JP2012037527A - Method for manufacturing near-field light generating element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a near-field light generating element for easily and inexpensively processing a tip of the element without using highly advanced microfabrication techniques.SOLUTION: The method for manufacturing a near-field light generating element, which comprises a frustum 102 of a polygonal cone and generates near-field light from an opening formed at the tip of the frustum 102, includes: a forming step of forming a metal film on a side face of the frustum 102; and after forming the metal film, a residue removing step of removing a residue of the metal film remaining on the side face and on a top face of the frustum 102 by adding external force to the residue.

Description

  The present invention relates to a method for manufacturing a near-field light generating element that generates near-field light.

  The near-field light generating element is used in an optical head in an optical recording apparatus that performs high-density information recording / reproduction, an optical probe in a near-field light microscope that performs observation at high resolution, and the like. The near-field optical technology can handle optical information in a minute region exceeding the diffraction limit of light, and is expected to obtain a high recording density and resolution that cannot be achieved by conventional optical technology.

  The main subject of the near-field light generating element is to obtain a minute and powerful spot of near-field light. Several shapes have already been proposed for this problem. In Patent Document 1, the contour shape of the optical aperture provided at the tip of the near-field light generating element is assumed to be a triangle, and the polarization direction of the incident light and one side of the triangle are orthogonal to each other, thereby localizing the one side. Strong near-field light is generated (triangular aperture method). In Non-Patent Document 1 and Patent Document 2, a metal film is formed on two opposing surfaces of the four side surfaces of a quadrangular pyramid, and the two surfaces have a gap less than the wavelength of light near the apex of the quadrangular pyramid. Each of the metal films has a vertex with a radius of curvature of several tens of nm or less in the gap portion, and generates strong near-field light localized in the gap portion (bowtie antenna system).

  A method for manufacturing the triangular aperture type near-field light generating element of Patent Document 1 has already been disclosed, and can be manufactured relatively easily. However, the bow-tie antenna type near-field light generating elements of Non-Patent Document 1 and Patent Document 2 generally require processing of several nanometers to several tens of nanometers in the shape of the metal film apex or gap portion. Uses extremely advanced microfabrication technology such as an electron beam drawing device and a focused ion beam device.

JP 2001-118543 A Japanese Patent Laid-Open No. 2002-221478

Technical Digest of 6th international conference on nearfield optics and related techniques, the Netherlands, Aug.27-31,2000, p100

  Among the above-described conventional technologies, in the manufacture of a bow-tie antenna type near-field light generating element, the advanced microfabrication technology used for the shape processing of the metal film apex and the gap portion is a single step of the near-field light generating element alone. It can only be processed, and it takes a long time to process the tip part of the near-field light generating element (element tip part), and the processing cost is high, so it is relatively simple and suitable for mass production. There is a need for a method of manufacturing a near-field light generating element of the type.

  Therefore, the present invention has been made in view of the above points, and manufacture of a near-field light generating element capable of processing the tip portion of the element simply and at low cost without using advanced fine processing technology. It aims to provide a method.

In order to solve the above problems, a manufacturing method of the present invention includes a frustum having a polygonal pyramid shape, and a manufacturing method of a near-field light generating element that generates near-field light from an opening formed at a tip of the frustum. A step of forming a metal film on the side surface of the frustum, and a residue of the metal film remaining on the side surface and the top surface of the frustum after the metal film is formed. And a residue removal step of removing the residue by applying an external force.
Further, the residue removing step includes a step of polishing and removing the residue using an abrasive.
The residue removing step is characterized by removing the residue by ultrasonic cleaning after the residue remaining on the top surface is subjected to an impact by the external force to plastically deform the residue. To do.
Further, the residue removing step is characterized in that the residue is removed by spraying a gas having a predetermined pressure on the residue.
The residue removing step is characterized in that solid particles are sprayed onto the residue with a gas having a predetermined pressure to remove the residue.
The residue removing step is characterized in that the residue is polished in a state where the metal film is immersed in a solution.
The residue removing step is characterized by performing ultrasonic cleaning after the polishing is started.

