阅读说明：本技术 体内异性掺杂的功率半导体器件及其制造方法 (Power semiconductor device with internal anisotropic doping and manufacturing method thereof ) 是由 章文通 吴旸 唐宁 乔明 李肇基 张波 于 2021-08-19 设计创作，主要内容包括：本发明提供一种体内异性掺杂的功率半导体器件及其制造方法,包括第一介质氧化层和浮空场板多晶硅电极构成纵向浮空场板,分布在整个第二导电类型漂移区中,形成纵向浮空等势场板阵列,槽壁周围附有第一导电类型杂质；由于硅的介电系数是二氧化硅的三倍,在相同漂移区长度下,介质层能够取得更大的电场,提高击穿电压。槽壁用第一导电类型杂质包围住,由于MIS结构带来的辅助耗尽作用,大大提高了第二导电类型漂移区的浓度,降低比导通电阻。(The invention provides an in-vivo heterosexual doped power semiconductor device and a manufacturing method thereof, wherein a longitudinal floating field plate is formed by a first dielectric oxide layer and a floating field plate polycrystalline silicon electrode and distributed in a whole second conductive type drift region to form a longitudinal floating equipotential field plate array, and first conductive type impurities are attached to the periphery of the wall of a groove; because the dielectric coefficient of silicon is three times of that of silicon dioxide, under the same drift region length, the dielectric layer can obtain a larger electric field, and the breakdown voltage is improved. The groove wall is surrounded by the first conductive type impurities, and due to the auxiliary depletion effect brought by the MIS structure, the concentration of the second conductive type drift region is greatly improved, and the specific on-resistance is reduced.)

1. An in-vivo heterodoped power semiconductor device, comprising:

the transistor comprises a first conduction type semiconductor substrate (11), a first conduction type well region (12), a first conduction type source end heavily doped region (13), a second conduction type drift region (21), a second conduction type well region (22), a second conduction type source end heavily doped region (23), a second conduction type drain end heavily doped region (24), a first dielectric oxide layer (31), a second dielectric oxide layer (32), a third dielectric oxide layer (33), a polycrystalline silicon electrode (41) and a control gate polycrystalline silicon electrode (42);

the second conduction type drift region (21) is positioned above the first conduction type semiconductor substrate (11), the second conduction type well region (22) is positioned on the right side of the second conduction type drift region (21), the first conduction type well region (12) is positioned on the left side of the second conduction type drift region (21), the first conduction type source end heavily doped region (13) and the second conduction type source end heavily doped region (23) are positioned in the first conduction type well region (12), and the second conduction type drain end heavily doped region (24) is positioned in the first conduction type well region (22); the second dielectric oxide layer (32) is positioned above the first conductive type well region (12), the left end of the second dielectric oxide layer is contacted with the second conductive type source end heavily doped region (23), and the right end of the second dielectric oxide layer is contacted with the second conductive type drift region (21); the third dielectric oxide layer (33) is positioned on the upper surface of the second conduction type drift region (21) between the second dielectric oxide layer (32) and the second conduction type drain terminal heavily doped region (24); the control gate polysilicon electrode (42) covers the upper surface of the second dielectric oxide layer (32) and partially extends to the upper surface of the third dielectric oxide layer (33);

the first dielectric oxide layer (31) and the polycrystalline silicon electrode (41) form a longitudinally extending longitudinal floating field plate, and the number of the longitudinal floating field plates is 1 to multiple; the longitudinal floating field plates are periodically distributed in the whole second conductive type drift region (21) to form a voltage-resistant layer with a plurality of equipotential floating grooves, and the periphery of each equipotential floating groove covers the first conductive type drift region (15); the longitudinal distance and the transverse distance of adjacent longitudinal floating field plates distributed in the whole second conduction type drift region (21) are equal, the transverse direction is a source-drain direction, and the longitudinal direction is perpendicular to the source-drain direction.

2. An in-vivo heterodoped power semiconductor device according to claim 1, characterized in that: the depth of the second conductive type semiconductor (21) is larger than that of the longitudinal floating field plate, and a section of space is reserved between the bottom end of the longitudinal floating field plate and the first conductive type semiconductor substrate (11) to form a conductive path at the bottom.

3. An in-vivo heterodoped power semiconductor device according to claim 1, characterized in that: the cross section of the longitudinal floating field plate is rectangular, circular, elliptical or hexagonal.

4. An in-vivo heterodoped power semiconductor device according to claim 1, characterized in that: a first conductivity type electric field clamp layer (14), i.e., a Ptop layer, is introduced inside the second conductivity type drift region (21).

