A surface cleaning method for (111) crystal orientation indium antimonide wafer

Abstract

The present invention relates to a surface cleaning method for an indium antimonide wafer with a (111) crystal orientation. The surface of the wafer is pre-cleaned with a solution containing a surfactant, and after rinsing, the wafer is immersed in a mixed solution of hydrogen peroxide, ammonia and water for etching; the wafer is then immersed in a dilute sulfuric acid solution containing ozone for cleaning. The etching with the mixed solution and the cleaning with the dilute sulfuric acid solution containing ozone achieve a better surface cleaning effect, thereby better reducing the particle density on the wafer surface, reducing metal residue and achieving uniform oxidation.

Description

Technical Field

[0001] The present invention belongs to the field of semiconductor processing technology, and specifically relates to a surface cleaning method for a (111) crystal orientation indium antimonide wafer. Background Art

[0002] InSb, a key III-V compound semiconductor, exhibits extremely high electron mobility, a narrow bandgap, and 100% quantum efficiency in the 3-5μm mid-wave infrared band. It remains the most widely used material for infrared detectors in this band. Infrared detectors based on InSb have evolved from single-element detectors to multi-element detectors to two-dimensional focal plane arrays (FPAs). They are widely used in civilian infrared systems, such as infrared detection and astronomical observation, with excellent results. To meet the demands of fabricating 3-5μm mid-wave infrared FPAs, higher processing requirements are imposed on the InSb surface.

[0003] Because indium antimonide is a binary compound single crystal material, it is more difficult to achieve a high-quality clean surface compared to single crystal silicon and germanium. Traditional cleaning methods are prone to surface residue, resulting in high particle counts and uneven oxidation. Especially for wafers with a (111) crystal orientation, the surface atomic ratio of indium / antimony is greater than 1, resulting in an indium-rich surface. The surface metal residue is higher than that of wafers with a general crystal orientation (100). This also leads to a large number of particles on the surface of indium antimonide with a (111) crystal orientation during cleaning, as well as oxidation and surface metal residue problems.

[0004] For example, in U.S. Patent No. 200780024615.6, entitled "Post-etching Wafer Surface Cleaning Using a Meniscus," a method for cleaning the surface of a semiconductor wafer is disclosed. The method first uses a first cleaning solution to simply remove contaminants, then uses an oxidant solution to form an oxide layer on the remaining contaminant material on the wafer surface, and finally uses a second cleaning solution for cleaning. Traditional cleaning methods often use this method for cleaning.

[0005] A Chinese patent application numbered 201410005806.X, titled "A Mask Preparation Method for Indium Antimonide Thermal Diffusion Process," discloses a mask preparation method for an Indium Antimonide thermal diffusion process. During degumming, the wafer is treated for 1 to 3 hours using ultraviolet ozone degumming equipment heated to 70 to 100°C, then immersed in hydrochloric acid with a concentration of less than 10% for 5 to 15 minutes, and rinsed with deionized water for more than 10 minutes. Summary of the Invention

[0006] The purpose of the present invention is to provide a method for cleaning the surface of an indium antimonide (111) crystal orientation wafer to reduce the particle density on the wafer surface, reduce metal residues and achieve uniform oxidation.

[0007] In order to solve the above technical problems, the present invention discloses a surface cleaning method for an indium antimonide wafer with a (111) crystal orientation, which is used for cleaning the surface of an indium antimonide (111) crystal orientation wafer to reduce the particle density on the wafer surface, reduce metal residues and achieve uniform oxidation, comprising the following steps:

[0008] S1. Pre-cleaning the wafer surface using a solution containing a surfactant to make the surface hydrophilic;

[0009] S2. Rinse the wafer surface with deionized water;

[0010] S3. The wafer is immersed in a mixed solution of hydrogen peroxide, ammonia and water for corrosion;

[0011] S4. Rinse the wafer surface with deionized water;

[0012] S5. Use a wafer dryer to dry the surface;

[0013] S6. The wafer is immersed in a dilute sulfuric acid solution containing ozone for cleaning. During cleaning, the wafer is fixed on a wafer clamp, and then the wafer clamp is placed in the solution and shaken horizontally;

[0014] S7. Rinse the wafer surface with deionized water;

[0015] S8. Use a spin dryer to spin dry the wafer.

