Coating apparatus – Gas or vapor deposition – Means to coat or impregnate particulate matter
Reexamination Certificate
1999-07-09
2001-01-30
Lund, Jeffrie R. (Department: 1763)
Coating apparatus
Gas or vapor deposition
Means to coat or impregnate particulate matter
C118S715000, C118S718000, C118S725000
Reexamination Certificate
active
06179922
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates generally to semiconductor integrated circuits, and more particularly, to an apparatus and method for fabricating photo sensitive material onto a surface of a semiconductor integrated circuit, such as a spherical-shaped semiconductor device.
Conventional integrated circuit devices, or “chips,” are formed from a flat surface semiconductor wafer. The semiconductor wafer is first manufactured in a semiconductor material manufacturing facility and is then provided to a fabrication facility. At the latter facility, several processing operations are performed on the semiconductor wafer surface. One such process is applying photo resist to the wafer to print integrated circuit patterns on the wafer's surface.
Traditionally, photo resist is made of one or more polymers and solvent by an off-site manufacturer. The photo resist is provided in liquid form to the fabrication facility for coating on the wafer surface. The resist is then dispensed onto a static or slowly rotating wafer and the wafer is spun rapidly to cover the wafers surface with an even, thin coating of the resist. Once covered, the resist is dried to remove any solvents and is available for any subsequent etch processing.
Photo resist is used to produce an “image” on the wafer surface. The image is responsive to light, so that where the light strikes, the resist becomes polymerized and more difficult to remove (i.e., the resist is developed). The non-polymerized regions may then be removed with etchants, including any layers under the non-polymerized regions. As a result, mask patterns can be placed on the wafer surface and used to create underlying circuit patterns in the semiconductor substrate.
The main requirements for resist application are that the resist be pinhole-free and of uniform and reproducible thickness. Very tight layers of resist are also generally required. However, the use of thin layers of resist requires much more attention be given to the removal of particles and gelatinous masses from the resist before it is dispensed.
There are many problems associated with conventional resist applications. For example, resist quality has a short life-span because it is difficult to maintain the solvents in liquid form in a normal environment. Solvents are used to maintain the liquid form, but must be efficiently removed during processing. Also, it is difficult to coat the photo resist on the wafer with a uniform thickness. Furthermore, although resist is filtered by the manufacturer, subsequent contamination may occur and long storage times produce more gel. To resolve this, the resist is often re-filtered just before application. What is needed is a system for applying photo resist to a substrate that does not experience the quality deterioration and maintenance difficulties associated with conventional resist applications.
In a continuing effort to provide an all-dry lithographic process, both dry application and dry developing of the resist are desired. Thus far, no production-worthy success has been achieved with dry resist application, and no production-worthy plasma-developable resists currently exist. What is needed is a system that facilitates the dry application and dry developing of photo resist.
Another problem with conventional photo resist applications is that they only work with relatively flat, wafer-shaped substrates. In U.S. Pat. No. 5,955,776 filed on May 16, 1997, a method and apparatus for manufacturing an integrated circuit on a spherical-shaped semiconductor is disclosed. Inherently, the technique of applying photo resist to a portion of a spherical shaped substrate and then spinning the substrate to spread the resist does not work well. Therefore, what is needed is a system that can apply the photo resist to various shaped substrates, such as a spherical-shaped semiconductor substrate.
SUMMARY
In response to the aforementioned problems, an improved chemical vapor deposition (“CVD”) photo resist and deposition system onto a semiconductor substrate is provided. In one embodiment, the system includes a processing chamber and a connected gas chamber. The gas chamber receives a monomer and supplies sufficient energy for polymerization of the monomer, thereby creating a polymer vapor. The processing chamber receives the semiconductor substrate and the polymer vapor. CVD is then performed in the processing chamber so that the polymer vapor deposits a thin layer of photo resist on the surface of the semiconductor substrate.
In some embodiments, a heater is connected to the gas chamber for facilitating the polymerization of the monomer. The heater may also facilitate the application of the polymer vapor onto the semiconductor substrate.
In some embodiments, the processing chamber includes an inlet and an outlet diametrically opposed to each other. In this way, the semiconductor substrate can move through the processing chamber and have the photo resist applied during the movement. This works well with substrates that are substantially spherical in shape.
In some embodiments, an inert carrier gas is also used with the system. The carrier gas may be used to facilitate the movement of the monomer in the gas chamber and/or to provide heat in the gas chamber to facilitate a rate of polymerization.
In another embodiment, the system includes a processing chamber and a heater. The processing chamber is for receiving the semiconductor substrate and the monomer. The heater surrounds and heats an interior of the processing chamber so that the heated processing chamber can convert the monomer into a polymer vapor. The polymer vapor will then deposit a thin film of photo resist about the semiconductor substrate's surface.
In some embodiments, both the monomer and the polymer vapor may be deposited on the semiconductor substrate. However, the deposited monomer subsequently polymerizes.
In some embodiments, the heater serves to harden the deposited polymer vapor.
In some embodiments, the semiconductor substrate is one of a sequence of similar shaped semiconductor substrates being sequentially provided to the processing chamber. The similar shape may be spherical or otherwise.
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Ishikawa Akira
Ohkusa Tadao
Ball Semiconductor Inc.
Haynes and Boone LLP
Lund Jeffrie R.
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