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7. Strip the Photoresist: Stripping the photoresist off completely is important before the next step.
No photoresist known can withstand furnace temperatures.
8. Boron Predeposition: In a furnace at 950 degrees Celcius with oxidized Boron Nitride
wafers present, the silicon wafers are "doped" with boron just inside the areas where the oxide
was removed. Boron is a P-type impurity in silicon since it only has 3 electrons in it's valence
shell. Remember, it will only take several parts per billion to override the
the original phosphorus concentration which made the silicon N-type. The actual source of the boron
is boron oxide from the oxidized boron nitride wafers, and in addition to the boron that diffuses
into the silicon, a thin layer of oxide (heavily doped with boron) grows on the
surface. This layer is called "Borosilicate Glass".
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