JP2009129817A - Ion beam processor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ion beam processor capable of restraining abnormal discharge and stably making plasma oscillation. <P>SOLUTION: The ion beam processor includes a plasma chamber 10 for regulating a plasma generation space, an antenna coil 12 for inducing an induction field in order to generate plasma in the plasma generation space, a dielectric window 22 arranged as a pressure partition for the plasma chamber and the open air between the antenna coil 12 and the plasma generation space, a dielectric plate 24 arranged between the dielectric window 22 and the plasma generation space, and an ion beam source arranged at a position opposite to the antenna coil 12 by sandwiching the plasma generation space and including two or more of porous extraction electrodes 30 in order to accelerate ions in the plasma. The ion beam processor has a shield electrode 20 arranged between the dielectric window 22 and the dielectric plate 24 and having a plurality of first conductive wirings mutually isolated with each other and a second conductive wiring connected to the plurality of the whole first conductive wirings at one location. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an ion beam processing apparatus using high frequency inductively coupled plasma.

  In an ion beam processing apparatus using high frequency inductively coupled plasma, a high frequency (RF) current is passed through a planar coil antenna coil disposed outside the plasma chamber to generate an alternating magnetic field on the plasma chamber side. Since an electric current tends to flow in a direction that cancels the generated alternating magnetic field, an induced electric field is induced on the plasma chamber side through a dielectric plate provided in the plasma chamber. Electrons are accelerated by this induction electric field, that is, inductively coupled, whereby the accelerated electrons ionize the gas in the plasma chamber to generate a discharge, and inductively coupled plasma is generated.

  Using charged particles in the inductively coupled plasma generated in the plasma chamber, it is possible to perform processing such as etching, sputtering, and deposition on an object to be processed in the sample chamber. For example, in the etching process, a voltage is applied to the extraction electrode to extract and accelerate ions in the plasma, and the object to be processed is etched by colliding the accelerated ions.

  In order not to reduce the inductive coupling between the antenna coil and the plasma, the antenna coil is disposed in the vicinity on the atmospheric pressure side of the dielectric window that is the pressure partition of the plasma chamber. In order to protect the surface of the dielectric window on the plasma generation space side from contamination by plasma, a dielectric plate is installed between the dielectric window and the plasma generation space.

  The antenna coil and the plasma are coupled including not only the inductive coupling component but also the capacitive coupling component. The RF voltage generated by flowing an RF current through the antenna is capacitively coupled with charged particles in the plasma, and the charged particles are accelerated toward the antenna. The surface of the dielectric plate exposed to the plasma is sputtered by accelerated ions, and the sputtered dielectric adheres to the plasma chamber wall and the surface of the extraction electrode.

  The dielectric attached to the extraction electrode is an insulating material. Therefore, the dielectric adhered by the DC voltage applied to the extraction electrode is charged up to cause electrostatic breakdown, and arc discharge occurs in the vicinity of the extraction electrode.

As means for suppressing sputtering of the dielectric plate, there is one in which a shield electrode is disposed between the antenna coil and the dielectric window (for example, see Patent Document 1). In this prior art, the shield electrode is composed of a plurality of thin conductors extending radially from the central hub, and the capacitive coupling component between the antenna coil and the plasma can be controlled by electrically floating or grounding. It is said.
Special Table 2004-500703

  In the prior art, while sputtering of the dielectric plate is suppressed by the grounding of the shield electrode, the problem is that discharge is less likely to occur due to a decrease in the capacitive coupling component. As described above, since the capacitive coupling component also contributes to the generation of plasma, there are cases where it is difficult to generate a discharge with only the inductive coupling component. In this case, it is necessary to increase the RF current as compared with the case where there is a capacitive coupling component. For this reason, at the start of discharge, the shield electrode is electrically floated to leave a capacitive coupling component and maintain the ease of occurrence of discharge. After the start of discharge, the shield electrode is grounded to electrostatically shield the potential of the antenna coil, and the capacitive coupling component is reduced to suppress sputtering of the dielectric plate.

