Power device on bulk substrate

A metal-oxide-semiconductor field-effect transistor (MOSFET) power device comprising:

• a bulk semiconductor substrate;
• an epitaxial layer formed on the bulk semiconductor substrate;
• an active region formed in the epitaxial layer;
• a buried well having a first conductivity type formed in the active region in the epitaxial layer;
• a source region having a second conductivity type formed in the active region proximate an upper surface of the active region, the source region being electrically connected to the buried well;
• a drain region having the second conductivity type formed in the active region proximate the upper surface of the active region and spaced laterally from the source region;
• a body region having the first conductivity type formed in the active region between the source region and the drain region on at least a portion of the buried well;
• a gate formed above the active region proximate the upper surface of the active region, wherein the gate is electrically isolated from the active region by a gate insulating layer;
• a drain terminal formed on the upper surface of the active region and electrically connected to the drain region;
• a source terminal electrically connected to the source region;
• a gate terminal electrically connected to the gate;
• and
• a shielding structure formed proximate the upper surface of the active region between the gate and the drain region, wherein the shielding structure comprises a field plate configured to control an electric field distribution along a top oxide interface away from an edge of the gate nearest the drain terminal;
• wherein the buried well has a first end below the source terminal and a second end that extends partially below the drain region, the second end being laterally spaced from the drain terminal between the drain terminal and the body region;
• and
• wherein the buried well is configured, in conjunction with the drain region, to form a clamping diode operative to position a breakdown avalanche region between the buried well and the drain terminal, and a breakdown voltage of the MOSFET power device is a function of one or more characteristics of the buried well.

A metal-oxide-semiconductor field-effect transistor (MOSFET) power device comprising:

• a bulk semiconductor substrate;
• an epitaxial layer formed on the bulk semiconductor substrate;
• an active region formed in and on the epitaxial layer;
• a buried well having a first conductivity type formed in the epitaxial layer;
• a source region having a second conductivity type formed in the active region proximate an upper surface of the active region, the source region being electrically connected to the buried well;
• a drain region having the second conductivity type formed in the active region proximate the upper surface of the active region and spaced laterally from the source region;
• a body region having the first conductivity type formed in the active region between the source region and the drain region on at least a portion of the buried well;
• a gate formed above the active region proximate the upper surface of the active region, wherein the gate is electrically isolated from the active region by a gate insulating layer;
• a drain terminal formed on the upper surface of the active region and electrically connected to the drain region;
• a source terminal electrically connected to the source region;
• a gate terminal electrically connected to the gate;
• and
• a shielding structure formed proximate the upper surface of the active region between the gate and the drain region, wherein the shielding structure comprises a field plate configured to control an electric field distribution along a top oxide interface away from an edge of the gate nearest the drain terminal;
• wherein the buried well has a first end below the source terminal and a second end that extends partially below the drain region, the second end being laterally spaced from the drain terminal between the drain terminal and the body region;
• and
• wherein the buried well is configured, in conjunction with the drain region, to form a clamping diode operative to position a breakdown avalanche region between the buried well and the drain terminal, and a breakdown voltage of the MOSFET power device is a function of one or more characteristics of the buried well.