Semiconductor device manufacturing: process – Coating with electrically or thermally conductive material – To form ohmic contact to semiconductive material
Reexamination Certificate
1998-07-06
2001-04-17
Smith, Matthew (Department: 2825)
Semiconductor device manufacturing: process
Coating with electrically or thermally conductive material
To form ohmic contact to semiconductive material
C438S780000, C438S788000
Reexamination Certificate
active
06218299
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a semiconductor device provided with a dielectric film comprising fluorocarbon film, and to a method for producing such a semiconductor device.
BACKGROUND ART
In order to increase the degree of integration of semiconductor devices, some means such as the formation of more minute patterns, and the production of multilayered circuits are now being devised. As one of these means, there is a technology in which wiring layers are formed as multiple layers. In order to attain multi-layer interconnection structure, an wiring layer of layer number n and that of layer number (n+1) are connected by a conductive layer, and, at the same time, a thin film called interlayer dielectric film is formed in the region other than the conductive layer.
SiO
2
film has been known as a representative of this interlayer dielectric film. In recent years, however, it is required to decrease the relative dielectric constant of the interlayer dielectric film in order to further increase the speed of device operation, and studies are now being made on materials suitable for the interlayer dielectric film. Namely, the relative dielectric constant of SiO
2
is approximately “4”, and energy is now being directed to the investigation of materials whose relative dielectric constants are lower than this value. As one of such materials, SiOF whose relative dielectric constant is “3.5” is now being tried to put into practical use. However, we are paying attention to fluorocarbon film whose relative dielectric constant is lower than this.
The interlayer dielectric film is required to have not only a low relative dielectric constant but also high adhesion, high mechanical strength, excellent thermal stability and the like. Teflon (trade name) (polytetrafluoroethylene) is well known as fluorocarbon. However, this one is extremely poor in adhesion, and also has low hardness. Therefore, even if it is tried to use fluorocarbon film as the interlayer dielectric film, there are many unknown points regarding the quality of the film, and it is difficult to put fluorocarbon film into practical use under the present conditions.
DISCLOSURE OF THE INVENTION
The present invention was accomplished under such circumstances. An object of the present invention is to provide a semiconductor device provided with a dielectric film having a relative dielectric constant of “2.5” or lower, comprising fluorocarbon film containing 18 to 66% of fluorine, and a method for producing such a semiconductor device.
A semiconductor device of the present invention is therefore characterized by comprising a dielectric film which comprises fluorocarbon film containing 18 to 66% of fluorine. Further, the semiconductor device may also be constructed by providing, on the top surface of a first dielectric film made of fluorocarbon film, a second dielectric film having hardness higher than that of the first dielectric film. In this case, it is desirable that the second dielectric film be silicon dioxide film.
Furthermore, the semiconductor device may also be constructed by providing, on the underside of the first dielectric film made of fluorocarbon film, a lower dielectric film containing carbon, having adhesion higher than that of the first dielectric layer; or by providing, on the top surface of the first dielectric film, an upper dielectric layer containing carbon, having adhesion higher than that of the first dielectric layer. Moreover, in a semiconductor device in which a dielectric layer is formed on a circuit area, and a plurality of wiring layers and of interlayer dielectric films are laminated on this dielectric layer, the interlayer dielectric films may be formed by using fluorocarbon film, and, at the same time, a thin film containing carbon, having adhesion higher than that of the fluorocarbon film may be formed between the dielectric layer and the fluorocarbon film and/or between the fluorocarbon films. In this case, it is desirable that the lower dielectric film and the upper dielectric film be hydrogenated amorphous carbon films, silicon carbide films, or films composed of carbon, hydrogen and fluorine, in which the fluorine content becomes higher toward the upper part.
In the case where a semiconductor device is constructed by laminating such a dielectric film made of fluorocarbon film, and the dielectric film containing carbon, having adhesion higher than that of the above fluorocarbon film, it is desirable to produce the semiconductor device by a method for producing a semiconductor device, employing, for example, a plurality of vacuum processing chambers, and a carrier chamber provided with a carrier member for carrying a substrate to be processed from one vacuum processing chamber to another vacuum processing chamber, and forming dielectric films by using plasmas created from film-forming gases in the vacuum processing chambers, wherein the method comprises the first step of creating a plasma from a first film-forming gas in a vacuum processing chamber, and forming, on a substrate to be processed, a dielectric film by the use of this plasma, and the second step of carrying the substrate to be processed, on which the dielectric film has been formed, from the vacuum processing chamber in which the first step has been effected to a vacuum processing chamber which is different from the above one by the carrier member, and forming, in this vacuum processing chamber, a dielectric film on the dielectric film which has been formed in the first step, by using a plasma created from a second film-forming gas.
Further, in a semiconductor device in which a protective film is formed on the outermost shell of a semiconductor chip, the protective film may be formed by using fluorocarbon film, and, by controlling the fluorine content of the fluorocarbon film, the inner part of the protective film may be formed by fluorocarbon film having high moisture resistance, and the surface side of the protective film may be formed by fluorocarbon film which is excellent in the property of relaxing stress. In this case, the fluorocarbon film having high moisture resistance desirably contains 40 to 72% of fluorine, and the fluorocarbon film which is excellent in the property of relaxing stress desirably contains 8 to 40% of fluorine.
Furthermore, a method for producing a semiconductor device according to the present invention is characterized by comprising the step of creating a plasma from a pretreatment gas consisting of, for instance, a rare gas or hydrogen-plasma-creating gas, and applying this plasma to a surface to be processed, on which fluorocarbon film is tried to be formed, to form irregularities on the surface to be processed, and the step of creating a plasma from a film-forming gas, and forming, by the use of this plasma, fluorocarbon film on the surface to be processed. In this case, it is desirable to create the plasma from the pretreatment gas by interaction between microwave and magnetic field.
Furthermore, a method for producing a semiconductor device according to the present invention is characterized by comprising the step of forming titanium nitride layer on aluminum, the step of forming an wiring layer by etching the aluminum on which the titanium nitride layer has been formed, and the step of applying nitrogen plasma and/or oxygen plasma to the above-formed wiring layer.
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Akahori Takashi
Aoki Takeshi
Endo Shunichi
Hirata Tadashi
Naito Yoko
Rocchegiani Renzo
Smith Matthew
Smith , Gambrell & Russell, LLP
Tokyo Electron Limited
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