JP2006047894A - Optical waveguide device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical waveguide device that can perform photodetection while efficiently propagating light inside an optical waveguide and that can be easily manufactured. <P>SOLUTION: The optical waveguide device 23a is provided with an optical waveguide 21a such as an SiO<SB>2</SB>film for guiding light from a light incident section to a light emitting section, a light receiving part 2 such as a photo diode installed in contact with the outer face of this optical waveguide 21a, and a light reflection part 5 with a 45° mirror surface installed inside the optical waveguide 21a. A signal light 11, for which a vertical incident light beam 11 is guided after being reflected by a mirror 9, is converted 90° in the optical path by the light reflection part 5 and made incident to the light receiving part 2 for monitoring, while the remaining signal light is emitted from the optical waveguide 21a. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical waveguide device used as an optical wiring or the like.

  Conventionally, signal transmission between semiconductor chips such as LSIs (Large Scale Integrated Circuits) is generally performed by electric signals via substrate wiring. However, with the recent increase in functionality of MPU (Microprocessor Unit), the amount of data exchanged between chips has increased remarkably, making it necessary to increase the speed of signals and increase the density of signal wiring. As a result, various high frequency problems have emerged.

  Typical of these are EMC / EMI (Electro-Magnetic Compatibility / Interference) such as signal delay due to wiring resistance and capacitance, impedance mismatch, or noise and crosstalk. For example, compatibility with the electromagnetic environment). In order to solve such problems, various methods such as optimization of wiring arrangement and development of new materials have been developed.

  First, of these methods, the improvement of the back-end wiring material in the chip will be described. Until now, as the design rules for higher integration and higher speed have been refined, the wiring has also been miniaturized, and each time we use various methods such as optimization of layout structure and development of new materials, The end wiring is improved and solved.

For example, from the 0.18 micron rule generation to the 0.13 μm micron rule generation in terms of design rules, wiring has been formed with a structure using SiO ₂ as an insulating film and aluminum as a metal conductor, but 0.9 μm In the (or 90 nm) generation, instead of aluminum, copper having a low specific resistance is used as a wiring metal material. In the 65 nm generation, which is said to be the most advanced process that has started mass production, in addition to copper wiring, a low dielectric constant film A structure that reduces the total wiring RC delay by using a composite (hereinafter referred to as a Low-k film) is used.

  However, in recent years, the effects of optimizing the back-end wiring arrangement and the development of new materials such as copper and low dielectric constant films have been hampered by physical limitations, and the number of wiring layers has increased due to advanced miniaturization. In order to realize further higher functionality of the system in the future, it is necessary to review the shrink itself based on the premise of miniaturization in the design rule of a simple semiconductor chip. In recent years, various drastic measures have been proposed to solve these problems, but the following are representative examples.

  For example, a reduction in the effective dielectric constant of the insulating film by the Hy-Brid structure and a back-end reverse scaling method.

  Among them, the back-end reverse scaling method is miniaturized in the lower layer wiring due to the shrinkage of scaling, while the upper layer global wiring and semi-global wiring are conversely expanded to suppress wiring delay. It is a structure to do.

  As described above, various structures, materials, processes, etc. for optimizing the back-end wiring have been devised and implemented, and the elements are miniaturized when assuming the 32 nm Node and beyond after the 42 nm Node currently in the research and development stage. Prior to the process, the wiring structure for transmitting sufficient transmission capacity information in the required frequency band corresponding to the operating speed of the element had already failed, and it was shrunk by electrical signal transmission consisting of insulating film and metal There is a need to introduce some new method to replace it.

  Next, a method for optimizing electrical wiring by chip mounting will be described.

  Apart from optimizing the back-end wiring structure in the chip as described above, various chip mounting such as wiring layout optimization and new material development has been conducted mainly by the mounting industry so far to solve the above problem. We make full use of the technique and are solving it.

  In order to realize further enhancement of the functions of future systems, these problems will occur in high frequency transmission by reviewing the structure of the printed wiring board that is premised on mounting a simple semiconductor chip. Various drastic measures have been proposed to solve this problem, but the following are representative examples.

  The above-mentioned problems include, for example, reflection (impedance match) in which a reflected wave is generated due to a change in the wiring cross-sectional area and malfunction occurs, and energy decline that increases wiring resistance due to high-frequency transmission and increases power consumption ( Impedance increases), crosstalk (simultaneous switching noise) that causes signal instability and malfunction due to high-frequency transmission, and electromagnetic noise (EMC) that causes electromagnetic interference due to high-density wiring and increases skew.

  And as a solution for these problems, for example, fine wiring bonding by multi-chip module (MCM), two-dimensional semiconductor chip sealing and integration using polyimide resin, etc., electric wiring bonding, substrate Developments such as three-dimensional bonding of semiconductor chips by bonding have been made.

  First, fine wiring bonding by MCM realizes fine wiring bonding that cannot be formed on a conventional mother board (multilayer printed circuit board) by mounting a high-performance chip on a precision mounting board such as ceramic or silicon. As a result, the pitch of the wiring can be reduced, and the amount of data exchange can be dramatically increased by widening the bus width.

  Next, for electrical wiring bonding by chip sealing / integration, various semiconductor chips and the like are two-dimensionally sealed / integrated using polyimide resin or the like, and fine wiring bonding is performed on the integrated substrate. . As a result, the pitch of the wiring can be reduced, and the amount of data exchange can be dramatically increased by widening the bus width.

  Next, three-dimensional bonding of the semiconductor chips by bonding the substrates is performed by providing a through electrode on each chip and bonding them to form a laminated structure. This shortens the connection between different chips and avoids problems such as signal delay. However, new problems such as an increase in the amount of heat generated due to lamination and thermal stress between chips arise.

