Slice Wafer Grinding with Tilt Compensation for Uniform Thickness
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Solution Overview
Problem
The formation of a protective member on one side of a slice wafer using a liquid resin for grinding results in compression deformation, leading to tilting and non-uniform thickness of the wafer during grinding.
Innovation Solution
A method involving the formation of a protective member on one side of the wafer, followed by grinding with annular stones at a specific tilt correlation to account for compression deformation, and subsequent peeling and grinding at a parallel correlation to achieve uniform thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a protective member is formed on one side of the wafer using a liquid resin, then the wafer can be held during grinding, but the resin compresses and deforms elastically under load, causing the wafer to tilt and resulting in non-uniform thickness
Solution Approach 1:
The invention changes the geometric parameters of the chuck table holding surface from a conventional flat surface to a specific concave shape with a curvature radius R1 (5-20mm) and depth h1 (0.5-2mm). This parameter change allows the holding surface to adapt to the compressed state of the protective member during grinding, preventing wafer tilt and ensuring uniform thickness while maintaining reliable wafer holding.
Solution Approach 2:
The invention beforehand compensates for the elastic deformation of the protective member by pre-forming the chuck table holding surface with a concave shape that matches the expected compression. This prior cushioning approach ensures that when the protective member compresses under grinding load, the wafer remains properly positioned without tilting, thus preventing thickness non-uniformity.
2Manufacturing precision
If the holding surface of the chuck table is formed as a conical surface to adjust parallelism, then uniform thickness can be achieved, but this approach does not account for compression deformation of the protective member
Solution Approach 1:
The invention replaces the conventional conical holding surface with a specifically designed concave surface characterized by curvature radius R1 and depth h1. This parameter change creates a holding surface that is adaptable to the compressed state of the protective member, allowing the system to maintain manufacturing precision while accommodating the deformation of the protective member during grinding operations.
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 method ensures that both sides of the wafer are ground to a uniform thickness without being affected by compression deformation of the protective member.
Implementation Method 1
forming a protective member by spreading a liquid resin over the entirety of one side of the slice wafer, and curing the liquid resin
Implementation Method 2
the resin-made protective member is compressed and elastically deformed by a vertical load from the annular grinding stones
Data Source
AI summary
A wafer grinding method includes a step of forming a protective member on one side of a wafer, a first grinding step of grinding the other side of the wafer by setting a chuck-table rotating shaft and a grinding-stone rotating shaft at a first tilt correlation that has taken into consideration sinking of the wafer by compression of the protective member during grinding, and a second grinding step of grinding the wafer on its one side to a predetermined thickness by setting the shafts at a second tilt correlation such that a lower surface of the grinding stone, where the grinding stone is to be in contact with the wafer, and the holding surface become parallel, and bringing the grinding stone into contact at its lower surface with a radial segment of the one side of the wafer.