A surface treatment method for indium phosphide wafers

Abstract

The application provides a surface treatment method of an indium phosphide wafer, comprising the following steps: a) using a mixed liquid to perform a chemical treatment on the polished and waxed indium phosphide wafer, so as to obtain a treated wafer; the mixed liquid is prepared from an oxidizing agent solution, an acid solution and water; b) sequentially performing water flushing and spin-drying on the treated wafer obtained in the step a), so as to obtain an indium phosphide wafer before cleaning and inspection. Compared with the prior art, the surface treatment method of the indium phosphide wafer is an important process before the cleaning and inspection of the indium phosphide wafer, the surface treatment method is simple in operation and high in efficiency; the surface roughness of the treated wafer is better, and the product yield is higher; and the components in the mixed liquid are all common inorganic chemicals, so that the cost is low; therefore, the surface treatment method of the indium phosphide wafer has a wide application prospect.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of compound semiconductor wafer surface treatment, and more particularly to a surface treatment method of indium phosphide wafer. BACKGROUND

[0002] The indium phosphide wafer is widely used in the fields of communication, medical treatment, photoelectricity, etc., has high electron mobility and electro-optical conversion rate, is suitable for manufacturing mobile phone chips, has excellent radiation resistance, and can also be used for manufacturing solar cells, and is a semiconductor material with wide application prospect.

[0003] At present, the problem urgently needed to be solved for the indium phosphide wafer is still to improve the surface quality of the wafer under the condition of reducing production cost and improving production efficiency.

[0004] With the rapid development of semiconductor process technology, the quality requirement for the surface of the indium phosphide wafer is also higher and higher, so it is necessary to reduce the surface roughness to ensure the efficient subsequent epitaxy. SUMMARY

[0005] Therefore, the purpose of the present application is to provide a surface treatment method of indium phosphide wafer, which can reduce the surface roughness of the wafer and improve the efficiency of subsequent wafer processing and yield.

[0006] The present application provides a surface treatment method of indium phosphide wafer, comprising the following steps:

[0007] a) treating the indium phosphide wafer after polishing and waxing with a mixed liquid to obtain a treated wafer; the mixed liquid is prepared from an oxidizing agent solution, an acid solution and water;

[0008] b) sequentially rinsing and drying the treated wafer obtained in step a) to obtain an indium phosphide wafer before cleaning inspection.

[0009] Preferably, the process of waxing in step a) is specifically as follows:

[0010] After the polished indium phosphide wafer is taken out, it is placed in a turnover cassette; 10L of cleaning liquid is prepared, the cleaning liquid is prepared by mixing water and inorganic cleaning agent at a volume ratio of (9-11) : 1, the cleaning liquid is heated to 80-85℃, the indium phosphide wafer is sequentially placed in the waxing cassette, waxing is carried out, the treatment time is controlled at 200-300s, the wafer is rinsed for 100-300s after waxing, and finally the wafer is dried to complete the waxing process.

[0011] Preferably, the inorganic cleaning agent comprises the following components:

[0012] tetramethylammonium hydroxide 1wt%-3wt%;

[0013] Polyethylene glycol 13wt%~15wt%;

[0014] n-Hexane 13wt%~15wt%;

[0015] Sodium pyrophosphate 2wt%~5wt%;

[0016] The balance of ultrapure water.

[0017] Preferably, the oxidizing agent solution in step a) is potassium permanganate solution, hydrogen peroxide solution or potassium nitrate solution; the concentration of the oxidizing agent solution is 3%~8%.

[0018] Preferably, the acid solution in step a) is sulfuric acid solution, nitric acid solution, hydrochloric acid solution or acetic acid solution; the concentration of the acid solution is 0.28%~0.32%.

[0019] Preferably, the volume ratio of the oxidizing agent solution, acid solution and water in step a) is 1:(0.5~1.5):(2~3).

[0020] Preferably, the pH value of the mixed liquor in step a) is 0.8~1.2.

[0021] Preferably, the process of the over-treatment in step a) is specifically:

[0022] The polished and waxed indium phosphide wafer is sequentially placed into a cassette and immersed into the mixed liquor, and the control time is 20min~40min, and then the wafer is taken out.

