High voltage device and manufacturing method thereof

A manufacturing method of a high voltage device, comprising:

• forming a semiconductor layer formed on a substrate, wherein the semiconductor layer has a top surface and a bottom surface that is opposite to the top surface in a vertical direction;
• forming an isolation structure on and in contact with the top surface, wherein the isolation structure defines an operation region;
• forming a drift oxide region on and in contact with the top surface, wherein the drift oxide region is located on a drift region in the operation region and in contact with the drift region;
• forming a well region in the operation region, wherein the well region is formed beneath the top surface and in contact with the top surface in the vertical direction, and the well region has a first conductivity type;
• forming a body region having a second conductivity type in the well region in the operation region, wherein the body region is located beneath the top surface and in contact with the top surface in the vertical direction, and the body region has a first impurity concentration;
• forming a body electrode having the second conductivity type in the body region to serve as an electrical contact of the body region, wherein the body electrode is located beneath the top surface and in contact with the top surface in the vertical direction, and the body electrode includes a main body electrode and at least one sub-body electrode;
• forming a buffer region having the second conductivity type in the well region in the operation region, beneath the top surface and in contact with the top surface in the vertical direction, wherein the buffer region encompasses all periphery of the body region below the top surface, and wherein the buffer region has a second impurity concentration which is lower than the first impurity concentration;
• forming a gate on the top surface in the operation region, wherein the gate is substantially a rectangle that extends along a width direction which is a direction perpendicular to the vertical direction, and a portion of the body region and the buffer region are located right below the gate and in contact with the gate to assist forming an inverse current channel during ON operation of the high voltage device;
• forming a source and a drain having the first conductivity type, wherein the source and the drain are formed in the operation region, beneath the top surface and in contact with the top surface in the vertical direction, and the source and the drain are located outside and beneath the gate, and respectively at two lateral sides of the gate, wherein the source is located in the body region and the drain is located in the well region at a location which is away from the body region;
• wherein the drift region is located in the well region, between the drain and the buffer region in a channel direction which is a direction perpendicular to the vertical direction and the width direction, and is in contact with the top surface, to serve as a drift current channel during ON operation of the high voltage device;
• wherein the main body electrode is adjacent to the source, and the main body electrode and the source are substantially rectangles that extend along the width direction, wherein the source is located between the main body electrode and the gate, and the sub-body electrode extends from the main body electrode toward the gate in the channel direction and contacts the inverse current channel.

A high voltage device comprising:

• a semiconductor layer formed on a substrate, wherein the semiconductor layer has a top surface and a bottom surface that is opposite to the top surface in a vertical direction;
• an isolation structure formed on and in contact with the top surface, wherein the isolation structure defines an operation region;
• a drift oxide region formed on and in contact with the top surface, wherein the drift oxide region is located on a drift region in the operation region and in contact with the drift region;
• a drift well region having a first conductivity type, wherein the drift well region is formed in the operation region of the semiconductor layer and the drift well region is formed beneath the top surface and in contact with the top surface in the vertical direction;
• a channel well region having a second conductivity type, wherein the channel well region is formed in the operation region and is located beneath the top surface and in contact with the top surface, and the channel well region has a first impurity concentration;
• a channel well region contact having the second conductivity type, the channel well region contact serving as an electrical contact of the channel well region, wherein the channel well region contact is formed in the channel well region, beneath the top surface and in contact with the top surface in the vertical direction, and the channel well region contact includes a main channel well region contact and at least one sub-channel well region contact;
• a buffer region having the second conductivity type in the operation region, wherein the buffer region is formed beneath the top surface and in contact with the top surface in the vertical direction, and the buffer region encompasses all periphery of the channel well region below the top surface of the semiconductor layer, and the buffer region is in contact with the drift well region in a channel direction which is a direction perpendicular to the vertical direction, wherein the buffer region has a second impurity concentration which is lower than the first impurity concentration;
• a buried layer having the first conductivity type, wherein the buried layer is formed beneath the channel well region and in contact with the channel well region in the vertical direction, and the buried layer completely covers a portion of the channel well region which is in the operation region;
• a gate formed on the top surface in the operation region, wherein the gate is substantially a rectangle that extends along a width direction which is a direction perpendicular to the vertical direction and the channel direction, and a portion of the body region and the buffer region are located right below the gate and in contact with the gate to assist forming an inverse current channel during ON operation of the high voltage device;
• and
• a source and a drain having the first conductivity type, wherein the source and the drain are formed in the operation region, beneath the top surface and in contact with the top surface in the vertical direction, and the source and the drain are located outside and beneath the gate, and respectively at two lateral sides of the gate, wherein the source is located in the channel well region and the drain is located in the drift well region at a location which is away from the channel well region;
• wherein the drift region is located in the drift well region, between the drain and the buffer region in the channel direction, and is in contact with the top surface, to serve as a drift current channel during ON operation of the high voltage device;
• wherein the main channel well region contact is adjacent to the source, and the main channel well region contact and the source substantially are rectangles that extend along the width direction, wherein the source is located between the main channel well region contact and the gate, and the sub-channel well region contact extends from the main channel well region contact toward the gate in the channel direction and contacts the inverse current channel.

