Exposure Lens Focus Compensation via Line-Width Curves
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Solution Overview
Problem
The low-temperature polysilicon process in semiconductor manufacturing faces challenges in focusing accuracy due to complex layer structures and parameters like self-flatness and deflection, which current exposure machines struggle to address effectively.
Innovation Solution
A focusing compensation method that involves measuring line-widths at multiple points along an axial direction under various focusing conditions, obtaining line-width curves, and using these curves to calculate compensation values for calibrating the exposure lens set to improve focusing accuracy, specifically considering self-flatness and deflection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional focusing measurement is used, then focusing stability is improved, but focusing accuracy is insufficient due to self-flatness and deflection
Solution Approach 1:
The patent replaces conventional mechanical focusing measurement with an optical measurement system that uses line-width curves obtained through photolithography exposure. By measuring line-widths at multiple focal planes and processing the data to generate compensation values, the system substitutes direct mechanical focus measurement with an optical-based indirect measurement that accounts for self-flatness and deflection effects.
Solution Approach 2:
The patent changes the measurement parameter from direct focus position to line-width values at different focal planes. By measuring line-widths at multiple focal planes (e.g., -40μm, -20μm, 0μm, +20μm, +40μm) and analyzing the resulting line-width curves, the system extracts focus compensation values that inherently account for self-flatness and deflection, thereby improving focusing accuracy without sacrificing stability.
2Reliability
If multiple measurement points are used, then focusing stability is improved, but measurement complexity increases
Solution Approach 1:
The patent divides the focusing measurement into multiple discrete focal planes (e.g., -40μm, -20μm, 0μm, +20μm, +40μm) and measures line-widths at each plane separately. This segmentation allows systematic data collection while maintaining manageable complexity through structured measurement procedures and automated data processing.
Solution Approach 2:
The patent creates a universal line-width curve analysis method that can be applied across different focal planes and measurement conditions. The same measurement and processing procedure is used regardless of the specific focal plane or object being measured, reducing operational complexity through standardization while maintaining high measurement reliability.
Data Source
AI summary
A focus compensation method and apparatus thereof are provided. The focusing compensation method includes steps of: (S11) providing an exposure lens set; (S12) providing an object, measuring line-widths of the object at points of line segments along an axial direction by different focusing conditions, to obtain measured values, and obtaining at least one line-width curve from the measured values; and (S13) calibrating a focusing operation of the exposure lens set according to the at least one line-width curve. Line-widths of a product are measured, and fed back to an exposure machine to calibrate the focusing operations of the exposure machine, thereby improving the focusing accuracy of the exposure machine.