Odd Fin Formation via Sidewall Imaging Transfer
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Solution Overview
Problem
Conventional sidewall imaging transfer (SIT) processes consistently result in even numbers of fins, making it difficult to form odd numbers of fins, especially as fin pitch scales and fin-to-fin spacing narrows, as removing unwanted fins without damaging adjacent ones becomes nearly impossible.
Innovation Solution
The method involves forming a pad layer, mandrels, and pairs of spacers on a substrate, where the first pair of spacers is selectively removed, and the mandrels and second pair of spacers are used as fin masks to pattern an odd number of fins, eliminating the need for subsequent fin removal processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional SIT process is used to form fins, then even number of fins is produced, but odd number of fins cannot be formed without additional fin cut process
Solution Approach 1:
The spacer formation process is segmented into two distinct pairs: first spacers formed on both sides of mandrels, and second spacers formed only on the side opposite the mandrels. This segmentation allows selective removal of first spacers while retaining second spacers, enabling odd number fin patterning without additional fin cut processes
Solution Approach 2:
The second spacers are formed in advance on the side opposite the mandrels before the mandrels are removed. This preliminary action ensures that when mandrels are removed, the second spacers remain in place to serve as masks for forming the odd number of fins, eliminating the need for subsequent fin removal
2Adaptability or versatility
If fin cut process is performed to remove dummy fins, then odd number of fins can be formed, but adjacent device fins are compromised due to narrow fin-to-fin space
Solution Approach 1:
The first spacers are selectively removed while the second spacers and mandrels are retained. This extraction leaves the second spacers in place as protective masks during fin formation, preventing any contact or damage to adjacent device fins that would occur in conventional fin cut processes
Solution Approach 2:
The second spacers act as intermediary structures that remain in place during the fin formation process. These spacers serve as the final masks that define the odd number of fins while protecting adjacent structures, replacing the need for direct fin removal
3Adaptability or versatility
If conventional SIT process is used, then even number of fins is formed, but additional process steps are required to achieve odd number of fins
Solution Approach 1:
The mandrels and second spacers are combined to form the final fin masks. This merging allows the odd number of fins to be formed in a single patterning step without requiring separate fin removal processes, improving manufacturing efficiency while maintaining flexibility
Solution Approach 2:
The second spacers are formed in advance and positioned to work with the mandrels as the final masks. This preliminary positioning ensures that the odd number fin pattern is achieved directly during the main fin formation process, eliminating additional process steps
Data Source
AI summary
Techniques for forming an odd number of fins by SIT are provided. In one aspect, a method of forming an odd number of fins by SIT includes the steps of: forming a pad layer on a substrate; forming at least one mandrel on the pad layer; forming a first pair of spacers on opposite sides of the mandrel; forming a second pair of spacers on a side of the first pair of spacers opposite the mandrel; removing the first pair of spacers selective to the mandrel and the second pair of spacers; and patterning the odd number of fins in the substrate using a combination of the mandrel and the second pair of spacers as fin masks. A method of forming a finFET device and a fin device structure are also provided.