SiC Trench Gate Structure for Deep Doping Without Lattice Damage
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Solution Overview
Problem
The existing manufacturing methods for silicon carbide semiconductor devices face challenges in forming doping regions with larger depths due to lattice damage caused by high-energy ion injection, leading to complex processes and higher costs, especially in achieving targeted groove gate electrode protection structures and anti-surge designs.
Innovation Solution
A manufacturing method for silicon carbide semiconductor devices involves forming an epitaxial wafer with a semiconductor substrate, first, second, and third epitaxial layers, where ion injection is performed in the second epitaxial layer based on a groove to create a doping region that penetrates through, allowing for the formation of a gate electrode and enabling deeper doping without lattice damage, thus simplifying the process and reducing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If high-energy ion injection is used to achieve large injection depth, then doping depth is improved, but lattice damage occurs
Solution Approach 1:
The epitaxial wafer is divided into multiple epitaxial layers (first, second, and third epitaxial layers) with different doping types and depths. The doping process is segmented into multiple stages: forming well regions in the third epitaxial layer, then performing ion injection through the groove into the second epitaxial layer to create the doping region. This segmentation allows achieving deep doping without concentrating all energy in a single injection step, thereby reducing lattice damage.
Solution Approach 2:
The groove is formed in the third epitaxial layer before performing ion injection. This preliminary action creates a predefined pathway that guides the ion injection process, enabling precise control over the doping region formation in the second epitaxial layer. The groove structure allows subsequent ion injection to achieve the desired doping depth while maintaining lattice integrity through controlled energy distribution.
2Length of stationary object
If multiple etching and ion injection steps are performed to form deep doping regions, then doping depth is improved, but manufacturing complexity increases
Solution Approach 1:
The groove is formed in advance in the third epitaxial layer before ion injection. This preliminary groove formation simplifies subsequent processing by providing a predefined structure that guides the ion injection process. The groove acts as a mask and pathway, eliminating the need for multiple complex etching steps that would otherwise be required to create the doping region geometry.
Solution Approach 2:
The formation of the doping region is merged with the existing groove structure. Instead of separately forming the doping region geometry and then filling it with ions, the groove itself serves as the template for both the geometric structure and the ion injection pathway. This merging of functions reduces the total number of process steps and simplifies manufacturing.
3Reliability
If complex manufacturing processes are used to achieve targeted groove gate electrode protection, then device reliability is improved, but manufacturing cost increases
Solution Approach 1:
The groove structure serves multiple functions simultaneously: it provides mechanical support for the gate electrode, defines the doping region geometry through ion injection, and offers protection to the underlying structures. This multi-functionality eliminates the need for separate protective structures, simplifying the manufacturing process and reducing costs while maintaining device reliability.
Solution Approach 2:
The groove structure automatically provides protection to the gate electrode and underlying regions through its geometric configuration. The groove walls and bottom inherently shield sensitive areas during subsequent processing steps without requiring additional protective layers or complex manufacturing interventions. The structure serves itself as both the functional element and the protective element.
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 formation of a JFET structure on the current path, automatically adjusting on-resistance and self-locking protective effects, reducing device size, and enhancing surge voltage resistance and overvoltage protection, thereby improving device reliability and manufacturability.
Implementation Method 1
performing ion injection in the second epitaxial layer based on the groove to form a doping region inverted from the second epitaxial layer
Implementation Method 2
sequentially performing epitaxy on the surface of the semiconductor substrate to form the first epitaxial layer, the second epitaxial layer and the third epitaxial layer
Data Source
AI summary
The present application discloses a silicon carbide semiconductor device and a manufacturing method therefor. An epitaxial wafer comprises a semiconductor substrate; a first epitaxial layer provided on the surface of the semiconductor substrate; al second epitaxial layer provided on the surface of the side of the first epitaxial layer facing away from the semiconductor substrate; and a third epitaxial layer provided on the surface of the side of the second epitaxial layer facing away from the first epitaxial layer. A gate is formed by means of a trench formed in the third epitaxial layer, and ion implantation can also be performed in the second epitaxial layer on the basis of the trench before the gate is formed, such that a doped region inverted with the second epitaxial layer is formed in the second epitaxial layer.