Development and Performance of. Kyoto s X-ray Astronomical SOI pixel sensor Sensor

Transcription

1 Development and Performance of 1 Kyoto s X-ray Astronomical SOI pixel sensor Sensor T.G.Tsuru (tsuru@cr.scphys.kyoto-u.ac.jp) S.G. Ryu, S.Nakashima, Matsumura, T.Tanaka (Kyoto U.), A.Takeda, Y.Arai (KEK), K.Mori, Y.Nishioka (U. Miyazaki), T.Kohmura (Kogakuin U.) + SOIPIX group T. Imamura, A. Iwata, T. Ohmoto, T. Maeda (A-R-Tec) for Chip Design Publication Ryu et al. IEEE NSS 21, Conf. Record XRPIX1-CZ -FI Ryu et al. IEEE TNS 58, 2528 (211) XRPIX1-CZ-FI Tsuru et al. IEEE NSS 211 Review Ryu et al. IEEE NSS 211, Conf. Record Event-Driven Readout system Nakashima et al. IEEE NSS 211, Conf. Record XRPIX-ADC1 Nakashima et al. Physics Procedia 37, 1373 (212) XRPIX1-FZ-FI Ryu et al. IEEE TNS 6, 465 (213) XRPIX1b-CZ-FI, Inter-pixel cross-talk Takeda et al. IEEE TNS 6, 586 (213) Event-Driven Readout with XRPIX1b-CZ-FI Tsuru et al. SPIE Astro212 Review Nakashima et al. NIM A, Accepted (213) XRPIX2 Matsumura NIM A in Prep. Charge Collection Efficiency 21319_SDW213_XRPIX_v8

2 Talk Plan 2 XRPIX the Kyoto s X-ray Astronomical SOI pixel sensor Spectral Performance Depletion Layer Trigger output and Event Driven Readout Charge loss at the interface between the depletion layer and SiO2 insulator

3 The standard Imaging Spectrometer of modern X-ray astronomical satellites X-ray CCD 3 Suzaku XIS Fano limited spectroscopy with the readout noise ~3e- (rms). Wide and fine imaging with the sensor size of ~2-3mm pixel size of ~3μm High QE by BI and thick depletion (2μm for ASTRO-H). Non X-ray background above 1keV is too high to study faint sources. The time resolution is too poor (~sec) to make fast timing obervation of time variable sources (eg. BH and NS). Non X-ray background of Suzaku XIS (BI) Due to high energy particles on orbit.

4 Sensor (high ρ, depleted Si) Insulator (SiO2) XRPIX = Monolithic SOI pixel sensor for future X-ray astronomical satellites X-ray V_back Electron Hole P+ BPW X-ray 4 non X-ray BGD (high energy particle) Fast CMOS (low ρ Si) Each pixel has its own trigger and analogue readout CMOS circuit. Target Spec. CMOS Readout CMOS Readout CMOS Readout V_sig Time Our SOIPIX (XRPIX) CMOS Readout scintillator on-board processor Very low BGD by anti-coincidence (1/1 of CCD at 2keV) Imaging area > 25x25mm2, pixel ~ 3-6μm F=9m) Energy Band.3-4keV with BI (<.1μm), and thick depletion (>25μm) Spectroscopy ΔE < 6keV, Fano limit (Req.<1e-, Goal < 3e-) Timing <1μsec Dark Current <2pA/cm2 (assuming working T = -4 ) Function Trigger signal & pixel address output, built-in ADC (option) Non X-ray BGD 5e-5 c/s/kev/1x1mm2 at 2keV (1/1 of CCD)

5 XRPIX Series - Road Map mm 4.5mm XRPIX1 XRPIX1b XRPIX2 XRPIX2b XRPIX3 XRPIX3b 2.4 mm 2.4 mm 2.9 mm 2.9 mm First Model 6. mm 6. mm Trigger Charge Output Middle Size Buttable Sensitive AMP XRPIX ΔΣ-type ADC

