Litho performance

Resolution, Dose Matrix, Under/overdevelopment, characterization techniques

Resolution test patterns

Pitch: the spacing between corresponding points of an array. Known in math as the period:

$$T: f(x+T=f(x)$$

A line array with 50% duty cycle is a pattern with linewidth=x, spacewidth=x, and period=x+x=2x

Isolated lines take spacewidth>>linewidth giving enough room for underexposed tails to extend

Characterization Techniques

Visual inspection: Optical Microscope

Gives inexpensive and immediate visual feedback: interference colours show resist thickness variation.

Cross-section and 3D mapping: Profilometry, AFM