CN107256883B - A kind of two-way TVS diode of two-way and preparation method thereof - Google Patents

Abstract

The invention discloses a two-way bidirectional TVS diode and a manufacturing method thereof. Including: back electrode, N+ substrate, P-epitaxial layer, two P-wells arranged side by side in the P-epitaxial layer, N-type isolation regions on both sides of the P-well, P-type doping in each P-well region, an N-type doped region located in each P-type doped region, an oxide layer located on the surface of the P-epitaxial layer, a contact hole is provided in the oxide layer corresponding to each N-type doped region, and two front electrodes The passivation layer is electrically connected to the corresponding N-type doped region through respective contact holes, and is located on the front electrode and the oxide layer. The two TVS diodes are composed of N-type doped regions, P-type doped regions, P wells and N+ substrates. The unique NPN structure makes the TVS diodes bidirectionally symmetrical. The two TVSs are separated by an N-type isolation region, and there is also an N-type isolation at the edge of the device, which minimizes the leakage between the two diodes in the device and the leakage at the edge of the device.

Description

A kind of two-way bidirectional TVS diode and its manufacturing method

technical field

The invention relates to the technical field of semiconductors, in particular to a two-way bidirectional TVS diode and a manufacturing method thereof.

Background technique

With the development of semiconductor technology, ultra-deep submicron has become the mainstream process of integrated circuit processing. However, there will always be various unexpected surges and static electricity in various interface segments. In order to ensure the reliability of integrated circuits, protective devices mainly based on TVS diodes are widely used in sensitive ports that have generated surges. . The TVS diode is connected in parallel to the front end of the protected circuit. Under normal conditions, TVS is high impedance, and ideally it can be regarded as an open circuit. When a transient high voltage is suddenly input from the outside, the TVS immediately uses the avalanche breakdown effect of the PN junction to reduce the impedance, and the surge generated by the high voltage is shunted by the TVS diode. At the same time, the voltage at both ends of the TVS is clamped below the maximum clamping voltage. When the surge disappears, the TVS returns to its previous high-impedance state.

TVS diodes are widely used in mobile phones, tablet computers, liquid crystal displays, cameras, and set-top boxes. In traditional applications, engineers will connect a TVS diode in parallel to the ports that are prone to surges. In this way, if there are many I/O ports, not to mention the cost, it also takes up too many resources on the PCB board.

Contents of the invention

The technical problem to be solved by the present invention is: how to provide a two-way bidirectional TVS diode and its manufacturing method. The present invention utilizes the dual-way TVS diode designed with the integration concept, and one device can protect two-way I/O interfaces.

The present invention is achieved through the following technical solutions:

A method for manufacturing two-way bidirectional TVS diodes, comprising the following steps:

(1) Provide N+ substrate;

(2) growing a silicon dioxide layer and a silicon nitride layer sequentially on the front and back sides of the N+ substrate, respectively;

(3) removing the silicon dioxide layer and silicon nitride layer on the front side of the N+ substrate, and retaining the silicon dioxide layer and silicon nitride layer on the back side of the N+ substrate as a back seal layer;

(4) growing a P- epitaxial layer on the front side of the N+ substrate, and then wet etching to remove the silicon dioxide layer and silicon nitride layer on the back side of the N+ substrate;

(5) performing boron doping in the P- epitaxial layer using a mask to form two P wells arranged side by side;

(6) N-type isolation regions are formed by phosphorus doping at the edges of both sides of the P- epitaxial layer and between the two P wells;

(7) Forming a P-type doped region by ion-implanting boron in each P-well;

(8) Forming an N-type doped region by ion-implanting phosphorus in each P-type doped region;

(9) forming an oxide layer on the P- epitaxial layer, forming a contact hole in the oxide layer corresponding to each N-type doped region, and depositing a front electrode in each contact hole and on the surface of the oxide layer;

(10) Form a passivation layer on the surface of the front electrode, and form a hole in the passivation layer as a back-end packaging wiring;

(11) Thinning the N+ substrate, and then preparing a back electrode on the back of the N+ substrate, so as to complete the fabrication of two-way bidirectional TVS diodes.

