Maskless Exposure Apparatus Substrate Rotation for Stain Reduction
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Solution Overview
Problem
Existing maskless exposure technologies face challenges in preventing stains generated in the scanning direction on substrates with repeated patterns, as cumulative illuminations in the scanning direction are often uniform, leading to visibility issues and differences in critical dimensions (CDs) across patterns.
Innovation Solution
A maskless exposure apparatus and method that includes a light source, an optical head with a micro-mirror array, and a stage that rotates the substrate to adjust the angle of illumination, allowing for varied accumulations of light on the substrate, thereby minimizing stains by differing illuminations across patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the substrate is scanned in a straight line with uniform illumination, then the exposure process is simple and fast, but stains are generated in the scanning direction due to uniform cumulative illumination
Solution Approach 1:
The patent applies asymmetry by rotating the substrate at a specific angle (e.g., 45 degrees) relative to the scanning direction, breaking the symmetric uniform illumination pattern. This angular offset causes the beam spot array to illuminate different portions of repeated patterns differently, preventing uniform cumulative illumination and thereby eliminating stains in the scanning direction while maintaining high exposure speed
Solution Approach 2:
The patent implements local quality by varying the illumination intensity distribution across different regions of the substrate. Through substrate rotation, certain portions of repeated patterns receive different cumulative illuminations, creating local variations in exposure dosage that prevent uniform staining while maintaining overall process efficiency
2Manufacturing precision
If the substrate is rotated to vary illumination, then stains are minimized and pattern quality improves, but the alignment and positioning complexity increases
Solution Approach 1:
The patent changes the angular parameter of substrate orientation relative to the scanning direction. By rotating the substrate to a specific angle (such as 45 degrees), the system transforms the illumination pattern without requiring complex mechanical adjustments during exposure, thereby improving pattern quality while keeping the alignment mechanism relatively simple
Solution Approach 2:
The substrate rotation is performed as a preliminary action before the exposure process begins. The substrate is pre-positioned at the optimal angle, and then the exposure proceeds with standard scanning, eliminating the need for complex real-time alignment adjustments and reducing overall system complexity
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 effectively minimizes stains in the scanning direction by varying illuminations across patterns, ensuring uniform critical dimensions and reducing visibility of stains, thus enhancing the quality of pattern formation on substrates.
Implementation Method 1
The light modulator includes a micro-mirror array configured to reflect light from the light source and allow the light to be incident to the optical system
Implementation Method 2
the optical system radiates the reflected light from the light modulator to the first substrate by transforming the reflected light into a beam spot array including a plurality of rows and a plurality of columns
Implementation Method 3
a stage configured to support the first substrate and move the first substrate in a first direction, which is a scanning direction
Implementation Method 4
an optical head rotating unit configured to rotate the optical head
Data Source
AI summary
A maskless exposure apparatus includes a light source, an optical head including a light modulator and an optical system, and reflecting light from the light source to radiate the light to a substrate to be exposed, a stage supporting the substrate and moving the substrate in a scanning direction, where the substrate is rotated such that a reference line of the substrate is at a first angle with respect to the scanning direction, and an optical head rotating unit rotating the optical head. When patterns are formed on the substrate in a direction of a first row and an nth row that is substantially perpendicular to the reference line, the first angle is set such that illuminations accumulated, by a beam spot array, in first portions and second portions on the substrate respectively corresponding to the patterns of the first row and the patterns of the nth row vary.