Compositions: ceramic – Ceramic compositions – Refractory
Patent
1996-07-11
1998-06-16
Marcheschi, Michael
Compositions: ceramic
Ceramic compositions
Refractory
501 985, 264 65, C04B 35581
Patent
active
057670277
DESCRIPTION:
BRIEF SUMMARY
CROSS-REFERENCE TO RELATED APPLICATION
This application is a 371 of Intentional Application No. PCT/JP95/00141, filed Feb. 3, 1995.
TECHNICAL FIELD
The present invention relates to an aluminum nitride sintered body and its production method.
BACKGROUND OF INVENTION
Heretofore, in semiconductor apparatuses, such as, etching apparatuses, chemical vapor deposition apparatuses and the like, so-called stainless heaters and indirect heating system heaters have been generally used. However, when such heating systems are used, they are occasionally corroded by an action of a halogen series corrosive gas to form particles and they have bad heating efficiency.
In order to solve these problems, the inventors formerly proposed a ceramic heater comprising a dense ceramic substrate, and a high melting point metal wire embedded in the interior of the substrate. The wire was wound spirally in the interior of a disc shaped substrate and connected to electric terminals at both ends. Such a ceramic heater has been found to have superior properties, particularly in producing semiconductors.
As the ceramics for constituting the substrate of the ceramic heater, silicon nitride, aluminum nitride, SIALON and the like nitride series ceramics are considered preferable. In some cases, a susceptor is provided on the ceramic heater and a semiconductor wafer is mounted on the susceptor when heating the semiconductor wafer.
According to the inventors' study, aluminum nitride is preferably used as the substrate for such ceramic heaters and susceptors. This is because halogen series corrosive gases, such as, CF.sub.3 are often used as etching gases or cleaning gases particularly in semiconductor production apparatuses and aluminum nitride is found to have an extremely high corrosion resistant property against these halogen series corrosive gases.
Meanwhile, the substrates used for such heaters and susceptors are requested to be black in color, because black substrates have a larger radiation heat and a superior heating property than white substrates.
However, aluminum nitride sintered bodies per se generally assume white or gray-white color, so that their heat radiation property is inferior. Therefore, in order to make aluminum nitride sintered bodies black, a suitable metal element is added to the raw material powder and the added raw material powder is fired to produce black aluminum nitride sintered bodies (refer to Japanese Patent Publication No.5-64,897). As such additives, tungsten, titanium oxide, nickel, palladium and the like are known.
However, when such a metal element is contained as a blackening agent in the aluminum nitride sintered body, the amount of impurities contained in the aluminum nitride sintered body is increased due to the influence of the additive. Particularly, if a Group I a element, a Group II a element or a transition metal element is present in the process of producing semiconductors, such an element can cause a serious adverse influence on the semiconductor wafers and the production plant, even if the amount of the element existing in the aluminum nitride sintered body is small. For example, it can be a cause of defects of the product semiconductors.
DESCRIPTION OF INVENTION
The present invention relates to an aluminum nitride sintered body, comprising metal elements of contents of not more than 100 ppm for each metal element except for aluminum and assuming black color of a lightness of not more than N 4 according to the definition of JIS Z 8721 (wherein JIS=Japanese Industrial Standard).
Also, the present invention relates to a method of producing an aluminum nitride sintered body, comprising sintering a powder of aluminum nitride obtained by reduction nitriding, at a temperature of at least 1,800.degree. C. under a pressure of at least 120 kg/cm.sup.2.
Also, the present invention relates to a method of producing an aluminum nitride sintered body, comprising sintering a powder of aluminum nitride containing metal elements contained in an amount of not more than 100 ppm for each metal element exc
REFERENCES:
patent: 4618592 (1986-10-01), Kuramoto et al.
patent: 4803183 (1989-02-01), Schwetz et al.
patent: 5036026 (1991-07-01), Yamakawa et al.
patent: 5049367 (1991-09-01), Nakano et al.
patent: 5293509 (1994-03-01), Yamakawa et al.
Kobayashi Hiromichi
Sakon Atsushi
Umemoto Koichi
Ushikoshi Ryusuke
Marcheschi Michael
NGK Insulators Ltd.
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