Methods of assembling optical structure for lidar system

Abstract

To provide an innovative packaging technology for silicon photonic devices.SOLUTION: A method for assembling an optical structure 1001 for a light detection and ranging (LIDAR) system comprises: forming a trench 1064 and one or more pedestals 1066 on a wafer 1060; forming a plurality of solder deposits on a surface of the trench 1064; placing a chip on the wafer by positioning the chip with respect to the one or more pedestals 1066, such that, when the chip is initially placed on the wafer 1060, the solder deposits do not contact the chip; and reflowing the solder deposits to form a plurality of joints, each contacting the chip.SELECTED DRAWING: Figure 10

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Regular Application No. 17 / 362,080, filed June 29, 2021, which claims priority to U.S. Provisional Application No. 63 / 046,906, filed July 1, 2020. Applications Nos. 17 / 362,080 and 63 / 046,906 are incorporated herein by reference.

[0002] TECHNICAL FIELD This disclosure relates generally to lasers and more particularly to photonics packaging. [Background technology]

[0003] Over the past two decades, significant advances have been made in silicon photonic devices for a wide range of applications, including communications and sensing, such as optical interconnects and light detection and ranging (LIDAR). Silicon photonics offers many advantages over other photonic technology platforms due to the inherent material properties of silicon. However, despite all of its advantages, the extremely small optical mode field of single-mode silicon waveguides makes it extremely challenging to package silicon photonic devices with essential light sources, such as lasers and optical amplifiers, and glass fibers. Furthermore, to minimize miniaturization and limit power consumption, the relevant light sources are often semiconductor laser diodes and semiconductor optical amplifiers (SOAs), fabricated from compound semiconductor materials, which are preferably packaged in hermetically sealed enclosures.

[0004] It is generally agreed that the packaging costs of silicon photonic products far exceed the wafer fabrication costs for producing silicon photonic integrated circuits (PICs), laser diodes (LDs), and SOA chips. Packaging technologies for silicon photonic devices require innovation and development. Summary of the Invention [Means for solving the problem]

[0005] Embodiments of the present disclosure include a light detection and ranging (LIDAR) device for an autonomous vehicle. The LIDAR device includes a laser assembly layer and a photonic integrated circuit (PIC) layer. The laser assembly layer includes a laser configured to emit laser light. The PIC layer includes a semiconductor optical amplifier (SOA) and a PIC wafer configured to incouple the laser light to the PIC wafer and transmit the laser light to the SOA.

[0006] In one embodiment, the LIDAR device further includes a wafer layer disposed between the laser assembly layer and the PIC wafer, the laser light being infrared laser light, and the wafer layer being transparent to the infrared laser light.

[0007] In one embodiment, the wafer layer includes a lens configured to receive infrared laser light from the laser assembly layer, the lens being integrated into the wafer layer and configured to focus the infrared laser light onto the input grating of the PIC wafer.

[0008] In one embodiment, the wafer layer includes a laser carrier wafer and an SOA cap wafer. The laser is coupled to the laser carrier wafer. The SOA cap wafer seals the SOA from the environment of the LIDAR device, and the SOA cap wafer is positioned between the PIC wafer and the laser carrier wafer.

[0009] In one embodiment, the wafer layer and the PIC wafer are formed of single crystal silicon.

[0010] In one embodiment, the wafer layer seals the SOA from the environment of the LIDAR device, and the laser is coupled to the wafer layer.

[0011] In one embodiment, the PIC wafer includes a lens configured to receive laser light from the laser assembly layer, the lens being integrated into the PIC wafer and configured to focus the laser light onto an input grating on the PIC wafer.

[0012] In one embodiment, the PIC wafer includes an exit feature integrated into the PIC wafer that is configured to receive the amplified laser light generated by the SOA and outcouple the amplified laser light from the PIC wafer.

[0013] In one embodiment, the laser assembly layer includes a laser lens disposed between the laser and a mirror of the PIC layer, the laser lens configured to collimate the laser light emitted from the laser.

[0014] In one embodiment, the SOA is flip-bonded to the PIC wafer.

[0015] In one embodiment, the PIC wafer includes a trench sized to accommodate solder for the SOA and a support platform formed from the PIC wafer to mechanically support the SOA and provide a vertical alignment reference.

[0016] In one embodiment, the PIC wafer includes one or more edge couplers that receive laser light from an input grating of the PIC wafer, the one or more edge couplers configured to incouple the laser light into the SOA.

[0017] In one embodiment, the output grating of the PIC wafer is located deeper within the PIC wafer than the input grating.

