JPH1167494A - Plasma treatment equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress heat generation in the inside of a chamber caused by chemical reactions and ion impact by plasma and eliminate causes of damages of an O-ring made of fluoro-rubber and used for a vacuum sealing part of an insulating material, leakage, generation of foreign substances such as fluorine base substances even in the ease a high frequency antenna is installed in outside air through an insulating material such as quartz in relation to plasma in the treatment chamber. SOLUTION: In this plasma treatment equipment provided with a high frequency antenna 12 installed in the outer circumference of a cylindrical insulating tube 8, a circular tube-like metal member 15 having slits cut as to cross the antenna is installed in the further outside of the high frequency antenna 12. Air in the part of the antenna 12 surrounded with the circular tube-like member and an insulating tube 8 is sent to the upper part and the temperature of the air is adjusted by a heated or cooled radiator and then, the air is sent to the outside of the circular tube-like member having slits to be blown out to the antenna 12 and the insulating tube 8 through the slits, so that the air in the discharge part can be circulated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma processing apparatus suitable for processing such as etching and film formation in the production of semiconductors, substrates for liquid crystal displays, and the like.

[0002]

2. Description of the Related Art With the increase in the degree of integration of semiconductor elements, the increase in the diameter of semiconductor wafers, and the increase in the area of liquid crystal displays, the demands placed on these processing apparatuses have become increasingly severe. Plasma etching equipment, plasma CVD equipment,
The situation is the same in a plasma processing apparatus such as a plasma ashing apparatus, in which the plasma density is increased to improve the throughput, and the area of the workpiece is increased.
Cleaning is an important issue. Currently, the plasma sources used in these devices include:
Plasma sources such as high frequency capacitively coupled plasma sources, microwave ECR plasma sources, and high frequency inductively coupled plasma sources
Taking advantage of this feature, they are used for various processing processes. Among the plasma processing apparatuses including the three plasma sources described above, a high-frequency inductively coupled plasma processing apparatus that has begun to be rapidly used in recent years. The inductively-coupled plasma processing apparatus is, for example, an apparatus as disclosed in Japanese Patent Application Laid-Open No. 2-235332, which is disposed outside the processing chamber via an insulating material such as quartz which is a part of the chamber.
Generally, a high-frequency antenna shaped like a loop, coil, or helix is
This is a plasma apparatus of a type that supplies high-frequency power of 1 Hz and supplies energy to a process gas introduced into a processing chamber by an induction magnetic field formed by an antenna to generate and maintain plasma. In such a device, an induced current is generated in the plasma, and in terms of an electric circuit, the plasma is inductively coupled with the high-frequency antenna (in terms of an electric circuit, the antenna is a primary coil, and the current in the plasma is a secondary coil. It is considered as an inductively coupled plasma processing apparatus. The advantage of the inductively coupled plasma processing system is that it can generate relatively high-density plasma of 1E11 to 1E12 (cm-3) with a simple and inexpensive configuration consisting of a simple antenna and high-frequency power supply, and can easily generate large-area plasma. It can be generated, the plasma is stable because it has no mode, the inside of the processing chamber is simple, the maintenance is easy, and the amount of foreign matter flying on the processing object during the processing can be reduced.

In the inductively coupled plasma processing apparatus disclosed in Japanese Patent Application Laid-Open No. 2-235332, a high-frequency antenna is disposed on the atmosphere side with respect to plasma in a processing chamber via an insulating material such as quartz. The insulating material is heated by ion bombardment or chemical reaction due to plasma inside the chamber, and the temperature rises if discharge is continued without taking any measures. Such a rise in temperature may damage an O-ring such as a fluorine rubber used for a vacuum seal portion of the insulating material, causing a leak or a fluorine-based foreign substance caused by the O-ring. In addition, in the etching process, since the temperature of the chamber strongly affects the chemical composition of the gas being processed,
It is necessary to keep the temperature of the chamber constant including this insulating material. Therefore, when starting the operation, the chamber is warmed up, and when the processing object is continuously subjected to plasma processing, heat is generated during the processing. is there. In any case, even when processing is performed continuously, it is essential to keep the chamber at a constant temperature in each processing. Also, since the plasma processing apparatus is usually installed in a clean room, if the flow in the clean room is disturbed,
Roll up small garbage. Therefore, even when cooling the plasma discharge unit, it is necessary to prevent the flow of air generated by the fan or the like from causing turbulence to the outside.

