A novel silicon carbide device based on laser graphitization technology and preparation method

Abstract

The present invention belongs to the technical field of semiconductor device preparation, and discloses a new type of silicon carbide device based on laser graphitization technology and a preparation method, including a high-resistance silicon carbide single crystal, a silicon dioxide protective layer, a metal electrode, a connecting electrode and a lead electrode; the metal electrode is located inside the high-resistance silicon carbide single crystal; the silicon dioxide protective layer is arranged around the metal electrode, covering the upper surface of the high-resistance silicon carbide single crystal in the area where the non-metallic electrode is located, ensuring that the high-resistance silicon carbide single crystal and the metal electrode are in the same plane; the connecting electrode is located on the metal electrode, ensuring that the connecting electrode and the silicon dioxide protective layer are in the same plane; the lead electrode is located on the upper surface of the connecting electrode and the silicon dioxide protective layer. The present invention designs a new type of silicon carbide device and proposes an effective and simple process manufacturing technology, which solves the preparation and performance problems of silicon carbide-based high-energy particle and ray detectors, and realizes the development of a new type of silicon carbide radiation detector.

Description

Technical Field

[0001] The invention belongs to the technical field of semiconductor device preparation, and relates to a novel silicon carbide device based on laser graphitization technology and a preparation method thereof. Background Art

[0002] Silicon carbide is a third-generation wide bandgap semiconductor material with a bandgap of 3.2eV and a breakdown electric field of 2.2MV / cm, which is significantly higher than silicon-based materials. The electron saturation velocity is 2.0×10 7 cm / s can reach twice that of silicon, which means that silicon carbide devices can withstand higher operating voltages, have reduced carrier drift time, lower carrier recombination probability and higher time resolution than silicon-based devices, and are ideal materials for preparing semiconductor detectors. The silicon carbide devices currently prepared by people are all based on planar structures, and are mainly prepared by the following two methods: First, the device is prepared based on the homogeneous epitaxy of silicon carbide single crystals. This type of device has high detector energy resolution under full deposition conditions, but the voltage required for full depletion of the epitaxial layer is large and high-quality epitaxial substrates are expensive and difficult to obtain. Second, compared with epitaxially grown silicon carbide devices, silicon carbide single crystal devices have lower costs, but the carrier collection distance is too long. If the sample is thinned to shorten the collection distance, surface defects and self-support problems need to be solved. Nowadays, with the increasing requirements for the performance of semiconductor detectors, traditional two-dimensional structures are no longer sufficient to meet scientific research needs. Three-dimensional silicon carbide devices using laser etching technology have the advantages of low processing cost, fast etching rate, controllable carrier collection distance, and diversified structures. After laser processing, a layer of graphite is formed on the etching interface of a silicon carbide single crystal sample, and the metal electrode in contact with the graphite is an ohmic contact. To this end, the present invention innovatively proposes a new type of silicon carbide device based on laser graphitization technology and a preparation method thereof. Summary of the invention

[0003] The purpose of the present invention is to propose a new silicon carbide device and preparation method based on laser graphitization technology in response to the many technical difficulties faced in the process of preparing the above-mentioned silicon carbide high-energy particle or ray detector.

[0004] The technical solution of the present invention:

[0005] A novel silicon carbide device based on laser graphitization technology comprises a high-resistance silicon carbide single crystal 1, a silicon dioxide protective layer 2, a metal electrode 3, a connecting electrode 4 and a lead electrode 5;

[0006] The high-resistance silicon carbide single crystal wafer 1 is the main structure;

[0007] The metal electrode 3 is located inside the high-resistance silicon carbide single crystal wafer 1;

[0008] The silicon dioxide protective layer 2 is arranged around the metal electrode 3, covering the upper surface of the high-resistance silicon carbide single crystal wafer 1 in the area where the non-metallic electrode 3 is located, ensuring that the high-resistance silicon carbide single crystal wafer 1 and the metal electrode 3 are in the same plane;

[0009] The connecting electrode 4 is located on the metal electrode 3, ensuring that the connecting electrode 4 and the silicon dioxide protective layer 2 are in the same plane;

[0010] The lead electrode 5 is located on the upper surface of the connection electrode 4 and the silicon dioxide protection layer 2 .

[0011] A method for preparing a new type of silicon carbide device based on laser graphitization technology, the steps are as follows:

[0012] Step 1: On a high-resistance silicon carbide single crystal wafer 1, a through-hole array is prepared by using a pulsed laser, the through-hole diameter is 1 μm to 500 μm, the cathode and anode arrays are arranged alternately, the spacing between anodes in the same row is 5 μm to 300 μm, the spacing between cathodes in the same row is 5 μm to 300 μm, and the spacing between adjacent cathodes and anodes is 10 μm to 800 μm;

[0013] Step 2: Use a mixed solution of hydrofluoric acid and deionized water to ultrasonicate for 5 to 20 minutes to remove the byproducts after laser processing;

[0014] Step 3: using electrochemical metal deposition technology to prepare the metal electrode 3 in the through hole, and using chemical mechanical polishing technology to make the electrochemically deposited metal electrode 3 and the surface of the high-resistance silicon carbide single crystal wafer 1 in the same plane;

[0015] Step 4: using microwave plasma chemical vapor deposition technology to deposit a 10nm-600nm silicon dioxide protective layer 2 on the surface of the high-resistance silicon carbide single crystal wafer 1;

[0016] Step 5: Using photolithography technology, a window is opened at the position where the through hole is located, and the silicon dioxide protective layer 2 is etched using a hydrofluoric acid solution;

[0017] Step 6: Prepare the connection electrode 4 by thermal evaporation or electron beam evaporation, the thickness of which is not less than the thickness of the deposited silicon dioxide, and then use CMP technology to keep the connection electrode 4 at the same height as the silicon dioxide layer 2;

[0018] Step 7: Use photolithography technology to make lead electrodes 5.

