Ryu et al. IEEE NSS 2010, Conf. Record (2010) Ryu et al. IEEE TNS 58, 2528 (2011) Nakashima et al. TIPP 2011 (2011) Submitted

Transcription

1 Development and Performance of X-ray Astronomical SOI pixel sensor T.G.Tsuru, S.G.Ryu, S.Nakashima (Kyoto), Y. Arai, A. Takeda, Y.Ikemoto (KEK), A.Iwata, T.Imamura, T.Ohmoto (A-R-Tec) Posters Ryu et al. Trigger-Driven Readout NP3.M-90 Nakashima et al. Analog to Digital Converter NP3.M-92 Ryu-kun Nakashima-kun Papers Ryu et al. IEEE NSS 20, Conf. Record (20) Ryu et al. IEEE TNS 58, 2528 (2011) Nakashima et al. TIPP 2011 (2011) Submitted _XRPIX_SOIPIX_IEEE-NSS11_v11.key

2 The standard Imaging Spectrometer of modern X-ray astronomical satellites X-ray CCD Suzaku XIS Fano limited spectroscopy with the readout noise ~3e- (rms). Wide and fine imaging with the sensor size of ~20-30mm pixel size of ~30μm

3 The standard Imaging Spectrometer of modern X-ray astronomical satellites X-ray CCD Suzaku XIS Fano limited spectroscopy with the readout noise ~3e- (rms). Wide and fine imaging with the sensor size of ~20-30mm pixel size of ~30μm Non X-ray background above kev is too high to study faint sources. The time resolution is too poor (~ sec) to make fast timing obervation of variable sources. Non X-ray background of XIS (BI) Due to high energy particles on orbit.

4 XRPIX = SOI pixel sensor for future X-ray astronomical satellites Sensor (high ρ, V_back X-ray depleted Si) Electron Insulator P+ Hole BPW (SiO2) CMOS Readout CMOS Readout CMOS Readout CMOS Readout Fast CMOS V_sig Time (low ρ Si) Our SOIPIX Each pixel has its own trigger and analogue readout CMOS circuit.

5 XRPIX = SOI pixel sensor for future X-ray astronomical satellites Sensor (high ρ, depleted Si) Insulator (SiO2) Fast CMOS (low ρ Si) V_back CMOS Readout CMOS Readout Electron Our SOIPIX X-ray CMOS Readout V_sig Hole BPW Time Each pixel has its own trigger and analogue readout CMOS circuit. P+ CMOS Readout X-ray non X-ray BGD (high energy particle) scintillator on-board processor Realize Very Low BGD by Anti-coincidence

6 XRPIX = SOI pixel sensor for future X-ray astronomical satellites Sensor (high ρ, depleted Si) Insulator (SiO2) Fast CMOS (low ρ Si) V_back CMOS Readout CMOS Readout Electron Our SOIPIX X-ray CMOS Readout V_sig Hole BPW Time Each pixel has its own trigger and analogue readout CMOS circuit. P+ CMOS Readout X-ray non X-ray BGD (high energy particle) scintillator on-board processor Realize Very Low BGD by Anti-coincidence Target Specification Imaging Energy Band Spectroscopy Timing Function Non X-ray BGD area > 25x25mm2, pixel ~ 30-60μm F=9m) keV with BI, and thick depletion (>300μm) ΔE < 6keV, Fano limit (<e-) ~ μsec Trigger signal & pixel address output, built-in ADC 5e-5 c/s/kev/xmm2 at 20keV (1/0 of CCD)

7 Road Map to the Goal Wafer 1-CZ Mask

8 Road Map to the Goal Wafer 1-FZ Thick Depletion 1-CZ Mask

9 Road Map to the Goal Wafer 1-FZ-BI Back Illumination 1-FZ Thick Depletion 1-CZ Mask

10 Road Map to the Goal Wafer 1-FZ-BI Back Illumination 1-FZ Thick Depletion 1-CZ 1b-CZ Spectroscopy Mask

11 Road Map to the Goal Wafer 1-FZ-BI Large Size Back Illumination 2-FZ-BI 1-FZ Thick Depletion Spectroscopy 1-CZ 1b-CZ Spectroscopy Mask

