QUALITY
ASSURANCE--------------------
3.3.1 Quality Control
of
Parts and Material.
As semiconductor devices tend towards higher per-
formance and higher reliability. the importance of
quality control
of
parts and materials becomes para-
mount.
Items such as crystals. lead frames.
fine
wire
for wire bonding. packages. and materials needed
in
manufacturing processes such as masks and chemi-
cals. are
all subject to rigorous inspection and control.
Incoming inspection is performed based on the
pur-
chase specification and drawing. The sampling is exe-
cuted based mainly on Mll-STD-105D.
The other activities
of
quality assurance are as
follows:
(1) Outside vendor technical information meeting.
(2)
Approval and guidance of outside vendors.
(3)
Chemical analysis and test.
The typical check points
of
parts and materials are
shown in
Table
1.
Mlttrill.
Plrtl
Wlfer
Milk
Fine
Wirlfor
Wirl
Bonding
Pilltic
Impol'Ulnt
Control
It,ml
Apptlr_
Dimension
ShtttRllilt_
D.ttct
Denlity
Cryltll Axis
Appelrlnce
Dimension
Rlliltorllion
Grldltion
Appelrlnce
DimenSion
Purity
Elongltion Ratio
Appnr_
Dimenllon
PrOCllling
Accuracy
Pllting
Mounting
Chlrtcterilties
Appelr_
Dimension
L.ak Rlliltanee
Pllting
Mountiftg
Char_rilties
Eltctrical
Char_rilties
Mechanical
Strlngth
Composition
Electrical
Chartctariitici
Thermll
Chartcterilties
Molding
Performlnce
Mounting
Chlrtcttrilties
Point for Check
DIlNglInd
Conttmlna·
tion
on
Surftct
Flit"...
RlliltlllCt
D.fect Numbers
Defect Numben.
Scrltch
Dimenlion
Level
Uniformity
of
,Grldltion
Contlminltion. Scrltch.
Bend. Twilt
Purity
Level
Mechanical
Str.ngth
Contaminltion. Scratch
Dimenlion
Level
Bondabilitv. Solderability
Helt
RllilOtlnee
Contlminltion. Scratch
Dimenlion
Level
Airtightn
...
BondlbilitV. Solderlbilitv
He.t
Rlliltlnce
Mechlnical Strlngth
CharlCtirilties
of
Pilitic Mlterill
Molding Performance
Mounting
Char_risties
22
3.3.2
Inner Process Quality Control
Inner Process Quality Control performs very important
functions
in
quality assurance of semiconductor
devices. The manufacturing
Inner Process Quality
Control is shown
in
Fig.
3.
(1) Quality
Control of Semi-final Products and Final
Products
Potential
failure factors of semiconductor devices
are removed
in
the manufacturing process.
To
achieve this. check points are set-up
in
each pro-
cess and products which have potential failure
factors are not moved to the next process step.
Manufacturing lines are rigidly selected and tight
inner process quality controls are
executed-rigid
checks
in
each process and each lot. 100% inspec-
tion to remove failure factors caused
by
manufac-
turing variables and high temperature aging and
temperature cycling. Elements
of inner process
quality control are as follows:
• Condition control of equipment and
worker.
environment and random sampling
of
semi-
final products.
• Suggestion system for improvement
of
work.
• Education
of
workers.
• Maintenance and improvement
of
yield.
• Determining quality problems. and implement·
ing countermeasures.
• Transfer
of
quality information.
(2) Quality
Control of Manufacturing Facilities and
Measuring Equipment
Manufacturing equipment is improving as higher
performance devices are
needed.
At
Hitachi. the
automation
of
manufacturing equipment is en-
couraged. Maintenance Systems maintain opera-
tion
of high performance equipment. There are
daily inSpections which are performed based on
related specifications.
Inspection points are listed
in
the specification and are checked one
by
one
to
prevent any omission.
As
for adjustment and
maintenance
of
measuring equipment. specifica-
tions are checked one by one to maintain and
improve quality.
(3) Quality Control
of
Manufacturing Circumstances
and Sub-Materials
The quality and reliability
of semiconductor
devices
are highly affected
by
the manufacturing process.
Therefore. controls
of
manufacturing circum-
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