CN105047694B - A kind of junction termination structures of horizontal high voltage power device - Google Patents

Abstract

The invention belongs to technical field of semiconductors, more particularly to a kind of junction termination structures of horizontal high voltage power device.The structure of the present invention, the inwall of N-type drift region 2 and the inwall of p type buried layer 9 extend to centre be connected with the inwall of N-type drift region 2 in direct junction termination structures and the inwall of p type buried layer 9 respectively in curvature junction termination structures, N-type drift region 2 and the inwall vertical direction of p type buried layer 9 all have ɑ degree angles in bearing of trend and direct junction termination structures, and ɑ degree angles are 45 degree；It so can effectively alleviate the curvature effect of junction electric field.The vertical direction of bearing of trend in junction, p type buried layer 9, apart from for 5 microns, improves charge unbalance problem beyond N-type drift region 2.Beneficial effects of the present invention are to improve the problem of straight line junction termination structures are with curvature junction termination structures connected component charge unbalance and junction electric field curvature effect, it is to avoid device punctures in advance, so that the breakdown voltage optimized.

Description

A Junction Termination Structure for Lateral High Voltage Power Devices

technical field

The invention belongs to the technical field of semiconductors, and in particular relates to a junction terminal structure of a lateral high-voltage power device.

Background technique

The development of high-voltage power integrated circuits is inseparable from the integration of lateral high-voltage power semiconductor devices. Lateral high-voltage power semiconductor devices are usually closed structures, including circular, racetrack and interdigitated structures. For the closed racetrack structure and interdigitated structure, there will be small curvature terminations in the curved part and the fingertip part, and the electric field lines are easy to concentrate at the small curvature radius, which will lead to early avalanche breakdown of the device at the small curvature radius , which poses new challenges to the layout structure of lateral high-voltage power devices.

The Chinese patent with the publication number ^CN102244092A discloses "a junction terminal structure of a lateral high-voltage power device, as shown in Fig. Extreme polysilicon 4, gate oxide layer 5, P-well region 6, source N ⁺ 7, source P ⁺ 8. The device structure is divided into two parts, including a straight junction termination structure and a curvature junction termination structure. In the straight junction termination structure , the P-well region 6 is connected to the N-type drift region 2. When a high voltage is applied to the drain, the PN junction metallurgical junction formed by the P-well region 6 and the N-type drift region 2 begins to deplete, and the lightly doped N-type The depletion region of the drift region 2 will mainly bear the withstand voltage, and the peak value of the electric field appears at the PN junction metallurgical junction formed by the P-well region 6 and the N-type drift region 2. The power lines of the PN junction curvature metallurgical junction formed by the heterogeneous N-type drift region 2 are highly concentrated, causing the problem of avalanche breakdown in advance. The patent adopts the curvature junction terminal structure as shown in Figure 1, and the highly doped P-well The region 6 is connected to the lightly doped P-type substrate 3, the lightly doped P-type substrate 3 is connected to the lightly doped N-type drift region 2, and the highly doped P-well region 6 is connected to the lightly doped N-type drift region 2. The distance is L _P. When high voltage is applied to the drain of the device, the lightly doped P-type substrate 3 connected to the lightly doped N-type drift region 2 in the curvature of the fingertip of the device source replaces the highly doped P-well region 6 and the The PN junction metallurgical junction formed by the lightly doped N-type drift region 2, the lightly doped P-type substrate 3 adds additional charges to the depletion region, which effectively reduces the high electric field due to the highly doped P-well region 6 peak, and introduces a new electric field peak with the N-type drift region 2. Since the P-type substrate 3 and the N-type drift region 2 are lightly doped, the electric field peak at the metallurgical junction is reduced under the same bias voltage condition. Due to the contact between the highly doped P-well region 6 of the device fingertip curvature and the lightly doped P-type substrate 3, the radius of the P-type curvature terminal is increased, the excessive concentration of electric field lines is alleviated, and the device is avoided in the source finger. The early breakdown of the tip curvature increases the breakdown voltage of the fingertip curvature of the device. At the same time, the junction termination structure proposed in this patent is also applied to the triple RESURF structure device. Figure 2 shows the N-type drift in the straight junction termination structure of the device Area 2 is a device cross-sectional schematic diagram of a triple RESURF structure; Fig. 3 is a device cross-sectional schematic diagram of a triple RESURF structure in an N-type drift region 2 in a device curvature junction terminal structure. However, this patent is under a triple RESURF structure device, and the linear junction terminal structure The terminal structure of the part connected to the curvature junction terminal structure is not optimized. In the connected part, due to the charge imbalance and the curvature effect of the electric field at the connection, the power device will break down early, so the device withstand voltage is not optimal.

