Photomask Blank Light-Shielding Film for Defect Inspection Accuracy
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Solution Overview
Problem
Highly integrated semiconductor devices require finer circuit patterns, leading to challenges in photomask resolution and defect inspection accuracy due to light diffraction and increased particle generation from light-shielding films with high surface metal content.
Innovation Solution
A blank mask and photomask design featuring a light-transmitting substrate with a multilayer light-shielding film structure, where the second light-shielding layer includes transition metals, oxygen, or nitrogen, with controlled reflectance and hardness values to enhance defect inspection accuracy and reduce particle generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the surface metal content of the light-shielding film is increased to improve defect inspection accuracy, then the inspection accuracy improves, but particle generation increases
Solution Approach 1:
The light-shielding film is designed with a gradient metal content distribution, where the surface region has lower metal content to reduce particle generation, while the bulk maintains sufficient metal content for light shielding. This spatial variation in material composition allows simultaneous optimization of defect inspection accuracy and particle reduction.
Solution Approach 2:
The light-shielding film employs a composite structure combining metal layers with low-metal-content layers or metal oxide layers. This composite approach enables the film to maintain adequate light shielding performance while reducing surface metal content to minimize particle generation during processing.
2Device complexity
If the light-shielding film structure is simplified to reduce manufacturing complexity, then the manufacturing complexity decreases, but defect inspection accuracy deteriorates
Solution Approach 1:
The light-shielding film is segmented into multiple functional layers with distinct metal content levels. The surface region is designed with reduced metal content to minimize particle generation and improve defect inspection, while the bulk maintains sufficient metal content for light shielding. This segmentation allows independent optimization of each layer's properties.
Solution Approach 2:
The invention changes the metal content parameter spatially within the light-shielding film, creating a gradient or stepped structure where surface regions have lower metal content than bulk regions. This parameter variation enables simultaneous achievement of improved defect inspection accuracy and reduced particle generation without requiring completely complex multi-layer structures.
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
The solution improves defect inspection accuracy by reducing pseudo defect detection and particle formation, maintaining photomask resolution and durability, and effectively controlling optical and mechanical properties of the light-shielding film.
Implementation Method 1
A reflectance of a surface of the light-shielding film with respect to light having a wavelength of 193 nm is 20% or more and 40% or less
Implementation Method 2
a light-shielding portion, including the light-shielding film blocks the exposure light
Data Source
AI summary
A blank mask includes a light-transmitting substrate; and a light-shielding film, disposed on the light-transmitting substrate, including a first light-shielding layer and a second light-shielding layer disposed on the first light-shielding layer. The second light-shielding layer includes at least one of a transition metal, oxygen, or nitrogen, or any combination thereof. A reflectance of a surface of the light-shielding film with respect to light having a wavelength of 193 nm is 20% or more and 40% or less. A hardness value of the second light-shielding layer is 0.3 kPa or more and 0.55 kPa or less.