JP3897566B2 - Plasma processing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a semiconductor device, it relates to a liquid crystal display panel and solar plasma treatment how used in thin film formation process and micromachining processes, such as in the manufacture of such batteries.
[0002]
[Prior art]
In recent years, in the plasma processing technology, in order to increase the functionality of devices and reduce processing costs, efforts to achieve high accuracy, high speed, large area, and low damage have been actively conducted.
[0003]
In particular, plasma processing used for microfabrication requires processing in a clean atmosphere free of dust in order to improve device yield.
[0004]
A schematic configuration of a conventional dry etching apparatus will be described with reference to FIG. In FIG. 1, reference numeral 1 denotes a vacuum vessel for performing a dry etching process, to which a vacuum exhaust means 2 is connected and a gas introduction port 4 connected to a gas introduction means 3 for supplying an etching gas is formed. An upper antenna 5 is disposed in the upper part of the vacuum vessel 1 and is connected to a 100 MHz high frequency power source 6 for plasma generation.
[0005]
A substrate holder 8 that electrostatically attracts the substrate 7 to be processed is disposed in the lower part of the vacuum container 1. An electrode 9 is disposed on the substrate holding table 8, and a 500 kHz high frequency power source 10 for generating plasma and power sources 11 a and 11 b for electrostatic adsorption are connected. The substrate holding table 8 is provided with push-up means 12 for pushing up the substrate 7 to be processed after the processing is completed, and a drive mechanism 13 is provided.
[0006]
On one side of the vacuum vessel 1, a vacuum transfer system 15 for appropriately supplying and discharging the substrate 7 to be processed is connected to the inside of the vacuum vessel 1 through a communication opening 14. The communication opening 14 is provided with a gate valve 16 that is arbitrarily opened and closed. The gate valve 16 is provided with a conductive vacuum seal 17, which not only blocks gas leakage from the vacuum vessel 1 with the vacuum seal 17 but also makes the gate valve 16 and the vacuum vessel 1 have the same potential. It is configured as follows. Reference numeral 18 denotes an antenna cover which is installed to reduce the complexity of maintenance due to wear of the upper antenna 5 due to plasma sputtering in a short period of time and contamination such as deposits, and fixing means (not shown) so that it can be easily removed. ).
[0007]
Next, the operation of the dry etching apparatus having the above configuration will be described. First, by operating the gate valve 16, the vacuum vessel 1 and the vacuum transfer system 15 are spatially communicated via the communication opening 14. Next, the substrate 7 to be processed is carried into the vacuum container 1 by the vacuum transfer system 15, and the substrate 7 to be processed is placed on the substrate holder 8 using the push-up means 12 provided on the substrate holder 8. Electrostatic adsorption is performed by the power sources 11a and 11b for electroadsorption. Thereafter, the gate valve 16 is operated to shield the communication opening 14.
[0008]
Next, while Ar gas as an etching gas is introduced at 200 cc / min from the gas introduction port 4, the inside of the vacuum chamber 1 is regulated to 0.5 Pa, and 1 kW is supplied from the high frequency power source 10 to the substrate holder 8, and the high frequency power source 6. By applying a high frequency power of 2 kW to the upper antenna 5 from the plasma, plasma is generated in the vacuum vessel 1 and a desired dry etching process is performed.
[0009]
After the etching is finished, the operation of the high-frequency power sources 6 and 10 for plasma generation is stopped, the introduction of the reaction gas is stopped, and the substrate 7 is moved by the push-up means 12 while the vacuum exhaust means 2 is evacuated. The substrate holding table 8 is peeled off, the gate valve 16 is operated to open the communication opening 14, the substrate to be processed 7 is discharged by the vacuum transfer system 15, and the predetermined processing is completed.
[0010]
By the way, in such a plasma processing apparatus, the generation of dust is particularly noticeable when a member in contact with the discharge space is the cause. Therefore, conventionally, as disclosed in, for example, Japanese Patent Laid-Open No. 10-163180, the surface roughness of a member in contact with the discharge space is used as an index to increase the adhesion of a reaction product (hereinafter referred to as a deposit). As a result, methods for reducing dust have been proposed.
