Atomization cleaning method for indium phosphide wafer
The "acid-alkali-acid" three-step cleaning method using a high-pressure nitrogen atomization system solves the problems of corrosion and secondary contamination of indium phosphide wafers caused by traditional RCA wet chemical cleaning processes, achieving efficient and non-destructive cleaning results and ensuring the cleanliness and smoothness of the wafer surface.
Patent Information
- Application Number
- CN202511809518.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-03
- Publication Date
- 2026-03-03
AI Technical Summary
Traditional RCA wet chemical cleaning processes can easily lead to wafer corrosion, increased surface roughness, and secondary contamination when cleaning indium phosphide wafers, affecting the fabrication quality of high-end optoelectronic and microelectronic devices.
A three-step chemical synergistic cleaning method using a high-pressure nitrogen atomization system employs an "acid-base-acid" atomization mechanism. This method uses high-pressure nitrogen to atomize diluted acidic and alkaline solutions into tiny droplets, combined with high-speed rotation and nitrogen purging, to achieve comprehensive cleaning and avoid secondary adsorption.
This effectively avoids wafer corrosion, reduces surface roughness, ensures the cleanliness and flatness of the wafer surface, and improves the compatibility of subsequent processes and device performance.
Smart Images
Figure CN121604749A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of semiconductor materials, and more particularly to an atomization cleaning method for indium phosphide wafers. Background Technology
[0002] Indium phosphide (InP) wafers are a key material for high-end optoelectronic and microelectronic devices. During device fabrication, various contaminants inevitably adsorb onto the surface of the InP wafer, primarily including: organic residues (such as photoresist residue, polymer impurities, and environmental organic pollutants), and metal ion contaminants (such as sodium ions). + K + Fe 3+ Cu 2+ Indium phosphide (IP) wafers contain various contaminants, including indium phosphide (IP) wafers and natural oxide layers (primarily In₂O₃, P₂O₅, and hydroxide composite layers). These surface contaminants can severely affect the compatibility of subsequent thin film deposition, photolithography, etching, and other processes. Therefore, achieving efficient and thorough removal of surface contaminants from IPT wafers is a core prerequisite for ensuring the quality of high-end optoelectronic and microelectronic device fabrication.
[0003] Currently, the most widely used wafer cleaning solution in the industry is the traditional RCA wet chemical cleaning process, which removes contaminants through a combination of two chemical solutions: one is SC-1 cleaning solution, which uses the strong oxidizing properties of hydroxyl radicals to decompose organic contaminants and uses the high pH value of the solution to make the wafer surface negatively charged, thereby removing particulate impurities through electrostatic repulsion; the other is SC-2 cleaning solution, which uses hydrochloric acid to form soluble chlorides with metal ions to dissolve and remove metal contaminants. However, applying the traditional RCA wet chemical cleaning process to indium phosphide wafers presents several insurmountable technical drawbacks: First, indium phosphide itself is chemically reactive, and both the highly alkaline environment of SC-1 cleaning solution and the acidic environment of SC-2 cleaning solution will react chemically with the surface of the indium phosphide wafer, leading to significant corrosion and the formation of uneven corrosion pits or etching marks. Second, prolonged chemical immersion will damage the atomic-level flatness of the wafer surface, resulting in a significant increase in surface roughness, which in turn affects the interfacial bonding quality between the thin film and the wafer in subsequent device fabrication, as well as the electrical and optical performance of the device. In addition, issues such as residual components of the chemical solution during the cleaning process and incomplete rinsing after cleaning can easily introduce new contaminants onto the wafer surface, causing secondary pollution and further reducing the cleaning effect.
[0004] The aforementioned defects severely limit the application of traditional RCA wet chemical cleaning processes in the fabrication of high-end indium phosphide-based optoelectronic and microelectronic devices. Therefore, how to develop an efficient cleaning technology for indium phosphide wafers that can avoid wafer corrosion, reduce surface roughness, and eliminate secondary pollution has become an urgent technical problem to be solved in this field. Summary of the Invention
[0005] In view of this, the purpose of this application is to provide an atomization cleaning method for indium phosphide wafers, which solves the technical defects of traditional RCA wet chemical cleaning process, such as easy corrosion of wafers, reduction of wafer surface roughness, and generation of secondary pollution.
[0006] To achieve the above-mentioned technical objectives, this application provides an atomization cleaning method for indium phosphide wafers, comprising the following steps:
[0007] Step S1: The indium phosphide wafer rotating at a constant speed is atomized and cleaned sequentially with a first acidic solution and deionized water. After cleaning, it is dried by purging with nitrogen.
