Method of making an optical memory disk and a product thereby

#This invention relates to a method of making an optical memory disk and a product thereby using tellurium and oxides thereof.

#The possibility of recording information by laser at high density onto any optical memory disk has been observed by several workers in recent years. Typically, such disks are produced by applying an optical thin film of metal or pigment or the like onto a base plate. For example, the following publications describe such disks:

#1. Seiji Yonezawa et al, "An Optical High Density Disk Using As-Te System Amorphous Film", which is a manuscript of a lecture given at the 26th Applied Physics Society of Japan on Mar. 27, 1967;

#The foregoing objects and other objects as well as the characteristic features of the invention will become more apparent and more readily understood by the following description and the appended claims when read in conjunction with the accompanying drawings.

#FIG. 1 and FIG. 2 are sectional views of an optical memory of the prior art;

#FIG. 3 shows deterioration of the optical memory of the prior art;

#Now there will be described a first embodiment of this invention according to FIGS. 4, 5, and 6.

#A base plate 11 is made of glass or plastic and is surface polished after being formed into a predetermined shape, for example, a disk. Base plate 11 is then fixed on a turntable 12 which is located in a vacuum chamber 13 shown in FIG. 4. A block of tellurium 14 is placed on crucible 15 for evaporation. Crucible 15 is located at a lower portion of the vacuum chamber 13 and a heater 16 is located to vaporize a quantity of tellurium 14. The air in vacuum chamber 13 is exhausted from exhaust pipe 17 by a vacuum exhausting pump (not shown). Base plate 11 rotates with turntable 12, and heater 16 is energized. Tellurium vapor evaporates from tellurium 14, and a tellurium film 18 is formed on base plate 11 about 300 A in thickness.

#Next, base plate 11 is introduced into an oxidizing apparatus 19 shown in FIG. 5 which is made of a conveyor 20, drive pulleys 21 for driving conveyor 20, heater 22 which is located beneath conveyor 20, ultra-violet irradiators 23 and cover 24. Base plate 11 and tellurium film 18 are heated to at least about 50.degree. C. and preferably about 100.degree. C. by heater 22 and are irradiated with 50 mW/cm.sup.2 ultraviolet rays by irradiator 23 for about 30 minutes under low humidity. Tellurium film 18 is oxidized on its surface by this treatment and the oxidation is promoted by the heat. Typically, several layers of oxides will form, each layer being a different oxide. The number of layers and their composition can be controlled according to well known principles.