Semiconductor Wafer Etcher Stage Charge Neutralization
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Solution Overview
Problem
In polysilicon etching processes, residual charges on the ceramic stage of a semiconductor wafer etcher cause positional shifts during wafer transfer, leading to carrying-out errors and reduced productivity.
Innovation Solution
Introducing process gases with higher electronegativity, such as oxygen gas, to form plasma and neutralize residual charges on the stage before wafer transfer, ensuring accurate positioning and reducing transfer errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If inert gas is introduced to neutralize charges on the wafer back surface, then charge neutralization is achieved, but residual charges remain on the ceramic stage causing carrying-out errors
Solution Approach 1:
The patent applies preliminary action by introducing process gas to form plasma and neutralize residual charges on the ceramic stage before the wafer is transferred. This pre-neutralization step ensures that when the wafer is later pushed up by lift pins for transfer, no residual charges remain on the stage to cause positional shifts or carrying-out errors.
2Ease of operation
If lift pins push up the wafer for transfer, then wafer delivery is enabled, but positional shifts occur due to residual charges on the stage
Solution Approach 1:
The patent performs charge neutralization on the ceramic stage before wafer transfer by introducing process gas to form plasma. This preliminary action eliminates residual charges that would otherwise cause positional shifts when lift pins push the wafer up for transfer to the transfer arm.
3Productivity
If plasma processing is performed continuously, then productivity is maintained, but residual charges accumulate on the stage
Solution Approach 1:
The patent maintains continuous plasma processing for high productivity while simultaneously introducing process gas to form plasma that continuously neutralizes residual charges on the ceramic stage. This continuous dual action ensures charges are eliminated as they accumulate, preventing carrying-out errors without interrupting production flow.
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 eliminates residual charges, preventing positional shifts and transfer errors, thereby improving the productivity and reducing damage to semiconductor wafers during plasma processing.
Implementation Method 1
a wafer is adsorbed and held by an electrostatic chuck system
Implementation Method 2
forming plasma in the vacuum vessel in a state where the semiconductor wafer is adsorbed and held by the stage
Implementation Method 3
charges are neutralized by inert gas ionized by a UV light irradiation apparatus
Data Source
AI summary
A manufacturing method of a semiconductor device includes the steps of: (a) placing a semiconductor wafer over a stage provided in a chamber, the pressure in the inside of which is reduced by vacuum pumping; and (b) after the step (a), forming plasma in the chamber in a state where the semiconductor wafer is adsorbed and held by the stage, so that desired etching processing is performed on the semiconductor wafer. Herein, before the step (a), O2 gas, negative gas having an electronegativity higher than that of nitrogen gas, is introduced into the chamber to form O2 plasma in the chamber, thereby allowing the charges remaining over the stage to be eliminated.