Chlorine-free small-size deep etching method based on InP substrate
By using a two-step plasma etching method with a CH4:H2 mixed gas on an InP substrate, the toxicity of Cl2 etching and the difficulty in removing high-temperature products in the existing technology are solved, and an etching effect with small size, high aspect ratio and low roughness is achieved, thereby improving the etching stability and surface quality.
Patent Information
- Application Number
- CN202510607938.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-13
- Publication Date
- 2025-09-23
AI Technical Summary
The existing technology uses Cl2 gas in the InP substrate etching process, which is highly toxic and difficult to remove high-temperature products, resulting in a rough etched surface with many defects, making it difficult to achieve small-size, high aspect ratio and low-roughness etching effects.
Chlorine-free etching is performed in a two-step plasma etching device using a CH4:H2 mixed gas. First, a patterned mask is formed on the hard film, and then an etched pattern groove is formed on the InP substrate. Chlorine-free etching is achieved by controlling etching parameters such as RF power, temperature and pressure.
Chlorine-free etching of small-size structures on InP substrates is achieved, with an etching effect of high aspect ratio and low roughness, avoiding the use of highly toxic gases and the generation of high-temperature products, and improving the etching stability and surface quality.
Smart Images
Figure CN120690684A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of semiconductor manufacturing, and in particular to a chlorine-free small-size deep etching method based on an InP substrate. Background Art
[0002] InP-based substrates have the advantages of good direct bandgap structure luminescence characteristics, high electron mobility, good thermal conductivity, high photoelectric conversion efficiency, wide bandgap bandwidth, high temperature resistance, and strong radiation resistance, which makes InP-based substrates used in 5G communications, data centers, new generation displays, artificial intelligence, unmanned operation, optoelectronic integrated circuit quantum devices, ultra-high-speed electronic devices and other devices.
[0003] The etching process used in device manufacturing generally needs to have the characteristics of stable and controllable etching, high anisotropy of etching profile, and smooth etching surface. 2 / Ar gas combination etches InP; because Cl2 is highly toxic, corrosive and oxidizing, there are certain risks in storage, transportation and use, and the chlorine-based reaction product InCl3 has a high vaporization temperature (570°C), which makes surface removal difficult, the etched surface rough, and forms etching defects. These factors will affect the performance of the device after etching.
[0004] Therefore, there is an urgent need for an etching method that can etch small size, high aspect ratio, and low roughness on an InP substrate without chlorine. Summary of the Invention
[0005] The purpose of the present invention is to overcome the shortcomings and deficiencies of the prior art and to provide a chlorine-free small-size deep etching method based on an InP substrate.
[0006] The purpose of the present invention is achieved through the following technical solutions: A chlorine-free small-size deep etching method based on an InP substrate comprises the following steps: (1) Providing an InP substrate, depositing a hard film on the InP substrate by chemical vapor deposition equipment or electron beam evaporation equipment; spin coating photoresist on the hard film; (2) Using electron beam lithography direct writing equipment to form a pattern of photoresist exposure and then develop; (3) etching the hard film using gas A through a first plasma etching device to form a patterned mask; (4) Using a second plasma etching device, the InP substrate is etched using gas B to form an InP etching pattern groove.
[0007] Furthermore, the hard film in step (1) comprises one of SiO2, SiNx, SiON, Cr, Ni and Al. Furthermore, the hard film in step (1) comprises one of SiO2, SiNx and Cr.
[0008] Furthermore, the process parameters of the first plasma etching equipment in step (3) are as follows: The radio frequency power of the RF radio frequency unit is 50 to 600 W; the reaction temperature on the sample stage is 0 to 60° C.; and the pressure of the reaction chamber of the plasma etching equipment is 2 to 50 mTorr.
[0009] Furthermore, the process parameters of the first plasma etching equipment in step (3) are as follows: The RF power of the RF unit is 120 to 450 W; the reaction temperature on the sample stage is 10 to 60°C; the pressure of the plasma etching equipment reaction chamber is 30 to 50 mTorr; Furthermore, the gas A in step (3) includes at least one of SF6, CF4, CHF3, O2 and Ar.
[0010] Furthermore, the gas A in step (3) is CHF3 and O2, the flow rate of CHF3 is 50 sccm; the flow rate of O2 is 5 sccm.
[0011] Furthermore, the gas A in step (3) is Ar, and the flow rate of Ar is 40 sccm.
[0012] Furthermore, before etching in step (4), the photoresist is removed using a microwave stripper and subjected to an O2 plasma treatment to prevent the photoresist residue from introducing contamination and other effects on the subsequent atomic layer etching process. In some embodiments, the photoresist is removed by wet removal.
[0013] Furthermore, the process parameters of the second plasma etching equipment in step (4) are as follows: The radio frequency power of the ICP radio frequency unit is 100 to 3000 W; the radio frequency power of the RF radio frequency unit is 200 to 600 W; the reaction temperature on the sample stage is 0 to 70°C; and the pressure of the reaction chamber of the ion etching equipment is 2 to 50 mTorr.
