An integrated advanced process control on RTP gate oxide thickness and feed-forward implant compensation in mass production

A fully automated advanced process control (APC) is developed for rapid thermal process (RTP) thin gate oxide (Gox) to improve both within wafer (W-in-W) and wafer to wafer (W-to-W) thickness uniformity. In addition, novel feed-forward implant dosage compensation is integrated to further improve the W-to-W drain saturation current (I_dsat or I_on) uniformity based on Gox thickness and poly critical dimension (CD) measurement. With these APC strategies implemented in a mass production line, we are able to control Gox thickness mean within 1% and within wafer sigma below 0.3% of the target, and reduce I_on variation to below 2% of its average. This helps to improve the device minimum voltage percentage (V_min %) failure to below 1.5%.