Wafer Grinding Sequence for Nanotopography and Warpage Control
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Solution Overview
Problem
Existing wafer manufacturing methods face challenges in achieving excellent nanotopography quality due to residual undulation and warpage caused by resin thickness differences and the use of fixed-abrasive-grain wire saws, which result in low productivity and deteriorated surface conditions.
Innovation Solution
A manufacturing method involving multiple resin-application grinding steps followed by surface-grinding, where a curing material is applied and removed sequentially on both surfaces of the wafer, with additional surface-grinding steps to enhance nanotopography quality without compromising productivity, using a wire-saw machine for slicing and grinding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If resin application grinding is performed only once on one surface, then productivity is maintained, but nanotopography quality is insufficient due to residual undulation
Solution Approach 1:
The invention divides the resin application grinding process into multiple sequential steps: first resin application grinding on one surface, then second resin application grinding on the opposite surface, and finally third resin application grinding on the first surface again. This segmentation allows each step to address specific undulation issues, achieving excellent nanotopography quality (PV value of 0.1 μm or less) while maintaining reasonable productivity through efficient process design
Solution Approach 2:
The invention applies resin to the opposite surface before the first surface grinding is completed, and performs the third resin application on the first surface before final polishing. These preliminary actions prevent undulation from propagating to subsequent processing steps, ensuring that the wafer surface is already optimized for nanotopography before the final polishing stage
2Productivity
If fixed-abrasive-grain wire saw is used for slicing, then slicing efficiency is improved, but process damage increases causing large undulation on wafer surface
Solution Approach 1:
The invention accepts the undulation caused by fixed-abrasive-grain wire saw slicing as an inevitable intermediate state, then uses resin application grinding to convert this harmful effect into a beneficial process feature. The resin fills and flattens the undulations created by efficient slicing, transforming the slicing damage into an opportunity for precise surface control in subsequent grinding steps
Solution Approach 2:
The invention introduces resin as an intermediary material between the slicing and grinding processes. The resin is applied to the wafer surface, cured to form a flat reference surface, and then used as a mediator during grinding to protect the wafer while achieving precise flatness, effectively decoupling the high-productivity slicing from the high-precision surface finishing requirements
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 method effectively improves nanotopography quality by reducing undulation and warpage, maintaining high productivity, and minimizing process damage, even with large undulations and larger wafer diameters.
Implementation Method 1
a curable resin is applied on a second surface of a wafer and the curable resin is flatly shaped and cured
Implementation Method 2
a first surface of the wafer is ground while the flat surface of the curable resin is held
Data Source
AI summary
A manufacturing method of a wafer includes a first and a second resin-application grinding step, and a third surface-grinding step. The first step includes: a first formation step of forming a first coating layer; a first surface-grinding step of placing the wafer so that the first coating layer contacts a reference surface of a table and surface-grinding a first surface of the wafer; and a first removal step of removing the first coating layer. The second step includes: a second formation step of forming a second coating layer; a second surface-grinding step of placing the wafer so that the second coating layer contacts the reference surface and surface-grinding the second surface; and a second removal step of removing the second coating layer. In the third step, the wafer is placed so that the last surface-ground surface contacts the reference surface and a surface opposite the contacted surface is surface-ground.