Semiconductor device with asymmetric PMOS source/drain implant and method of manufacture thereof

A method for forming a CMOS device, comprising:

• (a) forming at least one NMOS gate electrode over a NMOS device region of a substrate and at least one PMOS gate electrode over a PMOS device region of a substrate;
• (b) forming spacers on sidewalls of the NMOS gate electrode and the PMOS gate electrode;
• (c) selectively implanting a first n-type dopant material into NMOS active regions adjacent to the NMOS gate electrode using the spacers on the NMOS gate electrode as a mask;
• (d) forming active regions adjacent to the PMOS gate electrode by multiple implantations of p-type dopant material using at least one spacer as a mask for each implantation, the step of forming the active regions comprising:
• (i) selectively implanting a first p-type dopant material into PMOS active regions adjacent to the PMOS gate electrode using the spacers on the PMOS gate electrode as a mask;
• (ii) removing at least a portion of one of the spacers on the PMOS gate electrode and forming a thinner spacer on the PMOS gate electrode;
• and
• (iii) selectively implanting a second p-type dopant material, comprising a heavy atom species, into one of the PMOS active regions using the thinner spacer as a mask, wherein the heavy atom species is an indium or gallium species.

A method for forming a semiconductor device, comprising:

• (a) forming a gate electrode over a first device region of a substrate;
• (b) forming spacers on sidewalls of the gate electrode;
• (c) forming active regions adjacent to the gate electrode by multiple implantations of p-type dopant material using at least one spacer as a mask for each implantation, the step of forming the active regions comprising:
• (i) selectively implanting a first p-type dopant material into active regions adjacent to the gate electrode using the spacers as a mask;
• (ii) removing at least a portion of only one of the spacers and forming a thinner spacer on the gate electrode;
• and
• (iii) selectively implanting a second p-type dopant material, comprising a heavy atom species, into a first one of the active regions using the thinner spacer as a mask, wherein the heavy atom species is a gallium or indium species.

A method for forming a semiconductor device, comprising:

• forming a gate electrode over a device region of a substrate;
• forming first spacers on sidewalls of the gate electrode, the first spacers having a lateral width of 50 to 100 angstroms;
• forming second spacers adjacent to the first spacers, the second spacers having a lateral width of 50 to 250 angstroms;
• selectively implanting a first p-type dopant material into active regions adjacent to the gate electrode using the spacers as a mask;
• removing at least a portion of only one of the second spacers and forming a thinner spacer;
• and
• selectively implanting a second p-type dopant material, comprising a heavy atom species, into a first one of the active regions using the thinner spacer as a mask,
• wherein the heavy atom species is a gallium or indium species.

A method for forming a semiconductor device, comprising:

• (a) forming a gate electrode over a device region of a substrate;
• (b) forming spacers on sidewalls of the gate electrode;
• (c) forming active regions adjacent to the gate electrode by multiple implantations of p-type dopant material using at least one spacer as a mask for each implantation, the step of forming the active regions comprising:
• (i) selectively implanting a first p-type dopant material into active regions previously undoped with p-type dopant material and adjacent to the gate electrode using the spacers as a mask, wherein the dopant dosage of the first p-type dopant material ranges from 8E14 to 2E15 dopant atoms/cm.sup.2 ;
• (ii) removing at least a portion of only one of the spacers and forming a thinner spacer on the gate electrode;
• and
• (iii) selectively implanting a second p-type dopant material, comprising a heavy atom species, into a first one of the active regions using the thinner spacer as a mask, wherein the dopant dosage of the second p-type dopant material ranges from 3E15 to 8E15 dopant atoms/cm, wherein the heavy atom species is a gallium or indium species.