  Here, as a background requiring the potential control of the shield electrode, there is an installation position of the shield electrode. In the prior art, since the shield electrode is installed between the antenna coil and the dielectric window, in order to avoid contact between the antenna coil and the shield electrode and to avoid discharge between the antenna coil and the shield electrode, the antenna It is necessary to provide a gap between the coil and the shield electrode. The gap increases the distance between the antenna coil and the plasma and weakens the inductive coupling. Therefore, compared to the case where the antenna coil and the dielectric window are close to each other, discharge is less likely to occur.

  In view of the above problems, an object of the present invention is to provide an ion beam processing apparatus capable of suppressing sputtering of a dielectric plate with a simple structure and suppressing abnormal discharge.

  In order to achieve the above object, an aspect of the present invention includes (a) a plasma chamber that defines a plasma generation space, and (b) an antenna coil that induces an induction electromagnetic field for generating plasma in the plasma generation space; (C) a dielectric window provided as a pressure partition between the plasma chamber and the atmosphere between the antenna coil and the plasma generation space; and (d) a dielectric plate disposed between the dielectric window and the plasma generation space. And (e) two or more porous extraction electrodes for accelerating ions in the plasma disposed at a position facing the antenna coil across the plasma generation space, and (f) between the dielectric window and the dielectric plate. An ion beam processing apparatus comprising a shield electrode having a second conductive wiring arranged and connected to all of the plurality of first conductive wirings isolated from each other and all of the plurality of first conductive wirings at one point and having one end grounded And summary that is.

  In the present invention, it is not necessary to provide a gap between the antenna coil and the dielectric window by providing the shield electrode between the dielectric window which is a pressure partition and the dielectric plate. By installing the antenna coil close to the dielectric window, the antenna coil and the plasma are efficiently inductively coupled, and even when the shield electrode is grounded and the capacitive coupling component is reduced, the discharge can be performed without increasing the RF current. Can be generated. Since the ease of plasma generation does not change even when the shield electrode is grounded, it is not necessary to control the potential of the shield electrode, and sputtering of the dielectric plate can be suppressed with a simpler structure.

  ADVANTAGE OF THE INVENTION According to this invention, the ion beam processing apparatus which can suppress sputtering of a dielectric plate with a simple structure and can suppress arc discharge can be provided.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic and the configuration of the apparatus and system is different from the actual one. Therefore, a specific configuration should be determined in consideration of the following description. Moreover, it is a matter of course that portions having different structures and the like are included between the drawings.

  The following embodiments of the present invention exemplify apparatuses and methods for embodying the technical idea of the present invention. The technical idea of the present invention is based on the material and shape of component parts. The structure, arrangement, etc. are not specified below. The technical idea of the present invention can be variously modified within the technical scope described in the claims.

  As shown in FIG. 1, an ion beam processing apparatus according to an embodiment of the present invention applies a plasma chamber 10 that defines a plasma generation space, and a substrate 50 that is a sample using plasma PL generated in the plasma chamber 10. A sample chamber 40 or the like for performing processing is provided. An antenna coil 12 is disposed outside the plasma chamber 10. Plasma PL is generated in the plasma chamber 10 by being induced from an alternating magnetic field (induction electric field) generated in the antenna coil 12. The antenna coil 12 is connected to a radio frequency (RF) power supply 16 through a matching unit.

  The plasma chamber 10 is disposed between the dielectric window 22 facing the antenna coil 12, the dielectric plate 24 disposed between the dielectric window 22 and the plasma PL, and between the dielectric window 22 and the dielectric plate 24. The shield electrode 20 is provided. Further, in the plasma chamber 10, a porous extraction electrode 30 that extracts the ion beam IB from the plasma PL is disposed between the plasma PL and the substrate 50. The porous extraction electrode 30 includes a first grid 32, a second grid 34, and a third grid 36 arranged from the plasma PL side toward the substrate 50 side.

