Selective Fin Cut Process for FINFET Fabrication
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Solution Overview
Problem
Existing fin cut processes during FINFET fabrication often result in unwanted fin residue and excessive semiconductor removal, failing to provide a precise and residue-free method for removing unwanted fin structures.
Innovation Solution
A method involving a conformal protective layer over multiple fin structures, patterning openings over unwanted fins, and using a combination of unselective dry-etch and selective wet-etch processes to remove the unwanted fin structures while protecting the remaining fins, including the removal of a hard mask and subsequent semiconductor material exposure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional lithographic fabrication methods are used for fin cut, then the process is simple and fast, but unwanted fin residue and excessive semiconductor removal occur
Solution Approach 1:
The fin cut process is divided into multiple sequential steps: first forming a conformal protective layer over all fin structures, then patterning openings over unwanted fins, followed by selective removal steps. This segmentation allows precise control over which fins are removed while protecting others, eliminating residue issues without excessive complexity
Solution Approach 2:
A conformal protective layer is formed over all fin structures before the fin cut process begins. This preliminary protective action ensures that during subsequent etching steps, only the exposed unwanted fins are removed while the protected fins remain intact, achieving high precision without requiring complex real-time control
2Productivity
If unselective dry-etch process is used to remove unwanted fins, then the removal speed is fast, but fin residue remains and selectivity is poor
Solution Approach 1:
The conformal protective layer acts as an intermediary element between the etch process and the fin structures. It allows the use of aggressive unselective dry-etch for fast removal while the protective layer mediates the process to prevent damage to unwanted fins and eliminate residue, combining speed with precision
Solution Approach 2:
The protective layer provides different protection levels to different fin structures: fins under openings receive no protection and are fully removed, while other fins are protected by the conformal layer. This local differentiation enables precise selective removal with high speed
3Manufacturing precision
If selective wet-etch is used to remove semiconductor material, then the selectivity is high, but the process time is long and productivity is reduced
Solution Approach 1:
The etching process is segmented into two distinct phases: first an unselective dry-etch phase for rapid bulk material removal, then a selective wet-etch phase for precise final cleanup. This segmentation allows each process to operate at its optimal speed and selectivity, achieving both high productivity and high precision
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 minimizes fin residue and unwanted recessing, achieving a cleaner base surface and precise fin cut with reduced semiconductor material loss, enhancing the fin cut process's selectivity and integration with existing FINFET fabrication.
Implementation Method 1
providing a conformal protective layer over multiple fin structures on a substrate
Implementation Method 2
the removing is performed using an unselective dry-etch process
Implementation Method 3
selectively removing the semiconductor material of the at least one unwanted fin structure using, for example, a selective semiconductor wet-etch
Data Source
AI summary
A process is provided for selective removal of one or more unwanted fins during FINFET device fabrication. In one aspect, the process includes: providing a conformal protective layer over multiple fin structures on a substrate; patterning one or more openings over the unwanted fin structure(s); and removing at least a top portion of the unwanted fin structure(s) exposed through the opening(s), the removing including removing at least a portion of the conformal protective layer over the unwanted fin structure(s) exposed through the opening(s). In enhanced aspects, the removing includes removing a hard mask from the at least one unwanted fin structure(s) exposed through the opening(s), and selectively removing semiconductor material of at least one unwanted fin structure(s). The conformal protective layer protects one or more remaining fin structures during the selective removal of the semiconductor material of the unwanted fin structure(s).