Bosch Etching Chamber Pressure Gradient for Smooth Silicon Walls
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Solution Overview
Problem
The Bosch deep silicon etching process faces challenges with high chamber pressure leading to accumulation of reaction products in silicon grooves, causing damage and a rough side wall profile due to inadequate discharge of reaction products.
Innovation Solution
Gradually decreasing the chamber pressure from a preset highest to a lowest pressure according to a specific rule during the etching process, ensuring each etching operation has a lower pressure than the previous one, allowing for effective discharge of reaction products and maintaining a smooth side wall profile.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If chamber pressure is kept at a relatively high level throughout the etching operation to generate more active radicals and improve etching rate, then etching rate is improved, but reaction products accumulate within the silicon groove and damage the side wall, causing a rough profile
Solution Approach 1:
The patent applies dynamics by making the chamber pressure variable rather than constant. The pressure is gradually decreased from a first preset value to a second preset value throughout the etching process. This dynamic adjustment allows the system to maintain high etching rate initially while progressively improving reaction product discharge to achieve smooth side wall profile, thus resolving the contradiction between productivity and manufacturing precision.
2Manufacturing precision
If chamber pressure is gradually decreased from highest to lowest pressure during etching operations to improve reaction product discharge, then side wall profile smoothness is improved, but etching rate may be reduced
Solution Approach 1:
The patent applies parameter changes by systematically varying the chamber pressure parameter throughout the etching process. The pressure transitions from a highest preset value to a lowest preset value in a controlled manner. This parameter change strategy enables the process to achieve both high etching rate (when pressure is high) and smooth side wall profile (when pressure is low), resolving the contradiction between manufacturing precision and productivity.
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 prevents side wall damage by ensuring reaction products are discharged, resulting in a smooth silicon groove profile and improved etching process quality.
Implementation Method 1
gradually decreasing the chamber pressure of a reaction chamber from a preset highest pressure to a preset lowest pressure according to a preset rule in the process of completing all cycles of the etching operation
Implementation Method 2
Dry Plasma Deep Silicon Etching Process gradually becomes one of the hottest processes in the MEMS processing field and TSV technique
Data Source
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Figure 2b~2c
Figure 2d~2f
AI summary
A substrate etching method comprises the following steps: a deposition operation, for depositing a polymer on a side wall of a silicon groove; an etching operation, for etching the side wall of the silicon groove; repeating the deposition operation and the etching operation at least twice. In the process of completing all cycles of the etching operation, the chamber pressure of a reaction chamber is decreased from a preset highest pressure to a preset lowest pressure according to a preset rule. The substrate etching method can avoid the problem of damaging the side wall, thereby making the side wall smooth.