CN219476687U

CN219476687U - Silicon carbide power device with MOSFET and IGBT structures

Info

Publication number: CN219476687U
Application number: CN202223597230.XU
Authority: CN
Inventors: 傅玥; 徐吉; 孔令涛
Original assignee: Nanjing Xingan Technology Co ltd
Current assignee: Nanjing Xingan Technology Co ltd
Priority date: 2022-12-30
Filing date: 2022-12-30
Publication date: 2023-08-04
Anticipated expiration: 2032-12-30

Abstract

The utility model relates to a silicon carbide power device with a MOSFET and IGBT structure, which comprises a substrate layer and a grid electrode, wherein the substrate layer comprises a first substrate and a second substrate; the grid electrode is arranged on the second substrate; the first substrate comprises first conductive type parts and second conductive type parts, the first conductive type parts and the second conductive type parts are alternately arranged, the first conductive type parts and the grid electrode form a groove grid MOSFET structure, and the second conductive type parts and the grid electrode form a groove grid IGBT structure. The utility model improves the defect of low switching frequency through the MOSFET structure while having the advantages of voltage control, larger input impedance, smaller driving power and smaller on-resistance of the IGBT.

Description

Silicon carbide power device with MOSFET and IGBT structures

Technical Field

The utility model relates to the technical field of semiconductors, in particular to a silicon carbide power device with a MOSFET and IGBT structure.

Background

Silicon carbide is a novel wide bandgap semiconductor material having excellent physical, chemical and electrical properties. The breakdown electric field intensity of silicon carbide is 10 times that of traditional silicon, the thermal conductivity is three times that of traditional silicon, and the silicon carbide has higher switching frequency, so that the loss and the volume of energy storage elements in a circuit can be reduced. In theory, the silicon carbide device can work in a high-temperature environment above 600 ℃, has intentional radiation resistance, and greatly improves the high-temperature stability. This makes silicon carbide based power device semiconductors very attractive and promising for applications in high power and high temperature applications.

Among them, silicon carbide MOSFET has low on-resistance, fast switching speed and high temperature resistance etc., and silicon carbide MOSFET device is the next generation semiconductor device manufactured by wide band gap semiconductor material silicon carbide, which is considered to be a new generation semiconductor power piece with the potential of replacing traditional silicon-based IGBT device in the full power application range by virtue of excellent material characteristics. The IGBT integrates the advantages of MOSFET gate voltage control and the advantages of BJT low on-resistance, and has the advantages of voltage control, larger input impedance, smaller driving power, smaller on-resistance and the like. However, in the use of an IGBT, since a P layer is formed on the drain side of the MOSFET, when holes are injected from the P region, the resistivity of the N drift layer decreases when turned on. The turn-on voltage can be reduced due to the conductivity modulation. But minority carriers need to be removed from the N drift layer when the IGBT is turned off. When the IGBT starts to turn off, minority carriers are purged to an external circuit, thereby forming a tail current. This tail current affects the switching frequency of the device, so the switching frequency of the IGBT is not as high as that of the MOSFET.

Therefore, there is an urgent need to provide a silicon carbide power device with both MOSFET and IGBT structures to overcome the above-mentioned technical drawbacks of the prior art.

Disclosure of Invention

Therefore, the technical problem to be solved by the utility model is to overcome the technical defects in the prior art and provide a silicon carbide power device with a MOSFET and IGBT structure, which has the advantages of voltage control, larger input impedance, smaller driving power and smaller on-resistance of the IGBT, and simultaneously improves the defect of low switching frequency through the MOSFET structure.

In order to solve the technical problems, the utility model provides a silicon carbide power device with a MOSFET and IGBT structure, comprising:

a substrate layer including a first substrate and a second substrate;

a gate electrode disposed on the second substrate;

the first substrate comprises a first conductive type part and a second conductive type part, the first conductive type part and the second conductive type part are alternately arranged, the first conductive type part and the grid form a groove grid MOSFET structure, and the second conductive type part and the grid form a groove grid IGBT structure.

In one embodiment of the present utility model, a drift layer is further included, and the drift layer is disposed on the second layer.

In one embodiment of the present utility model, the drift layer is etched with a trench, and polysilicon is deposited in the trench to form the gate.

In one embodiment provided by the utility model, the bottom of the trench is provided with a conductivity type P-region.

