JP2007164110A - Optical I / O part manufacturing method and optical integrated circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve bidirectional optical transmission in in-chip optical transmission and inter-chip optical transmission, to decrease the total wiring distance and the total wiring spacing, and to increase the total transmission capacity. <P>SOLUTION: An optical element produced in an epitaxial lift-off process is transferred to a portion in an optical integrated circuit where optical input and output are carried out to and from the optical wiring. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for producing an optical I / O portion useful for intra-chip optical transmission and inter-chip optical transmission in an optical integrated circuit such as Si-LSI, and an optical integrated circuit including the optical I / O portion. It is.

Conventionally, research on in-chip optical transmission such as optical wiring and optical I / O section in Si-LSI has been activated based on names such as Si photonics, a) heterogeneous epitaxy technology, b) Si substrate Optical wiring formation technology such as upper Si waveguide and SiON waveguide, c) SOI (Silicon
On Insulator) technology, d) CMOS (Complementary Metal Oxide Semiconductor) technology, etc. are known.

  In particular, means for providing an optical I / O portion (= optical input / output portion) by heteroepitaxial growth of a compound semiconductor or Ge on Si-LSI is often used. Also, various optical elements such as a Raman laser element of 1.55 μm long wavelength band, an evanescent light incident type light receiving element such as 0.85 μm short wavelength band, and an optical modulator are formed on the chip by CMOS / SOI technology. The technology is also actively researched and developed.

  On the other hand, for inter-chip optical wiring such as between CPUs and memories, a) ELO process technology, b) heterogeneous integration technology, c) waveguide formation technology on a board using polymer or fiber, and the like are known.

  In particular, an ELO (Epitaxial Lift Off) process technology that extracts only the active layer of the light emitting / receiving element, that is, the active portion of the thin film from the substrate, allows the ELO emitting / receiving thin film element to be placed on the Si-LSI or optical waveguide. Heterogeneous integration technology, such as mounting or embedding in an optical waveguide, has been actively researched and developed. With this integration technology, it is possible to add an optical I / O interface to a Si-LSI or an optical waveguide for the purpose of optical transmission between chips.

  However, the conventional technology as described above has the following problems to be solved.

  First, with regard to heteroepitaxial growth technology for intra-chip optical transmission, basic research efforts are being made, such as defect removal in the epi layer, and CMOS / SOI technology is also in the basic research stage. The laser oscillation output is also extremely low, and the wavelength does not match between the light emitting side and the light receiving side of the laser. That is, since the light emitting side has a long wavelength and the light receiving side has a short wavelength, long wavelength light cannot be received, and light cannot be transmitted or received even if they are combined. Therefore, there is no practical bidirectional optical transmission means for intra-chip optical transmission.

  In addition, it is desirable to reduce the total wiring distance and wiring interval as much as possible and to increase the total transmission capacity in a narrow space such as in a chip as compared with optical transmission between boards. However, effective practical means for realizing these requirements have not been realized yet.

  On the other hand, for inter-chip optical transmission, it is known that heterogeneous integration technology is used for Si-LSIs, optical elements, waveguides, etc. as described above, but the memory bandwidth that is the bottleneck of inter-chip optical transmission However, there is no practical means for effectively utilizing these heterogeneous integrated mounting techniques.

  Therefore, in view of the circumstances as described above, the present invention enables bidirectional optical transmission in intra-chip optical transmission and inter-chip optical transmission, and shortens the total wiring distance and wiring interval and increases the total transmission capacity. It is an object of the present invention to provide a method of manufacturing an optical I / O unit that can be achieved, and an optical integrated circuit including the optical I / O unit.

  The optical I / O part manufacturing method of the present invention solves the above-mentioned problems. First, an optical element generated by epitaxial lift-off is used as a part for optical input / output with an optical wiring. It is characterized by transferring.

  Second, in a multi-core processor in which a plurality of processor cores and a cache are integrated, the optical element is transferred to a portion where optical input / output is performed between the processor core and the optical interconnection bus connecting the cache. And

  Third, in a multi-core processor in which a plurality of processor cores and a cache are integrated, the optical element is transferred to a portion that performs optical input / output with an optical wiring bus that connects the processor cores. To do.

  Fourth, in a multi-core processor in which a plurality of processor cores and a cache are integrated, the optical element is transferred to a portion where optical input / output is performed with an optical wiring connecting other semiconductor chips. .

  Fifth, in a memory constituted by a plurality of memory chips, the optical element is transferred to a portion that performs optical input / output with an optical wiring connecting other semiconductor chips.