  Furthermore, as a technique for realizing more fundamentally high speed and large capacity of signal transmission / reception, an optical waveguide device 73a having an optical signal transmission coupling technique using optical wiring as shown in FIG. 16 has been developed (for example, described later). (See Non-Patent Document 1).

  In this structure, a surface emitting laser 68 provided with a through hole 64, a surface emitting laser driving IC 63, and a through hole electrode is supported on a printed wiring board 70 by an interposer 61 including a submount 65 and a metal post 66. A photodiode receiving IC 60 and a photodiode 62 provided with a through-hole electrode are supported on a printed wiring board 70 by an interposer 61 composed of a submount 65 and a metal post 66, so that light is incident. An optical waveguide 67 having an optical component 69 in each of the light emitting portion and the light emitting portion is disposed on the printed wiring board 70, and a surface emitting laser 68 provided with a through-hole electrode and a photodiode 62 provided with a through-hole electrode are It is disposed at a position corresponding to the optical component 69.

  In this technique, an electrical signal is converted into an optical signal and sent through an optical waveguide 67, thereby greatly improving the transmission speed between chips. In addition, the optical signal does not require any countermeasure for electromagnetic waves, and a relatively free wiring design is possible. However, since new problems such as time loss and optical element cost due to conversion arise, this countermeasure becomes important. Hereinafter, in the present specification, when the light emitting element and the light receiving element are not distinguished, they may be referred to as optical elements.

  Next, various types of optical wiring technologies corresponding to signal transmission between chips have been proposed, for example, an active interposer method (see p. 125 of Non-Patent Document 1 described later, FIG. 7). Free space transmission method (see p.123 of Non-Patent Document 1 described later, see FIG. 5), optical connector connection method (see p.122 of Non-Patent Document 1, described later, FIG. 4), optical waveguide embedding method (described later) P. 124 of Non-Patent Document 1 and FIG. 6) and an optical waveguide surface mounting method (see Non-Patent Document 2 described later).

  For example, in the active interposer method, an optical waveguide is mounted on a board, optical fiber connectors are attached to the incident side end and the output side end of the optical waveguide, and transmission between the boards is performed by an optical fiber. The optical element is mounted on the back surface of the transceiver module and is precisely positioned with respect to the 45 ° total reflection mirror of the waveguide.

  The advantage of this method is that it can be deployed on an existing board system, and because it uses an optical fiber, it can be widely applied both inside and outside the board. However, because the structure is large, the cost is high, it is difficult to align the optical axis, the electrical transmission path is difficult to shorten, and it is not suitable for high-frequency transmission, and an optical fiber is used as the transmission medium. The problem is that there is a limit to the number of buses.

  Next, in the free space transmission system, an optical wiring board (quartz) is mounted on the back side of the board as an optical transmission path, and light is reflected in a zigzag manner in the optical wiring board to propagate signals. In order to facilitate alignment of the optical axis, a hybrid optical system in which several lenses are combined is configured.

  The advantage of this method is that, in principle, multi-channels (multiplex transmission) of several thousand levels are possible by optical element array and free space transmission, and the optical axis alignment is possible because of the hybrid optical system. It is easy. However, there are problems that the optical wiring board (quartz) is expensive and that the signal propagation due to reflection tends to disturb the waveform and increase the propagation loss. In addition, since many newly developed technologies are incorporated, there is also a problem that there is almost no track record regarding reliability.

  Next, the optical connector connection method is an optical transmission module system in which a small optical fiber connector is attached around the LSI chip, transmission between LSI chips is performed with an optical fiber, and the optical path can be freely set after the LSI is mounted. To do.

  The advantage of this method is that the optical connector and the optical path are guaranteed to be coupled with an optical connector, which eliminates the need for a costly optical axis alignment process and uses an optical fiber. Transmission is possible, and it can be deployed on an existing board system. However, there is a limit to miniaturization of the optical connector module, and it is difficult to shorten the electrical wiring between the LSI chip and the optical connector. Therefore, it is not suitable for high-frequency transmission, and an optical fiber is used as a transmission medium. Since it is adopted, there are problems in that there is a limit to the number of buses and that there are many components and it is difficult to reduce the cost per bus.

  Next, the optical waveguide embedding method is a method in which an optical element is directly attached to the back surface of an LSI, an optical waveguide is embedded in a printed board, and optical wiring is provided while maintaining the form of an existing board system. Further, by adopting a microlens for coupling the optical element and the optical path, the allowable amount of optical axis deviation is relaxed to the general mounting accuracy level.

  The advantage of this method is that the optical element is directly mounted on the back surface (electrode formation surface) of the LSI chip, so that the electrical wiring path between the LSI chip and the optical element can be shortened to the limit, and collimated optical coupling is generally used. The optical axis can be aligned with mounting accuracy. However, since the optical wiring is provided in the printed circuit board, it is difficult to manufacture and reduce the cost of the board, the heat dissipation measures for the optical elements are unknown, and the printed circuit board is fragile. The problem is that the optical coupling loss between the two may vary.

  Next, the optical waveguide surface mounting method is a method in which the optical element is fixed to the back surface of the LSI chip, the optical waveguide is mounted on the surface of the printed circuit board, and the optical wiring is provided side by side while maintaining the existing board structure. is there. Further, by adopting a microlens for coupling the optical element and the optical path, the allowable amount of optical axis deviation is relaxed to the general mounting accuracy level.

