The yield from the 300-Å devices was about 70%. This loss is
most likely due to aluminum diffusing through the pinholes in
the polyimide at this high temperature. The failed 300-Å devices
as tested display very low resistance (few Ohms) indicative of
a short between the two electrodes. As suggested by the manufacturer
(Dupont) the polyimide film has pinholes and cannot
be reliably manufactured for thicknesses less than 300 Å