JP5947148B2 - Manufacturing method of optical element - Google Patents

Description

The present invention relates to a manufacturing method of Hikarimoto child with a compound of a rare earth.

  The research field of silicon photonics that aims to monolithically fabricate an optical waveguide, a light emitting element, and a light receiving element on a silicon substrate has greatly advanced (see Non-Patent Document 1). In this silicon photonics, when a silicon-based semiconductor is used as a light emitting element material on a silicon substrate, the problem is that the emission intensity is very weak compared to a direct transition type semiconductor material such as a compound semiconductor. In silicon photonics, thin silicon wires play an important role as optical waveguides (see Patent Documents 1 and 2). Since light having a wavelength of 1.1 μm or less is absorbed by silicon, silicon photonics requires light having a wavelength of 1.1 μm or more.

  Against this background, attempts have been made to add rare earth elements that emit light at 1.5 μm, such as erbium, to silicon. However, due to the solid solubility limit of erbium in silicon, sufficient intensity of light emission can be obtained. (See Non-Patent Document 2). Here, even if silicon-based relatively weak light emission can be added with an optical amplification function such as an erbium doped fiber amplifier (EDFA) realized by an optical fiber, excitation in silicon photonics is possible. There is a possibility that it can be sufficiently used as light or signal light.

However, in the case of EDFA, the fiber length for performing optical amplification usually requires several tens of meters, and it is physically impossible to mount on a silicon substrate. Usually, the gain of optical amplification is determined by the concentration (amount) of rare earth ions added to the glass. In the case of EDFA, about 10 ¹⁹ cm ^-3 erbium ions are added. This concentration is determined by the solid solution limit of erbium ions in the glass, and the concentration of erbium cannot be increased more than that described above.

  On the other hand, if the fiber length is further increased, the amount of erbium ions contributing to optical amplification can be increased, and the gain of optical amplification can be improved. However, further increasing the fiber length makes it more difficult to apply to silicon photonics. As described above, it is not practical to apply EDFA to silicon photonics due to physical restrictions (see Non-Patent Document 2).

  On the other hand, in the natural world, there are rare earth compounds containing a large amount of rare earth ions, for example. For example, erbium compounds exist. In particular, rare earth oxides and rare earth silicate materials have attracted much attention because of their high potential for application to silicon photonics (see Non-Patent Document 3).

The reason will be described below. For example, when erbium oxide and erbium silicate structures are taken as examples, erbium oxide and erbium silicate crystals naturally contain Er ³⁺ ions at a concentration of 10 ²² cm ⁻³ in the unit cell. This concentration corresponds to about 1000 times when compared with the case of EDFA, and when this is applied to EDFA, even if the length of EDFA is reduced to 1/1000, that is, to a length of several hundred nm, the same level of light amplification. It means that the performance of can be obtained.

  Therefore, if the rare earth compound as described above is used, the application to silicon photonics considering optical circuit design on silicon will be in the field of view. For example, erbium oxide and erbium silicate are the most promising material candidates for realizing a light amplification function on a silicon substrate.

  Under such a background, researches on the growth of erbium compounds on silicon substrates and the evaluation of optical properties of erbium compounds have been actively conducted recently (see Non-Patent Documents 4, 5, and 6).

  However, on the other hand, the problem of concentration quenching occurs because the concentration of erbium is too high. Concentration quenching is a phenomenon that occurs when the distance between erbium ions is close to the atomic level. Energy migration and cooperative up-conversion are known as the mechanism of concentration disappearance.

  In order to solve this problem, erbium has recently been added to rare earth oxides, such as yttrium (Y) and gadolinium (Gd), yttrium silicate, gadolinium silicate compound materials, and the like having almost the same ionic radius as erbium ions. Technology has been proposed (see Non-Patent Document 7).

