CN117116994B - A trench silicon carbide MOSFET and its manufacturing process - Google Patents

Abstract

The invention discloses a trench-type silicon carbide MOSFET and a manufacturing process thereof. The invention relates to the technical field of semiconductor devices and includes: a substrate, the top of which is provided with a source trench for installing source terminals; The drain trench of the drain terminal is installed. The top of the source terminal is connected to the top of the drain terminal through the gate terminal. The bottom of the substrate is provided with a body terminal. When the MOSFET is a depletion mode, the The top of the substrate is also provided with a conductive trench filled with conductive medium; when the MOSFET is an enhancement type, the source trench and the drain trench are separated by the substrate; the source trench and The drain trenches are each provided with an epitaxial region. By increasing the epitaxial area and shortening the length of the circuit channel, under the same Vg condition, when the saturation current is reached, the minimum thickness Dh of the circuit channel is greater than the minimum thickness Dc of the circuit channel of conventional MOSFETs, so that the produced MOSFET can through greater saturation current.

Description

A trench silicon carbide MOSFET and its manufacturing process

Technical field

The present invention relates to the technical field of semiconductor devices, and more specifically, the present invention relates to a trench silicon carbide MOSFET and its manufacturing process.

Background technique

As a vertical structure device, trench MOSFET has the advantages of fast switching speed, good frequency performance, high input impedance, low driving power, good temperature characteristics, and no secondary breakdown problem. It has been used in voltage regulators and power management modules. , electromechanical control, display control, automotive electronics and other fields have been widely used. There is a circuit channel between the source and drain of the MOSFET. As the voltage at the drain terminal increases, the drain of the MOSFET and the depletion region of the substrate will increase due to reverse bias, resulting in a reduction in the width of the circuit channel. To limit the flow of charge, which in turn causes the current to decrease until it reaches saturation current, we usually adjust the threshold voltage to increase the width of the circuit channel, thereby adjusting the saturation current through the circuit channel. However, this requires the power supply of the gate terminal to be controllable. How to obtain a larger saturation current without adjusting the threshold voltage and produce a MOSFET that can meet this condition is a technical problem to be solved by the present invention. Therefore, it is necessary to propose a trench silicon carbide MOSFET and its manufacturing process to at least partially solve the problems existing in the prior art.

Contents of the invention

This summary introduces a series of concepts in a simplified form that are further described in detail in the detailed description. The summary of the present invention is not intended to limit the key features and necessary technical features of the claimed technical solution, nor is it intended to determine the protection scope of the claimed technical solution.

In order to at least partially solve the above problems, the present invention provides a trench-type silicon carbide MOSFET, including: a substrate, a source trench for installing a source terminal is provided on the top of the substrate, and a drain terminal is installed on the top of the substrate. the drain trench, the top of the source terminal is connected to the top of the drain terminal through the gate terminal, and the bottom of the substrate is provided with a body terminal,

When the MOSFET is depletion mode, a conductive trench filled with conductive medium is also provided on the top of the substrate. The source trench and the drain trench are connected through the conductive trench, and the gate terminal is connected to the conductive trench. The source terminal and the drain terminal are both connected to the conductive trench;

When the MOSFET is an enhancement type, the source trench and the drain trench are separated by the substrate, and the source terminal is connected to the drain terminal through the gate terminal;

Epitaxial regions are provided on both the source trench and the drain trench.

Preferably, the source trench is a vertical trench, and an epitaxial region is provided on a side wall of the source trench close to the drain trench, and the epitaxial region extends from the source trench to the The drain trench direction extends.

Preferably, the drain trench is a vertical trench, and an epitaxial region is provided on a side wall of the drain trench close to the source trench, and the epitaxial region extends from the drain trench to the The source trench extends in the direction.

Preferably, a dielectric layer is provided between the source terminal and the drain terminal, and the gate terminal is provided above the dielectric layer.

