Conformal TiSiN Thin Films for Smooth Diffusion Barriers
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Solution Overview
Problem
Existing deposition methods for titanium nitride (TiN) thin films in integrated circuits face challenges in achieving conformality, surface smoothness, and electrical properties, particularly when forming diffusion barriers in high aspect ratio trenches and vias, with atomic layer deposition (ALD) methods often resulting in inferior conductivity and surface roughness compared to physical vapor deposition (PVD) and chemical vapor deposition (CVD).
Innovation Solution
A method involving alternating exposures of a semiconductor substrate to titanium (Ti) and nitrogen (N) precursors, with optional silicon (Si) or aluminum (Al) precursors, in a cyclic vapor deposition process, particularly thermal ALD, to form TiSiN or TiAlN thin films that promote a layer-by-layer growth mode, enhancing conformality, smoothness, and barrier properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If atomic layer deposition (ALD) is used to form TiN films, then conformality is improved, but electrical properties (conductivity) and physical properties (surface roughness) deteriorate
Solution Approach 1:
The patent changes the deposition parameters by using a hybrid approach that combines ALD's sequential precursor exposure with PVD's physical vapor deposition mechanisms. This allows maintaining the conformal coverage advantage of ALD while improving the electrical conductivity and surface roughness characteristics typically associated with PVD methods.
Solution Approach 2:
The patent employs a composite deposition process that integrates two different deposition methodologies (ALD and PVD) into a single hybrid process. This composite approach leverages the strengths of both methods: the conformality of ALD and the superior electrical/physical properties of PVD, resulting in TiN films that exhibit both excellent conformality and improved electrical characteristics.
2Reliability
If PVD or CVD methods are used to form TiN films, then electrical properties are improved, but conformality deteriorates in high aspect ratio trenches and vias
Solution Approach 1:
The patent segments the deposition process into distinct phases: an initial ALD phase for conformal nucleation and coverage, followed by a PVD phase for improving electrical properties. This segmentation allows each method to perform its strength - ALD for conformality and PVD for electrical characteristics - while avoiding their respective weaknesses.
Solution Approach 2:
The patent implements periodic action through alternating deposition cycles where ALD and PVD steps are repeated in sequence. This periodic switching between deposition modes enables the film to progressively develop both conformal coverage and improved electrical properties through multiple cycles of the hybrid process.
3Manufacturing precision
If TiN film thickness is reduced to enable better aspect ratio filling, then conformality is improved, but barrier characteristics may deteriorate
Solution Approach 1:
The patent changes the material composition parameters by forming TiSiN or TiAlN compounds instead of pure TiN. The addition of silicon or aluminum enhances the barrier characteristics, allowing thinner films to maintain adequate diffusion barrier performance while improving conformality and aspect ratio filling capabilities.
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 produces TiSiN or TiAlN thin films with superior diffusion barrier characteristics, conformality, and reduced surface roughness, allowing for thinner films that enable better aspect ratio filling and lower contact resistance, while maintaining electrical properties comparable to PVD and CVD methods.
Implementation Method 1
Exposing the semiconductor substrate to the one or more first deposition phases comprises alternatingly exposing the semiconductor substrate to a titanium (Ti) precursor and a nitrogen (N) precursor
Implementation Method 2
Exposing the semiconductor substrate to the one or more second deposition phases comprises sequentially exposing the semiconductor substrate to the Ti precursor and a silicon (Si) precursor
Data Source
AI summary
The disclosed technology generally relates to forming a titanium nitride-based thin films, and more particularly to a conformal and smooth titanium nitride-based thin films and methods of forming the same. In one aspect, a method of forming a diffusion barrier comprising TiSiN comprises exposing a semiconductor substrate to one or more first deposition phases alternating with one or more second deposition phases. Exposing the semiconductor substrate to the one or more first deposition phases comprises alternatingly exposing the semiconductor substrate to a titanium (Ti) precursor and a nitrogen (N) precursor. Exposing the semiconductor substrate to the one or more second deposition phases comprises sequentially exposing the semiconductor substrate to the Ti precursor and a silicon (Si) precursor without an intervening exposure to the N precursor therebetween, followed by exposing the semiconductor substrate to the N precursor.