ABSTRACT
Recent bright field transmission electron microscopy (TEM) studies (Xing et a!. 2002a, b, Helvoort et a!. 2003a, b, c) in combination with X-ray energy dispersive spectrometry (XEDS) have been able to detect a sodium depleted layer in the Pyrex near the bonded interface for both silicon and aluminium as anode materials. Depending on the process conditions and the choice of anode material, the sodium depletion layer varies between 0.5 and 2 J.lm in width. Less mobile potassium ions pile up close to the bulk Pyrex in this sodium depletion layer.
