Hereinafter, preferred exemplary embodiments of the present invention are described in detail with reference to the drawings.
A first exemplary embodiment of the present invention relates to an ion gun 10 shown in
The ion gun 10 comprises a plasma generation source 14 and an extraction electrode unit 16. The extraction electrode unit 16 has a first electrode unit 20 and a second electrode unit 22. In the first exemplary embodiment, the ion gun 10 is disposed in an upper portion of the ion beam etching apparatus 12 and is configured so as to emit ions in a downward direction.
The plasma generation source 14 has a discharge chamber 26 opening downwardly and a coil 28 disposed so as to surround the discharge chamber 26. The discharge chamber 26 and the coil 28 are common components of the plasma generation source 14 for supplying ions to both the first and second electrode units 20 and 22. An air supply hole 26A is formed in the upper portion of the discharge chamber 26. A gas supply apparatus 30 is provided for supplying a processing gas, such as Ar, Xe, or Kr, for generating plasma and is connected to the air supply hole 26A via a pipe. Furthermore, one end of the coil 28 is grounded, and the other end is connected to a high frequency power supply apparatus 32 (frequency: from several MHz to several tens of MHz, for example, 13.56 MHz).
The extraction electrode unit 16 comprises a plurality (three in the first exemplary embodiment) of thin plate-like electrode plates 34, 36, and 38 which are disposed close to one another. Each of the electrode plates 34, 36, and 38 has a corresponding plurality is of through holes 34A, 36A, and 38A formed therein to allow ions from the plasma generation source 14 to pass therethrough. The electrode plates 34, 36, and 38 are disposed in the lower portion of the discharge chamber 26 so as to be away from the plasma generation source 14 in that order. In the first exemplary embodiment, the extraction electrode unit 16 has a substantially circular shape when viewed from below. Moreover, the side wall of the discharge chamber 26 has a substantially cylindrical shape.
The first electrode unit 20 includes a portion of the electrode plates 34, 36, and 38 on a first side (being the left side in
The first electrode unit 20 is configured such that the irradiation target area 18A is irradiated with ions from the plasma generation source 14 in a first irradiation direction D1 which is inclined with respect to the reference plane 18 from the first side (being the left side in
The first and second electrode units 20 and 22 are arranged so as to be plane symmetrical one another with respect to the reference plane 18.
The irradiation angle formed by the reference plane 18 and each of the first and second irradiation directions D1 and D2 is set to a small angle, preferably within the range of 1° to 30°, and more preferably within the range of 1° to 5°. As used herein, the term “irradiation angle” is used to refer to an acute angle formed by the reference plane 18 and each of the first and second irradiation directions D1 and D2. Each of the first and second irradiation directions D1 and D2 is a direction of the central axis of the ion beam emitted from a corresponding one of the first and second electrode units 20 and 22. In reality, the respective traveling directions of ions emitted from the first and second electrode units 20 and 22 deviate to a certain extent from the first and second irradiation directions D1 and D2, respectively.
The electrode plate 34 is a screen grid which can isolate the plasma in the discharge chamber 26 from the electrode plate 36 and is connected to a positive electrode of a direct current power source 40. The electrode plate 36 is an acceleration grid and is connected to a negative electrode of a direct current power source 42. The electrode plate 38 is a deceleration grid, also known as an earth electrode, and is grounded. C (carbon) or Mo can be used as the material forming the electrode plates 34, 36, and 38.
Each of these electrode plates 34, 36, and 38 is bent along a portion where the reference plane 18 intersects so as to be plane symmetrical with respect to the reference plane 18, so that the portion where the reference plane 18 intersects protrudes toward the plasma generation source 14 side. In addition to this, the portion included in the first electrode unit 20 and the portion included in the second electrode unit 22 are integrally formed. In each of the electrode plates 34, 36, and 38, the portion included in the first electrode unit 20 is disposed perpendicular to the first irradiation direction D1, and the portion included in the second electrode unit 22 is disposed perpendicular to the second irradiation direction D2.
In the portions included in the first electrode unit 20, the through holes 34A, 36A, and 38A are arranged such that the through holes in each electrode plate are aligned with the corresponding through holes in the other electrode plates in the first irradiation direction D1. Further to this, in the portions included in the second electrode unit 22, the through holes 34A, 36A, and 38A are arranged such that the through holes in each electrode plate are aligned with the corresponding through holes in the other electrode plates in the second irradiation direction D2.
The ion beam etching apparatus 12 is further provided with: a vacuum chamber 44; a supporting portion 46; and a neutralizer 48. The supporting portion 46 can support a thin plate-like irradiation object 24 in the irradiation target area 18A within the vacuum chamber 44 such that the irradiation object 24 is parallel to the reference plane 18.
