JP5822133B2 - Mask member of inductively coupled plasma processing apparatus - Google Patents

Description

  The present invention relates to a mask member for an inductively coupled plasma processing apparatus.

A sputter etching method is conventionally known as a method for finely processing the surface of a workpiece. In this method, a processing object in which a mask having a processing pattern is formed on a processing surface is accommodated in an airtight processing chamber, and a processing gas (Ar, Cl _2, etc.) is stored in the processing chamber while maintaining the processing chamber at a low pressure. And generating a high-frequency electromagnetic field in the processing chamber to convert the processing gas into plasma. By accelerating the ions contained in the plasma with a bias voltage and colliding with the workpiece surface of the workpiece, the unmasked portion of the workpiece surface is scraped off.

  An inductively coupled plasma (ICP) processing apparatus is known as one of apparatuses for performing the above processing. An ICP processing apparatus generally includes a window serving as a power introduction port for supplying high-frequency power into a processing chamber, a coil electrode disposed outside the window, and a high-frequency power source for applying a high-frequency voltage to the coil electrode. It has. The window is generally made of a dielectric material such as quartz and is called a dielectric window.

  In microfabrication using an ICP processing apparatus, a conductor thin film made of a metal (for example, Pt, Ir, Ni) or a metal oxide (for example, iridium oxide, tin oxide, etc.) is often used as an object to be processed. When many such metal objects are processed over a long period of time, the metal sputtered by the plasma ions and scattered from the object gradually adheres to the surface of the dielectric window, and forms a conductive film there. When a conductive film is formed on the surface of the dielectric window in this way, an induced current is induced in the conductive film by the magnetic field of the high frequency electromagnetic field generated by the coil electrode, and high frequency power is consumed by this induced current. Therefore, the supply of high frequency power into the processing chamber is hindered. In the case of an ICP processing apparatus, the induced current tends to flow in a direction substantially along the winding of the coil electrode. Therefore, in the conventional ICP processing apparatus, the shape of the conductive film formed on the surface of the dielectric window is such that the induced current flow induced by the high-frequency magnetic field is interrupted halfway. A plastic mask member is mounted on the inner surface of the dielectric window (the surface facing the processing chamber). For example, when mounted on a circular dielectric window, the mask member is formed by forming a linear slit extending radially from the center of a disk-shaped member having the same size as the dielectric window. (See Patent Document 1).

JP 2001-254188 JP

By the way, when an object has a hole, a groove, or the like, a large stress is concentrated on the portion. In the mask member having a linear slit as described above, stress concentrates at both ends of the slit, so when a force is applied to the mask member when the mask member is attached or detached for cleaning or replacement of the mask member, Cracks occur at both ends of the slit. Such a crack occurs in the direction of extending the slit.
The conventional mask member is provided with a pair of slits so as to face each other across the center, and the other slit is positioned on one extension line of these slits. At the ends of the pair of slits facing each other across the center of the mask member, the cracks are generated in the same direction, so that the cracks are likely to occur, and when cracks occur at the ends of the slits, these cracks face each other. It progresses toward the end of the slit to be bonded, and the two are combined to cause damage to the mask member.

  The present invention has been made to solve such problems, and the object of the present invention is to prevent the high-frequency supply from being hindered by the conductive film of metal atoms formed on the surface of the dielectric window. It is intended to improve the strength of a mask member of an inductively coupled plasma processing apparatus having a plurality of linear slits.

In order to solve the above problems, the present invention includes a processing chamber in which a workpiece containing metal atoms is stored, and a plate-like shape provided in the processing chamber to introduce high-frequency power into the processing chamber. A mask member attached to a surface of the dielectric window facing the processing chamber of an inductively coupled plasma processing apparatus comprising a dielectric window and a coil electrode disposed behind the dielectric window. ,
A conductive film formed on the surface of the dielectric window due to metal atoms scattered from the workpiece during plasma processing adheres to the conductive film by the action of a high-frequency magnetic field generated by the coil electrode. A plurality of linear slits for adhering the metal atoms only to a part of the dielectric window so as to be a shape that interrupts the flow of current induced in the conductive film halfway,
None of the slits is located on the same straight line as the other slits.

