JP4645309B2 - Method for producing three-dimensional photonic crystal and substrate for producing three-dimensional photonic crystal - Google Patents

Description

  The present invention is used as an optical waveguide, an optical resonator, a near-field optical probe, a birefringence element, a filter, a branch element, a wavefront conversion element, and a deflection element in the fields of optical communication, optical interconnection, optoelectronics, and optical measurement. The present invention relates to a method for manufacturing a three-dimensional structure including a diffraction optical element, a multilayer film having a periodic structure, a photonic crystal, and the like, and a substrate for manufacturing the three-dimensional structure.

  It is conventionally known that a medium having a periodic structure with a refractive index distribution having a pitch comparable to the wavelength of light has unique light propagation characteristics. As a one-dimensional periodic structure, a dielectric multilayer film has been known for a long time, and its design theory and fabrication technology are already mature fields. On the other hand, a method of controlling spontaneous emission in a semiconductor device using a medium having a three-dimensional periodic structure with a pitch similar to the wavelength of light has been proposed by Yablonovitch in 1987. Or, the behavior of light in a three-dimensional periodic structure medium has attracted attention. In such a medium, light having a wave vector in a specific range is prohibited from propagating, and a photonic band similar to the energy band of electrons in a semiconductor is formed. A periodic refractive index structure that forms a photonic band is called a photonic crystal.

  When such a photonic band is used, unprecedented control of photons becomes possible, and various applications are expected. Already a low threshold or no threshold laser by controlling spontaneous emission light, an optical waveguide using the property that light is localized around lattice defects in a photonic crystal, and also highly efficient μm using the localization of light Applications to ultra-small optical resonators of the order and elements with a new prism function that change the deflection angle greatly by minute changes in wavelength and incident angle have been proposed.

  These optical elements have various optical functions such as light emission control, propagation control, prism action, filter action, optical waveguide, etc. by themselves. Various electronic and optical functions will be developed.

  In the photonic crystal, the three-dimensional photonic crystal is most desirable as a structure that can obtain the most photonic band effect. Also in a three-dimensional photonic crystal, it is desirable that a complete photonic band gap can be obtained and a defect can be inserted into the three-dimensional photonic crystal relatively easily and freely. A method for manufacturing a three-dimensional structure for efficiently manufacturing such a three-dimensional photonic crystal has been proposed in Patent Document 1, for example. In this method, a plurality of cross-sectional shape members corresponding to a slice pattern of a three-dimensional (periodic) structure body held in the air via a holding member on a first substrate (donor substrate) are converted into a second substrate (target substrate). ) And sequentially laminating them by bonding and transferring them.

In this method, at the time of joining each cross-sectional member, (1) the target substrate is pressed against the donor substrate including the cross-sectional member, (2) the cross-sectional member is joined to the target substrate, and (3) the target substrate The joined cross-sectional member is pulled up, whereby the connecting member constituting the holding member is broken, so that the cross-sectional member is separated from the donor substrate and transferred to the target substrate. By repeating these steps, a plurality of cross-sectional members are sequentially stacked on the target substrate. The advantage is that the cross-sectional shape member is held on the target substrate in a plane (two-dimensional), and a plurality of cross-sectional shape members are sequentially stacked on the target substrate. The laminating process can be performed continuously with simple position correction, which is extremely efficient.
JP 2004-347788 A

However, in the method of Patent Document 1, the connecting member that constitutes the holding member is not necessarily broken in the step (3). Depending on the size of the cross-sectional shape member, the shape of the connecting member, and the like ( There is a risk of breakage in the process of 1). As described above, the rupture of the connecting member other than the step (3) causes a problem in that the yield is deteriorated due to misalignment or incomplete joining (transfer) at the time of joining the cross-sectional members.
In addition, when room temperature bonding is used, the bonding surface is subjected to FAB (Fast Atom Beam) treatment (irradiation) for the purpose of surface cleaning as a step before bonding the donor substrate and the target substrate. When the member has a shape including holes such as a lattice shape, the FAB passes through the holes, and the substrate under the cross-sectional shape member is simultaneously cleaned. For this reason, at the time of joining of the cross-sectional member, the cross-sectional member may not be joined to the target substrate but may be joined to the substrate below the cross-sectional member.
Also in the production of the donor substrate itself, during the process of producing the donor substrate, and during handling until the donor substrate is bonded to the target substrate (operation for introducing the substrate into the chamber, carrying it, cleaning the substrate, etc.) There is a problem that the yield of the donor substrate itself is deteriorated such that the shape member comes into contact with the lower substrate, the gap between the cross-sectional shape member and the lower substrate cannot be maintained, and the connecting member is broken.

