Interfacial Atomic Monolayers for Low-Resistance Group IV Contacts
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Solution Overview
Problem
As transistors shrink to nanometer scales, the unwanted resistance at metal-semiconductor junctions increases, limiting the performance of devices like ultra-thin body FETs and FinFETs, due to high Schottky barriers and reduced dopant activation, with existing methods like high doping concentrations becoming insufficient.
Innovation Solution
Interposing a monolayer of group V or group III atoms, or a bi-layer of these atoms, at the interface between the metal and semiconductor to reduce the Schottky barrier and specific contact resistance, allowing for lower resistance metal-semiconductor contacts without the need for doping or silicidation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If transistor dimensions are reduced to nanometer scale, then device integration density is improved, but contact resistance increases due to enhanced Schottky barrier effects and reduced dopant activation
Solution Approach 1:
The patent applies local quality by creating a specialized interfacial layer with distinct chemical and electrical properties only at the metal-semiconductor contact region. The group V atomic layer is selectively positioned at the interface, providing localized modification of barrier characteristics without altering the bulk semiconductor properties or requiring widespread doping changes throughout the device structure.
Solution Approach 2:
The interfacial group V layer serves as a mediator that decouples the relationship between metal work function and semiconductor electron affinity, allowing nanoscale transistors to achieve low contact resistance through interface engineering rather than bulk doping, thereby maintaining performance at reduced dimensions.
2Reliability
If metal silicide contacts are used, then contact resistance is reduced through doping, but manufacturing complexity increases due to additional silicidation process steps
Solution Approach 1:
The patent extracts the barrier-modifying function from the bulk doping process and concentrates it into a thin interfacial layer of group V atoms. This eliminates the need for complex silicidation sequences and multiple doping steps, simplifying the manufacturing process while achieving the same electrical performance through a more direct approach.
Solution Approach 2:
The invention changes the fundamental parameter approach from modifying bulk doping concentration to modifying interfacial atomic composition. By controlling the presence and arrangement of group V atoms at the interface, the Schottky barrier characteristics are tuned without requiring the complex thermal and chemical processes associated with silicide formation and dopant activation.
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 significantly reduces the Schottky barrier and specific contact resistance, enabling lower resistance electrodes in semiconductor devices and improving the performance of nanoscale transistors by eliminating or minimizing the barrier between the metal and semiconductor, thus enhancing electrical conductivity.
Implementation Method 1
Interposing a monolayer of group V or group III atoms, or a bi-layer of these atoms, at the interface between the metal and semiconductor to reduce the Schottky barrier and specific contact resistance
Data Source
AI summary
Techniques for reducing the specific contact resistance of metal-semiconductor (group IV) junctions by interposing a monolayer of group V or group III atoms at the interface between the metal and the semiconductor, or interposing a bi-layer made of one monolayer of each, or interposing multiple such bi-layers. The resulting low specific resistance metal-group IV semiconductor junctions find application as a low resistance electrode in semiconductor devices including electronic devices (e.g., transistors, diodes, etc.) and optoelectronic devices (e.g., lasers, solar cells, photodetectors, etc.) and/or as a metal source and/or drain region (or a portion thereof) in a field effect transistor (FET). The monolayers of group III and group V atoms are predominantly ordered layers of atoms formed on the surface of the group IV semiconductor and chemically bonded to the surface atoms of the group IV semiconductor.