JP2010056028A - Ion beam treatment device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ion beam treatment device which suppresses a change in incident energy distribution of an ion beam. <P>SOLUTION: The ion beam treatment device includes a plasma chamber for defining a generation space of plasma, a first grid 12 having a plurality of first through-holes 6a, a second grid 14 arranged on an opposite side of the generation space with the first grid 12 formed therebetween and having a plurality of second through-holes 6b for respectively communicating to the plurality of first through-holes 6a, a spacer 2 having projections 52, 54 projecting to both sides so as to fit to a first communicating hole 6A among the plurality of first through-holes 6a and a second communicating hole 6B among the plurality of second through-holes 6b, an extraction electrode 10 facing to the generation space for extracting ions in plasma, and a substrate base facing to the extraction electrode 10 for mounting a substrate to be treated by ions extracted from the generation space. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an ion beam processing apparatus having an ion extraction electrode.

  In an ion beam processing apparatus that performs processing such as etching, sputtering, and deposition, charged particles in plasma generated in a plasma chamber are used. For example, in the etching process, a voltage is applied to the extraction electrode to extract ions in the plasma and accelerate in the direction from the plasma chamber toward the sample chamber. The object to be processed is etched by causing the accelerated ions to collide with the object to be processed arranged in the sample chamber.

  The extraction electrode has a plurality of grids. Each of the plurality of grids is provided with a plurality of through holes communicating with each other in order to allow the ion beam to pass therethrough. When the extraction electrode has two grids, a positive voltage is applied to the plasma-side grid and a negative voltage is applied to the sample chamber-side grid. When the extraction electrode has three grids, a positive voltage is applied to the plasma-side grid and a negative voltage is applied to the intermediate grid, and the grid on the sample chamber side is grounded.

  Ions in the plasma are accelerated by the potential gradient between the grids of extraction electrodes. Since the incident energy of ions to the object to be processed is proportional to the velocity, it is necessary to keep the distance between the grids constant in order to make the incident energy distribution of the accelerated ions uniform. For this reason, the extraction electrode is assembled by sandwiching the spacer with a plurality of grids. Usually, the spacer is arranged and fixed on the outer periphery of the grid so as not to obstruct the passage of the ion beam. Further, since an acceleration voltage of several hundred volts is applied to the grid, a material having a high withstand voltage is used for the spacer.

  Since the extraction electrode is exposed to plasma, the temperature of the grid rises due to radiant heat from the plasma. The temperature of the plasma depends on the generation method and generation conditions, but the grid facing the plasma has the highest temperature and may be 100 ° C. or higher. The grid that has become hot expands thermally. Since the grid is fixed at the outer periphery, it cannot extend in a direction parallel to the grid surface, and deforms like a bow in a direction perpendicular to the grid surface. The grid facing the plasma has the highest temperature and the amount of deformation increases.

  In the outer periphery of the extraction electrode, the distance between the grids does not change because the spacers are sandwiched between the grids. However, at the center of the extraction electrode, the grid facing the plasma is deformed like a bow and the distance between the grids changes. Therefore, the potential gradient between the grids becomes non-uniform, and the incident energy distribution of the ion beam extracted from the extraction electrode changes. Due to the change of the incident energy distribution of the ion beam, the etching process causes performance deterioration such as deterioration of the etching distribution and change of the etching rate.

  In view of the above problems, an object of the present invention is to provide an ion beam processing apparatus capable of suppressing changes in the incident energy distribution of an ion beam.