[0008] Step S2: The indium phosphide wafer rotating at a constant speed is atomized and cleaned sequentially with alkaline peroxide solution and deionized water. After cleaning, it is dried by purging with nitrogen.
[0009] In step S3, the indium phosphide wafer rotating at a constant speed is sequentially atomized and cleaned using a second acidic solution and deionized water. After cleaning, nitrogen gas is used for purging and drying to obtain a clean indium phosphide wafer.
[0010] Furthermore, the atomization cleaning is achieved through a high-pressure nitrogen atomization system with an atomization pressure of 0.2MPa~0.4MPa and a droplet size of 1μm~30μm.
[0011] Furthermore, the first acidic solution includes one of a hydrochloric acid solution with a mass concentration of 0.1% to 5% and a citric acid solution with a mass concentration of 0.1% to 5%.
[0012] Furthermore, the mass concentration of the hydrochloric acid solution is 0.5% to 2%; and / or, the mass concentration of the citric acid solution is 0.5% to 2%.
[0013] Furthermore, in step S1, the atomization cleaning time of the first acidic solution is 30s~120s; the atomization cleaning time of deionized water is 60s~180s; and the nitrogen purging time is 10s~30s.
[0014] Furthermore, the alkaline peroxide solution is SC-1 solution; in the SC-1 solution, the mass ratio of ammonia, hydrogen peroxide and deionized water is 0.05~0.5:0.05~0.5:5.
[0015] Furthermore, in step S2, the atomization cleaning time of the alkaline peroxide solution is 60s~180s; the atomization cleaning time of the deionized water is 60s~180s; and the nitrogen purging time is 10s~30s.
[0016] Furthermore, the second acidic solution includes at least one of SC-2 solution and hydrofluoric acid solution; in the SC-2 solution, the mass ratio of hydrochloric acid, hydrogen peroxide and deionized water is 0.05~0.5:0.05~0.5:5; the mass concentration of the hydrofluoric acid solution is 0.1%~5%.
[0017] Furthermore, in step S3, the atomization cleaning time of the second acidic solution is 30s~120s; the atomization cleaning time of deionized water is 120s~240s; and the nitrogen purging time is 30s~60s.
[0018] Furthermore, in steps S1, S2 and S3, during atomization cleaning, the rotation speed of the indium phosphide wafer is 100 r / min to 800 r / min; in step S3, during nitrogen purging, the rotation speed of the indium phosphide wafer is 1500 r / min to 3000 r / min.
[0019] In summary, this application provides an atomization cleaning method for indium phosphide wafers, comprising the following steps:
[0020] The indium phosphide wafers rotating at a constant speed are sequentially atomized and cleaned using a first acidic solution and deionized water, followed by nitrogen purging and drying. Then, an alkaline peroxide solution and deionized water are used sequentially for the same atomized cleaning process, followed by nitrogen purging and drying. Finally, a second acidic solution and deionized water are used sequentially for atomized cleaning, followed by nitrogen purging and drying, resulting in clean indium phosphide wafers. The indium phosphide wafer atomization cleaning method provided in this application constructs a complete cleaning system based on a three-step chemical synergistic mechanism of "acid-base-acid." This cleaning system covers various contaminants such as oxides, organic matter, particles, and metal ions, achieving a comprehensive and thorough cleaning effect, solving the technical pain point of incomplete cleaning in traditional processes. Furthermore, the high-speed rotating wafers instantly detach reaction products and waste liquid through centrifugal force, avoiding secondary adsorption.
[0021] Compared to existing technologies, this application transforms "immersion corrosion" into a controllable "micro-area reaction" by significantly diluting and atomizing the highly corrosive SC-1 / SC-2 solution, thus enabling the safe and efficient application of acid and alkali reagents in the cleaning of indium phosphide wafers. Furthermore, because the wafer only comes into short-term contact with the droplets during atomized cleaning, and the concentration at contact is low, the surface roughness of the wafer is stably controlled below 0.15 nm RMS, resulting in performance far superior to traditional processes. Attached Figure Description
[0022] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0023] Figure 1 This is a schematic flowchart of an atomization cleaning method for indium phosphide wafers provided in an embodiment of this application. Detailed Implementation
[0024] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Based on the embodiments in this application specification, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection claimed in this application.
[0025] In the description of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating the orientation or positional relationship shown, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.
[0026] Unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.
