Semiconductor Substrate Weight Measurement for Optical Contamination Control
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Solution Overview
Problem
The challenge in semiconductor device manufacturing is accurately determining the degree of contamination in the optical system during the lithography process, which affects the exposure process, as premature or delayed cleaning can impact performance.
Innovation Solution
A method and apparatus that measure the weight difference of substrates before and after exposure to estimate contamination film thickness, using a witness sample to correlate weight changes with contamination levels, allowing for precise timing of optical system cleaning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cleaning of the optical system is started too late, then a suitable exposure process cannot be performed, but if cleaning is started too soon, then operation performance of the exposure apparatus decreases
Solution Approach 1:
The patent replaces direct measurement of optical system contamination with a substitute measurement method. A witness substrate is exposed to the same environment as the optical system, and its contamination level is measured indirectly through weight change or reflectivity change. This substitution allows accurate contamination assessment without directly interfering with the optical system's operation, enabling timely cleaning decisions that maintain both exposure suitability and operational productivity.
2Reliability
If cleaning is performed frequently to maintain exposure quality, then contamination is controlled, but operation performance and efficiency decrease
Solution Approach 1:
The patent implements a feedback mechanism where the contamination level of the optical system is continuously monitored through the witness substrate. The measured contamination level (via weight or reflectivity changes) feeds back to determine when cleaning is actually needed. This feedback loop prevents both premature cleaning (which wastes time) and delayed cleaning (which degrades quality), optimizing the cleaning schedule to match actual contamination accumulation.
3Measurement precision
If direct measurement of optical system contamination is attempted, then accurate contamination level is obtained, but measurement complexity and difficulty increase
Solution Approach 1:
The patent introduces a witness substrate as an intermediary object that indirectly measures the contamination level of the optical system. Instead of directly measuring the difficult-to-access optical surfaces, the witness substrate accumulates contamination in the same environment and can be easily removed and measured. This intermediary approach maintains measurement precision while dramatically reducing measurement complexity and operational disruption.
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
Enables accurate determination of contamination levels, ensuring timely and efficient cleaning of the optical system, thereby maintaining optimal exposure process performance.
Implementation Method 1
a weight measurement unit configured to measure a weight of the substrate
Implementation Method 2
performing an exposure process for the resist film; an exposure process for a resist is performed
Data Source
AI summary
According to one embodiment, a management method of a manufacturing apparatus of a semiconductor device, the method includes measuring a weight of a pre-exposure substrate including a semiconductor substrate and a resist film provided on the semiconductor substrate, performing an exposure process for the resist film, measuring a weight of a post-exposure substrate including the semiconductor substrate and the resist film after the exposure process is performed, and acquiring a weight difference between the weight of the pre-exposure substrate and the weight of the post-exposure substrate.