A method of ion-assisted chemical etching of silicon carbide

Abstract

This invention provides a method for ion-assisted chemical etching of silicon carbide, comprising the following steps: A) After annealing single-crystal silicon carbide, high-energy inert gas ions are implanted into specific patterned areas on the surface of the single-crystal silicon carbide using ion implantation to obtain ion-implanted single-crystal silicon carbide; B) The ion-implanted single-crystal silicon carbide is wet-etched, then cleaned and dried to obtain etched silicon carbide. This invention provides a method for ion-assisted chemical etching of silicon carbide. By combining ion implantation modification with chemical wet etching, ion-assisted wet etching of silicon carbide is achieved. This method can process silicon carbide etched structures at the micron and nanoscale, with high manufacturing precision. Furthermore, it requires only one ion implantation and one chemical wet etching step. The manufacturing process is simple and efficient, requiring no mask preparation, and no special conditions such as vacuum, voltage, or special gases. The process complexity is low, and the reliability is high.

Description

Technical Field

[0001] This invention belongs to the field of silicon carbide etching technology, specifically relating to a method for ion-assisted chemical etching of silicon carbide. Background Technology

[0002] Silicon carbide (SiC) is a high-performance third-generation semiconductor material. Compared to traditional semiconductor materials such as germanium and silicon, SiC offers advantages in electrical properties, including a wide bandgap, high thermal conductivity, high saturation drift velocity, and high critical electric field strength. Furthermore, SiC possesses excellent chemical stability, making it resistant to high temperatures and corrosion. This makes SiC-based semiconductor devices highly promising for applications in harsh environments such as high temperature, high frequency, high voltage, high power, and strong radiation.

[0003] However, silicon carbide is a hard and brittle material, second only to diamond in hardness, making it very difficult to machine. Furthermore, due to its excellent chemical stability, chemical etching of silicon carbide remains a challenging problem: traditional wet etching methods are ineffective. Currently, dry etching methods are mostly used to process silicon carbide, but dry etching requires several factors such as vacuum, voltage, and special gases, placing high demands on equipment structure, engineering technology, and supporting experimental conditions. It also requires the fabrication of etching masks through pre-processing steps such as photolithography and film deposition, resulting in a complex process flow, numerous processing limitations, and significant challenges in cost and quality control. Therefore, there is an urgent need to propose a novel etching method for processing silicon carbide that is simple to operate, effective, controllable, and low-cost. Summary of the Invention

[0004] In view of this, the technical problem to be solved by the present invention is to provide a method for ion-assisted chemical etching of silicon carbide. The method provided by the present invention is simple to operate, effective and controllable and low in cost.

[0005] This invention provides a method for ion-assisted chemical etching of silicon carbide, comprising the following steps:

[0006] A) After annealing single-crystal silicon carbide, high-energy inert gas ions are implanted into specific patterned regions on the surface of single-crystal silicon carbide using the ion implantation method to obtain ion-implanted single-crystal silicon carbide.

[0007] B) The ion-implanted single-crystal silicon carbide is wet-etched, then cleaned and dried to obtain etched silicon carbide.

[0008] Preferably, the annealing temperature is 800–1500°C, and the annealing time is 2 min–2 h.

[0009] Preferably, the energy of the implanted ions is 1–200 keV; the high-energy inert gas ions are selected from helium ions, neon ions, or argon ions.

[0010] Preferably, the wet etching agent is a mixed solution of 40% HF and 33% H2O2, with a volume ratio of 100:1 to 1:100, more preferably 20:1 to 1:50. The etching time is 0.5 to 72 hours, more preferably 1 to 10 hours; the solution temperature during etching is room temperature to 100°C.

[0011] Preferably, the wet etching agent is a mixed solution of 40% HF and 68% HNO3, with a volume ratio of 50:1 to 1:50, more preferably 20:1 to 1:20. The etching time is 0.5 to 72 hours, more preferably 1 to 10 hours; the solution temperature during etching is room temperature to 100°C.

[0012] Preferably, the wet etching agent is a mixed solution of 40% HF and 37% HCl, with a volume ratio of 50:1 to 1:50, more preferably 20:1 to 1:20. The etching time is 0.5 to 72 hours, more preferably 1 to 10 hours; the solution temperature during etching is room temperature to 100°C.