A manufacturing process of trench silicon carbide MOSFET, the steps are as follows:

S1: Use wet etching equipment to etch the glue-coated substrate to form source trenches and drain trenches;

S2: Place the wet-etched substrate in the dry etching equipment, and connect and position it with the fixed components in the dry etching equipment through the positioning component clamped on the substrate;

S3: Reprocess the source trench and drain trench through dry etching equipment to form a source trench with an epitaxial region and a drain trench with an epitaxial region;

S4: Inject ions into the source trench and drain trench, and deposit source terminals and drain terminals.

Preferably, in step S1, the source trench and the drain trench produced by wet etching equipment are V-shaped trenches.

Preferably, in step S2, the positioning assembly clamped on the base plate is composed of a fixed plate and a positioning matrix arranged on the fixed plate. One side of the fixed plate is clamped and fixed to the base plate, and the other side is connected to the base plate through the positioning matrix. The fixed components on the dry etching equipment are connected and positioned, and the positioning matrix is composed of several quadrangular pyramids.

Preferably, the fixing component in the dry etching equipment is composed of a positioning layer and a fixing layer. The positioning layer is arranged above the fixing layer. The top surface of the positioning layer is provided with the positioning matrix. A suitable positioning slot matrix, which is composed of several positioning slots that penetrate the positioning layer and extend into the fixed layer. The shape of the positioning slots is consistent with the shape of the quadrangular pyramid on the positioning matrix. The shape is suitable, and a positioning channel is provided between the positioning layer and the fixed layer, and the positioning grooves in the positioning groove matrix are all connected through the positioning channel;

The positioning channel is filled with elastomer,

Or the positioning channel extends to the side wall of the positioning layer and is connected to the vacuuming equipment.

Preferably, in step S3, the dry etching equipment performs eccentric etching on the source trench and the drain trench, and the V-shaped parts that are not dry etched form an epitaxial region.

Preferably, in step S4, ions are implanted into the source trench and the drain trench to define the source and drain regions, and then the source metal, the drain metal and the gate terminal are deposited.

Compared with the prior art, the present invention at least includes the following beneficial effects:

The invention consists of a substrate, a source terminal arranged in the source trench, a drain terminal arranged in the drain trench, a body terminal connected to the substrate, and an intermediary connected between the source terminal and the drain terminal. It consists of an electrical layer and a gate terminal connected above the dielectric layer. It should be noted that the source terminal and the drain terminal are structurally the same, so there is no need to specifically distinguish the source terminal and the drain terminal, that is, one is used as the source terminal, and the other is naturally used as the drain terminal. Taking the enhancement mode N channel as an example, that is, the source terminal and drain terminal use N-type semiconductor, and the substrate uses P-type semiconductor. The source terminal and the body terminal are electrically connected, and the power supply can be connected between the drain terminal (connected to the positive electrode) and the source terminal (connected to the negative electrode). At this time, the voltage between the drain terminal and the source terminal is Vd, because The power supply increases the potential of the drain terminal, so it causes the depletion region between the drain terminal and the substrate to increase, so the current does not flow from the drain terminal into the source terminal, leaving the MOSFET in the off state (normally closed). ), in order to allow the current to flow from the drain terminal to the source terminal, another channel needs to be established. We add a power supply between the gate terminal and the source terminal. The positive electrode is connected to the gate terminal, and the negative electrode is connected to the source terminal. connection, the voltage between the gate terminal and the source terminal is Vg at this time. Because of the existence of the dielectric layer, electrons cannot flow from the substrate to the gate terminal. In addition to blocking electrons, the dielectric layer can also increase the charge on the electrons ( Similar to a capacitor), thereby attracting more electrons because the substrate at the gate terminal collects a large number of free electrons, causing the substrate near the gate terminal to become a negative or N-type semiconductor, which in turn forms a source terminal within the substrate A circuit channel (similar to a conductive trench) connected to the drain terminal so that current can flow from the drain terminal to the source terminal to form a path, that is, the switch is open. We can adjust the voltage of the gate terminal by changing Vg, thereby changing the thickness of the circuit channel, which can form the voltage of the circuit channel, which we call the threshold voltage. When the circuit channel is connected, the MOSFET is in the ohmic or linear region. In this region within, following Ohm's law.

