Semiconductor Contact Barrier Using Segmented Titanium Deposition
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Solution Overview
Problem
The increasing packaging density and reduced device dimensions in semiconductor ICs pose challenges for contact fabrication, particularly in achieving conformal step coverage and preventing chemical reactions, which are not adequately addressed by existing CVD-based titanium nitride deposition methods.
Innovation Solution
A method involving physical vapor deposition (PVD) for the first titanium layer, followed by plasma-enhanced chemical vapor deposition (PECVD) for the second titanium layer, and chemical vapor deposition (CVD) for the titanium nitride barrier layer, ensuring conformal coverage and preventing overhang, while controlling temperature and gas flow to maintain stability and uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If chemical vapor deposition (CVD) is used to deposit titanium nitride barrier layer, then the barrier layer can be formed, but conformal step coverage is not achieved and overhang occurs
Solution Approach 1:
The deposition process is segmented into multiple sequential steps: first depositing a titanium layer, then forming titanium silicide through thermal reaction, and finally depositing the titanium nitride barrier layer. This segmentation allows each step to be optimized independently, achieving conformal coverage that a single CVD step cannot provide
Solution Approach 2:
The titanium layer is deposited preliminarily before the barrier layer formation. This preliminary titanium layer serves as a foundation that enables subsequent conformal barrier layer deposition by filling contact openings and providing a uniform surface, preventing the overhang problem that occurs with direct CVD barrier layer deposition
2Reliability
If CVD titanium deposition is conducted at high temperature to form titanium silicide, then titanium silicide forms immediately, but thermal stability control becomes challenging
Solution Approach 1:
The titanium layer is deposited preliminarily at controlled temperatures before thermal silicide formation. This preliminary deposition step allows precise temperature control during barrier layer formation, separating the silicide formation temperature control from the barrier layer deposition temperature control to enhance overall thermal stability
Solution Approach 2:
The process utilizes parameter changes by conducting titanium layer deposition at one temperature regime and then performing thermal annealing at a different temperature regime to form titanium silicide. This separation of temperature parameters allows optimization of each step independently, improving thermal stability control
3Productivity
If device dimension is reduced to increase packaging density, then integration level increases, but contact fabrication becomes more difficult
Solution Approach 1:
The contact structure is segmented into multiple conformal layers (titanium layer, titanium silicide layer, titanium nitride barrier layer) deposited sequentially. This segmentation enables precise control of each layer's thickness and coverage, achieving the manufacturing precision required for reduced device dimensions and higher packaging density
Solution Approach 2:
Each layer in the contact structure is deposited with specific local properties: the titanium layer provides conformal coverage, the titanium silicide layer provides controlled thermal reaction characteristics, and the titanium nitride layer provides barrier properties. This local quality optimization enables precise contact fabrication at reduced dimensions
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 provides improved step coverage, reduced contact resistance, and enhanced thermal stability of the titanium silicide layer, leading to superior performance and reliability of the contact barrier layer in semiconductor devices.
Implementation Method 1
A method involving physical vapor deposition (PVD) for the first titanium layer
Implementation Method 2
followed by plasma-enhanced chemical vapor deposition (PECVD) for the second titanium layer
Implementation Method 3
and chemical vapor deposition (CVD) for the titanium nitride barrier layer
Implementation Method 4
so that titanium silicide (TiSi2) forms immediately when Ti layer is deposited
Data Source
AI summary
A method for manufacturing a semiconductor device is disclosed. A semiconductor substrate such as bare silicon is provided, and a dielectric layer is formed over the semiconductor substrate. An opening is provided within the dielectric layer by removing a portion of the dielectric layer. A conformal first conductive layer is formed over the dielectric layer and the opening. A conformal second conductive layer is formed over the first conductive layer. A conformal barrier layer is formed over the second conductive layer.