Two-Beam Interference Laser System for Semiconductor Exposure
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Solution Overview
Problem
The miniaturization and increased integration of semiconductor integrated circuits require higher resolutions in semiconductor exposure apparatuses, which is hindered by chromatic aberration in gas laser devices due to their wide natural oscillation width, necessitating the reduction of spectral line width and the use of two-beam interference apparatuses for forming line-and-space patterns.
Innovation Solution
A two-beam interference apparatus and system that includes a wafer stage, a beam splitter, and an optical system to guide split laser light beams onto a wafer, causing interference to form high-contrast interference patterns, with a laser device having an amplifier unit with elongated discharge region and a beam tuning unit to adjust beam profiles and coherence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If gas laser devices are used as exposure light sources, then high power output is achieved, but chromatic aberration occurs due to wide spectral line width
Solution Approach 1:
The laser device is divided into a seed laser unit and an amplifier unit. The seed laser generates light with narrow spectral width to avoid chromatic aberration, while the amplifier provides power amplification without significantly broadening the spectrum, thus resolving the contradiction between power output and spectral width.
Solution Approach 2:
A seed laser acts as an intermediary between the amplifier and the exposure system. It produces coherent light with controlled spectral properties that the amplifier then boosts in power, serving as a mediator that preserves spectral narrowness while enabling high power output.
2Manufacturing precision
If line narrowing elements are added to narrow spectral width, then chromatic aberration is reduced, but device complexity increases
Solution Approach 1:
The patent replaces mechanical line narrowing elements (such as etalons or gratings) with a seed laser-based approach. The seed laser inherently generates narrow-spectral-width light through its oscillation characteristics, eliminating the need for additional mechanical narrowing components and reducing device complexity.
3Manufacturing precision
If two-beam interference apparatus is used to form line-and-space patterns, then resolution is improved, but system complexity increases
Solution Approach 1:
The laser device with elongated discharge region serves multiple functions: it provides high power output, maintains narrow spectral width, and generates appropriate beam profiles for interference patterning. This multi-functionality reduces the need for additional specialized components, thereby reducing overall system complexity while maintaining high resolution 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
The system achieves high spatial coherence and uniform energy distribution for forming precise line-and-space patterns on the wafer, improving resolution and reducing chromatic aberration effects.
Implementation Method 1
the second laser light and the third laser light are caused to interfere with each other on the wafer
Data Source
AI summary
A two-beam interference apparatus may include a wafer stage on which a wafer may be set, a beam splitter to split first laser light into second and third laser light having a beam intensity distribution elongated in a first direction within a surface of the wafer, and an optical system to guide the second and third laser light onto the wafer. The wafer is irradiated with the second laser light from a second direction perpendicular to the first direction, and the third laser light from a third direction perpendicular to the first direction but different from the second direction, to thereby cause interference of the second and third laser light on the wafer. This apparatus increases the accuracy of the two-beam interference exposure.