[0004]

As described above, according to the present invention, the temperature of an insulating member in the vicinity of a processing chamber, particularly, an antenna where heating is remarkable is made constant from before processing to the end of processing to protect an O-ring seal portion and the like. It is another object of the present invention to provide a plasma processing apparatus capable of performing stable plasma processing by making the gas composition in the chamber constant even during continuous processing. It is another object of the present invention to provide a plasma processing apparatus which has high reliability and generates less dust during processing.

[0005]

The above object of the present invention is achieved by circulating air in an induction antenna section by a suitable structure. Specifically, in an induction plasma device in which a high-frequency antenna is arranged around a cylindrical insulating tube,
A circular tubular member with a slit cut across the antenna is installed further outside the high-frequency antenna, and the air in the portion of the antenna surrounded by the tubular member and the insulating tube is sent upward by a fan or the like, and heated. Alternatively, after adjusting the temperature of this air by a radiator to be cooled, it is sent to the outside of the cylindrical member with the slit, and from the slit,
Blow out to antenna and insulating tube. In an induction plasma processing system using a flat insulating plate and a loop or spiral high-frequency antenna placed above it, a plate with a radial slit is placed above the insulating plate and the antenna, and again a fan is used. The air in the space around the antenna may be sucked from the outside, the temperature may be adjusted, and the air may be blown out from the slit. Alternatively, in this type of device, it may be better to suck air out of the slit in the opposite direction in consideration of the fact that heat tends to go upward due to natural convection. With such a structure, the above-mentioned problem is solved and the air is circulated inside, so that there is no danger that the flow of air in the clean room is disturbed and dust is generated outside the device.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is not limited to the field of semiconductor device manufacturing, but can be applied to liquid crystal display manufacturing, film formation of various materials, and surface treatment. Here, an embodiment will be described mainly by taking a plasma ashing processing apparatus for manufacturing a semiconductor device as an example.

FIG. 1 shows an embodiment of the present invention. The processing chamber 1 in the figure is a vacuum container made of aluminum or stainless steel. The processing chamber 1 includes an exhaust unit 2 and
A transfer system 4 for loading and unloading a semiconductor wafer 3 as an object to be processed is provided. In the processing chamber 1, a stage 5 for mounting a semiconductor wafer is provided. The wafer carried into the processing chamber from the transfer system 4 is
It is carried on the stage by the push rod 6. The stage is provided with a heater 7 for heating the temperature of the wafer during plasma processing to about 200 ° C.