[0013] Preferably, the wet etching agent is a mixed solution of 40% HF and 85% H3PO4, with a volume ratio of 50:1 to 1:50, more preferably 20:1 to 1:20. The etching time is 0.5 to 72 hours, more preferably 1 to 10 hours; the solution temperature during etching is room temperature to 180°C.

[0014] Preferably, the cleaning process involves sequentially immersing the device in pure water, isopropanol, or alcohol. Drying is achieved by nitrogen blowing or natural air drying.

[0015] Compared with existing technologies, this invention provides a method for ion-assisted chemical etching of silicon carbide, comprising the following steps: A) After annealing single-crystal silicon carbide, high-energy inert gas ions are implanted into specific patterned regions on the surface of the single-crystal silicon carbide using ion implantation to obtain ion-implanted single-crystal silicon carbide; B) The ion-implanted single-crystal silicon carbide is wet-etched, then cleaned and dried to obtain etched silicon carbide. This invention provides a method for ion-assisted chemical etching of silicon carbide. By combining ion implantation modification with chemical wet etching, ion-assisted wet etching of silicon carbide is achieved. This method can process silicon carbide etched structures at the micron and nanoscale, with high manufacturing precision. Furthermore, it requires only one ion implantation and one chemical wet etching. Compared with the currently common dry etching process for silicon carbide, this method has a simpler manufacturing process, higher efficiency, no need for mask preparation, and no need for vacuum, voltage, special gas, or other conditions. It also has low process complexity and high reliability. Attached Figure Description

[0016] Figure 1 A flowchart of the ion-assisted etching method for silicon carbide provided by the present invention;

[0017] Figure 2 A schematic diagram of the process steps of the ion-assisted etching method for silicon carbide provided by the present invention;

[0018] Figure 3 This is a high-resolution image of the completed process in Example 1;

[0019] Figure 4 This is a high-resolution image of the completed process in Example 2;

[0020] Figure 5 This is a high-resolution image of the completed process in Example 3. Detailed Implementation

[0021] This invention provides a method for ion-assisted chemical etching of silicon carbide, comprising the following steps:

[0022] A) After annealing single-crystal silicon carbide, high-energy inert gas ions are implanted into specific patterned regions on the surface of single-crystal silicon carbide using the ion implantation method to obtain ion-implanted single-crystal silicon carbide.

[0023] B) The ion-implanted single-crystal silicon carbide is wet-etched, then cleaned and dried to obtain etched silicon carbide.

[0024] This invention uses single-crystal silicon carbide as the substrate, and firstly, the single-crystal silicon carbide undergoes annealing. The invention does not impose any particular limitation on the annealing apparatus; it can be an annealing furnace, a rapid thermal annealing machine, an oxidation furnace, or LPCVD. In this invention, the annealing temperature is 800–1500°C, preferably 800, 900, 1000, 1100, 1200, 1300, 1400, or 1500°C, or any value between 800 and 1500°C; the annealing time is 2 min–120 min, preferably 2, 3, 4, 5, 8, 10, 30, 60, 90, or 120 min, or any value between 2 min and 120 min.

[0025] Then, high-energy inert gas ions are implanted into specific patterned regions on the surface of single-crystal silicon carbide using the ion implantation method to obtain ion-implanted single-crystal silicon carbide.

[0026] The ion beam implantation method refers to the implantation of high-energy inert gas ions with a certain energy into a specific patterned region of a sample using an ion implantation device. The ion implantation device is selected from a focused ion beam microscope or an ion implanter, with the focused ion beam microscope preferably being a helium ion microscope. The shape of the specific patterned region of the implanted sample can be a straight line, curve, rectangle, circle, ring, polygon, or irregular shape, and the planar size can be 10 nm to 500 μm, preferably 10 nm, 50 nm, 100 nm, 500 nm, 1 μm, 5 μm, 10 μm, 50 μm, 100 μm, 200 μm, 500 μm, or any value between 10 nm and 500 μm. The ion energy is 1 to 200 keV, preferably 1, 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 120, 140, 160, 180, 200, or any value between 1 and 200 keV. The high-energy inert gas ions are selected from helium ions, neon ions, or argon ions. The etching depth / ion implantation depth is determined by the ion energy. In this invention, the etching depth corresponding to an ion energy of 1-200 keV is 1-800 nm, preferably 1, 5, 10, 50, 100, 200, 500, 800, or any value between 1 and 800 nm.

