JP2004040017A - Plasma treatment apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plasma treatment apparatus capable of preventing plasma from being diffused to the lower part of a vacuum container without lowering a gas exhaust characteristic. <P>SOLUTION: Shield meshes having two kinds of hole diameters are halved and arranged on a wafer-present side and an absent part of the vacuum container; and holes of diameter small enough to securely prevent discharge diffusion are formed in a punching metal shape on a surface which is nearly perpendicular to a gas flow and holes of a diameter large enough to secure the exhaust characteristic are formed in a punching metal shape on a surface which is nearly parallel to the gas flow. Or shield meshes having a certain angle relative to the gas flow are halved and arranged on the wafer-present side and absent side of the vacuum container. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a plasma processing apparatus used in a thin film forming step or a fine processing step in manufacturing a semiconductor element, a liquid crystal display panel, a solar cell, or the like.
[0002]
[Prior art]
2. Description of the Related Art In recent years, in a plasma processing apparatus, efforts have been actively made to realize high accuracy, high speed, large area, and low damage in order to enhance the functionality of a device and reduce the processing cost. In order to meet such various demands and realize further progress of devices, it is common to use a processing technique using plasma, for example, a dry etching method, a sputtering method, a plasma CVD method, etc. Is mentioned.
[0003]
Above all, in dry etching used for microfabrication, it is required to generate a low electron temperature plasma in order to etch a new material for the purpose of improving the electrical characteristics of a device and to secure dimensional accuracy. Therefore, at present, the frequency of the high-frequency power has been further increased as plasma generation means.
[0004]
Hereinafter, among the above-described plasma processing techniques, a dry etching method (hereinafter, referred to as “D / E”) will be particularly described. FIG. 4 is a schematic diagram of a conventional dry etching apparatus.
[0005]
In FIG. 1, a vacuum vessel 101 has a gas inlet 130 connected to a gas inlet system, and a gas exhaust system 120. The vacuum vessel 101 includes a substrate holding table 103 on which a substrate 102 is placed.
[0006]
Hereinafter, specific operation specifications of D / E will be described.
[0007]
First, a reaction gas is introduced from the gas inlet 130, and the inside of the vacuum chamber 101 is adjusted to a pressure at which plasma processing can be performed with the highest accuracy. Then, the high-frequency power is supplied to the substrate holder 103 and the antenna 171 from the high-frequency power sources 107 and 170, respectively. To generate plasma. The substrate 102 placed on the substrate holding table 103 can be etched by the action of the plasma thus generated.
[0008]
After the D / E is completed, the high-frequency power supplied to the substrate holding table 103 and the antenna 171 and the reaction gas introduced from the gas inlet 130 are stopped, and the gas exhaust system 120 temporarily evacuates the vacuum chamber 101. I do. Thereafter, the substrate 102 is peeled off from the substrate holding table 103 by the push-up mechanism 105, and a series of processing is completed.
[0009]
However, in the above-described plasma processing apparatus, when the applied frequency is increased to lower the plasma electron temperature, the plasma spreads from the vicinity of the substrate holder 103 to the gas exhaust system 120 (hatched portion 129). Problems will arise. Since the plasma spread to the lower portion of the vacuum vessel 101 is completely unnecessary for processing the substrate 102, the processing efficiency is deteriorated with respect to the input power. This has been a factor that causes problems such as generation of dust due to adhesion or an increase in maintenance work.
[0010]
In order to solve the above problem, in the invention disclosed in Japanese Patent Application Laid-Open No. 2001-182167, a shield plate made of a porous material is provided around a substrate holding table to prevent electromagnetic waves from leaking, thereby eliminating unnecessary parts such as a lower part of a vacuum vessel. It prevents the spread of the plasma into the space.
[0011]
[Problems to be solved by the invention]
However, in the above-described prior art, as a means for preventing the diffusion of plasma, the hole diameter of the porous shield plate provided around the substrate holding table is made as small as possible.
[0012]
Certainly, as one means to prevent plasma diffusion, reducing the hole diameter of the shield plate may have a certain effect, but there is a trade-off relationship between plasma diffusion and gas exhaust characteristics. At present, as the exhaust opening becomes smaller, it is difficult to maintain the inside of the vacuum vessel at a high vacuum by introducing a reaction gas, adjusting the pressure inside the vacuum vessel to a pressure that can accurately perform plasma processing, and maintaining the inside of the vacuum vessel at a high vacuum. In particular, when the substrate is a large-sized liquid crystal or a 300-mm wafer, the above problem becomes conspicuous because the flow rate of gas introduced into the vacuum vessel increases.
