Method for reducing chromatic aberration in silicon wafer cutting by using aminocarboxylic acid complexing agent
By adding amino carboxylic acid complexing agent and polyether modified silicone to the silicon wafer cutting liquid, the pH is adjusted to 7.5-8.5 to form a stable complex and a protective film, the problems of oxide layer inhomogeneity and chromatic aberration caused by metal ion contamination during the cutting of large-size silicon wafers are solved, and wettability is improved and cost reduction is achieved.
Patent Information
- Application Number
- CN202510473412.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-16
- Publication Date
- 2025-07-04
AI Technical Summary
In the cutting process of large-size silicon wafers, the problems of oxide layer inhomogeneity and color difference caused by metal ion pollution are difficult to effectively solve through existing methods and increase production costs or introduce wastewater treatment problems.
The amino carboxylic acid complexing agent and polyether modified silicone are used to form a stable complex in the cleavage liquid, adjust the pH to 7.5-8.5, enhance the complexing effect, anchor the silicon surface through the hydrophobic chain segment, enrich the complexing agent to form a dense protective film, solve the problem of wetting unevenness, and block the catalytic oxidation reaction of metal ions.
Effectively reduce chromatic aberration, improve the wettability of silicon wafers, reduce the formation of local oxide layers, reduce production costs by 20%, and does not require equipment modification, which is more economical than pickling technology.
Smart Images
Figure CN120248968A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of photovoltaic material processing, and specifically to a method for reducing color difference in silicon wafer cutting using an amino carboxylic acid complexing agent. Background Art
[0002] Silicon wafers are important upstream materials in the semiconductor and photovoltaic fields. The production cost and efficiency of solar cells are directly related to the size of silicon wafers. Increasing the diameter of silicon wafers can increase the effective light-receiving area of the cells to improve the efficiency of modules, thereby providing higher economies of scale. With the development of technology and the pursuit of cost reduction and efficiency improvement, the diamond wire cutting technology for silicon wafers is continuously developing towards larger sizes, thinner wafers, higher wire speeds, and thinner wires. The surface area of large-size silicon wafers (such as 210 mm) increases, and the penetration and wettability of the cutting fluid in the central area of the silicon wafer decrease, resulting in significant differences in lubrication and cooling effects between the central area and the edge, which in turn leads to uneven thickness of the oxide layer and color difference. The trend of thinner wafers further amplifies the impact of cutting process instability and indirectly exacerbates the oxidation color difference. The color difference is mainly due to the uneven surface oxide layer caused by the pollution of metal ions (such as Fe3+, Ni 2 + etc.) during the cutting process, resulting in rainbow color difference, and the reflectivity difference of the finished silicon wafers reaches 8 - 12%. When cutting large-size silicon wafers, the contact area between the wire and the silicon wafer increases, and the total amount of metal ions released by wire wear increases, and the abnormal color difference ratio of the silicon wafers increases.
[0003] Although the existing technology can improve the color difference by increasing the pickling process, it leads to a 15% increase in production cost and generates wastewater treatment problems. Although it can reduce physical damage, it cannot inhibit the chemical oxidation of metal ions, and it depends on equipment modification and is difficult to be compatible with the existing production line. Summary of the Invention
[0004] In view of the deficiencies of the prior art, the present invention provides a method for reducing color difference in silicon wafer cutting using an amino carboxylic acid complexing agent, which solves the problems raised in the above background.
[0005] To achieve the above objectives, the present invention is realized through the following technical solutions: A method for reducing color difference in silicon wafer cutting using an amino carboxylic acid complexing agent, specifically including the following steps:
[0006] S1. Selection and concentration of the complexing agent: Add 0.1 - 3 wt% of the complexing agent to the cutting fluid to ensure the formation of a stable water-soluble complex with metal ions. The weight and percentage of the cutting fluid are: polyethylene glycol 10 - 20 wt%, amino carboxylic acid complexing agent 0.5 - 1.5 wt%, polyether-modified silicone 0.05 - 0.1 wt%, pH regulator 5 - 10 wt%, and deionized water 10 - 20 wt%.
