WO2009009766A2 - Flip-chip photodiode - Google Patents

Flip-chip photodiode Download PDF

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Publication number
WO2009009766A2
WO2009009766A2 PCT/US2008/069875 US2008069875W WO2009009766A2 WO 2009009766 A2 WO2009009766 A2 WO 2009009766A2 US 2008069875 W US2008069875 W US 2008069875W WO 2009009766 A2 WO2009009766 A2 WO 2009009766A2
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WO
WIPO (PCT)
Prior art keywords
substrate
flip
photodiode according
chip
photodiode
Prior art date
Application number
PCT/US2008/069875
Other languages
French (fr)
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WO2009009766A3 (en
Inventor
Tony Maryfield
Mahyar Dadkhah
Thomas Davidson
Original Assignee
Cubic Corporation
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Publication date
Application filed by Cubic Corporation filed Critical Cubic Corporation
Publication of WO2009009766A2 publication Critical patent/WO2009009766A2/en
Publication of WO2009009766A3 publication Critical patent/WO2009009766A3/en

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Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/0102—Constructional details, not otherwise provided for in this subclass
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y20/00—Nanooptics, e.g. quantum optics or photonic crystals
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
    • G01S17/74—Systems using reradiation of electromagnetic waves other than radio waves, e.g. IFF, i.e. identification of friend or foe
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/08—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof in which radiation controls flow of current through the device, e.g. photoresistors
    • H01L31/10—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof in which radiation controls flow of current through the device, e.g. photoresistors characterised by at least one potential-jump barrier or surface barrier, e.g. phototransistors
    • H01L31/101—Devices sensitive to infrared, visible or ultraviolet radiation
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/015—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on semiconductor elements with at least one potential jump barrier, e.g. PN, PIN junction
    • G02F1/017—Structures with periodic or quasi periodic potential variation, e.g. superlattices, quantum wells
    • G02F1/01716—Optically controlled superlattice or quantum well devices
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/10—Bump connectors; Manufacturing methods related thereto
    • H01L2224/15—Structure, shape, material or disposition of the bump connectors after the connecting process
    • H01L2224/16—Structure, shape, material or disposition of the bump connectors after the connecting process of an individual bump connector
    • H01L2224/161—Disposition
    • H01L2224/16151—Disposition the bump connector connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive
    • H01L2224/16221—Disposition the bump connector connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked
    • H01L2224/16225—Disposition the bump connector connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked the item being non-metallic, e.g. insulating substrate with or without metallisation
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/42—Wire connectors; Manufacturing methods related thereto
    • H01L2224/47—Structure, shape, material or disposition of the wire connectors after the connecting process
    • H01L2224/48—Structure, shape, material or disposition of the wire connectors after the connecting process of an individual wire connector
    • H01L2224/4805—Shape
    • H01L2224/4809—Loop shape
    • H01L2224/48091—Arched
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/73—Means for bonding being of different types provided for in two or more of groups H01L2224/10, H01L2224/18, H01L2224/26, H01L2224/34, H01L2224/42, H01L2224/50, H01L2224/63, H01L2224/71
    • H01L2224/732—Location after the connecting process
    • H01L2224/73251—Location after the connecting process on different surfaces
    • H01L2224/73253—Bump and layer connectors
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
    • H01L2924/10—Details of semiconductor or other solid state devices to be connected
    • H01L2924/11—Device type
    • H01L2924/12—Passive devices, e.g. 2 terminal devices
    • H01L2924/1203—Rectifying Diode
    • H01L2924/12032—Schottky diode
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/12—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof structurally associated with, e.g. formed in or on a common substrate with, one or more electric light sources, e.g. electroluminescent light sources, and electrically or optically coupled thereto

