Laterally diffused metal oxide semiconductor transistors for radio frequency power amplifiers

A laterally diffused metal oxide semiconductor (LDMOS) transistor comprising:

• a substrate having a first surface and a second surface, wherein the first surface comprises an epitaxial layer, and wherein the first surface comprises a drain region, a source region, and a channel region for the LDMOS transistor;
• a first region formed from a first N-type dopant having a first doping concentration, wherein the first region is a continuous region across the source region, the channel region, and the drain region, wherein the first region extends from the first surface into the substrate, stopping at a first depth below the first surface, and wherein the first depth is less than a depth of the epitaxial layer;
• a gate electrode over the channel region of the first surface of the substrate;
• a P-type dopant in the source region of the first surface, wherein the P-type dopant extends from the first surface into the substrate, stopping at a second depth that is greater than the first depth, the P-type dopant having a second doping concentration, wherein the P-type dopant laterally diffused under the gate electrode into the channel region a predetermined distance;
• a second N-type dopant in the drain region, the second N-type dopant having a third doping concentration that is greater than the first doping concentration, wherein the second N-type dopant extends from the first surface into the substrate, stopping at a third depth, the third depth being less than the first depth;
• an N+ source implant in the source region;
• and
• an N+ drain implant in the drain region.

A laterally diffused metal oxide semiconductor (LDMOS) transistor comprising:

• a substrate having a surface, a source region, a drain region, and a channel region;
• a first region formed from a first implant of a first conductivity type, wherein the first region is a continuous region across the source region, the drain region, and the channel region, wherein the first region extends from the surface into the substrate, stopping at a first depth below the first surface;
• a gate electrode formed over the channel region;
• a second implant of a second conductivity type formed in the source region of the substrate, wherein the second implant extends from the surface into the substrate, stopping at a second depth that is greater than the first depth, and the second implant is laterally diffused under the gate electrode into the channel region a predetermined distance;
• and
• a third implant of the first conductivity type that extends from the surface into the substrate in the drain region of the substrate, wherein the third implant stops at a third depth, the third depth being less than the first depth.