Optical device and forming method thereof

Abstract

Described herein is a method of forming an optical device and the optical device itself in which a modulation device is bonded to a photonic integrated circuit. The photonic integrated circuit has a modulation device that can be used to modulate an optical signal from the photonic integrated circuit, and the modulation device is formed using lithium niobate.

Description

Technical Field

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

[0002] Electrical signal processing is a signal transmission and processing technology. In recent years, optical signal processing has been used in an increasing number of applications, especially for signal transmission in fiber optic applications.

[0003] Optical devices can provide optical signal coupling from optical fiber to optical waveguide for use in optical signal and processing systems. The efficiency of optical coupling and modulation has gradually improved, making the design of individual couplers and modulators crucial for advancing optical signal transmission. However, improvements are still needed. Summary of the Invention

[0004] According to one aspect of the embodiments of this application, a method for forming an optical device is provided, the method comprising: forming a photonic integrated circuit including a first optical component, the first optical component including a waveguide connected to a coupler; bonding a first semiconductor device to the photonic integrated circuit; and bonding a modulation device to the photonic integrated circuit, the modulation device including a modulation device having lithium niobate, wherein, after bonding the modulation device, the modulation device is optically coupled to the waveguide.

[0005] According to another aspect of the present application, a method for forming an optical device is provided, the method comprising: bonding a first semiconductor device to a first side of a photonic integrated circuit, the photonic integrated circuit including a coupler and a waveguide; and bonding a modulation device to the photonic integrated circuit on the opposite side of the first semiconductor device, the modulation device including a lithium niobate film.

[0006] According to another aspect of the embodiments of this application, an optical device is provided, comprising: a modulation device including a lithium niobate film; a first waveguide located above the modulation device and optically connected to the modulation device; a photonic integrated circuit bonded above the modulation device, the first waveguide being located between the modulation device and the photonic integrated circuit, the photonic integrated circuit comprising: a second waveguide optically connected to the first waveguide; a coupler optically connected to the second waveguide; and an electronic integrated circuit bonded above the photonic integrated circuit. Attached Figure Description

[0007] The various aspects of this disclosure are best understood from the following detailed description when read in conjunction with the accompanying drawings. It should be emphasized that, in accordance with standard industry practice, the various parts are not drawn to scale and are for illustrative purposes only. In fact, the dimensions of the various parts may be arbitrarily increased or decreased for clarity of discussion.

[0008] Figure 1 A substrate used in a method for forming a photonic platform according to some embodiments is shown.

[0009] Figure 2 The diagram illustrates the formation of a dielectric layer over a substrate according to some embodiments.

[0010] Figure 3 The formation of an optical component according to some embodiments is shown.

[0011] Figure 4 The attachment of a first semiconductor device according to some embodiments is shown.

[0012] Figure 5 The removal of the substrate is shown according to some embodiments.

[0013] Figures 6A-6C A modulation device according to some embodiments is shown.

[0014] Figure 7 The junction of a modulation device according to some embodiments is shown.

[0015] Figure 8 The formation of a metallization layer according to some embodiments is illustrated.

[0016] Figure 9 A first simplified optical path is shown according to some embodiments.

[0017] Figure 10 A second simplified optical path is shown according to some embodiments.

[0018] Figure 11 A third simplified optical path is shown according to some embodiments.

[0019] Figures 12A-12B The formation of a reflector according to some embodiments is shown. Detailed Implementation

[0020] The following disclosure provides numerous different embodiments or examples for implementing various features of this disclosure. Specific embodiments or 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 can include embodiments where the first and second components are in direct contact, and can also include embodiments where an additional component can be formed between the first and second components, such that the first and second components are not in direct contact. Furthermore, reference numerals and / or letters may be repeated in various examples. This repetition is for simplicity and clarity and does not in itself indicate a relationship between the various embodiments and / or configurations discussed.

[0021] Furthermore, for ease of description, this document may use spacing relation terms such as “below,” “under,” “lower,” “above,” “upper,” etc., 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, spacing relation terms are intended to include 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 spacing relation descriptors used herein may be interpreted accordingly.

[0022] Embodiments will now be described and discussed in which a modulation device is used to provide modulation to a first optical package, and the first optical package is not contaminated by the material within the modulation device die. However, the embodiments presented herein are intended to be illustrative and are not intended to limit the embodiments to the precise descriptions discussed. Rather, the embodiments discussed can be incorporated into a wide variety of implementations, and all such implementations are fully intended to be included within the scope of the embodiments.

[0023] Now for reference Figure 1 The diagram illustrates an initial structure, which includes a first substrate 101 located between a first isolation layer 103 and a second isolation layer 105. Looking first at the first substrate 101, it can be a semiconductor material such as silicon or germanium, a dielectric material such as glass, or any other suitable material that allows for structural support of the overlaid device.

[0024] In one embodiment, the first isolation layer 103 and the second isolation layer 105 may be silicon oxide, silicon nitride, germanium oxide, germanium nitride, combinations thereof, etc., formed using methods such as implantation (e.g., forming a buried oxide (BOX) layer), or deposited on opposite sides of the first substrate 101 using deposition methods such as chemical vapor deposition, atomic layer deposition, physical vapor deposition, etc. However, any suitable materials and manufacturing methods may be used.

[0025] Figure 2 A first dielectric layer 201 and a second dielectric layer 203 are shown deposited over a first isolation layer 103. In one embodiment, the first dielectric layer 201 may be a dielectric material such as silicon nitride, and a deposition method such as chemical vapor deposition, atomic layer deposition, or physical vapor deposition is used. The first dielectric layer 201 may be deposited to approximately [value missing]. to approximately The thickness between, for example, approximately However, any suitable material, process, and thickness can be used.