[0013]
An object of the present invention is to solve the above-mentioned conventional problems and to provide a plasma processing apparatus capable of preventing plasma from diffusing to a lower portion of a vacuum vessel without reducing gas exhaust characteristics. With the goal.
[0014]
[Means for Solving the Problems]
In order to achieve the above object, a plasma processing apparatus according to claim 1 includes a vacuum container capable of maintaining a vacuum, and a gas supply / exhaust system configured to supply and exhaust gas into the vacuum container. A plasma processing apparatus comprising: a substrate holder in which the substrate to be processed by plasma is placed in the vacuum vessel; and a high-frequency power supply that applies high-frequency power to an antenna disposed opposite to the substrate holder. A porous body is arranged around the substrate holder, and the inside of the vacuum container is divided into two sides by the porous body into a side where the substrate is and a side where the substrate is not provided, and the porous body mounts the substrate of the substrate holder. And a second surface substantially perpendicular to the first surface.
[0015]
Also, in the plasma processing apparatus according to claim 2, in the plasma processing apparatus according to claim 1, the diameter of the hole formed on the first surface is larger than the diameter of the hole formed on the second surface. It is characterized by being small.
[0016]
According to a third aspect of the present invention, in the plasma processing apparatus according to the first or second aspect, the diameter of the hole formed in the first surface is 0.1 mm or more and 2 mm or less. Features.
[0017]
According to a fourth aspect of the present invention, there is provided the plasma processing apparatus according to any one of the first to third aspects, wherein the diameter of the hole formed in the second surface is greater than 2 mm and equal to or less than 5 mm. It is characterized by being.
[0018]
According to a fifth aspect of the present invention, in the plasma processing apparatus according to any one of the first to fourth aspects, a high frequency of 500 kHz to 300 MHz is applied to the antenna.
[0019]
The plasma processing apparatus according to claim 6 is the plasma processing apparatus according to any one of claims 1 to 5, wherein a discharge cover is disposed between the vacuum vessel and the porous body. I do.
[0020]
Further, the plasma processing apparatus according to claim 7 includes a vacuum container capable of maintaining a vacuum, a gas supply / exhaust system configured to supply and exhaust gas into the vacuum container, and a gas supply / exhaust system provided in the vacuum container. A plasma processing apparatus comprising: a substrate holder on which a substrate to be processed by plasma is mounted; and a high-frequency power supply for applying high-frequency power to an antenna disposed opposite to the substrate holder. A porous body is arranged around the substrate, and the inside of the vacuum vessel is divided into two sides by the porous body into a side where the substrate is not provided and a side where the substrate is not provided. It is characterized by having and being arranged.
[0021]
The plasma processing apparatus according to claim 8 is the plasma processing apparatus according to claim 7, wherein when the hole axis of the porous body is projected on a surface perpendicular to the gas flow, the projected hole diameter is 0.1 mm. It is characterized in that it is not less than 2 mm.
[0022]
A plasma processing apparatus according to a ninth aspect is the plasma processing apparatus according to the seventh or eighth aspect, wherein a high frequency of 500 kHz or more and 300 MHz or less is applied to the antenna.
[0023]
Furthermore, the plasma processing apparatus according to claim 9 is the plasma processing apparatus according to any one of claims 7 to 9, wherein a discharge cover is disposed between the vacuum vessel and the porous body. I do.
[0024]
BEST MODE FOR CARRYING OUT THE INVENTION
(1st Embodiment)
A first embodiment of the present invention will be described in detail with reference to FIGS.
[0025]
In FIG. 1, the vacuum vessel 1 has a gas inlet 30 connected to a gas introduction system, and a gas exhaust system 20. Further, a substrate holder 3 for electrostatically adsorbing the substrate 2 is provided in the vacuum vessel 1, and an AC power source 7 of 500 kHz for plasma generation is connected to the substrate holder 3. Further, a 100 MHz AC power supply 70 for plasma generation is similarly connected to the antenna 71.
[0026]
Hereinafter, specific operation specifications of D / E will be described.
[0027]
First, the substrate 2 is set on the substrate holder 3 using the push-up mechanism 5 provided below the substrate holder 3. After that, argon (Ar), which is a reaction gas, is introduced at a rate of 200 cc / min from the gas inlet 30, the pressure in the vacuum vessel 1 is adjusted to 0.5 Pa, and the AC power sources 7 and 70 supply the substrate holder 3 and the antenna 71. Plasma is generated by supplying high-frequency power of 1 kw and 2 kw, respectively. The substrate 2 placed on the substrate holder 3 can be etched by the action of the plasma generated in this manner.