[0023] Preferably, the time of the water flushing in step b) is greater than or equal to 60s.

[0024] The present application provides a surface treatment method of indium phosphide wafer, comprising the following steps: a) polishing and waxing the indium phosphide wafer, and then using a mixed liquor to perform over-treatment, so as to obtain a treated wafer; the mixed liquor is prepared from an oxidizing agent solution, an acid solution and water; b) sequentially performing water flushing and spin-drying on the treated wafer obtained in step a), so as to obtain an indium phosphide wafer before cleaning and inspection. Compared with the prior art, the surface treatment method of the indium phosphide wafer provided by the present application is an important process before the cleaning and inspection of the indium phosphide wafer, and the surface treatment method is simple in operation and high in efficiency; the surface roughness of the treated wafer is better, and the product yield is higher; and the components in the mixed liquor used are all common inorganic chemicals, and the cost is low; therefore, the surface treatment method of the indium phosphide wafer provided by the present application has a wide application prospect. The experimental results show that the indium phosphide wafer obtained by the surface treatment method provided by the present application has a surface roughness of ≤0.230nm, and the product yield is above 91%. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 A process flow chart of the surface treatment method of the indium phosphide wafer provided by the present application is shown in the figure. DETAILED DESCRIPTION

[0026] The technical solutions of the present application will be described clearly and completely below in combination with the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative efforts belong to the scope of protection of the present application.

[0027] The present application provides a surface treatment method of an indium phosphide wafer, comprising the following steps:

[0028] a) treating the polished and waxed indium phosphide wafer with a mixed solution to obtain a treated wafer; the mixed solution is prepared from an oxidizing agent solution, an acid solution and water;

[0029] b) sequentially rinsing and drying the treated wafer obtained in step a) to obtain an indium phosphide wafer before cleaning and inspection.

[0030] The present application first treats the polished and waxed indium phosphide wafer with a mixed solution to obtain a treated wafer. The present application does not have special restrictions on the source of the indium phosphide wafer, and any indium phosphide wafer before cleaning and inspection known to those skilled in the art can be used.

[0031] The present application does not have special restrictions on the polishing process, and any polishing technical solution known to those skilled in the art can be used.

[0032] In the present application, the waxing process is preferably as follows:

[0033] After the polished indium phosphide wafer is unloaded, it is placed in a turnover cassette. 10L of cleaning solution is prepared, the cleaning solution is prepared by mixing water and inorganic cleaning agent at a volume ratio of (9-11):1, the cleaning solution is heated to 80-85℃, the indium phosphide wafer is sequentially placed in the waxing cassette, waxing is performed, the time for treating the wafer is controlled at 200-300s, the wafer is rinsed for 100-300s after waxing, and finally the indium phosphide wafer is dried to complete the waxing process.

[0034] More preferably, the waxing process is as follows:

[0035] After the polished indium phosphide wafer is unloaded, it is placed in a turnover cassette. 10L of cleaning solution is prepared, the cleaning solution is prepared by mixing water and inorganic cleaning agent at a volume ratio of 10:1, the cleaning solution is heated to 82℃, the indium phosphide wafer is sequentially placed in the waxing cassette, waxing is performed, the time for treating the wafer is controlled at 240s, the wafer is rinsed for 200s after waxing, and finally the indium phosphide wafer is dried to complete the waxing process.

[0036] In the present application, the inorganic cleaning agent preferably comprises the following components:

[0037] tetramethylammonium hydroxide 1wt%~3wt%;

[0038] polyethylene glycol 13wt%~15wt%;

[0039] n-hexane 13wt%~15wt%;

[0040] sodium pyrophosphate 2wt%~5wt%;

[0041] the balance of ultrapure water;

[0042] More preferably:

[0043] tetramethylammonium hydroxide 2wt%;

[0044] polyethylene glycol 14wt%;

[0045] n-hexane 14wt%;

[0046] sodium pyrophosphate 3wt%;

[0047] the balance of ultrapure water.