[0026] If desired, in embodiments where the first dielectric layer 201 is formed of a material that can be used as a core material (e.g., silicon nitride), the first dielectric layer 201 can be further patterned to form a back-side optical device (in) from the material of the first dielectric layer 201 (e.g., silicon nitride). Figure 2 (Represented by a dashed box labeled 205). In some embodiments, the back-side optical assembly 205 may include components such as optical waveguides (e.g., ridge waveguides, rib waveguides, buried trench waveguides, diffused waveguides, etc.), couplers for connection to external signals (e.g., edge couplers, grating couplers, etc.), optical modulation devices (e.g., Mach-Zehnder silicon photonic switches, microelectromechanical switches, microring resonators, etc.), amplifiers, multiplexers, multiplexers, photoelectric converters (e.g., PN junctions), electro-optic converters, lasers, combinations thereof, etc. However, any suitable optical component may be used for one or more back-side optical assemblies 205. In a particular embodiment, at least a portion of the back-side optical assembly 205 may be a waveguide that will be located at the subsequently connected modulation device 600 ( Figure 2 Not shown in the image, but will be referenced below. Figures 6A-6C (As further shown and discussed below) so as to provide optical signal input and output to the modulation device 600.

[0027] In one embodiment, the material of the first dielectric layer 201 can be patterned into the desired shape of one or more back-side optical components 205. In one embodiment, the material of one or more back-side optical components 205 can be patterned using, for example, one or more photolithographic masks and etching processes. However, any suitable method for patterning the material of one or more back-side optical components 205 can be utilized.

[0028] The second dielectric layer 203 can be another dielectric material such as silicon oxide, deposited using methods such as chemical vapor deposition, atomic layer deposition, or physical vapor deposition. The second dielectric layer 203 can be deposited on and around the first dielectric layer 201 and any back-side optical component 205, with a thickness of approximately [missing information]. Peace Treaty Between. However, any suitable material, process, and thickness can be used.

[0029] Figure 3A photonic integrated circuit (PIC) 300 is shown formed on a second dielectric layer 203. In one embodiment, the formation of the PIC 300 can be initiated by initially forming a material (not shown separately) for a first active layer 301 for a first optical component 303. In one embodiment, the material for the first active layer 301 can be a light-transmitting material that can be used as a core material for the desired first optical component 303, such as a semiconductor material like silicon, germanium, silicon-germanium, combinations of these materials, etc., while in other embodiments, the material for the first active region 301 can be a dielectric material, such as silicon nitride, etc., although in other embodiments the material for the first active layer 301 can be a group III-V material or a polymer. In embodiments where the material for the first active layer 301 is deposited, methods such as epitaxial growth, chemical vapor deposition, atomic layer deposition, physical vapor deposition, or combinations thereof can be used to deposit the material for the first active layer 302. However, the material for the first active layer 301 can be formed using any suitable material and manufacturing method.

[0030] Once the material for the first active layer 301 is ready, the material for the first active layer 302 is used to fabricate the first optical component 303 of the first active layer 301. In embodiments, the first optical component 303 of the first active layer 301 may include components such as optical waveguides (e.g., ridge waveguides, rib waveguides, buried trench waveguides, diffused waveguides, etc.), directional couplers, optical modulation devices (e.g., Mach-Zehnder silicon photonic switches, microelectromechanical switches, microring resonators, etc.), amplifiers, multiplexers, multiplexers, photoelectric converters (e.g., PN junctions), electro-optic converters, lasers, combinations thereof, etc. However, any suitable first optical component 303 may be used.

[0031] To begin forming the first active layer 301 of the first optical component 303 from initial material, the material for the first active layer 301 can be patterned into a desired shape for the first optical component 303. In one embodiment, the material for the first active layer 301 can be patterned using, for example, one or more photolithographic masks and etching processes. However, any suitable method for patterning the material for the first active layer 301 can be utilized. For some first optical components 303, the patterning process can be all or at least most of the manufacturing processes used to form these first optical components 303.

[0032] For components that utilize further manufacturing processes, such as Mach-Zehnder silicon photonic switches using resistance heating elements, additional processing can be performed before or after patterning the material used to form the first active layer 301 of the first optical component. For example, implantation processes, additional deposition and patterning processes of different materials (e.g., resistance heating elements, III-V materials for converters), combinations of all these processes, etc., can be used to facilitate further fabrication of various desired first optical components 303. In a particular embodiment, such as... Figure 3 As specifically illustrated, in some embodiments, epitaxial deposition of a semiconductor material 304 (e.g., germanium, for electro / optical signal modulation and conversion) can be performed on a patterned portion of the material of the first active layer 301. In this embodiment, the semiconductor material 304 can be epitaxially grown to aid in the fabrication of a photodiode, for example, for a photoelectric converter. All such fabrication processes and all suitable first optical components 303 can be fabricated, and all such combinations are fully intended to be included within the scope of the embodiments.

[0033] Once the first optical component 303 is formed, a second insulating layer 305 can be deposited to cover the first optical component 303. The second insulating layer 305 can provide additional cladding material. In one embodiment, the second insulating layer 305 can be a dielectric layer that spaces the various components of the first active layer 301 apart from each other and from the overlying structure, and can also serve as another portion of the cladding material surrounding the first optical component 303. In one embodiment, the second insulating layer 305 can be silicon oxide, silicon nitride, germanium oxide, germanium nitride, or combinations thereof, formed using deposition methods such as chemical vapor deposition, atomic layer deposition, physical vapor deposition, etc. Once the material of the second insulating layer 305 has been deposited, it can be planarized using, for example, a chemical mechanical polishing process to planarize the top surface of the second insulating layer 305 (in embodiments where the second insulating layer 305 is intended to completely cover the first optical component 303), or to planarize the second insulating layer 305 with the top surface of the first optical component 303. However, any suitable materials and manufacturing methods can be used.

[0034] Once the first optical component 303 has been fabricated and the second insulating layer 305 has been formed, one or more second optical components 307 can be formed as part of the first metallization layer 309. In some embodiments, the second optical component 307 of the first metallization layer 309 may include components for connection to external signals such as couplers (e.g., edge couplers, grating couplers, etc.), optical waveguides (e.g., ridge waveguides, rib waveguides, buried trench waveguides, diffused waveguides, etc.), optical modulation devices (e.g., Mach-Zehnder silicon photonic switches, microelectromechanical switches, microring resonators, etc.), amplifiers, multiplexers, multiplexers, photoelectric converters (e.g., PN junctions), electro-optic converters, lasers, combinations thereof, etc. However, any suitable optical component can be used for one or more second optical components 307.