    In order to achieve the above object, an aspect of the present invention includes (a) a plasma chamber that defines a plasma generation space, (b) a first grid having a plurality of first through holes, and a first grid sandwiched between the first grids. A second grid having a plurality of second through holes disposed on the opposite side of the space and communicating with each of the plurality of first through holes, and disposed between the first and second grids, And a first spacer having first protrusions projecting on both sides so as to be fitted in the first communication hole and the second communication hole of the plurality of second through holes, respectively, facing the generation space, and plasma Abstract: An ion beam processing apparatus comprising: an extraction electrode for extracting ions therein; and (c) a substrate table that faces the extraction electrode and mounts an object to be processed by ions extracted from the generation space. And

  ADVANTAGE OF THE INVENTION According to this invention, the ion beam processing apparatus which can suppress the change of the incident energy distribution of an ion beam 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 uses a plasma chamber 20 that defines a plasma space for generating plasma, and a plasma PL generated in the plasma chamber 20 to be processed. A processing chamber 24 for performing processing on the substrate 30 is provided. A plasma source 22 is disposed outside the plasma chamber 20. Plasma PL is generated in the plasma chamber 20 by being induced by the plasma source 22.

  In the plasma chamber 20, an extraction electrode 10 that extracts ions from the plasma PL and accelerates them to form an ion beam IB is disposed between the plasma PL and the substrate 30. The extraction electrode 10 has a circular shape, the first grid 12 facing the plasma PL, the second grid 14 arranged on the opposite side of the plasma space with the first grid 12 in between, and the first with the second grid 14 in between. A third grid 16 disposed on the opposite side of the grid 12 is provided. Note that the shape of the extraction electrode 10 is not limited to a circle, and may be, for example, a rectangle or a polygon.

  A positive voltage Vga is applied to the first grid 12. A negative voltage Vgb is applied to the second grid 14. The third grid 16 is connected to the ground wiring.

  In the processing chamber 24, a substrate 30 such as a semiconductor or dielectric, which is an object to be processed, is placed on the substrate base 26. The processing chamber 24 and the plasma chamber 20 are evacuated by a vacuum pump (not shown) connected to the exhaust pipe 28.

  As shown in FIGS. 2 and 3, the first grid 12 of the extraction electrode 10 includes a plurality of first through holes 6 a and a plurality of through holes 8 a provided along the outer periphery of the first grid 12. The second grid 14 has a plurality of second through holes 6b provided to communicate with each of the plurality of first through holes 6a, and a plurality of penetrations provided to communicate with each of the plurality of through holes 8a. It has a hole 8b. The third grid 16 has a plurality of third through holes 6c provided so as to communicate with each of the plurality of second through holes 6b, and a plurality of penetrations provided so as to communicate with each of the plurality of through holes 8b. It has a hole 8c.

  For example, the width Wg of each of the first to third grids 12, 14, and 16 is 1 mm to 5 mm. The interval Ws between the first and second grids 12 and 14 is 1 mm to 10 mm. The interval between the second and third grids 14 and 16 is substantially the same as the interval Ws. The diameters Dh of the first to third through holes 6a, 6b, 6c are 1 mm to 10 mm.

  A spacer (first spacer) 2 is disposed between the first and second grids 12 and 14. As shown in FIGS. 4 and 5, the spacer 2 includes a disk-shaped base (first base) 50 and protrusions (first protrusions) 52 and 54 protruding from the base 50 on both sides. In addition, the shape of the base | substrate 50 is not limited to disk shape, For example, a rectangle and a polygon may be sufficient.

  The protrusions 52 provided on the surface of the base 50 on the first grid 12 side are fitted in the first communication holes 6A in the plurality of first through holes 6a. The protrusions 54 provided on the surface of the base 50 on the second grid 14 side are fitted into the second communication holes 6B in the plurality of second through holes 6b.

  The thickness Wa of the base 50 of the spacer 2 is substantially the same as the interval Ws between the first and second grids 12 and 14. The diameters Dp and Dq of the protrusions 52 and 54 are substantially the same as the diameters Dh of the first and second communication holes 6A and 6B. The heights Wb and Wc of the protrusions 52 and 54 are preferably set to be equal to or less than the thickness Wg of the first and second grids 12 and 14, respectively. In particular, when the height Wb of the protrusion 52 exceeds the thickness Wg of the first grid 12, as will be described later, the spacer as a dielectric is charged up, so that the in-plane of the extraction electrode 10 viewed from the plasma space is obtained. This is because there is a possibility that a singular point of the potential is generated and the distribution of the extracted ion beam becomes non-uniform. In addition, it is desirable that the spacer 2 has a size that does not block the first through hole 6a other than the first communication hole 6A. This is because if the number of first through holes 6a to be blocked increases, the number of holes from which the ion beam is not extracted increases, which may affect the etching distribution of the object to be processed.

