TiSiN Deposition via Pulsed CVD for Diffusion Barriers
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Solution Overview
Problem
Titanium nitride (TiN) diffusion barriers in semiconductor devices allow metal diffusion due to their crystal structure, necessitating the development of more effective materials like titanium silicon nitride (TiSiN) with improved deposition processes.
Innovation Solution
A method involving cyclical chemical vapor deposition (CVD) where a TiN layer is formed, exposed to a nitrogen-containing reducing agent, and then to a silicon precursor, facilitating high silicon incorporation and achieving high deposition rates and uniformity, with the ability to tailor film properties like resistivity and grain size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If TiN is used as a diffusion barrier, then it provides basic metal diffusion protection, but metals can still diffuse along grain boundaries reducing barrier effectiveness
Solution Approach 1:
The patent changes the material composition parameters by incorporating silicon into TiN to form TiSiN, and controls the crystal structure parameters through deposition conditions to achieve an amorphous or nano-crystalline structure with very small grains, thereby eliminating grain boundary diffusion paths and improving barrier effectiveness
Solution Approach 2:
The patent creates a composite material TiSiN by combining titanium, silicon, and nitrogen elements, where silicon incorporation modifies the crystal structure to reduce grain size and eliminate continuous grain boundaries, thereby enhancing the diffusion barrier properties beyond what TiN alone can provide
2Reliability
If more amorphous or nano-crystalline materials are used to reduce grain boundaries, then diffusion barrier effectiveness improves, but deposition process complexity increases
Solution Approach 1:
The patent employs periodic pulsed deposition cycles with alternating gas flows (TiCl4 and NH3 pulses separated by N2 purges) to control the deposition process, enabling precise control over film composition and structure while managing process complexity through rhythmic, repeatable steps
Solution Approach 2:
The patent performs preliminary actions by carefully controlling the deposition parameters and gas flow sequences during the CVD process to directly form the desired amorphous or nano-crystalline structure, avoiding the need for subsequent heat treatment or structural modification steps
3Productivity
If pulsed deposition cycles are used to control film properties, then deposition rate and uniformity improve, but process time increases
Solution Approach 1:
The patent maintains continuity of useful action by using overlapping gas flows and minimizing purge times between deposition pulses, ensuring that the chamber remains in a reactive state as much as possible and reducing idle time while maintaining control over film properties
Solution Approach 2:
The patent dynamically adjusts deposition parameters such as gas flow rates, pulse durations, and chamber pressure during the deposition process to optimize both deposition rate and film uniformity, allowing real-time control to balance productivity and time requirements
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 high silicon incorporation into TiN films, resulting in effective diffusion barriers with tailored properties, including excellent oxidation resistance and adjustable resistivity and grain size.
Implementation Method 1
Titanium silicon nitride is deposited on the substrates by performing a plurality of deposition cycles. Each deposition cycle comprises the following steps: A) flowing TiCl4 into the chamber while simultaneously flowing NH3 into the chamber
Implementation Method 2
D) flowing a silicon precursor into the chamber
Data Source
AI summary
Titanium silicon nitride (TiSiN) films are formed in a cyclic chemical vapor deposition process. In some embodiments, the TiSiN films are formed in a batch reactor using TiCl4, NH3 and SiH4 as precursors. Substrates are provided in a deposition chamber of the batch reactor. In each deposition cycle, a TiN layer is formed on the substrates by flowing TiCl4 into the deposition chamber simultaneously with NH3. The deposition chamber is subsequently flushed with NH3. to prepare the TiN layer for silicon incorporation. SiH4 is subsequently flowed into the deposition chamber. Silicon from the SiH4 is incorporated into the TiN layers to form TiSiN. Exposing the TiN layers to NH3 before the silicon precursor has been found to facilitate efficient silicon incorporation into the TiN layers to form TiSiN.