Lithography Gray Tone Control via Local Transmittance
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Solution Overview
Problem
Conventional lithography systems require multiple passes to write gray tone patterns into a photoresist layer, which decreases throughput and efficiency.
Innovation Solution
A lithography process that uses a system with a controller to provide mask pattern data to a processing unit with multiple image projection systems. Each exposure area includes a gray pattern with sub-grids and pattern units, allowing for varying local transmittance rates of write beams to be projected in a single scan, thereby forming a desired profile in the photoresist layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple passes are used to write gray tone patterns into photoresist, then gray tone pattern writing capability is achieved, but throughput decreases
Solution Approach 1:
The exposure area is divided into multiple sub-grids, and each sub-grid is further divided into pattern units with patterned lines. This segmentation allows different local transmittance rates to be applied simultaneously across different regions, enabling gray tone pattern writing in a single pass while maintaining high throughput
Solution Approach 2:
The system applies different local transmittance rates to different sub-grids and pattern units within the same exposure area. By varying the transmittance rate locally across the substrate, the system can create gray tone patterns with different exposure doses simultaneously, achieving both pattern writing capability and high throughput
2Manufacturing precision
If local transmittance rate control is implemented across sub-grids, then photoresist profile precision is improved, but system complexity increases
Solution Approach 1:
The exposure area is segmented into sub-grids and pattern units, allowing independent control of local transmittance rates. This segmentation enables precise control of photoresist profiles across different regions without requiring a completely complex system redesign, as each segment can be controlled independently through the existing projection system
Solution Approach 2:
The system controls the local transmittance rate by varying parameters such as the number of shots projected to each sub-grid and the positioning of patterned lines within pattern units. By changing these parameters, the system achieves precise photoresist profile control while utilizing the existing projection infrastructure, thereby limiting the increase in system complexity
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 writing of gray tone patterns in a single exposure operation, improving throughput and allowing for precise control of photoresist layer profiles, including varying step heights and planarization of the top surface.
Implementation Method 1
A first portion of the photoresist layer is removed in a first development process and a second portion of the photoresist layer is removed in a second development process
Data Source
AI summary
Embodiments of the present disclosure generally relate to lithography systems. More particularly, embodiments of the present disclosure relate to a method, a system, and a software application for a lithography process to control transmittance rate of write beams and write gray tone patterns in a single exposure operation. In one embodiment, a plurality of shots are provided by an image projection system in a lithography system to a photoresist layer. The plurality of shots exposes the photoresist layer to an intensity of light emitted from the image projection system. The local transmittance rate of the plurality of shots within an exposure area is varied to form varying step heights in the exposure area of the photoresist layer.