SiC Device Compensation Layer via Self-Aligned Implantation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The challenge in manufacturing silicon carbide devices with high vertical extension and well-defined charge compensation structures is exacerbated by low diffusion coefficients of dopants, making it difficult to achieve both high voltage blocking capability and low on-state resistance at competitive costs.
Innovation Solution
A method involving self-aligned implantation and etching processes to form compensation layers with uniform dopant distribution, extending parallel to trench sidewalls, and repeating implant/etch sequences to create stepped trench sidewalls, allowing for precise control of charge balance and vertical extension without intermediate epitaxy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional multi-epitaxy/multi-implant processes with masked doping are used, then charge balance can be achieved, but manufacturing complexity and cost increase significantly
Solution Approach 1:
The patent employs self-aligned processes where the same masking structures serve multiple functions: defining both the implantation regions and the subsequent trench locations. The n-type implantation mask automatically becomes the template for trench formation, eliminating the need for separate alignment processes and reducing manufacturing complexity while maintaining charge balance precision.
Solution Approach 2:
The patent combines multiple process steps into integrated sequences: implantation and trench formation are merged into a single self-aligned workflow, and the voltage-sustaining layer simultaneously provides both the n-type doping region and the trench structure. This merging reduces the total number of separate process steps and masks required.
2Manufacturing precision
If dopant diffusion is suppressed to maintain sharp junctions, then junction definition improves, but vertical extension of compensation structures becomes difficult to achieve
Solution Approach 1:
The patent performs n-type implantation into the voltage-sustaining layer before trench formation, ensuring that the dopant distribution is established in advance. The implantation energy and angle are carefully selected to achieve the desired vertical penetration depth and lateral profile, creating a pre-defined dopant distribution that will form the compensation structure after trench etching.
Solution Approach 2:
The patent creates different dopant concentration profiles in different spatial regions: high concentration near the implantation entry point for sharp junction definition, and extended lower concentration regions for vertical compensation. The trench geometry is also locally optimized with varying depths and widths to control the final compensation structure characteristics.
3Length of stationary object
If high energy implantation is used to achieve deep dopant penetration, then vertical extension improves, but dopant distribution control and junction sharpness deteriorate
Solution Approach 1:
The patent systematically varies implantation parameters including energy (from keV to MeV ranges), angle (from normal to oblique incidence), and dose to achieve the desired dopant depth and distribution profile. By changing these parameters, the patent can control both the vertical penetration depth and the lateral spread, achieving deep compensation structures with maintained distribution control.
Solution Approach 2:
The patent employs multiple implantation steps with different energies and angles rather than relying on a single high-energy implant. This partial action approach allows cumulative dopant distribution control, where each step contributes a specific portion of the final profile, achieving deep penetration while maintaining precision through the combination of multiple controlled actions.
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 enables silicon carbide devices with high voltage breakdown capability and low on-state resistance, reducing on-state losses and allowing for precise prediction of avalanche and breakdown behavior, while also reducing the complexity and cost of manufacturing.
Implementation Method 1
First dopants are implanted into a silicon carbide body through a larger opening of a first process mask
Data Source
AI summary
First dopants are implanted through a larger opening of a first process mask into a silicon carbide body, wherein the larger opening exposes a first surface section of the silicon carbide body. A trench is formed in the silicon carbide body in a second surface section exposed by a smaller opening in a second process mask. The second surface section is a sub-section of the first surface section. The larger opening and the smaller opening are formed self-aligned to each other. At least part of the implanted first dopants form at least one compensation layer portion extending parallel to a trench sidewall.