FinFET Fin-Cut Isolation Structure for Void-Free Trench Fill
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Solution Overview
Problem
The semiconductor industry faces challenges in reducing seam and void formation in dielectric material within trenches during the fin cut process, leading to issues such as shorting between contact plugs and affecting device yield and performance.
Innovation Solution
A method involving the use of multiple dielectric materials, where a first dielectric material is filled into the trench and partially removed, followed by filling the upper portion with a second dielectric material, which can be the same or different, to reduce the aspect ratio and prevent seam formation, and improve gap-fill performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single dielectric material is filled into the trench, then the manufacturing process is simple, but seam and void formation occurs leading to shorting between contact plugs
Solution Approach 1:
The dielectric filling process is segmented into multiple steps: first filling the trench with a bottom dielectric material, selectively removing portions to create recesses, then filling the upper portions with a top dielectric material. This segmentation eliminates seam and void formation by ensuring complete gap-fill at each stage while reducing the aspect ratio that causes defects.
Solution Approach 2:
The bottom dielectric material is deposited and selectively removed in advance before the top dielectric material is filled. This preliminary action creates optimized recesses that facilitate complete filling of the upper portion without voids or seams, preventing shorting between contact plugs.
2Manufacturing precision
If the trench aspect ratio is high, then the fin cut process is effective, but gap-fill performance deteriorates causing seam and void formation
Solution Approach 1:
The deep trench is divided into lower and upper portions filled at different stages. The bottom dielectric material fills the lower portion first, then selective removal creates recesses that reduce the effective aspect ratio for the subsequent top dielectric material filling, ensuring complete gap-fill performance.
Solution Approach 2:
The bottom dielectric material is selectively removed to create recesses that extend beyond what would be needed for a simple fill. This partial removal action ensures that the top dielectric material can completely fill the upper portion without voids, achieving excessive gap-fill quality that prevents defects.
Data Source
AI summary
A semiconductor device a method of forming the same are provided. The semiconductor device includes a substrate, a first isolation structure and a second isolation structure over the substrate, a semiconductor fin over the substrate and between the first isolation structure and the second isolation structure, and a third isolation structure extending through the semiconductor fin and between the first isolation structure and the second isolation structure. A top surface of the semiconductor fin is above a top surface of the first isolation structure and a top surface of the second isolation structure. The third isolation structure includes a first dielectric material and a second dielectric material over the first dielectric material. An interface between the first dielectric material and the second dielectric material is below the top surface of the first isolation structure and the top surface of the second isolation structure.