JP5689832B2 - Method for manufacturing silicon light emitting device - Google Patents

Description

The present invention relates to a manufacturing method of a silicon light emitting element using silicon that rare-earth doped, such as erbium.

  The field of silicon photonics, which aims to monolithically fabricate optical waveguides, light-emitting elements (active devices), and light-receiving elements (passive devices) on a silicon substrate, has greatly advanced. Among these, it is considered difficult to realize an active device, and at present, development (research) of a high-efficiency light-emitting diode (LED) element using silicon as an active layer is being actively pursued.

  If a silicon light emitting diode (Si-LED) structure is to be produced, there are significant technical advantages to using silicon for the active layer for light emission, but there are significant problems. First, the advantages will be described. By using silicon, fusion of silicon electronic device technology represented by LSI and optical device technology can be realized. If this fusion is realized by silicon photonics technology, the power consumption of silicon devices can be reduced and the cost of device manufacturing can be significantly reduced.

  However, as is generally well known, silicon is an indirect transition type semiconductor and generally has a low luminous efficiency. For this reason, there is an essential problem that it is difficult to realize a high-intensity light-emitting element with silicon. In addition, when aiming to use silicon photonics technology in combination with optical fiber communication technology, the emission wavelength of the active layer of the silicon light emitting diode needs to be in the near infrared region, for example, about 1.5 μm. This is because it is desirable that the pump light and signal light necessary for the optical device are near infrared light in the communication wavelength band. Therefore, meeting these technical requirements is very important for the development and realization of light emitting elements (active devices) using silicon.

  Several techniques for utilizing silicon as an active layer of a light emitting device have been proposed from the viewpoint of material development. Use of silicon nanocrystals, formation of ultrathin silicon films and epitaxial films thereof, use of defects formed in silicon substrates, addition of rare earth to silicon substrates (for example, ion implantation), or a combination of these techniques Is mentioned.

  First, a technique of ion-implanting a light emitting element into silicon is the most basic method (see Non-Patent Document 1). For example, erbium can be optically activated by ion-implanting a rare earth such as erbium into a silicon substrate, followed by heat treatment. Since light emission from the transition from the first excited level of the erbium ion to the ground level is about 1550 nm, silicon can be emitted in the near infrared region by emitting doped erbium.

  Furthermore, an advantage of the ion implantation method is that, in addition to the rare earth, a light element such as oxygen and nitrogen or a metal such as silver can be added (co-added) together with the rare earth (see Non-Patent Document 3). For example, it is known that when erbium and oxygen are co-added, a light emitter called an erbium-oxygen atom complex is formed, thereby enhancing the light emission of erbium (see Non-Patent Document 2 and Patent Document 1). .

  However, the upper limit of the amount of erbium and oxygen that can be implanted into the silicon substrate is determined by the solid solubility of erbium and oxygen in silicon, and when the implantation amount increases, a large number of defects are formed in the silicon substrate. It is mentioned as a drawback. Furthermore, since the density of the ion-implanted element (atom) shows a wide Gaussian distribution in the depth direction under normal implantation conditions, it is difficult to effectively bring erbium and oxygen close to each other, and the number of erbium-oxygen emitters is reduced. There is also a problem that it is difficult to increase.

  Next, the use of silicon nanocrystals has the advantage that silicon itself can emit light as a direct transition type when the size (particle size) of the silicon nanoparticles is 3 nm or less where quantum confinement of light occurs. However, since the emission wavelength of nanocrystals is not a communication wavelength band, it does not directly lead to fusion with communication technology of silicon photonics. Attempts have also been made to ion-implant rare earth, particularly erbium, into a silicon oxide film containing silicon nanoparticles to emit light in the communication wavelength band (see Non-Patent Document 3 and Patent Document 2).

  This technique has an advantage that the emission wavelength of silicon can be adjusted to the communication wavelength band by transferring the energy absorbed by the silicon nanocrystal to erbium ions and emitting erbium ions. However, not all implanted erbium ions contribute to light emission. The upper limit of the number that contributes to light emission is almost determined by the number of silicon nanoparticles, and since there are not enough erbium ions that can contribute to light emission, there is a problem that light cannot be emitted with high intensity or lasing (oscillation). is there. In addition, the amorphous oxide film containing silicon nanocrystals added with erbium can enhance the emission of erbium. However, since the film itself is an insulator, current cannot flow through the film, and a light emitting diode ( There is a problem that the structure of the LED) is inappropriate.

