SiC MOSFET Channel Self-Alignment for Lower On-Resistance
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Solution Overview
Problem
Existing silicon carbide (SiC) MOSFET devices face challenges in precisely controlling the channel length due to alignment deviations in non-self-alignment processes, which affect performance and reliability, and conventional methods struggle to further reduce on-resistance.
Innovation Solution
A self-aligned manufacturing method for SiC MOSFETs that adjusts ion implantation angle and energy to form a body region, using a barrier layer to control the transverse extension length of the channel, allowing for a shorter channel and reduced on-resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If non-self-alignment process with two independent masks is used to form channel, then ion implantation can be performed to form P-type body region and N+ source region, but alignment deviation between different photoetching processes affects manufacturing precision and device reliability
Solution Approach 1:
The patent merges the formation of P-type body region and N+ source region into a single ion implantation process step. By using one mask patterned with both body and source regions, the patent eliminates the alignment deviation between multiple photoetching processes, thereby improving manufacturing precision while maintaining device reliability.
2Loss of energy
If channel length is reduced to lower on-resistance, then device performance improves, but conventional self-alignment methods using oxidized polysilicon cannot precisely control channel length
Solution Approach 1:
The patent changes the controlling parameter for channel length from oxidized polysilicon thickness to the physical mask pattern dimensions. By defining the source region boundary directly in the mask pattern, the channel length becomes precisely controllable through photolithography parameters rather than being limited by oxidation process variability, enabling shorter channels with precise control.
3Reliability
If conventional self-alignment method using oxidized polysilicon barrier layer is used, then N+ source region can be formed with self-alignment, but channel length cannot be precisely controlled and on-resistance cannot be further reduced
Solution Approach 1:
The patent extracts and removes the oxidized polysilicon barrier layer formation step from the conventional self-alignment process. Instead of relying on polysilicon oxidation to define the source region boundary, the patent directly patterns the source region in the mask, eliminating the intermediate oxidation step and its associated variability in channel length control.
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 enables precise control of the channel length to less than 0.5 μm, improving device reliability and reducing on-resistance, while maintaining high performance.
Implementation Method 1
performing an ion implantation process on the epitaxial layer to form a body region of a second doping type
Data Source
AI summary
Disclosed is a silicon carbide MOSFET device and a manufacturing method thereof. The manufacturing method comprises: forming a source region in an epitaxial layer; forming a body region in the epitaxial layer; forming a gate structure, comprising a gate dielectric layer, a gate conductor layer and an interlayer dielectric layer; forming an opening in the interlayer dielectric layer to expose the source region; forming a source contact connected to the source region via the opening, wherein an ion implantation angle of the ion implantation process is controlled to make a transverse extension range of the body region larger than a transverse extension range of the source region, so that a channel that extends transversely is formed by a portion, which is peripheral to the source region, of the body region, and at least a portion of the gate conductor layer is located above the channel.