Electric lamp and discharge devices: systems – Discharge device load with fluent material supply to the... – Plasma generating
Reexamination Certificate
2000-05-18
2002-04-30
Wong, Don (Department: 2821)
Electric lamp and discharge devices: systems
Discharge device load with fluent material supply to the...
Plasma generating
C118S7230ER, C156S345420, C204S298370
Reexamination Certificate
active
06380684
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a modified magnetron high-frequency discharge plasma generating apparatus and to a semiconductor manufacturing method, and more particularly to an apparatus for performing various processes on rectangular substrates using a plasma, such as plasma dry etching of a film formed on the surface of a large-area rectangular substrate, or suitable as a plasma CVD (chemical vapor deposition) apparatus for producing a thin film on the surface of a substrate using a plasma-induced vapor phase reaction.
2. Description of the Related Art
In production processes for solid state devices such as semiconductor devices, it is necessary to subject substrates to predetermined processes. One such substrate processing method involves introducing a reactive gas into the reaction chamber in which the process will be performed, and applying heat to induce the gas to react so as to deposit a film on the substrate surface. This method requires relatively high temperatures, which may have a number of adverse effects on devices. Thus, more recently, plasma CVD techniques in which the energy needed to activate the reaction is supplied by a plasma generated through a glow discharge have come into use.
Plasma CVD techniques are also employed for film deposition on rectangular substrates for use in liquid crystal displays of various types, solar cells, and the like. In plasma CVD—the plasma process used for typical large-area rectangular substrates—uniform high-density plasma is needed to accommodate larger-area substrates and to improve apparatus through-put. Plasma sources to meet this need are currently under development. As used herein, “typical large-area rectangular substrates”@refers to those of 860 mm×650 mm class or larger.
However, the plasma sources most relied upon currently are ordinary parallel plate high-frequency discharge plasma sources. Since ordinary parallel plate high-frequency discharge plasma sources generate plasma rather inefficiently, the low film deposition rate poses problems when depositing a film on a substrate surface using plasma CVD. Also, the uniformity of film thickness cannot be said to be adequate at present.
To accommodate rectangular substrates, ordinary parallel plate high-frequency discharge plasma sources currently in use are designed with rectangular electrodes, but since the electric field tends to become concentrated at the corners of the electrodes, plasma density tends to be higher at the electrode corners, with the rate of film deposition being higher in proximity to the electrode corners as well. Using an ordinary parallel plate high-frequency discharge plasma source, when it is attempted to increase the high-frequency power input in order to increase the throughput of the apparatus, high sheath voltage tends to form on the cathode electrode surface to which the high frequency is applied, resulting in a serious problem of metal contamination from the electrode surface. As used herein, “sheath voltage”@refers the potential of the substrate surface relative to the average potential of the plasma space.
Besides the parallel plate high-frequency discharge plasma sources, electron-cyclotron resonance (ECR) plasma sources, inductively-coupled plasma (ICP), micro surface wave, helicon wave, and other high-density plasma sources are also available, but while these give adequate plasma densities, they still have not reached plasma uniformity levels adequate for processing of large-area substrates.
On the other hand, a modified magnetron plasma source employing annular high-frequency electrodes has been disclosed (JP(A) 7-201831). The plasma generating apparatus disclosed in this publication generates plasma by producing a magnetron discharge from a high-frequency electrical field generated by a cylindrical discharge electrode and magnetic fields generated by annular permanent magnets.
The plasma generating apparatus disclosed in the above publication, however, has the drawback that high density plasma cannot be generated in the diametral central area of the plasma generation zone. This is due to the fact that plasma is generated predominantly on the surface of the discharge electrode. Accordingly, any plasma surface processing apparatus designed using this plasma generating apparatus will not be capable of surface processing under conditions of uniform plasma density. This problem can be solved by locating the susceptor some distance from the discharge electrode in the axial direction thereof.
This design, however, while affording surface processing under conditions of uniform plasma density, produces a new problem, namely, inability to perform surface processing under conditions of high plasma density, owing to the excessively large volume of the vacuum chamber. In a plasma generating apparatus of this kind, plasma density declines further away from the discharge electrode in the axial direction thereof due to plasma diffusion loss. Thus, with this design the rate of surface processing tends to be slow, and the efficiency of utilization of the gas and the efficiency of utilization of the electrodes tend to be poor.
Accordingly, there is a need for an apparatus capable of generating high density plasma in both the central area of the discharge electrode as well as in the peripheral area.
SUMMARY OF THE INVENTION
With the foregoing in view, it is an object of the present invention to provide a modified magnetron high-frequency discharge plasma generating apparatus and a semiconductor manufacturing method that solve the problems pertaining to the conventional art so as to allow plasma processing of large-area rectangular substrates to be conducted at high speed.
The plasma generating apparatus recited in claim
1
comprises: a vacuum chamber of rectangular cross section having a plasma generating zone provided therein; gas introducer for introducing a discharge gas into this vacuum chamber; an exhaust for exhausting the atmosphere within said vacuum chamber; a fistulous discharge electrode of rectangular shape (hereinbelow termed simply “rectangular fistulous”), arranged surrounding said plasma generating zone, for inducing discharge of the gas introduced into said plasma generating zone by said gas introducer; first high-frequency power supplier for supplying high-frequency power to said discharge electrode for inducing discharge of said gas; magnetic lines of force generator for producing magnetic lines of force within said plasma generating zone; and a pair of rectangular parallel plate electrodes, arranged so as to sandwich said plasma generating zone in the direction of the central axis of said discharge electrode and to define a range of said plasma generating zone in the direction of this central axis. “Rectangular fistulous” refers to a fistulous configuration having a rectangular aperture.
The gas introducer has the function of introducing the discharge gas and the reactive gas needed for plasma processing into the vacuum chamber. The exhaust has the function of exhausting the atmosphere present within the vacuum chamber to the outside, Since the vacuum chamber for processing the substrate is of rectangular configuration like the substrate, the vacuum chamber need not have excessively large volume in order to process a large-area rectangular substrate, thus improving the efficiency of utilization of the gas and the efficiency of utilization of the high-frequency discharge electrode. Since the discharge electrode for generating the plasma is also rectangular, the space in which the plasma is generated has the same rectangular shape as the substrate. Accordingly, the installation area required for the vacuum chamber can be reduced further, as a result reducing the area occupied thereby in the clean room in which it is installed and reducing the costs associated with clean room maintenance. Interaction between the high-frequency electrical field generated by supplying high-frequency power to the discharge electrode and the magnetic field created by the magnetic lines of for
Iizuka Satoru
Li Yunlong
Sato Masanobu
Sato Noriyoshi
Tominaga Yoshio
Hitachi Kokusai Electric Inc.
Oliff & Berridg,e PLC
Tran Thuy Vinh
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