[0035] In one embodiment, one or more second optical components 307 may be formed by initially depositing material for one or more second optical components 307. In one embodiment, the material for one or more second optical components 307 may be a dielectric material such as silicon nitride, silicon oxide, or a combination thereof, or a semiconductor material such as silicon deposited using a deposition method such as chemical vapor deposition, atomic layer deposition, physical vapor deposition, etc. However, any suitable material and any suitable deposition method may be used.

[0036] Once the material for one or more second optical components 307 is deposited or otherwise formed, the material can be patterned into the desired shape for one or more third optical components 307. In one embodiment, the material for one or more second optical components 307 can be patterned using, for example, one or more photolithographic masks and etching processes. However, any suitable method for patterning the material for one or more second optical components 307 can be utilized.

[0037] For some of the one or more second optical components 307, such as waveguides or edge couplers, the patterning process can be all or at least most of the manufacturing processes used to form these elements. Furthermore, for components utilizing further manufacturing processes, such as Mach-Zehnder silicon photonic switches utilizing resistance heating elements, additional processing can be performed before or after the material patterning of one or more second optical components 307. For example, implantation processes, additional deposition and patterning processes of different materials, combinations of all these processes, etc., can be used to facilitate the further fabrication of various desired one or more second optical components 307. All such manufacturing processes and all suitable one or more second optical components 307 can be manufactured, and all such combinations are fully intended to be included within the scope of the embodiments.

[0038] Furthermore, while one or more second optical components 307 may be formed to create optical components in a single layer, this is merely illustrative and not intended to limit the embodiments. Instead, one or more second optical components 307 may include multilayer core and cladding materials. In other embodiments, one or more second optical components 307 may be formed to cooperate with portions of the first optical component 303 to form a device such as a dual-layer grating coupler, wherein a first portion of the desired grating coupler is formed as one of the first optical components 303, and a second portion of the desired grating coupler is formed as one of the one or more second optical components 307. Any suitable combination of optical elements in the first optical component 303 and the second optical component 307, or even a single optical element spanning both, is fully intended to be included within the scope of the embodiments.

[0039] The remaining portion of the first metallization layer 309 is formed above and around the second optical component 307. In one embodiment, the first metallization layer 309 is formed to electrically connect the first active layer 301 of the first optical component 303 to a control circuit, to each other, and to subsequently attached devices. Figure 3 Not shown in the image, but will be referenced below. Figure 4 (Further illustrated and described). In one embodiment, the first metallization layer 309 is formed of alternating layers of dielectric (deposited to cover one or more second optical components 307) and conductive material, and can be formed by any suitable process (such as deposition, damascene, dual damascene, etc.). In a particular embodiment, there may be multiple metallization layers for interconnecting the various first optical components 303, but the exact number of first metallization layers 309 depends on the design.

[0040] Once the first metallization layer 309 is fabricated, a first bonding layer 315 is formed on the first metallization layer 309. In one embodiment, the first bonding layer 315 can be used for dielectric-to-dielectric and metal-to-metal bonding. According to some embodiments, the first bonding layer 315 is formed of a first dielectric material 317 such as silicon oxide, silicon nitride, etc. The first dielectric material 317 can be deposited using any suitable method, such as CVD, high-density plasma chemical vapor deposition (HDPCVD), PVD, atomic layer deposition (ALD), etc. However, any suitable material and deposition process can be utilized.

[0041] Once the first dielectric material 317 is formed, a first opening is formed in the first dielectric material 317 to expose the conductive portion of the underlying layer, preparing for the formation of a first bonding pad 319 within the first bonding layer 315. Once the first opening is formed within the first dielectric material 317, a seed layer and plate metal can be used to fill the first opening to form the first bonding pad 319 within the first dielectric material 317. The seed layer can be blanket-deposited on the top surface of the first dielectric material 317, the exposed conductive portion of the underlying layer, and the sidewalls of the opening and the second opening. The seed layer may include a copper layer. Depending on the desired material, the seed layer can be deposited using processes such as sputtering, evaporation, or plasma-enhanced chemical vapor deposition (PECVD). The plate metal can be deposited on the seed layer using an electroplating process (such as electroplating or electroless plating). The metal plate may include copper, copper alloys, etc. The metal plate may be a filler material. A barrier layer (not shown separately) can be blanket-deposited on the top surface of the first dielectric material 317 and the sidewalls of the opening and the second opening prior to the seed layer. The barrier layer may include titanium, titanium nitride, tantalum, tantalum nitride, etc.

[0042] After filling the first opening, a planarization process such as CMP is performed to remove excess portions of the seed layer and board metal, thereby forming a first bonding pad 319 within the first bonding layer 315. In some embodiments, the first bonding pad 319 may also be connected to an underlying conductive portion via bonding pad vias (not shown separately), and the first bonding pad 319 may be connected to the first metallization layer 309 via the underlying conductive portion.

[0043] Furthermore, the first bonding layer 315 may also include one or more third optical components 321 bonded within the first bonding layer 314. In this embodiment, the one or more third optical components 321 may be fabricated using methods and materials similar to those used for the one or more second optical components 307 (as described above), for example by forming waveguides and other structures at least partially through deposition and patterning processes, prior to the deposition of the first dielectric material 317. However, any suitable structure, material, and manufacturing method may be utilized.

[0044] Furthermore, if desired, a path 323 for optical signals can be formed through the layers of the first metallization layer 309 and the first bonding layer 315. In one embodiment, at any desired point in the process of forming the multilayer of the first metallization layer 309 and the first bonding layer 315, material above the coupler (e.g., a grating coupler) can be removed using, for example, one or more masking and etching processes. Once this material is removed, the remaining opening is filled with a dielectric material suitable for facilitating the transmission of optical signals inside and outside the grating coupler. However, in other embodiments, this path may be omitted.

