Coating apparatus – Gas or vapor deposition – With treating means
Reexamination Certificate
1998-03-18
2002-07-23
Jones, Deborah (Department: 1775)
Coating apparatus
Gas or vapor deposition
With treating means
C118S7230IR, C118S7230ER, C204S298340, C204S298370, C204S298380
Reexamination Certificate
active
06422172
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a processing apparatus including a plasma generating means, and particularly to a plasma processing apparatus which is used for plasma etching of a type suitable for forming fine patterns on semiconductor devices or liquid crystal display elements and also suitable for uniformly processing large-diameter substrates, and which is used for plasma CVD and plasma polymerization suitable for forming thin films with fine structures; and the invention relates to a plasma processing method using the plasma processing apparatus.
In a plasma processing apparatus for processing semiconductor elements or liquid crystal display elements using a plasma, it is necessary to control the radical species and the energy of ions to be incident on a substrate to be processed, the directivity of ions, and the uniformity of plasma processing exerting an effect on the processing capability, and also to enhance the productivity of plasma processing.
With respect to the control of radical species, a parallel plate electrode type plasma processing apparatus has been disclosed, for example, in Japanese Patent Laid-open No. Sho 57-131374, and an example of this parallel plate electrode type plasma processing apparatus is shown in FIG.
17
.
In the apparatus shown in
FIG. 17
, a processing chamber
9
surrounded by a cylindrical side wall portion
6
, an insulating portion
5
, and a disk-like electrode
2
is kept in a vacuum by an evacuating means (not shown). A processing gas is supplied from a gas supplying means
7
into the processing chamber
9
through the electrode
2
serving as a gas introducing passage. In general, the side wall portion
6
is earthed, and is insulated from the electrode
2
by means of the insulating portion
5
. The electrode
2
and a stage
3
constitute parallel plate electrodes. When power is applied from a power supply
1
between these parallel plate electrodes, a plasma of the processing gas is generated in the processing chamber
9
.
A wafer
4
to be processed is placed on the stage
3
at a lower portion of the processing chamber
9
and is subjected to fine processing by plasma generated in the processing chamber
9
and radical species in the processing gas activated by the plasma. At this time, the plasma density and the temperature of electrons in the plasma are changed, and, at the same time the decomposition state of the processing gas, that is, the amount and the ratio of the radical species exerting an effect on the fine processing capability are changed, depending on the power inputted from the power supply
1
, the pressure in the processing chamber
9
, the width of the gap between the electrode
2
and the stage
3
, and the like.
With respect to control of the energy of the ions, there is a method disclosed in Japanese Patent Laid-open No. Hei 4-239128.
In this method, a divergent magnetic field is provided in such a manner as to be directed perpendicularly to parallel plate electrodes, whereby a self-bias voltage is controlled independently of the output from a high-frequency power supply for generating plasma, so as to independently control the energy of ions to be incident on a substrate by the magnetic field, thereby performing etching at a high accuracy with no damage.
As a method of enhancing the directivity of ions without a reduction in processing rate, there is a method disclosed in Japanese Patent Laid-open No. Hei 8195379.
This method is intended to realize plasma processing capable of generating a high density plasma at a low pressure and of enhancing the controllability of the plasma density distribution by generating a capacitive coupled plasma mixed with an inductive coupled plasma.
As a plasma processing apparatus for controlling the uniformity of plasma processing, there is an apparatus disclosed in Japanese Patent Laid-open No. Sho 61-283127.
In this apparatus, an electrode to which a high-frequency power is applied is divided into a plurality of parts, wherein the power applied to each of the divided electrode parts is independently controlled, to thereby improve the uniformity of plasma processing.
A large problem occurring in the case of enhancing the productivity of plasma processing is that a film, formed on an inner wall surface of a processing chamber during etching or plasma CVD, peels or flakes to give rise to dust, and the dust acts to reduce a rate of production of non-defective products to the total products being produced, such as highly integrated semiconductor devices and liquid crystal display elements, that is, to reduce the production yield. Another problem is that in the course of production, processing characteristics are changed, which also reduces the production yield.
The occurrence of dust will be more fully described below. A deposition film formed on an inner wall surface of a processing chamber by plasma processing is subjected to repeated temperature changes due to variations in heat inputted from the plasma, with a result that a stress occurs in the deposition film. Then, when the film is made thicker, the stress in the film becomes larger than the adhesive force of the film, causing peeling of the film, leading to the occurrence of dust.
A plasma processing apparatus which is intended to remove a deposition film formed on an inner wall surface of a processing chamber is disclosed in Japanese Patent Laid-open No. Hei 8-330282. In this apparatus, the removing rate of a deposition film is enhanced by increasing the energy of ions incident on a surface on which a deposition film is formed.
Further, a method of converting a deposition film formed on an inner wall surface of a processing chamber into a volatile material and exhausting such a material using an evacuating system is disclosed in Japanese Patent Laid-open No. Hei 7-153751. In this method, a non-gaseous material disposed in a processing chamber reacts with the plasma to create reactive chemical species, which in turn react with a deposition film to convert the deposition film into a volatile material, followed by cleaning of the volatile material.
To stabilize the processing characteristics of plasma processing, Japanese Patent Laid-open Nos. Hei 6-188220 and Sho 61-8927 disclose a method of controlling the temperature of an inner wall surface of a plasma processing chamber at a specific value and an apparatus provided with parallel electrodes cooled by a fluid.
SUMMARY OF THE INVENTION
With a tendency toward higher integration of semiconductor devices and substrates of larger diameter for producing semiconductor devices, it is further required to attain high selectivity with respect to underlying materials, high accuracies in the processing of shapes, uniform processing of large-sized substrates, and reduction in the occurrence of dust.
1) One factor exerting a large effect on processing characteristics, such as a selectivity, the processing shape and the film quality in plasma etching and plasma CVD, is based on radical species produced by collision of electrons in the plasma. The generation amount and the kinds of radical species are dependent on the energy state of electrons in the plasma.
The energy state of electrons in the plasma is determined on the basis of the collision frequency of electrons depending on the processing pressure, the disappearance rate of electrons due to diffusion of electrons in the plasma, and the like. The energy state of electrons in plasma is expressed by a statistical distribution based on the collision of the electrons with neutral molecules, ions and the like. It has been considered difficult to control such a statistical distribution of the energy state of electrons, except that the statistical distribution can be changed by varying the collision frequency of electrons through control of the processing pressure. For this reason, to control the energy state of electrons, there has been adopted a method of controlling the processing pressure. Such a method of controlling the processing pressure, however, has a problem. That is, in the case of etching, it
Kaji Tetsunori
Masuda Toshio
Otsubo Toru
Sasaki Ichiro
Tanaka Jyunichi
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