Synthetic Quartz Substrate Polishing with Impact-Absorbing Liquid
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Solution Overview
Problem
Conventional methods for producing polished substrates, particularly synthetic quartz glass, often result in surface defects due to uneven pressure and impact during lapping and polishing, leading to cracking and reduced yields, especially with thin substrates.
Innovation Solution
The method involves applying an impact-absorbing liquid to the substrate surface and rotating the lower polishing plate while the upper polishing plate comes into contact, reducing vertical force and minimizing damage by applying a resultant force with both vertical and horizontal components, thus protecting the substrate from defects like crow's tracks and macroscratches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If lapping is performed with a hard lapping plate to achieve high flatness, then surface flatness is improved, but substrate surface suffers impact and defects increase
Solution Approach 1:
A compliant layer is introduced between the lapping plate and the substrate surface. This layer acts as an intermediary that absorbs impact while transmitting the necessary mechanical force for lapping, thereby maintaining surface flatness improvement while reducing substrate damage and defects
Solution Approach 2:
The compliant layer is applied beforehand to the lapping plate surface, creating a cushioning effect that prevents direct impact between the hard lapping plate and the substrate. This prior cushioning protects the substrate from damage while enabling effective lapping
2Manufacturing precision
If polishing is performed with a hard polishing plate to achieve high flatness, then surface flatness is improved, but uneven pressure causes substrate surface defects
Solution Approach 1:
The compliant layer serves as an intermediary between the polishing plate and substrate, distributing pressure evenly across the substrate surface while maintaining the rigidity needed for achieving high flatness
Solution Approach 2:
The compliant layer changes the mechanical parameters of the polishing interface by providing compliance and pressure distribution, transforming the pressure distribution from uneven to uniform while maintaining polishing effectiveness
3Length of moving object
If thin substrates are used to meet application requirements, then device miniaturization is achieved, but substrate is more liable to break during processing
Solution Approach 1:
The compliant layer is applied beforehand to cushion the thin substrate from impact during lapping and polishing operations, preventing breakage while enabling processing of ultra-thin substrates that would otherwise be too fragile
Solution Approach 2:
The compliant layer acts as a protective intermediary that supports thin substrates during processing, distributing mechanical loads and preventing stress concentration that would cause breakage in ultra-thin materials
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
This approach effectively reduces surface damage and defectiveness, improving yields and productivity without the need for large-scale apparatus or precision polishing plates, utilizing existing facilities and maintaining high substrate quality.
Implementation Method 1
an impact-absorbing liquid is applied onto the surfaces of the substrate stocks, and the bringing of the upper polishing plate into contact with the surfaces is while they are coated with the impact-absorbing liquid
Implementation Method 2
rotating the lower polishing plate while the upper polishing plate comes into contact, reducing vertical force and minimizing damage by applying a resultant force with both vertical and horizontal components
Implementation Method 3
with supply of a polishing slurry to the surfaces of the substrate stocks to polish the substrate stocks
Data Source
Figure 1
AI summary
Proposed herein is a method for producing substrates, particularly those of synthetic quartz glass, while saving the substrate surface from killer defects without resorting to any large-scale apparatus and precision polishing plate, thereby reducing defectives and improving yields more than in production with conventional facilities. The method for producing substrates by polishing, includes steps of placing substrate stocks individually in work holes formed in a carrier on a lower polishing plate, bringing an upper polishing plate into contact with the surface of the substrate stocks, with the surface of the substrate stocks being coated with an impact-absorbing liquid and the lower polishing plate being rotated, and rotating the upper and lower polishing plates, with the surface of the substrate stocks being accompanied by a polishing slurry.