Cadmium zinc telluride substrate pretreatment method for molecular beam epitaxy
Through a pretreatment method for pre-treatment of zinc tellurium substrates with molecular beam epitaxial including multi-step chemical corrosion and heat treatment, the inconsistency caused by substrate surface damage, polishing reagent residues and oxides is solved, and the uniformity of surface state and high-quality growth of epitaxial layer are achieved.
Patent Information
- Application Number
- CN202411686399.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-25
- Publication Date
- 2025-04-11
AI Technical Summary
In the prior art, surface damage to the zinc tellurium cadmium tellurium substrate for epitaxial use, residual polishing reagents and surface oxides lead to inconsistent surface states, affecting the quality of the epitaxial film.
A pretreatment method for molecular beam epitaxial with a zinc tellurium substrate, including soaking and rinsing through a methanol solution, performing three steps of chemical corrosion: the first step is to use a mixed solution of hydrofluoric acid and hydrochloric acid, the second step is to use a mixed solution of bromine and methanol, the third step is to use a mixed solution of hydrogen peroxide and ammonia, and heat after the third step to remove surface oxides.
By improving the type, concentration and time of cleaning reagents, the substrate surface is treated with chemical corrosion liquid to achieve consistency between surface oxides and chemical states, and further reconstitute surface atoms by heat treatment to meet the standards for growing epitaxial mercury cadmium tellurium materials.
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Figure CN119800512A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the field of semiconductor technology, and in particular to a method for pretreating a cadmium zinc telluride substrate for molecular beam epitaxy. Background Art
[0002] After CdZnTe crystals are processed through cutting, grinding, chemical polishing and other processes, there will be a damaged layer on the surface of the substrate. For the molecular beam epitaxy process, the damage to the substrate or surface defects and polishing reagent residues will extend to the epitaxial film, and as the thickness of the epitaxial film increases, the surface defects will increase. At the same time, after polishing, the surface of the substrate is very susceptible to oxidation reaction in the air, and the formation of oxides makes it impossible to perform thin film epitaxy on it. Therefore, before epitaxy, the CdZnTe substrate needs to undergo appropriate cleaning or pretreatment processes to remove the damaged layer, reagent residues, and form an easily removable surface oxide layer.
[0003] At present, the treatment of CdZnTe substrates for molecular beam epitaxy before growth is usually a one-step bromine methanol solution to corrode the CdZnTe to obtain a tellurium-rich surface, and then directly enter the growth chamber for epitaxy. However, bromine methanol corrosion will cause the CdZnTe surface to have a large orange peel-like roughness. VGIVANITS'KA et al. studied iodic acid system corrosion solutions, using hydrogen peroxide, citric acid, and iodic acid to remove the oxide layer on the surface of CdZnTe. The corrosion effect is better than that of simple bromine methanol solution, and the surface atomic layer is more uniform. However, iodine is easier to precipitate in iodine-based solutions, resulting in changes in solution concentration during processing and scratches on the substrate surface caused by precipitates, and it has not been widely used. Summary of the invention
[0004] The embodiment of the present application provides a method for pretreating a CdZnTe substrate for molecular beam epitaxy in view of the inconsistent surface state of the CdZnTe substrate caused by surface damage, polishing agent residue, surface oxides and different oxidation degrees of the CdZnTe substrate for molecular beam epitaxy in the prior art.
[0005] The present application provides a method for pretreating a cadmium zinc telluride substrate for molecular beam epitaxy, comprising:
[0006] The cadmium zinc telluride substrate is immersed and rinsed in a methanol solution;
[0007] The washed cadmium zinc telluride substrate is subjected to a first step of chemical etching, wherein the etching solution of the first step of chemical etching is a mixed solution of a hydrofluoric acid solution and a hydrochloric acid solution;
[0008] After the first step of chemical etching, soak, rinse and blow dry;
[0009] Performing a second step of chemical etching, wherein the etching solution of the second step of chemical etching is a mixed solution of a bromine solution and a methanol solution;
[0010] After the second step of chemical etching, the process is dried, and then the third step of chemical etching is performed, wherein the third step of chemical etching is a mixed solution of hydrogen peroxide solution and ammonia solution;
[0011] After the third step of chemical etching, the CdZnTe substrate is heated until the surface oxide is removed to meet the requirements.