Contents of the invention

What the present invention aims to solve is to propose a junction terminal structure of a lateral high-voltage power device, aiming at the defects of charge imbalance of traditional devices and electric field curvature effect at connections.

To achieve the above object, the present invention adopts the following technical solutions:

A junction termination structure of a lateral high-voltage power device, as shown in FIG. 4 , includes a straight junction termination structure and a curvature junction termination structure;

The linear junction terminal structure is the same as that of the active region of the lateral high-voltage power device, including the drain N ⁺ contact region 1, the N-type drift region 2, the P-type substrate 3, the gate polysilicon 4, the gate oxide layer 5, the P- Well region 6, source N ⁺ contact region 7, source P ⁺ contact region 8, P-type buried layer 9; P-well region 6 and N-type drift region 2 are located on the upper layer of P-type substrate 3, where P-well Region 6 is located in the middle, with N-type drift region 2 on both sides, and P-well region 6 is connected to N-type drift region 2; both sides of N-type drift region 2 away from P-well region 6 are drain N ⁺ contact regions 1 , the surface of the P-well region 6 has a source N ⁺ contact region 7 and a source P ⁺ contact region 8 connected to the metallized source, wherein the source P ⁺ contact region 8 is located in the middle, and the source N ⁺ contact region 7 Located on both sides of the source P ⁺ contact region 8; the P-type buried layer 9 is located in the N-type drift region 2, between the P-well region 6 and the N ⁺ contact region 1; the source N ⁺ contact region 7 is connected to the N-type drift region Above the surface of the P-well region 6 between the regions 2 is the gate oxide layer 5 , and above the surface of the gate oxide layer 5 is the gate polysilicon 4 .

The curvature junction termination structure includes a drain N ⁺ contact region 1, an N-type drift region 2, a P-type substrate 3, a gate polysilicon 4, a gate oxide layer 5, a P-well region 6, and a source P ⁺ contact region 8 , P-type buried layer 9; the gate oxide layer 5 is above the surface of the P-well region 6, and the gate polysilicon 4 is above the surface of the gate oxide layer 5; N ⁺ contact region 1 and N-type drift region 2 in the curvature junction termination structure , gate polysilicon 4, gate oxide layer 5 and P-type buried layer 9 are respectively connected with N ⁺ contact region 1, N-type drift region 2, gate polysilicon 4, gate oxide layer 5 and P-type buried layer in the linear junction termination structure 9 are connected and form a ring structure; wherein, the ring-shaped N ⁺ contact region 1 in the curvature junction termination structure surrounds the ring-shaped N-type drift region 2, and the ring-shaped N-type drift region 2 in the curvature junction termination structure has a ring-shaped gate polysilicon 4 and a ring Gate oxide layer 5; different from "the P-well region 6 in the linear junction termination structure is connected to the N-type drift region 2", the P-well region 6 in the curvature junction termination structure is not connected to the N-type drift region 2 and The mutual spacing is L _P , and the specific value range of L _P is between a few microns and tens of microns;

It is characterized in that the junction of the N-type drift region 2 in the curvature junction termination structure and the N-type drift region 2 in the linear junction termination structure is close to the side of the P-well region 6, and the N-type drift region 2 in the curvature junction termination structure is The end has a first slope, the first slope is connected to the P-well region 6, and the first slope has an angle of α degrees with the direction of the horizontal line of the device; in the curvature junction termination structure, the P-type buried layer 9 and the straight junction termination structure The junction of the P-type buried layer 9 is close to the side of the P-well region 6, and the end of the P-type buried layer 9 in the curvature junction terminal structure has a second slope, and the second slope is parallel to the first slope; The specific value range of is 30 degrees to 60 degrees; the distance between the first slope and the second slope is b, and the specific value range of b is 0 to 15 microns; the ring P in the curvature junction terminal structure The distance between the inner wall of the type buried layer 9 and the connection between the annular N-type drift region 2 and the P-type substrate 3 in the curvature junction termination structure is a.