A problem will arise at this time, that is, as the voltage increases, the depletion area of the drain terminal and the substrate (circuit channel part) will increase with reverse bias, as shown in Figure 3, and the depletion area in the circuit channel The depletion area will increase from the drain terminal to the source terminal, thereby reducing the width of the channel, limiting the flow of charge, resulting in a decrease in current (the principle of changing the size of the current through the conductive trench in the depletion mode is the same, but the depletion mode requires Negative gate voltage to achieve circuit break), when the voltage increases, the circuit channel will be completely blocked by the depletion region, which we call the pinch-off effect. However, in actual application, the circuit channel will not be completely closed, but A constant saturation current will be formed, and the voltage that generates the saturation current is the saturation voltage. In order to increase the size of the saturation current, the threshold voltage of the gate terminal is generally increased to increase the width of the circuit channel, thereby increasing the size of the saturation current. Because this method requires changing Vg, we propose an implementation method of changing the saturation current under the same Vg, that is, we add epitaxial regions on the source trench and drain trench, as shown in Figure 4. Increase the epitaxial area and shorten the distance between the drain trench and the drain trench on the end surface, thereby shortening the length of the circuit channel. Under the same Vg condition, when the saturation current is reached, the minimum thickness Dh of the circuit channel is greater than conventional processing The minimum thickness Dc of the circuit channel of the MOSFET processed in this way is shown in Figure 5. In this way, the produced MOSFET can pass a larger saturation current without changing Vg.

The trench type silicon carbide MOSFET and its manufacturing process according to the present invention, other advantages, objectives and features of the present invention will be partially reflected by the following description, and partially will also be demonstrated to those skilled in the art through the research and practice of the present invention. understood.

Description of the drawings

The drawings are used to provide a further understanding of the present invention and constitute a part of the specification. They are used to explain the present invention together with the embodiments of the present invention and do not constitute a limitation of the present invention. In the attached picture:

Figure 1 is a schematic structural diagram of an enhancement mode MOSFET in the prior art.

Figure 2 is a schematic structural diagram of a depletion mode MOSFET in the prior art.

Figure 3 is a schematic diagram of the structure of the increased depletion region.

Figure 4 is a schematic structural diagram of the trench silicon carbide MOSFET according to the present invention.

Figure 5 is a schematic diagram comparing the minimum thickness of the trench silicon carbide MOSFET circuit channel according to the present invention with the prior art (dotted line part).

6 is a schematic structural diagram of the source trench and the drain trench produced by wet etching equipment in the trench silicon carbide MOSFET manufacturing process S1 of the present invention.

FIG. 7 is a schematic diagram of the source trench and the drain trench processed by dry etching equipment in the trench silicon carbide MOSFET manufacturing process S3 of the present invention.

FIG. 8 is a schematic structural diagram of the positioning component and the fixing component in the trench silicon carbide MOSFET manufacturing process S2 of the present invention.

9 is a partial top view and a cross-sectional view of the fixed component in the trench silicon carbide MOSFET manufacturing process S2 of the present invention.

Figure 10 is a schematic diagram of the positioning component and the fixed component before and after the connection (shown as C in the figure) and after the connection (shown as D in the figure) in the trench silicon carbide MOSFET manufacturing process S2 of the present invention.

In the picture: 1 substrate, 11 source trench, 12 drain trench, 2 source terminal, 3 drain terminal, 4 gate terminal, 5 body terminal, 6 dielectric layer, 7 depletion region, 8 positioning components , 81 fixed plate, 82 positioning matrix, 9 fixed components, 91 positioning layer, 92 fixed layer, 93 positioning channel.

Implementation

The present invention will be further described in detail below in conjunction with the accompanying drawings and examples, so that those skilled in the art can implement it with reference to the text of the description.

