Quartz Prism Line Narrowing Module for Stable Laser Direction
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Solution Overview
Problem
Existing semiconductor exposure apparatuses face challenges in maintaining resolution due to chromatic aberrations caused by wide spectral linewidths in KrF and ArF excimer laser apparatuses, necessitating the use of line narrowing modules, while current materials like calcium fluoride are expensive and unstable, and continuous operation leads to deviations in laser light direction.
Innovation Solution
Employing a line narrowing module with an enlarging optical system using quartz crystal and synthetic quartz prisms, where the quartz crystal prism's optic axis is perpendicular to the light incident plane and positioned closest to the grating, and synthetic quartz prism is disposed near the grating, along with a rotating mechanism to adjust wavelength, to minimize material usage and temperature-induced deviations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If calcium fluoride is used in the enlarging optical system, then the spectral linewidth can be narrowed, but the cost increases and material stability decreases
Solution Approach 1:
The patent changes the material parameter from calcium fluoride to quartz crystal, altering the optical properties while maintaining the line-narrowing function. This substitution resolves the contradiction by providing a more stable and cost-effective material that still achieves the required spectral linewidth narrowing through its specific optical characteristics.
Solution Approach 2:
The patent employs a composite optical system combining quartz crystal and synthetic quartz prisms. This composite approach allows the system to leverage the advantages of different materials - quartz crystal for its piezoelectric properties and optical characteristics, and synthetic quartz for structural stability - thereby achieving both narrow spectral linewidth and high material reliability.
2Productivity
If the enlarging optical system operates continuously, then productivity increases, but temperature-induced deviations in laser light direction occur
Solution Approach 1:
The patent utilizes the piezoelectric effect of quartz crystal to create an adjustable optical element that can compensate for temperature-induced deviations. By applying electrical voltage to the quartz crystal prism, the optical path can be dynamically adjusted to maintain laser light direction accuracy even during continuous operation when temperature changes occur.
Solution Approach 2:
The patent implements a feedback mechanism where the quartz crystal's optical properties are dynamically controlled based on temperature conditions. The system monitors and adjusts the optical path through the quartz crystal prism to counteract temperature-induced deviations, ensuring consistent laser light direction accuracy throughout continuous operation.
3Reliability
If quartz crystal prism is oriented with optic axis perpendicular to light incident plane, then temperature-induced deviations are minimized, but the device complexity increases
Solution Approach 1:
The patent employs an asymmetric orientation of the quartz crystal prism where the optic axis is positioned perpendicular to the light incident plane. This specific asymmetric configuration exploits the crystal's optical anisotropy to minimize temperature-induced deviations. The asymmetric design is simpler than alternative symmetric configurations because it directly leverages the crystal's inherent properties rather than requiring complex compensating elements.
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 configuration reduces the need for expensive calcium fluoride, stabilizes laser light direction, and enhances the reliability and accuracy of the narrowed-line laser apparatus by minimizing temperature-induced deviations and optical effects, thereby improving the apparatus's operational stability and efficiency.
Implementation Method 1
a first quartz crystal prism so disposed that an optic axis thereof is perpendicular to a light incident plane of the laser light entering the first quartz crystal prism
Implementation Method 2
the laser light approaches the grating, and a synthetic quartz prism disposed at a position closest to the grating
Implementation Method 3
a grating configured to reflectively diffract the laser light output from the enlarging optical system
Implementation Method 4
a grating configured to reflectively diffract the laser light
Data Source
AI summary
A line narrowing module includes an enlarging optical system configured to enlarge and output laser light; and a grating configured to reflectively diffract the laser light output from the enlarging optical system, and the enlarging optical system includes a first quartz crystal prism so disposed that an optic axis thereof is perpendicular to a light incident plane of the laser light entering the first quartz crystal prism in such a way that the laser light approaches the grating, and a synthetic quartz prism disposed at a position closest to the grating.