Self-Aligned Diffusion Barrier for III-V MOSFETs
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Solution Overview
Problem
Forming self-aligned, low-resistance diffusion barriers for metallic contacts on III-V materials in MOSFETs is challenging due to unwanted alloying with titanium at low temperatures, restricting the thermal budget and hindering the manufacture of high-performance devices.
Innovation Solution
A method involving the formation of a raised source with Group III-V material, an interfacial layer of silicon or germanium, and a metal layer of transition metal, where the transition metal bonds with silicon or germanium to create a diffusion barrier, allowing for low resistivity and preventing interdiffusion between metal contacts and III-V structures, while maintaining adequate thermal budgets for BEOL processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If titanium is deposited on InGaAs to form a diffusion barrier, then the barrier prevents interdiffusion between metal contacts and III-V structures, but the thermal budget for BEOL processing is severely restricted due to alloying at temperatures as low as 400°C
Solution Approach 1:
A silicon interfacial layer is introduced between the titanium diffusion barrier and the InGaAs raised source. This intermediary layer prevents direct contact between titanium and arsenic, eliminating the formation of high-resistivity titanium arsenide compounds while maintaining the diffusion barrier's interdiffusion prevention capability. The silicon layer acts as a protective mediator that allows subsequent BEOL processing at higher temperatures without triggering unwanted alloying reactions.
2Object-generated harmful factors
If the thermal budget is restricted to avoid titanium-arsenic alloying, then unwanted alloy formation is prevented, but the manufacture of high-performance devices is hindered
Solution Approach 1:
The silicon interfacial layer serves as a protective barrier that eliminates the harmful titanium-arsenic alloying reaction. By preventing direct interaction between titanium and arsenic atoms, the silicon layer removes the constraint on thermal budget, thereby enabling standard high-performance device manufacturing processes without the risk of unwanted alloy formation.
3Reliability
If titanium nitride is used as a contact diffusion barrier for silicon-based technologies, then the barrier provides effective diffusion prevention, but it forms high-resistivity compounds when deposited on InGaAs
Solution Approach 1:
The silicon interfacial layer prevents titanium from directly reacting with arsenic in the InGaAs raised source. This intermediary protection ensures that the titanium diffusion barrier maintains its low-resistivity properties by preventing the formation of high-resistivity titanium arsenide compounds, while still providing effective diffusion barrier functionality.
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 solution provides diffusion barriers with low thin film resistivities and prevents interdiffusion, enabling high-performance MOSFETs with sufficient thermal budgets for BEOL processing, overcoming the limitations of existing methods.
Implementation Method 1
a diffusion barrier is formed at least partially on the raised source with the diffusion barrier layer comprising transition metal from the metal layer bonded to silicon or germanium from the interfacial layer
Data Source
AI summary
A method is presented for forming a diffusion barrier in a field effect transistor with a source. A raised source is formed at least partially on the source with the raised source including III-V material. An interfacial layer is formed at least partially on the raised source with the interfacial layer including silicon or germanium. A metal layer is formed at least partially on the interfacial layer with the metal layer including transition metal. The diffusion barrier is formed at least partially on the raised source with the diffusion barrier layer including transition metal from the metal layer bonded to silicon or germanium from the interfacial layer. Similar processing forms a corresponding diffusion barrier on a raised drain.