Spatial Light Modulator Unit for Pupil Intensity Control
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Solution Overview
Problem
Existing exposure devices face challenges in achieving a high degree of freedom for both the intensity levels and shape of the pupil intensity distribution, leading to suboptimal illumination conditions for transferring fine patterns onto wafers.
Innovation Solution
A spatial light modulator unit with a plurality of individually controlled optical elements, including a reflection-type diffractive optical element and a control unit, which applies spatial light modulation to create desired intensity levels and distributions, ensuring both high intensity level freedom and shape flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a movable multi-mirror system is used to change pupil intensity distribution, then the intensity distribution can be continuously adjusted, but the degree of freedom for both intensity levels and shape is limited
Solution Approach 1:
The patent segments the optical elements into a two-dimensional array of independently controllable elements. Each element can be individually controlled to achieve fine-grained adjustment of both intensity levels and shape of the pupil intensity distribution, overcoming the limitations of conventional multi-mirror systems.
Solution Approach 2:
The patent employs dynamically controllable optical elements (such as liquid crystal elements or micro-electro-mechanical mirrors) that can change their optical properties in real-time. This dynamic control enables continuous adjustment of pupil intensity distribution with high degree of freedom for both intensity levels and shape.
2Device complexity
If conventional illumination optical systems are used, then the structure is relatively simple, but the illumination conditions are suboptimal for transferring fine patterns
Solution Approach 1:
The patent changes the controllable parameters of the illumination system by introducing individually controllable optical elements arranged in a two-dimensional array. This enables precise control of pupil intensity distribution parameters (intensity levels and shape) to optimize illumination conditions for fine pattern transfer, achieving high manufacturing precision.
3Adaptability or versatility
If the number of controllable optical elements is increased to improve intensity distribution freedom, then the control complexity and device complexity increase
Solution Approach 1:
The patent merges multiple optical elements into a two-dimensional array configuration where elements work cooperatively. This arrangement achieves high degree of freedom for intensity distribution control while managing device complexity through systematic integration and coordinated control of the 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
The solution enables highly diverse illumination conditions, allowing for excellent exposure performance by individually controlling mirror elements based on intensity levels, thereby enhancing the degree of freedom for intensity distributions without compromising shape flexibility.
Implementation Method 1
a spatial light modulation element which applies spatial light modulation to the light incident from the light source
Implementation Method 2
a reflection-type diffractive optical element
Data Source
AI summary
An illumination optical apparatus that illuminates an object with illumination light includes a first spatial light modulator in an optical path of the illumination light, and having a plurality of first mirror elements; a second spatial light modulator in the optical path of the illumination light from the first spatial light modulator, and having a plurality of second mirror elements; a control unit which controls the first and second spatial light modulators to control postures of the first and second mirror elements; and an optical integrator in the optical path of the illumination light from the second spatial light modulator on an incidence side of an illumination pupil plane of the illumination optical apparatus. The control unit controls the postures of the first and second mirror elements to set a light intensity distribution of the illumination light on the illumination pupil plane.