A preparation process of TMBS device

Abstract

The present invention relates to the field of semiconductors, and in particular to a preparation process of a TMBS device, comprising the following steps: step 1, cutting, polishing, cleaning and drying a silicon substrate in sequence, and using it as a substrate material; step 2, forming an epitaxial layer on the upper surface of the substrate material; step 3, processing the epitaxial layer by etching to form a groove, forming an oxide layer on the inner surface of the groove, and then filling it with polysilicon; step 4, setting a Schottky barrier layer, setting a metal electrode, and leading out a positive and negative electrode through the metal electrode, thus completing the preparation of the TMBS device. The device prepared by the present invention uses bismuth germanium selenide as an epitaxial layer, which greatly improves the breakdown characteristics of the device and the unstable factors of the leakage current, improves the breakdown resistance and reduces the leakage current density, thereby improving the reliability of the device.

Description

Technical Field

[0001] The invention relates to the field of semiconductors, and in particular to a preparation process of a TMBS device. Background Art

[0002] The preparation and processing of semiconductor materials are an important part of the modern electronics industry. The development and performance improvement of semiconductor devices are inseparable from advanced semiconductor process technology. TMBS (Trench MOS Barrier Schottky) semiconductor devices are a new type of power device that combines MOS drain structure and Schottky barrier. It has the advantages of low leakage current, fast switching speed and low turn-on voltage drop. It is widely used in power management, electric vehicles, aerospace and other fields.

[0003] TMBS semiconductor process preparation technology is one of the key links in the preparation of TMBS devices. Its quality and stability directly affect the performance and cost of the device. In the process of TMBS semiconductor process preparation, it is necessary to include multiple links such as material growth, device processing, surface treatment, testing and packaging.

[0004] In the process of preparing TMBS devices, inductive plasma etching (ICP) will inevitably damage the structure of silicide, generate a large number of defects, and ultimately sacrifice the device's performance such as breakdown voltage and on-resistance, while affecting the reliability of the device. However, as one of the most important parameters of power devices, breakdown voltage largely limits the application scope of power devices. In the prior art, the breakdown resistance of the device is improved by changing the structure of the TMBS device, but there are still problems such as large leakage current and breakdown voltage far below the theoretical value. Summary of the invention

[0005] In view of the problems existing in the prior art, the object of the present invention is to provide a preparation process of a TMBS device.

[0006] The purpose of the present invention is achieved by the following technical solutions:

[0007] In a first aspect, the present invention provides a process for preparing a TMBS device, comprising the following steps:

[0008] Step 1, cutting, polishing, cleaning and drying the silicon substrate in sequence and then using it as a substrate material;

[0009] Step 2, forming an epitaxial layer on the upper surface of the substrate material, wherein the epitaxial layer is made of germanium bismuth selenide and is grown on the upper surface of the substrate material by chemical vapor deposition (CVD);

[0010] Step 3, the epitaxial layer is processed by etching to form an array of U-shaped grooves, and then an oxide layer is formed on the inner surface of the grooves, and then the grooves are completely filled with polysilicon;

[0011] Step 4, a Schottky barrier layer is set on the upper surface of the epitaxial layer except the groove, and then metal electrodes are set on the lower surface of the Schottky barrier layer and the substrate material respectively, and the positive and negative electrodes are led out through the metal electrodes, thus completing the preparation of the TMBS device.

[0012] Preferably, in step 1, the material of the silicon substrate is one of single crystal silicon, silicon carbide and silicon nitride.

[0013] Preferably, in step 1, the cutting is single-wire cutting or multi-wire cutting, more preferably single-wire cutting.

[0014] Preferably, in step 1, the polishing method is chemical mechanical polishing (CMP).

[0015] Preferably, in step 1, the cleaning is ultrasonic cleaning using ethanol and deionized water in sequence, the frequency of ultrasonic cleaning is 20-100 kHz, the temperature is room temperature, and the washing time is 30-60 s.

[0016] Preferably, in step 1, the drying method is one of vacuum drying, heating drying and nitrogen blowing drying, and nitrogen blowing drying is more preferred.