[0012] Optionally, the volume ratio of the hydrofluoric acid solution to the hydrochloric acid solution in the etching solution for performing the first step of chemical etching is 1:5-1:1.
[0013] Optionally, the concentration of bromine methanol in the bromine solution and methanol solution used in the second step of chemical etching is 0.005%-5%.
[0014] Optionally, the volume ratio of the hydrogen peroxide solution to the ammonia solution in the third step of chemical etching is 10:1-1:1.
[0015] Optionally, heating the CdZnTe substrate after the third step of chemical etching includes:
[0016] The cadmium zinc telluride substrate is heated by a gradual heating method, a first heating rate is configured, and after heating to a first target temperature, the temperature is maintained for a set time, and then the temperature is heated to a second target temperature using a second heating rate, wherein the first heating rate is greater than the second heating rate.
[0017] Optionally, after the first step of chemical etching, the following steps may be specifically performed:
[0018] The CdZnTe substrate obtained by chemical etching in the first step is transferred to a methanol solution for immersion and rinsing, and then the CdZnTe substrate is blown dry using a nitrogen gun.
[0019] Optionally, after performing the third step of chemical etching, the following steps may also be performed:
[0020] After the third step of chemical etching, the CdZnTe substrate is rinsed with a methanol solution, blown dry, and then transferred to a molecular beam epitaxy processing chamber to perform a heating step.
[0021] The embodiments of the present application improve the damaged layer and surface oxide by changing parameters such as the type, concentration, and cleaning time of the cleaning reagent, and use a chemical etching solution to treat the surface oxide and chemical state of the cadmium zinc telluride substrate to be consistent, and then heat treat the substrate to reconstruct the surface atoms through the heat treatment to meet the standards for growing an epitaxial layer of mercury cadmium telluride material.
[0022] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS
[0023] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present application. Also, the same reference symbols are used throughout the accompanying drawings to represent the same components. In the accompanying drawings:
[0024] Figure 1 The basic process diagram of the method for pretreating a cadmium zinc telluride substrate for molecular beam epitaxy according to an embodiment of the present application is shown;
[0025] Figure 2 An initial RHEED image of the surface of a CdZnTe substrate used as an example of the present application;
[0026] Figure 3 This is a RHEED image of the surface of a CdZnTe substrate after pretreatment, which is an example of the application of this application. DETAILED DESCRIPTION
[0027] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.
[0028] The present application provides a method for pretreating a cadmium zinc telluride substrate for molecular beam epitaxy. Figure 1 As shown, the following steps are included:
[0029] In step S101, the CdZnTe substrate is immersed and rinsed in a methanol solution.
[0030] In step S102, the washed CdZnTe substrate is subjected to a first chemical etching step, wherein the etching solution of the first chemical etching step is a mixed solution of hydrofluoric acid solution and hydrochloric acid solution. The first chemical etching step is used to remove polishing solution residues on the surface of the CdZnTe substrate, such as silicon dioxide particles.
[0031] In step S103, after the first step of chemical etching, soaking, rinsing and drying are performed.
[0032] In step S104, a second step of chemical etching is performed, wherein the etching solution of the second step of chemical etching is a mixed solution of bromine solution and methanol solution. The second step of chemical etching is used to remove the mechanical damage layer of the substrate processing and the tellurium oxide on the surface of the substrate after processing.
[0033] In step S105, the second step of chemical etching is followed by drying, and then the third step of chemical etching is performed, wherein the third step of chemical etching is a mixed solution of hydrogen peroxide solution and ammonia solution. The third step of chemical etching is used to form oxides on the surface of the cadmium zinc telluride substrate, and the oxide content and valence state are consistent.
