This page describes the hardware setup for CROC wafer-level testing used in Torino.
Wafer probing hardware
This section describes the waferprobing-specific hardware such as the probe station or the probe card.
Block diagrams
- Powering (revision 1.1): wlt-power-v1_1
- Monitoring (revision 1.0): wlt-monitoring-v1
- Scan chain test (revision 2.2): wlt-sct-v2-2.pdf
Probe station
The probe station employed in the CROC wafer setup is the Cascade Microtech CM300Xi; this is a semiautomated probe station.
The probe station is connected to the controlling computer via a GPIB-USB cable.
CROC probe card v1.0
The first version of the CROC probe card. It is compatible with the RD53 DAQ but with improvements aimed at improving the versatility of the probe card.
Features of the CROC probe card include:
- added pin header in order to share I2C lines and monitoring signals with the auxiliary waferprobing card (WPAC). This separates high speed lines in the DisplayPort from slow control signals;
- added jumpers to select between the WPAC and an FPGA for sending control signals to the chip (e.g.,
LP_EN
,SCAN
); - added jumpers to select between the source-meter unit and the WPAC for measuring the signals from the probe card.
The schematic for the v1.0 probe card can be found in the attached PDF.
CROC probe card v1.1
The second version of the CROC probe card, with improvements with respect to version 1.0.
The list of modifications and the schematic diagram can be found attached to this Wiki page.
CROC probe card v2
This is the probe-card for the production, with improvements wrt V1.1.
The list of modifications and the schematic diagram can be found attached to this Wiki page.
Wafer Probing Auxiliary Card (WPAC)
Auxiliary wafer probing card used mainly for slow control and monitoring.
The board is connected to the acquisition PC using a RS232-USB cable based on the FT232R chip. A micro-USB cable can be temporarily connected to the programming port of the mounted Arduino Due in order to upload the firmware of the ARM microcontroller.
The following figure describes the connections between the WPAC and the rest of the wafer-probing hardware.
The WPAC documentation, which includes the schematic diagram of the board, can be found attached to this Wiki page. Instructions to flash the firmware to the Arduino Due board are provided here.
Power Board
The power board allows to safely choose to power the CROC using:
- the internal regulator (in LDO or shunt-LDO mode);
- direct powering of
VDDA
andVDDD
. - allows to put in parallel VINA and VIND
The selection between these two powering modes is controlled by the WPAC.
The Power Board schematic diagram V2 can be found in the attached PDF.
Wafer probing setup with ProbeCard V2 and Power Board connected
Info on temperature sensors used in the probe-station
To calibrate the temperature sensors on the C-ROC, external sensors have to be used to set the temperature of calibration. The DS18S20 are used, also DS18S20-PAR could be used here
Two sensors have to be in contact with the probe-station chuck, that behaves as heat sink of the wafer under test. Sensors have to be connected to the WPAC, J2 pins 1,3 for data, pin 2 and 6 for power and GND.
DisplayPort cables
Connection | Length | Manufacturer id |
---|---|---|
DP1 | 1 m | 11.04.5634 A |
DP2 | 2 m | 11.04.5635 E |
DP3 | 2 m | 11.04.5635 E |
DAQ hardware
The CMS DAQ is based on an FC7 data acquisition board containing a Kintex 7 FPGA chip. The board is mounted inside a nanocrate.
A Kansas State University FPGA Mezzanine Card (FMC) in slot L12 is used to connect the FC7 to the probe card and the Single Chip Card. The schematics and the manual can be found at the previous links.
The wafer-level testing firmware to be used for the FC7 can be downloaded from CERNBox.
Instruments
This section describes the instruments (power supplies, source meter) present in the wafer-level testing hardware setup.
For powering the CROC chip under test by the probe card, two TTi QL355TP power supplies are used:
- the first QL355TP is used to provide
VINA
andVIND
to the chip using different (PWR_IN
) channels; - the second QL355TP has not been implemented yet in the setup but it will be soon. It will provide direct CROC powering (
PWR_VDD
= 1,2 V) to the probe card.
A third QL355TP is used to:
- power the SCC employed to debug the DAQ;
- power the Wafer Probing Auxiliary Card.
The choice of PWR_IN
or PWR_VDD
will be perfomed using the Power Board, which selects either one or the other powering scheme but never both.
Right now AUX_PWR
, which provides autonomous powering of VDD_PLL
and VDD_CML
, is available in the probe card but it is not used. Therefore, an additional power supply is not needed.
The output of the probe card LEMO can be measured using a Keithley 2400 or a Keithley 2401 source-meter unit.