COUNTER-IMPLANTATION METHOD OF MANUFACTURING A SEMICONDUCTOR DEVICE WITH SELF-ALIGNED ANTI-PUNCHTHROUGH POCKETS

摘要

A method of processing a semiconductor device shapes a layer buried within a substrate of the semiconductor device. This layer has a conductivity the same as that of the substrate but has a higher doping level. In this process, a region of the layer is selected and ions of an opposite conductivity to the selected layer are counter-implanted in the region so that the doping level is substantially canceled. A region of the layer adjacent to the counter-implanted region retains a higher doping level. Alternative techniques are employed to protect the doped region against the counter-implant. In a first approach, the layer is doped and subsequently a mask is formed on the surface of the substrate. The mask is furnished by a part of the semiconductor device, such as a spacer which is connected to the gate electrode after the dopant layer is formed in the substrate. After the mask is formed, ions are counter-implanted with the mask protecting the doped region. In a second approach, both the ion implant forming the doped layer and the counter-implant are performed after masking structures are formed, however the ion implant is a large-angle implant which implants ions beneath the masking structure while the counter-implant is a perpendicular implant so that regions beneath the masking structure are protected from cancellation.