Conductive Carbon Contact Layer for Low-Resistance Source/Drain Junctions
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Solution Overview
Problem
As chip sizes scale down, critical dimension (CD) of contacts decreases, leading to higher contact resistance between source/drain regions and metal contacts, which is a critical issue in advanced semiconductor technologies.
Innovation Solution
The introduction of a conductive carbon layer, such as a graphene layer, and/or a dipole layer between the metal contact and the source/drain portion at a metal-semiconductor junction to reduce contact resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If chip size is scaled down, then device integration is improved, but contact resistance increases
Solution Approach 1:
A dipole layer is introduced as an intermediary between the metal contact and the source/drain region. This dipole layer modifies the band alignment and reduces the Schottky barrier height, thereby lowering contact resistance despite the reduced contact area due to scaling. The dipole layer acts as a mediator that facilitates charge carrier transport across the metal-semiconductor interface.
Solution Approach 2:
The invention changes the electrical parameters at the metal-semiconductor interface by introducing the dipole layer, which alters the work function and band alignment. This parameter change reduces the Schottky barrier height and contact resistance, enabling low-resistance contacts even at scaled-down dimensions where contact area is reduced.
2Area of stationary object
If contact area is reduced, then device scaling is improved, but contact resistance increases
Solution Approach 1:
Instead of relying on increased contact area to reduce resistance, the invention changes the electrical parameters at the interface by introducing a dipole layer. This modifies the band alignment and reduces the Schottky barrier height, enabling low contact resistance despite reduced contact area. The approach transitions from geometric scaling to electrical parameter optimization.
Solution Approach 2:
The dipole layer serves as an intermediary that facilitates charge transport across the metal-semiconductor interface. By modifying the local electrical environment and band structure at the interface, it compensates for the reduced contact area and maintains low contact resistance.
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
The use of conductive carbon and dipole layers effectively reduces the source/drain contact resistivity by alleviating Fermi level pinning and modifying the band edges, thereby lowering the Schottky barrier height and contact resistance.
Implementation Method 1
modifying the band edges, thereby lowering the Schottky barrier height and contact resistance
Implementation Method 2
alleviating Fermi level pinning and modifying the band edges
Data Source
AI summary
A semiconductor structure includes a semiconductor substrate, a first source/drain portion, a second source/drain portion, a first metal contact, a second metal contact and a first conductive carbon layer. The first and second source/drain portions are formed over the semiconductor substrate, and are spaced apart from each other. The first source/drain portion has a conductivity type different from that of the second source/drain portion. The first and second metal contacts are respectively formed on the first and second source/drain portions. The first conductive carbon layer is formed between the first source/drain portion and the first metal contact.