[0027] The raw materials used in this invention are not particularly restricted in their source; they can be purchased on the market or prepared using conventional methods known to those skilled in the art.
[0028] See Figure 1 This application provides an atomization cleaning method for indium phosphide wafers. The entire process is carried out in a closed, temperature-controlled process chamber, with the indium phosphide wafer constantly rotating at high speed to ensure uniform contact between the cleaning solution and the wafer surface, and efficient removal of residual solution. The cleaning steps are as follows:
[0029] Step S1: The indium phosphide wafer rotating at a constant speed is atomized and cleaned sequentially with a first acidic solution and deionized water. After cleaning, it is dried by purging with nitrogen.
[0030] Step S2: The indium phosphide wafer rotating at a constant speed is atomized and cleaned sequentially with alkaline peroxide solution and deionized water. After cleaning, it is dried by purging with nitrogen.
[0031] In step S3, the indium phosphide wafer rotating at a constant speed is sequentially atomized and cleaned using a second acidic solution and deionized water. After cleaning, nitrogen gas is used for purging and drying to obtain a clean indium phosphide wafer.
[0032] It should be noted that the first acidic solution atomization cleaning is used for pre-cleaning of the indium phosphide wafer to remove oxides; the alkaline peroxide solution atomization cleaning is used to remove organic contaminants and particles from the surface of the indium phosphide wafer; and the second acidic solution atomization cleaning is used for passivation and final purification of the indium phosphide wafer surface. During cleaning, liquid and gas are sprayed out together and atomized into particles. The dual-fluid nozzle oscillates back and forth from the center of the wafer to its two edges, and the speed gradually increases as it oscillates towards the center of the wafer until cleaning is complete, ensuring uniform contact between the solution and the surface of the indium phosphide wafer and efficiently removing residual liquid.
[0033] In some embodiments, atomized cleaning is achieved through a high-pressure nitrogen atomization system, with an atomization pressure of 0.2 MPa to 0.4 MPa and a droplet size of 1 μm to 30 μm.
[0034] In some embodiments, the first acidic solution includes one of a hydrochloric acid solution with a mass concentration of 0.1% to 5% and a citric acid solution with a mass concentration of 0.1% to 5%. In some preferred embodiments, the mass concentration of the hydrochloric acid solution is 0.5% to 2%; and / or, the mass concentration of the citric acid solution is 0.5% to 2%. In some specific embodiments, in step S1, the atomization cleaning time of the first acidic solution is 30s to 120s; the atomization cleaning time of deionized water is 60s to 180s; and the nitrogen purging time is 10s to 30s.
[0035] It should be noted that the first acidic solution can gently remove the natural oxide layer and some metal contaminants from the wafer surface, and the physicochemical damage to the wafer surface is controlled at an extremely low level.
[0036] In some embodiments, the alkaline peroxide solution is SC-1 solution; in the SC-1 solution, the mass ratio of ammonia, hydrogen peroxide, and deionized water is 0.05~0.5:0.05~0.5:5. In some specific embodiments, in step S2, the atomization cleaning time of the alkaline peroxide solution is 60s~180s; the atomization cleaning time of the deionized water is 60s~180s; and the nitrogen purging time is 10s~30s.
[0037] It should be noted that in this embodiment, the concentration of the SC-1 solution is much lower than that of the SC-1 concentration in the standard RCA process, which can significantly reduce the risk of corrosion to the indium phosphide wafer. Through the synergistic mechanism of "extremely diluted system + atomized short-time contact", the formation of corrosion pits or etching marks on the wafer surface is effectively avoided while retaining the high efficiency of the SC-1 solution in removing organic contaminants and particles, thus ensuring the integrity of the wafer surface.
[0038] In some embodiments, the second acidic solution includes at least one of SC-2 solution and hydrofluoric acid solution; in the SC-2 solution, the mass ratio of hydrochloric acid, hydrogen peroxide and deionized water is 0.05~0.5:0.05~0.5:5; the mass concentration of the hydrofluoric acid solution is 0.1%~5%.
[0039] In some specific embodiments, in step S3, the atomization cleaning time of the second acidic solution is 30s~120s; the atomization cleaning time of deionized water is 120s~240s; and the nitrogen purging time is 30s~60s.
[0040] It should be noted that the core function of the second acidic solution atomization cleaning is to achieve final passivation and slight etching of the wafer surface to obtain a surface with atomic-level cleanliness and flatness; at the same time, with the flushing effect of high-flow-rate atomized deionized water, residual salts, metal ions and organic debris on the wafer surface are thoroughly removed to ensure the purity of the wafer surface.