[0017] Preferably, in step 2, the preparation process of the epitaxial layer includes:

[0018] S1, first tetramethylgermanium (Ge(CH 3 ) 4 ), trimethylbismuth (Bi(CH 3 ) 3 ) and dimethylselenide (Se(CH 3 ) 2 ) are mixed in a container, hydrogen is introduced as a protective gas, and the temperature is raised until all gasification occurs to obtain a mixed gas;

[0019] S2. Place the substrate material in the reaction chamber of the deposition equipment, introduce hydrogen after evacuation, maintain the pressure at 150-250 mbar, then increase the temperature to 250-350°C, gradually introduce the mixed gas, then increase the temperature to 550-650°C, and control the pressure to 450-550 mbar;

[0020] S3. Maintaining constant temperature and pressure until the deposition thickness on the substrate material surface reaches 5-15 μm, stopping ventilation, and slowly lowering the temperature and pressure to normal temperature and pressure to complete the deposition of germanium bismuth selenide.

[0021] Preferably, in S1, the mass ratio of tetramethylgermanium, trimethylbismuth, dimethylselenium and hydrogen is 0.7-1.4:1.2-2.4:3-8:10-20.

[0022] Preferably, in step 3, the thickness of the oxide layer is 80-160 nm, the depth of each groove is 1.2-3.6 μm, the width of each groove is 0.4-0.6 μm, and the distance between every two grooves is 0.6-1.2 μm.

[0023] Preferably, in step 4, the material of the Schottky barrier layer is titanium nitride or aluminum nitride, and the thickness is 0.2-0.7 μm, more preferably titanium nitride.

[0024] In a second aspect, the present invention provides a TMBS device prepared by the above-mentioned preparation process.

[0025] The beneficial effects of the present invention are:

[0026] 1. The present invention provides a preparation process of a TMBS device. On the basis of the traditional synthesis method, the synthesis steps are slightly improved, and an epitaxial layer is directly generated on the surface of a substrate, and the epitaxial layer is made of germanium bismuth selenide, and then etching and surface setting are performed. The TMBS device obtained by the method of the present invention not only has better breakdown resistance, but also effectively suppresses reverse leakage current.

[0027] 2. In the traditional preparation process, the buffer layer is generally omitted only when the material of the epitaxial layer is the same as that of the substrate, because when the epitaxial layer and the substrate are made of different materials, it is easy to increase the surface defects of the substrate, thereby reducing the electron mobility and service life of the device. In the process of the present invention, the substrate is a silicon substrate, and the epitaxial layer uses bismuth germanium selenide. However, after omitting the design of the buffer layer, it is found that there is no obvious defect state on the substrate surface, indicating that its lattice is relatively matched, which helps to improve the stability and life of the device.

[0028] 3. The device prepared by the present invention uses bismuth germanium selenide as the epitaxial layer, which greatly improves the breakdown characteristics of the device and the instability factor of the leakage current, enhances the breakdown resistance and reduces the leakage current density, thereby improving the reliability of the device. DETAILED DESCRIPTION

[0029] In order to better understand the above technical scheme, the exemplary embodiments of the present invention are described in more detail below. Although exemplary embodiments of the present invention are shown, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present invention and to enable the scope of the present invention to be fully communicated to those skilled in the art.

[0030] The present invention will be further described below in conjunction with the following examples.

[0031] Example 1

[0032] A preparation process of a TMBS device comprises the following steps:

[0033] Step 1, single-wire cutting is first performed on the single crystal silicon wafer, followed by chemical mechanical polishing (CMP), followed by ultrasonic cleaning with ethanol and deionized water at room temperature for 40 seconds respectively, the frequency of ultrasonic cleaning is 80kHz, and then nitrogen blowing is performed to dry the wafer, and the wafer is used as a substrate material;

[0034] Step 2, forming an epitaxial layer on the upper surface of the substrate material, wherein the epitaxial layer is made of germanium bismuth selenide and is grown on the upper surface of the substrate material by chemical vapor deposition (CVD);

[0035] Step 3, the epitaxial layer is processed by etching to form an array of U-shaped grooves, each of which has a depth of 2.4 μm, a width of 0.5 μm, and a spacing of 0.9 μm between every two grooves, and then an oxide layer with a thickness of 120 nm is formed on the inner surface of the groove, and then the groove is completely filled with polysilicon;

[0036] Step 4, set a Schottky barrier layer on the upper surface of the epitaxial layer except the groove, the material is titanium nitride, the thickness is 0.5μm, and then set a metal electrode copper on the surface of the Schottky barrier layer to lead out the positive electrode. At the same time, set a metal electrode copper on the lower surface of the substrate material to lead out the negative electrode, and complete the preparation of the TMBS device.