Further, the step of spraying the solid particles with the gas having the predetermined pressure includes a step of spraying other solid particles having a diameter different from the diameter of the solid particles over time. is there.
Further, the frictional resistance between the abrasive and the residue is reduced as the residue is reduced by the abrasive. In the step of polishing, the frictional resistance is measured, and the measured frictional resistance is The residue is polished until a predetermined value is reached.
In addition, the abrasive has a concavo-convex portion on a surface, and the concavo-convex portion is made of a member softer than the frustum.
Further, the member is made of a fiber.
Further, the member is made of a porous material.
Further, the residue removing step comprises a step of simultaneously removing the residue remaining on each of the two side surfaces after forming the metal film on the two opposite side surfaces of the frustum. It is.
The residue removing step first removes the residue left after forming the metal film on one of the two side surfaces of the frustum facing each other, and then shapes the metal film on the other side. The residue left behind is removed.
The frustum is composed of a plurality of pieces, and after forming a metal film on the two side surfaces of the plurality of frustums facing each other, the residue remaining on each of the plurality of frustums is removed. It is characterized by being performed simultaneously.
Further, the metal film is made of Au.
The solid particles are made of dry ice powder.
The forming step includes a step of forming a sacrificial layer on the first side surface of the frustum and the other side of the frustum surface except the second side surface facing the first side surface; Forming a base material of the metal film on the second side surface facing the first side surface and at least a part of the sacrificial layer; and after forming the base material, the sacrificial layer and the sacrificial layer Removing the base material on the layer using a lift-off method.
Further, the sacrificial layer is made of a metal.
Further, the sacrificial layer has a thickness of 5 nm or more and 100 nm or less.
Further, in the residue removing step, light is irradiated from the rear end side to the front end side of the frustum, the transmittance of light transmitted to the outside from the opening of the frustum is measured, and the measured transmission The residue is polished until the rate reaches a predetermined value.

  According to the present invention, the tip portion of the element can be processed easily and at low cost without using an advanced fine processing technique.

It is the schematic of the near-field light generating element in Embodiment 1 of this invention. It is sectional drawing which shows the manufacturing method of the near-field light generating element in Embodiment 1 of this invention. It is sectional drawing and the side view which show the manufacturing method of the near-field light generating element in Embodiment 1 of this invention. It is sectional drawing and the side view which show the manufacturing method of the near-field light generating element in Embodiment 1 of this invention. It is the cross-sectional enlarged view and top view of the near-field light generating element in Embodiment 1 of this invention. It is the cross-sectional enlarged view and top view of the near-field light generating element in Embodiment 1 of this invention. It is the cross-sectional enlarged view, top view, and perspective view of the near-field light generating element in Embodiment 1 of this invention. It is the cross-sectional enlarged view and top view which show the manufacturing method of the near-field light generating element in Embodiment 1 of this invention. It is a cross-sectional enlarged view which shows the manufacturing method of the near-field light generating element in Embodiment 1 of this invention. It is the cross-sectional enlarged view and top view which show the manufacturing method of the near-field light generating element in Embodiment 1 of this invention. It is the perspective view and cross-sectional enlarged view which show the manufacturing method of the near-field light generating element in Embodiment 1 of this invention. It is the top view, cross-sectional enlarged view, and perspective view of the near-field light generating element in Embodiment 1 of this invention. It is sectional drawing and the side view which show the manufacturing method of the near-field light generating element in Embodiment 1 of this invention. It is sectional drawing and the side view which show the manufacturing method of the near-field light generating element in Embodiment 1 of this invention. It is sectional drawing and the side view which show the manufacturing method of the near-field light generating element in Embodiment 2 of this invention. It is sectional drawing and the side view which show the manufacturing method of the near-field light generating element in Embodiment 2 of this invention. It is sectional drawing which shows the manufacturing method of the near-field light generating element in Embodiment 3 of this invention. It is sectional drawing which shows the manufacturing method of the near-field light generating element in Embodiment 3 of this invention. It is sectional drawing of the near-field light generating element in Embodiment 3 of this invention. It is sectional drawing which shows the manufacturing method of the near-field light generating element in Embodiment 4 of this invention. It is sectional drawing which shows the manufacturing method of the near-field light generating element in Embodiment 5 of this invention.

(Embodiment 1)
FIG. 1 shows an outline of a near-field light generating element in Embodiment 1 of the present invention. FIG. 1A is a perspective view and FIG. 1B is a top view. A quadrangular frustum 102 is disposed on an optically transparent substrate 101, and the quadrangular frustum 102 is seen from a side surface 102a (invisible in the metal film 103 in FIG. 1) and 102b (invisible in the metal film 104 in FIG. 1). Not), 102c, 102d and top surface 102e. As the substrate 101, quartz glass or the like is used. The side surface 102a and the side surface 102b are disposed to face each other, and the side surface 102c and the side surface 102d are also disposed to face each other. A metal film 103 is formed on the side surface 102a, and a metal film 104 is formed on the side surface 102b. As the metal film 103 and the metal film 104, an Au film having a film thickness of several nm to several tens of nm is used. The metal film 103 and the metal film 104 form a so-called bow tie antenna.

  The top surface 102e is rectangular, and the length of the side in contact with the side surface 102a and the side surface 102b is d1, and the length of the side in contact with the side surface 102c and the side surface 102d is g1. The metal film 103 and the metal film 104 on the side surface 102a and the side surface 102b have a sharpened shape near the top surface 102e, and the sharpness is represented by d1. The metal film 103 and the metal film 104 have a gap in the vicinity of the top surface 102e, and the size thereof is represented by g1. Both d1 and g1 have a value of several nanometers to several tens of nanometers.

