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Technology Stocks : Intel Corporation (INTC)
INTC 46.47-4.5%Jan 30 9:30 AM EST

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To: Aaron Cooperband who wrote (40558)11/17/1997 9:12:00 PM
From: Paul Engel  Read Replies (2) of 186894
 
Aaron - Re: "could this be what theta refers to?, "

Yes, you are correct - in both cases - Theta refers to rotation in the x-y plane - the plane of the wafer.

As you noted (and I didn't discuss it) the "z" height of the stage is adjustable in order to insure proper depth of focus. The focal plane is very shallow - a micron and usually less - with the high numerical aperture lenses used in these steppers. Accordingly, the plane of the wafer's top surface is munutely adjusted (z axis) to insure proper focus.

This is also done on a die-by-die basis.

Paul
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