SiC Substrate Carbon Face Exposure via Ion Implantation Splitting
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Solution Overview
Problem
Current silicon carbide device manufacturing on the silicon face has limitations in achieving low doping levels and high channel mobility, particularly for devices like SiC-MOSFETs, due to the site-competition effect, which restricts the attainment of desired doping levels below 1*10^16 cm^-3 on the carbon face without significant effort or high process temperatures.
Innovation Solution
A method involving a silicon carbide substrate manufacturing process where a silicon carbide epitaxial layer is deposited on a silicon face, ion-implanted with a predefined energy characteristic to form an implant zone, and then split along this zone to expose a carbon face, allowing for the production of substrates with low doping densities and high channel mobility, enabling the fabrication of devices with blocking voltages above 500 V.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If epitaxial layer is deposited on the silicon face of silicon carbide wafer, then doping control is improved and low doping levels can be achieved, but the channel mobility of manufactured devices is reduced
Solution Approach 1:
The patent applies inversion by depositing the epitaxial layer on the silicon face and then flipping the wafer orientation through ion implantation and bonding processes. This allows the carbon face to become the exposed surface for device manufacturing, thereby achieving both low doping levels (from silicon face deposition) and high channel mobility (from carbon face device fabrication)
Solution Approach 2:
The patent segments the epitaxial layer from the original substrate using ion implantation to create a weakened implant zone, followed by bonding to a carrier wafer. This segmentation enables the epitaxial layer to be transferred and reoriented, separating the deposition surface (silicon face) from the device fabrication surface (carbon face)
2Manufacturing precision
If high process temperature is used to achieve low doping levels on carbon face, then doping control is improved, but process complexity and manufacturing effort increase
Solution Approach 1:
The patent performs preliminary action by depositing the epitaxial layer with controlled low doping levels on the silicon face before any high-temperature processing. The ion implantation and bonding steps are then used to transfer and reorient the already-formed low-doping epitaxial layer to expose the carbon face, achieving low doping levels without requiring high-temperature carbon face epitaxy
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 allows for the production of silicon carbide devices with enhanced channel mobility and high blocking voltages by creating substrates with exposed carbon faces, overcoming the limitations of doping control on the silicon face and reducing epitaxial layer defects, thereby improving device performance.
Implementation Method 1
implanting ions with a predefined energy characteristic forming an implant zone within the epitaxial layer
Implementation Method 2
depositing a silicon carbide epitaxial layer on the silicon face of the dispenser wafer
Data Source
AI summary
A method for manufacturing a silicon carbide substrate for an electrical silicon carbide device includes providing a silicon carbide dispenser wafer including a silicon face and a carbon face and depositing a silicon carbide epitaxial layer on the silicon face. Further, the method includes implanting ions with a predefined energy characteristic forming an implant zone within the epitaxial layer, so that the ions are implanted with an average depth within the epitaxial layer corresponding to a designated thickness of an epitaxial layer of the silicon carbide substrate to be manufactured. Furthermore, the method comprises bonding an acceptor wafer onto the epitaxial layer so that the epitaxial layer is arranged between the dispenser wafer and the acceptor wafer. Further, the epitaxial layer is split along the implant zone so that a silicon carbide substrate represented by the acceptor wafer with an epitaxial layer with the designated thickness is obtained.