Definitions

  • Photodiodes are constructed with an active layer placed upon a substrate that may then be coupled, for example, with a printed circuit board.
  • an optical filter may also be included to block unwanted bands of light. The inclusion of the filter often adds weight and complexity, increases costs, and decreases the photodiode field of view.
  • the flip-chip photodiode may include an active layer, a substrate, and a plurality of solder balls.
  • the active layer comprises a top and a bottom surface such that the top surface of the active layer is coupled with the substrate.
  • the active layer is coupled with the substrate with an intervening layer, for example, an intrinsic layer, or a gap.
  • the plurality of solder balls may be coupled with the bottom of the active layer and may be configured to couple with a circuit board.
  • a plurality of solder balls may be coupled with the bottom of the substrate and configured to couple with a circuit board.
  • the substrate may include an antireflective coating on the top surface thereof.
  • a flip-chip photo diode stack is provided according to another embodiment, that includes a substrate, an active area and a printed circuit board.
  • the substrate includes a top surface and a bottom surface. The top surface may be configured to receive light.
  • the active layer includes a top surface and a bottom surface. The top surface of the active area may be coupled with the bottom surface of the substrate.
  • the printed circuit board includes at least a top surface coupled with the active layer. Solder balls, according to another embodiment, may be used to couple the active array to the printed circuit board.
  • An intrinsic layer may, in some embodiments, be included between the active layer and the substrate.
  • a photodiode includes a substrate and an active region.
  • the substrate includes a top surface and a bottom surface.
  • the active region comprises a top surface and a bottom surface.
  • the top surface of the active region may be aligned below the bottom surface of the substrate.
  • the photodiode may be configured to receive light through the top surface of the substrate. At least a portion of the light received through the top surface of the substrate may be incident on the active region.
  • the substrate may be substantially transparent to light with wavelengths between about 1530 nm and about 1560 nm. In another embodiment, the substrate maybe substantially transparent to infrared light.
  • FIG. IA shows a prior art photodiode.
  • FIG. IB shows a flip-chip photodiode according to one embodiment.
  • FIGS. 2A-2C show various flip-chip photodiode configurations according to some embodiments.
  • FIG. 3 shows a communication system that may implement a photodiode according to some embodiments.
  • FIG. 4 shows light incident off the active layer of a photodiode according to one embodiment.
  • FIG. 5 shows a top view of a photodiode array according to one embodiment.
  • FIG. 6 shows a bottom view of a photodiode according to one embodiment.
  • FIGS. 7A and 7B show a flip-chip photodiode used in conjunction with an optical communication device according to one embodiment.
  • a flip-chip photodiode may use the substrate as a light filter.
  • a flip-chip diode may include an active layer and a substrate. The active layer may be coupled with the substrate. The coupling of the active layer with the substrate may include direct coupling, indirect coupling, coupling with a gap between, and/or coupling with an intrinsic layer between the two.
  • the photodiode may be constructed from a plurality of semiconductor materials. In other embodiments, the photodiode may be a surface mount device.
  • a photodiode is shown according to the prior art.
  • a substrate 110 includes an active area 105 deposited thereon.
  • the substrate 110 is coupled with the circuit board 115 using, for example, solder balls and/or die attach epoxy 120.
  • the active layer 105 is coupled with the circuit board 115 using wire bonds 125.
  • the active layer 105 is exposed to the incoming light and a filter may be required to cut back on unwanted light sources.
  • FIG. IB shows a photodiode according to one embodiment.
  • the photodiode is flipped. That is, the substrate 110 is above the active layer 105. In such an embodiment, only light that transmits through the substrate 110 is incident on the active area 105.
  • the substrate 110 acts not only as a substrate, but also as a light filter. Accordingly, the substrate 110 may be selected based on the wavelength of light that one is interested in filtering.
  • the substrate may comprise indium phosphide (InP) which permits transmission of wavelengths of the desired wavelength, for example of about 1550 nm, and may block other wavelengths. In some embodiments, the desired wavelength may be between about nm.
  • the substrate 110 may act as a long-pass filter to daylight and may block short wave infrared radiation. In other embodiments, the substrate 110 filters sun light.
  • the active area 105 may be coupled with solder balls 120 or other connectors used to couple the active area to a circuit board, such as, for example, conductive epoxy bumps.
  • the active area 105 may include various surface-mount interconnects. These interconnects may include, for example, J-leads, solder balls, pins, fine pitch balls, leads, epoxy bumps, stencil printed polymer bumps, conductive adhesives, stud bumps, etc.
  • the photodiode may be used as a surface-mount device with any type of grid array and/or packaging.
  • solder balls 120 may electrically connect the active area 105 with the printed circuit board 115.
