阅读说明：本技术 一种具有逆向导通能力的GaN RC-HEMT (GaN RC-HEMT with reverse conduction capability ) 是由 罗小蓉 张�成 廖德尊 邓思宇 杨可萌 魏杰 贾艳江 孙涛 郗路凡 于 2021-08-27 设计创作，主要内容包括：本发明属于半导体技术领域,涉及一种具有逆向导通能力的GaN RC-HEMT器件。本发明在传统MIS栅HEMT器件基础上引入电流阻挡层和多沟道导电通路,并且集成了反向续流肖特基管,降低了反向开启损耗。阻挡层形成2DHG阻断纵向电流通路,实现器件增强型。正向导通时栅极加高电位,栅极侧壁形成反型层使纵向沟道导通,漂移区的多沟道导电通路和栅极下方形成的电子积累层均降低了导通电阻；正向阻断时,阻挡层辅助耗尽漂移区调制电场,降低电场尖峰,此外多沟道区域形成的极化电场可以进一步提高漂移区耐压,有效缓解了导通电阻与耐压之间的矛盾关系；反向续流时集成肖特基管沿2DEG形成电流路径,降低导通损耗的同时相较于常规集成SBD的方法节省了面积。(The invention belongs to the technical field of semiconductors, and relates to a GaN RC-HEMT device with reverse conduction capability. The invention introduces the current barrier layer and the multi-channel conducting path on the basis of the traditional MIS gate HEMT device, integrates the reverse follow current Schottky tube and reduces the reverse turn-on loss. The barrier layer forms 2DHG to block a longitudinal current path, and enhancement of the device is achieved. When the grid is conducted in the forward direction, the grid is heightened to be high in potential, an inversion layer is formed on the side wall of the grid to conduct a longitudinal channel, and both a multi-channel conducting path of the drift region and an electron accumulation layer formed below the grid reduce the conduction resistance; when the drift region is blocked in the forward direction, the blocking layer assists in depleting the drift region to modulate an electric field, so that electric field peaks are reduced, in addition, a polarization electric field formed by the multi-channel region can further improve the withstand voltage of the drift region, and the contradiction relationship between the on-resistance and the withstand voltage is effectively relieved; the integrated Schottky tube forms a current path along the 2DEG during reverse freewheeling, and compared with a conventional integrated SBD method, the area is saved while the conduction loss is reduced.)

1. A GaN RC-HEMT with reverse conduction capability is characterized by comprising a substrate material (1), a GaN buffer layer (2) and a barrier layer (3) which are sequentially stacked from bottom to top along the vertical direction of a device, wherein a heterojunction is formed between the barrier layer (3) and the GaN buffer layer (2) and 2DEG is generated, and a Schottky metal (4), a source electrode semiconductor region, an insulated gate structure and a first conductive material (5) are sequentially distributed on the upper surface of the barrier layer (3) along the transverse direction of the device;

the insulated gate structure is composed of an insulated gate dielectric (6) and a second conductive material (7), the lower surface of the insulated gate dielectric (6) is in contact with the barrier layer (3), and the side wall and the bottom of the second conductive material (7) are surrounded by the insulated gate dielectric (6); the second conductive material (7), the insulated gate dielectric (6) and the barrier layer (3) form an MIS structure; a grid is led out of the upper surface of the second conductive material (7);

one side of the source semiconductor region is contacted with the insulated gate structure, and the other side of the source semiconductor region is spaced from the Schottky metal (4); the source semiconductor region comprises a barrier layer (8), an AlGaN layer (9) and a third conductive material (10) which are sequentially stacked from bottom to top; the third conductive material (10) is positioned at one end, close to the special metal (4), of the upper surface of the AlGaN layer (9), the third conductive material (10) has a distance with the insulated gate structure, the third conductive material (10) is in ohmic contact with the AlGaN layer (9), and a source electrode is led out of the upper surface of the third conductive material (10);

the Schottky metal (4) is in Schottky contact with the barrier layer (3); a Schottky electrode is led out from the upper surface of the Schottky metal (4);

the first conductive material (5) and the insulated gate structure have a distance, and the first conductive material (5) and the barrier layer (3) are in ohmic contact; and the drain electrode is led out from the upper surface of the first conductive material (5).