  As shown in FIG. 3, the assembling spacer 4 having through holes 8d, 8e communicating with the through holes 8a, 8b, 8c of the first to third grids 12, 14, 16 is provided in the first and second grids. 12 and 14 and between the second and third grids 14 and 16. The thickness of the assembly spacer 4 is substantially the same as the interval Ws between the first and second grids 12 and 14. The diameters of the through holes 8a, 8b, 8c, 8d, and 8e are substantially the same. Therefore, the through holes 8a, 8d, 8b, 8c, and 8e form a series of assembly through holes 8.

  As the spacers 2 and 4, a dielectric material having a high withstand voltage such as ceramics is used. As the first to third grids 12, 14, and 16, a metal such as molybdenum (Mo) or tungsten (W) is used. As the plasma source 22, a plasma source such as inductively coupled plasma (ICP), electron cyclotron resonance plasma (ECR), helicon wave excitation plasma (HWP), microwave excitation surface wave plasma (SWP), or the like can be used.

  As shown in FIG. 6, an insulating cylindrical part 40, a bolt 41, and a nut 42 are fastened to a plurality of assembly through-holes 8 provided along the outer periphery of the extraction electrode 10, and the first to third grids are fastened. 12, 14, 16 are fixed, and the extraction electrode 10 is assembled. When using conductive bolts 41 and nuts 42 such as metal, an insulating washer 44 is inserted between the bolts 41 and the first grid 12.

  When the plasma PL is generated by the plasma source 22 in the plasma chamber 20 shown in FIG. 1, the temperature of the extraction electrode 10 rises due to the radiant heat of the plasma. The closer to the plasma PL, the higher the grid temperature. For example, in the first grid 12 in contact with the plasma PL, the temperature may be 100 ° C. or higher. In the conventional extraction electrode, bolts and nuts are fastened on the outer periphery of the extraction electrode to fix the first to third grids. Therefore, the first grid is deformed like a bow in the direction perpendicular to the surface of the extraction electrode by heating compared to the second and third grids, and the distance between the first and second grids at the center of the extraction electrode changes. As a result, the potential gradient between the first and second grids becomes non-uniform, and the incident energy distribution on the object to be processed of the ion beam extracted from the extraction electrode changes.

  In the extraction electrode 10 according to the embodiment of the present invention, the spacer 2 having the projections 52 and 54 fitted in the first and second communication holes 6A and 6B is disposed between the first and second grids 12 and 14. The The thickness Wa of the base body 50 of the spacer 2 is substantially the same as the interval Ws between the first and second grids 12 and 14. Even if the first grid 12 is heated by plasma radiation, the projections 52 and 54 fitted in the first and second communication holes 6A and 6B suppress deformation of the first grid 12, and the first and second The interval Ws between the grids 12 and 14 hardly changes. Since the dielectric material having a high withstand voltage is used for the spacer 2, the potential gradient formed between the first and second grids 12 and 14 is not affected. In addition, the first communication hole 6A is blocked by the spacer 2, but generally, since the ion beam has a divergence angle, by the divergence of the ion beam through the plurality of first through holes 6a around the first communication hole 6A, The ion beam also enters the position of the object to be processed corresponding to the first communication hole 6A, and the etching distribution is not affected. As described above, according to the embodiment of the present invention, it is possible to suppress the change in the incident energy distribution of the ion beam supplied to the surface of the substrate 30, and the etching distribution by the extraction electrode 10 according to the embodiment. There is no impact on

  The spacer 2 is preferably arranged at the center in the plane of the extraction electrode 10. If the spacer 2 is disposed at the center, the deformation of the first grid 12 can be effectively suppressed. In order to suppress the deformation of the first grid 12 more effectively, a plurality of spacers may be arranged in the plane of the extraction electrode 10 at appropriate intervals.