  Furthermore, in order to increase the luminous efficiency of erbium ions, a technique has been proposed in which ytterbium (Yb) is added to yttrium compounds and gadolinium compounds in addition to erbium. In this technology, by making the wavelength of the pump light the same as the energy level of the ytterbium ion, the ytterbium ion in the compound mentioned above effectively absorbs the pump light, and this absorbed energy is absorbed through the ytterbium. To increase the luminous efficiency of erbium ions (Er) (see Non-Patent Document 8).

JP 2004-281972 A JP 2004-319668 A

Yoshihiko Kinmitsu and Satoshi Fukatsu, “Silicon Photonics”, Ohmsha, pages 89-118. A. J. Kenyon, "Erbium in silicon", Semicond. Sci. Technol., VOL.20, R65-R84, 2005. Edited by Shoichi Sudo, “Erbium-doped fiber amplifier”, Optronics, pages 3-22. C. P. Michael et al, "Growth, processing, and optical properties of epitaxial Er2O3 on silicon", OPTICS EXPRESS, Vol.16, No.24, pp.19649-19666, 2008. John B. Gruber et al., "Modeling optical transitions of Er3 + .4f11… in C2 and C3i sites in fused Y2O3", JOURNAL OF APPLIED PHYSICS, vol.104, 023101, 2008. H.ISSHIKI and T.KIMURA, "Toward Small Size Waveguide Amplifiers Based on Erbium Silicate for Silicon Photonics", IEICE TRANS. ELECTRON., Vol.E91.C, no.2, pp.138-144, 2008. K. Shu et al., "Cooperative upconversion and optical gain in ion-beam sputter-deposited ErxY2-xSiO5 waveguides", Optics Lett. Vol. 18, No. 8, pp.7724-7731, 2010. R. Guo et al., "Optical amplification Er / Yb silicate loaded waveguide", Appl. Phys. Lett., Vol. 99, 161115, 2011.

  By the way, in silicon photonics as described above, it is necessary to produce functions such as light emission, light reception, and resonator at desired positions on a silicon substrate, and the same applies to an optical amplifier. In other words, a technique for arranging, for example, erbium oxide or erbium silicate crystals at a desired position of a silicon wafer is important, and establishment of this technique is strongly demanded.

  As a technique described above, for example, in order to fabricate an optical resonator structure such as an optical waveguide and a microdisk, the following is generally performed. First, a rare earth oxide (for example, erbium oxide) is vapor-deposited on a silicon oxide film (refractive index n = about 1.5) having a film thickness of several hundreds nm on a silicon substrate to form a rare earth oxide layer. The silicon oxide film becomes the lower cladding layer. Next, the rare earth oxide layer is patterned by a known photolithography and etching technique to form a thin wire core of erbium oxide (refractive index n = 2.0) on the lower cladding layer made of a silicon oxide film. Thereafter, an oxide film or an epoxy resin is applied on the formed erbium oxide thin wire core to form an upper clad layer, thereby forming a waveguide structure.

  However, in this method, erbium oxide is formed as a film on the entire surface of the substrate, and most of it is removed by lithography and etching as described above. Thus, there is a problem that the rare earth compound material is wasted, resulting in an increase in material cost.

  The present invention has been made to solve the above-described problems, and an optical element using a rare earth compound can be manufactured in a state where problems such as concentration quenching are solved without wasting materials. The purpose is to do so.

The method of manufacturing an optical element according to the present invention includes a third rare earth oxide co-doped with a first rare earth and a second rare earth different from the first rare earth or a third rare earth co-doped with the first rare earth and the second rare earth. It includes at least a step of forming a rare earth-containing layer made of silicate on the lower silicon layer by physical vapor deposition and a step of heating and aggregating the rare earth-containing layer to form an optical functional layer.

  The method for manufacturing an optical element includes a step of forming an upper silicon layer on the optical functional layer after forming the optical functional layer, wherein the lower silicon layer and the upper silicon layer have different conductivity types, and the rare earth-containing layer is formed. What is necessary is just to form the optical function layer used as the light emitting layer which consists of a several fine structure comprised from the rare earth silicate on the lower silicon layer by heating. Further, a step of forming irregularities on the surface of the lower silicon layer may be provided, and the rare earth-containing layer may be formed on the lower silicon layer having the irregularities formed thereon. If the irregularities are groove portions, the rare earth-containing layer can be heated and aggregated into the groove portions to form an optical functional layer that becomes the core of the optical waveguide.