A manufacturing method of a high voltage device, comprising:

• forming a semiconductor layer on a substrate, wherein the semiconductor layer has a top surface and a bottom surface that is opposite to the top surface in a vertical direction;
• forming an isolation structure on and in contact with the top surface, wherein the isolation structure defines an operation region;
• forming a drift oxide region on and in contact with the top surface, wherein the drift oxide region is located on a drift region in the operation region and in contact with the drift region;
• forming a drift well region having a first conductivity type in the operation region of the semiconductor layer, wherein the drift well region is formed beneath the top surface and in contact with the top surface in the vertical direction;
• forming a channel well region having a second conductivity type in the operation region, beneath the top surface and in contact with the top surface in the vertical direction, wherein the channel well region has a first impurity concentration;
• forming a channel well region contact having the second conductivity type to serve as an electrical contact of the channel well region, wherein the channel well region contact is formed in the channel well region, beneath the top surface and in contact with the top surface in the vertical direction, and the channel well region contact includes a main channel well region contact and at least one sub-channel well region contact;
• forming a buffer region having the second conductivity type in the operation region, wherein the buffer region is formed beneath the top surface and in contact with the top surface in the vertical direction, and the buffer region encompasses all periphery of the channel well region below the top surface of the semiconductor layer, and the buffer region is in contact with the drift well region in a channel direction which is a direction perpendicular to the vertical direction, wherein the buffer region has a second impurity concentration which is lower than the first impurity concentration;
• forming a buried layer having the first conductivity type beneath the channel well region and in contact with the channel well region in the vertical direction, wherein the buried layer completely covers a portion of the channel well region which is in the operation region;
• forming a gate on the top surface in the operation region, wherein the gate is substantially a rectangle that extends along a width direction which is a direction perpendicular to the vertical direction and the channel direction, and a portion of the body region and the buffer region are located right below the gate and in contact with the gate to assist forming an inverse current channel during ON operation of the high voltage device;
• and
• forming a source and a drain having the first conductivity type, wherein the source and the drain are formed in the operation region, beneath the top surface and in contact with the top surface in the vertical direction, and the source and the drain are located outside and beneath the gate, and respectively at two lateral sides of the gate, wherein the source is located in the channel well region and the drain is located in the drift well region at a location which is away from the channel well region;
• wherein the drift region is located in the drift well region, between the drain and the buffer region in the channel direction, and is in contact with the top surface, to serve as a drift current channel during ON operation of the high voltage device;
• wherein the main channel well region contact is adjacent to the source, and the main channel well region contact and the source substantially are rectangles that extend along the width direction, wherein the source is located between the main channel well region contact and the gate, and the sub-channel well region contact extends from the main channel well region contact toward the gate in the channel direction and contacts the inverse current channel.