In the general technical solution of the present invention, in the connecting part of the straight junction terminal structure and the curvature junction termination structure, the inner wall of the N-type drift region 2 in the curvature junction termination structure extends to the middle to connect with the inner wall of the N-type drift region 2 in the direct junction termination structure, extending The direction and the vertical direction of the inner wall of the N-type drift region 2 in the direct junction terminal structure have an included angle of α degrees, and the specific value range of the included angle of α degrees is 30 degrees to 60 degrees; the inner wall of the P-type buried layer 9 in the curvature junction terminal structure Extending to the middle to connect with the inner wall of the P-type buried layer 9 in the direct junction terminal structure, the extension direction has an included angle of ɑ degrees with the vertical direction of the inner wall of the P-type buried layer 9 in the direct junction terminal structure, and the specific value range of the included angle of ɑ degrees is 30 degrees to 60 degrees; compared with the traditional structure, connecting the straight junction terminal structure and the curvature junction terminal structure at an angle of ɑ degrees at the connection can effectively alleviate the curvature effect of the electric field at the connection. In the direction perpendicular to the extending direction of the connection, there is a distance b between the P-type buried layer 9 and the N-type drift region 2, and the specific value of b is in the range of 0-15 microns. In the actual process, the N-type drift region 2 is formed by ion implantation. After annealing pushes the junction, the N-type drift region 2 will diffuse outward, and the P-type buried layer 9 will exceed the N-type drift region 2 by some distance, so that the diffused The N-type drift region 2 is depleted with P-type impurities. In this way, the problem of charge imbalance can be improved at the connecting portion of the straight junction terminal structure and the curvature junction terminal structure, thereby obtaining an optimized breakdown voltage. In the above scheme, it should be understood that the outer wall of the P-type buried layer 9 in the linear junction termination structure and the P-type buried layer 9 in the curvature junction termination structure refers to a part of the P-type buried layer 9 close to the N+ contact region 1 in the entire device. The side and the inner wall refer to the side of the P-type buried layer 9 close to the P-type substrate 3 in the entire device; the outer and inner walls of other parts have this meaning.

Further, the outer wall of the P-type buried layer 9 in the curvature junction termination structure and the outer wall of the P-type buried layer 9 in the linear junction termination structure are located in the N-type drift region 2, and the ring-shaped P-type buried layer 9 in the curvature junction termination structure The distance between the inner wall and the joint between the annular N-type drift region 2 and the P-type substrate 3 in the curvature junction terminal structure is a, and the specific value of a ranges from 0 to 15 microns.

Further, the inner wall of the P-type buried layer 9 in the linear junction termination structure is located in the N-type drift region 2 in the curvature junction termination structure.

Further, the inner wall of the P-type buried layer 9 in the linear junction termination structure is located in the P-type substrate 3 in the curvature junction termination structure.

Further, the second slope is located in the N-type drift region 2 in the curvature junction termination structure.

Further, the second slope is located in the P-type substrate 3 in the curvature junction terminal structure.

The beneficial effect of the present invention is that, by analyzing and optimizing the terminal structure of the connecting part of the linear junction terminal structure and the curvature junction terminal structure, the present invention improves the problem of charge imbalance and the electric field curvature Effect, to avoid premature breakdown of the device, so as to obtain the optimal breakdown voltage.