[0007] S2, pH Coordination Regulation: Adjust the pH of the cutting fluid to 7.5 - 8.5, and enhance the complexing efficiency through the following mechanisms:
[0008] (1) High Degree of Dissociation: The degree of dissociation of amino carboxylic acid increases under alkaline conditions, the charge distribution of carboxylic acid groups and amino groups is optimized, and the coordination of metal ions is accelerated;
[0009] (2) Oxidation Inhibition: pH 7.5 - 8.5 can reduce the oxidation activity of hydroxyl groups on the silicon surface and reduce the formation of local oxide layers;
[0010] S3, Interface Adsorption Enhancement: Add 0.05 - 0.1 wt% of polyether-modified siloxane. The hydrophobic chain segment (siloxane) anchors on the silicon surface, and the hydrophilic chain segment (polyether) enriches the complexing agent to form a dense protective film, reducing the surface tension of the cutting fluid, solving the problem of uneven wetting of large-size silicon wafers, and increasing the local concentration of the complexing agent by more than 50%.
[0011] Preferably, in S1, the complexing agent is selected from one or more of ethylenediaminetetraacetic acid, nitrilotriacetic acid, or diethylenetriaminepentaacetic acid. The amino carboxylic acid complexing agent forms five-membered or six-membered ring chelates with metal ions through six coordination sites (four carboxylic acid oxygen atoms and two amino nitrogen atoms), and the stability constant logK of the stable water-soluble complex is > 16.
[0012] Preferably, in S1, in the cutting fluid, complexing agents such as EDTA preferentially bind to high-valent metal ions such as Fe3+ and Ni 2 + etc., blocking their catalytic oxidation reactions, and at the same time having a deep capture ability for low-concentration metal ions. Other ions present in the cutting fluid will not significantly interfere with the chelation of target metal ions because the stability constants of EDTA with these ions are relatively low.
[0013] Preferably, in S3, the hydrophobic chain segment is mainly a polydimethylsiloxane chain segment that forms a strong interaction with the silicon surface through Si - O - Si bonds to achieve anchoring; the hydrophilic chain segment is mainly a polyether chain segment that binds to water molecules and complexing agent molecules in the cutting fluid through hydrogen bonds to form an enrichment layer.
[0014] Preferably, in S3, the addition of polyether-modified siloxane reduces the surface tension of the cutting fluid from 72 mN / m to 35 - 40 mN / m, significantly improving the wettability of large-size silicon wafers and reducing the "dry spot" phenomenon during cutting.
[0015] Preferably, in S3, the addition of polyether-modified siloxane reduces the surface tension of the cutting fluid from 72 mN / m to 35 - 40 mN / m, significantly improving the wettability of large-size silicon wafers and reducing the "dry spot" phenomenon during cutting.
[0016] Beneficial Effects
[0017] The present invention provides a method for reducing color difference in silicon wafer cutting using an amino carboxylic acid complexing agent. Compared with the prior art, it has the following beneficial effects: The method for reducing color difference in silicon wafer cutting using an amino carboxylic acid complexing agent specifically includes the following steps: S1. Complexing agent selection and concentration: Add 0.1-3 wt% of the complexing agent to the cutting fluid to ensure the formation of a stable water-soluble complex with metal ions. The weight and percentage of the cutting fluid are as follows: polyethylene glycol 10-20 wt%, amino carboxylic acid complexing agent 0.5-1.5 wt%, polyether-modified silicone 0.05-0.1 wt%, pH regulator 5-10 wt%, and deionized water 10-20 wt%; S2. pH co-regulation: Adjust the pH of the cutting fluid to 7.5-8.5, and enhance the complexing efficiency through the following mechanisms: (1) High dissociation degree: The dissociation degree of amino carboxylic acid increases under alkaline conditions, and the charge distribution of the carboxylic acid group and the amino group is optimized, accelerating the coordination of metal ions; (2) Inhibition of oxidation: pH 7.5-8.5 can reduce the oxidation activity of the hydroxyl groups on the silicon surface and reduce the formation of local oxide layers; S3. Interface adsorption enhancement: Add 0.05-0.1 wt% of polyether-modified silicone. The hydrophobic segment (silicone) anchors to the silicon surface, and the hydrophilic segment (polyether) enriches the complexing agent to form a dense protective film, reducing the surface tension of the cutting fluid, solving the problem of uneven wetting of large-size silicon wafers, and increasing the local concentration of the complexing agent by more than 50%; Select an amino carboxylic acid complexing agent with a stability constant logK>16, far exceeding phytic acid (logK = 8-10) and conventional chelating agents, and capable of achieving deep capture of Fe3+ and Ni 2 +, blocking the catalytic oxidation chain reaction; By adjusting the pH of the cutting fluid to 7.5-8.5, utilize the high dissociation degree of amino carboxylic acid in an alkaline environment to enhance the complexing efficiency, and at the same time inhibit the oxidation activity of the hydroxyl groups (-OH) on the silicon surface; Introduce polyether-modified silicone (0.05-0.1 wt%), anchor to the silicon surface through the hydrophobic chain and enrich the complexing agent through the hydrophilic chain to form a "molecular brush" structure, increasing the local concentration of the complexing agent by more than 50% and solving the problem of uneven wetting of large-size silicon wafers; Directly add it to the existing cutting fluid without equipment modification, reducing the comprehensive cost by 20% compared with the pickling process. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] Figure 1 It is a flowchart of the steps of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS
[0019] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.