  Here, “not on the same straight line” means that the center line in the width direction of one slit and the center line in the width direction of another slit do not overlap. Such a configuration can be realized, for example, by arranging the plurality of linear slits in a radial spiral shape.

  In the mask member, stress concentrates on both ends of the plurality of slits, but since none of the slits is located on the same straight line as the other slits, the direction of the crack generated at the end of one slit is different from the other. It does not coincide with the direction of the crack generated at the end of the slit. For this reason, it can suppress that a crack generate | occur | produces in the edge part of a slit. In addition, even if a crack occurs, it is difficult for the crack to be combined with a crack generated at the end of another slit, so that the mask member can be prevented from being greatly damaged.

  As described above, since the mask member of the ICP processing apparatus according to the present invention is not easily cracked even when a force is applied, it can be prevented from being damaged during replacement or cleaning.

1 is a schematic configuration diagram of an ICP processing apparatus according to Embodiment 1 of the present invention. (A) is the figure which looked at the mask member supported by the mask support component from the bottom, (B) is sectional drawing in the IIB-IIB line | wire of (A). The figure which looked at the mask member concerning Example 2 of the present invention from the bottom. The figure which looked at the mask member which concerns on Example 3 of this invention from the bottom.

  Several embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a schematic configuration diagram of an ICP processing apparatus. The ICP processing apparatus 1 has an airtight processing chamber 20 for storing a sample 10 made of metal or metal oxide. A processing gas passage 21 is connected to the upper portion of the processing chamber 20, and a gas for plasma etching processing is supplied from the processing gas supply unit 22 into the processing chamber 20 through the processing gas passage 21. The pressure inside the processing chamber 20 is controlled to a low pressure by a pressure control mechanism including a rotary pump 31, a turbo molecular pump 32, a valve 33 and a pressure controller 34.

  A lower electrode 23 for placing the sample 10 is provided at the bottom of the processing chamber 20. The lower electrode 23 is connected to a first radio frequency (RF) generator 36 via a first matching circuit 35. The first RF generator 36 applies a bias voltage to the lower electrode 23 for accelerating plasma ions generated in the processing chamber 20 toward the sample 10.

  A circular window member receiving portion 202 having an opening is provided on the upper wall surface (ceiling) 201 of the processing chamber 20, and a disk-shaped window member 25 made of a dielectric is disposed here. The inner surface of the window member 25 is concealed by a discard plate 27 (see FIG. 2B), and a mask member 50 is mounted on the lower surface of the discard plate 27. The whole of the discarded plate 27 and the window material 25 corresponds to the dielectric window of the present invention. On the other hand, a spiral coil electrode 26 is disposed on the upper surface of the window member 25. The coil electrode 26 is connected to a second RF generator 38 via a second matching circuit 37. The second RF generator 38 applies a high-frequency voltage for generating a high-frequency magnetic field from the coil electrode 26 to the coil electrode 26.

  The structure of the mask member 50 is shown in FIG. 2A shows the mask member 50 viewed from inside the processing chamber 20, and FIG. 2B shows a cross section of the mask member 50 taken along the line IIB-IIB in FIG. The mask member 50 is disposed in a circular opening 203 formed in the window material receiving portion 202 of the processing chamber 20, and is placed under the discard plate 27 by a ring-shaped mask support component 52 fixed to the ceiling 201 with screws 51. It is supported. A step portion 501 is formed along the circumference on the upper surface of the mask member 50, whereby a gap 502 is formed between the discard plate 27 and the mask member 50. Further, 32 linear slits are formed inside the step portion 501 of the mask member 50.

