development of silicon microstrip sensors in 150 mm p-type wafers

Y.Unno, 3rd Workshop on Advanced Silicon Radiation Detectors, Barcelona, Spain, 14-16 April. 2008

Development of Silicon Microstrip Sensors in 150 mm p-type Wafers

Y. Unno, S.Terada, Y.Ikegami, T. Kohriki, K.Hara, and the ATLAS R&D collaboration of "Development of non-

inverting Silicon strip detectors for the ATLAS ID upgrade"

K. Yamamura, S. Kamada (Hamamatsu Photonics)


Some History of Development

• 1995 p-type 4-inch (100 mm) wafer (p95)– FZ(111) (~6 kΩcm) wafers

• 2005 p-type 4-inch (100 mm) wafer (ATLAS05)– FZ(111) (~6k Ωcm)

– MCZ(100) (~900 Ωcm) wafers

• 2006 p-type 6-inch (150 mm) wafer (ATLAS06)– FZ-1(100)(~6.7k Ωcm), FZ-2(100)(~6.2k Ωcm)

– MCZ(100)(~2.3k Ωcm)

• 2007 p-type 6-inch (150 mm) wafer (ATLAS07)– FZ-1(100)(~6.7k Ωcm), FZ-2(100)(~6.2k Ωcm)


p95 p-type Sensors• A prototype n-in-p sensor was

fabricated in 1995– 6 cm x 3 cm x 300 um, 50 um

pitch, common p-stop • no DC-field plate over p-stop

– p-bulk, (111), ~6 kΩcm– Irradiated up to 1.1 x 1014 p/cm2

at 12 GeV PS at KEK– A report was made in NIM

A383(96)159– Re-measurements after 10yrs

(irrad. stored at 0 C)• I-V• C-V• CCE with laser


ATLAS05 p-type Sensors

• Investigation of isolation of n-strips– p-stop with/without p-spray

– With/without field-plate

– p-stop doping levels


ATLAS05 p-type Sensors• p-type wafers

– 4-inch wafer for cost reason

– MCZ: • ~900 Ωcm

• Orientation (100)

– FZ: • ~6k Ωcm

• Orientation (111)

• Sensors– Miniature: 1cm x 1cm

– Large: ((~1cm x ~6cm) x6 zones)



• 6 inch (150 mm) wafer– FZ-1 (100), FZ-2 (100), MCZ

• Further R&D of isolation structures– No DC-field plate

– Width of (common) p-stop

– p-stop/p-spray doping variations



• Many miniature (1cm x 1cm) sensors – One sensor per one "Zone"

• Large (3cm x 6 cm) sensors with 2 striplets– Variation of Polysilicon bias resistor connections


ATLAS07 p-type Sensors• 6-inch (150 mm) wafer• Maximum size sensor (~10 cm x ~10

cm) prototyping• R&D's

– Candidate isolation structures– "Punch-thru Protection" structures– Wide/Narrow metal effect– Wide/Narrow pitch effect



• Full size (9.75 cm x 9.75 cm) prototype sensors– 4 segments: two "axial" and two "stereo" (inclined) strips


Proton Irradiation at CYRIC

• Facility associated with Univ. Tohoku, Sendai, Japan

Beamline 32

Beamline 31-2

KEK70 MeV protons


Proton irradiations at CYRIC• AVF Cyclotron at Tohoku University

– Beam energy: 70 MeV– Beam intensity: 10nA ~ 800nA– Beam spot size: ~5 mm FWHM

• ~4 min. for 1x1015 at 800 nA

• Irradiation history– Beamline 31-2

• 2005.10.17 - 1st and beamline study• ATLAS05 - up to 5x1015

– 2006.01.27 +2006.03.14 +2006.06.26 + 2006.10.16

• ATLAS06 - up to 2x1015

– 2007.05.18,

– Beamline 32– 2007.08.28

• ATLAS07 - up to 1x1015

– 2008.03.11

• Change of beamline– Machine time/user conflict in 31– Straight, simpler line in 32

Beamline 31-2

Beamline 32


Laser for FDV and CCE• Full Depletion Voltages (FDV)

– C-V method– Laser method

• Charge Collection Efficiencies (CCE)– Laser method

Pulsed laser (1064nm) focused to 4um x 4um

Referencesensor


Full Depletion Voltages

• Very different fluence development in 4 inch and 6 inch!!– All p-type– 4 inch FZ (111), though

• FZ and MCZ are similar in 6 inch!!– except below ~2x1014 , no advantage in MCZ

ATLAS05CCE

CCE

CV

CV

ATLAS06

CCE

FDV~500V!!at 1x1015


CCE

• Charge loss up to 1x1015 is small– 2x1015 appreciably less

• No obvious difference is FZ and MCZ

not fully depletedVB=1kV

ATLAS05ATLAS06


Microdischarge• Onset voltage (VMD)

– >600 V in FZ– some trouble in MCZ– Zone5 exceptional

• After irradiation (>1x1014)– >1000 V!!– Even Zone5 and MCZ

ATLAS06


N-strip Isolations

• Showing Vbias voltages to achieve isolation– Isolation gets worse as fluence accumulates– Number of observations can be seen from the plots....

+ p-spray


TCAD Simulations

• N-P gap was too narrow

• Potential of 2nd p-stops makes effective p-stop width as wide up to 2nd p-stop


Summary• n-in-p p-type microstrip sensors have been fabricated in p-FZ and p-

MCZ wafers, for several years by now

• Proton irradiations, 70 MeV, are being routinely carried out at CYRIC of Tohoku Univ.,

• Fluence development of full depletion voltage (FDV) of 4-inch (100 mm) and 6-inch (150 mm) is very different

• In 6-inch, FDV is ~500 V at 1x1015 neq/cm2

• CCE is near full up to 1x1015 neq/cm2

• Onset voltage of the microdischarge has been achieved to be >600 V in general

• Number of isolation structures are being investigated and we are narrowing the candidates

• A full size microstrip sensor has been prototyped and we have the first look in hand

development of silicon microstrip sensors in 150 mm p-type wafers

Documents

wafers2006 ptype

cm2007 ptype

ptype wafersy

kcm wafers2005 ptype

wafer p95fz111

wafer atlas05fz111

wafer atlas06fz

wafer atlas07fz