1. 2004/09/07 Junkichi Asai (RBRC) (Kieran Boyle (SBU))
Sensor QA at BNL
2004/09/07
Junkichi Asai (RBRC)
(Kieran Boyle (SBU))
I would like to talk about the evaluation of Stripixel sensor at BNL.
I and Kieran study the sensor QA.

2. Contents Previous Evaluation of Stripixel Sensor Preparation
Result IV (leakage current –Voltage) CV (Capacitance-Voltage) (at BNL)
Preparation
Semi-automatic probe station
IV measurement with comb type
Effect of grounding other strips on IV measurement
Schedule of sensor QA
Development/production
These are the contents.
First, I will show the result of IV/CV measured previously at BNL with manual probe station.
Next, I will talk about the Semi-Automatic Probe station and Measurements with Switch System
Finally, I will show the schedule of sensor QA.

3. Setup for IV/CV measurement
Dark Box
Micro Scope
picture
Measured Needle to sensor pad
Grounded Needle to guard ring
Micro Scope
Measured Needle
Vacuum hole
wafer
Grounded Needle
chuck
These are the setup for IV/CV measurement.
In the dark box, the silicon wafer putted on the chuck.
In this picture, there are no wafer.
The bias voltage supplied to the chuck.
Because the pad size so small, the probe needle is contacted the pad of the wafer by watching through the microscope.
The grounded needle contacted the Guard ring.
With this manual station we measured leakage current and strip capacitance.
Later I would like to talk about semi-automatic station.
chuck
Bias Voltage
Because the pad size so small, the probe needle is contacted the pad of the wafer by watching through the microscope.
There are in the Instrumentation Division.

4. Result : IV/CV measurements
We found leakage current in the range of 100’s nA and capacitance in the 10s of pF range.
These are the result of leakage current and capacitance measurement.
The x axis is bias voltage, y axis are the current and capacitance.
We found dark current in the range of 100’s of nA and capacitance in the 10s of pF range.
400um strip sensor

5. Effect of grounding other strip
Micro Scope
100
Measured Needle to sensor pad
Grounded Needle to guard ring
Leakage current (uA)
10-1
With Grounded Needle to neighbor pad
decrease current
10-2
wafer
10-1
10-1
100
101
102
103
Grounded Needle to neighbor pad
chuck
Bias Voltage (V)
For these measurements, an adjacent channel was grounded. The leakage current decreases by around 1/3.
Bias Voltage
We measured the leakage current for effect of grounding other strip.
For the measurement, another one needle grounded on the neighbor pad.
The leakage current decreases by around 1/3.

6. Why Semi-Automatic Probe station
With the present manual probe station, measuring one entire wafer (200 measurements) takes ~ 2 weeks.
To speed up, We use the Semi-Automatic Probe Station
With the present manual probe station, measuring one entire wafer (200 measurements) takes ~ 2 weeks.
To speed up, we use the Semi-Automatic Probe Station.

7. Setup Semi-Automatic Probe station
Microscope
Dark Box
Windows LabView controlled All device through GPIB cable.
Ribbon Cable
Probe card
Probe positioner
for Guard Ring
Probe stage
HV/Ammeter
Keithley 6487
Windows LabView
sensor
chuck
The semi-automatic probe station consist of these device pictured here.
This probe station has a movable chuck which the silicon wafer is placed on.
With the microscope, we can check the contact of the sensor pad and the needles.
For the measurement, we use a probe card, it has 128 needles.
For grounding the guard ring, we use a probe positioner.
A ribbon cable carries the signal to our switcher system.
All the devices are controlled by windows Labview software through GPIB cables.
The HV/Ammeter and LCR are connected to the scanners.
Now , this set up is in the Instrumentation Division.
But in September, they will be moved to the RIKEN Lab room in physics building.
In the room, the clean tent will be set up.
Then we can start measurements.
GPIB Cable
Movable stage
LCR Meter
Agilent 4263B
Switch system
Keithley 7002
Probe station
Early Oct., they will be moved to the RIKEN Lab room in physics building at BNL In the room, the clean tent will be set up. Then we can start measurement.

8. Probe Card 64 x strip needles By RUCKER & KOLLS, INC. 80um 330um
64 u strip needles
We see here the probe card.
It has 64 x and 64 u strip needles.
The dimensions are here.
One needle is used to measure, the other 127 are grounded.
We measure all 384 channels.
80um
One needle is used to measure, the other127 are grounded
Measurement all 384 pad of strip with overlap step by step
150um

9. Semi-Automatic Probe station with Imaging card
COMB type sensor
u pads
The needles contacted with the u pads
This is the pictured window of probe card needles and the u pad.
It was pictured by the Imaging card.
We can check without looking through the microscope.
This is the picture of the needles contacted with the u pads.
And this is the maximum zoom.
With this, we can check the contacting.
64 u needles of probe card
Maximum zoom
It was pictured by the Imaging card We can check without looking through the microscope.
Check the contacting

10. IV/CV measurement schematic
Chuck
GND Ring
n-1
measured
This is the IV/CV measurement schematic.
The keithley 7002 system controls these switches.
In the IV case, the switch is set this way.
In the CV case, the switch is set this way.
In the CV measurement of between strip by strip, the switches are connected like this.
Now. I am making the program.
Keithley 7002,7011,7153 switch system
Keithley 6487 HV/Ammeter
Agilent 4263B LCR Meter
CV Measurement (Between strip-strip)
CV Measurement
IV Measurement (Between strip-strip)
IV Measurement

11. Result of IV measurement with Semi-Automatic Probe station
Using COMB design for practice
Here is an IV for the semiautomatic probe station using COMB design for practice.

12. Effect of grounding other strips
GND needle: 14
GND needle: 10
GND needle: 6
GND needle: 4
GND needle: 2
GND needle: 1
GND needle: 0
Measured
This is the effect of grounding other strip on IV measurement with probe card and switch system.
I think it need at least 4 or 6 grounding needles for the 1 strip measurement.
We should QA test it with new sensor.
Needles of Probe Card
400um
Electric Field

13. Schedule of silicon sensor
Preproduction Sensor
Soon SINTEF 17 wafers are supposed to arrive at RIKEN, yesterday (9/6)
(500um, STD design, 2 type : sintering process deference)
They will be shipped to BNL and UNM, when clean room ready(?)
End of Sep. 20 sensors from Hamamatsu
(4 type : thickness=(500um, 625um) , design=(STD, New))
Clean Room
Early Oct. build at RIKEN Lab room in BNL
QA test
Now Programing Semi-Automatic station with LabView
Wiring (probe card, Scanner, HV/Am, LCR…)
should decide how to measurement
Sep. IV/CV measurement at UNM (with probe positoner)
Continue studying sensor response with probe card at BNL
Oct. IV/CV measurement at BNL
All wafers are expected to complete QA in Dec or earlier
Finally, I would like to talk about the schedule of silicon strip detector.