Dopant implantation method using multi-step implants

A method of forming a dopant implant region in a MOS transistor device, the dopant implant region having a dopant profile having a target dopant concentration, the method comprising the steps of:

• implanting a first concentration of dopants into a region of a substrate, said first concentration of dopants being less than said target dopant concentration;
• and
• without annealing the substrate after said implanting step, performing at least one second implanting step to implant at least one second concentration of dopants into the region of the substrate to bring the dopant concentration in the region to said target dopant concentration, wherein the implanting steps are performed in an implantation chamber of an implantation tool, the method further comprising the steps of unloading the substrate from the implantation chamber and then reloading the substrate into the implantation chamber in between said implanting steps.