Implanted-ion dose variation from Si surface status of sub-nm scale on 90 nm ULSI process

To make a shallow junction, understanding the influence of the Si surface status is quite important to achieve stable-dose implanted layers. The causes of dose variation can be a sub-nm screening/capping oxide and silicon loss, which originate from the wet chemical processes, the photo resist processes and the clean room environment. These phenomena are examined using SIMS, sheet resistance and the transistor characteristics of a 90 nm node of high end CMOS logic device.