6 XRPIX1: Pixel Circuit 6 Trigger Comparator VDD18 Trigger output GND18 Analog Readout Analog output VDD18 Sensor Sensor C SF1 STORE Sample C 1fF CDS CDS C 1fF SF2 COL_AMP OUT_BUF G=1 G=1 GND18 PD_VRST Sample /Store CDS _VRST VTH TEST_ECA EOXX

7 XRPIX1-CZ (.7kΩcm), -FZ(21) (7kΩcm): Depletion Depth Depletion Depth [um] FZ : VBB=3V FZ : Physical Thickness 7 15 CZ : VBB=1V Back Bias [V] Measure the depletion thickness by observing the ratio between the counting rates of two energies X-rays having different attenuation lengths. CZ: Depletion thickness of 15μm at VBB=1V. FZ: Full depletion is achieved at VBB=3V. + : Experimental results : Expected value Nakashima et al., 212, Physics Procedia 37, 1373

8 Full Depletion of 5μm is reached at VBB=2V _matsumura.pdf XRPIX1b-FZ(212)-FI (7kΩcm) : Depletion Depth 8 Counting Rate of 22keV X-ray Physical Thickness 5μm (not 26μm) Preliminary Depletion VBB^1/2 back_bias 2V 2V Counting Rate of 22keV X-ray (Cd-19) as a function of VBB. (Attenuation Length = 12μm > Physical Thickness = 5μm.) The data follow the expected slope of depletion VBB^1/2.

9 XRPIX2-CZ-FI (Small Pixel) : Spectrum in the frame mode Cu Count Cu Kα (8. kev) 656 ev FWHM Mo Kα (17.4 kev) PH [ADU] 16 Pulse Hight (ch = 244 µv) 2 8 ev FWHM 1 Mo Kβ (19.6 kev) Mo Count Pulse Hight (ch) XRPIX2 Gain 6.5 µv/e- XRPIX1 Gain 3.6 µv/e X-ray Energy (kev) Observed Readout Noise Fano Noise Pixel-Pixel Gain Dispersion 1% Sum Cu Kα 656 ev 548 ev (FWHM) Mo Kα 8 ev 64 e-(rms) 139 ev 255 ev 62 ev 25 ev 553 ev 85 ev Nakashima et al., 212, NIM A submitted

10 XRPIX3/3b : Pre Amp in Each Pixel 1 Reset SW Protection Diode Sensor Node Feedback Charge Amp Capacitance 1fF A charge sensitive amp (CSA) in every pixel in order to increase the gain and improve energy resolution. CSA is basically the same that developed in another SOIPIX (PIXOR). Gain ~5 μv/e, higher by a factor of ~1. Readout noise = 64e (rms) Now testing

11 Row Hit Add. Resister XRPIX1b-CZ : Event Driven Readout 11 TRIG_COL COL Hit Add. Resister ROW Readout ADDR X-ray! O R TRIG_ROW TRIG_O A_OUT F P G A COL Readout ADDR COL Amp ADC Takeda et al., IEEE Accepted (212)

12 Pulse Hight (ch) XRPIX2b-CZ : Event-driven Readout Mode 12 Trigger! TRIG_OUT SCLK Trigger Address Readout Clock 22keV X-ray detection Cd-19 Fe-55 (5.9keV) Note: Pixel gain is not calibrated. CA[151-] Preliminary RA[151-] Address of Triggered Pixel Row Column 4μsec Event-Driven 5.4 μv/e- Pulse Hight (ch) - Event-driven mode basically operates. - Capacity of event rate >1kHz. - The gain is different. There is offset. - Due to interference between analog and digital circuits Offset Frame-Mode 7. μv/e- Preliminary X-ray Energy (kev) Takeda et al., IEEE (213)