  • the substrate in this embodiment, may use wire bonds to connect the substrate 110 with the circuit board 115.
  • the substrate 110 may include any semiconductor material.
  • the substrate may comprise indium phosphide, silicon, silicon germanium, and/or indium gallium arsenide.
  • the active area 105 may include silicon, gallium, indium gallium arsenide, gallium phosphide, silicon carbide, titanium dioxide, germanium, gallium nitride, aluminum gallium nitride, and/or lead sulfide.
  • the active area 105 comprise a p-type semiconductor material and the substrate 110 comprises an n-type semiconductor material.
  • the photodiode may comprise any type of photodiode.
  • the photodiode may include a PN photodiode, a PNN photodiode, a PIN photodiode, a Schottky type photodiode, and/or an avalanche type photodiode.
  • Various embodiments use the substrate as a sunlight filter. Such a filter may eliminate the need for added filter components, which may reduce the photodiode stack height and dimension. Moreover, using the substrate as a sunlight filter reduces the complexity and cost of the photodiode.
  • the sunlight filter also reduces photocurrent within the photodiode according to some embodiments. In other embodiments, the sunlight filter may also reduce power consumption from the photocurrent when the photodiode is reverse biased.
  • FIGS. 2 A and 2B show other flip-chip photodiodes with a window 150 according to some embodiments.
  • the window 150 may provide protection from the elements and/or provide some filtering.
  • the substrate includes solder balls 130 in a surface mount package.
  • FIG. 2B shows a PIN type photodiode with an intrinsic layer 135 between the substrate 110 and the active area 105.
  • FIG. 2C shows a photodiode with an active area 105 that were constructed using a mesa etch technique according to some embodiments.
  • the edges of the active area 105 may be are protected with a non-conductive layer, such as a passivation layer.
  • a passivation layer may include benzocyclobutene.
  • both the N-semiconductor layer and P- semiconductor layer of the photodiode are interconnected with the printed circuit board, for example using epoxy bumps and/or solder.
  • FIG. 3 shows an optical communication system employing a photodiode according to one embodiment.
  • transceiver 310 transmits an information bearing optical signal toward an optical tag 320.
  • An optical receiver 330 may be disposed within the optical tag 320 and receives the signal.
  • the optical receiver 330 may include a flip-chip photodiode and may be used to synchronize and phase lock the receiver to an incoming pulsed light source.
  • the incoming light may also coupled to an optical modulator 340 and retro-reflector 350 that modifies the return beam energy with data from the tag. This amplitude modulation may be intercepted by the Interrogating transceiver and decodes the amplitude changes back into serial data bits.
  • the inventive photodiode may be included in the optical tag 320 as part of optical receiver 330.
  • the photodiode detects the information bearing signal and may be exposed to significant solar radiation.
  • An optical tag employing a flip-chip photodiodes may provide a large field of view (e.g., 120 degrees).
  • photodiodes may be inexpensive to construct and have a small size, a low weight, and modest power requirements.
  • photodiodes may undergo solar loading. Under the influence of solar loading, conventional photodiodes generate significant sun current, which can increase "shot noise" in the optical receiver, which reduces the signal to noise ratio and the effective optical range.
  • Optical receivers including a flip-chip photodiode may exhibit significantly reduced solar current, higher signal-to-noise ratios, and improved optical range improvements.
  • flip-chip photodiodes can eliminate the need for an additional narrowband filter attachment. Narrow-band filters used with conventional photodiodes often limit the field of view, whereas flip-chip photodiodes may avoid such limitations through use of the filtering substrate.
  • FIG. 4 shows a flip-chip photodiode 400 shown with light rays according to one embodiment.
  • a flip-chip diode may have about a ⁇ 60° field of view.
  • the field of view for example, may be about ⁇ 50°, ⁇ 51°, ⁇ 52°, ⁇ 53°, ⁇ 54°, ⁇ 55°, ⁇ 56°, ⁇ 57°, ⁇ 58°, ⁇ 59°, ⁇ 50°, ⁇ 61°, ⁇ 62°, ⁇ 63°, ⁇ 64°, ⁇ 65°, ⁇ 66°, ⁇ 67°, ⁇ 68°, ⁇ 69° or ⁇ 70°.
  • the field of view may be less than about ⁇ 50°.
  • an indium gallium arsenide detector may be used with a silicon filter.
  • the active area for example, may include indium phosphide.
  • FIG. 5 shows a top view of a flip-chip photodiode wafer 500 according to one embodiment.
  • the photodiode wafer 500 may include a plurality of photodiodes 520 as shown. Any number of photodiodes may be used within an array. In this embodiment, two quality control test sites 510 are included.
  • FIG. 6 shows a bottom view of a surface mount package flip-chip photodiode 600 according to one embodiment.
  • the active area 640 is shown surrounded by the substrate 620.
  • Solder balls 630 are coupled with the active area 640 and solder balls 610 are coupled with the substrate 620.
  • FIG. 7B shows an exploded view of an optical communication device that includes a flip-chip photodiode 735 according to one embodiment.
  • a housing 730 contains a retro- reflector 725, a modulating quantum well modulator 720, a window 715 and a photodiode 735.
  • the quantum well modulator 720 may modify or add information to the signal after reflection through the retro-reflector 725.
  • FIG. 7A shows an unexploded packaged view of the optical communication device.

