Vertical FinFET Channel Width Control via Sacrificial Oxidation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
As device dimensions decrease, forming consistent components and electrical contacts in Field Effect Transistors (FETs) becomes increasingly difficult, particularly in FinFETs where channel width variation leads to scaling issues.
Innovation Solution
A method is developed to form vertical FinFETs with consistent channel width by creating vertical fins with a tapered profile, oxidizing them to form a straight channel portion, and removing the tapered portions to achieve facetted bottom source/drain structures, using sacrificial oxidation and selective etching to control fin width and crystal orientation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If vertical fins are formed with traditional methods, then device scaling is achieved, but channel width variation increases leading to inconsistent fin width
Solution Approach 1:
A sacrificial oxide layer is formed on the vertical fin surface before the main fabrication steps. This preliminary oxidation creates a template that guides subsequent etching to form straight sidewalls, preventing the channel width variation that normally occurs during device scaling.
Solution Approach 2:
The sacrificial oxide layer acts as an intermediary structure between the fin formation and the final device structure. It provides a temporary framework that ensures consistent channel width during processing, and is later removed to reveal the precisely-formed fins with straight sidewalls.
2Shape
If tapered profile fins are formed, then facetted bottom source/drain structures are achieved, but channel width consistency is compromised
Solution Approach 1:
The fin structure is segmented into distinct regions: a tapered lower portion for the facetted bottom source/drain, a straight channel portion for consistent current flow, and a tapered upper portion. This segmentation allows each region to serve its specific function without compromising the others.
Solution Approach 2:
Different portions of the fin have different geometries tailored to their specific functions. The lower portion is tapered to create facetted structures for optimal source/drain contact, while the middle channel portion maintains straight sidewalls for consistent width, and the upper portion is tapered for gate alignment. Each local region has the quality needed for its specific purpose.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach results in improved FinFET device performance by reducing threshold voltage variation and enabling the formation of consistent fin width, enhancing the reliability and efficiency of FinFETs in applications like CMOS transistors and memory devices.
Implementation Method 1
oxidizing the one or more vertical fin(s) to form an oxide by consuming at least a portion of the vertical fin material
Data Source
AI summary
A method of forming a vertical fin field effect transistor having a consistent channel width, including forming one or more vertical fin(s) on the substrate, wherein the one or more vertical fin(s) have a tapered profile, oxidizing the one or more vertical fin(s) to form an oxide by consuming at least a portion of the vertical fin material, and removing the oxide from the one or more vertical fin(s), wherein the one or more vertical fin(s) include a tapered upper portion, a tapered lower portion and a straight channel portion there between.