Coating apparatus – Gas or vapor deposition
Reexamination Certificate
2002-05-13
2004-05-11
Lund, Jeffrie R. (Department: 1763)
Coating apparatus
Gas or vapor deposition
C118S719000, C118S724000, C118S725000, C156S345520, C414S935000
Reexamination Certificate
active
06733592
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a device for treating ULSI semiconductors represented by Si wafers in a high-temperature, high-pressure atmosphere. More particularly, the invention relates to a device used for a treatment for eliminating pores mainly by means of inert gas pressure, such as a so-called pressure filling method (high-pressure reflow process) for wiring films by which wafers having wiring films formed therein are treated using inert gas pressure.
2. Description of the Related Art
One example of a known semiconductor wafer fabrication process including a high-pressure gas treatment is a so-called pressure filling method for wiring films (high-pressure reflow processes; disclosed in Japanese Unexamined Laid-Open Applications Nos. 2-205678, 3-225829, and 7-193063) in which wafers having aluminum alloy wiring films formed therein by a PVD method are treated using inert gas pressure.
Further, an example of a known semiconductor processing technique using a gas whose pressure is as high as several tens atm is a high-pressure oxidation process in which a dielectric layer is formed by oxidizing the surface of a Si wafer. Since this treatment is intended for oxidation, oxygen or water is inevitably mixed into a pressure medium.
It is known that the former process uses a so-called single wafer processing cluster tool type device by which semiconductor wafers are subjected to a PVD treatment and then to a high-pressure treatment one by one. As disclosed in Japanese Unexamined Patent Laid-Open Application No. 7-193063 (see FIG. 6 in the said publication), this device treats wafers by sequentially transferring the wafers in a lock chamber to a series of treating modules disposed around a core chamber using a transfer arm inside the core chamber. A high-pressure module directly installed to the core chamber has been proposed as one of the modules (Prior art 1). An example of a more detailed structure of this high-pressure module has also been proposed by the same applicant in Japanese Unexamined Patent Laid-Open Application No. 7-502376 (Prior art 2).
It is also known that the latter process, particularly a process performed in an atmosphere of high-pressure gas using a vertical boat (wafer stacking jig), employs a device such as disclosed in Japanese Unexamined Patent Laid-Open Application No. 4-234119 (Prior art 3).
This device, although completely different from the device of the present invention in its application, is indicated as the prior art for reference because its construction is similar to that of the device of the invention. Prior art 3 is “a device for treating semiconductor wafers characterized by comprising: a pressure vessel; a hollow body having a treatment chamber within the pressure vessel, the hollow body having a lower opening for receiving a plurality of wafers when the plurality of wafers are moved as a group from a position in a lower region of the pressure vessel to a position within the treatment chamber; operating means movable perpendicularly to the pressure vessel for closing the opening; means for introducing a high-pressure inert gas into the pressure vessel; means for beating an oxidizing agent within the treatment chamber; means for cooling the hollow body after the wafers have been processed within the treatment chamber; and means, coupled with the pressure vessel and the hollow body for equalizing the pressure of the inert gas and that of the oxidizing agent and coupled with a main body for equalizing the pressure of the inert gas and that of the oxidizing agent, for substantially separating the insert gas from the oxidizing agent.” The wafers, which are the products to be treated, are treated while stored in a vertical boat that can stack several tens to one hundred and several tens of wafers thereon.
In the single wafer type devices, such as Prior arts 1 and 2, whose treatment mode is different from that of a so-called batch type device according to the present invention, problems inherent in their processing mode are more serious than drawbacks attributable to their structure.
That is, to meet the requirement that the cycle time of the single wafer processing be substantially equal to that of the concurrently performed PVD treatment, a short-cycle operation must be repeated more than tens of thousands of times per month.
In such a heavy-duty operation, various parts and components including the seal structure, seal material and the like of the opening and closing part of the vessel are used under so severe conditions that it would be quite difficult for these devices to secure safety and treatment reliability.
Especially, taking the pressure filling method for wiring films as an example, it is difficult to design a single wafer treatment device having a satisfactory life standing up to 1,000,000 or more operations for the following reasons. In the pressure filling method for wiring films, copper films are replacing conventional Al films in recent years, and the pressure filling method for these copper films require a high pressure of 100 MPa or more, or even 150 MPa at low temperatures of 350-400° C. Due to such a high pressure involved in the process, it is difficult to design a single wafer treatment device with a satisfactory life.
Further, the high-pressure oxidation device such as Prior art 3 is operated with an inert gas unless an oxidizing agent is introduced. Since the device of this type is originally intended to perform an oxidation treatment, no considerations are given to air that inevitably enters into the high-pressure vessel when objects to be treated are put in and out of the vessel. That is, no such considerations are given at all since unlike the pressure filling method having to cope with the oxidation problem of wafers, the oxidation treatment requires no measures to prevent possible mixture of oxygen, i.e., mixture of oxygen accompanied by mixture of air. Therefore, this device addresses problems when operated in an almost inert atmosphere, especially in an oxygen-free atmosphere.
Under such prior art situation, a recent tendency is that wafers not only have larger diameter from 8 to 12 inches, but also are managed in a smaller lot size. In a standard fabrication process for 8 inches wafers, twenty-five wafers are stored in a single cassette, and product quality control is carried out on a lot basis, the size of a lot being 25, 50, or 100 wafers, i.e., multiples of 25.
However, the minimum lot size of twenty-five wafers is likely to change to, for example, thirteen as the wafer diameter increases to 12 inches. Particularly, the lot size will probably be decreased for the production of semiconductors applied to logic parts that are to be fabricated in small quantities and in various types. Under such circumstances, it is most likely that a device capable of flexibly accommodating various production quantities with a minimum lot size will dominate the future design of a fabrication device.
The above-mentioned single wafer treatment devices (Prior arts 1 and 2) could respond to this requirement. However, their structure of being integrated with a film-forming device used in the preceding step of sputtering rather imposes difficulty when they need to be operated with other film-forming methods, e.g., a plating method in combination.
To meet such needs, it is preferable to use a device or system capable not only of operating independently of the preceding and succeeding steps but also of treatment efficiently a small lot of one to ten or so wafers in accordance with the production quantity. However, such a device or system has not yet been proposed.
On the other hand, due to the fact that the formation of oxide films by oxidation is time-dependent, the oxidation treatment device such as shown as Prior art 3 inevitably requires much time for processing even a small lot of wafers. Thus, the device of this type has many problems to be overcome.
For treatment not so time-restricted as above, a device or system capable of processing a small lot of wafers quickly while maint
Fujikawa Takao
Inoue Yoichi
Ishii Takahiko
Kadoguchi Makoto
Masuda Tsuneharu
(Kobe Steel, Ltd.)
Lund Jeffrie R.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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