Description of drawings

FIG. 1 is a schematic diagram of a junction terminal structure of a conventional lateral high-voltage power semiconductor device;

FIG. 2 is a schematic cross-sectional view of a device in which the N-type drift region 2 is a triple RESURF structure in a conventional straight-line junction terminal structure;

3 is a schematic cross-sectional view of a device in which the N-type drift region 2 is a triple RESURF structure in a traditional device curvature junction terminal structure;

4 is a schematic diagram of a junction terminal structure of a lateral high-voltage power device of the present invention;

Fig. 5 is the structural representation of embodiment 1;

Fig. 6 is the structural representation of embodiment 2;

Fig. 7 is the structural representation of embodiment 3;

FIG. 8 is a schematic structural diagram of Embodiment 4.

detailed description

Below in conjunction with accompanying drawing and embodiment, describe technical solution of the present invention in detail:

Example 1:

As shown in Figure 5, the structure of this example includes a straight line knot terminal structure and a curvature knot terminal structure;

The linear junction terminal structure is the same as that of the active region of the lateral high-voltage power device, including the drain N ⁺ contact region 1, the N-type drift region 2, the P-type substrate 3, the gate polysilicon 4, the gate oxide layer 5, the P- Well region 6, source N ⁺ contact region 7, source P ⁺ contact region 8, P-type buried layer 9; P-well region 6 and N-type drift region 2 are located on the upper layer of P-type substrate 3, where P-well Region 6 is located in the middle, with N-type drift region 2 on both sides, and P-well region 6 is connected to N-type drift region 2; both sides of N-type drift region 2 away from P-well region 6 are drain N ⁺ contact regions 1 , the surface of the P-well region 6 has a source N ⁺ contact region 7 and a source P ⁺ contact region 8 connected to the metallized source, wherein the source P ⁺ contact region 8 is located in the middle, and the source N ⁺ contact region 7 Located on both sides of the source P ⁺ contact region 8; the P-type buried layer 9 is located in the N-type drift region 2, between the P-well region 6 and the N ⁺ contact region 1; the source N ⁺ contact region 7 is connected to the N-type drift region Above the surface of the P-well region 6 between the regions 2 is the gate oxide layer 5 , and above the surface of the gate oxide layer 5 is the gate polysilicon 4 .

The curvature junction termination structure includes a drain N ⁺ contact region 1, an N-type drift region 2, a P-type substrate 3, a gate polysilicon 4, a gate oxide layer 5, a P-well region 6, and a source P ⁺ contact region 8 , P-type buried layer 9; the gate oxide layer 5 is above the surface of the P-well region 6, and the gate polysilicon 4 is above the surface of the gate oxide layer 5; N ⁺ contact region 1 and N-type drift region 2 in the curvature junction termination structure , gate polysilicon 4, gate oxide layer 5 and P-type buried layer 9 are respectively connected with N ⁺ contact region 1, N-type drift region 2, gate polysilicon 4, gate oxide layer 5 and P-type buried layer in the linear junction termination structure 9 are connected and form a ring structure; wherein, the ring-shaped N ⁺ contact region 1 in the curvature junction termination structure surrounds the ring-shaped N-type drift region 2, and the ring-shaped N-type drift region 2 in the curvature junction termination structure has a ring-shaped gate polysilicon 4 and a ring Gate oxide layer 5; different from "the P-well region 6 in the linear junction termination structure is connected to the N-type drift region 2", the P-well region 6 in the curvature junction termination structure is not connected to the N-type drift region 2 and The mutual spacing is L _P , and the specific value range of L _P is between a few microns and tens of microns;

