SiC MOSFET P-Well Formation With Two-Step Ion Implantation
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Solution Overview
Problem
Multiple Al ion implantation in planar gate SiC MOSFET processes causes surface damage and roughness of the P well channel, limiting channel carrier mobility and device conductivity.
Innovation Solution
A two-step ion implantation process forms a first easy-to-diffuse region followed by a second deeper, less-diffuse region, with a shared mask layer, to create a well region through junction diffusion, reducing surface roughness and enhancing conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If multiple Al ion implantation is used to form P well, then the P well depth is sufficient, but the channel surface becomes rough and conductivity decreases
Solution Approach 1:
The P well formation process is segmented into two distinct ion implantation steps: first forming a shallow easy-to-diffuse region, then forming a deeper difficult-to-diffuse region. This segmentation allows the channel surface to remain smooth while achieving sufficient P well depth through the combined effect of both regions.
Solution Approach 2:
The invention changes the diffusion parameters by using two different ion types with different diffusion characteristics. The easy-to-diffuse ions (first conductive type) provide shallow doping that diffuses well, while the difficult-to-diffuse ions (second conductive type) provide deep doping with minimal diffusion, maintaining surface quality while achieving depth.
2Reliability
If multiple Al ion implantation is used to form P well, then the P well is formed, but device conductivity is limited
Solution Approach 1:
The invention changes the diffusion parameters by using two different ion types with different diffusion characteristics. The easy-to-diffuse ions (first conductive type) provide shallow doping that diffuses well, while the difficult-to-diffuse ions (second conductive type) provide deep doping with minimal diffusion, maintaining surface quality while achieving depth.
Solution Approach 2:
Different regions of the P well are given different local qualities through selective ion implantation. The shallow region has easy-to-diffuse ions for good conductivity near the surface, while the deep region has difficult-to-diffuse ions for stable deep doping. This local differentiation optimizes both surface mobility and overall P well formation.
3Length of stationary object
If multiple Al ion implantation is used, then P well depth is achieved, but surface damage occurs
Solution Approach 1:
The P well formation process is segmented into two distinct ion implantation steps: first forming a shallow easy-to-diffuse region, then forming a deeper difficult-to-diffuse region. This segmentation allows the channel surface to remain smooth while achieving sufficient P well depth through the combined effect of both regions.
Solution Approach 2:
The easy-to-diffuse ion region acts as an intermediary layer between the surface and the deep difficult-to-diffuse ion region. This intermediary layer protects the surface from direct damage by the deeper ion implantation while still allowing the deep region to be formed effectively.
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
The method reduces channel surface roughness, improves channel mobility, and enhances device reliability by maintaining SiC crystal quality and gate oxide integrity, while simplifying the manufacturing process.
Implementation Method 1
the first implantation region is activated to form a required well region in a mode of junction diffusion in the first implantation region
Implementation Method 2
first well ions of a first conductive type are implanted in a surface layer on the front of the substrate to form a first implantation region
Data Source
Figure 1
Figure 2(A)~2(F)
AI summary
The present invention provides a metal oxide semiconductor field effect transistor (MOSFET) device and a manufacturing method therefor. First, a first implantation region easy to diffuse is formed, and then, a second implantation region which is not easy to diffuse and has a deeper junction is formed in sequence. After ion implantation in a source region and the like is completed, the first implantation region is activated to form a required well region in a mode of junction diffusion in the first implantation region, and the second implantation region is used for increasing the depth of the well region, thereby avoiding the problems of damage to the surface of a substrate at a channel and roughness of the surface of the channel of the device caused by the formation of a P well directly through multiple Al ion implantation in the prior art, and achieving high conductivity of the device. In addition, the ion implantation in the first implantation region, the second implantation region and the source region can use a same mask layer, so that the process is simple to implement, and the photoetching frequency can be effectively reduced.