[0014] Furthermore, the process parameters of the second plasma etching equipment in step (4) are as follows: The radio frequency power of the ICP radio frequency unit is 180 to 300 W; the radio frequency power of the RF radio frequency unit is 200 to 250 W; the reaction temperature on the sample stage is 60 to 70°C; and the pressure in the reaction chamber of the ion etching equipment is 5 to 20 mTorr.
[0015] Furthermore, the gas B in step (4) is CH4 and H2. Furthermore, the flow rate of CH4 is 5-100 sccm: the flow rate of H2 is 5-100 sccm. Still further, the flow rate of CH4 is 30-35 sccm: the flow rate of H2 is 5-10 sccm.
[0016] The principle of etching the hard film using the first plasma etching equipment is as follows: providing lower RF power to the lower electrode and the RF radio frequency unit to excite the gas into plasma, and the plasma bombards the hard film vertically downward to form the hard patterned mask.
[0017] The principle of using the second plasma etching equipment to etch the InP substrate is as follows: provide upper RF power to the ICP radio frequency unit to convert the gas into etching plasma; provide lower RF power to the RF radio frequency unit and etch the InP substrate through the etching plasma.
[0018] The present invention has the following advantages and effects compared to the prior art: Compared to existing technologies, this application uses a CH4:H2 mixed gas to etch InP, enabling chlorine-free etching of InP. Cl2 is a highly toxic gas, and chlorine-containing etching solutions generate InCl2 products that are difficult to volatilize and remove, resulting in: a) high etching temperatures and poor process compatibility; b) surface residue after etching; and c) difficulty controlling small-scale morphologies. However, the present invention uses CH4:H2 to etch InP, enabling the etching of smaller structures with high aspect ratios and good sidewall roughness. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Figure 1 It is a schematic flow diagram of the method of the present invention.
[0020] Figure 2 This is a SEM electron microscope image of Example 1 after etching in the method of the present invention.
[0021] Figure 3 This is an AFM test result diagram of the roughness after etching in Example 1 of the method of the present invention. DETAILED DESCRIPTION
[0022] The present invention will be described in further detail below with reference to the embodiments and drawings, but the embodiments of the present invention are not limited thereto.
[0023] The equipment used in the following examples is as follows: Chemical vapor deposition equipment: Oxford-PlasmPro100PECVD and PlasmPro100ICPCVD Electron beam evaporation coating machine: Denton-Explorer4 Electron beam lithography direct writing equipment: Raith-EBPG 5150 Microwave plasma degumming machine: ASTRO PLASMA - ASTRO PACTO 10H First plasma etching equipment: Oxford-PlasmPro100RIE Second plasma etching equipment: Oxford-PlasmPro100Cobra The present invention provides a chlorine-free small-size deep etching method based on an InP substrate, comprising the following steps: A chlorine-free small-size deep etching method based on InP substrate, such as Figure 1 As shown, the following steps are included: (1) Providing an InP substrate, depositing a hard film on the InP substrate using a chemical vapor deposition device or an electron beam evaporation coating machine; and spin-coating a photoresist on the hard film; (2) Using electron beam lithography direct writing equipment to form a pattern of photoresist exposure and then develop; (3) etching the hard film using gas A through a first plasma etching device to form a patterned mask; (4) Using a second plasma etching device, the InP substrate is etched using gas B to form an InP etching pattern groove.
[0024] In some embodiments, before etching in step (4), the photoresist is removed using a microwave plasma stripper and subjected to an O2 plasma treatment to prevent the photoresist residue from introducing contamination and other effects on the subsequent atomic layer etching process. In some embodiments, the photoresist is removed by wet removal.
[0025] Example 1 A chlorine-free small-size deep etching method based on an InP substrate comprises the following steps: (1) Providing an InP substrate, depositing a SiO2 hard film on the InP substrate using a chemical vapor deposition device; and spin-coating a photoresist on the SiO2 hard film; (2) Using electron beam lithography direct writing equipment to form a pattern of photoresist exposure and then develop; (3) The SiO2 hard film was etched with CHF3 and Ar using a first plasma etching device to form a patterned mask. The process parameters of the first plasma etching device were as follows: the RF power of the RF unit was 120 W; the reaction temperature on the sample stage was 10°C; the flow rate of CHF3 was 50 sccm; the flow rate of O2 was 5 sccm; and the pressure of the plasma etching device reaction chamber was 40 mTorr. (4) Remove the photoresist and perform O2 plasma treatment; use CH4 and H2 to etch the InP substrate through the second plasma etching equipment to form InP etching pattern grooves; the process parameters of the second plasma etching equipment are as follows: the radio frequency power of the ICP radio frequency unit is 180 W; the radio frequency power of the RF radio frequency unit is 200 W; the reaction temperature on the sample stage is 70℃; the flow rate of CH4 is 30 sccm: the flow rate of H2 is 10 sccm; the pressure of the reaction chamber of the ion etching equipment is 20 mTorr.
[0026] The SEM electron microscopy results of the etched InP substrate are as follows: Figure 2 The roughness AFM test results are shown as follows Figure 3 The results show that the method of the present invention can etch a small-sized, high-aspect-ratio, low-roughness structure on an InP substrate.