In one embodiment of the present utility model, the method further includes a base layer disposed on the drift layer.

In one embodiment of the present utility model, the active layer is disposed on the base layer.

In one embodiment provided by the utility model, the side surface of the groove, which is in partial contact with the conductive type N+ region and the conductive type P-region contained in the active layer, forms a conductive channel.

In one embodiment of the present utility model, the method further includes a source electrode, a trench is etched on the active layer, and metal is deposited in the trench to form the source electrode.

In one embodiment of the present utility model, the method further comprises a drain electrode, wherein a metal contact is deposited on the first substrate to form the drain electrode.

In one embodiment provided by the utility model, the substrate layer is a silicon carbide substrate.

Compared with the prior art, the technical scheme of the utility model has the following advantages:

1. the silicon carbide power device with the MOSFET and IGBT structures has the advantages of voltage control, larger input impedance, smaller driving power and smaller on-resistance of the IGBT, and meanwhile, the defect of low switching frequency is overcome through the MOSFET structure;

2. the silicon carbide power device with the MOSFET and IGBT structures improves the problem of large tailing current and improves the switching frequency of the device;

3. the silicon carbide power device with the MOSFET and IGBT structure, provided by the utility model, connects the IGBT and the MOSFET in parallel, and can be used as a channel of reverse current of the IGBT without connecting a freewheeling diode in parallel under certain use conditions.

Drawings

In order that the utility model may be more readily understood, a more particular description of the utility model will be rendered by reference to specific embodiments thereof that are illustrated in the appended drawings.

Fig. 1 is a schematic structural diagram of a silicon carbide power device with both MOSFET and IGBT structures according to an embodiment of the present utility model.

Wherein reference numerals are as follows: 1. a first substrate; 2. a second substrate; 3. a drift layer; 4. a base layer; 5. an active layer; 6. a gate; 7. a source electrode; 8. and a drain electrode.

Detailed Description

The present utility model will be further described with reference to the accompanying drawings and specific examples, which are not intended to be limiting, so that those skilled in the art will better understand the utility model and practice it.

Referring to fig. 1, an embodiment of the present utility model provides a silicon carbide power device having a MOSFET and IGBT structure, including a substrate layer, a drift layer 3, a base layer 4, an active layer 5, a gate electrode 6, a source electrode 7, and a drain electrode 8, where the drift layer 3, the base layer 4, and the active layer 5 are sequentially formed on the substrate layer from bottom to top, the substrate layer includes a first substrate 1 and a second substrate 2, the drift layer 3 is disposed on the second substrate 2, the drift layer 3 is etched with a trench, polysilicon is deposited in the trench to form the gate electrode 6, a conductive type P-region is disposed at the bottom of the trench, and a conductive channel is formed on a side surface of the trench, which is partially contacted with the conductive type n+ region and the conductive type P-region included in the active layer 5; etching a groove on the active layer 5, and depositing metal in the groove to form the source 7; the first substrate 1 comprises a first conductive type part and a second conductive type part, and the first conductive type part and the second conductive type part are alternately arranged with each other, wherein the first conductive type part and the grid electrode 6 form a trench gate MOSFET structure, and the second conductive type part and the grid electrode 6 form a trench gate IGBT structure; a metal contact is deposited on the conductivity type layer to form the drain 8.

The silicon carbide power device with the MOSFET and IGBT structure has the advantages of voltage control, larger input impedance, smaller driving power and smaller on-resistance of the IGBT, and simultaneously improves the defect of low switching frequency through the MOSFET structure

Specifically, the utility model forms a groove in the drift region by etching, and fills polysilicon as the grid electrode 6 of the device, thereby forming the device with the groove grid structure. The structure can obviously improve the area of the device, reduce the on-resistance and reduce the switching loss.

Further, the first substrate 1 includes a first conductive type n+ and a second conductive type p+ alternately arranged, wherein the first conductive type n+ forms a trench gate MOSFET structure with the gate 6, and the second conductive type p+ forms a trench gate IGBT structure with the gate 6.

As an example, the preparation process of the silicon carbide power device with the MOSFET and IGBT structures provided by the utility model can be manufactured by adopting the following processes:

step one: an n-drift layer 3 is formed on an n+ silicon carbide substrate layer by first depositing, etching is used for etching a poly region in the drift layer 3, an oxide layer is deposited, a gate oxide layer is formed, and aluminum ions are injected in a high-energy ion injection mode to form a p-type region at the bottom. Polysilicon is then deposited in the trenches, forming poly as shown in the figure, as the gate 6 of the device.