  In addition, in order to use the light emission of defects in silicon as an LED, artificial defects can be introduced as a method of ion-implanting light elements such as hydrogen and nitrogen into silicon, or at the bonding interface of silicon substrates. There is a method using a dislocation network that is used (see Non-Patent Documents 4 and 5). With this technique, a silicon light-emitting diode is actually realized (see Non-Patent Document 4). However, when the defect light emission artificially introduced into silicon is used as an LED, there is a problem that the light emission efficiency is not good as in the above-described technique.

  Considering the advantages and disadvantages of the above techniques, when a current injection type light emitting element is considered, a technique for effectively forming a light emitter made of erbium and oxygen on silicon shows a high possibility. Therefore, realization of a silicon light emitting diode doped with rare earth such as erbium and oxygen that emits light with high intensity in the communication wavelength band is strongly demanded.

JP 2004-319668 A JP 2004-281972 A

A. J. Kenyon, "Erbium in silicon", Semicond. Sci. Technol., Vol.20, pp.R65-R84, 2005. G. Franz et al., "Erbium.oxygen interactions in crystalline silicon", Semicond. Sci. Technol., Vol.26, 055002, 2005. M. Fujii et al., "1.54 mm photoluminescence of Er3 + doped into SiO2 films containing Si nanocrystals: Evidence for energy transfer from Si nanocrystals to Er3 +", Appl. Phys. Lett., Vol.71, no.9, pp.1198 -1200, 1997. X. Yu et al., "A pure 1.5 m electroluminescence from metal-oxide-silicon tunneling diode using dislocation network", Applied Physics Letters, vol.93, 041108, 2008. E. Toyoda et al., "Mechanical Properties and Chemical Reactions at the Directly Bonded Si.Si Interface", Japanese Journal of Applied Physics, vol.48, 011202, 2009.

  However, as described above, when erbium and oxygen are ion-implanted into the silicon substrate, the implanted atoms are widely distributed in the depth direction from the surface in the silicon substrate. And oxygen cannot be effectively combined. Further, when the amount of ion implantation of erbium and oxygen is increased, defects in the silicon substrate also increase, so that there is a problem that the light emission efficiency of erbium in the silicon substrate cannot be increased.

  The present invention has been made to solve the above-described problems, and it is intended to further improve the light emission efficiency of a light-emitting element using silicon to which rare earth such as erbium that emits light in a communication wavelength band and oxygen is added. Objective.

  The method for manufacturing a silicon light emitting device according to the present invention includes: a first step of bonding a second silicon layer to a first silicon layer on a substrate; and a rare earth and an interface between the first silicon layer and the second silicon layer. And a second step of doping the oxygen to form an active layer at the interface.

  In the method for manufacturing a silicon light emitting device, the surface silicon layer of the SOI substrate in which the surface silicon layer is formed on the base via the buried insulating layer is bonded to the first silicon layer, and the buried insulating layer and the base are removed. Thus, the second silicon layer made of the surface silicon layer may be bonded to the first silicon layer.

  The method for manufacturing a silicon light emitting device according to the present invention includes a first step of doping a silicon oxide layer of a substrate having a second silicon layer on the first silicon layer on the substrate with a silicon oxide layer interposed between the rare earth and oxygen. And a second step of forming an active layer doped with rare earth and oxygen at the interface between the first silicon layer and the second silicon layer by eliminating the silicon oxide layer by heating in an inert atmosphere. .

  The method for manufacturing a silicon light emitting device according to the present invention includes a first step of doping a first silicon layer on a substrate with rare earth and oxygen to form a doped layer, and a first silicon on the side on which the doped layer is formed. A second step of bonding the second silicon layer to the surface of the layer, and heating the first silicon layer and the second silicon layer to diffuse the rare earth and oxygen of the doped layer, whereby the first silicon layer and the second silicon layer And a third step of forming an active layer at the interface by doping rare earth and oxygen at the interface.