  The advantage of this method is that the optical element is directly mounted on the back surface (electrode formation surface) of the LSI chip, so that the electrical wiring path between the LSI chip and the optical element can be shortened to the limit, and collimated optical coupling is generally used. The optical axis can be aligned with mounting accuracy. In addition, since the structure is simple, the cost can be reduced and there is an advantage that it can be deployed on an existing board system. However, there are some concerns, such as the fact that the optical element is directly attached to the LSI chip, it is necessary to develop a dedicated LSI, and the optical element may be deteriorated due to the heat of the high-temperature LSI chip.

  As mentioned above, the five specifications of the optical transmission system by the typical chip mounting are shown. However, even when the board wiring system by mounting is simply compared with the electrical transmission, the following problems and problems are as follows for each plan. There is a point.

  For example, in the structure in which the optical path is directly laminated on the board, the base board itself is fragile, so that problems such as optical axis misalignment occur in the embedded waveguide and the like. In the post structure as in the above-mentioned proposal 1, the optical axis is likely to be shifted due to external stress.

  In addition, it is necessary to use materials and parts that take into consideration high-temperature processes after mounting optical elements such as solder reflow and underfill resin sealing, which is a major constraint.

  Moreover, the proposal using the above-mentioned fiber cannot be increased in density, and is limited as a system for inter-device communication. Further, in a structure in which the electrical wiring length between the LSI and the optical element cannot be shortened, the high-frequency signal deteriorates before reaching the optical element, and the effect of light conversion is lost. Therefore, it is necessary to construct a system structure that can shorten this distance.

  For the above reasons, there are still problems and problems in each plan even when the board wiring system by mounting is simply compared with electrical transmission.

  Furthermore, connection wiring is considered in signal propagation between elements formed on the front end by transistors, capacitors, etc. formed on silicon in the LSI chip of LSI wiring, or between blocks of these elements. In this case, in these methods and structures based on the mounting of the optical element chip, the so-called backbone optical transmission physics is merely shrunk, and the circuit chip required as a system architecture such as a codec for output electric signals to be transmitted, MUX / DEMUX, etc. In addition, a drive circuit chip for a light-emitting element, a light-emitting element chip (photoelectric conversion element), a waveguide (optical path), a light-receiving element chip (electro-optical conversion element), an impedance matching circuit, and an IV conversion circuit are physically required, and are monolithic As many chips as there are physical layer elements Can not be reduced.

  Therefore, before the mounting problem compared with the electric transmission as described above, the operation power consumption of each of the physical chips is accumulated as a simple sum, and the alignment error, yield and cost due to the mounting are accumulated. Exists as an inevitable problem.

  As described above, the integration of LSI is approaching its limit. As an alternative method, a proposal for replacing electric transmission with optical transmission has been widely proposed. As one method, SOI (Silicon On Insulator) substrate + laser diode (LD) → waveguide (WG) → photodetector ( A photoelectric composite chip based on PD) is conceivable.

  Currently, a synchronization signal is transmitted by electricity in order to achieve synchronization in the LSI. However, as described above, in the case of electricity, it is becoming difficult to distribute synchronous signals with high quality at the GHz level due to mutual interference of electromagnetic waves, increase in power consumption, RC delay and the like. Therefore, the above problem can be solved by optically transmitting only these clock signals.

  Furthermore, although blocks having various functions are mixed in the LSI, the power supply voltage, the modulation band, etc. are different, and problems such as mutual electromagnetic interference are likely to occur. By making the transmission between these blocks optical, isolation between the blocks is possible, and the reliability of the chip function is improved.

  And, by using this SOI structure wafer, a structure in which the physical layer is partially integrated into one chip so as to achieve a complex function and a reduction in the number of elements has been widely proposed. However, although it is easy to guide light in the horizontal direction, it is difficult to manufacture and design a PC in the vertical direction, that is, a means for propagating a signal to a waveguiding layer or a means for introducing a guided light into a functional element. Only a photonic crystal structure is proposed. An example of a structure that enables a signal to be vertically guided without using a PC structure, and an example of a PC structure are shown.

  First, as shown in FIG. 17, an optical waveguide device 73b having an SOI structure, which allows a signal to be vertically guided without using a PC structure, will be described (see Patent Document 1 described later).

  In the structure of the optical waveguide device 73b, an optical waveguide 85 having a light reflecting portion 81 and a signal receiving portion 84 having an inclination angle of 45 ° at predetermined positions in the waveguide is provided at predetermined positions on the semiconductor substrate 80. An oxide film 79 and a semiconductor layer 78 (semiconductor substrate) are sequentially formed on the optical waveguide 85. The semiconductor layer 78 is provided with a recess 77 at an upper position of the light reflecting portion 81, and further, a MOS transistor or the like. A semiconductor integrated circuit 74 is formed in the vicinity of the surface. Further, an optical fiber 71 a is disposed on the light incident side of the optical waveguide 85 via a wavelength guiding portion (lens) 72, and an optical fiber 71 b is disposed on the light emitting side on the concave portion 77 of the oxide film 78 via the lens 72. Has been placed.

  Next, a part of the incident light 76 converged from the optical fiber 71 a via the wavelength guiding unit 72 and incident from the light incident side of the optical waveguide 85 is incident on the signal receiving unit 84 and then on the signal receiving unit 84. An electric signal 82 can be sent to the provided conductive portion 83. Further, the incident light 76 that has not entered the signal receiving section 84 is reflected by the light reflecting section 81 in the direction perpendicular to the optical waveguide 85 to become reflected light 75, passes through the recess 77 and the lens 72, and enters the optical fiber 71b. Incident.

  Next, an optical waveguide device 73c using a PC structure will be described with reference to FIG.

  First, in the structure shown in FIG. 18A, a line defect waveguide 89 is provided at a predetermined position in a linearly arranged PC structure 90, and further, a point defect is formed at a predetermined position in the structure made of the PC crystal 90. Resonators 88a, 88b, 88c, 88d, 88e, 88f and 88g are provided, respectively.

