Optical device and forming method thereof

Abstract

A method of forming an optical device includes forming a photonic integrated circuit, the photonic integrated circuit including: a first waveguide; a second waveguide over the first waveguide, wherein the second waveguide is optically coupled to the first waveguide; a first external coupler optically coupled to the second waveguide; and a first interconnect structure; attaching an electron die to a first side of the photonic integrated circuit; directly bonding the first photonic die to the second side of the photonic integrated circuit, where after the direct bonding, the first photonic die is optically coupled to the first waveguide; and forming a second interconnect structure over the first photonic die and the photonic integrated circuit. The embodiment of the invention also provides an optical device.

Description

Technical Field

[0001] Embodiments of this disclosure relate to optical devices and methods of forming the same. Background Technology

[0002] Optical signal transmission and processing are often combined with electrical signal transmission and processing to provide robust applications. For example, optical fibers can be used for long-range signal transmission, while electrical signals can be used for short-range signal transmission, processing, and control. Accordingly, devices integrating long-range optical components and short-range electrical components are formed for the conversion between optical and electrical signals, as well as the processing of optical and electrical signals. Therefore, packages can include both optical (photonic) components and electronic devices. Summary of the Invention

[0003] Some embodiments of this disclosure provide a method for forming an optical device, the method comprising: forming a photonic integrated circuit, the photonic integrated circuit including: a first waveguide; a second waveguide located above the first waveguide, wherein the second waveguide is optically coupled to the first waveguide; a first external coupler optically coupled to the second waveguide; and a first interconnect structure; attaching an electron die to a first side of the photonic integrated circuit; directly bonding the first photonic die to a second side of the photonic integrated circuit, wherein, after direct bonding, the first photonic die is optically coupled to the first waveguide; and forming a second interconnect structure above the first photonic die and the photonic integrated circuit.

[0004] Other embodiments of this disclosure provide a method for forming an optical device, the method comprising: patterning a first photonic layer to form a first waveguide, wherein the first photonic layer is located on a first side of a first insulating layer; forming a first interconnect structure over the first waveguide; bonding a first electron die to the first interconnect structure; patterning a second photonic layer to form a second waveguide, wherein the second photonic layer is located on a second side of the first insulating layer, wherein the second waveguide overlaps with the first waveguide; depositing a second insulating layer over the second waveguide; bonding a photonic die to the second insulating layer, wherein the photonic die overlaps with the second waveguide; and forming a second interconnect structure over the photonic die and over the second insulating layer, wherein the second interconnect structure is electrically connected to the photonic die and electrically connected to the first interconnect structure.

[0005] Further embodiments of this disclosure provide an optical device comprising: a first interconnect structure; a photonic device located on the first interconnect structure, wherein the photonic device is in physical and electrical contact with the first interconnect structure; a plurality of first waveguides located above the photonic device, wherein the plurality of first waveguides are coupled to the photonic device; a plurality of second waveguides located above the plurality of first waveguides, wherein the plurality of second waveguides are coupled to the plurality of first waveguides; a plurality of grating couplers adjacent to the plurality of second waveguides, wherein the plurality of grating couplers are optically coupled to the plurality of second waveguides; a second interconnect structure located above the plurality of second waveguides; and an electron die coupled to the second interconnect structure. Attached Figure Description

[0006] The aspects of this disclosure are best understood from the following detailed description when read in conjunction with the accompanying drawings. It should be noted that, in accordance with standard industry practice, the various components are not drawn to scale. In fact, the dimensions of the various components may be arbitrarily increased or decreased for clarity of discussion.

[0007] Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 , Figure 7 , Figure 8 , Figure 9 and Figure 10 Intermediate steps in forming an optical engine with a photodetector die, according to some embodiments, are shown.

[0008] Figure 11 An optical engine with a photodetector die is shown according to some embodiments.

[0009] Figure 12 An optical engine with a photodetector die is shown according to some embodiments.

[0010] Figure 13 An optical engine with a photodetector die is shown according to some embodiments.

[0011] Figure 14 An optical engine with a photodetector die is shown according to some embodiments.

[0012] Figure 15 and Figure 16 Intermediate steps in forming an optical engine with a modulator die, according to some embodiments, are shown.

[0013] Figure 17 An optical engine with a modulator die is shown according to some embodiments.

[0014] Figure 18An optical engine with a modulator die is shown according to some embodiments.

[0015] Figure 19 An optical engine with a modulator die is shown according to some embodiments.

[0016] Figure 20 An optical engine having a modulator die and a photodetector die is shown according to some embodiments.

[0017] Figure 21 A top view of an optical engine according to some embodiments is shown.

[0018] Figure 22 An optical engine having a modulator die and a photodetector die is shown according to some embodiments. Detailed Implementation

[0019] The following disclosure provides numerous different embodiments or instances of various components for implementing this application. Specific examples of components and arrangements are described below to simplify this disclosure. Of course, these are merely examples and not intended to be limiting. For example, in the following description, forming a first component above or on a second component may include embodiments where the first and second components are in direct contact, and may also include embodiments where an additional component may be formed between the first and second components, thereby allowing the first and second components to not be in direct contact. Additionally, reference numerals and / or characters may be repeated in various instances of this disclosure. This repetition is for clarity and simplicity and does not, in itself, indicate a relationship between the individual embodiments and / or configurations discussed.

[0020] Furthermore, for ease of description, spatial relative terms such as “below,” “under,” “lower,” “above,” and “upper” may be used herein to describe the relationship between one element or component and another, as shown in the figures. In addition to the orientations shown in the figures, spatial relative terms are intended to encompass different orientations of the device during use or operation. The device may be positioned in other ways (rotated 90 degrees or in other orientations), and the spatial relative descriptors used herein can be interpreted accordingly.

[0021] This article describes various structures of packages, such as those containing photonic structures and optical engines, and methods for their fabrication. During the fabrication of the optical engine, photonic dies (such as photodetector dies and / or modulator dies) are directly bonded to a photonic integrated circuit (PIC). This allows for the use of more efficient or higher bandwidth photodetectors or modulators within the optical engine. The photonic die can be optically coupled to a waveguide within the optical engine. In this way, the data rate of the optical engine can be improved.

[0022] The embodiments discussed herein provide examples of how the subject matter of this disclosure can be made or used, and those skilled in the art will readily understand that modifications can be made while remaining within the intended scope of the various embodiments. Throughout the various views and illustrative embodiments, the same reference numerals are used to denote the same elements. While method embodiments may be discussed as being performed in a particular order, other method embodiments may be performed in any logical order. More precisely, the embodiments discussed can be incorporated into a variety of different implementations, and all such implementations are intended to be fully encompassed within the scope of the embodiments.

[0023] Figures 1 to 11 An optical engine 100 according to some embodiments is shown (see [link]). Figure 11 The optical engine 100 includes a waveguide, photonic components, and an integrated circuit that can be configured to receive, generate, modify, transmit, and / or process optical signals. In some embodiments, the optical engine 100 provides an input / output (I / O) interface between optical and electrical signals within a package or package assembly. In some embodiments, the optical engine 100 provides an optical network for signal communication between various components (e.g., photonic devices, integrated circuits, coupling to external optical fibers, etc.). In this way, the optical engine 100 can ensure photoelectric (OE) conversion of package-level optical communication (e.g., within the package). The optical engine 100 described herein can provide high-speed optical signal modulation and / or optical signal detection, thereby ensuring data rates greater than approximately 400 Gbps. In some cases, the optical engine 100 can be considered as a photonic package assembly, an optical package module, a silicon photonic chip, etc.

[0024] Go to Figure 1According to some embodiments, at this stage, the optical engine 100 includes a substrate 10, a dielectric layer 12, and a photonic layer 14. In embodiments, at the start of the fabrication process of the optical engine 100, the substrate 10, dielectric layer 12, and photonic layer 14 may collectively be part of a silicon-on-insulator (SOI) substrate, which may be doped (e.g., doped with p-type or n-type dopants) or undoped. In some embodiments, the substrate 10 may be a wafer, such as a silicon wafer. Other substrates may also be used, such as silicon-on-insulator (SOI) substrates, multilayer substrates, or gradient substrates. In some embodiments, the semiconductor material of the substrate 10 may include silicon, germanium; compound semiconductors including silicon carbide, gallium arsenide, gallium phosphide, indium phosphide, indium arsenide, and / or indium antimonide; alloy semiconductors including silicon germanium, gallium arsenide phosphide, aluminum indium arsenide, aluminum gallium arsenide, gallium indium arsenide, gallium indium phosphide, and / or gallium arsenide phosphide; or combinations thereof. In other embodiments, substrate 10 may be a dielectric material, such as silicon oxide, glass, ceramic, plastic, or any other suitable material that allows for structural support of the devices thereon. Other substrates, such as multilayer substrates or gradient substrates, may also be used. In some cases, substrate 10 may contain no passive or active devices. In some embodiments, a plurality of optical engines 100 are formed on a single substrate 10, and then the plurality of optical engines 100 are subsequently cut into individual optical engines 100.

