Diamond Wire Saw Slicing with Aqueous Polyphosphate Solution
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Solution Overview
Problem
The introduction of diamond wire saws in silicon wafer fabrication eliminates the need for abrasive slurry, but poses challenges in preventing abraded silicon contamination and requires a more environmentally friendly solution for waste treatment compared to traditional ethylene glycol-based systems.
Innovation Solution
An aqueous polyphosphate solution is applied during the slicing process with diamond wire saws to keep abraded silicon particles in suspension, preventing build-up on wafers and equipment, and offering improved environmental handling over ethylene glycol solutions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If diamond wire saws are used without abrasive slurry, then the cutting process becomes more environmentally friendly, but abraded silicon particles contaminate the photovoltaic substrates and build up on the machinery
Solution Approach 1:
An aqueous polyphosphate solution is introduced as an intermediary substance between the diamond wire saw and the silicon ingot. This solution serves multiple functions: it facilitates the cutting process, suspends abraded silicon particles to prevent contamination of substrates and machinery, and enables environmentally friendly disposal. The polyphosphate solution acts as a mediator that resolves the contradiction between eliminating abrasive slurry and preventing particle contamination.
Solution Approach 2:
The invention changes the chemical parameters of the cutting fluid by using aqueous polyphosphate solution instead of traditional abrasive slurry or ethylene glycol-based solutions. This parameter change transforms the cutting environment to one that is environmentally friendly while simultaneously providing particle suspension capabilities through the specific chemical properties of polyphosphates, which prevent particle deposition on surfaces.
2Object-generated harmful factors
If traditional ethylene glycol-based slurry is used, then abraded particles are controlled, but the solution is environmentally problematic for waste treatment and disposal
Solution Approach 1:
The invention fundamentally changes the chemical composition parameter of the cutting fluid from ethylene glycol-based slurry to aqueous polyphosphate solution. This parameter change maintains the necessary functional properties for particle control during cutting while transforming the environmental profile from problematic to benign, allowing for easier and more environmentally friendly waste treatment and disposal.
Solution Approach 2:
The aqueous polyphosphate solution can be used as a disposable, easily replaceable fluid that does not require complex recycling or treatment processes. Unlike ethylene glycol-based solutions that require sophisticated waste management, the polyphosphate solution can be disposed of through simpler, more environmentally friendly processes, effectively treating it as a consumable that minimizes environmental impact.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The polyphosphate solution effectively suspends abraded particles, reducing contamination and facilitating easier cleaning, while being more environmentally friendly and eliminating the need for abrasive materials in the cutting fluid.
Implementation Method 1
The polyphosphate solution used in the present invention is effective at keeping small particles and debris from the cutting operation in suspension, thereby reducing the build-up of abraded particles on both the wafers and the equipment used in the slicing process.
Data Source
AI summary
A method for slicing a workpiece into wafers in which a polyphosphate solution is applied to the workpiece during the slicing process. The method comprises the steps of positioning the workpiece, such as a silicon ingot, in the vicinity of a wire saw that can cut through the workpiece without the use of an abrasive slurry; causing an aqueous polyphosphate solution to contact the workpiece; and causing the wire saw to cut into the workpiece while the polyphosphate solution is in contact with the workpiece. After the workpiece has been cut into wafers, the polyphosphate solution is rinsed off of the wafers. Preferably, the wire saw used in this method is a diamond wire saw.