JPH0420793B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to an optical recording system.

Conventionally, in optical disks, etc., the recording layer on the substrate is irradiated with a focused laser beam, and the recording layer is melted, evaporated, or melted by the thermal energy converted from the optical energy absorbed in the recording layer.・Information is written by agglomerating to form geometric shape changes (pits). The pits formed in this way are irradiated with a low power laser beam,
Information is read by detecting the presence or absence of pits based on changes in the amount of reflected light, etc. Miniaturization of such recording devices,
In order to reduce costs, it is strongly desired to use a semiconductor laser as a writing laser. Therefore, there is a need for a highly sensitive recording medium and recording method that can write at a sufficiently high speed even when using a semiconductor laser with a low output, but a desirable medium and method have not yet been developed. Since media sensitivity largely depends on the thermal properties of the substrate supporting the medium, a substrate with as low thermal conductivity as possible is used. Even so, a large amount of heat flows into the substrate, and this is the main reason for lowering media sensitivity.

An object of the present invention is to provide an optical recording system that enables highly sensitive optical recording.

The present invention relates to an optical recording method in which recording is performed by irradiating a focused laser beam to form a geometric change (pit) in a recording layer. There are air bubbles between the first layer and a second layer located directly above the first layer and below the recording layer, and recording is performed by forming pits in the recording layer above the air bubbles. It is characterized by this.

The optical recording system of the present invention will be explained below using examples. FIG. 1 is a sectional view of an optical recording medium in one embodiment of the present invention. First, on a polymethyl methacrylate (PMMA) substrate 1, a 30 nm thick aluminum (Al) film as a reflective layer 2, a 200 nm thick polymer film as a transparent layer 3, and a 10 nm thick titanium (Ti) film as a support layer 4 were sequentially laminated. After that, the wavelength
By irradiating a 514 nm argon gas laser beam (not shown) convergently and locally heating the support layer 4, the support layer 4 is peeled off from the transparent layer 3.
Bubbles 5 with a maximum gap length of about 200 nm were formed.
Next, a 20 nm tellurium (Te) film was deposited as a recording layer 6 on the entire surface of the support layer 4. A semiconductor laser beam 7 having a wavelength of 830 nm was convergently irradiated onto the portion above the bubble 5 of the recording medium to form a pit 20 as shown in FIG. 2. The laser power required at this time was to deposit a 10 nm thick Ti film on a PMMA substrate.
This was less than half the laser power required to form pits in a recording medium in which a 20 nm thick Te film was sequentially laminated. The main reason for this high recording sensitivity is that the presence of air bubbles under the support layer below the recording layer that should form pits prevents the flow of heat from the recording layer and the support layer. It is. When reading was performed by irradiating a low-power semiconductor laser beam with a wavelength of 830 nm, the reflectance changed from 45% to 21% due to pit formation, and a sufficient degree of modulation was obtained. Also, the reflectance of the Te film on the bubbles is 45%, compared to the reflectance of the area without bubbles.
The reflectance of the Te film was as high as 60%, and the difference in reflectance between the areas above and outside of the bubbles was large enough to enable good tracking.

Although a Te film was used as the recording layer in this example, it goes without saying that other pit-forming materials such as other low melting point metals and organic dyes may also be used. Furthermore, although a Ti film/polymer film/Al film was used here as a layer structure for forming bubbles, it goes without saying that other bubble-forming layer structures may be used.

As described above, according to the present invention, an optical recording system that enables highly sensitive optical recording can be obtained.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing a recording medium in an embodiment of the present invention, and FIG. 2 is a cross-sectional view showing the state after recording on this recording medium. In the figure, 1 is a substrate, 2 is a reflective layer, 3 is a transparent layer, 4 is a support layer, 5 is a bubble, 6 is a recording layer, 7 is a laser beam, and 20 is a pit.

Claims (1)

[Claims] 1. In an optical recording method in which recording is performed by irradiating a focused laser beam to form a geometric shape change (pit) in a recording layer, a first layer among the layers stacked on a substrate; A bubble is present between a second layer located directly above the first layer and below the recording layer, and recording is performed by forming pits in the recording layer above the bubble. Optical recording method.