[0034] In step S106, after the third step of chemical etching, the CdZnTe substrate is heated until the surface oxide is removed to meet the requirement.
[0035] The embodiments of the present application improve the damaged layer and surface oxide by changing parameters such as the type, concentration, and cleaning time of the cleaning reagent, and use a chemical etching solution to treat the surface oxide and chemical state of the cadmium zinc telluride substrate to be consistent, and then heat treat the substrate to reconstruct the surface atoms through the heat treatment to meet the standards for growing an epitaxial layer of mercury cadmium telluride material.
[0036] In some embodiments, after the first step of chemical etching, the method further includes: transferring the CdZnTe substrate after the first step of chemical etching to a methanol solution for immersion and rinsing, and then drying the CdZnTe substrate with a nitrogen gun.
[0037] In some embodiments, the volume ratio of the hydrofluoric acid solution to the hydrochloric acid solution in the etching solution for performing the first step of chemical etching is 1:5-1:1.
[0038] In some embodiments, the concentration of bromine methanol mixed with bromine solution and methanol solution in the second step of chemical etching is 0.005%-5%. Bromine methanol solution is prepared by mixing methanol and bromine, and the dosage of the two is adjusted according to the concentration requirements.
[0039] In some embodiments, the volume ratio of the hydrogen peroxide solution to the ammonia solution in the third step of chemical etching is 10:1-1:1.
[0040] In some embodiments, after performing the third step of chemical etching, the method further includes: rinsing the CdZnTe substrate after the third step of chemical etching with a methanol solution, drying it, and transferring it to a molecular beam epitaxy processing chamber to perform a heating step.
[0041] In some embodiments, heating the CdZnTe substrate after the third chemical etching step includes:
[0042] The cadmium zinc telluride substrate is heated by a stepwise heating method, a first heating rate is configured, and after heating to the first target temperature, the temperature is maintained for a set time, and then the temperature is increased to the second target temperature using a second heating rate, wherein the first heating rate is greater than the second heating rate. For example, the cadmium zinc telluride substrate is heated by a stepwise heating method, the heating rate is 20°C / min, and after heating to 280°C, the temperature is maintained for 5-30 minutes, and then the heating rate is adjusted to 10°C / min, and the temperature is increased to between 350°C and 450°C, to obtain a cadmium zinc telluride substrate with a consistent surface state.
[0043] The present application also provides an implementation case of a method for pretreating a cadmium zinc telluride substrate for molecular beam epitaxy, including:
[0044] Take a piece of 211 crystal orientation B-side CdZnTe substrate, place it in a polytetrafluoroethylene basket, take a 100ml beaker filled with 50ml methanol solution, place the basket in the methanol solution, and slowly rotate and clean for 3 minutes.
[0045] Take out the flower basket, take another methanol reagent to rinse the CdZnTe substrate, repeat the rinsing three times, and blow dry the substrate surface with a nitrogen gun.
[0046] Use a pipette to take 10 ml of hydrofluoric acid solution, 10 ml of hydrochloric acid, and 200 ml of water to mix to form chemical etching solution 1. Etch the dried cadmium zinc telluride substrate in the chemical etching solution 1 for 30 seconds. After taking it out, rinse it with methanol and dry the substrate surface with a nitrogen gun.
[0047] Prepare 100 ml of 0.005% bromine methanol solution, corrode the dried CdZnTe substrate in the bromine methanol solution for 60 seconds, take it out and rinse it with methanol and dry the substrate surface with a nitrogen gun.
[0048] Use a pipette to take 10 ml of hydrogen peroxide solution, 10 ml of ammonia water, and 200 ml of water to mix to form chemical etching solution 3. Etch the dried cadmium zinc telluride substrate in chemical etching solution 3 for 10 seconds. After taking it out, rinse it with methanol and dry the substrate surface with a nitrogen gun.
