Phase Shift Mask Silicon Attenuation Layer
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Solution Overview
Problem
Phase shift masks used in semiconductor manufacturing experience deterioration due to repeated exposure to short-wavelength light, leading to changes in transmittance and phase difference, which affect mask performance and pattern resolution.
Innovation Solution
A mask blank with a phase shift film containing a transition metal and silicon, where a silicon layer is formed to attenuate exposure light, reducing the excitation of transition metals and thereby suppressing oxidation and alteration of the phase shift layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a phase shift mask using transition metal silicide-based material is used with short-wavelength exposure light, then pattern resolution is improved, but mask deterioration occurs due to changes in transmittance and phase difference
Solution Approach 1:
A silicon layer is formed on the substrate side of the phase shift layer before exposure to attenuate the incident light. This preliminary action reduces the light intensity reaching the transition metal, preventing oxidation and alteration that would otherwise occur during repeated exposures, thereby maintaining mask performance stability while enabling the use of short-wavelength light for high resolution
Solution Approach 2:
The silicon layer acts as an intermediary between the exposure light and the phase shift layer. It absorbs excess light energy and reduces the excitation of transition metals in the phase shift layer, preventing harmful oxidation reactions while allowing sufficient light transmission to maintain the phase shift effect and pattern resolution
2Productivity
If repeated exposure to short-wavelength light is performed, then productivity is improved, but mask deterioration accelerates due to accumulated light irradiation
Solution Approach 1:
The silicon layer is pre-formed on the substrate side to provide continuous protection during repeated exposures. This preliminary protective structure enables high-volume manufacturing by preventing accumulated light damage that would otherwise limit mask life, allowing sustained productivity without performance degradation
3Use of energy by moving object
If the phase shift layer is made thinner to reduce light absorption, then light transmission is improved, but phase shift effect is reduced
Solution Approach 1:
Instead of adjusting only the thickness of the phase shift layer, the solution adds a dimensional element by placing a silicon layer on the substrate side. This multi-layer structure allows independent optimization of light transmission (via silicon layer thickness) and phase shift effect (via phase shift layer properties), resolving the trade-off between transmission and phase shift effectiveness
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 provides a phase shift mask with improved light fastness and stability, maintaining high-quality pattern accuracy during semiconductor device manufacturing.
Implementation Method 1
a silicon layer, which is configured to attenuate exposure light with which the phase shift layer is irradiated
Implementation Method 2
has a predetermined phase difference... a phase of the light that has been transmitted through the semi-transparent portion is substantially reversed with respect to a phase of the light that has been transmitted through the light transparent portion
Data Source
AI summary
Provided is a mask blank including a phase shift film on a transparent substrate. This phase shift film includes a phase shift layer at least containing a transition metal and silicon, and a silicon layer, which is configured to attenuate exposure light with which the phase shift layer is irradiated, and the silicon layer is formed to be in contact with the substrate side of the phase shift layer. This mask blank is used in manufacturing a phase shift mask to which laser exposure light having a wavelength of 200 nm or less is applied.