2. The GaN RC-HEMT with reverse turn-on capability of claim 1, wherein there is a multi-channel region (11) between the insulated gate structure and the first conductive material (5); the multi-channel region (11) is composed of a plurality of GaN layers and AlGaN layers which are sequentially and alternately stacked, the lower surface of the GaN layer is in contact with the barrier layer (3), one side of the multi-channel region (11) is in contact with the first conductive material (5), the contact type is ohmic contact, and the other side of the multi-channel region (11) is in contact with the insulated gate dielectric (6).

3. The GaN RC-HEMT with reverse turn-on capability according to claim 1 or 2, wherein said barrier layer (8) is a GaN layer, said barrier layer (3) is an AlGaN layer, and said barrier layer (8) and said barrier layer (3) form a heterojunction and produce a 2 DHG.

4. The GaN RC-HEMT with reverse turn-on capability of claim 1, wherein the barrier layer (8) and the barrier layer (3) are Al doped with different polarizations_xGa_1-xN material, Al_xGa_1-xThe Al mole component in the N barrier layer (8) is gradually increased from 0 to x (x is more than or equal to 0 and less than or equal to 1) from top to bottom to form 3DHG equivalent to P-type doping, or Al_xGa_1-xThe Al mole composition in the N barrier layer (3) is gradually reduced from x to 0 from top to bottom to form 3 DEG.

Technical Field

The invention belongs to the technical field of power semiconductors, and particularly relates to a GaN RC-HEMT device with reverse conduction capability.

Background

GaN HEMTs switch faster than Si-based power MOSFETs, have less resistance at the same withstand voltage, and can withstand higher operating temperatures. However, GaN HEMTs do not have the advantages of body diodes compared to Si-based power MOSFETs. In inverter circuits widely used in industry, a power MOSFET can use its body diode as a freewheeling diode, which effectively reduces system cost. The system cost can also be reduced more effectively if the GaN HEMT can possess excellent reverse turn-on performance. Due to its unique lateral symmetry, GaN E-HEMTs do not have the same PN body diode as MOSFETs, but can still utilize the lateral conduction channel to conduct current in the reverse direction, while having the advantage of zero reverse recovery loss. However, when the bidirectional conductivity of the GaN E-HEMT is utilized, the turn-on voltage of the third quadrant is much larger than that of the SBD, so that the reverse conduction loss is increased.

In order to solve the problem, an external reverse parallel SBD method is usually adopted to realize reverse freewheeling, but this method may increase parasitic effects, overshoot and oscillation of the device during turn-on and turn-off may be more obvious, and turn-on loss may also increase accordingly. In addition, the additional devices increase the cost, increase the system size, and increase the packaging difficulty. Therefore, how to realize the reverse freewheeling with low conduction loss, low conduction voltage drop and less parasitic effect needs to be solved urgently.

Disclosure of Invention

In order to solve the problems, the invention provides a GaN HEMT device with reverse conduction capability. The on-state loss is further reduced on the basis of the HEMT of the traditional integrated SBD, and the voltage resistance of the device is improved.

The technical scheme of the invention is as follows:

a GaN RC-HEMT with reverse conduction capability comprises a substrate material 1, a GaN buffer layer 2 and a barrier layer 3 which are sequentially stacked from bottom to top along the vertical direction of a device, wherein a heterojunction is formed between the barrier layer 3 and the GaN buffer layer 2 and generates 2DEG, and a Schottky metal 4, a source electrode semiconductor region, an insulated gate structure and a first conductive material 5 are sequentially distributed on the upper surface of the barrier layer 3 along the transverse direction of the device;

the insulated gate structure is composed of an insulated gate dielectric 6 and a second conductive material 7, the lower surface of the insulated gate dielectric 6 is in contact with the barrier layer 3, and the side wall and the bottom of the second conductive material 7 are surrounded by the insulated gate dielectric 6; the second conductive material 7, the insulated gate dielectric 6 and the barrier layer 3 form an MIS structure; a grid is led out of the upper surface of the second conductive material 7;