  In the method for manufacturing a silicon light emitting device, the first silicon layer may be a first conductivity type, and the second silicon layer may be a second conductivity type. The first silicon layer and the second silicon layer may have the same conductivity type.

  In the method for manufacturing the silicon light emitting device, the rare earth may be erbium.

  As described above, according to the present invention, it is possible to further improve the light emission efficiency of the light emitting element using silicon to which rare earth such as erbium that emits light in the communication wavelength band and oxygen is added.

FIG. 1 is an explanatory diagram for explaining a method for manufacturing a silicon light-emitting element according to Embodiment 1 of the present invention. FIG. 2 is an explanatory diagram for explaining the method for manufacturing the silicon light emitting element in the first embodiment of the present invention. FIG. 3 is a cross-sectional view showing the configuration of the silicon light emitting device in the first embodiment of the present invention. FIG. 4A is a schematic cross-sectional view showing the state of each step in the manufacturing process for explaining the method for manufacturing the silicon light-emitting element in the second embodiment of the present invention. FIG. 4B is a schematic cross-sectional view showing the state of each step in the manufacturing process for explaining the method for manufacturing the silicon light-emitting element in the second embodiment of the present invention. FIG. 4C is a schematic cross-sectional view showing the state of each step in the manufacturing process for explaining the method for manufacturing the silicon light-emitting element in the second embodiment of the present invention. FIG. 4D is a schematic cross-sectional view showing the state of each step in the manufacturing process for explaining the method for manufacturing the silicon light-emitting element in the second embodiment of the present invention. FIG. 4E is a schematic cross-sectional view showing the state of each step in the manufacturing process, for explaining the method for manufacturing the silicon light-emitting element in the second embodiment of the present invention. FIG. 5A is a schematic cross-sectional view showing the state of each step in the manufacturing process for explaining the method for manufacturing the silicon light-emitting element in the third embodiment of the present invention. FIG. 5B is a schematic cross-sectional view showing the state of each step in the manufacturing process for explaining the method for manufacturing the silicon light-emitting element in Embodiment 3 of the present invention. FIG. 5C is a schematic cross-sectional view showing the state of each step in the manufacturing process for explaining the method for manufacturing the silicon light-emitting element in the third embodiment of the present invention. FIG. 5D is a schematic cross-sectional view showing the state of each step in the manufacturing process, for explaining the method for manufacturing the silicon light-emitting element in the third embodiment of the present invention. FIG. 5E is a schematic cross-sectional view showing the state of each step in the manufacturing process, for explaining the method for manufacturing the silicon light-emitting element in the third embodiment of the present invention. FIG. 6A is a schematic cross-sectional view showing the state of each step in the manufacturing process for explaining the method for manufacturing the silicon light-emitting element in the fourth embodiment of the present invention. FIG. 6B is a schematic cross-sectional view showing the state of each step in the manufacturing process for explaining the method for manufacturing the silicon light-emitting element in the fourth embodiment of the present invention. FIG. 6C is a schematic cross-sectional view showing the state of each step in the manufacturing process for explaining the method for manufacturing the silicon light-emitting element in the fourth embodiment of the present invention. FIG. 7A is a schematic cross-sectional view showing the state of each step in the manufacturing process for explaining the method for manufacturing the silicon light-emitting element in the fifth embodiment of the present invention. FIG. 7B is a schematic cross-sectional view showing the state of each step in the manufacturing process for explaining the method for manufacturing the silicon light-emitting element in Embodiment 5 of the present invention. FIG. 7C is a schematic cross-sectional view showing the state of each step in the manufacturing process for explaining the method for manufacturing the silicon light-emitting element in the fifth embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[Embodiment 1]
First, a method for manufacturing a silicon light-emitting element according to Embodiment 1 of the present invention will be described with reference to FIG. FIG. 1 is an explanatory diagram for explaining a method of manufacturing a silicon light emitting device in an embodiment of the present invention. FIG. 1 is a schematic cross-sectional view showing the state of each process in the manufacturing process.