Abstract

A flip-chip photodiode is provided according to various embodiments. The photodiode includes a substrate and an active region. The active region is configured to receive light through the substrate. In such a configuration, the substrate not only participates in the photodiode operation. lt also acts as a light filter depending on the substrate material. In some embodiments, the active region may include solder balls that may be used to couple the photodiode to a printed circuit board. In some embodiments, the active region is coupled face-to-face with the printed circuit board.

Description

FLIP-CHIP PHOTODIODE
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] This application is a non-provisional, and claims the benefit, of commonly assigned U.S. Provisional Patent Application No. 60/949,200, filed July 11, 2007, entitled "Flip Chip Photo-Diode," the entirety of which is herein incorporated by reference for all purposes.
[0002] This application is a non-provisional, and claims the benefit, of commonly assigned U.S. Provisional Patent Application No. 60/949,229, filed July 11, 2007, entitled "Flip Chip Quantum Well Modulator," the entirety of which is herein incorporated by reference for all purposes.
[0003] This application is a non-provisional, and claims the benefit, of commonly assigned U.S. Provisional Patent Application No. 60/949,230, filed July 11, 2007, entitled "Integrated Modulating Retro-Reflector," the entirety of which is herein incorporated by reference for all purposes.
STATEMENTAS TO RIGHTS TO INVENTIONS MADE UNDER FEDERALLY SPONSORED RESEARCH ORDEVELOPMENT
[0004] The U.S. Government may have rights in this invention pursuant to Special Operations Command under Contract No. H92222-04-C-0004.
BACKGROUND
[0005] This disclosure relates in general to photodiodes. Photodiodes are constructed with an active layer placed upon a substrate that may then be coupled, for example, with a printed circuit board. In some applications, an optical filter may also be included to block unwanted bands of light. The inclusion of the filter often adds weight and complexity, increases costs, and decreases the photodiode field of view.
BRIEF SUMMARY
[0006] A flip-chip photo diode is provided according to various embodiments. The flip- chip photodiode may include an active layer, a substrate, and a plurality of solder balls. The active layer comprises a top and a bottom surface such that the top surface of the active layer is coupled with the substrate. In some embodiments, the active layer is coupled with the substrate with an intervening layer, for example, an intrinsic layer, or a gap. The plurality of solder balls may be coupled with the bottom of the active layer and may be configured to couple with a circuit board. In other embodiments a plurality of solder balls may be coupled with the bottom of the substrate and configured to couple with a circuit board. The substrate may include an antireflective coating on the top surface thereof.
[0007] A flip-chip photo diode stack is provided according to another embodiment, that includes a substrate, an active area and a printed circuit board. The substrate includes a top surface and a bottom surface. The top surface may be configured to receive light. The active layer includes a top surface and a bottom surface. The top surface of the active area may be coupled with the bottom surface of the substrate. The printed circuit board includes at least a top surface coupled with the active layer. Solder balls, according to another embodiment, may be used to couple the active array to the printed circuit board. An intrinsic layer may, in some embodiments, be included between the active layer and the substrate.
[0008] A photodiode is provided according to some embodiments that includes a substrate and an active region. The substrate includes a top surface and a bottom surface. The active region comprises a top surface and a bottom surface. The top surface of the active region may be aligned below the bottom surface of the substrate. The photodiode may be configured to receive light through the top surface of the substrate. At least a portion of the light received through the top surface of the substrate may be incident on the active region. In one embodiment, the substrate may be substantially transparent to light with wavelengths between about 1530 nm and about 1560 nm. In another embodiment, the substrate maybe substantially transparent to infrared light.
[0009] Further areas of applicability of the present disclosure will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating various embodiments, are intended for purposes of illustration only and do not limit the scope of the disclosure.
BRIEF DESCRIPTION OF THE DRAWINGS [0010] FIG. IA shows a prior art photodiode. [0011] FIG. IB shows a flip-chip photodiode according to one embodiment. [0012] FIGS. 2A-2C show various flip-chip photodiode configurations according to some embodiments.
[0013] FIG. 3 shows a communication system that may implement a photodiode according to some embodiments.
[0014] FIG. 4 shows light incident off the active layer of a photodiode according to one embodiment.
[0015] FIG. 5 shows a top view of a photodiode array according to one embodiment. [0016] FIG. 6 shows a bottom view of a photodiode according to one embodiment.
[0017] FIGS. 7A and 7B show a flip-chip photodiode used in conjunction with an optical communication device according to one embodiment.
[0018] In the appended figures, similar components and/or features may have the same reference label. Where the reference label is used in the specification, the description is applicable to any one of the similar components having the same reference label.
DETAILED DESCRIPTION
[0019] The ensuing description provides preferred exemplary embodiment(s) only, and is not intended to limit the scope, applicability or configuration of the disclosure. Rather, the ensuing description of the preferred exemplary embodiment(s) will provide those skilled in the art with an enabling description for implementing a preferred exemplary embodiment. It should be understood that various changes may be made in the function and arrangement of elements without departing from the spirit and scope as set forth in the appended claims.
[0020] In one embodiment, the present disclosure provides for a flip-chip photodiode. In some embodiments, a flip-chip photodiode may use the substrate as a light filter. In other embodiments, a flip-chip diode may include an active layer and a substrate. The active layer may be coupled with the substrate. The coupling of the active layer with the substrate may include direct coupling, indirect coupling, coupling with a gap between, and/or coupling with an intrinsic layer between the two. In embodiments described herein, the photodiode may be constructed from a plurality of semiconductor materials. In other embodiments, the photodiode may be a surface mount device. [0021] Referring first to FIG. IA, a photodiode is shown according to the prior art. As shown, a substrate 110 includes an active area 105 deposited thereon. The substrate 110 is coupled with the circuit board 115 using, for example, solder balls and/or die attach epoxy 120. The active layer 105 is coupled with the circuit board 115 using wire bonds 125. As shown, the active layer 105 is exposed to the incoming light and a filter may be required to cut back on unwanted light sources.
[0022] FIG. IB shows a photodiode according to one embodiment. In this embodiment, the photodiode is flipped. That is, the substrate 110 is above the active layer 105. In such an embodiment, only light that transmits through the substrate 110 is incident on the active area 105. Thus, the substrate 110 acts not only as a substrate, but also as a light filter. Accordingly, the substrate 110 may be selected based on the wavelength of light that one is interested in filtering. For example, the substrate may comprise indium phosphide (InP) which permits transmission of wavelengths of the desired wavelength, for example of about 1550 nm, and may block other wavelengths. In some embodiments, the desired wavelength may be between about nm. In some embodiments, the substrate 110 may act as a long-pass filter to daylight and may block short wave infrared radiation. In other embodiments, the substrate 110 filters sun light.
