Ge-Bi-Te Recording Layer Oxide Interface for Moisture Resistance
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Solution Overview
Problem
High-speed Blu-ray discs face issues with separation between the recording layer and the dielectric layer, leading to reliability and moisture resistance problems during high temperature humidity tests.
Innovation Solution
A Ge—Bi—Te—M recording layer with an oxide layer containing an oxide of the same element as the recording layer, formed using a sputtering method, is used to prevent separation and enhance moisture resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional dielectric layer is used in contact with the recording layer, then the disc can be manufactured with standard materials, but separation occurs between the recording layer and dielectric layer during high temperature humidity tests
Solution Approach 1:
An oxide layer containing oxide of element M is introduced as an intermediary layer between the recording layer and the dielectric layer. This intermediate oxide layer acts as a buffer that prevents direct contact and separation between the recording layer and dielectric layer during high temperature humidity tests, thereby improving moisture resistance and layer stability.
Solution Approach 2:
The patent uses a composite structure consisting of the recording layer containing element M, an oxide layer containing oxide of element M, and a dielectric layer. This composite material structure leverages the chemical compatibility between the oxide of element M and both adjacent layers to prevent separation and enhance overall reliability during environmental stress tests.
2Productivity
If high-speed recording is implemented, then data transfer rate increases, but separation between layers occurs leading to reliability problems
Solution Approach 1:
The oxide layer containing oxide of element M serves as a mediator that maintains layer adhesion during high-speed recording operations. The intermediate layer absorbs thermal and mechanical stress generated during high-speed recording, preventing separation between the recording layer and dielectric layer while enabling sustained high recording speeds.
Solution Approach 2:
The patent modifies the compositional parameters of the layer structure by introducing an oxide layer with specific chemical composition (oxide of element M). This parameter change in material composition enhances the interfacial bonding and stress distribution, allowing the structure to withstand the thermal and mechanical loads generated during high-speed recording without layer separation.
3Speed
If the recording layer composition is optimized for high speed recording, then recording performance improves, but moisture resistance deteriorates due to layer separation
Solution Approach 1:
The oxide layer containing oxide of element M acts as a protective intermediary that blocks moisture infiltration pathways. By positioning this oxide layer between the recording layer and dielectric layer, the patent prevents moisture from penetrating into the interface region, thereby maintaining both high-speed recording performance and moisture resistance simultaneously.
Solution Approach 2:
The composite material structure of recording layer + oxide layer + dielectric layer creates a multi-functional barrier system. The oxide layer in this composite structure provides both mechanical bonding enhancement and moisture barrier properties, allowing the system to achieve high recording speed while resisting moisture infiltration that would otherwise cause layer separation and performance degradation.
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
The solution effectively suppresses separation between the recording and oxide layers, resulting in a highly reliable information recording medium with improved moisture resistance, as demonstrated by reduced corrosion points in film corrosion tests.
Implementation Method 1
a recording layer reversibly changes its state between amorphous and crystalline (or between crystalline and another crystalline with a different structure) by being irradiated with a laser beam
Implementation Method 2
formed using a sputtering method
Data Source
AI summary
An information recording medium of the present invention includes recording layers 19 and 26 whose phase can change by an optical or an electrical system so as to be detectable, and interface layers 18, 20, 25 and 27, which are in contact with the recording layers 19 and 26, to serve as oxide layers. The recording layer 19 contains a Ge—Bi—Te-M material represented by a formula: GeαBiβTeγM100-α-β-γ (atom %), where M denotes at least one element selected from Al, Ga, In and Mn, and α, β and γ satisfy 25≦α≦60, 0<β≦18, 35≦γ≦55, and 82≦α+β+γ<100. The interface layers 18, 20, 25 and 27 contain at least one oxide of the element M contained in the recording layers 19 and 26.