmic contact with the P-type base region 7 where the diode N+ source region 28 is located or electrically connected in other ways, that is, the electrical connection method between the first electrode metal of the device and the P-type base region 7 where the diode N+ source region 28 is located can be selected. When the first electrode body 15 in the groove and the second electrode body 17 in the groove are set in the diode-like groove 4, at the same time, the first electrode body 15 in the groove and the second electrode body 17 in the groove are separated by the electrode body isolation dielectric layer 18, and the first electrode body 15 in the groove and the second electrode body 17 in the groove are both electrically connected to the first electrode metal of the device, the gate-drain capacitance Cgd of the shielded gate power device can be reduced, thereby reducing the switching loss of the shielded gate power device.

In one embodiment of the present invention, in the diode-like trench 4, the width of the second electrode body 17 in the trench is greater than the width of the first electrode body 15 in the trench;

The width of the first region of the first electrode body in the groove is smaller than the width of the second region of the first electrode body in the groove;

The end surface of the first region of the first electrode body in the groove is located above the bottom surface of the P-type base region 7;

The end surface of the second electrode body 17 in the groove adjacent to the bottom of the diode-like groove 4 is not higher than the bottom surface of the P-type base region 7 .

Figures 1 to 5 show an embodiment in which the width of the second electrode body 17 in the groove is greater than the width of the first electrode body 15 in the groove. In the figures, the second electrode body 17 in the groove is directly in contact with the gate oxide layer 16 in the groove, and the second region of the first electrode body 15 in the groove is in contact with the field oxide layer 14 in the groove; the width of the first region of the first electrode body in the groove is smaller than the width of the second region of the first electrode body in the groove.

In order to further disperse the electric field and reduce leakage through the gate oxide layer 16 in the groove, the end surface of the first region of the first electrode body in the groove is located above the bottom surface of the P-type base region 7, wherein the bottom surface of the P-type base region 7 specifically refers to the surface of the P-type base region 7 adjacent to the bottom of the diode-like groove 4. In addition, the end surface of the second electrode body 17 in the groove adjacent to the bottom of the diode-like groove 4 is not higher than the bottom surface of the P-type base region 7. In Figures 1 to 5, the end surface of the second electrode body 17 in the groove adjacent to the bottom of the diode-like groove 4 is located below the bottom surface of the P-type base region 7, that is, the end surface is located between the P-type base region 7 and the bottom of the diode-like groove 4. In addition, Figures 1 to 5 also show an embodiment in which the end surface of the second electrode body 17 in the groove adjacent to the bottom of the diode-like groove 4 is inclined. It can be understood that when the end surface of the second electrode body 17 in the groove adjacent to the bottom of the diode-like groove 4 is located below the bottom surface of the P-type base region 7 and the end surface of the second electrode body 17 in the groove adjacent to the bottom of the diode-like groove 4 is inclined, the gate-drain capacitance Cgd of the shielded gate power device can be further reduced.

As can be seen from the above description, the first electrode metal of the device is electrically connected to the diode N+ source region 28 and the corresponding P-type base region 7. Figures 1 to 3 show an embodiment of ohmic contact, wherein, in Figures 1 to 3, a contact P+ injection region 13 is also provided in the P-type base region 7, the doping concentration of the contact P+ injection region 13 is greater than the doping concentration of the P-type base region 7, and the contact P+ injection region 13 is in contact with the diode N+ source region 28. At this time, the first electrode metal of the device can directly make ohmic contact with the diode N+ source region 28, and at the same time, the first electrode metal of the device is electrically connected to the corresponding P-type base region 7 through the contact P+ injection region 13. In addition, the first electrode body 15 in the groove and the second electrode body 17 in the groove can be electrically connected to the first electrode metal of the device by a lead-out method commonly used in the technical field, and the specific lead-out method is not shown in the figure.

In the embodiments in FIG. 4 and FIG. 5 , the first electrode metal of the device can be in direct ohmic contact with the diode N+ source region 28. In addition, by setting a diode electrode body contact hole 22 in the notch region of the diode-like groove 4, the diode electrode body contact hole 22 penetrates the second electrode body 17 in the groove and corresponds to the first region of the first electrode body in the groove, so that after the first electrode metal of the device is filled in the diode electrode body contact hole 22, the first electrode metal of the device can be electrically connected to the first electrode body 15 in the groove and the second electrode body 17 in the groove. In FIG. 4 and FIG. 5 , the first electrode metal of the device filled in the isolation unit outer contact hole 25 contacts the isolation unit P+ injection region 24, and the isolation unit P+ injection region 24 contacts the corresponding P-type base region 7, so that a conductive channel can still be formed on the side wall of the diode-like groove 4 adjacent to the isolation unit outer contact hole 25, that is, it will not affect the normal operation of the Schottky-like diode.

