Pattern Transfer via Dual Hard Mask Layers
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Solution Overview
Problem
In semiconductor manufacturing, the optical proximity effect causes defects during photolithographic processes, especially for small critical dimensions and random pattern layouts, leading to reduced process windows and complexity in resolution enhancement technologies.
Innovation Solution
The method involves using two different patterned hard mask layers, with the first layer comprising a circuit pattern and dummy patterns to maintain equal spaces, allowing for improved resolution and reduced optical proximity effects, thereby simplifying the lithography process and omitting the need for complex resolution enhancement techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If photolithographic process is used for transferring circuit pattern with small critical dimension, then pattern transfer is achieved, but optical proximity effect causes defects and reduces manufacturing precision
Solution Approach 1:
The patent introduces a first hard mask layer with dummy patterns as an intermediary between the lithography process and the final circuit pattern. This intermediary layer absorbs the optical proximity effects, preventing them from directly affecting the circuit pattern transfer. The dummy patterns act as a buffer that compensates for the harmful optical effects.
Solution Approach 2:
The patent segments the pattern transfer process into two distinct stages: first transferring a pattern with dummy features to a hard mask layer, then using that hard mask to transfer the final circuit pattern. This segmentation allows each stage to be optimized independently, with the first stage focusing on uniform spacing and the second on precise circuit feature transfer.
2Manufacturing precision
If resolution enhancement technology (RET) is applied to correct optical proximity effect, then pattern transfer precision is improved, but device complexity and process complexity increase
Solution Approach 1:
The patent performs preliminary action by pre-configuring the lithography pattern with dummy patterns and uniform spacing before the actual pattern transfer. This preliminary configuration prevents optical proximity effects from causing defects in the first place, eliminating the need for complex post-processing RET techniques.
3Adaptability or versatility
If random pattern layout is used for circuit design, then design flexibility is improved, but process window decreases due to varying spaces between elements
Solution Approach 1:
The patent applies local quality by maintaining uniform spacing only in regions with dummy patterns where optical proximity effects are critical, while allowing random layouts in other regions. This localized approach to spacing optimization maintains design flexibility elsewhere in the circuit while ensuring manufacturing precision in critical areas.
Data Source
AI summary
Pattern transfer is achieved by forming a first patterned hard mask layer with a circuit pattern and a plurality of dummy patterns on a substrate, forming a second pattern mask layer on the substrate, exposing the circuit pattern of the first pattern mask layer, and removing a portion of the substrate exposed by the first patterned mask layer, so as to transfer the circuit pattern to the substrate.