Spacer-Defined Line Cut Structures for Precise Metal Patterning
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Solution Overview
Problem
Conventional lithographic processes face limitations in forming line cuts in line patterns, particularly in metal layers of integrated circuits, due to critical dimension (CD) variations and alignment issues, leading to electrical shorts and increased processing complexity.
Innovation Solution
A method involving conformal deposition of a spacer material on the sidewalls of a resist layer to form line cut structures, followed by etching and removing the resist layer, allowing for well-controlled line cuts that are then used to create dielectric and metal cuts in the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional lithographic processes are used to form line cuts, then the process can be implemented with existing equipment, but critical dimension variations and alignment issues occur leading to electrical shorts
Solution Approach 1:
A spacer layer is introduced as an intermediary material between the resist pattern and the final line cut structure. The spacer is conformally deposited on the sidewalls of the resist pattern, providing precise dimensional control that mediates between the lithographic pattern and the etched feature, thereby reducing CD variation and preventing electrical shorts
Solution Approach 2:
The resist pattern is formed first as a preliminary structure, followed by conformal spacer deposition. This preliminary action allows the spacer to define the final line cut dimensions independently of lithographic limitations, improving manufacturing precision and reliability
2Ease of manufacture
If conventional direct metal removal is used to form cuts, then the process is simple, but alignment issues and CD variations increase processing complexity
Solution Approach 1:
The cut formation process is segmented into distinct steps: resist pattern formation, conformal spacer deposition, and selective etching. This segmentation separates the dimensional definition function (performed by the spacer) from the material removal function (performed by etching), reducing alignment issues and CD variations despite adding process steps
3Manufacturing precision
If conformal spacer deposition is used to form line cuts, then manufacturing precision and alignment are improved, but additional processing steps are required
Solution Approach 1:
The conformal spacer process is self-aligned, where the spacer automatically forms on the sidewalls of the resist pattern without requiring additional alignment steps. The spacer thickness is self-controlled by the conformal deposition process, eliminating the need for separate alignment and dimensional control operations
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 reduces CD variation and processing complexity, improving the precision of line cuts and metal cuts, minimizing the risk of electrical shorts and simplifying the manufacturing process.
Implementation Method 1
conformally depositing, using an ALD process, a conformal layer on at least one sidewall of a cut window
Implementation Method 2
etching the conformal layer from horizontal surfaces of the substrate leaving a cut sidewall spacer on the at least one sidewall
Data Source
AI summary
A method of forming a line cut structure in a space separating lines of a line pattern formed in or on a substrate includes conformally depositing a conformal layer on at least one sidewall of a cut window in a resist layer and through the cut window on a portion of the space, etching the conformal layer from horizontal surfaces of the substrate leaving a cut sidewall spacer on the at least one sidewall, and removing the resist layer to form the line cut structure from the cut sidewall spacer. The method may further include forming a metal cut in a metal line by etching a dielectric layer to transfer the line pattern and the line cut structure into the dielectric layer forming a dielectric line cut structure and then forming a metal layer including the metal line in the dielectric layer.