Plasma Chamber Gas-In Sequencing for First-Wafer Etch Stability
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Solution Overview
Problem
Existing plasma processing methods fail to prevent process variation in the first wafer of a lot processing due to changes in chamber environment, such as surface temperature and deposit state, leading to reduced yield and accuracy.
Innovation Solution
A plasma processing method that includes a gas-in step before the heating step, using gases containing carbon, hydrogen, and chlorine elements, or their mixtures, to stabilize the chamber environment and reduce residual gas accumulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If plasma etching is used to attach Si-based and C-based deposits to the surface of the processing chamber before product processing, then particle generation is reduced and surface member protection is improved, but process variation occurs in the first wafer of lot processing due to changes in chamber environment
Solution Approach 1:
The patent applies preliminary action by introducing a gas-in step before the heating step to pre-establish the desired chamber environment. Gas is supplied to the processing chamber before heating to maintain appropriate atmospheric conditions, preventing the first-wafer effect by ensuring the chamber is already in the correct state before thermal changes occur.
Solution Approach 2:
The patent employs parameter changes by controlling the sequence and conditions of gas supply and heating. By adjusting the gas flow rate, gas composition, and heating rate as independent controllable parameters, the chamber environment is optimized to prevent both particle generation and process variation in the first wafer.
2Manufacturing precision
If the surface temperature of the processing chamber is kept constant, then processing reproducibility is improved, but additional control measures are required to maintain temperature consistency
Solution Approach 1:
The gas-in step performs preliminary action by establishing the desired gas atmosphere before heating begins. This pre-conditioning of the chamber environment reduces the complexity of temperature control by preventing thermal shock and ensuring uniform heating from the start, thereby improving processing reproducibility without requiring overly complex control systems.
3Manufacturing precision
If gas is supplied to the processing chamber before heating, then the chamber environment is stabilized and first-wafer process variation is reduced, but additional processing time is required
Solution Approach 1:
The patent applies partial action by supplying gas at a controlled flow rate for a specific duration before heating, rather than continuously throughout the entire process. This optimized gas-in step provides sufficient atmosphere stabilization to prevent first-wafer variation while minimizing the additional time required, achieving the balance between process consistency 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
The method reduces process variation in the first wafer of a lot by stabilizing the chamber environment, ensuring consistent etching accuracy and yield by maintaining a consistent radical balance and residual gas composition.
Implementation Method 1
a plasma processing method in which a sample is processed in a processing chamber by using plasma
Implementation Method 2
since radicals and ion energy generated by plasma are relatively large
Implementation Method 3
a measure has been carried out for starting product processing after the plasma etching is used to attach Si-based and C-based deposits to the surface of the processing chamber
Implementation Method 4
the reaction rate between the radicals and the processing chamber and an attachment coefficient of deposits differ depending on a surface temperature of the processing chamber, and thus it is necessary to keep the temperature in the processing chamber constant
Data Source
AI summary
A plasma processing method which can realize a reduction of process variation in the first one of lot processing includes a first step of supplying gas to a processing chamber and a second step of etching the sample by using plasma after the first step. The gas is a gas containing a carbon element and a hydrogen element, a gas containing a chlorine element, or a mixed gas containing all of the gases used in the second step.