[0016] Preferably, in S1, the surfactant is a 10%-50% concentration aqueous solution of sodium fatty alcohol polyoxyethylene ether sulfate, and the treatment time is 5s to 60s.

[0017] Preferably, in S3, the volume ratio of the mixed solution is hydrogen peroxide: ammonia water: water = 1-5: 1-5: 1-9, wherein the concentration of hydrogen peroxide is 30±2%, the concentration of ammonia water is 27±3%, and the corrosion time is 5s to 60s.

[0018] Preferably, in S3, the volume ratio of the mixed solution is hydrogen peroxide:ammonia water:water=2:1:8.

[0019] Preferably, the deionized water rinsing time in S2, S4 and S7 is 5s to 60s.

[0020] Preferably, the drying time in S5 and S8 is 5s to 60s.

[0021] Preferably, in S6, the concentration of the dilute sulfuric acid is 10%-50%, the concentration of ozone in the solution is 0.1-0.5 mg / L, and the treatment time is 5s to 60s.

[0022] Preferably, in S6, during cleaning, the temperature of the dilute sulfuric acid solution containing ozone is 4±2° C., and the cleaning time is 15 s to 25 s.

[0023] Preferably, in S6, when the wafer clamp is placed in the solution and shaken horizontally left and right, the moving speed of the wafer clamp is 0.3-1 m / s.

[0024] Preferably, in S6, during cleaning, the area above the ozone-containing dilute sulfuric acid solution is in an ozone atmosphere.

[0025] The surface cleaning method of the (111) crystal orientation indium antimonide wafer of the present invention adds a surfactant to the traditional acid cleaning and alkaline cleaning to reduce the tension of the wafer surface, so that the surface reaches a good hydrophilic state, is easier to obtain a clean surface, and reduces the surface particle size; at the same time, by adding ozone cleaning, the surface oxidation can be made more uniform; this method can effectively solve the problems of indium antimonide (111) crystal orientation surface particles, oxidation, and residual metal on the surface, and prepare a high-quality wafer surface for subsequent processes. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figures 1 to 6 This is the particle distribution diagram measured by a surface analyzer. DETAILED DESCRIPTION

[0027] The present invention is further described in detail below through examples so that those skilled in the art can implement the invention with reference to the description.

[0028] It should be understood that terms such as “having”, “including” and “comprising” used herein do not preclude the existence or addition of one or more other elements or combinations thereof.

[0029] A surface cleaning method for an indium antimonide wafer with a (111) crystal orientation is used for cleaning the surface of an indium antimonide (111) crystal orientation wafer to reduce particle density on the wafer surface, reduce metal residue, and achieve uniform oxidation, comprising the following steps:

[0030] S1. Pre-cleaning the wafer surface using a solution containing a surfactant to make the surface hydrophilic;

[0031] S2. Rinse the wafer surface with deionized water;

[0032] S3. The wafer is immersed in a mixed solution of hydrogen peroxide, ammonia and water for corrosion;

[0033] S4. Rinse the wafer surface with deionized water;

[0034] S5. Use a wafer dryer to dry the surface;

[0035] S6. The wafer is immersed in a dilute sulfuric acid solution containing ozone for cleaning. During cleaning, the wafer is fixed on a wafer clamp, and then the wafer clamp is placed in the solution and shaken horizontally;

[0036] S7. Rinse the wafer surface with deionized water;

[0037] S8. Use a spin dryer to spin dry the wafer.

