Semiconductor Devices: Physics and Technology, 3rd Edition

13

Lithography and Etching

13.1 OPTICAL LITHOGRAPHY

13.2 NEXT-GENERATION LITHOGRAPHIC METHODS

13.3 WET CHEMICAL ETCHING

13.4 DRY ETCHING

SUMMARY

Lithography is the process of transferring patterns of geometric shapes on a mask to a thin layer of radiation-sensitive material (called resist) covering the surface of a semiconductor wafer.¹ These patterns define the various regions in an integrated circuit such as the implantation regions, the contact windows, and the bonding-pad areas. The resist patterns defined by the lithographic process are not permanent elements of the final device but only replicas of circuit features. To produce circuit features, these resist patterns must be transferred once more into the underlying layers comprising the device. The pattern transfer is accomplished by an etching process that selectively removes unmasked portions of a layer.²

Specifically, we cover ...