12 Road Map to the Goal ADC1 Wafer 1-FZ-BI Large Size Back Illumination 2-FZ-BI 1-FZ Thick Depletion Spectroscopy 1-CZ 1b-CZ Spectroscopy Mask

13 Road Map to the Goal Integration ADC1 Wafer 1-FZ-BI Large Size Goal! Back Illumination 2-FZ-BI 1-FZ Thick Depletion Spectroscopy 1-CZ 1b-CZ Spectroscopy Mask

14 Row Hit Pattern XRPIX1-CZ (X-Ray PIXel detector - CZochralski) CZ (0.7kΩcm), 260μm thick Front Illumination COL Hit Pattern COL Hit Pattern TRIG_COL TRIG_ROW 2.4 mm ROW ADDR 1.0 mm 30.6 µm x 32 Pixel O R TRIG_O COL ADDR COL Amp A_OUT

15 XRPIX1: Pixel Circuit Trigger Comparator VDD18 Trigger output GND18 Analog Readout Analog output VDD18 Sensor Sensor C SF1 STORE Sample C 0fF CDS CDS C 0fF SF2 COL_AMP OUT_BUF G=1 G=1 GND18 PD_VRST Sample /Store CDS _VRST VTH TEST_ECA EOXX

16 XRPIX1-CZ (0.7kΩcm): Depletion Depth Depletion Depth [um] CZ : VBB=0V Back Bias [V] + : Experimental results : Expected value kev and 8 kev X-rays have different attenuation lengths. Measure the depletion thickness by observing the ratio between the counting rates of the two energies X-rays. The data follow the expectation well. Nakashima et al., 2011, submitted

17 XRPIX1-FZ (7kΩcm): Dark Current from Rough Backside Surface Dark Current (e/ms/pixel) w/o CMP Back Bias (V) Nakashima et al., 2011, submitted

18 XRPIX1-FZ (7kΩcm): Dark Current from Rough Backside Surface Dark Current (e/ms/pixel) w/o CMP Rough backside Back Bias (V) Depletion Layer Reaches the backside at 25V Nakashima et al., 2011, submitted

19 XRPIX1-FZ (7kΩcm): Dark Current from Rough Backside Surface Chemical Mechanical Dark Current (e/ms/pixel) w/o CMP Polish (CMP) Rough backside Back Bias (V) Depletion Layer Reaches the backside at 25V Nakashima et al., 2011, submitted

20 XRPIX1-FZ (7kΩcm): Dark Current from Rough Backside Surface Chemical Mechanical Dark Current (e/ms/pixel) w/o CMP Polish (CMP) Rough backside Back Bias (V) Depletion Layer Reaches the backside at 25V Smooth backside Nakashima et al., 2011, submitted

21 XRPIX1-FZ (7kΩcm): Dark Current from Rough Backside Surface Chemical Mechanical Dark Current (e/ms/pixel) w/o CMP with CMP Polish (CMP) Rough backside Back Bias (V) Depletion Layer Reaches the backside at 25V Smooth backside Nakashima et al., 2011, submitted

22 Depletion Depth [um] XRPIX1-FZ (7kΩ): Depletion Depth FZ : VBB=30V 150 CZ : VBB=0V Back Bias [V] + : Experimental results : Expected value The thickness of the depletion layer of XRPIX1-FZ reaches ~250μm at 30V and stops its growth there. The 250μm is nearly equal to the hi-ρ Si thickness (260μm). Full depletion is achieved at VBB=30V. Nakashima et al., 2011, submitted

23 XRPIX1-CZ : X-ray Spectra in frame mode Counts 250 Red: 9 Cd 22.2 kev Blue: 241 Am kev 17.7 kev FWHM = 1.1 kev 24.9 kev Output [ADU] Good Linearity Channel Sensitivity = 4.0 μv/e- (including SF, amps) Sensor C = 34 ff Energy Resolution ΔE = keV (FWHM) Fano limit Readout Noise = 0e- (rms) XRPIX1-CZ (T=-50C, VBB=0V) X-ray Energy [kev] Ryu et al., 2011