In one embodiment of the present invention, a self-isolation unit is provided in the active region at least on one side of the Schottky-like diode, wherein:

The self-isolation unit includes a self-isolation trench 19 and an isolation unit electrode body 21 filled in the self-isolation trench 19;

The isolation unit electrode body 21 is insulated and isolated from the sidewalls and bottom wall of the self-isolation trench 19 through the oxide layer 20 in the isolation trench;

The isolation unit electrode body 21 is electrically connected to the first electrode metal of the device.

In order to further reduce the leakage current of the shielded gate power device during reverse recovery, in one embodiment of the present invention, at least one self-isolation unit can be set in the active area, wherein the self-isolation unit can generally be distributed on one side of the Schottky-like diode, or a self-isolation unit can be set on both sides of the Schottky-like diode. Figures 2 to 4 show an embodiment of setting a self-isolation unit on the left side of the Schottky-like diode, and Figure 5 shows an embodiment of setting a self-isolation unit on both sides of the Schottky-like diode. The distribution of the self-isolation unit in the active area can be selected according to actual needs. At this time, the isolation effect of the self-isolation unit can be used to disperse the electric field gathered on the side wall of the diode-like groove 4, further reducing the leakage current at the Schottky-like diode.

FIG2 to FIG5 show an embodiment of a self-isolation unit, in which the self-isolation unit includes a self-isolation groove 19 and an isolation unit electrode body 21 filled in the self-isolation groove 19, the notch of the self-isolation groove 19 is located on the surface of the epitaxial layer 2, and the bottom of the self-isolation groove 19 is located in the epitaxial layer 2. The isolation unit electrode body 21 can be conductive polysilicon or other conductive materials, and the specific material type can be selected according to needs.

An isolation trench inner oxide layer 20 is provided in the self-isolation trench 19. The isolation trench inner oxide layer 20 is generally a silicon dioxide layer. The isolation trench inner oxide layer 20 can be used to isolate the isolation unit electrode body 21 from the sidewall and bottom wall of the self-isolation trench 19. Generally, the thickness of the isolation trench inner oxide layer 20 can be consistent with the thickness of the field oxide layer 14 in the trench.

During specific implementation, it is provided to electrically connect the isolation unit electrode body 21 with the first electrode metal of the device, wherein the isolation unit electrode body 21 can be electrically connected with the first electrode metal of the device by using the commonly used technical means in the present technology, and the method of leading out the isolation unit electrode body 21 and connecting it with the first electrode metal of the device is not shown in FIGS. 1 to 3 ; FIGS. 4 to 5 show an embodiment of leading out and connecting the isolation unit electrode body 21, in which an isolation unit internal contact hole 26 is provided at the notch of the self-isolation groove 19, and the isolation unit internal contact hole 26 is opened from the notch of the self-isolation groove 19 vertically toward the groove bottom direction of the self-isolation groove 19, and the isolation unit electrode body 21 can be exposed through the isolation unit internal contact hole 26, and thereafter, the first electrode metal of the device can be filled in the isolation unit internal contact hole 26, that is, the contact between the first electrode metal of the device and the isolation unit electrode body 21, as well as the electrical connection after the contact can be realized.

It should be noted that after the self-isolation unit is set on one side of the Schottky-like diode, since the isolation unit electrode body 21 in the self-isolation unit is also electrically connected to the first electrode metal of the device, the shielded gate power device can disperse the electric field in the reverse recovery state to protect the Schottky-like diode, so that the area where leakage breakdown occurs is moved from the Schottky-like diode to the area where the self-isolation unit is located, or even to the area outside the self-isolation unit, thereby avoiding the electric field from gathering in the side wall area corresponding to the diode-like groove and the gate oxide layer 16 in the groove. It can be seen that while maintaining the fast recovery capability of the shielded gate power device, the leakage can be further reduced and the avalanche capability of the shielded gate power device can be enhanced.

In Figures 2 to 4, a self-isolation unit is set on the left side of the Schottky-like diode. At this time, the area where leakage breakdown occurs can be moved at least to the area where the self-isolation unit is located; in Figure 5, after a self-isolation unit is set on both sides of the Schottky-like diode, the area where leakage breakdown occurs can be moved at least to the area where the self-isolation unit is located, thereby reducing leakage and enhancing the avalanche capability of the shielded gate power device.

