Coating apparatus – Gas or vapor deposition – Multizone chamber
Reexamination Certificate
1998-10-26
2001-03-20
Meeks, Timothy (Department: 1762)
Coating apparatus
Gas or vapor deposition
Multizone chamber
C118S050000, C118S050100, C118S629000
Reexamination Certificate
active
06203619
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to apparatus and methods that more efficiently fabricate thin films for use in the active components of integrated circuits, and more particularly, such apparatus and methods employing misted liquid deposition devices and techniques.
2. Statement of the Problem
The formation of thin films of complex chemical compounds such as metal oxides, ferroelectrics, materials with high dielectric constants, and so on, is very important in the integrated circuit art. It is particularly difficult to form thin films for use in active components in integrated circuits; that is, components that perform an electrical function, such as charge storage or control, as opposed to materials that merely serve as temporary sacrificial layers or insulation or protective packaging for an integrated circuit. This difficulty arises from the fact that even minor microscopic defects can result in the loss of an entire device, and thus significantly decrease the yield and increase the cost of producing integrated circuits. Thus, the art of fabricating thin films for active components is a highly developed art with much ongoing research.
Some methods of forming thin films of complex chemical compounds for integrated circuits are: physical vapor deposition (PVD) techniques, such as thermal, electron beam, molecular beam epitaxy, laser ablation and sputtering; chemical vapor deposition (CVD); and misted deposition. See, for example, U.S. Pat. No. 5,648,114 issued Jul. 15, 1997, and U.S. Pat. No. 5,456,945 issued Oct. 10, 1995. All of these methods are used in commercial manufacturing systems, though they each have significant disadvantages. PVD techniques typically require a deposition environment of medium vacuum (~10
−3
to 25 torr), high vacuum (~10
−7
to 10
−3
torr), or very high vacuum (~10
−12
to 10
−7
torr) to create or maintain an evaporate vapor, to prevent contamination from atmospheric gases, and/or to create sub-micron thin films. Such vacuums can be costly to create and maintain, and the corresponding vacuum pumps themselves have the potential of introducing contaminants (such as oil) into the deposition chambers unless additional preventative measures are introduced. Further, the physical necessity of pumping the vacuum chambers to the corresponding operating range and waiting until the interior surfaces have completed outgasing the residual atmospheric gases can take from several hours to several days. Such costs and delays reduce the efficiency and, hence, the commercial value of large-scale PVD manufacturing. Although CVD can operate at low vacuum (~25 to 760 torr), CVD requires transport of the precursors of the material desired to be deposited via chemically reactive carrier gases. The chemical reactions or decompositions that result in the desired deposition also frequently create exhaust products that are toxic or corrosive, which then require additional procedures (typically involving scrubbers) to prevent their release into the atmosphere. Further, CVD requires cleaning of the deposition chamber on a frequent and regular basis to maintain high quality of the thin films subsequently fabricated in the same chamber. As in PVD techniques, such encumbrances erode the efficiency of large-scale manufacturing by CVD. Misted deposition devices and processes in the prior art operate at low vacuum and do not require the maintenance of CVD devices, but are not suited to large-scale manufacturing since only one wafer can be fabricated at a time. Thus, an apparatus and method for producing thin films for use in active components in integrated circuits that is capable of sustained continuous or semi-continuous production that is easy and relatively cheap to maintain, produces a finished and consistently high quality thin film, permits a shorter production time, and results in high yields of integrated circuit chips would be highly desirable.
SUMMARY OF THE INVENTION
An object of the invention is to provide a relatively low energy process and apparatus for manufacturing high quality thin films of use in active components in integrated circuits in commercial quantities.
Another object of the invention is to provide such a process and apparatus that employs a low or no vacuum environment.
Another object of the invention is to provide one or more of the above objects in a process and apparatus that does not require the use of reactive chemistry and does not create toxic or corrosive by-products.
Another object of the invention is to provide one or more of the above objects in a process and apparatus that does not require frequent cleaning of the deposition chamber.
A further object of the invention is to provide one or more of the above objects in a process and apparatus that permits automatic processing of multiple wafers.
Still a further object of the invention is to provide one or more of the above objects in a relatively fast process capable of mass production of high quality thin films in a relatively short time.
The invention provides an assembly line type of manufacturing process for the fabrication of solid thin films on integrated circuit substrates from liquid precursors.
The invention provides a movable platen that includes a plurality of integrated circuit substrate stations. The invention also provides a plurality of fabrication devices arranged in a predetermined sequence and spaced at a distance corresponding to the distance between the substrate stations on the platen. The substrate stations progress from the operational vicinity of one fabrication device to the next, and while one manufacturing process step is being performed on one substrate, other manufacturing process steps are being performed on other substrates at other stations. Each substrate station progresses along a series of fabrication devices until a solid thin film is completed on the substrate. In this manner, three or more integrated circuit substrates may be simultaneously processed to form a high electronic quality thin film on each substrate.
In the preferred embodiment, the predetermined sequence of fabrication devices include a liquid deposition device, a device for drying the deposited liquid film, and a device for solidifying the dried film to form a solid thin film. Preferably, the method steps include depositing a liquid film, drying the film, and annealing the dried film.
Preferably, the deposition device comprises a misted deposition device. Preferably, the misted deposition device includes a mist showerhead and a vacuum chamber for enclosing the substrate. Preferably, the misted deposition device includes an electrical particle acceleration system. Alternatively, the deposition device can comprise a spin coating device.
Preferably, during the deposition process, the substrate is at ambient temperature. Preferably, the ambient temperature is between about 15° C. and 40° C. In general, the temperature may be between about −50° C. and 100° C.
Preferably, the misted deposition is performed in a low vacuum, generally between approximately 5 Torr and 800 Torr. More preferably, the vacuum is maintained between about 450 Torr and 700 Torr.
Preferably, the drying device comprises a heater, though it may also comprise the above-mentioned vacuum chamber.
Preferably, each substrate is dried by heating it to between 100° C. and 300° C.
After the substrate is dried, it is optionally baked at a temperature of between 250° C. and 450° C.
Preferably, the solidification device comprises a rapid thermal processing (RTP) device. Alternatively, the solidification device may comprise a furnace.
Preferably, the rapid thermal processing step is performed at a temperature between 300° C. and 850° C., with a ramping rate between 1° C./sec and 175° C./sec, and most preferably 75° C. per second, and with a holding time of five seconds to 300 seconds. The annealing step, if performed in a furnace, is performed at a temperature between 500° C. and 850° C. for a period of between 15 minutes and three hours.
In one embodiment, a
Calcagni Jennifer
Duft, Gra{dot over (z)}iano & Forest, P.C.
Meeks Timothy
Symetrix Corporation
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