Preferably, the N+ substrate in the step (1) has a <111> crystal orientation, is doped with As, has a resistivity of 0.007 Ohm.cm, and a thickness of 675 microns.

Preferably, in the step (2), the silicon dioxide layer has a thickness of 1-3 microns, and the silicon nitride layer has a thickness of 1-3 microns. In the step (3), firstly, the plasma The silicon nitride layer on the front side of the N+ substrate is removed by bulk etching, and then the silicon dioxide layer on the front side of the N+ substrate is removed by using a mixed reagent of hydrofluoric acid and ammonium fluoride.

Preferably, in the step (4), the thickness of the P-epitaxial layer is 3-6 microns, the resistivity of the P-epitaxial layer is 50-150 Ohm.cm, and the P-epitaxial layer is protected by photoresist - the epitaxial layer, the etching solution for wet etching is hydrofluoric acid.

Preferably, the specific process of the step (5) is: grow a 700-nanometer oxide layer, then apply glue, photolithography, development, etch, open an opening in an appropriate area, and ion-implant boron in the opening, the implantation dose is 4E14 /cm ² , the implantation energy is 70KeV.

Preferably, the specific process of the step (5) is: forming a mask, then applying glue, photolithography, developing, and etching, opening a window in an appropriate area, and ion-implanting boron in the window, with an implantation dose of 4E14 /cm ^2. The implantation energy is 70KeV. The specific process of the step (6) is: forming a mask, opening a window in an appropriate area, and then putting the N+ substrate into a furnace tube at 1000°C, and injecting PoCL3 gas for doping impurity, form N-type doped region in P-epitaxy, and connect with N-type substrate to form N-type isolation region.

Preferably, the specific process of the step (7) is: forming a mask, opening a window in a suitable area of the P well, and ion-implanting boron element with an implantation dose of 4E14/cm ² and an implantation energy of 160KeV to form a P well. type doping region; the specific process of the step (8) is: forming a mask, opening a window in a suitable area of the P-type doping region, and ion-implanting phosphorus element, the implantation dose is 3E15 /cm ² , and the implantation energy 45KeV, forming an N-type doped region.

Preferably, the specific process of the step (9) is as follows: the oxide layer is a silicon dioxide layer, the thickness of the oxide layer is 200-500 nanometers, the front electrode is an aluminum-silicon-copper electrode, and the thickness of the front electrode is 1-4 microns.

Preferably, the specific process of the step (10) is: deposit 1-3 micron thick PSG (phosphosilicate glass) and 1-3 micron thick Si ₃ N ₄ on the surface of the front electrode as a passivation layer.

Preferably, the specific process of the step (11) is as follows: the N+ substrate is thinned to 250 microns, and the back gold is made by evaporation to form the back electrode.

The gold back can be made by evaporation of metal elements, preferably by evaporation of gold elements.

The present invention also proposes a two-way bidirectional TVS diode, which is prepared according to the manufacturing method of the above-mentioned two-way bidirectional TVS diode.

The two TVS diodes of the present invention are respectively composed of an N-type doped region, a P-type doped region, a P well and an N+ substrate, and the unique NPN structure enables the TVS diode to have bidirectional symmetry. The two TVS are separated by an N-type isolation area, and there is also an N-type isolation at the edge of the device, which minimizes the leakage before the two diodes in the device and the leakage at the edge of the device. The present invention integrates the two The bidirectional TVS diode is integrated in one chip, and one device can protect two I/O ports, which greatly saves the area occupied by the PCB board and saves the cost.

Description of drawings

1-11 are flowcharts of the manufacturing method of the two-way bidirectional TVS diode of the present invention. .

Detailed ways

As shown in Figure 1-11, a method of manufacturing a two-way bidirectional TVS diode includes the following steps:

(1) Provide an N+ substrate, as shown in Figure 1, the N+ substrate has a <111> crystal orientation, is doped with As, has a resistivity of 0.007Ohm.cm, and a thickness of 675 microns;

(2) A silicon dioxide layer and a silicon nitride layer are sequentially grown on both sides of the N+ substrate respectively, as shown in FIG. 2 , the thickness of the silicon dioxide layer is 1-3 microns, and the nitrided The thickness of the silicon layer is 1-3 microns;

