In-Line Process Control Solutions:
Film Thickness, Resistivity, and Uniformity
Problem: Provide a superior non-destructive
alternative to the 4-point-probe.
Solution: MultiMetrixs´
MPS-150/200/300, MS-FIS 200/300, and ACS-200/300
provide non-contact, non-destructive commercial In-Line alternative to the 4-point-probe.
Comparison Testing: 200mm silicon
wafer with ~ 1,000Â Cu deposited layer.
A 49-point measurement was
performed with a 4-point-probe and with MultiMetrixs´ MPS-200 system
on April 28, 2003.
At 49 points of measurement, both tools showed very similar results.
When 700 points measurement was taken by MultiMetrixs´ MPS-200 system,
some circular surface formations were noticed.
At 3,000 points of measurement, 9 concentric circles become clearly visible
on the wafer surface.
The circles were the artifacts of the polishing process and were not
detectable with the 4-point-probe.
Taking into account that:
a) 3,000-point measurement with RST-based tool takes
almost same amount of time as the 49-point measurement with a 4-point-probe,
b) RST-based method is contact-less and non-destructive,
c) RST sensors have smaller spot size and capable to map wafer uniformity
with greater resolution it is apparent that RST method is clearly superior
to 4-point-probe method.
Furthermore, RST method is superior to any non-contact metrology technique
in the electrical arena available on the market today.
The diagram below contrasts the differences between 4-point-probe and
MultiMetrixs´ RST method.
|
|
Number of Measured Spots
|
4-point-probe
|
MultiMetrixs´
MS-FIS 200/300
|
MultiMetrixs´
MPS-200/300
|
|
49
|
~120 sec
|
> 1 sec
|
~20 sec
|
|
700
|
~30 min
|
N/A
|
N/A
|
|
3,000
|
~120 min
|
N/A
|
~150 sec
|
|
|
Visual Representation of the Test Results
|
4-point-probe at 49 spots
|
MPS-200 at 3,000 spots
|
|
