TaNH Absorber Layer for EUV Mask Blank
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Solution Overview
Problem
The existing EUV mask blanks face challenges with the absorber layer, including increased insulating properties leading to charge-up during electron beam patterning, low film deposition rates, and high production costs due to the use of expensive gases like xenon, as well as difficulties in controlling the crystalline state and B content in TaBN and TaBNO films.
Innovation Solution
A reflective mask blank with an absorber layer composed of TaNH film, containing tantalum, nitrogen, and hydrogen, with specific compositional ratios and surface roughness, formed using a sputtering method with inert gases, which simplifies the process and reduces costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If TaBN or TaBNO film is used as absorber layer, then EUV light absorption is improved, but charge-up occurs during electron beam patterning due to increased insulating properties
Solution Approach 1:
The patent changes the compositional parameters of the absorber layer by incorporating hydrogen along with tantalum and nitrogen. This parameter change modifies the electrical properties of the film, reducing insulating characteristics while maintaining EUV absorption. The hydrogen content is controlled within specific ranges (0.1-50 at%, preferably 0.5-20 at%) to achieve optimal balance between conductivity and absorption.
Solution Approach 2:
The patent creates a composite absorber layer material comprising tantalum, nitrogen, and hydrogen. This composite approach combines the high EUV absorption of TaBN with the electrical conductivity benefits introduced by hydrogen, resulting in a material that exhibits both excellent EUV absorption and reduced charge-up tendency during electron beam patterning.
2Manufacturing precision
If TaBN film is formed by magnetron sputtering with B target, then film quality is improved, but film deposition rate becomes very low (less than 1/10 of Ta target rate)
Solution Approach 1:
The patent changes the sputtering process parameters by using a Ta target instead of a B target, and controlling the nitrogen and hydrogen gas environment during deposition. This parameter change allows the formation of TaBN and TaNH films with appropriate compositional ratios while achieving much higher deposition rates compared to using a B target.
Solution Approach 2:
The patent uses nitrogen and hydrogen gases as intermediaries to transfer boron atoms during the sputtering process. Instead of directly sputtering from a B target, boron is introduced through the gas phase, allowing efficient film formation with high deposition rates while maintaining film quality.
3Manufacturing precision
If TaBNO film is used to achieve amorphous crystalline state, then surface smoothness is improved, but control of B content becomes difficult and production cost increases
Solution Approach 1:
The patent changes the material composition by replacing some or all of the difficult-to-control boron with hydrogen. This parameter change simplifies the compositional control during film formation, as hydrogen can be more easily controlled through gas phase introduction during sputtering, while still achieving the desired amorphous crystalline state and surface smoothness.
4Reliability
If TaBNO film is used, then EUV absorption is improved, but production cost increases due to use of expensive gases like xenon
Solution Approach 1:
The patent replaces expensive gases (such as xenon) with cheaper, more readily available gases like nitrogen and hydrogen. This substitution maintains the ability to form high-quality absorber layers with excellent EUV absorption while significantly reducing production costs and making the process more economically viable for commercial manufacturing.
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 TaNH film absorber layer achieves an amorphous crystalline state, reducing stress and surface roughness, enhancing pattern precision and production efficiency while avoiding costly gases, thus improving the overall performance and cost-effectiveness of the EUV mask blank.
Implementation Method 1
formed using a sputtering method with inert gases
Implementation Method 2
an absorber layer for absorbing EUV light
Implementation Method 3
a reflective layer for reflecting EUV light
Data Source
AI summary
A reflective mask blank for EUV lithography is provided which has an absorber layer wherein stress and crystal structure can be easily controlled.A reflective mask blank for EUV lithography, which comprises a substrate, and at least a reflective layer for reflecting EUV light and an absorber layer for absorbing EUV light formed in this order on the substrate, wherein the absorber layer contains tantalum (Ta), nitrogen (N) and hydrogen (H); and in the absorber layer, the total content of Ta and N is from 50 to 99.9 at %, and the content of H is from 0.1 to 50 at %.