micro pixel chamber based on MEMS technology Taito Takemura (Kyoto - PowerPoint PPT Presentation

Development of the micro pixel chamber based on MEMS technology Taito Takemura (Kyoto Univ.) T. TANIMORI, H. KUBO, A. TAKADA, T. MIZUMOTO, Y. MIZUMURA, D. TOMONO, S. SONODA, S. KOMURA, T. KISHIMOTO , S. MIYAMOTO, K. YOSHIKAWA, Y. NAKAMASU, Y. MATSUOKA, M. ODA, K. MIUCHI (Kobe Univ.) T. SAWANO(Kanazawa Univ.), K. OHTA (Dai Nippon Printing Co., Ltd.) T. MOTOMURA (Dai Nippon Printing Co., Ltd.)

Outline  Introduction -Micro pixel chamber (m -PIC) and its application -Requirements for m -PIC  m -PIC based on MEMS Technology  Gain Simulation of MEMS m -PIC with Garfield++  Measured spectrum and gain of MEMS m -PIC  Summary 1

Micro pixel chamber ( m -PIC) A gaseous 2D imaging detector  with strip read out Manufactured with PCB(Printed Circuit  Board) technology Cu electrodes and polyimide substrate Each pixel is place with  a pitch of 400 m m Gas gain: Max ~ 15,000  stable operation ~ 6,000 60 m m Fine position resolution(RMS ~ 120 m m)  Large detection area:  Anode Cathode 10 x 10 cm 2 , 30 x 30 cm 2 Time of operation:  > 2 years (30 x 30 cm 2 ) 400μm T . Nagayoshi+ (NIMA, 2003) 2

m -PIC Application Application for Dark Matter Search Application for MeV talk id[108] Thursday 15 Gamma-Ray astronomy 10:25~ Mr. IKEDA (Kobe Univ.) ETCC (Electron-Tracking Compton Camera) K. Nakamura+ (PTEP 2015) Application for neutron imaging 1 cm T. Tanimori+ J.D. Parker+ (NIMA 2013) (Astrophysical Journal 2015) Using m -PIC as TPC 3

Requirements of m -PIC for TPC A gap of anode cap makes discharge easily ① Higher gas gain ② Suppression of discharge ③ Precise 3D tracking For Gamma-ray imaging Cumulative ratio in PSF (Point Spread Function) The precision 3-D tracking is essential to determine the Point Spread Function for gamma ray S : N = 10 3 :10 6 (simulation) Imaging with Present 15 degree diameter precise 3D tracking imaging T. Tanimori+ 4 (Astrophysical Journal, 2015)

PCB Technology & MEMS Technology m -PIC based on m -PIC based on MEMS (Micro-Electro- Mechanical Systems) technology PCB technology 400μm 100μm PCB m -PIC MEMS m -PIC Substrate Polyimide Silicon (+ thin SiO 2 ) (dielectric constant) (Pl: 3.2) (Si: 11, SiO 2 : 4.5) Higher gas gain Aspect ratio of ~ 2 ~ 8 (100 m m/60 (400 m m/50 m m) anode m m) (height/diameter) Suppression of discharge & ~ 10 m m ~ several m m Processing accuracy Uniformity > 400 m m > 200 m m Pitch length Precise 3D tracking Cost ~ PCB (if 10 x 10 cm 2 ) We studied MEMS -PIC with ever the same pitch 5 to focus on only the difference between PCB and MEMS

Electric Field MEMS PCB 100μm 400μm [cm] [cm] [V/cm] [V/cm] Simulation (Elmer) Simulation (Elmer) Anode Anode Cathode Cathode 6 [cm] [cm]

Simulation 7

MEMS m -PIC structures and types 400 m m 400 m m Type B Type A 250 m m Anode 250 m m Cathode Cathode Anode 80 or 157.5 m m 50 m m 50 m m 15 m m 15 m m 15 m m 15 m m 4 m m 10 m m 10 m m 1 m m or Cu Cu 10 m m 400 400 m m m m The structure is manufactured by The Structure is similar to that of basic MEMS technology (through- 8 present m -PIC hole technology)

Gas Gain of MEMS m -PIC in Simulation : Garfield++(MEMS, Type B) Gain : Garfield++(MEMS, Type A) ― :Garfield++(PCB) 10 4 :Measured value of PCB m -PIC gain 10 3 Ar 90% + C 2 H 6 10%, 1 atm 460 500 540 580 Anode Voltage[V] PCB m -PIC simulation : A. Takada+ (JINST 2013) Simulation suggests the gain of MEMS m -PIC is 2 times higher than that of PCB m -PIC ① the gains of two types MEMS m -PIC are same ② 9

Dependence on polyimide layer of gain (MEMS μ -PIC type A) Cathode Anode Gain 250 m m Variable parameter as insulation 50 m m 15 m m 15 m m 10 m m 10 m m Anode 460V Ar 90% + C 2 H 6 10%, 1 atm 400 m m Hole diameter of polyimide layer [ m m] Material around anode disturb electric field Hole diameter of polyimide should be large 10

Measurement 11

Setup of Experiment MEMS m -PIC MEMS m -PIC Drift Voltage 250[V/cm] Cathode strip × 12 Drift Space ~3mm 5 mm D GEM 300V(Gain ~ 20) Induction field 10 mm 1[kV/cm] ~3mm Anode strip × 20 Ar:90%,C 2 H 6 :10%,1atm DAQ MEMS m -PIC Anode20 strip FPGA Memory FADC 25MHz Board Preamplifer & 10 cm Cathode 12 strip Discriminator PC FPGA FADC 25MHz 10 cm 12 T . Mizumoto+ (NIMA, 2015)