In one embodiment of the present invention, in the active region, the trench depth of the self-isolation trench 19 is consistent with the trench depth of the diode-like trench 4;

The height of the isolation unit electrode body 21 is consistent with the height of the first electrode body 15 in the groove, and the second end of the isolation unit electrode body 21 is flush with the end of the first region of the first electrode body in the groove;

The first end of the isolation unit electrode body 21 is adjacent to the bottom of the self-isolation trench 19 .

As can be seen from FIG. 2 to FIG. 5 and the above description, the notch of the self-isolation groove 19 corresponds to the surface of the epitaxial layer 2. When the groove depth of the self-isolation groove 19 is consistent with the groove depth of the diode-like groove 4, the groove bottom of the self-isolation groove 19 and the groove bottom of the diode-like groove 4 are flush in the epitaxial layer 2. At this time, the self-isolation groove 19 and the diode-like groove 4 can be prepared and formed based on the same groove process. When the groove depth of the self-isolation groove 19 is consistent with the groove depth of the diode-like groove, the groove depth of the self-isolation groove 19 is larger. At this time, the groove depth of the self-isolation groove 19 can be used to further increase the withstand voltage of the self-isolation unit. At this time, the avalanche breakdown point of the Schottky-like diode can be turned to the SGT cell area with relatively low withstand voltage, which can effectively reduce the electric field of the Schottky-like diode, reduce the leakage of the Schottky-like diode, and improve the avalanche breakdown capability of the snow shielded gate power device.

In FIG. 1 to FIG. 5 , the length direction of the isolation unit electrode body 21 is consistent with the length direction of the self-isolation groove 19, and the isolation unit electrode body 21 has a first end and a second end corresponding to the first end, wherein the first end of the isolation unit electrode body 21 is adjacent to the bottom of the self-isolation groove 19, and in this case: the second end of the isolation unit electrode body 21 is adjacent to the notch of the self-isolation groove 19. In one embodiment of the present invention, the height of the isolation unit electrode body 21 is consistent with the height of the first electrode body 15 in the groove, and the height is the dimension along the length direction of the self-isolation groove 19 and the diode-like groove 4.

In addition, the second end of the isolation unit electrode body 21 is flush with the end of the first region of the first electrode body in the groove. As can be seen from the above description, at this time, the second end of the isolation unit electrode body 21 is located above the bottom surface of the P-type base region 7. When the second end of the isolation unit electrode body 21 is set above the bottom surface of the P-type base region 7, the field plate effect of the first electrode of the shielded gate power device can be further enhanced, the withstand voltage can be improved, and the leakage can be reduced.

During specific implementation, a trench P+ injection region can also be set at the bottom of the self-isolation trench 19 and/or the diode-like trench 4, and the trench P+ injection region can be used to cover the bottom of the self-isolation trench 19 and the diode-like trench 4. The trench P+ injection region can be used to further avoid the accumulation of the electric field at the bottom of the diode-like trench 4 and the self-isolation trench 19, thereby further improving the withstand voltage of the Schottky-like diode and the self-isolation unit. As a result, the withstand voltage of the shielded gate device can be further improved, and the avalanche capability of the shielded gate power device can be enhanced.

In one embodiment of the present invention, the self-isolation unit further includes an isolation unit N+ source region 29 located outside the self-isolation trench 19, wherein:

The isolation unit N+ source region 29 is located in the P-type base region 7 outside the self-isolation trench 19, and the isolation unit N+ source region 29 and the P-type base region 7 are both in contact with the outer side wall of the self-isolation trench 19;

The first electrode metal of the device is also electrically connected to the isolation unit N+ source region 29 and the P-type base region 7 .

FIG. 2 and FIG. 3 show an embodiment in which an isolation unit N+ source region 29 is disposed on the outer side of the self-isolation trench 19. The isolation unit N+ source region 29 is located in the P-type base region 7 in contact with the self-isolation trench 19, and the isolation unit N+ source region 29 is in contact with the outer side wall of the self-isolation trench 19. When the first electrode metal of the device is electrically connected to the isolation unit N+ source region 29 and the P-type base region 7, a conductive channel can be formed on the outer side wall of the self-isolation trench 19 when the shielded gate power device is in operation, and at this time, the on-resistance of the shielded gate power device can be reduced.

In one embodiment of the present invention, the self-isolation unit further includes an isolation unit P+ injection region 24 disposed outside the self-isolation trench 19 and an isolation unit external contact hole 25 corresponding to the isolation unit P+ injection region 24, wherein:

The isolation unit P+ injection region 24 penetrates the P-type base region 7 outside the isolation trench 19, the doping concentration of the isolation unit P+ injection region 24 is greater than the doping concentration of the P-type base region 7, and the bottom of the isolation unit P+ injection region 24 is located below the bottom surface of the P-type base region 7;

The isolation unit P+ implantation region 24 contacts the corresponding outer sidewall of the self-isolation trench 19 , and the isolation unit P+ implantation region 24 makes ohmic contact with the first electrode metal of the device filled in the isolation unit external contact hole 25 .