  When incident light 92 composed of light having a plurality of different wavelengths is incident from the light incident side of the line defect waveguide 89, the wavelength of each of the point defect resonators 88a, 88b, 88c, 88d, 88e, 88f and 88g is changed. Different outgoing light beams 87a, 87b, 87c, 87d, 87e, 87f and 87g are split.

  In the structure shown in FIG. 18B, the inner surface heterostructure having a heterointerface 93 indicated by a broken line is divided into a crystal region 91a and a crystal region 91b, and point defect resonators 88a and 88b are respectively provided in the regions 91a and 91b. A PC structure 90 provided at a predetermined position is configured. A line defect waveguide having a relatively high refractive index is a very small optical waveguide, and each point defect resonator captures light of a specific wavelength by changing its defect area and drops it into free space (or To add). In addition, said PC structure part has a comparatively low refractive index.

  Here, after incident light 92 composed of light having a plurality of different wavelengths enters from the light incident side of the line defect waveguide 89, it reaches the point defect resonators 88a and 88b for each wavelength through the PC structure 90, From here, it radiate | emits as the emitted light 87a and 87b from which a wavelength differs, respectively.

Nikkei Electronics, “Encounter with Optical Wiring”, December 3, 2001, p.122-125, Fig.4-7 Yasuhiro Ando, “Trends in Optical Interconnection Technology and Next-Generation Device Mounting Technology”, NTT R & D, Vol.48, No.3, p.271-280 (1999) WO 2004/010192 A2 (page 7, line 15 to page 8, line 20, FIG. 1)

  Here, in the optical waveguide device 73b having the SOI structure shown in FIG. 17 described above, since the signal receiving unit 84 exists in the optical waveguide 85, most of the incident light 76 is incident on the signal receiving unit 84. Therefore, it is difficult to sufficiently propagate the light to the light reflecting portion 81 located in the subsequent stage in the light propagation direction, and as a result, it may be difficult to send a sufficient amount of light to the optical fiber 71.

  Further, in the optical waveguide device 73c having the PC structure shown in FIG. 18 described above, although vertical waveguide is possible, a desired crystal arrangement is formed, and a line defect and a point defect are formed at a desired position and size. To do so, advanced techniques are required and their formation is difficult.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide an optical waveguide device that can sufficiently propagate light in an optical waveguide, perform optical detection, for example, by optical path conversion, and can be easily manufactured. Is to provide.

  That is, the present invention includes an optical waveguide that guides light from a light incident portion to a light emitting portion, a photoelectric conversion element provided in contact with the outer surface of the optical waveguide, and a light reflecting portion provided in the optical waveguide. And an optical waveguide device in which optical path conversion is performed between the optical waveguide and the photoelectric conversion element by the light reflecting portion.

  According to the optical waveguide device of the present invention, the photoelectric conversion element is provided in contact with the outer surface of the optical waveguide, and the light reflection unit provided in the optical waveguide causes the optical waveguide between the optical waveguide and the photoelectric conversion element. Since the optical path conversion is performed efficiently, the light can be sufficiently propagated in the optical waveguide, and the optical path is converted to improve the light propagation (optical coupling) between the photoelectric conversion element and the optical waveguide. It can be carried out.

  In addition, the optical waveguide device can be easily manufactured using a process established in the past.

  In the present invention, in order to efficiently and easily perform light incident on the optical waveguide and optical waveguide on the light reflecting portion, incident light from the light incident portion arranged to intersect the optical waveguide. However, it is desirable that the optical path is changed by the light reflecting means provided in the optical waveguide and guided to at least the light reflecting portion.

  Further, in order to make the incident light to the photoelectric conversion element, for example, a monitoring photodiode with a sufficient amount of light, the incident light propagating through the optical waveguide passes through the light reflecting portion and the photoelectric conversion element. It is desirable to be incident on the.

  In this case, when the light reflecting portion and / or the light reflecting means are configured by cutting off a part of the optical waveguide and filling the cut portion with a low refractive index material, the reflectance is improved. Can be made.

  Further, when the light reflecting section and / or the light reflecting means are configured as a grating having wavelength selectivity, a specific wavelength component of light propagating in the optical waveguide can be reflected.

  In particular, incident light of multiple wavelengths is selected or separated by the grating, and specific wavelength light can be incident on the photoelectric conversion element via the light reflection unit, and the photoelectric conversion element is wavelength selective (or This is advantageous when there is wavelength sensitivity.

  Moreover, it is good also as a structure where the light source is arrange | positioned at array form corresponding to the said several light-incidence part provided in a row by the said light reflection means to the said common optical waveguide.

  In this case, in order to efficiently guide each outgoing light from the light source array to the light incident part, it is desirable that each outgoing light from the light source array is converged by a light converging means and guided to the light incident part. .

  Preferably, the optical waveguide is sandwiched between first and second semiconductor substrates, and the photoelectric conversion element and the semiconductor integrated circuit element are incorporated in the first semiconductor substrate. Thus, an optical waveguide device can be manufactured using a so-called SOI structure.

For example, the core of the optical waveguide may be composed of an insulating layer between the first and second semiconductor substrates (for example, a SiO ₂ layer between a pair of silicon substrates). Alternatively, the core of the optical waveguide may be formed of an impurity-doped semiconductor layer (for example, a germanium-doped silicon layer) on the first optical semiconductor substrate side.

  Next, a preferred embodiment of the present invention will be described specifically and in detail with reference to the drawings.

First Embodiment FIGS. 1 to 3 show a first embodiment of the present invention.