[0018] In one embodiment, the laser assembly layer further includes a capping layer that seals the laser from the environment of the LIDAR device and a mirror disposed on the sloped wall of the capping layer. The PIC wafer includes an input grating and an output grating. The input grating is configured to incouple the laser light reflected from the mirror and transmit the laser light to the SOA. The output grating is configured to receive the amplified laser light from the SOA and outcouple the amplified laser light from the PIC wafer.

[0019] An embodiment of the present disclosure includes an autonomous vehicle control system including a LIDAR device, a photodetector, and one or more processors. The LIDAR device includes a laser assembly layer and a PIC layer. The laser assembly layer includes an infrared laser configured to emit infrared laser light. The PIC layer includes an SOA and a PIC wafer configured to incouple the infrared laser light to the PIC wafer and transmit the infrared laser light to the SOA. The photodetector is configured to receive the infrared laser light reflected from an object in the environment of the autonomous vehicle control system that reflects the amplified laser light generated by the SOA. The one or more processors control the autonomous vehicle control system in response to signals generated by the photodetector.

[0020] In one embodiment, a wafer layer is disposed between the laser assembly layer and the PIC wafer, the wafer layer being transparent to infrared laser light.

[0021] In one embodiment, the wafer layer includes a lens configured to receive infrared laser light from the laser assembly layer, the lens being integrated into the wafer layer and configured to focus the infrared laser light onto the input grating of the PIC wafer.

[0022] In one embodiment, the wafer layer includes a laser carrier wafer and an SOA cap wafer. The laser is coupled to the laser carrier wafer. The SOA cap wafer seals the SOA from the environment of the LIDAR device, and the SOA cap wafer is positioned between the PIC wafer and the laser carrier wafer.

[0023] An embodiment of the present disclosure includes an autonomous vehicle including a LIDAR device, a photodetector, and one or more processors. The LIDAR device includes a laser assembly layer and a photonic integrated circuit (PIC) layer. The laser assembly layer includes a near-infrared laser configured to emit near-infrared laser light. The PIC layer includes a semiconductor optical amplifier (SOA) and a PIC wafer configured to incouple the near-infrared laser light to the PIC wafer and transmit the near-infrared laser light to the SOA. The photodetector is configured to receive the near-infrared laser light reflected from an object in the autonomous vehicle's environment that reflects the amplified laser light generated by the SOA. The one or more processors control the autonomous vehicle in response to signals generated by the photodetector.

[0024] In one embodiment, a wafer layer is disposed between the laser assembly layer and the PIC wafer, the wafer layer being transparent to near-infrared laser light. [Brief explanation of the drawings]

[0025] Non-limiting and non-exhaustive embodiments of the present invention are described with reference to the following drawings, in which like reference numerals refer to like parts throughout the various drawings unless otherwise specified.

[0026] [Figure 1a] 1 illustrates an apparatus including a laser assembly layer and a PIC layer according to an embodiment of the present disclosure. [Figure 1b] 1 illustrates an apparatus including a laser assembly layer and a PIC layer according to an embodiment of the present disclosure.

[0027] [Figure 2] 1 illustrates an apparatus including a laser assembly layer and a PIC layer, the PIC layer including an exit lens as an exit feature of the PIC wafer, according to an embodiment of the present disclosure.

[0028] [Figure 3] 1 illustrates an apparatus including a laser assembly layer and a wafer layer, including a focusing lens included in a laser carrier wafer of the wafer layer, according to an embodiment of the present disclosure.

[0029] [Figure 4] 1 illustrates an apparatus including a laser assembly layer and a focusing lens included in a PIC wafer of the PIC layer according to an embodiment of the present disclosure.

[0030] [Figure 5] 1 illustrates an apparatus including a laser assembly layer and a focusing lens included in an integrated wafer of a wafer layer according to an embodiment of the present disclosure.

[0031] [Figure 6] 1A-1D show side and top views of optical structures for fabricating laser and photonics devices according to embodiments of the present disclosure. [Figure 7] 1A-1D show side and top views of optical structures for fabricating laser and photonics devices according to embodiments of the present disclosure. [Figure 8] 1A-1D show side and top views of optical structures for fabricating laser and photonics devices according to embodiments of the present disclosure. [Figure 9] 1A-1D show side and top views of optical structures for fabricating laser and photonics devices according to embodiments of the present disclosure.

[0032] [Figure 10] 1A-1C show side and top views of an optical structure including a PIC wafer according to an embodiment of the present disclosure. [Figure 11]1A-1C show side and top views of an optical structure including a PIC wafer according to an embodiment of the present disclosure. [Figure 12] 1A-1C show side and top views of an optical structure including a PIC wafer according to an embodiment of the present disclosure. [Figure 13] 1A-1C show side and top views of an optical structure including a PIC wafer according to an embodiment of the present disclosure.