  FIG. 2 is a cross-sectional view showing a method for manufacturing the quadrangular frustum 102 of the near-field light generating element in the first embodiment of the present invention. A plane that crosses the side surfaces 102a and 102b and the top surface 102e and is perpendicular to the substrate 101 is a cross section A 1, and a surface that crosses the side surfaces 102c and 102d and top surface 102e and is perpendicular to the substrate 101 is a cross section B. The cross section A is shown on the left side of FIG. 2, and the cross section of the cross section B is shown on the right side of FIG.

  First, as shown in step S <b> 201, an etching mask 201 is formed on the upper surface of the substrate 101. The etching mask 201 is a photoresist thin film processed by photolithography. The etching mask 201 is rectangular, its two sides are parallel to the cross section A 1, and their length is g2. The remaining two sides are parallel to the cross section B, and their length is d2.

  Next, as shown in step S202, the substrate 101 is etched. Etching may be wet etching or dry etching, but is required to be isotropic etching. For example, when the substrate 101 is made of quartz glass, wet etching using a hydrofluoric acid aqueous solution may be used. By etching the substrate 101, a quadrangular frustum 102 is formed under the etching mask 201.

Next, as shown in step S203, the etching mask 201 is removed. For removing the etching mask 201, an organic solvent such as acetone or fuming nitric acid is used. When the etching mask 201 is removed, the top surface 102e of the quadrangular frustum 102 is exposed. As described above, the top surface 102e is rectangular and has a length of d1 on one side and a length of g1 on the other side perpendicular to the top surface 102e. What is important here is that the ratio between d1 and g1 is equal to the ratio between the side lengths d2 and g2 of the etching mask 201. By adjusting the aspect ratio of the etching mask 201 and the etching amount of the substrate 101, the dimensions of d1 and g1 can be controlled.
FIG. 3A is a cross-sectional view showing a method of forming a metal film on the side surface 102 a of the quadrangular frustum 102. First, as in step S301, the sacrificial layer 301 is formed on the side surface 102b from the direction D301 perpendicular to the side surface 102b by using a resin film forming method having directivity such as a spray coating method. At this time, the sacrificial layer 301 is formed not only on the side surface 102b but also on the side surfaces 102c and 102d and the top surface 102e adjacent to the side surface 102b. The sacrificial layer 301 is not formed on the side surface 102a facing the side surface 102b because it is shaded by the directivity of the film formation method. The sacrificial layer 301 is made of a resin film such as a photoresist and has a film thickness of several tens of nm to several μm.

  Next, as shown in step S302, the metal film 302 is formed on the side surface 102a from the direction D302 perpendicular to the side surface 102a by using a metal film forming method having directivity such as a vacuum deposition method. At this time, the metal film 302 is formed not only on the sacrificial layer 301 on the side surface 102a and the top surface 102e but also on the sacrificial layer 301 on the side surfaces 102c and 102d.

  Next, as shown in step S303, the sacrificial layer 301 is lifted off using an organic solvent such as acetone. Further, the sacrificial layer 301 can be peeled off more easily by applying ultrasonic waves at that time. At this time, the metal film 302 placed on the sacrificial layer 301 is also peeled off, leaving only the metal film 302 placed on the side surface 102a. A residue 303 remains on the top surface 102e side of the metal film 302. FIG. 3B is a side view in the D303 direction in S303 of FIG. As shown in FIG. 3B, residues 303a and 303b remain on the side surfaces.

  Next, FIG. 4A is a cross-sectional view showing a method of forming a metal film on the side surface 102b of the quadrangular frustum 102. FIG. As shown in step S401, a sacrificial layer 401 is formed on the side surface 102a from a direction D401 perpendicular to the side surface 102a by using a directional photoresist forming method such as a spray coating method. At this time, the sacrificial layer 401 is formed not only on the side surface 102a but also on the side surfaces 102c and 102d and the top surface 102e adjacent to the side surface 102a. The sacrificial layer 401 is not formed on the side surface 102b facing the side surface 102a because it is shaded by the directivity of the film formation method. The sacrificial layer 401 is made of a photoresist and has a film thickness of several tens of nanometers to several micrometers.

  Next, as shown in step S402, the metal film 402 is formed on the side surface 102b from the direction D402 perpendicular to the side surface 102b by using a metal film forming method having directivity such as a vacuum deposition method. At this time, the metal film 402 is formed not only on the sacrificial layer 401 on the side surface 102b and the top surface 102e but also on the sacrificial layer 401 on the side surfaces 102c and 102d. Next, as shown in step S403, the sacrificial layer 401 is peeled off using an organic solvent such as acetone. Further, when the ultrasonic wave is applied at that time, the sacrificial layer 401 can be more easily peeled off. At this time, the metal film 402 placed on the sacrificial layer 401 is also peeled off, leaving only the metal film 402 placed on the side surface 102b. A residue 403 remains on the top surface 102 e side of the metal film 402. FIG. 4B is a side view in the D403 direction in S403 of 43A. As shown in FIG. 4B, residues 403a and 403b remain on the side surface.