The inner wall of the N-type drift region 2 in the curvature junction termination structure extends to the middle to connect with the inner wall of the N-type drift region 2 in the direct junction termination structure, and the extension direction has a degree to the vertical direction of the inner wall of the N-type drift region 2 in the direct junction termination structure. The included angle is 45 degrees; the inner wall of the P-type buried layer 9 in the curvature junction terminal structure extends to the middle to connect with the inner wall of the P-type buried layer 9 in the direct junction termination structure, and the extension direction is the same as that in the direct junction termination structure. The vertical direction of the inner wall of the P-type buried layer 9 has an included angle of ɑ degrees, and the included angle of ɑ degrees is 45 degrees; the connection between the P-type buried layer 9 in the linear junction terminal structure and the P-type buried layer 9 in the curvature junction terminal structure is located at P In the substrate 3, the junction of the P-type buried layer 9 in the straight-line junction termination structure and the P-type buried layer 9 in the curvature junction termination structure and the N-type drift region 2 in the direct junction termination structure and the N-type drift in the curvature junction termination structure The distance between the junctions of the regions 2 is b, and b is 5 microns; the inner wall of the ring-shaped P-type buried layer 9 in the curvature junction termination structure is located in the N-type drift region 2, and the ring-shaped P-type buried layer in the curvature junction termination structure The distance between the inner wall of 9 and the connection between the annular N-type drift region 2 and the P-type substrate 3 in the curvature junction termination structure is a, and a is 5 microns.

The working principle of this example is: the inner wall of the N-type drift region 2 in the curvature junction termination structure extends to the middle to connect with the inner wall of the N-type drift region 2 in the direct junction termination structure, and the extension direction is the same as the inner wall of the N-type drift region 2 in the direct junction termination structure The vertical direction has an included angle of α degree, and the included angle of α degree is 45 degrees; the inner wall of the P-type buried layer 9 in the curvature junction terminal structure extends to the middle to connect with the inner wall of the P-type buried layer 9 in the direct junction terminal structure, and the extension direction is the same as In the direct junction terminal structure, the vertical direction of the inner wall of the P-type buried layer 9 has an included angle of ɑ degrees, and the included angle of ɑ degrees is 45 degrees; thus, compared with the traditional structure, the straight junction terminal structure and the curvature junction terminal are connected at an angle of 45 degrees at the junction The structure can effectively alleviate the curvature effect of the electric field at the junction. In the connecting portion of the linear junction terminal structure and the curvature junction terminal structure, the distance between the P-type buried layer 9 and the N-type drift region 2 is 5 microns in the vertical direction to the extending direction of the connection. In the actual process, the N-type drift region 2 is formed by ion implantation. After annealing pushes the junction, the N-type drift region 2 will diffuse, and the P-type buried layer 9 will exceed the N-type drift region 2 by some distance, so that the diffused N-type The drift region 2 is depleted with P-type impurities. In this way, the problem of charge imbalance and the curvature effect of the electric field at the connection is improved in the connecting portion of the straight junction termination structure and the curvature junction termination structure, thereby obtaining a more optimized breakdown voltage.

Example 2

As shown in FIG. 6 , this example differs from Example 1 in that the inner wall of the ring-shaped P-type buried layer 9 in the curvature junction termination structure is located in the P-type substrate 3 , and the principle is the same as that of Example 1.

Example 3

As shown in Figure 7, the difference between this example and Example 2 is that in this example, the junction of the P-type buried layer 9 in the linear junction termination structure and the P-type buried layer 9 in the curvature junction termination structure is located in the N-type drift region 2 , its principle is the same as that of Embodiment 2.

Example 4

As shown in Figure 8, the difference between this example and Example 1 is that in this example, the junction of the P-type buried layer 9 in the linear junction termination structure and the P-type buried layer 9 in the curvature junction termination structure is located in the N-type drift region 2 , its principle is the same as in Example 1.

Claims (6)

1. a kind of junction termination structures of horizontal high voltage power device, including straight line junction termination structures and curvature junction termination structures；

The straight line junction termination structures are identical with horizontal high voltage power device active area structure, including drain electrode N⁺Contact zone (1), N-type Drift region (2), P type substrate (3), grid polycrystalline silicon (4), gate oxide (5), P-well areas (6), source electrode N⁺Contact zone (7), source Pole P⁺Contact zone (8), p type buried layer (9)；P-well areas (6) are located at the upper strata of P type substrate (3), wherein P- with N-type drift region (2) Well areas (6) are located at centre, and both sides are N-type drift region (2), and P-well areas (6) are connected with N-type drift region (2)；N-type is drifted about The both sides away from P-well areas (6) are drain electrode N in area (2)⁺Contact zone (1), the surface of P-well areas (6) has and metallization source Extremely connected source electrode N⁺Contact zone (7) and source electrode P⁺Contact zone (8), wherein source electrode P⁺Contact zone (8) is located at centre, source electrode N⁺Connect Touch area (7) and be located at source electrode P⁺Contact zone (8) both sides；P type buried layer (9) is located in N-type drift region (2), in P-well areas (6) and N⁺ Between contact zone (1)；Source electrode N⁺It is grid oxygen above P-well areas (6) surface between contact zone (7) and N-type drift region (2) It is grid polycrystalline silicon (4) to change above layer (5), the surface of gate oxide (5)；

