United States Patent [191 [11] Patent Number: 4,786,538 Saito et al. [45] Date of Patent: Nov. 22, 1988 [54] OPTICAL RECORDING MEDIUM FORMED 4,500,889 2/1985 Wada et al. .. 430/945 OF CHALCOGENIDE OXIDE AND METHOD 4,579,807 4/1986 Blonder et al. ................ .. 346/1351 FOR PRODUCING THE SAME 4,645,685 2/1987 Murayama . [75] Inventors: Koichi Saito; Hideki Kobayashi, both FOREIGN PATENT DOCUMENTS 1 of Kurashiki; Junji Nakagawa, 54-3725 2/1979 Japan . Ichikawa; Yoichi Murayama, Tokyo, 58-7394 l/1983 Japan . all of Japan 58-158056 9/1983 Japan . 0203094 11/1983 Japan .............................. .. 346/1351 [73] Assignee: Kuraray Co., Ltd., Okayama, Japan 58-189850 11/1983 Japan . [21] Appl. No.: 82,909 60-179956 9/1985 Japan .............................. .. 346/1351 [22] Filed: Aug. 10, 1987 Primary Examiner-John E. Kittle Assistant Examiner-Betsy Bozzelli Attorney, Agent, or Firm-Armstrong, Nikaido, Related U.S. Application Data Marmelstein & Kubovcik [63] Continuation of Ser. No. 808,572, Dec. 13, 1985, aban doned. [57] ABSTRACT [30] Foreign Application Priority Data Metal tellurium is vaporized under the atmosphere of oxygen gas and/or inert gas formed into a plasma by a Dec. 13, 1984 [JP] Japan 59-264128 high frequency power to thereby form a tellurium oxide Dec. 13, 1984 [JP] Japan 59-264129 (TeOx, OéXéZ) layer. The tellurium oxide layer Dec. 13, 1984 [JP] Japan 59-264130 formed in accordance with the present method is stabi Dec. 13, 1984 [JP] lized, and a suboxide having a high sensitivity which has Dec. 13, 1934 [JP] , Japan been considered to be unsuitable as an optical recording Dec. 13,1984 [JP] ‘medium due to the lack of stability can be utilized. [51] 1111. cu . .. G11B 7/24 High frequency power, gas pressure and vaporization [52] U.S. c1. .................................... .. 428/64; 428/701; speed of metal tellurium can be varied to thereby vary 430/271; 430/273; 430/945; 346/1351 the value X of TeOx from 0 to 2. When the TeOx ?lms [58] Field of Search ..................... .. 430/945, 271, 273; whose value X thicknesswise is different are formed 428/64, 701; 346/1351 continuously within one and the same vessel and the vaporization speed is made to zero, oxidization of a film [56] References Cited surface may be carried out. Thereby, the T602 ?lm may U.S. PATENT DOCUMENTS be formed on the surface, and an optical recording medium may be obtained which is extremely stable and 3,971,874 7/1976 Ohta et a1. ........................ .. 428/432 4,370,391 l/1983 Mori et al. ........ .. has excellent adhesive properties between the substrates and between the layers. 4,385,3764,403,231 9/5/1983 1983 TakaokaAndo et al.et al........ .. 4,433,340 2/ 1984 Mashita et a1. ................... .. 430/945 7 Claims, 1 Drawing Sheet US. Patent Nov. 22, 1988 4,786,538 FIG. I’ IIIIIII'I'I'I‘ FIG. F/G. 4,786,538 1 2 sheet, a polycarbonate sheet etc. are used, these materi OPTICAL RECORDING MEDIUM FORMED OF als are relatively large in gas transmission rate, therefore CHALCOGENIDE OXIDE AND METHOD FOR posing a problem in that vapor, oxygen and the like PRODUCING THE SAME enter with the passing of time to oxidize the chalcogen ide suboxide, thus reducing the sensitivity. This application is a continuation of application Ser. Many techniques intended to improve the stability of No. 808,572, ?led Dec. 13, 1985, now abandoned. the chalcogenide group recording media have already been disclosed, for example, such as scattering into BACKGROUND OF THE INVENTION metal having good corrosion-resistance (Japanese Pa 1. Field of the Invention tent Application Laid-Open No. 164,037/ 83), coating The present invention relates to an optical recording with an organic material (Japanese Patent Application medium, and particularly to an optical recording me Laid-Open Nos. 21,892/81, 125,248/83 and dium formed of a chalcogenide oxide that may be re 203,643/ 83); coating with an inorganic material Japa corded and erased by light, preferably, formed of a nese Patent Application Laid-Open No. 199,449/83); tellurium oxide, and a method for producing the same. forcible oxididation of a surface (Japanese Patent Appli More speci?cally, the invention relates to an optical cation Laid-Open Nos. 3,442/81, 94,144/83, 189,850/ 83 recording medium whose optical recording properties and 2,245/ 84), which often involve cumbersome opera are retained in a stabilized condition for a long period of tion, and insuf?cient effect). time and which has excellent adhesive properties rela tive to a substrate. 