  Sixth, the optical element is transferred to a portion that performs optical input / output in a demultiplexer that electrically demultiplexes electrical signals from a multicore processor in which a plurality of processor cores and a cache are integrated. .

  Seventh, the optical element is transferred to a portion that performs optical input / output in a multiplexer that electrically multiplexes a plurality of electrical signals from a memory constituted by a plurality of memory chips.

  Eighth, the optical element is a WDM compatible optical element.

  In the integrated circuit according to the present invention, ninthly, the optical I / O section for performing optical input / output with the optical wiring in the circuit is composed of optical elements generated by epitaxial lift-off. It is characterized by.

  Furthermore, in the integrated circuit of the present invention, tenthly, an optical I / O unit for performing optical input / output with an optical wiring connecting another optical integrated circuit is an optical element generated by epitaxial lift-off. It is configured.

  According to the first to eighth aspects of the present invention, an optical element is generated by ELO without using the conventional heteroepitaxy growth technology or CMOS / SOI technology, and this is transferred to the above-described portion, thereby transmitting the light within the chip. In addition, an optical I / O unit responsible for optical transmission between chips can be manufactured. According to ELO, a thinned light emitting / receiving element can be formed, so that an optical I / O unit constituted by this optical element enables both short wavelength light and long wavelength light to be transmitted and received in a chip and between chips. Thus, the total wiring distance including the optical I / O unit and the optical wiring and the distance between the optical I / O unit and the optical wiring can be shortened, and the total transmission capacity can be increased.

  According to the ninth and tenth aspects of the present invention, an optical integrated circuit capable of similarly excellent in-chip optical transmission and inter-chip optical transmission is realized by using an optical element based on ELO as an optical I / O section. can do.

[Embodiment for intra-chip optical transmission]
FIG. 1 shows an embodiment of the present invention related to intra-chip optical transmission.

  In the present invention, as illustrated in FIG. 1, for the purpose of optical transmission in the optical integrated circuit 1, an optical element (hereinafter referred to as “ELO optical element”) 5 generated by ELO is mounted on a substrate. The optical I / O unit 50 for the optical wiring 4 is formed by transferring to the optical wiring 4 connecting the CPU 2, the cache 3, and the like.

  More specifically, in the embodiment of FIG. 1, the semiconductor chip optical integrated circuit 1 is a multi-core processor 10 in which a plurality of processor cores 2 and a cache 3 are integrated on a Si substrate 6. The global memory bus between the processor core 2 and the cache 3 and the bus between the processor cores 2 are constituted by optical wirings 4 such as optical waveguides, and the processor cores 2 connected by these optical wirings 4 As the optical I / O unit 50 and the optical I / O unit 50 of the cache 3, the ELO optical element 5 having a light emitting / receiving function is heterogeneously integrated.

  In the multi-core processor 10 in which the ELO optical element 5 is mounted, both the short wavelength band of 850 nm and the long wavelength band of 1300 to 1550 nm are used as optical wavelengths used for optical signal transmission according to the materials of the ELO optical element 5 and the optical wiring 4. You can choose freely. For example, in the short wavelength band, an AlGaAs VCSEL (Vertical Cavity Surface Emitting Laser) can be used as the light emitting element, and Si, GaAs, InP, or the like can be used as the light receiving element. In the long wavelength band, an InGaAs (P) -based element can be applied to both the light emitting element and the light receiving element.

  As the ELO optical element 5, a multi-wavelength light receiving / emitting element compatible with WDM (Wavelength Division Multiplexing) may be used.

Further, as the optical wiring 4, for example, as illustrated in FIGS. 2A and 2B, an optical waveguide 40 having an SOI structure can be applied. 2A and 2B, optical waveguides 40 having a core size of 3 × 2 μm (about Δ3%, particularly Δ3.3%) made of SiON on the Si substrate 6 and the SiO ₂ film 7 (FIG. 2A). )), An optical waveguide 40 (FIG. 2B) having a core size of Si of 0.5 × 0.2 μm (Δ5-6%, especially Δ5.8%) is formed by RIE (Reactive Ion Etching) The ELO optical element 5 is mounted above the optical waveguide 40 so that light can be input and output with each other.

  Here, the mounting process of the ELO optical element 5 will be described with reference to FIG. 3 as appropriate.

