Introduction to HEP Silicon at Cambridge

Software Support

We have developed and maintain support for comprehensive software packages used in silicon wafer testing, detector evaluation, and database interfaces. Our software is used in-house as well as by non-Cambridge institutes. The software includes:

LabView for wafer/detector testing, a suite of programs for IVscans, strip testing, depletion, stability etc, with automated file management and full analysis/plotting facilities.
LabView for analogue chip readout (FELIX, SCT128A), including full analysis of data with or without source.
Java GUI interface to the ATLAS SCT database. Can be run on any PC to generate spreadsheets, lists, html reports, test images, etc of items in the SCT database.
Perl/CGI web interfaces to view SCT barrel detector quality control data of Hamamatsu and Cambridge.

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Mask Design

We design detectors and pitch adaptors using 4-inch and 6-inch wafer technology using CADENCE Design Framework II running on a SUN Ultra1 workstation. Recent detector design projects include:

A p-on-n barrel detector for the ATLAS SCT
An n-on-n barrel detector prototype for the ATLAS SCT
Variable strip-pitch detectors for resolution optimisation studies at ATLAS test beams
Edge optimisation R&D for improved high voltage operation (funded by PPARC industrial award scheme)
A double-sided FOXFET biassed prototype detector for OPAL at LEP
The OPAL silicon detector

We have also designed customised pitch adaptors for specialised detector readout studies.

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Detector Test Facilities

We have dedicated cleanroom for the probing and testing of silicon devices. Our facilities include:

Summit 10K automatic (PC-controlled) probestation from Cascade Microtech

Wentworth manual probestation

K&S 4129 Deep Access Bonder

K&S 1470 automatic bonder for production wire bonding

Environment Chamber from Design Environmental Ltd for irradiated detector annealing and temperature cycling tests

Bosch freezers for irradiated detector storage and testing

Measurements are performed using a range of instrumentation from Keithley , Hewlitt-Packard , Wayne-Kerr and Pickering Interfaces:

Keithley 487 Volt Source/Picoammeter - "workhorse" for IV scans and I measurements / Vsource

Keithley 6517 Electrometer - IV scans, VV scans, High voltage source (up to 1000V)

Keithley 2000 DMM - for current, voltage, temperature measurements etc

WayneKerr 6425 - CV measurements from 30Hz to 300kHz

Hewlit-Packard 4263B - CV to 100kHz

Pickering 360-20 4x36 matrix for switching applications

All measurements (eg IV, CV, strip probing, etc) are generally fully automated under PC control (via IEEEbus) using LabView . LabView also manages data storage, analysis and plotting.

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Picture Gallery

LBIC/CDP binary irradiation assembly bonded to an irradiated ATLAS detector.

Closeup of bonding to LBIC/CDP Wires here are 25micron thick.

Bonding to a FELIX-128 analogue chip

IV measurements in progress The irradiated detector is in the freezer on the right.

Summit 10K automatic probestation

K&S Deep Access Bonder

K&S 1470 automatic bonder

Environment chamber

Strip probing with the Summit probestation

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Detector Readout

We use both analogue and binary readout systems for the evaluation of the devices as particle detectors, together with beta sources or laser.
The analogue SCT128A (and before that the FELIX) chips have been used extensively for Signal/Noise studies of irradiated detectors (using a Ru-106 beta source). For binary readout at 40MHz we have used reusable (rebondable) modules using LBIC/CDP and more recently ABCD systems for SCT strip noise studies.

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Personnel

Personnel involved directly with cleanroom activities are:

Janet Carter Group Leader
Dave Robinson Senior Research Associate
Brian Fromant Mechanical engineer / Cleanroom technician

Other group members working with silicon on ATLAS:

Maurice Goodrick Electronics engineer
John Hill DAQ
Andy Parker

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