20 SUMMARY OF THE INVENTION 2. Description of the Prior Art Accordingly, it is an object of the invention to pro For the optical recording medium, there are known a vide an optical recording medium and method for pro system for forming small holes or bubbles by the heat ducing the same which improves the stability for a long energy of a laser beam and a system for varying the period of time. It is another object of the invention to optical characteristics of a ?lm. In the former system, 25 provide an optical recording medium and method for since a change of uneven shape occurs in a recording producing the same which display excellent effects also ?lm layer during the recording, the recording ?lm and in terms of adhesive properties relative to the substrate. the substrate are liable to change in quality and produce These objects of the present invention are accom corrosion with the passage of time, and therefore, usu plished by an optical recording medium in which by a ally two recording media are formed into an air sand metal tellurium vapor passing through oxygen gas and wiched construction for use. In the latter, however, /or inert gas formed into a plasma by a high frequency such construction is not necessary and two recording electric power, (a) a tellurium or tellurium suboxide media can be simply bonded together for use, and there (TeOx, 0§x<2) layer and or (b) a tellurium dioxide fore, this system has an advantage in that the manufac (T602) layer are laminated, or (a) a tellurium dioxide turing step may be simpli?ed considerably. Among (TeOg), (b) tellurium and/or a tellurium suboxide materials used for the latter system, there is known a (TeOx, 0§x<2) and (c) a tellurium dioxide (TeOZ) material having high sensitivity, that is, a material layers are laminated. Alternatively, an optical recording whose optical characteristics are greatly changed with medium can be used in which a ?lm is formed so that respect to a predetermined incident light intensity, such tellurium or tellurium oxide (TeOx) is formed and the as a chalcogenide oxide, particularly, a tellurium oxide 40 proportion x of the oxygen component in the direction TeOx, where x is 0<x<2.0. of the thickness the layer changes from 0 to 2. Known methods for producing a tellurium oxide ?lm The aforementioned optical recording medium is include a method which comprises placing a powder of accomplished in such a manner that in forming a tellu TeOz on a boat-type heater of W or Mo, heating the rium or tellurium oxide (TeOx, O§x<2.0) layer from heater, and effecting vacuum evaporation while reduc 45 metal tellurium passing through inert gas, oxygen gas or ing part of the TeOz; a method which comprises intro a mixture thereof (which are generally merely some ducing a mixture of TeO; powder and various reduced times referred to as “gas”) formed into a plasma by a metals into a quartz crucible under vacuum, and a high frequency electric power on the substrate, a ?lm is method which comprises using individual vaporizing formed while varying the partial pressure of oxygen of sources to simultaneously vaporize TeOz and metal Te. said gas or while varying the high frequency power. Among these methods, the former two methods are Alternatively, the optical recording medium is accom simple but in these two methods, the boat or reducing plished by being oxidized in the plasma after the tellu force of the reducing metal changes during the evapora rium oxide TeOx 0§x<2, preferably O§x=l.0) has tion, and therfore these methods have a disadvantage in been formed from the metal tellurium vapor passing that the composition of the vaporized ?lm in the wall through the inert gas, oxygen gas or the mixture thereof thickness direction is subjected to an irregular change. formed into the plasma by the high frequency power on According to the method which uses two vaporizing the substrate. sources, an even ?lm can be obtained. The ?lm of TeOx produced by this method wherein x is less than 1 has the BRIEF DESCRIPTION OF THE DRAWINGS advantages in that the blackening initiation temperature FIG. 1 is a structural view of an optical recording is low and the sensitivity is high. However, where the medium having a tellurium dioxide layer on the surface ?lm is left under a relatively high temperature which is thereof; less than the blackening initiation temperature and FIG. 2 is a structural view of an optical recording where it is left under a high humidity, the change of medium having a tellurium dioxide on the joining sur transmittance is great. For this reason, TeOx which is 65 face between the surface and the substrate; poor in sensitivity but wherein x is more than 1 is gener FIG. 3 is a structural view of an optical recording ally used mainly in view of stability of the ?lm. Where medium whose ?lm composition changes in the direc for the substrate, plastics materials such as an acrylic tion of the thickness, and 4,786,538 3 4 FIG.