Photomask Assembly Buffer Layer Removal
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Solution Overview
Problem
The existing photomask assembly manufacturing process faces issues with the hard mask layer becoming unstable and delaminating due to undercutting of the buffer layer, leading to potential damage to the pellicle layer and other components.
Innovation Solution
The solution involves forming a photomask assembly without an intervening buffer layer by depositing a capping layer directly on the substrate where the buffer layer is removed, and then forming a hard mask layer on top. This reduces the likelihood of delamination and enhances adhesion between layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a buffer layer is used between the substrate and capping layer, then adhesion is improved, but the hard mask layer becomes unstable and delaminates due to undercutting
Solution Approach 1:
The patent removes the buffer layer from the structure entirely, depositing the capping layer directly onto the substrate. This extraction of the problematic buffer layer eliminates the undercutting issue that causes hard mask layer delamination, while the direct contact between capping layer and substrate provides sufficient adhesion without requiring the buffer layer
Solution Approach 2:
Instead of adding a buffer layer to improve adhesion (conventional approach), the patent inverts the approach by removing the buffer layer and achieving adhesion through direct deposition of the capping layer onto the substrate, which prevents the undercutting problem
2Ease of manufacture
If a buffer layer is present, then manufacturing process is simplified, but delamination occurs leading to damage of pellicle layer
Solution Approach 1:
The buffer layer is extracted/removed from the manufacturing process. By depositing the capping layer directly onto the substrate without an intervening buffer layer, the patent eliminates the source of delamination that ultimately damages the pellicle layer, while the process remains straightforward
3Reliability
If buffer layer is removed entirely, then delamination is prevented, but adhesion between layers must be maintained
Solution Approach 1:
The problematic buffer layer is removed, and the capping layer is deposited directly onto the substrate. This direct interface provides sufficient adhesion strength while completely preventing the delamination issue that would occur with a buffer layer present
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 approach reduces the likelihood of damage to the pellicle layer and other components, increases the yield of the exposure process, and stabilizes the hard mask layer, preventing delamination.
Implementation Method 1
depositing a capping layer directly on the substrate where the buffer layer is removed
Data Source
AI summary
A portion of a buffer layer on a backside of a substrate of a photomask assembly may be removed prior to formation of one or more capping layers on the backside of the substrate. The one or more capping layers may be formed directly on the backside of the substrate where the buffer layer is removed from the substrate, and a hard mask layer may be formed directly on the one or more capping layers. The one or more capping layers may include a low-stress material to promote adhesion between the one or more capping layers and the substrate, and to reduce and/or minimize peeling and delamination of the capping layer(s) from the substrate. This may reduce the likelihood of damage to the pellicle layer and/or other components of the photomask assembly and/or may increase the yield of an exposure process in which the photomask assembly is used.