Testing Site Qualification

• Purpose: – Perform detailed scans of the silicon microstrips to

make sure they all work.

– Check HPK.

• Candidates for Certification: – Kansas State University (KSU)

– Stony Brook (SB)

– Fermilab

Measurements to be Done on All Strips

– Measurement Bad Strip• Idiel >10 nA (PINHOLE)

– current through the coupling capacitance

• Cac > 1.2*mean (OPEN)

– coupling capacitance < 0.8*mean (SHORT)

• Istrip > 10 nA (LEAKY)

– leakage current to a strip

• Rpoly > 1.1 MOhm or < 0.5 MOhm

– polysilicon resistance

• SB measures on strips, KSU on test structures

• Rint < 2 GOhm – interstrip resistance

• Cint > 4.65 pF (L1)– interstrip capacitance > 5.90 pF (L2)

Whole Detector Measurements

• CV > 300 V– measure capacitance versus voltage– determine FDV

• IV – measure current up to 500 V (L2) > 16 A at 350V– measure current up to 800 V (L0,1) > 4 A at 700V

• bad strips > 1%

Measurement Bad Detector

Done also by Fermilab

KSU

SB

Rochester

Equipment

probe station Alessi 6100 Alessi 6100strip probes 3 4bias line probe (rides chuck) 1 1Source Measure Unit (voltage source with picoammeter) Keithley 237 Keithley 237voltage source Keithley 487 Keithley 487Picoammeter Keithley 487 Keithley 487LCR meter HP 4284 Agilent4263B4 X 8 Matrix Switch HP34904A HP34904A

Both groups use the matrix to perform multiple tests while only touching each pad once. KSU scans the even and odd pads separately, since the AC pads are staggered. The three probes are used for the AC pad and DC pad of each strip, plus a neighbor AC pad (an additional touch). SB touches AC and DC pads of neighboring strips and completes the scan in pairs. One probe always even, one always odd. This enables interstrip measurements at the same time.

KSU SBItem

HP 34904A Matrix Switch

C 1 2 3 54

R

4

3

2

1

876

HP 4284LCR

K487 pA meter

K237 SMU

H L

chuck

AC1DC2

DC1

bias

Kansas State U Plan for use of the Matrix

K487 Voltage Source

matrix connection

connection

H

H HL L

L275 k 275 k

HP 34904A Matrix Switch

C 1 2 3 54

R

4

3

2

1

876

Agilent 4263B LCR

K487 pA meter

K237 SMU

54 nF

54 nF

470 k

470 k

H

H

H

L

L

L

chuck AC2AC1DC2DC1

bias

Stony Brook Plan for use of the Matrix

K487 Voltage SourceH

matrix connection

connection

Idiel for ELMA sensor L1-010

0

1

2

3

4

5

6

7

8

9

10

0 50 100 150 200 250 300 350 400 450

strip num ber

Idie

l (n

A)

Idiel for L1_010

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0.1

0.11

0.12

0.13

0.14

0.15

0.16

0.17

0.18

0.19

0.2

0 50 100 150 200 250 300 350 400 450

strip num ber

Idie

l (n

A)

SB

KSU

Polysilicon Resistance of Each Strip on L1_010

1200

1250

1300

1350

1400

0 50 100 150 200 250 300 350 400 450 500

strip num ber

Rp

oly

(kO

hm

)

SB

KSU

Measurement Techniques

bias voltage All measurements at FDV+20V. All measurements at FDV+20V.

Idiel put 20 V on DC pad and measurecurrent (K487) to AC pad near ground

put 80V on AC pad and measure currentout of SMU to bias line at ground.

Cac measure capacitance between the ACpad and the DC pad with neighborf = 1 kHz

measure capacitance between the ACpad and the bias linef = 100 Hz now (but 1 kHz for L1-010)

Istrip measure current to the DC pad atground with the K487

measure current to the DC pad at groundwith the K487

Rpoly apply a voltage to the DC pad with theK487 and measure the current with theK487 to the bias line at ground

apply a voltage to the DC pad with theSMU and measure current with the SMUto the bias line at ground

Cint measure capacitance between the twoAC pads

Condint Apply a voltage with the SMU to oneDC pad and measure current to aneighbor at ground with the K487

KSU SB

Measurement Procedures• Repeat obviously bad measurements:

– The bias line loses contact: Strip currents approach the total leakage current.– SMU mode problem: Rpoly is infinite and Idiel is very small for all strips.– [Neither of these has caused a problem recently.]