[0048] The present application has no special restrictions on the source of the above-mentioned tetramethylammonium hydroxide, polyethylene glycol, n-hexane and sodium pyrophosphate, and commercially available products known to those skilled in the art can be used.

[0049] In the present application, the mixed liquid is prepared from an oxidizing agent solution, an acid solution and water.

[0050] In the present application, the oxidizing agent solution is preferably a potassium permanganate solution, a hydrogen peroxide solution or a potassium nitrate solution, more preferably a potassium permanganate solution or a potassium nitrate solution; the concentration of the oxidizing agent solution is preferably 3%~8%, more preferably 5%~6%. The present application has no special restrictions on the source of the oxidizing agent solution, and a solution prepared from the above-mentioned commercially available oxidizing substances such as potassium permanganate, hydrogen peroxide and potassium nitrate known to those skilled in the art can be used.

[0051] In the present application, the acid solution is preferably a sulfuric acid solution, a nitric acid solution, a hydrochloric acid solution or an acetic acid solution, more preferably a sulfuric acid solution or a hydrochloric acid solution; the concentration of the acid solution is preferably 0.28%~0.32%, more preferably 0.3%. The present application has no special restrictions on the source of the acid solution, and a solution prepared from the above-mentioned commercially available acidic substances such as sulfuric acid, nitric acid, hydrochloric acid and acetic acid known to those skilled in the art can be used.

[0052] In the present application, the volume ratio of the oxidizing agent solution, the acid solution and water in the mixed chemical solution is preferably 1:(0.5-1.5):(2-3), more preferably 1:1:2; in the preferred embodiment of the present application, the amount of the mixed chemical solution is 10 L, and the volume of the oxidizing agent solution, the acid solution and water is 2.5 L, 2.5 L and 5 L respectively.

[0053] In the present application, the pH value of the mixed chemical solution is preferably 0.8-1.2, more preferably 0.9-1.1.

[0054] The preparation method of the mixed chemical solution is not particularly limited in the present application, and any method known to those skilled in the art can be used.

[0055] In the present application, the process of the over-treatment is preferably as follows:

[0056] The polished and waxed indium phosphide wafer is sequentially placed in the cassette, immersed in the mixed chemical solution, and controlled for 20-40 min, and then taken out.

[0057] More preferably, the process of the over-treatment is as follows:

[0058] The polished and waxed indium phosphide wafer is sequentially placed in the cassette, immersed in the mixed chemical solution, and controlled for 30 min, and then taken out. The cassette used in the present application is convenient to operate and has high efficiency, and can realize batch processing of the indium phosphide wafer surface treatment and improve the processing efficiency; at the same time, it can also improve the product yield and reduce the cost to some extent.

[0059] In the present application, the cassette should ensure a smooth surface and a large density, and be matched with a corresponding cassette handle.

[0060] The temperature of the over-treatment is not particularly limited in the present application, and any room temperature condition known to those skilled in the art can be used.

[0061] By adjusting the pH value of the mixed chemical solution and the over-treatment time of the wafer, the surface quality of the wafer can be improved.

[0062] After obtaining the treated wafer, the treated wafer is sequentially rinsed and spun dry to obtain the indium phosphide wafer before cleaning and inspection.

[0063] In the present application, the rinsing time is preferably greater than or equal to 60 s.

[0064] The process of the spin-drying is not particularly limited in the present application, and any method known to those skilled in the art can be used.

[0065] The surface treatment method of the indium phosphide wafer provided by the application can batch process the indium phosphide wafer, improve the surface treatment efficiency of the wafer, greatly save the cost, and obviously reduce the surface roughness of the processed wafer (improve the surface quality of the wafer), which can reach 0.227 nm. In the subsequent processing, mechanical defects such as scratches and scratches are obviously reduced, and the product yield is greatly improved, which is more than 91%.