  Further, in the extraction electrode 10, the spacer 2 is disposed between the first and second grids 12 and 14. However, as shown in FIG. 7, an extraction electrode 10a in which a spacer (second spacer) 2a is further arranged between the second and third grids 14 and 16 may be used. The spacer 2a includes a base body (second base body) 50a and protrusions (second protrusions) 52a and 54a. The base body 50 a is sandwiched between opposing surfaces of the second and third grids 14 and 16. The protrusions 52a provided on the surface of the base 50a on the second grid 14 side are fitted into the second communication holes 6B. The protrusions 54a provided on the surface of the base 50a on the third grid 16 side are fitted into the third communication holes 6C in the plurality of third through holes 6c communicating with the second communication holes 6B.

  The thickness of the base 50a is substantially the same as the distance between the second and third grids 14 and 16. Further, the heights of the protrusions 54 and 52a of the spacers 2 and 2a are, for example, less than one half of the thickness of the second grid 14 so as not to interfere in the second communication hole 6B. Therefore, even if the temperature of the extraction electrode 10a rises due to plasma radiation, the distance between the first and second grids 12 and 14 and the second and third grids 14 and 16 is kept substantially constant. As a result, it is possible to more effectively suppress the change in the incident energy distribution of the ion beam supplied to the surface of the substrate 30.

(Modification)
As shown in FIGS. 8 and 9, the extraction electrode 10 b according to the modification of the embodiment of the present invention has a spacer 2 b between the first and second grids 12 and 14 in the center of the first grid 12. Placed in. The spacer 2b includes a base body 50b and protrusions 52b and 54b. On the first grid 12 side, a conductive film 56 that covers the surface and side surfaces of the protrusion 52b and extends to at least a part of the surface of the base body 50b is provided. The conductive film 56 is electrically connected to the first grid 12. The base body 50 b is disposed between the opposing surfaces of the first and second grids 12 and 14. The protrusion 52b is fitted into the second communication hole 6B. The protrusion 54b is fitted into the third communication hole 6C among the plurality of third through holes 6c communicating with the second communication hole 6B.

  In the modification of the embodiment of the present invention, the spacer 2b has a conductive film 56 that extends from the protrusion 52b to at least a part of the surface of the base body 50b and is electrically connected to the first grid 12. Different from the embodiment. Other configurations are the same as those in the embodiment, and thus redundant description is omitted.

  In the extraction electrode 10b according to the modification of the embodiment, the spacer 2b having the projections 52b and 54b fitted in the first and second communication holes 6A and 6B is provided at the first and first in the center of the first grid 12. Two grids 12 and 14 are arranged. The thickness of the base body 50 b of the spacer 2 b is substantially the same as the distance between the first and second grids 12 and 14. Even if the first grid 12 is heated by the radiation of plasma, the projections 52b and 54b fitted in the first and second communication holes 6A and 6B suppress deformation of the first grid 12, and the first and second The spacing between the grids 12, 14 hardly changes. In the spacer 2b, the conductive film 56 is electrically connected to the first grid 12. When the first grid 12 is viewed from the plasma side, the potential distribution in the plane of the first grid 12 becomes uniform, and no singular point of potential occurs. Therefore, the trajectory of the ion beam extracted by the extraction electrode 10b is not affected by the spacer 2b. As described above, according to the modification of the embodiment, it is possible to effectively suppress the change in the incident energy distribution of the ion beam supplied to the surface of the substrate 30.