[0025] The dielectric layer 12 may be a dielectric layer separating the substrate 10 from the photonic layer 14 above it. In some embodiments, the dielectric layer 12 may also serve as an insulating layer or as part of a covering material surrounding a subsequently fabricated photonic component (described below). In embodiments, the dielectric layer 12 may be silicon oxide, silicon nitride, germanium oxide, germanium nitride, etc., or combinations thereof. The dielectric layer 12 may be formed using techniques such as ion implantation (e.g., to form a buried oxide (BOX) layer) or using suitable deposition techniques such as chemical vapor deposition (CVD), atomic layer deposition (ALD), physical vapor deposition (PVD), or combinations thereof. In some embodiments, the dielectric layer 12 may be deposited onto a substrate with approximately to approximately The thickness varies. However, any suitable material, thickness, or manufacturing method can be used.

[0026] A photonic layer 14 is formed over the dielectric layer 12. In some embodiments, the photonic layer 14 may be a semiconductor material, such as silicon, germanium, silicon-germanium, or a combination thereof. In other embodiments, the photonic layer 14 may include a dielectric material, such as silicon nitride, III-V semiconductor materials, compound semiconductor materials, lithium niobate materials, polymers, or a combination thereof. Suitable techniques, such as epitaxial growth, CVD, ALD, PVD, or a combination thereof, may be used to form the photonic layer 14. In other embodiments, the photonic layer 14 may be a material suitable for forming an optical waveguide, such as silicon nitride. Other materials or techniques are possible. In some cases, the photonic layer 14 may be considered as an "active layer," an "optical layer," a "core layer," etc.

[0027] Figure 2 A photonic component formed from a photonic layer 14 according to some embodiments is shown. In some embodiments, the photonic component may include devices or components such as optical waveguides (e.g., ridge waveguides, rib waveguides, buried channel waveguides, diffused waveguides, etc.), couplers (e.g., grating couplers, end-face couplers, or other external couplers), evanescent wave couplers, directional couplers, optical modulators (e.g., germanium modulators, Mach-Zehnder silicon photonic switches, microelectromechanical switches, microring resonators, etc.), amplifiers, multiplexers, demultiplexers, photoelectric converters (e.g., photodetectors, PN junctions, etc.), electro-optic converters, lasers (e.g., laser diodes), phase shifters, combinations thereof, etc. As an exemplary photonic component, Figure 2 A silicon waveguide 15, a grating coupler 16, and an optics device 17 are shown. The silicon waveguide 15 can be, for example, a strip waveguide with a thickness of about 270 nm; however, other waveguides are also possible. Some photonic components can be optically coupled so that optical signals and / or optical power can be transmitted between the photonic components. For example, the silicon waveguide 15 can be optically coupled to the grating coupler 16. Different numbers of photonic components can be present, and the photonic components can include other devices, structures, or components besides those shown above.

[0028] In some embodiments, a photonic component can be formed by patterning the photonic layer 14 into a suitable shape for the photonic component. For example, the photonic layer 14 can be patterned using one or more photolithographic masking and etching processes; however, any suitable method for patterning the photonic layer 14 can also be utilized. Patterning may expose portions of the dielectric layer 12. In some cases, additional processing steps may be performed to form certain types of photonic components, such as additional implantation processes, deposition processes, epitaxial growth processes, and / or patterning processes. In some embodiments, one or more photonic components can be formed by patterning the photonic layer 14 and then depositing another material on portions of the patterned photonic layer 14. For example, the formation of a photonic component may include patterning the photonic layer 14 comprising silicon and then epitaxially growing a germanium region on the patterned photonic layer 14. Other materials, techniques, or process steps are also possible.

[0029] Still referencing Figure 2 According to some embodiments, a dielectric layer 18 may be formed over the dielectric layer 12 and / or the photonic components. The dielectric layer 18 may be, for example, an insulating or dielectric material that isolates the individual photonic components from each other and from the overlying structure. Furthermore, in some cases, the dielectric layer 18 may serve as a covering material that at least partially surrounds one or more photonic components. In some embodiments, the dielectric layer 18 may include silicon oxide, silicon nitride, germanium oxide, germanium nitride, combinations thereof, etc., and may be formed using suitable deposition techniques such as CVD, ALD, PVD, etc. Other materials or deposition techniques are also possible. In some embodiments, after depositing the dielectric layer 18, a planarization process (e.g., chemical mechanical polishing (CMP), grinding, etc.) may be performed to planarize the top surface of the dielectric layer 18. In some embodiments, the planarization process may expose the top surface of one or more photonic components. In such embodiments, the top surfaces of some photonic components and the top surface of dielectric layer 18 may be flush or coplanar (within the range of process variations). In some embodiments, after a planarization process is performed, one or more photonic components remain covered by dielectric layer 18.

[0030] Figure 3An interconnect structure 20 formed over a photonic component is illustrated according to some embodiments. In some embodiments, the interconnect structure 20 includes a dielectric layer 22 (not shown separately) in which conductive components 24 are formed. The conductive components 24 allow electrical communication within the optical engine 100. The conductive components 24 may include wires, conductive vias, conductive pads, metallization patterns, redistribution layers, etc., providing electrical interconnections and wiring within the optical engine 100. In some cases, some conductive components 24 may be electrically connected to one or more photonic components. In some embodiments, the interconnect structure 20 may also include conductive pads 28 located on the top surface of the interconnect structure 20. The conductive pads 28 may be metal pads, bonding pads, etc.

[0031] In some embodiments, the interconnect structure 20 is formed of alternating layers of dielectric material (e.g., dielectric layer 22) and conductive material (e.g., conductive component 24). Any suitable process, such as deposition, damascene, dual damascene, etc., can be used to form the conductive component 24. In certain embodiments, the interconnect structure 20 may have multiple layers of conductive component 24, but the exact number of layers of conductive component 24 may depend on the design of the optical engine 100. The dielectric layer 22 may be, for example, an insulating layer and / or a passivation layer, and may include silicon oxide, silicon nitride, polymers, molding materials, etc., or combinations thereof. The conductive component 24 may comprise, for example, metals or metal alloys, such as copper, silver, gold, tungsten, cobalt, ruthenium, aluminum, alloys thereof, combinations thereof, etc. Other materials or forming techniques are possible.

[0032] In some embodiments, conductive pads 28 are formed in the topmost dielectric layer 22 (not shown separately) of dielectric layer 22. In some embodiments, conductive pads 28 may include via portions (not shown separately) that are in physical and electrical contact with the underlying conductive component 24. In some embodiments, the topmost dielectric layer 22 of interconnect structure 20 may be a material suitable for dielectric-to-dielectric bonding, such as silicon oxide, silicon nitride, silicon oxynitride, etc. Other materials are possible. In some embodiments, conductive pads 28 may be formed by first forming an opening (not shown separately) in the topmost dielectric layer 22 that exposes some conductive portion of the underlying conductive component 24; depositing an optional pad in the opening; and then depositing a conductive material in the opening. The conductive material may be similar to the conductive material described with respect to conductive component 24. For example, in some embodiments, the conductive material may be copper or a copper alloy. A planarization process (e.g., CMP or polishing process) may be performed to remove excess conductive material so that the top surfaces of conductive pads 28 and the topmost dielectric layer 22 are substantially flush. This is an example, and other materials, techniques, or process steps can be used to form conductive pads 28.

[0033] Additionally, according to some embodiments, one or more photonic components 26 may be formed within the dielectric layer 22 during the fabrication of the interconnect structure 20. The photonic components 26 may be similar to the previously described photonic components. For example, in some embodiments, the photonic component 26 may include waveguides (e.g., silicon nitride waveguides), couplers, etc. In some cases, one or more photonic components 26 may be optically coupled to each other and / or optically coupled to one or more underlying photonic components within the dielectric layer 18. For example, in some embodiments, the photonic component 26 may be a silicon nitride waveguide optically coupled to the underlying silicon waveguide 15 via, for example, evanescent optical coupling. The photonic component 26 may be, for example, a silicon nitride strip waveguide with a thickness of about 400 nm; however, other waveguides are also possible.

[0034] In some embodiments, during the fabrication of interconnect structure 20, photonic component 26 can be formed by depositing material for photonic component 26 on dielectric layer 22. The material for photonic component 26 can be a dielectric material, such as silicon nitride, silicon oxide, silicon oxynitride, polymers, combinations thereof, etc.; or a semiconductor material, such as silicon, germanium, etc. The material can then be patterned into a suitable shape for photonic component 26 using appropriate photolithography and etching techniques. Another dielectric layer 22 can then be deposited on photonic component 26. In certain embodiments, interconnect structure 20 may have multiple layers of photonic component 26, but the exact number of layers of photonic component 26 may depend on the design of optical engine 100.

[0035] In some cases, the individual dielectric layers (e.g., layers 12, 18, and 22), photonic components (e.g., components 15, 16, 17, and 26), and interconnect structure 20 can be considered as "photonic wafers," "photonic integrated circuits" (PICs), etc. Accordingly, for ease of reference, some of the figures indicate PIC 40. PIC 40 may contain other layers, components, or parts besides those shown in the figures.

