JP2012004108A - Plasma processing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize the power transmission on a surface of an upper electrode with high reliability when the power to be supplied to the upper electrode has high frequency.SOLUTION: In a plasma processing apparatus having a chamber in which an upper electrode and a lower electrode are provided to face each other, the atmosphere (in a coaxial tube) between the upper electrode and a chamber wall covering the upper electrode is set to an inert gas atmosphere of positive pressure and the upper electrode and the chamber wall covering the upper electrode are set to have a coaxial shape. The upper electrode is preferably connected electrically to a matching box, and the inert gas atmosphere is preferably cooled.

Description

  The present invention relates to a plasma processing apparatus.

  In recent years, semiconductor devices have become indispensable for human life. Here, the semiconductor device is a device including at least one transistor, and all electronic devices are included in the semiconductor device.

  An element such as a transistor included in such a semiconductor device is formed of a thin film. Plasma treatment is indispensable for forming such a thin film. Here, plasma CVD is also included in the plasma treatment. For example, when a thin film transistor is formed over a glass substrate, a dense film can be formed at a low temperature by applying a plasma CVD method for forming a gate insulating film.

  Since it is used when manufacturing an element such as a transistor included in a semiconductor device in this way, various technical developments have been advanced for plasma processing apparatuses.

  Note that the plasma processing apparatus includes a matching unit electrically connected to the upper electrode, and a variable capacitor (also referred to as a variable capacitor or a variable capacitor) is provided in the matching unit. Such a variable capacitor includes a vacuum variable capacitor provided in a vacuum environment and an air variable capacitor exposed to the atmosphere.

JP 2002-313785 A JP 2003-042169 A

  An object of one embodiment of the present invention is to provide a plasma processing apparatus with higher reliability than before. Note that this plasma processing apparatus has at least one of the following problems, and by solving at least one of the following problems, a highly reliable plasma processing apparatus can be obtained.

  An object of the plasma processing apparatus of one embodiment of the present invention is not to cause corrosion of a portion that has been corroded by moisture or the like contained in the air in the conventional plasma processing apparatus. One object of the present invention is to reduce the maintenance frequency and increase the mean time between failure (MTBF) by not causing corrosion in this way.

  The plasma processing apparatus of one embodiment of the present invention controls the atmosphere to which the surface of the upper electrode is exposed without exposing the surface of the upper electrode that has been exposed to the atmosphere in the conventional plasma processing apparatus to the atmosphere. One object is to control the dielectric constant of the atmosphere to which the surface of the upper electrode is exposed and to stabilize the propagation of power on the surface of the upper electrode when the power supplied to the upper electrode is high frequency. .

  Another object of the plasma processing apparatus of one embodiment of the present invention is to prevent air components from being mixed into a chamber when the chamber leaks.

  The plasma processing apparatus of one embodiment of the present invention has a stable operation even when an inexpensive air variable capacitor is used as a variable capacitor provided in a matching unit electrically connected to the upper electrode. One of the issues is to be able to

  In the plasma processing apparatus of one embodiment of the present invention, the upper electrode may be provided with a heater. In the plasma processing apparatus in which the upper electrode is provided with a heater, the conductor plate and the matching unit connected to the upper electrode are overheated. One of the issues is to prevent this.

  An object of the plasma processing apparatus of one embodiment of the present invention is to improve the transmission efficiency of the upper electrode as compared with a conventional plasma processing apparatus.

  One embodiment of the present invention is a plasma processing apparatus in which an upper electrode and a lower electrode are opposed to each other in a chamber, and an atmosphere between the upper electrode and a chamber wall covering the upper electrode (in a coaxial tube) is A plasma processing apparatus characterized by being in a positive pressure inert gas atmosphere.

  One embodiment of the present invention is a plasma processing apparatus in which an upper electrode and a lower electrode are opposed to each other in a chamber, and an atmosphere between the upper electrode and the chamber wall covering the upper electrode is free from positive pressure. The plasma processing apparatus is characterized in that it is an active gas atmosphere, and the upper electrode and the chamber wall covering the upper electrode are coaxial.