[0049] The CdZnTe substrate was placed on a molybdenum tray and transferred to the growth chamber of the molecular beam epitaxy equipment. The heating program was set with a heating rate of 20°C / min. After heating to 280°C, it was kept for 5 minutes, and then heated to 350°C at a heating rate of 10°C / min. The lattice fringes during the heating process were monitored by a high-energy electron diffractometer. Figure 2 , Figure 3 shown. Figure 3 The diffraction fringes in the figure indicate that the CdZnTe substrate has a good surface state after pretreatment and meets the state requirements for the epitaxial growth of HgCdTe materials.
[0050] The embodiments of the present application improve the damaged layer and surface oxide by changing parameters such as the type, concentration, and cleaning time of the cleaning reagent, and use a chemical etching solution to treat the surface oxide and chemical state of the cadmium zinc telluride substrate to be consistent, and then heat treat the substrate to reconstruct the surface atoms through the heat treatment to meet the standards for growing an epitaxial layer of mercury cadmium telluride material.
[0051] It should be noted that in the various embodiments of the present application, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "includes a ..." does not exclude the presence of other identical elements in the process, method, article or device including the element.
[0052] The serial numbers of the above-mentioned embodiments of the present application are for description only and do not represent the advantages or disadvantages of the embodiments.
[0053] The embodiments of the present application are described above in conjunction with the accompanying drawings, but the present application is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of the present application, ordinary technicians in this field can also make many forms without departing from the purpose of the present application and the scope of protection of the claims, all of which are within the protection of the present application.
Claims
1. A method for pretreating cadmium zinc telluride substrates for molecular beam epitaxy, characterized in that: include: The cadmium zinc telluride substrate is immersed and rinsed in a methanol solution; The washed cadmium zinc telluride substrate is subjected to a first step of chemical etching, wherein the etching solution of the first step of chemical etching is a mixed solution of a hydrofluoric acid solution and a hydrochloric acid solution; After the first step of chemical etching, soak, rinse and blow dry; Performing a second step of chemical etching, wherein the etching solution of the second step of chemical etching is a mixed solution of a bromine solution and a methanol solution; After the second step of chemical etching, the process is blown dry, and then the third step of chemical etching is performed, wherein the third step of chemical etching uses a mixed solution of a hydrogen peroxide solution and an ammonia solution; After the third step of chemical etching, the CdZnTe substrate is heated until the surface oxide is removed to meet the requirements.
2. The method for pretreating a CdZnTe substrate for molecular beam epitaxy according to claim 1, characterized in that: The volume ratio of the hydrofluoric acid solution to the hydrochloric acid solution in the etching solution for performing the first step of chemical etching is 1:5-1:
1.
3. The method for pretreating a CdZnTe substrate for molecular beam epitaxy according to claim 1, characterized in that: The concentration of bromine methanol in the bromine solution and methanol solution used in the second step of chemical etching is 0.005%-5%.
4. The method for pretreating a CdZnTe substrate for molecular beam epitaxy according to claim 1, characterized in that: The volume ratio of the hydrogen peroxide solution to the ammonia solution in the third step of chemical etching is 10:1-1:
1.
5. The method for pretreating a CdZnTe substrate for molecular beam epitaxy according to claim 1, characterized in that: Heating the CdZnTe substrate after the third step of chemical etching includes: The cadmium zinc telluride substrate is heated by a gradual heating method, a first heating rate is configured, and after heating to a first target temperature, the temperature is maintained for a set time, and then a second heating rate is used to heat the substrate to a second target temperature, wherein the first heating rate is greater than the second heating rate.
6. The method for pretreating a CdZnTe substrate for molecular beam epitaxy according to claim 1, characterized in that: After the first step of chemical etching, it also includes: The CdZnTe substrate chemically etched in the first step is transferred to a methanol solution for immersion and rinsing, and then the CdZnTe substrate is blown dry using a nitrogen gun.
7. The method for pretreating a CdZnTe substrate for molecular beam epitaxy according to claim 1, characterized in that: After the third step of chemical etching, it also includes: After the third step of chemical etching, the CdZnTe substrate is rinsed with a methanol solution, blown dry, and then transferred to a molecular beam epitaxy processing chamber to perform a heating step.