Step two: aluminum ions are implanted on the n-drift layer 3 through a mask plate in a high-energy ion implantation mode to form a p-region, and nitrogen ions are implanted in the p-region to form an n+ region, so that a vertical conductive channel is formed.

Step three: an oxide layer is deposited on the top of the silicon carbide, a trench area of a source electrode 7 and a trench area of a grid electrode 6 in the figure are etched through a mask, aluminum ions are injected into the source electrode 7 area through the trench area in an ion injection mode to form a p+ area, and therefore contact of a metal electrode is improved. Metal is then deposited in the trench, directly contacting the silicon carbide to form the electrodes of the gate 6 and source 7.

Step four: finally, aluminum ions and nitrogen ions are implanted on the back of the n+ silicon carbide substrate through high-energy ions so as to form a p+ and n+ alternating region, and finally, metal contacts are deposited on the p+ and n+ alternating region so as to form the drain electrode 8.

In the silicon carbide power device with the MOSFET and IGBT structure, the P+ part at the bottom and N+ and P-together form the PNP bipolar transistor, so that the PNP bipolar transistor can play a role of an emitter, holes can be injected into the drain electrode 8 by the structure, conducting modulation is carried out, and the on-state voltage of the device can be reduced.

When the device is turned on, a sufficient voltage is applied to the gate 6, the side of the poly in contact with the n+ and P-portions forms a conductive channel, and a voltage is applied to the drain 8, thereby allowing an operating current to be formed. When the device is turned off, the N+ part at the bottom can compound minority carriers removed from N-in the part, so that the tail current is reduced, and the switching frequency is improved; the utility model improves the problem of large tailing current and improves the switching frequency of the device.

In the silicon carbide power device with the MOSFET and IGBT structures, a P-region is formed below the groove by utilizing ion implantation, so that a peak electric field generated at the bottom of the groove during high voltage is avoided, and the voltage resistance of the device is further improved.

The silicon carbide power device with the MOSFET and IGBT structure, provided by the utility model, connects the IGBT and the MOSFET in parallel, and can be used as a channel of reverse current of the IGBT without connecting a freewheeling diode in parallel under certain use conditions.

It is apparent that the above examples are given by way of illustration only and are not limiting of the embodiments. Other variations and modifications of the present utility model will be apparent to those of ordinary skill in the art in light of the foregoing description. It is not necessary here nor is it exhaustive of all embodiments. And obvious variations or modifications thereof are contemplated as falling within the scope of the present utility model.

Claims

1. A silicon carbide power device with a MOSFET and IGBT structure is characterized in that: comprising the following steps:

a substrate layer including a first substrate and a second substrate;

a gate electrode disposed on the second substrate;

2. The silicon carbide power device with both MOSFET and IGBT structures of claim 1 wherein: the semiconductor device further comprises a drift layer arranged on the second substrate.

3. The silicon carbide power device with both MOSFET and IGBT structures of claim 2 wherein: and etching a groove on the drift layer, and depositing polysilicon in the groove to form the grid electrode.

4. A silicon carbide power device having both MOSFET and IGBT structures according to claim 3, wherein: the bottom of the trench is provided with a conductivity type P-region.

5. A silicon carbide power device having both MOSFET and IGBT structures according to any of claims 2 to 4, wherein: the semiconductor device further comprises a base layer, wherein the base layer is arranged on the drift layer.

6. The silicon carbide power device with both MOSFET and IGBT structures of claim 5 wherein: the active layer is arranged on the base layer.

7. The silicon carbide power device with both MOSFET and IGBT structures of claim 6 wherein: the side surface of the groove, which is in partial contact with the conductive type N+ region and the conductive type P-region contained in the active layer, forms a conductive channel.

8. The silicon carbide power device with both MOSFET and IGBT structures of claim 6 wherein: and the source electrode is formed by etching a groove on the active layer and depositing metal in the groove.

9. A silicon carbide power device having both MOSFET and IGBT structures according to any of claims 1 to 4, wherein: and the drain electrode is formed by depositing a metal contact on the first substrate.

10. A silicon carbide power device having both MOSFET and IGBT structures according to any of claims 1 to 4, wherein: the substrate layer is a silicon carbide substrate.