Source/Drain Oxide Contact Structure for Lower ON Resistance
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Solution Overview
Problem
In semiconductor devices, high ohmic contact resistance between metal contacts and semiconductor materials increases ON resistance, limiting device performance, and reducing doping concentration to lower this resistance is challenging due to high ionization energy.
Innovation Solution
A semiconductor device structure incorporating a source/drain region with specific doping regions and an oxide thin film with a conduction band energy level lower than the doping region, which directly contacts the source/drain region and the contact, reducing contact resistance by enhancing tunneling effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the semiconductor material is doped to reduce the barrier thickness between the metal contact and the semiconductor material, then the ohmic contact resistance decreases, but it becomes difficult to increase the doping concentration due to high ionization energy
Solution Approach 1:
An oxide thin film with conduction band energy level lower than the doping region is introduced as an intermediary layer between the metal contact and the semiconductor source/drain region. This mediator enables efficient charge carrier tunneling by providing a favorable energy level alignment, thereby reducing contact resistance without requiring high doping concentrations in the semiconductor material itself.
Solution Approach 2:
The energy level parameter of the interface between the metal contact and semiconductor material is modified by introducing the oxide thin film. The conduction band energy level of the oxide film is specifically selected to be lower than that of the doping region, creating an optimized energy level gradient that facilitates charge carrier transport and reduces contact resistance.
2Reliability
If the doping concentration of the semiconductor material is increased to reduce the ohmic contact resistance, then the contact resistance decreases, but the ionization energy increases making further doping difficult
Solution Approach 1:
The oxide thin film serves as an intermediary that decouples the relationship between doping concentration and contact resistance. By providing a separate tunneling path with favorable energy level alignment, the oxide layer reduces contact resistance without requiring proportional increases in semiconductor doping concentration, thereby avoiding the associated ionization energy penalties.
3Reliability
If the barrier thickness between the metal contact and the semiconductor material is reduced to decrease the ohmic contact resistance, then the contact resistance decreases, but the device structure becomes more complex
Solution Approach 1:
Rather than directly reducing the barrier thickness by complex structural modifications, an oxide thin film intermediary is introduced. This approach maintains a relatively simple overall device structure while achieving contact resistance reduction through the energy level engineering of the oxide layer, which facilitates charge carrier tunneling.
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 oxide thin film reduces contact resistance and improves semiconductor device performance by altering the energy level of the source/drain region, thereby decreasing overall ON resistance.
Implementation Method 1
reduces contact resistance by enhancing tunneling effects
Data Source
AI summary
The present disclosure provides a semiconductor device including a drift layer above the substrate, a source/drain region above the drift layer, an oxide thin film on the source/drain region, a contact on the oxide thin film, and a gate structure adjacent to source/drain region. The oxide thin film directly contacts the top surface of the source/drain region and the bottom surface of the contact. The source/drain region includes a first doping region having a first conductive type and a second doping region having a second conductive type different from the first conductive type, in which the first doping region and the second doping region forms the top surface of the source/drain region. The conduction band energy level of the oxide thin film is lower than the conduction band energy level of the first doping region.