[0037] Wherein, in step 2, the preparation process of the epitaxial layer includes:

[0038] S1, first tetramethylgermanium (Ge(CH 3 ) 4 ), trimethylbismuth (Bi(CH 3 ) 3 ) and dimethylselenide (Se(CH 3 ) 2 ) are mixed in a container, hydrogen is introduced as a protective gas, the mass ratio of tetramethylgermanium, trimethylbismuth, dimethylselenium and hydrogen is 1.1:1.8:5:15, and the temperature is raised until all are gasified to obtain a mixed gas;

[0039] S2, placing the substrate material in the reaction chamber of the deposition equipment, introducing hydrogen after evacuation, maintaining the pressure at 200 mbar, then raising the temperature to 300°C, gradually introducing the mixed gas, then raising the temperature to 600°C, and controlling the pressure to 500 mbar;

[0040] S3. Maintaining constant temperature and pressure until the deposition thickness on the substrate material surface reaches 10 μm, stopping ventilation, and slowly lowering the temperature and pressure to normal temperature and pressure to complete the deposition of germanium bismuth selenide.

[0041] Example 2

[0042] A preparation process of a TMBS device comprises the following steps:

[0043] Step 1, single-wire cutting is first performed on the single crystal silicon wafer, followed by chemical mechanical polishing (CMP), followed by ultrasonic cleaning with ethanol and deionized water at room temperature for 30 seconds respectively, the frequency of ultrasonic cleaning is 100kHz, and then nitrogen blowing is performed to dry it, and it is used as a substrate material;

[0044] Step 2, forming an epitaxial layer on the upper surface of the substrate material, wherein the epitaxial layer is made of germanium bismuth selenide (prepared in the same manner as in Example 1), and is grown on the upper surface of the substrate material by chemical vapor deposition (CVD);

[0045] Step 3, the epitaxial layer is processed by etching to form an array of U-shaped grooves, each of which has a depth of 1.2 μm, a width of 0.4 μm, and a spacing of 0.6 μm between every two grooves, and then an oxide layer with a thickness of 80 nm is formed on the inner surface of the groove, and then the groove is completely filled with polysilicon;

[0046] Step 4: Set a Schottky barrier layer on the upper surface of the epitaxial layer except the groove, the material is aluminum nitride, and the thickness is 0.2μm. Then set a metal electrode copper on the Schottky barrier layer to lead out the positive electrode. At the same time, set a metal electrode copper on the lower surface of the substrate material to lead out the negative electrode, and complete the preparation of the TMBS device.

[0047] Example 3

[0048] A preparation process of a TMBS device comprises the following steps:

[0049] Step 1, single-wire cutting is first performed on the single crystal silicon wafer, followed by chemical mechanical polishing (CMP), followed by ultrasonic cleaning with ethanol and deionized water at room temperature for 60 seconds respectively, the frequency of ultrasonic cleaning is 20kHz, and then nitrogen blowing is performed to dry the wafer, and the wafer is used as a substrate material;

[0050] Step 2, forming an epitaxial layer on the upper surface of the substrate material, wherein the epitaxial layer is made of germanium bismuth selenide (prepared in the same manner as in Example 1), and is grown on the upper surface of the substrate material by chemical vapor deposition (CVD);

[0051] Step 3, the epitaxial layer is processed by etching to form an array of U-shaped grooves, each of which has a depth of 3.6 μm, a width of 0.6 μm, and a spacing of 1.2 μm between every two grooves, and then an oxide layer with a thickness of 80-160 nm is formed on the inner surface of the groove, and then the groove is completely filled with polysilicon;

[0052] Step 4: Set a Schottky barrier layer on the upper surface of the epitaxial layer except the groove, the material is titanium nitride, and the thickness is 0.7μm. Then set a metal electrode copper on the Schottky barrier layer to lead out the positive electrode. At the same time, set a metal electrode copper on the lower surface of the substrate material to lead out the negative electrode, and complete the preparation of the TMBS device.

[0053] Example 4

[0054] A preparation process of a TMBS device is different from that of Example 1 only in that the preparation process of the epitaxial layer in step 2 is different.

