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   .  The backside of the wafer is always towards the "H" bar in the cassette.
   .  Some general facts about Bow on an SOI wafer. The bow is caused
      by the stress of  having an oxide on only one side of the handle. The
      thicker the oxide the higher the stress, the thinner the handle the
      easier it is to Bow.
      Possible Solutions: 

          1)  Have a thicker handle
          2)  Use a thinner burried oxide
          3)  Leave the oxide on the back of the handle wafer.
          4)  Grow the oxide on the device wafer


   .  Device fringes - on fusion bonded SOI wafers with device
      thicknesses less than 8um the oxide fringes are normally visible.
      The fringes are caused by angstrom thickness variations in the
      oxide. This is also another way to tell the device side or font side of 
      a fusion bonded SOI Wafer. 

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