Multi-level Isolation Structure for FinFET Parasitic Capacitance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In modern integrated circuits, the existing isolation structures for transistors, such as FinFET devices, often result in planar upper surfaces after recess etching, which can lead to inefficiencies in electrical isolation and increased parasitic capacitance, limiting the performance of circuit elements.
Innovation Solution
A multi-level isolation structure is introduced, featuring a stepped upper surface with distinct regions, where the gate structure is positioned above both levels of the isolation structure, allowing for improved electrical isolation and reduced parasitic capacitance by varying the height levels of the insulating material between and adjacent to fins.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a planar isolation structure is used after recess etching, then the manufacturing process is simple, but the parasitic capacitance increases and electrical isolation performance deteriorates
Solution Approach 1:
The patent transitions from a two-dimensional planar isolation surface to a three-dimensional multi-level stepped surface. By creating different height levels (first level and second level) in the isolation structure, the invention increases the vertical dimension utilization, allowing the gate structure to be positioned at different heights above different isolation regions, thereby reducing parasitic capacitance while maintaining manufacturing feasibility through sequential processing steps.
Solution Approach 2:
The patent applies different isolation heights in different local regions. The first region has an isolation surface at a first level, while the second region has an isolation surface at a second level (higher than the first level). This local differentiation allows optimized electrical isolation in specific areas where parasitic capacitance reduction is most critical, while maintaining simpler structure in other areas.
2Object-generated harmful factors
If a multi-level isolation structure is implemented, then parasitic capacitance is reduced and electrical isolation is improved, but the device structure becomes more complex
Solution Approach 1:
The isolation structure is segmented into distinct regions with different heights. The first region contains the first level isolation surface, while the second region contains the second level isolation surface. This segmentation allows each region to be optimized independently for its specific electrical isolation requirements, reducing overall parasitic capacitance without requiring complete restructuring of the entire device.
Solution Approach 2:
By introducing vertical height differentiation through multi-level isolation surfaces, the patent utilizes the vertical dimension to reduce parasitic capacitance between the gate and substrate. The gate structure can extend to different heights above different isolation regions, creating effective electrical isolation without increasing lateral footprint or requiring overly complex three-dimensional configurations.
Data Source
AI summary
One illustrative device disclosed herein includes at least one fin structure and an isolation structure comprising a stepped upper surface comprising a first region and a second region. The first region has a first upper surface and the second region has a second upper surface, wherein the first upper surface is positioned at a first level and the second upper surface is positioned at a second level and wherein the first level is below the second level. In this illustrative example, the device also includes a gate structure comprising a first portion and a second portion, wherein the first portion of the gate structure is positioned above the first upper surface of the isolation structure and above the at least one fin structure and wherein the second portion of the gate structure is positioned above the second upper surface of the isolation structure.