[0055] Wherein, in step 2, the preparation process of the epitaxial layer includes:

[0056] S1, first tetramethylgermanium (Ge(CH 3 ) 4 ), trimethylbismuth (Bi(CH 3 ) 3 ) and dimethylselenide (Se(CH 3 ) 2 ) are mixed in a container, hydrogen is introduced as a protective gas, the mass ratio of tetramethylgermanium, trimethylbismuth, dimethylselenium and hydrogen is 0.7:1.2:3:10, and the temperature is raised until all are gasified to obtain a mixed gas;

[0057] S2, placing the substrate material in the reaction chamber of the deposition equipment, introducing hydrogen after evacuation, maintaining the pressure at 150 mbar, then raising the temperature to 250°C, gradually introducing the mixed gas, then raising the temperature to 550°C, and controlling the pressure at 450 mbar;

[0058] S3. Maintaining constant temperature and pressure until the deposition thickness on the substrate material surface reaches 5 μm, stopping ventilation, and slowly lowering the temperature and pressure to normal temperature and pressure to complete the deposition of germanium bismuth selenide.

[0059] Example 5

[0060] A preparation process of a TMBS device is different from that of Example 1 only in that the preparation process of the epitaxial layer in step 2 is different.

[0061] Wherein, in step 2, the preparation process of the epitaxial layer includes:

[0062] S1, first tetramethylgermanium (Ge(CH 3 )4 ), trimethylbismuth (Bi(CH 3 ) 3 ) and dimethylselenide (Se(CH 3 ) 2 ) are mixed in a container, hydrogen is introduced as a protective gas, the mass ratio of tetramethylgermanium, trimethylbismuth, dimethylselenium and hydrogen is 1.4:2.4:8:20, and the temperature is raised until all are gasified to obtain a mixed gas;

[0063] S2, placing the substrate material in the reaction chamber of the deposition equipment, introducing hydrogen after evacuation, maintaining the pressure at 250 mbar, then raising the temperature to 350°C, gradually introducing the mixed gas, then raising the temperature to 650°C, and controlling the pressure at 550 mbar;

[0064] S3. Maintaining constant temperature and pressure until the deposition thickness on the substrate material surface reaches 15 μm, stopping ventilation, and slowly lowering the temperature and pressure to normal temperature and pressure to complete the deposition of germanium bismuth selenide.

[0065] Comparative Example 1

[0066] A TMBS device, the preparation process is different from that of Example 1 only in that the epitaxial layer in step 2 is indium nitride, and the epitaxial layer preparation process includes:

[0067] The substrate material is placed in the reaction chamber of the deposition equipment, nitrogen is introduced as a protective gas, and then ammonia (NH 3 ) and trimethylindium (In(CH 3 ) 3 ), the mass ratio of ammonia and trimethyl indium is 1.5:1.2, the temperature in the reaction chamber is controlled to be 950°C and the pressure is 600 mbar, and the heat preservation treatment is carried out until the growth thickness of the buffer layer reaches 6 μm, then the introduction of the reaction gas is stopped, and the preparation of the epitaxial layer is completed after the furnace is cooled.

[0068] Comparative Example 2

[0069] A TMBS device, the preparation process of which is different from that of Example 1 only in that the epitaxial layer in step 2 is bismuth selenide, and the epitaxial layer preparation process includes:

[0070] S1, first trimethyl bismuth (Bi(CH 3 ) 3 ) and dimethylselenide (Se(CH 3 ) 2 ) are mixed in a container, hydrogen is introduced as a protective gas, the mass ratio of trimethyl bismuth, dimethyl selenium and hydrogen is 2.9:5:15, and the temperature is raised until all are gasified to obtain a mixed gas;

[0071] S2, placing the substrate material in the reaction chamber of the deposition equipment, introducing hydrogen after evacuation, maintaining the pressure at 200 mbar, then raising the temperature to 300°C, gradually introducing the mixed gas, then raising the temperature to 600°C, and controlling the pressure to 500 mbar;

[0072] S3. Maintaining constant temperature and pressure until the deposition thickness on the substrate material surface reaches 10 μm, stopping ventilation, and slowly lowering the temperature and pressure to normal temperature and pressure to complete the deposition of bismuth selenide.

[0073] Comparative Example 3

[0074] A TMBS device, the preparation process of which is different from that of Example 1 only in that the epitaxial layer in step 2 is germanium selenide, and the epitaxial layer preparation process includes:

[0075] Wherein, in step 2, the preparation process of the epitaxial layer includes:

[0076] S1, first tetramethylgermanium (Ge(CH 3 ) 4 ) and dimethylselenide (Se(CH 3 ) 2 ) are mixed in a container, hydrogen is introduced as a protective gas, the mass ratio of tetramethylgermanium, dimethylselenium and hydrogen is 2.9:5:15, and the temperature is raised until all are gasified to obtain a mixed gas;

[0077] S2, placing the substrate material in the reaction chamber of the deposition equipment, introducing hydrogen after evacuation, maintaining the pressure at 200 mbar, then raising the temperature to 300°C, gradually introducing the mixed gas, then raising the temperature to 600°C, and controlling the pressure to 500 mbar;

[0078] S3. Maintaining constant temperature and pressure until the deposition thickness on the substrate material surface reaches 10 μm, stopping ventilation, and slowly lowering the temperature and pressure to normal temperature and pressure to complete the deposition of germanium selenide.