[0028]
After the D / E is completed, the high-frequency power supplied to the substrate holding table 3 and the antenna 71 and the reaction gas introduced from the gas inlet 30 are stopped, and the gas exhaust system 20 temporarily evacuates the vacuum chamber 1. Do. Thereafter, the substrate 2 is peeled off from the substrate holding table 3 by the push-up mechanism 5, and a series of processing is completed.
[0029]
At this time, a shield mesh having two kinds of hole diameters is provided in the vacuum vessel 1 so as to prevent plasma generated during the D / E processing from spreading to a lower portion of the vacuum vessel 1. 21 is arranged so as to be divided into two sides on the side of the vacuum container with and without the wafer.
[0030]
FIG. 2 is a schematic diagram illustrating the shield mesh 21.
[0031]
In FIG. 2, a surface 21a substantially perpendicular to the gas flow (hereinafter referred to as "first surface") is a surface having a hole diameter of 1.5 mm (21b) formed in a punching metal shape and substantially parallel to the gas flow. 21c (hereinafter, referred to as "second surface") is formed in a punched metal shape with a hole diameter of 3 mm (21d). That is, the hole diameter 21b plays a role of reliably preventing the diffusion of plasma, and the hole diameter 21d plays a role of ensuring desired gas exhaust characteristics.
[0032]
As described above, the first surface 21a and the second surface 21c are provided around the substrate holding table 3, and a predetermined hole diameter is provided in each of the first surface 21a and the second surface 21c, so that the plasma is diffused to the lower part in the vacuum vessel 1. Not only can the gas exhaust characteristics be maintained at a desired pressure. The experimental results by the inventor have confirmed that the pressure can be adjusted to the desired pressure of 0.5 Pa even when the reactant gas is introduced about twice as much as the conventional technology, as compared with the conventional technology. Further, it was also confirmed that the same effect as that of the prior art was obtained with respect to the diffusion of plasma to the lower part of the vacuum vessel.
[0033]
In the present embodiment, an example is shown in which the hole diameter D ₁ of the first surface is set to D ₁ = 1.5 mm and the hole diameter D ₂ of the second surface is set to D ₂ = 3 mm. The same effect can be obtained even when ≦ D ₁ ≦ 2 mm and 2 mm <D ₂ ≦ 5 mm.
[0034]
(Second embodiment)
In the first embodiment, when the first surface 21a and the second surface 21c are substantially perpendicular to each other, the diffusion of the plasma to the lower part of the vacuum vessel is prevented. An example of maintaining this is shown. This embodiment shows an example in consideration of the relationship between the shield mesh and the substrate holder.
[0035]
FIG. 3 is a schematic diagram of the shield mesh 22 according to the present embodiment. In addition, in order to distinguish it from the shield mesh in the first embodiment, the reference numeral is newly assigned to the shield mesh 22. The shape, configuration, and operation procedure of other members constituting the plasma processing apparatus are the same as in the first embodiment.
[0036]
The shield mesh 22 has a flat portion 22a and a hole diameter of 4 mm (22b) formed in a punching metal shape. The plane portion 22a is arranged at an angle of 60 degrees from the horizontal plane so as to bisect the side of the vacuum container 1 with and without the wafer.
[0037]
According to the experimental results by the inventor, it has been found that the diffusion of the plasma increases when the hole axis of the shield mesh 22 and the gas flow direction substantially coincide with each other. Therefore, as shown in FIG. 3, it was confirmed that when the flat portion 22 a was installed at an angle with the gas flow, although the plasma was slightly diffused, the plasma was stopped in the vicinity. Needless to say, since the hole diameter 22b is 2 mm or more, the required and sufficient performance is obtained as compared with the conventional gas exhaust characteristics.
[0038]
In the present embodiment, only the case where the angle θ between the plane portion and the horizontal plane is θ = 60 degrees is shown. However, a preferable result can be obtained even when θ = about 60 degrees ± 10 degrees.
[0039]
Furthermore, according to the experimental results by the inventor, when the shield mesh 22 is projected on a plane orthogonal to the gas flow, if the projected hole diameter 22b is 2 mm or less, the diffusion of plasma stops near the shield mesh 22. I also checked. That is, in order to operate the plasma processing apparatus stably for a long time, the hole diameter 22b of the shield mesh 22 is sufficiently considered, and the effect is high when the projected hole diameter is 2 mm or less.
