Vertical Power MOSFET Structure With Built-In Multi-Vt Storage
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Solution Overview
Problem
Current multi-valued logic transistors are complex and costly to produce, limiting their application in vertical power MOS devices for information storage in power circuits.
Innovation Solution
A vertical power MOSFET with built-in multiple threshold voltages (multi-Vt) is designed, featuring an epitaxial layer, well region, source region, trench gate structure, and contact structures with varying traversal gaps, allowing for information storage without additional process complexity or cost, using a semiconductor substrate with specific conductivity types and doping concentrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional multi-Vt logic transistors are used for information storage, then multiple threshold voltages can be achieved, but process complexity and manufacturing cost increase
Solution Approach 1:
The patent applies local quality by creating different threshold voltages through varying the doping concentration in the channel region at different locations. Specifically, the channel region has a first doping concentration in a first region and a second doping concentration in a second region, allowing each region to exhibit different threshold voltages while using a single unified process flow for the entire device
Solution Approach 2:
The patent implements multiple threshold voltages by changing the doping concentration parameter in the channel region. The channel region is doped with a first dopant type at a first concentration in the first region and with a second dopant type at a second concentration in the second region, creating distinct electrical characteristics in different areas without requiring separate device structures
2Adaptability or versatility
If conventional multi-Vt logic transistors are used for information storage, then multiple threshold voltages can be achieved, but manufacturing cost increases
Solution Approach 1:
The patent merges the formation of multiple threshold voltage regions into a single integrated device structure. The channel region simultaneously contains both the first and second doped regions, and the gate electrode controls both regions through a unified gate structure, eliminating the need for separate fabrication processes for each threshold voltage region
Solution Approach 2:
The gate electrode serves multiple functions by controlling both the first and second regions of the channel simultaneously. A single gate structure实现对多个阈值电压区域的控制，making the device multi-functional without requiring multiple separate control structures, thereby reducing manufacturing complexity and cost
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 multi-Vt vertical power device enables simple and cost-effective information storage with adaptable threshold voltages, suitable for both digital and analog information, and high current applications, without requiring additional process steps.
Implementation Method 1
the doping concentration of the second conductivity type within the gap region (i.e. D in FIG. 4) can influence the doping concentration in the channel region (i.e. adjacent to the physical edge of the trench) of the vertical MOS transistor depending on the gap
Data Source
AI summary
The invention provides a multi-Vt vertical power device and a method of making the same. Through patterning a contact mask, a contact structure array having a shared trench gate structure may be formed, and different traversal gaps between an edge of a contact portion of a second conductivity type and an edge of a trench may be formed in the contact structure array. As such, multi-Vt vertical states may be implemented for storing information. The present invention allows making a multi-Vt vertical power device having different Vt's to be capable to store information without additional process steps. Therefore, with respect to the present invention, the process is simple, cost is low, and application field is wide; number of Vt varies to store multi-bit digital information or analog information in the power device; the built-in multi-Vt power MOSFET and IGBT are adapted not only for the high power applications but also for information storage.