Method of forming a MOS transistor
View Patent ↗A method of forming a MOS transistor, in which, a co-implantation is performed to implant a carbon co-implant into a source region and a drain region or a halo implanted region to effectively prevent dopants from over diffusion in the source region and the drain region or the halo implanted region, for obtaining a good junction profile and improving short channel effect, and the carbon co-implant is from a precursor comprising CO or CO 2 .
1. A method of forming a MOS transistor, comprising:
providing a substrate having a gate thereon, a source region and a drain region therein with a channel region under the gate therebetween;
pre-amorphizing the source region and the drain region to form amorphized regions;
performing a first ion implantation to implant a first dopant in the source region and the drain region to form a first doped region;
forming at least a spacer on the sidewalls of the gate;
performing a second ion implantation to implant a second dopant in the source region and the drain region to form a second doped region;
annealing the source region and the drain region to activate the first dopant, regrow the amorphized regions to a substantially crystalline form, and form a junction profile; and
performing a co-implantation process, after pre-amorphizing the source region and the drain region and before annealing the source region and the drain region, to implant a carbon co-implant in the source region and the drain region, wherein the carbon co-implant is from a precursor comprising CO or CO 2 .
2. The method of claim 1 , wherein the carbon co-implant is implanted in the substrate at a place substantially the same as that of the first dopant or the second dopant.
3. The method of claim 1 , further, after pre-amorphizing the source region and the drain region and before performing the first ion implantation, comprising:
performing a halo implantation to implant a third dopant between the channel region and the source region and between the channel region and the drain region.
4. The method of claim 3 , wherein the carbon co-implant is implanted in the substrate at a place substantially the same as that of the first dopant, the second dopant, or the third dopant.
5. The method of claim 3 , wherein the co-implantation process is performed after pre-amorphizing the source region and the drain region and before performing the halo implantation.
6. The method of claim 3 , wherein the co-implantation process is performed after performing the halo implantation and before performing the first ion implantation.
7. The method of claim 1 , wherein the co-implantation process is performed after pre-amorphizing the source region and the drain region and before performing the first ion implantation.
8. The method of claim 1 , wherein the co-implantation process is performed after performing the first ion implantation and before performing the second ion implantation.
9. The method of claim 1 , wherein the co-implantation process is performed after performing the second ion implantation and before annealing the source region and the drain region.
10. The method of claim 1 , wherein the first dopant comprises B, BF 2 , B w H z + , or (B w H z ) m + , wherein w is a number of 2 to 30, z is a number of 2 to 40, and m is a number of 10 to 1000.