l. Plntopolym.Sci.Techtnl.,Vol.16,No.2, 2003
observedfor the Si2p spectraas increasingprocesstemperaturesfrom "as depo" to 600 C', indicatingthat Si-N bonds in the heated polysilazanesurface
were dissociated and recombined with oxygen
In consistent withatoms to form Si-O bonds.
the Si2p shifts, intensities of the Nls or Ols
specha were decreasedor increasedwith process
The surface of thetemperatures, respectively.
thermally fabricated coatings at 600 C' werecompletely converted to SiO2 without any residual
nitrogen atoms.
As shown in the fig. 1(g), the surfaces ofphotochemically fabricated coatings are found tobe equivalent to that of the thermally fabricatedcoatings at 600 C', becauseno residual nitrogen
atom was detectedfor thesecoatings.

fabricated coatings across the depth is nearly equal
to the thermally fabricated coatings between 200 -300c'.

(rtE
7ct
Oo(tl€U)

3000

2000

1500

1000

s00

/ cm-lWavenumber

Fig. 2. IR absorptionspecta of thermally (a-f) or
photochemically(g) fabricatedcoatings : (a) as dcpo,(b) 200C', (c) 300C', (d) 400C', (e) 500C', (f) 600C",(g) VUV irradiated.

((Ét{>rvtaÉ

106100N2396/ eV
Binding
EnergyFig. l.
X-ray photoelectron
spectraof thermally(a-f)
or photochemically(g) fabricatedcoatings: (a) as depo,(b) 200C', (c) 300C', (d) 400C", (e) 500C', (0 600C',(g) VUV inadiated.
536

530

3.2 IR absorptionspectra
Figure 2 shows IR absorption spectra ofthermally (a-f) or photochemically (S) fabricatedIR
coatings from polysilazane, respectively.
gives
average chemicalabsorption spectroscopySo
information across the film depth.
complementary information can be extractablefrom the )(PS and IR spectraof the coatings. Asshown in the fig. z(a-f), N-H stretching bands at
3370 cffi-r, Si-H shetchingbands at 2160 cmr, andSi-N bands at 830 cm-l were decreased as'Whereas
increasing processing temperatures.
Si-O bands at 1060 and 450 cm-r were increased.
These spechal changes are reasonably explainablewith the structural change from (-SiH2-NH-)"(polysilazane) to SiO2 (silica glass) occurring allover the film.
As shown in the fig. 2(g), it was found that theaverage chemical structure of photochemically161

3.3 Discussion
From the XPS and IR
spectroscopic
investigationsof photochemically fabricated silica
glass coatings at room temperatures,there fbund adifference in quality between the surface nnd theFor thebulk state of the coatings.
process
photochemicallrom
conversion
polysilazaneto SiO2, it needs any kind of oxygen
supply from gas phase such as Oz molecule in dry
ar, Ol or O radicals produced by VUV photolysisof 02, becausepolysilazaneitself does not include
oxygen atoms in its molecular structure. Thus
that difference is explainable to the oxygen gas
barrier characteristicsof the photogeneratedsilica
glasslayer at the top of the silica glasscoating.
4. Conclusion
In this study, the 172 nm VUV photoirradiationfrom recently developed high pov/er xenon
excimer lamps is found to be useful to achieveroom temperature photochemical fabrication ofqvartz glasscoatings from polysilazane.
References
1. D. Seyferth et al., J. Am. Ceram. Soc., 66[1](1e83)
C13-Cr4.
2. Funayamaet al., J. Ceram. Soc. Jpn., 98 (1990)
104.
3. Suzuki et â1., Proc. Znd Japan InternationalSAMPE Symposium,216 (1991).