  First, aligner, plasma CVD (Chemical Vapor Deposition) apparatus, IBE (Ion Beam Evaporation) apparatus, EB (Electron Beam) evaporation apparatus, resistance heating evaporation apparatus, ion milling apparatus The optical element 51 is formed from the epitaxial layer 13 (FIG. 3A) laminated on the substrate 11 in the wafer state via the etch stop layer 12 using a semiconductor process apparatus such as a sintering furnace (FIG. 3 ( b)), an electrode 52 is formed thereon (FIG. 3C), and a protective wax agent 14 is deposited (FIG. 3D).

Subsequently, RIE using a reactive gas such as SiCl ₄ , SF _6, etc. is performed on the wafer that has been processed into an element as described above, and the optical element 51 is separated from the substrate 11 (FIG. 3E). Thereby, the ELO optical element 5 is formed.

  The ELO optical element 5 is transferred to an expansion sheet ring diaphragm 15 (FIG. 3F), and this is transferred to the Si substrate 6 of the multi-core processor 10 on which the electrode 16 is formed, that is, a Si-LSI substrate. Then, the image is transferred onto the upper surface 6 by using an aligner device, an FC (Flip Chip) bonder device, a pressing probe device, or the like (FIG. 3G).

  The transfer process itself of the optical element 5 so far is known and disclosed in, for example, “IEEE Photon. Lett., 1991, 3 (12), pp. 1123-1126”. The main feature of the present invention is that the optical element 5 is transferred as a light I / O unit 50 to a portion where light input / output is performed with the optical wiring 4, and a known transfer process can be adopted. .

  On the other hand, as an original transfer process, an adhesive is applied between the ELO optical element 5 and the diaphragm 15 so that the adhesive strength decreases when irradiated with UV light, and then transferred (FIG. 3 (f)). By irradiating UV light using a UV light irradiation device, the ELO optical element 5 is separated from the diaphragm 15 and transferred onto the Si substrate 6 (FIG. 3G).

  Thereafter, the bump-like electrode 16 on the Si-LSI substrate 6 and the electrode 52 of the ELO optical element 5 are bonded to each other using an FC bonder device, a flash alloy furnace, a plasma clean device, or the like (FIG. 3 (h)). .

  As a result, the ELO optical element 5 is formed and mounted on the Si-LSI substrate 6, and the optical I / O unit 50 of the multi-core processor 10 is formed.

  After completion, morphological evaluation may be performed using SEM (Scanning Electron Microscopy), TEM (Transmission Electron Microscopy), or the like.

When the ELO optical element 5 is compatible with WDM, a light emitting element or a light receiving element corresponding to a plurality of wavelengths λ _{1 to} λ _n is mounted on the diaphragm 15 in the same manner as described above, and the wavelengths λ ₁ to by performing sequentially transferred every lambda _n, the ELO optical element 5 WDM corresponding to Si-LSI substrate 6 can be heterogeneous integration.

  In the case where a polymer material is used as the optical waveguide 40 constituting the optical wiring 4, the thinned ELO optical element 5 is embedded in the polymer material, and then the optical waveguide 40 with the ELO optical element 5 and the Si-LSI substrate 6. It is possible to consider both of the process of mounting with facing the optical waveguide 40 or the process of mounting the ELO optical element 5 on the Si-LSI substrate 6 and then mounting it facing the optical waveguide 40 as described above. In any process, the configuration is such that the ELO optical element 5 is transferred to a portion for inputting / outputting light to / from the optical wiring 4.

  The former embedding form will be further described. For example, as illustrated in FIGS. 4 and 5, the optical element 5 is embedded in the support substrate 43 (FIG. 4) or the clad 42 (FIG. 5) constituting the optical waveguide 40. be able to.

  The ELO optical element 5 in FIG. 4 has an electric substrate 9 (or a semiconductor such as an LSI) in contact with the bottom of the support substrate 43 through an electrode 52 provided therein and a through-hole electrode 431 formed through the support substrate 43. Device). In the ELO optical element 5 in FIG. 5, only the electrode 52 protrudes outside the clad 42 and is electrically connected to an electric substrate 9 (or a semiconductor element such as an LSI) disposed close to the bottom of the clad 42.

  In the form of FIG. 4, the support substrate 43 is formed of the same polymer material as that of the clad 42, and the optical waveguide 2 is integrally formed with the core 41 and the clad 42. Of course, it is also possible to use a polymer material different from the clad material as the support substrate 43.

  Here, an example of a process for manufacturing the embedded type in FIG. 4 will be described with reference to FIGS. 6A to 6E as appropriate.

