Reflective EUV Mask Peripheral Region Light Scattering
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Solution Overview
Problem
Extreme ultraviolet (EUV) masks absorb most EUV light due to high energy, preventing it from reaching semiconductor substrates, necessitating the development of reflective EUV masks that utilize reflected light effectively.
Innovation Solution
A reflective EUV mask with a light scattering crystalline portion in the peripheral region, a reflective layer with alternately stacked silicon and molybdenum layers, and an absorbing layer pattern including EUV and DUV absorbing layers, where the crystalline portion scatters incident light to decrease reflectivity and prevent interference with the exposing region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a reflective EUV mask is used to allow EUV light to reach the substrate, then the EUV light transmission is improved, but light interference from the peripheral region may occur
Solution Approach 1:
The mask substrate is differentiated into an exposing region with high reflectivity for EUV light transmission and a peripheral region with reduced reflectivity to minimize light interference. This local quality differentiation allows the mask to simultaneously achieve high EUV light transmission in the exposing region while suppressing harmful reflected light in the peripheral region.
Solution Approach 2:
The reflectivity parameter of the mask substrate is changed by forming a crystalline portion in the peripheral region. The crystalline structure modifies the optical properties of the substrate, reducing reflectivity in the peripheral region while maintaining high reflectivity in the exposing region, thereby controlling light interference.
2Stability of the object's composition
If the peripheral region has high reflectivity, then light scattering is reduced, but light interference with the exposing region increases
Solution Approach 1:
Different optical properties are assigned to different regions of the mask substrate. The exposing region maintains high reflectivity for stable light scattering control, while the peripheral region is modified with a crystalline portion to reduce reflectivity and eliminate light interference with the exposing region.
3Object-generated harmful factors
If an absorbing layer is added to reduce peripheral reflectivity, then light interference is decreased, but the mask structure complexity increases
Solution Approach 1:
Instead of adding complex absorbing layer structures, the invention changes the physical state of the mask substrate material in the peripheral region from amorphous to crystalline. This parameter change in material structure effectively reduces reflectivity and light interference while maintaining a relatively simple overall mask structure.
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 allows for accurate formation of photoresist patterns by reducing reflectivity in the peripheral region, ensuring that EUV light effectively reaches the semiconductor substrate, thereby improving the precision of pattern formation during the exposing process.
Implementation Method 1
a light scattering crystalline portion that scatters light incident to the peripheral region and that decreases reflectivity of the peripheral region
Implementation Method 2
a reflective EUV mask capable of using reflected EUV light
Implementation Method 3
most of the EUV light may be absorbed in an absorbing layer of an EUV mask
Data Source
AI summary
A reflective EUV mask and a method of manufacturing the same, the reflective EUV mask including a mask substrate having an exposing region and a peripheral region, the mask substrate including a light scattering crystalline portion that scatters light incident to the peripheral region and that decreases reflectivity of the peripheral region; a reflective layer on an upper surface of the mask substrate, the reflective layer having a first opening that exposes the crystalline portion; and an absorbing layer pattern on an upper surface of the reflective layer, the absorbing layer pattern having a second opening in fluidic communication with the first opening.