[0038] Pre-cleaning with the sodium sulfate solution of fatty alcohol polyoxyethylene ether in S1 makes the wafer surface hydrophilic, reduces the surface tension of the wafer, and makes the surface hydrophilic, making it easier to obtain a clean surface, thereby reducing the surface particle size and other possible effects. From the comprehensive test results, compared with other cleaning agents, the use of sodium sulfate solution of fatty alcohol polyoxyethylene ether for cleaning has better performance in terms of surface particle density, metal residue and uniform oxidation effect after cleaning. In addition, better surface cleaning effect can be achieved through corrosion in S3 and cleaning in S6: in S3, the InSb surface forms an oxide film under the oxidation of hydrogen peroxide, which is corroded by NH4OH, thereby removing particles attached to the surface; the oxides generated in the S3 stage include Sb2O3 and Sb2O5. Although NH4OH will dissolve some of them, there will still be residual and newly formed natural oxide films; in S6, due to the strong oxidizing property of ozone, it can attack the CC bond, effectively remove organic matter remaining on the wafer surface, and also remove residual Sb 3+ Oxidized to soluble SbO3 - , achieving better cleaning effects under acidic conditions, thereby better reducing the particle density on the wafer surface, reducing metal residues and achieving uniform oxidation.

[0039] In S1, the surfactant is a 10%-50% concentration aqueous solution of sodium fatty alcohol polyoxyethylene ether sulfate, and the treatment time is 5s to 60s.

[0040] In S3, the volume ratio of the mixed solution is hydrogen peroxide: ammonia water: water = 1-5: 1-5: 1-9, wherein the concentration of hydrogen peroxide is 30±2%, the concentration of ammonia water is 27±3%, and the corrosion time is 5s to 60s.

[0041] The deionized water rinsing time in S2, S4 and S7 is 5s to 60s, and the spin-drying time in S5 and S8 is 5s to 60s.

[0042] In S6, the concentration of dilute sulfuric acid is 10%-50%, the concentration of ozone in the solution is 0.1-0.5 mg / L, and the treatment time is 5s to 60s. When preparing the dilute sulfuric acid solution, the sulfuric acid is diluted to a mass concentration of 40%, and about 1L of solution is prepared. The ozone generator is turned on and the concentration of the O3 / O2 mixed gas is adjusted to 8-10wt%; ozone is introduced into the sulfuric acid through a titanium aeration head at a flow rate of 0.5L / min. The dissolved ozone concentration is detected online using a UV detector. When the detected value stabilizes at 0.4mg / L, ventilation is immediately stopped.

[0043] In S6, during cleaning, the temperature of the dilute sulfuric acid solution containing ozone is 4±2°C, and the cleaning time is 15s to 25s. During cleaning, the area above the dilute sulfuric acid solution containing ozone is in an ozone atmosphere. It is worth noting that due to the instability of ozone during the cleaning process, in order to better prevent the decomposition of ozone during the cleaning process, the following measures are adopted:

[0044] Use deionized water to prepare dilute sulfuric acid solution to reduce impurities. If necessary, the dilute sulfuric acid can be ultrasonically degassed. An ozone generator can also be added above the solution to keep the solution in an ozone atmosphere and increase its half-life. In addition, under strong acidic conditions and a lower temperature of about 4°C, the stability of ozone can also be increased, so that multiple wafers can be processed in batches with one solution.

[0045] In S6, the wafer holder is placed in the solution and shaken horizontally from side to side at a speed of 0.3-1 m / s. An appropriate wafer holder movement speed facilitates cleaning. Lower speeds make it difficult to achieve a good cleaning effect in a short period of time, while higher speeds may result in uneven cleaning. A guide rail can be placed at the bottom of the container to ensure smooth movement of the wafer holder.

[0046] Below we will illustrate through examples and comparative examples:

[0047] The following all use 30% concentration hydrogen peroxide and 27% concentration ammonia water. The volume ratio of the mixed solution is hydrogen peroxide: ammonia water: water = 2:1:8. This is the mixed solution ratio with the best effect under comprehensive comparison. Example 1

[0048] The following steps are used to clean the indium antimonide wafer. The single side of the wafer used in this embodiment has been rough-polished and fine-polished, and the crystal orientation is (111).

[0049] The wafer to be cleaned is placed in a 10% by mass fatty alcohol polyoxyethylene ether sodium sulfate solution and treated at about 20° C. for 15 seconds.

[0050] Take out the above wafer and rinse it under running water for 45 seconds.

