Fin Isolation Structure for Tight Fin Spacing in GAA FETs
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Solution Overview
Problem
In advanced semiconductor technology nodes, dimension scaling poses challenges in cutting fins of semiconductor devices without damaging neighboring fins, leading to difficulties in achieving adequate spacing and reducing complexity in manufacturing processes.
Innovation Solution
The implementation of fin isolation structures formed after shallow trench isolation (STI) formation, which acts as an etch stop layer and protects lateral sidewalls of neighboring fins, allowing for reduced spacing between fins by up to 10%-50% and minimizing damage during the fin cutting process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If fin cutting operation is performed before shallow trench isolation formation, then fin spacing can be reduced, but neighboring fins are damaged during the cutting process
Solution Approach 1:
The patent applies preliminary action by forming the shallow trench isolation structure before performing the fin cutting operation. The STI structure is prepared in advance as a protective framework that will prevent damage to neighboring fins during subsequent cutting processes. This sequence reversal ensures that the protective isolation structures are in place before the potentially damaging cutting operation occurs.
Solution Approach 2:
The shallow trench isolation structure serves as an intermediary protective element between the cutting tool and the neighboring fins. By introducing this intermediate structure, the patent prevents direct contact between the cutting process and the fins that need to be protected, thereby eliminating damage while still allowing for reduced spacing.
2Device complexity
If fin cutting operation is performed before shallow trench isolation formation, then manufacturing process complexity is reduced, but damage to neighboring fins occurs
Solution Approach 1:
The patent resequences the manufacturing process by performing preliminary formation of shallow trench isolation structures before fin cutting. This preliminary action adds a step to the process but eliminates the need for complex damage repair or rework operations, ultimately simplifying the overall manufacturing complexity while preventing fin damage.
Solution Approach 2:
By introducing the shallow trench isolation structure as an intermediary element in the manufacturing process, the patent creates a protective barrier that eliminates harmful damage to neighboring fins. This intermediary structure manages the interaction between cutting operations and adjacent fins, preventing harmful effects while maintaining process feasibility.
3Quantity of substance
If spacing between fins is reduced, then functional density increases, but damage to neighboring fins during cutting increases
Solution Approach 1:
The patent enables reduced fin spacing by performing preliminary formation of shallow trench isolation structures that will protect neighboring fins during cutting. This preliminary protective measure allows the implementation of higher functional density through closer fin spacing without incurring the previously unavoidable damage to adjacent fins.
Solution Approach 2:
The shallow trench isolation structure acts as an intermediary protective barrier that enables reduced fin spacing for increased functional density. By introducing this intermediate protective structure, the patent allows fins to be positioned closer together while preventing damage during the cutting operation, thus achieving higher functional density safely.
Data Source
AI summary
A device includes a substrate and a fin isolation structure between a first gate structure and a second gate structure. The first gate structure wraps around a first vertical stack of nanostructure channels overlying a first fin. The second gate structure wraps around a second vertical stack of nanostructure channels overlying a second fin. The fin isolation structure extends from an upper surface of the first gate structure to an upper surface of the substrate. A trench isolation structure is between the first fin and the fin isolation structure, and has different etch selectivity than the fin isolation structure.