[0020] Please refer toFigure 1 , the present invention provides three technical solutions: a method for reducing color difference in silicon wafer cutting using an amino carboxylic acid complexing agent, specifically including the following embodiments:
[0021] Example 1
[0022] S1. Complexing agent selection and concentration: Add 2 wt% of the complexing agent to the cutting fluid to ensure the formation of a stable water-soluble complex with metal ions. The weight and percentage of the cutting fluid are: polyethylene glycol 15 wt%, amino carboxylic acid complexing agent 1 wt%, polyether-modified silicone 0.07 wt%, pH regulator 7 wt%, and deionized water 15 wt%;
[0023] S2. pH co-regulation: Adjust the pH of the cutting fluid to 8 to enhance the complexing efficiency through the following mechanism:
[0024] (1) High dissociation degree: The dissociation degree of amino carboxylic acid increases under alkaline conditions, optimizing the charge distribution of the carboxylic acid group and the amino group, and accelerating the coordination of metal ions;
[0025] (2) Oxidation inhibition: pH 8 can reduce the oxidation activity of the hydroxyl groups on the silicon surface and reduce the formation of local oxide layers;
[0026] S3. Interface adsorption enhancement: Add 0.07 wt% of polyether-modified silicone. The hydrophobic segment (silicone) anchors on the silicon surface, and the hydrophilic segment (polyether) enriches the complexing agent to form a dense protective film, reducing the surface tension of the cutting fluid, solving the problem of uneven wetting of large-size silicon wafers, and increasing the local concentration of the complexing agent by more than 50%.
[0027] Example 2
[0028] S1. Complexing agent selection and concentration: Add 0.1 wt% of the complexing agent to the cutting fluid to ensure the formation of a stable water-soluble complex with metal ions. The weight and percentage of the cutting fluid are: polyethylene glycol 10 wt%, amino carboxylic acid complexing agent 0.5 wt%, polyether-modified silicone 0.05 wt%, pH regulator 5 wt%, and deionized water 10 wt%;
[0029] S2. pH co-regulation: Adjust the pH of the cutting fluid to 7.5 to enhance the complexing efficiency through the following mechanism:
[0030] (1) High dissociation degree: The dissociation degree of amino carboxylic acid increases under alkaline conditions, optimizing the charge distribution of the carboxylic acid group and the amino group, and accelerating the coordination of metal ions;
[0031] (2) Oxidation inhibition: pH 7.5 can reduce the oxidation activity of the hydroxyl groups on the silicon surface and reduce the formation of local oxide layers;
[0032] S3. Interface Adsorption Enhancement: Add 0.05 wt% of polyether-modified siloxane. The hydrophobic segment (siloxane) anchors on the silicon surface, and the hydrophilic segment (polyether) enriches the complexing agent to form a dense protective film, reducing the surface tension of the cutting fluid, solving the problem of uneven wetting of large-sized silicon wafers, and increasing the local concentration of the complexing agent by more than 50%.
[0033] Example 3
[0034] S1. Complexing Agent Selection and Concentration: Add 3 wt% of the complexing agent to the cutting fluid to ensure the formation of stable water-soluble complexes with metal ions. The weight and percentage of the cutting fluid are: polyethylene glycol 20 wt%, amino carboxylic acid complexing agent 1.5 wt%, polyether-modified siloxane 0.1 wt%, pH regulator 10 wt%, and deionized water 20 wt%.