The optical element is an optical element manufactured by the above-described optical element manufacturing method. For example, it is a light emitting element provided with the said light emitting layer. Further, for example, the optical element is an optical amplifier including an optical amplifying unit configured from an optical functional layer serving as a core.

  As described above, according to the present invention, an optical element using a rare earth compound can be manufactured in a state where problems such as concentration quenching are solved without wasting materials.

FIG. 1A is a cross-sectional view showing a state in each step for explaining a method of manufacturing an optical element in Embodiment 1 of the present invention. FIG. 1B is a cross-sectional view showing a state in each step for explaining the method of manufacturing an optical element in the first embodiment of the present invention. FIG. 1C is a cross-sectional view showing a state in each step for explaining the method of manufacturing an optical element in the first embodiment of the present invention. FIG. 1D is a cross-sectional view showing a state in each step for explaining the method of manufacturing an optical element in the first embodiment of the present invention. FIG. 1E is a cross-sectional view showing a state in each step for explaining the method of manufacturing an optical element in the first embodiment of the present invention. FIG. 1F is a plan view showing a state in each step for explaining the method of manufacturing an optical element in the first embodiment of the present invention. FIG. 2A is a cross-sectional view showing a state in each step for explaining the method of manufacturing an optical element in the second embodiment of the present invention. FIG. 2B is a cross-sectional view showing a state in each step for explaining the method of manufacturing an optical element in the second embodiment of the present invention. FIG. 2C is a cross-sectional view showing a state in each step for explaining the method of manufacturing an optical element in the second embodiment of the present invention. FIG. 2D is a plan view showing a state in each step for explaining the method of manufacturing the optical element in the second embodiment of the present invention. FIG. 2E is a cross-sectional view showing a state in each step for explaining the method of manufacturing an optical element in the second embodiment of the present invention. FIG. 2F is a cross-sectional view showing a state in each step for explaining the method of manufacturing an optical element in the second embodiment of the present invention. FIG. 3A is a cross-sectional view showing a state in each step for explaining the method of manufacturing an optical element in the third embodiment of the present invention. FIG. 3B is a cross-sectional view showing a state in each step for explaining the method of manufacturing an optical element in the third embodiment of the present invention. FIG. 3C is a plan view showing a state in each step for explaining the method of manufacturing an optical element in the third embodiment of the present invention. FIG. 3D is a cross-sectional view showing a state in each step for explaining the method of manufacturing an optical element in the third embodiment of the present invention. FIG. 3E is a cross-sectional view showing a state in each step for explaining the method of manufacturing an optical element in the third embodiment of the present invention. FIG. 3F is a plan view showing a state in each step for explaining the method of manufacturing an optical element in the third embodiment of the present invention. FIG. 4A is a plan view showing a state in each step for explaining the method of manufacturing an optical element in the fourth embodiment of the present invention. FIG. 4B is a plan view showing a state in each step for explaining the method of manufacturing an optical element in the fourth embodiment of the present invention. FIG. 4C is a plan view showing a state in each step for explaining the method of manufacturing an optical element in the fourth embodiment of the present invention. FIG. 4D is a plan view showing a state in each step for explaining the method of manufacturing an optical element in the fourth embodiment of the present invention. FIG. 4E is a plan view showing a state in each step for explaining the method of manufacturing an optical element in the fourth embodiment of the present invention. FIG. 4F is a plan view showing a state in each step for explaining the method of manufacturing an optical element in the fourth embodiment of the present invention. FIG. 5 is a plan view showing a configuration example of the optical element in the embodiment of the present invention. FIG. 6 is a cross-sectional view showing a configuration example of the optical element in the embodiment of the present invention. FIG. 7 is a plan view showing a configuration example of the optical element in the embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[Embodiment 1]
First, Embodiment 1 of the present invention will be described with reference to FIGS. 1A to 1F. 1A to 1F are a cross-sectional view and a plan view showing a state in each step for explaining a method of manufacturing an optical element in Embodiment 1 of the present invention. 1A to 1E are sectional views, and FIG. 1F is a plan view.