The vacuum chamber 44 has a substantially box-like shape, and has an attachment portion with opening for the ion gun 10 at the upper portion thereof. An exhaust hole 44A is provided in the lower portion of the vacuum chamber 44, and a vacuum pump 50 is connected to the exhaust hole 44A via a pipe.
As shown in
As shown in
In the present application, the term “magnetic recording media” is not limited to media, such as hard disks, floppy ® disks, and magnetic tapes, in which magnetism alone is used for recording and reproducing information. The term is also used to refer to magneto-optical recording media, such as MO disks, in which both magnetism and light are used and to heat assisted type recording media in which both magnetism and heat are used.
The holding unit 54 is provided with a plurality of holding portions 54A for holding the plurality of substantially disk-shaped workpieces 52. Each of the holding portions 54A is configured such that one disk-shaped workpiece 52 is contained in a through hole 54B which is a size that is slightly larger than the workpiece 52. Three engagement members 54C, 54D, and 54E for engaging the disk-shaped workpiece 52 at three points on the periphery of the workpiece 52 are provided in the surroundings of each through hole 54B.
The supporting portion 46 is provided with three rollers 46A, 46B, and 46C and is configured such that the periphery of the generally disk-shaped irradiation object 24 is supported by the rollers 46A, 46B, and 46C with the irradiation object 24 held upright.
More specifically, a circumferential groove for engaging the outer periphery of the irradiation object 24 is formed in the outer periphery of each of these rollers 46A, 46B, and 46C. Further to this, these rollers 46A, 46B, and 46C are placed so as to support the disk-shaped irradiation object 24 near its lower end and near its horizontal opposite ends.
Moreover, some or all of the rollers 46A, 46B, and 46C are connected to a driving device (not shown) and are configured so as to rotate the substantially disk-shaped irradiation object 24.
The neutralizer 48 is configured to emit particles for neutralizing ions emitted from the ion gun 10. For example, the neutralizer 48 emits electrons into the vacuum chamber 44 for neutralizing positive ions, such as Ar+, emitted from the ion gun 10.
Next, the action of the ion gun 10 and the action of the ion beam etching apparatus 12 are described with reference to the flowchart shown in
First, the irradiation object 24 is placed so as to be supported in an upright position by the supporting portion 46 of the ion beam etching apparatus 12. Thus, a plurality of the workpieces 52 held by the irradiation object 24 are placed in the irradiation target area 18A so as to be parallel to the reference plane 18 (S102).
Next, while the irradiation object 24 are rotated with the supporting portion 46, the opposite surfaces of the plurality of the workpieces 52 held by the irradiation object 24 are irradiated with ions from the ion gun 10 (S104). Specifically, the opposite surfaces of the workpieces 52 are irradiated with ions in plane symmetrical arrangement in the first and second irradiation directions D1 and D2 which are inclined with respect to the surfaces of the workpieces 52.
The filling material 52C on the opposite surfaces of the workpieces 52 is gradually removed as the ions impinge on the surfaces of the workpieces 52. When the upper surface of the convex portions of the recording layers 52B is exposed, the ion irradiation is terminated. In this manner, the surfaces of the workpieces 52 are flattened. In dry etching such as ion beam etching, convex portions tend to be selectively removed faster than concave portions. Further to this, by irradiating the surfaces of the workpieces 52 with ions from a direction which is inclined with respect to each of the surfaces, the tendency of convex portions to be selectively removed faster than concave portions is further enhanced. Therefore, high precision flattening can be performed. In order to achieve high precision flattening, the irradiation angle formed by the reference plane 18 and each of the first and second irradiation directions D1 and D2 should preferably fall within the range of 1° to 30°, and more preferably within the range of 1° to 5° (for example, about 2°).
After the flattening step (S104), a protection layer and a lubrication layer are formed on both sides of the workpieces 52 in accordance with need, whereby the magnetic recording media are completed.
As described above, since the ion gun 10 can irradiate both sides of the workpieces 52 with ions simultaneously, both the sides of the workpieces 52 can be flattened simultaneously using only one ion gun. Therefore, it is sufficient to provide only one ion gun 10 in the ion beam etching apparatus 12, and as such, the ion beam etching apparatus 12 is compact.
Moreover, the plasma generation source 14 of the ion gun 10 has common components for supplying ions to both the first and second electrode units 20 and 22. This also contributes to making the ion beam etching apparatus 12 compact.
