FinFET Fin Sidewall Structuring to Prevent Adhesion Collapse
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Solution Overview
Problem
The semiconductor industry faces challenges in reducing the adhesion forces between adjacent fins in FinFET devices, which can lead to fin collapse and process failures during manufacturing.
Innovation Solution
The formation of semiconductor fins with reduced contact area is achieved by etching hard mask regions to create lateral protrusions, depositing a rough film over the fins, or performing an etching process to roughen the sidewalls of the fins, thereby reducing adhesion forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the contact area between adjacent fins is reduced, then adhesion forces are reduced and fin collapse is prevented, but manufacturing complexity increases due to additional etching steps
Solution Approach 1:
The patent applies preliminary action by forming lateral protrusions on the hard mask regions before the fin etching process. These protrusions are created through selective etching of the hard mask layer, which then serve as protective features during subsequent processing steps. This preliminary structuring prevents fin collapse by reducing adhesion forces between adjacent fins before the fins are fully formed, thereby improving reliability without requiring complex real-time control during fin formation.
Solution Approach 2:
The patent segments the hard mask region into distinct functional zones: protected regions that form the lateral protrusions and exposed regions that allow fin etching. This segmentation is achieved through selective masking techniques where certain areas of the hard mask are removed while others are retained. The segmented structure enables differential etching rates and provides mechanical support to reduce fin adhesion, resolving the contradiction between maintaining simple processes and achieving reliable fin structures.
2Reliability
If lateral protrusions are formed on hard mask regions, then adhesion forces between fins are reduced, but manufacturing precision requirements increase
Solution Approach 1:
The patent utilizes parameter changes by controlling the etching conditions to selectively remove portions of the hard mask layer and form lateral protrusions. By adjusting etching parameters such as etchant concentration, temperature, and exposure time, the process creates the desired protrusion geometry with appropriate dimensions. This parameter control allows the formation of protrusions that effectively reduce fin adhesion forces while maintaining manufacturing precision through process optimization rather than requiring ultra-precise lithographic patterning.
Data Source
AI summary
A method includes depositing a mask layer over a semiconductor substrate, etching the mask layer to form a patterned mask, wherein a sidewall of the patterned mask includes a first sidewall region, a second sidewall region, and a third sidewall region, wherein the first sidewall region is farther from the semiconductor substrate than the second sidewall region and the second sidewall region is farther from the semiconductor substrate than the third sidewall region, wherein the second sidewall region protrudes laterally from the first sidewall region and from the third sidewall region, etching the semiconductor substrate using the patterned mask to form fins, forming a gate stack over the fins, and forming source and drain regions in the fin adjacent the gate stack.