  First, as shown in FIG. 1A, a substrate including a silicon layer (lower silicon layer) 103 is prepared. The substrate is an SOI (Silicon On Insulator) substrate including a silicon base 101 and a buried insulating layer 102, and the surface silicon layer of the SOI substrate is a silicon layer 103.

  Next, as shown in FIG. 1B, a groove 104 is formed in the silicon layer 103. For example, the groove 104 may be formed by patterning the silicon layer 103 by a known photolithography and etching technique.

  Next, as shown in FIG. 1C, a rare earth-containing layer 105 is formed. The rare earth-containing layer 105 is a third rare earth oxide in which a first rare earth and a second rare earth different from the first rare earth are co-added. For example, the first rare earth is erbium and the second rare earth is ytterbium. The third rare earth is yttrium. In this case, the rare earth-containing layer 105 is composed of yttrium oxide to which erbium and ytterbium are co-added.

  Here, the rare earth-containing layer 105 is formed by heating a substrate by physical vapor deposition such as sputtering. Note that the rare earth-containing layer 105 may be formed by a vacuum evaporation method. The rare earth-containing layer 105 thus formed is in an amorphous state.

  Next, the rare earth-containing layer 105 is heated to, for example, 1000 ° C. to agglomerate the rare earth-containing layer 105 into the groove portion 104, and as shown in FIG. 1D, the first rare earth and the second rare earth different from the first rare earth are shared. A rare earth core portion (optical functional layer) 106 made of the added third rare earth oxide crystal is formed. In the first embodiment, the rare earth core portion 106 made of a yttrium oxide crystal co-doped with erbium and ytterbium is formed.

  The rare earth oxide having the above-described structure aggregates in the recess formed in the base by heating. Moreover, since the rare earth-containing layer 105 that has been in an amorphous state is crystallized by this heating, the rare earth core portion 106 is composed of crystals. In other words, it is important that the aggregation temperature is at least a temperature at which the rare earth-containing layer 105 having the above-described configuration is crystallized. The dimension of the rare earth core portion 106, for example, the height of the cross-sectional shape is determined by the amount of the rare earth-containing layer 105.

  Next, as shown in FIG. 1E, a silicon oxide layer 107 is formed on the silicon layer 103 on which the rare earth core portion 106 is formed. For example, the silicon oxide layer 107 can be formed by depositing silicon oxide by a sputtering method. As shown in the plan view of FIG. 1F, the planar shape of the rare earth core 106 is a rectangle that is long in the waveguide direction (the vertical direction on the paper surface). In the cross-sectional view of FIG. 1E, it has a core shape extending from the front to the back of the page. As a result, an optical amplifying element using the rare earth core portion 106 of the optical waveguide structure in which the buried insulating layer 102 is the lower cladding layer and the silicon oxide layer 107 is the upper cladding layer is obtained.

  In the optical waveguide structure formed by the manufacturing method described above, the dimensions of the cross-sectional shape of the rare earth core portion 106 are, for example, a height and a width of 1.5 μm or more. Moreover, the layer thickness of the silicon layer 103 should just be more than half of the thickness of the rare earth core part 106. FIG.

  As described above, according to the first embodiment, the rare earth core portion 106 can be formed without removing most of the deposited rare earth-containing layer 105 by etching or the like. The optical waveguide composed of the rare earth core portion 106 can be used as an optical modulator (optical element). Thus, according to the first embodiment, an optical element using a rare earth compound can be manufactured without wasting materials. In addition, according to the first embodiment, the rare earth core portion 106 is made of, for example, yttrium oxide to which erbium and ytterbium are co-added. Therefore, in an optical element using the rare earth core portion 106, there is a problem of concentration quenching. Will be solved.