[0045] Figure 4The bonding between the first semiconductor device 401 and the first bonding layer 315 is shown (for clarity). Figure 4 (The structure shown in the figure is simplified). In some embodiments, the first semiconductor device 401 is an electronic integrated circuit (EIC, e.g., a device without optical components) and may have a semiconductor substrate 403, an active device layer 405 having transistors (e.g., gates, source / drain regions, contacts), an overlay interconnect structure 407 (e.g., a back-end fabrication structure), a second bonding layer 409, and an associated second bonding pad 411. In one embodiment, the semiconductor substrate 403 may be similar to the first substrate 101 (e.g., a semiconductor material such as silicon or silicon-germanium), the active device 405 may be a transistor, capacitor, resistor, etc. formed on the semiconductor substrate 403, the interconnect structure 407 may be similar to the first metallization layer 309 (without optical components), the second bonding layer 409 may be similar to the first bonding layer 315, and the second bonding pad 411 may be similar to the first bonding pad 319. However, any suitable device may be used.

[0046] In one embodiment, the first semiconductor device 401 may be configured to work with the photonic integrated circuit 300 to achieve the desired functionality. In some embodiments, the first semiconductor device 401 may be a high-bandwidth memory (HBM) module, xPU, logic die, 3DIC die, CPU, GPU, SoC die, MEMS die, or a combination thereof. Any suitable device with any appropriate functionality may be used, and all such devices are fully intended to be included within the scope of the embodiments.

[0047] In one embodiment, the first semiconductor device 401 and the first bonding layer 315 can be bonded using dielectric-to-dielectric and metal-to-metal bonding processes. In a particular embodiment utilizing dielectric-to-dielectric and metal-to-metal bonding processes, the process can be initiated by activating the surfaces of the second bonding layer 409 and the first bonding layer 315. As an example, activating the top surfaces of the first bonding layer 315 and the second bonding layer 409 can include dry treatment, wet treatment, plasma treatment, exposure to inert gas plasma, exposure to H2, exposure to N2, exposure to O2, or combinations thereof. In embodiments using wet treatment, for example, RCA cleaning can be used. In another embodiment, the activation process can include other types of processing. The activation process facilitates the bonding of the first bonding layer 315 and the second bonding layer 409.

[0048] After the activation process, the first bonding layer 315 and the first semiconductor device 401 can be cleaned using, for example, chemical rinsing, and then the first semiconductor device 402 is aligned and brought into physical contact with the first bonding layer 315. The first bonding layer 315 and the first semiconductor device 401 are then subjected to heat treatment and contact pressure to bond the first bonding layer 315 and the first semiconductor device 401. For example, the first bonding layer 315 and the first semiconductor device 401 may be subjected to pressures of about 200 kPa or less and temperatures between about 25°C and about 250°C to fuse the first bonding layer 315 and the first semiconductor device 401. The first bonding layer 315 and the first semiconductor device 401 may then be subjected to temperatures equal to or higher than the eutectic point of the materials of the first bonding pad 319 and the second bonding pad 411, for example, between about 150°C and about 650°C, to fuse the metals. In this way, the first bonding layer 315 and the first semiconductor device 401 form a dielectric-to-dielectric and metal-to-metal bonding device. In some embodiments, the joined dies are subsequently baked, annealed, pressed, or otherwise treated to strengthen or complete the joint.

[0049] Furthermore, while specific processes for initiating and strengthening the bond 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 these processes are entirely intended to be included within the scope of the embodiments.

[0050] Figure 4 It is also shown that once the first semiconductor device 401 is bonded, a first gap filler material 413 is deposited to fill the space around the first semiconductor device 401 and provide additional support. In one embodiment, the first gap filler material 413 may be a material deposited to fill and overfill the space around the first semiconductor device 401, such as silicon oxide, silicon nitride, silicon oxynitride, combinations of these materials, etc. However, any suitable material and deposition method may be used.

[0051] Figure 4 The attachment of the first support substrate 415 to the first semiconductor device 401 and the first gap filler material 413 is also illustrated. In one embodiment, the first support substrate 415 may be a support material transparent to the wavelength of the light to be used, such as silicon, and may be attached using, for example, a bonding agent (not shown separately). However, in other embodiments, the first support substrate 415 may be bonded to the first semiconductor device 401 and the first gap filler material 413 using, for example, a bonding process. Any suitable method may be used to attach the first support substrate 415.

[0052] In some embodiments, the first support substrate 415 includes a first coupling lens 417, which is positioned to facilitate the connection from, for example, an optical fiber (…). Figure 4 The movement of an optical signal (not shown). In one embodiment, the first coupling lens 417 can be formed by shaping a material (e.g., silicon) of a support substrate using a mask and etching process. However, any suitable process can be utilized.

[0053] Furthermore, if desired, a first anti-reflective coating (ARC) (not shown separately) may be formed on the first coupling lens 417. In one embodiment, the first ARC may be one or more layers of material that helps prevent unwanted reflections when light is focused through the first coupling lens 417. In a particular embodiment, the one or more layers of material may be materials such as silicon oxide, silicon nitride, or combinations thereof, formed using processes such as chemical vapor deposition, atomic layer deposition, physical vapor deposition, oxidation, nitriding, or combinations thereof.

[0054] In a particular embodiment, the first ARC can be formed using a first silicon oxide layer and a first silicon nitride layer formed on the first silicon oxide layer. A second silicon oxide layer and a second silicon nitride layer are deposited on the first silicon oxide layer and the first silicon nitride layer, forming an alternating stack of silicon oxide and silicon nitride. Once all the required layers have been deposited, these layers can be patterned using, for example, photolithography masks and etching processes. However, any suitable combination of materials and processes can be utilized.

[0055] Figure 5 The diagram illustrates the removal of a first substrate 101, a first insulating layer 103, and a second insulating layer 105, thereby exposing a portion of a first dielectric layer 201 and a second dielectric layer 203 surrounding a back-side optical assembly 205. In one embodiment, a planarization process can be used to remove the first substrate 101, the first insulating layer 103, and the second insulating layer 105, such as a chemical mechanical polishing process, a grinding process, one or more etching processes, or a combination of these processes. However, any suitable method can be used to remove the first substrate 101, the first insulating layer 103, and the second insulating layer 105.

[0056] Figures 6A-6B A modulation device 600 is shown, which can be bonded to a first dielectric layer 201 to provide modulation material isolated from the rest of the PIC 300. In one embodiment, the modulation device 600 includes a modulation substrate 601 and an overlying modulator 603. In one embodiment, the modulation substrate 601 may be similar to the first substrate 101, for example, by being a semiconductor material such as silicon.

[0057] Next, consider modulator 603. In some embodiments, modulator 603 is a Mach-Zehnder modulator (MZM), but any suitable modulator may be used. In this embodiment where modulator 603 is a Mach-Zehnder modulator, modulator 603 may include modulation unit 605, cladding material 607, and core material 609. First, consider modulation unit 605. Modulation unit 605 may be a metal resistance heater comprising a metallic material such as copper, aluminum, etc., which can be heated, for example, by resistance heating when current flows through modulation unit 605. In this embodiment, modulation unit 605 may be formed using processes and materials similar to those used for the electrical components of the first metallization layer 309 (e.g., damascene or dual damascene processes). Any suitable structure may be utilized, and all such structures are fully intended to be included within the scope of this embodiment.

[0058] The cladding material 607 and the core material 609 can be formed using similar processes and materials as the material of the second optical component 307 and the dielectric material of the first metallization layer 309. For example, a first cladding material 607 (e.g., a dielectric material) can be deposited, and the material of the core material 609 (e.g., lithium niobate to form a thin-film lithium niobate device) can be deposited and patterned as needed, followed by the deposition of another cladding material 606 to cover the patterned core material 609. However, any suitable materials and processes can be used.

[0059] Figure 6B A top view of one embodiment of modulator 603 is shown, wherein modulator 603 is a Mach-Zehnder modulator having a core material 609 (wherein, for clarity, Figure 6B (The cladding material 607 has been removed). In the illustrated embodiment, the modulator 601 includes two waveguides 611 formed to enter a splitter portion 613 (where the waveguides 611 are close enough to allow evanescent coupling) and a combiner portion 615 (where the waveguides 611 are again close enough to allow evanescent coupling), which are connected by two waveguides 611 arranged as a first connecting arm 617 and a second connecting arm 619.

[0060] In addition to the waveguide 611 as shown, the modulator 603 also includes modulation units 605 located near the first connecting arm 617 and the second connecting arm 619. In other embodiments, the modulation units 605 may be formed along a single waveguide in the waveguide 611, or along the first connecting arm 617 and the second connecting arm 619. In further embodiments, one or more modulation units 605 may be formed adjacent to a single waveguide in the waveguide 611. Any suitable configuration may be utilized, and all such configurations are fully intended to be included within the scope of the embodiments.

[0061] Back Figure 6ATo control the modulation unit 605, a modulation through-substrate via (TSV) (also referred to as a through-device via (TDV) 621) is formed to connect the modulation unit 605 to an external device driver (not shown separately). In one embodiment, the modulation through-device via 621 extends through the modulation substrate 601 to provide a fast path for power, data, and ground to the modulation unit 605. In one embodiment, the modulation through-device via 621 can be formed by initially forming a modulation via opening in the modulation substrate 601. The modulation through-device via opening can be formed by applying and developing a suitable photoresist (not shown) and removing exposed portions of the modulation substrate 601.

[0062] Once the modulation through-device via opening is formed, the via can be lined with a pad. The pad can be an oxide, for example, formed of tetraethyl orthosilicate (TEOS) or silicon nitride, but any suitable dielectric material can also be used. The pad can be formed using a plasma-enhanced chemical vapor deposition (PECVD) process, but other suitable processes, such as physical vapor deposition or thermal processes, can also be used.

[0063] Once a liner is formed along the sidewalls and bottom of the modulation through-device via opening, a barrier layer (not shown separately) can be formed, and the remainder of the modulation through-device via opening can be filled with a conductive material. The conductive material may include copper, but other suitable materials such as aluminum, alloys, doped polysilicon, combinations thereof, etc., may also be used. The conductive material can be formed by electroplating copper onto a seed layer (not shown), filling, and overfilling the modulation through-device via opening. Once the modulation through-device via opening is filled, excess liner, barrier layer, seed layer, and conductive material outside the modulation through-device via opening can be removed by a planarization process such as chemical mechanical polishing (CMP), but any suitable removal process may also be used.

[0064] The size of the modulator 600 can be configured to provide any suitable number of modulators 603 (for clarity, Figure 6A Only a single modulator 603 is shown in the diagram. In some embodiments, the modulator 600 may have a thickness between about 2 μm and about 4 μm, and in more specific embodiments, the modulator 600 has a thickness such as 1.2 × 3 × 0.7 mm. 3 Or a larger size. However, any suitable size can be used.

[0065] Figure 6CAnother embodiment of the modulation device 600 is shown. In this embodiment, the waveguide 611 is formed as a ridge waveguide. Furthermore, the modulation unit 605 is formed after the waveguide 611, and thus located on the side of the waveguide 611 opposite to the modulation substrate 601. Any suitable configuration can be utilized, and all such configurations are fully intended to be included within the scope of this embodiment.

[0066] Figure 7 As shown, once the modulator 600 is formed, a waveguide within the back-side optical assembly 205 is used as an optical interposer to bond the modulator 600 to the first dielectric layer 201. In one embodiment, the modulator 600 and the first dielectric layer 201 can be bonded using a dielectric-to-dielectric bonding process. In a particular embodiment utilizing a dielectric-to-dielectric bonding process, this process can be initiated by activating the surfaces of the modulator 600 and the first dielectric layer 201. As an example, activating the top surface of the modulator 600 and the first dielectric layer 201 can include dry treatment, wet treatment, plasma treatment, exposure to inert gas plasma, exposure to H2, exposure to N2, exposure to O2, and combinations thereof. In embodiments using wet treatment, for example, RCA cleaning can be used. In another embodiment, the activation process can include other types of treatments. The activation process facilitates the bonding of the modulator 600 and the first dielectric layer 201.

[0067] Following the activation process, the modulation device 600 and the first dielectric layer 201 can be cleaned using, for example, chemical rinsing. The modulation device 600 is then aligned and positioned to physically contact the first dielectric layer 201. The modulation device 600 and the first dielectric layer 201 are then subjected to heat treatment and contact pressure to bond the modulation device 600 to the first dielectric layer 201. For example, the modulation device 600 and the first dielectric layer 201 may withstand pressures of about 200 kPa or less and temperatures of about 25°C to about 250°C to fuse the modulation device 600 to the first dielectric layer 201. In this way, the modulation device 600 and the first dielectric layer 201 form a dielectric-to-dielectric bonding device. In some embodiments, the bonding device is subsequently baked, annealed, pressed, or otherwise treated to strengthen or complete the bonding.

