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SEMI E124-1103 © SEMI 2003 15 ( ) - - - 2355.5 minutes 2592.0 minutes 90.88% best case cycle time throughput rate and cycle time e fficiency avera ge cycle time = ≈ ≈ (8) ( ) ( ) ( ) () w afers 812.4 minutes 0.2182 min u…
SEMI E124-1103 © SEMI 2003 14
Table R2-2 Equipment Data
Equipment
Set
Name
Number
in
Set
Process
Batch Size,
wafers
Buffer
Size,
wafers
Average
operational
efficiency
availability
efficiency
(each tool)
Average
availability
efficiency
bottleneck throughput
rate (See Note 1),
wafers/minute
Diffusion 2 75 450 88% 93% & 97% 95% 0.2969
Dry Etch 2 25 300 78% 81% & 85% 83% 0.5188
Lithography 1 1 300 91% 96% 96% (max!) 0.2182
Transport 1 25 0 69% 62% 62% 0.5536
NOTE 1: (bottleneck throughput rate) = (Number in Set) × (Average availability efficiency)/Σ(theoretical production time per unit)
() ()
[][]
[][]
[][]
[][]
450 75 2 300 25 2
300 1 1 0 25 1
450 150 300 50
300 1 0 25
600 350 301 25
1276 wafers
Process Size
WIP Buffer
Batch of
capacity Size
Size Set
eE
=+×
∈
=+×++×
+ + × + + ×
=+++
+ + + +
=+++
=
∑
(1)
(
)
938,571 wafers
4,733,640 minutes
wafers
0.1983
minute
f
inished units out
actual
throughput rate
total time
=
=
≈
(2)
(
)
(
)
(
)
()
wafers
2592 minutes 0.19827
minute
513.9 wafers
average average actual
WIP cycle time throughput rate
=×
≈×
≈
(3)
(
)
938,571 wafers
513.9 wafers
1826.3 turns
f
inished units out
WIP
turnover
average WIP
=
≈
≈
(4)
(
)
()
{}
min ,
1276 wafers wafers
min , 0.2182
812.4 minutes minute
wafers
min 1.5707, 0.2182
minute
0
WIP
theoretical
bottleneck
capacity
throughput throughput
theoretical
rate
rate
cycle time
=
≈
≈
≈
wafers
.2182
minute
(5)
(
)
()
{}
-
min ,
513.9 wafers wafers
min , 0.2182
812.4 minutes minute
wafers
min 0.6326, 0.2182
minute
0.2
average
best case bottleneck
WIP
throughput throughput
theoretical
rate rate
cycle time
=
≈
≈
≈
wafers
182
minute
(6)
()
()
-
max ,
513.9 wafers
max 812.4 minutes,
wafers
0.2182
minute
max 812.4 minutes, 2355.5 minute
average
best
WIP
case theoretical
cycle cycle time
bottleneck
time
throughput
rate
=
≈
≈
{}
s
2355.5 minutes≈
(7)
NOTE 1: For this average WIP level, the best-case cycle time
was not determined by the theoretical cycle time, but by the
bottleneck throughput rate. Thus, a simple metric like
(average cycle time)/(theoretical cycle time) underestimates
how well the factory is doing.
SEMI E124-1103 © SEMI 2003 15
(
)
-
-
-
2355.5 minutes
2592.0 minutes
90.88%
best case cycle time
throughput rate and
cycle time efficiency
average cycle time
=
≈
≈
(8)
(
)
(
)
(
)
()
wafers
812.4 minutes 0.2182
minute
177.3 wafers
critical theoretical bottleneck
WIP cycle time throughput rate
=×
≈×
≈
(9)
()
[][][][]
maximum
average
number of
number
units processed
of tools
simultaneously
in
on a tool of
equipment
equipment
type
type
275 225 11 125 waf
process
capacity
eE
e
e
=×
∈
= × + × +×+×
∑
ers
150 50 1 25 wafers
226 wafers
=+++
=
(10)
()
(
)
(
)
{
}
()( )
{}
{}
{}
min ,
max ,
min 513.9, 177.3 wafers
max 513.9, 177.3 wafers
177.3 wafers
513.9 wafers
34.49%
critical average
WIP WIP
WIP
efficiency
critical average
WIP WIP
=
≈
≈
≈
(11)
() ()
()()
-
-
0.9087 0.3449
31.34%
throughput rate
production WIP
and cycle time
efficiency efficiency
efficiency
=×
≈×
≈
(12)
(
)
()()
()()
{}
{}
[]
2
2
2
2
1
1
log
min ,
1
513.9 177.3 1 wafers
log
min 513.9, 177.3 wafers
1
690.2 wafers
log
177.3 wafers
1
log 3.894
1
1.961
normalizing
exponent
average critical
WIP WIP
average critical
WIP WIP
=
+−
≈
+−
≈
≈
≈
≈ 0.5099
(13)
()
()
()
0.5099
0.3134
55.35%
normalizing
exponent
normalized
production
production
efficiency
efficiency
=
≈
≈
(14)
(
)
177.3 wafers
226 wafers
78.43%
critical WIP
balance
efficiency
process capacity
=
≈
≈
(15)
() ()
()()
0.5535 0.7843
43.41%
normalized
volume balance
production
efficiency efficiency
efficiency
=×
≈×
≈
(16)
(
)
891,642.1 wafers
938,571.0 wafers
95.00%
g
ood unit equivalents out
test
yield
finished units out
=
≈
≈
(17)
(
)
()( )
()()
938,571 wafers
938,571 wafers 46,929 wafers
938,571 wafers
985,500 wafers
95.24%
finished units out
line
yield
finished units out scrapped units out
=
+
=
+
=
≈
(18)
SEMI E124-1103 © SEMI 2003 16
(
)
(
)
(
)
()()
0.9524 0.9400
90.48%
yield line test
efficiency yield yield
=×
≈×
≈
(19)
(
)
(
)
(
)
()()
0.4341 0.9048
39.27%
overall factory volume yield
efficiency efficiency efficiency
=×
≈×
≈
(20)