It should be understood that terms such as "having," "comprising," and "including" as used herein do not exclude the presence or addition of one or more other elements or combinations thereof.

As shown in Figures 1 to 10, the present invention provides a trench silicon carbide MOSFET and its manufacturing process, including: a substrate 1, with a source trench for installing a source terminal 2 provided on the top of the substrate 1 11, and a drain trench 12 for mounting the drain terminal 3. The top of the source terminal 2 is connected to the top of the drain terminal 3 through the gate terminal 4. The bottom of the substrate 1 is provided with a main body. Terminal 5,

When the MOSFET is a depletion mode, a conductive trench filled with conductive medium is also provided on the top of the substrate 1. The source trench 11 and the drain trench 12 are connected through the conductive trench, and the gate terminal Terminal 4 is connected to the source terminal 2 and the drain terminal 3 to the conductive trench;

When the MOSFET is an enhancement type, the source trench 11 and the drain trench 12 are separated by the substrate 1 , and the source terminal 2 is connected to the drain terminal through the gate terminal 4 sub3 connection;

Epitaxial regions are provided on both the source trench 11 and the drain trench 12 .

The source trench 11 is a vertical trench, and an epitaxial region is provided on the side wall of the source trench 11 close to the drain trench 12. The epitaxial region extends from the source trench 11 to the direction of the drain trench 12. The drain trench 12 extends in the direction 12 .

The drain trench 12 is a vertical trench, and an epitaxial region is provided on the side wall of the drain trench 12 close to the source trench 11. The epitaxial region extends from the drain trench 12 to the direction of the source trench 11. The source trench 11 extends in one direction.

A dielectric layer 6 is provided between the source terminal 2 and the drain terminal 3 , and the gate terminal 4 is provided above the dielectric layer 6 .

The working principle and beneficial effects of the above technical solution: MOSFET is usually made of semiconductor materials such as silicon, and because the conductivity of the semiconductor is between the conductor and the insulator, we add impurities to the silicon crystal to make it have better Conductivity. If a pentavalent impurity is added, the semiconductor is called N-type. If a trivalent impurity is added, the semiconductor is P-type. When P-type and N-type semiconductors are connected together At this time, the electrons in the N-type semiconductor at the junction will fill the holes in the P-type semiconductor, thereby depleting the charges near the junction, forming a depletion region 7, as shown in Figures 1 and 2. The depletion region 7 that decreases when power is on is called forward bias (for example, the P-type is connected to the positive electrode of the battery, and the N-type is connected to the negative electrode of the battery); the depletion region 7 that increases when power is on is called reverse bias. MOSFET is usually divided into depletion type (a conductive trench is provided, and the MOSFET is in a normally open state, that is, when there is no voltage across the gate terminal 4, it conducts through the conductive trench. When there is a voltage across the gate terminal 4, The conductivity decreases) and the enhancement type (no conductive trench, that is, when there is no voltage across the gate terminal 4, the device does not conduct, and when the voltage across the gate terminal 4 reaches the maximum, the device conducts), and according to the substrate 1, source The material selection of terminal 2 and drain terminal 3, depletion type and enhancement type can be subdivided into two types: N channel and P channel. The present invention does not further limit the selection of channels, that is, regardless of whether N channel is selected , or P channel, whether depletion type or enhancement type, should be included in the protection scope of the present invention.

