Wafer Wet Etching Condition Superposition for Surface Shape Control
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Solution Overview
Problem
Existing substrate processing methods face challenges in precisely controlling the surface shape of wafers during etching, particularly at the central portion, due to centrifugal forces causing uneven distribution of the etching liquid.
Innovation Solution
The method involves acquiring etching amount deviation distributions under multiple etching conditions, optimizing these distributions through superimposition to determine optimal etching conditions, which are then used to control the surface shape by adjusting the time ratio of etching liquid supply.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single etching condition is used, then the etching process is simple and fast, but the surface shape cannot be precisely controlled
Solution Approach 1:
The patent segments the etching process into multiple discrete etching conditions, each producing a specific etching amount deviation distribution. By dividing the continuous etching parameter space into discrete segments (different etching conditions with different rotation speeds, liquid supply speeds, etc.), the system can selectively combine these segments to achieve precise surface shape control while maintaining manageable process complexity.
Solution Approach 2:
The patent merges multiple etching index distributions (obtained from different etching conditions) through superimposition to create a composite distribution that achieves the target surface shape. This combining approach allows the system to leverage the strengths of multiple individual etching conditions and achieve precision that would be impossible with any single condition alone.
2Manufacturing precision
If multiple etching conditions are tested to find optimal conditions, then surface shape control improves, but processing time increases
Solution Approach 1:
The patent performs preliminary actions by pre-acquiring etching index distributions for multiple different etching conditions before actual production. These pre-characterized distributions are stored and can be rapidly superimposed during operation, eliminating the need for time-consuming real-time experimentation and optimization during manufacturing.
Solution Approach 2:
The patent creates simplified copies of the complex etching process by representing each etching condition as an etching index distribution (a mathematical model). These copies can be rapidly manipulated through superimposition without requiring actual physical experimentation, significantly reducing the time needed for condition optimization.
3Manufacturing precision
If etching liquid is supplied uniformly across the wafer, then the process is simple, but centrifugal force causes uneven distribution at the central portion
Solution Approach 1:
The patent applies local quality by acquiring etching index distributions under multiple different local conditions (different rotation speeds, different liquid supply speeds, different supply positions). Each distribution captures the local etching characteristics under specific conditions, allowing the system to select and combine the appropriate local characteristics to achieve uniform overall etching while accounting for centrifugal force effects at different wafer regions.
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 allows for precise control of the surface shape of wafers after etching, ensuring uniformity and improving flatness, thereby addressing the challenge of uneven etching at the central portion.
Implementation Method 1
a substrate processing method including a grinding process of grinding a surface of a substrate, a measuring process of measuring a thickness of the ground substrate, a condition determining process of determining processing conditions for a wet etching to be performed on the substrate based on the measured thickness of the substrate, and an etching process of performing the wet etching by supplying a processing liquid to the ground substrate under the determined processing conditions
Data Source
AI summary
A substrate processing method includes determining an optimal etching condition; and etching a surface of an etching target of a substrate by supplying an etching liquid to the surface based on the optimal etching condition. The determining of the optimal etching condition includes acquiring etching index distributions in a radial direction of the etching target when the surface of the etching target is etched under multiple different etching conditions; optimizing, by using an optimization method, a combination of the etching index distributions used in superimposition and a superimposing number of the etching index distributions by superimposing the etching index distributions respectively corresponding to the multiple etching conditions such that a shape of the surface of the etching target becomes a target shape; and determining the optimal etching condition by integrating the etching conditions corresponding to the optimized combination.