Delta Doped Transistor Contacts for Low Interface Resistance
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Solution Overview
Problem
Current industry deposition techniques find it difficult to achieve high n-type heavy doping in III-V field effect transistors, leading to increased interface resistance between source/drain regions and metal contacts, which affects the performance of semiconductor devices.
Innovation Solution
The use of delta doped sheet layers with high doping concentrations and an insulating layer between the source/drain regions and metal contacts to reduce interface resistance, where delta doped sheet layers are formed during the source/drain region formation and an insulating layer is inserted to decrease metal-induced gap state density and Fermi unpinning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If current industry deposition techniques are used to form source/drain regions, then the manufacturing process is simple, but high n-type heavy doping cannot be achieved leading to high interface resistance
Solution Approach 1:
The source/drain region is segmented into multiple doping zones with different doping concentrations. A first doping zone with lower n-type doping concentration is formed, and a second doping zone with higher n-type doping concentration is formed within or adjacent to the first zone. This segmentation allows achieving heavy doping in specific regions without requiring extremely complex overall doping processes.
Solution Approach 2:
Different regions of the source/drain structure are given different doping concentrations tailored to their specific functional requirements. The region adjacent to the metal contact receives higher n-type doping concentration to reduce interface resistance, while other regions maintain appropriate doping levels for their respective functions. This local optimization resolves the contradiction by applying heavy doping only where necessary.
2Reliability
If high n-type heavy doping is achieved in source/drain regions, then interface resistance decreases, but the doping process becomes more difficult with current techniques
Solution Approach 1:
A lower n-type doping concentration is applied first to form a base doping zone in the source/drain region. Subsequently, a second doping process applies higher n-type doping concentration to create a heavily doped zone in the desired location. This preliminary action allows the heavy doping to be achieved through a staged process rather than requiring a single extremely complex doping step.
Solution Approach 2:
The doping concentration parameter is varied across different zones and stages of the process. The first doping zone uses one doping concentration level, while the second doping zone uses a higher doping concentration level. This parameter change approach enables achieving heavy doping where needed while maintaining process feasibility through controlled variation of doping parameters.
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 effectively reduces contact resistance by promoting efficient carrier transport and lowering the Schottky barrier height, thereby improving the performance of semiconductor devices.
Implementation Method 1
promoting efficient carrier transport and lowering the Schottky barrier height
Implementation Method 2
lowering the Schottky barrier height
Implementation Method 3
reduce interface resistance between source/drain regions and metal contacts
Implementation Method 4
decrease metal-induced gap state density and Fermi unpinning
Data Source
AI summary
The present disclosure relates to a semiconductor device having a delta doped sheet layer within a transistor's source/drain region to reduce contact resistance, and an associated method. In some embodiments, a dielectric layer is disposed over the transistor. A trench is disposed through the dielectric layer to the source/drain region and a conductive contact is disposed in the trench. The source/drain region comprises a delta doped sheet layer with a doping concentration that is higher than rest of the source/drain region.