Coating processes – Direct application of electrical – magnetic – wave – or... – Ion plating or implantation
Reexamination Certificate
1998-01-13
2001-06-12
Meeks, Timothy (Department: 1762)
Coating processes
Direct application of electrical, magnetic, wave, or...
Ion plating or implantation
C427S562000, C427S564000, C427S126300
Reexamination Certificate
active
06245394
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a film growth method and a film growth apparatus using plasma. More particularly, the present invention relates to a film growth method and a film growth apparatus for forming magnesium oxide (MgO) films on substrates.
In plasma display panels (PDP in the following), MgO is normally used for the protective films for discharge cells. In general, wet methods like coating and dry methods like vacuum vapor deposition are used for the formation of MgO films. Films formed by the dry methods have film qualities that are superior to films formed by the wet methods. Thus, the use of the dry methods in the formation of the MgO films is more common.
In terms of the dry methods, there is vacuum vapor deposition using an electron gun and sputtering. Since vacuum vapor deposition forms films at higher speeds than the sputtering, it is more commonly used. A film growth speed or rate with vacuum vapor deposition that uses the electron gun depends on output power of the electron gun, but it is generally 20-40 (Å/s). If the output power of the electron gun is too great, problems, such as splashing in the tablets, or vaporization material, arise.
On the other hand, when MgO is used for the tablets in radio frequency (RF) ion plating, an operating pressure of 10
−3
to 10
−4
Torr is necessary for generating the plasma. However, since this operating pressure hinders the vaporization of MgO, the film growth speed is reduced. The greater the vacuum is below 10
−4
Torr, the easier it is for MgO to vaporize. On the other hand, there is also the method of reactive film growth using Mg for the tablets. However, there are problems such as film quality being unstable and the oxidizing atmosphere shortening the life of the electron gun with this method.
Incidentally, MgO film growth processes take up a large amount of the time in the PDP fabrication process. However, the film growth speeds are insufficient with the above methods, and they are preventing improvements in PDP productivity.
SUMMARY OF THE INVENTION
Therefore, an object of the present invention is to provide a film growth method for fast formation of magnesium oxide films of high quality.
Another object of the present invention is to provide a film growth apparatus for magnesium oxide films that is suitable for implementing the above-mentioned film growth method.
A magnesium oxide film growth method according to the present invention comprises the steps of: guiding a plasma beam generated by a plasma beam generator that uses arc discharge into a hearth placed in a vacuum chamber as an anode; ionizing a vaporization material on the hearth; and depositing the ionized vaporization material on a surface of a substrate placed opposite to the hearth for film formation.
According to an aspect of the present invention, a ring-shaped permanent magnet is provided as an auxiliary anode, the ring-shaped permanent magnet being coaxial with a central axis of the hearth and being positioned so as to surround an upper area of the hearth. Mg is used as the vaporization material. Gas mixed with oxygen is supplied into the vacuum chamber. Mg particles sublimated from the hearth react with oxygen plasma generated by the plasma to form an Mgo film on the substrate.
A magnesium oxide film growth apparatus according to the present invention comprises: a vacuum chamber; a plasma beam generator placed in the vacuum chamber, the plasma beam generator using arc discharge; and a hearth placed in the vacuum chamber to serve as an anode. A plasma beam generated by the plasma beam generator is guided into the hearth in the vacuum chamber to ionize a vaporization material on the hearth. The ionized vaporization material is deposited on a surface of a substrate placed opposite to the hearth for film formation.
According to an aspect of the present invention, an auxiliary anode is coaxial with a central axis of the hearth and is positioned around the hearth so as to surround an upper area of the hearth, the auxiliary anode comprising a ring-shaped permanent magnet. Mg is used as the vaporization material. The vacuum chamber has a supply unit to supply gas mixed with oxygen therein. As a result, Mg particles sublimated from the hearth react with oxygen plasma generated by the plasma to form an MgO film on the substrate.
REFERENCES:
patent: 4951604 (1990-08-01), Temple et al.
patent: 5009922 (1991-04-01), Harano et al.
patent: 5055169 (1991-10-01), Hock et al.
patent: 5378506 (1995-01-01), Imai et al.
patent: 5849370 (1998-12-01), Lee et al.
patent: 7-316794 (1995-12-01), None
Sakemi Toshiyuki
Tanaka Masaru
Burns Doane , Swecker, Mathis LLP
Meeks Timothy
Sumitomo Heavy Industries, Inc.
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