[0066] The surface treatment method of the indium phosphide wafer provided by the application comprises the following steps: a) polishing and waxing the indium phosphide wafer, and using a mixed liquid to perform a drug treatment, to obtain a processed wafer; the mixed liquid is prepared from an oxidizing agent solution, an acid solution and water; b) the processed wafer obtained in step a) is sequentially washed and dried to obtain an indium phosphide wafer before cleaning and inspection. Compared with the prior art, the surface treatment method of the indium phosphide wafer provided by the application is an important process before the cleaning and inspection of the indium phosphide wafer. The surface treatment method is simple to operate and has high efficiency; the surface roughness of the processed wafer is better, and the product yield is higher; and the components of the mixed liquid used are common inorganic chemicals, which has low cost. Therefore, the surface treatment method of the indium phosphide wafer provided by the application has a wide application prospect. Experimental results show that the surface roughness of the indium phosphide wafer obtained by the surface treatment method reaches ≤0.230 nm, and the product yield is more than 91%.

[0067] In order to further illustrate the application, the following examples are described in detail. The "concentration" in the following examples of the application is mass percentage concentration; the waxing process is specifically as follows: after the polished indium phosphide wafer is unloaded, it is placed in a turnover cassette; 10L of cleaning liquid is prepared, the cleaning liquid is prepared by mixing water and inorganic cleaning agent (components: tetramethylammonium hydroxide 2wt%, polyethylene glycol 14wt%, n-hexane 14wt%, sodium pyrophosphate 3wt%, and the balance of ultrapure water) at a volume ratio of 10:1, the cleaning liquid is heated to 82℃, the indium phosphide wafer is sequentially placed in the waxing cassette, waxing is performed, the drug treatment time is controlled at 240s, the wafer is washed for 200s after waxing, and finally the indium phosphide wafer is dried to complete the waxing process.

[0068] Example 1

[0069] Referring to Figure 1 As shown in Figure 1 The process flow chart of the surface treatment method of the indium phosphide wafer provided by the application. In order to meet the normal use of the indium phosphide wafer in the subsequent use process, it is necessary to meet the requirement of ≤0.230 nm of the wafer surface roughness at the present stage, and the wafer surface treatment is required after the wafer polishing and waxing to improve the roughness of the wafer surface.

[0070] The wafer is treated with mixed chemicals, 10L of chemicals are prepared, the components are 2.5L of 5% potassium permanganate solution, 2.5L of 0.30% hydrochloric acid, and 5L of deionized water; the pH is 1.086. The polished and waxed wafer is sequentially placed in a cassette, and the wafer is treated with chemicals for 30 minutes, then rinsed for more than 60 seconds, and finally dried and cleaned for inspection. The surface roughness is 0.227nm tested by AFM, and the product yield reaches 91.3%.

[0071] Comparative Example 1

[0072] The wafer is treated with mixed chemicals, 10L of chemicals are prepared, the components are 2.5L of 5% potassium permanganate solution, 2.5L of 0.30% hydrochloric acid, and 5L of deionized water; the pH is 1.086. The polished and waxed wafer is sequentially placed in a cassette, and the wafer is treated with chemicals for 30 minutes, then rinsed for more than 60 seconds, and finally dried and cleaned for inspection. The surface roughness is 0.227nm tested by AFM, and the product yield reaches 91.3%.

[0073] Comparative Example 2

[0074] The wafer is treated with mixed chemicals, 10L of chemicals are prepared, the components are 2.5L of 5% potassium permanganate solution, 2.5L of 0.30% hydrochloric acid, and 5L of deionized water; the pH is 1.086. The polished and waxed wafer is sequentially placed in a cassette, and the wafer is treated with chemicals for 30 minutes, then rinsed for more than 60 seconds, and finally dried and cleaned for inspection. The surface roughness is 0.227nm tested by AFM, and the product yield reaches 91.3%.

[0075] Comparative Example 3

[0076] The wafer is treated with mixed chemicals, 10L of chemicals are prepared, the components are 2.5L of 5% potassium permanganate solution, 2.5L of 0.30% hydrochloric acid, and 5L of deionized water; the pH is 1.086. The polished and waxed wafer is sequentially placed in a cassette, and the wafer is treated with chemicals for 30 minutes, then rinsed for more than 60 seconds, and finally dried and cleaned for inspection. The surface roughness is 0.227nm tested by AFM, and the product yield reaches 91.3%.