Accordingly, an object of the present invention is to provide a three-dimensional photonic crystal manufacturing method and three-dimensional photonic crystal fabrication substrate that can improve the yield of the three-dimensional photonic crystal fabrication.

Above object, a plurality of cross-sectional shape member in accordance with the slice pattern of retained three-dimensional structure via the holding member on the first substrate, laminating sequentially joined transferred onto the second substrate In the method of manufacturing a three-dimensional photonic crystal comprising 3, an inclusion for preventing breakage of the holding member at the time of joining the cross-sectional members is provided between the first substrate and the cross-sectional member 3 This is achieved by a method for manufacturing a two-dimensional photonic crystal .

  Here, the inclusion is preferably made of a material that can be removed by post-processing, and the material that can be removed by post-processing is, for example, a photoresist. Moreover, it is preferable that joining of the said cross-sectional shape member is performed by normal temperature joining. Room temperature bonding is a method in which the oxide films and impurities on the surfaces of the members to be joined in vacuum are removed and cleaned by FAB treatment, etc., and then these clean surfaces are brought into contact with each other to join the members. It is.

A method of manufacturing three-dimensional photonic crystal according to the present invention, the step of forming a plurality of cross-sectional shape member in accordance with the slice pattern of retained three-dimensional structure via the holding member on the first substrate And a step of arranging an inclusion for preventing breakage of the holding member at the time of joining the cross-sectional shape member in a subsequent step between the first substrate and the cross-sectional shape member, And sequentially laminating and transferring on the two substrates.

  Here, the step of disposing the inclusions may include a step of applying a material of the inclusions on the first substrate and a step of curing the applied material. Furthermore, when the applied material covers a part or all of at least one of the holding member and the cross-sectional shape member, a step of removing the covering material can be included. The applied material can be, for example, a photoresist, and in this case, the removing step can include ashing. Ashing means ashing with oxygen plasma or the like to remove unnecessary photoresist.

Further, the present invention is a substrate for manufacturing a three-dimensional photonic crystal used in a method for manufacturing a three-dimensional photonic crystal comprising a step of sequentially joining and transferring a plurality of cross-sectional members and laminating the substrate, and the substrate and the substrate a plurality of cross-sectional shape member in accordance with the slice pattern of retained three-dimensional structure via the holding member, the at the time of bonding of the cross-sectional shape member provided between the substrate and the cross section member And an inclusion for preventing breakage of the holding member. Here, the inclusion may be made of a material that can be removed by post-processing. The material that can be removed by the post-treatment is, for example, a photoresist.

According to the present invention, it is possible to obtain a three-dimensional photonic crystal manufacturing method and three-dimensional photonic crystal fabrication substrate that can improve the yield of the three-dimensional photonic crystal fabrication. As a result, it is possible to manufacture a three-dimensional photonic crystal efficiently based on a free design while reducing the constraints on the constituent materials.

  Examples of the present invention will be described below. In this embodiment, a so-called woodpile type three-dimensional photonic crystal is produced as a three-dimensional structure. This three-dimensional photonic crystal is formed by laminating a plurality of air bridge structure patterns made of one kind of thin film material and air or vacuum while shifting the position in the lateral direction.

