SPECTROSCOPIC ELLIPSOMETRY - A NEW TOOL FOR ON LINE QUALITY-CONTROL

In this paper we report on the development and performance of the firs t fully automatic spectroscopic ellipsometer in a production line of i ntegrated circuits. We describe the problem to be solved by the new eq uipment (multilayer monitor), combining the advantages of spectroscopi c ellipsometry, i.e. ultrathin layer measurement and multilayer measur ement capability, with mass production requirements, i.e. fully automa tic system with cassette to cassette robot, compatible with clean room (class 1), operator oriented user friendly software and equipped with host computer connection. Measurement results, obtained on production wafers, are discussed in terms of reproducibility, stability and prec ision of thickness measurements for single layers-oxide, nitride on si licon or resist on aluminium-and for multilayer stacks-oxide/polysilic on/oxide on silicon and nitride/oxide/polysilicon/oxide on silicon.