2.2.3 Implantation Dose

The implantation dose determines the number of ions which hit the implantation target. It is measured by counting the electrons that are necessary to neutralize the charge on the wafer introduced by the positively charged ions. These electrons are introduced into the system by connecting the wafer to an electron source, but also electron flood guns and plasma flood guns [91], which shoot electrons through the surface into the wafer. Thereby also isolating materials can be neutralized and a charge-up of insulating surfaces can be avoided.

A critical parameter for the definition of the implantation dose is the implant area, because the dose is defined as concentration per area. When simulating ion implantation often two definitions of the implantation dose are applied, which differ if the ion beam is not incident perpendicular to the wafer surface. One definition refers to an area perpendicular to the ion beam, the other defines the implantation area as being parallel to the wafer surface, which we use throughout this text.