PHOBOS Silicon Sensors Production W.T. Lin Dept. of Physics, National Central University Chung-Li, Taiwan Introduction Design and Production of Si-Sensors Milestone and Status of Si-Sensors Conclusions TAC BNL Nov

Unique feature of PHOBOS A single detector technology for almost the whole experiment Silicon detectors (pad and strip): small pad for high density detection truly two dimensional readout well developed technology 438 Silicon sensors with 134,832 channels

Sensors for PHOBOS expt. Type Assembly Spare Total 1-arm Spectrometer Multiplicity counter Oct Ivtx Ovtx Ring

Phobos Silicon Sensors V F.D. < 70 V I leak =  A R poly > 1 M  C SOG = 40 +/- 2 pF/mm 2 C ONO = 170 +/- 5 pF/mm 2 Bulk 320+/- 30  m 1 st metal 5000 A 2 nd metal A SOG A ONO 3200 A The electric characteristic of each component can be measured from test keys

Design of PHOBOS Silicon Sensors AC-coupled Direct bias Double metalization metal 1 metal 2 p+ ImplantPolysilicon Drain Resistor bias bus signal lines vias n+ Implant 320  m 5K  -cm SOG thick oxide ONO thin oxide -V +V Signal

Dimensions of Sensors TypeDimen. Of SensorDimen. Of Pad channels 17.16x3.78(cm) 940x940(  m) x x x x x x x x Oct 8.41x x Ivtx6.2104x x Ovtx6.2104x x Ring11>R>5 45deg varies 64 Pad size from 1 mm 2 to 23 mm 2 Gap btw pads 60  m Width of signal traces 15  m Gap btw traces >35  m

Mask Design 6 masks to define 1st : P+(Implant 0.8  m) 2nd: Polysilicon (L:250  m, W:15  m) 3rd: Contact window (L:10  m, W:10  m) 4th: Metal 1(T:0.5  m) 5th: Via (L:15  m, W:15  m) 6th: Metal 2 (T:1.2  m, W:15  m) 34 Stages to process Normal run : stage/day Hot run : stage/day

Type-1 : 1536 channels Time consume: min/wafer CV Scan

R poly > 1 M  I leak < 5  (1.1)*V FD or I leak < 10  A with a flat IV line shape Yield of pinhole < 3% V FD < 70V Criteria of Accepted Sensor

Status of Spectrometer 1-arm spectrometer Need NCU MIT Tested Accepted Rejected Type Type Type Type Type

Milestone of Spectrometer WBS milestone Sensor delivered Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Type Type Type Type Type

Status of Multiplicity Counter Need NCU UIC Tested Accepted Rejected Octagon Inner Outer Ring Need 1 batch of inner vtx and 4 batches of octagon to fulfill multiplicity detector.

Milestone of Multiplicity Counter WBS milestone Sensor delivered ‘98 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Octagon Inner Vtx Outer Vtx Ring Annual shut down for maintenance is during Chinese New Year. ERSO changed a brand new implanter.

Most silicon wafer production has been completed and sensors now being tested. Most of production was on time except for type-5 and octagon. Conclusions