  In the sample chamber 40, a substrate 50 such as a semiconductor or a dielectric that is a sample (object to be processed) is placed on a substrate holder 42. The sample chamber 40 and the plasma chamber 10 are evacuated by a vacuum pump (not shown) connected to the exhaust pipe 44.

  As shown in FIG. 2, an RF current is supplied to one end of the antenna coil 12 from the RF power source 16 shown in FIG. The other end of the antenna coil 12 is connected to the ground wiring. The shield electrode 20 is connected to the ground wiring. A positive voltage Vga is applied to the first grid 32 of the porous extraction electrode 30. A negative voltage Vgb is applied to the second grid 34. The third grid 36 is connected to the ground wiring. The main body of the plasma chamber 10 is also connected to the ground wiring. The dielectric window 22 holds the plasma chamber 10 in a vacuum by a gasket 46 such as an O-ring.

  As shown in FIGS. 3 and 4, the shield electrode 20 includes a plurality of first conductive wires 2 and second conductive wires 4 provided on the surface of the insulating film 6. Each of the plurality of first conductive wirings 2 is a wiring that is isolated from each other in the form of stripes arranged substantially in parallel. The second conductive wiring 4 is a striped wiring connected to all of the plurality of first conductive wirings 2 at one place. A connection terminal 3 connected to the ground wiring is provided at one end of the second conductive wiring 4. In FIG. 4, the shield electrode 20, the dielectric window 22, and the dielectric plate 24 are shown separated from each other, but when mounted in the plasma chamber 10, they are arranged in close contact with each other.

  The wiring patterns of the first and second conductive wirings 2 and 4 are formed in a comb shape so as not to be parallel to the antenna coil 12 in a plane parallel to the surface of the insulating film 6. Therefore, the first and second conductive wirings 2 and 4 are not parallel to the electric field induced by the high frequency current applied to the antenna coil 12 and do not form an eddy current loop circuit. As a result, the first and second conductive wirings 2 and 4 can be prevented from being heated and damaged.

  The antenna coil 12 is formed so as to be included in the wiring pattern of the first and second conductive wirings 2 and 4. In other words, the area occupied by the wiring patterns of the first and second conductive wirings 2 and 4 is wider than the area formed by the antenna coil 12. Therefore, the electric field of the antenna coil 12 can be electrostatically shielded by the first and second conductive wirings 2 and 4, and the capacitive coupling component between the antenna coil 12 and the plasma PL can be reduced. Although the first and second conductive wirings 2 and 4 have been described as linear stripes, they are not limited. For example, an arc shape, a meandering shape, or a polygonal line shape may be sufficient. Further, as shown in FIG. 4, the shield electrode 20 is arranged so that the first and second conductive wirings 2, 4 face the dielectric plate 24, but the arrangement may be reversed.

  The first and second conductive wirings 2 and 4 are made of a conductive material such as a metal such as aluminum (Al), copper (Cu), silver (Ag), and gold (Au), or a combination of these conductive materials. A thin film such as a composite material or a composite material made of a combination of these conductive materials and other materials, or a foil is used. As the insulating film 6, a polymer film such as a fluorine resin such as polytetrafluoroethylene (PTFE), polyimide, polyethylene terephthalate (PET), silicon resin, and epoxy resin is used. The insulating film 6 is desirably thin enough to be negligible, for example, about 20 μm to about 50 μm so as not to weaken the inductive coupling between the antenna coil 12 and the plasma PL.

  For example, the shield electrode 20 can be produced by patterning a metal foil (conductive thin film) formed on the surface of the polymer film as the insulating film 6 by photolithography, etching, or the like. Alternatively, a metal foil (conductive thin film) may be attached to the surface of the polymer film as the insulating film 6 with an adhesive.

  Alternatively, the shield electrode 20 may be formed by patterning and baking a conductive paste of Al, Ag, carbon (C), Cu or the like or a composite paste of these materials by silk printing or the like. For example, as the conductive paste, a material in which Ag or silver carbon (Ag / C) is mixed with a solvent such as epoxy is used, and can be fired at a low temperature of about 70 ° C. to about 200 ° C. Therefore, even when the frequency of the high-frequency current applied to the antenna coil 12 is changed or the shape of the antenna coil 12 is changed, the specification of the shield electrode 20 can be easily changed.