[Embodiment 2]
Next, Embodiment 2 of the present invention will be described with reference to FIGS. 2A to 2F. 2A to 2F are cross-sectional views and plan views showing states in respective steps for explaining the method of manufacturing an optical element in the second embodiment of the present invention. 2A to 2C, 2E, and 2F are cross-sectional views, and FIG. 2D is a plan view.

  First, as shown in FIG. 2A, a substrate provided with a silicon layer (lower silicon layer) 203 is prepared. The substrate is an SOI substrate including a silicon base 201 and a buried insulating layer 202, and the surface silicon layer of the SOI substrate is a silicon layer 203.

Next, as shown in FIG. 2B, a rare earth-containing layer 204 is formed on the silicon layer 203. The rare earth-containing layer 204 is a third rare earth oxide in which a first rare earth and a second rare earth different from the first rare earth are co-added. For example, the first rare earth is erbium and the second rare earth is ytterbium. The third rare earth is yttrium. In this case, the rare earth-containing layer 204, becomes the erbium and ytterbium is composed of yttrium oxide being co-doped _{(Er x Yb y Y 2-} xy O 3).

  Here, the rare earth-containing layer 204 is formed without heating the substrate by physical vapor deposition such as sputtering. Note that the rare earth-containing layer 204 may be formed by a vacuum evaporation method. The rare earth-containing layer 204 thus formed is in an amorphous state.

Next, with the rare earth-containing layer 204 formed, these are heated to, for example, 1000 ° C. to cause the rare earth-containing layer 204 and silicon of the silicon layer 203 to react with each other, as shown in FIGS. 2C and 2D. A plurality of nanostructures (optical functional layers) 205 made of a silicate of a third rare earth co-doped with a first rare earth and a second rare earth different from the first rare earth are formed. In the second embodiment, since the silicon layer 203 has no irregularities, the rare earth-containing layer 204 does not agglomerate integrally by heating, and reacts with the silicon of the lower silicon layer 203 to form silicate. Agglomerate to form nanostructures 205. In the second embodiment, _{"Er x Yb y Y 2-xy} O 3 + O 2 + Si → Er x Yb y Y 2-xy SiO 5 " or _{"Er x Yb y Y 2-xy} O 3 + 2O 2 + 2Si → Er x by chemical reaction _{Yb y Y 2-xy Si 2} O 7 ", to produce a silicate of a rare earth that two rare earths are added together.

  Next, as shown in FIG. 2E, a silicon layer (upper silicon layer) 206 is formed on the silicon layer 203 on which the nanostructure 205 is formed. Thereafter, as shown in FIG. 2F, the silicon layer 203 and the silicon layer 206 are patterned into a predetermined mesa structure, an electrode 207 is formed on the silicon layer 206, and an electrode 208 connected to the silicon layer 203 is formed. .

  In the above structure, when the silicon layer 203 is p-type and the silicon layer 206 is n-type, a light-emitting element having a plurality of nanostructures 205 sandwiched therebetween as a light-emitting layer can be obtained. Note that the silicon layer 203 may be n-type and the silicon layer 206 may be p-type.

[Embodiment 3]
Next, Embodiment 3 of the present invention will be described with reference to FIGS. 3A to 3F. 3A to 3F are cross-sectional views and plan views showing states in respective steps for explaining the method of manufacturing an optical element in the third embodiment of the present invention. 3A, 3B, 3D, and 3E are cross-sectional views, and FIGS. 3C and 3F are plan views.

  First, as shown in FIG. 3A, a substrate provided with a silicon layer (lower silicon layer) 303 is prepared. The substrate is an SOI substrate including a silicon base 301 and a buried insulating layer 302, and the surface silicon layer of the SOI substrate is a silicon layer 303.