24 XRPIX1-CZ : Readout Noise See if the readout noise of 0e- (rms) is explained by the sum of circuit noises or not. Measure the noise of individual circuit element through several DC voltage input points. The sum of these noise are almost consistent with the observed readout noise of 0e. VDD18 Sensor A Sensor C SF1 GND18 PD_VRST STORE Sample C 0fF Sample /Store CDS CDS C 0fF CDS _VRST VTH SF2 COL_AMP OUT_BUF G=1 G=1 TEST_ECA EOXX Vout SF1 13e VB CDS ktc 70e (0fF 51e) Sum = 94e B C D SF2 13e VC COL_AMP 31e VD OUT_BUF External 53e Ryu et al., 2011

25 Purpose XRPIX1 XRPIX1b Improvement of Spectroscopic performance Block 1 Increase C_CDS from 0fF to 400fF to reduce the reset noise generated at the CDS circuit. Block 2, 3 Reduce the area of BPW to 45% to obtain higher gain. BPW (buried p-well) suppressing back gate effect dominates the capacitance at the sensor node. Show results from block 2 today 1 44D_CDS (400fF) 3 44D_BPW (45%) 2 44M_BPW (45%) 4 44D_ORG (BPW0%, CDS=0fF)

26 Purpose XRPIX1 XRPIX1b Improvement of Spectroscopic performance Block 1 Increase C_CDS from 0fF to 400fF to reduce the reset noise generated at the CDS circuit. Block 2, 3 Reduce the area of BPW to 45% to obtain higher gain. BPW (buried p-well) suppressing back gate effect Designed by 1 44D_CDS (400fF) 2 44M_BPW (45%) (KEK) dominates the capacitance at the sensor node. Show results from block 2 today 3 44D_BPW (45%) 4 44D_ORG (BPW0%, CDS=0fF)

27 Cts XRPIX1-CZ 1b-CZ : X-ray Spectra in frame mode Bule: 9 Cd 22.2 kev FWHM=8 ev h7 Entries 1196 Mean 1.9 RMS 48.88! 2 / ndf / 6 Constant ± 3.91 Mean ± 0.2 Sigma ± [ADU] Gain Increased 24.9 kev Sensitivity = μV/e- Sensor C = 34 23fF Better Energy Resolution Output [ADU] ΔE = keV kev(fwhm) Readout Noise = 0e- 74e- (rms) XRPIX1b-CZ (T=-50C, VBB=0V) x1.5 XRPIX1-CZ (T=-50C, VBB=0V) X-ray Energy [kev] Second dominating source of C of sensor node.

28 XRPIX1b-CZ : Single Pixel Readout In order to study the limit of the spectroscopic performance. PH [ADU] X-ray Hit average 0 samples Pulse τ=0μsec Height average 0 samples τ=0μsec sample number in one frame Cts / ADU CMS Histgra (RC) rms=14.6e- Cu-Kα 44M-BPW h1 Entries Mean RMS 3.1 2! / ndf 3.97e+05 / 9 Constant ± 1.41 Mean ± 1.41 Sigma ± kev Cu-Kβ PH [ADU] ΔE = 8.0keV (FWHM), readout noise = 14.6 (rms)

29 XRPIX1b-CZ : Single Pixel Readout In order to study the limit of the spectroscopic performance. Observe the waveform of analogue output from a single pixel by fixing the readout address without clocking (Single Pixel Readout like a SSD). PH [ADU] X-ray Hit average 0 samples Pulse τ=0μsec Height average 0 samples τ=0μsec sample number in one frame Cts / ADU CMS Histgra (RC) rms=14.6e- Cu-Kα 44M-BPW h1 Entries Mean RMS 3.1 2! / ndf 3.97e+05 / 9 Constant ± 1.41 Mean ± 1.41 Sigma ± kev Cu-Kβ PH [ADU] ΔE = 8.0keV (FWHM), readout noise = 14.6 (rms)

