Coating apparatus – Gas or vapor deposition
Reexamination Certificate
2001-02-02
2003-02-18
Mills, Gregory (Department: 1763)
Coating apparatus
Gas or vapor deposition
C118S728000, C118S725000, C156S345520, C156S345510
Reexamination Certificate
active
06521046
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention concerns a chamber material made of alloy which is used suitably to various application uses requiring thermal cracking resistance and chemical and/or physical corrosion resistance in a plasma and/or an elevated temperature corrosive circumstance, for example, vacuum chambers, used in plasma processing apparatus such as production facilities for semiconductors and liquid crystals display panel, as well as components disposed in the inside of the chamber.
2. Statement of the Relevant Art
For vacuum chambers made of Al alloy used for plasma processing apparatus in production facilities for semiconductors and liquid crystals display panel, as well as various kinds of components such as electrodes disposed in the chamber, those materials comprising mainly Al—Mg series alloy (JIS A 5000 series) and Al—Mg—Si series alloy (JIS A 6000 series) as substrate with or without applying anodization have been used so far.
Anodization of forming anodized film on the surf ace of Al alloy substrates thereby providing the substrates with corrosion resistance and wear resistance has been generally adopted so far. In the inside of vacuum chambers, since predetermined processings are applied by various kinds of corrosive gases and plasmas or active species obtained by conversion into plasmas under circumstances from room temperature to elevated temperature of 200° C. or higher to materials to be processed such as silicon wafers during pre-treatment steps and production steps for semiconductors, the inner surfaces of the vacuum chambers and various components such as plasma electrodes disposed the inside of the vacuum chamber are exposed to the atmospheres described above, so that anodization is applied on the Al alloy substrates, particularly, for those components exposed in the plasmas to form anodized film on the surfaces thereof in order to maintain the corrosion resistance and the wear resistance.
The vacuum chambers made of Al alloys and various kinds of components such as electrodes disposed therein are required for corrosion resistance and wearing resistance, and there are further such components requiring brazing property such as for heater blocks. Al—Mg series alloys (JIS A 5000 series) have been used generally for the surface of the heater blocks and the block main body with a view point of forgeability and corrosion resistance.
Along with technical development in recent years, higher corrosion resistance of aluminum alloy materials used for vacuum chambers and various kinds of components such as electrodes disposed therein and reduction of contamination for products to be treated have further been demanded in order to cope with narrow rule of device design and increasing density of plasmas or more severe atmosphere to achieve the performance requested. For satisfying such demands, there have been proposed high purity aluminum (Al: 99.9 wt % or higher) or an aluminum alloy with addition of Si and Mg in high purity aluminum in which the sum of other impurities is restricted to 0.1% or less as described in Japanese Patent Laid-Open Publication Hei 10-88271 as materials for the substrates to be applied with anodization.
However, in the materials comprising substrates made of aluminum alloys and applied with anodization, contamination caused by the anodized film per se can be reduced to some extent, but a difference of expansion due to the difference of the thermal expansion coefficient between the substrate aluminum alloy and the anodized film can not be relieved to result in crackings in the anodized film and develop corrosion along crackings thus formed in corrosive gas and plasma circumstances at high temperature of 200° C. or higher. This not only shortens each part or the material's life but also results in formation of particles to cause contamination for the products to be processed in plasma processing. When heater blocks and the like are formed by using existent Al alloys, the following problems are further present. That is, since the Al—Mg series alloys are not applicable for wide range of condition for the brazing property, special low temperature brazing materials have to be used upon bonding between the surface plate and the block main body, which disadvantageously increases the cost. Further, since the Al—Mg alloys have low heat conductivity, the surface temperature distribution on the heater blocks tends to become not uniform.
OBJECT OF THE INVENTION
This invention has been accomplished in view of the foregoing problems and intends to provide a chamber material made of aluminum alloy excellent in thermal cracking resistance and chemical and/or physical corrosion resistance in a high temperature corrosive circumstance and capable of reducing contamination excellently with having anodized film, as well as also excellent in brazing property.
Materials for the chambers in this invention include not only the structural materials for vacuum chambers used in semiconductor production apparatus but also include those materials for clampers, shower heads, susceptors, upper electrodes, lower electrodes, gas diffusion plates, heater blocks, pedestals, substrates for chucks, shower plates, diffusers, face plates, liner earth or earth electrodes. That is, they include, among those components disposed in the vacuum chambers or reactors, all of components that can be made of aluminum or aluminum alloys. In the subsequent descriptions, all of such materials are collectively referred to as chamber materials.
SUMMARY OF THE INVENTION
A chamber material made of Al alloy according to this invention is applied with an anodized film in which a substrate has a composition comprising, on the mass % basis, 0.1 to 2.0% Si, 0.1 to 3.5% Mg, 0.02 to 4.0% Cu and the balance of Al as the essential ingredient, as well as other impurity elements in which Cr is less than 0.04% in the impurity elements described above (hereinafter % means mass % unless otherwise specified).
According to this invention, precipitates (Mg
2
Si) are precipitated by aging by the incorporation of Si and Mg in predetermined amount, Cu is concentrated at the periphery of Mg
2
Si and, when anodization is applied in this state, it is considered that sufficient spaces so called secondary pores to relieve the difference of the thermal expansion coefficient are formed at cell triplet points in the anodized film. This can suppress and prevent occurrence of crackings in the anodized film in a elevated temperature circumstance, so that the anodized film can develop inherent corrosion resistance, and thermal cracking resistance and corrosion resistance are excellent. Further, since corrosion caused by the crackings due to heat expansion difference is prevented, contamination due to corrosion products can be suppressed and prevented. Then, by restricting Cr in the impurity elements to less than 0.04%, the amount of impurity elements in the anodized film can be decreased by which contamination caused by the films per se can be suppressed to attain excellent reduction of the contamination. Further, in this invention, it is preferred to restrict Fe to 0.1% or less and Mn to 0.04% or less and, further, to restrict the sum for the impurity elements other than Fe, Cr, Mn to 0.1% or less among the impurity elements. This can realize excellent reduction of contamination. At the same time, this can be achieved to obtain physical stability in anodized film since there was less interruption for forming the anodized film in this materials state.
The chamber material according to this invention is used for plasma processing apparatus for applying predetermined processings to products to be processed by plasmas or active species obtained by conversion into plasmas in a chamber and the chamber material preferably has an anodized film at a portion exposed in the plasmas.
When the chamber material according to this invention is used for the plasma processing apparatus, since the material has excellent thermal cracking resistance and corrosion resistance in an atmosphere of high temperature
Hisamoto Jun
Matsuura Hiroshi
Sawada Hiroki
Tanaka Toshiyuki
Wada Koji
Hassanzadeh P.
Kabushiki Kaisha Kobe Seiko Sho
Mills Gregory
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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