Furthermore, in the ion gun 10, the plasma generation source 14 for supplying ions to the first and second electrode units 20 and 22 is common to both the first and second electrode units 20 and 22, and the space inside the discharge chamber 26 is also common to both of them. Hence, both sides of the workpieces 52 are easily irradiated with ion beams of the same intensity. Therefore, both sides of the workpieces 52 can be flattened to the same extent, and the effect of suppressing any warpage of the thin plate-like workpieces 52 is significant.
Next, a description of the second exemplary embodiment of the present invention will be given.
In contrast to the first exemplary embodiment, the second exemplary embodiment is characterized in that a non-irradiating portion 60 is provided between the first and second electrode units 20 and 22, as shown in
The non-irradiating portion 60 includes: a portion which is located at the central portion of each of the electrode plates 34, 36, and 38 (being a portion which the reference plane 18 intersects); and a portion near the central portion in which through holes are not formed.
As described above, by providing the non-irradiating portion 60, the outer peripheral surface of the irradiation object 24 can be prevented from being etched.
Next, a description of the third exemplary embodiment of the present invention will be given.
In contrast to the ion gun 10 of the first exemplary embodiment, an ion gun 70 of the third exemplary embodiment is characterized in that an extraction electrode unit 72 has a generally rectangular shape when viewed from below, as shown in
Ions having passed through the electrode plate-through holes that are distant from the reference plane 18 may reach beyond the irradiation object and may therefore not be projected onto the irradiation object. This will be determined by the size of the irradiation object. When the irradiation angle formed by the reference plane 18 and each of the first and second irradiation directions D1 and D2 is small, the amount of ions not projected onto the irradiation object may increase. However, by forming the extraction electrode unit 72 into a substantially rectangular shape, when viewed from below, in which the edges that are substantially parallel to the reference plane 18 are long and the edges that are substantially perpendicular to the reference plane 18 are short, the amount of ions not projected onto the irradiation object can be reduced. In this manner, the irradiation efficiency of the irradiation object with the ion beam can be improved.
Next, a description of the fourth exemplary embodiment of the present invention will be given.
In contrast to the first exemplary embodiment, in the configuration of the fourth exemplary embodiment, electrode plates 84, 86, and 88 constitute an extraction electrode unit 82 that includes the first and second electrode units 20 and 22. In addition to this, insulating portions 84A, 86A, and 88A are provided between portions included in the first electrode unit 20 and portions included in the second electrode unit 22, as shown in
The material for the insulating portions 84A, 86A, and 88A, may include, for example, a ceramic containing Al, Ti, or C as the principal ingredient such as silicon carbide, titanium oxide, or AlTiC.
Moreover, two direct current power sources 40 are provided and are connected to the corresponding portions included in the first and second electrode units 20 and 22, respectively, in the electrode plate 84 serving as a screen grid.
Similarly, two direct current power sources 42 are provided and are connected to the corresponding portions included in the first and second electrode units 20 and 22, respectively, in the electrode plate 86 which serves as an acceleration grid.
As described above, by electrically insulating the portions included in the first and second electrode units 20 and 22, respectively, in each of the electrode plates 84, 86, and 88 constituting the extraction electrode unit 82, the voltages applied thereto can be adjusted independently. Hence, the intensity and energy of the ion beam emitted from the first electrode unit 20 and the intensity and energy of the ion beam emitted from the second electrode unit 22 can also be controlled independently. In this manner, for example, the intensity and energy of the ion beam projected onto one side of the irradiation object 24 and the intensity and energy of the ion beam projected onto the other side can be made coincident with each other with high precision. Alternatively, the intensity and energy of the ion beam projected onto one side of the irradiation object 24 can be intentionally made different from the intensity and energy of the ion beam projected onto the other side of the irradiation object 24.
Next, a description of the fifth exemplary embodiment of the present invention will be given.
In contrast to the fourth exemplary embodiment, in the configuration of the fifth exemplary embodiment, each of the insulating portions 84A, 86A, and 88A also serves as the non-irradiating portion in the second exemplary embodiment, as shown in
Next, a description of the sixth exemplary embodiment of the present invention will be given.
In contrast to the first exemplary embodiment, in the configuration of the sixth exemplary embodiment, a partition wall 26B is provided in the discharge chamber 26, as shown in
Even when the partition wall 26B is provided inside the discharge chamber 26 as described above, the plasma generation source 14 has common components, such as the outside wall of the discharge chamber 26 and the coil 28, for supplying ions to both the first and second electrode units 20 and 22. This contributes to making the ion gun compact, as is also the case in the first exemplary embodiment.
Next, a description of the seventh exemplary embodiment of the present invention will be given.