[0027] After obtaining ion-implanted single-crystal silicon carbide, the ion-implanted single-crystal silicon carbide is subjected to wet etching. Preferably, the wet etching is chemical wet etching.

[0028] In some specific embodiments of the present invention, the wet etching agent is a mixed solution of 40% HF and 33% H2O2, with a volume ratio of 100:1 to 1:100, preferably 20:1 to 1:50. The etching time is 0.5 to 72 hours, preferably 1 to 10 hours; the solution temperature during etching is room temperature to 100°C.

[0029] In some specific embodiments of the present invention, the wet etching agent is a mixed solution of 40% HF and 68% HNO3, with a volume ratio of 50:1 to 1:50, preferably 20:1 to 1:20. The etching time is 0.5 to 72 hours, preferably 1 to 10 hours; the solution temperature during etching is room temperature to 100°C.

[0030] In some specific embodiments of the present invention, the wet etching agent is a mixed solution of 40% HF and 37% HCl, with a volume ratio of 50:1 to 1:50, preferably 20:1 to 1:20. The etching time is 0.5 to 72 hours, preferably 1 to 10 hours; the solution temperature during etching is room temperature to 100°C.

[0031] In some specific embodiments of the present invention, the wet etching agent is a mixed solution of 40% HF and 85% H3PO4, with a volume ratio of 50:1 to 1:50, preferably 20:1 to 1:20. The etching time is 0.5 to 72 hours, preferably 1 to 10 hours; the solution temperature during etching is room temperature to 180°C.

[0032] Finally, the single-crystal silicon carbide is cleaned and dried. This invention does not impose any particular limitation on the cleaning and drying methods; any cleaning and drying methods known to those skilled in the art are acceptable.

[0033] In this invention, the cleaning process involves sequentially immersing the device in pure water, isopropanol, or alcohol. Drying is achieved by either nitrogen blowing or natural air drying.

[0034] This invention provides a novel etching method for silicon carbide, combining ion implantation modification with wet chemical etching to achieve ion-assisted chemical etching of silicon carbide. This method features a simple and efficient fabrication process, requiring no mask preparation or specific conditions such as vacuum, voltage, or special gases. It also boasts low process complexity and high reliability. It can be used for the fabrication of silicon carbide micro / nano structures and devices.

[0035] See Figures 1-2 , Figure 1 A flowchart of the ion-assisted etching method for silicon carbide provided by the present invention. Figure 2 This diagram illustrates the process steps of the ion-assisted etching method for silicon carbide provided by the present invention. Specifically, firstly, the single-crystal silicon carbide substrate 1 is annealed. Then, a high-energy inert gas ion beam 2 is used to implant the desired positions and patterns onto the silicon carbide surface. Due to the interaction between the inert gas ions and the silicon carbide, the single-crystal silicon carbide directly below the implantation point undergoes denaturation, forming an amorphous region 3. Next, a wet etchant is used to selectively etch region 3, and the sample is cleaned and dried to remove residual wet etchant, ultimately obtaining the etched structure 4.

[0036] This invention provides a method for ion-assisted chemical etching of silicon carbide. By combining ion implantation modification with chemical wet etching, ion-assisted wet etching of silicon carbide is achieved. This method can process silicon carbide etched structures at the micron and nanoscale, achieving high manufacturing precision. Furthermore, it requires only one ion implantation and one chemical wet etching step. Compared to the commonly used dry etching process for silicon carbide, this method has a simpler manufacturing process, higher efficiency, eliminates the need for mask preparation, and does not require vacuum, voltage, or special gases. It also features lower process complexity and higher reliability.

[0037] To further understand the present invention, the method for ion-assisted chemical etching of silicon carbide provided by the present invention will be described below with reference to embodiments. The scope of protection of the present invention is not limited by the following embodiments.

[0038] Example 1:

[0039] Step 1: Anneal the single-crystal silicon carbide.

[0040] Step 2: High-energy inert gas ions are implanted into specific locations on the surface of single-crystal silicon carbide using an ion implantation method.

