Comparative study of the low pressure chemical vapor deposition processes of W and Mo

Journal Article · Fri Jul 01 04:00:00 UTC 1988 · J. Electrochem. Soc.; (United States)

DOI:https://doi.org/10.1149/1.2096141· OSTI ID:6506027

Lifshitz, N; Green, M L ^[1]

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1. AT and T Bell Labs., Murray Hill, NJ (US)

The authors present a comparative study of low pressure chemical vapor deposition (LPCVD) of the refractory metals W and Mo on silicon substrates by the silicon reduction of their fluorides WF/sub 6/ and MoF/sub 6/. Their results contribute a new insight into the LPCVD process, explaining both the microstructure of the films and the kinetics of their deposition. The processes of W and Mo deposition follow a very similar course as indicated by the similarity of the deposits; both films are porous, and their interfaces with silicon have identical textures. Moreover, from experiments with excess SiF/sub 4/, even the intermediate reactions contributing into the deposition process follow similar course. Despite the similarity of W and Mo deposition the two processes exhibit a puzzling difference. Mo films grow linearly with time, whereas tungsten deposition in inhibited at an early stage by a self-limiting effect. The authors propose a mechanism in which the nonvolatile lower fluoride of W interrupt further deposition of metal tungsten. Their model is supported by SIMS studies. In terms of the model, it becomes clear why the self-limiting effect never occurs during Mo deposition: since all Mo subfluorides are volatile, they cannot act as a blocking agent and interrupt the process. The difference in volatility between Mo-F and W-F compounds may also explain why the process of Mo deposition via hydrogen reduction never loses its absolute selectivity, whereas the analogous tungsten process is plagued by the selectivity loss.

• OSTI ID: 6506027
• Journal Information: J. Electrochem. Soc.; (United States), Journal Name: J. Electrochem. Soc.; (United States) Vol. 135:7; ISSN JESOA
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360601* -- Other Materials-- Preparation & Manufacture
360602 -- Other Materials-- Structure & Phase Studies
CHEMICAL COATING
CHEMICAL REACTIONS
CHEMICAL VAPOR DEPOSITION
CRYSTAL STRUCTURE
DATA
DEPOSITION
ELEMENTS
EXPERIMENTAL DATA
FILMS
FLUORIDES
FLUORINE COMPOUNDS
HALIDES
HALOGEN COMPOUNDS
INFORMATION
LOW PRESSURE
METALS
MICROSTRUCTURE
MOLYBDENUM
MOLYBDENUM COMPOUNDS
MOLYBDENUM FLUORIDES
NUMERICAL DATA
REFRACTORY METAL COMPOUNDS
SILICON COMPOUNDS
SILICON FLUORIDES
SURFACE COATING
TECHNOLOGY ASSESSMENT
THIN FILMS
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
TUNGSTEN
TUNGSTEN COMPOUNDS
TUNGSTEN FLUORIDES