Page 108 - Sami Franssila Introduction to Microfabrication
P. 108

Thin-film Growth and Structure 87





















                                 (a)                                     (b)





























                                                    (c)
           Figure 7.16 Step coverage in different CVD processes: (a) phosphorus doped CVD oxide with conformal (100%) step
           coverage, (b) undoped CVD oxide with flow-like profiles and (c) PECVD oxide from silane/nitrous oxide reaction leads
           to a void formation. Reproduced from Cote, D.R. et al. (1995), by permission of IBM





                                        (a)                      (b)




                                        (c)                      (d)
           Figure 7.17 (a) Gap filling with conformal step coverage. (b) Conformal deposition of a larger gap with the same
           process does not lead to gap filling but the original step height remains. (c) Void and (d) cusp are formed when step
           coverage is maximum at the step corner
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