As the dielectric window 22 and the dielectric plate 24, a dielectric such as alumina (Al ₂ O ₃ ), quartz, boron nitride (BN), or the like is used. Since the dielectric window 22 is a pressure partition wall of the plasma chamber 10, it needs mechanical strength, and has a diameter greater than the antenna coil diameter and a thickness of about 10 mm to about 20 mm. The dielectric plate 24 preferably has a thickness of about 1 mm to about 2 mm so as not to weaken the inductive coupling between the antenna coil and the plasma. The dielectric plate 24 is used to prevent contamination of the dielectric window 22 from the plasma PL, and is appropriately removed and cleaned. During maintenance, it is not necessary to remove the dielectric window 22 and the shield electrode 20.

  Since the shield electrode 20 is disposed with the dielectric window 22 sandwiched from the antenna coil 12, no discharge is generated between the antenna coil 12 and the dielectric window 22. Therefore, the antenna coil 12 may be disposed in contact with the dielectric window 22.

  For example, FIG. 5 shows an ion beam processing apparatus that does not use a shield electrode as a comparative example. A gas such as argon (Ar) introduced into the plasma chamber 10 from an introduction pipe (not shown) is ionized in the plasma PL. The ions in the plasma PL are accelerated by the potential difference between the antenna coil potential Vc and the plasma potential Vp due to capacitive coupling between the antenna coil and the plasma, and the dielectric plate 24 is sputtered. The sputtered dielectric 62 adheres to the inner wall of the plasma chamber 10 and the extraction electrode 30, particularly the surface of the first grid 32 facing the plasma PL. The dielectric film 64 attached to the surface of the first grid 32 is an insulating material, and is electrostatically broken by being charged up by the DC voltages Vga and Vgb applied between the first and second grids 32 and 34. As a result, arc discharge occurs in the vicinity of the extraction electrode 30.

  On the other hand, in the embodiment of the present invention, the shield electrode 20 is disposed between the dielectric window 22 and the dielectric plate 24 as shown in FIG. The shield electrode 20 is grounded. Therefore, the electric field of the antenna coil 12 can be electrostatically shielded, and the capacitive coupling component between the antenna coil 12 and the plasma PL can be reduced. As a result, sputtering of the dielectric plate 24 by ions in the plasma PL can be suppressed. The sputtered dielectric 62 adheres to the inner wall of the plasma chamber 10 and the extraction electrode 30, particularly the surface of the first grid 32 facing the plasma PL, but the amount of dielectric film adhering to the surface of the first grid 32 due to the suppression of sputtering. Therefore, arc discharge generated in the vicinity of the extraction electrode 30 due to the DC voltage applied to the grid can be reduced.

  3 and FIG. 4, the insulating film 6 is not used, and the first conductive wiring 2 and the second conductive wiring 4 having the connection terminals 3 are patterned as shown in FIG. 6 and FIG. Alternatively, the shield electrode 20a may be formed by fixing the dielectric window 22 by directly attaching it to the dielectric window 22 with an adhesive or the like. Alternatively, the shield electrode 20 a may be fixed to the dielectric window 22 by patterning and baking the conductive paste by silk printing or the like. By directly fixing the shield electrode 20a to the dielectric window 22, the maintenance of the dielectric plate 24 can be performed while the shield electrode 20a is fixed at the time of maintenance of the dielectric plate 24.

  Further, as shown in FIGS. 8 and 9, the first conductive wiring 2 and the second conductive wiring 4 having the connection terminals 3 are formed by patterning, and directly adhered to the dielectric plate 24 with an adhesive or the like. The shield electrode 20b may be fixed. Alternatively, the shield electrode 20b may be fixed to the dielectric plate 24 by patterning and baking the conductive paste by silk printing or the like. By directly fixing the shield electrode 20b to the dielectric plate 24, an optimum pattern of shield electrode can be obtained. For example, even when the frequency of the high-frequency current applied to the antenna coil 12 is changed or the shape of the antenna coil 12 is changed, the shield electrode 20b can be changed by replacing the dielectric plate 24.

