Capacitive Etch Rate Monitor for Dielectric Etching
Original Publication Date: 1988-Jun-01
Included in the Prior Art Database: 2005-Feb-15
An in-situ etch rate monitor is described which is applicable for etching dielectrics, and the device measures the change in capacitance between the etch bath and a metal electrode that is coated with the dielectric to be etched. The etch rate monitor comprises an electrically conductive etch bath 1 into which is inserted a non-etching reference metal electrode 2. The electrode 2 is connected to one terminal of a capacitance bridge 3, and the other terminal of the capacitance bridge 3, is connected to a powered electrode 4. The powered electrode 4 is isolated from the bath 1 by a dielectric fixture. The dielectric fixture comprises a non-etchable holder having side walls 6 which extend above the level of the etch bath 1 and a thick annular rim 7 upon which a test electrode 8 is mounted.