DEPFET development at the MPI Semiconductor Laboratory

DEPFET development at the MPI Semiconductor Laboratory

Gerhard LutzMPI-Semiconductor Laboratory, MnchenVertex2003Lake Windermere, Sept.16, 2003

ContentIntroduction DEPFET detector-amplifier structurePrinciple and propertiesApplicationsDEFETs as pixel detector In x-ray astronomy (XEUS)In particle colliders (TESLA)DEPFET production in MunichVertex detector for TESLADetector thinning technologyReadout electronicsSummary and conclusions

Introduction

DEPFET detector development at Munich is part of our activities in connection with instute experimentsOwn laboratory is supported by two Max-Planck InstitutesActive in particle physics and astrophysics (X-ray astronomy)Complete semiconductor processing line in houseDetectors mostly based on own conceptsPresent major project: DEPFET pixel detectors

The Depleted Field Effect Transistor (DEPFET)Kemmer+Lutz 1985 Device concept: Combination of FET transistor with Sideward depletion (Drift chamber) Gatti + Rehak 1984

DEPFET properties

Field effect transistor on top of fully depleted bulk All charge generated in fully depleted bulk assembles underneath the transistor channel steers the transistor current Combined function of sensor and amplifier low capacitance and low noise Signal charge remains undisturbed by readout repeated readout Complete clearing of signal charge no reset noise Full sensitivity over whole bulk Thin radiation entrance window on backside DEPFET structure and device symbol

Operation modes of DEPFET

DEPFET operation properties Charge collected and stored in internal gate both in transistor on mode and also in transistor off mode Charge is not destroyed by measuring itDEPFET operation modes:Normally on (continuous operation, occasional reset) real time operationNormally off (charge collection in powerless condition) integration mode operation

Simulations operation modesReal time mode:Signal collection with DEPFET onReal time signal processing (shaping)Clear internal gate from time to timeDrain currentDrain currentCharge in internal gateApplications:Readout element of drift detectorsor CCDs

Simulations operation modesIntegration and Sample mode:Signal collection with turned off DEPFETTurn on DEPFET by gate First current measurementClear internal gateRemeasure current and take difference Drain currentDrain currentCharge in internal gateApplications:Building block of pixel detectors Readout element of drift detectors

DEPFET types:MOS-depletionMOS-enhancementJFETOpen (rectangular) geometryClosed (circular) geometry

DEFET applicationsReadout element ofDrift detectorCCDElement of pixel detector

DEPFET 55Fe Spectrum Single DEPFET (JFET, closed geometry)

At room temperature

Cooled

MPI experiments needing DEPFETsX-ray astronomy: XEUS (next generationEuropean X-ray observatory) successor of XMM-Newton

Particle physics: TESLA vertex detector

Both experiments need pixel detectors

DEPFET pixel matrix Read filled cells of a row Clear the internal gates of the row Read empty cellsDifference of readings (filled/empty) mesures chargeLow power consumption

Fast random access to specific array regions

Prototype DEPFET-Systemdeveloped with Bonn University 64 x 64 matrix with 50 x 50 m2 pixel designed for Biomedical Applications clock rate : 50 kHz achieved noise in matrix: ~50e64x64 pixel DEPFET-MatrixJFET typeClosed geometry(50x50m2 pixel)low noiseReadout-Chip:CARLOSControl-Chip:Switcher

results with prototype systemspatial resolution: ~ 9m(with 50x50 m2 pixel)~ 3.2 mmMatrix-picture with 55Fe:[J.Ulrici, Bonn]Autoradiography with 3H:~ 10 mmdetection of Tritium 3H(5,6keV mean energy)

MPI semiconductor laboratory... with modern, custom made facilities ...... for a full 6 silicon process line 800 m cleanroom up to class 1 ...

Future X-ray Mission: XEUS (X-ray Evolving Universe Spectroscopy) Experiment Increase in collecting area (factor 100)Increase of collection area (0.5 to 6-30m2)Increase in focal length (7.5 to 50m)Optics and focal imaging on separate satellites Focal detector requirements: faster readout (factor 10 to 100) avoidance of ''out of time'' eventslarger size focal detector (7x7cm2)smaller pixel size (5050m2)Detector requirements can be met with DEPFET pixel detectorsScientific aim: investigation of the universe at an early evolution stage: - early black holes - evolution and clustering of galaxies - evolution of element synthesis6% out of time events in XMM

Present DEPFET pixel detector development forXEUS and TESLA Total > 500 MPixel (with 25x25 m Pixelsize)(read out speed 50 MHz)Options:CCDMAPSHAPSDEPFETTESLA vertex detectorThinFastLow powerIn collaboration with Bonn (N.Wermes) and Mannheim (P.Fischer)

LayerModule size No. Of modulesI13 x 100 mm1 x 8II22 x 125 mm2 x 8III22 x 125 mm2 x 12IV22 x 125 mm2 x 16V22 x 125 mm2 x 20