[0011]
[Problems to be solved by the invention]
However, in the dust reduction method as described above, a process called seasoning for processing a dummy wafer in an actual process is not performed on five or more dummy wafers after maintenance or replacement of components in the vacuum vessel. The present inventors have found that there is a problem that dust is not reduced.
[0012]
However, due to the recent miniaturization of device patterns, the target particle size of dust has become smaller. Especially when the target particle size is about 0.10 to 0.30 μm, further seasoning is necessary. There is a problem that the downtime (non-operating time) of the apparatus is prolonged.
[0013]
As a result of investigating the cause, the surface of the component in the vacuum vessel 1, particularly a member such as a ceramic antenna cover 18 made of quartz, alumina or the like, is used to increase the adhesion of the deposit using the surface roughness as an index. When machined to form a concavo-convex shape M as shown in FIG. 3 (b), as shown in FIG. 3 (c), cracks m generated during machining called microcracks having a width of 1 μm or less are generated. Turned out to be by. Since the microcrack m is very fragile in terms of strength, it is peeled off and diffused by slight vibration, gas flow during gas supply, and molecular sputtering by plasma. Therefore, by performing seasoning, the microcracks m are removed at an accelerated rate. This is the cause of dust having a particle size of 0.3 μm or less when the member is replaced with a new one after maintenance.
[0014]
Further, the method for controlling the surface roughness as an index has the following problems. If you want to increase the surface area in order to increase the adhesion of the depot, you should make the unevenness as sharp as possible, and increase the unevenness of the unevenness as much as possible. This further promotes the adverse effects of the microcracks m.
[0015]
In addition, ceramic-based insulator bulks are easily charged with static electricity, dust adheres to the gaps in the valleys, and cannot be completely removed simply by performing conventional depot removal cleaning using pure water or simultaneous ultrasonic cleaning. It has been found.
[0016]
Further, such a concavo-convex shape M is generally processed by sand blasting. Microscopically, as shown in FIG. 3B, the concavo-convex shape M is a repetitive concavo-convex pattern having a constant interval and a constant height difference such as a saw. The current situation is not. On the other hand, when the surface irregularities are formed in a gentle state, the surface becomes microscopically, so that the surface area is not enough to obtain a stable adhesion of the deposit.
[0017]
Further, when the surface roughness Ra = 20 μm was evaluated so as to have a certain surface area, 20 or more seasonings were required, and the surface roughness after the seasoning treatment was chemically and physically flattened by plasma. Thus, it was found that Ra = 20 μm, which is effective for the desired deposition degree, was not achieved. Therefore, in the actual processing, the deposit deposited on the antenna cover 18 is peeled off by continuous processing of about 100 non-processed substrates 7 and maintenance is forced.
[0018]
In addition, the prior art disclosed in Japanese Patent Laid-Open No. 10-163180 and others is limited to the process of attaching a depot, and there is also a problem that there is no effective method in a site or process where the depot does not adhere. .
[0019]
In view of the above-described conventional problems, and its object is to be realized the process in the clean atmosphere free from dust to provide a plasma processing how that can improve the yield of microfabricated device.
[0020]
[Means for Solving the Problems]
In the plasma processing method of the present invention, a gas is introduced into a vacuum vessel and evacuated while being maintained at a predetermined pressure, and high frequency power is applied to an antenna provided facing an electrode disposed in the vacuum vessel. In the plasma processing method for generating plasma, as an antenna cover for covering the antenna, a member made of ceramics such as quartz or alumina, having a surface with unevenness and creating a surface shape, a gold for creating the surface shape A mold is prepared, the mold is pressed against the surface of the member, heated to a high temperature and the shape is transferred, and an antenna cover having a surface shape without microcracks can be obtained . The unevenness provides a high adhesion of the deposit and does not generate dust due to the peeling of the deposit, and does not generate dust due to the peeling of the microcracks, and a clean atmosphere without dust. It can be realized the treatment in the gas can improve the yield of the microfabricated device. In particular, it can be applied to an antenna cover made of quartz, which is particularly effective.
[0022]
Further, when the surface shape of the antenna cover is created, if the buffing is performed while using a hydrofluoric acid having a concentration of 3% or less, the microcracks can be surely removed and the above effect can be obtained . This is particularly effective when the antenna cover is made of a ceramic such as alumina or quartz.
[0027]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment in which a plasma processing apparatus of the present invention is applied to a dry etching apparatus will be described with reference to FIGS. Note that the overall configuration of the dry etching apparatus and the dry etching operation thereof are basically the same as those of the conventional example described with reference to FIG. 1, and description of common components is omitted with the aid of the description. Only the structure of the main part of the present invention will be described below.
[0028]
In the present embodiment, in order to reduce the troubles during maintenance due to short-term wear of the upper antenna 5 due to plasma sputtering and contamination such as deposits, as shown in detail in FIG. A ceramic antenna cover 21 made of alumina or the like is fixed by fixing means (not shown) so that it can be easily removed.
[0029]
The antenna cover 21 has a height 22 of about 20 μm as shown in FIG. 2B on a surface 22 facing the discharge space in the vacuum vessel 1 as shown by a one-dot chain line in FIG. As shown in FIG. 2C, about 15-30 concavo-convex shapes 23 having a difference are formed in the range of about 15-30 per 1 mm, and in this embodiment, and the surface of the concavo-convex is finer 1-5 μm. An uneven shape 24 having a difference is formed. It is preferable that 5 to 30 uneven shapes having a height difference of 1 to 5 μm are formed within a range of 30 to 70 μm.
[0030]
Such concavo-convex shapes 23 and 24 are formed in a repetitive shape of concavo-convex having a constant interval and a constant height difference such as a saw. As a result, the area where deposits generated during dry etching adhere ideally increases, and the adhesion strength increases, thereby increasing the time until the deposits are deposited and peeled off. As a result, the maintenance period is extended and the non-operating time of the apparatus is shortened.
[0031]
Further, the antenna cover 21 of the present embodiment is made of ceramic such as quartz or alumina, and the concavo-convex shapes 23 and 24 on the surface thereof are formed by pressing a metal mold against the surface of the constituent member and heating it to a high temperature. It is formed by transferring. Furthermore, in this embodiment, the tops of the irregularities are made smooth by performing buffing finishing using hydrofluoric acid having a concentration of 0.5% or less. As a result, there are no microcracks that occur when machining ceramics, and no dust is generated even when seasoning is not performed when a new antenna cover 21 is replaced.
[0032]
Further, another means for forming the uneven shapes 23 and 24 will be described. The constituent members in the vacuum vessel have various shapes, and machining according to the shapes is necessary. However, the finished surface condition varies depending on the type of machining. In other words, since the degree of occurrence of microcracks is greatly different, a technique that is less susceptible to the influence is necessary.
[0033]
Therefore, after machining, a blasting process using alumina having a particle size of 100 μm or less is performed in a range where microcracks need to be removed and a necessary range of the concave and convex shapes 23 and 24, and different surface states are obtained depending on the type of machining. While homogenizing, the surface roughness was Rmax 5-15 μm. Thereafter, by performing a surface treatment using hydrofluoric acid having a concentration of 10% or more, a desired surface state can be obtained.
[0034]
By using the antenna cover 21 having the above configuration, 500 or more substrates to be processed can be continuously processed without maintenance.
[0035]
Furthermore, when performing maintenance or when exchanging the components in the vacuum vessel 1 for a new one, in the cleaning for removing deposited depots and dust, etc., before the final finishing process, a cleaning process is performed to remove static electricity, By removing dust adhered by static electricity, finally washing with pure water, drying and then assembling to the device, generation of dust after maintenance is suppressed, and the device can be smoothly shifted to normal production without seasoning .
[0036]
As described above, according to the present embodiment, even with dust having a particle size of 0.10 μm or more, dust generated from the constituent members inside the vacuum vessel 1 and generation of dust due to peeling of the deposit are suppressed. It is possible to reduce the processing time and the downtime (non-operation time) of the apparatus in a clean atmosphere without any problems.
