An instrument was designed and constructed to perform a sequential etch of an oxidized silicon wafer by periodically lowering the wafer deeper into an etch bath. The unit will step the wafer at four different time intervals 15, 30, 45 and 60 seconds. Either five or ten steps can be done at one time. The unit is primarily designed for the etching of silicon dioxide in a Buffered Oxide Etch.
Crandall, Robert L.
"Design and Construction of a Step Etching Instrument,"
Journal of the Microelectronic Engineering Conference: Vol. 4
, Article 9.
Available at: http://scholarworks.rit.edu/ritamec/vol4/iss1/9