[0019] Beneficial effects of the invention: The invention designs a new silicon carbide device structure and preparation method based on laser graphitization technology, and proposes an effective and simple process manufacturing technology, which solves the preparation and performance problems of silicon carbide-based high-energy particle and ray detectors, and realizes the development of new silicon carbide radiation detectors. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic diagram of the structure of a new type of silicon carbide device based on laser graphitization.

[0021] Figure 2 This is a top view of the structure of a new type of silicon carbide device based on laser graphitization.

[0022] In the figure: 1 high-resistance silicon carbide single crystal; 2 silicon dioxide protective layer; 3 metal electrode; 4 connecting electrode; 5 lead electrode. DETAILED DESCRIPTION

[0023] The specific implementation of the present invention is further described below in conjunction with the technical scheme and the accompanying drawings.

[0024] Example 1

[0025] This embodiment provides a novel silicon carbide device and a preparation method based on laser graphitization technology, including the following process steps:

[0026] Step 1: Select a high-resistance silicon carbide single crystal wafer 1 with a thickness of 350 μm and a surface area of ​​5 mm square;

[0027] Step 2: On the high-resistance silicon carbide single crystal wafer 1, a through hole with a high true aspect ratio is produced by repeatedly changing the focus of the laser processing equipment, and the hole diameter is 50 um;

[0028] Step 3: Clean the processed sample with hydrofluoric acid solution;

[0029] Step 4: Use electrochemical electrode metal technology to fill the through hole with metal electrode 3, and then use CMP technology to remove excess metal;

[0030] Step 5: Using microwave plasma chemical vapor deposition technology, a silicon dioxide protective layer 2 with a thickness of 200 nm is deposited on the upper and lower surfaces of the high-resistance silicon carbide single crystal 1. Photolithography is performed on the upper surface to open a window above the metal electrode 3, and then the silicon dioxide protective layer 2 is etched with a hydrofluoric acid solution to the same height as the upper surface of the metal electrode 3;

[0031] Step 6: Use electron beam deposition to deposit metal at the window to prepare the connecting electrode 4; the thickness is not less than 200nm, and then use CMP technology to remove excess metal on the surface of the silicon dioxide protective layer 2.

[0032] Step 7: Use photolithography to connect the electrodes on the silicon dioxide protective layer 2 to make lead electrodes 5.

Claims

1. A silicon carbide device based on laser graphitization technology, the silicon carbide device comprising a high-resistance silicon carbide single crystal (1), a silicon dioxide protective layer (2), a metal electrode (3), a connecting electrode (4) and a lead electrode (5); The high-resistance silicon carbide single crystal wafer (1) is the main structure; The metal electrode (3) is located inside the high-resistance silicon carbide single crystal wafer (1); The silicon dioxide protective layer (2) is arranged around the metal electrode (3) and covers the upper surface of the high-resistance silicon carbide single crystal wafer (1) in the area where the non-metal electrode (3) is located, ensuring that the high-resistance silicon carbide single crystal wafer (1) and the metal electrode (3) are on the same plane; The connecting electrode (4) is located on the metal electrode (3), ensuring that the connecting electrode (4) and the silicon dioxide protective layer (2) are on the same plane; The lead electrode (5) is located on the upper surface of the connecting electrode (4) and the silicon dioxide protective layer (2); It is characterized in that Here are the steps: Step 1: On a high-resistance silicon carbide single crystal wafer (1), a through hole array is prepared by using a pulsed laser, the through hole diameter is 1 μm to 500 μm, the cathode and anode arrays are arranged alternately, the spacing between anodes in the same row is 5 μm to 300 μm, the spacing between cathodes in the same row is 5 μm to 300 μm, and the spacing between adjacent cathodes and anodes is 10 μm to 800 μm; Step 2: Use a mixed solution of hydrofluoric acid and deionized water to ultrasonicate for 5 to 20 minutes to remove the byproducts after laser processing; Step 3: using electrochemical metal deposition technology to prepare the metal electrode (3) in the through hole, and using chemical mechanical polishing technology to make the electrochemically deposited metal electrode (3) and the surface of the high-resistance silicon carbide single crystal (1) on the same plane; Step 4: using microwave plasma chemical vapor deposition technology to deposit a 10nm to 600nm silicon dioxide protective layer (2) on the surface of the high-resistance silicon carbide single crystal wafer (1); Step 5: using photolithography technology to open windows at locations with through holes, and etching the silicon dioxide protective layer (2) using a hydrofluoric acid solution; Step 6: Prepare the connection electrode (4) by thermal evaporation or electron beam evaporation, the thickness of which is not less than the thickness of the deposited silicon dioxide, and then use CMP technology to keep the connection electrode (4) at the same height as the silicon dioxide layer 2; Step 7: Use photolithography technology to make lead electrodes (5).

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