As can be seen from FIG. 2 to FIG. 3 and the above description, when the isolation unit N+ source region 29 is set on the outside of the self-isolation groove 19, a conductive channel can be formed on the outside of the self-isolation groove 19. In order to reduce the influence of the conductive channel and further improve the withstand voltage of the shielded gate power device, in FIG. 4 to FIG. 5, an isolation unit P+ injection region 24 and an isolation unit external contact hole 25 corresponding to the isolation unit P+ injection region 24 are set on the outside of the self-isolation groove 19, that is, the isolation unit external contact hole 25 is in one-to-one correspondence with the isolation unit P+ injection region 24. Specifically, the isolation unit P+ injection region 24 penetrates the P-type base region 7, and the junction depth of the isolation unit P+ injection region 24 is greater than the junction depth of the P-type base region 7, that is, the bottom of the isolation unit P+ injection region 24 is located below the P-type base region 7, and the isolation unit P+ injection region 24 is in contact with the P-type base region 7.

In Figures 4 and 5, the isolation unit P+ injection region 24 contacts the corresponding outer side wall of the self-isolation trench 19, and the isolation unit external contact hole 25 is distributed at least along the outer side wall of the self-isolation trench 19. When the isolation unit external contact hole 25 is set on the outer side wall of the self-isolation trench 19, there is no above-mentioned isolation unit N+ source region 29 on the outer side wall of the self-isolation trench 19, that is, a conductive channel cannot be formed on the outer wall of the self-isolation trench 19.

Specifically, the isolation unit P+ injection region 24 can effectively reduce the electric field of the contacted P-type base region 7. Since the isolation unit P+ injection region 24 is adjacent to the Schottky-like diode, the electric field concentration at the gate oxide layer 16 in the trench of the Schottky-like diode can be further alleviated, thereby reducing leakage. In addition, a hot carrier extraction channel can be formed through the isolation unit P+ injection region 24, further enhancing the avalanche capability of the shielded gate power device.

The depth of the isolation unit external contact hole 25 is smaller than the depth of the isolation unit P+ injection region 24. In a specific implementation, the device first electrode metal can be filled in the isolation unit external contact hole 25. At this time, the device first electrode metal is in ohmic contact with the isolation unit P+ injection region 24, and can be electrically connected to the P-type base region 7 through the isolation unit P+ injection region 24.

In one embodiment of the present invention, in the cross section of the shielded gate power device, the isolation unit external contact hole 25 is in a trapezoidal shape, wherein:

The width of the first end of the isolation unit external contact hole 25 is smaller than the width of the second end of the isolation unit external contact hole 25, wherein the first end of the isolation unit external contact hole 25 is located below the notch of the self-isolation trench 19;

The width of the second end of the isolation unit external contact hole 25 is greater than the width of the isolation unit P+ implantation region 24 , so that the second end of the isolation unit external contact hole 25 enters the notch region of the self-isolation trench 19 .

In Figures 4 to 5, the isolation unit external contact hole 25 may be trapezoidal in shape, and the isolation unit external contact hole 25 has a first end and a second end corresponding to the first end, wherein the first end of the isolation unit external contact hole 25 is located below the notch of the self-isolation groove 19, and the first end of the isolation unit external contact hole 25 is adjacent to the bottom of the self-isolation groove 19, at this time, the second end of the isolation unit external contact hole 25 corresponds to the notch of the self-isolation groove 19.

In one embodiment of the present invention, the width of the first end of the isolation unit external contact hole 25 is smaller than the width of the second end of the isolation unit external contact hole 25, and the width of the second end of the isolation unit external contact hole 25 is larger than the width of the isolation unit P+ injection region 24, so that the second end of the isolation unit external contact hole 25 enters the notch area of the self-isolation groove 19, as shown in Figures 4 and 5. At this time, when etching to form the isolation unit external contact hole 25, the oxide layer 20 in the isolation trench of the notch of the self-isolation groove 19 will be partially etched away, which can increase the width of the isolation unit external contact hole 25.