13 BPW : CMS Raw Histgram Buried p-well Pixel structure 4 1 Circuit P+ SiO2 XRPIX1/2-CZ : Charge Loss CMS Split1 Histgram 1-FZ-FI Small Pixel Large Pixel 1-2-CZ-FI/SP = 1b-FZ-FI Peak / Tail = 6.7 CMS Split2 Histgram Mo-K CZ-FI/LP1 Peak / Tail = CMS Split3 Histgram Mo-K BPW CMS Split4 Histgram Back Bias 22 Sensor 2 Node Suppress the back 14 gate effect of Tr Also act as a part 8 of 6 charge collecting 4 node Increase parasitic capacitance. A large BPW reduces node gain Node CMS Split5 Histgram BPW 2μm 3μm PH [ADU] Energy (kev) PH [ADU] Energy (kev) Channe 1 pixel event 1 pixel event CMS Sum Histgram BI_Cu_Mo_Vb3V_1f 3μV/e 6μV/e 6μV/e A part of signal charge is lost somewhere.

14 single pixel event tgram tgram Large BPW (2.9μm) double pixel event CMS Split5 Histgram Charge Loss CMS 4 Split2 6 8 Histgram CMS Raw Histgram 2 CMS 4 Split1 6 8 Histgram CMS Split3 Histgram 2 CMS 4 Split2 6 8 Histgram Channel (ADU) Channel (ADU) CMS Split4 Histgram CMS Sum 4 Histgram CMS Split3 Histgram BI_Cu_Mo_Vb3V_1f tgram CMS Split4 Histgram CMS Sum Histgram 2 CMS 4 Split5 6 8 Histgram CMS 4 Sum 6 Histgram The charge loss occurs in the region Channel of (ADU) pixel Channel boundary. (ADU) 16 1 BI_Cu_Mo_Vb3V_1f 45 BI_Cu_Mo_Vb1V_-55c_1f XRPIX1-FZ-FI Cu Kα (8.4 kev) Mo Kα (17.4 kev) No peak 12 1 shift CMS Raw Histgram single pixel event double pixel 3 45 event Small BPW (14.μm) CMS Split1 Histgram XRPIX1b-FZ-FI Cu Kα (8.4 kev) Mo Kα (17.4 kev) peak shift CMS Split5 Histgram single 4 35 pixel 3 event double pixel event CMS 4 Split3 6 8 Histgram charge is shared Top view of 3x3 pixels CMS Split2 Histgram charge cloud CMS Sum Histgram by two pixels Matsumura+13 HSTD9

15 Charge Loss at interface 6.27: BNW between Si and SiO2 15 E field ( NHR5um,3V ) (a) BNW (b) BNW No BPW E field ( NHR5um,3V,BPW6um ) 1.5e+4 1.5e e e+4 E field ( NHR5um,3V,BNW6um ) Electric field penetrates 1.5e+4 into SiO2 insulator. 1.15e+4 Large BPW Active boundary of (a) BPW 6(µm) two pixels (b) Active 8.84e e e e e e+3 4.e+3 4.e+3 Sensor node BPW Signal charge moves to the interface region between 6.79e+3 depleted Si and SiO2 insulator. 6.28: BPW, BNW Circuit SiO2 The signal charge would be (b) E BNW field ( NHR5um,3V,BNW6um 6(µm) ) trapped and lost at the interface. 8.84e e+3 4.e+3 Pencil X-ray beam test in SPring-8. Y. Ono, master thesis "Research and development of the PIXOR (PIXel OR) semiconductor detector for the high energy experiments based on the SOI technology" (unpublished, in Japanese) epx.phys.tohoku.ac.jp/eeweb/paper.html

16 Summary 16 Developing monolithic SOI sensor XRPIX for future Xray Astronomical Satellites. Realize the event driven readout mode and very low nonx-ray BGD by the function of the trigger signal output. Depletion region ~5μm. The readout noise ~6e- Charge Sensitive Amp. The event driven readout basically operates. Signal charge would be lost at the interface between the depleted Si and SiO2 insulator. Pencil X-ray mean test. A-R-Tec Analog and RF Technologies URL: