Reducing End-to-End Spacing in Semiconductor Masks via Plasma Etching
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Solution Overview
Problem
As semiconductor devices continue to shrink, traditional photolithography equipment struggles to achieve the increasingly smaller pitch and end-to-end spacing required, approaching the theoretical limits of its capabilities.
Innovation Solution
A method involving multiple patterning processes and the use of a plasma ribbon beam with controlled ion direction and anisotropic etching to reduce end-to-end spacing between features in semiconductor structures, allowing for the formation of features with dimensions below what is achievable through traditional photolithography.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional photolithography equipment is used, then manufacturing process is simple, but end-to-end spacing between features cannot be reduced below a certain limit
Solution Approach 1:
The patterning process is divided into multiple sequential steps: forming a first mask layer with initial features, forming a second mask layer with additional features, and selectively removing portions of the second mask layer to create cut features that reduce end-to-end spacing. This segmentation allows traditional photolithography to be combined with additional patterning steps to achieve spacing below conventional limits.
Solution Approach 2:
The invention introduces a vertical dimension by forming a multi-layer mask structure where the second mask layer is deposited over the first mask layer. The selective removal of the second mask layer creates cut features that extend into the first mask layer, utilizing the vertical stacking dimension to achieve reduced horizontal spacing between features.
2Length of moving object
If photolithography process parameters are optimized, then feature size is reduced, but process window becomes smaller and manufacturing becomes more difficult
Solution Approach 1:
The manufacturing process is segmented into distinct stages with different objectives: first mask formation defines initial feature locations, second mask formation adds additional features, and selective removal creates the final reduced-spacing pattern. Each stage can be optimized independently, avoiding the need to push traditional photolithography to its theoretical limits while still achieving small final feature sizes.
Solution Approach 2:
The multi-layer mask structure acts as an intermediary that decouples the feature size reduction from the direct photolithography process. Instead of relying solely on photolithography resolution, the mask layers serve as intermediaries that define the final pattern through their geometric relationships and selective removal, thereby maintaining a larger process window.
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 creation of semiconductor structures with reduced end-to-end spacing, overcoming the limitations of traditional photolithography and achieving smaller feature sizes necessary for advanced semiconductor devices.
Implementation Method 1
performing a second etching process on the mask layer to reduce an end-to-end spacing between the first opening and the second opening, the first etching process and the second etching process having different anisotropy properties
Implementation Method 2
the use of a plasma ribbon beam with controlled ion direction and anisotropic etching to reduce end-to-end spacing between features
Data Source
AI summary
A method includes forming a mask layer over a target layer. A first etching process is performed on the mask layer to form a first opening and a second opening in the mask layer. A second etching process is performed on the mask layer to reduce an end-to-end spacing between the first opening and the second opening. The first etching process and the second etching process have different anisotropy properties. A pattern of the mask layer is transferred to the target layer.