(3) removing the silicon dioxide layer and silicon nitride layer on the front side of the N+ substrate, and retaining the silicon dioxide layer and silicon nitride layer on the back side of the N+ substrate as the back seal layer, as shown in FIG. 3 , Specifically, firstly, the silicon nitride layer on the front side of the N+ substrate is removed by plasma etching, and then the silicon dioxide layer on the front side of the N+ substrate is removed by a mixed reagent of hydrofluoric acid and ammonium fluoride;

(4) A P- epitaxial layer is grown on the front side of the N+ substrate, and then the silicon dioxide layer and the silicon nitride layer on the back side of the N+ substrate are removed by wet etching, as shown in FIG. 4 , the P- epitaxial layer The thickness of the layer is 3-6 microns, the resistivity of the P-epitaxial layer is 50-150 Ohm.cm, the P-epitaxial layer is protected by photoresist, and the etching solution for wet etching is hydrofluoric acid ;

(5) Use a mask to perform boron doping in the P- epitaxial layer to form two P wells arranged side by side, as shown in Figure 5, the specific process is: grow a 700 nm oxide layer, then apply glue, light Engraving, development, etching, openings in appropriate areas, ion-implanting boron elements in the openings, the implantation dose is 4E14 /cm ² , and the implantation energy is 70KeV;

(6) N-type isolation regions are formed by phosphorus doping at the edges of both sides of the P- epitaxial layer and between the two P wells, as shown in FIG. 6 , the specific process is: forming a mask, Open a window in the region, then put the N+ substrate into a furnace tube at 1000°C, inject PoCL3 gas for doping, form an N-type doped region in the P- epitaxy, and connect it to the N-type substrate to form an N-type quarantine area;

(7) Form a P-type doped region by ion-implanting boron in each P-well, as shown in Figure 7, the specific process is: forming a mask, opening a window in a suitable area of the P-well, and ion-implanting boron element, the implantation dose is 4E14 /cm ² , and the implantation energy is 160KeV to form a P-type doped region;

(8) In each P-type doped region, an N-type doped region is formed by ion-implanting phosphorus, as shown in FIG. 8 , the specific process is: forming a mask, opening a window, and ion-implant phosphorus element, the implantation dose is 3E15 /cm ² , and the implantation energy is 45KeV to form an N-type doped region;

(9) Form an oxide layer on the P-epitaxial layer, form a contact hole in the oxide layer corresponding to each N-type doped region, and deposit a front electrode in each contact hole and on the surface of the oxide layer, as shown in the figure As shown in 9, the specific process is: the oxide layer is a silicon dioxide layer, the thickness of the oxide layer is 200-500 nanometers, the front electrode is an aluminum-silicon-copper electrode, and the thickness of the front electrode is 1-4 microns;

(10) Form a passivation layer on the surface of the front electrode, and form a hole in the passivation layer as a back-end packaging wire, as shown in Figure 10. The specific process is: deposit 1-3 micron thick on the surface of the front electrode PSG (phosphosilicate glass) and 1-3 micron thick Si ₃ N ₄ as passivation layer;

(11) Thinning the N+ substrate, and then preparing a back electrode on the back of the N+ substrate, as shown in Figure 11, the specific process is: the N+ substrate is thinned to 250 microns, and the evaporation process Make the back gold and form the back electrode to complete the production of two bidirectional TVS diodes.

The present invention also proposes a two-way bidirectional TVS diode, as shown in FIG. 11 , the two-way bidirectional TVS diode is prepared according to the manufacturing method of the above-mentioned two-way bidirectional TVS diode.

Example 1

As shown in Figure 1-11, a method of manufacturing a two-way bidirectional TVS diode includes the following steps:

(1) Provide an N+ substrate, as shown in Figure 1, the N+ substrate has a <111> crystal orientation, is doped with As, has a resistivity of 0.007Ohm.cm, and a thickness of 675 microns;

(2) A silicon dioxide layer and a silicon nitride layer are sequentially grown on both sides of the N+ substrate respectively, as shown in FIG. 2 , the thickness of the silicon dioxide layer is 1 micron, and the silicon nitride layer is The thickness is 1 micron;