[0035] S2. pH Coordination Regulation: Adjust the pH of the cutting fluid to 8.5 to enhance the complexing efficiency through the following mechanisms:
[0036] (1) High degree of dissociation: The degree of dissociation of amino carboxylic acid increases under alkaline conditions, and the charge distribution of the carboxylic acid group and the amino group is optimized, accelerating the coordination of metal ions;
[0037] (2) Inhibition of oxidation: pH 8.5 can reduce the oxidation activity of the hydroxyl groups on the silicon surface and reduce the formation of the local oxide layer;
[0038] S3. Interface Adsorption Enhancement: Add 0.1 wt% of polyether-modified siloxane. The hydrophobic segment (siloxane) anchors on the silicon surface, and the hydrophilic segment (polyether) enriches the complexing agent to form a dense protective film, reducing the surface tension of the cutting fluid, solving the problem of uneven wetting of large-sized silicon wafers, and increasing the local concentration of the complexing agent by more than 50%.
[0039] Meanwhile, the content not detailedly described in this specification belongs to the prior art well-known to those skilled in the art.
[0040] It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device.
[0041] Although embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.
Claims
1. A method for reducing color difference in silicon wafer cutting using an amino carboxylic acid complexing agent, characterized in that: Specifically, it includes the following steps: S1. Chelating agent selection and concentration: Add 0.1-3 wt% of a chelating agent to the cutting fluid to ensure the formation of a stable water-soluble complex with metal ions. The weight and percentage of the cutting fluid are as follows: polyethylene glycol 10-20 wt%, amino carboxylic acid chelating agent 0.5-1.5 wt%, polyether-modified silicone 0.05-0.1 wt%, pH regulator 5-10 wt%, and deionized water 10-20 wt%. S2. pH co-regulation: Adjust the pH of the cutting fluid to 7.5-8.5 to enhance the complexing efficiency through the following mechanisms: (1) High dissociation degree: The dissociation degree of amino carboxylic acid increases under alkaline conditions, and the charge distribution of the carboxylic acid group and the amino group is optimized, accelerating the coordination of metal ions. (2) Inhibition of oxidation: pH 7.5-8.5 can reduce the oxidation activity of the hydroxyl groups on the silicon surface and reduce the formation of local oxide layers. S3. Interface adsorption enhancement: Add 0.05-0.1 wt% of polyether-modified silicone. The hydrophobic segment (silicone) anchors to the silicon surface, and the hydrophilic segment (polyether) enriches the chelating agent to form a dense protective film, reducing the surface tension of the cutting fluid, solving the problem of uneven wetting of large-size silicon wafers, and increasing the local concentration of the chelating agent by more than 50%.
2. A method for reducing color difference in silicon wafer cutting using an amino carboxylic acid complexing agent according to claim 1, characterized in that: In S1, the chelating agent is selected from one or more of ethylenediaminetetraacetic acid, nitrilotriacetic acid, or diethylenetriaminepentaacetic acid. The amino carboxylic acid chelating agent forms a five-membered or six-membered ring chelate with metal ions through six coordination sites (four carboxylic acid oxygen atoms and two amino nitrogen atoms), and the stability constant logK of the stable water-soluble complex is >16.
3. A method for reducing color difference in silicon wafer cutting using an aminocarboxylic acid complexing agent according to claim 1, characterized in that: In S1, in the cutting fluid, complexing agents such as EDTA preferentially bind to high-valent metal ions such as Fe3+ and Ni 2 + to block their catalytic oxidation reactions. At the same time, they have a deep capture ability for low-concentration metal ions, and other ions present in the cutting fluid will not significantly interfere with the chelation of target metal ions because the stability constants of EDTA with these ions are relatively low.
4. A method for reducing color difference in silicon wafer cutting using an amino carboxylic acid complexing agent according to claim 1, characterized in that: In S3, the hydrophobic segment is mainly a polydimethylsiloxane segment that forms a strong interaction with the silicon surface through Si-O-Si bonds to achieve anchoring; the hydrophilic segment is mainly a polyether segment that binds to water molecules and chelating agent molecules in the cutting fluid through hydrogen bonds to form an enrichment layer.
5. A method for reducing color difference in silicon wafer cutting using an amino carboxylic acid complexing agent according to claim 1, characterized in that: In S3, the addition of polyether-modified silicone reduces the surface tension of the cutting fluid from 72 mN / m to 35-40 mN / m, significantly improving the wettability of large-size silicon wafers and reducing the "dry spot" phenomenon during cutting.
6. A method for reducing color difference in silicon wafer cutting using an amino carboxylic acid complexing agent according to claim 1, characterized in that: In S1, both the amino carboxylic acid chelating agent and the polyether-modified silicone exist in a water-soluble form and can be directly added to the existing cutting fluid without equipment modification. Uniform dispersion can be achieved through stirring and mixing at a rotation speed of 500-800 rpm for 30-60 minutes.