Design of DEPFET pixel detectorsType of DEPFETS:MOS-depletion typeXEUS: zylindrical geometryTESLA: rectangular geometry

Technology:6 InchDouble-poly, double metal,Self-aligned

DEPMOS Technology Simulation DEPMOS pixel array cuts through one cellAlong the channelPerpendicular to the channel Metal 2

Metal 1

Oxyd Poly 2 Metal 2 Metal 1 Poly 2 Clear Gclear ChannnelpDeep nn+Deep pPoly 1

Pixel prototype production (6 wafer)for XEUS and LC (TESLA)Many test arrays- Circular and linear DEPFETS up to 128 x 128 pixels minimum pixel size about 30 x 30 m - variety of special test structures

Aim: Select design options for an optimized array operation (no charge loss, high gain, low noise, good clear operation) On base of these results => production of full size sensors

Structures requiring only one metalization layerProduction up to first metal layer finishedDevices are under testTest results agree very well with device simulations

First DEPFET measurements on rectangular test transistors (W = 120m L = 5m)Output characteristics:

Correct transistor behavior

Transfer characteristics:

Device can be completely switched off

Transistor parameters agree with simulation

DEPFET test results: Noise and SpectroscopySingle circular DEPFETL = 5 m, W = 40 mtime-continuous filter, = 6 sec

Rectangular double cell test structureas used in TESLA pixel prototype

DEPFET test results Clearing of internal gate:complete clearing possible?At which voltage?Single rectangular DEPFET: measure current with cleared internal gateAs function of clear voltage

Measure pedestal noiseCompare situation of charge generation followed by single clear pulse with many clear pulses before readingSingle clear pulseMany clear pulses

Messungen

MessungU PDU out1 hi [V]I lo [A]U out1 lo [V]I hi [A]Delta IBemerkungen

13-10-1.169.91-6.6083.4373.51Ga 0V

14-10-3.845.59-10.76139.6494.05Ga 1V

15-10-3.4841.26-10.76139.6498.38

16-10-2.9233.70-10.76139.64105.95ohne Terminator

17-10-2.6830.45-10.8140.18109.73

18-10-2.6830.45-10.8140.18109.73

19-10-2.6830.45-10.76139.64109.19

20-10-2.6029.37-10.44135.32105.95

21-226.6852.30-1.56163.65111.35Ga 1,5V

22-227.0846.890.44136.6289.73

23-229.7211.224.5281.4970.27

24-226.5254.46-4.12198.24143.78

25-227.8436.62-4.16198.78162.16

26-223.6493.380.2139.8746.49

27-225.1273.380.24139.3365.95

28-227.4442.030.48136.0894.05

29-226.9648.510.4137.1688.65

30-228.3230.140.4137.16107.03

31-227.5240.950.24139.3398.38

32-227.5240.950.24139.3398.38

33-227.6039.870.32138.2498.38

34-227.6439.330.32138.2498.92

35-227.6838.780.4137.1698.38

36-227.5240.950.72132.8491.89

37-227.5240.950.64133.9292.97

38-227.6039.871.04128.5188.65

39-227.6039.870.96129.6089.73

40-227.9235.540.8131.7696.22

41-227.6838.780.4137.1698.38

Clearfrequenz Diagramm

128.739729729737.9289189189

117.938918918939.02

104.259459459538.8540540541

91.286486486538.8540540541

81.556756756838.3135135135

72.097297297338.0432432432

65.881081081137.9081081081

61.82702702737.9081081081

58.718918918937.2324324324

56.286486486536.9621621622

48.313513513535.6108108108

44.238378378434.6437837838

38.968108108132.887027027

34.778918918930.9951351351

31.498378378429.0659459459

29.336216216228.9308108108

29.038918918928.7145945946

28.795675675728.62

I hi (vor Clearpuls)

I lo (nach Clearpuls)

n [Hz]

I lo [A]

I in Abhngigkeit von nClear

Clearfrequenz

bulkRK/GRGa1Dr1Ga2Dr2Cl loCl hiCl widthCl-G loCl-G hiCl-G widthCl-G delay

6-50-1-5-3-528100055025

n [Hz]I PD [A]U out1 hi [V]I lo [A]U out1 lo [V]I hi [A]Delta IBemerkungen

0.1159.013.9637.93-2.76128.7490.81

0.2159.023.8839.02-1.96117.9478.92

0.3134.802.138.85-2.74104.2665.41

0.4134.802.138.85-1.7891.2952.43

0.5134.802.1438.31-1.0681.5643.24

0.6134.802.1638.04-0.3672.1034.05

0.7134.802.1737.910.165.8827.97

0.8134.802.1737.910.461.8323.92

0.9134.802.2237.230.6358.7221.49

1134.802.2436.960.8156.2919.32

1.5134.802.3435.611.448.3112.70

2105.860.2734.64-0.4444.249.59

3105.860.432.89-0.0538.976.08

5105.860.5431.000.2634.783.78

1098.120.1129.07-0.0731.502.43

5098.120.1228.930.0929.340.41

10098.120