Powder metallurgy processes – Powder metallurgy processes with heating or sintering – Making composite or hollow article
Reexamination Certificate
2002-03-12
2003-10-21
Mai, Ngoclan (Department: 1742)
Powder metallurgy processes
Powder metallurgy processes with heating or sintering
Making composite or hollow article
C419S008000
Reexamination Certificate
active
06635219
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of regenerating a sputtering target and, more particularly, to a method of regenerating a phase-change sputtering target for optical storage media.
2. Description of the Related Art
Phase-change erasable optical recording media, such as CD-RW, DVD-RW or DVD-RAM, can repeatedly read and rewrite to achieve a large number of records. The phase-change erasable optical recording media uses a phase-change material as a recording layer, and uses a focused laser beam serving as a heat source to irradiate a micron-scale region on the recording layer, resulting in a reversible transformation generated between the crystalline phase and the amorphous phase of the phase-change material on the irradiated region. Thus, the different optical properties of the crystalline phase and the amorphous phase of the phase-change material can determine the states of the irradiated regions. Under conditions in which each irradiated region has the same crystalline structure, the information of a unit cell is stored in a small spot of the amorphous phase. The performance of the recording layer depends on the quality of a phase-change sputtering target for optical storage media and the sputtering technique.
Generally, a phase-change sputtering target comprises a target material, an adhesion material and a backing plate of copper alloy. According to various phase-change types, the phase-change target material is classified as: (1) amorphous phase→crystalline phase (irreversible), such as Te—TeO
2
, Te—TeO
2
—Pd, Sb
2
Se
3
/Bi
2
Te
3
, Ge—Te—Sb and Ag—In—Sb—Te; (2) amorphous phase→crystalline phase (reversible), such as Ge—Te—Sb, Ag—In—Sb—Te, Te—TeO
2
—Ge—Sn, Te—Ge—Sn—Au, Sn—Se—Te, Sb—Se—Te, Sb—Se, Ga—Se—Te, Ga—Se—Te—Ge, In—Se, In—Se—Tl—Co, Ge—Te—Sb—S, In—Sb—Te, In—Se—Te and Ge—Te—Sn; (3) crystalline phase→crystalline phase, such as Ab—Zn, Cu—Al—Ni, In—Sb and In—Sb—Se. Preferably, the series of Ge—Sb—Te and Ag—In—Sb—Te are in common use.
However, in planar magnetron sputtering, the sputtering ions' orbit along a specific trajectory caused by the magnetic field leads to the appearance of non-uniform erosion on the target material. Therefore the sputtering target needs to be renewed when the sputtering target is employed reaching a predetermined time or a fixed quantity in order to prevent damage to the backing plate from the penetration by the sputtering ions. As a rule, the percentage of real use for a rectangular-shaped sputtering target is less than 28%, for a circular-shaped sputtering target, less than 35%, and commercial-use sputtering targets are controlled about 25%. In addition, compared with ordinary metallic target material, the phase-change target material is rather costly and more than 70~75% of the phase-change target material cannot be recycled. Thus, a method of regenerating the phase-change sputtering target to increase the useable percentage of the target material, avoid its waste thereby reducing process costs, is called for.
SUMMARY OF THE INVENTION
The present invention provides a method of recycling a used powder-metallurgy sputtering target and thermal-pressure sintering thereof to regenerate a new powder-metallurgy sputtering target.
The present invention provides a method of regenerating a phase-change sputtering target for optical storage media. First, a used powder-metallurgy sputtering target composed of a target material, an adhesion material, and a backing plate is recycled. Then, the target material is separated from the backing plate. Next, the adhesion material is scraped from the recycled target material. Thereafter, the surface of the recycled target material is processed. Finally, the backing plate, a new adhesion material, the recycled target material, and new powders are placed in a vacuum thermal-pressure furnace in sequence to perform a thermal-pressure sintering process. This completes a new phase-change sputtering target.
Accordingly, it is a principal object of the invention to provide a method of regenerating a powder-metallurgy sputtering target to increase the utility rate of the backing plate.
It is another object of the invention to provide a method of regenerating a powder-metallurgy sputtering target to decrease material cost.
Yet another object of the invention is to provide a method of regenerating a powder-metallurgy sputtering target to increase the useable percentage of the target material.
It is a further object of the invention to provide a method of regenerating a powder-metallurgy sputtering target to avoid waste of the target material.
These and other objects of the present invention will become readily apparent upon further review of the following specification and drawings.
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Lai Ming-Shyong
Li Bean-Jon
Wen Jyh-Chung
Birch & Stewart Kolasch & Birch, LLP
Industrial Technology Research Institute
Mai Ngoclan
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