On the other hand, on the upper part of the processing chamber, a discharge part comprising an insulating tube 8, a gas introduction flange 9 and the like is installed via vacuum seals 10 and 11, and around the discharge part, a conductive metal such as copper The antenna 12 of one loop or several loops made by the above is installed. The antenna 12 has
Generally, a high-frequency power source 14 is connected via an impedance matching device 13 having two built-in variable capacitors.
The frequency of the high-frequency power supply is not particularly limited, but is generally several hundred kHz to several hundred MHz, which is a commercial frequency.
3.56MHz is the most common. Outside the antenna 12, a cylindrical metal member 15 having a slit in a direction crossing the antenna, that is, in FIG. FIG. 2 is an exploded perspective view of this member. The slits 16 are provided to blow out the temperature-controlled air and to prevent induction loss in this member. That is,
The plasma is induction-heated by the high-frequency power applied to the antenna, but without this slit, an induction current also flows through this cylindrical metal member. As a result, the cylindrical member is heated and the power supplied to the plasma is reduced, so that the density of the plasma is reduced. By providing the slit as shown in FIG. 2, a current flowing through this member along the antenna can be prevented, so that the problem of heating this member and lowering the plasma density is solved. Also, 1
Since the wavelength of the high frequency of 3.56 MHz is about 22 m, the length of the slit is considered to be sufficiently shorter than the wavelength, so that the cylindrical metal member can prevent electromagnetic waves leaking to the outside. Further, the slit only needs to cross the antenna, and does not necessarily have to be in the vertical direction. It may be oblique as shown in FIG. Alternatively, a combination of at least one slit for preventing induced current and a small hole 17 for air as shown in FIG. 4 may be used. The entire discharge unit is covered by the cover 18. The space around the antenna is an almost closed space except for the upper part by an insulating tube, a chamber, and a cylindrical member. At the upper part, a fan 19 for sucking out the air in this part is installed. The air 20 blown out by the fan is sent to a radiator 21 for temperature adjustment to a predetermined temperature. In the ashing process, the heating of the insulating tube is remarkable, and since the temperature of the chamber is not so important for the ashing process, almost only cooling may be considered. Therefore, the air is cooled in this part and sent to the space 22 between the cover and the cylindrical member. In the case of an etching apparatus, physicochemical surface reactions on the inner surface of the chamber affect the gas composition inside, and conversely, heating may be required. From the space 22, air blows through the slits, effectively cooling the antenna and the insulation.

The same effect can be obtained by attaching a temperature control mechanism to a cylindrical member instead of providing an air temperature control mechanism at the top. Specifically, as shown in FIG. 5, this is realized by putting a cooling pipe 31 and a heater 32 on the surface of a cylindrical member. In addition, by providing the surface of the member with irregularities, the heat transfer surface for circulating air is increased, and the heating and cooling efficiency of the air is increased. Further, as shown in FIG. 6, by providing the surface of the insulating cylinder with irregularities, the heat transfer surface can be similarly enlarged. In general, the insulating cylinder is often made of quartz, but by using alumina ceramic having good thermal conductivity, the temperature distribution in the insulating cylinder can be reduced and reliability can be increased. Also, since the alumina component is made by a mold, the production cost does not increase so much by making the surface uneven. Alumina ceramics are opaque, so that compared to using quartz, there are problems such as not being able to see the state of plasma during discharge and not being able to detect the light for determining the end point. The problem is solved by providing the upper part with a window 33 made by.

FIG. 7 shows another embodiment. In this embodiment, a fan is installed outside the cylindrical member. When the main purpose is to cool the insulating tube, by blowing air from a fan directly to the insulating tube, the flow velocity of the air hitting the insulating tube is greatly and effectively cooled. Cooling can be particularly effectively performed when used in combination with an insulating cylinder having an uneven surface as shown in FIG. However, there is also a disadvantage that the occupation area of the entire discharge unit is increased by installing the fan horizontally.

FIG. 8 shows an example in which the present invention is applied to a plasma processing apparatus having an induction antenna arranged in a plane. In this case, as shown in FIG. 9, a flat metal member 42 cut with a radial slit 41 is placed above the insulating plate 43 and the loop or spiral antenna 44, and a fan is placed above the antenna. Since the air heated by the antenna and the insulating plate heated by the plasma easily goes to the top due to natural convection, the fan exhausts the air around the antenna, contrary to the embodiment shown in FIG. In some cases, the cooling efficiency is higher. The exhausted air returns from the outer periphery after being cooled.

Although the embodiments of the present invention have been described mainly by taking a plasma ashing apparatus for manufacturing semiconductor devices as an example, the present invention is not limited to a plasma ashing apparatus, but includes a plasma etching apparatus and a plasma CVD apparatus.
The present invention can be applied to apparatuses and the like, and can be applied not only to processing of semiconductor devices, but also to processing of liquid crystal display substrates and other general surface treatments.