  1A and 1B are diagrams showing a pattern member used in the method for manufacturing a three-dimensional structure according to the present invention. FIG. 1A shows a pattern member before processing, and FIG. 1B shows a pattern member after processing. As shown in FIG. 1A, this multilayer film is made of InP / InGaAs / InP, and an InGaAs spacer layer 11 (sacrificial layer) and an InP layer 12 are formed on an InP substrate as the first substrate 10 by MOCVD. It is obtained by growing sequentially by the method. A pattern member (donor substrate) 15 having a cross-sectional shape member is manufactured from the InP / InGaAs / InP multilayer film using a semiconductor microfabrication process as follows. As shown in FIG. 1B, first, a plurality of cross-sectional members 1 having a two-dimensional microstructure are formed on the MOCVD-grown InP layer 12 by electron beam exposure and dry etching. At this time, the connecting member 2 connected to the cross-sectional member 1 and the frame-like member 3 for holding the cross-sectional member 1 via the connecting member 2 are simultaneously produced. The connecting member 2 and the frame-like member 3 constitute a holding member 7 for the cross-sectional member 1. The direction of the stripe pattern of the cross-sectional shape member is formed so as to be orthogonal to each other, whereby two types of patterns respectively arranged so as to develop each layer of the photonic crystal are produced on the first substrate. Next, the InGaAs spacer layer 11 under the cross-sectional shape member 1 and the connecting member 2 is removed by undercut etching. Thereby, the cross-sectional shape member 1 is held in the air by the frame-shaped member 3 via the connecting member 2.

  2A and 2B are diagrams illustrating an example of a holding state of the cross-sectional shape member, where FIG. 2A is a plan view, FIG. 2B is a cross-sectional view taken along line AB in FIG. 2A, and FIG. is there. As shown in FIG. 2A, the stripe pattern of the cross-sectional shape member 1 of this example is formed so as to be orthogonal to each other. The frame-shaped member 3 includes a columnar portion 4 and a frame portion 5, and is sufficient to the extent that the underlying InGaAs layer 11 is not completely lost in the under-etching process (the columnar portion 4 remains) as shown in FIG. It has a wide width. Moreover, as shown in FIG.2 (c), the connection member 2 has the connection part 6 with the cross-sectional shape member 1 tapered. This is because the cross-sectional shape member 1 is easily separated from the connecting portion 2.

  FIGS. 3A to 3D illustrate an example of a method of providing an inclusion for preventing breakage of the holding member at the time of joining the cross-sectional members between the first substrate and the cross-sectional member. FIG. As the inclusion in this example, a material that can be removed by post-processing, for example, a resin such as a photoresist is used. The resin such as photoresist is removed by ashing, for example. Hereinafter, this method will be described in detail.

  First, as shown in FIG. 3A, the donor substrate 15 includes a first substrate 10, a spacer layer 11, a cross-sectional member 1 having a two-dimensional microstructure, a holding member 2, and a frame-shaped member 3. A member 7 is provided. As shown in the figure, a gap 90 is formed between the first substrate 10 and the cross-sectional shape member 1. On the donor substrate 15, as shown in FIG. 3B, a resin 91 such as a photoresist is applied so as to fill the gap 90 below the cross-sectional shape member 1. Thereby, as shown in FIG. 3C, the lower space of the cross-sectional member 1 is filled with the resin 91. Next, the resin 91 is cured by baking the donor substrate. Thereafter, as shown in FIG. 3D, the cured resin covering the cross-sectional shape member 1 and the connecting member 2 is removed by performing ashing 92 using, for example, oxygen plasma. Thereby, inclusions 93 are formed between the first substrate 10 and the cross-sectional shape member 1. Here, when the application amount of the resin 91 is adjusted in advance and the resin 91 does not cover the cross-sectional shape member 1 and the connecting member 2, the ashing step of FIG.

  As described above, by forming the inclusions 93 using the steps shown in FIG. 3, the gap 90 below the cross-sectional shape member 1 is eliminated or reduced. Thereby, the bending of the connection member 2 at the time of joining of the cross-sectional shape member 1 can be eliminated, or a bending can be made small. In this way, the first substrate 10, the plurality of cross-sectional members 1 corresponding to the slice pattern of the three-dimensional structure held in the air via the holding member on the substrate, the first substrate 10 and the cross section Producing a donor substrate 15 as a three-dimensional structure manufacturing substrate provided with an inclusion 93 for preventing breakage of a holding member at the time of joining a cross-sectional shape member provided between the shape member 1 and it can.