[0036] exist Figure 4In some embodiments, the electron die 30 is bonded to the interconnect structure 20 of the PIC 40. The electron die 30 can be, for example, a semiconductor device, die, component, or chip. The electron die 30 may include an integrated circuit and can interact with various components of the optical engine 100 using electrical signals. These components may include, for example, photonic components, photonic dies (e.g., photodetector dies, modulator dies, etc.). For example, the electron die 30 may include a controller, driver, transimpedance amplifier, transistor, other active devices, resistors, capacitors, other passive devices, etc., or combinations thereof. Accordingly, the electron die 30 can be considered as an electronic integrated circuit (EIC) structure, etc. In some embodiments, the electron die 30 can process electrical signals received from the photonic die (or photonic component, photonic device, etc.), control the operation of the photonic die, and / or generate electrical signals that the photonic die converts into optical signals. Figure 4 One electron tube 30 is shown, but in other embodiments, the optical engine 100 may include two or more electron tubes 30.

[0037] In some embodiments, die 30 may provide serializer / deserializer (SerDes) functionality. In this way, die 30 may act as part of the I / O interface between optical and electrical signals within or within a package or package assembly including optical engine 100. In some embodiments, die 30 may include one or more processing devices, such as a central processing unit (CPU or “xPU”), graphics processing unit (GPU), application-specific integrated circuit (ASIC), high-performance computing (HPC) die, logic die, or combinations thereof. Die 30 may include one or more memory devices, which may be volatile memory, such as dynamic random access memory (DRAM), static random access memory (SRAM), high-bandwidth memory (HBM), or another type of memory. Other dies 30 or their configurations are possible.

[0038] In some embodiments, the die 30 may include bonding pads formed in a bonding layer, and the die 30 is bonded to the interconnect structure 20 by dielectric-to-dielectric bonding and / or metal-to-metal bonding (e.g., direct bonding, fusion bonding, oxide-to-oxide bonding, hybrid bonding, etc.). In some embodiments, a bonding layer (e.g., an exposed dielectric layer) of the die 30 is bonded to a bonding layer (e.g., an exposed dielectric layer, such as the topmost dielectric layer 22) of the interconnect structure 20 using a dielectric-to-dielectric bonding process, and conductive pads of the die 30 are bonded to corresponding conductive pads 28 of the interconnect structure 20 using a metal-to-metal bonding process. In some embodiments, the bonding process can be initiated by activating the bonding surfaces of the die 30 and the interconnect structure 20, which can facilitate bonding of the bonding surfaces. Activating the bonding surfaces may include, for example, dry processing, wet processing, plasma processing, exposure to inert gas plasma, exposure to H2, exposure to N2, exposure to O2, combinations thereof, etc. For embodiments using wet processing, for example, an RCA cleaning process may be used. In other embodiments, the activation process may include other types of processing. After the activation process, the die 30 is aligned with the interconnect structure 20 and positioned in physical contact with the interconnect structure 20. The die 30 and the interconnect structure 20 are then subjected to heat treatment and contact pressure to bond their respective bonding layers together via dielectric-to-dielectric bonding and to bond the conductive pads of the die 30 to the conductive pads 28 of the interconnect structure 20 via metal-to-metal bonding. In some embodiments, the resulting bonded structure is subsequently baked, annealed, pressed, or otherwise treated to enhance or complete the bond. This is an example, and other bonding processes are possible. In other embodiments, the die 30 may include conductive connectors (e.g., solder bumps, etc.), and these conductive connectors may be used to bond the die 30 to the interconnect structure 20.

[0039] In addition, Figure 4In some embodiments, a dielectric material 34 is formed over the electron die 30 and the interconnect structure 20. The dielectric material 34 may be formed from silicon oxide, silicon nitride, polymers, or combinations thereof. The dielectric material 34 may be formed by CVD, PVD, ALD, spin coating, or combinations thereof. In some embodiments, the dielectric material 34 may be formed by HDP-CVD, FCVD, PECVD, or combinations thereof. In some embodiments, the dielectric material 34 may be a gap-filling material, which may comprise one or more of the exemplary materials described above. In some embodiments, the dielectric material 34 may be a material substantially transparent to light of a wavelength suitable for transmitting optical signals or optical power (e.g., silicon oxide). For example, the dielectric material 34 may allow optical signals or optical power to be transmitted between photonic components (e.g., grating coupler 16, etc.) and the optical fibers, fiber array units, etc., above it. In some embodiments, the dielectric material 34 may be a material similar to the material of dielectric layer 22 and / or dielectric layer 18. Other dielectric materials formed by any acceptable process may be used. Planarization processes, such as CMP or polishing, can be used to planarize the dielectric material 34. In other embodiments, the planarization process can expose the die 30 so that the surfaces of the die 30 and the dielectric material 34 are coplanar.

[0040] In addition, Figure 4 In some embodiments, a support member 36 is attached to the structure. The support member 36 is a rigid structure attached to the structure to provide structural or mechanical stability. The use of the support member 36 can reduce warpage or bending, which can improve the performance of the photonic components within the optical engine 100. According to some embodiments, the support member 36 can be attached to the structure (e.g., to the dielectric material 34 and / or the electron die 30) using a bonding layer (not shown) formed over the dielectric material 34 and the electron die 30. In some embodiments, the bonding layer can be an adhesive layer. In other embodiments, the bonding layer can be a dielectric layer suitable for dielectric-to-dielectric bonding of the support member 36. For example, the bonding layer can be deposited on the dielectric material 34 and the electron die 30, and the support member 36 can then be bonded to the bonding layer using a suitable dielectric-to-dielectric bonding technique.

[0041] In some embodiments, the support 36 is formed of a material transparent to light of a relevant wavelength, allowing optical signals to be transmitted through the support 36. In some embodiments, a lens 38 is formed in the upper surface of the support 36. The lens 38 can be optically coupled to a photonic component through the support 36. In some embodiments, the lens 38 facilitates optical coupling between the photonic component (e.g., grating coupler 16, etc.) and the optical fiber, fiber array unit, etc., above it. In some embodiments, the lens 38 is formed in the support 36 using one or more patterning steps, which may include suitable photolithography and etching processes. In this way, the lens 38 may include grooves, etc., located in the top surface of the support 36. In other embodiments, the lens 38 is formed separately and attached to the support 36. In some embodiments, a refractive index matching material, etc. (not shown), is deposited over the lens 38. In some embodiments, the support 36 may include multiple lenses 38. Figure 4 The lens 38 shown is an example, and the lens 38 can be a lens structure with other shapes or sizes than those shown in the figure.

[0042] exist Figure 5 In some embodiments, substrate 10 is removed. The structure can be flipped, such as... Figure 5 As shown. The substrate 10 can be removed using planarization processes (e.g., CMP, polishing, etc.) and / or etching processes. In some embodiments, removing the substrate 10 exposes the dielectric layer 12. In some embodiments, removing the substrate 10 may include a thinned dielectric layer 12. The thinned dielectric layer 12 may have a dielectric layer thickness of approximately [missing information]. to approximately The thickness is within the range specified, however other thicknesses are also possible. In some embodiments, the dielectric layer 12 serves as a stop layer during substrate 10 removal. In other embodiments, the dielectric layer 12 is removed.

[0043] exist Figure 6 In some embodiments, a photonic material 41 is deposited over the dielectric layer 12. The photonic material 41 can be a dielectric material, such as silicon nitride, silicon oxide, silicon oxynitride, polymers, combinations thereof, etc. In other embodiments, the photonic material 41 can be a semiconductor material, such as silicon, germanium, etc. Suitable techniques, such as CVD, ALD, PVD, etc., can be used to deposit the photonic material 41. For example, the photonic material 41 can be a material having approximately to approximately Silicon nitride of various thicknesses is possible, however other materials or thicknesses are also possible.

[0044] exist Figure 7In some embodiments, waveguide 42 is formed of photonic material 41. For example, waveguide 42 may be a silicon nitride waveguide with a thickness of about 400 nm; however, other waveguides 42 are possible. More than one waveguide 42 may be formed of photonic material 41. In some embodiments, photonic components such as grating couplers, end-face couplers, evanescent wave couplers, etc., are also formed of photonic material 41, and these photonic components may be optically coupled to waveguide 42. Waveguide 42 can be formed by patterning photonic material 41 using suitable photolithography and etching techniques.

[0045] A dielectric layer 44 can then be deposited over waveguide 42. Dielectric layer 44 can be a material similar to dielectric layer 18 or dielectric layer 22. In some embodiments, dielectric layer 44 is a material suitable for dielectric-to-dielectric bonding, such as silicon oxide. Accordingly, in some cases, dielectric layer 44 can be considered as a bonding layer of PIC 40. In some embodiments, a planarization process (e.g., CMP or polishing) can be performed on dielectric layer 44. After performing the planarization process, the thickness of dielectric layer 44 over waveguide 42 can be less than about 200 nm; however, in some embodiments, other thicknesses are possible. The steps of depositing photonic material, patterning photonic material to form layers of waveguide, and then depositing a dielectric layer over the layers of waveguide can be repeated to form multiple layers of waveguide. In some cases, waveguide 42, other waveguides formed of photonic material, and / or photonic components formed of photonic material are considered as part of PIC 40.

