Multi-Layer Optical Disc Common Sputtering Targets
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Solution Overview
Problem
The existing methods for manufacturing multi-layer single-sided optical discs face challenges due to the need to replace targets during the sputtering process, leading to reduced operation rates and quality issues caused by residual moisture, which affects the recording and reproducing characteristics of the medium, especially at high-fold speeds.
Innovation Solution
The solution involves creating an optical disc with two or more information layers having common compositions for recording layers and adjacent dielectric layers, allowing for the same composition targets to be used throughout the sputtering process without the need for frequent target replacements, thereby reducing production interruptions and improving film quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If different composition targets are used for different information layers, then the recording and reproducing characteristics are optimized, but the operation rate decreases due to frequent target replacement
Solution Approach 1:
The patent applies universality by designing the first and second information layers with identical compositions (both using Ge-Sb-Te-based recording layers and ZnS-SiO2-based dielectric layers), allowing a single multi-component target to form all layers. This eliminates the need for target replacement between layers, maintaining high operation rates while ensuring consistent recording and reproducing characteristics across both layers.
2Manufacturing precision
If target replacement is performed frequently, then the film quality is maintained, but residual moisture affects the recording and reproducing characteristics
Solution Approach 1:
The patent implements continuity of useful action by forming both information layers without interrupting the sputtering process or replacing targets. The continuous deposition in vacuum prevents moisture contamination that would occur during target replacement, while the identical layer compositions ensure consistent film quality and recording characteristics throughout the process.
3Productivity
If the same composition targets are used for both information layers, then the operation rate increases and production time is reduced, but the adaptability to different recording modes decreases
Solution Approach 1:
The patent applies parameter changes by maintaining identical material compositions for both information layers while varying the thickness parameters and laser beam irradiation conditions during recording. This allows the same Ge-Sb-Te-based recording layer to function in different recording modes (e.g., different modulation formats or power levels) without requiring different target materials, thus preserving both high operation rate and recording mode adaptability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances the recording and reproducing characteristics and life characteristics of the optical disc while reducing production costs and time losses associated with target replacement and pre-sputtering, enabling efficient manufacturing of high-density, high-speed discs.
Implementation Method 1
phase-change recording modes are employed. This recording mode takes an advantage of the property of a recording layer's irreversible change in its state between an amorphous phase and a crystal phase (or between a crystal phase and another crystal phase having a different structure) when being irradiated with a laser beam
Implementation Method 2
In formation of a recording layer, a reflective layer, a dielectric layer and other thin layers (e.g. a transmittance-adjusting layer, etc.) of a information recording medium by the sputtering process
Data Source
AI summary
In each of at least two information layers (1, 2) which constitute a information recording medium having a plurality of information layers on its one side, the compositions of the recording layer (7) and the dielectric layers (6, 8) adjacent to the recording layer (7) in one information layer (1) are common to the compositions of the corresponding layers (12, 11, 13) in the other information layer, so that the recording layers (7, 12) and the dielectric layers (6, 11) and (8, 13) in the two information layers (1, 2) can be formed in common sputtering film-forming chambers without the replacement of targets, which makes it possible to produce a multi-layer single-sided recording medium with a decreased time loss in the production process.