JP2006339673A - Plasma processing equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plasma processing apparatus capable of improving the yield of devices formed by microfabrication by realizing a process in a dust-free clean atmosphere. <P>SOLUTION: The plasma processing apparatus is provided with a vacuum chamber 1, an evacuation means for evacuating the vacuum chamber, a gas introducing means for introducing a gas into the vacuum chamber, an electrode for disposing an object to be processed thereon, and an antenna 5 arranged facing the electrode in the vacuum chamber 1. The antenna 5 is covered with an antenna cover 21 which is made of a ceramic and has an uneven shape in its surface. The uneven shape consists of a first uneven shape 23 having a top-to-bottom height difference of 10-30 μm and a further fine second uneven shape 24 having a top-to-bottom height difference of 1-5 μm formed on the surface of the first uneven shape 23. The first uneven shape 23 has 15-30 high-low cycles within the range of 1 mm. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a plasma processing apparatus used in a thin film forming process, a microfabrication process, and the like in the manufacture of semiconductor elements, liquid crystal display panels, solar cells and the like.

  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.

  In particular, plasma processing used for microfabrication requires processing in a clean atmosphere free of dust in order to improve device yield.

  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.

  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.

  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. ).

  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.

  Next, while Ar gas as an etching gas is introduced at 200 cc / min from the gas inlet 4, the inside of the vacuum chamber 1 is adjusted 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.

  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.

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, a method has been proposed in which the surface roughness of a member in contact with the discharge space is used as an index, the adhesion of a reaction product (hereinafter referred to as a deposit) is increased, and as a result, dust is reduced (for example, , See Patent Document 1).
JP 10-163180 A

  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.

  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.

  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.

  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.

  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.

  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.

  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.

  The prior art disclosed in Patent Document 1 and others is limited to the process of attaching a deposit, and there is a problem that there is no effective technique in a site or process where the deposit is not attached.

  In view of the above-described conventional problems, an object of the present invention is to provide a plasma processing apparatus capable of realizing processing in a clean atmosphere free of dust and improving the yield of microfabricated devices.

  The plasma processing apparatus of the present invention includes a vacuum vessel, an exhaust unit for evacuating the vacuum vessel, a gas introduction unit for introducing a gas into the vacuum vessel, an electrode for placing an object to be processed, and a vacuum vessel In a plasma processing apparatus provided with an antenna provided facing the electrode, an antenna cover for covering the antenna is provided, the antenna cover is made of ceramic, and has an uneven shape on the surface thereof. The first concavo-convex shape having a height difference of 10 to 30 μm and the second concavo-convex shape having a finer height difference of 1 to 5 μm formed on the surface of the first concavo-convex shape, and the first The concavo-convex shape of 15 to 30 is formed within a range of 1 mm.

  According to this configuration, 15 to 30 first concavo-convex shapes having a height difference of 10 to 30 μm are formed in the range of 1 mm on the surface of the antenna cover made of ceramic, and further, the surface of the first concavo-convex shape is further formed. Since the second uneven shape having a fine difference in height of 1 to 5 μm is formed, the surface has unevenness with a high density, so a stable adhesion of the deposit is obtained, and the surface unevenness High adhesion can be obtained, no dust is generated due to peeling of the deposit, and no dust is generated due to peeling of the microcracks, and processing in a clean atmosphere free of dust can be realized and the yield of the microfabricated device can be improved.

  Furthermore, when 5-30 pieces of said 2nd uneven | corrugated shape are formed in the range of 30-70 micrometers, a still higher effect can be acquired.

  According to the plasma processing apparatus of the present invention, by optimizing the surface shape of the antenna cover in the vacuum vessel as described above, generation of dust generated from the surface of the antenna cover and dust due to delamination is suppressed. Even if the target particle size of dust becomes smaller due to the miniaturization of the device pattern, it is possible to secure the treatment in a clean atmosphere to improve the device yield and reduce the downtime of the apparatus.

  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.

  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.

  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.

  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.

  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.

  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.

  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.

  By using the antenna cover 21 having the above configuration, 500 or more substrates to be processed can be continuously processed without maintenance.

  Furthermore, when performing maintenance or when exchanging the components in the vacuum vessel 1 with new ones, in the cleaning for removing attached 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 .

  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.

In the above embodiment, the following five technical means, namely, (1) In the antenna cover in the vacuum vessel, an uneven shape having a predetermined height difference is formed within a predetermined width range, and the uneven surface is further finer. (2) When creating the surface shape of the antenna cover in the vacuum container, prepare a mold and press the mold against the surface of the component in the vacuum container. Heat and transfer the shape (3) When creating the surface shape of the antenna cover in the vacuum vessel, buff polishing is performed using hydrofluoric acid with a concentration of 3% or less in order to create a shape with a gentle top and bottom of the unevenness. (4) When creating the surface shape of the antenna cover in the vacuum vessel, form a concavo-convex shape having a predetermined height difference within a required range, and form a finer concavo-convex shape on the surface of the concavo-convex shape. For this purpose, first, a blast treatment is performed, and then a surface treatment is performed using hydrofluoric acid having a concentration of 10% or more. (5) A cleaning process is included to remove static electricity when cleaning the components in the vacuum vessel. It has been confirmed that sufficient effects can be obtained even if each of the five technical means for removing the stuck dust is 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 implement the above four technical means simultaneously.

  In the above embodiment, the dry etching apparatus has been described as an example. However, the present invention can also be applied to a plasma CVD apparatus, a sputtering apparatus, and an ashing apparatus.

  By optimizing the surface shape of the antenna cover in the vacuum vessel, the present invention can suppress the generation of dust generated from the surface of the antenna cover and the dust due to peeling of the deposit. Even when the target particle size of dust is smaller, it is possible to improve the device yield and reduce the downtime of the device by ensuring the treatment in a clean atmosphere. Useful for processing equipment.

It is a longitudinal cross-sectional view which shows schematic structure of one Embodiment of the dry etching apparatus to which the plasma processing apparatus of this invention is applied. The antenna cover in the vacuum vessel in the same embodiment is shown, (a) is a longitudinal sectional view showing the arrangement state, (b) is an enlarged view of the A part of (a), (c) is a B part of (b) FIG. The antenna cover in the vacuum vessel in a prior art example is shown, (a) is a longitudinal cross-sectional view which shows the arrangement | positioning state, (b) is the C section enlarged detail drawing of (a), (c) is D section enlarged of (b). FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vacuum container 2 Vacuum disposal means 3 Gas introduction means 5 Upper antenna 7 Substrate 8 Substrate holding base 9 Electrode 21 Antenna cover 23 Uneven shape (first uneven shape)
24 Uneven shape (second uneven shape)

Claims (2)

A vacuum vessel, an exhaust means for evacuating the inside of the vacuum vessel, a gas introduction means for introducing a gas into the vacuum vessel, an electrode for placing an object to be processed, and the electrode in the vacuum vessel facing the electrode In a plasma processing apparatus equipped with an antenna,
An antenna cover for covering the antenna is provided, and the antenna cover is made of ceramic and has a concavo-convex shape on a surface thereof. The concavo-convex shape includes a first concavo-convex shape having a height difference of 10 to 30 μm and the first concavo-convex shape. It is composed of a second uneven shape having a fine difference in height of 1 to 5 μm formed on the surface of the uneven shape, and 15 to 30 of the first uneven shapes are formed within a range of 1 mm. A plasma processing apparatus. The plasma processing apparatus according to claim 1, wherein 5 to 30 second uneven shapes are formed in a range of 30 to 70 μm.

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