[0041] In some embodiments, during atomization cleaning in steps S1, S2 and S3, the rotation speed of the indium phosphide wafer is 100 r / min to 800 r / min; during nitrogen purging in step S3, the rotation speed of the indium phosphide wafer is 1500 r / min to 3000 r / min.
[0042] It should be noted that the synergistic effect of "high-speed centrifugal force field + nitrogen purging" accelerates the removal and evaporation of moisture from the wafer surface, while the inert atmosphere of nitrogen prevents secondary oxidation of the wafer surface.
[0043] The applicant further provides the following specific embodiments to describe the present invention. It should be noted that these embodiments are merely descriptive and do not limit the present invention in any way.
[0044] Example 1
[0045] This embodiment provides an atomization cleaning method for indium phosphide wafers, which is carried out entirely within a closed, temperature-controlled process chamber. The indium phosphide wafer is specifically a 4-inch InP-Fe semi-insulating indium phosphide wafer, and it is constantly rotating at high speed. The specific steps are as follows:
[0046] Step S1, Atomization cleaning with the first acidic solution: The rotation speed of the indium phosphide wafer is set to 400 r / min, and a hydrochloric acid solution with a mass concentration of 0.1% is used as the first acidic solution; the first acidic solution is atomized into hydrochloric acid droplets with an average particle size of 5 μm through a high-pressure nitrogen atomization system, and the atomization pressure is 0.3 MPa; the atomized hydrochloric acid droplets are uniformly sprayed onto the wafer surface for 50 s;
[0047] Step S2, First Atomization Rinse and Purge: Stop the supply of the first acidic solution and switch to deionized water. Atomize the deionized water into droplets with an average particle size of 5 μm using a high-pressure nitrogen atomization system to rinse the wafer surface for 120 seconds. After rinsing, purge the wafer surface with nitrogen (purity ≥99.999%) for 20 seconds.
[0048] Step S3, alkaline peroxide solution atomization cleaning: SC-1 solution (mass ratio of ammonia, hydrogen peroxide and deionized water of 0.1:0.1:5) is used as alkaline peroxide cleaning solution; a high-pressure nitrogen atomization system is used to atomize the alkaline peroxide cleaning solution into droplets with an average particle size of 5μm, which are then sprayed onto the wafer surface and cleaned continuously for 90s;
[0049] Step S4, Second Atomized Rinsing and Purging: Stop the supply of alkaline peroxide cleaning solution and switch to deionized water. Atomize the deionized water into droplets with an average particle size of 10~20μm using a high-pressure nitrogen atomization system to rinse the wafer surface for 150s. After rinsing, purge the wafer surface with nitrogen (purity ≥99.999%) for 20s.
[0050] Step S5, second acidic solution atomization cleaning: SC-2 solution (hydrochloric acid, hydrogen peroxide and deionized water in a mass ratio of 0.1:0.1:5) is used as the second acidic solution; the second acidic solution is atomized into droplets with an average particle size of 5μm through a high-pressure nitrogen atomization system and sprayed onto the wafer surface for continuous cleaning for 60s;
[0051] Step S6, final atomization rinse: Stop the supply of the second acidic solution and switch to deionized water. Use a high-pressure nitrogen atomization system to atomize the deionized water into droplets with an average particle size of 5μm to perform atomization rinse on the wafer surface for 180s.
[0052] Step S7, Rotary Drying: Stop the supply of deionized water and increase the wafer rotation speed to 2500 r / min; introduce nitrogen gas (purity ≥99.999%) to purge the wafer surface for 60 s to obtain a clean indium phosphide wafer.