  Next, as the last step, the residues 303, 303a, 303b and 403, 403a, 403b are removed, whereby the metal films 103 and 104 of the near-field light generating element in step S404 are processed.

  Details of the mechanism in which the residue 303 and residue 403 remain in FIG. 4 will be described below. FIG. 5A is an enlarged view of the vicinity of the top surface in step S302 of FIG. 3, and FIG. 5B is a top view thereof. When the sacrificial layer 301 is peeled off using the lift-off method from the state of FIG. 5, the metal film 302 placed on the sacrificial layer 301 is also peeled off. At that time, the metal film 302a which is a part of the metal film 302 remains on the side surface 102a, but at the same time, the metal film 302e which is a part of the metal film 302 remains as the residue 303 shown in FIG. End up. Further, due to a similar mechanism in which the residue 303 remains, the residues 303a and 303b shown in FIG. 3 also remain on the ridgeline formed by the two side surfaces 102c and 102d adjacent to the lower surfaces 102a and 102a of the metal film 103.

FIG. 6 shows a detailed state in which the residues 303 and 303a and 303b remain. FIG. 6A is an enlarged view of the vicinity of the top surface of step 303 in FIG. 3, and FIG. 6B is a top view thereof.
Further, even if the sacrificial layer 401 in step S401 in FIG. 4 is lifted off, the residue 403 remains as in step S403 in FIG. 4 by the same mechanism as described above. Further, due to a similar mechanism in which the residue 403 remains, residues 403a and 403b remain on the ridge line formed by the two side surfaces 102c and 102d adjacent to the lower side surfaces 102b and 102b of the metal film 104. FIG. 7A is an enlarged view of the vicinity of the top surface of step S403 in FIG. 4, and FIG. 7B is a top view thereof. FIG. 7C is a perspective view of step S403 in FIG. 4, and it can be seen that residues 303, 303a, 303b and residues 403, 403a, 403b remain.

  Next, FIG. 8 shows a method of removing residues 303, 303a, and 303b and residues 403, 403a, and 403b. Any one of the external forces P801 to P805 is applied from above and the side of the quadrangular frustum 102, and the residues 303, 303a, 303b and the residues 403, 403a, 403b are simultaneously plastically deformed and removed. Details of the residue removal method will be described below.

First, as shown in FIG. 9A, the residue 303 and residue 403 can be removed simultaneously by polishing in the D901 direction using an abrasive W901. Further, as shown in FIG. 9B, the residue 303, 303a, 303b and the residue 403, 403a, 403b are simultaneously removed by polishing in the direction D902 using an abrasive W902 surrounding the frustum 102. be able to. In that case, it can also carry out in the state immersed in acetone. By performing the above method and ultrasonic cleaning in parallel, the residues 303, 303a, and 303b and the residues 403, 403a, and 403b can be removed more efficiently. Further, when the polishing material W901 or W902 having a concavo-convex portion on the surface and the concavo-convex portion is softer than the quadrangular frustum 102, polishing can be performed without damaging the quadrangular frustum 102. Further, when the uneven portion of the quadrangular frustum 102 is made of fiber or porous, a further polishing effect can be obtained.
Further, as shown in FIG. 10A, from the upper side of the residues 303 and 403, an impact is applied in the direction of D1001 using W1001, and the residues 303 and 403 are formed into shapes like 1001 and 1002 in FIG. 10B. Plastically deform. Thereafter, the residue 303 and residue 403 can be removed simultaneously by adding ultrasonic cleaning.

  Further, as shown in FIG. 11 (a), solid particles such as dry ice S1101 are put into a quadrangular frustum 102 with a gas having a high pressure (predetermined pressure) such as spray cleaning of a CO2 gas jet (dry ice pellet). The residue 303, 303a, 303b and residue 403, 403a, 403b can also be removed by using a method of spraying in the direction D1101 from above. In addition, examples of the gas having the predetermined pressure include compressed air.

  In addition, it is preferable that the predetermined pressure of compressed air exists in the range of 8-14 atmospheres. Of course, depending on the size of the metal residue, the metal residue can be removed even if the predetermined pressure of the compressed air is outside the range.

  Further, as shown in FIG. 11B, a method is used in which solid particles such as dry ice S1101 are sprayed with a high-pressure gas from the direction D1101 having a predetermined angle from the extension line of the protrusions of the residue 303 and residue 403. The residue 303 and residue 403 can be easily removed. Further, when the predetermined angle is about 90 degrees, the force applied to the residue is maximized, and a further residue removal effect can be obtained. The method of spraying the solid particles having the predetermined angle can also be used for removing the residues 303a and 303b and the residues 403a and 403b.

  In the step of spraying solid particles with a gas having a predetermined pressure, other solid particles having a diameter different from the diameter of the solid particles may be sprayed with the passage of time. The other solid particles may be the same as or different from the type of solid particles sprayed first.

