Lateral IGBT With Multiple MOS Gates and Buffer Region
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Integrated circuits require lateral insulated gate bipolar transistors (L-IGBTs) with increased current density capacity to meet the demands of shrinking component sizes, but existing L-IGBTs struggle to achieve high current densities without increasing voltage drop across the n-type drift region.
Innovation Solution
The design incorporates multiple metal oxide semiconductor (MOS) gates controlling multiple MOS transistor channels in parallel, along with a vertically extended base and a source buffer region with higher doping density, to enhance base current uniformity and capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the n-type drift region is made thinner to reduce voltage drop, then voltage drop decreases, but current carrying capacity is reduced
Solution Approach 1:
The patent applies local quality by creating a buffer region with higher doping concentration (1E16 to 1E18 atoms/cm³) specifically in the n-type drift region near the collector contact, while maintaining lower doping in other areas. This localized high-doping region reduces voltage drop and improves carrier injection without requiring the entire drift region to be thin, thus preserving current carrying capacity.
2Productivity
If component size is reduced to increase current density, then current density increases, but manufacturing precision requirements increase
Solution Approach 1:
The patent changes the doping concentration parameter by introducing a buffer region with higher doping (1E16 to 1E18 atoms/cm³) compared to the base region (1E15 to 1E17 atoms/cm³). This parameter change enables the device to achieve higher current density without proportionally reducing component dimensions, thereby avoiding the need for extremely precise fabrication at smaller scales.
3Quantity of substance
If base current is increased to drive higher collector current, then collector current capacity increases, but base current uniformity deteriorates
Solution Approach 1:
The buffer region with higher doping concentration is strategically positioned near the collector contact to locally enhance carrier generation and injection. This localized approach increases overall base current capacity while maintaining uniform current distribution by addressing the specific region where non-uniformity typically occurs, rather than uniformly increasing doping throughout the entire base region.
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 configuration increases current capacity and reduces voltage drop, providing higher collector current density and improved spatial uniformity of injected hole current, addressing the need for higher current densities in L-IGBTs.
Implementation Method 1
two or more metal oxide semiconductor (MOS) gates controlling two or more MOS transistor channels connected in parallel to the base of the bipolar transistor
Implementation Method 2
A buffer region is formed which surrounds the sinks in the source area of the L-IGBT, with a higher doping density than the base of the bipolar transistor
Data Source
AI summary
Current density in an insulated gate bipolar transistor (L-IGBT) may be increased by adding a second gate, and the corresponding MOS transistors, to the source area, which increases the base current compared to a L-IGBT with a single MOS gate. The current density may be further increased by extending the base of the bipolar transistor in the L-IGBT vertically to the bottom surface of the silicon on insulator (SOI) film in which the L-IGBT is fabricated. Adding a buffer diffused region around the sinks in the source improves the base current spatial uniformity, which improves the safe operating area (SOA) of the L-IGBT. A L-IGBT of either polarity may be formed with the inventive configurations. A method of forming the inventive L-IGBT is also disclosed.