Optical photomicrograph of untreated cracks in a 1.4-um-
thick CVD PSG layer over a continuous 1.8-um-thick layer
of aluminum on oxidized silicon. Pinholes (if present)
would be invisible because of metal grain structure
(385X, brightfield) .
Etching-demarcated microcracks in sample shown in figure 1.
Dark bands are substrate from which aluminum was removed
from underneath glass layer in 10 min selective metal
etching at 50°C. Glass crack is dark line in center of
15-18-um-wide bands. No pinholes are present in this
sample area (385X, Nomarski differential interference
contrast)
Scratch-induced heavy damage in glass layer made visible by
20-min aluminum etching. Scribe direction was apparently
downward with increasing pressure. Sample structure as
noted in figure 1 (385X, bright field)
Scratch-induced microcracks in glass layer similar to
figure 3. Most damage occurs in V-shaped part of pattern.
Maximum spread of demarcation is 80 μm (385X, brightfield).
Optical photomicrograph of microcrack structure in 1.4-um-
thick PSG layer on a 1.8-um-thick aluminum layer on oxi-
dized silicon. (a)-incompletely demarcated by selective
etching for 20 min. (b)-completely demarcated by addition-
al 10 min of aluminum etching (500X, bright field)
Stress- and scratch-induced cracks and several pinholes in
0.7-um-thick PSG layer on 1.8-um-thick aluminum layer on
oxidized silicon. Demarcation-etched for 20 min. Width
of circular band is 25 μm (200X, bright field)
Circular, self-terminating crack pattern in glass layer as
in figure 6 except that PSG is 1.4 um thick (200X)
Optical photomicrograph of stress cracks of a CVD silicon
dioxide film of 1-um thickness deposited over oxidized
silicon with squares of 105 x 105 um of evaporated aluminum.
Demarcation was achieved by 10-min aluminum etching. Cracks
surround most of pattern along edge of aluminum. Differ-
ences in the width of the inside area are most probably
caused by differences in the width of the cracks (150X,
brightfield) . .
Scanning electron micrographs at 5000X of untreated micro-
crack in 1.4-um-thick PSG over 1.8-um-thick evaporated
aluminum on oxidized silicon substrate wafer.
crack is about 0.4 μm. (a)-45° view and (b)-25° view from
perpendicular