  The principle of CO2 gas jet spray cleaning is that dry ice particles of about −80 ° C. are caused to collide with the residues 303, 303a, 303b and residues 403, 403a, 403b from the nozzle by compressed air. At that time, the residue removal effect 1 by impact force and the residue removal effect 2 by the generation of microcracks are born by rapidly cooling the residue. Further, the residue removal effect 3 is further generated by generating expansion energy when the dry ice particles that have reached the interface of the residue are sublimated. The CO2 gas jet spray cleaning is a method that can remove only the residues 303, 303a, and 303b and the residues 403, 403a, and 403b without damaging the frustum 102 that is the target.

  Moreover, the residues 303, 303a, and 303b and the residues 403, 403a, and 403b due to the residue removal effects 2 and 3 can also be removed by spraying only the cooled high-pressure gas.

  FIG. 12 shows a state near the top surface after the residues 303, 303a, and 303b and the residues 403, 403a, and 403b are removed. 12A is an enlarged view of the vicinity of the top surface in step S404 in FIG. 4, and FIG. 12B is a top view of the vicinity of the top surface in step S404 of FIG. FIG. 12C is a perspective view of the vicinity of the top surface of step S404 in FIG. By removing the residues 303, 303a, and 303b and the residues 403, 403a, and 403b, the top surface 102e having the sizes d1 and g1 necessary for the near-field light generation of the near-field light generating element is manufactured as shown in FIG. be able to.

Further, even if the residues 303, 303a, and 303b and the residues 403, 403a, and 403b are not removed at the same time by using any one of the residue removal methods described above, as shown in FIGS. After removing the residues 303, 303a and 303b in S303, and removing the residues 403, 403a and 403b in step S403 of FIGS. 14A and 14B, the residues 303, 303a, 303b and 403, Each of 403a and 403b can be removed. By removing the residues 303, 303a, and 303b first, the sacrificial layer 401 can be easily and accurately formed in step S401 of FIG.
Further, by reducing the thickness of the sacrificial layer 301 and the sacrificial layer 401, the residues 303, 303a, and 303b and the residues 403, 403a, and 403b can be further reduced, and the residues 303, 303a, 303b, and the residues 403, 403a can be more easily formed. , 403b can be removed.

All the explanations in this embodiment are also valid for a frustum having a multi-sided surface other than a quadrangular pyramid. After the frustum having many side faces is manufactured by changing the mask pattern, the metal film forming method, residue removing method, and the like are substantially the same as the method using the square frustum.
In this embodiment, even if a plurality of square frustums 102 are formed on the substrate 101, they are convenient because they are not shaded when forming the metal film.

According to the feature of the present embodiment, the sharpness in the vicinity of the top surface of the two-surface metal film, which is the most important parameter of the bow-tie antenna type near-field light generating element, and the two-surface metal in the vicinity of the top surface The gaps in the film can be easily processed with sufficient accuracy without using extremely sophisticated fine processing techniques such as an electron beam drawing apparatus and a focused ion beam apparatus. Further, by forming a metal film on the frustum and then using a relatively low level metal film residue removing method, the sharpness and the gap can be easily reduced to several nanometers to several tens of nanometers.
In addition, since the metal film forming method and the means for removing the metal film residue are relatively simple, the yield is improved in the production of the near-field light generating element, and mass production at a low cost is possible.
Also, the removal efficiency of the incident light improves the light collection efficiency of the incident light, thereby improving the S / N ratio and generating stronger near-field light. The improvement of the light collection efficiency means that near-field light can be generated even with relatively weak incident light, and power consumption is reduced.

(Embodiment 2)
FIG. 15 is a cross-sectional view showing the method for manufacturing the near-field light generating element in the second embodiment of the present invention. The present embodiment is similar to the first embodiment except that a metal film is used instead of the resin film as the sacrificial layer. Details are described below. The shape of the near-field light generating element to be manufactured is almost the same as that shown in FIG. FIG. 15 is a cross-sectional view showing a method of forming a metal film on the side surface 102 a of the quadrangular frustum 102. The left side of FIG. 15 shows a cross section A 1 and the right side of FIG. First, the quadrangular frustum 102 is formed on the substrate 101 by the same method as in the first embodiment. That is, the same processing is performed up to step S203 in FIG.

  Next, as shown in step S1501, a sacrificial layer 1501 is formed on the side surface 102b from the direction D1501 perpendicular to the side surface 102b by using a film forming method having directivity such as a vacuum evaporation method. At this time, the sacrificial layer 1501 is formed not only on the side surface 102b but also on the side surfaces 102c and 102d and the top surface 102e adjacent to the side surface 102b. The sacrificial layer 1501 is not formed on the side surface 102a facing the side surface 102b because it is shaded by the directivity of the film formation method. The sacrificial layer 1501 is made of an Al film, and the film thickness is several nm to several hundred nm.