  First, as shown in FIG. 1A, according to the structure of the optical waveguide device 23a according to the present embodiment that guides light incident from the hole 10 (light incident part), the base substrate having the hole 8 is obtained. On a semiconductor substrate 7 (second semiconductor substrate) made of silicon or the like, a plurality of light reflecting portions having a reflecting surface 5 with a substantially right triangle cross section and 45 °, and a reflecting mirror 9 with a 45 ° isosceles triangle or wedge shape cross section. An oxide film 3 having a light reflecting means having an optical waveguide 21a is formed on the optical waveguide 21a. A plurality of light receiving portions 2 (photoelectric conversion elements such as photodiodes), bipolar transistors 12 and MOS transistors are formed on the optical waveguide 21a. Photoelectric composite element using an SOI substrate in which a semiconductor layer 1 (first semiconductor substrate) such as silicon in which a semiconductor integrated circuit element such as 13 is formed and a hole portion 10 is formed as a light incident portion is bonded. Constitutes a child.

  A plurality of light receiving portions 2 as photo detectors are provided in contact with the optical waveguide 21a on the inner surface of the optical waveguide 21a, and a plurality of light reflecting surfaces 5 are provided at positions facing the light receiving surfaces of the light receiving portions 2, respectively. It has been. The hole 10, the mirror 9, and the hole 8 are coaxially arranged so as to be orthogonal (intersect) with the optical waveguide. By changing the position of the mirror 9, the inside of the optical waveguide 21a is changed to the left and right in the drawing. The distribution of light branched and propagating in the direction can be controlled.

  In the present embodiment, as shown by an arrow in the drawing, incident light 11 incident from a hole 10 formed in a direction perpendicular to the optical waveguide 21a is a light diffusion mirror provided in the optical waveguide 21a. The optical path is converted into two optical paths in the horizontal direction by the mirror 9, and at least one of the optical paths propagates in the direction in which the plurality of light reflecting surfaces 5 exist. In this case, most of the incident light 11 propagating through the optical waveguide 21a continues to propagate through the optical waveguide 21a and is emitted, but a part of the incident light 11 is reflected by 90 ° on the respective light reflecting surfaces 5. Then, the light beams are simultaneously incident on the corresponding light receiving portions 2 in the vertical direction, and the respective light amounts are detected and can be used for monitoring the incident light 11 to the optical waveguide 21a.

FIG. 1B shows another optical waveguide structure. An optical waveguide layer 21a having a high refractive index made of a semiconductor layer 6 such as silicon doped with an impurity (eg, germanium) is an oxide film such as SiO _2. It is joined to the substrate 7 through 3A. The core 6 doped with an impurity (eg, germanium) has a higher refractive index than the substrate 1 and the oxide film 3A as the cladding.

  Next, an example of a manufacturing process of the optical waveguide device 23a will be sequentially described with reference to FIGS.

  First, as shown in FIG. 2 (b), a plurality of photodetectors (PD) to be the light receiving portions 2 are provided on the surface of the silicon substrate 1 shown in FIG. 2 (a) by a conventional method (see FIG. 1 (B)). In the case of an optical waveguide, an impurity-doped semiconductor layer 6 is formed instead of the oxide film material 3a described later, as indicated by a dashed line).

Next, as shown in FIG. 2C, an oxide film material 3 a is formed on the substrate 1 so as to cover the entire surface including the light receiving portion 2. For example, the SiO ₂ film can be formed by chemical vapor deposition (CVD).

  Next, as shown in FIG. 2D, a resist 4 is applied and formed on the oxide film material 3a.

  Next, as shown in FIG. 2E, a recess 5 a for forming the light reflecting surface 5 is formed in the resist 4 at a position corresponding to the light receiving unit 2. The recess 5a is formed by three-dimensional exposure and development.

  Next, as shown in FIG. 2F, by performing dry etching (reactive ion etching: RIE) from the surface, the resist 4 is removed and the recess 5a is held as it is, and the oxide film material 3a is also etched. Then, the recess 5 a is formed in the oxide film material 3 a to form the oxide film 3.

Next, as shown in FIG. 3G, SiO ₂ (low refractive index substance) having a refractive index different from that of the oxide film 3 is applied or deposited on the oxide film 3 to form a light reflecting surface material 5b. To do.

  Next, as shown in FIG. 3H, the light reflecting surface material 5b is polished and planarized from the upper surface side by chemical mechanical polishing (CMP) until the surface of the oxide film 3 is exposed. As a result, the light reflecting surface 5 is formed by embedding the light reflecting material having a low refractive index in the recess 5a.

  Next, as shown in FIG. 3I (upside down in the figure), an SOI structure is formed by bonding a silicon substrate 7 on the exposed surface of the oxide film 3.

  Next, as shown in FIG. 3 (j), the substrate 1 is polished to a predetermined thickness by a chemical mechanical polishing method (CMP) from the side opposite to the signal receiving unit 2.

  Next, as shown in FIG. 3K, semiconductor integrated circuit elements such as the bipolar transistor 12 and the MOS transistor 13 are formed on the substrate 1 according to a conventional method.

  Next, a hole 8 for wet etching is formed through a predetermined portion of the substrate 7 by selective dry etching using a resist as a mask.

Further, by performing isotropic etching of SiO ₂ by dipping into DHF (dilute hydrofluoric acid: for example, concentration 0.5%) through the hole 8, the hole 8 and the hole 8 are formed in the SiO ₂ film 3. The reflection mirror 9 having an isosceles triangle cross section that is continuously provided is formed.

  Next, as shown in FIG. 1A, a hole 10 for introducing light is formed in the vertical direction by selective dry etching using a resist mask through the portion of the substrate 1 corresponding to the mirror 9. Thus, the manufacturing process of the optical waveguide device 23a is completed.

