R&D of CVD DIAMONd in SUMITOMO ELECtric INdustries
T. Imai
Itami R&D
Laboratories, Sumitomo Electric Industries, LTD.
Koya-Kita , Itami,
Hyogo, 664-0016, Japan
Abstract
Sumitomo
Electric Industries (SEI) has developed several kinds of diamond products by using
CVD methods. The R&D mainly have been performed in Itami R&D
Laboratories since 1981. SEI’s CVD
diamond products includes speaker diaphragms, tape-automated bonding tools
(TAB), 3-inches mirror-polished diamond–coated wafers and surface acoustic wave
(SAW) devices are released from 1985. And the results of research consists the
investigation of the atomic structure on epitaxial-grown diamond, the
well-controlled single domain epitaxial growth, CVD-grown high quality
free-standing diamond with 8mm diameter,
the forming of sharp diamond emitter tips with 200nm diameter at the
tops, and the diamond coated and
polished bearings. The latter there themes were started as sub-themes of
Frontier Carbon Projects since 1998.
The status of SEI’s R&D are as follows,
(1)
The
4-inches-diameter diamond-coated wafer is developed for next generation diamond
SAW devices. The diamond layer of the wafer is about 10 microns in thickness.
Their surface are mirror-polished and the roughness is under 5nm in average.
(2)
The Lithium
Niobate (LN) piezoelectric film are developed for high performance and
wide-band diamond SAW devices. The LN film which highly oriented to c-axis is
deposited by KrF excimer laser ablation method. The structure of laminated
LN/diamond are expected to obtain higher electro-mechanical coupling
coefficients than ZnO/diamond structure as well as high acoustic velocity.
(3)
The plasma
assisted CVD reactor optimized for the homoepitaxial growth of single
crystalline diamond is designed and constructed. The uniformity of plasma
parameter and homoepitaxial growth conditions are enough to grow large size
single crystalline diamond as 20mm diameter. The large free-standing single
crystalline diamond with 8mm diameter is already obtained.
(4)
A diamond coated
bearing is manufactured, and its inner-diameter is 10mm and length is also
10mm. About 10 microns CVD diamond are coated on Si3N4 substrate and polished
under roughness of 1 micron.
Some of these
works were supported by FCT Project, which was consigned to JFCC by NEDO.
Keywords:
homoepitaxial growth, single crystal,
piezoelectric, surface acoustic wave, bearing
Takahiro IMAI
Itami R&D Laboratories, Sumitomo Electric
Industries, LTD.
Koya-Kita, Itami, Hyogo 664-0016, Japan
Fax: +81-727-71-0407, Phone: +81-727-71-0621