The objective of this project was to develop a method for using thermal imaging to determine end-point in chemical mechanical polishing (C.M.P.) for a shallow trench isolation (S.T.L) C.M.P. process and contact layer C.M.P. process. A two-dimensional thermal imaging camera was used to measure the pad temperature during processing. The pad temperature is an indication of the friction between the pad and the wafer being processed. As the polishing process transitions from one layer of material to the next layer of material the amount of heat generated will change. For the STI layer a 0.3 to 0.4 degree Fahrenheit (F) shift was found in the transition from LTO to Nitride and a 1.1 degree shift was found going from Nitride to Silicon substrate. The Contact layer results were inconclusive because seven of the eight experimental wafers could not be polished. The top layer of Tantalum film could only be polished on one out of eight wafers.
"Endpoint Detection in CMP Utilizing Thermal Imaging,"
Journal of the Microelectronic Engineering Conference: Vol. 8
, Article 19.
Available at: http://scholarworks.rit.edu/ritamec/vol8/iss1/19