Effects of plasma and vacuum-ultraviolet exposure on the mechanical properties of low-k porous organosilicate glass

Journal Article · Mon Jul 28 00:00:00 EDT 2014 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4891501· OSTI ID:22308545

Guo, X.; Shohet, J. L. ^[1]; Jakes, J. E. ^[2]; Banna, S. ^[3]; Nishi, Y. ^[4]

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1. Plasma Processing and Technology Laboratory and Department of Electrical and Computer Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States)
2. Performance Enhanced Biopolymers, USDA Forest Service Forest Products Laboratory, Madison, Wisconsin 53726 (United States)
3. Applied Materials, Sunnyvale, California 94085 (United States)
4. Stanford University, Stanford, California 94305 (United States)

The effects of plasma exposure and vacuum-ultraviolet (VUV) irradiation on the mechanical properties of low-k porous organosilicate glass (SiCOH) dielectric films were investigated. Nanoindentation measurements were made on SiCOH films before and after exposure to an electron-cyclotron-resonance plasma or a monochromatic synchrotron VUV beam, to determine the changes of film hardness, elastic modulus, and crack threshold due to these exposures. This permits the effects of ion bombardment and photon bombardment to be analyzed separately. The role of energetic ions was examined with a variety of inert plasma-exposure conditions. The role of VUV photons was analyzed as a function of synchrotron photon energy. It was found that both energetic ions and VUV photons with energies larger than the bond energy of the Si-O bond cause a significant increase in film hardness along with a smaller increase in elastic modulus and crack threshold. Differential Fourier transform infrared spectra and x-ray photoemission spectroscopy results show that the energetic ions affect the SiCOH properties mainly through physical bombardment, during which the ions transfer their momentum to the Si-O-Si backbone and transform them into more energetically stable Si-O-Si network structures. This results in the Si-O-Si network structures becoming densified. VUV photons assist reaction that increase the number of bridging O{sub 3}≡Si-O-Si≡O{sub 3} bonds and deplete nonbridging O{sub 3}≡Si-O and C-Si≡O{sub 3} bonds. This increased degree of cross linking in porous organosilicate dielectrics can substantially enhance their hardness and elastic modulus while showing no significant film shrinkage or densification.

• OSTI ID: 22308545
• Journal Information: Journal of Applied Physics, Vol. 116, Issue 4; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
BINDING ENERGY
CROSS-LINKING
DIELECTRIC MATERIALS
ELECTRON CYCLOTRON-RESONANCE
FAR ULTRAVIOLET RADIATION
FILMS
FOURIER TRANSFORMATION
GLASS
HARDNESS
INFRARED SPECTRA
MONOCHROMATIC RADIATION
PHOTOEMISSION
PHOTONS
PLASMA
POROUS MATERIALS
SILICATES
SPECTROSCOPY
X RADIATION