A microstructural study of LPCVD tungsten thin films for use as contact material to silicon

Thesis/Dissertation · Fri Jan 01 04:00:00 EST 1988

OSTI ID:7154818

Paine, D C

Tungsten deposition by low-pressure chemical vapor deposition (LPCVD) techniques is ideally suited to integrated-circuit applications. Its unique chemistry allows selective tungsten deposition on exposed silicon and not on surrounding passivation. Several problems, however, impede the widespread adoption of this technology. In an effort to resolve some of these problems, the microstructure, interfacial morphology, and crystalline phase of tungsten deposited on silicon were studied. A metastable phase of tungsten known as {beta}-tungsten - previously never observed in LPCVD tungsten films - was seen in the contacts on patterned wafers but not under identical deposition conditions on bare, unpatterened silicon wafers. This phase is of interest because, when produced by sputtering, it has a resistivity that is ten times greater than that of the stable {alpha}-tungsten. The growth of {beta}-tungsten in preference to {alpha}-tungsten was seen to depend on: reactor configuration, temperature, H{sub 2} dilution of WF{sub 6} and wafer surface preparation. Models based on the chemistry of LPCVD tungsten deposition are proposed to explain these experimental results. Blanket deposits of {beta}-tungsten were produced in order for a detailed study of the metastable phase to be carried out using large area sampling techniques.

• Research Organization: Stanford Univ., CA (USA)
• OSTI ID: 7154818
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360102 -- Metals & Alloys-- Structure & Phase Studies
42 ENGINEERING
426000* -- Engineering-- Components
Electron Devices & Circuits-- (1990-)
CHEMICAL COATING
CHEMICAL VAPOR DEPOSITION
CRYSTAL STRUCTURE
DEPOSITION
ELECTRONIC CIRCUITS
ELEMENTS
FABRICATION
FILMS
INTEGRATED CIRCUITS
INTERFACES
METALS
MICROELECTRONIC CIRCUITS
MICROSTRUCTURE
PHASE STUDIES
SILICON COMPOUNDS
SUBSTRATES
SURFACE COATING
THIN FILMS
TRANSITION ELEMENTS
TUNGSTEN