[0046] Figure 8 and Figure 9 The bonding of a photodetector die 50 to a PIC 40 according to some embodiments is shown. Figure 8 The photodetector die 50 before bonding is shown, and Figure 9 The diagram illustrates the structure after the photodetector die 50 has been bonded to the PIC 40. In some embodiments, the photodetector die 50 may include a photodetector based on a III-V semiconductor material or a compound semiconductor material, such as gallium arsenide (GaAs), indium gallium arsenide (InGaAs), etc. In other embodiments, other photodetector materials, such as germanium, may also be used. In some cases, the specific semiconductor material or its composition may depend on the wavelength of the light used within the optical engine 100 by the optical signal or optical power. Forming the photodetector die 50 separately and bonding it to the PIC 40 allows the use of photodetector materials that are difficult to manufacture within the PIC 40, such as some III-V semiconductor materials. Accordingly, the optical engine 100 can benefit from the improved speed, sensitivity, bandwidth, or efficiency offered by the photodetector die 50 utilizing these photodetector materials.

[0047] In some embodiments, the photodetector die 50 includes a bonding layer 52. The bonding layer 52 includes a material suitable for direct bonding to the dielectric layer 44. For example, in some embodiments, the bonding layer 52 includes silicon oxide, indium phosphide, etc. The bonding layer 52 may include multiple layers, at least the outermost layer (e.g., the bottom layer) being a material suitable for direct bonding. Above the bonding layer 52 is a photodetector 54, which may include one or more materials comprising the aforementioned photodetector materials. In some embodiments, the photodetector 54 includes a waveguide (not separately labeled) and is configured to detect or respond to an optical signal or optical power within the waveguide. In some embodiments, the photodetector die 50 includes multiple photodetectors 54. The photodetectors 54 may be covered by one or more dielectric layers 53, which may be similar to the dielectric layers previously described or may include different materials. The photodetector die 50 also includes a via 56 extending through the dielectric layer 53 to make electrical contact with the photodetector 54, thereby allowing electrical signals or power to be transmitted to or from the photodetector 54. In some embodiments, the photodetector die 50 has a thickness in the range of about 2 μm to 4 μm; however, other thicknesses are also possible. The photodetector die 50 may include integrated circuits, electrical interconnects, or other components. Figure 8 Other suitable components are not shown. Accordingly, the photodetector die 50 shown is a representative example, and other configurations or structures are also possible. In some cases, in addition to the photodetector 54, the photodetector die 50 may also include a photonic component.

[0048] refer to Figure 9 According to some embodiments, a photodetector die 50 is bonded to a PIC 40. The photodetector die 50 can be bonded to the PIC 40 using a direct bonding process, such as a dielectric-to-dielectric bonding process. In certain embodiments utilizing a dielectric-to-dielectric bonding process, the process can be initiated by activating the bonding surfaces of the photodetector die 50 and the PIC 40, such as the surface of the bonding layer 52 of the photodetector die 50 and the surface of the dielectric layer 44 of the PIC 40. Activating the bonding surfaces of the photodetector die 50 and the PIC 40 can include dry processing, wet processing, plasma processing, exposure to an inert gas plasma, exposure to H2, exposure to N2, exposure to O2, etc., or combinations thereof. For embodiments performing wet processing, for example, RCA cleaning can be used. In other embodiments, the activation process can include other types of processing. The activation process facilitates bonding the photodetector die 50 to the PIC 40.

[0049] After the activation process, the bonding layer 52 and dielectric layer 44 can be cleaned using, for example, chemical cleaning. The photodetector die 50 is then aligned with the dielectric layer 44 and positioned in physical contact with it. The photodetector die 50 and PIC 40 are then subjected to heat treatment and contact pressure to bond them together. For example, the photodetector die 50 and dielectric layer 44 can be subjected to a pressure of about 200 kPa or less and a temperature of about 25°C to about 250°C to melt the bonding layer 52 and dielectric layer 44. In this way, the photodetector die 50 and PIC 40 form a dielectric-to-dielectric bonding structure. In some embodiments, the bonded structure is subsequently baked, annealed, pressed, or otherwise treated to strengthen or complete the bonding. Furthermore, while specific processes for initiating and strengthening the bonding have been described, these descriptions are illustrative and not intended to limit the embodiments. Rather, any suitable combination of baking, annealing, pressing, or other processes can be utilized. All such processes are intended to be included within the scope of the embodiments.

[0050] In some embodiments, the photodetector die 50 can be aligned with the waveguide 42 such that the photodetector die 50 is optically coupled to the waveguide 42. For example, the photodetector die 50 can overlap with the waveguide 42 such that the waveguide 42 is evanescently coupled to the photodetector 54 of the photodetector die 50. In this way, optical signals and / or optical power can be transmitted between the PIC 40 and the photodetector die 50. As described herein, using direct bonding to bond the photodetector die 50 to the PIC 40 can allow for improved optical coupling between the photodetector die 50 and the PIC 40. In some embodiments, one or more photodetector dies 50 can be bonded to the PIC 40 and optically coupled to one or more waveguides 42.

[0051] Figure 10 The formation of additional layers and conductive components according to some embodiments is illustrated, thereby forming an optical engine 100. After the photodetector die 50 is bonded to the PIC 40, a dielectric material 62 may be deposited over the dielectric layer 44 and around the photodetector die 50. In some cases, the dielectric material 62 may be a gap filler material or the like that that fills gaps and provides additional structural support. In some embodiments, the dielectric material 62 is a material such as silicon oxide, silicon nitride, silicon oxynitride, or combinations thereof, and suitable techniques may be used to deposit the dielectric material 62. In some embodiments, a planarization process (e.g., CMP or polishing process) may be performed to remove excess dielectric material 62. In some cases, the planarization process may expose the top surface of the photodetector die 50 such that the surfaces of the photodetector die 50 and the dielectric material 62 are substantially flush or coplanar.

[0052] In some embodiments, an optional dielectric layer 63 is deposited over the dielectric material 62 and the photodetector die 50. In some cases, the dielectric layer 63 may be an etch stop layer. The dielectric layer 63 may be a suitable material, such as silicon nitride, silicon oxide, metal oxide, or a combination thereof. In some embodiments, the dielectric layer 63 has approximately to approximately The thickness is within the range, however other thicknesses are also possible. In other embodiments, dielectric layer 63 is omitted.

[0053] In some embodiments, an interconnect structure 60 may be formed over the dielectric layer 63. In some embodiments, the interconnect structure 60 includes one or more dielectric layers 67 (not shown separately), in which one or more conductive components 65 are formed. Figure 10 A single-layer conductive component 65 is shown, but in other embodiments, multiple layers of conductive components 65 may be formed. The conductive components 65 allow electrical communication within the optical engine 100. The conductive components 65 may include wires, conductive vias, conductive pads, metallization patterns, redistribution layers, etc., providing electrical interconnections and wiring within the optical engine 100. In some cases, some conductive components 65 may be electrically connected to one or more photonic components and / or photodetector dies 50.

[0054] In some embodiments, the interconnect structure 60 is formed of alternating layers of dielectric material (e.g., dielectric layer 67) and conductive material (e.g., conductive component 65). The conductive component 65 can be formed using any suitable process, such as deposition, damascene, dual damascene, etc. In certain embodiments, the interconnect structure 60 may have multiple layers of conductive component 65, but the exact number of layers of conductive component 65 may depend on the design of the optical engine 100. For example, the dielectric layer 67 may be an insulating layer and / or a passivation layer, and may include silicon oxide, silicon nitride, polymers, molding materials, etc., or combinations thereof. In some cases, the dielectric layer 67 may contain a passivation layer or a bonding layer. For example, the conductive component 65 may contain metals or metal alloys, such as copper, silver, gold, tungsten, cobalt, ruthenium, aluminum, alloys thereof, combinations thereof, etc. Other materials or forming techniques are also possible.

[0055] In some embodiments, via 64 is formed to extend through dielectric layer 67, dielectric layer 63, and / or other underlying dielectric layers. Via 64 may physically and electrically contact conductive components 65 of interconnect structure 60, via 56 of photodetector die 50, and / or conductive components 24 of interconnect structure 20. In this way, via 64 provides some electrical connections between PIC 40, EIC 30, photodetector die 50, and interconnect structure 60. In some embodiments, one or more vias 64 extend through bonding layer 52, dielectric layer 44, dielectric layer 12, and dielectric layer 18 to contact conductive components 24 of interconnect structure 20, and in some embodiments, some vias 64 may extend into one or more dielectric layers 22 of interconnect structure 20.

[0056] For example, a via 64 can be formed by creating an opening on the surface of a conductive component 24 of the interconnect structure 20 or a via 56 of the photodetector die 50. Acceptable photolithography and etching techniques can be used to form the opening, such as by forming and patterning a photoresist, and then performing an etching process using the patterned photoresist as an etching mask. The etching process can include, for example, dry etching and / or wet etching processes. A conductive material can then be deposited in the opening to form the via 64. In some embodiments, a pad (not shown) can be deposited in the opening prior to the formation of the conductive material. The conductive material can include, for example, a metal or metal alloy, such as copper, silver, gold, tungsten, cobalt, aluminum, alloys thereof, etc. A planarization process (e.g., CMP or polishing) can be performed to remove excess conductive material so that the surfaces of the via 64 and the dielectric layer 67 are flush. A conductive component 65 can be formed over the via 64, and the conductive component 65 can directly contact the via 64. Other materials or techniques are possible. In other embodiments, the via 64 is formed at a stage of the manufacturing process other than those described above.

