Math in the Workplace - Algebra
MICRON TECHNOLOGY, INC.,
Semiconductor Manufacturing
Engineer - Yield
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Job Description: Develop
wafer level test strategies and test programs. Provide failure
analysis reporting. Monitor device yields, failure rates,
and repair rates. Interact with various engineering and product
groups to optimize device yields and minimize costs. |
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Problem:
Following the fabrication process of memory chips, wafers are tested
for functionality. Wafers are tested with voltage that stresses
performance causing those devices that do not meet specifications
to fail. "Yield" refers to the number or percentage of acceptable
units produced on each wafer compared to the maximum possible
Yield vs. Parameter
Use graph paper to create an x-y graph of yields vs. electrical
parameters measured in volts.
| Parameter |
Yield |
| 5v |
50% |
| 10v |
60% |
| 15v |
70% |
a. How does the parameter relate to the yield?
(Positive vs. negative correlation)
b. Where do we want the parameter to be for
the highest yield?
c. What’s the equation of the line?
Y = mx+b

| Old Data |
|
New Data |
| Parameter |
Yield |
Parameter |
Yield |
| 5v |
50% |
20v |
80% |
| 10v |
60% |
30v |
30% |
| 15v |
70% |
40v |
20% |
d. We did more tests, raising the voltage for
the parameter. Plot both the old and new data. Now, where does
the graph say to set the volts?

MICRON TECHNOLOGY, INC. |

Solution:
Use graph paper to create an x-y graph of yields vs. electrical
parameters measured in volts.
| Parameter |
Yield |
| 5v |
50% |
| 10v |
60% |
| 15v |
70% |
a. How does the parameter relate to the yield? (Positive vs. negative
correlation)
Positive correlation - As voltage increases, the
yield percentage increases
b. Where do we want the parameter to be for the highest yield?
15v would be the parameter that produces the highest
yield.
c. What is the equation of the line?
Y = mx + b
50 = mx 5+b
60 = mx 10+b
m=2, b=40
Y=2x+40
| Old Data |
 |
New Data |
| Parameter |
Yield |
Parameter |
Yield |
| 5v |
50% |
20v |
80% |
| 10v |
60% |
30v |
30% |
| 15v |
70% |
40v |
20% |
d. We did more tests, raising the voltage for
the parameter. Plot both the old and new data. Now, where does the
graph say to set the volts?
Based on the new data, set the volts at 20