  FIG. 4A is a diagram showing an example of a manufacturing apparatus used in the method for manufacturing a three-dimensional structure according to the present invention, and FIG. 4B is a diagram showing an example of a woodpile type three-dimensional photonic crystal produced thereby. It is.

  As shown in FIG. 4A, the manufacturing apparatus 30 has a vacuum chamber 300 in which a lamination process is performed, and a pattern member (donor substrate) as shown in FIG. 15, a substrate holder 301 on which the substrate 15 is placed, a stage 302 that holds a second substrate (target substrate) 60 onto which the cross-sectional member 1 formed on the pattern member 15 is transferred, and a stage 302 that is attached to the stage 302. The first FAB source 303A that performs FAB processing on the 302 side, the second FAB source 303B that performs FAB processing on the pattern member 15 side, and the stage 302 are moved in the X-axis direction (left-right direction in the figure) by an X-axis motor (not shown). ) To move the stage 302 and the Y-axis table 320 to move the stage 302 in the Y-axis direction (perpendicular to the drawing in the drawing) by a Y-axis motor (not shown). There has been arranged. Note that the first and second FAB sources 303A and 303B, after the FAB processing is completed, retreat the arm by rotating about 90 ° in the direction of the arrow in the drawing by a retraction motor. Here, “FAB treatment” refers to accelerating, for example, argon gas as a particle beam at a voltage of about 1 kV and irradiating the surface of the material to remove an oxide film, impurities, etc. on the surface of the material to form a clean surface. Refers to processing. In the present embodiment, the irradiation conditions of FAB can be changed, for example, in the range of an acceleration voltage of 1 to 1.5 kV and an irradiation time of 1 to 10 minutes depending on the material to be processed.

  Further, the manufacturing apparatus 30 includes a Z-axis table 330 that moves the substrate holder 301 in the Z-axis direction (vertical direction in the drawing) by a Z-axis motor (not shown) outside the vacuum chamber 300, and the alignment adjustment. And a θ table 340 for rotating the substrate holder 301 around the Z axis by a θ motor, and an argon gas cylinder 351 for supplying argon gas to the first and second FAB sources 303A and 303B.

  FIG. 4B is a diagram illustrating an example of a woodpile type three-dimensional photonic crystal. The three-dimensional photonic crystal 40 of this example includes a plurality of cross-sectional members 1 a, 1 b, 1 c, 1 d... On a substrate (not shown) so that the stripe pattern directions are orthogonal to each other. ). Hereinafter, the production method according to the present invention will be described in detail.

  FIGS. 5A to 5G are views showing an embodiment of a method for manufacturing a three-dimensional structure according to the present invention. First, as shown in FIG. 5A, a pattern member 15 in which a plurality of cross-sectional members 1 are formed is used as a donor substrate in room temperature bonding, and this donor substrate 15 is opposed to a second substrate (target substrate) 60. It installs in the manufacturing apparatus 30 like this. A plurality of cross-sectional members 1 are formed, but one of them is shown in the figure. On the other hand, the target substrate 60 has a mesa portion 61 on the donor substrate 15 side. In this case, the target substrate 60 is made of InP for both mesa portions. In addition, when the three-dimensional structure formed after the lamination of the cross-sectional members is desired to be removed from the target substrate, InGaAs is deposited as a sacrificial layer on the target substrate having a mesa shape made of InP by MOCVD. Also good. By doing so, it is possible to remove the three-dimensional structure from the target substrate by etching only InGaAs after the completion of the lamination. The height of the mesa portion 61 from the flat portion of the target substrate 60 is, for example, about 15 μm. The top of the mesa portion 61 is flat and has an area that is the same as or slightly larger than that of one of the cross-sectional members 1.

