TWI245286B - Phase change optical disk - Google Patents

Abstract

A phase change optical disc includes a substrate, a first dielectric layer, a second dielectric layer, a third dielectric layer, a recording layer, a fourth dielectric layer and a reflecting layer. In this case, the first dielectric layer is formed on the substrate. The second dielectric layer is formed on the first dielectric layer. The refractive index of the second dielectric layer is greater than the refractive index of the first dielectric layer. The third dielectric layer is formed on the second dielectric layer. The refractive index of the third dielectric layer is small than the refractive index of the second dielectric layer. The fourth dielectric layer is formed on the recording layer. The reflecting layer is formed on the fourth dielectric layer.

Description

The correction is especially a multi-layer dielectric cross-erase) and improves the anti-9310340 ?. V. Description of the invention G)) [Technical field to which the invention belongs] The present invention relates to an optical disc, a θ structure, which can eliminate crossover and elimination phenomena (Phase change discs with different emissivity. ， °, [prior art] When developing re-writable discs, there are two main systems, one; optical discs (Magnet〇-〇ptical disk M〇); Another ^ ase— Change Optical Disks). As technology 2 progresses and the market changes, it is currently dominated by phase-change recording media, including re-writable optical discs (CD-RW), and rewritable digital digital optical discs (DVDs). -RW, DVD + RW) and dynamic random memory digital video disc (DVD-RAM), etc. FIG. 1 shows a conventional phase change optical disc, which includes a substrate 1 and a first dielectric layer 12, a recording layer 13, a second dielectric layer 14, and a first dielectric layer 12, which are sequentially formed on the substrate 11. And a reflective layer 15. Phase change optical discs use laser light to illuminate the disc. The laser beam enters the disc from the substrate 11 and passes through the dielectric layer 12 and then enters the recording layer 13. The energy of the laser beam makes the material of the recording layer 13 in the crystalline phase. (Crystanine) · and amorphous phase (amorphous) structure conversion. Thereafter, the laser beam is reflected by the reflective layer 15 so that the optical pickup head can recognize the signal by the high reflectance (^) of the crystalline phase and the low reflectance (Ra) of the amorphous phase to read the bits. When writing, the high-power short-pulse irradiation is used to locally melt the recording layer 13 and quickly cool it to form an amorphous phase structure.

Amendment 1245286 Case No. 93103402 V. Description of the invention (2) Crystal. In conventional phase change discs, the light absorption rate (Aa) of the amorphous phase is usually higher than the light absorption rate (Ac) of the crystalline phase. Recently, some people have used blue laser beams with a wavelength less than 4Onin instead of near-infrared or red laser beams, and reduced the pitch of the track pattern ^ to increase the recording density of the optical disc. However, when the track pitch is reduced, the laser beam will cause the temperature on the neighboring track to rise during the recording period, thereby eliminating the information marks recorded on the neighboring track, which is also called cross-erase. When the light absorption ratio is increased with Ac / Aa, the "cross-elimination phenomenon" will decrease. Therefore, if you want to increase the recording density, you need to "increase the light absorption ratio Ac / Aa to the maximum. And" In addition, as shown in Figure 2 For conventional phase change optical discs, when the light source with a shorter wavelength is illuminated, the reflectivity difference between the crystalline phase and the amorphous phase of the recording layer will decrease as the wavelength becomes smaller. If the crystalline phase and The difference in reflectivity between the amorphous phases is too small, and the optical read head cannot correctly determine the recorded information marks. However, the light absorption rate (Aa) of the amorphous phase should be much smaller than the light absorption rate (Ac) of the crystalline phase. It is also very difficult to maintain sufficient reflectance difference (& — Ra) between the crystalline phase and the amorphous phase when the short-wavelength light source is irradiated to correctly determine the information mark of the recording layer. In view of the above problems, the inventors of the present case have therefore eagerly considered a "phase-change optical disc" that can solve the above-mentioned cross-elimination phenomenon and improve the reflectance difference.

Page 7 mm, Revision V. Description of the invention (3) As stated above, the purpose of the present invention is to provide a structure of one, one, and one, which can eliminate the phenomenon of cross-removal and twist the _, Baixian layer '丨 electric layer disc . In order to achieve the above-mentioned object, the phase change light of the difference in reflectance between the k-direction and the k-direction is according to the board of the present invention, a -dielectric layer, a second dielectric sheet =: a base two layers, a fourth dielectric layer, And an inverse 'layer. 1 " Second series: the second dielectric layer is formed on the substrate; the second layer of the first dielectric layer has a refractive index (n2) greater than the first name (heart = shape;): the second dielectric layer Refractive index (n2) of the third dielectric 2 223, the recording layer system is formed in the dielectric layer system is formed in the recording layer h reflective layer system: the phase change optical disc of the dielectric invention [especially-a kind of having multiple layers ΐ: !! Structure 'Phase change discs to avoid cross-elimination phenomenon Compared with the known technology, the phase of the present invention is slightly less than the ancient phase μ y, ^ ^ ^ „The phase of the production umbrella A 3 Sheet, attached to the substrate! Flute: It has a first dielectric layer, a second dielectric layer, and a second one:] and the refractive index (n2) of the second dielectric layer is greater than the emissivity U1 of the first dielectric layer) Moreover, the refractive index (n2) of the second dielectric layer is greater than the refractive index (n3) of the third dielectric. The phase change optical disc of the present invention can not only increase the light absorption ratio of the two crystalline phases to the amorphous phase in the recording medium ( / Advise) to reduce the cross-elimination phenomenon, on the other hand, it is more able to maintain sufficient reflectance difference between the crystalline phase and the amorphous phase of the recording layer when the light source is short-wavelength (KeflectiVlty Difference ) To improve the accuracy of determining the recording layer information Lu Ji 5 ^.

