Phase Shift Mask SRAF Printing Margin via Segmented Materials
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Solution Overview
Problem
Conventional photolithography techniques face challenges in improving the printing margin of sub-resolution assist features (SRAF) near main patterns in phase shift masks, leading to defects and reduced precision in micro pattern formation on semiconductor wafers.
Innovation Solution
A method for fabricating photolithography masks involves forming a phase shift material layer and a light blocking layer on a substrate, creating main and sub patterns using different materials, where the sub pattern is formed using an opaque MoSi layer and the main pattern using a partially transparent phase shift material, to enhance the printing margin by controlling light transmittance and phase shifting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If sub-resolution assist features (SRAF) are formed near main patterns in conventional phase shift masks, then the printing margin is insufficient, but forming them with conventional methods causes defects and reduces precision in micro pattern formation
Solution Approach 1:
The patent segments the mask structure into distinct main patterns and sub-resolution assist features (SRAF) with different material compositions. The SRAF regions use an opaque material layer while main patterns use a phase shift material layer, allowing independent optimization of each feature type's printing characteristics without mutual interference
Solution Approach 2:
The patent applies local quality by using different material properties in different regions of the mask. The SRAF regions are specifically designed with opaque materials to provide strong light blocking and improved printing margin, while main patterns use phase shift materials for their specific optical characteristics, creating locally optimized structures
2Manufacturing precision
If conventional photolithography techniques are used for phase shift masks, then the process is simpler, but the printing margin of SRAF is insufficient leading to reduced quality
Solution Approach 1:
The patent employs composite materials by combining an opaque material layer and a phase shift material layer in a multi-layer mask structure. This composite approach allows the SRAF regions to utilize the opaque material for enhanced printing margin while main patterns use the phase shift material, achieving superior overall pattern quality
Solution Approach 2:
The patent adds a dimensional aspect to the mask structure by introducing multiple material layers with different optical properties. This vertical layering creates additional control dimensions for light interaction, enabling independent optimization of SRAF and main pattern printing characteristics
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
This approach improves the printing margin of sub-resolution assist features, reducing defects and enhancing the resolution of main patterns, thereby improving the precision and quality of micro patterns on semiconductor wafers.
Implementation Method 1
forming a phase shift material layer on the substrate... the phase shift material layer may include molybdenum (Mo) and silicon (Si)... to enhance the printing margin by controlling light transmittance and phase shifting
Implementation Method 2
forming a light blocking layer on the phase shift material layer... The light blocking layer may include chrome (Cr)... sub pattern including an opaque material
Data Source
AI summary
A mask for photolithography and methods of manufacturing a mask and a semiconductor device are provided. The method of manufacturing a mask may comprise providing a substrate, forming a phase shift material layer on the substrate, forming a light blocking layer on the phase shift material layer, and forming a main pattern and a sub pattern on the substrate by patterning the phase shift material layer and the light blocking layer. The light blocking layer may be removed on the main pattern left on the light blocking layer remaining on the sub pattern. A semiconductor device may be manufactured using the mask to form a photoresist pattern on a semiconductor wafer. The pattern of the photoresist may be used to etch an object layer of the semiconductor wafer.