[0051] Place the rinsed wafer in a mixed aqueous solution of hydrogen peroxide: ammonia: water in a volume ratio of 2:1:8 and treat at approximately 20°C for 10 seconds.

[0052] Take out the above wafer and rinse it under running water for 45 seconds.

[0053] Place the wafer on a spin dryer and spin dry for 60 seconds.

[0054] Place the surface-dried wafer in a dilute sulfuric acid solution containing ozone, where the concentration of ozone in the dilute sulfuric acid is 0.4 mg / L and the concentration of the dilute sulfuric acid is 40%, and treat at about 4°C for 20 seconds.

[0055] Take out the above wafer and rinse it under running water for 45 seconds.

[0056] Place the wafer on a spin dryer and spin dry for 60 seconds.

[0057] The strong light test shows that there are few particles on the surface of the wafer and the surface oxidation is uniform. The particle distribution measured by the surface analyzer is as follows Figure 1 As shown: particle density is about 24 particles / cm 2 The surface metal content was measured by reflection X-ray analyzer as follows: Cu content 1.8×10 10 , Zn content 0.9×10 10 The thickness of the nutrient layer measured by ellipsometer was 2.8 nm. Example 2

[0058] The following steps are used to clean the indium antimonide wafer. The single side of the wafer used in this embodiment has been rough-polished and fine-polished, and the crystal orientation is (111).

[0059] The wafer to be cleaned is placed in a 20% by mass fatty alcohol polyoxyethylene ether sodium sulfate (anionic surfactant) solution and treated at about 20°C for 15 seconds.

[0060] Take out the above wafer and rinse it under running water for 45 seconds.

[0061] Place the rinsed wafer in a mixed aqueous solution of hydrogen peroxide: ammonia: water in a volume ratio of 2:1:8 and treat at approximately 20°C for 10 seconds.

[0062] Take out the above wafer and rinse it under running water for 45 seconds.

[0063] Place the wafer on a spin dryer and spin dry for 60 seconds.

[0064] Place the surface-dried wafer in a dilute sulfuric acid solution containing ozone, where the concentration of ozone in the dilute sulfuric acid is 0.4 mg / L and the concentration of the dilute sulfuric acid is 40%, and treat at about 4°C for 20 seconds.

[0065] Take out the above wafer and rinse it under running water for 45 seconds.

[0066] Place the wafer on a spin dryer and spin dry for 60 seconds.

[0067] The strong light test shows that there are few particles on the surface of the wafer and the surface oxidation is uniform. The particle distribution measured by the surface analyzer is as follows Figure 2 As shown: particle density is about 43 particles / cm 2 The surface metal content was measured by reflection X-ray analyzer as follows: Cu content 1.9×10 10 , Zn content 1.2×10 10 The thickness of the nutrient layer measured by ellipsometer was 3.1 nm. Example 3

[0068] The following steps are used to clean the indium antimonide wafer. The single side of the wafer used in this embodiment has been rough polished and fine polished, and the crystal orientation is (100).

[0069] The wafer to be cleaned is placed in a 10% by mass fatty alcohol polyoxyethylene ether sodium sulfate solution and treated at about 20° C. for 15 seconds.

[0070] Take out the above wafer and rinse it under running water for 45 seconds.

[0071] Place the rinsed wafer in a mixed aqueous solution of hydrogen peroxide: ammonia: water in a volume ratio of 2:1:8 and treat at approximately 20°C for 10 seconds.

[0072] Take out the above wafer and rinse it under running water for 45 seconds.

[0073] Place the wafer on a spin dryer and spin dry for 60 seconds.

[0074] Place the surface-dried wafer in a dilute sulfuric acid solution containing ozone, where the concentration of ozone in the dilute sulfuric acid is 0.4 mg / L and the concentration of the dilute sulfuric acid is 40%, and treat at about 4°C for 20 seconds.

[0075] Take out the above wafer and rinse it under running water for 45 seconds.

[0076] Place the wafer on a spin dryer and spin dry for 60 seconds.