(3) removing the silicon dioxide layer and silicon nitride layer on the front side of the N+ substrate, and retaining the silicon dioxide layer and silicon nitride layer on the back side of the N+ substrate as the back seal layer, as shown in FIG. 3 , Specifically, firstly, the silicon nitride layer on the front side of the N+ substrate is removed by plasma etching, and then the silicon dioxide layer on the front side of the N+ substrate is removed by a mixed reagent of hydrofluoric acid and ammonium fluoride;

(4) A P- epitaxial layer is grown on the front side of the N+ substrate, and then the silicon dioxide layer and the silicon nitride layer on the back side of the N+ substrate are removed by wet etching, as shown in FIG. 4 , the P- epitaxial layer The thickness of the layer is 6 microns, and the resistivity of the P-epitaxial layer is 100 Ohm.cm. The P-epitaxial layer is protected by photoresist, and the etching solution for wet etching is hydrofluoric acid, that is, hydrogen Fluoric acid will float all the SiO ₂ and Si ₃ N ₄ on the back;

(5) Use a mask to perform boron doping in the P- epitaxial layer to form two P wells arranged side by side, as shown in Figure 5, the specific process is: grow a 700 nm oxide layer, then apply glue, light Engraving, development, etching, openings in appropriate areas, ion-implanting boron elements in the openings, the implantation dose is 4E14 /cm ² , and the implantation energy is 70KeV;

(6) N-type isolation regions are formed by phosphorus doping at the edges of both sides of the P- epitaxial layer and between the two P wells, as shown in FIG. 6 , the specific process is: forming a mask, Open a window in the region, then put the N+ substrate into a furnace tube at 1000°C, inject PoCL3 gas for doping, form an N-type doped region in the P- epitaxy, and connect it to the N-type substrate to form an N-type quarantine area;

(7) Form a P-type doped region by ion-implanting boron in each P-well, as shown in Figure 7, the specific process is: forming a mask, opening a window in a suitable area of the P-well, and ion-implanting boron element, the implantation dose is 4E14 /cm ² , and the implantation energy is 160KeV to form a P-type doped region;

(8) In each P-type doped region, an N-type doped region is formed by ion-implanting phosphorus, as shown in FIG. 8 , the specific process is: forming a mask, opening a window, and ion-implant phosphorus element, the implantation dose is 3E15 /cm ² , and the implantation energy is 45KeV to form an N-type doped region;

(9) Form an oxide layer on the P-epitaxial layer, form a contact hole in the oxide layer corresponding to each N-type doped region, and deposit a front electrode in each contact hole and on the surface of the oxide layer, as shown in the figure As shown in 9, the specific process is: the oxide layer is a silicon dioxide layer, the thickness of the oxide layer is 300 nanometers, the front electrode is an aluminum silicon copper electrode, and the thickness of the front electrode is 2 microns;

(10) Form a passivation layer on the surface of the front electrode, and form a hole in the passivation layer as a back-end packaging wiring, as shown in Figure 10. The specific process is: deposit 1 micron thick PSG on the surface of the front electrode ( Phosphosilicate glass) and 1 micron thick Si ₃ N ₄ as a passivation layer;

(11) Thinning the N+ substrate, and then preparing a back electrode on the back of the N+ substrate, as shown in Figure 11, the specific process is: the N+ substrate is thinned to 250 microns, and the evaporation process Make the back gold and form the back electrode to complete the production of two bidirectional TVS diodes.

The present invention also proposes a two-way bidirectional TVS diode, as shown in FIG. 11 , the two-way bidirectional TVS diode is prepared according to the manufacturing method of the above-mentioned two-way bidirectional TVS diode.

The above description is a preferred embodiment of the present invention, and it should be pointed out that for those skilled in the art, without departing from the principle of the present invention, some improvements and modifications can also be made, and these improvements and modifications are also considered Be the protection scope of the present invention.