[0057] Further in Figure 10 In some embodiments, conductive connectors 66 are formed on the interconnect structure 60. The conductive connectors 66 can be used to electrically connect the optical engine 100 to external structures, such as a packaging substrate, a core substrate, an interposer, etc. In some embodiments, a bump under-metallization (UBM) 69 is formed within the interconnect structure 60 to make physical and electrical contact with conductive components 65 within the interconnect structure 60. In some embodiments, the UBM 69 has bump portions located on and extending along the main surface of a dielectric layer 67 (such as the topmost dielectric layer 67). The UBM 69 can be formed from one or more conductive materials using suitable processes (such as plating). In some embodiments, the UBM 69 is not formed.

[0058] According to some embodiments, conductive connectors 66 are then formed on the UBM 69. The conductive connectors 66 can be, for example, ball grid array (BGA) connectors, solder balls, metal pillars, controlled collapse chip connection (C4) bumps, microbumps, bumps formed using electroless nickel-palladium immersion gold (ENEPIG) technology, etc. The conductive connectors 66 can contain conductive materials such as solder, copper, aluminum, gold, nickel, silver, palladium, tin, etc., or combinations thereof. In some embodiments, the conductive connectors 66 are initially formed by a solder layer formed via evaporation, electroplating, printing, solder transfer, ball placement, etc. Once the solder layer is structurally formed, reflow can be performed to shape the material into the desired bump shape. In another embodiment, the conductive connectors 66 include metal pillars (such as copper pillars) formed by sputtering, printing, electroplating, electroless plating, CVD, etc. The metal pillars can be solderless and have substantially vertical sidewalls. In some embodiments, a metal cap layer is formed on the top of the metal pillar. The metal cap layer may comprise nickel, tin, tin-lead, gold, silver, palladium, indium, nickel-palladium-gold, nickel-gold, or combinations thereof, and may be formed by a plating process. In other embodiments, conductive connector 66 is omitted, and UBM 69 is a bonding pad for metal-to-metal bonding with external components. In this way, optical engine 100 can be formed. Figure 10 The optical engine 100 shown is an example, and other process steps, materials, configurations, or arrangements are also possible.

[0059] According to some embodiments, Figure 11 It shows Figure 10 Optical engine 100, Figure 10The optical engine 100 is flipped and a simplified optical path diagram is shown (indicated by arrow 101). Arrow 101 indicates the possible path of the optical signal entering the optical engine 100 and being received and detected by the photodetector die 50. The optical signal can be transmitted to the optical engine 100 from an optical fiber, etc. (not shown separately). The optical signal is transmitted through the lens 38, support 36, dielectric material 34, and interconnect structure 20 to the grating coupler 16. The grating coupler 16 receives the optical signal and couples it to the silicon waveguide 15. The optical signal is then evanescently coupled from the silicon waveguide 15 to the waveguide 42. The optical signal is then evanescently coupled from the waveguide 42 to the photodetector die 50. The photodetector die 50 detects the optical signal and generates a corresponding electrical signal, which is transmitted through the connected via 64 to the interconnect structure 60. The electrical signal can be transmitted to the conductive connector 66 and / or the electron die 30. In some cases, electrical signals and / or electrical power can be transmitted to the photodetector die 50, such as electrical signals transmitted from the electron die 30 or electrical power transmitted from the conductive connector 66. In other embodiments, optical signals can be coupled between waveguides using grating couplers or other techniques instead of evanescent coupling. In this way, the techniques described herein can allow high-speed photodetectors to be incorporated into the optical engine, thus ensuring high-bandwidth optical communication.

[0060] In some cases, some optical signals transmitted to the photodetector die 50 can be transmitted out of the photodetector die 50 to enter other waveguides. For example, Figure 12 An optical engine 150 according to some embodiments is shown. The optical engine 150 is similar to... Figure 11 The optical engine 100 differs in that additional waveguides and grating couplers are shown. For example, waveguides 15A-B and grating couplers 16A-B can be similar to waveguide 15 and grating coupler 16 of the optical engine 100, and waveguides 42A-B can be similar to waveguide 42 of the optical engine 100. For clarity, Figure 12 Some components may not be shown in the text, including... Figure 11 Some of the components shown. Figure 12 A simplified optical path diagram (indicated by arrow 101) is shown according to some embodiments. Arrow 101 indicates the possible path for the optical signal to enter the optical engine 150, be received and detected by the photodetector die 50, and then be transmitted out of the optical engine 150. In some cases, the optical signal may be transmitted in either direction along the optical path, not just in the direction indicated by arrow 101.

[0061] Optical signals can be transmitted from optical fibers (not shown separately) to optical engine 150. The optical signal passes through lens 38A, support 36, and dielectric material 34 to grating coupler 16A within PIC 40. Grating coupler 16A receives the optical signal and couples it to silicon waveguide 15A. The optical signal then evanescently couples from silicon waveguide 15A to waveguide 42A. The optical signal then evanescently couples from waveguide 42A to photodetector die 50. Photodetector die 50 detects the optical signal and generates a corresponding electrical signal. After detection by photodetector die 50, the optical signal can evanescently couple to waveguide 42B. The optical signal can then evanescently couple to waveguide 15B, and then evanescently couple to grating coupler 16B. Grating coupler 16B guides the optical signal upwards, through dielectric material 34 and support 36 to lens 38B. The optical signal can then be coupled to an external optical component, such as an optical fiber, via lens 38B. In this way, the technique described herein allows for the incorporation of a high-speed photodetector into the optical engine, thus ensuring high-bandwidth optical communication.

[0062] In some embodiments, the optical signal can be split such that a portion of the optical signal is received by the photodetector die 50 and another portion is transmitted out of the photodetector die 50 (e.g., into waveguide 42B). In some embodiments, the optical signal can be split before a portion of the optical signal enters the photodetector die 50. In other embodiments, the optical signal is transmitted to an optical modulator within the optical engine 150 before being transmitted to the photodetector die 50.

[0063] Figure 13 An optical engine 200 according to some embodiments is shown. The optical engine 200 is similar to... Figure 12 The optical engine 150 in the example differs from the optical engine 200 in that it uses additional waveguides 226A-B and dual grating couplers 216A-B to transmit optical signals. Figure 13 A simplified optical path diagram (indicated by arrow 101) is shown according to some embodiments. Arrow 101 indicates the possible path for the optical signal to enter the optical engine 200, be received and detected by the photodetector die 50, and then be transmitted out of the optical engine 200.

[0064] Waveguides 226A-B can be similar to the waveguides previously described for photonic component 26 (see [link]). Figure 3For example, waveguide 226A-B can be a silicon nitride strip waveguide with a thickness of approximately 400 nm; however, other waveguides are also possible. Waveguide 226A-B is optically coupled to the underlying silicon waveguide 15A-B via, for example, evanescent optical coupling. The dual grating coupler 216A-B includes a lower grating coupler component 214A-B formed of a photonic layer 14, similar to the previously described grating coupler 16. The dual grating coupler 216A-B also includes an upper grating coupler component 212A-B formed of the same material as waveguide 226A-B. For example, waveguide 226A-B and upper grating coupler component 212A-B can be formed by depositing a material layer and then patterning the material layer. The material layer can be, for example, silicon nitride; however, other materials are also possible. The lower grating coupler component 214A-B and the upper grating coupler component 212A-B can be formed of different materials. In this manner, dual grating coupler 216A comprises a lower grating coupler component 214A and an upper grating coupler component 212A, and dual grating coupler 216B comprises a lower grating coupler component 214B and an upper grating coupler component 212B. Dual grating coupler 216A is optically coupled to waveguide 226A, and dual grating coupler 216B is optically coupled to waveguide 226B. Other numbers or configurations of waveguide 226 and / or dual grating couplers 216 are possible.

[0065] Optical signals can be transmitted from optical fibers (not shown separately) to optical engine 200. The optical signal passes through lens 38A, support 36, and dielectric material 34 to a dual grating coupler 216A within PIC 40. Dual grating coupler 216A receives the optical signal and couples it to waveguide 226A. The optical signal then evanescently couples from waveguide 226A to silicon waveguide 15A. The optical signal evanescently couples from silicon waveguide 15A to waveguide 42A, and from waveguide 42A to photodetector die 50. Photodetector die 50 detects the optical signal and generates a corresponding electrical signal. After detection by photodetector die 50, the optical signal can evanescently couple to waveguide 42B. The optical signal can evanescently couple to waveguide 15B, and then evanescently couple to waveguide 226B. The optical signal is coupled from waveguide 226B to a dual grating coupler 216B. The grating coupler 216B guides the optical signal upwards, through dielectric material 34 and support 36, to lens 38B. The optical signal can then be coupled through lens 38B to external optical components, such as optical fibers. In this way, the technique described herein allows for the incorporation of high-speed photodetectors into the optical engine, thus ensuring high-bandwidth optical communication.

[0066] Figure 14 An optical engine 250 according to some embodiments is shown. The optical engine 250 is similar to... Figure 13The optical engine 200 differs from the optical engine 250 in that it uses end-face couplers 252A-B to transmit optical signals into and out of the optical engine 250. End-face couplers 252A-B are optically coupled to waveguides 226A-B. For example, end-face coupler 252A is optically coupled to waveguide 226A, and end-face coupler 252B is optically coupled to waveguide 226B. Figure 14 A simplified optical path diagram (indicated by arrow 101) is shown according to some embodiments. Arrow 101 indicates the possible path of the optical signal entering the optical engine 250, being received and detected by the photodetector die 50, and then being transmitted out of the optical engine 250.