  Next, as shown in FIG. 3B, a groove 304 is formed in the silicon layer 303. For example, the groove 304 may be formed by patterning the silicon layer 303 by a known photolithography and etching technique. As shown in the plan view of FIG. 3C, the groove 304 is formed in a state of being arranged on each side of the quadrangle. The four grooves 304 arranged in this way are in a state in which these inner regions are enclosed.

Next, as shown in FIG. 3D, a rare earth-containing layer 305 is formed on the silicon layer 303. The rare earth-containing layer 305 is a third rare earth oxide in which a first rare earth and a second rare earth different from the first rare earth are co-added. For example, the first rare earth is erbium and the second rare earth is ytterbium. The third rare earth is yttrium. In this case, the rare earth-containing layer 305, becomes the erbium and ytterbium is composed of yttrium oxide being co-doped _{(Er x Yb y Y 2-} xy O 3).

  The rare earth-containing layer 305 is formed without heating the substrate by physical vapor deposition such as sputtering. Note that the rare earth-containing layer 305 may be formed by a vacuum evaporation method. The rare earth-containing layer 305 thus formed is in an amorphous state.

Next, in a state where the rare earth-containing layer 305 is formed, these are heated to, for example, 1000 ° C., and as shown in FIGS. 3E and 3F, in the four groove portions 304, the first rare earth and the first rare earth are defined. to form a different second third rare earth oxide of rare earth was codoped _{(Er x Yb y Y 2-} xy O 3) consisting of crystalline pattern portion 306, on the silicon layer 303 of the region surrounded with these , the third rare earth co added different second rare earth and the first earth and the first rare earth silicates (e.g. _{Er x Yb y Y 2-xy} SiO 5 or _{Er x Yb y Y 2-xy} Si 2 O 7 A plurality of nanostructures 307 are formed.

  In the four groove portions 304, the rare earth-containing layer 305 aggregates to form a pattern portion 306. On the other hand, in the flat region surrounded by the four groove portions 304, the silicate is formed by reacting with the silicon of the lower silicon layer 303 to form the nanostructure 307. As described above, the nanostructure 307 can be arranged in a specific region by the unevenness formed in the silicon layer 303. The thickness of the pattern portion 306 and the size of the nanostructure 307 can be controlled by the deposition amount of the rare earth-containing layer 305, the width of the groove portion 304, and the interval between the groove portions 304.

[Embodiment 4]
Next, Embodiment 4 of the present invention will be described with reference to FIGS. 4A to 4F. 4A to 4F are a cross-sectional view and a plan view showing a state in each step for explaining the method of manufacturing an optical element in the fourth embodiment of the present invention. 4A, 4B, and 4D to 4F are sectional views, and FIG. 4C is a plan view.

  First, as shown in FIG. 4A, a substrate provided with a silicon layer (lower silicon layer) 403 is prepared. The substrate is an SOI substrate including a silicon base 401 and a buried insulating layer 402, and the surface silicon layer of the SOI substrate is a silicon layer 403.

  Next, as shown in FIG. 4B, a mask pattern 404 is formed on the silicon layer 403. The mask pattern 404 includes a rectangular opening 405 as shown in the plan view of FIG. 4C. For example, the mask pattern 404 may be formed by patterning a photoresist layer applied on the silicon layer 403 by a known photolithography technique. In the opening 405, the silicon layer 403 is exposed.

  Next, as shown in FIG. 4D, a rare earth-containing layer 406 is formed on the silicon layer 403 on which the mask pattern 404 is formed. The rare earth-containing layer 406 is a third rare earth oxide in which a first rare earth and a second rare earth different from the first rare earth are co-added. For example, the first rare earth is erbium and the second rare earth is ytterbium. The third rare earth is yttrium. In this case, the rare earth-containing layer 406 is composed of yttrium oxide to which erbium and ytterbium are co-added.

  The rare earth-containing layer 406 is formed without heating the substrate by a physical vapor deposition method such as a sputtering method. Note that the rare earth-containing layer 406 may be formed by a vacuum evaporation method. The rare earth-containing layer 406 thus formed is in an amorphous state.

