Point of Use Solvent Mixing for Wafer Edge Bead Removal
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Solution Overview
Problem
Conventional edge bead removal (EBR) processes using single solvents often result in non-ideal film removal at the wafer edges, leading to hump formation, which affects subsequent photolithography processes and is costly to optimize due to solvent sharing across multiple processes.
Innovation Solution
A method and system for point-of-use solvent mixing, using a dispense nozzle assembly to combine two solvents at a controlled mixing ratio, effectively eliminating edge hump formation by dynamically adjusting the solvent composition during the EBR process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single solvent is used in conventional EBR processes, then the process is simple and solvents can be shared across multiple processes, but edge hump formation occurs and film removal is non-ideal
Solution Approach 1:
The solvent system is segmented into multiple components (first solvent and second solvent) that are mixed in controlled ratios. The first solvent (e.g., PGMEA) provides baseline dissolving power while the second solvent (e.g., GBL, EB, or DMF) enhances edge bead removal capability. This segmentation allows optimization of film removal without compromising other process functions.
Solution Approach 2:
The invention changes the chemical composition parameters of the solvent system by introducing variable mixing ratios of two solvents. By adjusting the proportion of the second solvent (e.g., 1-50% by volume), the dissolving power and volatility characteristics are tuned to achieve ideal edge bead removal while maintaining compatibility with spin coating and other processes.
2Manufacturing precision
If solvent composition is optimized for EBR, then edge hump formation is reduced, but other processes using the same solvent may be impacted
Solution Approach 1:
The solvent mixture is designed with local quality differentiation where the first solvent (majority component) maintains compatibility with spin coating and other processes, while the second solvent (minority component, 1-50%) provides localized enhancement for edge bead removal. This allows the solvent system to perform different functions at different locations on the wafer during the EBR process.
Solution Approach 2:
The solvent composition is made dynamic through controllable mixing ratios that can be adjusted based on specific process requirements. The system can adapt the proportion of the second solvent depending on the film type, thickness, and desired EBR aggressiveness, while maintaining overall versatility across different semiconductor manufacturing processes.
3Productivity
If conventional EBR processes are used, then the process flow is simple, but hump formation affects subsequent photolithography and causes yield loss
Solution Approach 1:
The solvent mixing is performed preliminarily in a mixing chamber before dispensing onto the wafer. This preliminary mixing ensures that the optimal solvent composition is prepared in advance, allowing immediate and consistent edge bead removal that prevents hump formation before it can affect subsequent photolithography processes, thereby protecting yield.
Solution Approach 2:
The mixing chamber and dispense nozzle assembly serve as intermediary components that translate the requirement for high yield (through effective EBR) into a controlled solvent delivery system. This intermediary system bridges the gap between simple process flow and the need for optimized solvent composition, enabling yield improvement without requiring complete process redesign.
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 edge hump height from over 400 nm to less than 20 nm, improving the fidelity of subsequent processes and reducing yield loss issues by allowing fine-tuning of solvent composition specifically for EBR without impacting other processes.
Implementation Method 1
mixing a first fluid with a second fluid at a mixing ratio using a dispense nozzle assembly resulting in a fluid mixture
Implementation Method 2
while rotating the wafer, dispensing the fluid mixture from the dispense nozzle assembly over an edge portion of the wafer
Data Source
AI summary
A method of processing a wafer that includes: positioning the wafer within a processing chamber, the wafer including a film deposited over a surface of the wafer; rotating the wafer within the processing chamber; mixing a first fluid with a second fluid at a mixing ratio using a dispense nozzle assembly resulting in a fluid mixture; and while rotating the wafer, dispensing the fluid mixture from the dispense nozzle assembly over an edge portion of the wafer to remove a portion of the film on the edge portion of the wafer.