[0067] Optical signals can be transmitted from an optical fiber (not shown separately) to an optical engine 250, which is attached to a sidewall of the optical engine 250 near an end-face coupler 252A. The end-face coupler 252A receives the optical signal and couples it into waveguide 226A. The optical signal then effervescently couples from waveguide 226A into silicon waveguide 15A. The optical signal effervescently couples from silicon waveguide 15A into waveguide 42A, and from waveguide 42A into a photodetector die 50. The photodetector die 50 detects the optical signal and generates a corresponding electrical signal. After detection by the photodetector die 50, the optical signal can effervescently couple into waveguide 42B. The optical signal can effervescently couple into waveguide 15B, and then effervescently couple into waveguide 226B. The optical signal is then coupled from waveguide 226B to the end-face coupler 252B. The optical signal can then be coupled to an external optical component, such as an optical fiber, via the end-face coupler 252B. In this way, the technique described herein allows for the incorporation of a high-speed photodetector into the optical engine, thus ensuring high-bandwidth optical communication.

[0068] Figure 15 and Figure 16 The intermediate stages in forming an optical engine 500 according to some embodiments are shown. The optical engine 500 is similar to... Figure 11 The optical engine 100 differs from the optical engine 500 in that it includes a modulator die 70 instead of a photodetector die 50. The optical engine 500 can be formed using some materials and process steps similar to those used in the optical engine 100 described previously, and therefore, some details will not be repeated.

[0069] Figure 15 A modulator die 70 prior to being attached to a PIC 40 is shown according to some embodiments. The PIC 40 may be similar to the previously described PIC 40. Additionally, an electron die 30 and a support member 36 may be formed above the PIC 40, similar to the previously described structure.

[0070] In some embodiments, the modulator die 70 includes a bonding layer 72. The bonding layer 72 includes a material suitable for direct bonding to the dielectric layer 44. For example, in some embodiments, the bonding layer 72 includes silicon oxide, indium phosphide, etc. The bonding layer 72 may include multiple layers, at least the outermost layer (e.g., the bottom layer) being a material suitable for direct bonding. For example, the bonding layer 72 may include a cladding layer, etc. The bonding layer 72 covers the modulator 74, which is configured to receive an optical signal or optical power and modulate the optical signal or optical power based on the received electrical signal. The modulator 74 can be any suitable optical modulator, such as a Mach-Zehnder modulator, a Michelson modulator, a phase modulator, etc. Furthermore, the modulator 74 can be an electro-optic modulator, a thermo-optic modulator, etc. For example, in some embodiments, the modulator 74 can be a thin-film lithium niobate (TFLN) modulator, etc.; however, other modulators are also possible. In some cases, using a TFLN modulator as the modulator 74 allows for a thinner modulator die 70. In some embodiments, modulator 74 includes a waveguide (not separately labeled), and modulator 74 is configured to detect or respond to an optical signal or optical power within the waveguide. For example, in some embodiments, the waveguide may be a lithium niobate ridge waveguide with a thickness of about 600 nm; however, other materials or thicknesses are also possible. In some embodiments, modulator die 70 includes a plurality of modulators 74. Modulators 74 may be formed on a substrate 73, which may include a dielectric material, a semiconductor material, and / or other suitable materials.

[0071] The modulator die 70 also includes a conductive component 76 that provides electrical connections and electrical operation for the modulator die 70. In some embodiments, the modulator die 70 has a thickness ranging from about 2 μm to about 4 μm; however, other thicknesses are also possible. The modulator die 70 may include integrated circuits, electrical interconnects, or... Figure 15 Other suitable structures are not shown. Accordingly, the modulator die 70 shown is a representative example, and other configurations or structures are also possible. In some cases, in addition to the modulator 74, the modulator die 70 may also include photonic components.

[0072] Figure 16A modulator die 70 after being bonded to a PIC 40 according to some embodiments is shown. Following bonding, additional processing is performed to form an optical engine 300. In some embodiments, the modulator die 70 is bonded to the PIC 40 using direct bonding, similar to the photodetector die 50. The modulator die 70 can be bonded to the PIC 40 using a dielectric-to-dielectric bonding process. For example, the bonding layer 72 of the modulator die 70 can be bonded to the dielectric layer 44 of the PIC 40. Similar to the photodetector die 50, any suitable combination of baking, annealing, pressing, or other processes can be used to bond the modulator die 70 to the PIC 40. All such processes are intended to be included within the scope of this embodiment.

[0073] In some embodiments, modulator die 70 may be aligned with waveguide 42 such that modulator die 70 is optically coupled to waveguide 42. For example, modulator die 70 may overlap with waveguide 42 such that waveguide 42 is evanescently coupled to modulator 74 of modulator die 70. In this way, optical signals and / or optical power can be transmitted between PIC 40 and modulator die 70. As described herein, using direct bonding to bond modulator die 70 to PIC 40 can allow for improved optical coupling between modulator die 70 and PIC 40 and can allow for thinner optical engines. In some embodiments, one or more modulator dies 70 may be bonded to PIC 40 and optically coupled to one or more waveguides 42.

[0074] Additional process steps can be performed, which can be similar to those previously performed on [the target]. Figure 10 The described process steps include, for example, depositing a dielectric material 62 over the modulator die 70, and depositing an optional dielectric layer 63 over the dielectric material 62 and the modulator die 70. In some embodiments, an interconnect structure 60 may be formed over the dielectric layer 63. In some embodiments, the interconnect structure 60 includes one or more dielectric layers 67 (not shown separately), in which one or more conductive members 65 are formed. Vias 64 may be formed, electrically connecting the interconnect structure 60, the modulator die 70, and / or the interconnect structure 20. According to some embodiments, conductive connectors 66 may be formed on the interconnect structure 60.

[0075] Figure 17 An optical engine 350 according to some embodiments is shown. The optical engine 350 is similar to... Figure 16 Optical engine 300 differs from optical engine 150 in that it includes additional waveguides and grating couplers. Optical engine 350 can be similar to optical engine 150, except that it uses modulator die 70 instead of photodetector die 50. For clarity, Figure 17 Some components may not be shown in the text, including... Figure 16 Some of the components shown. Figure 17 A simplified optical path diagram (indicated by arrow 101) is shown according to some embodiments. Arrow 101 indicates a possible path for an optical signal or power to enter the optical engine 350, be received and modulated by the modulator die 70, and then be transmitted out of the optical engine 350. In some cases, the optical signal may be transmitted in either direction along the optical path, not just in the direction indicated by arrow 101.

[0076] Optical signals can be transmitted from optical fibers (not shown separately) to optical engine 350. The optical signal passes through lens 38A, support 36, and dielectric material 34 to grating coupler 16A within PIC 40. Grating coupler 16A receives the optical signal and couples it to silicon waveguide 15A. The optical signal then evanescently couples from silicon waveguide 15A to waveguide 42A. The optical signal then evanescently couples from waveguide 42A to modulator die 70. Modulator die 70 receives electrical signals and modulates the optical signal based on the electrical signals. The modulated optical signal can then evanescently couple from modulator die 70 to waveguide 42B. The optical signal can then evanescently couple to waveguide 15B and then evanescently couple to grating coupler 16B. Grating coupler 16B guides the optical signal upwards, through dielectric material 34 and support 36, to lens 38B. The optical signal can then be coupled to an external optical component, such as an optical fiber, via lens 38B. In this way, the technique described herein allows for the incorporation of a high-speed modulator into the optical engine, thus ensuring high-bandwidth optical communication.

[0077] In some embodiments, the optical signal can be split such that a portion of the optical signal is received by the modulator die 70 and another portion is transmitted out of the modulator die 70 (e.g., into waveguide 42B). In some embodiments, the optical signal can be split before a portion of the optical signal enters the modulator die 70. In other embodiments, after the optical signal is transmitted to the modulator die 70, it is transmitted to a photodetector within the optical engine 350.

[0078] Figure 18 An optical engine 400 according to some embodiments is shown. The optical engine 400 is similar to... Figure 17 The optical engine 400 differs from the optical engine 350 in that it uses additional waveguides 226A-B and dual grating couplers 216A-B to transmit optical signals. The optical engine 400 can be similar to... Figure 13 The optical engine 200 differs in that it uses a modulator die 70 instead of a photodetector die 50. For example, waveguides 226A-B and dual grating couplers 216A-B can be similar to those previously used for... Figure 13 Described waveguides and dual-grating couplers. Figure 18A simplified optical path diagram (indicated by arrow 101) is shown according to some embodiments. Arrow 101 indicates the possible path for an optical signal or optical power to enter the optical engine 400, be received and modulated by the modulator die 70, and then be transmitted out of the optical engine 400.

[0079] Optical signals can be transmitted from optical fibers (not shown separately) to optical engine 400. The optical signals pass through lens 38A, support 36, and dielectric material 34 to a dual grating coupler 216A within PIC 40. Dual grating coupler 216A receives the optical signal and couples it to waveguide 226A. The optical signal then evanescently couples from waveguide 226A to silicon waveguide 15A. The optical signal evanescently couples from silicon waveguide 15A to waveguide 42A, and from waveguide 42A to modulator die 70. Modulator die 70 receives electrical signals and modulates the optical signal based on the electrical signals. The modulated optical signal can evanescently couple from modulator die 70 to waveguide 42B. The optical signal can evanescently couple from waveguide 42B to waveguide 15B, and then evanescently couple to waveguide 226B. The optical signal is coupled from waveguide 226B to a dual grating coupler 216B. The grating coupler 216B guides the optical signal upwards, through dielectric material 34 and support 36, to lens 38B. The optical signal can then be coupled through lens 38B to external optical components, such as optical fibers. In this way, the technique described herein allows for the incorporation of a high-speed modulator into the optical engine, thus ensuring high-bandwidth optical communication.

