Physical Resist Model Calibration For Implant Level Using Laser-Written Photomasks

To reduce cost, implant levels usually use masks fabricated with older generation mask tools, such as laser writers, which are known to introduce significant mask errors. In fact, for the same implant photolithography process, Optical Proximity Correction (OPC) models have to be developed separately for the negative and positive mask tones to account for the resulting differences from the mask making process. However, in order to calibrate a physical resist model, it is ideal to use single resist model to predict the resist performance under the two mask polarities. In this study, we show our attempt to de-convolute mask error from the Correct Positive (CP) and Correct Negative (CN) tone CD data collected from bare Si wafer and derive a single resist model. Moreover, we also present the predictability of this resist model over a patterned substrate by comparing simulated CD/profiles against wafer data of various features.