[0041] Step 3: Use a wet etchant to etch the sample obtained in Step 1 to form an etched structure corresponding to the shape of the ion implantation region.

[0042] Step 4: Clean and dry the sample obtained in Step 3 to remove residual wet etching agent.

[0043] In step 1, the annealing of single-crystal silicon carbide is performed by annealing the silicon carbide using a rapid thermal annealing machine at a temperature of 900°C for a time of 4 minutes.

[0044] In step 2, the ion beam implantation method involves injecting high-energy helium ions into a specific region of the sample using a helium ion microscope. The ion energy is 30 keV. The substrate material is single-crystal silicon carbide.

[0045] In step 3, the wet etching agent is a mixed solution of 40% HF and 33% H₂O₂ in a volume ratio of 1:5. The etching time is 3 hours, and the temperature is 80°C. The resulting etched structure is shown below. Figure 3 As shown, Figure 3 The image shown is a high-resolution image of the processed area in Example 1. The ion implantation region is a square with a side length of 1 μm.

[0046] In step 4, the cleaning method involves immersing the item in pure water followed by isopropanol. The drying method involves blowing the item with nitrogen gas.

[0047] Example 2:

[0048] Step 1: Anneal the single-crystal silicon carbide.

[0049] Step 2: High-energy inert gas ions are implanted into specific locations on the surface of single-crystal silicon carbide using an ion implantation method.

[0050] Step 3: Use a wet etchant to etch the sample obtained in Step 1 to form an etched structure corresponding to the shape of the ion implantation region.

[0051] Step 4: Clean and dry the sample obtained in Step 3 to remove residual wet etching agent.

[0052] In step 1, the annealing of single-crystal silicon carbide is performed by annealing the silicon carbide using a rapid thermal annealing machine at a temperature of 900°C for a time of 4 minutes.

[0053] In step 2, the ion beam implantation method involves injecting high-energy helium ions into a specific region of the sample using a helium ion microscope. The ion energy is 10 keV. The substrate material is single-crystal silicon carbide.

[0054] In step 3, the wet etching agent is a mixed solution of 40% HF and 33% H₂O₂, with a volume ratio of 1:20. The etching time is 8 hours, and the temperature is 80℃. The resulting etched structure is shown below. Figure 4 As shown, Figure 4 The image shown is a high-resolution image after processing in Example 2. The ion implantation region is a straight line with a width that gradually increases from 10 nm to 200 nm from left to right (the edges of the lines are widened to a certain extent after etching) and a length of 5 μm.

[0055] In step 4, the cleaning method involves immersing the item in pure water followed by isopropanol. The drying method involves blowing the item with nitrogen gas.

[0056] Example 3:

[0057] Step 1: Anneal the single-crystal silicon carbide.

[0058] Step 2: High-energy inert gas ions are implanted into specific locations on the surface of single-crystal silicon carbide using an ion implantation method.

[0059] Step 3: Use a wet etchant to etch the sample obtained in Step 1 to form an etched structure corresponding to the shape of the ion implantation region.

[0060] Step 4: Clean and dry the sample obtained in Step 2 to remove residual wet etching agent.

[0061] In step 1, the annealing of single-crystal silicon carbide is performed by annealing the silicon carbide using a rapid thermal annealing machine at a temperature of 900°C for a time of 4 minutes.

[0062] In step 2, the ion beam implantation method involves injecting high-energy neon ions into a specific region of the sample using a focused ion beam microscope. The ion energy is 40 keV. The substrate material is single-crystal silicon carbide.

[0063] In step 3, the wet etching agent is a mixed solution of 40% HF and 68% HNO3, with a volume ratio of 10:1. The etching time is 0.5 h, and the temperature is 95 °C. The resulting etched structure is shown below. Figure 5 As shown, Figure 5 The image shown is a high-resolution image of the processed area in Example 3. The ion implantation area consists of a square with a side length of 2 μm and a rectangle with a side length of 2 μm × 1 μm.

[0064] In step 4, the cleaning method involves immersing the item in pure water followed by anhydrous ethanol. The drying method is natural air drying.

[0065] Example 4:

[0066] Step 1: Anneal the single-crystal silicon carbide.

