Gas Flow Module for Wafer Particle Contamination Control
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Solution Overview
Problem
The challenge in the semiconductor industry is maintaining a clean environment for wafer inspection tools, particularly in controlling particle contamination, as existing designs are obstructed by optical benches and wafer stages, which can introduce particles and fail to meet stringent ISO class 1 cleanliness standards.
Innovation Solution
A system that includes a mechanical stage for moving objects along a predetermined path, a structural support element for the optical module, and a gas flow module that directs clean gas over a coverage area larger than the object, ensuring clean gas flow above at least 50-90% of the object's path, using a filter and pump to maintain cleanliness and prevent contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a controlled minienvironment with laminar gas flow is used to maintain cleanliness, then particle contamination is reduced, but the optical bench obstructs the gas flow to the wafer
Solution Approach 1:
The gas flow system is segmented into multiple independent gas flow modules positioned at different locations (above and below the optical bench) to deliver clean gas to the wafer from multiple directions, overcoming the obstruction caused by the optical bench
Solution Approach 2:
Clean gas acts as an intermediary substance that flows through and around the optical bench structure, maintaining a particle-free environment for the wafer despite the physical obstruction
2Productivity
If the wafer is placed on an X-Y stage for scanning, then inspection coverage is improved, but the stage produces particles during movement
Solution Approach 1:
The harmful particle-generating functions are extracted from the X-Y stage system and relocated to dedicated particle-free zones, separating the scanning function from the contamination source
Solution Approach 2:
Clean gas flow is used as a pneumatic barrier to suppress and redirect particles generated by the X-Y stage, preventing them from reaching the wafer surface during scanning operations
3Object-affected harmful factors
If a coverage area bigger than the object is used, then clean gas coverage is improved, but the gas flow module size increases
Solution Approach 1:
The gas flow coverage is extended to three dimensions by positioning gas flow modules both above and below the optical bench, allowing a compact module size to achieve large coverage area through spatial distribution
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 effectively reduces particle contamination by ensuring clean gas flow over the wafer, meeting stringent cleanliness standards and preventing contamination from optical and stage sources, as validated by computer flow design simulations and experiments.
Implementation Method 1
a constant laminar gas flow of 0.35 m/s is forced to go vertically downwards
Implementation Method 2
The gas is previously filtered by a high performance ULPA filter
Data Source
AI summary
A system that may include a mechanical stage that is arranged to move an object along a predetermined path in relation to an optical module during an illumination of the object by the optical module; a structural support element that is arranged to support at least a part of the optical module; a gas flow module that is arranged to direct clean gas towards the object through gas flow module openings that define a coverage area that is (a) bigger than the object and (b) is positioned directly above at least a majority of the object when the object is positioned anywhere along the predetermined path.