[0023] The active area 105 may be coupled with solder balls 120 or other connectors used to couple the active area to a circuit board, such as, for example, conductive epoxy bumps. In some embodiments, the active area 105 may include various surface-mount interconnects. These interconnects may include, for example, J-leads, solder balls, pins, fine pitch balls, leads, epoxy bumps, stencil printed polymer bumps, conductive adhesives, stud bumps, etc. Accordingly, the photodiode may be used as a surface-mount device with any type of grid array and/or packaging. In the embodiment shown in FIG. IB, solder balls 120 may electrically connect the active area 105 with the printed circuit board 115. The substrate, in this embodiment, may use wire bonds to connect the substrate 110 with the circuit board 115.
[0024] The substrate 110 may include any semiconductor material. For example, the substrate may comprise indium phosphide, silicon, silicon germanium, and/or indium gallium arsenide. As another example, the active area 105 may include silicon, gallium, indium gallium arsenide, gallium phosphide, silicon carbide, titanium dioxide, germanium, gallium nitride, aluminum gallium nitride, and/or lead sulfide. In some embodiments, the active area 105 comprise a p-type semiconductor material and the substrate 110 comprises an n-type semiconductor material.
[0025] The photodiode may comprise any type of photodiode. For example, the photodiode may include a PN photodiode, a PNN photodiode, a PIN photodiode, a Schottky type photodiode, and/or an avalanche type photodiode.
[0026] Various embodiments use the substrate as a sunlight filter. Such a filter may eliminate the need for added filter components, which may reduce the photodiode stack height and dimension. Moreover, using the substrate as a sunlight filter reduces the complexity and cost of the photodiode. The sunlight filter also reduces photocurrent within the photodiode according to some embodiments. In other embodiments, the sunlight filter may also reduce power consumption from the photocurrent when the photodiode is reverse biased.
[0027] FIGS. 2 A and 2B show other flip-chip photodiodes with a window 150 according to some embodiments. The window 150 may provide protection from the elements and/or provide some filtering. Moreover, in FIG. 2A the substrate includes solder balls 130 in a surface mount package. FIG. 2B shows a PIN type photodiode with an intrinsic layer 135 between the substrate 110 and the active area 105. FIG. 2C shows a photodiode with an active area 105 that were constructed using a mesa etch technique according to some embodiments. The edges of the active area 105 may be are protected with a non-conductive layer, such as a passivation layer. In some embodiments, a passivation layer may include benzocyclobutene. In various embodiments, both the N-semiconductor layer and P- semiconductor layer of the photodiode are interconnected with the printed circuit board, for example using epoxy bumps and/or solder.
[0028] FIG. 3 shows an optical communication system employing a photodiode according to one embodiment. As shown, transceiver 310 transmits an information bearing optical signal toward an optical tag 320. An optical receiver 330 may be disposed within the optical tag 320 and receives the signal. The optical receiver 330 may include a flip-chip photodiode and may be used to synchronize and phase lock the receiver to an incoming pulsed light source. The incoming light may also coupled to an optical modulator 340 and retro-reflector 350 that modifies the return beam energy with data from the tag. This amplitude modulation may be intercepted by the Interrogating transceiver and decodes the amplitude changes back into serial data bits. In this manner, transceiver 310 and optical tag 320 communicate. [0029] In various embodiments, the inventive photodiode may be included in the optical tag 320 as part of optical receiver 330. As such, the photodiode detects the information bearing signal and may be exposed to significant solar radiation. An optical tag employing a flip-chip photodiodes, for example, may provide a large field of view (e.g., 120 degrees). Moreover, such photodiodes may be inexpensive to construct and have a small size, a low weight, and modest power requirements.
[0030] In operation in a solar environment, photodiodes may undergo solar loading. Under the influence of solar loading, conventional photodiodes generate significant sun current, which can increase "shot noise" in the optical receiver, which reduces the signal to noise ratio and the effective optical range. Optical receivers including a flip-chip photodiode, in some embodiments, may exhibit significantly reduced solar current, higher signal-to-noise ratios, and improved optical range improvements. In addition, unlike conventional photodiodes, in some embodiments, flip-chip photodiodes can eliminate the need for an additional narrowband filter attachment. Narrow-band filters used with conventional photodiodes often limit the field of view, whereas flip-chip photodiodes may avoid such limitations through use of the filtering substrate.
[0031] FIG. 4 shows a flip-chip photodiode 400 shown with light rays according to one embodiment. As shown, a flip-chip diode according to embodiments described herein, may have about a ±60° field of view. In other embodiments, the field of view, for example, may be about ±50°, ±51°, ±52°, ±53°, ±54°, ±55°, ±56°, ±57°, ±58°, ±59°, ±50°, ±61°, ±62°, ±63°, ±64°, ±65°, ±66°, ±67°, ±68°, ±69° or ±70°. In other embodiments, the field of view may be less than about ±50°. As shown in the expanded view portion, an indium gallium arsenide detector may be used with a silicon filter. The active area, for example, may include indium phosphide.
[0032] FIG. 5 shows a top view of a flip-chip photodiode wafer 500 according to one embodiment. The photodiode wafer 500 may include a plurality of photodiodes 520 as shown. Any number of photodiodes may be used within an array. In this embodiment, two quality control test sites 510 are included.
[0033] FIG. 6 shows a bottom view of a surface mount package flip-chip photodiode 600 according to one embodiment. The active area 640 is shown surrounded by the substrate 620. Solder balls 630 are coupled with the active area 640 and solder balls 610 are coupled with the substrate 620. [0034] FIG. 7B shows an exploded view of an optical communication device that includes a flip-chip photodiode 735 according to one embodiment. A housing 730 contains a retro- reflector 725, a modulating quantum well modulator 720, a window 715 and a photodiode 735. The quantum well modulator 720 may modify or add information to the signal after reflection through the retro-reflector 725. FIG. 7A shows an unexploded packaged view of the optical communication device.
[0035] Specific details are given in the above description to provide a thorough understanding of the embodiments. However, it is understood that the embodiments may be practiced without these specific details. For example, circuits, structures, and/or components may be shown in block diagrams in order not to obscure the embodiments in unnecessary detail, hi other instances, well-known circuits, processes, algorithms, structures, components, and techniques may be shown without unnecessary detail in order to avoid obscuring the embodiments.
[0036] While the principles of the disclosure have been described above in connection with specific apparatuses and methods this description is made only by way of example and not as limitation on the scope of the disclosure.