After increasing the width of the isolation unit external contact hole 25, the injection depth of the isolation unit P+ injection region 24 can be further enhanced. As can be seen from the above description, after enhancing the injection depth of the isolation unit P+ injection region 24, the isolation unit P+ injection region 24 can be used to further increase the protection of the gate oxide layer 16 in the trench, which can further alleviate the electric field concentration at the gate oxide layer 16 in the trench of the Schottky-like diode, and reduce the leakage at the gate oxide layer 16 in the trench of the Schottky-like diode. In specific implementation, the isolation unit external contact hole 25 can be first etched from the outside of the isolation trench 19 to form the isolation unit external contact hole 25. After the isolation unit external contact hole 25 is prepared, P-type impurity ions are implanted to form the isolation unit P+ injection region 24.

In one embodiment of the present invention, for any SGT cell, an SGT structure is provided in the cell groove 3 of the SGT cell, wherein:

When the SGT structure adopts a top-bottom structure, the SGT structure includes a cell bottom electrode body 6 and a cell top electrode body 8, the cell top electrode body 8 is located above the cell bottom electrode body 6, and the cell top electrode body 8 is insulated and isolated from the cell bottom electrode body 6;

The cell upper electrode body 8 is insulated and isolated from the sidewall of the cell trench 3 by the cell gate oxide layer 10;

The thickness of the cell gate oxide layer 10 is greater than the thickness of the in-groove gate oxide layer 16;

The cell upper electrode body 8 is electrically connected to the second electrode metal of the device above the semiconductor substrate, and the cell lower electrode body 6 is electrically connected to the first electrode metal of the device.

FIG. 1 to FIG. 5 show an embodiment in which an SGT structure is arranged in a cell groove 3, and the SGT structure adopts an upper and lower structure, wherein the SGT structure includes a cell lower electrode body 6 and a cell upper electrode body 8. As can be seen from the above description, the cell lower electrode body 6 and the cell upper electrode body 8 can generally be made of conductive polysilicon. Of course, other conductive materials can also be used, and the type of specific material can be selected as needed. In FIG. 1 to FIG. 5, the cell upper electrode body 8 is located above the cell lower electrode body 6. At this time, in the cell groove 3, the cell upper electrode body 8 is adjacent to the notch of the cell groove 3, and the cell lower electrode body 6 is closer to the groove bottom of the cell groove 3.

It can be known from the SGT cell principle that in the cell groove 3, the cell upper electrode body 8 and the cell lower electrode body 6 need to be insulated and isolated, and the cell upper electrode body 8 is electrically connected to the second electrode metal of the device, and the cell lower electrode body 6 is electrically connected to the first electrode metal of the device. It can be seen from the above description that the first electrode metal of the device can form the first electrode of the shielded gate power device; at this time, the second electrode of the shielded gate power device can be formed by using the second electrode metal of the device. When the shielded gate power device is an SGT MOSFET device, the second electrode is the gate electrode of the SGT MOSFET device. When the shielded gate power device is an SGT IGBT device, the second electrode is the gate of the SGT IGBT device. When the shielded gate power device is other types of power devices, the type of second electrode formed based on the second electrode metal of the device can be obtained, which will not be repeated here.

In order to achieve insulation isolation between the cell upper electrode body 8 and the cell lower electrode body 6, an interlayer oxide layer 9 is provided in the cell groove 3, and insulation isolation between the cell upper electrode body 8 and the cell lower electrode body 6 can be achieved by using the interlayer oxide layer 9. In addition, a cell field oxide layer 5 is provided in the cell groove 3, the cell field oxide layer 5 corresponds to the cell lower electrode body 6, and the cell field oxide layer 5 covers the side wall and the bottom wall of the cell groove 3, so the cell lower electrode body 6 can be insulated and isolated from the side wall and the bottom wall of the cell groove 3 by using the cell field oxide layer 5, and of course, the interlayer oxide layer 9 is in contact with the cell field oxide layer 5.

The cell upper electrode body 8 is in corresponding contact with the cell gate oxide layer 10 in the cell trench 3, and the cell gate oxide layer 10 covers the corresponding side wall of the cell trench 3. It should be noted that the cell gate oxide layer 10, the cell field oxide layer 5 and the interlayer oxide layer 9 are all silicon dioxide layers, which can be prepared by thermal oxidation process; the thickness of the cell gate oxide layer 10 is less than the thickness of the cell field oxide layer 5, and in addition, the thickness of the cell gate oxide layer 10 is less than the thickness of the gate oxide layer 16 in the groove, so it can be seen that the turn-on voltage of the Schottky-like diode is less than the turn-on voltage of the SGT cell.

