Reflective EUV Mask Peripheral Grating for Light Interference
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Reflective EUV masks face challenges in reducing reflectivity in peripheral regions, leading to interference issues with deep ultraviolet light, which affects pattern formation accuracy in semiconductor manufacturing.
Innovation Solution
Incorporating a grating pattern in the peripheral region of the absorbing layer pattern, formed by alternately stacking molybdenum and silicon layers, to scatter and reduce the reflectivity of extreme ultraviolet and deep ultraviolet light, thereby minimizing interference and maintaining critical dimension accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a reflective EUV mask uses a peripheral region corresponding to an edge region of the absorbing layer pattern, then the mask area is increased, but light interference occurs due to high reflectivity in the peripheral region
Solution Approach 1:
The patent applies local quality by differentiating the treatment of the peripheral region from the exposing region. The grating pattern is specifically formed only in the peripheral region to reduce reflectivity, while the exposing region maintains its original absorbing layer structure for proper pattern formation. This localized modification allows the peripheral region to serve as a light-absorbing area rather than a reflective one, eliminating interference without affecting the functional exposing area.
Solution Approach 2:
The patent converts the harmful high reflectivity of the peripheral region into a beneficial light-absorbing characteristic. By forming a grating pattern that reduces reflectivity, the previously harmful reflected light is transformed into absorbed light, allowing the peripheral region to contribute to pattern formation rather than cause interference. This converts a defect (high reflectivity) into a useful function (light absorption for pattern definition).
2Ease of manufacture
If the absorbing layer pattern is formed without a grating pattern, then the manufacturing process is simpler, but reflectivity remains high causing overlay errors and image deterioration
Solution Approach 1:
The patent segments the absorbing layer pattern into two distinct functional regions: the exposing region with the original absorbing layer structure for pattern formation, and the peripheral region with a grating pattern for light absorption. This segmentation allows each region to be optimized for its specific function while being manufactured as an integrated structure, balancing manufacturing simplicity with pattern formation accuracy.
3Object-affected harmful factors
If a grating pattern is formed in the peripheral region to decrease reflectivity, then light interference is reduced, but the device structure becomes more complex
Solution Approach 1:
The patent merges the grating pattern formation with the existing absorbing layer pattern manufacturing process. The grating pattern is formed as an integral part of the absorbing layer structure in the peripheral region, combining multiple functions (light absorption, structural integrity, pattern definition) into a single unified structure rather than adding separate components.
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 grating pattern effectively decreases reflectivity in the peripheral region, preventing light interference and ensuring accurate pattern formation with reduced overlay errors and image deterioration, maintaining desired critical dimensions in semiconductor substrates.
Implementation Method 1
The absorbing layer pattern may include a grating pattern formed in the peripheral region to decrease a reflectivity of light incident to the peripheral region
Implementation Method 2
The reflecting layer may include a molybdenum layer and a silicon layer alternately stacked
Data Source
AI summary
A reflective extreme ultraviolet (EUV) mask includes a mask substrate, a reflecting layer on an upper surface of the mask substrate, and an absorbing layer pattern on an upper surface of the reflecting layer, the absorbing layer pattern having an exposing region and a peripheral region, and the absorbing layer pattern including a grating pattern in the peripheral region to reduce reflectivity of light incident on the peripheral region.