[0013]

As described above, according to the present invention, the temperature rise of the insulating material heated by the ion bombardment or the chemical reaction due to the plasma inside the chamber is suppressed, and the vacuum sealing of the insulating material is performed. Parts are protected, and the reliability of the device is improved. Further, the fluorine-based foreign matter caused by the breakage of the O-ring is reduced, and the operation rate of the apparatus is improved. In addition, by maintaining the temperature of the chamber constant, a constant plasma process can be realized even when performing a continuous process. As a result, plasma processing performance as a whole is improved, and high-throughput ashing processing, fine etching processing, high-quality film formation processing, surface processing, and the like can be performed.

[Brief description of the drawings]

FIG. 1 is a diagram showing one embodiment of the present invention.

FIG. 2 is an exploded perspective view of a cylindrical metal member.

FIG. 3 is a view showing a slit pattern of a cylindrical metal member.

FIG. 4 is a view showing a pattern of slits and holes of a cylindrical metal member.

FIG. 5 is a diagram showing one embodiment of the present invention.

FIG. 6 is a diagram showing an embodiment of the present invention.

FIG. 7 is a diagram showing one embodiment of the present invention.

FIG. 8 is a diagram showing one embodiment of the present invention.

FIG. 9 is a view showing a pattern of slits of a flat metal member.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Processing chamber, 2 ... Vacuum exhaust means, 3 ... Semiconductor wafer, 4 ... Transport system, 5 ... Stage, 6 ... Push rod, 7 ... Heater, 8 ... Insulation tube, 9 ... Gas introduction flange, 10 ... Vacuum seal, 11: vacuum seal, 12: antenna. 13: impedance matching device, 14: high frequency power supply, 15: cylindrical metal member, 16: slit, 17 ...
Small holes for air, 18 ... cover, 19 ... fan, 20 ... air, 21 ... radiator, 22 ... space between cover and cylindrical member, 31 ... cooling pipe, 32 ... heater, 33 ... window,
41: radial slit, 42: flat metal member, 43
... insulating plate, 44 ... loop or spiral antenna, 4
5 ... gas introduction part.

Continuation of the front page (51) Int.Cl. ⁶ Identification code FI H01L 21/31 H01L 21/302 B (72) Inventor Masashi Arai 502 Kandate-cho, Tsuchiura-shi, Ibaraki Pref. Inventor Takeshi Yoshioka 794, Higashi Toyoi, Hitachi, Ltd.

Claims (6)

[Claims] 1. A plasma processing apparatus comprising a processing chamber, a gas introducing means, an exhaust means, and an induction antenna for plasma generation connected to a high-frequency power supply, a discharge tube formed of an insulating material, or a vicinity of a flat plate or a dome. An inductive antenna is disposed on the antenna, and a surrounding member that covers the outside or the top of the antenna, a cover that covers the member, and air in a portion surrounded by the discharge tube and the member is circulated through a slit or a hole provided in the member. A plasma processing apparatus wherein the temperature of the discharge tube is adjusted by causing the temperature to be adjusted. 2. An inductive antenna for plasma generation connected to a processing chamber, gas introduction means, exhaust means and a high frequency power supply, and a discharge tube formed of alumina ceramic, one end of the discharge tube having a gas introduction port. A plasma processing apparatus characterized by being closed by a flange having a window made of a transparent material. 3. A plasma processing apparatus comprising a processing chamber, a gas introducing means, an exhaust means, and an induction antenna for plasma generation connected to a high-frequency power supply, the surface of a plate, a dome or a tube made of an insulating material being uneven. A plasma processing apparatus comprising: 4. The plasma processing apparatus according to claim 1, wherein an air temperature adjusting means is provided in an air circulation section. 5. The plasma processing apparatus according to claim 1, wherein a temperature adjusting means is provided on said enclosure member. 6. The plasma processing apparatus according to claim 1, wherein the surface of the enclosure member is provided with irregularities.