Update of CMS Process Quality Control Sensor Meeting, CMS TK Week, , CERN Florence Anna Macchiolo Carlo Civinini Mirko Brianzi Strasbourg Jean-Charles Fontaine Jean-Laurent Agram Vienna Thomas Bergauer Margit Oberegger

Anna Macchiolo, Sensor Meeting, 9th April Overview  Conclusions from the inter-calibration process  Software update  Results from the last measured batches Karlsruhe 5 HPK W1 Tid Vienna HPK W4 Perugia HPK IB1 / IB2 Pisa HPK IB1 / IB2 Vienna 8-9 STM W7A / W7B Perugia STM OB1 / OB2  Wafer resistivity in HPK  Stability of our results

Anna Macchiolo, Sensor Meeting, 9th April Inter-calibration Results: Good agreement in all the measurements except Aluminum resistivity Inter-strip resistance Circulation of 15 Test-structures Vienna Strasbourg Florence Strasbourg Florence Vienna Florence Vienna Strasbourg

Anna Macchiolo, Sensor Meeting, 9th April Aluminum resistivity Differences in the measured aluminum resistivity in the three labs are of the order of % 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 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 Rint in M 

Anna Macchiolo, Sensor Meeting, 9th April 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 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 Vienna 8-9

Anna Macchiolo, Sensor Meeting, 9th April 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 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 Perugia Pisa Karlsruhe 05 Vienna 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 HPK bulk resistivity … but last HPK batches have a substrate resistivity over 4 Kper 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 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 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 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 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  m Metal resistivity in STM

Anna Macchiolo, Sensor Meeting, 9th April  m 7.7  m 2.7  m 1.6  m 2.7  m 1.6  m 20  m 18  m Metal strips in the Sheet Structure (STM) :  = 26.5 m  per square :  = 20 m  per square

Anna Macchiolo, Sensor Meeting, 9th April Dependence of PQC variables upon production time (2) 0.5 < Cint < 1.3 pF Cac > 16 pF Cac > 18 pF STM HPK