Selective Titanium Silicide Formation Using TiCl4
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Solution Overview
Problem
Conventional titanium silicide formation methods are non-selective, consume silicon, and are not compatible with advanced node contact structure integration schemes due to high temperatures and long processing times, particularly below 800°C.
Innovation Solution
A method involving heating a substrate to 400-500°C, exposing it to silicon and titanium precursors, including TiCl4, within a pressure range of 10-100 torr, to form a titanium silicide layer selectively on silicon or germanium substrates, allowing for efficient nucleation and reduced resistivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional CVD methods are used for titanium silicide formation, then titanium silicide layer can be formed, but the process is not selective for temperatures below 800°C and consumes silicon
Solution Approach 1:
The patent changes the temperature parameter from conventional high temperatures (>800°C) to a lower range (400-500°C), and modifies the chemical environment by introducing specific precursors (TiCl4 and silicon-containing precursor) to achieve selective titanium silicide formation without silicon consumption. This parameter change resolves the contradiction by enabling selectivity and preventing silicon loss simultaneously.
2Reliability
If post deposition anneal is used to form low resistivity phase silicides, then low resistivity is achieved, but the process is time consuming and not compatible with thermal budgets for advanced node contact structure integration
Solution Approach 1:
The patent performs preliminary action by forming the titanium silicide layer with desired low resistivity properties directly during the deposition process itself, rather than requiring a subsequent post-deposition anneal step. The concurrent exposure to TiCl4 and silicon precursor at controlled temperatures creates the low resistivity phase in-situ, eliminating the need for additional time-consuming annealing steps and making the process compatible with advanced node thermal budgets.
3Manufacturing precision
If conventional titanium silicide formation is used, then silicide layer can be formed, but conformity is less than desirable
Solution Approach 1:
The patent utilizes vapor-phase delivery of precursors (TiCl4 and silicon-containing precursor) through the process chamber, creating a uniform gaseous environment that ensures consistent deposition across the substrate surface. This pneumatic approach to material delivery improves conformity by enabling uniform precursor distribution and reaction conditions, achieving desirable manufacturing precision while maintaining reasonable process complexity.
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 method achieves selective titanium silicide formation with desirable contact resistance and compatibility with advanced contact integration schemes, reducing thermal budget and processing time while being selective against oxides and nitrides.
Implementation Method 1
heating a substrate in a process chamber to a temperature within a range of about 400 degrees Celsius to about 500 degrees Celsius
Implementation Method 2
exposing the substrate to a silicon precursor and titanium precursor concurrently while maintaining a pressure within the process chamber between about 10 torr and about 100 torr, the titanium precursor comprising TiCl4; and forming a titanium silicide layer on the substrate
Data Source
AI summary
The present disclosure generally relates to methods of selectively forming titanium silicides on substrates. The methods are generally utilized in conjunction with contact structure integration schemes. In one embodiment, a titanium silicide material is selectively formed on a substrate as an interfacial layer on a source/drain region. The titanium silicide layer may be formed at a temperature within range of about 400 degrees Celsius to about 500 degrees Celsius.