TiN Thin Film Deposition with Smoothness and Step Coverage
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Solution Overview
Problem
There is a need for atomic layer deposition methods that can form titanium nitride (TiN) films with superior surface smoothness and step coverage, while maintaining or exceeding the electrical and physical properties of TiN films formed by physical vapor deposition (PVD) and chemical vapor deposition (CVD).
Innovation Solution
A cyclical vapor deposition process involving alternating exposures to titanium (Ti) and nitrogen (N) precursors at different pressures, where the first portion of the TiN film is grown at lower pressures to promote layer-by-layer growth, and the second portion is grown at higher pressures to enhance conformality and step coverage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If atomic layer deposition (ALD) is used to form conformal TiN films, then conformality is improved, but surface roughness and electrical conductivity deteriorate
Solution Approach 1:
The TiN film deposition process is segmented into multiple ALD cycles with varying precursor exposure pressures. Initial cycles use lower pressures to establish a smooth foundation layer, while subsequent cycles use higher pressures to build conformal coverage, thereby resolving the contradiction between surface smoothness and conformality
Solution Approach 2:
The precursor exposure pressure parameter is dynamically changed during the deposition process. By adjusting pressure conditions across different deposition stages, the method achieves both low surface roughness in early cycles and high conformality in later cycles, overcoming the limitations of constant-pressure ALD
2Shape
If atomic layer deposition (ALD) is used to form conformal TiN films, then conformality is improved, but electrical conductivity deteriorates
Solution Approach 1:
The deposition process is divided into stages where early low-pressure cycles create a dense, low-resistance foundation that improves overall electrical conductivity, while later high-pressure cycles provide conformal coverage, thus achieving both high conductivity and conformality simultaneously
Solution Approach 2:
By changing precursor exposure pressures during deposition, the method optimizes film density and crystalline structure in early cycles to enhance electrical conductivity, while maintaining conformal morphology through pressure adjustments in subsequent cycles
3Reliability
If PVD or CVD methods are used to form TiN films, then electrical conductivity is improved, but conformality deteriorates
Solution Approach 1:
The patent replaces physical vapor deposition (PVD) and chemical vapor deposition (CVD) mechanical processes with atomic layer deposition (ALD), which uses controlled precursor exposure and surface reactions to achieve conformal deposition while maintaining good electrical properties through optimized cycling conditions
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 a combination of high conformality, low surface roughness, and improved electrical conductivity, surpassing the properties of TiN films formed by traditional PVD and CVD methods.
Implementation Method 1
forming on a semiconductor substrate a first portion of the thin film by exposing the semiconductor substrate to one or more first cyclical vapor deposition cycles
Implementation Method 2
forming on the first portion of the thin film a second portion of the thin film by exposing the semiconductor substrate to one or more second cyclical vapor deposition cycles
Data Source
AI summary
The disclosed technology generally relates to forming a thin film comprising titanium nitride (TiN), and more particularly to forming by a cyclical vapor deposition process the thin film comprising (TiN). In one aspect, a method of forming a thin film comprising TiN comprises exposing a semiconductor substrate to one or more first cyclical vapor deposition cycles each comprising an exposure to a first Ti precursor and an exposure to a first N precursor to form a first portion of the thin film and exposing the semiconductor substrate to one or more second cyclical vapor deposition cycles each comprising an exposure to a second Ti precursor and an exposure to a second N precursor to form a second portion of the thin film, wherein exposures to one or both of the first Ti precursor and the first N precursor during the one or more first cyclical vapor deposition cycles are at different pressures relative to corresponding exposures to one or both of the second Ti precursor and the second N precursor during the one or more second cyclical vapor deposition cycles. Aspects are also directed to semiconductor structures incorporating the thin film and method of forming the same.