Target Technology Company, LLC (Irvine, CA) inventor Han H. Nee has developed new metal alloys for the reflective or the semi-reflective layer of an optical storage medium such as compact discs. These silver alloys are used in a thin film with the thickness of 8 to 12 nanometers for the semi reflective layer of DVD dual layer discs according to U.S. Patent 7,645,500.
Nanometer silver-based thin film alloys provide a highly reflective or semi-reflective coating layer on optical discs. Elements that can be added to silver to produce useful silver alloys include zinc, aluminum, copper, manganese, germanium, yttrium, bismuth, scandium, and cobalt. These alloys have moderate to high reflectivity and reasonable corrosion resistance in the ambient environment.
The silver based nanolayer will compete with reflective layers which are usually made of aluminum or an aluminum alloy and are typically between about 40 to about 100 nanometers (nm) thick.
Target Technology metallic alloys for use in thin film reflective layers have high reflectivity, sputtering characteristics similar to gold, are corrosion resistant, and are generally less expensive than gold. A number of these alloys can also be used as semi-reflective layers (coatings) in optical storage devices such as DVD-dual layer devices.
One embodiment, provides silver-based alloys with sufficient chemical, thermal and optical properties to satisfy the functional requirements of the reflective layer in a DVD-RW or DVD+RW disc and other current or future generations of optical discs in which reflectivity, corrosion resistance, and ease of application are all important requirements for a low cost and high performance product.
One embodiment, provides silver-based alloys with sufficient chemical, thermal and optical properties to satisfy the functional requirements of the reflective layer in a DVD-RW or DVD+RW disc and other current or future generations of optical discs in which reflectivity, corrosion resistance, and ease of application are all important requirements for a low cost and high performance product.
The key component of a CD-R disc is the organic dye, which is made from solvent and one or more organic compounds from the cyanine, phthalocyanine or azo family. The disc is normally produced by spin coating the dye onto the disc and sputtering the reflective layer over the dye after the dye is sufficiently dry. But because the dye may contain halogen ions or other chemicals that can corrode the reflective layer, many commonly used reflective layer materials such as aluminum may not be suitable to give the CD-R disc a reasonable life span. So being, frequently gold must be used to manufacture a recordable CD. But while gold satisfies all the functional requirements of CD-R discs, it is a very expensive solution.
Recently, other types of recordable optical disks have been developed. These optical disks use a phase-change or magneto-optic material as the recording medium. An optical laser is used to change the phase or magnetic state (microstructural change) of the recording layer by modulating a beam focused on the recording medium while the medium is rotated to produce microstructural changes in the recording layer. During playback, changes in the intensity of light from the optical beam reflected through the recording medium are sensed by a detector. These modulations in light intensity are due to variations in the microstructure of the recording medium produced during the recording process. Some phase-change and/or magneto-optic materials may be readily and repeatedly transformed from a first state to a second state and back again with substantially no degradation. These materials may be used as the recording media for a compact disc-rewritable disc, or commonly known as CD-RW.
Recently, other types of recordable optical disks have been developed. These optical disks use a phase-change or magneto-optic material as the recording medium. An optical laser is used to change the phase or magnetic state (microstructural change) of the recording layer by modulating a beam focused on the recording medium while the medium is rotated to produce microstructural changes in the recording layer. During playback, changes in the intensity of light from the optical beam reflected through the recording medium are sensed by a detector. These modulations in light intensity are due to variations in the microstructure of the recording medium produced during the recording process. Some phase-change and/or magneto-optic materials may be readily and repeatedly transformed from a first state to a second state and back again with substantially no degradation. These materials may be used as the recording media for a compact disc-rewritable disc, or commonly known as CD-RW.