5. An in-vivo heterodoped power semiconductor device according to claim 1, characterized in that: the bottom of the longitudinal floating field plate penetrates through the groove bottom to be implanted to form a second conduction type buried layer (25).

6. An in-vivo heterodoped power semiconductor device according to claim 1, characterized in that: the device is an SOI device.

7. A method of manufacturing an in-vivo anisotropically doped power semiconductor device according to claim 1, characterized by the steps of:

step 1: selecting a first conductivity type semiconductor substrate (11);

step 2: injecting a push junction above the first conductive type substrate (11) to obtain a second conductive type drift region (21);

and step 3: determining the depth and the distance between the grooves, and forming the grooves by photoetching and etching;

and 4, step 4: forming a first conductive type polycrystal on the groove wall, oxidizing to form a first dielectric oxide layer, attaching a first conductive type drift region (15) to the outer side of the groove wall, depositing polycrystal and etching to a silicon plane;

and 5: forming a second conductivity type well region (22) by ion-implanting second conductivity type impurities and junction-pushing;

step 6: forming a second dielectric oxide layer (32) by thermal oxidation, and forming a third dielectric oxide layer (33) by deposition and etching;

and 7: forming a first conductivity type well region (12) by ion implantation of first conductivity type impurities and junction push;

and 8: depositing and etching polysilicon to form a control gate polysilicon electrode (42);

and step 9: and (3) forming a first conduction type source end heavily doped region (13), a second conduction type source end heavily doped region (23) and a second conduction type drain end heavily doped region (24) by injection activation.

8. The method of claim 7, wherein: and 4, oxidizing the first conductive type polycrystal to form a medium so as to form an oxide layer and control the thickness of the oxide layer.

9. The method of claim 7, wherein: and 2, the second conductive type drift region (21) formed by implantation and junction pushing in the step 2 is obtained by an epitaxial method.

10. Use of a method of manufacturing an in vivo anisotropically doped power semiconductor device according to claims 7 to 9 for the preparation of SiC, GaN wide bandgap semiconductors.

Technical Field

The invention belongs to the field of power semiconductors, and mainly provides an in-vivo heterosexual doped power semiconductor device and a manufacturing method thereof.

Background

The power semiconductor device has the characteristics of high input impedance, high switching speed, low loss, wide safe working area and the like, and is widely applied to computers, peripheral equipment, consumer electronics, network communication, electronic special equipment, automobile electronics, instruments and meters, LED display screens, electronic lighting and other aspects. The source electrode, the grid electrode and the drain electrode of the transverse device are on the same surface, so that the transverse device is easy to integrate with other devices and circuits through internal connection, and is widely applied to power integrated circuits. In the design of the lateral device, the device is required to have high breakdown voltage and low specific on-resistance. A higher breakdown voltage requires a longer drift region length and a lower drift region doping concentration for the device, but this also results in an increased specific on-resistance of the device. The proposed resurfr device alleviates this contradiction, but the resurfr device can achieve high withstand voltage depending on strict charge balance.

In order to alleviate the contradiction between the breakdown voltage and the specific on-resistance, researchers have proposed a device with a longitudinal floating field plate and a manufacturing method thereof (CN 201910819933.6). Meanwhile, when the device is in an on state, an accumulation layer can be formed on the surface of the floating field plate, the specific on-resistance is reduced, and the saturation current is improved. However, since the depletion continuity is not easily maintained between the trenches, when the concentration of the drift region is increased, the drain end electric field is easily decreased, and the breakdown voltage is easily lowered. The introduction of Ptop brings double-charge self-balance, reduces specific on-resistance and ensures high tolerance. The invention provides an in-vivo heterosexual doped power semiconductor device and a manufacturing method thereof. The groove wall is surrounded by the first conductive type impurities, and due to the auxiliary depletion effect brought by the MIS structure, the concentration of the second conductive type drift region is greatly improved, and the specific on-resistance is reduced.

Disclosure of Invention

The invention introduces a longitudinal equipotential floating field plate array connected with a dielectric layer in a drift region, and provides a new structure of a low-resistance device with equipotential floating grooves, wherein a first conductive type semiconductor is attached to the groove walls, and the structure enables the device to obtain a larger average electric field, improves the withstand voltage and reduces the specific conductance.