[0053] In this embodiment, during cleaning, liquid and gas are sprayed out together and atomized into particles. The dual-fluid nozzle oscillates back and forth from the center of the wafer to its two edges, and the speed gradually increases as it oscillates towards the center of the wafer until cleaning is complete, ensuring uniform contact between the solution and the surface of the indium phosphide wafer and efficiently removing residual liquid. Example 2
[0054] This embodiment provides an atomization cleaning method for indium phosphide wafers. The entire process is carried out in a closed, temperature-controlled process chamber. The indium phosphide wafer is specifically a 3-inch InP-S semi-insulating indium phosphide wafer, and the wafer is constantly rotating at high speed to ensure uniform contact between the cleaning solution and the wafer surface and efficient removal of residual solution. The specific steps are as follows:
[0055] Step S1, Atomization cleaning with the first acidic solution: The rotation speed of the indium phosphide wafer is set to 600 r / min, and a citric acid solution with a mass concentration of 0.1% is used as the first acidic solution; the first acidic solution is atomized into hydrochloric acid droplets with an average particle size of 8 μm through a high-pressure nitrogen atomization system, and the atomization pressure is 0.25 MPa; the atomized citric acid droplets are uniformly sprayed onto the wafer surface for 75 s;
[0056] Step S2, First Atomization Rinse and Purge: Stop the supply of the first acidic solution and switch to deionized water. Atomize the deionized water into droplets with an average particle size of 8 μm using a high-pressure nitrogen atomization system to rinse the wafer surface for 100 seconds. After rinsing, purge the wafer surface with nitrogen (purity ≥99.999%) for 15 seconds.
[0057] Step S3, alkaline peroxide solution atomization cleaning: SC-1 solution (mass ratio of ammonia, hydrogen peroxide and deionized water of 0.15:0.15:5) is used as alkaline peroxide cleaning solution; a high-pressure nitrogen atomization system is used to atomize the alkaline peroxide cleaning solution into droplets with an average particle size of 10μm at an atomization pressure of 0.3MPa, and spray them onto the wafer surface for continuous cleaning for 80s;
[0058] Step S4, Second Atomized Rinsing and Purging: Stop the supply of alkaline peroxide cleaning solution and switch to deionized water. Atomize the deionized water into droplets with an average particle size of 10~20μm using a high-pressure nitrogen atomization system to rinse the wafer surface for 120s. After rinsing, purge the wafer surface with nitrogen (purity ≥99.999%) for 20s.
[0059] Step S5, second acidic solution atomization cleaning: a hydrofluoric acid solution with a mass fraction of 0.5% is used as the second acidic solution; the second acidic solution is atomized into droplets with an average particle size of 5μm through a high-pressure nitrogen atomization system at an atomization pressure of 0.2MPa, and sprayed onto the wafer surface for continuous cleaning for 30s;
[0060] Step S6, final atomization rinse: Stop the supply of the second acidic solution and switch to deionized water. Use a high-pressure nitrogen atomization system to atomize the deionized water into droplets with an average particle size of 5μm to perform atomization rinse on the wafer surface for 180s.
[0061] Step S7, Rotary Drying: Stop the supply of deionized water and increase the wafer rotation speed to 2200 r / min; introduce nitrogen gas (purity ≥99.999%) to purge the wafer surface for 45 s to obtain a clean indium phosphide wafer.
[0062] In this embodiment, during cleaning, liquid and gas are sprayed out together and atomized into particles. The dual-fluid nozzle oscillates back and forth from the center of the wafer to its two sides, and the speed gradually increases when oscillating towards the center of the wafer until cleaning is completed, ensuring that the solution makes uniform contact with the surface of the indium phosphide wafer and efficiently removes residual liquid.
[0063] Comparative Example 1
[0064] This comparative example provides an atomization cleaning method for indium phosphide wafers. The entire process is conducted within a closed, temperature-controlled process chamber. The indium phosphide wafer is specifically a 4-inch InP-Fe semi-insulating indium phosphide wafer, which is constantly rotating at high speed to ensure uniform contact between the cleaning solution and the wafer surface, and efficient removal of residual solution. The specific steps are as follows:
[0065] Step S1, alkaline peroxide solution atomization cleaning: SC-1 solution (mass ratio of ammonia, hydrogen peroxide and deionized water of 0.1:0.1:5) is used as alkaline peroxide cleaning solution; the alkaline peroxide cleaning solution is atomized into droplets with an average particle size of 5μm using a high-pressure nitrogen atomization system and sprayed onto the wafer surface for 90s.
[0066] Step S2, Second Atomized Rinsing and Purging: Stop the supply of alkaline peroxide cleaning solution and switch to deionized water. Atomize the deionized water into droplets with an average particle size of 10~20μm using a high-pressure nitrogen atomization system to rinse the wafer surface for 150s. After rinsing, purge the wafer surface with nitrogen (purity ≥99.999%) for 20s.
[0067] Step S3, second acidic solution atomization cleaning: SC-2 solution (hydrochloric acid, hydrogen peroxide and deionized water in a mass ratio of 0.1:0.1:5) is used as the second acidic solution; the second acidic solution is atomized into droplets with an average particle size of 5μm through a high-pressure nitrogen atomization system and sprayed onto the wafer surface for continuous cleaning for 60s;
[0068] Step S4, final atomization rinse: Stop the supply of the second acidic solution and switch to deionized water. Use a high-pressure nitrogen atomization system to atomize the deionized water into droplets with an average particle size of 5μm to perform atomization rinse on the wafer surface for 60s.
