Coating apparatus – Gas or vapor deposition – With treating means
Reexamination Certificate
2000-11-07
2003-04-29
Mills, Gregory (Department: 1763)
Coating apparatus
Gas or vapor deposition
With treating means
C118S728000, C118S715000, C118S500000, C156S345520, C361S234000
Reexamination Certificate
active
06554906
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to wafer holders for semiconductor manufacturing apparatus and semiconductor manufacturing apparatus using the same and particularly to wafer holders for semiconductor manufacturing apparatus having a heater for heating a wafer, an electrode for an electrostatic chuck electrostatically holding a wafer or the functions of both of such heater and electrode, and semiconductor manufacturing apparatus using the same.
2. Description of the Background Art
In etching a surface of a semiconductor wafer or depositing a film thereon, a multitude of such wafers are held on a rack and batch-processed, exposed to an etchant gas or a gas for deposition, and circumferentially heated with a heater, as required. This technique is referred to as hot-wall technique.
In recent years, however, as semiconductor is required to be more highly integrated and operate more rapidly, semiconductor manufacturing apparatus have therein uneven temperature and gas flow varying with different portions thereof and such unevenness in temperature and gas flow disadvantageously varies the quality of a film etched or deposited. Accordingly, the batch process as described above is being replaced by arranging multiple etching apparatus and deposition apparatus and using a loader therebetween to automatically feed wafers to process a single wafer at one time. In doing so, the loader transfers a wafer to an etching apparatus or a deposition apparatus and places the wafer in a chamber therein on a holder holding the wafer by means of an electrostatic chuck or alternatively on a holder's wafer bearing side having a surface increased in precision so that the wafer can be placed still on and in close contact with the holder and the holder thus heats the wafer directly to heat the wafer uniformly. As such the holder needs to at least have a portion in contact with a wafer that is formed of a material resistant to a highly corrosive gas such as halogen gas and highly heat-conducting, and the holder per se also needs to function to electrostatically chuck, mechanically fix and heat a wafer.
A material having been noted as a material used for forming the holder is aluminum nitride, which is resistant to corrosion and highly heat-conducting. Powdery aluminum nitride is molded to provide media formed thereof and therebetween a coil or wire of a refractory metal such as Mo is interposed and they are then hot-pressed and thus sintered to embed a conductive layer used for a heater, an electrostatic chuck or the like. For example, Japanese Patent Publication No. 2604944 discloses a configuration with an embedded heater allowing a heat emitting side to provide more uniform heat. To provide a conductive layer, a molded medium formed of aluminum nitride and having a surface printed with a paste containing W, Mo or the like is placed on another medium and the aluminum nitride is sintered to provide a holder having a conductive layer embedded therein.
With a holder having such a structure as above, a heater or an electrostatic chuck is powered, as described with reference to FIG.
19
. More specifically, as in a holder
110
, a ceramic base member
104
has a back side provided with a pipe bonded thereto and accommodating therein extraction lines
107
A and
107
B externally feeding power to each of conductive layers
101
and
102
serving as the heater or the electrostatic chuck.
The structure as shown in
FIG. 19
, however, is inevitably of three dimensions as holder
110
has a back side with pipe
106
bonded thereto. As such, the holder in the form of a disc and pipe
106
for accommodating the extraction lines must be manufactured separately and to bond holder
110
and pipe
106
together a bonding glass must be initially applied and diffusion-bonding or the like must be then employed, which is a cumbersome process.
Furthermore, holder
110
having a back side with a pipe bonded thereto would have front and back surfaces having different levels of heat dissipation. Thus the front side and the back side would have therebetween a difference in temperature and holder
110
would thus distort when it is heated or cooled. While a wafer is placed on holder
110
in close contact therewith so that the wafer is heated with an increased heat-transfer efficiency, holder
110
distorted would provide a gap between the holder and the wafer. This would result in uneven heat transfer which would then cause a variation in the temperature of the wafer's surface and hence an uneven etch rate and an uneven deposition rate in the wafer's plane. Accordingly, to prevent the holder from warpage the holder should be formed of a plate at least 5 mm thick, which would increase the cost for its source material(s).
Furthermore, bonding pipe
106
would increase the thermal capacity and if holder
110
is adapted to also function as a heater then it would require a long period of time to heat and cool the holder. Furthermore, in fabricating the pipe when the pipe molded has a binder heated and thus removed therefrom the binder is hard to remove and the pipe can thus break and the pipe tends to be unevenly sintered or deform when it is sintered so that the binder should be removed over a long period of time and furthermore the sintering charge level reduces, which significantly increases the production cost.
Furthermore this structure entails joining at an end of pipe
106
. As such, the area for the joint should be considered to maintain the anti-leakage level as required and pipe
106
is thus required to have an increased diameter. Furthermore, if pipe
106
is also required to support holder
110
, pipe
106
is also forced to have an increased diameter, resulting in the same disadvantage as described above.
It is possible to widen only the pipe
106
end in the form of a flange. This approach, however, requires applying extraction-molding to extract pipe
106
of a larger diameter and then remove the portion other than the flange.
Furthermore, the structure with pipe
106
joined would be damaged when it is transported, and it also has an in-furnace charge level inevitably reduced when the pipe is joined. Thus the production cost would be increased.
SUMMARY OF THE INVENTION
The present invention contemplates a wafer holder for use with a semiconductor manufacturing apparatus that can reduce such distortion as caused when it is heated and cooled and that can also be readily manufactured, and a semiconductor manufacturing apparatus employing the same.
The present invention in one aspect provides a wafer holder for use with a semiconductor manufacturing apparatus, including a conductive layer and a pair of ceramic base members sandwiching the conductive layer therebetween, wherein the conductive layer has a body located at a surface opposite a wafer holding surface of one of the ceramic base members and an extension protruding radially from the body to the outside of a vacuum chamber for external electrical connection, and the body and the extension are arranged substantially in a single plane. Throughout this specification, the extension is also referred to as an “extraction”.
Since the present invention in one aspect provides a wafer holder for a semiconductor manufacturing apparatus including a conductive layer having a body and an extension or extraction provided in a single plane, the body and the extraction can be both posed and thus protected between paired ceramic base members each in the form of a flat plate. This can eliminate the necessity of using a pipe for protecting the extraction, as conventional, and hence the necessity of providing the step of bonding the pipe. As such, the wafer holder can be readily manufactured and also free of such distortion as attributed to bonding such pipe.
In the above one aspect the wafer holder preferably includes the ceramic base member formed of at least one material selected from the group consisting of aluminum nitride, silicon nitride, aluminum nitride oxide and aluminum oxide.
As such, a material
Kuibira Akira
Nakata Hirohiko
Fasse W. F.
Fasse W. G.
Kackar Ram N
Mills Gregory
Sumitomo Electric Industries Ltd.
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