In contrast to the first exemplary embodiment, in the seventh exemplary embodiment, electrode plates 108, 110, and 112 constituting a first electrode unit 102 and a second electrode unit 104 of an extraction electrode unit 100 are configured as follows. In each of the electrode plates 108, 110, and 112, a portion of the electrode plate on one side of a plane 106 and a portion the electrode plate on the other side of the plane 106 are symmetrically inclined with respect to the plane 106 so as to face an intersecting portion of the plane 106 and the irradiation target area 18A, as shown in
It is important to note that, as in the first exemplary embodiment, each of the electrode plates 108, 110, and 112 is also symmetrically inclined with respect to the reference plane 18.
As described above, each of the electrode plates 108, 110, and 112 is symmetrically inclined with respect to the reference plane 18 and is also symmetrically inclined with respect to the plane 106 so as to face the intersecting portion of the plane 106 and the irradiation target area 18A. Also in this case, ions can be projected at a certain irradiation angle with respect to the reference plane 18. Moreover, the effect of increasing the intensity of ions projected onto the irradiation target area 18A can be obtained.
Next, a description of the eighth exemplary embodiment of the present invention will be given.
The eighth exemplary embodiment relates to an ion beam etching facility 200 shown in
The perpendicular irradiation ion beam etching apparatus 204 is provided with a pair of the perpendicular irradiation ion guns 202, and therefore the opposite surfaces of the workpieces 52 can be irradiated with ions. A gas supply apparatus 206 for supplying a processing gas, such as Ar, Xe, or Kr, for generating plasma is connected via a pipe to each of the perpendicular irradiation ion guns 202. In the perpendicular irradiation ion gun 202, the extraction electrode unit thereof has a planar structure. The structure of the other components of the perpendicular irradiation ion gun 202 is the same as that of the ion gun 10 of the first exemplary embodiment, and therefore a description thereof is omitted accordingly.
The perpendicular irradiation ion beam etching apparatus 204 is further provided with: a vacuum chamber 208; a supporting portion 210 for supporting the irradiation object 24; and a neutralizer 212. More specifically, the supporting portion 210 supports the irradiation object 24 between the pair of perpendicular irradiation ion guns 202 within the vacuum chamber 208 such that the opposite surfaces of the irradiation object 24 correspondingly face one of the pair of perpendicular irradiation ion guns 202. The supporting portion 210 may be configured so as to rotate the substantially disk-like irradiation object 24, as is the case for the supporting portion 46 of the (inclined irradiation) ion beam etching apparatus 12 in the first exemplary embodiment. Alternatively, the supporting portion 210 may be configured so as not to rotate the irradiation object 24 since the surface of the workpieces 52 is irradiated with ions from a direction that is perpendicular to the surfaces of the workpieces 52.
The vacuum chamber 208 has a substantially box-like shape and attachment portions for the pair of perpendicular irradiation ion guns 202 has opening. An exhaust hole 208A is provided in the lower portion of the vacuum chamber 208, and a vacuum pump 214 is connected to the exhaust hole 208A via a pipe.
Since the configuration of the (inclined irradiation) ion beam etching apparatus 12 has been described in the first exemplary embodiment, the redundant description is omitted accordingly. The configuration of the ion gun 10 of the (inclined irradiation) ion beam etching apparatus 12 may be similar to that detailed in the second to seventh exemplary embodiments.
Next, the action of the ion beam etching facility 200 will be described with reference to the flowchart shown in
First, by means of the perpendicular irradiation ion beam etching apparatus 204, the opposite surfaces of the workpieces 52 held by the irradiation object 24 are irradiated with ions in directions that are substantially perpendicular to the opposite surfaces of the workpieces 52 (S202). The filling material 52C on the opposite surfaces of the workpieces 52 is removed as the ions impinge on the surfaces thereof. The ion irradiation is terminated before the upper surface of the convex portions of the recording layers 52B is exposed. By irradiating the surfaces of the workpieces 52 with ions in directions that are substantially perpendicular to the surfaces as described above, the etching rate for the filling material 52C can be improved, and this contributes to an improvement in production efficiency.
Next, by means of the (inclined irradiation) ion beam etching apparatus 12, the opposite surfaces of the workpieces 52 are irradiated with ions in directions that are inclined with respect to the opposite surfaces of the workpieces 52 (S204). When the upper surface of the convex portions of the recording layers 52B is exposed, the ion irradiation is terminated. In this manner, the surfaces of the workpieces 52 are flattened. By irradiating the opposite surfaces of the workpieces 52 with ions in directions inclined with respect to the surfaces, the tendency of convex portions to be selectively removed faster than concave portions is further enhanced. Therefore, high precision flattening can be performed. After the inclined etching step (S204) is complete, a protection layer and a lubrication layer are formed on both sides of the workpieces 52 in accordance with need, whereby the magnetic recording media are completed.