Claims (8)

1. a kind of production method of the two-way TVS diode of two-way, which comprises the following steps:

(1) N+ substrate is provided；

(2) silicon dioxide layer and silicon nitride layer are successively grown respectively in the tow sides of the N+ substrate；

(3) the positive silicon dioxide layer and silicon nitride layer for removing the N+ substrate, retain the titanium dioxide of the N+ substrate back Silicon layer and silicon nitride layer are as back sealing；

(4) in the one P- epitaxial layer of front growth of N+ substrate, then wet etching removes the silica of the N+ substrate back Layer and silicon nitride layer；

(5) it carries out boron doping in the P-epitaxial layer using exposure mask and forms two p-wells being set side by side；The step (5) Specifically comprises the processes of: the oxide layer of 700 nanometers of growth, then gluing, photoetching, development, corrosion are being opened in region openings appropriate Ion implanting boron element in mouthful, implantation dosage 4E14/cm², Implantation Energy 70KeV；

(6) N-type isolated area is formed by phosphorus doping between P- epitaxial layer both sides of the edge and described two p-wells；

(7) P-doped zone is formed by boron ion implantation in each p-well；

(8) N-doped zone is formed by ion implanting phosphorus in each P-doped zone, the junction depth of N-doped zone is mixed less than p-type Miscellaneous area, thus to obtain the structure for the NPN being made of n-type doping region, P-doped zone domain, p-well and N+ substrate；Wherein, p-well It is deep into N+ substrate interior；

(9) oxide layer is formed on the P- epitaxial layer, the position that each N-doped zone is corresponded in oxide layer forms contact Hole, in each contact hole and oxidation layer surface deposits to form front electrode；

(10) passivation layer is formed on front electrode surface, forms the hole as rear end packaging and routing in the passivation layer；

(11) the N+ substrate is thinned, then rear electrode is prepared at the back side of the N+ substrate, to complete the two-way TVS bis- of two-way The production of pole pipe.

2. the production method of the two-way TVS diode of two-way according to claim 1, which is characterized in that the step (1) In, the N+ substrate is<111>crystal orientation, mix As, resistivity 0.007Ohm.cm, 675 microns of thickness.

3. the production method of the two-way TVS diode of two-way according to claim 1, which is characterized in that the step (2) In, the silicon dioxide layer with a thickness of 1-3 microns, the silicon nitride layer with a thickness of 1-3 microns, it is first in the step (3) The positive silicon nitride layer of the N+ substrate is removed first with plasma etching, then utilizes the mixing of hydrofluoric acid and ammonium fluoride Reagent removes the positive silicon dioxide layer of the N+ substrate.

4. the production method of the two-way TVS diode of two-way according to claim 1, which is characterized in that the step (4) In, the P- epitaxial layer with a thickness of 3-6 microns, the resistivity of the P- epitaxial layer is 50-150Ohm.cm, utilizes photoresist The P- epitaxial layer is protected, the etching liquid of wet etching is hydrofluoric acid.

5. the production method of the two-way TVS diode of two-way according to claim 1, which is characterized in that the step (6) Specifically comprises the processes of: it forms exposure mask and then the N+ substrate is put into 1000 DEG C of boiler tube, be passed through in region windowing appropriate PoCl₃Gas is doped, and Yanzhong forms N-doped zone outside P-, is connect with N+ substrate, is formd N-type isolated area.

6. the production method of the two-way TVS diode of two-way according to claim 1, which is characterized in that the step (7) Specifically comprises the processes of: exposure mask is formed, in the Production Zones Suitable windowing of the p-well, and ion implanting boron element, implantation dosage are 4E14/cm², Implantation Energy 160KeV, formation P-doped zone；The step (8) specifically comprises the processes of: exposure mask is formed, in institute State the Production Zones Suitable windowing of P-doped zone, and ion implanting P elements, implantation dosage 3E15/cm², Implantation Energy is 45KeV forms N-doped zone.

7. the production method of the two-way TVS diode of two-way according to claim 1, which is characterized in that the step (9) Specifically comprises the processes of: oxide layer is silicon dioxide layer, oxide layer with a thickness of 200-500 nanometers, front electrode is aluminium copper silicon electrode, Front electrode with a thickness of 1-4 microns.

8. the production method of the two-way TVS diode of two-way according to claim 1, which is characterized in that the step (10) Specifically comprises the processes of: in front electrode surface deposition 1-3 microns of thick PSG and 1-3 microns of thick Si₃N₄As passivation layer, institute State step (11) specifically comprises the processes of: the N+ substrate thinning, by the technique production back gold of evaporation, forms back to 250 microns Face electrode.