In order to achieve the purpose, the technical scheme of the invention is as follows:

an in-vivo heterodoped power semiconductor device, comprising:

a first conductive type semiconductor substrate 11, a first conductive type well region 12, a first conductive type source end heavily doped region 13, a second conductive type drift region 21, a second conductive type well region 22, a second conductive type source end heavily doped region 23, a second conductive type drain end heavily doped region 24, a first dielectric oxide layer 31, a second dielectric oxide layer 32, a third dielectric oxide layer 33, a polysilicon electrode 41 and a control gate polysilicon electrode 42;

wherein, the second conductive type drift region 21 is located above the first conductive type semiconductor substrate 11, the second conductive type well region 22 is located on the right side of the second conductive type drift region 21, the first conductive type well region 12 is located on the left side of the second conductive type drift region 21, the first conductive type source end heavily doped region 13 and the second conductive type source end heavily doped region 23 are located in the first conductive type well region 12, and the second conductive type drain end heavily doped region 24 is located in the first conductive type well region 22; the second dielectric oxide layer 32 is located above the first conductive type well region 12, and the left end of the second dielectric oxide layer is in contact with the second conductive type source heavily doped region 23, and the right end of the second dielectric oxide layer is in contact with the second conductive type drift region 21; the third dielectric oxide layer 33 is positioned on the upper surface of the second conductive type drift region 21 between the second dielectric oxide layer 32 and the second conductive type drain heavily doped region 24; the control gate polysilicon electrode 42 covers the upper surface of the second dielectric oxide layer 32 and partially extends to the upper surface of the third dielectric oxide layer 33;

the first dielectric oxide layer 31 and the polysilicon electrode 41 form a longitudinally extending longitudinal floating field plate, and the number of the longitudinal floating field plates is 1 to a plurality; the longitudinal floating field plates are periodically distributed in the whole second conductive type drift region 21 to form a voltage-resistant layer with a plurality of equipotential floating grooves, and the periphery of each equipotential floating groove is covered with the first conductive type drift region 15; the longitudinal distance and the transverse distance of adjacent longitudinal floating field plates distributed in the whole second conductivity type drift region 21 are equal, the transverse direction is the source-drain direction, and the longitudinal direction is perpendicular to the source-drain direction.

Preferably, the depth of the second conductivity type semiconductor 21 is greater than that of the longitudinal floating field plate, and a gap is left between the bottom end of the longitudinal floating field plate and the first conductivity type semiconductor substrate 11 to form a bottom conductive path.

Preferably, the cross-sectional shape of the longitudinal floating field plate is rectangular, circular, elliptical or hexagonal.

Preferably, the first conductivity type electric field clamp layer 14, i.e., the Ptop layer, is introduced inside the second conductivity type drift region 21.

Preferably, the bottom of the vertical floating field plate is implanted through the bottom of the trench to form a buried layer 25 of the second conductivity type.

Preferably, the device is an SOI device.

The invention also provides a manufacturing method of the in-vivo heterodoping power semiconductor device, which comprises the following steps:

step 1: selecting a first conductivity type semiconductor substrate 11;

step 2: injecting a push junction above the first conductive type substrate 11 to obtain a second conductive type drift region 21;

and step 3: determining the depth and the distance between the grooves, and forming the grooves by photoetching and etching;

and 4, step 4: forming first conductive type polycrystal on the groove wall, oxidizing to form a first dielectric oxide layer, attaching the first conductive type drift region 15 to the outer side of the groove wall, depositing polycrystal and etching to a silicon plane;

and 5: forming a second conductive type well region 22 by ion-implanting second conductive type impurities and junction-pushing;

step 6: forming a second dielectric oxide layer 32 by thermal oxidation, and depositing and etching to form a third dielectric oxide layer 33;

and 7: forming a first conductive type well region 12 by ion-implanting first conductive type impurities and junction-pushing;

and 8: depositing and etching polysilicon to form a control gate polysilicon electrode 42;

and step 9: the implantation activation forms a first conductive type source end heavily doped region 13, a second conductive type source end heavily doped region 23 and a second conductive type drain end heavily doped region 24.

Preferably, in step 4, the first conductivity type poly is oxidized after the dielectric is formed, thereby forming an oxide layer to control the thickness of the oxide layer.

Preferably, the second conductivity type drift region 21 formed by implantation and junction push-off in step 2 is obtained by an epitaxial method.

Preferably, in step 4, the first conductivity type poly may be a thin poly, and the thin poly is oxidized after oxidizing the forming medium to form an oxide layer, so as to control the thickness of the oxide layer.

Preferably, the first conductivity type well region 12 and the second conductivity type well region 22 obtained by implanting and pulling the junction in step 6 are formed by implanting and activating a plurality of times with different energies.

Preferably, the deep trench in step 3 is determined by the thickness of the drift region to ensure full depletion.