As described above, in the perpendicular etching step (S202), the filling material 52C is etched at a relatively high etching rate by means of the perpendicular irradiation ion beam etching apparatus 204. In the inclined etching step (S204), the filling material 52C is etched by means of the (inclined irradiation) ion beam etching apparatus 12 in which the tendency of convex portions to be selectively removed faster than concave portions is enhanced. By carrying out the perpendicular etching step (S202) and the inclined etching step (S204) in this order, both an improvement in production efficiency and high precision flattening can be compatible.
In the first to eighth exemplary embodiments, the first electrode unit 20 (74, 102) and the second electrode unit 22 (76, 104) are plane symmetric with respect to the reference plane 18. In addition, the irradiation angle formed by the first irradiation direction D1 and the reference plane 18 is the same as the irradiation angle formed by the second irradiation direction D2 and the reference plane 18. However, the irradiation angle formed by the first irradiation direction D1 and the reference plane 18 may be slightly different from the irradiation angle formed by the second irradiation direction D2 and the reference plane 18, so long as both sides of a workpiece can be flattened satisfactorily.
Furthermore, in the first to eighth exemplary embodiments, the extraction electrode unit 16 (72, 82, 100) is composed of the three electrode plates 34, 36, and 38 (84, 86, and, 88; 108, 110, and 112). However, the extraction electrode unit 16 (72, 82, 100) may be composed of two electrode plates or four or more electrode plates according to required specifications or the like.
Moreover, in the first to eighth exemplary embodiments, the electrode plates 34, 36, and 38 (84, 86, and, 88; 108, 110, and 112) have a flat surface shape. However, the electrode plates may have a curved surface shape, so long as both sides of a workpiece can be flattened satisfactorily.
Furthermore, in the first, second, and fourth to eighth exemplary embodiments, the extraction electrode unit 16 (82) has a substantially circular shape as viewed from the bottom. In the third exemplary embodiment, the extraction electrode unit 72 has a substantially rectangular shape as viewed from the bottom. However, the extraction electrode unit may have a shape, such as a hexagonal shape or an ellipsoidal shape, other than a circular shape and a rectangular shape, according the shape or the like of an irradiation object.
Furthermore, in the first to eighth exemplary embodiments, a plurality of the workpieces 52 held by the irradiation object 24 are etched simultaneously. However, the present invention is applicable to processing of a single workpiece.
Moreover, in the first to eighth exemplary embodiments, a noble gas such as Ar, Kr, or Xe is exemplified as the processing gas. However, both sides of the workpieces 52 may be flattened by using a gas containing a gas (an oxygen-containing gas or a halogen-containing gas) having a property of chemically reacting with the filling material 52C to make the filling material 52C brittle.
Furthermore, in the first to eighth exemplary embodiments, the plasma generation source 14 is of the inductive coupling type. However, there may be used, for example, a DC plasma source or a high frequency plasma source such as the ECR (electron cyclotron resonance) type, the helicon wave plasma type, the capacitive coupling type.
Moreover, in the eighth exemplary embodiment, the filling material 52C is first etched at a high etching rate by irradiating the opposite surfaces of the workpieces 52 with ions in respective directions perpendicular to the opposite surfaces of the workpieces 52 by means of the perpendicular irradiation ion beam etching apparatus 204 (S202). Subsequently, the opposite surfaces of the workpieces 52 are irradiated with ions in respective directions inclined with respect to the opposite surfaces of the workpieces 52 (S204). However, other etching apparatus such as a reactive ion etching apparatus may be used in place of the perpendicular irradiation ion beam etching apparatus 204. Also in this case, the filling material 52C can be etched at a high etching rate by using, for example, a gas containing a gas (an oxygen-containing gas or a halogen-containing gas) having a property of chemically reacting with the filling material 52C to make the filling material 52C brittle, and this contributes to the improvement of the production efficiency. In addition, etching may be performed in a reactive ion etching apparatus by using a noble gas, such as Ar, Kr, or Xe, as the processing gas.
Furthermore, in the first to eighth exemplary embodiments, discrete track media and patterned media are exemplified as the magnetic recording media obtained by processing the workpieces 52. However, the present invention is applicable to the manufacturing of magnetic disks having a spiral-shaped recording layer. Moreover, the present invention is applicable to the manufacturing of magneto-optical disks such as MO disks and heat assisted type recording disks in which both magnetism and heat are used.
Number | Date | Country | Kind |
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2006-278755 | Oct 2006 | JP | national |
2007-223111 | Aug 2007 | JP | national |