Update of CMS Process Quality Control

Florence

Anna Macchiolo Carlo Civinini Mirko Brianzi

Strasbourg

Jean-Charles Fontaine Jean-Laurent Agram

Vienna

Thomas Bergauer Margit Oberegger

Sensor Meeting, CMS TK Week, 9.4.2003, CERN

Inter-calibration

Circulation of 15 Test-structures

Vienna Strasbourg Florence Strasbourg Florence Vienna Florence Vienna Strasbourg

Results: Good agreement in all the measurements except • Aluminum resistivity • Inter-strip resistance

Anna Macchiolo, Sensor Meeting, 9th April 2003 3

Aluminum resistivity

Al r in m W per square 30210415061610 Florence 29.9

Vienna Strasbourg 25.5

35.6

30210421850314 27 24.5

31.7

30210421738304 30220126124234 30220126124237 26.8

24.3

21.8

25.2

21 21.8

32.5

27.5

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 Anna Macchiolo, Sensor Meeting, 9th April 2003 4

Inter-strip resistance

OBJECT_ID 30210321847706 30210421174025 30210921054623 30220621600117 30220822000117 Rint in M W

VIENNA SBG FLR

22975 136541 52774 14602 152151 57028 33915 185462 453261 22344 234265 263464 16473 238639 160180 •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

W is not respected Anna Macchiolo, Sensor Meeting, 9th April 2003 5

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 6

Results from last STM sets measured

Perugia 22-24-25-26-27 Vienna 8-9 ...

are of good quality • low metal resistivity • low V fb All the PQC measurements are inside specifications with the exceptions shown in the following … Anna Macchiolo, Sensor Meeting, 9th April 2003 7

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 8

Perugia 25 (STM)

3 structures from Perugia 25 have low depletion voltage Our request is 3.5 < r <7.5 K W per cm Wafer resistivity around 10 K W 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 9

Results from last HPK batches Perugia 15-16-17-18-19-23 Pisa 61-62-63 Karlsruhe 05 Vienna 11-12-13

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 10

•Our original request on wafer resistivity is 1.5 < r < 3.0 K W per cm

HPK bulk resistivity

Compiled will all data in DB

Depletion voltage measured on the diode • HPK has asked to enlarge the range to 1.25 < r < 3.25 K W per cm since the wafer supplier cannot assure narrower specifications Series production • … but last HPK batches have a substrate resistivity over 4 K W per cm Anna Macchiolo, Sensor Meeting, 9th April 2003 11

STM bulk resistivity

Depletion voltage measured on the diode

Inside our specifications

3.5 < r < 7.5 K W per cm Anna Macchiolo, Sensor Meeting, 9th April 2003 12

Dependence of PQC variables upon production time (1)

Compiled with all the data inserted in the DB up to now All the Vfb values outside our limits come from production weeks 209 and 210 STM HPK

Anna Macchiolo, Sensor Meeting, 9th April 2003 13

Metal resistivity in STM Sheet Structure: Al strip profile measured with a

Scanning Near-field Optical Microscope (SNOM)

at

LENS

european laboratory for non-linear spectroscopy 7.7 m

m

Before week 220: resistivity around 27 m W per square . Strip width at the mask nominal value of 10 m m 10 m

m

After week 220: 15-23 m W resistivity in the range 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 m in the strip height Decrease of about 2 m m in the strip width 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) .

Anna Macchiolo, Sensor Meeting, 9th April 2003 14

1000 500 0 -500 3000 2500 2000 1500 Metal strips in the Sheet Structure (STM) 302 104 203 870 17 : r = 26.5 m W per square 302 104 238 602 09 : r = 20 m W per square 18 m

m

20 m

m

238 602 09 medium strip 203 870 17 medium strip 7.7 m

m

10 m

m

Anna Macchiolo, Sensor Meeting, 9th April 2003 15

Dependence of PQC variables upon production time (2)

Cac > 16 pF STM 0.5 < Cint < 1.3 pF STM Cac > 18 pF HPK 0.5 < Cint < 1.3 pF HPK

Anna Macchiolo, Sensor Meeting, 9th April 2003 16