Year and month revision SS_931〇34〇2 V. Description of the invention (4) (IV), [Embodiment] Change the disc ^ ,,,, and related drawings to illustrate the phase 2 1 and 2 according to the preferred embodiment of the present invention. 3 'The phase change optical disc 2 of the present invention includes a substrate 24, a f: a dielectric layer 22, a second dielectric layer 23, a third dielectric layer jw layer 25, and a fourth dielectric Layer 26 and a reflective layer 27. The CD-ROM series 2 includes a repeatable read-write disc (CD-RW), a DVD video disc (DVD-RW, DVD + RW), and a dynamic random CD-ROM (DVD-RAM). And other recording media. The most commonly used material is Polycarbonate (Polymethylmethacrylate, PMMA), which is special, cheap, and inexpensive to produce. The dielectric layer 22, the second dielectric layer 23, and the first The tri-dielectric chirp adjusts the reflectivity and absorption of the optical disc by the effect of light interference, and can prevent the evaporation of the recording layer 25 and the thermal damage of the substrate 21. The first dielectric layer 22 is formed on On the substrate 21, a second dielectric layer 23 is formed on the first dielectric layer 22, and a third dielectric layer 24 is formed on the second dielectric layer 23.

I1HIIEH In this embodiment, the first dielectric layer 22 is alumina A1Λ with a thickness of 30 nm, and its refractive index (^. Is ^. The second dielectric layer 23 is a sulfide-silicon dioxide having a thickness of ^ OOnη. (ZnS —Si〇2), its refractive index (n2) is • 05, the first; | The electrical layer 24 is alumina with a thickness of 15 nm, and its refractive index (n3) is 1.6. Therefore, the second dielectric The refractive index (n2) of the layer 23 is larger than the refractive index (ni) of the first dielectric layer 22, and the refractive index of the third dielectric layer 24 & is smaller than the refractive index (n2) of the first dielectric layer 23 In particular, it should be pointed out that the first dielectric layer 22 and the third dielectric layer 24 are not limited to the use of alumina, and Case No. 93103402 amended

1245286 V. Description of the invention (5) The second dielectric layer 23 is not limited to the use of zinc sulfide. Any dielectric material with n2 greater than n3 can be used. Two = two = more than nl, and the three dielectric layers 24 can also use sulphur dioxide or nitride sulphur as ϋΐ2 / or the second dielectric layer can also use zinc sulfide as the dielectric material. 'Recording layer 25 The system is formed on the third dielectric layer 24, and is made of a compound mainly composed of germanium-recording-tellurium (Ge-Sb-Te), such as rhenium, osmium, and gallium. Record exhibition? Where the direct beam is irradiated, the phase of the beam can be changed in accordance with the incidence rate of the reversible crystalline phase or the amorphous phase. The work of the beam can be changed. It is Ge2Sb2Te5 with a thickness of 9.5 nm. In the case of T, the fourth dielectric layer 26 is formed on the recording layer 25. In this embodiment, the four dielectric layer 26 is a zinc sulfide-silicon dioxide (ZnS- SiO2). The reflective layer 27 is made of a compound having excellent reflectivity and high thermal conductivity, and is selected from at least one of gold, shaw, titanium, copper, chromium, and alloys thereof. The reflective layer 27 It is used to reflect the incident light beam generated by the laser light source, and can quickly diffuse the heat generated in the recording layer 25. The reflective layer 27 is formed on the fourth dielectric layer 26. In this embodiment, the reflective layer 27 It is an alloy with a thickness of 60 nm. The phase change optical disc of the present invention may further include a plurality of interface layers, a first interface layer formed between the third dielectric layer 24 and the recording layer 25, and a recording layer. The second interface layer between 25 and the fourth dielectric layer 26. The effect of the interface layer is It can promote the crystallization of the recording layer 25, improve the wiping characteristics, and further prevent the inter-diffusion of atoms between the recording layer 25 and the dielectric layer, so as to improve the longevity of the phase-change optical disc. It is usually composed of nitrogen-containing compounds. In this embodiment, the first interface layer and the second interface layer are both formed of nitrogen germanium (GeN) with a thickness of 5 nm.

