Sequential Stage Mixing for Resist Batch Strip Process
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Solution Overview
Problem
Current resist strip processes face challenges such as high defect rates, material compatibility issues, mist generation, and silicon nitride/silicon dioxide loss, particularly at higher temperatures, which affect the strip rate and selectivity in both batch and single substrate processing.
Innovation Solution
A resist removal system with a recirculation and bypass subsystem that adjusts temperature, concentration, and flow rates of treatment liquids using a staged mixing regime, incorporating primary, secondary, and tertiary stripping chemicals to optimize resist strip performance while minimizing silicon nitride and dioxide loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If higher process temperatures are used to increase strip rate, then resist strip performance is improved, but silicon nitride and silicon dioxide film loss increases
Solution Approach 1:
The treatment liquid is divided into multiple stages with different temperatures and compositions. The first stage uses higher temperature for rapid resist strip, while subsequent stages use lower temperatures to complete the strip process with minimal film loss, segmenting the strip process into temperature zones
Solution Approach 2:
The patent changes multiple parameters simultaneously including temperature, chemical composition, and flow rate across different stages. The treatment liquid composition is modified between stages to optimize both strip rate and selectivity, dynamically adjusting parameters to balance productivity and material preservation
2Loss of time
If higher process temperatures are used to reduce strip time, then economic feasibility is improved, but material compatibility concerns increase
Solution Approach 1:
The processing is segmented into multiple stages where only the first stage operates at high temperature for brief periods, while subsequent stages operate at lower temperatures. This temporal and spatial segmentation allows high temperature processing without sustained exposure that would cause material compatibility issues
Solution Approach 2:
The treatment liquid is pre-heated and pre-mixed to optimal conditions before contact with substrates, and the chamber is pre-conditioned. This preliminary preparation ensures that the high temperature process occurs efficiently when needed, while allowing cooling periods between cycles to protect materials
3Productivity
If higher process temperatures are used to achieve high strip rate, then mist generation increases
Solution Approach 1:
The treatment process is segmented into stages with decreasing temperatures. By reducing temperature in later stages, mist generation is significantly reduced while the cumulative strip effect across stages maintains high overall strip rate, breaking the direct link between continuous high temperature and continuous mist generation
4Productivity
If batch processing is used to process multiple substrates, then cost of ownership is reduced, but defect rate increases
Solution Approach 1:
Each substrate in the batch receives optimized local treatment through the multi-stage process. The treatment liquid flow and temperature distribution are designed to ensure uniform quality across all substrates in the batch, with each position receiving appropriate treatment conditions to minimize defects while maintaining batch processing efficiency
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 system achieves higher strip rates and selectivity with reduced material compatibility concerns and mist generation, maintaining performance at lower temperatures, thus addressing the limitations of existing processes.
Implementation Method 1
an inline heater
Implementation Method 2
a mixing device
Implementation Method 3
a sulfuric acid and hydrogen peroxide mixture (SPM)
Data Source
AI summary
Provided is a method and system for stripping a resist film on a plurality of substrates in a resist removal system comprising a processing chamber coupled to a recirculation system comprising a recycle sub-system and a bypass sub-system. The recycle sub-system includes a recycle line, an inline heater, a ratio monitor and control system, and recirculation injection device. The bypass sub-system comprises a treatment liquid supply line, a first injection line, a mixing device, and a second injection line. The treatment liquid comprises a primary stripping chemical, secondary stripping chemical, tertiary stripping chemical, and one or more reactive products. One or more of the temperatures, concentrations, and/or flow rates of the recirculated treatment liquid and/or injected stripping chemicals are adjusted to meet a target strip rate and selectivity for strip over etch of silicon nitride or silicon oxide.