Semiconductor devices and methods for forming a semiconductor device

A semiconductor device, comprising:

• a semiconductor substrate comprising a main surface, a back surface, an outer edge side extending between the main and back surfaces, and a second conductivity type drift region disposed between the main and rear surfaces;
• a cell region and an edge termination region disposed in the semiconductor substrate, the cell region being laterally separated from the outer edge side by the edge termination region;
• a switchable electrical structure disposed in the cell region, the switchable electrical structure comprising a second conductivity type source region disposed at the main surface, a first conductivity type body region, a second conductivity type drain region disposed at the back surface, a conductive gate electrode that is configured to control a conductive connection between the source and drain regions, and a conductive source electrode disposed at the main surface and connected to the source region;
• a first doping region of the first conductivity type that is disposed in the edge termination region;
• and
• a feedback path connected between the source electrode and the first doping region,
• wherein the feedback path is configured to permit charge carriers to flow between the source electrode and the first doping region during a transition from an off-state to an on-state of the switchable electrical structure and is configured to block a flow of charge carriers between the source electrode and the first doping region during at least part of a transition from the on-state to the off-state of the switchable electrical structure,
• wherein the feedback path is provided within the semiconductor substrate,
• wherein the feedback path comprises a third doping region of the first conductivity type that laterally extends from the cell region to the first doping region,
• wherein a doping concentration and thickness of the third doping region is such that the third doping region is depleted during the transition from the on-state to the off-state of the switchable electrical structure.

A semiconductor device, comprising:

• a semiconductor substrate comprising a main surface, a back surface, an outer edge side extending between the main and back surfaces, and a second conductivity type drift region disposed between the main and rear surfaces;
• a cell region and an edge termination region disposed in the semiconductor substrate, the cell region being laterally separated from the outer edge side by the edge termination region;
• a switchable electrical structure disposed in the cell region, the switchable electrical structure comprising a second conductivity type source region disposed at the main surface, a first conductivity type body region, a second conductivity type drain region disposed at the back surface, a conductive gate electrode that is configured to control a conductive connection between the source and drain regions, and a conductive source electrode disposed at the main surface and connected to the source region;
• a first doping region of the first conductivity type that is disposed in the edge termination region;
• and
• a feedback path connected between the source electrode and the first doping region,
• wherein the feedback path is configured to permit charge carriers to flow between the source electrode and the first doping region during a transition from an off-state to an on-state of the switchable electrical structure and is configured to block a flow of charge carriers between the source electrode and the first doping region during at least part of a transition from the on-state to the off-state of the switchable electrical structure,
• wherein the feedback path is provided within the semiconductor substrate,
• wherein the feedback path comprises a third doping region of the first conductivity type that laterally extends from the cell region to the first doping region,
• wherein the third doping region is configured to fully deplete before a depletion zone extending from a blocking p-n junction of the switchable electrical structure reaches the first doping region during the transition from the on-state to the off-state of the switchable electrical structure.