Spatial Light Modulator Phase Inversion for Intensity Distribution Accuracy
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Solution Overview
Problem
Spatial light modulators with arrays of micromirrors face errors in intensity distribution due to systematic and random errors, leading to deviations from target intensity distributions on substrates, and light passing through gap regions between micromirrors further complicates the issue.
Innovation Solution
A method of driving spatial light modulators by setting optical elements in alternating phases, where one region is set to pass light with the same phase as incident light or a phase difference of 180°, and the other region is inverted, to alleviate systematic errors and light passing through gaps, using a control system to manage these states for overlay exposure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a spatial light modulator uses an array of micromirrors to generate variable patterns, then manufacturing efficiency is improved and mask preparation costs are reduced, but systematic errors in micromirror height cause intensity distribution to deviate from target distribution
Solution Approach 1:
The patent applies inversion by creating a complementary spatial light modulator where the phase states of corresponding micromirrors are inverted relative to the first SLM. Specifically, micromirrors in the first state of the first SLM correspond to micromirrors in the second state of the second SLM, and vice versa. This inversion causes systematic errors to have opposite signs, allowing them to cancel out when patterns from both SLMs are superimposed, thereby resolving the intensity distribution deviation while maintaining high manufacturing efficiency
Solution Approach 2:
The patent merges the output patterns from two separate spatial light modulators by superimposing them on the same substrate. The exposure apparatus is configured to simultaneously or sequentially project patterns from both SLMs onto the substrate, combining their effects to achieve the desired intensity distribution that compensates for individual SLM errors while maintaining high productivity
2Device complexity
If light passes through gap regions between micromirrors, then the spatial light modulator can be simpler in structure, but the intensity distribution deviates from the target distribution
Solution Approach 1:
The patent converts the harmful effect of light passing through gap regions into a beneficial effect by using the complementary SLM configuration. The systematic errors including gap light effects in the first SLM are compensated by the inverted errors in the second SLM, transforming the previously harmful gap light interference into a canceling effect that improves intensity distribution accuracy while maintaining simple SLM structure
3Ease of manufacture
If systematic errors are present in micromirror height, then the spatial light modulator can be manufactured more easily, but the intensity distribution deviates from target distribution
Solution Approach 1:
The patent applies inversion by manufacturing a complementary spatial light modulator where systematic errors in micromirror height are deliberately inverted. The second SLM is configured such that micromirrors corresponding to the first state in the first SLM are in the second state, and vice versa. This creates opposite systematic errors that cancel out during pattern superimposition, allowing easier manufacturing of individual SLMs while achieving high intensity distribution accuracy through the paired configuration
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 reduces systematic errors and light interference from gaps, resulting in improved accuracy and consistency of intensity distributions on substrates, enhancing the precision of pattern formation in device manufacturing.
Implementation Method 1
spatial light modulators of a type having an array of many micromirrors a height of a reflective surface of each of which is controllable, in order to control a phase distribution of incident light
Implementation Method 2
spatial light modulators (SLM) having an array of many microscopic mirrors an inclination angle of each of which is variable
Data Source
AI summary
A mirror array device, and related exposure apparatus and manufacturing method, for driving a spatial light modulator that includes: setting, in an array of mirror elements, mirror elements in a first state for turning incident light into reflected light with the same phase as that of the incident light or with a phase different by a first phase from that of the incident light and mirror elements in a second state for turning incident light into reflected light with a phase different approximately 180° from the first phase to an arrangement with a first phase distribution; and setting, in the array of mirror elements, the first mirror elements and the second mirror elements to an arrangement with a second phase distribution which is an inversion of the first phase distribution.