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1245286 Case No. 93103402 Article 5 of the invention 5. Explanation of the invention (6) In addition, the phase change optical disc of this embodiment is suitable for an optical disc drive having a short-wavelength light source or a long-wavelength light source. The diode 'long-wavelength light source is, for example, a red laser diode. In this embodiment, the light absorption of the crystalline phase in the recording layer is less than 72❶ / 〇, while the light absorption of the amorphous phase is Aa is 63%, and the Ac / Aa is greater than 1, so it can reduce the luminescence of the cross elimination phenomenon. . In addition, under the irradiation of a blue laser diode (wavelength is 45 nm), the phase change disc of the present invention has a difference in reflectance between a crystalline phase recording layer and an amorphous phase recording layer (Ref lect ivi ty

Dif ference, Rc-Ra) 14%. This is a difference between the crystalline phase and the amorphous phase of the s-recorded layer of a phase change optical disc in conventional technology. As the wavelength becomes smaller and decreases, there are obvious differences. To sum up, the phase change optical disc of the present invention, particularly a phase change optical disc having a multi-layered dielectric layer structure, avoids the phenomenon of cross elimination, and improves the phase change optical disc in which the reflectance difference occurs. Compared with the conventional technology, the phase change optical disc of the present invention is located between the substrate and the recording layer, and has a first dielectric layer, a second dielectric layer, and a third dielectric layer in this order, and the second dielectric The refractive index (n2) of the layer is larger than the refractive index (ni) of the first dielectric layer, and the refractive index (n2) of the second dielectric layer is larger than the refractive index (n3) of the third dielectric layer. The phase change optical disc of the present invention can not only increase the light absorption ratio (Ac / Aa) of the crystalline phase to the amorphous phase in the recording layer to reduce the elimination phenomenon of the parent fork, but also to improve the recording when using a short-wavelength light source. The reflectance difference between the crystalline phase and the amorphous phase of the layer is used to improve the accuracy of the optical reading head in determining the information mark of the recording layer. The above description is exemplary only, and not restrictive. Any equivalent modification or change made without departing from the spirit and scope of the present invention is

1245 ^ 861 Case No. 93103402 Amendment V. Description of the invention (7) Should be included in the scope of the attached patent application Φ iHl Page 12 1245286 Case No. 93103402_ Year Month Amendment _ Simple Explanation of the Schematic (5), [ Brief description of the drawings] Figure 1 is a conventional phase-change optical disc; Figure 2 is a recording layer of a conventional phase-change disc with crystalline phase and amorphous phase at different wavelengths; and Figure 3 is a phase of the present invention Change disc. Description of component symbols: 1 phase change optical disc 11 substrate 12 first dielectric layer _ 13 recording layer 14 second dielectric layer 15 reflective layer 2 phase change optical disc 21 substrate 22 first dielectric layer 23 second dielectric layer 24 Third dielectric layer 2 5 Recording layer 26 Fourth dielectric layer 2 7 Reflective layer

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Claims (1)

1245286 Case No. 93103402 Amendment 6 、 Scope of patent application 1. A phase change optical disc, comprising: a substrate; a first dielectric layer formed on the substrate; a second dielectric layer, which is Formed on the first dielectric layer, the refractive index (n2) of the second dielectric layer is greater than the refractive index (nl) of the first dielectric layer; a third dielectric layer is formed on the first dielectric layer On the two dielectric layers, the refractive index (n3) of the third dielectric layer is smaller than the refractive index (n2) of the second dielectric layer; a recording layer is formed on the third dielectric layer; A fourth dielectric layer is formed on the recording layer; and a reflective layer is formed on the recording layer. 2. The phase change optical disc described in item 1 of the scope of patent application is suitable for an optical disc drive with a short-wavelength light source. 3. The phase change optical disc described in item 2 of the scope of application and patent, the short-wavelength light source is a monitor light laser diode. 4. The phase change optical disc described in item 1 of the scope of patent application is applicable to an optical disc drive with a long-wavelength light source. 5. The phase change optical disc described in item 4 of the scope of patent application, the long-wavelength light source is a red laser diode. 6. The phase change optical disc described in item 1 of the scope of patent application, wherein the first Page 14 1245286 Case No. 93103402 Amendment 6. Scope of patent application A dielectric layer is dioxide. 7. The phase change optical disc described in item 1 of the scope of patent application, wherein the first dielectric layer is alumina. 8. The phase change optical disc described in item 1 of the scope of patent application, wherein the second dielectric layer is zinc sulfide-silicon dioxide. 9. The phase change optical disc described in item 6 of the scope of patent application, wherein the third dielectric layer is silicon dioxide. 10. The phase change optical disc described in item 7 of the scope of patent application, wherein the third dielectric layer is alumina. 11. The phase change optical disc described in item 1 of the patent application scope, wherein the reflective layer is selected from at least one of gold, titanium, titanium, copper, chromium, and alloys thereof. Page 15 Page 4