Significant figures - Vector symbols

The first 200 words of this essay...

Andy Somody

97300-6222

ENSC 495

Assignment #2

Significant figures

Vector symbols

4-1). The linear coefficient for the thermal expansion of quartz used for a mask plate is 5.5x10-7 oC-1. This implies that when the mask plate is heated or cooled, its length changes by an amount proportional to the original length, the change in temperature, and the linear coefficient for thermal expansion of quartz. Mathematically, we can describe this relationship with the following equation:

where ?T is change in the temperature of the mask plate, ?l is the change in length of the mask plate caused by the thermal expansion, ? is the linear coefficient for the thermal expansion of quartz, and l0 is the largest distance from the portion of the mask plate that remains aligned during expansion to any portion on the mask plate that becomes misaligned. Therefore, ? = 5.5x10-7 oC-1. Alignment accuracy across a 6 inch (15 cm) silicon substrate must be maintained from one layer to the next within 0.5 um. The mask must be properly aligned on the wafer. However, if there is a change in the temperature of the mask plate during alignment,