PINHOLE FORMATION IN SOLID-PHASE EPITAXIAL FILM OF COSI2 ON SI(111)

The long-standing pinhole problem in solid phase epitaxial growth of a CoSi2 film on Si(111) has been revisited with in situ scanning tunnel ing microscopy. While the as-deposited film with 5 Angstrom of Co at r oom temperature shows a smooth granular texture with original substrat e terraces remaining intact, annealing at 580 degrees C produces an ep itaxial CoSi2 film with large pinholes enclosed by a thin ring CoSi2, exhibiting a volcano feature. Quantitative analysis shows that the for mation of pinholes is a result of rapid Si outward diffusion from bulk to surface, and of the subsequent Si reaction with Co an the outer su rface. Evidence suggests that inhibiting the Si diffusion channels dur ing the thermal annealing process is the key to solving the pinhole pr oblem. (C) 1998 American Institute of Physics.