30 XRPIX1b-CZ : Single Pixel Readout In order to study the limit of the spectroscopic performance. Observe the waveform of analogue output from a single pixel by fixing the readout address without clocking (Single Pixel Readout like a SSD). Detect an X-ray as a step and measure the pulse height. X-ray spectrum. PH [ADU] X-ray Hit average 0 samples Pulse τ=0μsec Height average 0 samples τ=0μsec sample number in one frame Cts / ADU CMS Histgra (RC) rms=14.6e- Cu-Kα 44M-BPW h1 Entries Mean RMS 3.1 2! / ndf 3.97e+05 / 9 Constant ± 1.41 Mean ± 1.41 Sigma ± kev Cu-Kβ PH [ADU] ΔE = 8.0keV (FWHM), readout noise = 14.6 (rms)

31 XRPIX1b-CZ : Single Pixel Readout In order to study the limit of the spectroscopic performance. Observe the waveform of analogue output from a single pixel by fixing the readout address without clocking (Single Pixel Readout like a SSD). Detect an X-ray as a step and measure the pulse height. X-ray spectrum. No reset during the measurement Free from the reset noise PH [ADU] X-ray Hit average 0 samples Pulse τ=0μsec Height average 0 samples τ=0μsec sample number in one frame Cts / ADU CMS Histgra (RC) rms=14.6e- Cu-Kα 44M-BPW h1 Entries Mean RMS 3.1 2! / ndf 3.97e+05 / 9 Constant ± 1.41 Mean ± 1.41 Sigma ± kev Cu-Kβ PH [ADU] ΔE = 8.0keV (FWHM), readout noise = 14.6 (rms)

32 XRPIX1b-CZ : Single Pixel Readout In order to study the limit of the spectroscopic performance. Observe the waveform of analogue output from a single pixel by fixing the readout address without clocking (Single Pixel Readout like a SSD). Detect an X-ray as a step and measure the pulse height. X-ray spectrum. No reset during the measurement Free from the reset noise Reduce noises other than the reset noise by introducing LPF. high_v(0 samples average) - low_v(0 samples average) LPF with τ=0μs PH [ADU] X-ray Hit average 0 samples Pulse τ=0μsec Height average 0 samples τ=0μsec sample number in one frame Cts / ADU CMS Histgra (RC) rms=14.6e- Cu-Kα 44M-BPW h1 Entries Mean RMS 3.1 2! / ndf 3.97e+05 / 9 Constant ± 1.41 Mean ± 1.41 Sigma ± kev Cu-Kβ PH [ADU] ΔE = 8.0keV (FWHM), readout noise = 14.6 (rms)

33 TRIG_O SCLK Trigger! CA[31-0] RA[31-0] XRPIX1b-CZ : Trigger Driven Readout X-ray Trigger-driven Spectra 31(ADDR) 0 Address of Triggered Pixel See Ryu s poster (NP3.M-90) in detail Trigger Address Readout Clock Row Column Counts / ADU kev FWHM 1.4 kev 13.9 kev 17.4 kev 17.7 kev h1 Entries 1617 Mean RMS h1 Entries 487 Mean RMS kev X-ray PH (ADU) Trigger-driven mode basically operates as designed. When X-ray is detected, the device outputs trigger signal. Address of the triggered pixel is output according to clock from FPGA. ADC reads out the analog signal of only the triggered pixel.

34 XRPIX-ADC Data from Odd modulator Counts 400 EIN = 72 µv rms 200 Offset Digital output (ADU) Fig. 6. Histogram of digital output in the case of GND input. ΔΣ type (over sampling type) SOI version of the ASIC developed for X-ray CCD camera onboard ASTRO-H (next Japanese X-ray satellite). It is working. Making performance test now. See Nakashima s poster (NP3.M-92) in detail.

35 XRPIX2 : New Device XRPIX1, 1b 1.0mm Large Size, Large Format 60μm : Single pixel can cover the whole charge cloud to reduce charge sharing effect. Make the capacitance at the readout node smaller (Area of BPW = 1/4 of XRPIX1). 4.0mm XRPIX2 Make further increase of C_CDS to reduce the reset noise. Just submitted last week. Designed by (KEK)

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