Fin Isolation Structure for Leakage Blocking at Tight Gate Pitch
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Solution Overview
Problem
Current methods for scaling gate pitch in multi-gate devices, such as FinFETs and GAA transistors, fail to achieve the required device density and performance for aggressively scaled circuits due to limitations in leakage current prevention and cell isolation.
Innovation Solution
A semiconductor device structure is manufactured using a process that includes forming alternating semiconductor layers, embedding fins in an insulating material, and performing a fin-cut process to create isolation regions, which are filled with dielectric material to block current leakage between transistors, thereby enhancing device density and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If conventional gate pitch scaling methods (PODE, CPODE) are used, then gate pitch is reduced, but device density and cell isolation are insufficient
Solution Approach 1:
The isolation structure is segmented into multiple portions (first portion in depletion region, second portion extending into accumulation region) that are disposed between adjacent fins. This segmentation allows the isolation structure to effectively block leakage current paths while maintaining compact device density, resolving the contradiction between reduced gate pitch and sufficient isolation.
Solution Approach 2:
The isolation structure implements local quality by positioning different portions at specific locations: the first portion is located in the depletion region between adjacent fins, while the second portion extends into the accumulation region. This localized positioning optimizes leakage current blocking at critical interfaces without compromising overall device performance.
2Productivity
If gate pitch is reduced to increase device density, then more transistors fit in smaller area, but leakage current between transistors increases
Solution Approach 1:
The isolation structure acts as an intermediary element disposed between adjacent fins and source/drain regions. It mediates the harmful interaction by blocking leakage current paths that would otherwise occur through the substrate between closely spaced transistors, enabling high device density without sacrificing electrical isolation.
Solution Approach 2:
The isolation structure extracts and removes the leakage current path from the system by providing a dedicated blocking structure between adjacent fins. This extracted isolation mechanism prevents harmful current flow while maintaining the compact layout required for high device density.
3Object-generated harmful factors
If isolation structures are added to prevent leakage current, then leakage current is blocked, but device complexity increases
Solution Approach 1:
The isolation structure merges multiple functions into a single integrated structure: it provides electrical isolation between adjacent fins, blocks leakage current paths, and defines device boundaries. This merging reduces overall device complexity compared to using separate structures for each function.
Solution Approach 2:
The isolation structure exhibits multi-functionality by simultaneously serving as an electrical isolation barrier, a leakage current blocker, and a structural element that defines fin spacing. This universal structure eliminates the need for additional specialized components, reducing device complexity.
Data Source
AI summary
A semiconductor device structure, along with methods of forming such, are described. The semiconductor device structure includes a substrate and an isolation structure disposed on the substrate and between two neighboring transistors. The isolation structure includes a dielectric feature, an insulating material disposed below the dielectric feature. The insulating material includes an upper portion comprising a first sidewall and a top surface in contact with the dielectric feature, and a bottom portion having a second sidewall, wherein the second sidewall is surrounded by and in contact with the substrate. The insulating material further includes a middle portion having a third sidewall disposed between the first sidewall and the second sidewall. The semiconductor device structure also includes a dielectric material in contact with the dielectric feature, the first sidewall, the third sidewall, and the substrate.