one side of the source semiconductor region is contacted with the insulated gate structure, and the other side of the source semiconductor region is spaced from the Schottky metal 4; the source semiconductor region comprises a barrier layer 8, an AlGaN layer 9 and a third conductive material 10 which are sequentially stacked from bottom to top; the third conductive material 10 is positioned at one end of the upper surface of the AlGaN layer 9 close to the special metal 4, the third conductive material (10 has a distance with the insulated gate structure, and the third conductive material 10 is in ohmic contact with the AlGaN layer 9; a source electrode is led out of the upper surface of the third conductive material 10;

the Schottky metal 4 is in Schottky contact with the barrier layer 3; a Schottky electrode is led out of the upper surface of the Schottky metal 4;

the first conductive material 5 has a distance with the insulated gate structure, and the first conductive material 5 is in ohmic contact with the barrier layer 3; a drain electrode is led out of the upper surface of the first conductive material 5;

further, a multi-channel region 11 is arranged between the insulated gate structure and the first conductive material 5; the multi-channel region 11 is composed of a plurality of GaN layers and AlGaN layers which are sequentially and alternately stacked, the lower surface of each GaN layer is in contact with the barrier layer 3, one side of the multi-channel region 11 is in contact with the first conductive material 5, the contact type is ohmic contact, and the other side of the multi-channel region 11 is in contact with the insulated gate dielectric 6.

Further, the barrier layer 8 is a GaN layer, and the barrier layer 3 is an AlGaN layer. A heterojunction is formed between the barrier layer 8 and the barrier layer 3 and 2DHG is generated.

Further, the barrier layer 8 and the barrier layer 3 are Al doped with different polarizations_xGa_1-xN material, Al_xGa_1-xThe Al mole component in the N barrier layer 8 is gradually increased from 0 to x (x is more than or equal to 0 and less than or equal to 1) from top to bottom to form 3DHG equivalent to P-type doping, or Al_xGa_1-xThe molar composition of Al in the N barrier layer 3 gradually decreases from x to 0 from top to bottom, forming 3 DEG.

The invention has the beneficial effects that:

1. the integrated reverse follow current SBD and the HEMT share a two-dimensional electron gas (2DEG) passage generated by heterojunction between the AlGaN barrier layer and the GaN buffer layer, and the whole drift region is completely involved in electric conduction when the forward conduction and the reverse follow current are conducted, so that the current capability of the whole device is improved. Compared with the method of separating the two conduction paths in the longitudinal direction of the HEMT of the conventional integrated reverse follow current SBD, the area is further saved. And when the current flows reversely, the current path of the Schottky tube reaches the drain electrode along the 2DEG below the AlGaN barrier layer, so that the conduction loss is reduced. The resistance of the drift region is further reduced by the multi-channel conductive path on the surface of the barrier layer, and meanwhile, the withstand voltage of the drift region can be further improved by a polarization electric field formed during withstand voltage, so that the contradiction between the on-resistance and the withstand voltage is effectively relieved;

2. electrons are accumulated below the insulated gate, so that the concentration of electrons under the gate is improved, the conduction loss is further reduced, and the current capacity is improved. The enhancement device can still be realized when higher 2DEG concentration is maintained below the insulated gate, the influence of an MIS gate HEMT etching barrier layer on the channel on-resistance is eliminated, and the problem of inconsistent threshold voltage distribution of the traditional insulated gate HEMT structure is avoided;

3. when the forward blocking is carried out, the blocking layer assists in depleting the drift region, so that the electric field at the Schottky anode is reduced, and the withstand voltage is effectively improved.

Drawings

FIG. 1 is a schematic structural view of example 1;

FIG. 2 is a schematic structural view of example 2;