  First, as shown in FIG. 1A, a first silicon layer 101 is prepared. The first silicon layer 101 is formed on a predetermined substrate. The substrate is, for example, a silicon substrate. In this case, the first silicon layer 101 is a portion on the surface side of the silicon substrate. In other words, the first silicon layer 101 is a silicon substrate. Next, as shown in FIG. 1B, the second silicon layer 102 is bonded to the first silicon layer 101. The second silicon layer 102 may be a silicon substrate. In the case of using a silicon substrate, after bonding, the second silicon layer 102 may be formed by thinning to a predetermined thickness. Here, it is important that the first silicon layer 101 and the second silicon layer 102 are single crystal silicon.

  The first silicon layer 101 and the second silicon layer 102 may be n-type and p-type by introducing predetermined impurities, respectively. For example, the first silicon layer 101 may be n-type, the second silicon layer 102 may be p-type, the first silicon layer 101 may be p-type, and the second silicon layer 102 may be n-type. May be. Both may be p-type or n-type.

  When the first silicon layer 101 which is a silicon substrate and the second silicon layer 102 which is a silicon substrate are bonded together, first, the bonded surfaces of the silicon substrates are respectively cleaned and chemically etched in hydrogen fluoride water. . By this treatment, the natural oxide film on the bonding surface of each silicon substrate is removed, and a hydrophobic hydrogen termination surface is formed on the surface of the bonding surface of each silicon substrate. Next, as shown in FIG. 2, the orientation of the silicon substrate 201 and the orientation of the silicon substrate 202 are set to arbitrary angles (φ, θ). In this state, both are crimped at room temperature (about 23 ° C.). θ is the rotation angle, and φ is the tilt angle.

  Next, the two silicon substrates bonded together at room temperature as described above are subjected to a treatment of heating at 200 ° C. to 400 ° C., and both are bonded together completely. After the second silicon layer 102 is bonded to the first silicon layer 101 in this way, the silicon substrate of the second silicon layer 102 is ground and polished to be thinned. With this thin layer, the depth from the surface side of the second silicon layer 102 to the interface 103 is adjusted.

  Next, as shown in FIG. 1C, the active layer 104 is formed on the interface 103 by doping the interface 103 between the first silicon layer 101 and the second silicon layer 102 with rare earth and oxygen. For example, heating is performed at 400 ° C. to 700 ° C., and the rare earth and oxygen are doped using, for example, an ion implantation method. The rare earth may be erbium.

Here, it is important to appropriately set the ion implantation conditions so that the maximum distribution of the implantation amount in the depth direction matches the interface 103. When rare earth and oxygen are added by the ion implantation method, the implantation amount may be, for example, about 1 × 10 ¹⁴ to 1 × 10 ¹⁵ cm ⁻² . The optimum amount of ion implantation is appropriately set according to the layer thickness of the second silicon layer 102. After the ion implantation, the first silicon layer 101 and the second silicon layer 102 are heated to 700 ° C. to 1000 ° C. in a nitrogen atmosphere to activate the implanted ions and recover the damage of the silicon layer by the ion implantation. I do.

  After forming the active layer 104 doped with rare earth and oxygen at the interface 103 between the two silicon layers as described above, the first electrode 301 connected to the first silicon layer 101 is formed as shown in FIG. Then, the second electrode 302 connected to the second silicon layer 102 is formed. For example, each electrode may be formed by depositing a metal such as titanium by a sputtering method. 3 includes a first silicon layer 101 formed on a substrate, a second silicon layer 102 bonded to the surface of the first silicon layer 101, a first silicon layer 101, and a second silicon layer. An active layer 104 formed by doping rare earth and oxygen is provided at the interface 103 with the layer 102.

  According to the silicon light emitting device manufactured as described above, since the active layer is formed by doping rare earth and oxygen at the interface between the two silicon layers, the doped rare earth and oxygen are aggregated at the interface. It becomes like this. This is because there is an effect of aggregating the contained elements (atoms) at the interface between the two silicon layers. For this reason, in the silicon light emitting device in the first embodiment, an erbium-oxygen atom complex (Er-O complex) is formed with high efficiency in the active layer. As a result, according to the silicon light emitting device of the first embodiment, the light emission efficiency can be further increased.