  Next, as shown in step S1502, a metal film 1502 is formed on the side surface 102a from a direction D1502 perpendicular to the side surface 102a by using a metal film forming method having directivity such as a vacuum deposition method. At this time, the metal film 1502 is formed not only on the side surface 102 a but also on a part of the sacrificial layer 1501.

  Next, as shown in step S1503, the sacrificial layer 1501 is peeled off. At this time, the metal film 1502 placed on the sacrificial layer 1501 is also peeled off, leaving only the metal film 1502 placed on the side surface 102a. Further, the residue 1503 on the top surface 102e side of the metal film 1502 and the residues 1503a and 1503b in FIG. For removing the sacrificial layer 1501, an aqueous solution containing phosphoric acid as a main component is used.

  Next, FIG. 16 is a cross-sectional view showing a method of forming a metal film on the side surface 102b of the quadrangular frustum 102. FIG. As shown in step S1601, a sacrificial layer 1601 is formed on the side surface 102a from a direction D1601 perpendicular to the side surface 102a by using a film forming method having directivity such as a vacuum evaporation method. At this time, the sacrificial layer 1601 is formed not only on the side surface 102a but also on the side surfaces 102c and 102d and the top surface 102e adjacent to the side surface 102a. The sacrificial layer 101 is not formed on the side surface 102b facing the side surface 102a because it is shaded by the directivity of the film forming method. The sacrificial layer 1601 is made of an Al film and has a thickness of several nm to several hundred nm.

  Next, as shown in step S1602, a metal film 1602 is formed on the side surface 102b from the direction D1602 perpendicular to the side surface 102b by using a metal film forming method having directivity such as a vacuum deposition method. At this time, the metal film 1602 is formed not only on the side surface 102 b but also on a part of the sacrificial layer 1601.

  Next, as shown in step S1603, the sacrificial layer 1601 is lifted off using an aqueous solution containing phosphoric acid as a main component. At this time, the metal film 1602 placed on the sacrificial layer 1601 is also peeled off, leaving only the metal film 1602 placed on the side surface 102a. Further, the residue 1603 is left on the top surface 102e side of the metal film 1602, and the residues 1603a and 1603b in FIG.

  Next, as shown in S1603 as the last step, the residues 1503, 1503a, 1503b and residues 1603, 1603a, 1603b are removed, so that the metal film 103 and the metal film 104 of the near-field light generating element in step S1604 are removed. Is processed.

  The mechanism in which the residues 1503, 1503a, and 1503b and the residues 1603, 1603a, and 1603b remain in Embodiment 2 is substantially the same as the mechanism in which the residues 303 and 403 remain in Embodiment 1, and thus description thereof is omitted.

  The method for removing the residues 1503, 1503a, and 1503b and the residues 1603, 1603a, and 1603b is the same as the method described in Embodiment 1. By removing the residue, it is possible to manufacture the top surface 102e having the sizes d1 and g1 necessary for the near-field light generation of the near-field light generating element which is almost the same as that shown in FIG. Further, by using an abrasive having substantially the same surface characteristics and materials as the abrasives W901 and W902 described in Embodiment 1, the residues 1503, 1503a and 1503b and the residues 1603, 1603a and 1603b can be efficiently removed. Can do.

  Further, when the thickness of the sacrificial layer 1501 and the sacrificial layer 1601 is 5 nm or less, the removal degree of the residue 1503 and the residue 1603 is improved, but it takes a long time to peel off the sacrificial layer 1501 and the sacrificial layer 1601, and the efficiency is improved. bad. Conversely, when the thickness of the sacrificial layer is 500 nm or more, the sacrificial layer 1501 and the sacrificial layer 1601 are peeled off in a short time, but the removal degree of the residue 1503 and the residue 1603 is deteriorated. When the thickness of the sacrificial layer 1501 and the sacrificial layer 1601 is about 100 nm, the sacrificial layer 1501 and the sacrificial layer 1601 can be peeled off in a relatively short time, and the degree of removal of the residue 1503 and the residue 1603 is improved.

All the explanations in the present embodiment are also effective for a frustum having multiple side surfaces other than a square frustum.
In this embodiment, in addition to the effects of the first embodiment, a sacrificial layer is formed by using a metal film forming method such as a vacuum evaporation method. Therefore, the sacrificial layer is sacrificed as compared with the resin sacrificial layer forming method of the first embodiment. Control of the film thickness and directivity of the layer is easily performed. In addition, since the sacrificial layer can be formed more accurately in the production of a plurality of near-field light generating elements, the accuracy of forming the metal film is improved, and the size of the residue and the control for reducing it are reduced. Is relatively easy, and further yield improvement effects can be obtained.

(Embodiment 3)
In the third embodiment, a plurality of quadrangular pyramids are manufactured by the same method as in the first or second embodiment, a metal film is formed on both sides facing each other, and then the top surfaces of the plurality of quadrangular pyramids are formed. A method for removing the residue of the metal film remaining on the side surface will be described.