[0079] The performance of the TMBS devices prepared in Example 1 and Comparative Examples 1-3 was tested at a temperature of 25°C and a humidity of 55 RH%, and the conditions were: the test current density of the forward conduction voltage drop was 180 A·cm -2 , and then record the data of other parameters. The test results are shown in Table 1:

[0080] Table 1 Performance of different TMBS devices

[0081]

[0082] It can be seen from the results in Table 1 that, when used under the same conditions, compared with Comparative Examples 1-3, the TMBS device prepared in Example 1 of the present invention not only has a higher breakdown voltage, but also a lower forward voltage and a smaller leakage current density, indicating that the stability and reliability of the device are greatly enhanced.

[0083] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms should not be understood as necessarily being directed to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine different embodiments or examples described in this specification.

[0084] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A process for preparing a TMBS device, characterized in that: The following steps are involved: Step 1, cutting, polishing, cleaning and drying the silicon substrate in sequence and then using it as a substrate material; Step 2, forming an epitaxial layer on the upper surface of the substrate material, wherein the epitaxial layer is made of germanium bismuth selenide and is grown on the upper surface of the substrate material by chemical vapor deposition; Step 3, the epitaxial layer is processed by etching to form an array of U-shaped grooves, and then an oxide layer is formed on the inner surface of the grooves, and then the grooves are completely filled with polysilicon; Step 4, a Schottky barrier layer is arranged on the upper surface of the epitaxial layer except the groove, and then metal electrodes are arranged on the lower surface of the Schottky barrier layer and the substrate material respectively, and the positive and negative electrodes are led out through the metal electrodes, thus completing the preparation of the TMBS device; In step 2, the preparation process of the epitaxial layer includes: S1. Tetramethylgermanium, trimethylbismuth and dimethylselenium are first mixed in a container, hydrogen is introduced as a protective gas, and the temperature is raised until all of them are gasified to obtain a mixed gas; S2. Place the substrate material in the reaction chamber of the deposition equipment, introduce hydrogen after evacuation, maintain the pressure at 150-250 mbar, then increase the temperature to 250-350°C, gradually introduce the mixed gas, then increase the temperature to 550-650°C, and control the pressure to 450-550 mbar; S3, treating at a constant temperature and pressure until the deposition thickness on the surface of the substrate material reaches 5-15 μm, stopping ventilation, and slowly lowering the temperature and pressure to normal temperature and pressure to complete the deposition of germanium bismuth selenide; In the S1, the mass ratio of tetramethylgermanium, trimethylbismuth, dimethylselenium and hydrogen is 0.7-1.4:1.2-2.4:3-8:10-20.

2. The process for preparing a TMBS device according to claim 1, characterized in that: In the step 1, the material of the silicon substrate is one of single crystal silicon and silicon carbide.

3. The process for preparing a TMBS device according to claim 1, characterized in that: In the step 1, the cutting is single-wire cutting or multi-wire cutting, and the polishing method is chemical mechanical polishing.

4. The process for preparing a TMBS device according to claim 1, characterized in that: In the step 1, the cleaning is performed by ultrasonic washing using ethanol and deionized water in sequence, the frequency of the ultrasonic washing is 20-100 kHz, the temperature is room temperature, and the washing time is 30-60 seconds.

5. The process for preparing a TMBS device according to claim 1, characterized in that: In the step 1, the drying method is one of vacuum drying, heating drying and nitrogen blowing drying.

6. The process for preparing a TMBS device according to claim 1, characterized in that: In step 3, the thickness of the oxide layer is 80-160 nm, the depth of each groove is 1.2-3.6 μm, the width of each groove is 0.4-0.6 μm, and the distance between every two grooves is 0.6-1.2 μm.

7. The process for preparing a TMBS device according to claim 1, characterized in that: In the step 4, the material of the Schottky barrier layer is titanium nitride or aluminum nitride, and the thickness is 0.2-0.7 μm.

8. A TMBS device, characterized in that: The product is prepared by any one of the preparation processes of claims 1 to 7.

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