Photomask Local Quality for Intersecting Slit Features
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Solution Overview
Problem
Existing methods struggle to form via features and slit features intersecting or joining each other with precise dimensions in a single step due to high light intensity requirements, leading to inaccuracies and increased widths of slit features.
Innovation Solution
A photomask design with specific light-transmitting and light-shielding portions is used, where a second light-shielding portion is strategically placed at the intersection points of light-transmitting portions to reduce light intensity and facilitate faithful reproduction of intersecting or joining slit features.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If exposure light is radiated through a conventional photomask to form via features and intersecting slit features in the same step, then productivity is improved, but manufacturing precision deteriorates due to increased light intensity causing widened slit features
Solution Approach 1:
The photomask applies local quality by creating regions with different light transmission properties. Specifically, the translucent substrate has varying degrees of light transmission in different areas, allowing the mask to transmit higher light intensity in regions forming via features while transmitting lower light intensity in regions forming slit features. This spatial variation in optical properties enables simultaneous formation of different feature types with appropriate exposure doses, resolving the contradiction between productivity and manufacturing precision.
Solution Approach 2:
The invention changes the optical parameters of the photomask substrate itself, rather than using uniform transmission. By controlling the light transmission characteristics of the translucent substrate at different locations, the system can deliver different effective exposure doses to different regions of the resist film. This parameter change allows the same exposure step to produce both via features and slit features with correct dimensions, preventing the widening problem while maintaining high productivity.
2Productivity
If light intensity is increased to form via features successfully, then productivity is improved, but manufacturing precision of slit features worsens due to excessive light causing feature widening
Solution Approach 1:
The photomask implements local quality by having different light transmission characteristics in different spatial regions. The translucent substrate is designed to transmit higher light intensity where via features are to be formed, ensuring successful via formation. Simultaneously, the substrate transmits lower light intensity where slit features are to be formed, preventing excessive exposure that would cause widening. This localized optimization of light transmission resolves the contradiction between via feature formation success and slit feature width control.
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 allows for the accurate formation of slit features that intersect or join with precise dimensions, reducing the formation of rounded corners and maintaining the intended shape, thus improving reproducibility and pattern fidelity.
Implementation Method 1
a photomask including, on a translucent substrate, first light-transmitting portions having a property of transmitting the exposure light and having the same shapes as the plurality of slit features in terms of plan arrangement, first light-shielding portions having a property of shielding the exposure light
Implementation Method 2
developing the resist film radiated with the exposure light to form a resist pattern having a plurality of slit features formed to intersect or join each other
Data Source
AI summary
A photomask includes, on a translucent substrate, three or more first light-shielding portions each in insular shape having a property of shielding exposure light and spaced equidistantly, a second light-shielding portion having a property of shielding the exposure light and formed to connect the adjacent first light-shielding portions, and first light-transmitting portions each in slit shape having a property of transmitting the exposure light and formed to be surrounded with the first and second light-shielding portions. The second light-shielding portion is formed to contain a point located equidistantly from the three or more first light-shielding portions.