Wafer Lifting Pin Vacuum-Gas Cleaning for Precise Chuck Mounting
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Solution Overview
Problem
In semiconductor manufacturing, improper mounting of wafers on chucks can lead to issues with mask overlay and heating homogeneity due to tighter design rules and narrower process margins, potentially causing damage to wafers during loading and unloading.
Innovation Solution
A wafer holding apparatus with a chuck and lifting pins, where the chuck has concentrically arranged chucking holes for vacuum retention and lifting pins with inner and outer gas passages for cleaning and vacuum suction, ensures secure and particle-free wafer placement on the chuck.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional wafer mounting methods are used, then the mounting process is simple, but mask overlay and heating homogeneity are impacted due to improper mounting
Solution Approach 1:
The chuck is divided into multiple functional zones with concentrically arranged chucking holes that create distinct vacuum retention zones. This segmentation allows different regions of the wafer to be held with appropriate force, improving mounting precision without requiring a completely complex new apparatus.
Solution Approach 2:
The system performs preliminary cleaning of the chuck surface using gas passages before wafer mounting to remove particles. This preliminary action ensures proper mounting conditions are established before the wafer is placed, preventing improper mounting issues without adding complex real-time adjustment mechanisms.
2Productivity
If tighter design rules are applied for highly integrated semiconductor devices, then device integration increases, but process margin becomes narrower making wafer handling more critical
Solution Approach 1:
The system incorporates sensors that detect wafer positioning and provides feedback to adjust mounting parameters. This feedback mechanism ensures that even with tighter design rules, the wafer is mounted with sufficient precision to maintain process margin and reliability.
Solution Approach 2:
The system dynamically adjusts vacuum pressure and gas flow parameters to optimize wafer mounting conditions. By changing these parameters based on detected conditions, the system maintains reliability despite narrower process margins associated with higher integration.
3Object-affected harmful factors
If conventional cleaning methods are used, then the cleaning process is simple, but particle contamination remains on the chuck affecting wafer placement
Solution Approach 1:
The system uses gas passages that deliver controlled gas flows to blow particles off the chuck surface. This pneumatic cleaning method effectively removes particle contamination without requiring complex mechanical cleaning mechanisms, balancing cleaning effectiveness with system simplicity.
Solution Approach 2:
The cleaning operation is performed as a preliminary step before wafer mounting, ensuring the chuck surface is free of particles. This preliminary cleaning action prevents contamination issues without requiring complex in-situ cleaning mechanisms during the mounting process.
4Productivity
If rapid wafer loading and unloading is performed, then productivity increases, but risk of wafer damage increases
Solution Approach 1:
The lifting pins are designed to move dynamically, allowing rapid insertion and retraction. The pins can quickly engage to support the wafer during transfer and just as quickly retract to release it, enabling fast loading/unloading while maintaining wafer support during critical moments to prevent damage.
Solution Approach 2:
The lifting pins are positioned to engage the wafer before any potential damage can occur during transfer. This beforehand support acts as cushioning, protecting the wafer from impacts or drops even during rapid processing cycles, thus maintaining integrity while enabling high throughput.
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 solution improves wafer handling by maintaining wafer integrity and reducing particle contamination, enhancing photolithographic overlay control and temperature uniformity during processing.
Implementation Method 1
holding the wafer on the lifting pin using a negative pressure source in gaseous communication with an inner gas passage of the lifting pin
Implementation Method 2
introducing a gas to a region between the wafer and the wafer chuck through an outer gas passage of the lifting pin
Data Source
AI summary
A method includes transferring a wafer to a position over a wafer chuck; lifting a lifting pin through the wafer chuck to a first position to support the wafer; holding the wafer on the lifting pin using a negative pressure source in gaseous communication with an inner gas passage of the lifting pin; introducing a gas to a region between the wafer and the wafer chuck through an outer gas passage of the lifting pin, wherein in a top view of the lifting pin, the inner gas passage has a circular profile, while the outer gas passage has a ring-shape profile; and lowering the lifting to dispose the wafer over the wafer chuck.