Claims

WHAT IS CLAIMED IS:
L A flip-chip photo diode, comprising: a substrate; an active layer comprising a top and a bottom, wherein the top of the active layer is coupled with the substrate; and a plurality of interconnects coupled with the bottom of the active layer and configured to couple with a circuit board.
2. The flip-chip photodiode according to claim 1, wherein the plurality of interconnects comprise at least one solder ball or at least one epoxy bump.
3. The flip-chip photodiode according to claim 1, further comprising a plurality of interconnects coupled with the bottom of the substrate and configured to couple with a circuit board.
4. The flip-chip photodiode according to claim 3, wherein the plurality of interconnects coupled with the bottom of the substrate comprise at least one solder ball or at least one epoxy bump.
5. The flip-chip photodiode according to claim 1 , wherein the substrate layer comprises indium phosphide.
6. The flip-chip photodiode according to claim 1, wherein the active layer comprises a material selected from the group consisting of indium gallium arsenide, gallium arsenide, aluminum gallium arsenide, silicon, germanium, and lead sulfide.
7. The flip-chip photodiode according to claim 1, wherein the substrate comprises silicon.
8. The flip-chip photodiode according to claim 1 , further comprising a gap between the substrate and the active layer.
9. The flip-chip photodiode according to claim 1, further comprising an antireflective coating on the top surface of the substrate.
10. The flip-chip photodiode according to claim 1, further comprising an intrinsic layer between the substrate and the active layer.
11. The flip-chip photodiode according to claim 1 , wherein the substrate is used as a sunlight filter that eliminates the need for an added filter component.
12. The flip-chip photodiode according to claim 1, wherein the substrate reduces photocurrent.
13. The flip-chip photodiode according to claim 1, wherein the substrate reduces power consumption when reverse biased.
14. A flip-chip photo diode stack, comprising: a substrate with a top surface and a bottom surface, wherein the top surface is configured to receive light; an active layer with a top surface and a bottom surface, wherein the top surface of the active area is coupled with the bottom surface of the substrate; and a printed circuit board with at least a top surface, wherein the bottom surface of the active layer is coupled with the printed circuit board.
15. The flip-chip photodiode according to claim 14, further comprising at least one solder ball coupled with the bottom surface of the active layer and the printed circuit board.
16. The flip-chip photodiode according to claim 14, further comprising at least one connector coupled with the substrate and the printed circuit board.
17. The flip-chip photodiode according to claim 14, wherein the substrate layer comprises indium phosphide.
18. The flip-chip photodiode according to claim 14, further comprising an intrinsic semiconductor layer between the substrate and the active layer.
19. The flip-chip photodiode according to claim 14, wherein the active layer comprises a material selected from the group consisting of indium gallium arsenide; silicon, germanium, and lead sulfide.
20. The flip-chip photodiode according to claim 14, further comprising a gap between the substrate and the active layer.
21. The flip-chip photodiode according to claim 14, further comprising an antireflective coating on the top surface of the substrate.
22. A photodiode comprising: a substrate comprising a top surface and a bottom surface; an active region comprising a top surface and a bottom surface, wherein the top surface of the active region is aligned below the bottom surface of the substrate, wherein the photodiode is configured to receive light through the top surface of the substrate, and wherein at least a portion of the light is incident on the active region.
23. The photodiode according to claim 22, further comprising an intrinsic semiconductor layer between the substrate and the active region.
24. The photodiode according to claim 22, wherein the active region comprises a material selected from the group consisting of indium gallium arsenide, silicon, germanium, and lead sulfide.
25. The photodiode according to claim 22, further comprising at least one connector coupled with the bottom surface of the active region.
26. The photodiode according to claim 22, wherein the substrate is substantially transparent to light with a wavelength of 1550 nm.
27. The photodiode according to claim 22, wherein the substrate is substantially transparent to infrared light.
28. The photodiode according to claim 22, wherein the field of view of the photodiode is at least ±60°.
29. The photodiode according to claim 22, wherein the substrate is used as a sunlight filter that eliminates the need for an added filter component.
30. The photodiode according to claim 22, wherein the substrate reduces photocurrent.
31. The photodiode according to claim 22, wherein the substrate reduces power consumption when reverse biased.
PCT/US2008/069875 2007-07-11 2008-07-11 Flip-chip photodiode WO2009009766A2 (en)

