Substrate Etching Sequence for Uniform Wafer Edge Removal
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Solution Overview
Problem
Existing etching methods struggle to achieve uniform etching distribution across a substrate while maintaining a high etching rate, particularly in semiconductor manufacturing where film thickness variations at the peripheral edge and central regions lead to non-uniform etching.
Innovation Solution
A two-step etching process is employed, where the first step etches the peripheral edge more aggressively than the central region, followed by a second step that adjusts the etching rate through temperature control on the substrate's rear surface, ensuring uniform etching distribution by controlling the temperature gradient.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If etching liquid is supplied to etch a thin film with thick film thickness distribution at the peripheral edge, then the etching rate increases, but the etching amount distribution becomes non-uniform across the substrate
Solution Approach 1:
The etching process is divided into two distinct steps: a first etching step that selectively etches the peripheral edge region with higher etching amount, and a second etching step that etches the entire surface with controlled etching amount. This segmentation allows different regions of the substrate to receive tailored etching treatment, achieving both high overall etching rate and uniform etching amount distribution across the substrate surface.
Solution Approach 2:
The patent changes the etching parameters between two steps: in the first step, etching liquid is supplied to achieve greater etching amount at the peripheral edge; in the second step, etching is performed under conditions that produce smaller etching amount at the periphery compared to the center. By adjusting etching liquid supply conditions and substrate rotation parameters between steps, the process achieves uniform total etching amount distribution while maintaining high etching rate.
2Temperature
If temperature control liquid is supplied to the central portion of the rear surface, then the substrate temperature increases, but the temperature distribution becomes non-uniform
Solution Approach 1:
Temperature control liquid is supplied asymmetrically to the central portion of the rear surface rather than uniformly across the entire surface. This asymmetric supply creates a controlled temperature gradient where the central region receives heating while the peripheral regions remain relatively cooler, allowing the etching process to compensate for peripheral edge effects and achieve uniform etching amount distribution across the substrate.
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 achieves uniform etching across the substrate surface with a high etching rate, addressing non-uniformity issues and enhancing substrate processing efficiency.
Implementation Method 1
by supplying a temperature control liquid to a central portion of a rear surface of the substrate, a temperature of the substrate is higher than that in a case in which the temperature control liquid is not supplied
Implementation Method 2
the temperature of the first region of the front surface of the substrate becomes higher than the temperature of the second region as the temperature control liquid spreads toward the peripheral edge of the substrate while losing heat to the substrate
Data Source
AI summary
A substrate processing method includes: a first etching step of performing a first etching by supplying an etching liquid on a front surface of a substrate while rotating the substrate, wherein the first etching is performed under a condition in which a second etching amount of an etching target film in a second region on a peripheral edge of the front surface, is greater than a first etching amount of the etching target film in a first region on a center side of the front surface; and a second etching step of performing a second etching by supplying the etching liquid to the front surface of the substrate while rotating the substrate, wherein the second etching is performed under a condition in which the second etching amount of the etching target film in the second region of the front surface of the substrate is smaller than the first etching amount of the etching target film in the first region.