SiC Ohmic Contact Formation Using Laser-Activated Dopant Regions
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Solution Overview
Problem
The existing methods for manufacturing SiC electronic devices require multiple thermal-annealing steps for doping activation and ohmic contact formation, which can lead to misalignment issues and result in devices with high leakage current or non-functional Schottky contacts.
Innovation Solution
A method involving the implantation of dopants in a SiC substrate followed by localized laser heating to form carbon-rich ohmic contacts, such as graphene or graphite layers, which activates the dopants and forms self-aligned ohmic contacts within the implanted regions, eliminating the need for multiple thermal-annealing steps and ensuring precise alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple thermal-annealing steps are used for doping activation and ohmic contact formation, then dopant activation and contact formation are achieved, but misalignment occurs and leakage current increases
Solution Approach 1:
The patent combines doping activation and ohmic contact formation into a single thermal-annealing step. The metal layer is deposited over the implanted region, and one annealing process simultaneously activates the dopants and forms the ohmic contact, eliminating the need for separate processing steps that cause misalignment.
Solution Approach 2:
The metal layer is deposited in advance over the implanted region before the thermal-annealing step. This preliminary deposition ensures that the metal is precisely positioned on the dopant-containing region, so that when annealing occurs, both dopant activation and contact formation happen at the exact same location without misalignment.
2Reliability
If multiple thermal-annealing steps are used for doping activation and ohmic contact formation, then dopant activation and contact formation are achieved, but processing time and complexity increase
Solution Approach 1:
The patent merges two separate thermal-annealing processes (doping activation and ohmic contact formation) into a single unified annealing step. This reduces the overall number of processing steps, decreases manufacturing complexity, and shortens production time while maintaining device reliability.
Solution Approach 2:
The single thermal-annealing step serves multiple functions simultaneously: it activates the implanted dopants, forms the ohmic contact between the metal layer and semiconductor, and ensures proper electrical characteristics. This multi-functionality simplifies the manufacturing process.
3Reliability
If thermal annealing is used for ohmic contact formation, then contact is formed, but misalignment with implanted regions occurs
Solution Approach 1:
The metal layer is deposited in advance directly over the implanted region, establishing precise spatial registration before the thermal-annealing step. This preliminary positioning ensures that when the annealing process forms the ohmic contact, it occurs exactly at the intended location with perfect alignment to the dopant region.
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 enhances the manufacturing process by achieving optimal dopant activation and ohmic contact formation, reducing leakage current and ensuring functional Schottky contacts, thereby improving the reliability and performance of SiC electronic devices.
Implementation Method 1
generating a laser beam directed towards the implanted region thereby heating the implanted region to temperatures in the range of 1500° C. and 2600° C.
Implementation Method 2
heating the implanted region to temperatures in the range of 1500° C. and 2600° C.
Implementation Method 3
activating the dopant of the first conductivity type
Implementation Method 4
a step of thermal annealing is carried out to enable diffusion and activation of the dopant species thus implanted
Data Source
AI summary
A method for manufacturing a SiC-based electronic device, that includes implanting, at a front side of a solid body of SiC having a conductivity of N type, dopant species of P type, thus forming an implanted region that extends in depth in the solid body starting from the front side and has a top surface co-planar with said front side; and generating a laser beam directed towards the implanted region in order to generate heating of the implanted region at temperatures comprised between 1500° C. and 2600° C. so as to form an ohmic contact region including one or more carbon-rich layers, for example graphene and/or graphite layers, in the implanted region and, simultaneously, activation of the dopant species of P type.