  Both surfaces of the opposing donor substrate 15 and target substrate 60 are cleaned by FAB treatment (irradiation with ion beam or the like) 16A, 16B. Next, both are aligned, and the target substrate 60 is moved and brought into contact with the cross-sectional shape member 1 of the donor substrate 15 (pattern member). At this time, as shown in FIG. 5B, the target substrate 60 is kept pressed against the cross-sectional shape member 1. Accordingly, the cross-sectional shape member 1 is pressed against the target substrate 60 by using the drag generated when the cross-section member 1 presses against the target substrate 60 and the above-described inclusions 93 and is bonded at room temperature.

  Here, the presence of the inclusions 93 eliminates or reduces the gap at the bottom of the cross-sectional member 1. For this reason, it is possible to prevent a positional shift caused by the bending of the connecting member 2 when the cross-sectional shape member 1 is joined, and an unexpected breakage of the connecting member, and to improve the yield in manufacturing the three-dimensional structure. Moreover, since it is possible to prevent FAB irradiation to the 1st board | substrate 10, it can prevent joining to the 1st board | substrate 10 in the joining process of the cross-sectional shape member 1. FIG. Here, the FAB is also irradiated to, for example, the cured resin as the inclusion 93, but the bonding at the room temperature bonding between the cross-sectional shape member and the cured resin is less likely to occur than the room temperature bonding to the lower substrate. This can also be expected to improve yield.

  In addition, by joining the cross-sectional members 1 at room temperature, it is not necessary to join the cross-sectional members using annealing fusion or the like, and a simple and strong joint can be obtained. Furthermore, since normal temperature bonding does not require heating, it is possible to simply bond materials having different coefficients of thermal expansion.

  After that, as shown in FIG. 5C, the cross-sectional member 1 bonded to the target substrate 60 is pulled up, thereby breaking the connecting member 2 and separating the cross-sectional member 1 from the donor substrate 10. Next, the target substrate 60 is moved to repeat these steps. That is, as shown in FIGS. 5D to 5F, the cross-sectional member 1 is bonded and transferred onto the target substrate 60 so that the stripe patterns are orthogonal to each other. Further, these steps are alternately repeated to produce a three-dimensional photonic crystal 40 as shown in FIG. In this embodiment, the target substrate 60 is moved when the cross-sectional members 1 are stacked. However, the donor substrate 15 may be moved.

  In this embodiment, the top of the mesa of the target substrate 60 has an area that is approximately the same as or slightly larger than that of one of the cross-sectional members 1, but when the target substrate 60 is pressed against the donor substrate 15, the donor substrate 15 is between the columnar portions 4. In this case, when the target substrate 60 and the columnar part 4 do not interfere with each other, the plurality of cross-sectional members can be transferred in one bonding transfer step. Therefore, the area of the top of the mesa portion of the target substrate 60 can be increased, and workability can be improved simultaneously with mass production.

  As described above, the method for manufacturing a three-dimensional structure according to the present invention forms a plurality of cross-sectional shape members according to the slice pattern of the three-dimensional structure held in the air via the holding member on the first substrate. A step, a step of disposing an inclusion for preventing breakage of the holding member at the time of joining the cross-sectional member in the subsequent step, between the first substrate and the cross-sectional member, and the cross-sectional member as the second substrate And sequentially laminating by bonding and transferring. The step of disposing the inclusion includes a step of applying a material of the inclusion on the first substrate and a step of curing the applied material. Further, when the applied material covers a part or all of at least one of the holding member and the cross-sectional shape member, a step of removing the covering material is included. Here, the applied material is, for example, a photoresist, and the step of removing it includes, for example, ashing.

  As described above, in the present invention, by filling the gap below the cross-sectional shape member with inclusions such as resist and polyimide, the gap can be eliminated or the size thereof can be reduced. Deflection of the connecting member during joining can be reduced. Further, since the FAB is not irradiated to the lower substrate due to the inclusions, it is possible to prevent the cross-sectional member and the lower substrate from being joined. Thereby, the manufacturing yield of the three-dimensional structure is improved.

  The present invention is used as an optical waveguide, an optical resonator, a near-field optical probe, a birefringence element, a filter, a branch element, a wavefront conversion element, and a deflection element in the fields of optical communication, optical interconnection, optoelectronics, and optical measurement. The present invention relates to a method for manufacturing a three-dimensional structure including a diffraction optical element, a multilayer film having a periodic structure, a photonic crystal, and the like, and a substrate for manufacturing a three-dimensional structure, and has industrial applicability.

