Nanostructure Transistor Source/Drain Cavity Contact for Lower Resistance
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Solution Overview
Problem
Nanostructure transistors face fabrication challenges that lead to increased resistance and reduced performance due to decreased contact surface area between the source/drain region and contact, causing current crowding and increased contact resistance.
Innovation Solution
A hollow cavity is formed in the source/drain region, filled with a metal core and recessed within the source/drain region to increase contact surface area, reducing contact resistance and enhancing current flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the contact surface area between source/drain region and contact is decreased, then device size is reduced, but contact resistance increases
Solution Approach 1:
The patent transitions from a planar contact interface to a three-dimensional recessed contact structure. The contact is formed in a cavity that extends into the source/drain region, creating vertical and lateral contact surfaces. This dimensional change allows the contact to access the source/drain region from multiple directions (top, sidewalls), significantly increasing the effective contact area without increasing the device footprint.
Solution Approach 2:
The contact structure is nested within the source/drain region by forming a cavity and filling it with conductive material. The contact is recessed into the source/drain region, creating a nested configuration where the contact resides within the source/drain structure. This nesting approach maximizes the contact interface area within the available vertical space, improving electrical connection without expanding the horizontal device dimensions.
2Use of energy by moving object
If current path efficiency is improved, then power efficiency increases, but device complexity increases
Solution Approach 1:
The cavity in which the contact is formed is created during the source/drain region formation process, before the contact deposition step. This preliminary creation of the cavity structure allows subsequent contact materials to be deposited directly into the pre-formed recess, establishing an efficient current path early in the fabrication sequence. The preliminary action of cavity formation enables better current flow without requiring complex post-processing steps.
Data Source
AI summary
A source/drain region is formed for a nanostructure transistor of a semiconductor device such that a hollow cavity extends into the source/drain region from a top of the source/drain region into the source/drain region. In some implementations, the cavity extends fully through the depth of the source/drain region. The cavity results from partial epitaxial growth of one or more epitaxial layers of the source/drain region. A metal core of the source/drain region is formed in the cavity and electrically coupled to a source/drain contact of a nanostructure transistor such that electrically conductive material is recessed within the source/drain region. This provides a greater amount of surface area for the source/drain contact to contact the source/drain region than if the source/drain region were fully filled in with epitaxially-grown semiconductor material.