[0080] Figure 19 An optical engine 450 according to some embodiments is shown. The optical engine 450 is similar to... Figure 18 The optical engine 400 differs from the optical engine 450 in that it uses end-face couplers 252A-B to transmit optical signals into and out of the optical engine 450. The optical engine 450 can be similar to... Figure 14 The optical engine 250 differs in that it uses a modulator die 70 instead of a photodetector die 50. For example, end coupler 252A is optically coupled to waveguide 226A, and end coupler 252B is optically coupled to waveguide 226B. Figure 19 A simplified optical path diagram according to some embodiments is shown (indicated by arrow 101). Arrow 101 indicates the possible path for an optical signal or optical power to enter the optical engine 450, be received and modulated by the modulator die 70, and then be transmitted out of the optical engine 450.

[0081] An optical signal can be transmitted from an optical fiber (not shown separately) to an optical engine 450, which is attached to a sidewall of the optical engine 450 near an end-face coupler 252A. The end-face coupler 252A receives the optical signal and couples it into waveguide 226A. The optical signal then evanescently couples from waveguide 226A into silicon waveguide 15A. The optical signal evanescently couples from silicon waveguide 15A into waveguide 42A, and from waveguide 42A into modulator die 70. Modulator die 70 receives an electrical signal and modulates the optical signal based on the electrical signal. The modulated optical signal can evanescently couple from modulator die 70 into waveguide 42B. The optical signal can evanescently couple into waveguide 15B, and then evanescently couple into waveguide 226B. The optical signal is then coupled from waveguide 226B to end-face coupler 252B. The optical signal can then be coupled to an external optical component, such as an optical fiber, via the end-face coupler 252B. In this way, the technique described herein allows for the incorporation of a high-speed modulator into the optical engine, thus ensuring high-bandwidth optical communication.

[0082] In some embodiments, the optical engine may include multiple photonic dies, such as both a photodetector die 50 and a modulator die 70. For example, Figure 20 An optical engine 500 according to some embodiments is shown, comprising both a photodetector die 50 and a modulator die 70. In this way, both high-speed optical modulation and high-speed optical detection can be achieved in the optical engine. The photodetector die 50 and modulator die 70 can be similar to those previously described, and the optical engine 500 can be similar to other previously described optical engines, except that it includes both the photodetector die 50 and the modulator die 70. For example, the optical engine 500 includes a lens 38A, a grating coupler 16A, waveguides 15A / 26A / 42A, and an electron die 30A associated with the modulator die 70, and includes a lens 38B, a grating coupler 16B, waveguides 15B / 26B / 42B, and an electron die 30B associated with the photodetector die 50. The electron die 30A is electrically connected to the modulator die 70, and the electron die 30B is electrically connected to the photodetector die 50. The optical engine 500 can be formed using materials or techniques similar to those previously described. For example, a direct bonding technique can be used to bond the photodetector die 50 and the modulator die 70 to the PIC 40. In some embodiments, a waveguide can be coupled to the photodetector die 50 and the modulator die 70 to allow optical communication between them. In some embodiments, a multiplexer or demultiplexer (not shown) can be incorporated into the optical engine 500 to facilitate optical communication within the optical engine 500. Arrow 101 indicates a possible path for an optical signal or optical power to enter or leave the optical engine 500. Figure 20The optical engine 500 shown is an illustrative example, and other configurations or arrangements are possible.

[0083] Figure 21 A simplified top view of an optical engine 550 according to some embodiments is shown. The optical engine 550 can be similar to the optical engine 500, except that it includes a plurality of photodetector dies 50 and a plurality of modulator dies 70. In the optical engine 550, each photodetector die 50 has an associated lens 38B, and each modulator die 70 has an associated lens 38A. Lenses 38A-B, photodetector dies 50, and modulator dies 70 can be arranged in an array or in any suitable arrangement. In some cases, the photodetector dies 50 and modulator dies 70 may each have an associated electronic die 30 (not shown). In some cases, the photodetector dies 50 and modulator dies 70 can be optically connected via waveguides (not shown). In this way, the optical engine can facilitate high-speed optical communication by using a plurality of photodetector dies 50 and a plurality of modulator dies 70. Figure 21 The optical engine 550 shown is an illustrative example, and other configurations, arrangements, or numbers of components are also possible.

[0084] Figure 22 An optical engine 600 according to some embodiments is shown. The optical engine 600 is similar to... Figure 17 The optical engine 600 differs from the optical engine 350 in that it includes both a modulator die 70 and a photodetector die 50. In some cases, the optical engine 600 can be similar to... Figure 20 The optical engine is 500. For clarity, Figure 22 Some components may not be shown. The optical engine 600 may be formed using materials or techniques similar to those previously described. For example, a direct bonding technique may be used to bond the photodetector die 50 and the modulator die 70 to the PIC 40. In some embodiments, a waveguide 42C may be coupled to the photodetector die 50 and the modulator die 70, allowing optical communication between them. In some embodiments, a multiplexer or demultiplexer (not shown) may be incorporated into the optical engine 600 to facilitate optical communication within the optical engine 600. Figure 22 A simplified optical path diagram (indicated by arrow 101) is shown according to some embodiments. Arrow 101 indicates a possible path for an optical signal or optical power to enter the optical engine 600, be modulated by the modulator die 70 and / or be detected by the photodetector die 50, and then be transmitted out of the optical engine 600. In some cases, the optical signal may be transmitted in either direction along the optical path, not just in the direction indicated by arrow 101. Figure 22The optical engine 600 shown is an illustrative example, and other configurations or arrangements are possible.

[0085] Optical signals can be transmitted from optical fibers (not shown separately) to optical engine 600. The optical signal passes through lens 38A, support 36, and dielectric material 34 to grating coupler 16A within PIC 40. Grating coupler 16A receives the optical signal and couples it to silicon waveguide 15A. The optical signal is then evanescently coupled from silicon waveguide 15A to waveguide 42A. The optical signal is then evanescently coupled from waveguide 42A to modulator die 70. Modulator die 70 receives electrical signals and modulates the optical signal based on the electrical signals. The modulated optical signal can then evanescently couple from modulator die 70 to waveguide 42C. The optical signal is then evanescently coupled from waveguide 42C to photodetector die 50. Photodetector die 50 detects the optical signal and generates a corresponding electrical signal. After detection by photodetector die 50, the optical signal can be evanescently coupled to waveguide 42B. The optical signal can then be evanescently coupled into waveguide 15B, and then evanescently coupled into grating coupler 16B. Grating coupler 16B guides the optical signal upwards, through dielectric material 34 and support 36 to lens 38B. The optical signal can then be coupled to external optical components, such as optical fibers, via lens 38B. In this way, the technique described herein allows for the incorporation of high-speed modulators and high-speed photodetectors into the optical engine, thus ensuring high-bandwidth optical communication.

[0086] The embodiments disclosed herein have several advantageous features. By directly bonding a photonic die to an optical engine formed from a photonic integrated circuit (PIC), it is possible to use materials that would otherwise be difficult or costly to form in the photonic assembly, for example, by processing materials during the formation of the optical engine or by bonding wafer-level structures to the PIC. The photonic assembly may include, for example, a high-speed photodetector or a modulator. As a non-limiting example, a photodetector using group III-V materials can be formed in a photodetector chip, and a modulator using thin-film lithium niobate (TFLN) can be formed in a modulator die. In this way, high data rates, such as data rates greater than about 400 Gbps, can be achieved in the optical engine. In addition, direct bonding of the photonic die allows for thinner photonic dies, which ensures more efficient optical coupling to the PIC and / or a thinner optical engine. The photonic die can be coupled to a waveguide within the PIC to allow high-speed optical communication within the optical engine. In this way, the photonic die can be heterogeneously integrated into the optical engine, and the optical engine can be formed at a reduced cost and with higher data rates.

[0087] In embodiments of this disclosure, a method includes: forming a photonic integrated circuit comprising: a first waveguide; a second waveguide located above the first waveguide, wherein the second waveguide is optically coupled to the first waveguide; a first external coupler optically coupled to the second waveguide; and a first interconnect structure; attaching an electron die to a first side of the photonic integrated circuit; directly bonding the first photonic die to a second side of the photonic integrated circuit, wherein after direct bonding, the first photonic die is optically coupled to the first waveguide; and forming a second interconnect structure above the first photonic die and the photonic integrated circuit. In embodiments, the first photonic die comprises a lithium niobate modulator. In embodiments, the first photonic die comprises a group III-V photodetector. In embodiments, direct bonding comprises a dielectric-to-dielectric bonding process. In embodiments, the method includes forming a lens above the first side of the photonic integrated circuit, wherein the lens is optically coupled to the first external coupler. In embodiments, the first external coupler is a grating coupler. In embodiments, the first external coupler is an end-face coupler. In one embodiment, the method includes directly bonding a second photonic die to a second side of a photonic integrated circuit, wherein after direct bonding, the second photonic die is optically coupled to a first waveguide.