MEMS m -PIC structure and types 400 m m 400 m m Type B Type A 250 m m Anode 250 m m Cathode Cathode 80 or 157.5 m m 50 m m Anode 50 m m 15 m m 15 m m 15 m m 4 m m 15 m m 10 m m 1 m m 10 m m or Cu Cu 10 m m 400 400 m m m m 13

Discharging Voltage Discharging Voltage [V] Gain Type Ar90% C 2 H 6 10%, 1 atm ~550 ~10,000 PCB 570 ~8,000 Type A (Anode Hole; Pl 157.5 m m) 590 ~10,000 Type A(Anode Hole; Pl 80 m m) 570 ~10,000 Type B(like PCB; SiO 2 10 m m) Type B(like PCB; SiO 2 1 m m) 530 ~1,700 It took a long time that current of SiO2 1 m m MEMS u-PIC settle down (SiO 2 1 m m: >20nA ~4h) (Other u-PICs: >20 nA ~1 min) 14

PCB and MEMS m -PIC spectra PCB MEMS (Type A) Mn-K a ( 5.9keV) 41.19%(FWHM) @Anode 540 V Gain 2279 Mn-K a (5.9 keV) 39.8%(FWHM) @Anode 480V Gain 1093 For the first time, we succeed in test operation of MEMS m -PIC GAS Ar90% C 2 H 6 10%, 1 atm X-ray source Fe-55 Bad Energy resolution probably due to much small detection area(10 mm x 5mm) A lot of electrons escape from detection area 15

MEMS m -PIC GAIN GAIN @Anode 500V 40% 16% Type A(Anode Hole; Pl 157.5 m m) Type A(Anode Hole ; Pl 80 m m) GAS Ar90% C 2 H 6 10%, 1 atm Type B(like PCB ; SiO2 10 m m) Type B(like PCB ; SiO2 1 m m) The gain of MEMS m -PIC is smaller than PCB m -PIC Anode Voltage[V] This results is inconsistent with Garfield++ simulation 16

Issue with Si ? MEMS Type B Gain 1 m m or 10 m m Si SiO2 10 m m (Measurement) SiO2 1 m m (Measurement) Anode Voltage [V] By the experiment, Assumption MEMS μ -PIC with SiO 2 1 m m Deterioration of gain against has a much lower gain than simulation is caused by Si near anode MEMS m -PIC with SiO 2 10 m m working as semiconductor 17

Future prospect Type B MEMS m -PIC > 15 m m MEMS m -PIC In order to study the effect of Si near anode Various thickness of SiO2 layer (≥ 15 m m)  we’ll experiment with MEMS m -PIC with SiO 2 15 m m soon MEMS m -PIC with glass substrate GALASS substrate  Both MEMS m -PIC can be manufactured Glass 18

Summary  We expect MEMS technology improves gas gain, suppression of discharge and precise tracking capability of u-PIC  Garfield++ simulation suggests that the gain of MEMS m -PIC is twice higher than that of PCB m -PIC  For the first time, we succeed in test operation of MEMS m -PIC  Measured gain of MEMS m -PIC is 16 % - 40% of simulation value (@ Anode 500 V, GAS: Ar 90% + C 2 H 6 10%, 1 atm )  We assume the deterioration is caused by Si working as semiconductor (We hope Garfield++ include semiconductor working) Future  We’ll investigate relation SiO 2 thickness and gas gain, and we’ll experiment with MEMS m -PIC with SiO 2 15 m m soon  We have started study of MEMS m -PIC with short pitch in simulation 19

Supplemental Slides

Problem of Si ? By the experiment, Gain MEMS μ -PIC with SiO 2 1 m m has a much lower gain than MEMS m -PIC with SiO 2 10 m m, though gain of MEMS m -PIC in simulation has no relation between gain and SiO 2 thickness Anode Voltage [V] Gain 2000 Supposition Anode 460[V] MEMS Type B (Garfield++) Deterioration of gain against 1800 simulation is caused by Si near anode working as semiconductor 1600 1 10 15 SiO2 thickness[ m m]

Si working as semiconductor ＋ ＋ ＋ － ＋ － － ＋ － － ＋

GAS Ar90%.C 2 H 6 10%, 1 atm MEMS spectrum X-ray source Fe-55 MEMS Type A (Pl 157.5 m m) MEMS Type A (Pl 80 m m) 41.19%(FWHM) @Anode 540 V 29.7%(FWHM) Gain 2279 @Anode 520 V Gain 2836 MEMS Type B (SiO 2 10 m m) MEMS Type B (SiO2 1 m m) 56.7%(FWHM) @Anode 520V 53.1%(FWHM) Gain 1208 @Anode 520V Gain 2904

Polyimide Edge 250 m m 80 or 157.5 m m 50 m m 15 m m 400 m m

Type B u-PIC

Manufacturing process of MEMS μ -PIC [1] [1]manufacturing alignment DRIE(Deep- Reactive Ion Etching) Si Bosch process Etching [2]DRIE Protective coating [3]manufacturing insulating layer (SiN/SiO 2 ) This process enable to make high aspect ratio

Manufacturing process MEMS μ -PIC [2] Type A Type B [1]manufacturing surface [1]manufacturing seed layer insulating layer (Polyimide) [5] photolithography, metal plating, seed etching [2]Filling plating metal [2] manufacturing seed layer [3]CMP [6] seed etching (Chemical Mechanical Polishing) [3] photolithography, metal [4] manufacturing surface plating, seed etching insulating layer (Polyimide)

1 st MEMS μ -PIC 理想形 Anode Anode の山形の崩れ と ポリイミド層形成の制御が失敗によりゲインが出なかった 放電が 1 度起こると、とまらなくなった (SiO2 の放電による傷が原因か？ ) 次タイプの MEMS は SiO 2 膜を厚く