Source and drain structures and manufacturing methods

A semiconductor structure comprising:

• a semiconductor substrate;
• a gate dielectric on the semiconductor substrate;
• a gate electrode over the gate dielectric;
• a lightly doped source or drain (LDD) region in the semiconductor substrate and adjacent the gate dielectric, wherein the LDD region comprises arsenic;
• and
• a deep source/drain region in the semiconductor substrate and adjacent the gate dielectric, wherein the deep source/drain region comprises phosphorous, and wherein a peak phosphorous concentration in the deep source/drain region is greater than about five times a peak arsenic concentration in the deep source/drain region.

A semiconductor structure comprising:

• a semiconductor substrate comprising a first region and a second region;
• a memory metal-oxide-semiconductor (MOS) device in the first region, the memory MOS device comprising:
• a first gate dielectric on the semiconductor substrate;
• a first gate electrode over the first gate dielectric;
• a first lightly doped source or drain (LDD) region in the semiconductor substrate and adjacent the first gate dielectric, wherein the first LDD region comprises arsenic;
• and
• a first deep source/drain region in the semiconductor substrate and adjacent the first gate dielectric, wherein the first deep source/drain region comprises phosphorous, and wherein a phosphorous junction depth in the first deep source/drain region is greater than an arsenic junction depth in the first deep source/drain region;
• and
• a logic MOS device in the second region, the logic MOS device comprising:
• a second gate dielectric on the semiconductor substrate;
• a second gate electrode over the second gate dielectric;
• a second LDD region in the semiconductor substrate and adjacent the second gate dielectric, wherein the second LDD region comprises arsenic;
• and
• a second deep source/drain region in the semiconductor substrate and adjacent the second gate dielectric, wherein the second deep source/drain region comprises arsenic and phosphorous, and wherein an arsenic junction depth in the second deep source/drain region is substantially comparable to a phosphorous junction depth in the second deep source/drain region, and wherein the arsenic junction depth in the second deep source/drain region is greater than about two times the arsenic junction depth in the first deep source/drain region.