SiC Ohmic Contacts Using 3C-SiC Interface Layer Formation
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Solution Overview
Problem
The formation of Ohmic contacts on silicon carbide (SiC) substrates is challenging due to the formation of intermediate semiconductor layers and loss of Ohmic contact behavior during post-metallization annealing, leading to increased costs and unreliable contacts.
Innovation Solution
A method involving multiple plasma deposition acts with different energy levels to implant dopants into the SiC substrate, followed by annealing to form a 3C-SiC layer, which is then metallized to create reliable Ohmic contacts with high dopant concentration near the interface, reducing the need for high-temperature annealing and minimizing dopant reorganization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If post-metallisation annealing is performed at high temperature to form Ohmic contacts, then contact resistance is reduced, but intermediate semiconductor layers form and Ohmic contact behavior is lost
Solution Approach 1:
The surface region is highly doped with dopants before metal layer deposition, creating a heavily doped surface layer that enables Ohmic contact formation without requiring post-metallisation annealing. This preliminary doping action prevents the formation of intermediate semiconductor layers while achieving low contact resistance.
Solution Approach 2:
The dopant concentration in the surface region is dramatically increased to create a highly doped layer with distinct electrical properties. This parameter change in dopant concentration transforms the surface region's ability to form Ohmic contacts without high-temperature annealing, preventing intermediate layer formation.
2Reliability
If post-metallisation annealing is performed to improve contact properties, then contact resistance decreases, but dopant reorganization occurs and dopant concentration near the interface decreases
Solution Approach 1:
The dopants are implanted into the surface region before metal layer deposition, creating a high dopant concentration profile in advance. This preliminary doping ensures that the interface region maintains high dopant concentration without subsequent annealing-induced reorganization or dopant loss.
Solution Approach 2:
The method skips the post-metallisation annealing step entirely by performing all necessary doping actions before metal layer deposition. This eliminates the harmful dopant reorganization and concentration loss that would occur during subsequent high-temperature annealing.
3Reliability
If conventional manufacturing methods are used with post-metallisation annealing, then Ohmic contacts can be formed, but additional steps are required which increase production costs
Solution Approach 1:
All dopant implantation is performed before metal layer deposition, eliminating the need for post-metallisation annealing steps. This preliminary action consolidates the manufacturing process into fewer steps, reducing production costs while maintaining reliable Ohmic contact behavior.
Solution Approach 2:
The harmful post-metallisation annealing step is removed from the manufacturing process. By extracting this unnecessary step, the method reduces production complexity and cost while avoiding the formation of intermediate semiconductor layers and dopant reorganization.
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 method enables efficient and cost-effective production of reliable Ohmic contacts with lower contact resistance, maintaining high dopant concentration at the interface, suitable for wide bandgap semiconductor devices.
Implementation Method 1
implanting dopants into a surface region of the SiC substrate
Implementation Method 2
plasma deposition acts
Implementation Method 3
annealing the implanted surface regions
Implementation Method 4
annealing the implanted surface regions to form a 3C—SiC layer
Data Source
AI summary
The present disclosure relates to methods of manufacturing Ohmic contacts on a silicon carbide (SiC) substrate including providing a 4H—SiC or 6H—SiC substrate, implanting dopants into a surface region of the 4H—SiC or 6H—SiC substrate, annealing the implanted surface regions to form a 3C—SiC layer, and depositing a metal layer on the 3C—SiC layer. An implanting sequence of the implantation of dopants includes a plurality of plasma deposition acts with implantation energy levels including at least two different implantation energy levels. The implantation energy levels and one or more implantation doses of the plurality of plasma deposition acts are selected to form a 3C—SiC layer in the surface region of the 4H—SiC or 6H—SiC substrate during the annealing act. A method of manufacturing a semiconductor device having a structure including at least three layers including a 4H—SiC or 6H—SiC layer, a 3C—SiC layer, and a metal layer, by applying one or more of the techniques described herein, and semiconductor devices obtained with one or more of the techniques described herein are described.