Spacer Patterning With Overlayer Etch for Flat Top Profiles
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Solution Overview
Problem
Conventional self-aligned multi-patterning processes for semiconductor structures result in asymmetric spacer profiles, leading to poor uniformity and pitch variations, and require multiple etch processes with different etchants, which complicates throughput and repeatability.
Innovation Solution
A method involving the deposition of an over layer on a spacer layer, followed by a fluorine-containing etch process with a post-deposition breakthrough step to achieve a flat top profile, simplifying the etching process and improving repeatability by using a single etch process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional spacer patterning processes are used, then spacers can be formed on mandrel sidewalls, but asymmetric profiles with round shoulders result leading to poor uniformity and pitch walk
Solution Approach 1:
An overlayer is deposited conformally over the spacer layer before etching. This preliminary action creates a protective cap that prevents etchant access to the spacer top surface, ensuring that etching occurs only on the sidewalls and producing symmetric spacer profiles with flat tops rather than rounded shoulders
Solution Approach 2:
The overlayer acts as an intermediary material between the etchant and the spacer layer. It selectively protects the spacer top surface during etching while allowing sidewall etching to proceed, thereby mediating the etching process to achieve the desired symmetric profile
2Manufacturing precision
If multiple etch processes with different etchants are used, then various pattern requirements can be met, but throughput decreases and process repeatability becomes poor
Solution Approach 1:
Multiple etching functions are merged into a single etch process by using the overlayer as a selective mask. The process combines breakthrough etching through the overlayer, spacer sidewall etching, and mandrel etching into one continuous step, eliminating the need for multiple separate etch processes with different etchants
Solution Approach 2:
The single etch process performs multiple functions: it etches through the overlayer to expose the spacer sidewalls, etches the spacer sidewalls to create the desired profile, and subsequently etches the mandrel. This multi-functional approach replaces multiple specialized etch processes
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
The method achieves reduced inconsistencies and asymmetries in spacer profiles, enhancing pitch uniformity and process repeatability by modifying the top profiles of the spacer layer to a flat top, while requiring only a single etch process with fluorine-containing gases.
Implementation Method 1
performing an etch process using a fluorine containing etching gas. The etch process includes a post-deposition breakthrough process, removing portions of the over layer on the top surfaces of the patterned mandrel layer, and a main-etch process, removing shoulder portions of the over layer and shoulder portions of the spacer layer
Implementation Method 2
performing a deposition process, the deposition process comprising conformally depositing an over layer over a spacer layer as deposited on top surfaces of a patterned mandrel layer and on sidewalls of the patterned mandrel layer
Data Source
AI summary
A method for spacer patterning includes performing a deposition process, the deposition process comprising conformally depositing an over layer over a spacer layer as deposited on top surfaces of a patterned mandrel layer and on sidewalls of the patterned mandrel layer, and performing an etch process using a fluorine containing etching gas. The etch process includes a post-deposition breakthrough process, removing portions of the over layer on the top surfaces of the patterned mandrel layer, and a main-etch process, removing shoulder portions of the over layer and shoulder portions of the spacer layer.