The present invention consists of a substrate 1, a source terminal 2 arranged in a source trench 11, a drain terminal 3 arranged in a drain trench 12, a body terminal 5 connected to the substrate 1, and a source terminal 2 connected to the substrate 1. It consists of a dielectric layer 6 between the dielectric layer 6 and the drain terminal 3 and a gate terminal 4 connected above the dielectric layer 6 . It should be noted that the source terminal 2 and the drain terminal 3 are structurally the same, so there is no need to distinguish the source terminal 2 and the drain terminal 3. That is, one is used as the source terminal 2, and the other is naturally used as the drain terminal. Sub3 is used. Taking the enhancement mode N channel as an example, that is, the source terminal 2 and the drain terminal 3 use N-type semiconductors, and the substrate 1 uses P-type semiconductors. The source terminal 2 and the body terminal 5 are electrically connected, and the power supply can be connected between the drain terminal 3 (connected to the positive electrode) and the source terminal 2 (connected to the negative electrode). At this time, between the drain terminal 3 and the source terminal 2 The voltage of is Vd, because the power supply increases the potential of the drain terminal 3, it will cause the depletion region 7 between the drain terminal 3 and the substrate 1 to increase, so the current will not enter from the drain terminal 3 to the source terminal 2 within, so that the MOSFET is in the off state (normally closed). In order to allow the current to reach the source terminal 2 from the drain terminal 3, another channel needs to be established. We add a channel between the gate terminal 4 and the source terminal 2. Assume a power supply, the positive electrode is connected to the gate terminal 4, and the negative electrode is connected to the source terminal 2. At this time, the voltage between the gate terminal 4 and the source terminal 2 is Vg. Because of the presence of the dielectric layer 6, electrons cannot escape from the substrate. 1 flows to the gate terminal 4, and the dielectric layer 6, in addition to blocking electrons, can also increase the charge on the electrons (similar to a capacitor), thereby attracting more electrons, because the substrate 1 at the gate terminal 4 accumulates a large number of free electrons , thereby causing the substrate 1 near the gate terminal 4 to become a negative or N-type semiconductor, thereby forming a circuit channel (similar to a conductive trench) connecting the source terminal 2 and the drain terminal 3 within the substrate 1, so that the current can flow from The drain terminal 3 flows to the source terminal 2 to form a path, that is, the switch is opened. We can adjust the voltage of gate terminal 4 by changing Vg, thereby changing the thickness of the circuit channel, which can form the voltage of the circuit channel, which we call the threshold voltage. When the circuit channel is connected, the MOSFET is in the ohmic or linear region, where Within the region, Ohm's law is followed.

A problem will arise at this time, that is, as the voltage increases, the depletion region 7 of the drain terminal 2 and the substrate 1 (circuit channel part) will increase with reverse bias, as shown in Figure 3, and the circuit channel The depletion region 7 inside will increase from the drain terminal 3 to the source terminal 2, thereby reducing the width of the channel, limiting the flow of charge, resulting in a decrease in current (the principle of the depletion type changing the size of the current through the conductive trench is the same, It’s just that the depletion mode requires a negative gate voltage to achieve circuit breakage). When the voltage increases, the circuit channel will be completely blocked by the depletion region 7. We call it the pinch-off effect. However, in actual application, the circuit channel does not It will not be completely closed, but will form a constant saturation current, and the voltage that generates the saturation current is the saturation voltage. In order to increase the size of the saturation current, the threshold voltage of the gate terminal 4 is generally increased to increase the width of the circuit channel, thereby increasing the size of the saturation current. Because this method requires changing Vg, we propose an implementation method of changing the saturation current under the same Vg, that is, we add an epitaxial region on the source trench 11 and the drain trench 12, as shown in Figure 4 , by increasing the epitaxial area, shortening the distance between the drain trench 12 and the drain trench 11 on the end surface, thereby shortening the length of the circuit channel. When Vg is the same, when the saturation current is reached, the minimum thickness of the circuit channel Dh is greater than the minimum thickness Dc of the circuit channel of MOSFET processed by conventional processing methods, as shown in Figure 5. This enables the produced MOSFET to pass a larger saturation current without changing Vg.