Detailed Description

The technical scheme of the invention is described in detail in the following with reference to the accompanying drawings and embodiments:

example 1

As shown in FIG. 1, the GaN RC-HEMT with reverse conduction capability comprises a substrate material 1, a GaN buffer layer 2 and a barrier layer 3 which are sequentially stacked from bottom to top along the vertical direction of the device, wherein a heterojunction is formed between the barrier layer 3 and the GaN buffer layer 2, and 2DEG is generated. The Schottky metal 4, the source electrode semiconductor region, the insulated gate structure and the first conductive material 5 are sequentially distributed along the transverse direction of the device;

the insulated gate structure is composed of an insulated gate dielectric 6 and a second conductive material 7, and the lower surface is in contact with the barrier layer 3. The sidewalls and bottom of the second conductive material 7 are surrounded by the insulated gate dielectric 6. The second conductive material 7, the insulated gate dielectric 6 and the barrier layer 3 form an MIS structure;

a grid is led out of the upper surface of the second conductive material 7;

the source semiconductor region is located above the barrier layer 3, the right side being in contact with the insulated gate structure. The source semiconductor region comprises a barrier layer 8, an AlGaN layer 9 and a third conductive material 10 which are sequentially stacked from bottom to top. The third conductive material 10 is positioned on the left side of the source semiconductor region, has a certain distance with the insulated gate structure, and the lower surface of the third conductive material is in contact with the AlGaN layer 9, wherein the contact type is ohmic contact;

a source electrode is led out of the upper surface of the third conductive material 10;

the first conductive material 5 has a certain distance with the insulated gate structure, the lower surface of the first conductive material is in contact with the barrier layer 3, and the contact type is ohmic contact;

a drain electrode is led out of the upper surface of the first conductive material 5;

the Schottky metal 4 is spaced from the source electrode semiconductor region, the lower surface of the Schottky metal is in contact with the barrier layer 3, and the contact type is Schottky contact;

a Schottky electrode is led out of the upper surface of the Schottky metal 4;

the barrier layer 8 is a GaN layer, and the barrier layer 3 is an AlGaN layer. A heterojunction is formed between the barrier layer 8 and the barrier layer 3 and 2DHG is generated.

The insulated gate structure and the first conductive material 5 have a multi-channel region 11 therebetween. The multi-channel region 11 is located above the barrier layer 3, and is formed by stacking a plurality of GaN layers and AlGaN layers in this order in a staggered manner, and the lower surface of the GaN layer is in contact with the barrier layer 3. The right side of the multi-channel region 11 is in contact with the first conductive material 5, the contact type is ohmic contact, and the left side is in contact with the insulated gate dielectric 6.

The integrated reverse follow current SBD and HEMT share a two-dimensional electron gas (2DEG) passage generated by heterojunction between an AlGaN barrier layer and a GaN buffer layer, the whole drift region is completely involved in conduction during forward conduction and reverse follow current, and the surface of the barrier layer adopts multiple layers of GaN layers and AlGaN layers which are sequentially and alternately stacked to form a multi-channel conduction passage.

According to the GaN RC-HEMT device with the reverse conduction capability, reverse follow current is realized by integrating the Schottky structure into the E-HEMT, and compared with an external reverse parallel follow current diode, the GaN RC-HEMT device with the reverse conduction capability has smaller parasitic parameters. The 2DHG blocking conductive path formed between the blocking layer and the barrier layer realizes enhancement, and the blocking layer assists in depleting the drift region during forward blocking, so that the peak value of a Schottky anode electric field is reduced, the voltage resistance of the device is improved, and a better blocking effect is realized. The resistance of the drift region is further reduced by the multi-channel conductive path, in addition, the withstand voltage of the drift region can be further improved by a polarization electric field formed during withstand voltage, and the contradiction relationship between the on-resistance and the withstand voltage is effectively relieved.

Example 2

Compared with the embodiment 1, the device of the embodiment replaces the conventional P type GaN layer and AlGaN barrier layer with polarization doped Al_xGa_1-xThe N layer solves the problem that P-type doping with higher concentration is difficult to realize due to low activation rate of acceptor impurity Mg in GaN. The barrier layer Al_xGa_1-xThe Al mole component in N is gradually increased from 0 to x (x is more than or equal to 0 and less than or equal to 1) from top to bottom to form 3DHG equivalent to PType doped, barrier layer Al_xGa_1-xThe molar composition of Al in N is gradually smaller from x to 0 from top to bottom, and 3DEG is formed. Polarization doped Al_xGa_1-xN barrier layer and Al_xGa_1-xThe N barrier layer has relatively high carrier mobility due to the fact that high-concentration charged donors and acceptors do not exist, in addition, the low-temperature freezeout effect of carriers is avoided, and the influence of temperature on the device is reduced.