• Remeasure bad strips, to see if the problem is a result of bad contact.– If the bad measurement value repeats once, the strip is called bad.

• At the end of the scan lift both probes to measure the background and do a two-strip scan. The background values of Idiel, Cac, Istrip, Cint, and Condint are then subtracted from corresponding values for all strips. (We should subtract conductances in measuring Rpoly, but do not bother since the correction is very small.) The background values are generally a small fraction of the bad strip limit.

Comparison of Results on Bad Strips

Sensor strip Kansas State Stony Brook SB remeasure Final

L2_014 none none none

L1_010 0 OK “pinhole” “pinhole” “pinhole”80 open OK OK OK239 pinhole, short pinhole, open pinhole, open pinhole240 pinhole, short pinhole, open pinhole, open pinhole241 pinhole, short pinhole, open pinhole, open pinhole242 pinhole, short pinhole, open pinhole, open pinhole243 pinhole, short pinhole, open pinhole, open pinhole247 pinhole, short pinhole, short pinhole, short pinhole, short316 OK Rpoly high OK OK376 open open open open380 OK short OK OK383 OK “pinhole” “pinhole” “pinhole”

So when the measurement repeats, KSU and SB agree.

4 L2 Sensor Comparison

• HPK and SB are higher than FNAL and KSU?

• Search for possible reasons:

• SB uses a different LCR meter from KSU and FNAL

• SB uses ceramic blocking capacitors in front of our LCR (low f)

sensor HPK FNAL SB KSUL2-77 120 105 130 106L2-96 120 105 120 106

L2-105 110 115 110 101L2-129 110 100 110 101

Full Depletion Voltage (HPK Method)

Deviation and 1/C*C vs Voltage

-1

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

0 50 100 150 200 250

Bias Voltage

Dev

iati

on

(%)

and

10/

(C(n

F)*

C(n

F))

Deviation

1/C*C

The SB 130V for L2-77 could be due to a fluctuation, in one value of C, weakness of the HPK method.

I leak L2-96

0100200300400500600700

0 200 400 600 800

bias(V)

I_le

ak (

nA

)

SB

KSU

FNAL

No Breakdown seen up to 500 V (L2 limit)

I leak L2-105

0

50

100

150

0 200 400 600 800

bias(V)

I_le

ak (

nA

)

SB

KSU

FNAL

I leak L2-129

0

50

100

150

200

0 200 400 600 800

bias(V)

I_le

ak (

nA

)

SB

KSU

FNAL

Hamamatsu L2-0129 1/C2 versus bias

0

0.0000001

0.0000002

0.0000003

0.0000004

0.0000005

0.0000006

0.0000007

0 50 100 150 200

bias (V)

1/C

2 (p

F-2) SB

KSU

FNAL

Hamamatsu L2-0129 I_diel

-1.5

-1

-0.5

0

0.5

1

1.5

0 100 200 300 400 500 600 700

strip#

I(nA

)

SB

KSU

FNAL

Hamamatsu L2-0129 Coupling Capacitance

20

40

60

80

100

120

0 100 200 300 400 500 600

strip#

Cap

(pF)

SB

KSU

FNAL

Hamamatsu L2-0129 I strip

-0.02

0.03

0.08

0.13

0.18

0 100 200 300 400 500 600 700

strip#

I(nA

)

SB

KSU

FNAL

Hamamatsu L2-0129 R_poly

0.66

0.68

0.7

0.72

0.74

0.76

0.78

0 100 200 300 400 500 600 700

strip#

R_p

oly SB

KSU

Number of Bad Strips

sensor HPK FNAL SB KSU KSU(bad contact/missed)

L2-77 0 0 0 1 3L2-96 0 0 2 created 2 0

L2-105 0 0 0 0 0(odd only)L2-129 0 0 0 0 8

Conclusions• KSU, SB, and Fermilab sensor probing sites are

fully equipped and operational• Equipment has arrived for the Rochester probing

site and is currently being setup– Rochester expected to probe inner layer sensors– Site will be certified in similar way as SB and KSU

• Bad contacts encountered during probing can be overcome

• No outstanding problems• Ready to probe the incoming sensors