TITANIUM MONONITRIDE AS AN ANTIREFLECTION LAYER ON ALUMINUM METALLIZATION FOR SUBMICRON PHOTOLITHOGRAPHIC PATTERNING

Titanium mononitride (TiN) as an antireflection layer over aluminium metallization on a Si wafer (Al/Si) in submicron photolithography has been studied. Both notching and standing wave effects of non-dyed and dyed positive resists coated on TiN/Al/Si are eliminated with 0.8-mu-m designed linewidth test patterns using a g-line stepper under defocus of 0, +1 and -1-mu-m. TiN/Al/Si has a sheet resistivity of about 45 m-OMEGA/square, similar to Al/Si up to tested TiN thickness of 0.12-mu-m. Thus, TiN in the TiN/Al/Si system functions not only as a conventional diffusion barrier, but also as an antireflection layer and as a metallization layer. Selective reactive ion etching between Al and TiN can be achieved in an etchant gas mixture of 3:7 CHF3:CF4 with a DC bias of -100 V.