Vertical Transistor Backside Contact for Smaller Cell Footprint
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current vertical transistor technologies consume valuable layout area with frontside contact structures adjacent to the primary cell, limiting space savings by not allowing the bottom source drain contact structures to be moved closer to the primary cell.
Innovation Solution
A self-aligned backside contact is formed vertically aligned with the fin of the primary cell, reducing the 'cell height' and design area by using a shallow trench isolation liner and spacers to isolate the source drain regions, allowing the backside contact to be directly beneath the bottom source drain region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If frontside contact structures are used adjacent to the primary cell, then electrical contact is achieved, but layout area is consumed
Solution Approach 1:
The contact structure is moved from the frontside (horizontal plane) to the backside (vertical dimension), allowing the bottom source drain contact to be positioned directly beneath the fin rather than adjacent to it, thereby reducing layout area while maintaining electrical contact functionality
Solution Approach 2:
Instead of contacting the bottom source drain region from the frontside, the contact is inverted to approach from the backside of the substrate, enabling the contact to be positioned directly below the fin and reducing the cell footprint
2Area of stationary object
If backside contact is positioned directly beneath the fin, then layout area is reduced, but alignment precision is required
Solution Approach 1:
Shallow trench isolation structures are formed beforehand to define the precise location where the backside contact will be formed, ensuring accurate alignment with the bottom source drain region before the contact fabrication process begins
Solution Approach 2:
Shallow trench isolation liners and spacers are introduced as intermediary structures that automatically define the contact position through self-alignment mechanisms, eliminating the need for additional alignment steps and ensuring precise positioning of the backside contact
Data Source
AI summary
A semiconductor structure including a fin of a vertical transistor structure, a top source drain region on a top side of the fin, a bottom source drain region on a bottom side of the fin, and a backside contact below and contacting the bottom source drain region.