The invention also provides an application of the manufacturing method of the in-vivo heterodoping power semiconductor device in preparing SiC and GaN wide bandgap semiconductors.

The invention has the beneficial effects that: the longitudinal floating field plate structure formed by the dielectric layers formed by the first dielectric oxide layer 31 and the polysilicon electrode 41 is introduced into the second conductive type drift region 21 of the device, and because the dielectric coefficient of silicon is three times that of silicon dioxide, the dielectric layers can obtain a larger electric field under the same drift region length, and the breakdown voltage is improved. The groove wall is surrounded by the first conductive type impurities, and due to the auxiliary depletion effect brought by the MIS structure, the concentration of the second conductive type drift region is greatly improved, and the specific on-resistance is reduced.

Drawings

Fig. 1 is a schematic structural diagram of a shimming device with an electric field clamping layer in embodiment 1;

fig. 2 is a schematic structural diagram of a shimming device with an electric field clamping layer in embodiment 2;

fig. 3 is a schematic structural diagram of a shimming device with an electric field clamping layer in embodiment 3;

fig. 4 is a schematic structural diagram of a shimming device with an electric field clamping layer in embodiment 4;

5(a) -5 (k) are schematic process flow diagrams of the device described in example 1;

the vertical field plate is characterized in that the vertical field plate is a vertical field plate, 11 is a vertical field plate, and the vertical field plate is a vertical plate, and the vertical plate is a vertical plate, and the vertical plate is a vertical plate, and a vertical plate, 11 is a vertical plate, and a vertical plate, and a vertical plate, 11 is a vertical plate, and a plate, 11 is provided, and a vertical plate, and a vertical plate, a vertical plate, a semiconductor plate, a plate, and a vertical plate, and a vertical plate, a plate, and a plate, a vertical plate, a plate, 11 is provided, and a plate, and a semiconductor plate, and a plate, and a plate, 11 is provided, and a plate, a plate.

Detailed Description

The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention.

Example 1

An in-vivo hetero-doped power semiconductor device described in embodiment 1, as shown in fig. 1, specifically includes:

a first conductive type semiconductor substrate 11, a first conductive type well region 12, a first conductive type source end heavily doped region 13, a second conductive type drift region 21, a second conductive type well region 22, a second conductive type source end heavily doped region 23, a second conductive type drain end heavily doped region 24, a first dielectric oxide layer 31, a second dielectric oxide layer 32, a third dielectric oxide layer 33, a polysilicon electrode 41 and a control gate polysilicon electrode 42;

wherein, the second conductive type drift region 21 is located above the first conductive type semiconductor substrate 11, the second conductive type well region 22 is located on the right side of the second conductive type drift region 21, the first conductive type well region 12 is located on the left side of the second conductive type drift region 21, the first conductive type source end heavily doped region 13 and the second conductive type source end heavily doped region 23 are located in the first conductive type well region 12, and the second conductive type drain end heavily doped region 24 is located in the first conductive type well region 22; the second dielectric oxide layer 32 is located above the first conductive type well region 12, and the left end of the second dielectric oxide layer is in contact with the second conductive type source heavily doped region 23, and the right end of the second dielectric oxide layer is in contact with the second conductive type drift region 21; the third dielectric oxide layer 33 is positioned on the upper surface of the second conductive type drift region 21 between the second dielectric oxide layer 32 and the second conductive type drain heavily doped region 24; the control gate polysilicon electrode 42 covers the upper surface of the second dielectric oxide layer 32 and partially extends to the upper surface of the third dielectric oxide layer 33;

the first dielectric oxide layer 31 and the polysilicon electrode 41 form a longitudinally extending longitudinal floating field plate, and the number of the longitudinal floating field plates is 1 to a plurality; the longitudinal floating field plates are periodically distributed in the whole second conductive type drift region 21 to form a voltage-resistant layer with a plurality of equipotential floating grooves, and the periphery of each equipotential floating groove is covered with the first conductive type drift region 15; the longitudinal distance and the transverse distance of adjacent longitudinal floating field plates distributed in the whole second conductivity type drift region 21 are equal, the transverse direction is the source-drain direction, and the longitudinal direction is perpendicular to the source-drain direction.

The depth of the second conductive type semiconductor 21 is greater than that of the longitudinal floating field plate, and a gap is left between the bottom end of the longitudinal floating field plate and the first conductive type semiconductor substrate 11 to form a conductive path at the bottom.

The cross section of the longitudinal floating field plate is rectangular, circular, elliptical or hexagonal.