[0069] Step S5, Rotary Drying: Stop the supply of deionized water and increase the wafer rotation speed to 2500 r / min; introduce nitrogen gas (purity ≥99.999%) to purge the wafer surface for 60 s.
[0070] In this embodiment, the surface cleanliness of the indium phosphide wafer is insufficient. The native natural oxide layer on the wafer surface was not effectively removed. This oxide layer forms a physical barrier, significantly weakening the contact efficiency between the alkaline solution and the underlying organic matter and particulate contaminants, hindering the full progress of the interfacial reaction, and ultimately leading to a significant reduction in the organic matter removal rate. At the same time, the native oxide layer itself has uneven thickness, further exacerbating the non-uniformity of the surface state.
[0071] Comparative Example 2
[0072] This comparative example provides an atomization cleaning method for indium phosphide wafers. The entire process is conducted within a closed, temperature-controlled process chamber. The indium phosphide wafer is specifically a 4-inch InP-Fe semi-insulating indium phosphide wafer, which is constantly rotating at high speed to ensure uniform contact between the cleaning solution and the wafer surface, and efficient removal of residual solution. The specific steps are as follows:
[0073] Step S1, Atomization cleaning with the first acidic solution: The rotation speed of the indium phosphide wafer is set to 400 r / min, and a hydrochloric acid solution with a mass concentration of 0.1% is used as the first acidic solution; the first acidic solution is atomized into hydrochloric acid droplets with an average particle size of 5 μm through a high-pressure nitrogen atomization system, and the atomization pressure is 0.3 MPa; the atomized hydrochloric acid droplets are uniformly sprayed onto the wafer surface for 50 s;
[0074] Step S2, First Atomization Rinse and Purge: Stop the supply of the first acidic solution and switch to deionized water. Atomize the deionized water into droplets with an average particle size of 5 μm using a high-pressure nitrogen atomization system to rinse the wafer surface for 120 seconds. After rinsing, purge the wafer surface with nitrogen (purity ≥99.999%) for 20 seconds.
[0075] Step S3, alkaline peroxide solution atomization cleaning: SC-1 solution (mass ratio of ammonia, hydrogen peroxide and deionized water of 0.1:0.1:5) is used as alkaline peroxide cleaning solution; a high-pressure nitrogen atomization system is used to atomize the alkaline peroxide cleaning solution into droplets with an average particle size of 5μm, which are then sprayed onto the wafer surface and cleaned continuously for 90s;
[0076] Step S4, Second Atomization Rinse and Purge: Stop the supply of alkaline peroxide cleaning solution and switch to deionized water. Atomize the deionized water into droplets with an average particle size of 10~20μm using a high-pressure nitrogen atomization system to perform atomization rinsing on the wafer surface for 150s. After rinsing, purge the wafer surface with nitrogen (purity ≥99.999%) for 20s.
[0077] In this comparative example, the surface quality stability of indium phosphide (InP) wafers was poor. After alkaline washing, the InP wafers exhibited strong hydrophilicity and significantly increased chemical activity. During subsequent rinsing and drying, they were highly susceptible to interaction with trace impurities in the environment, leading to secondary pollution, or slow oxidation reactions due to contact with air. Furthermore, alkaline peroxide cleaning solutions (such as ammonia-containing aqueous solutions) introduced trace metal ions (such as... The process lacks a subsequent SC-2 pickling step to remove residual metal ions, leading to the accumulation of metal impurities on the wafer surface, which may induce interface electrical defects and affect device performance.
[0078] Comparative Example 3
[0079] This comparative example provides an atomization cleaning method for indium phosphide wafers. The entire process is conducted within a closed, temperature-controlled process chamber. The indium phosphide wafer is specifically a 4-inch InP-Fe semi-insulating indium phosphide wafer, which is constantly rotating at high speed to ensure uniform contact between the cleaning solution and the wafer surface, and efficient removal of residual solution. The specific steps are as follows:
[0080] Step S1, alkaline peroxide solution atomization cleaning: Set the rotation speed of the indium phosphide wafer to 400 r / min, and use SC-1 solution (mass ratio of ammonia, hydrogen peroxide and deionized water of 0.1:0.1:5) as the alkaline peroxide cleaning solution; use a high-pressure nitrogen atomization system to atomize the alkaline peroxide cleaning solution into droplets with an average particle size of 5 μm, spray them onto the wafer surface, and continue cleaning for 90 s;
[0081] Step S2, Second Atomized Rinsing and Purging: Stop the supply of alkaline peroxide cleaning solution and switch to deionized water. Atomize the deionized water into droplets with an average particle size of 10~20μm using a high-pressure nitrogen atomization system to rinse the wafer surface for 150s. After rinsing, purge the wafer surface with nitrogen (purity ≥99.999%) for 20s.
