Multi-Step Fin Isolation Structure for Well Leakage Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing FinFET manufacturing processes face challenges in forming reliable devices at smaller sizes due to well leakage and shallow trench isolation issues, leading to increased latch-up and reduced mechanical strength.
Innovation Solution
A multi-step isolation structure is formed between fin structures, comprising a first isolation portion and a second isolation portion with a narrower top width, enhancing isolation depth and mechanical strength, thereby reducing well leakage and preventing fin collapse.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If shallow trench isolation (STI) is used in FinFET manufacturing, then isolation between devices is achieved, but well leakage increases and latch-up occurs at smaller device sizes
Solution Approach 1:
The isolation structure is divided into multiple segments: a first isolation portion at a higher elevation and a second isolation portion extending downward at a narrower width. This segmentation allows each portion to perform its isolation function independently, with the first portion providing broad coverage and the second portion providing deep isolation to block well leakage paths, thereby resolving the contradiction between isolation effectiveness and well leakage prevention at scaled dimensions.
Solution Approach 2:
The isolation structure transitions from a conventional single-level shallow trench isolation to a multi-level three-dimensional structure. The first isolation portion sits at a higher elevation while the second isolation portion extends downward into the substrate, creating a stepped configuration. This dimensional change enables the structure to block leakage currents that would otherwise travel through the well region, effectively preventing well leakage while maintaining device isolation.
2Reliability
If isolation depth is increased to reduce well leakage, then latch-up is prevented, but mechanical strength of the fin structure decreases
Solution Approach 1:
The isolation structure employs different widths at different depths: the first isolation portion has a broader width for mechanical support, while the second isolation portion has a narrower width for deep isolation. This local differentiation allows the structure to provide both mechanical strength at the surface level and effective leakage blocking at deeper levels, resolving the contradiction between latch-up prevention and mechanical strength maintenance.
Solution Approach 2:
The multi-step isolation structure segments the isolation function into two distinct portions: the first isolation portion provides mechanical support and broad coverage, while the second isolation portion provides deep isolation for latch-up prevention. This segmentation allows each portion to be optimized for its specific function, thereby resolving the contradiction between mechanical strength and reliability.
3Strength
If multi-step isolation structure with narrower top width is formed, then mechanical strength is maintained, but manufacturing complexity increases
Solution Approach 1:
The multi-step isolation structure is formed by performing isolation operations at different stages of the manufacturing process. The first isolation portion is formed initially, followed by the formation of the second isolation portion at a narrower width. This preliminary action approach allows each isolation portion to be formed using standard manufacturing techniques, avoiding the need for complex single-step processes while achieving the desired mechanical strength and isolation performance.
Data Source
AI summary
A semiconductor device structure is provided. The semiconductor device structure includes a semiconductor substrate including a first well region of a first conductivity type. The semiconductor device structure also includes a first fin structure and an adjacent second fin structure formed in and protruding from the first well region. The semiconductor device structure also includes a first isolation structure formed in the first well region between the first fin structure and the second fin structure. A first sidewall surface of the first fin structure faces to a second sidewall surface of the second fin structure. The first sidewall surface and the second sidewall surface each extend along at least two directions from a bottom of the first isolation structure to a top of the first isolation structure.