[0077] The strong light test shows that there are few particles on the surface of the wafer and the surface oxidation is uniform. The particle distribution measured by the surface analyzer is as follows Figure 3 As shown: particle density is about 50 particles / cm 2 The surface metal content was measured by reflection X-ray analyzer as follows: Cu content 1.9×10 10, Zn content 1.1×10 10 The thickness of the nutrient layer measured by ellipsometer was 2.9 nm.

[0078] Comparative Example 1

[0079] The surfactant was removed and the rest of the process was the same as in Example 1.

[0080] The following steps are used to clean the indium antimonide wafer. The single side of the wafer used in this comparative example has been rough polished and fine polished, and the crystal orientation is (111).

[0081] Place the wafer to be cleaned in a mixed solution of hydrogen peroxide: ammonia: water in a volume ratio of 2:1:8 and treat at approximately 20°C for 10 seconds.

[0082] Take out the above wafer and rinse it under running water for 45 seconds.

[0083] Place the wafer on a spin dryer and spin dry for 60 seconds.

[0084] Place the surface-dried wafer in a dilute sulfuric acid solution containing ozone, where the concentration of ozone in the dilute sulfuric acid is 0.4 mg / L and the concentration of the dilute sulfuric acid is 40%, and treat at about 4°C for 20 seconds.

[0085] Take out the above wafer and rinse it under running water for 45 seconds.

[0086] Place the wafer on a spin dryer and spin dry for 60 seconds.

[0087] The strong light test shows that the surface particles of the wafer increase and the surface oxidation is uniform. The particle distribution measured by the surface analyzer is as follows Figure 4 As shown: particle density is about 82 particles / cm 2 The surface metal content was measured by reflection X-ray analyzer as follows: Cu content 3.1×10 10 , Zn content 2.3×10 10 The thickness of the nutrient layer measured by ellipsometer was 3.1 nm.

[0088] Comparative Example 2

[0089] The ozone cleaning was removed, and the remaining process was the same as in Example 1.

[0090] The following steps are used to clean the indium antimonide wafer. The single side of the wafer used in this comparative example has been rough polished and fine polished, and the crystal orientation is (111).

[0091] The wafer to be cleaned is placed in a 10% by mass fatty alcohol polyoxyethylene ether sodium sulfate solution and treated at about 20° C. for 15 seconds.

[0092] Take out the above wafer and rinse it under running water for 45 seconds.

[0093] Place the rinsed wafer in a mixed aqueous solution of hydrogen peroxide: ammonia: water in a volume ratio of 2:1:8 and treat at approximately 20°C for 10 seconds.

[0094] Take out the above wafer and rinse it under running water for 45 seconds.

[0095] Place the wafer on a spin dryer and spin dry for 60 seconds.

[0096] The strong light test showed that the surface was unevenly oxidized, resulting in an increase in particulate matter. The particle distribution measured by the surface analyzer is as follows: Figure 5 As shown: Particle density is about 717 particles / cm 2 The surface metal content was measured by reflection X-ray analyzer as follows: Cu content 4.2×10 10 , Zn content 2.5×10 10 The thickness of the nutrient layer measured by ellipsometer was 5.1 nm.

[0097] Comparative Example 3

[0098] Ozone and acid washing were separated, and the remaining processes were the same as in Example 1.

[0099] The following steps are used to clean the indium antimonide wafer. The single side of the wafer used in this comparative example has been rough polished and fine polished, and the crystal orientation is (111).

[0100] The wafer to be cleaned is placed in a 10% by mass fatty alcohol polyoxyethylene ether sodium sulfate solution and treated at about 20° C. for 15 seconds.

[0101] Take out the above wafer and rinse it under running water for 45 seconds.

[0102] Place the rinsed wafer in a mixed aqueous solution of hydrogen peroxide: ammonia: water in a volume ratio of 2:1:8 and treat at approximately 20°C for 10 seconds.

[0103] Take out the above wafer and rinse it under running water for 45 seconds.

[0104] The wafer to be cleaned is then exposed to ozone (gaseous, concentration of about 0.4 mg / L) for 20 seconds, and then placed in a dilute sulfuric acid solution for cleaning. The concentration of the dilute sulfuric acid is 40%, and the treatment is carried out at about 4°C for 20 seconds.

