FinFET Threshold Voltage Control via Fin Length Segmentation
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Solution Overview
Problem
Current fin field effect transistors (finFETs) face challenges in scaling down device components, leading to difficulties in forming individual components and electrical contacts, necessitating a method to control threshold voltage without altering material compositions or doping concentrations.
Innovation Solution
The method involves forming a combination of long and short fin devices on the same substrate, where fin length is adjusted to achieve specific threshold voltages, with long fins ranging from 180 nm to 350 nm and short fins from 60 nm to 140 nm, allowing for varying threshold voltages without changing material compositions or doping concentrations, thereby controlling charge mobility and band gap.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If device dimensions are decreased to improve integration density, then productivity increases, but manufacturing precision deteriorates due to difficulty in forming individual components and electrical contacts
Solution Approach 1:
The patent divides the fin structure into multiple segments of different lengths (short fins and long fins) within the same gate structure. This segmentation allows different threshold voltages to be achieved without changing the overall device footprint, thereby maintaining high integration density while avoiding the manufacturing precision issues associated with further scaling down individual component dimensions
Solution Approach 2:
The patent applies local quality by creating fins with different lengths at different locations under a single gate. The short fins provide one threshold voltage characteristic while long fins provide another, allowing localized variation in electrical properties without requiring further reduction in overall device dimensions
2Reliability
If material compositions or doping concentrations are changed to control threshold voltage, then threshold voltage control improves, but device complexity increases
Solution Approach 1:
The patent changes the geometric parameter (fin length) rather than material composition or doping concentration to control threshold voltage. By varying the fin length parameter, the patent achieves different threshold voltages while maintaining uniform material composition and doping, thereby improving threshold voltage control without increasing device complexity
Data Source
AI summary
A method of forming an arrangement of long and short fins on a substrate, including forming a plurality of finFET devices having long fins on the substrate, where the long fins have a fin length in the range of about 180 nm to about 350 nm, and forming a plurality of finFET devices having short fins on the substrate, where the short fins have a fin length in the range of about 60 nm to about 140 nm, wherein at least one of the plurality of finFET devices having a long fin is adjacent to at least one of the plurality of finFET devices having a short fin.