[0068] Furthermore, while specific processes for initiating and strengthening the bond 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 may be utilized. All of these processes are intended to be included entirely within the scope of the embodiments.

[0069] Once the modulation device 600 is bonded, a second gap-filling material 701 is deposited to fill the space around the modulation device 600 and provide additional support. In one embodiment, the second gap-filling material 701 may be a material such as silicon oxide, silicon nitride, silicon oxynitride, or a combination of these materials, which is deposited to fill and overfill the space around the modulation device 600. However, any suitable material and deposition method may be used.

[0070] After depositing the second gap-filling material 701, a third dielectric layer 703 can be deposited on the modulation device 600 and the second gap-filling material 701. In one embodiment, the third dielectric layer 703 can be a dielectric material such as silicon nitride, deposited using a deposition method such as chemical vapor deposition, atomic layer deposition, or physical vapor deposition. The third dielectric layer 703 can be deposited to approximately [value missing]. to approximately The thickness between, for example, approximately However, any suitable material, process, and thickness can be used.

[0071] Figure 8 The formation of a first through-device via (TDV) 801 and a passivation layer 803 is illustrated to form a first optical package 800 (e.g., a co-packaged optics (CPO)), which in some embodiments is an optical engine. In one embodiment, the first TDV 801 extends through a second gap filler material 701 and, if desired, through a first active layer 301 to provide fast paths for power, data, and ground. In one embodiment, the first TDV 801 can be formed by initially forming a TDV opening. The TDV opening can be formed by applying and developing a suitable photoresist (not shown) and removing the exposed portion of the exposure layer.

[0072] Once the through-hole opening is formed, it can be lined with a gasket. The gasket can be an oxide, for example, formed of tetraethyl orthosilicate (TEOS) or silicon nitride, but any suitable dielectric material can also be used. The gasket can be formed using a plasma-enhanced chemical vapor deposition (PECVD) process, but other suitable processes, such as physical vapor deposition or thermal processes, can also be used.

[0073] Once a liner is formed along the sidewalls and bottom of the through-hole opening, a barrier layer (not shown separately) can be formed, and the remainder of the through-hole opening can be filled with a first conductive material. The first conductive material may include copper, but other suitable materials such as aluminum, alloys, doped polysilicon, combinations thereof, etc., may also be used. The first conductive material can be formed by electroplating copper onto a seed layer (not shown), filling, and overfilling the through-hole opening. Once the through-hole opening is filled, excess liner, barrier layer, seed layer, and first conductive material outside the through-hole opening can be removed by a planarization process such as chemical mechanical polishing (CMP), but any suitable removal process may also be used.

[0074] Once the first through-hole 801 is formed, a second metallization layer 804 electrically connected to the first through-hole 801 can be formed. In one embodiment, the second metallization layer 804 can be formed as described above with respect to the first metallization layer 309, for example, using alternating layers of dielectric and conductive materials using a damascene process, dual damascene process, etc. In other embodiments, a plating process can be used to form the second metallization layer 804 to form and shape the conductive material, and then cover the conductive material with a dielectric material. However, any suitable structure and manufacturing method can be utilized.

[0075] The passivation layer 803 is formed to provide protection. In one embodiment, the passivation layer 803 may be formed of a dielectric material, such as silicon oxide, silicon nitride, polyimide, or combinations thereof. The dielectric material can be deposited using any suitable method, such as CVD, high-density plasma chemical vapor deposition (HDPCVD), PVD, atomic layer deposition (ALD), etc. However, any suitable material and deposition process can be utilized.

[0076] Furthermore, a first external connector 813 can be formed to provide conductive areas for contacting other external devices. The first external connector 813 can be conductive bumps (e.g., C4 bumps, ball grid arrays, microbumps, etc.), conductive pillars, or combinations thereof, utilizing materials such as solder and copper. In embodiments where the first external connector 813 includes contact bumps, the first external connector 811 can include materials such as tin, or other suitable materials such as silver, lead-free tin, or copper. In embodiments where the first external connector 813 is a solder bump, the first external connector 811 can be formed by initially forming a tin layer using common methods such as evaporation, electroplating, printing, solder transfer, ball placement, etc. Once the tin layer is structurally formed, reflow can be performed to shape the material into the desired bump shape.

[0077] Of course, while the use of the first external connector 813 is one embodiment that can be used to provide a connection for the first optical package 800, this is merely illustrative and does not imply limitation of the embodiment. Instead, any suitable method of physically, electrically, and in some cases optically connecting the first optical package 800 can be utilized, such as dielectric-to-dielectric and metal-to-metal bonding. Any suitable method of bonding the first optical package 800 can be used.

[0078] Figure 9 A very simplified optical path diagram is shown, illustrating a potential path of the optical signal 901 when it enters the first optical package 800 and is modulated by the modulator 600. Figure 9 (Indicated by the arrow marked 901). Figure 9 In the specific embodiment shown, the first active layer 301 of the first optical component 303 and the second optical component 307 can be used to form a first double-layer grating coupler 903. Optical signal 901 is received by the first double-layer grating coupler 903 and transitions into the waveguide of the second optical component 307 (e.g., a 400 nm thick SiN waveguide). Optical signal 901 can transition from the waveguide in the second optical component 307 into the waveguide of the first optical component 303 (e.g., a 270 nm thick silicon waveguide) via evanescent coupling. Optical signal 901 can also transition from the waveguide of the first optical component 303 to the waveguide within the back-side optical component 205 (e.g., a 400 nm SiN waveguide). Finally, the optical signal 901 can be transitioned to a waveguide within the modulator 600, and the optical signal 901 can be modulated by a modulator 603 (e.g., a Mach-Zehnder modulator with a 600 nm thick ribbed waveguide), the modulator 603 being located at a distance of less than about 200 nm from the back-side optical component 205. However, any suitable path can be used to receive the optical signal 901, transmit the optical signal 901 to the modulator 603, and modulate the optical signal 901.

