Phase Shift Mask for Fine Pattern Resolution
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Solution Overview
Problem
Current flat panel display fabrication techniques face challenges in forming fine patterns beyond the critical resolution of existing exposure systems, leading to defects and increased costs due to the need for high-resolution exposers or complex light sources, which also reduce depth of focus and introduce non-uniformity defects.
Innovation Solution
A mask with a partially light-absorbing phase shift layer, made of materials like molybdenum silicide, is used to impart a phase shift of 110 to 250 degrees to incident light, allowing for the formation of fine patterns with pitches smaller than the critical resolution of the exposer without requiring new exposure equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a high-resolution exposer with a single wavelength light source or increased NA value is used to form fine patterns beyond the critical resolution, then the critical resolution is reduced, but the depth of focus is also reduced causing non-uniformity defects
Solution Approach 1:
A phase shift layer is introduced as an intermediary element between the light source and the photoresist. This layer modifies the optical path by introducing a phase shift of 110 to 250 degrees to incident light, enabling fine pattern formation without requiring high-NA optics that would compromise depth of focus. The phase shift layer acts as a mediator that allows conventional exposers to achieve enhanced resolution.
Solution Approach 2:
The invention changes the optical parameters by introducing a phase shift layer with specific phase shift characteristics (110 to 250 degrees). This parameter change enables the exposer to form fine patterns at reduced critical resolution without increasing the NA value, thereby maintaining adequate depth of focus and avoiding non-uniformity defects.
2Ease of manufacture
If a complex wavelength light source is used in the exposer, then the equipment is simpler to maintain, but the critical resolution is limited
Solution Approach 1:
The phase shift layer serves as an intermediary that compensates for the limited critical resolution of complex wavelength light sources. By introducing a controlled phase shift, the layer enhances the effective resolution capability of the exposer without requiring replacement with more complex single-wavelength equipment.
Solution Approach 2:
The invention modifies the optical interaction parameters by adding a phase shift layer that imparts a phase shift of 110 to 250 degrees. This parameter modification allows complex wavelength light sources to achieve finer pattern formation capability without changing the light source itself, maintaining ease of manufacture while improving manufacturing precision.
3Manufacturing precision
If a mask is used to form fine patterns beyond the critical resolution of the exposer, then the pattern pitch is reduced, but many defects occur in the formed fine pattern
Solution Approach 1:
The invention changes the optical parameters by introducing a phase shift layer with specific phase shift characteristics (110 to 250 degrees). This parameter change improves the intensity contrast at the patterned region, enabling better definition of fine patterns and reducing defects compared to conventional masks without phase shift layers.
Solution Approach 2:
The mask structure is enhanced by adding a phase shift layer composed of light-absorbing material with specific optical properties (phase shift of 110 to 250 degrees). This composite structure combining the mask substrate and phase shift layer creates superior optical contrast, reducing defect frequency while achieving finer pattern pitch.
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 solution enables the formation of finer patterns with reduced defect ratios and improved display quality, allowing for lower manufacturing costs and easier production, while maintaining high aperture ratios, by using conventional equipment and processes.
Implementation Method 1
the at least partially light absorbing phase shift layer is configured to impart a phase shift of about 110 degrees to about 250 degrees to incident light
Implementation Method 2
an at least partially light absorbing phase shift layer formed on one side of the substrate
Data Source
AI summary
Provided is a photolithography mask capable of forming fine patterns beyond a critical resolution of an exposer without replacing or changing the exposer. The mask includes an at least partially light absorbing phase shift layer and uses a complex wavelength light source.