  First, as illustrated in FIG. 6A, an ELO optical element 5 having an optical element 51 thinned out by ELO and an electrode 52 provided so as to protrude on the optical waveguide 40 is formed by a translucent resin 53. Paste directly. The adhesion is performed by curing the translucent resin 53 by UV light irradiation or heating from the back surface. Subsequently, as illustrated in FIG. 6B, using the same polymer material as the clad 42, the support substrate 43 is coated by spin coating or the like so as to cover the ELO optical element 5 and support the clad 42. Next, as illustrated in FIG. 6C, the through-hole electrode 431 is formed on the support substrate 43. Then, as illustrated in FIG. 6D, this is mounted on the electric substrate 9 (or a semiconductor element such as an LSI).

  According to the above, as illustrated in FIG. 7, mounting from one chip to a plurality of chips having different wavelengths is possible at any position on the wafer-like large-area Si substrate 6 by a normal photolithography process. Therefore, a scalable and low-cost mounting is possible.

  In addition, since it is compatible with WDM, it has function expandability, and the thickness of the ELO optical element 5 is usually 10 μm or less. The process becomes possible.

  7 denotes a modulator, which modulates light from an external light source (arrow in the figure) and inputs it to the optical wiring 4, or modulates light from a light emitting element mounted on-chip to generate light. Input to wiring 4.

[Embodiment 1 regarding optical transmission between chips]
In the present invention, for example, as illustrated in FIG. 8, for optical transmission between semiconductor chips, a part that performs optical input / output with the optical wiring 4 connecting them in the multi-core processor 10, the external memory 100, and the like. It is also possible to transfer and mount the ELO optical element 5 to form the respective optical I / O portions 50.

  The mounting process of FIG. 3 described above can be applied to the mounting process of each ELO optical element 5 in this case, and the same optical semiconductor and waveguide material as described above can be used.

  Needless to say, the embodiment of the intra-chip optical transmission in FIG. 1 and the embodiment of the inter-chip optical transmission in FIG. 8 can be combined, and the optical transmission by the ELO optical element 5 and the optical wiring 4 in the multi-core processor 10. In addition, an optical integrated circuit that enables both the ELO optical element 5 and the optical transmission between the multi-core processor 10 and the external memory 100 by the optical wiring 4 can be realized.

[Embodiment 2 concerning optical transmission between chips]
By the way, for optical transmission between the CPU (multi-core processor 10) and the external memory 100, in order to increase the access speed to the external memory 100, for example, as illustrated in FIG. Embodiments divided into memory chips 110 (# 1 to #n) can be employed.

More specifically, in this case, for example, in FIG. 9, the external memory 100 composed of a plurality of memory chips 110 (# 1, # 2, # 3... #N) is connected to the multi-core processor via one optical wiring 4. 10 and an optical integrated circuit 200 mounted so as to be capable of optical transmission. Electrical signals to be sent from each memory chip 110 to the multi-core processor 10 are electrically demultiplexed (wavelengths λ ₁ , λ ₂ , λ ₃ ... as optical I / O unit 50 in the multiplexer MUX (multiplexer) that · lambda _n) to also electrically multiplexing a plurality of electrical signals to be sent from the multi-core processor 10 to the memory chips 110 (wavelength lambda _1, lambda ₂ , as an optical I / O unit 50 in the demultiplexer DEMUX (demultiplexer the) for λ ₃ ··· λ _n) to, the ELO optical device 5 having a light receiving and emitting functions described above It is heterogeneous integrated by instrumentation process.

  As a result, not only high-speed optical transmission between the multi-core processor 10 and the external memory 100 by the ELO optical element 5 and the optical wiring 4 can be performed, but also a wasteful idling time of the multi-core processor 10 can be reduced. The time can be shortened to 1/3 to 1/4 of the conventional time.

  Further, the bandwidth per channel can be increased by setting the ELO optical element 5 of each optical I / O unit 50 to a WDM configuration as necessary.

[Embodiment 3 regarding optical transmission between chips]
In order to increase the access speed to the external memory 100, for example, the embodiment illustrated in FIG.

  First, the memory chips 110 constituting the external memory 100 are connected and arranged in a tree form of a plurality of stages and a plurality of columns (the uppermost stage / left end column = # 11 to the lowermost stage / right end column = # mn).

  In each of these memory chips 110, the optical I / O unit 50 is provided by heterogeneously integrating the WDM compatible ELO optical elements 5 by the mounting process shown in FIG.

