DMD Exposure Module Alignment for Diffraction-Corrected Pattern Projection
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Solution Overview
Problem
Existing exposure apparatuses using digital mirror devices (DMDs) face issues with image formation degradation due to wavelength-dependent diffraction effects and diffraction grating actions, leading to pattern quality deterioration during fine pattern projection.
Innovation Solution
The exposure apparatus includes a spatial light modulation element with micro mirrors that are switched between ON and OFF states, an illumination unit, and a projection unit, along with a control unit that adjusts optical members and micro mirrors based on correction information to correct image formation light flux errors and pattern line width changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a digital mirror device with micro mirrors is used to project patterns, then manufacturing costs and time are reduced by eliminating mask substrates, but image formation quality degrades due to diffraction grating effects
Solution Approach 1:
The patent applies parameter changes by adjusting the inclination angle of micro mirrors dynamically based on the pattern being projected. Different inclination angles are selected to optimize the balance between diffraction grating effects and image formation quality for different pattern types, thereby resolving the contradiction between ease of manufacture and manufacturing precision
Solution Approach 2:
The patent implements dynamics by making the micro mirror inclination angles adjustable and variable rather than fixed. The control unit dynamically changes the inclination angles based on the specific pattern requirements, allowing the system to adapt to different manufacturing precision needs while maintaining the cost advantages of DMD technology
2Device complexity
If micro mirrors are arranged in a matrix at constant pitch to form a diffraction grating, then the device structure is simplified, but pattern projection accuracy deteriorates due to wavelength-dependent diffraction
Solution Approach 1:
The patent changes the inclination angle parameter of micro mirrors based on the wavelength of illumination light and the specific pattern requirements. This dynamic parameter adjustment compensates for wavelength-dependent diffraction effects while maintaining the simple matrix structure of the micro mirrors
Solution Approach 2:
The patent employs feedback mechanisms where the control unit receives information about the projected pattern and adjusts the micro mirror inclination angles accordingly. This feedback loop ensures that pattern projection accuracy is maintained despite the simplified device structure and wavelength-dependent diffraction effects
3Productivity
If illumination light is irradiated onto the spatial light modulation element, then pattern projection is enabled, but telecentric errors and light amount variations occur affecting image quality
Solution Approach 1:
The patent adjusts the inclination angle parameter of micro mirrors to compensate for telecentric errors and light amount variations. By optimizing the inclination angles, the system maintains both pattern projection capability and image quality, resolving the contradiction between productivity and manufacturing precision
Solution Approach 2:
The patent implements dynamic adjustment of micro mirror inclination angles during pattern projection to correct optical errors in real-time. This dynamic approach allows the system to maintain high image quality while preserving the productivity benefits of rapid pattern projection using the spatial light modulation element
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 enhances pattern quality by correcting telecentric errors and light amount variations, ensuring precise and accurate projection of fine patterns onto substrates.
Implementation Method 1
a projection unit that causes reflected light from micro mirrors in the ON state in the spatial light modulation element to be incident on a substrate as an image formation light flux
Implementation Method 2
the micro mirrors also include an action as an optical diffraction grating
Implementation Method 3
depending on the wavelength of the illumination light to the DMD and the action (a generation direction of diffraction light and a state of intensity distribution) of the diffraction grating of the DMD
Data Source
AI summary
An exposure apparatus includes: a plurality of modules that include a spatial light modulation element including a plurality of micro mirrors driven to be switched between an ON state and an OFF state based on drawing data, an illumination unit that irradiates the spatial light modulation element with illumination light, and a projection unit that causes reflected light from micro mirrors in the ON state in the spatial light modulation element to be incident on a substrate as an image formation light flux; a control unit that stores correction information which corrects a state of the image formation light flux for each of the modules; and an adjustment mechanism that adjusts a position or an angle of an optical member in the illumination unit or the projection unit or an angle of the spatial light modulation element for each of the modules based on the correction information.