[0077] Comparative Example 4

[0078] The process flow of the surface treatment method provided in Example 1 is used: when preparing the wafer for surface treatment, 10 L of a mixed liquid is used, the components are: 2.5 L of a 5% potassium permanganate solution, 2.5 L of a 0.3% hydrochloric acid solution, and 5 L of deionized water; the pH is 1.086. The polished and waxed wafer is sequentially placed in a cassette, and the wafer is treated with the liquid, the liquid treatment time is increased to 60 min, the wafer is rinsed after the liquid treatment, the rinsing time is not less than 60 s, and finally the wafer is spun dry and then cleaned and inspected; the surface roughness is 0.229 nm as tested by AFM, and the product yield reaches 90.7%.

[0079] Comparative Example 5

[0080] The process flow of the surface treatment method provided in Example 1 is used: when preparing the wafer for surface treatment, 10 L of a mixed liquid is used, the components are: 2.5 L of a 5% potassium permanganate solution, 2.5 L of a 0.3% hydrochloric acid solution, and 5 L of deionized water; the pH is 1.086. The polished and waxed wafer is sequentially placed in a cassette, and the wafer is treated with the liquid, the liquid treatment time is increased to 60 min, the wafer is rinsed after the liquid treatment, the rinsing time is not less than 60 s, and finally the wafer is spun dry and then cleaned and inspected; the surface roughness is 0.229 nm as tested by AFM, and the product yield reaches 90.7%.

[0081] Comparative Example 6

[0082] The process flow of the surface treatment method provided in Example 1 is used: if the surface treatment process of the wafer is adjusted before polishing and waxing; when the wafer is treated, a mixed liquid is used, 10 L of the liquid is prepared, the components are: 2.5 L of a 5% potassium permanganate solution, 2.5 L of a 0.3% hydrochloric acid solution, and 5 L of deionized water; the pH is 1.086. The wafer is treated with the liquid, the liquid treatment time is controlled to be 30 min, the wafer is rinsed after the liquid treatment, the rinsing time is not less than 60 s, and finally the wafer is spun dry, polished, waxed, and then cleaned and inspected; the surface roughness is 0.248 nm as tested by AFM, and the product yield reaches 90.1%.

[0083] Example 2

[0084] The process flow of the surface treatment method provided in Example 1 is used: when preparing the wafer for surface treatment, 10 L of a mixed liquid is used, the components are: 2.5 L of a 5% potassium permanganate solution, 2.5 L of a 0.3% hydrochloric acid solution, and 5 L of deionized water; the pH is 1.086. The polished and waxed wafer is sequentially placed in a cassette, and the wafer is treated with the liquid, the liquid treatment time is increased to 60 min, the wafer is rinsed after the liquid treatment, the rinsing time is not less than 60 s, and finally the wafer is spun dry and then cleaned and inspected; the surface roughness is 0.229 nm as tested by AFM, and the product yield reaches 90.7%.

[0085] Example 3

[0086] The process flow of the surface treatment method provided in Example 1 is as follows: when the wafer is subjected to surface treatment, a mixed chemical solution is used, and the chemical solution is prepared in 10 L, and the components are as follows: 2.5 L of 5% potassium permanganate solution, 2.5 L of 0.9% sulfuric acid, and 5 L of deionized water; the pH is 1.037. The polished and waxed wafer is sequentially placed in a cassette, and the wafer is subjected to chemical treatment, and the chemical treatment time is controlled to be 30 min. After the chemical treatment, the wafer is rinsed for no less than 60 s, and finally the wafer is dried and cleaned for inspection. The surface roughness tested by AFM is 0.229 nm, and the product yield reaches 91.2%.