[0067] Step 2: High-energy inert gas ions are implanted into specific locations on the surface of single-crystal silicon carbide using an ion implantation method.

[0068] Step 3: Use a wet etchant to etch the sample obtained in Step 1 to form an etched structure corresponding to the shape of the ion implantation region.

[0069] Step 4: Clean and dry the sample obtained in Step 3 to remove residual wet etching agent.

[0070] In step 1, the annealing of single-crystal silicon carbide is performed by annealing the silicon carbide using a rapid thermal annealing machine at a temperature of 900°C for a time of 4 minutes.

[0071] In step 2, the ion beam implantation method involves using an ion implanter to implant high-energy helium ions into a specific region of the sample. The ion energy is 150 keV. The substrate material is single-crystal silicon carbide.

[0072] In step 3, the wet etching agent is a mixed solution of 40% HF and 37% HCl, with a volume ratio of 1:1. The etching time is 1 hour, and the temperature is 70°C.

[0073] In step 4, the cleaning method involves sequentially immersing in pure water and then cleaning with IPA. The drying method is nitrogen blowing.

[0074] Example 5:

[0075] Step 1: Anneal the single-crystal silicon carbide.

[0076] Step 2: High-energy inert gas ions are implanted into specific locations on the surface of single-crystal silicon carbide using an ion implantation method.

[0077] Step 3: Use a wet etchant to etch the sample obtained in Step 1 to form an etched structure corresponding to the shape of the ion implantation region.

[0078] Step 4: Clean and dry the sample obtained in Step 3 to remove residual wet etching agent.

[0079] In step 1, the annealing of single-crystal silicon carbide is performed by annealing the silicon carbide using a rapid thermal annealing machine at a temperature of 900°C for a time of 4 minutes.

[0080] In step 2, the ion beam implantation method involves using an ion implanter to implant high-energy argon ions into a specific region of the sample. The ion energy is 80 keV. The substrate material is single-crystal silicon carbide. The implanted region is a square with a side length of 200 μm.

[0081] In step 3, the wet etching agent is a mixed solution of 40% HF and 33% H2O2, with a volume ratio of 1:1. The etching time is 24 hours, and the temperature is 85℃.

[0082] In step 4, the cleaning method involves sequentially immersing in pure water and then cleaning with IPA. The drying method is nitrogen blowing.

[0083] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method of ion-assisted chemical etching of silicon carbide, characterized in that, The method comprises the following steps: A) after annealing treatment of single crystal silicon carbide, high-energy inert gas ions are injected into specific pattern areas on the surface of the single crystal silicon carbide by ion implantation, to obtain ion-implanted single crystal silicon carbide; due to the interaction between the inert gas ions and the silicon carbide, the single crystal silicon carbide directly below the injection point is denatured to form an amorphous region; the annealing temperature is 800-1000°C, the annealing time is 2-5 minutes, and the annealing device is selected from an annealing furnace, a rapid thermal annealing machine, an oxidation furnace or an LPCVD; the ion energy of the ion implantation is 1-80 keV; the high-energy inert gas ions are selected from helium ions, neon ions or argon ions; B) after wet etching of the amorphous region of the ion-implanted single crystal silicon carbide, cleaning and drying are performed to obtain etched silicon carbide, and the etching depth is 1-800 nm; the wet etching agent for the wet etching is a 40% HF and 33% H2O2 mixed solution with a volume ratio of 100:1-1:100, the etching time is 0.5-72 hours, and the solution temperature during etching is room temperature-100°C; or the wet etching agent for the wet etching is a 40% HF and 68% HNO3 mixed solution with a volume ratio of 50:1-1:50, the etching time is 0.5-72 hours, and the solution temperature during etching is room temperature-100°C.

2. The method of claim 1, wherein, The wet etching agent for the wet etching is a 40% HF and 33% H2O2 mixed solution with a volume ratio of 20:1-1:50, and the etching time is 1-10 hours.

3. The method of claim 1, wherein, The wet etching agent for the wet etching is a 40% HF and 68% HNO3 mixed solution with a volume ratio of 20:1-1:20, and the etching time is 1-10 hours.

4. The method of claim 1, wherein, The cleaning is soaking in pure water, isopropyl alcohol or alcohol in sequence, and the drying method is nitrogen blowing or natural air drying.

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