  According to the optical waveguide device 23a according to the present embodiment, the monitoring light receiving section 2 is provided in contact with the outer surface of the optical waveguide 21a, and is received from the optical waveguide 21a by the light reflecting section 5 provided in the optical waveguide 21a. Since the optical path can be changed by reflecting a part of the incident light to the portion 2, it is possible to detect light while efficiently propagating the light in the optical waveguide 21a. Light other than the monitor is emitted from the light exit end of the optical waveguide 21a and can be extracted as signal light.

Further, the optical waveguide device 23a can be manufactured without fundamentally changing the same process as the manufacturing process of the conventional SOI structure, and the light reflecting part 5 and the light reflecting part 5 are added to the optical waveguide 21a made of the SiO ₂ film. In addition, the light reflecting means 9 can be easily manufactured simply by forming the photodetector 2 on the substrate 1.

Second Embodiment FIGS. 4 to 5 show a second embodiment of the present invention.

  In the optical waveguide device 23b according to the present embodiment, as shown in FIG. 4, a plurality of mirrors 9 connected to a hole portion 8 penetrating perpendicularly to the substrate 7 are provided instead of the plurality of light reflecting surfaces 5 described above. This is basically the same as the above-described first embodiment except that it is provided in the oxide film 3 corresponding to the light receiving unit 2.

  In the present embodiment, as indicated by the arrows in the figure, incident light 11 incident in the horizontal direction from the end face of the optical waveguide 21a propagates in the direction in which the plurality of mirrors 9 exist. And most of the incident light 11 propagating in the optical waveguide 21a propagates in the optical waveguide 21a as it is to reach the light exit end, but a part of the incident light 11 passes through the 45 ° reflection surface of each mirror 9. Thus, the light is incident on the corresponding light receiving portions 2 simultaneously in the vertical direction and detected.

  In order to manufacture such an optical waveguide device 23b, as shown in FIG. 5A, a plurality of light receiving portions 2 and an oxide film 3 are formed on the substrate 1 in the same manner as described above. As shown in FIGS. 5B to 5C, the same steps as those in FIGS. 3I to 3J are performed to form an SOI structure.

  Next, as shown in FIG. 5D, similarly to the above, holes 8 are provided in the substrate 7 corresponding to the respective light receiving portions 2, and the oxide film 3 facing the holes 8 is further provided. The mirror 9 is formed inside, and the manufacturing process of the optical waveguide device 23b is completed.

  Also in the present embodiment, similar to the above-described first embodiment, it is possible to obtain an operation and an effect such that light can be efficiently propagated through the optical waveguide 21b and monitoring can be performed.

Third Embodiment FIGS. 6 to 8 show a third embodiment of the present invention.

  In the optical waveguide device 23c according to the present embodiment, as shown in FIG. 6, instead of the above-described mirrors 5 and 9, a desired wavelength of light is emitted by a grating (size or pitch of a concavo-convex shape having a 45 ° reflection surface). Are provided in a plurality of locations in the optical waveguide 21c. Among these multiple gratings, the light incident part is provided with a grating 35 that reflects light to the left and right, and the gratings 15 and the gratings 25 having different concavo-convex shapes that select and reflect different wavelength lights are provided to the plurality of light receiving parts 2. Are basically the same as those of the first embodiment described above except that they are provided corresponding to the above.

  In the present embodiment, only desired signal light among the multiple wavelength incident light (incident signal light) 11 incident in the vertical direction through the hole 10 arranged orthogonal to the optical waveguide 21c is shown in the figure. As indicated by the arrows, the light is separated into two in the horizontal direction by a grating 35 provided in the optical waveguide 21c, and propagates in the optical waveguide 21c in the direction in which the grating 15 and the grating 25 exist.

  Then, most of the multi-wavelength light propagating in the optical waveguide 21c propagates in the optical waveguide 21c as it is and is emitted from the light emitting end, but part of the multi-wavelength light selects different wavelength light. Through the grating 15 and the grating 25, which are reflected on each other, they are simultaneously incident in the vertical direction on the respective light receiving sections 2 corresponding to different wavelength lights and detected.

  In order to manufacture such an optical waveguide device 23c, as shown in FIG. 7A, a plurality of processes are performed on the substrate 1 through the same processes as those shown in FIGS. 2A to 2D. After the light receiving portion 2, the oxide film material 3a, and the resist 4 are formed, as shown in FIGS. Next, a recess 15a, a recess 25a, and a recess 35a are formed on the oxide film 3 by RIE. Thereafter, as shown in FIG. 7D, a grating material 15b is formed on the entire surface including the recess 15a, the recess 25a, and the recess 35a.

  Next, as shown in FIGS. 7 (e) to 8 (g), the substrate 1 is ground and the substrate 7 is bonded through the same steps as in FIGS. 3 (g) to 3 (j) described above. An SOI structure is formed. In this structure, the grating 15, the grating 25, and the grating 35 are formed at predetermined positions in the oxide film 3, respectively.

  Next, as shown in FIG. 8 (h), integrated circuit elements such as the transistors 12 and 13 are formed on the substrate 1, and then, as shown in FIG. Then, the hole 10 is formed, and the manufacturing process of the optical waveguide device 23c is completed.

  According to the present embodiment, after selectively introducing desired multi-wavelength signal light (WDM) from incident light, the multi-wavelength signal light can be freely transmitted by the gratings 15 and 25 corresponding to the respective light receiving units 2. To receive light.

  In addition, in the present embodiment, the same operations and effects as those of the first embodiment described above can be obtained.

Fourth Embodiment FIGS. 9 to 11 show a fourth embodiment of the present invention.

  As shown in FIG. 9, the optical waveguide device 23d according to the present embodiment is basically the same as the third embodiment described above except that the optical waveguide 21d does not include the hole 10 and the grating 35. It is the same.