  Next, by removing the mask pattern 404 and removing the rare earth-containing layer 406 formed on the mask pattern 404 other than the opening 405, a portion of the silicon layer 403 is formed on the silicon layer 403 as shown in FIG. 4E. In particular, the rare earth-containing layer 406 is arranged.

Next, in a state where the rare earth-containing layer 406 is formed, these are heated to, for example, 1000 ° C., and the rare earth-containing layer 406 and the silicon of the silicon layer 403 are allowed to react with each other, as shown in FIG. on the silicon layer 403, a third rare earth silicate which codoped different second rare earth and the first earth and the first rare earth (e.g., _{Er x Yb y Y 2-xy} SiO 5 or Er _x Yb _{y Y 2-xy} A plurality of nanostructures 407 made of Si ₂ O ₇ ) are formed. In the fourth embodiment, the nanostructure 407 is arranged in a desired specific region by using the mask pattern 404.

As described above, various optical elements can be formed by heating a rare earth-containing layer made of a rare earth oxide formed on a silicon layer by physical vapor deposition. For example, if unevenness is formed in the silicon layer, the rare earth-containing layer can be aggregated and crystallized in the recess. In this case, by forming the thin line the recess in plan _{view, Er x Yb y Y 2-} xy O 3 of the third rare earth co added different second rare earth and the first earth and the first rare earth, such as A thin wire core (optical functional layer) made of an oxide crystal can be formed, and an optical amplifying element can be configured by using this. In this structure, an electrode can be provided to function as a light-emitting element.

Further, in the flat region of the silicon layer can be formed nanostructures consisting of silicate, such as _{Er x Yb y Y 2-xy} SiO 5 or _{Er x Yb y Y 2-xy} Si 2 O 7. A plurality of nanostructures made of rare earth silicate co-doped with two different rare earths can be used as a light emitting material free from problems such as concentration quenching.

  For example, as shown in the plan view of FIG. 5, the nanostructure forming part 511, the rare earth core part 512, and the silicon fine wire core 513 can be arranged and combined in the optical waveguide direction. The nanostructure forming portion 511 and the rare earth core portion 512 are formed on the silicon layer 501, and the silicon fine wire core 513 is formed on the buried insulating layer 504. Here, as shown in the cross-sectional view of FIG. 6, the formation region of the rare earth core portion 512 is formed in the concave portion of the silicon layer 501, and the silicon oxide layer 502 is formed thereon. Although not shown, a silicon oxide layer 502 is also formed on the nanostructure forming portion 511 and the silicon thin wire core 513.

  Under the silicon layer 501, a buried insulating layer 504 and a silicon base 503 are disposed. The silicon base 503, the buried insulating layer 504, and the silicon layer 501 are SOI substrates. FIG. 6 shows a cross section taken along line XX ′ of FIG. In these configurations, the buried insulating layer 504 serves as a lower cladding layer, and the silicon oxide layer 502 serves as an upper cladding layer.

  Further, as shown in the plan view of FIG. 7, the nanostructure forming portion 511, the silicon fine wire core 513, and the rare earth core portion 512 may be arranged in this order in the waveguide direction.

  The nanostructure forming portion 511 and the rare earth core portion 512 include the first rare earth and the second rare earth different from the first rare earth on the silicon layer 501 as is apparent from the description in the first to fourth embodiments. It can be formed by forming a rare earth-containing layer made of a co-doped third rare earth oxide and heating it. Further, the silicon fine wire core 513 can be formed by patterning the silicon layer 501 by a known lithography and etching technique. As described above, each optical element can be easily combined with an optical waveguide made of the silicon fine wire core 513.

  Further, these can be formed by a generally used LSI integrated circuit manufacturing technique, and the positional accuracy with respect to the waveguide direction can be in units of sub-μm. Therefore, it is easy to align the nanostructure forming portion 511, the rare earth core portion 512, and the silicon fine wire core 513 in order to arrange them in the waveguide direction. In addition, at the stage where each configuration is formed, the optical axes are aligned, and there is no need to adjust the optical axes later.

