Maximizing step coverage during blanket tungsten low pressure chemical vapor deposition

Timothy S. Cale, Manoj K. Jain, Gregory Raupp

Research output: Contribution to journalArticlepeer-review

5 Scopus citations


A significant range of step coverages can be realized in the low pressure chemical vapor deposition of blanket tungsten films by either hydrogen reduction or silane reduction of tungsten hexafluoride, at a specified deposition rate. The step coverage realized in a single-wafer reactor (SWR) depends on the operating conditions used, e.g. feed flow rate ratios and reactant conversion level. The pseudosteady state approximation to the diffusion-reaction model is used to select the partial pressure ratios at the wafer surface which lead to a balance between reactant availability and consumption. The complete transient model is then used to demonstrate that the reactant pressure ratio obtained using this "availability analysis" maximizes the step coverage at a specified deposition rate. The reactant pressure ratio at the feature mouth is related to the inlet feed rate ratio and reactor conversion level for an SWR, assuming a well-mixed reactor. Guidelines for SWR operation are given to obtain the maximum step coverage for each system. In well-mixed reactors, the optimum feed ratio is a linear function of conversion, and approaches the stoichiometric ratio as the conversion approaches unity.

Original languageEnglish (US)
Pages (from-to)51-60
Number of pages10
JournalThin Solid Films
Issue numberPART 1
StatePublished - 1990

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films
  • Metals and Alloys
  • Materials Chemistry


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