Y. Martin et Hk. Wickramasinghe, TOWARD ACCURATE METROLOGY WITH SCANNING FORCE MICROSCOPES, Journal of vacuum science & technology. B, Microelectronics and nanometer structures processing, measurement and phenomena, 13(6), 1995, pp. 2335-2339
Scanning force microscopes (SFMs) have become valuable instruments for
inspection of surfaces on a submicron scale in the semiconductor indu
stry. Their ability to track the position of a surface with an accurac
y of the order of 1 nm opens the door to applications in micro- or nan
ometrology. Standard SFMs, using a conical shaped tip, are being appli
ed to measurements of the height or depth of shallow features, such as
via holes or small lines and trenches, that cannot readily be charact
erized by scanning electron microscopy or optical techniques. Recent t
echnical developments of the SFM have provided new capabilities for ac
curate measurement of the line and trench width using a flared tip and
an improved scanning and tracking method for the tip. Laboratory test
s as well as industrial tests have revealed that repeatability in meas
uring critical dimensions approaches 1 nm. If careful attention is giv
en to issues of calibration, particularly for the motion of the tip an
d for dimensioning of the tip itself, SFM techniques may attain accura
cies that approach their measurement precision. (C) 1995 American Vacu
um Society.