Towards an intelligent in-line temperature measurement system for semiconductor manufacturing

Photolithography is a major process in the semiconductor manufacturing industry. As the absolute temperature and temperature uniformity of the silicon wafer are important parameters for critical dimension control, special temperature considerations are needed during the various steps in the lithography sequence. The desire to print smaller features on larger substrates has necessitated more stringent wafer temperature control. It is becoming increasingly difficult to meet the tighter specifications using the current practices because wafer temperature is usually not measured in-line. Consequently, there are interests in developing in-situ wafer temperature metrology. This paper describes an intelligent in-line temperature acquisition system for continuously monitoring the wafer's spatial temperature distribution as well as the conditions of the sensing elements. Experimental results that demonstrate the feasibility of utilising the self-heating test to detect out-of-contact faults are presented.