[0087] Table 1: Summary of chemical solution, conditions, parameters, and effect data in Examples 1-3 and Comparative Examples 1-6

[0088]

[0089]

[0090] The experimental results show that the product of Example 1 is detected, the roughness is 0.227 nm, and the product yield is 91.3%. The cost is reduced and the high use requirements of the subsequent epitaxy of indium phosphide wafer are met. The product of Comparative Example 2 is detected, the roughness is 0.228 nm, and the product yield is 90.9%. When the pH of the mixed chemical solution is 1.5, the product quality is better, but the product yield is not high. The product of Comparative Example 1 is severely corroded due to the decrease of the pH of the mixed chemical solution, the roughness is seriously out of standard, and the product yield is relatively poor. The product of Comparative Example 3 is not chemically reacted due to the increase of the pH of the mixed chemical solution, the roughness is out of standard, and the product yield is relatively poor. The product of Comparative Example 4 reduces the chemical treatment time, the roughness is out of standard, and the product yield is general. The product of Comparative Example 5 increases the chemical treatment time, the roughness is up to standard, and the product yield is not high. The process position of Comparative Example 6 is changed, and the process is adjusted before polishing and waxing. The same process parameters as Example 1 are used. Since the wafer is polished after surface treatment, the wafer maintains the roughness of 0.248 nm, which cannot meet the requirement of low roughness of the wafer, and the product yield is general. Examples 2 and 3 change the A and B chemical solutions respectively, the pH is kept at 1±0.1, and the chemical treatment time is kept at 30 min. The products still meet the high use requirements of the subsequent epitaxy: the roughness is ≤0.230 nm, and the product yield is ≥91%.

[0091] The above description of disclosed examples enables one of ordinary skill in the art to make or use the application. Various modifications to these examples will be readily apparent to those of ordinary skill in the art, and the generic principles defined herein can be applied to other examples without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the examples shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for surface treatment of indium phosphide wafer, comprising the following steps: a) treating the polished and waxed indium phosphide wafer with a mixed solution to obtain a treated wafer; the mixed solution is prepared from an oxidizing agent solution, an acid solution and water; the concentration of the oxidizing agent solution is 3-8%; the concentration of the acid solution is 0.28-0.32%; the volume ratio of the oxidizing agent solution, the acid solution and water is 1: (0.5-1.5) : (2-3); the time for the treatment is 20-40 min; the pH value of the mixed solution is 0.8-1.2; b) sequentially rinsing and drying the treated wafer obtained in step a) to obtain an indium phosphide wafer before cleaning inspection. The waxing process in step a) is specifically as follows: after the polished indium phosphide wafer is unloaded, it is placed in a turnover cassette; 10 L of cleaning solution is prepared, the cleaning solution is prepared from water and inorganic cleaning agent at a volume ratio of (9-11) : 1, the cleaning solution is heated to 80-85℃, the indium phosphide wafer is sequentially placed in a waxing cassette, waxing is performed, the treatment time is controlled to be 200-300 s, the wafer is rinsed for 100-300 s after waxing, and finally the wafer is dried to complete the waxing process. The inorganic cleaning agent comprises the following components:

2. The surface treatment method of an indium phosphide wafer according to claim 1, wherein tetramethylammonium hydroxide 1-3 wt%; polyethylene glycol 13-15 wt%; 3. The surface treatment method of an indium phosphide wafer according to claim 2, wherein n-hexane 13-15 wt%; sodium pyrophosphate 2-5 wt%; the balance is ultrapure water. The oxidizing agent solution in step a) is potassium permanganate solution, hydrogen peroxide solution or potassium nitrate solution. The acid solution in step a) is sulfuric acid solution, nitric acid solution, hydrochloric acid solution or acetic acid solution. The treatment process in step a) is specifically as follows:

4. The surface treatment method of an indium phosphide wafer according to Claim 1, wherein the polished and waxed indium phosphide wafer is sequentially placed in a cassette, immersed in the mixed solution, and controlled for 20-40 min, and then taken out.

5. The surface treatment method of an indium phosphide wafer according to Claim 1, wherein The rinsing time in step b) is greater than or equal to 60 s.

6. The method of claim 1, wherein the InP wafer is a bulk InP wafer. ​ ​ 7. The method of claim 1, wherein the InP wafer is a bulk InP wafer. ​

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