  As shown in FIG. 17 (a) by the same method as in FIG. 9, polishing is performed in the direction D1701 using an abrasive W1701, so that residues remaining on the side surface and the top surface of the plurality of near-field light generating elements. 303 and residue 403 can be removed simultaneously.

  Further, as shown in FIG. 17B, by using a polishing material W1702 surrounding the frustum 102 and polishing in the direction D1702, it remains on the side surface and the top surface of the plurality of near-field light generating elements. The remaining residues 303, 303a and 303b and the remaining residues 403, 403a and 403b can be removed simultaneously.

  Further, as a method of removing the metal film residue, as shown in FIG. 18 in the same manner as in FIG. 10, by applying an impact in the direction of D1802 using W1802, the top surface of the plurality of near-field light generating elements can be removed. The remaining residue 303 and residue 403 can be removed simultaneously.

  By removing the residues 303, 303a, and 303b and the residues 403, 403a, and 403b using the residue removal method described above, the peaks having the sizes d1 and g1 necessary for the near-field light generation of the plurality of near-field light generating elements are obtained. The surface 102e can be manufactured. FIG. 19 shows a cross-sectional view after removing the residues 303, 303a, 303b and residues 403, 403a, 403b of a plurality of near-field light generating elements.

  In the present embodiment, in addition to the effects of the first and second embodiments, a plurality of metal film residues can be removed simultaneously in the manufacture of the near-field light generating element, so that the manufacturing efficiency of the near-field light generating element can be further improved. Is suitable for mass production.

(Embodiment 4)
In the fourth embodiment, in the residue removal method using the abrasive in the first, second, and third embodiments, as shown in FIG. 20, the frictional resistance F2002 against the catch between the abrasive W2001 and the residues 303 and 403 is resisted. Measurement is performed by a measuring instrument M2003. Next, the frictional resistance measurement value F2002a is given to the controller M2004, and the controller M2004 controls the force F2006 that moves the abrasive W2001 by the actuator M2005, so that the polishing can be performed while feeding back F2002 and F2006 until the polishing is completed. it can. When the residue removal method is used, the degree of residue removal can be monitored, and therefore residue removal can be further quantitatively and efficiently performed. It is also suitable for mass production. Further, by using W902 in FIG. 9B as an abrasive, the degree of removal of the residue is monitored by the same method as described above in removing the residues 303a and 303b and residues 403a and 403b in FIG. And the same effect can be obtained.

  Here, the frictional resistance F2002 between the residues 303a, 303b, 403a, and 403b and the abrasive W2001 decreases as the residues 303a, 303b, 403a, and 403b decrease due to the abrasive W2001. For this reason, the controller M2004 stops the operation of the actuator M2005 when the frictional resistance F2002 measured by the resistance measuring device M2003 reaches a predetermined value.

  Accordingly, the residues 303a, 303b, 403a, and 403b can be appropriately removed and the other portions can be prevented from being cut, and an opening capable of generating near-field light can be more reliably formed at the tip portion of the frustum 102. Can be provided.

  The above method is also effective for removing metal film residues from a plurality of near-field light generating elements.

(Embodiment 5)
In the fifth embodiment, any one of the residue removal methods described in the first, second, and third embodiments and the residue removal method described below can be performed in parallel.

  As shown in FIG. 21, the laser light L2102 from the light source M2101 is passed through the lens M2103, and the condensed light L2104 is incident on the substrate 101. Next, the light L2105 transmitted from the top surface 102e is collected by the lens M2106. Next, the transmittance R2109 of the detection light L2107 calculated by the light transmittance measurement device M2108 is given to the controller M2110, and the laser light L2102 from the light source M2101 is controlled, so that the laser light L2102 and the detection light L2107 are used until the polishing is completed. The residues 303, 303a, and 303b and the residues 403, 403a, and 403b can be removed while feeding back.

  When the residue removal method is used, the degree of removal of the residue can be monitored, so that the residue removal can be further quantitatively and efficiently performed. It is also suitable for mass production. The above method is also effective for removing metal film residues from a plurality of near-field light generating elements.

  Here, when the calculated transmittance R2109 reaches a predetermined value, the controller M2110 stops polishing the residues 303, 303a, 303b, 403, 403a, and 403b. Accordingly, the residues 303, 303a, 303b, 403, 403a, and 403b can be appropriately removed and the other portions can be prevented from being scraped, and an opening capable of generating near-field light at the tip portion of the frustum 102 Can be provided more reliably.