[Embodiment 2]
Next, Embodiment 2 of the present invention will be described with reference to FIGS. 4A to 4E. 4A to 4E are schematic cross-sectional views showing the states of the respective steps in the manufacturing process for explaining the method for manufacturing the silicon light emitting element in the second embodiment of the present invention.

  First, as shown in FIG. 4A, an SOI substrate is prepared in which a surface silicon layer 403 is formed on a silicon base 401 via a buried insulating layer 402. The surface silicon layer 403 is single crystal silicon. Next, as shown in FIG. 4B, the silicon base 401 is thinned by cutting and polishing.

  Next, as shown in FIG. 4C, the surface silicon layer 403 of the SOI substrate described above is bonded to the surface of the silicon substrate 404. The silicon substrate 404 is made of single crystal silicon. In this bonding, the bonding surfaces of the silicon substrate 404 and the surface silicon layer 403 are each cleaned and chemically etched in hydrogen fluoride water. By this treatment, the natural oxide film on each bonding surface is removed, and a hydrophobic hydrogen termination surface is formed on the surface of each bonding surface. Next, the orientation of the silicon substrate 404 and the orientation of the surface silicon layer 403 are set to an arbitrary angle. In this state, both are pressure-bonded at room temperature.

  Next, the silicon base 401 is cut and polished by mechanical polishing to be thinned, and additionally removed by chemical etching with an alkali such as potassium hydroxide. Further, the buried insulating layer 402 is removed by etching using, for example, hydrogen fluoride. As a result, the silicon base 401 and the buried insulating layer 402 are removed, and the surface silicon layer (second silicon layer) 403 is bonded onto the silicon substrate (first silicon layer) 404 as shown in FIG. 4D. State.

  Next, as shown in FIG. 4E, the interface 405 between the silicon substrate 404 and the surface silicon layer 403 is doped with rare earth and oxygen to form an active layer 406 at the interface 405. For example, heating is performed at 400 ° C. to 700 ° C., and the rare earth and oxygen are doped using, for example, an ion implantation method. The rare earth may be erbium.

Here, it is important to appropriately set the ion implantation conditions so that the maximum distribution of the implantation amount in the depth direction matches the interface 405. When rare earth and oxygen are added by the ion implantation method, the implantation amount may be, for example, about 1 × 10 ¹⁴ to 1 × 10 ¹⁵ cm ⁻² . The optimum amount of ion implantation is appropriately set according to the layer thickness of the surface silicon layer 403. After the ion implantation, the silicon substrate 404 and the surface silicon layer 403 are heated to 700 ° C. to 1000 ° C. in a nitrogen atmosphere to activate the implanted ions and recover silicon damage by the ion implantation.

  As described above, after forming the active layer 406 doped with rare earth and oxygen at the interface between the two silicon layers, the first electrode (not shown) connected to the silicon substrate 404 is formed, and the surface silicon layer 403 is formed on the surface silicon layer 403. A second electrode (not shown) to be connected is formed. For example, each electrode may be formed by depositing a metal such as titanium by a sputtering method.

  According to the silicon light emitting device manufactured as described above, since the active layer is formed by doping rare earth and oxygen at the interface between the silicon substrate and the surface silicon layer, the doped rare earth and oxygen are present at the interface. Aggregates. This is because there is an effect of aggregating the contained elements (atoms) at the interface between the two silicon layers. For this reason, also in the silicon light emitting device in the second embodiment, the erbium-oxygen atom complex is formed with high efficiency in the active layer. As a result, also in the silicon light emitting device of the second embodiment, the light emission efficiency can be further increased.

[Embodiment 3]
Next, Embodiment 3 of the present invention will be described with reference to FIGS. 5A to 5E. 5A to 5E are schematic cross-sectional views showing the states of the respective steps in the manufacturing process for explaining the method for manufacturing the silicon light-emitting element in the third embodiment of the present invention.

  First, as shown in FIG. 5A, an SOI substrate is prepared in which a surface silicon layer 503 is formed on a silicon base 501 with a buried insulating layer 502 interposed therebetween. The surface silicon layer 503 is single crystal silicon. Next, as shown in FIG. 5B, the silicon base portion 501 is thinned by cutting and polishing.