[0079] Once the optical signal 901 is modulated on demand, it can be transmitted from the modulator 600 and returned to the remainder of the first optical package 800. In a particular embodiment, the optical signal 901 can transition from a waveguide within the modulator 600 to a waveguide within the back-side optics 205. The optical signal 901 can transition from the waveguide within the back-side optics 205 to a waveguide (e.g., a silicon waveguide) of the first optical component 303 via evanescent coupling. Then, the optical signal 901 can transition to a waveguide (e.g., a SiN waveguide) of the second optical component 307. From there, the optical signal 901 can be routed to other devices within the first optical package 800, or routed out of the first optical package 800 using, for example, a second double-layer grating coupler 905. However, any suitable route for the optical signal 901 to and from the modulator 600 can be utilized.

[0080] Figure 10 Another embodiment with a very simplified optical path diagram is shown, illustrating a potential path of the optical signal (in) when the optical signal 901 enters the first optical package 800 and is modulated by the modulator 600. Figure 10 (Indicated by the arrow marked 901). However, in Figure 10 In the specific embodiment shown, an edge coupler 1001 is used instead of the first double-layer grating coupler 903 to receive the optical signal 901. The optical signal 901 is received by the edge coupler 1001 and transitioned to the waveguide (e.g., a SiN waveguide) of the second optical component 307. The optical signal 901 can transition from the waveguide in the second optical component 307 to the waveguide (e.g., a silicon waveguide) of the first optical component 303 via evanescent coupling. The optical signal 901 can be transitioned from the waveguide of the first optical component 303 to a waveguide (e.g., a SiN waveguide) within the back-side optical component 205. Finally, the optical signal 901 can transition to the waveguide within the modulator 600 and be modulated by the modulator 603 (e.g., a Mach-Zehnder modulator). However, any suitable path can be used to receive, transmit, and modulate the optical signal 901 to the modulator 603.

[0081] Once the optical signal 901 is modulated on demand, it can be transmitted from the modulator 600 and returned to the remainder of the first optical package 800. In a particular embodiment, the optical signal 901 can transition from a waveguide within the modulator 600 to a waveguide within the back-side optics 205. The optical signal 901 can transition from the waveguide within the back-side optics 205 to a waveguide (e.g., a silicon waveguide) of the first optical component 303 via evanescent coupling. Then, the optical signal 901 can transition to a waveguide (e.g., a SiN waveguide) of the second optical component 307. From there, the optical signal 901 can be routed to other devices within the first optical package 800, or routed out of the first optical package 800 using, for example, a second edge coupler 1003. However, any suitable route for the optical signal 901 to and from the modulator 600 can be utilized.

[0082] Figure 11 Another embodiment with a very simplified optical path diagram is shown, illustrating a potential path of the optical signal (in) when the optical signal 901 enters the first optical package 800 and is modulated by the modulator 600. Figure 11 (Indicated by the arrow marked 901). However, in Figure 11 In the specific embodiment shown, instead of using the first optical component 303 ( Figure 10 The edge coupler 1001 or the first double-layer grating coupler 903 shown) Figure 9 Instead of receiving the optical signal 901 through the first optical component 302 (as shown), a first grating coupler 1101 located within the first active layer 301 of the first optical component 302 is used. In this embodiment, the optical signal 901 is received by the first grating coupler 1101 and transitioned to the waveguide (e.g., a silicon waveguide) of the first optical component 303. The optical signal 901 can then transition from the waveguide of the first optical component 303 to a waveguide (e.g., a SiN waveguide) within the back-side optical component 205. Finally, the optical signal 901 can transition to a waveguide within the modulator 600 and be modulated by the modulator 603 (e.g., a Mach-Zehnder modulator). However, any suitable path can be used to receive the optical signal 901, transmit it to the modulator 603, and modulate it.

[0083] Once the optical signal 901 is modulated on demand, it can be transmitted from the modulator 600 and returned to the rest of the first optical package 800. In a particular embodiment, the optical signal 901 can transition from a waveguide within the modulator 600 to a waveguide within the back-side optics 205. The optical signal 901 can also transition from a waveguide within the back-side optics 205 to a waveguide (e.g., a silicon waveguide) of the first optical component 303 via evanescent coupling. The optical signal 901 can then be routed to other devices within the first optical package 800, or routed out of the first optical package 800 using, for example, a second grating coupler 1103 located within the first active layer 301 of the first optical component 303. However, any suitable route for the optical signal 901 to and from the modulator 600 can be utilized.

[0084] Figure 12A Another embodiment is shown, wherein a grating coupler 1201 (or a dual-layer grating coupler or an edge coupler) is located within a first active layer 301 for receiving and / or transmitting optical signals 901. In this embodiment, in forming as described above... Figure 7 Following the aforementioned structure, one or more reflectors 1203 (e.g., different reflectors for each grating coupler) are formed and positioned such that portions of the optical signal 901 initially not captured by the grating coupler 1201 are reflected back to the grating coupler 1201, thereby improving the overall capture efficiency of the grating coupler 1201. In one embodiment, one or more reflectors 1203 may be formed along the top surface of the third dielectric layer 703. In one embodiment, one or more reflectors 1203 may be a single layer of reflective material, such as aluminum-copper, copper, gold, aluminum, titanium nitride, combinations of these materials, etc., or may be a multilayer structure, such as a Bragg reflector comprising alternating layers of different materials, such as alternating layers of silicon dioxide and amorphous silicon. The individual materials of one or more reflectors 1203 may be deposited using any suitable method, such as chemical vapor deposition, physical vapor deposition, plating, combinations of these methods, etc., and the individual layers may then be further patterned using, for example, photolithography masks and etching processes. However, the first reflector 1011 may be formed along the sidewalls of the recess using any suitable materials and methods. Furthermore, once reflector 1203 is formed, it can be used as described above. Figures 8-11 Additional processing is required to complete the first optical package 800.

[0085] In embodiments using reflector 1203, the reflected light from reflector 1203 will interfere with the optical signal 901 that first encounters grating coupler 1201. Therefore, the second gap filler material 701 should be thick enough to make the interference constructive and to maximize the light intensity at grating coupler 1201. In specific embodiments where the third dielectric layer 703, the first dielectric layer 201, and the second dielectric layer 203 have the dimensions described above, the second gap filler material 701 can have a thickness that increases the light intensity at grating coupler 1201. Therefore, it is possible to use... Figure 12B The chart shown indicates the thickness, such as 3.2μm, 3.7μm, etc. However, any suitable size can be used.