  Similarly, each optical I / O unit 50 in the multi-core processor 10 corresponding to each stage of the external memory 100 is also formed by the WDM compatible ELO optical element 5.

Then, a WDM configuration in which different optical wavelengths (may be a plurality of wavelength groups) are assigned to each memory chip 110 is adopted. In FIG. 10, wavelengths λ ₁₁ to λ _1n , λ _{21 to} λ _2n ... Λ _{m1 to} λ _mn are assigned to # 11 to #mn of the memory chip 110, and each ELO light receives and emits light of the respective wavelengths. Element 5 performs. ELO optical device 5 of the multi-core processor 10 performs wavelength lambda _11-1N of each stage in charge respectively, lambda ₂₁ and to [lambda] _2n · · · emitting and receiving light λ _m1 ~λ _mn.

  Thereby, parallel simultaneous reading to each memory chip 110, that is, multi-threading is possible, and the calculation processing speed can be greatly improved.

It is the top view which showed one Embodiment of this invention regarding the optical transmission in a chip | tip. (A) (b) is sectional drawing which showed one Embodiment of the ELO optical element, respectively. The figure for demonstrating the formation and mounting process of an ELO optical element. It is sectional drawing which showed one Embodiment which embedded the ELO optical element in the optical waveguide. It is sectional drawing which showed one Embodiment which embedded the ELO optical element in the optical waveguide. It is a figure for demonstrating the manufacturing process of a buried type. It is a figure for demonstrating this invention regarding the optical transmission in a chip | tip. It is the top view which showed one Embodiment of this invention regarding the optical transmission between chips | tips. It is the top view which showed another one Embodiment of this invention regarding the optical transmission between chips | tips. It is the top view which showed another one Embodiment of this invention regarding the optical transmission between chips | tips.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical integrated circuit 10 Multi-core processor 2 Processor core (CPU)
DESCRIPTION OF SYMBOLS 3 Cache 4 Optical wiring 40 Optical waveguide 41 Core 42 Clad 43 Support substrate 431 Through-hole electrode 5 ELO optical element 50 Optical I / O part 51 Optical element 52 Electrode 53 Translucent resin 6 Si substrate (Si-LSI substrate)
7 SiO ₂ film 8 Modulator 9 Electric substrate (or semiconductor element such as LSI)
DESCRIPTION OF SYMBOLS 11 Substrate 12 Etch stop layer 13 Epi layer 14 Wax agent 15 Diaphragm 16 Electrode 100 External memory 110 Memory chip 200 Optical integrated circuit

Claims (10)

  An optical I / O portion manufacturing method, wherein an optical element generated by epitaxial lift-off is transferred to a portion where optical input / output is performed with an optical wiring.   2. A multi-core processor in which a plurality of processor cores and a cache are integrated, wherein the optical element is transferred to a portion where optical input / output is performed between an optical wiring bus connecting the processor core and the cache. The optical I / O part manufacturing method as described.   2. The optical element is transferred to a portion that performs optical input / output with an optical wiring bus that connects the processor cores in a multi-core processor in which a plurality of processor cores and a cache are integrated. Optical I / O part manufacturing method.   2. The multi-core processor in which a plurality of processor cores and a cache are integrated, wherein the optical element is transferred to a portion that performs optical input / output with an optical wiring connecting another semiconductor chip. Optical I / O part manufacturing method.   2. The optical I / I according to claim 1, wherein, in a memory constituted by a plurality of memory chips, the optical element is transferred to a portion where optical input / output is performed with an optical wiring connecting another semiconductor chip. O part production method.   The optical element is transferred to a portion that performs optical input / output with an optical wiring in a demultiplexer that electrically demultiplexes electrical signals from a multi-core processor in which a plurality of processor cores and a cache are integrated. The method for producing an optical I / O portion according to claim 1.   The optical element is transferred to a portion that performs optical input / output with an optical wiring in a multiplexer that electrically multiplexes a plurality of electrical signals from a memory constituted by a plurality of memory chips. Item 2. A method for producing an optical I / O part according to Item 1.   The optical I / O part manufacturing method according to claim 1, wherein the optical element is a WDM compatible optical element.   An optical integrated circuit, wherein an optical I / O unit for inputting / outputting light to / from an optical wiring in the circuit is composed of an optical element generated by epitaxial lift-off. An optical integrated circuit, wherein an optical I / O unit that inputs and outputs light to and from an optical wiring connecting another optical integrated circuit is composed of an optical element generated by epitaxial lift-off.

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