The present invention provides a manufacturing process for trench silicon carbide MOSFET. The steps are as follows:

S1: Use wet etching equipment to perform isotropic etching to etch the glue-coated substrate 1 to form the source trench 11 and the drain trench 12. In order to make the source trench 11 and the drain trench Groove 12 is processed into a V-shaped groove, which requires the use of alkaline solution, and excessive etching depth should be avoided;

S2: Place the wet-etched substrate 1 in the dry etching equipment, perform anisotropic etching, and pass the positioning component 8 clamped on the substrate 1 and the fixing component 9 in the dry etching equipment. Connection and positioning (in fact, the difficulty in etching processing is not etching, but positioning, because there are many dry etching equipment now, such as CCP and ICP etching equipment. Because in the present invention, it is necessary to To process the epitaxial area, the bevel needs to be processed by wet etching first, and then the bevel and depth on the other side are processed by dry etching. Therefore, how to ensure the accuracy of the processing position after switching equipment is a problem to be solved by this process. );

The positioning assembly 8 clamped on the base plate 1 is composed of a fixing plate 81 and a positioning matrix 82 arranged on the fixing plate 81. One side of the fixing plate 81 is clamped and fixed to the base plate 1 (the clamping of the fixing plate 81 and the base plate 1 Fixing can be achieved by conventional technical means, such as side groove clamping, etc.), and the other side is connected and positioned with the fixing component 9 on the dry etching equipment through the positioning matrix 82. The positioning matrix 82 is composed of several Composed of four-sided pyramid;

The fixing component 9 in the dry etching equipment is composed of a positioning layer 91 and a fixing layer 92. The positioning layer 91 is provided above the fixing layer 92. The top surface of the positioning layer 91 is provided with the fixing layer 92. A matrix of positioning grooves adapted to the positioning matrix 82. The matrix of positioning grooves is composed of several positioning grooves that penetrate the positioning layer 91 and extend into the fixed layer 92. The shape of the positioning grooves is consistent with that of the positioning matrix. The shape of the quadrangular pyramid on 82 is adapted to the shape. When transferring the processing equipment, the quadrangular pyramid of the positioning matrix 82 is inserted into the positioning slot of the positioning slot matrix. The matrix positioning slot and the quadrangular pyramid can be used to achieve quick insertion and positioning, and Ensure the firmness after positioning. A positioning channel 93 is provided between the positioning layer 91 and the fixing layer 92, and the positioning grooves in the positioning groove matrix are all connected through the positioning channel 93;

In order to increase the firmness of the connection, we have given two solutions:

1. By filling the positioning channel 93 with an elastomer, the friction between the single quadrangular pyramid and the positioning groove is increased. The elastomer can be a silicone pad. In this implementation, dry etching equipment is required. Set up fixing devices that can press on the fixing plate 81, such as buckles, screws, etc. This method is generally not used because the structure is relatively complex and requires a lot of additional equipment.

2. The positioning channel 93 extends to the side wall of the positioning layer 91 and is connected to the vacuuming equipment; after the quadrangular pyramid is inserted into the positioning groove, the vacuuming equipment is started to pump air to fix the positioning matrix. and the role of positioning. Because dry etching needs to be performed under a specified vacuum pressure, there is no need to equip separate vacuuming equipment. This embodiment has a simple structure and the equipment can be shared. Therefore, this embodiment is usually used in actual production.

S3: Use dry etching equipment to eccentrically etch the source trench 11 and the drain trench 12 (that is, when dry etching, retain the slope of the source trench 11 close to the drain trench 12 , in the same way, retain the slope of the drain trench 12 close to the source trench 11, and the V-shaped part that has not been dry-etched forms an epitaxial region), and processes it to a specified depth to form a source with an epitaxial region. Trench 11 and drain trench 12 with epitaxial region;

S4: Inject ions into the source trench 11 and the drain trench 12, and deposit the source terminal 2 and the drain terminal 3; inject ions into the source trench 11 and the drain trench 12 to define the source and drain regions. , and then deposit the source metal, drain metal and gate terminal 4.

The MOSFET processed through this production process can effectively shorten the length of the circuit channel. At the same time, compared with traditional MOSFET, this equipment has higher processing accuracy and the finished product is smaller in size.