  In the present embodiment, incident light 11 (multiple wavelength light) that enters the optical waveguide 21d in the horizontal direction from the end thereof propagates in the direction in which the grating 15 and the grating 25 exist, as indicated by arrows in the figure. To do. Most of the multi-wavelength light propagating in the optical waveguide 21d propagates in the optical waveguide 21d as it is to reach the light emitting end, but part of the multi-wavelength light reflects the different wavelength light in the grating 15. Then, the light is incident on the respective light receiving units 2 corresponding to different wavelength lights simultaneously in the vertical direction through the grating 25 and detected.

  In order to manufacture such an optical waveguide device 23d, as shown in FIGS. 10A to 11G, except that the hole 10 and the grating 35 are not provided, the above-described FIGS. The grating 15 and the grating 25 are formed in the oxide film 3 (optical waveguide 21d) through the same manufacturing process as that in FIG.

  Next, semiconductor integrated circuit elements such as the transistors 12 and 13 are formed on the substrate 1, and the manufacturing process of the optical waveguide device 23d is completed.

  In the present embodiment, the same operations and effects as those in the first and third embodiments described above can be obtained.

Fifth Embodiment FIGS. 12 to 14 show a fifth embodiment of the present invention.

  In the optical waveguide device 23e according to the present embodiment, as shown in FIG. 12, the hole 10, the hole 8, and the mirror 9 are formed at predetermined positions of the light incident portion, as in the first embodiment described above. This is basically the same as the third embodiment except that the optical waveguide 21e is provided.

  In the present embodiment, multiple-wavelength incident light 11 incident in the vertical direction through the hole 10 formed orthogonal to the optical waveguide 21e is incident on the optical waveguide 21c as indicated by arrows in the figure. Desired multi-wavelength light (incident light) that has been optically path-converted into two optical paths by the provided mirror 9 propagates in the optical waveguide 21c in the direction in which the grating 15 and the grating 25 exist. And most of the multi-wavelength light propagating in the optical waveguide 21e propagates in the optical waveguide 21e as it is and reaches the light emitting end, but part of the multi-wavelength light selectively selects light of different wavelengths. Through the reflecting grating 15 and the grating 25, the light is incident on the respective light receiving sections 2 corresponding to different wavelength lights simultaneously in the vertical direction and detected.

  As for the manufacturing process of such an optical waveguide device 23e, as shown in FIGS. 13A to 14G, the grating is processed through the same processes as those in FIGS. 10A to 11G described above. 15 and an SOI structure having an oxide film 3 having a grating 25 and a plurality of light receiving portions 2 are formed. Next, as shown in FIGS. 14H to 14I, the transistors 12 and 13, the hole 8 and the mirror 9 are formed in the same manner as in FIG. 3K described above. Next, the hole 10 is formed in the substrate 1, and the manufacturing process of the optical waveguide device 23e is completed.

  In the present embodiment, the same operations and effects as those in the first and third embodiments described above can be obtained.

Sixth Embodiment FIG. 15 shows a sixth embodiment of the present invention.

  In the optical waveguide device 23f according to the present embodiment, as shown in FIG. 15A, an insulating layer 19 provided with a wiring layer composed of conductive plugs 16 and 17 connected to an integrated circuit element is provided on the substrate 1. The substrate 22 having the vertical cavity surface emitting lasers (VCSEL) 18 arranged in an array is disposed on the insulating layer 19 so that the hole 10 and the grating 35 correspond to the lasers 18 in the light incident part. The third embodiment is basically the same as the third embodiment except that it is formed in the optical waveguide 21f.

  In the present embodiment, multi-wavelength incident light (incident signal light) 11 incident in the vertical direction from each laser light source 18 through a plurality of holes 10 formed orthogonal to the optical waveguide 21f is shown in the figure. As shown by the arrows in FIG. 4, each grating 35 provided in the optical waveguide 21f separates the light in two in the horizontal direction so that the desired multi-wavelength light has an isosceles triangle cross section having a 45 ° reflecting surface. It propagates in the direction in which the part 5 exists. A part of the multi-wavelength light is simultaneously detected in the vertical direction on each light receiving unit 2 via each light reflection surface 5 and detected. In this case, a plurality of or a plurality of types of wavelength light may enter each light receiving unit 2, and a plurality of or a plurality of types of signal light may be emitted from the optical waveguide 21f.

  Here, since the incident light 11 from the VCSEL 18 (or an optical fiber or the like) enters the hole 10 with a certain extent, in order to introduce it into the substrate 1 with high efficiency, plugs 16 and 17 are used. It is desirable to enlarge the hole 10 without providing any interference in the introduction part on the provided insulating layer 19.

  However, as shown in FIG. 15B, the microlenses 20 (light focusing means) are fixed to the transparent substrate 40 in the form of an array on the insulating layer 19 or directly provided on the insulating layer 19 (not shown). Therefore, the light beam of the incident light 11 from the light source can be introduced with a reduced diameter (convergence). Thereby, even if the hole 10 is reduced, sufficient light incidence can be performed, so that the wirings 16 and 17 and circuit elements provided in the insulating layer 19 can be highly integrated.

  In addition, in the present embodiment, the same operations and effects as those in the first and third embodiments described above can be obtained.

  As mentioned above, although this invention was demonstrated based on embodiment, it cannot be overemphasized that this invention is not limited to these examples at all, and can be suitably changed in the range which does not deviate from the main point of invention.

  For example, an antireflection (AR) coating (antireflection film) may be applied to the light receiving surface side of the light receiving unit 2 to reduce the loss, or a nonreflective coating or a metal light shielding film may be formed in addition to the light incident unit. .