When the thickness of the cell gate oxide layer 10 is less than the thickness of the cell field oxide layer 5, the width of the cell upper electrode body 8 should be greater than the width of the cell lower electrode body 6; in addition, in Figures 1 to 5, a notch oxide layer 11 is also provided in the cell groove 3, and the notch oxide layer 11 can be used to cover the cell upper electrode body 8, so as to achieve insulation isolation between the cell upper electrode body 8 and the first electrode metal of the device. Further, the end surface of the cell upper electrode body 8 adjacent to the bottom of the cell groove 3 is located below the bottom surface of the P-type base region 7.

In order to form a conductive channel of the SGT cell, a cell N+ source region 12 should be set on the outer side wall of the cell trench 3. The cell N+ source region 12 is located in the P-type base region 7 in contact with the cell trench 3, and the cell N+ source region 12 contacts the outer side wall of the corresponding cell trench 3. At the same time, the cell N+ source region 12 and the P-type base region 7 in which it is located need to be in ohmic contact with the first electrode metal of the device. In order to achieve ohmic contact with the first electrode metal of the device, in Figures 1 to 3, a contact P+ injection region 13 is set in the P-type base region 7, and the doping concentration of the contact P+ injection region 13 is greater than the doping concentration of the P-type base region 7. The contact P+ injection region 13 contacts the cell N+ source region 12. At this time, the first electrode metal of the device can be in ohmic contact with the cell N+ source region 12, and the electrical connection with the corresponding P-type base region 7 is achieved through the contact P+ injection region 13.

It should be noted that the contact P+ implantation region 13 can be formed by ion implantation in the P-type base region 7 . FIGS. 1 to 3 show an embodiment of directly performing ion implantation in the P-type base region 7 to form the contact P+ implantation region 13 .

In a specific implementation, the cell trench 3 , the diode-like trench 4 , and the self-isolation trench 19 are all in the shape of long strips, and the cell trench 3 , the diode-like trench 4 , and the self-isolation trench 19 are parallel to each other.

The following is an explanation of how the Schottky-like diodes in the active region can improve the recovery capability of the shielded gate power device, specifically:

When a reverse recovery current flows through the first electrode metal of the shielded gate power device, a voltage drop will be generated when the current flows through the Schottky-like diode, and then the Schottky-like diode is at a positive voltage. Since the thickness of the gate oxide layer 16 in the groove is less than the thickness of the cell gate oxide layer 10, before the forward bias voltage of the PN junction between the P-type base region 7 and the epitaxial layer 2 increases to 0.7v, the channel at the gate oxide layer 16 in the groove can be turned on before the channel at the cell gate oxide layer 10, thereby making the forward bias voltage of the PN junction between the P-type base region 7 and the epitaxial layer 2 less than 0.7v. That is, before the PN junction is turned on, the channel at the Schottky-like diode has already been turned on, causing the mobile charge inside the PN junction to be lost and consumed, making it impossible for the mobile charge inside the PN junction to accumulate, resulting in the voltage of the PN junction unable to rise to 0.7V. As a result, the change in the depletion region of the PN junction affected by the voltage is reduced, and the PN junction can recover more quickly, thereby reducing the reverse recovery charge Qrr and reverse recovery time Trr of the shielded gate power device and improving the reverse recovery characteristics of the shielded gate power device.

In one embodiment of the present invention, a plurality of source region contact hole units are arranged in the active region, wherein:

The source region contact hole unit is distributed at least between two adjacent SGT cells;

The source contact hole unit includes a source contact hole 27 and a contact hole P+ implantation region 23 located directly below the source contact hole 27, wherein:

The doping concentration of the P+ injection region 23 under the contact hole is greater than the doping concentration of the P-type base region 7. The P+ injection region 23 under the contact hole is located below the P-type base region 7 and contacts the corresponding P-type base region 7.

The first electrode metal of the device is filled in the source contact hole 27, and the first electrode metal of the device is in ohmic contact with the P+ injection region 23 under the contact hole, the P-type base region 7, and the cell N+ source region 12 on both sides of the filled source contact hole;

The cell N+ source region 12 contacts the outer sidewall of the corresponding cell trench 3 .

In order to further protect the Schottky-like diode, a source contact hole unit may be provided in the active region, wherein the source contact hole unit is distributed between at least two adjacent SGT cells, as shown in FIG4 . Of course, the source contact hole unit may also be distributed between the Schottky-like diode and the SGT cell, as shown in FIG4 and FIG5 . When the source contact hole unit is distributed between the Schottky-like diode and the SGT cell, it may be specifically related to the distribution position of the Schottky-like diode; specifically, the source contact hole unit corresponds to the above-mentioned contact P+ injection region 13, that is, by improving the position of the contact P+ injection region 13, the withstand voltage of the shielded gate power device can be further improved, thereby achieving the purpose of protecting the Schottky-like diode.

