Titanium Contact Interface for Non-Planar Transistor Source/Drain
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Solution Overview
Problem
In the fabrication of non-planar transistors, such as tri-gate and FinFETs, forming reliable source/drain contacts with small gate lengths is challenging due to the complexity of semiconductor body structures and the risk of shorts from highly mobile elements like nickel, which can diffuse and cause electrical failures.
Innovation Solution
The use of a titanium-containing contact interface layer with a discreet titanium silicide formation between the titanium-containing interface and the silicon-containing source/drain regions, eliminating the need for fully silicided nickel-containing contact layers and reducing the risk of shorts by forming low resistive contacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If nickel-containing contact layers are used to form source/drain contacts, then low resistive contacts are achieved, but highly mobile nickel elements diffuse and cause electrical shorts
Solution Approach 1:
A titanium-containing contact interface layer is introduced as an intermediary between the nickel-containing contact layer and the silicon-containing source/drain regions. This intermediate layer prevents direct contact between nickel and silicon, blocking nickel diffusion while maintaining electrical conductivity. The titanium layer acts as a diffusion barrier that mediates the interaction between the contact metal and semiconductor, eliminating the harmful shorting effect while preserving the low-resistance contact property.
Solution Approach 2:
The contact structure is segmented into multiple distinct layers: a nickel-containing contact layer, a titanium-containing contact interface layer, and a silicon-containing source/drain region. This segmentation separates the functions of each layer - the nickel layer provides electrical conductivity, the titanium layer prevents diffusion, and the silicon layer forms the semiconductor structure. By dividing the contact structure into functional segments, the patent eliminates nickel diffusion while maintaining low resistance.
2Ease of manufacture
If fully silicided nickel-containing contact layers are used, then low resistive contacts are formed, but the complexity of preventing nickel diffusion increases
Solution Approach 1:
The titanium-containing contact interface layer serves as a simple intermediary that inherently prevents nickel diffusion without requiring complex process controls. Rather than attempting to control nickel diffusion through complex silicide formation processes, the patent introduces a titanium layer that naturally acts as a diffusion barrier, simplifying the manufacturing process while reducing device complexity.
Solution Approach 2:
The titanium-containing contact interface layer is a relatively simple, thin layer that can be deposited using standard PVD or CVD techniques. This layer acts as a disposable barrier that prevents nickel diffusion without requiring complex structures or multi-step processes. The simplicity of this intermediate layer reduces both manufacturing complexity and device structure complexity.
3Productivity
If large-sized source/drain contacts are formed to enhance drive current, then transistor performance improves, but the risk of shorts from nickel diffusion increases
Solution Approach 1:
The titanium-containing contact interface layer acts as a mediator that enables large-sized source/drain contacts to be formed without increasing shorting risk. By placing this diffusion barrier between the nickel contact layer and silicon regions, the patent allows the contact area to be enlarged for higher drive current while the titanium layer continuously prevents nickel diffusion, even across larger contact areas.
Solution Approach 2:
The titanium-containing contact interface layer provides localized diffusion prevention exactly where nickel and silicon would otherwise contact. This local quality enhancement - a thin barrier layer at the critical interface - enables large overall contact sizes for high drive current while maintaining reliability through localized protection against nickel diffusion at the contact regions.
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 enhances transistor drive current performance by forming large-sized source/drain contacts without shorting risks, improving the reliability and efficiency of non-planar transistor fabrication.
Implementation Method 1
a titanium silicide interface discretely formed between the titanium-containing contact interface layer and the silicon-containing source/drain regions
Implementation Method 2
a conductive contact material deposited in the contact opening to form a source/drain contact
Data Source
AI summary
The present description relates to the field of fabricating microelectronic devices having non-planar transistors. Embodiments of the present description relate to the formation of source/drain contacts within non-planar transistors, wherein a titanium-containing contact interface may be used in the formation of the source/drain contact with a discreet titanium silicide formed between the titanium-containing interface and a silicon-containing source/drain structure.