  The present invention is not limited to the embodiment described above, and many modifications and combinations can be implemented by those having ordinary knowledge in the art within the technical idea of the present invention. It is obvious. For example, in the above description, the case where the first rare earth and the third rare earth oxide co-doped with the second rare earth different from the first rare earth is formed by physical vapor deposition as the rare earth-containing layer has been described. Instead, a third rare earth silicate co-doped with the first rare earth and the second rare earth may be formed by physical vapor deposition.

  In addition, the case of using yttrium oxide co-added with erbium and ytterbium has been described. However, the present invention is not limited to this. Europium oxide co-added with ytterbium and thulium, neodymium oxide co-added with ytterbium and thulium , Thulium oxide co-doped with ytterbium and thulium, praseodymium oxide co-doped with ytterbium and thulium, hafnium oxide co-doped with ytterbium and thulium, gadolinium oxide co-doped with ytterbium and thulium, terbium oxide co-doped with ytterbium and thulium This also applies to other rare earth oxides such as dysprosium oxide co-doped with ytterbium and thulium. The same applies to aluminum oxide and tellurium oxide.

  The rare earth-containing layer may contain not only the rare earth and rare earth oxides described above, but also, for example, yttrium oxide, silicon oxide, titanium oxide, aluminum oxide, bismuth oxide, germanium oxide, and the like. These can be formed, for example, in the state of being included in the rare earth-containing layer by vapor deposition at the same time as the rare earth oxide. Note that since the crystallization temperature differs depending on the material, the temperature of the heat treatment is set appropriately. Even when a nanostructure made of silicide is formed, the heat treatment time is appropriately set in order to form a complete compound.

  In the above description, the SOI substrate is used. However, the present invention is not limited to this, and a silicon substrate, a germanium substrate, a GOI (Germanium on insulator) substrate, or an SGOI (Silicon germanium on insulator) substrate may be used. . Further, for example, the linear rare earth core 106 is formed by forming the groove 104 in a straight line, but the present invention is not limited to this, and a ring shape may be used. A resonator can be formed by forming it in a ring shape. By forming the resonator in this way, the resonator can be combined with the optical circuit described with reference to FIGS. Further, the intensity of excitation light can be enhanced by applying the resonator structure to a light emitting element.

  DESCRIPTION OF SYMBOLS 101 ... Silicon base part, 102 ... Embedded insulating layer, 103 ... Silicon layer (lower silicon layer), 104 ... Groove part, 105 ... Rare earth containing layer, 106 ... Rare earth core part (optical functional layer), 107 ... Silicon oxide layer.

Claims (4)

A rare earth-containing layer comprising a third rare earth oxide co-doped with a first rare earth and a second rare earth different from the first rare earth or a third rare earth silicate co-doped with the first rare earth and the second rare earth Forming on the lower silicon layer by vapor deposition;
And a step of heating and aggregating the rare earth-containing layer to form an optical functional layer. In the manufacturing method of the optical element of Claim 1,
After forming the optical functional layer, comprising a step of forming an upper silicon layer on the optical functional layer,
The lower silicon layer and the upper silicon layer have different conductivity types,
The optical functional layer to be a light emitting layer composed of a plurality of microstructures composed of the rare earth silicate is formed on the lower silicon layer by heating the rare earth-containing layer. Method. In the manufacturing method of the optical element of Claim 1,
Comprising the step of forming irregularities on the surface of the lower silicon layer,
A method for manufacturing an optical element, comprising forming the rare earth-containing layer on the lower silicon layer having the irregularities formed thereon. In the manufacturing method of the optical element of Claim 3,
The unevenness is a groove,
A method of manufacturing an optical element, comprising heating the rare earth-containing layer to agglomerate in the groove to form the optical functional layer serving as a core of an optical waveguide.

Images