The present invention generally relates to an optical interconnection device capable of achieving intra-chip optical interconnection.
The optical interconnection is widely available in the field of long-distance signal transmission using an optical fiber based on the utilization of characteristics such as high-speed, wide-bandwidth transmission, superior noise immunity, and a fine diameter of a cable. On the other hand, in order to further increase the information processing speed in the information processing device, extremely short distance optical interconnection between boards, chips, or in a chip is necessary, and a technology development for this has been advanced currently.
Basic elements in the short-distance optical interconnection are a light emitting element, an optical waveguide, and a light receiving element. The light emitting element drives light emitting based on a signal in a send circuit and outputs an optical signal. The optical waveguide transmits the output optical signal. The light receiving element receives the transmitted optical signal and outputs it to a receive circuit. Patent Literature 1 describes that optical coupling between a first optical device (light emitting element) mounted on a substrate and a second optical device (optical waveguide) formed on the substrate is performed with a curved mirror consisted of a part of an oval sphere formed on the substrate.
Patent Literature 1: Japanese Patent Application Publication No. 2001-141965
In order to achieve the intra-chip optical interconnection, it is required to efficiently perform the optical coupling between the light emitting element or the light receiving element mounted on the substrate and the optical waveguide on the substrate. In the conventional art, an optical coupler has been used for this optical coupling between the light emitting element or the light receiving element and the optical waveguide. In this optical coupler, a deflection element such as a mirror, a prism, or a diffraction grating and a light condensing element such as a lens are required, and in order to obtain high optical coupling efficiency, a processing technique and a positioning technique with high accuracy are required in formation of the optical coupler. In the above-mentioned conventional art, a curved mirror obtained by integrating a light deflection element and a light condensing element is used. However, high accuracy in the formation is still required.
As described above, in order to achieve the intra-chip optical interconnection, an optical coupler which performs optical coupling between a light emitting element or a light receiving element and an optical waveguide with high coupling efficiency has been conventionally required. However, it is actually difficult to obtain such optical coupler. Thus, this has been a great obstacle to achieve the intra-chip optical interconnection.
One or more embodiments of the present invention may be an intra-chip optical interconnection with high efficiency by coupling between a light emitting element or a light receiving element and an optical waveguide formed in a substrate without using an optical coupler and the like.
The optical interconnection device according to one or more embodiments of the present invention includes: a Si semiconductor substrate; an optical waveguide formed on the Si semiconductor substrate; and a light emitting element formed at one end of the optical waveguide, wherein the light emitting element has a pn junction part obtained by performing an anneal treatment on a second semiconductor layer obtained by doping a first semiconductor layer in the Si semiconductor substrate with an impurity at high concentration, the anneal treatment being performed while irradiating the second semiconductor layer with light.
In the optical interconnection device having such characteristics, the end of an optical waveguide formed on an Si semiconductor substrate includes a light emitting element including a pn junction part formed on the Si semiconductor substrate as a light emission part. Thus, an optical signal generated from the light emitting element can be introduced into the optical waveguide without using an optical coupler. Therefore, it becomes possible to achieve an intra-chip optical interconnection with high efficiency.
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Embodiments of the present invention are described with reference to the drawings.
An optical interconnection device 1 includes an Si semiconductor substrate 10, an optical waveguide 2 formed on the Si semiconductor substrate 10, and a light emitting element 3 formed at one end of the optical waveguide 2. In the Si semiconductor substrate 10, for example, an n-type first semiconductor layer 10n is formed. In the Si semiconductor substrate 10, a second semiconductor layer 10p obtained by doping the first semiconductor layer 10n with an impurity is further formed. The second semiconductor layer 10p is, for example, a p-type semiconductor layer.
