Thickness Choice

							  Thickness Choice
Operating Conditions &
     Fabrication
        T. Bowcock
     25 January, 2005
                     Qualification Data
   All data available on db – see GDP’s talk for more
    detail
       Public (non-Liverpool) access hampered by firewall issues. To
        be addressed
   Comments
       Thickness
       Currents to 150V
            QA and Technical specification web pages
            http://hep.ph.liv.ac.uk/lhcb/Documents/documents.html
                  http://hep.ph.liv.ac.uk/lhcb/QA_Home/qa_home.html
                  http://hep.ph.liv.ac.uk/lhcb/Programme/Hardware/Sensors/Specific
                   ation/specification.html
            See later
       Curvature
       Bad strips
Thickness
                    Current
   Data to 150V

                   Sensor Thickness(um)      300   200
                                   I(microA)       I(microA)

                                    5.8            0.8
                                    1.0            3.2
                                    1.5            4.4
                                    1.8            6.8
                                                   1.4
                                                   0.9
                   Average          2.5            2.9
                       Specifications
   Technical Specs                         QA documentation
       Initial Depletion Voltage:              Leakage current at 150V(330V)
        Vdepletion< 150V for 200                 bias for 200(300) micron sensors.
        micron thick detector                    Ramp time 60s/10V V and 1m
                                                 settling. Data provided at 1OV
       Initial leakage current at 20            steps.
        oC: < 10 A at 100 V (and               Voltage where breakdown sets
        <20 A at 150 V to be verified           in. (current >100 microA)
        by contractor) at 50%                     `TEST IS SUSPENDED PENDING REVIEW
        humidity or less.
       Breakdown must occur at
        >280V for a 200micron sensor
        and 500V for a 300micron
        thick sensor. Breakdown will
        deemed to be a current
        greater than 100 A
       Leakage Current Stability:
        Current to increase by no
        more than 5A, at full
        depletion during 72 hours in
        vacuum. This test need only
        be performed on a batch
        basis.
Curvature
                            Curvature
   Note 50% of the 200 micron sensors FAIL
    the 200 micron curvature limit in TS
                                          Curvature

                 25

                 20
                                                                    200 Micron (R-Mech)
                 15
         Freq.




                                                                    200 Micron (Phi-Mech)
                                                                    200 Micron
                 10
                                                                    300 micron

                  5

                  0
                           10

                                15

                                     20

                                          25

                                               30

                                                    35

                                                          40

                                                               45
                      50

                            0

                                 0

                                      0

                                           0

                                                0

                                                      0

                                                           0

                                                                0
                                     Microns
                Brittleness
   Note how curved the mechanicals are
                    Cut Quality
   Marconi CO2
       All results shown tuned
   fs laser             Micron: “UV laser is as good as the fs laser

   UV laser
       Laserod
       Micron
   Cut quality may be quantified
       See GDP’s talk
                    Residuals
                                      Histogram


        120



        100



        80
Count




        60



        40



        20



         0
              0        20        40      60       80    100   120   140

                            Residual RMS / Edge (microns)
              Bin Center vs Count
                          Cut
   We believe cutting is under control and
    will meet our specifications
       Rms ~ 3 microns
   Understand angle with edge




             80 microns
                                                  Cut
    As well as visual on Smartscope
               understood                  RMS >10 micron edges

                    16
                    14
                    12
                    10                                                    200 micron
           Wafers




                     8                                                    300 micron
                     6                                                    Mechanicals (200micron)
                     4
                     2
                     0
                         1   2   3   4    5   6   7     8   9   10   11
                                         Number Edges




    inspection
                    Bad Strips
   300 sensors seem a little better

       Bad Strips   300r 300phi 200r   200phi
       Det1         16   12    33      65
       Det2              3     0       22
       Det3                    1       7
            Operating Conditions
   Temp
   Voltage
   All after 3 years of LHC operation
       Radiation effects at 23C (non ideal)
               Operating Conditions
                         0.7

                         0.6
                                             200micron/350V+rad
                         0.5
                                             250micron/500V+rad
Heating(W)




                         0.4                 300micron/500V+rad
                                             radiation
                         0.3                 200micron/350V
                                             200micron/500V
                         0.2
                                             300micron/500V
                         0.1

                          0
             -20   -10         0   10   20
                          Tcool
           Si Temperature
                   5
                  4.5
                   4
                  3.5                 200
                                      micron/350V
                   3
                                      200
DT




                  2.5
                                      micron/500V
                   2
                                      300
                  1.5                 micron/500V
                   1
                  0.5
                   0
     -20    -10         0   10   20
                   Tcool
                      Currents
                    1000
                    900
                    800
                                         200
Iblkp




                    700
                                         micron/250V
                    600
                                         200
                    500
                                         micron/500V
                    400
                                         300
                    300                  micron/500V
                    200
                    100
                      0
        -20   -10          0   10   20
                      Tcool
                   Currents
   Effects of currents negligible in terms of
    noise
         Depletion Voltage
                   1000
                   900
                   800
                   700                  200
                                        micron/350V
                   600
Vdep




                                        200
                   500
                                        micron/500V
                   400
                                        300
                   300                  micron/500V
                   200
                   100
                     0
       -20   -10          0   10   20
                     Tcool
         Operating Conditions
   300 better for temp control and handling
   200 full depletion voltage is only ~200V
             Vacuum Performance
   From Micron Semiconductor
       “Micron will not qualify sensors for operation
        above 200V in high vacuum”.
          10 days problems set in
          Field plates

          polysilicon
          Wojtek K.

       Data being made available from Micron and
        NASA/Goddard on 10-6b operation (same
        processing) AND LHCb tests.(????????)
Production
                Processing
   6 weeks -8 weeks extra for 300 micron to
    be brought to 200 status
   Voltage tests in vacuum are their only
    concern
                     Summary
   Either seem OK
   Important
       Operation of irradiated (type inverted) 300
        micron sensors at 200 micron thick voltages is
        a real option