Single-Mask Double-Patterning Lithography Shift-Trim Method
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Double-patterning lithography (DPL) faces challenges including high mask costs, reduced fabrication throughput, and critical dimension (CD) variability due to the need for two photomasks and additional processing steps, as well as CD bimodality affecting transistor performance.
Innovation Solution
The shift-trim double-patterning lithography (ST-DPL) method uses a single photomask by shifting it a predetermined distance and applying a trim mask to achieve 2X pitch relaxation, reducing unnecessary features and maintaining compatibility with standard DPL processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If two critical photomasks are used for DPL, then patterning capability is improved, but mask costs increase
Solution Approach 1:
A single photomask is designed to perform multiple functions by containing multiple pattern sets that can be selectively exposed. The mask structure includes first and second patterns with different translational symmetries, allowing one mask to replace what would traditionally require two separate masks, thereby reducing mask costs while maintaining patterning capability
Solution Approach 2:
The single photomask is segmented into multiple functional regions containing different pattern sets. Each region can be selectively exposed through dose modulation or proximity control, allowing the mask to generate multiple patterns in a single exposure step, thus reducing the total number of masks needed
2Manufacturing precision
If additional processing steps are added for second pattern, then patterning precision is improved, but fabrication throughput decreases
Solution Approach 1:
Multiple patterning operations are merged into a single exposure step by using a single photomask with multiple pattern sets. The different patterns are exposed simultaneously or in a single pass through dose modulation techniques, eliminating the need for separate exposure and etch steps for each pattern, thereby improving fabrication throughput while maintaining patterning precision
Solution Approach 2:
The exposure process is made continuous by enabling single-step exposure of multiple patterns through the single photomask. The system maintains continuous useful action by avoiding interruptions between separate exposure steps, using techniques like dose modulation to selectively activate different pattern regions within a single exposure cycle
3Manufacturing precision
If overlay of second to first pattern is tight, then pattern accuracy is improved, but CD variability increases
Solution Approach 1:
The mask patterns are designed with different translational symmetries - the first pattern has a translational symmetry vector that is not parallel to the second pattern's vector. This asymmetric design allows the patterns to be distinguished and selectively exposed based on their directional characteristics, improving pattern accuracy while reducing CD variability by eliminating reliance on tight overlay between symmetric patterns
4Quantity of substance
If single photomask is used to reduce cost, then mask costs decrease, but fabrication throughput worsens
Solution Approach 1:
The system introduces dynamic control over the exposure process through dose modulation, allowing selective activation of different pattern regions on the single photomask. This dynamic approach enables multiple patterns to be exposed in a single pass without requiring sequential processing steps, thereby maintaining high fabrication throughput while using only one mask
Data Source
AI summary
A method of printing a final layout on a wafer comprises printing a first pattern from a first mask located at a first position onto the wafer, shifting the first mask by a predetermined distance to a second position, printing the first pattern from the first mask located at the second position onto the wafer, and applying a trim mask to the wafer.