In the vicinity of the interface between the first semiconductor layer 10n and the second semiconductor layer 10p, a pn junction part 10pn is formed. Insulation layers 11 are formed in the Si semiconductor substrate 10. In an example shown in
As shown in
The light emitting element 3 includes, as a light emission part, the pn junction part 10pn formed in the vicinity of the interface between the first semiconductor layer 10n and the second semiconductor layer 10p. In an example shown in
That is, the light emitting element 3 includes the first electrode 12 formed on the second semiconductor layer 10p, the second electrodes 14 formed on the first semiconductor layer 10n, and the pn junction part 10pn formed of the first semiconductor layer 10n and the second semiconductor layer 10p, and the first electrode 12 and the second electrodes 14 are arranged so as to sandwich the surface insulation layers 11b on one surface side of the Si semiconductor substrate 10. Although the second electrodes 14 are arranged on both sides of the first electrode 12 in the example shown in
Subsequently, as shown in
Subsequently, as shown in
The Si semiconductor substrate itself is an indirect transition semiconductor and has low light emitting efficiency, cannot obtain useful light emission merely by forming a pn junction part, and has no light transmission properties in the visible light region. However, the Si semiconductor substrate 10 is subjected to annealing with the assistance of phonon to generate dressed photons in the vicinity of the pn junction part 10pn and change Si which is an indirect transmission-type semiconductor to as if it is a direct transition-type semiconductor, thereby achieving high-efficiency, high-output pn junction-type light emission. In order to obtain such pn junction-type light emission, doping with an impurity which is a Group 13 element such as boron (B) at high concentration is performed. An example of impurity doping conditions (in the case of boron (B)) at the time of the doping includes a dose density: 5*1013/cm2, acceleration energy at the time of the injection: 700 keV, a wavelength of light L with which the irradiation is performed in the stage of the annealing: a desired wavelength band.
Thereafter, as shown in
A process shown in
According to such optical interconnection device 1, since the optical waveguide 2 and the light emitting element 3 are fabricated on one Si semiconductor substrate 10, light emitted from the pn junction part 10pn of the light emitting element 3 is propagated through the second semiconductor layer 10p and is directly incident on the optical guide layer of the optical waveguide 2. At that time, in each of the second semiconductor layer 10p in the optical waveguide 2 and the second semiconductor layer 10p in the light emitting element 3, a pattern in formed by the same photolithography process. Thus, the optical waveguide 2 and the light emitting element 3 can be formed integrally without a specific positioning, and light emitted from the light emitting element 3 can be introduced into the optical waveguide 2 without any loss.
An optical interconnection device 1 (1A) according to one or more embodiments is another embodiment of a structural example of an optical wave guide 2 (2A). In this example, a rib 2R is formed on the surface of a first semiconductor layer 10n to form a rib-type optical waveguide 2 (2A). In this case, a pattern of an etching mask for forming the rib 2R is formed on an extension of a pattern of the second semiconductor layer 10p in the light emitting element 3. Thus, a light axis of a pn junction part 10pn in the light emitting element 3 can agree with a light axis of the optical waveguide 2. In an example shown in
That is, the light receiving element 4 includes the first electrode 12 formed on the second semiconductor layer 10p, the second electrodes 14 formed on the first semiconductor layer 10n, and the pn junction part 10pn formed of the first semiconductor layer 10n and the second semiconductor layer 10p, and the first electrode 12 and the second electrodes 14 are arranged so as to sandwich the surface insulation layers 11b on one surface side of the Si semiconductor substrate 10. Although the second electrodes 14 are arranged on the both sides of the first electrode 12 in the example shown in
The light emitting drive part 30 or the light receiving detect part 40 can be consisted of a semiconductor element 5 such as a MOS-type transistor as shown in
As described above, the optical interconnection device according to one or more of the embodiments of the present invention can achieve an intra-chip optical interconnection with high efficiency by coupling the light emitting element 3 or the light receiving element 4 formed in the semiconductor substrate and the optical waveguide 2 without using an optical coupler. In particular, the light emitting wavelength, the light transmission wavelength, and the light receiving wavelength can agree with one another by setting light with which irradiation is performed at the time of forming the optical waveguide 2, the light emitting element 3, and the pn junction part 10pn in the light receiving element 4 to be light at the same wavelength. The wavelength of the light used at that time can be selected from any wavelength in the near-infrared to near-ultraviolet region. Accordingly, intra-chip optical interconnection having less transmission loss and a less crosstalk can be achieved in any transmission band.
The above-mentioned optical waveguide 2 is not required to be linear and may be curved, bent, or branched into plural guides. The optical waveguide 2 may have a structure in which signals of one or plural light emitting elements 3 are connected to plural or one light receiving element 4.
Although the above-mentioned description is made with reference to an example of an Si semiconductor substrate, any of other semiconductor substrates which can be replaced with the Si semiconductor substrate can be used.
Although the disclosure has been described with respect to only a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that various other embodiments may be devised without departing from the scope of the present invention. Accordingly, the scope of the invention should be limited only by the attached claims.
Number | Date | Country | Kind |
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2012-246684 | Nov 2012 | JP | national |
This application claims the benefit of International Application PCT/JP2013/076922, filed Oct. 3, 2013 and Japanese Patent Application JP2012-246684 filed Nov. 8, 2012, both of which are incorporated herein by reference in their entirety.
Filing Document | Filing Date | Country | Kind |
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PCT/JP2013/076922 | 10/3/2013 | WO | 00 |