The curvature junction termination structures include drain electrode N⁺Contact zone (1), N-type drift region (2), P type substrate (3), grid polycrystalline silicon (4), gate oxide (5), P-well areas (6), source electrode P⁺Contact zone (8), p type buried layer (9)；P-well areas (6) surface is Gate oxide (5), the surface of gate oxide (5) is grid polycrystalline silicon (4)；N in curvature junction termination structures⁺Contact zone (1), N-type drift region (2), grid polycrystalline silicon (4), gate oxide (5) and p type buried layer (9) respectively with straight line junction termination structures N⁺Contact zone (1), N-type drift region (2), grid polycrystalline silicon (4), gate oxide (5) are connected with p type buried layer (9) and form ring Shape structure；Wherein, the annular N in curvature junction termination structures⁺Contact zone (1) surrounds annular N-type drift region (2), curvature knot terminal There are annular grid polysilicon (4) and annular gate oxide (5) in annular N-type drift region (2) in structure；With " straight line knot terminal P-well areas (6) in structure are connected from N-type drift region (2) " unlike, the P-well areas (6) in curvature junction termination structures It is not attached to N-type drift region (2) and each other away from for L_P, L_PSpecific span at a few micrometers between some tens of pm；

Characterized in that, N-type drift region (2) in N-type drift region (2) and straight line junction termination structures in the curvature junction termination structures The end of junction N-type drift region (2) in the side of P-well areas (6), curvature junction termination structures has the first inclined-plane, institute State the first inclined-plane to be connected with P-well areas (6), the first inclined-plane has ɑ degree angles with device crossline direction；The curvature knot terminal In structure in p type buried layer (9) and straight line junction termination structures p type buried layer (9) junction close to the side of P-well areas (6), curvature The end of p type buried layer (9) has the second inclined-plane in junction termination structures, and second inclined-plane is parallel with the first inclined-plane；ɑ degree angles Specific span is 30 degree to 60 degree；Spacing between first inclined-plane and the second inclined-plane is b, b specific span For 0 to 15 microns；The inwall of ring-shaped P type buried regions (9) in the curvature junction termination structures and the ring in curvature junction termination structures The spacing of the junction of shape N-type drift region (2) and P type substrate (3) is a.

2. a kind of junction termination structures of horizontal high voltage power device according to claim 1, it is characterised in that the curvature P type buried layer (9) outer wall is located in N-type drift region (2) with p type buried layer (9) outer wall in straight line junction termination structures in junction termination structures, The inwall of ring-shaped P type buried regions (9) in the curvature junction termination structures and the annular N-type drift region in curvature junction termination structures (2) and the spacing of junction of P type substrate (3) is a, a specific span is 0 to 15 microns.

3. a kind of junction termination structures of horizontal high voltage power device according to claim 2, it is characterised in that the straight line The inwall of p type buried layer (9) is located in the N-type drift region (2) in curvature junction termination structures in junction termination structures.

4. a kind of junction termination structures of horizontal high voltage power device according to claim 2, it is characterised in that the straight line The inwall of p type buried layer (9) is located in the P type substrate (3) in curvature junction termination structures in junction termination structures.

5. the junction termination structures of a kind of horizontal high voltage power device according to claim 3 or 4, it is characterised in that described Second inclined-plane is located in the N-type drift region (2) in curvature junction termination structures.

6. the junction termination structures of a kind of horizontal high voltage power device according to claim 3 or 4, it is characterised in that described Second inclined-plane is located in the P type substrate (3) in curvature junction termination structures.