[0105] Take out the above wafer and rinse it under running water for 45 seconds.

[0106] Place the wafer on a spin dryer and spin dry for 60 seconds.

[0107] The strong light test showed that the surface was unevenly oxidized, resulting in an increase in particulate matter. The particle distribution measured by the surface analyzer is as follows: Figure 6 As shown: particle density is not less than 213 particles / cm 2 The surface metal content was measured by reflection X-ray analyzer as follows: Cu content 3.5×10 10 , Zn content 1.6×10 10 The thickness of the nutrient layer measured by ellipsometer was 3.2 nm.

[0108] The data of 3 groups of embodiments and 3 groups of comparative examples are summarized as shown in the following table:

[0109]

[0110] Overall, the method of the present invention is more suitable for wafers with (111) crystal orientation. The appropriate concentration of fatty alcohol polyoxyethylene ether sodium sulfate solution has a certain effect on the particle density on the wafer surface after cleaning (10%-20% fatty alcohol polyoxyethylene ether sodium sulfate solution is preferred in practical applications); in addition, the use of dilute sulfuric acid containing ozone for cleaning has a better cleaning effect. Furthermore, compared with ozone treatment and acid washing of the wafer separately, the use of 40% dilute sulfuric acid with an ozone concentration of 0.4 mg / L for cleaning has a better effect.

[0111] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the description and implementation methods. They can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and embodiments shown and described herein.

Claims

1. A surface cleaning method for indium antimonide wafers with a (111) crystal orientation, used for cleaning the surface of indium antimonide wafers with a (111) crystal orientation to reduce the particle density on the wafer surface, reduce metal residues and achieve uniform oxidation, characterized in that: The following steps are involved: S1. Pre-cleaning the wafer surface using a solution containing a surfactant to make the surface hydrophilic; S2. Rinse the wafer surface with deionized water; S3. The wafer is immersed in a mixed solution of hydrogen peroxide, ammonia and water for corrosion; S4. Rinse the wafer surface with deionized water; S5. Use a wafer dryer to dry the surface; S6. The wafer is immersed in a dilute sulfuric acid solution containing ozone for cleaning. During cleaning, the wafer is fixed on a wafer clamp, and then the wafer clamp is placed in the solution and shaken horizontally; S7. Rinse the wafer surface with deionized water; S8. Use a dryer to dry the wafer; In S1, the surfactant is a 10%-50% concentration aqueous solution of sodium fatty alcohol polyoxyethylene ether sulfate, and the treatment time is 5s to 60s.

2. The method according to claim 1, characterized in that In S3, the volume ratio of the mixed solution is hydrogen peroxide: ammonia water: water = 1-5: 1-5: 1-9, wherein the concentration of hydrogen peroxide is 30±2%, the concentration of ammonia water is 27±3%, and the corrosion time is 5s to 60s.

3. The method according to claim 2, characterized in that In S3, the volume ratio of the mixed solution is hydrogen peroxide:ammonia water:water=2:1:

8.

4. The method according to claim 1, wherein In S2, S4 and S7, the deionized water rinsing time is 5s to 60s.

5. The method according to claim 1, wherein In S5 and S8, the drying time is 5s to 60s.

6. The method according to claim 1, wherein In S6, the concentration of the dilute sulfuric acid is 10%-50%, the concentration of ozone in the solution is 0.1-0.5 mg / L, and the treatment time is 5s to 60s.

7. The method according to claim 6, characterized in that In S6, during cleaning, the temperature of the dilute sulfuric acid solution containing ozone is 4±2° C., and the cleaning time is 15 to 25 seconds.

8. The method according to claim 7, characterized in that In S6, when the wafer holder is placed in the solution and shaken horizontally left and right, the moving speed of the wafer holder is 0.3-1 m / s.

9. The method according to claim 1, characterized in that In S6, during cleaning, the area above the dilute sulfuric acid solution containing ozone is in an ozone atmosphere.

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