  Next, as shown in FIG. 5C, on the surface of the surface silicon layer 506 of the other SOI substrate in which the surface silicon layer 506 is formed on the silicon base 504 via the buried insulating layer 505, the above-described SOI substrate is formed. A surface silicon layer 503 is bonded. The surface silicon layer 506 is single crystal silicon. In this bonding, the bonded surfaces of the surface silicon layer 506 and the surface silicon layer 503 are each cleaned and chemically etched in hydrogen fluoride water. By this treatment, the natural oxide film on each bonding surface is removed, and a hydrophobic hydrogen termination surface is formed on the surface of each bonding surface. Next, the orientation of the surface silicon layer 506 and the orientation of the surface silicon layer 503 are set to an arbitrary angle. In this state, both are pressure-bonded at room temperature.

  Next, the silicon base portion 501 is thinned by cutting by mechanical polishing, and additionally removed by chemical etching with an alkali such as potassium hydroxide. Further, the buried insulating layer 502 is removed by etching using, for example, hydrogen fluoride. As a result, the silicon base 501 and the buried insulating layer 502 are removed, and a surface silicon layer (second silicon layer) is formed on the surface silicon layer (first silicon layer) 506 of another SOI substrate as shown in FIG. 5D. Layer) 503 is bonded.

  Next, as shown in FIG. 5E, the interface 507 between the surface silicon layer 506 and the surface silicon layer 503 is doped with rare earth and oxygen to form an active layer 508 at the interface 507. For example, heating is performed at 400 ° C. to 700 ° C., and the rare earth and oxygen are doped using, for example, an ion implantation method. The rare earth may be erbium.

Here, it is important to appropriately set the ion implantation conditions so that the maximum distribution of the implantation amount in the depth direction matches the interface 507. When rare earth and oxygen are added by the ion implantation method, the implantation amount may be, for example, about 1 × 10 ¹⁴ to 1 × 10 ¹⁵ cm ⁻² . The optimum amount of ion implantation is appropriately set according to the thickness of the surface silicon layer 503. After the ion implantation, the surface silicon layer 506 and the surface silicon layer 503 are heated to 700 ° C. to 1000 ° C. in a nitrogen atmosphere to activate the implanted ions and recover silicon damage by the ion implantation.

  As described above, after forming the active layer 508 doped with rare earth and oxygen at the interface between the two silicon layers, the first electrode (not shown) connected to the surface silicon layer 506 is formed, and the surface silicon layer 503 is formed. A second electrode (not shown) connected to is formed. For example, each electrode may be formed by depositing a metal such as titanium by a sputtering method. Further, the first electrode connected to the surface silicon layer 506 may be formed at a portion where the surface silicon layer 506 is exposed by removing a part of the surface silicon layer 503.

  According to the silicon light emitting device manufactured as described above, since the active layer is formed by doping rare earth and oxygen at the interface between the silicon substrate and the surface silicon layer, the doped rare earth and oxygen are present at the interface. Aggregates. This is because there is an effect of aggregating the contained elements (atoms) at the interface between the two silicon layers. For this reason, also in the silicon light emitting device in the third embodiment, the erbium-oxygen atom complex is formed with high efficiency in the active layer. As a result, also in the silicon light emitting device of the third embodiment, the light emission efficiency can be further increased.

  In the third embodiment, since the active layer is formed at the silicon layer interface above the buried insulating layer, it can be applied to a light excitation device in addition to application to a light emitting device by electronic excitation. For example, by patterning using a known lithography technique and etching technique, it is possible to form an optical waveguide structure with a buried insulating layer as a cladding and a silicon layer with an active layer as a core. A device can be realized. In addition, in the same manner, an optical amplification amplifier, a photonic crystal, and the like can be realized.

[Embodiment 4]
Next, Embodiment 4 of the present invention will be described with reference to FIGS. 6A to 6C. 6A to 6C are schematic cross-sectional views showing the states of the respective steps in the manufacturing process for explaining the method for manufacturing the silicon light emitting element in the fourth embodiment of the present invention.