  In the plasma processing apparatus according to one aspect of the present invention, preferably, a matching unit is electrically connected to the upper electrode, and the matching unit is the same as between the upper electrode and a chamber wall covering the upper electrode. It is provided in the atmosphere.

  In the plasma processing apparatus which is one embodiment of the present invention, the upper electrode may be provided with a heater. And it is good also as a structure which can control the temperature of the said upper electrode by introduce | transducing the cooled inert gas between the chamber walls which cover the said upper electrode and the said upper electrode. Here, the temperature at the time of introduction of the cooled inert gas is preferably from −200 ° C. to room temperature.

  In the present specification, the “positive pressure” preferably refers to an atmospheric pressure higher than the atmospheric pressure, but is not limited thereto, and may be at least higher than the atmospheric pressure in the processing chamber.

  In this specification, the chamber inner wall refers to the inner surface of the chamber wall, and the chamber outer wall refers to the outer surface of the chamber wall.

  According to one embodiment of the present invention, a highly reliable plasma processing apparatus can be obtained.

  According to one embodiment of the present invention, parts of a plasma processing apparatus can be prevented from being corroded, maintenance frequency can be reduced, and a mean time between failure (MTBF) can be increased.

  According to one embodiment of the present invention, stable power propagation is possible even when power supplied to the upper electrode is high-frequency.

  According to one embodiment of the present invention, entry of atmospheric components into a chamber can be prevented when a leak occurs in the chamber.

  According to one embodiment of the present invention, even when an inexpensive air variable capacitor is used as a variable capacitor provided in a matching unit that is electrically connected to the upper electrode, the operation can be stabilized.

  According to one embodiment of the present invention, an upper electrode can be prevented from being overheated even in a plasma processing apparatus in which a heater is provided in the upper electrode.

  According to one embodiment of the present invention, the transmission efficiency of the upper electrode can be improved.

FIG. 6 illustrates an example of a plasma processing apparatus which is one embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following description, and it will be easily understood by those skilled in the art that modes and details can be variously changed without departing from the spirit and scope of the present invention. Therefore, the present invention should not be construed as being limited to the description of the embodiments below.

  1A and 1B are diagrams schematically illustrating a plasma processing apparatus which is one embodiment of the present invention.

  The plasma processing apparatus shown in FIGS. 1A and 1B has a first space 140 and a second space 142 in a chamber, and the first space 140 includes an upper electrode 100 facing the surface and the first electrode 140. The lower electrode 102 is provided, and an insulator 106 is provided between the side surface of the upper electrode 100 and the chamber wall 104 so that the atmospheres of the first space 140 and the second space 142 are different from each other. Are connected to the first supply pipe 110 connected to the processing gas supply source 108 and the exhaust pipe 114 connected to the exhaust means 112. In the second space 142, the upper electrode 100 is connected to the conductor plate 116. The second space 142 is connected to the inert gas supply source 124 via the second supply pipe 122. The second space 142 is maintained at a positive pressure. Matching device 120 is electrically connected to AC power supply 126, and lower electrode 102 is grounded. However, the lower electrode 102 is not necessarily grounded.

  As shown in FIG. 1A, the upper electrode 100 and the chamber wall 104 covering the upper electrode 100 are preferably coaxial. Transmission efficiency can be increased by using a coaxial shape.

  Further, as shown in FIGS. 1A and 1B, a matching unit 120 is connected to the upper electrode 100, the matching unit 120 includes a variable capacitor 130, and the atmosphere in the matching unit 120 is the second space. The same atmosphere as 142 is preferable. As described above, when the atmosphere in the matching unit 120 is the same as that of the second space 142, even if an air variable capacitor is used, a stable operation can be performed as in the case of a vacuum variable capacitor.

  As shown in FIG. 1A, impedance can be reduced by forming the upper electrode 100 and the chamber wall 104 in a coaxial shape (coaxial tube 128).

