Lithography Mask Border Layout to Prevent Cold Welding
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Solution Overview
Problem
The issue with existing semiconductor lithography masks is that the light-absorbing border extending to the edges of the substrate can cause cold welding or sticking to the support pads, leading to wear and damage to the mask and mask stage, as well as potential contamination from dislodged particles.
Innovation Solution
The light-absorbing border is inset from the edges of the substrate to create peripheral regions where the support pads contact the substrate instead, reducing the likelihood of cold welding and minimizing contact area with the support pads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the light-absorbing border extends to all edges of the substrate, then the border effectively suppresses optical cross-talk and blocks light from sensors, but the mask sticks to the support pads causing cold welds and damage during unloading
Solution Approach 1:
The patent removes the light-absorbing layer from peripheral regions outside the border, extracting the problematic contact area between the border and support pads while preserving the border's optical functionality. This creates a separation between the functional border region and the contact region with support pads.
Solution Approach 2:
The patent applies different properties to different regions: the border region maintains light-absorbing material for optical suppression, while peripheral regions outside the border have removed light-absorbing material to prevent cold welding. This local differentiation resolves the contradiction between optical performance and handling reliability.
2Reliability
If the light-absorbing border extends to all edges of the substrate, then the border provides complete light blocking, but the mask experiences wear and contamination during handling and reduced operational lifespan
Solution Approach 1:
The patent extracts the light-absorbing layer from peripheral regions outside the border, creating a design where the border maintains complete light blocking functionality while the peripheral regions are free of light-absorbing material. This reduces contact area with support pads, minimizing wear and contamination, thereby extending mask operational lifespan.
3Device complexity
If the light-absorbing border extends to all edges of the substrate, then the border structure is simple and complete, but the contact area with support pads increases causing sticking and cold welds
Solution Approach 1:
The patent maintains a simple, complete border structure that extends to all edges for optical functionality, while locally modifying peripheral regions outside the border by removing light-absorbing material. This creates a dual-region structure where the border remains simple and effective, but peripheral contact areas are reduced to prevent cold welding.
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 design reduces wear and damage to the mask and mask stage, prevents contamination, and maintains effective optical cross-talk suppression and protection of sensitive components from light exposure.
Implementation Method 1
a light absorbing border surrounding the mask pattern, wherein the light absorbing border comprises a light absorbing layer disposed on the substrate that is absorbing for the light at the lithography wavelength
Data Source
AI summary
A mask for use in a semiconductor lithography process includes a substrate, a mask pattern disposed on the substrate, and a light absorbing border surrounding the mask pattern. The light absorbing border is inset from at least two edges of the substrate to define a peripheral region outside of the light absorbing border. In some designs, a first peripheral region extends from an outer perimeter of the light absorbing border to a first edge of the substrate, and a second peripheral region that extends from the outer perimeter of the light absorbing border to a second edge of the substrate, where the first edge of the substrate and the second edge of the substrate are on opposite sides of the mask pattern.