The basic working principle of the invention is as follows: taking the first conductive type semiconductor material as the P-type, the second conductive type drift region 21 and the first conductive type drift region under the condition of not applying the gate voltagePN junction formed by well region 12 under reverse voltage V_dDepletion is started by the action, and the PN junction formed by the first conductivity type semiconductor substrate 11 and the second conductivity type drift region 21 also starts depletion at the drain voltage. Meanwhile, the floating electrode in the longitudinal field plate has an auxiliary depletion effect on the drift region, so that the surface electric field is uniformly distributed, wherein most of the breakdown voltage is borne by the dielectric layer, and the dielectric coefficient of silicon dioxide is smaller than that of silicon, so that the withstand voltage of the device is greatly improved, and the breakdown voltage of the device is improved. When the gate bias voltage V_gWhen the threshold voltage is higher than the threshold voltage, inversion layer electrons appear on the surface of the first conductivity type well region 12 close to the second dielectric oxide layer 32, so that the source and drain are conducted.

As shown in fig. 5, the manufacturing method of embodiment 1 includes the following steps:

step 1: selecting a first conductivity type semiconductor substrate 11;

step 2: injecting a push junction above the first conductive type substrate 11 to obtain a second conductive type drift region 21;

and step 3: determining the depth and the distance between the grooves, and forming the grooves by photoetching and etching;

and 4, step 4: forming first conductive type polycrystal on the groove wall, oxidizing to form a first dielectric oxide layer, attaching the first conductive type drift region 15 to the outer side of the groove wall, depositing polycrystal and etching to a silicon plane;

and 5: forming a second conductive type well region 22 by ion-implanting second conductive type impurities and junction-pushing;

step 6: forming a second dielectric oxide layer 32 by thermal oxidation, and depositing and etching to form a third dielectric oxide layer 33;

and 7: forming a first conductive type well region 12 by ion-implanting first conductive type impurities and junction-pushing;

and 8: depositing and etching polysilicon to form a control gate polysilicon electrode 42;

and step 9: the implantation activation forms a first conductive type source end heavily doped region 13, a second conductive type source end heavily doped region 23 and a second conductive type drain end heavily doped region 24.

It should be noted that:

step 4, the first conductive type polycrystal can adopt a thin polycrystal, and the thin polycrystal is oxidized to form a medium and then oxidized to form an oxide layer so as to control the thickness of the oxide layer.

The second conductive type drift region 21 formed by injection and junction pushing in the step 2 is obtained by an epitaxial method;

the first conductivity type well region 12 and the second conductivity type well region 22 obtained by implantation and junction push in step 6 are formed by a plurality of implantations of different energies and activations.

In the step 3, the deep groove is determined by the thickness of the drift region so as to ensure full depletion;

the process is suitable for wide bandgap semiconductors such as SiC, GaN and the like and other types of semiconductors.

Example 2

As shown in fig. 2, a schematic structural diagram of an in-vivo hetero-doped power semiconductor device in embodiment 2 is shown, and this example is different from the structure in embodiment 1 in that a first conductivity type electric field clamp layer 14, i.e., a Ptop layer, is introduced inside a second conductivity type drift region 21. The introduction of Ptop brings double-charge self-balance, the MIS electrode is high-potential-assisted to deplete the P-type impurities, the low-potential-assisted to deplete the N-type impurities, and meanwhile, the P-type impurities and the N-type impurities can be mutually depleted, so that the concentration of a drift region can be greatly increased, and the specific on-resistance is reduced. Meanwhile, Ptop ensures the continuity of depletion and has the function of clamping a surface electric field, so that high breakdown voltage is kept in a very wide drift region concentration and high tolerance is realized. The same plate is adopted in the process as the first conductive type well region, the blocking effect of the field oxide layer is utilized, and high-energy injection is performed without additional plates.

Example 3

As shown in fig. 3, a schematic structural diagram of an in-vivo anisotropically doped power semiconductor device in embodiment 3 is shown, and this example is different from the structure in embodiment 1 in that a second conductive type buried layer 25 is formed by implanting the bottom of a vertical floating field plate through the bottom of a trench. In this example, the second conductive type buried layer 25 introduces a low-resistance conductive path at the bottom of the trench to further reduce the device resistance and increase the device current, and the operation principle is basically the same as that of embodiment 1.

Example 4

As shown in fig. 4, a schematic structural diagram of an in-vivo anisotropically-doped power semiconductor device in example 4 is shown, and this example is different from the structure in example 1 in that the device is an SOI device instead of a bulk silicon device, and floating field plates are uniformly distributed in a drift region 21 of a second conductivity type, and the operation principle is basically the same as that in example 1.