NMOS half-bridge power device and manufacturing method thereof

A manufacturing method of an NMOS half-bridge power device, wherein the NMOS half-bridge power device includes:

• an NMOS upper gate device and an NMOS lower gate device;
• the manufacturing method of the NMOS half-bridge power device comprising steps of:
• forming a semiconductor layer on a substrate;
• forming a plurality of insulation regions on the semiconductor layer, for defining an NMOS upper gate device region and an NMOS lower gate device region, wherein an NMOS upper gate device is formed in the NMOS upper gate device region, whereas, an NMOS lower gate device is formed in the NMOS lower gate device region;
• forming a first N-type buried layer in the NMOS upper gate device region;
• forming a first N-type high voltage isolation region and a second N-type high voltage isolation region in the semiconductor layer of the NMOS upper gate device region by one same ion implantation process;
• forming a first N-type high voltage well and a second N-type high voltage well in the semiconductor layer of the NMOS upper gate device region and the semiconductor layer of the NMOS lower gate device region, respectively, by one same ion implantation process;
• forming a first P-type high voltage well and a second P-type high voltage well in the semiconductor layer of the NMOS upper gate device region and the semiconductor layer of the NMOS lower gate device region, respectively, by one same ion implantation process;
• wherein the first N-type high voltage well and the first P-type high voltage well are in contact with each other in a channel direction, and wherein the second N-type high voltage well and the second P-type high voltage well are in contact with each other in the channel direction;
• forming a drift oxide layer on the semiconductor layer, wherein the drift oxide layer overlays the NMOS upper gate device region and the NMOS lower gate device region;
• etching the drift oxide layer to form a first drift oxide region in the NMOS upper gate device region and to form a second drift oxide region in the NMOS lower gate device region by one same etching process;
• subsequent to the formation of the first drift oxide region and the second drift oxide region, forming a gate dielectric layer on the semiconductor layer, wherein the gate dielectric layer overlays the NMOS upper gate device region and the NMOS lower gate device region;
• forming a polysilicon layer on the gate dielectric layer, wherein the polysilicon layer overlays the NMOS upper gate device region and the NMOS lower gate device region;
• etching the polysilicon layer to form a first gate in the NMOS upper gate device region and to form a second gate in the NMOS lower gate device region by one same etching process;
• forming a first P-type body region and a second P-type body region in the semiconductor layer of the NMOS upper gate device region and the semiconductor layer of the NMOS lower gate device region, respectively, by one same ion implantation process;
• wherein a portion of the first P-type body region is located vertically below the first gate, and wherein the first P-type body region and the first N-type high voltage well are in contact with each other in the channel direction, wherein a portion of the second P-type body region is located vertically below the second gate, and wherein the second P-type body region and the second N-type high voltage well are in contact with each other in the channel direction;
• forming a first N-type source and a first N-type drain in the semiconductor layer of the NMOS upper gate device region by one same ion implantation process, wherein the first N-type source and the first N-type drain are located below and outside two sides of the first gate, respectively, wherein a side of the first gate which is closer to the first N-type source is a source side and another side of the first gate which is closer to the first N-type drain is a drain side, and wherein the first N-type source is located in the first P-type body region, and the first N-type drain is located in the first N-type high voltage well;
• and
• forming a second N-type source and a second N-type drain in the semiconductor layer of the NMOS lower gate device region by the one same ion implantation process that forms the first N-type source and the first N-type drain, wherein the second N-type source and the second N-type drain are located below and outside two sides of the second gate, respectively, wherein aside of the second gate which is closer to the second N-type source is a source side and another side of the second gate which is closer to the second N-type drain is a drain side, and wherein the second N-type source is located in the second P-type body region, and the second N-type drain is located in the second N-type high voltage well;
• wherein the first N-type buried layer is formed in the semiconductor layer and in the substrate and is vertically below the first N-type high voltage well and the first P-type high voltage well;
• wherein in the channel direction, the first N-type high voltage isolation region is in contact with a side of the first N-type high voltage well, wherein this side of the first N-type high voltage well is opposite to another side of the first N-type high voltage well which is in contact with the first P-type high voltage well;
• wherein in the channel direction, the second N-type high voltage isolation region is in contact with a side of the first P-type high voltage well, wherein this side of the first P-type high voltage well is opposite to another side of the first P-type high voltage well which is in contact with the first N-type high voltage well.