[0027] Example 2 A chlorine-free small-size deep etching method based on an InP substrate comprises the following steps: (1) Providing an InP substrate, depositing a SiNx hard film on the InP substrate using a chemical vapor deposition device; and spin-coating a photoresist on the SiNx hard film; (2) Using electron beam lithography direct writing equipment to form a pattern of photoresist exposure and then develop; (3) Using a first plasma etching device, the SiNx hard film is etched with CHF3 and O2 to form a patterned mask; the RF power of the RF unit is 135 W; the reaction temperature on the sample stage is 15°C; the flow rate of CHF3 is 50 sccm; the flow rate of O2 is 5 sccm; and the pressure of the plasma etching device reaction chamber is 30 mTorr; (4) Remove the photoresist and perform O2 plasma treatment; use CH4 and H2 to etch the InP substrate through the second plasma etching equipment to form InP etching pattern grooves; the process parameters of the second plasma etching equipment are as follows: the radio frequency power of the ICP radio frequency unit is 300 W; the radio frequency power of the RF radio frequency unit is 250 W; the reaction temperature on the sample stage is 60℃; the flow rate of CH4 is 33 sccm: the flow rate of H2 is 7 sccm; the pressure of the reaction chamber of the ion etching equipment is 10 mTorr.
[0028] Example 3 A chlorine-free small-size deep etching method based on an InP substrate comprises the following steps: (1) Providing an InP substrate, depositing a Cr hard film on the InP substrate by electron beam evaporation coating equipment; spin coating a photoresist on the Cr hard film; (2) Using electron beam lithography direct writing equipment to form a pattern of photoresist exposure and then develop; (3) Using a first plasma etching device, Ar is used to etch the Cr hard film to form a patterned mask; the RF power of the RF unit is 450 W; the reaction temperature on the sample stage is 60°C; the Ar flow rate is 40 sccm; and the pressure in the plasma etching device reaction chamber is 30 mTorr; (4) Remove the photoresist and perform O2 plasma treatment; use CH4 and H2 to etch the InP substrate through the second plasma etching equipment to form InP etching pattern grooves; the process parameters of the second plasma etching equipment are as follows: the radio frequency power of the ICP radio frequency unit is 235 W; the radio frequency power of the RF radio frequency unit is 220 W; the reaction temperature on the sample stage is 60℃; the flow rate of CH4 is 35 sccm: the flow rate of H2 is 5 sccm; the pressure of the reaction chamber of the ion etching equipment is 5 mTorr.
[0029] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.
Claims
1. A chlorine-free small-size deep etching method based on an InP substrate, characterized in that: The following steps are involved: (1) Providing an InP substrate, depositing a hard film on the InP substrate using a chemical vapor deposition device; and spin-coating a photoresist on the hard film; (2) Using electron beam lithography direct writing equipment to form a pattern of photoresist exposure and then develop; (3) etching the hard film using gas A through a first plasma etching device to form a patterned mask; (4) Using a second plasma etching device, the InP substrate is etched using gas B to form an InP etching pattern groove.
2. The chlorine-free small-size deep etching method according to claim 1, characterized in that: The hard film described in step (1) includes one of SiO2, SiNx, SiON, Cr, Ni and Al.
3. The chlorine-free small-size deep etching method according to claim 1, characterized in that: The process parameters of the first plasma etching equipment in step (3) are as follows: The radio frequency power of the RF radio frequency unit is 50 to 600 W; the reaction temperature on the sample stage is 0 to 60° C.; and the pressure of the reaction chamber of the plasma etching equipment is 2 to 50 mTorr.
4. The chlorine-free small-size deep etching method according to claim 1, characterized in that: The gas A in step (3) includes at least one of SF6, CF4, CHF3, O2 and Ar.
5. The chlorine-free small-size deep etching method according to claim 4, characterized in that: The gas A described in step (3) is CHF3 and O2, the flow rate of CHF3 is 50 sccm; the flow rate of O2 is 5 sccm.
6. The chlorine-free small-size deep etching method according to claim 4, characterized in that: The gas A described in step (3) is Ar, and the flow rate of Ar is 40 sccm.
7. The chlorine-free small-size deep etching method according to claim 1, characterized in that: Before etching in step (4), the photoresist is removed using a microwave plasma stripper and O2 plasma treatment is performed.
8. The chlorine-free small-size deep etching method according to claim 1, characterized in that: The process parameters of the second plasma etching equipment in step (4) are as follows: The radio frequency power of the ICP radio frequency unit is 100 to 3000 W; the radio frequency power of the RF radio frequency unit is 200 to 600 W; the reaction temperature on the sample stage is 0 to 70°C; and the pressure of the reaction chamber of the ion etching equipment is 2 to 50 mTorr.
9. The chlorine-free small-size deep etching method according to claim 1, characterized in that: The gas B described in step (4) is CH4 and H2.
10. The chlorine-free small-size deep etching method according to claim 9, characterized in that: The flow rate of CH4 is 5 to 100 sccm; the flow rate of H2 is 5 to 100 sccm.