SPiDeR First beam test results of the FORTIS sensor FORTIS 4T MAPS Deep PWell Testbeam results CHERWELL Summary J.J. Velthuis.

Jaap Velthuis, University of Bristol

SPiDeRFirst beam test results of the FORTIS sensor

• FORTIS• 4T MAPS• Deep PWell• Testbeam results• CHERWELL• Summary

J.J. Velthuisfor the

SPIDER collaboration

Jaap Velthuis, University of Bristol

SPiDeRFORTIS• FORTIS is the first 4T MAPS

aimed at Particle Physics• 0.18µm CMOS• 12µm epi layer• Uses INMAPS technology• 13 different type of pixels• Tested 3 types of sensors:

– Standard epi– Standard epi + deep Pwell

islands– High res epi + deep Pwell

islands

• Deep Pwell islands are first step towards in-pixel data processing

STFC IP STFC IP

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STFC IP

Jaap Velthuis, University of Bristol

SPiDeRMAPS

• Charged particle generates free charge carriers in epitaxial layers.

• Due to doping profiles, electrons are confined to epitaxial layer.

• Electrons diffuse.• When close to diode

electrons collected

Jaap Velthuis, University of Bristol

SPiDeRFORTIS

• FORTIS is the first 4T MAPS for Particle Physics– 3T CMOS

• Simple architecture• Readout and charge collection node are the same

– 4T CMOS• Three additional elements• Readout and charge collection area are at different

points

Jaap Velthuis, University of Bristol

SPiDeR4T Pixel Advantages• Low Noise

– readout node separated from charge collection area

– The reset noise and pixel fixed pattern noise (FPN) can be removed by in-pixel correlated double sampling read out (CDS)

• High Conversion Gain– Charge is collected on large

diode then transferred to the floating diffusion

– Large C gives larger depleted area and complete charge collection

– Small C yields large gain

e-e-

V = q/C small

V = q/C large

5

Jaap Velthuis, University of Bristol

SPiDeRDeep Pwell• Problem in MAPS:

– PMOS electronics need Nwell

– Nwell acts as charge collection diode

– So can’t make PMOS without losing huge amount of Q

• New development: make deep pwell with Nwell inside can do CMOS– Road to data processing in

pixel

• Some FORTIS have empty deep pwell islands to test effect of Q collection

Jaap Velthuis, University of Bristol

SPiDeRSubstrate Resistivity

• High resistivity (intrinsic) silicon enlarges the depletion region to fully occupy the pixel– Majority of deposited

charge now falls in a depletion region and is collected by electric field

– Improved charge collection efficiency

– Faster charge collection (drift vs diffusion)

• Some FORTIS have high res

Jaap Velthuis, University of Bristol

SPiDeRSome test beam

pictures

Jaap Velthuis, University of Bristol

SPiDeRWe see hits…

• Beam at SPS

• 120 GeV pions

• Using EUDET telescope

C2

on F

1.1

hig

h r

es

Jaap Velthuis, University of Bristol

SPiDeREUDET telescope

• Telescope 6 planes, 18.4µm pitch, binary readout– single hit resolution: 18/√12=5.3µm

• FORTIS at 572 mm

• Simulated telescope error 3.2±0.2µm– Consistent EUDET values, only is different error in X and Y

(see talk Ingrid Gregor)

simulation

Jaap Velthuis, University of Bristol

SPiDeRC-structures• 4 test pixels:

– 128 × 128 pixels– 15µm pitch– C structures have different W and L for

source follower

• Three different wafers– standard epi – standard epi plus Deep PWell islands – high resistivity epi plus Deep PWell

islands plus implant to prevent FD and diode from merging

• Read out speed 15 frames per second

STFC IP

STFC IP

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Jaap Velthuis, University of Bristol

SPiDeRC-structures: Noise• Noise is spread around pedestal after hit

removal• All 4 pixel types have same noise.• Difference in noise between various wafers

minimal– 21.9 ADC high resistivity plus Deep PWell

islands – 20.3 ADC Standard epi– 18.7 ADC Standard epi + deep PWell islands DPWHres Std

Jaap Velthuis, University of Bristol

SPiDeRC-structures: Signal• Cluster search: seed 5×noise, neighbours 2×noise,

max cluster size 5×5 pixels• Low signal peaks due to incomplete clusters.• Signals in standard epi + deep Pwell islands

highest• Signals in high res epi layer lowest.

– Naively expected to be higher: high res should increase depleted area and thus charge collection efficiency

DPWHres Std

Jaap Velthuis, University of Bristol

SPiDeRC-structures: Cluster

size

• Cluster size for high res much larger. – Charge travels much further– Charge per pixel much lower

• Deep PWell islands no effect cluster size

DPWHres Std

Jaap Velthuis, University of Bristol

SPiDeRC-structure: summary

table

• First time a 4T structure was successfully used for the detection of MIPs

• S/N ratios very high– S/N>100

Jaap Velthuis, University of Bristol

SPiDeRC-structures: position resolution

• Positions reconstructed using: – CoG, – 2 pixel clusters– eta

• Resolution worse for High res: due to large charge spread.

• Number still contains 3.2µm telescope uncertainty

DPWHres Std

Jaap Velthuis, University of Bristol

SPiDeRC-structure: summary

table (II)

• Resolutions corrected for telescope uncertainty. Large errors due to uncertainty in telescope error.

• Algorithms do not make much difference in resolution indicating that the charge division is reasonably linear.

Jaap Velthuis, University of Bristol

SPiDeRThe future: Cherwell

• Uses Deep Pwell and 4T to achieve 100% fill factor with integratedsensor and readout electronics

• Incorporation of complex logic within a pixel

• Investigation of data reduction/clustering

– CDS in-pixel and in-pixel amplification– Low power using rolling shutter readout

• First attempt housing ADC in the islands has been received.

4T

SELECT

COL

RESET

4T

COL

4T

COL

50 um pixel boundary

1xSRAM

4T

SELECT

COL

RESET

4T

COL

4T

COL

50 um pixel boundary

1xSRAM

Pixel

Bo

un

dary

Jaap Velthuis, University of Bristol

SPiDeRSummary• FORTIS is first 4T MAPS for Particle Physics• Using the Deep Pwell technology, we can incorporate full

CMOS circuits in pixel.• Tested three different wafers:

– Standard epi– Standard epi with Deep Pwell islands– High resistivity epi with Deep Pwell islands

• Deep Pwell islands have no detrimental effect on the signal.• FORTIS works really well:

– S/N>100 observed for 15µm pitch pixels– Position resolution <2µm

• Cherwell: first device with ADC in deep Pwell islands has been received.

• We thank the EUDET collaboration for the provided infrastructure and travel funds