Photomask Pattern Positioning for Critical Dimension Control
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Solution Overview
Problem
Conventional photolithography techniques face challenges in achieving precise critical dimension control as integrated circuit densities increase, particularly due to the limitations of wave properties of light used in imaging processes.
Innovation Solution
A method is introduced to determine the position of photomask patterns using mask rules, where a non-critical edge is positioned a specific distance from a critical edge to affect the length of the critical edge, enhancing critical dimension control through multi-pattern processing and proximity correction techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional photolithography imaging techniques are used, then high throughput and economical processing are achieved, but critical dimension control deteriorates as integrated circuit densities increase
Solution Approach 1:
The photomask pattern is segmented into multiple separate patterns (first pattern and second pattern) that are positioned at different locations. Each pattern is independently designed and positioned to address specific critical dimensions, allowing the system to maintain high throughput while improving critical dimension control through multi-pattern processing
Solution Approach 2:
Different regions of the photomask are assigned different pattern densities and configurations based on local requirements. The first pattern is positioned in regions requiring specific critical dimension control, while the second pattern addresses other critical dimensions, enabling localized optimization of manufacturing precision without compromising overall throughput
2Device complexity
If wave properties of light are used in imaging, then the lithography process can be simplified, but feature definition precision deteriorates when critical dimensions approach or below the wavelength of light
Solution Approach 1:
The solution moves from conventional two-dimensional imaging to a multi-dimensional approach by introducing multiple patterns at different positions and orientations. This dimensional expansion allows the system to overcome the wavelength limitations by creating multiple projection paths that collectively define features with higher precision
3Productivity
If single photoresist processing is used, then the process is simpler and faster, but critical dimension control deteriorates due to inability to individually optimize patterns
Solution Approach 1:
The single photoresist processing is segmented into multiple sequential photoresist processing steps. Each photoresist layer is exposed to different patterns (first pattern and second pattern) and developed separately, allowing individual optimization of each pattern's critical dimensions while maintaining overall processing efficiency through systematic multi-step execution
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 approach improves critical dimension control by allowing for more precise positioning of photomask patterns, effectively addressing the limitations of conventional imaging techniques and achieving better control over feature sizes in dense integrated circuit areas.
Implementation Method 1
A stepper includes a light source and optics that project light coming through the photomask to image the circuit pattern on a photoresist film
Data Source
AI summary
The present application is directed a method for determining the position of photomask patterns in a mask making process. The method comprises providing one or more mask rules defining the minimum spacing between photomask patterns. The method further comprises determining the position of a first photomask pattern relative to an adjacent second photomask pattern, the first photomask pattern having a critical edge for defining a critical dimension of a first device structure and a non-critical edge for defining a non-critical dimension. The non-critical edge is attached to the critical edge so that the positioning of the non-critical edge will affect the length of the critical edge. The non-critical edge of the first photomask pattern is positioned a distance X from an edge of the second photomask pattern, wherein the distance X is chosen to be substantially the minimum spacing allowed by the mask rules. Embodiments directed to software modules for implementing the method and patterning processes employing the method are also disclosed.