It is a figure which shows the pattern member used for the manufacturing method of the three-dimensional structure which concerns on this invention, (a) is before a pattern member process, (b) is a figure which shows after a pattern member process. It is a figure which shows an example of the holding | maintenance state of a cross-sectional shape member, (a) is a top view, (b) is AB sectional drawing in (a), (c) is the partially expanded view of (a). (A)-(d) is a figure for demonstrating an example of the method of providing the inclusion for preventing the fracture | rupture of a holding member at the time of joining of a cross-sectional shape member between a 1st board | substrate and a cross-sectional shape member. is there. (A) is a figure which shows an example of the manufacturing apparatus used for the manufacturing method of the three-dimensional structure which concerns on this invention, (b) is a figure which shows an example of the woodpile type | mold three-dimensional photonic crystal produced by this. . (A)-(g) is a figure which shows one Example of the manufacturing method of the three-dimensional structure which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Section shape member 2 Connection member 3 Frame-shaped member 4 Column-shaped part 5 Frame part 6 Connection part 7 Holding member 10 1st board | substrate 15 Pattern member 40 3D photonic crystal 60 2nd board | substrate 90 Cavity 91 Resin 92 Ashing 93 Interposition object

Claims (12)

A plurality of cross-sectional shape member in accordance with the slice pattern of retained three-dimensional structure via the holding member on the first substrate, a three-dimensional with a step of laminating sequentially joined transferred onto the second substrate In the photonic crystal manufacturing method, an inclusion for preventing breakage of the holding member at the time of joining of the cross-sectional members is provided between the first substrate and the cross-sectional member. A method for producing a three-dimensional photonic crystal . The method for producing a three-dimensional photonic crystal according to claim 1, wherein the inclusion is made of a material that can be removed by post-processing. 3. The method for producing a three-dimensional photonic crystal according to claim 2, wherein the material that can be removed by the post-treatment is a photoresist. The method for producing a three-dimensional photonic crystal according to any one of claims 1 to 3, wherein the joining of the cross-sectional members is performed by room temperature joining. Forming a plurality of cross-sectional shape member in accordance with the slice pattern of retained three-dimensional structure via the holding member on the first substrate, the holding member during the bonding of the cross-shaped member in a subsequent step A step of disposing an inclusion for preventing breakage between the first substrate and the cross-sectional shape member; and a step of sequentially bonding and transferring the cross-sectional shape member onto the second substrate and laminating. A method for producing a three-dimensional photonic crystal . 6. The method according to claim 5, wherein the step of disposing the inclusion includes a step of applying a material of the inclusion on the first substrate and a step of curing the applied material. A method for producing a two-dimensional photonic crystal . 7. The method according to claim 6, further comprising the step of removing the covering material when the applied material covers a part or all of at least one of the holding member and the cross-sectional shape member. A method for producing a two-dimensional photonic crystal . The method for producing a three-dimensional photonic crystal according to claim 7, wherein the applied material is a photoresist. The method for producing a three-dimensional photonic crystal according to claim 8, wherein the step of removing the covering material includes ashing. A substrate for manufacturing a three-dimensional photonic crystal used in a method for manufacturing a three-dimensional photonic crystal comprising a step of sequentially joining, transferring, and laminating a plurality of cross-sectional shape members, the substrate and a holding member on the substrate via a holding member prevention and a plurality of cross-sectional shape member in accordance with the slice pattern of retained three-dimensional structure, the breakage of the holding member during the bonding of the cross-sectional shape member provided between the cross-sectional shape member and the substrate And a substrate for manufacturing a three-dimensional photonic crystal , characterized in that the substrate includes an inclusion for the purpose. The substrate for manufacturing a three-dimensional photonic crystal according to claim 10, wherein the inclusion is made of a material that can be removed by post-processing. 12. The substrate for manufacturing a three-dimensional photonic crystal according to claim 11, wherein the material that can be removed by the post-treatment is a photoresist.

Images