[0040]
Further, as shown in FIG. 3, a discharge cover 23 may be arranged between the vacuum vessel 1 and the shield mesh 22. This is because the region where the plasma is diffused can be suppressed to be narrow, so by making the region a replaceable member, even if parts should be worn out due to discharge, dirt, etc., parts can be replaced quickly and inexpensively, Downtime of the plasma processing apparatus can be reduced. In addition, as a desirable configuration of a plasma processing apparatus that suppresses a region where plasma is diffused to be narrow and secures gas exhaust characteristics, when viewed concentrically with a substrate, a vacuum vessel and an auxiliary member that partition a vacuum and an atmosphere include: There is no extremely different portion in the configuration, the configuration is almost symmetric, and the electric field is uniform inside the vacuum vessel.
[0041]
As described above, the shield mesh and the substrate holder are configured to have a certain angle, and the diameter of the hole formed in the shield mesh is set to 2 mm or less, so that the gas exhaust capability is minimized. It is possible to obtain an apparatus that does not reduce the amount and prevents unnecessary diffusion of plasma and further reduces running cost.
[0042]
In the present embodiment, a dry etching apparatus has been described as an example, but the present invention may be applied to a plasma CVD apparatus, a sputtering apparatus, and an ashing apparatus.
[0043]
Further, in both the first and second embodiments, the case where the high frequency applied to the antenna is 100 MHz has been described, but good results can be obtained even in the range of 500 kHz or more and 300 MHz or less.
[0044]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to the plasma processing apparatus of this invention, a porous body is arrange | positioned around a board | substrate holding base, and the inside of a vacuum container is divided into the side with and without a board | substrate by this porous body, and the porous body is a board holding board. A first surface parallel to the surface on which the substrate is placed and a second surface substantially perpendicular to the first surface, so that the lower portion of the vacuum vessel can be reduced without reducing gas exhaust characteristics. It is possible to prevent the plasma from being diffused.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of a plasma processing apparatus according to a first embodiment of the present invention; FIG. 2 is a schematic diagram of a shield mesh according to the first embodiment of the present invention; FIG. Schematic diagram of shield mesh [Figure 4] Schematic diagram of conventional plasma processing apparatus [Description of reference numerals]
DESCRIPTION OF SYMBOLS 1 Vacuum container 2 Substrate 3 Substrate holder 5 Push-up mechanism 20 Gas exhaust system 21 Shield mesh 30 Gas inlet 7, 70 High frequency power supply 71 Antenna

Claims (10)

A vacuum container capable of maintaining a vacuum, a gas supply / exhaust system for supplying and exhausting gas into the vacuum container, and a substrate holding table on which a substrate to be processed in the vacuum container is mounted. And a high-frequency power supply that applies high-frequency power to an antenna disposed opposite to the substrate holding table,
A porous body is arranged around the substrate holder, and the inside of the vacuum vessel is divided into two sides by the porous body into a side where the substrate is not provided and a side where the substrate is not provided, and the porous body is provided on a surface of the substrate holder on which the substrate is placed. A plasma processing apparatus comprising a parallel first surface and a second surface substantially perpendicular to the first surface. 2. The plasma processing apparatus according to claim 1, wherein a diameter of the hole formed on the first surface is smaller than a diameter of the hole formed on the second surface. 3. The plasma processing apparatus according to claim 1, wherein a diameter of the hole formed in the first surface is 0.1 mm or more and 2 mm or less. 4. The plasma processing apparatus according to claim 1, wherein a diameter of the hole formed in the second surface is greater than 2 mm and 5 mm or less. 5. The plasma processing apparatus according to any one of claims 1 to 4, wherein a high frequency of 500 kHz or more and 300 MHz or less is applied to the antenna. The plasma processing apparatus according to any one of claims 1 to 5, wherein a discharge cover is disposed between the vacuum vessel and the porous body. A vacuum container capable of maintaining a vacuum, a gas supply / exhaust system for supplying and exhausting gas into the vacuum container, and a substrate holding table on which a substrate to be processed in the vacuum container is mounted. And a high-frequency power supply that applies high-frequency power to an antenna disposed opposite to the substrate holding table,
A porous body is disposed around the substrate holder, and the inside of the vacuum container is divided into two sides by the porous body into a side where the substrate is and a side where the substrate is not provided, and the porous body has a surface on which the substrate of the substrate holder is placed. A plasma processing apparatus, wherein the plasma processing apparatus is arranged at a certain angle. 8. The plasma processing apparatus according to claim 7, wherein when the hole axis of the porous body is projected on a plane perpendicular to the gas flow, the projected hole diameter is 0.1 mm or more and 2 mm or less. The plasma processing apparatus according to claim 7, wherein a high frequency of 500 kHz or more and 300 MHz or less is applied to the antenna. The plasma processing apparatus according to any one of claims 7 to 9, wherein a discharge cover is disposed between the vacuum vessel and the porous body.

Images