  Further, the light source may be provided in the optical waveguide, or the reflection surface such as the mirror 9 may be metal-coated to improve the reflection efficiency. The mirror 9 and the like may be formed by machining or the like other than etching.

  Further, instead of the grating 35, a diffuser lens or a photonic crystal may be used.

  In addition, the arrangement and type of the light receiving section 2 described above, the light reflecting section 5, the gratings 15, 25 and 35, the mirror 9, the hole 10 and the like, the material, shape, forming positions, number, forming method, and the like are variously changed. be able to.

  Note that a light emitting element may be provided at the same position instead of the light receiving unit 2 described above, and the light path of the emitted light may be converted by the light reflecting unit to be guided in the optical waveguide. Also, a similar optical waveguide device can be manufactured without using the SOI structure as described above.

  The optical waveguide device of the present invention can be applied to various places such as between electronic devices, between boards in an electronic device, particularly between semiconductor chips in a board, and is suitable as an optical wiring system, for example, at high speed, high density, This can contribute to the construction of a low-cost optical transmission / optical communication system. In addition to this, the present invention can also be applied to a display or the like by selecting a light source or the like.

FIG. 4 is a cross-sectional view (A) of the optical waveguide device according to the first embodiment of the present invention and a partial cross-sectional view (B) of another optical waveguide. FIG. 6 is a cross-sectional view sequentially showing the manufacturing steps of the optical waveguide device. FIG. 6 is a cross-sectional view sequentially showing the manufacturing steps of the optical waveguide device. It is sectional drawing of the optical waveguide device by the 2nd Embodiment of this invention. FIG. 6 is a cross-sectional view sequentially showing the manufacturing steps of the optical waveguide device. It is sectional drawing of the optical waveguide device by the 3rd Embodiment of this invention. FIG. 6 is a cross-sectional view sequentially showing the manufacturing steps of the optical waveguide device. FIG. 6 is a cross-sectional view sequentially showing the manufacturing steps of the optical waveguide device. It is sectional drawing of the optical waveguide device by the 4th Embodiment of this invention. FIG. 6 is a cross-sectional view sequentially showing the manufacturing steps of the optical waveguide device. FIG. 6 is a cross-sectional view sequentially showing the manufacturing steps of the optical waveguide device. It is sectional drawing of the optical waveguide device by the 5th Embodiment of this invention. FIG. 6 is a cross-sectional view sequentially showing the manufacturing steps of the optical waveguide device. FIG. 6 is a cross-sectional view sequentially showing the manufacturing steps of the optical waveguide device. It is sectional drawing (A) and (B) of the optical waveguide device by the 6th Embodiment of this invention. It is sectional drawing of the optical waveguide device by a prior art example. It is sectional drawing of another optical waveguide device same as the above. It is sectional drawing of the same another optical waveguide apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 7 ... Semiconductor substrate or semiconductor layer, 2 ... Light-receiving part, 3, 3A ... Oxide film, 3a ... Oxide film material,
4 ... resist, 5 ... light reflecting surface, 5a, 15a ... concave, 5b ... reflecting surface material,
6 ... impurity doped layer, 8, 10 ... hole, 9 ... mirror, 11 ... incident light,
12 ... bipolar transistor, 13 ... MOS transistor,
15, 25, 35 ... grating, 15b ... grating material, 16, 17 ... plug,
18 ... VCSEL (light source), 19 ... insulating layer, 20 ... microlens (array),
21a, 21b, 21c, 21d, 21e, 21f ... optical waveguide,
23a, 23b, 23c, 23d, 23e, 23f ... optical waveguide device, 25a ... concave portion

Claims (12)

  An optical waveguide for guiding light from the light incident portion to the light emitting portion; a photoelectric conversion element provided in contact with an outer surface of the optical waveguide; and a light reflecting portion provided in the optical waveguide; An optical waveguide device in which optical path conversion is performed between the optical waveguide and the photoelectric conversion element by a unit.   The incident light from the light incident portion arranged so as to intersect the optical waveguide is subjected to optical path conversion by a light reflecting means provided in the optical waveguide, and is guided to at least the light reflecting portion. The optical waveguide device described.   The optical waveguide device according to claim 1, wherein the incident light propagating through the optical waveguide is incident on the photoelectric conversion element via the light reflecting portion.   The optical waveguide device according to claim 3, wherein incident light from the light reflecting portion to the photoelectric conversion element is used for monitoring incident light to the optical waveguide.   4. The optical waveguide device according to claim 3, wherein a part of the optical waveguide is excised, and the excision is filled with a low refractive index material, whereby the optical reflector and / or the optical reflector is configured. .   The optical waveguide device according to claim 3, wherein the light reflecting portion and / or the light reflecting means are configured as a wavelength selective grating.   The optical waveguide device according to claim 6, wherein multiple-wavelength incident signal light is selected or separated by the grating and is incident on the photoelectric conversion element via the light reflecting portion.   2. The optical waveguide device according to claim 1, wherein light sources are arranged in an array corresponding to the plurality of light incident portions connected to the common optical waveguide via the light reflecting means.   9. The optical waveguide device according to claim 8, wherein each light emitted from the light source array is converged by light converging means and guided to the light incident portion.   The optical waveguide device according to claim 1, wherein the optical waveguide is sandwiched between first and second semiconductor substrates, and the photoelectric conversion element and the semiconductor integrated circuit element are incorporated in the first semiconductor substrate.   The optical waveguide device according to claim 10, wherein a core of the optical waveguide is formed of an insulating layer between the first and second semiconductor substrates. The optical waveguide device according to claim 10, wherein a core of the optical waveguide is formed by an impurity-doped semiconductor layer on the first semiconductor substrate side.

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