2D Semiconductor Contacts With Alloy Interface for Low Resistance
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Solution Overview
Problem
The performance of single 2D transition metal dichalcogenide materials in devices is limited by high electrical resistance at the source/drain regions and electrode contacts, which hinders their application in semiconductor devices.
Innovation Solution
A method is developed to form a metal-reactive metal alloy interface between the semiconductor material and electrical contacts, eliminating the van der Waals gap and reducing contact resistance by using a hydrogen plasma to replace chalcogen in the metal dichalcogenide layer with hydrogen, followed by a reactive metal to form a seamless alloy bond, and a protective less reactive metal layer to prevent oxidation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single 2D transition metal dichalcogenide material is used, then device simplicity is maintained, but electrical resistance at source/drain regions and electrode contacts becomes excessively high
Solution Approach 1:
The patent applies composite materials by combining multiple metal layers (reactive metal layer and protective metal layer) with the 2D transition metal dichalcogenide material. The reactive metal layer forms an alloy interface to reduce contact resistance, while the protective metal layer prevents oxidation, creating a composite structure that simultaneously maintains device simplicity and improves electrical performance.
Solution Approach 2:
The patent applies local quality by modifying only the contact regions at source/drain areas with multi-layer metal structures, while leaving the channel region as pure 2D material. This localized modification reduces contact resistance at critical interfaces without changing the overall device simplicity or affecting the intrinsic properties of the 2D semiconductor material.
2Reliability
If a metal layer is added to reduce contact resistance, then electrical performance improves, but device complexity increases
Solution Approach 1:
The patent uses composite materials with a specific two-layer metal structure (reactive metal + protective metal) that provides both low contact resistance and oxidation protection. This composite approach achieves superior electrical performance while keeping the additional structure minimal and manageable, rather than using complex multi-layer or graded structures.
3Reliability
If a reactive metal layer is used to form alloy bond, then contact resistance decreases, but oxidation resistance decreases
Solution Approach 1:
The patent uses an intermediary approach by introducing a protective metal layer as a mediator between the reactive metal layer and the environment. The reactive metal layer forms the low-resistance alloy bond with the 2D material, while the protective metal layer acts as an intermediary barrier that prevents oxidation of the reactive metal, allowing both functions to coexist.
Solution Approach 2:
The patent applies composite materials by creating a bi-layer metal structure where the reactive metal layer provides low contact resistance through alloy formation, and the protective metal layer provides oxidation resistance. This composite structure resolves the contradiction by combining materials with complementary properties in a functional sequence.
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 contact resistance and enhances current density through the channel, improving the performance of 2D semiconductor devices by eliminating defects and Fermi level pinning effects, thereby increasing drain current and field-effect mobility.
Implementation Method 1
applying a plasma to a portion of a metal dichalcogenide film
Implementation Method 2
the chalcogen is replaced with hydrogen to form a metal chalcogenide hydride
Implementation Method 3
the hydrogen is replaced with a second metal to form a metal-reactive metal alloy interface
Implementation Method 4
a protective less reactive metal layer is deposited over the reactive metal layer to prevent oxidation
Data Source
AI summary
A method of fabricating a semiconductor device includes applying a plasma to a portion of a metal dichalcogenide film. The metal dichalcogenide film includes a first metal and a chalcogen selected from the group consisting of S, Se, Te, and combinations thereof. A metal layer including a second metal is formed over the portion of the metal dichalcogenide film after applying the plasma.