Exposure Apparatus Alignment Using Dual Magnification Scopes
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional wafer alignment methods require a long alignment time due to the need to measure positions of two low-magnification alignment marks, which hampers throughput in semiconductor exposure processes.
Innovation Solution
An exposure method and apparatus that utilize a first scope for detecting a low-magnification mark, a second scope with higher magnification for detecting a different mark, and subsequent correction value calculations to align and expose the substrate efficiently, reducing the need for extensive low-magnification measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If two low-magnification alignment marks are measured for prealignment, then alignment accuracy is improved, but alignment time increases
Solution Approach 1:
The patent divides the alignment process into two distinct stages: prealignment using low-magnification scope and main alignment using high-magnification scope. By segmenting the measurement tasks according to magnification levels and purposes, the system avoids redundant low-magnification measurements while maintaining comprehensive alignment accuracy.
Solution Approach 2:
The patent performs prealignment as a preliminary action using low-magnification scope to quickly establish rough alignment, followed by main alignment using high-magnification scope for precise measurement. This preliminary action reduces the burden on subsequent high-magnification measurements, shortening total alignment time while preserving accuracy.
2Measurement precision
If multiple sample shots are measured for global alignment, then alignment accuracy is improved, but productivity decreases
Solution Approach 1:
The patent applies different measurement qualities to different alignment stages: low-magnification measurement for prealignment and high-magnification measurement for main alignment. This local differentiation of measurement quality allows efficient prealignment with fewer measurements while reserving high-precision measurements for critical main alignment steps.
Solution Approach 2:
The patent changes the magnification parameter between prealignment and main alignment stages. By switching from low-magnification to high-magnification scope, the system optimizes the balance between measurement speed and precision for each stage, improving overall productivity without sacrificing alignment accuracy.
Data Source
AI summary
An exposure method comprises: a first detection step of detecting a position of a first mark by a first scope; a second detection step of detecting a position of a second mark by a second scope having a magnification higher than the first scope; a first calculation step of calculating a first correction value based on the detection results obtained in the first and second detection steps; a third detection step of detecting a position of a third mark by the second scope after the substrate is aligned based on the first correction value calculated in the first calculation step; a second calculation step of calculating a second correction value based on the detection results obtained in the second and third detection steps; and an exposure step of exposing the substrate after the substrate is aligned based on the second correction value calculated in the second calculation step.