Film Etching Flow Rate Calibration and Particle Removal
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Solution Overview
Problem
The existing film etching methods, such as the chemical oxide removal (COR) process, face challenges in maintaining consistent etching results across multiple workpieces due to particle adhesion on chamber walls and stages, leading to differences in etching outcomes.
Innovation Solution
A method involving a processing system with a first and second processing apparatus, where the flow rate controller is calibrated using a build-up method based on internal pressure increase, and a mixed gas of HF and NH3 is used to form a reaction product, which is then removed by heating, reducing particle adherence and ensuring consistent etching across workpieces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the flow rate controller is calibrated using the build-up method with a single gas, then the flow rate control accuracy is improved, but particle adhesion on chamber walls and stages causes etching result variation between sequentially processed workpieces
Solution Approach 1:
The patent applies preliminary action by performing a conditioning process before actual etching workpieces. This conditioning process involves supplying the first gas (HF) alone to the chamber to form particles on the wall surface and stage, then removing these particles through heating and exhaustion. This preliminary preparation ensures that subsequent etching processes start from a consistent baseline, eliminating the accumulation effect that causes variation between sequentially processed workpieces.
Solution Approach 2:
The patent extracts the harmful effect of particle adhesion by separating the calibration process from the actual etching process. The build-up method is used for calibration, but the harmful particle accumulation is removed through the conditioning process that involves heating the chamber to sublime and exhaust the reaction products, thereby extracting the source of etching variation before processing workpieces.
2Measurement precision
If particles constituting the first gas adhere to the wall surface and stage during calibration, then flow rate calibration is achieved, but etching results differ between initially and finally processed workpieces
Solution Approach 1:
The patent applies discarding and recovering by deliberately allowing particles to form during the conditioning process, then removing (discarding) these particles through heating and exhaustion before processing actual workpieces. This controlled discarding of particles resets the chamber state, ensuring that each batch of workpieces is processed under consistent conditions, thereby recovering etching uniformity across multiple batches.
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 reduces the difference in etching results between sequentially processed workpieces by calibrating the flow rate controller effectively and maintaining a stable etching environment, as demonstrated by experimental results showing minimal variation in etching amounts across samples.
Implementation Method 1
a first gas (HF) and a second gas (NH3) react with a film to form a reaction product
Implementation Method 2
the workpiece having the reaction product formed thereon is heated inside a second chamber. As the workpiece is heated, the reaction product is sublimated and exhausted
Data Source
AI summary
A method of etching a film of a workpiece, which includes: measuring a second flow rate of a first gas based on an increase rate of an internal pressure of a first chamber in a state in which a valve is closed and the first gas is supplied into the first chamber at a first flow rate adjusted by a flow rate controller, and calibrating the flow rate controller using the measured second flow rate; supplying a second gas into the first chamber; exhausting the first chamber; supplying a mixed gas of the first and second gases into the first chamber with the workpiece not mounted on a stage; forming a reaction product from the film by supplying the mixed gas into the first chamber with the workpiece mounted on the stage; and removing the reaction product by heating the workpiece with the workpiece accommodated in a second chamber.