APC Implementation on VIISta Ion Implanters

As transistor features shrink, small variations in process steps have a significant impact on device performance and yield. The industry is adopting Advanced Process Control (APC) to control wafer‐to‐wafer variations in several process steps, but to‐date APC has had limited application for implant. For example, lot‐to‐lot adjustments are being used today by chip manufacturers to adjust halo implants. The controls now possible due to the use of single wafer implant systems to adjust for blanket film variations has generated increased interest in implementing APC in the implant bay. Emerging implant APC applications are being implemented using Within wafer (WiW) control and feed‐forward methods to compensate for transistor threshold voltage non‐uniformities introduced during gate etch process steps. In the past, APC applications in implant have lagged other processing steps because of the inability to adjust parameters on batch systems and the lack of on‐board metrology. New in‐situ metrology technologies b...