Double-Headed Projection Optical System for High-Throughput Lithography
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Solution Overview
Problem
Current photolithography processes for semiconductor device manufacturing face challenges in efficiently projecting and superimposing patterns on a photosensitive substrate using existing projection optical systems, particularly in maintaining high throughput and image quality without increasing the optical system size.
Innovation Solution
A double-headed projection optical system is developed, comprising multiple refractive imaging optical systems and folding members, which allows for the formation of images from two spaced patterns in parallel within a predetermined region on a photosensitive substrate, ensuring the required image-side numerical aperture and effective imaging area without increasing the optical system size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a double exposure method is used to superimpose two types of patterns in one shot area, then throughput is improved, but the complexity of the projection optical system increases
Solution Approach 1:
The projection optical system is divided into two independent imaging optical systems (first and second imaging optical systems) that can separately focus light from two different masks onto the wafer. Each imaging system operates independently with its own optical path, allowing simultaneous projection of two patterns without requiring a single complex multi-component system.
Solution Approach 2:
The patent introduces a vertical stacking dimension by positioning the first and second masks at different heights (first mask at height h1, second mask at height h2) above the wafer. This three-dimensional arrangement allows both masks to be illuminated simultaneously through the projection optical system without optical interference, enabling double exposure in one shot area and thereby improving throughput.
2Manufacturing precision
If the optical system size is increased to ensure image-side numerical aperture, then image quality is improved, but the device size increases
Solution Approach 1:
The first and second imaging optical systems share common optical components including the projection optical system, wafer stage, and detection systems. The optical paths are merged at the wafer plane where both patterns are projected simultaneously. This merging of functions and components allows the system to achieve high image-side numerical aperture for both patterns without requiring separate dedicated optical paths, thereby avoiding excessive size increase.
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 enables high-throughput device manufacturing by effectively superimposing patterns on a photosensitive substrate, maintaining image quality and suppressing vibration-induced issues, while allowing for easier manufacturing and stability of refractive elements.
Implementation Method 1
every optical element having a power in the third imaging optical system is a refractive element
Implementation Method 2
a first folding member for guiding light from the first imaging optical system to the third imaging optical system; and a second folding member for guiding light from the second imaging optical system to the third imaging optical system
Data Source
AI summary
A projection optical system for forming an image of a first surface on a second surface has a first imaging optical system and a second imaging optical system, and a folding member for guiding light from the first imaging optical system to the second imaging optical system. Every optical element having a power in the second imaging optical system is a refractive element.