SLM Pattern Printing with Phase-Shifted Complex Amplitudes
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Solution Overview
Problem
Current techniques for manufacturing integrated circuits without conventional masks or reticles face limitations, such as low scanning speeds and inability to scan multiple dimensions, and struggle with creating fine patterns with high acuity and accurate feature boundary placement.
Innovation Solution
A method utilizing a spatial light modulator (SLM) with an array of modulator elements, providing partially coherent illumination with a coherence length greater than half the pitch of the modulators, and using negative complex amplitudes to enhance pattern precision and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional mask writers use beams of electrons or laser beams for forming the pattern on a workpiece, then the pattern can be formed, but the scanning speed is limited to relatively low speeds and only a single dimension can be scanned
Solution Approach 1:
The patent replaces the mechanical beam scanning system with an optical field-based system using spatial light modulators. Instead of physically scanning electron or laser beams across the workpiece in a single dimension, the invention uses multiple SLMs to simultaneously modulate light fields that expose the entire pattern area in parallel, achieving high-speed multi-dimensional patterning without mechanical scanning limitations
Solution Approach 2:
The invention transitions from single-dimensional sequential scanning to multi-dimensional parallel processing by introducing additional spatial dimensions through arrays of spatial light modulators. The system uses multiple SLMs arranged in a two-dimensional array, each controlling a specific region of the pattern, enabling simultaneous exposure across multiple dimensions rather than sequential single-dimensional scanning
2Manufacturing precision
If SLMs with analog modulation are used for precision printing, then patterns can be formed, but the feature edge acuity and accuracy of placement are insufficient for high precision requirements
Solution Approach 1:
The patent changes the modulation parameter from analog intensity control to digital binary control (0 or 1) combined with phase manipulation. By using binary control with phase shifts, the system achieves higher edge acuity through constructive and destructive interference patterns, creating sharper feature edges compared to analog modulation's gradual intensity transitions
Solution Approach 2:
The invention utilizes phase transitions in the light field by controlling the phase of light waves reflected from the SLM elements. By introducing phase shifts of 0 or π (180 degrees), the system creates constructive interference for desired pattern features and destructive interference for spaces, achieving high-contrast, high-acuity edge definition that surpasses analog intensity modulation
3Measurement precision
If the coherence length is smaller than or equal to half the pitch of the modulating elements, then the illumination is more coherent, but the pattern precision and feature boundary accuracy deteriorate
Solution Approach 1:
The patent applies local quality control by using binary modulation (0 or 1) at each SLM element location rather than uniform analog modulation. This local binary control combined with phase management creates precise local interference patterns that improve feature boundary accuracy while maintaining appropriate coherence characteristics for the overall pattern formation
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
Enables the creation of fine patterns with high feature edge acuity and accurate placement of feature boundaries, improving the precision and efficiency of pattern formation on semiconductor wafers without the need for reticles or masks.
Implementation Method 1
collimating radiation from said radiation source to create partially coherent illumination of said SLM with a coherence length that is larger than half the pitch of the modulating elements in the SLM
Implementation Method 2
creating a negative complex amplitude with at least one modulator element
Data Source
AI summary
The present invention includes a method to print patterns with improved edge acuity. The method for printing fine patterns comprises the actions of: providing an SLM and providing a pixel layout pattern with different categories of modulating elements, the categories differing in the phase of the complex amplitude.