1) resolution (based on Rayleighs criterion)
: the ability of an optical system to distinguish closely spaced objects.
* minimum resolution of lithographic tools
-. the dimension of minimum linewidth or space that the machine can adquately print (or resolve)
-. it depends on the photoresist and etching technology as well as the resolution of the aligner.
k1, : process dependent constants
( k1 = 0.5 for a research environment, 0.8 for a production process)
2) Depth of focus
: focus tolerance
-. Focus errors result from errors in autofocusing, wafer bow, and topography
-. It is desirable for the latent image in the resist to remain in focus throughout the thickenss of the resist.
Depth of Focus
k1, k2 : process dependent constants
( k1 = 0.5 for a research environment, 0.8 for a production process, k2 = 0.5 )
3) pattern registration capability
: a measure of the degree to which the pattern being printed can be "fit" relative to a previously printed pattern
4) dimensional control
: the ability to produce device feature sizes over the entire wafer surface with high accuracy and precision