Fin Isolation Structure for Tighter Nanosheet Fin Spacing
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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 neighboring fins, allowing for reduced spacing between fins by up to 50% by moving the fin cutting operation to after STI formation, thereby minimizing damage and increasing manufacturing efficiency.
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
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, and then fins are cut within this protected environment. This sequence allows fin spacing to be reduced while the pre-formed STI structure prevents damage to neighboring fins during the cutting process.
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 enables the fin cutting operation to proceed without directly exposing neighboring fins to damage, thus allowing tighter fin spacing while maintaining fin integrity.
2Reliability
If fin cutting operation is performed after shallow trench isolation formation, then neighboring fins are protected from damage, but spacing between fins increases
Solution Approach 1:
The patent reverses the conventional sequence by performing preliminary shallow trench isolation formation before fin cutting. This preliminary STI formation creates a protective framework that enables subsequent fin cutting with reduced spacing without damaging neighboring fins, thus resolving the contradiction between fin spacing reduction and fin protection.
3Ease of manufacture
If conventional fin cutting process is used, then manufacturing process is simpler, but damage to neighboring fins occurs
Solution Approach 1:
The patent modifies the manufacturing sequence by performing shallow trench isolation formation as a preliminary step before fin cutting. While this adds a process step, it enables significantly reduced fin spacing and eliminates fin damage, ultimately improving manufacturing efficiency and device density despite the additional process step.
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.