[0033] [Figure 14] 14A-14C show side and top views of optical structures including the optical structure of FIG. 9 and the optical structure of FIG. 13 according to embodiments of the present disclosure.

[0034] [Figure 15a] 1 illustrates an autonomous vehicle including an exemplary array of sensors according to an embodiment of the present disclosure.

[0035] [Figure 15b] FIG. 1 illustrates a top view of an autonomous vehicle including an exemplary array of sensors according to an embodiment of the present disclosure.

[0036] [Figure 15c] 1 illustrates an exemplary vehicle control system including a sensor, a powertrain, and a control system according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0037] Described herein are embodiments of laser and photonics packaging that can be embodied in light detection and ranging (LIDAR) devices and systems. In the following description, numerous specific details are set forth to provide a thorough understanding of the embodiments. However, one of ordinary skill in the relevant art will recognize that the techniques described herein may be practiced without one or more of the specific details, or may be practiced with other methods, components, or materials. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring certain aspects.

[0038] References throughout this specification to "one embodiment" or "one embodiment" mean that a particular feature, structure, or characteristic described in connection with an embodiment is included in at least one embodiment of the present invention. Thus, the appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification do not necessarily all refer to the same embodiment. Furthermore, features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0039] The automotive industry is currently developing autonomous features to control vehicles in certain situations. According to SAE International Standard J3016, there are six levels of autonomy ranging from Level 0 (no autonomy) to Level 5 (vehicles that can operate without driver input in all conditions). Vehicles with autonomous features utilize sensors to sense the environment in which the vehicle travels. Acquiring and processing data from the sensors allows the vehicle to navigate through its environment. An autonomous vehicle may include one or more of the disclosed LIDAR devices and systems for sensing its environment.

[0040] Throughout this specification, several technical terms are used. These terms shall take their ordinary meaning in the art unless specifically defined herein or the context of their use clearly indicates otherwise. For purposes of this disclosure, the term "autonomous vehicle" includes a vehicle having autonomous functionality at any autonomy level of SAE International Standard J3016.

[0041] In an embodiment of the present disclosure, visible light can be defined as having a wavelength range of approximately 380 nm to 700 nm. Invisible light can be defined as light having a wavelength outside the visible light range, such as ultraviolet and infrared light. Infrared light, which has a wavelength range of approximately 700 nm to 1 mm, includes near-infrared light. In an embodiment of the present disclosure, near-infrared light can be defined as having a wavelength range of approximately 700 nm to 1.6 μm.

[0042] In embodiments of the present disclosure, the term "transparent" can be defined as having a light transmittance of greater than 90%. In some embodiments, the term "transparent" can be defined as a material having a visible light transmittance of greater than 90%.

[0043] This disclosure relates to the construction of silicon photonic devices with optical amplifiers and semiconductor lasers encapsulated using silicon micro-optical benches (MOBs) with wafer-level packaging technology. Embodiments of this disclosure describe the design and assembly process of silicon photonic packages containing silicon photonic integrated circuits (PICs), laser diodes, and semiconductor optical amplifiers (SOAs), as well as other optoelectronic and micro-optical components such as photodiodes (PDs), focusing lenses, isolators, prisms, and mirrors. The carrier and enclosure of such packages can be silicon micro-benches fabricated using silicon micromachining techniques. The assembly process can be performed at the die or wafer level, and hermetic sealing can be achieved by wafer bonding under vacuum or inert atmosphere. The completed wafer assembly can be tested using automated wafer-level testing and then diced into individual dies containing fully hermetically sealed PICs, LDs, and SOAs for integration with other electronic processing equipment.

[0044] 1a illustrates an apparatus 100 including a laser assembly layer 110 and a PIC layer 150 according to an embodiment of the present disclosure. The apparatus 100 may be included in a LIDAR device and / or system utilized in an autonomous vehicle. The apparatus 100 illustrates an exemplary photonic package including a silicon PIC wafer 160, one or more laser diodes 123, and an SOA 151. The apparatus 100 may also include other optoelectronic and microcomponents, such as additional photodiodes, additional focusing lenses, prisms, mirrors, and / or beam monitoring, correction, and steering components.

[0045] Laser assembly layer 110 includes laser 123 configured to emit laser light 191. Laser 123 can be a continuous wave (CW) laser. Laser 123 can be an infrared laser that emits infrared laser light. Laser 123 can be a near-infrared laser that emits near-infrared laser light. In FIG. 1a, laser assembly layer 110 also includes photodiode 121, laser lens 125, and isolator 127. Laser assembly layer 110 also includes capping layer 111 that seals laser 123 (and other components of laser assembly layer 110) from the environment of device 100. Mirror 115 is disposed on the angled wall of capping layer 111. In some embodiments, mirror 115 can be a separate component that is not disposed on the angled wall of capping layer 111.

