Disadvantages: the mask separation from wafer causes greater diffraction and leads to low resolution (~1-2 um or slightly better), less repeatable than contact methods and the mask is expensive since it has the same size of the wafer and no magnification.

Projection printing

Mask image is projected a distance from the mask and de-magnified to a smaller image: 1:4-1:10 magnification

Advantages : Can be very high resolution (~0.07 um or slightly better), No mask contact results in almost no mask wear (high production compatible), mask defects or particles on mask are reduced in size on the wafer.

Disadvantages : Extremely expensive and complicated equipment, Diffraction effects limit accuracy of pattern transfer.