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Families Citing this family (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7956347B2 (en) * 2007-07-11 2011-06-07 Cubic Corporation Integrated modulating retro-reflector
US8929741B2 (en) * 2007-07-30 2015-01-06 Hewlett-Packard Development Company, L.P. Optical interconnect
US8027591B2 (en) * 2007-10-29 2011-09-27 Cubic Corporation Resonant quantum well modulator driver
KR101579332B1 (en) 2008-02-15 2015-12-21 쓰리엠 이노베이티브 프로퍼티즈 컴파니 Brightness enhancing film and film based diffuser for improved illumination uniformity of displays
US9203513B2 (en) * 2008-05-15 2015-12-01 Teledyne Scientific & Imaging, Llc SNR enhancement in modulating retroreflector optical communication links
KR101479783B1 (en) * 2008-09-01 2015-01-08 삼성전자주식회사 Method and apparatus for aligning communication link using retroreflector in visible light communication
JP5197436B2 (en) * 2009-02-26 2013-05-15 株式会社東芝 Sensor chip and manufacturing method thereof.
US20120061789A1 (en) * 2010-09-13 2012-03-15 Omnivision Technologies, Inc. Image sensor with improved noise shielding
US8338200B2 (en) 2011-02-02 2012-12-25 L-3 Communications Cincinnati Electronics Corporation Frontside-illuminated inverted quantum well infrared photodetector devices and methods of fabricating the same
JP2012227670A (en) * 2011-04-19 2012-11-15 Sony Corp Ic card
WO2013040184A1 (en) 2011-09-13 2013-03-21 L-3 Communications Cincinnati Electronics Corporation Frontside-illuminated barrier infrared photodetector device and methods of fabricating the same
KR101974576B1 (en) 2012-04-12 2019-05-02 삼성전자주식회사 Transmitting type optical image modulator having large aperture area and method of manufacturing the same and optical apparatus comprising transmitting type optical image modulator

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5668386A (en) * 1994-09-19 1997-09-16 Fujitsu Limited Planar photodetection device suitable for flip-chip process and a fabrication process of such a planar photodetection device
US6005276A (en) * 1997-11-12 1999-12-21 Advanced Photonix, Inc. Solid state photodetector with light-responsive rear face
JP2000299489A (en) * 1999-04-15 2000-10-24 Hamamatsu Photonics Kk Photoelectric conversion element and light receiver
US6229165B1 (en) * 1997-08-29 2001-05-08 Ntt Electronics Corporation Semiconductor device
US20060180830A1 (en) * 2005-02-17 2006-08-17 Bae Systems Information And Electronic Systems Integration Inc Resonant cavity enhanced multi-quantum well light modulator and detector

