Hello All,

         I am trying to fabricate Piezoresistive Pressure Sensors, as
part of the project work associated with my part-time Master's Degree. I
need to know how exactly to orient the P type piezoresistors in the [110]
direction. I work on 100mm diameter, {100} orientation, N type Silicon
wafers. The resistors are formed by Boron Ion Implant into the silicon
substrate.

         Presently, I align the primary wafer flat parallel to the mask
edge (the piezoresistors are parallel to the mask edge). This is however
only an approximate method of alignment, and the resistors do not align
exactly in the [110] direction. This inturn affects the output of my
resistive Wheatstone bridge.

Could someone suggest a method that can repeatedly be used to exactly
align the resistors (on a 100mm silicon wafer) in the [110] direction?
It would be a great help.

Thanks in advance.

With Best Regards,
Sriram
Senior Process Engineer,
Bharat Electronics
Bangalore 560 013
INDIA