Photomask Deformation Control Using Structured Light
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Solution Overview
Problem
In semiconductor lithography, mask deformation due to imperfect support platform movement causes distortion in pattern transfer, especially for feature sizes below 2 micrometers, leading to yield losses and requiring unreliable manual height adjustments.
Innovation Solution
A method and system using structured light projection and image analysis to quantify and correct mask deformation by comparing pre- and post-contact images, adjusting the support platform to maintain deformation within acceptable limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If manual height adjustment of the support platform is used, then the device complexity is reduced, but the manufacturing precision and reliability deteriorate due to reliance on operator experience
Solution Approach 1:
The patent replaces manual mechanical adjustment with an automated optical measurement and control system. Structured light projection and image capture devices automatically detect mask deformation, eliminating reliance on operator experience while maintaining device simplicity through software-based control
Solution Approach 2:
The system implements real-time feedback by capturing images of the mask surface, analyzing deformation through structured light patterns, and automatically adjusting the support platform height based on the detected deformation, creating a closed-loop control system that improves precision without proportionally increasing complexity
2Manufacturing precision
If structured light projection and image analysis are implemented, then the manufacturing precision improves through automated deformation detection, but the device complexity increases due to additional measurement and control systems
Solution Approach 1:
The patent introduces structured light patterns as an intermediary medium to indirectly measure mask deformation. Instead of directly measuring physical displacement, the system projects light patterns that deform with the mask surface, making subtle deformations visible and measurable through optical means
Solution Approach 2:
The system creates an optical copy of the mask surface deformation through structured light projection. The light patterns serve as a visual replica of the mask topography, allowing digital image processing to accurately capture and analyze deformation without physical contact with the mask
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
Enhances precision and reliability of photolithography by ensuring accurate pattern transfer, contributing to high-quality semiconductor device fabrication.
Implementation Method 1
checking whether there is a previously stored image-referred to as the first image-representing the structured light pattern formed on the mask before contact with the wafer
Implementation Method 2
the system captures a second image depicting the convex pattern formed after contact, allowing direct comparison with the first (reference) image
Data Source
AI summary
A method and system for adjusting mask deformation are provided to enhance the accuracy of lithography processes, which are critical to semiconductor manufacturing. The method involves projecting structured light onto a mask to capture a reference image before the mask makes contact with a wafer. If this reference image, referred to as the first image, is not already stored, the system captures it by projecting structured light onto the surface of the mask. A wafer is then placed on a support platform (the wafer stage) that is moved underneath the mask. The upward movement of the support platform brings the wafer into contact with the mask, forming a convex pattern that indicates mask deformation, referred to as the second image. A computing device analyzes the difference between the first and second images to guide adjustments of the support platform, ensuring that mask deformation remains within a predetermined range.