[0088] In embodiments of this disclosure, a method includes: patterning a first photonic layer to form a first waveguide, wherein the first photonic layer is located on a first side of a first insulating layer; forming a first interconnect structure over the first waveguide; bonding a first electron die to the first interconnect structure; patterning a second photonic layer to form a second waveguide, wherein the second photonic layer is located on a second side of the first insulating layer, wherein the second waveguide overlaps with the first waveguide; depositing a second insulating layer over the second waveguide; bonding a photonic die to the second insulating layer, wherein the photonic die overlaps with the second waveguide; and forming a second interconnect structure over the photonic die and over the second insulating layer, wherein the second interconnect structure is electrically connected to the photonic die and electrically connected to the first interconnect structure. In embodiments, the method includes depositing a second insulating layer over the first waveguide; and forming a third waveguide on the second insulating layer, wherein the third waveguide overlaps with the first waveguide. In embodiments, the method includes forming a dual grating coupler adjacent to the third waveguide, the dual grating coupler being optically coupled to the third waveguide. In embodiments, the first photonic layer and the second photonic layer are made of different materials. In one embodiment, a fusion bonding process is used to bond the photonic die to a second insulating layer. In another embodiment, the method includes patterning the second photonic layer to form a fourth waveguide, wherein the photonic die overlaps with the fourth waveguide. In yet another embodiment, the photonic die includes a fifth waveguide.

[0089] In embodiments of this disclosure, the optical device includes: a first interconnect structure; a photonic device located on the first interconnect structure, wherein the photonic device is in physical and electrical contact with the first interconnect structure; a first waveguide located above the photonic device, wherein the first waveguide is coupled to the photonic device; a second waveguide located above the first waveguide, wherein the second waveguide is coupled to the first waveguide; a grating coupler adjacent to the second waveguide, wherein the grating coupler is optically coupled to the second waveguide; a second interconnect structure located above the second waveguide; and an electron die bonded to the second interconnect structure. In embodiments, the photonic device includes a thin-film lithium niobate modulator. In embodiments, at least one of the first waveguides is a silicon nitride waveguide. In embodiments, at least one of the second waveguides is a silicon waveguide. In embodiments, the optical device includes a conductive via extending from the first interconnect structure to the second interconnect structure.

[0090] According to one aspect of this application, a method for forming an optical device is provided, the method comprising: forming a photonic integrated circuit, the photonic integrated circuit including: a first waveguide; a second waveguide located above the first waveguide, wherein the second waveguide is optically coupled to the first waveguide; a first external coupler optically coupled to the second waveguide; and a first interconnect structure; attaching an electron die to a first side of the photonic integrated circuit; directly bonding the first photonic die to a second side of the photonic integrated circuit, wherein, after direct bonding, the first photonic die is optically coupled to the first waveguide; and forming a second interconnect structure above the first photonic die and the photonic integrated circuit. In some embodiments, the first photonic die includes a lithium niobate modulator. In some embodiments, the first photonic die includes a III-V group photodetector. In some embodiments, direct bonding includes a dielectric-to-dielectric bonding process. In some embodiments, the method of forming the optical device further includes forming a lens above the first side of the photonic integrated circuit, wherein the lens is optically coupled to the first external coupler. In some embodiments, the first external coupler is a grating coupler. In some embodiments, the first external coupler is an end-face coupler. In some embodiments, the method of forming an optical device further includes directly bonding a second photonic die to a second side of a photonic integrated circuit, wherein, after direct bonding, the second photonic die is optically coupled to a first waveguide.

[0091] According to another aspect of this application, a method for forming an optical device is provided, the method comprising: patterning a first photonic layer to form a first waveguide, wherein the first photonic layer is located on a first side of a first insulating layer; forming a first interconnect structure over the first waveguide; bonding a first electron die to the first interconnect structure; patterning a second photonic layer to form a second waveguide, wherein the second photonic layer is located on a second side of the first insulating layer, wherein the second waveguide overlaps with the first waveguide; depositing a second insulating layer over the second waveguide; bonding a photonic die to the second insulating layer, wherein the photonic die overlaps with the second waveguide; and forming a second interconnect structure over the photonic die and the second insulating layer, wherein the second interconnect structure is electrically connected to the photonic die and electrically connected to the first interconnect structure. In some embodiments, the method for forming the optical device further comprises: depositing a second insulating layer over the first waveguide; and forming a third waveguide on the second insulating layer, wherein the third waveguide overlaps with the first waveguide. In some embodiments, the method for forming the optical device further comprises forming a dual grating coupler adjacent to the third waveguide, the dual grating coupler being optically coupled to the third waveguide. In some embodiments, the first photonic layer and the second photonic layer are made of different materials. In some embodiments, a fusion bonding process is used to bond the photonic die to a second insulating layer. In some embodiments, the method of forming the optical device further includes patterning the second photonic layer to form a fourth waveguide, wherein the photonic die overlaps with the fourth waveguide. In some embodiments, the photonic die includes a fifth waveguide.

[0092] According to another aspect of this application, an optical device is provided, comprising: a first interconnect structure; a photonic device located on the first interconnect structure, wherein the photonic device is in physical and electrical contact with the first interconnect structure; a plurality of first waveguides located above the photonic device, wherein the plurality of first waveguides are coupled to the photonic device; a plurality of second waveguides located above the plurality of first waveguides, wherein the plurality of second waveguides are coupled to the plurality of first waveguides; a plurality of grating couplers adjacent to the plurality of second waveguides, wherein the plurality of grating couplers are optically coupled to the plurality of second waveguides; a second interconnect structure located above the plurality of second waveguides; and an electron die bonded to the second interconnect structure. In some embodiments, the photonic device includes a thin-film lithium niobate modulator. In some embodiments, at least one of the plurality of first waveguides is a silicon nitride waveguide. In some embodiments, at least one of the plurality of second waveguides is a silicon waveguide. In some embodiments, the optical device further includes a conductive via extending from the first interconnect structure to the second interconnect structure.

[0093] The foregoing has outlined features of several embodiments to enable those skilled in the art to better understand aspects of this disclosure. Those skilled in the art should understand that they can readily use this disclosure as a basis to design or modify other operations and structures for implementing the same purposes and / or achieving the same advantages as the embodiments described herein. Those skilled in the art should also recognize that such equivalent constructions do not depart from the spirit and scope of this disclosure, and that various changes, substitutions, and alterations can be made to them herein without departing from the spirit and scope of this disclosure.

Claims

1. A method for forming an optical device, comprising: Forming a photonic integrated circuit, the photonic integrated circuit comprising: First waveguide; A second waveguide is located above the first waveguide, wherein the second waveguide is optically coupled to the first waveguide; A first external coupler optically couples to the second waveguide; and First interconnect structure; The electron tube die is attached to the first side of the photonic integrated circuit; A first photonic die is directly bonded to the second side of the photonic integrated circuit, wherein, after the direct bonding, the first photonic die is optically coupled to the first waveguide; and A second interconnect structure is formed above the first photonic die and the photonic integrated circuit.

2. The method according to claim 1, wherein, The photonic chip includes a lithium niobate modulator.

3. The method according to claim 1, wherein, The photonic chip includes a III-V group photodetector.

4. The method according to claim 1, wherein, The direct bonding includes a dielectric-to-dielectric bonding process.

5. The method of claim 1, further comprising forming a lens over the first side of the photonic integrated circuit, wherein, The lens is optically coupled to the first external coupler.

6. The method according to claim 1, wherein, The first external coupler is a grating coupler.

7. The method according to claim 1, wherein, The first external coupler is an end-face coupler.

8. The method of claim 1, further comprising directly bonding the second photonic die to the second side of the photonic integrated circuit, wherein, After the direct bonding, the second photonic die is optically coupled to the first waveguide.

9. A method for forming an optical device, comprising: The first photonic layer is patterned to form a first waveguide, wherein the first photonic layer is located on a first side of the first insulating layer; A first interconnect structure is formed above the first waveguide; The first electron die is bonded to the first interconnect structure; A second photonic layer is patterned to form a second waveguide, wherein the second photonic layer is located on a second side of the first insulating layer, and wherein the second waveguide overlaps with the first waveguide; A second insulating layer is deposited above the second waveguide; The photonic die is bonded to the second insulating layer, wherein the photonic die overlaps with the second waveguide; and A second interconnect structure is formed above the photonic die and above the second insulating layer, wherein the second interconnect structure is electrically connected to the photonic die and electrically connected to the first interconnect structure.

10. An optical device, comprising: First interconnect structure; A photonic device is located on the first interconnect structure, wherein the photonic device is in physical and electrical contact with the first interconnect structure; A plurality of first waveguides are located above the photonic device, wherein the plurality of first waveguides are coupled to the photonic device; A plurality of second waveguides are located above the plurality of first waveguides, wherein the plurality of second waveguides are coupled to the plurality of first waveguides; Multiple grating couplers are adjacent to the multiple second waveguides, wherein the multiple grating couplers are optically coupled to the multiple second waveguides; A second interconnection structure is located above the plurality of second waveguides; and The electron tube die is bonded to the second interconnect structure.

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