  First, as shown in FIG. 6A, an SOI substrate is prepared in which a surface silicon layer 603 is formed on a silicon base 601 with a buried silicon oxide layer 602 interposed therebetween.

  Next, the buried silicon oxide layer 602 is doped with rare earth, and as shown in FIG. 6B, the rare earth-added layer 612 is formed so as to be sandwiched between the silicon base 601 and the surface silicon layer 603. . For example, rare earth is doped using an ion implantation method. The rare earth may be erbium. Here, it is important to appropriately set the ion implantation conditions so that the maximum distribution in the depth direction of the implantation amount matches the buried silicon oxide layer 602.

  When the rare earth-added layer 612 is formed between the silicon base 601 and the surface silicon layer 603 as described above, these are heated to 1000 to 1350 ° C. in an inert atmosphere to eliminate silicon oxide. The inert atmosphere may be a vacuum or a nitrogen or argon atmosphere. The inert atmosphere may be a nitrogen or argon gas atmosphere with a low oxygen concentration.

When heated in such an inert atmosphere, the rare earth-added layer 612 that was a buried silicon oxide layer made of silicon oxide disappears due to the reaction of “Si (solid phase) + SiO ₂ → 2SiO”. Due to this disappearance, as shown in FIG. 6C, the silicon base 601 and the surface silicon layer 603 are bonded together. Further, oxygen atoms dissolved in the silicon base portion 601 and the surface silicon layer 603 are precipitated at the interface 604. As a result, the interface 604 is doped with erbium and oxygen, and an active layer 605 is formed.

  After forming the active layer 605 doped with rare earth and oxygen at the interface between the two silicon layers as described above, the first electrode (not shown) connected to the silicon base 601 is formed and connected to the surface silicon layer 603. A second electrode (not shown) is formed. For example, each electrode may be formed by depositing a metal such as titanium by a sputtering method.

  According to the silicon light emitting device manufactured as described above, since the active layer is formed by doping rare earth and oxygen at the interface between the silicon base and the surface silicon layer, the doped rare earth and oxygen are present at the interface. Aggregates. This is because there is an effect of aggregating the contained elements (atoms) at the interface between the two silicon layers. For this reason, also in the silicon light emitting device in the fourth embodiment, the erbium-oxygen atom complex is formed with high efficiency in the active layer. As a result, also in the silicon light emitting device of the fourth embodiment, the light emission efficiency can be further increased.

  Further, according to the fourth embodiment, erbium is doped into an amorphous buried silicon oxide layer made of silicon oxide. For this reason, generation | occurrence | production of the damage (defect) in a silicon crystal by ion implantation can be suppressed now.

[Embodiment 5]
Next, a method for manufacturing the silicon light emitting element in the fifth embodiment of the present invention will be described with reference to FIGS. 7A to 7C. FIG. 7A to FIG. 7C are schematic cross-sectional views showing the states of the respective steps in the manufacturing process for explaining the method for manufacturing the silicon light emitting element in the embodiment of the present invention.

  First, as shown in FIG. 7A, a doped layer 702 is formed in the vicinity of the surface of the first silicon layer 701 by doping rare earth and oxygen. For example, heating is performed at 400 ° C. to 700 ° C., and the rare earth and oxygen are doped using, for example, an ion implantation method. The rare earth may be erbium. Here, the ion implantation conditions may be appropriately set so that the maximum distribution in the depth direction of the implantation amount is about 50 nm deep from the surface of the first silicon layer 701. The implantation depth may be set so that the rare earth and oxygen can reach the interface by the diffusion of rare earth and oxygen described later.

  Next, as shown in FIG. 7B, a second silicon layer 703 is bonded to the surface of the first silicon layer 701 on the side where the doped layer 702 is formed. For example, the bonding surface of each silicon layer is cleaned and chemically etched in hydrogen fluoride water. By this treatment, the natural oxide film on the bonding surface of each silicon layer is removed, and a hydrophobic hydrogen termination surface is formed on the surface of the bonding surface of each silicon layer. Next, the orientation of each silicon layer is set to an arbitrary angle (φ, θ), and both are pressure-bonded at room temperature (about 23 ° C.).

