IGBT Deep Body Clamp Diode Prevents Latch-Up
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Solution Overview
Problem
Conventional IGBT devices face issues with latch-up due to parasitic thyristors and slow switching speed caused by extra charged carriers after gate shutdown, leading to increased collector-emitter saturation voltage and poor electron injection efficiency.
Innovation Solution
The formation of deep-body dopant regions in the emitter-base contact regions to create monolithic deep-body clamping diodes, which prevent latch-up and enhance switching speed by efficiently withdrawing electrons when the gate is turned off, and function as metal field plates in the termination area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional IGBT device configuration is used, then the device can operate as a power switching device, but latch-up occurs due to parasitic thyristors formed by NPN and PNP transistors
Solution Approach 1:
A deep-body clamp diode is introduced as an intermediary component between the collector and emitter regions. The diode's anode is connected to the collector region and cathode to the emitter region, acting as a mediator that provides a controlled current path to prevent parasitic thyristor latch-up while maintaining the basic IGBT structure
Solution Approach 2:
The deep-body clamp diode utilizes specific parameter changes including deep junction depth (extending into the drift region), optimized doping concentrations (1E16 to 1E18 atoms/cm³ for the deep-body region), and controlled breakdown voltage (50V to 200V) to prevent latch-up while maintaining device performance
2Speed
If conventional IGBT device is used, then current conduction involves two electric carriers, but switching speed is slow due to extra charged carriers remaining after gate shutdown
Solution Approach 1:
The deep-body clamp diode extracts extra charged carriers (electrons and holes) from the drift region after gate shutdown by providing a dedicated recombination path. The diode becomes forward-biased when voltage exceeds the clamp voltage, enabling rapid carrier removal and reducing tail current duration
Solution Approach 2:
The deep-body clamp diode is pre-configured with specific doping profiles and junction depths during manufacturing to ensure it activates at the appropriate moment during switching. The diode's breakdown voltage is designed to be slightly higher than the collector-emitter saturation voltage, ensuring it remains inactive during normal conduction but activates promptly when needed for carrier removal
3Productivity
If IGBT is miniaturized to increase cell density, then device integration is improved, but collector-emitter saturation voltage increases
Solution Approach 1:
The deep-body clamp diode is implemented with localized doping regions having specific spatial distribution. The deep-body region is formed with dopant concentration of 1E16 to 1E18 atoms/cm³ extending 5μm to 20μm into the drift region, creating local electrical properties that control carrier behavior without affecting overall device geometry
Solution Approach 2:
The deep-body clamp diode extends the functional depth of the device by creating a vertical junction that penetrates deep into the drift region. This third-dimensional approach (depth dimension) allows carrier control without increasing planar device area, enabling the diode to function effectively in miniaturized high-density cell structures
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 deep-body clamping diodes effectively prevent latch-up and improve switching speed by reducing electron withdrawal time through electron-hole recombination, thereby reducing collector-emitter saturation voltage and enhancing overall device performance.
Implementation Method 1
The deep-body diodes serve as clamping diodes for both preventing latch up and further improving the switching speed such that the above-discussed technical difficulties and limitations may be resolved
Data Source
AI summary
A trench insulation gate bipolar transistor (IGBT) power device with a monolithic deep body clamp diode comprising a plurality of trench gates surrounded by emitter regions of a first conductivity type near a top surface of a semiconductor substrate of the first conductivity type encompassed in base regions of a second conductivity type. A collector region of the second conductivity type is disposed on a rear side opposite from the top surface of the semiconductor substrate corresponding to and underneath the trench gates surrounded by the emitter regions encompassed in the base regions constituting a plurality of insulation gate bipolar transistors (IGBTs). A deep dopant region of the second conductivity type having P-N junction depth deeper than the base region is disposed between and extending below the trench gates in the base region of the first conductivity type.