In the embodiment according to the present invention shown in FIGS. 3 to 9, it is not necessary to attach or detach the antenna coil 12 when changing the shield electrode, as compared with the case where the shield electrode is installed between the antenna coil and the dielectric window. . As a result, the mounting position of the antenna coil does not shift, and the performance of the ion beam processing apparatus such as processing uniformity and processing speed for the substrate 50 shown in FIG. 1 can be stabilized.

(Other embodiments)
As mentioned above, although this invention was described by embodiment of this invention, it should not be understood that the statement and drawing which make a part of this indication limit this invention. From this disclosure, various alternative embodiments, examples, and operational techniques will be apparent to those skilled in the art. Accordingly, the technical scope of the present invention is defined only by the invention specifying matters according to the scope of claims reasonable from the above description.

It is the schematic which shows an example of a structure of the ion beam processing apparatus which concerns on embodiment of this invention. It is the schematic which shows an example of a structure of the plasma chamber of the ion beam processing apparatus which concerns on embodiment of this invention. It is a schematic plan view which shows an example of the shield electrode of the ion beam processing apparatus which concerns on embodiment of this invention. It is the schematic which shows the cross section along the AA line of the shield electrode shown in FIG. It is the schematic which shows an example of the plasma chamber of the ion beam apparatus by a comparative example. It is a schematic plan view which shows the other example of the shield electrode of the ion beam apparatus which concerns on embodiment of this invention. It is the schematic which shows the cross section along the BB line of the shield electrode shown in FIG. It is a schematic plan view which shows the further another example of the shield electrode of the ion beam apparatus which concerns on embodiment of this invention. It is the schematic which shows the cross section along CC line of the shield electrode shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 2 ... 1st conductive wiring 4 ... 2nd conductive wiring 6 ... Insulating film 10 ... Plasma chamber 12 ... Antenna coil 20 ... Shield electrode 22 ... Dielectric window 24 ... Dielectric board

Claims (9)

A plasma chamber defining a plasma generation space;
An antenna coil for inducing an induction electromagnetic field for generating plasma in the plasma generation space;
A dielectric window provided as a pressure partition between the plasma chamber and the atmosphere between the antenna coil and the plasma generation space;
A dielectric plate disposed between the dielectric window and the plasma generation space;
Two or more porous extraction electrodes for accelerating ions in the plasma, disposed at positions facing the antenna coil across the plasma generation space;
A plurality of first conductive wirings arranged between the dielectric window and the dielectric plate, connected to all of the plurality of first conductive wirings at one place, and one end grounded. Shield electrode wiring having
An ion beam processing apparatus comprising:   2. The ion beam processing apparatus according to claim 1, wherein the shield electrode wiring is formed of a pattern of a conductive thin film fixed to a surface of the dielectric window facing the dielectric plate.   2. The ion beam processing apparatus according to claim 1, wherein the shield electrode wiring comprises a pattern of a conductive thin film fixed to a surface of the dielectric plate facing the dielectric window.   2. The ion beam processing apparatus according to claim 1, wherein the shield electrode wiring includes a polymer film and a pattern of a conductive thin film on the polymer film.   The ion beam processing apparatus according to claim 2, wherein the pattern of the conductive thin film is attached to the dielectric window with an adhesive.   The ion beam processing apparatus according to claim 3, wherein the pattern of the conductive thin film is attached to the dielectric plate with an adhesive.   The ion beam processing apparatus according to claim 1, wherein the first and second conductive wirings are a fired product of a conductive paste.   The ion beam processing apparatus according to claim 1, wherein the first and second conductive wires form a pattern that is not parallel to an induced electric field induced from the antenna coil. . 9. The ion beam processing apparatus according to claim 1, wherein a region occupied by a wiring pattern formed by the first and second conductive wirings is wider than a region formed by the antenna coil.

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