IGBT Diode Substrate Segmentation for Reverse Current Suppression
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Solution Overview
Problem
Existing semiconductor devices with diode and IGBT regions experience high reverse current during reverse recovery operations due to the formation of parasitic diodes, leading to increased losses.
Innovation Solution
The semiconductor device incorporates two or more deep p-type separation regions within the boundary region between the diode and IGBT regions, along with a lifetime control region in the diode drift region, to suppress the electric field and reverse current, with the separation regions being separated from each other and the cathode region, thereby reducing the flow of reverse current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a deep p-type region is formed in the boundary region between diode region and IGBT region, then the electric field concentration on gate electrode and body region is suppressed, but a parasitic diode is formed causing high reverse current during reverse recovery operation
Solution Approach 1:
The single deep p-type region is divided into multiple deep p-type regions (first deep p-type region and second deep p-type region) separated by an n-type region. This segmentation prevents the formation of a continuous parasitic diode path while maintaining electric field suppression benefits, as the n-type region interrupts the p-type conductivity path that would otherwise allow high reverse current flow.
Solution Approach 2:
An n-type region is introduced as an intermediary between the first and second deep p-type regions. This n-type region acts as a barrier that blocks the formation of a continuous parasitic diode path through the boundary region, while the separated p-type regions continue to provide electric field suppression at their respective interfaces with the diode and IGBT regions.
2Loss of energy
If a lifetime control region is formed in the diode drift region to suppress reverse current, then carrier lifetime is shortened, but reverse current still flows through the parasitic diode formed by the deep p-type region
Solution Approach 1:
The boundary region is segmented into multiple p-type regions separated by an n-type region, which interrupts the parasitic diode current path. This prevents reverse current from flowing through the boundary region even when lifetime control regions are present in the diode drift region, as the segmented structure blocks the continuous p-type path required for parasitic diode operation.
3Device complexity
If the anode electrode and emitter electrode are conducted together, then the device structure is simplified, but the deep p-type region becomes high potential causing current flow to cathode electrode via drift region
Solution Approach 1:
The n-type region serves as an intermediary barrier between the p-type anode region and p-type body region in the boundary zone. When anode and emitter electrodes are connected, this n-type intermediary prevents the formation of a continuous parasitic current path through the boundary region, blocking the harmful current flow to the cathode electrode while allowing the simplified electrode connection structure to be maintained.
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 significantly reduces the reverse current during reverse recovery operations, minimizing energy losses by localizing the electric field and utilizing a carrier lifetime control region to recombine carriers, resulting in a semiconductor device that hardly generates reverse current.
Implementation Method 1
a lifetime control region is formed in the drift region of the diode (hereafter called diode drift region) in order to suppress the reverse current which flows when the diode performs the reverse recovery operation. The lifetime control region is a region where the lifetime of carriers is shortened by forming crystal defects or the like.
Implementation Method 2
a p-type region is formed within a boundary region between the diode region and the IGBT region. The p-type region is formed in a range extending from an upper surface of the semiconductor substrate to a position deeper than both of a lower end of an anode region and a lower end of a body region. By forming the deep p-type region as aforementioned, an electric field to be concentrated on a gate electrode and the body region near the boundary of the IGBT region and the diode region is suppressed.
Data Source
AI summary
A semiconductor device, including a semiconductor substrate in which a diode region and an IGBT region are formed, is provided. A lifetime control region is formed within a diode drift region. The diode drift region and the IGBT drift region are a continuous region across a boundary region between the diode region and the IGBT region. A first separation region and a second separation region are formed within the boundary region. The first separation region is formed of a p-type semiconductor, formed in a range extending from an upper surface of the semiconductor substrate to a position deeper than both of a lower end of an anode region and a lower end of a body region, and bordering with the anode region. The second separation region is formed of a p-type semiconductor, formed in a range extending from the upper surface of the semiconductor substrate to a position deeper than both of the lower end of the anode region and the lower end of the body region, and bordering with the body region. The second separation region is separated from the first separation region.