[0086] Furthermore, the gap between the waveguide within the first dielectric layer 201 and the waveguide within the first active layer 301 of the first optical component 303 should be spaced apart to minimize insertion loss. In some embodiments, the gap width should be between about 0.2 μm and about 0.3 μm, and the insertion loss should be between about -0.37 dB and -0.2 dB. However, any suitable gap spacing can be used.

[0087] By using the modulation device 600, problematic materials such as lithium niobate, which tend to contaminate and poison surrounding materials, can be used in optical modulation devices. Therefore, high-speed modulation of 100 GHz devices (e.g., achieving data rates exceeding 400 Gb / s) can be obtained, thereby increasing data bandwidth and allowing for realistic and feasible integration of thin-film lithium niobate structures into optical packages without the usual lithium contamination. Furthermore, the proposed embodiments are highly compatible with current manufacturing processes.

[0088] In some embodiments, a method of forming an optical device includes: forming a photonic integrated circuit including a first optical component, the first optical component including a waveguide connected to a coupler; bonding a first semiconductor device to the photonic integrated circuit; and bonding a modulation device to the photonic integrated circuit, the modulation device including a modulation device having lithium niobate, wherein, after bonding the modulation device, the modulation device is optically coupled to the waveguide. In one embodiment, the coupler is a grating coupler. In one embodiment, the method further includes forming a reflector after bonding the modulation device, the reflector being positioned to reflect an optical signal back to the grating coupler. In one embodiment, the modulation device is a Mach-Zehnder modulation device. In one embodiment, forming the photonic integrated circuit includes: forming a first active layer of the first optical component; and forming a second active layer of a second optical component over the first active layer, wherein the coupler is located within the second active layer of the second optical component. In one embodiment, the coupler is a double-layer grating coupler. In one embodiment, the method further includes forming the modulation device.

[0089] In another embodiment, a method of forming an optical device includes: bonding a first semiconductor device to a first side of a photonic integrated circuit, the photonic integrated circuit including a coupler and a waveguide; and bonding a modulation device to the photonic integrated circuit on the opposite side of the first semiconductor device, the modulation device including a lithium niobate film. In one embodiment, the method further includes forming the photonic integrated circuit. In one embodiment, the lithium niobate film is part of a Mach-Zehnder modulation device. In one embodiment, at least one coupler is a grating coupler. In one embodiment, the method further includes forming a reflector after bonding the modulation device, the reflector being positioned to reflect an optical signal to the grating coupler. In one embodiment, at least one coupler is an edge coupler. In one embodiment, the modulation device includes a through-substrate via.

[0090] In another embodiment, an optical device includes: a modulation device including a lithium niobate film; a first waveguide located above the modulation device and optically connected to the modulation device; and a photonic integrated circuit bonded above the modulation device, the first waveguide located between the modulation device and the photonic integrated circuit, the photonic integrated circuit including: a second waveguide optically connected to the first waveguide; a coupler optically connected to the second waveguide; and an electronic integrated circuit bonded above the photonic integrated circuit. In one embodiment, the coupler is an edge coupler. In one embodiment, the coupler is a grating coupler. In one embodiment, the optical device further includes a reflector located on the side of the modulation device opposite to the grating coupler and positioned to reflect optical signals to the grating coupler. In one embodiment, the grating coupler is a double-layer grating coupler. In one embodiment, the grating coupler is located on the side of the first active layer of the first optical component opposite to the first waveguide.

[0091] The foregoing outlines features of several embodiments to enable those skilled in the art to better understand various aspects of this disclosure. Those skilled in the art will understand that they can readily use this disclosure as the basis for designing or modifying other processes and structures to achieve the same purposes and / or advantages of the embodiments described herein. Those skilled in the art will also recognize that such equivalent structures do not depart from the spirit and scope of this disclosure, and that various changes, substitutions, and modifications can be made to them within this disclosure without departing from its spirit and scope.

Claims

1. A method for forming an optical device, the method comprising: A photonic integrated circuit is formed, comprising a first optical component, the first optical component including a waveguide connected to a coupler; The first semiconductor device is bonded to the photonic integrated circuit; as well as A modulation device is bonded to the photonic integrated circuit, the modulation device including a modulation device with lithium niobate, wherein, after bonding the modulation device, the modulation device is optically coupled to the waveguide.

2. The method according to claim 1, wherein, The coupler is a grating coupler.

3. The method of claim 2, further comprising, after joining the modulation device, forming a reflector positioned to reflect an optical signal back to the grating coupler.

4. The method according to claim 1, wherein, The modulation device is a Mach-Zehnder modulation device.

5. The method according to claim 1, wherein, Forming the photonic integrated circuit includes: The first active layer forming the first optical component; and A second active layer of a second optical component is formed above the first active layer, wherein the coupler is located within the second active layer of the second optical component.

6. The method according to claim 1, wherein, The coupler is a double-layer grating coupler.

7. A method for forming an optical device, the method comprising: A first semiconductor device is bonded to a first side of a photonic integrated circuit, the photonic integrated circuit including a coupler and a waveguide; as well as A modulation device is bonded to the photonic integrated circuit on the opposite side of the first semiconductor device, the modulation device comprising a lithium niobate film.

8. The method according to claim 7, wherein, The lithium niobate film is part of the Mach-Zehnder modulation device.

9. An optical device, comprising: Modulation devices, including lithium niobate films; A first waveguide is located above the modulation device, and the first waveguide is optically connected to the modulation device. A photonic integrated circuit, bonded above the modulation device, wherein the first waveguide is located between the modulation device and the photonic integrated circuit, the photonic integrated circuit comprising: The second waveguide is optically connected to the first waveguide; Coupler, optically connected to the second waveguide; and An electronic integrated circuit is bonded above the photonic integrated circuit.

10. The optical device of claim 9 further includes a reflector located on the side of the modulation device opposite to the grating coupler and positioned to reflect an optical signal to the grating coupler.

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