| 摘要 |
A method is described for improving the exposure focus for modern steppers used in the lithography of semiconductor substrates such as wafers. A wafer is sawed from a semiconductor ingot in a particular direction relative to a reference point on the ingot. As a result of the sawing, a series of raised and recessed formations manifest on the surface of the wafer. After various layers have been added to the wafer and the photoresist layer is ready to be removed, the wafer is aligned with the stepper so that a dynamic focus area of the stepper is aligned with the formations and/or the sawing direction. Such alignment improves the critical dimension control and reduces variability in printing small geometry features during lithography, resulting in higher yields.
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