101 Substrate 102 Square Frustum 102a Side 102b Side 102c Side 102d Side 102e Side 103 Metal Film 104 Metal Film 201 Etching Mask 301 Sacrificial Layer D301 Direction perpendicular to Side 102b 302 Metal Film D302 Direction perpendicular to Side 102a D303 Observation direction 302a of side surface 102a Metal film 302e Residual layer 401 of metal films 303, 303a, 303b Sacrificial layer D401 Direction perpendicular to side surface 102a 402 Metal film D402 Direction perpendicular to side surface 102b D403 Observation direction 403, 403a of side surface 102a , 403b Residue P801 External force P802 External force P803 External force P804 External force P805 External force W901, W902 Abrasive material D901 Polishing direction W1001 Impact material D1001 Impact direction D1101 External force direction S1101 Solid Child 1501 Sacrificial layer D1501 Direction perpendicular to side surface 102b 1502 Metal film D1502 Direction perpendicular to side surface 102a 1502a Metal film 1502e Metal film 1503, 1503a, 1503b Residual layer 1601 Sacrificial layer D1601 Direction perpendicular to side surface 102a 1602 Metal film D1602 Vertical direction 1603, 1603a, 1603b with respect to side surface 102b Remnants W1701, W1702 Abrasive material D1701, D1702 Polishing direction W1801 Impact material D1801 Impact direction W2001 Abrasive material F2002 Friction resistance M2003 Resistance measurement device F2002a Friction resistance measurement value M2004 Controller M2005 Actuator F2006 Force M2101 for moving abrasive W2001 Light source L2102 Laser light M2103 Lens L2104 Condensed light L2 05 transmitted light M2106 lens L2107 detection light M2108 light transmittance measuring instrument R2109 transmittance M2110 controller

Claims (20)

A manufacturing method of a near-field light generating element that has a frustum having a polygonal shape and generates near-field light from an opening formed at a tip of the frustum,
Forming a metal film on a side surface of the frustum; and applying an external force to the residue of the metal film remaining on the side surface and the top surface of the frustum after the metal film is formed. And a residue removal step of removing the residue by the method of manufacturing a near-field light generating element.   The method of manufacturing a near-field light generating element according to claim 1, wherein the residue removing step includes a step of polishing and removing the residue using an abrasive.   The residue removal step is characterized by removing the residue by ultrasonic cleaning after applying an impact by the external force to the residue remaining on the top surface to plastically deform the residue. Item 2. A method for producing a near-field light generating element according to Item 1.   2. The method of manufacturing a near-field light generating element according to claim 1, wherein the residue removal step removes the residue by spraying a gas having a predetermined pressure on the residue.   The method of manufacturing a near-field light generating element according to claim 1, wherein the residue removing step removes the residue by spraying solid particles with a gas having a predetermined pressure on the residue.   The method of manufacturing a near-field light generating element according to claim 2, wherein the residue removal step comprises polishing the residue in a state where the metal film is immersed in a solution.   The method of manufacturing a near-field light generating element according to claim 2, wherein the residue removing step performs ultrasonic cleaning after the polishing is started.   The step of spraying the solid particles with the gas having the predetermined pressure includes a step of spraying other solid particles having a diameter different from the diameter of the solid particles with time. The manufacturing method of the near-field light generating element of description. The frictional resistance between the abrasive and the residue is reduced as the residue is reduced by the abrasive.
The near field according to any one of claims 2, 6, and 7, wherein, in the polishing step, the frictional resistance is measured, and the residue is polished until the measured frictional resistance reaches a predetermined value. Manufacturing method of a light generating element.   The method for manufacturing a near-field light generating element according to claim 2, wherein the abrasive has a concavo-convex portion on a surface thereof, and the concavo-convex portion is made of a member softer than the frustum. .   The method of manufacturing a near-field light generating element according to claim 10, wherein the member is made of a fiber.   The method of manufacturing a near-field light generating element according to claim 10, wherein the member is made of a porous material. The said residue removing step removes the residues remaining on each of the two side surfaces after forming the metal film on the two opposite side surfaces of the frustum at the same time.

A method for producing a near-field light generating element according to any one of 1 to 5 and 7.   The residue removing step first removes the residue left after forming the metal film on one of the two opposite sides of the frustum, and then remains after forming the metal film on the other side. The method of manufacturing a near-field light generating element according to claim 1, wherein the residue is removed.   The frustum includes a plurality of frustums, and a metal film is formed on two opposite side surfaces of the frustums, and then the residue remaining on each of the frustums is simultaneously removed. The manufacturing method of the near-field light generating element of Claim 1 characterized by these.   The method of manufacturing a near-field light generating element according to claim 1, wherein the metal film is made of Au 2.   The method for manufacturing a near-field light generating element according to claim 5, wherein the solid particles are made of dry ice powder. The forming step includes
Forming a sacrificial layer on the first side of the frustum and the other side of the frustum except the second side facing the first side; the second side; Forming a base material of the metal film on at least a part of the sacrificial layer; and removing the base material on the sacrificial layer and the sacrificial layer after forming the base material. The method of manufacturing a near-field light generating element according to claim 1.   The method of manufacturing a near-field light generating element according to claim 18, wherein the sacrificial layer is made of a metal.   The method of manufacturing a near-field light generating element according to claim 18, wherein the sacrificial layer has a thickness of 5 nm to 500 nm.

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