Family Cites Families (32)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3845296A (en) * 1973-10-10 1974-10-29 Us Army Photosensitive junction controlled electron emitter
US4328508A (en) * 1979-04-02 1982-05-04 Rca Corporation III-V Quaternary alloy photodiode
US4716449A (en) * 1984-03-14 1987-12-29 American Telephone And Telegraph Company At&T Bell Laboratories Nonlinear and bistable optical device
DE69020189T2 (en) * 1989-03-03 1996-02-29 Mitsubishi Electric Corp Optical component.
JPH03174790A (en) * 1989-09-26 1991-07-29 Fujitsu Ltd Optical semiconductor element
JPH04263475A (en) 1991-02-19 1992-09-18 Nec Corp Semiconductor photodetector and manufacture thereof
JP2898467B2 (en) * 1992-04-15 1999-06-02 三菱電機株式会社 Optical nonlinear element and method of using the same
JPH09331110A (en) * 1996-06-12 1997-12-22 Mitsubishi Electric Corp Optical semiconductor device and manufacture thereof
JPH10294491A (en) * 1997-04-22 1998-11-04 Toshiba Corp Semiconductor light-emitting element, manufacture thereof and light-emitting device
KR100249788B1 (en) * 1997-11-17 2000-03-15 정선종 Photo-induced electro-optic oscillator using pin diode
US6154299A (en) 1998-06-15 2000-11-28 The United States Of America As Represented By The Secretary Of The Navy Modulating retroreflector using multiple quantum well technology
US6845184B1 (en) * 1998-10-09 2005-01-18 Fujitsu Limited Multi-layer opto-electronic substrates with electrical and optical interconnections and methods for making
US6438150B1 (en) * 1999-03-09 2002-08-20 Telecordia Technologies, Inc. Edge-emitting semiconductor laser having asymmetric interference filters
US6646292B2 (en) 1999-12-22 2003-11-11 Lumileds Lighting, U.S., Llc Semiconductor light emitting device and method
GB0008126D0 (en) * 2000-04-03 2000-05-24 Univ Court Of The University O Improvements in and relating to optoelectronic devices
US20020096729A1 (en) * 2001-01-24 2002-07-25 Tu Hsiu Wen Stacked package structure of image sensor
US6803604B2 (en) * 2001-03-13 2004-10-12 Ricoh Company, Ltd. Semiconductor optical modulator, an optical amplifier and an integrated semiconductor light-emitting device
US6687268B2 (en) * 2001-03-26 2004-02-03 Seiko Epson Corporation Surface emitting laser and photodiode, manufacturing method therefor, and optoelectric integrated circuit using the surface emitting laser and the photodiode
DE60208416T2 (en) * 2001-10-09 2006-06-22 Infinera Corp., Sunnyvale Digital Optic Network Architecture
US7751658B2 (en) * 2001-10-09 2010-07-06 Infinera Corporation Monolithic transmitter photonic integrated circuit (TxPIC) having tunable modulated sources with feedback system for source power level or wavelength tuning
WO2003075493A2 (en) 2002-03-05 2003-09-12 Scientific Generics Ltd. Optical free-space signalling system
US6865208B1 (en) * 2002-06-10 2005-03-08 The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration Ultrafast laser beam switching and pulse train generation by using coupled vertical-cavity, surface-emitting lasers (VCSELS)
US7038288B2 (en) * 2002-09-25 2006-05-02 Microsemi Corporation Front side illuminated photodiode with backside bump
US7213942B2 (en) * 2002-10-24 2007-05-08 Ac Led Lighting, L.L.C. Light emitting diodes for high AC voltage operation and general lighting
US6836351B2 (en) * 2002-10-30 2004-12-28 Northrop Grumman Corporation Quantum-confined stark effect quantum-dot optical modulator
US6762473B1 (en) * 2003-06-25 2004-07-13 Semicoa Semiconductors Ultra thin back-illuminated photodiode array structures and fabrication methods
KR100637929B1 (en) * 2004-11-03 2006-10-24 한국전자통신연구원 Hybrid integration type optical device
JP2007005594A (en) * 2005-06-24 2007-01-11 Opnext Japan Inc Semiconductor optical element and module using same
US20070127928A1 (en) 2005-12-07 2007-06-07 Cubic Corporation Large field of view modulating retro reflector (MRR) for free space optical communication
US7576371B1 (en) * 2006-03-03 2009-08-18 Array Optronix, Inc. Structures and methods to improve the crosstalk between adjacent pixels of back-illuminated photodiode arrays
US7888700B2 (en) 2007-03-08 2011-02-15 Eastman Kodak Company Quantum dot light emitting device
US7956347B2 (en) * 2007-07-11 2011-06-07 Cubic Corporation Integrated modulating retro-reflector

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5668386A (en) * 1994-09-19 1997-09-16 Fujitsu Limited Planar photodetection device suitable for flip-chip process and a fabrication process of such a planar photodetection device
US6229165B1 (en) * 1997-08-29 2001-05-08 Ntt Electronics Corporation Semiconductor device
US6005276A (en) * 1997-11-12 1999-12-21 Advanced Photonix, Inc. Solid state photodetector with light-responsive rear face
JP2000299489A (en) * 1999-04-15 2000-10-24 Hamamatsu Photonics Kk Photoelectric conversion element and light receiver
US20060180830A1 (en) * 2005-02-17 2006-08-17 Bae Systems Information And Electronic Systems Integration Inc Resonant cavity enhanced multi-quantum well light modulator and detector

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US8455972B2 (en) 2013-06-04
US20090032894A1 (en) 2009-02-05

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