ITT - Index of

SMALL SIGNAL CHIPS AND WAFERS
TRANSISTOR WAFER INSPECTION CRITERIA
MECHANICAL INSPECTION
Measure overall thickness of one (1) wafer if run
contains five (5) or less wafers. Measure two (2)
wafers if run size is greater than six (6) wafers.
Reject the run if any of the measured wafers are
not per limits specified in Table I.
Q.C. will 100% measure overall thickness of each
wafer in a rejected run.
VISUAL INSPECTION
Inspect ten (10) randomly selected devices on
each wafer with no more than three (3) die in any
one quadrent using 100X magnification.
3. Aluminum color - the aluminum may not
be dark brown or black.
4. Aluminum reduction - aluminum fingers
must be continuous along 75% of the oxide
cutout length nearest the bond pad on
metal over oxide devices. Aluminum fingers
may not be reduced more than 50%
of the oxide cutout width on metal over
oxide devices, nor more than 25% in width
at an oxide step-down point. Bond pads
must not be reduced more than 25% of
their intended area. EQR rings may not be
discontinuous at more than one place.
5. Oxide holes-silicon may not be exposed
within .0002 in. of any junction.
TABLE I
UNAIDED EYE INSPECTION
1. Backside gold - the backside gold must
cover 90% of the wafer surface. The gold
must exhibit a gold, orange, or yellow cast.
The gold must show no evidence of peeling
or blistering.
6. Mask misalignment - the outline of one
oxide mask definition may not cross over
the outline of another mask definition.
Aluminum mask outlines must cover more
than 50% of the intended oxide cutouts.
TijANSISTDR DIE INSPECTION CRITERIA
Inspect per Table II using 100X to combined 2.5%
AQL.
Microscope Inspection (ll1DX) -
Combined 1:0% AQL
1. Aluminum bridging-the base metal, emitter
metal, and EQR ring metal may not be
connected or bridged by unetched or
smeared aluminum.
2. Aluminum adherance-the aluminum may
show no evidence of peeling, blistering,
or flaking.
TABLE II
1. Broken die - broken corners, edges, or
shell chips may not extend closer thai1
.001" to a junction or bond pad.
2. Cracks-cracks which are not terminated
at each end at the periphery of the die
may not extend toward a junction or bond
pad.
9-2