The slit includes a short slit 503 having a length of about 1/7 of the diameter of the mask member 50 and a long slit 504 having a length of about 1/3. The short slit 503 and the long slit 504 are arranged in the circumferential direction. Alternatingly arranged.
The short slit 503 is arranged close to the outer peripheral side of the mask member 50. Further, the long slit 504 is disposed in an intermediate portion between the center and the outer peripheral edge of the mask member 50, and one of the four long slits 504 is disposed slightly closer to the center side of the mask member 50. Has been.
Each of the short slit 503 and the long slit 504 is inclined by a certain angle (about 10 ° in the example shown in FIG. 2) with respect to a straight line extending in the radial direction from the center of the mask member 50, and as a whole has a radial spiral shape. Is arranged. With such an arrangement, no two slits are positioned on the same straight line. Therefore, the directions of cracks generated at both ends of all the slits (short slit 503 and long slit 504) are different, and the generation of cracks can be suppressed. Further, even if a crack occurs at the end of one of the slits, it is difficult for the crack to combine with a crack generated at the end of another slit, so that the mask member 50 can be prevented from being greatly damaged. it can.

  FIG. 3 is a view showing a mask member according to Embodiment 2 of the present invention. The mask member 60 has 16 slits 603 arranged in a radial spiral shape from the center of the mask member 60 to the outside of the step portion 601. All the slits 603 have the same length, and have a length of about 1/3 of the diameter of the mask member 60. Even if such a mask member 60 is used, the same effect as that obtained by the mask member 50 can be obtained.

  FIG. 4 is a view showing a mask member according to Embodiment 3 of the present invention. The mask member 70 has nine slits 703 arranged radially from the center of the mask member 70 inside the step portion 701. These slits 703 are located on a line connecting each vertex of the regular pentagon 705 shown by a one-dot chain line in FIG. 4 and the center of the mask member 70 so that neither of the two slits 703 is located on the same straight line. It has become. Even if such a mask member 70 is used, the same effect as that obtained by the mask member 50 can be obtained.

  Here, an example in which the slit 703 is provided on a line connecting each vertex of the regular pentagon 705 and the center of the mask member 70 is shown. However, each vertex of the n-gon (n is an odd number) is connected to the center of the mask member. If a slit is provided on the line, any two slits are not located on the same straight line, and thus the same effect as the mask member 70 can be obtained.

  Further, in each of the above-described embodiments, the disk-shaped mask member has been described as an example. However, the present invention can be applied to, for example, a rectangular plate-shaped mask member other than the disk-shaped mask member. Various modifications are possible.

1. Inductively coupled plasma processing apparatus (ICP processing apparatus)
10 ... Sample (object to be processed)
20 ... Processing chamber 23 ... Lower electrode 25 ... Window material 26 ... Coil electrodes 36, 38 ... Radio frequency (RF) generators 50, 60, 70 ... Mask members 503, 504, 603, 703 ... Slits

Claims (2)

A processing chamber in which an object to be processed containing metal atoms is stored, a plate-shaped dielectric window provided in the processing chamber for introducing high-frequency power into the processing chamber, and disposed behind the dielectric window. A mask member mounted on a surface of the dielectric window facing the processing chamber of the inductively coupled plasma processing apparatus including the coil electrode,
A conductive film formed on the surface of the dielectric window due to metal atoms scattered from the workpiece during plasma processing adheres to the conductive film by the action of a high-frequency magnetic field generated by the coil electrode. A plurality of linear slits for adhering the metal atoms only to a part of the dielectric window so as to be a shape that interrupts the flow of current induced in the conductive film halfway,
The mask member of an inductively coupled plasma processing apparatus, wherein the plurality of linear slits are arranged in a radial spiral shape, and none of the slits is positioned on the same straight line as other slits. A processing chamber in which an object to be processed containing metal atoms is stored, a plate-shaped dielectric window provided in the processing chamber for introducing high-frequency power into the processing chamber, and disposed behind the dielectric window. A mask member mounted on a surface of the dielectric window facing the processing chamber of the inductively coupled plasma processing apparatus including the coil electrode,
A conductive film formed on the surface of the dielectric window due to metal atoms scattered from the workpiece during plasma processing adheres to the conductive film by the action of a high-frequency magnetic field generated by the coil electrode. A plurality of linear slits for adhering the metal atoms only to a part of the dielectric window so as to be a shape that interrupts the flow of current induced in the conductive film halfway,
The plurality of linear slits are composed of n linear slits located on a straight line extending from the center of the n-gon (n is an odd number) toward the apex, and each slit is the same as the other slits. A mask member for an inductively coupled plasma processing apparatus, wherein the mask member is not located on a straight line.

Images