FIG. 4 and FIG. 5 show an embodiment of a source contact hole unit. In the figure, the source contact hole unit includes a source contact hole 27 and a contact hole P+ injection area 23 located directly below the source contact hole 27. As can be seen from the above description, the location of the source contact hole 27 can be the same as the location of the contact P+ injection area 13. The difference is that the width of the source contact hole 27 is greater than the width of the contact P+ injection area 13. It can be understood that when the contact P+ injection area 13 shown in FIG. 1 to FIG. 3 is set, the step of opening the contact hole can be omitted under the condition that the connection of the first electrode metal of the device is met. When the source contact hole 27 is set in the active area, the source contact hole 27 must be set outside the cell trench 3 and/or outside the diode-like trench 4. The source contact hole 27 can be prepared and formed using the contact hole process commonly used in the technical field.

In one embodiment of the present invention, the depth of the source contact hole 27 is at least consistent with the thickness of the P-type base region 7. At this time, the opening of the source contact hole 27 is located on the surface of the epitaxial layer 2, and the bottom of the source contact hole 27 is flush with the bottom surface of the P-type base region 7, or the bottom of the source contact hole 27 is located below the P-type base region 7. At this time, the source contact hole 27 contacts the cell N+ source regions 12 on both sides. In specific implementation, after the source contact hole 27 is opened, an ion implantation process can be used to form a P+ implantation region 23 below the source contact hole 27. The doping concentration of the P+ implantation region 23 below the contact hole is greater than the doping concentration of the P-type base region 7, and the P+ implantation region 23 below the contact hole contacts the corresponding P-type base region 7, as shown in Figures 4 and 5.

After the first electrode metal of the device is filled in the source contact hole 27, the first electrode metal of the device will make ohmic contact with the cell N+ source region 12, the P-type base region 7 and the P+ injection region 23 under the contact hole on both sides of the source contact hole 27; at this time, the P+ injection region 23 under the contact hole can be used to achieve a dispersed electric field, which can further reduce the concentration of the electric field in the gate oxide layer 16 in the inner groove of the Schottky-like diode, thereby reducing the possibility of leakage at the gate oxide layer 16 in the inner groove of the Schottky-like diode.

Claims (9)

1. A shielded gate power device with low leakage and fast recovery capability, the shielded gate power device comprising:

a semiconductor substrate of a first conductivity type;

An active region distributed in a central region of the semiconductor substrate and comprising a plurality of SGT cells and at least one Schottky-like diode, wherein,

The schottky-like diode is a trench schottky-like diode, and comprises a diode-like trench located in the active region;

in the active region, the groove depth of the diode-like groove is larger than the groove depth of a cell groove of any SGT cell;

For the schottky-like diode, comprising a diode electrode body filled in the diode-like trench, wherein,

The diode electrode body comprises a first electrode body in a groove and a second electrode body in the groove corresponding to the first electrode body in the groove, and the second electrode body in the groove is adjacent to a notch of the diode-like groove;

The first electrode body in the groove comprises a first area of the first electrode body in the groove entering the second electrode body in the groove and a second area of the first electrode body in the groove below the second electrode body in the groove, wherein,

The first region of the first electrode body in the groove is separated from the second electrode body in the groove by an electrode body isolation medium layer, and the second region of the first electrode body in the groove is isolated from the bottom wall and the corresponding side wall of the diode-like groove by using a field oxide layer in the groove;

The second electrode body in the groove is insulated and isolated from the side wall of the diode-like groove by the gate oxide layer in the groove, the thickness of the gate oxide layer in the groove is smaller than that of the field oxide layer in the groove, and the gate oxide layer in the groove is contacted with the field oxide layer in the groove;

the first electrode body in the groove and the second electrode body in the groove are electrically connected with the first electrode metal of the device above the semiconductor substrate, wherein,

The device first electrode metal is also in ohmic contact with the diode first conductivity type source region corresponding to the outside of the diode-like trench and the second conductivity type base region traversing the active region,

The diode first conduction type source region and the second conduction type base region are both in contact with the outer side wall of the diode-like groove.

2. The shielded gate power device with low leakage and fast recovery capability of claim 1, wherein a width of the second electrode body in the trench is greater than a width of the first electrode body in the trench in the diode-like trench;

the width of the first area of the first electrode body in the groove is smaller than that of the second area of the first electrode body in the groove;

the end face of the first region of the first electrode body in the groove is positioned above the bottom face of the second conductive type base region;

the end face of the second electrode body in the groove, which is adjacent to the bottom of the diode-like groove, is not higher than the bottom face of the second conductive type base region.

