Metal Sulfide ALD Interface for High-Mobility Channels
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Solution Overview
Problem
High-mobility semiconductor channel materials like Ge and InGaAs face issues with interface states that pin the Fermi energy, leading to deteriorated device performance, and existing interface layers fail to prevent oxidation, current leakage, and charge trapping.
Innovation Solution
A method for forming metal sulfide thin films using atomic layer deposition (ALD) involving cyclical processes with vapor-phase metal and sulfur reactants, where the metal reactant includes metals like Mg, Ca, and lanthanides, and sulfur precursors like H2S, to create a protective interface layer between the high-mobility channel and dielectric layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If high-mobility substrate materials like Ge and group III-V materials are used, then electron and hole mobility are improved, but interface states increase and Fermi energy pinning occurs
Solution Approach 1:
A metal sulfide interface layer is introduced as an intermediary between the high-mobility semiconductor channel and the dielectric layer. This intermediate layer passivates the interface states on the semiconductor surface, reducing Fermi energy pinning while maintaining the high carrier mobility benefits of the underlying material.
Solution Approach 2:
The patent employs composite material structures combining metal sulfide compounds (such as MgS, CaS, SrS, BaS) with high-k dielectric materials. This composite approach leverages the high mobility characteristics of the semiconductor channel while the metal sulfide layer provides interface state passivation and enables integration with dielectric layers.
2Ease of manufacture
If conventional interface layers are used, then integration with dielectric layers is achieved, but oxidation of the underlying channel and current leakage occur
Solution Approach 1:
Metal sulfide compounds are employed to create a chemically inert interface environment that protects the underlying high-mobility semiconductor channel from oxidation. The metal sulfide layer acts as a barrier, preventing reactive species from reaching and oxidizing the sensitive channel material while enabling subsequent dielectric layer formation.
3Ease of manufacture
If known interface layers are used, then dielectric integration is enabled, but up diffusion of group III-V elements or Ge into the gate dielectric occurs
Solution Approach 1:
The metal sulfide interface layer serves as a diffusion barrier intermediary between the semiconductor channel and dielectric layer. It prevents up-diffusion of group III-V elements or Ge into the gate dielectric while allowing the dielectric layer to be successfully formed and integrated with the underlying structure.
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 metal sulfide thin films effectively reduce interface states, prevent oxidation, and minimize current leakage and charge trapping, enhancing the performance of electronic devices by forming a stable and efficient interface between high-mobility channels and dielectric layers.
Implementation Method 1
a metal sulfide thin film is deposited on a substrate in a reaction space in a cyclical process where at least one cycle includes alternately and sequentially contacting the substrate with a first vapor-phase metal reactant and a second vapor-phase sulfur reactant
Implementation Method 2
the metal sulfide film is formed using a metal reactant having at least one cyclopentadienyl (Cp) ligand
Data Source
AI summary
In some aspects, methods of forming a metal sulfide thin film are provided. According to some methods, a metal sulfide thin film is deposited on a substrate in a reaction space in a cyclical process where at least one cycle includes alternately and sequentially contacting the substrate with a first vapor-phase metal reactant and a second vapor-phase sulfur reactant. In some aspects, methods of forming a three-dimensional architecture on a substrate surface are provided. In some embodiments, the method includes forming a metal sulfide thin film on the substrate surface and forming a capping layer over the metal sulfide thin film. The substrate surface may comprise a high-mobility channel.