[0082] Step S3, first acidic solution atomization cleaning: a hydrochloric acid solution with a mass concentration of 0.1% is used as the first acidic solution; the first acidic solution is atomized into hydrochloric acid droplets with an average particle size of 5μm through a high-pressure nitrogen atomization system, and the atomization pressure is 0.3MPa; the atomized hydrochloric acid droplets are uniformly sprayed onto the wafer surface for 50s.
[0083] Step S4, First Atomization Rinse and Purge: Stop the supply of the first acidic solution and switch to deionized water. Atomize the deionized water into droplets with an average particle size of 5 μm using a high-pressure nitrogen atomization system to rinse the wafer surface for 120 seconds. After rinsing, purge the wafer surface with nitrogen (purity ≥99.999%) for 20 seconds.
[0084] Step S5, second acidic solution atomization cleaning: SC-2 solution (hydrochloric acid, hydrogen peroxide and deionized water in a mass ratio of 0.1:0.1:5) is used as the second acidic solution; the second acidic solution is atomized into droplets with an average particle size of 5μm through a high-pressure nitrogen atomization system and sprayed onto the wafer surface for continuous cleaning for 60s;
[0085] Step S6, final atomization rinse: Stop the supply of the second acidic solution and switch to deionized water. Use a high-pressure nitrogen atomization system to atomize the deionized water into droplets with an average particle size of 5μm to perform atomization rinse on the wafer surface for 60s.
[0086] Step S7, Rotary Drying: Stop the supply of deionized water and increase the wafer rotation speed to 2500 r / min; introduce nitrogen gas (purity ≥99.999%) to purge the wafer surface for 60 s.
[0087] In this comparative example, the cleaning process did not follow the scientific principle of "removing the oxide layer first and then removing contaminants". Alkali washing was carried out directly without removing the oxide layer, which greatly reduced the contaminant desorption efficiency. To compensate for the insufficient cleaning effect, if the alkali concentration is increased or the treatment time is extended, the risk of chemical corrosion of the InP wafer will be significantly increased, which may lead to increased wafer surface roughness and damage to lattice integrity.
[0088] Comparative Example 4
[0089] This comparative example provides an atomization cleaning method for indium phosphide wafers. The entire process is conducted within a closed, temperature-controlled process chamber. The indium phosphide wafer is specifically a 4-inch InP-Fe semi-insulating indium phosphide wafer, which is constantly rotating at high speed to ensure uniform contact between the cleaning solution and the wafer surface, and efficient removal of residual solution. The specific steps are as follows:
[0090] Step S1, alkaline peroxide solution atomization cleaning: Set the rotation speed of the indium phosphide wafer to 400 r / min, and use SC-1 solution (mass ratio of ammonia, hydrogen peroxide and deionized water of 0.1:0.1:5) as the alkaline peroxide cleaning solution; use a high-pressure nitrogen atomization system to atomize the alkaline peroxide cleaning solution into droplets with an average particle size of 5 μm, spray them onto the wafer surface, and continue cleaning for 90 s;
[0091] Step S2, Second atomized rinsing and purging: Stop the supply of alkaline peroxide cleaning solution, use overflow deionized water to immerse the wafer surface for 150 seconds; after rinsing, introduce nitrogen gas to purge the wafer surface for 20 seconds.
[0092] Step S3, second acidic solution atomization cleaning: SC-2 solution (hydrochloric acid, hydrogen peroxide and deionized water in a mass ratio of 0.1:0.1:5) is used as the second acidic solution; the second acidic solution is atomized into droplets with an average particle size of 5μm through a high-pressure nitrogen atomization system and sprayed onto the wafer surface for continuous cleaning for 60s;
[0093] Step S4, final atomization rinsing: Stop the supply of the second acidic solution, switch to deionized water, and use the overflowing deionized water to immerse the wafer surface for 60 seconds;
[0094] Step S5, Rotary Drying: Stop the supply of deionized water and increase the wafer rotation speed to 2500 r / min; introduce nitrogen gas to purge the wafer surface for 60 s.
