Asymmetric Static Pressure Pad for Semiconductor Wafer Nanotopography Control
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Solution Overview
Problem
Conventional double-disc grinding methods for semiconductor wafers fail to minimize the 'middle ring' component of nanotopography, which affects the yield in device manufacturing processes.
Innovation Solution
A static pressure pad with an outer circumferential land pattern that is a concentric circle and an inner land pattern that is a non-concentric circle, asymmetrical to the wafer's rotation center, is used to support the wafer without contact, allowing for improved nanotopography during double-disc grinding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional static pressure pad with concentric circle land pattern is used, then the wafer can be supported stably during grinding, but the middle ring component of nanotopography cannot be minimized
Solution Approach 1:
The patent applies asymmetry by designing the inner land pattern to be non-concentric with respect to the wafer center, breaking the conventional symmetric concentric circle pattern. This asymmetric configuration specifically targets and minimizes the middle ring component of nanotopography, demonstrating how changing from symmetric to asymmetric design can resolve precision issues in grinding processes
2Manufacturing precision
If the inner land pattern is made non-concentric and asymmetrical, then the middle ring nanotopography is minimized, but the manufacturing complexity of the static pressure pad increases
Solution Approach 1:
The patent applies local quality by differentiating the land pattern design between inner and outer regions. The outer land pattern maintains a simple concentric circle configuration for ease of manufacture, while the inner land pattern uses a non-concentric asymmetric design to achieve the specific function of minimizing middle ring nanotopography. This localized differentiation allows complex functionality to be achieved without uniformly increasing manufacturing complexity across the entire component
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 configuration minimizes the 'middle ring' component of nanotopography, enhancing the yield in device manufacturing by ensuring more uniform grinding and reducing nanotopography-related issues.
Implementation Method 1
a static pressure pad which supports both sides of a raw wafer by a static pressure of a fluid supplied to the both sides of the raw wafer, without contact
Data Source
AI summary
The present invention is a static pressure pad for supporting both sides of a raw wafer without contact by a static pressure of a fluid supplied to the both sides of the raw wafer in a double-disc grinding machine for a semiconductor wafer, wherein in patterns of lands to be banks of surrounding pockets formed on a surface side of supporting the raw wafer of the static pressure pad, an outer circumferential land pattern required to support the raw wafer is a concentric circle with respect to a rotation center of the raw wafer, and a land pattern inside the outer circumferential land pattern is a non-concentric circle with respect to the rotation center of the raw wafer and asymmetrical with respect to all the straight lines which bisect the static pressure pad. With this static pressure pad, there is provided the double-disc grinding machine and a double-disc grinding method for the semiconductor wafer, which can minimize a “middle ring” of average components obtained by averaging a nanotopography of the wafers after the double-disc grinding.