Update of CMS Process Quality Control Sensor Meeting, CMS TK Week, 9.4.2003, CERN Florence Anna...
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Transcript of Update of CMS Process Quality Control Sensor Meeting, CMS TK Week, 9.4.2003, CERN Florence Anna...
Update of CMS Process Quality Control
Sensor Meeting, CMS TK Week, 9.4.2003, CERN
FlorenceAnna Macchiolo
Carlo Civinini
Mirko Brianzi
StrasbourgJean-Charles Fontaine
Jean-Laurent Agram
ViennaThomas Bergauer
Margit Oberegger
Anna Macchiolo, Sensor Meeting, 9th April 2003 3
Inter-calibration
Results: Good agreement in all the measurements except • Aluminum resistivity• Inter-strip resistance
Circulation of 15 Test-structures
Vienna Strasbourg FlorenceStrasbourg Florence ViennaFlorence Vienna Strasbourg
Anna Macchiolo, Sensor Meeting, 9th April 2003 4
Aluminum resistivity
Florence Vienna Strasbourg30210415061610 29.9 25.5 35.630210421850314 27 24.5 31.730210421738304 26.8 25.2 32.530220126124234 24.3 21 27.530220126124237 21.8 21.8 27.4
•Differences in the measured aluminum resistivity in the three labs are of the order of 20-25 %
•The corrections we have to apply to take into account additional resistive contributions (from the probe-card, cables, switching matrix) are of the same order of the Al resistances
•Further investigations are going on
Al in m per square
Anna Macchiolo, Sensor Meeting, 9th April 2003 5
Inter-strip resistance
•Since we are measuring currents of few pA the spurious currents introduced by the probe-card make a big difference.
• Our measurements must be intended as lower limits on the real resistance
• We are able to detect the cases where the specification
Rint > 1 G
is not respected
OBJECT_ID VIENNA SBG FLR30210321847706 22975 136541 5277430210421174025 14602 152151 5702830210921054623 33915 185462 45326130220621600117 22344 234265 26346430220822000117 16473 238639 160180
Rint in M
Anna Macchiolo, Sensor Meeting, 9th April 2003 6
Software update
The acquisition software has been made faster by:
Decreasing the LCR meter integration time for the CV on diode and on MOS, where we do not need extreme precision
Optimization of the LCR driver, cutting useless initialization and configuration at every step
The time needed for the full analysis of a standard moon has decreased (for example in Florence it takes now 23 minutes
instead of 48).
The analysis VIs have changed to remove infinite loops in the cases where the fit fails
Anna Macchiolo, Sensor Meeting, 9th April 2003 7
Results from last STM sets measured
are of good quality
• low metal resistivity
• low V fb
All the PQC measurements are inside specifications with the exceptions shown in the following …
Perugia 22-24-25-26-27
Vienna 8-9
Anna Macchiolo, Sensor Meeting, 9th April 2003 8
Perugia 24 (STM): defects on the surface of many structures
Early breakdown of one mini-sensor with the surface heavily damaged
Anna Macchiolo, Sensor Meeting, 9th April 2003 9
Perugia 25 (STM)
3 structures from Perugia 25 have low depletion voltage
Wafer resistivity around 10 K per cm
Our request is
3.5 < <7.5 K per cm
The surface current measured on the GCD is very high for one structure but Vfb is inside limit.
First time we don’t see the correlation between the two problems. Only one sensor has been shipped from this batch.
We suggested to reject the corresponding sensor.
Anna Macchiolo, Sensor Meeting, 9th April 2003 10
Perugia 15-16-17-18-19-23
Pisa 61-62-63
Karlsruhe 05
Vienna 11-12-13
Results from last HPK batches
100 < Vdepl < 250 V
Almost perfect for the PQC qualification. The only notable problem is the depletion voltage, much lower than our specification
Anna Macchiolo, Sensor Meeting, 9th April 2003 11
HPK bulk resistivity
• … but last HPK batches have a substrate resistivity over 4 Kper cm
•Our original request on wafer resistivity is
1.5 < < 3.0 K per cm
• HPK has asked to enlarge the range to
1.25 < < 3.25 K per cm
since the wafer supplier cannot assure narrower specifications
Depletion voltage
measured on the diode
Compiled will all data in DB
Series production
Anna Macchiolo, Sensor Meeting, 9th April 2003 12
STM bulk resistivity
Depletion voltage
measured on the diode Inside our specifications
3.5 < < 7.5 K per cm
Anna Macchiolo, Sensor Meeting, 9th April 2003 13
Dependence of PQC variables upon production time (1)
All the Vfb values outside our limits come from production weeks 209 and 210
Compiled with all the data inserted in the DB up to now
STM
HPK
Anna Macchiolo, Sensor Meeting, 9th April 2003 14
0
500
1000
1500
2000
2500
3000
Before week 220: resistivity around 27 m per square . Strip width at the mask nominal value of 10 m
After week 220: resistivity in the range 15-23 m per square.
From the strip profile it’s difficult to disentangle the contribution to the strip height of the passivation oxide and of the metal layer but we can clearly observe:
Increase of 1 m in the strip height
Decrease of about 2 m in the strip width
Sheet Structure: Al strip profile measured with
a Scanning Near-field Optical Microscope (SNOM)
at LENS - european laboratory for non-linear spectroscopy
Fluctuations in the Al resistivity probably due to the fact that the numbers of squares used in the calculation was not correct (STM communicated the new numbers in October 2002).
10 m
7.7 m 2.7 m 1.6
mMetal resistivity in STM
Anna Macchiolo, Sensor Meeting, 9th April 2003 15
0
500
1000
1500
2000
2500
3000
10 m
7.7 m 2.7 m 1.6
m
2.7 m
1.6 m20 m
18 m
Metal strips in the Sheet Structure (STM)
302 104 203 870 17 : = 26.5 mper square
302 104 238 602 09 : = 20 mper square
Anna Macchiolo, Sensor Meeting, 9th April 2003 16
Dependence of PQC variables upon production time (2)
0.5 < Cint < 1.3 pF
0.5 < Cint < 1.3 pF
Cac > 16 pF
Cac > 18 pF
STM STM
HPK
HPK