[0095] In this comparative example, the risk of secondary contamination is prominent. During the immersion cleaning and subsequent rinsing process, the desorbed contaminants and residual metal ions in the system can easily re-adhere to the wafer surface through interfacial adsorption, forming secondary contamination and further deteriorating the cleanliness of the wafer surface.
[0096] The indium phosphide wafers treated by the cleaning methods provided in Example 1 and Comparative Examples 1 to 4 were characterized by X-ray photoelectron spectroscopy (XPS) to characterize the residual organic pollutants and the thickness of the natural oxide layer, and the metal ion contamination level was detected by total reflectance X-ray fluorescence spectroscopy (TXRF). The relevant test results are summarized in Table 1.
[0097] Table 1. Surface cleanliness of indium phosphide wafers under different cleaning methods
[0098]
[0099] The above are merely preferred embodiments of this application and are not intended to limit the present invention. Although this application has been described in detail with reference to examples, those skilled in the art can still modify the technical solutions described in the foregoing examples or make equivalent substitutions for some of the technical features. However, any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.
Claims
1. A method for atomizing and cleaning indium phosphide wafers, characterized in that, Includes the following steps: Step S1: The indium phosphide wafer rotating at a constant speed is atomized and cleaned sequentially with a first acidic solution and deionized water. After cleaning, it is dried by purging with nitrogen. Step S2: The indium phosphide wafer rotating at a constant speed is cleaned by atomization using alkaline peroxide solution and deionized water in sequence. After cleaning, it is dried by nitrogen purging. In step S3, the indium phosphide wafer rotating at a constant speed is sequentially atomized and cleaned using a second acidic solution and deionized water. After cleaning, nitrogen gas is used for purging and drying to obtain a clean indium phosphide wafer.
2. The atomization cleaning method for indium phosphide wafers according to claim 1, characterized in that, The atomized cleaning is achieved through a high-pressure nitrogen atomization system, with an atomization pressure of 0.2MPa to 0.4MPa and a droplet size of 1μm to 30μm.
3. The atomization cleaning method for indium phosphide wafers according to claim 1, characterized in that, The first acidic solution includes one of a hydrochloric acid solution with a mass concentration of 0.1% to 5% and a citric acid solution with a mass concentration of 0.1% to 5%.
4. The atomization cleaning method for indium phosphide wafers according to claim 3, characterized in that, The hydrochloric acid solution has a mass concentration of 0.5% to 2%; and / or, the citric acid solution has a mass concentration of 0.5% to 2%.
5. The atomization cleaning method for indium phosphide wafers according to claim 4, characterized in that, In step S1, the atomization cleaning time of the first acidic solution is 30s~120s; the atomization cleaning time of deionized water is 60s~180s; and the nitrogen purging time is 10s~30s.
6. The atomization cleaning method for indium phosphide wafers according to claim 1, characterized in that, The alkaline peroxide solution is an SC-1 solution; in the SC-1 solution, the mass ratio of ammonia, hydrogen peroxide and deionized water is 0.05~0.5:0.05~0.5:
5.
7. The atomization cleaning method for indium phosphide wafers according to claim 6, characterized in that, In step S2, the atomization cleaning time of the alkaline peroxide solution is 60s~180s; the atomization cleaning time of the deionized water is 60s~180s; and the nitrogen purging time is 10s~30s.
8. The atomization cleaning method for indium phosphide wafers according to claim 1, characterized in that, The second acidic solution includes at least one of SC-2 solution and hydrofluoric acid solution; in the SC-2 solution, the mass ratio of hydrochloric acid, hydrogen peroxide and deionized water is 0.05~0.5:0.05~0.5:5; the mass concentration of the hydrofluoric acid solution is 0.1%~5%.
9. The atomization cleaning method for indium phosphide wafers according to claim 8, characterized in that, In step S3, the atomization cleaning time of the second acidic solution is 30s~120s; the atomization cleaning time of deionized water is 120s~240s; and the nitrogen purging time is 30s~60s.
10. The atomization cleaning method for indium phosphide wafers according to claim 1, characterized in that, In steps S1, S2, and S3, during atomization cleaning, the rotation speed of the indium phosphide wafer is 100 r / min to 800 r / min; in step S3, during nitrogen purging, the rotation speed of the indium phosphide wafer is 1500 r / min to 3000 r / min.