[0037]
In the above embodiment, the following four technical means (1) In all or a part of the constituent members in the vacuum vessel, an uneven shape having a predetermined height difference is formed within a predetermined width, and the uneven surface thereof Further, a concavo-convex shape having a finer height difference is formed.
[0038]
(2) When creating the surface shape of the constituent member in the vacuum vessel, a mold is prepared, and the die is pressed against the surface of the constituent member in the vacuum vessel and heated to a high temperature to transfer the shape.
[0039]
(3) When creating the surface shape of the constituent members in the vacuum vessel, buffing is performed using hydrofluoric acid having a concentration of 3% or less in order to create a shape in which the tops of the irregularities are gentle.
[0040]
(4) When creating the surface shape of the component in the vacuum vessel, in order to form a concavo-convex shape having a predetermined height difference within the required range, and to form a finer concavo-convex shape on the surface of the concavo-convex shape, First, blast treatment is performed, and then surface treatment is performed using hydrofluoric acid having a concentration of 10% or more.
[0041]
(5) When cleaning the constituent members in the vacuum vessel, a cleaning process for removing static electricity is included, and dust adhered by static electricity is removed.
As for the above, it has been confirmed that sufficient effects can be obtained even if carried out independently. For example, instead of transferring the mold in (2), after forming irregularities by conventional machining, sandblasting with extremely fine powder, and removing microcracks by (3) hydrofluoric acid + buff polishing However, it is also possible to set conditions so as to obtain a surface shape that produces the same effect. Of course, it is needless to say that it is more preferable to carry out the above four technical means simultaneously.
[0042]
In the above embodiment, the dry etching apparatus has been described as an example, but the present invention can also be applied to a plasma CVD apparatus, a sputtering apparatus, and an ashing apparatus.
[0043]
【The invention's effect】
According to the plasma treatment how the present invention, or the surface shape of the antenna cover of the vacuum chamber as the surface treatment, by optimizing the cleaning method, dust generated from the antenna cover surface, and due to peeling of the depot The generation of dust can be suppressed, and even if the target particle size of dust becomes smaller due to miniaturization of the device pattern, it is possible to ensure the treatment in a clean atmosphere and improve the device yield and reduce the downtime of the apparatus. It can be shortened.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing a schematic configuration of an embodiment of a dry etching apparatus to which a plasma processing apparatus of the present invention is applied.
2A and 2B show an antenna cover as a constituent member in the vacuum container according to the embodiment, wherein FIG. 2A is a longitudinal sectional view showing an arrangement state, FIG. 2B is an enlarged detail view of a part A in FIG. ) Is an enlarged detail view of part B of (b).
FIGS. 3A and 3B show an antenna cover as a constituent member in a vacuum vessel in a conventional example, FIG. 3A is a longitudinal sectional view showing an arrangement state, FIG. 3B is an enlarged detail view of a portion C in FIG. FIG. 4B is an enlarged detail view of a D part in FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Vacuum container 2 Vacuum disposal means 3 Gas introduction means 5 Upper antenna 21 Antenna cover (component in a vacuum container)
23 Uneven shape 24 Uneven shape

Claims (2)

In a plasma processing method for generating plasma by applying high-frequency power to an antenna provided opposite to an electrode disposed in a vacuum container while evacuating and maintaining a predetermined pressure while introducing gas into the vacuum container As the antenna cover for covering the antenna, a die made of ceramics such as quartz or alumina, having a surface irregularity and creating the surface shape, is prepared. The plasma processing method is characterized by using a material whose shape is transferred by being pressed against the surface of the member and heated to a high temperature . In a plasma processing method for generating plasma by applying high-frequency power to an antenna provided opposite to an electrode disposed in a vacuum container while evacuating and maintaining a predetermined pressure while introducing gas into the vacuum container The antenna cover that covers the antenna is a member made of ceramics such as quartz or alumina, and has a surface with irregularities and is buffed using hydrofluoric acid with a concentration of 3% or less when creating the surface shape. It features and to pulp plasma processing method to be used those.

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