  Next, as described above, the two silicon layers bonded at room temperature are heated to 700 ° C. to 1000 ° C. in a nitrogen atmosphere, and the two are completely bonded together, and activation of the implanted ions and ion implantation are performed. And repairing damage to the silicon layer. Further, by this heat treatment, the implanted erbium and oxygen are diffused to form a state in which erbium and oxygen are doped at the interface 704, and as shown in FIG. 7C, a rare earth is formed at the interface 704 of the two silicon layers. Then, an active layer 712 doped with oxygen is formed.

  As described above, after forming the active layer 712 doped with rare earth and oxygen at the interface between the two silicon layers, the first electrode (not shown) connected to the first silicon layer 701 is formed, and the second silicon is formed. A second electrode (not shown) connected to the layer 703 is formed. For example, each electrode may be formed by depositing a metal such as titanium by a sputtering method.

  According to the silicon light emitting device manufactured as described above, since the active layer is formed by doping rare earth and oxygen at the interface between the two silicon layers, the doped rare earth and oxygen are aggregated at the interface. It becomes like this. This is because there is an effect of aggregating the contained elements (atoms) at the interface between the two silicon layers. For this reason, in the silicon light emitting device in the fifth embodiment, the erbium-oxygen atom complex is formed with high efficiency in the active layer. As a result, also in the silicon light emitting device of the fifth embodiment, the light emission efficiency can be further increased.

  As described above, according to the present invention, an interface between two silicon layers is formed, and an active layer is formed by doping rare earth and oxygen at the interface, so that light is emitted in the communication wavelength band. The light emission efficiency of the light emitting element using silicon to which rare earth such as erbium and oxygen are added can be further increased.

  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, as an SOI substrate, a SIMOX (Separation by implanted oxygen) substrate, a UNIBOND substrate manufactured by Soitec, or an ERTRAN (Epitaxial layer transfer) substrate manufactured by Canon can be used. The rare earth is not limited to erbium, and may be thulium, for example. With thulium, light emission in the communication wavelength band can be obtained.

  DESCRIPTION OF SYMBOLS 101 ... 1st silicon layer, 102 ... 2nd silicon layer, 103 ... Interface, 104 ... Active layer.

Claims (7)

A first step of bonding a second silicon layer to a first silicon layer on a substrate;
And a second step of doping the rare earth and oxygen into the interface between the first silicon layer and the second silicon layer to form an active layer at the interface. In the manufacturing method of the silicon light emitting element according to claim 1 ,
The surface silicon layer of the SOI substrate in which a surface silicon layer is formed on a base via a buried insulating layer is bonded to the first silicon layer, and the buried insulating layer and the base are removed, thereby removing the first A method for producing a silicon light-emitting element, wherein the second silicon layer made of the surface silicon layer is bonded to one silicon layer. A first step of doping rare earth and oxygen into the silicon oxide layer of the substrate in which the second silicon layer is formed on the first silicon layer on the substrate via the silicon oxide layer;
At least a second step of eliminating the silicon oxide layer by heating in an inert atmosphere and forming an active layer doped with rare earth and oxygen at the interface between the first silicon layer and the second silicon layer; A method for producing a silicon light emitting device, comprising: A first step of doping the first silicon layer on the substrate with rare earth and oxygen to form a doped layer;
A second step of bonding a second silicon layer to the surface of the first silicon layer on the side where the doped layer is formed;
The rare earth and oxygen of the dope layer are diffused by heating the first silicon layer and the second silicon layer, thereby doping rare earth and oxygen at the interface between the first silicon layer and the second silicon layer. And a third step of forming an active layer on the interface. In the manufacturing method of the silicon light emitting element according to any one of claims 1 to 4 ,
The method of manufacturing a silicon light emitting device, wherein the first silicon layer is of a first conductivity type and the second silicon layer is of a second conductivity type. In the manufacturing method of the silicon light emitting element according to any one of claims 1 to 4 ,
The method of manufacturing a silicon light emitting device, wherein the first silicon layer and the second silicon layer have the same conductivity type. In the manufacturing method of the silicon light emitting element according to any one of claims 1 to 6,
The method of manufacturing a silicon light emitting element, wherein the rare earth is erbium.

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