Site: Canon Research Center
Advanced MM Device Division
Atsugi, Kanagawa 243-01, Japan
Date Visited: 13 March 1998
WTEC: M. Kryder (report author), M. Keshner
Canon is a major corporation with over 75,000 employees and sales of over $22 billion in 1996. Its products include a large number of image-based systems including copiers, facsimile machines, image scanners, projectors, cameras, printers, displays, camcorders, lenses, binoculars, medical imaging systems, and photolithographic systems for the semiconductor industry.
The Canon Research Center carries out projects in biotechnology, optical technology, electron beam technology, advanced materials and nanometer technology.
Mr. Takimoto presented an overview of the work on probe recording technology at the Canon Research Center. He explained that the work on probe recording has been carried out by the groups working on advanced materials and on nanometer technology. There are approximately 10 people from the advanced materials area and 20 from the nanometer technology area who are involved.
The Advanced Materials Group discovered the "switching memory" phenomenon of Langmuir Blodgett (LB) films. LB films are ultra-thin films composed of organic mono-layers on a substrate. Canon researchers found that when electrical current is applied to a certain type of LB film between a gold and aluminum layers, it displays a change in electrical resistance. This work was described in an article by Sakai et al. (1988).
The Nanometer Technology Group is now exploring the use of these LB films as a medium for probe recording using a scanning probe microscope. Researchers showed the WTEC team data indicating that a micromachined Pt-Rh probe could be used to repeatably write 10 nm spots on such media. The write time was quoted as being less than 1 microsecond and the read time as being less than 10 microseconds. The researchers reported that reproducibility of the recording and readback process was greater than 104. Although the LB materials had been shown to be rewritable in a metal/LB/metal configuration, they reported that using the SPM, it was only write once. The researchers were trying to understand the reason they had not been able to achieve rewritability.
They also reported that others had found a similar conductance change phenomenon in GeSbTe thin films, but said that these materials were rougher than the LB films, which had a peak-to-valley roughness of less than 1 nm.
The Canon researchers indicated that they were interested in developing these ultra-high density memory devices for server applications and for use in camcorders, which could record HDTV quality images.
They indicated they were not currently working on near-field optical probe storage, but said they were following the development of that technology.
H. Yoshida also described work on "domain wall displacement detection" (DWDD), which was first presented at the MORIS/ISOM Conference in Yamagata, Japan, Oct. 1997. This technology enables one to read out marks smaller than the diffraction limit of optical resolution from a magneto-optical disk, and appears to be a very promising technology for extending the density of magneto-optical recording technology. This work was done at the Products Technology Research Center, rather than the Canon Research Center.
Canon researchers took the WTEC team to the laboratory where they showed an LB film coating apparatus of a very clever design and on which they could continuously coat A4 size sheets. They asserted this was the only system that could do continuous coating.
The researchers then exhibited the playback of an array of 10 nm sized spots recorded on their media. They also showed panel members SEM images of a probe array containing eight Pt probe tips. They had developed a very repeatable process for making the probes, which were very clean in appearance. In operation these probes were run in contact with the media, but the load was very light and there was no detectable wear of either the medium or the probe itself.
Canon has about 30 people working on MEMS-based probe recording on a Langmuir-Blodgett film. The researchers are able to selectively write 10 nm sized spots in arrays and play them back very repeatably. They appear to have excellent MEMS processing capabilities and have also developed a continuous coating apparatus for Langmuir-Blodgett films. Canon researchers have interest in applying these very advanced storage technologies to video cameras and server applications. Currently the technology is write-once, but they are working to make it rewritable.
In the Products Technology Research Center, Canon also has an active research group working on magneto-optical recording. Recently this group reported on a new method of high-density recording called "domain wall displacement detection." This technology appears to be very promising for achieving densities beyond the diffraction limit and appears competitive with the best of the magnetic super resolution techniques.
Canon fact book. 1997/98.
The Canon story. 1997/98. Canon Research Center brochure.
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Shiratori, T., E. Fujii, Y. Miyaoka and Y. Hozumi. High density magneto-optical recording with domain wall displacement detection. J. Magn. Soc. Jpn., Vol.22. Supplement No. S2(1998), pp.47-50.
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