  Here, when the diameter of the upper electrode 100 is d, the inner diameter of the chamber wall 104 is D, and the relative dielectric constant of the atmosphere between the upper electrode 100 and the chamber wall 104 covering the upper electrode 100 is ε, the impedance Z is expressed by the equation: It is represented by (1).

  According to the above formula (1), the impedance Z can be reduced by increasing the relative dielectric constant ε. According to one embodiment of the present invention, since the atmosphere in the second space 142 (between the upper electrode 100 and the chamber wall 104 covering the upper electrode 100) can be selected, the relative permittivity ε is increased and the impedance Z is increased. Can be reduced. For example, when the atmosphere of the second space 142 (between the upper electrode 100 and the chamber wall 104 covering the upper electrode 100) is a nitrogen atmosphere, the relative dielectric constant ε = 5.47 when the temperature in the atmosphere is 20 ° C. Become. Alternatively, when the atmosphere of the second space 142 (between the upper electrode 100 and the chamber wall 104 covering the upper electrode 100) is an argon atmosphere, the relative dielectric constant ε = 5.17 when the temperature in the atmosphere is 20 ° C. Become.

  The upper electrode 100 includes a first portion having a plane parallel to the lower electrode 102 and a second portion extending in a direction perpendicular to the lower electrode 102. When the voltage applied to the upper electrode 100 is a high frequency, as shown in FIG. 1 (B), a chamfer is applied to a portion to be a connection portion between the first portion and the second portion. It is preferable.

  As shown in FIG. 1, the upper electrode 100 may be provided with a heater 132. A heater having a structure in which a heating wire is provided in the groove of the heater block provided with the groove may be used. Further, the lower electrode 102 may be provided with a heater 134.

  In addition, when the upper electrode 100 is provided with a heater, it is particularly preferable to introduce a cooled inert gas into the coaxial tube 128. At this time, first, the inert gas cooled in the matching unit 120 is introduced. It is preferable to introduce an inert gas that is introduced and cooled so that the gas reaches the first portion of the upper electrode 100 through the conductor plate 116 and the second portion of the upper electrode 100. That is, it is preferable to cool from the portion where the effect by cooling is the greatest.

  Then, according to one aspect of the present invention, the upper electrode 100 is disposed in the coaxial tube 128 as shown in FIG. 1 and the path of the inert gas is not obstructed, so that the inert gas can be flowed well. Therefore, in the second portion of the upper electrode 100, the uniformity of the temperature distribution at the same height is increased, and the propagation of power on the surface of the upper electrode when the power supplied to the upper electrode is high frequency is further stabilized. can do. This point can be said to be a synergistic effect by forming the upper electrode in a coaxial shape and arranging the upper electrode in the coaxial tube.

  As described above, according to one embodiment of the present invention, the reliability of a plasma processing apparatus can be increased.

100 Upper electrode 102 Lower electrode 104 Chamber wall 106 Insulator 108 Processing gas supply source 110 First supply pipe 112 Exhaust means 114 Exhaust pipe 116 Conductor plate 120 Matching device 122 Second supply pipe 124 Inert gas supply source 126 AC Power supply 128 Coaxial tube 130 Variable condenser 132 Heater 134 Heater 140 First space 142 Second space

Claims (3)

A plasma processing apparatus provided in a chamber with an upper electrode and a lower electrode facing each other,
The atmosphere between the upper electrode and the chamber wall covering the upper electrode is a positive pressure inert gas atmosphere,
The plasma processing apparatus, wherein the upper electrode and the chamber wall covering the upper electrode have a coaxial shape. In claim 1,
A matching device is electrically connected to the upper electrode,
The plasma processing apparatus, wherein the matching unit is provided in the same atmosphere as between the upper electrode and a chamber wall covering the upper electrode. In claim 1 or claim 2,
The upper electrode is equipped with a heater,
The plasma processing apparatus, wherein an atmosphere between the upper electrode and a chamber wall covering the upper electrode is a cooled inert gas atmosphere.

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