# Presentation: 009851

## 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 Review @ BNL
- Nov. 6 1998

## 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
-    1             8                   4          12
-    2           14                 14          28
-    3           28                 14          42
-    4           21                 14          35
-    5           66                 20	   86
- Multiplicity counter
- Oct          92                 18         110
- Ivtx           8                   2           10
- Ovtx        16                  4            20
- Ring        48                 12           60

## Phobos Silicon Sensors

- VF.D. < 70 V
- Ileak  = 1 - 5 A
- Rpoly  > 1 M
- CSOG   = 40 +/- 2 pF/mm2
- CONO  = 170 +/- 5 pF/mm2

- Bulk     320+/- 30 m
- 1st metal     5000 A
- 2nd metal   20000 A
- SOG         12000 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+ Implant**

**Polysilicon **
**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

- Type	Dimen. Of Sensor	Dimen. Of Pad      channels
-    1	7.16x3.78(cm)	            940x940(m)	          1536
-    2	8.04x4.485	            5940x367	            500
-    3	8.04x4.4838	            7440x607	            512
-    4	8.04x4.4838     	14940x607	            256
-    5	7.98x4.43	            18940x607	            256
-   Oct    8.41x3.63         	8650x2648	            120
-   Ivtx	6.2104x5.04    	11975x413	            512
-   Ovtx	6.2104x5.04    	24010x413	            256
-   Ring	11>R>5 45deg	            varies                         	  64

- Pad size from 1 mm2 to 23 mm2
- 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 : 0.8 - 1 stage/day
-            Hot run       : 1.5 - 2 stage/day

## CV Scan

- Type-1 : 1536 channels
- Time consume: 128-180 min/wafer

**CV Scan**

## Criteria of Accepted Sensor

-  Rpoly > 1 M
-  Ileak   < 5 A @ (1.1)*VFD or
-    Ileak  < 10 A with a flat IV line shape
-  Yield of pinhole < 3%
-  VFD < 70V

**Criteria of Accepted Sensor**

## Status of Spectrometer

**1-arm spectrometer**
-                Need  NCU   MIT     Tested   Accepted   Rejected
- Type-1       12                  66          27          17             10
- Type-2       28                  89          10            7               3
- Type-3       42      23        64          23          18               5
- Type-4       35      39        50          48          45               3
- Type-5       86    100      114         105         67             38

## Milestone of Spectrometer

**                                   ****WBS milestone             ****Sensor delivered**
-                                          Jan   Feb   Mar   Apr   May   Jun   Jul   Aug   Sep   Oct   Nov   Dec
-      Type-1
-                        7                                 12      24     31
-      Type-2
-                        7                                            9      28    63
-      Type-3
-                        7                                         5 9       7     41                        2337
-      Type-4
-                        7                                                            43              25      39       20
-      Type-5
-                                                                   4616    50   35        40  25     100

## Status of Multiplicity Counter

-                Need     NCU   UIC  Tested   Accepted   Rejected
- Octagon  110         82      58       53           23             30
- Inner         10                   13       13             8               5
- Outer         20        39        7         7             3               4
- Ring          60        60       70       58           41             17
- 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
-                      12                                          10 1102     34                       82
-    Inner Vtx
-                                                                               7   10 1                5
-    Outer Vtx
-                                                                               3               4      20     39
-    Ring
-                                                                                                    6070     60
-   Annual shut down for maintenance is during  Chinese New Year.
-    ERSO changed a brand new implanter.

## Conclusions 

**   ****completed  and sensors now being tested****.**
-  **Most of production was on time except**
**   ****for type-5 and octagon.**

**Conclusions**