3. The shielded gate power device with low leakage and fast recovery capability according to claim 1, wherein a self-isolation cell is provided in the active region at least on one side of the schottky-like diode, wherein,

The self-isolation unit comprises a self-isolation groove and an isolation unit electrode body filled in the self-isolation groove;

The isolation unit electrode body is isolated from the side wall and the bottom wall of the self-isolation groove through an oxide layer in the isolation groove;

the isolation unit electrode body is electrically connected with the first electrode metal of the device.

4. A shielded gate power device with low leakage and fast recovery capability according to claim 3, wherein the self-isolation trench has a trench depth in the active region that corresponds to the trench depth of the diode-like trench;

the height of the isolation unit electrode body is consistent with that of the first electrode body in the groove, and the second end part of the isolation unit electrode body is level with the end part of the first area of the first electrode body in the groove;

The first end of the isolation unit electrode body is adjacent to the bottom of the self-isolation trench.

5. The shielded gate power device with low leakage and fast recovery capability according to claim 3, further comprising an isolation cell source region of a first conductivity type outside the self-isolation trench for the self-isolation cell, wherein,

The isolation unit first conductive type source region is positioned in the second conductive type base region outside the self-isolation trench, and the isolation unit first conductive type source region and the second conductive type base region are both in contact with the outer side wall of the self-isolation trench;

the first electrode metal of the device is also electrically connected with the first conductive type source region and the second conductive type base region of the isolation unit.

6. The device of claim 3, further comprising an isolation cell second conductivity type injection region disposed outside the self-isolation trench and an isolation cell external contact hole corresponding to the isolation cell second conductivity type injection region for the self-isolation cell,

The second conductive type injection region of the isolation unit penetrates through the second conductive type base region outside the isolation groove, the doping concentration of the second conductive type injection region of the isolation unit is larger than that of the second conductive type base region, and the bottom of the second conductive type injection region of the isolation unit is positioned below the bottom surface of the second conductive type base region;

The isolation unit second conductivity type injection region is in contact with the corresponding outer side wall of the self-isolation trench, and the isolation unit second conductivity type injection region is in ohmic contact with the device first electrode metal filled in the isolation unit outer contact hole.

7. The shielded gate power device with low leakage and fast recovery capability according to claim 6, wherein the isolation cell outer contact hole has a trapezoid shape in a cross section of the shielded gate power device, wherein,

The width of the first end of the outer contact hole of the isolation unit is smaller than that of the second end of the outer contact hole of the isolation unit, wherein the first end of the outer contact hole of the isolation unit is positioned below a notch of the self-isolation groove;

The width of the second end of the isolation unit outer contact hole is greater than the width of the isolation unit second conductivity type injection region, so that the second end of the isolation unit outer contact hole enters the notch region of the self-isolation trench.

8. The shielded gate power device with low leakage and fast recovery capability according to any one of claims 1 to 7, wherein for any one SGT cell, an SGT structure is provided in a cell trench of said SGT cell, wherein,

When the SGT structure adopts an up-down structure, the SGT structure comprises a cell lower electrode body and a cell upper electrode body, wherein the cell upper electrode body is positioned above the cell lower electrode body, and the cell upper electrode body is insulated and isolated from the cell lower electrode body;

the upper electrode body of the cell is insulated and isolated from the side wall of the cell groove through the cell gate oxide layer;

The thickness of the cellular gate oxide layer is larger than that of the gate oxide layer in the groove;

the upper electrode body of the cell is electrically connected with the second electrode metal of the device above the semiconductor substrate, and the lower electrode body of the cell is electrically connected with the first electrode metal of the device.

9. The shielded gate power device with low leakage and fast recovery capability according to claim 8, wherein a plurality of source contact hole cells are disposed in the active region, wherein,

The source region contact hole units are at least distributed between two adjacent SGT unit cells;

The source region contact hole unit comprises a source region contact hole and a contact Kong Xiadi two conductivity type injection region positioned right below the source region contact hole, wherein,

The doping concentration of the contact Kong Xiadi second conductive type injection region is larger than that of the second conductive type base region, and the contact Kong Xiadi second conductive type injection region is positioned below the second conductive type base region and is in contact with the corresponding second conductive type base region;

The first electrode metal of the device is filled in the contact hole of the source region, and is in ohmic contact with the two conductive type injection regions of the contact Kong Xiadi, the second conductive type base region and the cell first conductive type source regions at two sides of the contact hole of the filled source region;

The first conductivity type source region of the cell is in contact with the outer sidewall of the corresponding cell trench.