FinFET Fin Patterning Using Mask and Spacer Merging
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Solution Overview
Problem
Current lithography techniques face limitations in patterning fin-like field-effect transistors (FinFET) devices, particularly in achieving precise non-rectangular patterns with uniform end-cutting and minimizing corner rounding due to resolution limits, especially around pattern corners.
Innovation Solution
The method involves using specialized masks with sub-resolution features and spacer technology to enhance lithography resolution, allowing for the formation of non-rectangular patterns with improved corner fidelity and uniformity by merging mask portions and spacer materials to protect and define the pattern edges during etching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional lithography techniques are used for patterning FinFET devices, then the process is simple and straightforward, but the resolution is insufficient to achieve precise non-rectangular patterns with uniform end-cutting and minimal corner rounding
Solution Approach 1:
The mask is divided into multiple separate mask portions (first mask portion, second mask portion, third mask portion) that are deposited at different orientations. Each mask portion is positioned at specific locations relative to the fin structures, allowing the etch process to proceed in stages and achieve precise non-rectangular patterns with controlled corner rounding and uniform end-cutting.
Solution Approach 2:
The patent introduces a temporal dimension to the patterning process by performing multiple deposition steps at different orientations and positions. Instead of attempting to create the entire complex pattern in a single lithography step, the process unfolds over time with sequential mask depositions, allowing each mask portion to protect specific regions during targeted etching operations.
2Manufacturing precision
If multiple mask portions are deposited at different orientations to form non-rectangular patterns, then corner rounding is reduced and pattern accuracy is improved, but the process complexity and number of steps increase
Solution Approach 1:
Mask portions are deposited in advance at specific orientations and positions before the final etching process. The first mask portion is deposited with fins extending in a first direction, the second mask portion with fins extending in a second direction, and the third mask portion at a third orientation. This preliminary positioning of mask portions prepares the structure for subsequent selective etching, ensuring that corner rounding is minimized and pattern accuracy is achieved.
3Manufacturing precision
If spacer material is used to merge mask portions and protect pattern edges, then uniform end-cutting and edge definition are achieved, but the process requires additional materials and steps
Solution Approach 1:
Spacer material is introduced as an intermediary substance between the mask portions and the fin structures. The spacer material merges adjacent mask portions together and provides protective coverage during the etching process. This intermediary layer ensures uniform end-cutting of the fin structures and maintains precise edge definition, as the spacer material is removed selectively after serving its protective function.
Data Source
AI summary
A method for patterning fins for FinFET devices are disclosed. The method includes forming elongated protrusions on a semiconductor substrate and forming a mask covering a first portion of the elongated protrusions. The method further includes forming a spacer surrounding the mask. The mask and the spacer together cover a second portion of the elongated protrusions. The method further includes removing a portion of the elongated protrusions not covered by the mask and the spacer. In an embodiment, an outer boundary of the spacer and the mask corresponds to an outer boundary of a non-rectangular pattern.