In the description of the present invention, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", " "Back", "Left", "Right", "Vertical", "Horizontal", "Top", "Bottom", "Inside", "Outside", "Clockwise", "Counterclockwise", "Axis", The orientations or positional relationships indicated by "radial direction", "circumferential direction", etc. are based on the orientations or positional relationships shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply the referred devices or components. Must have a specific orientation, be constructed and operate in a specific orientation and are therefore not to be construed as limitations of the invention.

In the present invention, unless otherwise clearly stated and limited, the terms "installation", "connection", "connection", "fixing" and other terms should be understood in a broad sense. For example, it can be a fixed connection or a detachable connection. , or integrated; it can be mechanically connected, electrically connected or communicable with each other; it can be directly connected or indirectly connected through an intermediate medium; it can be the internal connection of two elements or the interaction between two elements, Unless otherwise expressly limited. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the description and embodiments. They can be applied to various fields suitable for the present invention. For those familiar with the art, they can easily Additional modifications may be made, and the invention is therefore not limited to the specific details and illustrations shown and described herein without departing from the general concept defined by the claims and equivalent scope.

Claims (4)

1. The manufacturing process of the groove type silicon carbide MOSFET is characterized by comprising the following steps of:

s1: etching the glued substrate (1) through wet etching equipment to form a source electrode groove (11) and a drain electrode groove (12);

s2: placing the substrate (1) subjected to wet etching in dry etching equipment for anisotropic etching, and connecting and positioning the substrate with a fixed component (9) in the dry etching equipment through a positioning component (8) clamped on the substrate (1);

s3: reprocessing the source trench (11) and the drain trench (12) by a dry etching device to form a source trench (11) with an epitaxial region and a drain trench (12) with an epitaxial region;

s4: implanting ions into the source trench (11) and the drain trench (12), and depositing a source terminal (2) and a drain terminal (3);

in the step S2, a positioning component (8) clamped on a substrate (1) consists of a fixed plate (81) and a positioning matrix (82) arranged on the fixed plate (81), one surface of the fixed plate (81) is clamped and fixed with the substrate (1), the other surface of the fixed plate is connected and positioned with a fixing component (9) on dry etching equipment through the positioning matrix (82), and the positioning matrix (82) consists of a plurality of rectangular pyramids;

the fixing assembly (9) in the dry etching equipment is composed of a locating layer (91) and a fixing layer (92), the locating layer (91) is arranged above the fixing layer (92), a locating channel (93) is arranged between the locating layer (91) and the fixing layer (92), the locating channel matrix is composed of a plurality of locating grooves penetrating through the locating layer (91) and extending into the fixing layer (92), the shape of each locating groove is matched with that of a quadrangular pyramid on the locating matrix (82), when the processing equipment is transferred, the quadrangular pyramid of the locating matrix (82) is inserted into the locating groove of the locating channel matrix, and locating grooves in the locating channel matrix are all communicated through the locating channel (93);

the positioning channel (93) is filled with an elastomer,

or the positioning channel (93) extends to the side wall of the positioning layer (91) and is connected with a vacuumizing device;

when the positioning channel (93) is filled with an elastomer, the dry etching equipment is provided with a fixing equipment capable of being pressed on the fixing plate (81);

when the positioning channel (93) extends to the side wall of the positioning layer (91) and is connected with the vacuumizing device, the vacuumizing device is started to suck air after the rectangular pyramid is inserted into the positioning groove.

2. The process for fabricating a trench type silicon carbide MOSFET according to claim 1, wherein in step S1, the source trench (11) and the drain trench (12) fabricated by the wet etching apparatus are V-shaped grooves.

3. The process for fabricating a trench type silicon carbide MOSFET according to claim 1, wherein in step S3, the dry etching apparatus performs eccentric etching on the source trench (11) and the drain trench (12), and V-shaped portions not dry etched form an epitaxial region.

4. The process according to claim 1, wherein in step S4 ions are implanted into the source trench (11) and the drain trench (12), defining source and drain regions, and then source metal, drain metal and gate terminal (4) are deposited.