  As shown in FIG. 10, an extraction electrode 10c in which a spacer 2c is further arranged between the second and third grids 14 and 16 may be used. The spacer 2c includes a base body 50c and protrusions 52c and 54c. On the third grid 16 side, a conductive film 56a that covers the surface and side surfaces of the protrusion 54c and extends to at least a part of the surface of the base body 50c is provided. The conductive film 56 a is electrically connected to the third grid 16. The base body 50 c is disposed between the opposing surfaces of the second and third grids 14 and 16. The protrusion 52c is fitted into the second communication hole 6B. The protrusion 54c is fitted into the third communication hole 6C among the plurality of third through holes 6c communicating with the second communication hole 6B.

  The thickness of the base 50c is substantially the same as the distance between the second and third grids 14 and 16. Further, the heights of the protrusions 54b and 52c of the spacers 2b and 2c are less than a half of the thickness of the second grid 14 so as not to interfere in the second communication hole 6B. Therefore, even if the extraction electrode 10c is heated by plasma radiation, the spacing between the first and second grids 12 and 14 and the second and third grids 14 and 16 is kept substantially constant. As a result, it is possible to more effectively suppress the change in the incident energy distribution of the ion beam supplied to the surface of the substrate 30.

(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. Therefore, 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 a schematic plan view which shows an example of the extraction electrode which concerns on embodiment of this invention. It is the schematic which shows the cross section along the AA line of the extraction electrode shown in FIG. It is a schematic plan view which shows an example of the spacer of the extraction electrode which concerns on embodiment of this invention. It is the schematic which shows the cross section along the BB line of the spacer shown in FIG. It is a schematic sectional drawing which shows an example of the assembly of the extraction electrode which concerns on embodiment of this invention. It is a schematic sectional drawing which shows the other example of the extraction electrode which concerns on embodiment of this invention. It is a schematic sectional drawing which shows an example of the extraction electrode which concerns on the modification of embodiment of this invention. It is a schematic sectional drawing which shows an example of the spacer of the extraction electrode which concerns on the modification of embodiment of this invention. It is a schematic sectional drawing which shows the other example of the extraction electrode which concerns on the modification of embodiment of this invention.

Explanation of symbols

2 ... Spacer 6A ... 1st communicating hole 6B ... 2nd communicating hole 6C ... 3rd communicating hole 6a ... 1st through-hole 6b ... 2nd through-hole 6c ... 3rd through-hole 10 ... Extraction electrode 12 ... 1st grid 14 ... 2nd grid 16 ... 3rd grid 20 ... Plasma chamber 26 ... Substrate stand 30 ... Substrate 50 ... Base 52, 54 ... Projection

Claims (5)

A plasma chamber defining a plasma generation space;
A first grid having a plurality of first through holes, a first grid having a plurality of second through holes disposed on the opposite side of the generation space across the first grid and communicating with each of the plurality of first through holes. 2 grids, arranged between the first and second grids, so as to fit into the first communication holes in the plurality of first through holes and the second communication holes in the plurality of second through holes, respectively. A first spacer having first protrusions projecting on both sides, an extraction electrode facing the generation space and extracting ions in the plasma;
An ion beam processing apparatus comprising: a substrate table that faces the extraction electrode and places an object to be processed by the ions extracted from the generation space.   The first spacer has a conductive film that extends from the first protrusion to a part of the surface of the first base on the surface on the first grid side and is electrically connected to the first grid. The ion beam processing apparatus according to claim 1.   3. The ion beam processing apparatus according to claim 1, wherein the first spacer is disposed at a central portion in a plane of the extraction electrode. The extraction electrode is
A third grid having a plurality of third through holes disposed on the opposite side of the first grid across the second grid and provided to communicate with the plurality of second through holes;
A second protrusion that is disposed between the second and third grids and protrudes on both sides so as to fit into the second communication hole and a third communication hole of the plurality of third through holes, respectively; The ion beam processing apparatus according to claim 1, further comprising a second spacer.   The second spacer has a conductive film extending from the second protrusion to a part of the surface of the second base on the surface on the third grid side and electrically connected to the third grid. The ion beam processing apparatus according to claim 4.

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