[0046] The wafer layer 130 of the device 100 is disposed between the laser assembly layer 110 and the PIC wafer 160 of the PIC layer 150. The wafer layer 130 can be silicon. In one embodiment, the wafer layer 130 is formed of single-crystal silicon. In particular, silicon is at least partially transparent at infrared wavelengths. Silicon may be considered transparent at some infrared wavelengths. In FIG. 1a, the wafer layer 130 includes a laser carrier wafer 131 and an SOA cap wafer 132. The laser carrier wafer 131 and the SOA cap wafer 132 can be silicon or other semiconductor materials. The laser carrier wafer 131 and the SOA cap wafer 132 can be bonded together. The optical components 121, 123, and 125 and the isolator 127 can be coupled to the laser carrier wafer 131. The capping layer 111 is supported by the laser carrier wafer 131.

[0047] 1a, SOA cap wafer 132 is configured to seal SOA 151 from the environment of device 100. SOA cap wafer 132 is configured to seal SOA 151 from the environment of device 100. SOA cap wafer 132 is disposed between PIC wafer 160 and laser carrier wafer 131. Wafer layer 130 includes focusing lens 133 configured to receive laser light 193 from laser assembly layer 110 (reflected from mirror 115 in the illustrated embodiment of FIG. 1a). Focusing lens 133 is integrated into wafer layer 130. In FIG. 1a, focusing lens 133 is integrated into SOA cap wafer 132. Focusing lens 133 is configured to focus laser light 193 onto input grating 163 of PIC wafer 160. The lens curvature of the focusing lens 133 can be formed by a subtractive process (eg, plasma etching technique) that forms the focusing lens 133 in the SOA cap wafer 132 .

[0048] In one embodiment, PIC wafer 160 is formed of single crystal silicon. PIC wafer 160 includes input grating 163 and output grating 165. Input grating 163 and output grating 165 may be diffractive optical elements formed of single crystal silicon. Input grating 163 is configured to incouple laser light 193 (reflected from mirror 115) and direct the laser light 193 to SOA 151 as incoupled laser light 195. Input grating 163 may be formed using surface relief technology. Input grating 163 may be designed to incouple (and redirect) light received at a specific angle and having a specific wavelength. Focusing lens 133 may be configured to receive laser light 193 and illuminate input grating 163 at a specific angle that increases the efficiency of input grating 163. Focusing lens 133 may also be configured to illuminate a two-dimensional area of ​​input grating 163 to increase and / or maximize incoupling efficiency.

[0049] The SOA 151 receives incoupled laser light 195 from the input grating 163. The incoupled laser light 195 is amplified by the SOA 151 and directed to the output grating 165 as amplified laser light 197. FIG. 1b shows a slightly enlarged view of the PIC wafer 160 and the SOA 151. In FIG. 1b, the incoupled laser light 195 is indicated by a dashed arrow, and the amplified laser light 197 is indicated by a dotted arrow. In FIG. 1a, solder 152 secures the SOA 151 to the PIC wafer 160. The SOA 151 can be flip-bonded to the PIC wafer 160. Electrical pads and traces can be formed on the PIC wafer 160 to connect the SOA 151 to the PIC wafer 160. Output grating 165 receives amplified laser light 197 from SOA 151 and outcouples the amplified laser light 197 from PIC wafer 160. As shown in FIG. 1a, output grating 165 produces output light 198. Exit feature 169 receives the amplified laser light and outcouples the amplified laser light from PIC wafer 160 as output light 199. In the particular embodiment of FIG. 1a, exit feature 169 receives amplified laser light 197 via output grating 165 as output light 198. Exit feature 169 may be integrated into PIC wafer 160 or may be designed to direct output light 199 at a particular design angle to another device (not shown). In the particular embodiment of FIG. 1a, exit feature 169 is a prism structure that may be formed in a subtractive process (e.g., chemical etching techniques) of PIC wafer 160.

[0050] During operation, laser 123 emits laser light 191. Laser lens 125 can collimate the laser light. Laser lens 125 is disposed between laser 123 and mirror 115. In the particular embodiment of FIG. 1a, laser lens 125 is disposed between isolator 127 and laser 123. Isolator 127 receives laser light 191 from laser lens 125. Isolator 127 optically isolates laser 123 from optical elements following isolator 127 in the optical system. For example, isolator 127 prevents the laser light from being reflected back to laser 123 by mirror 115. Mirror 115 receives the laser light from isolator 127 and reflects the laser light to lens 133 as laser light 193. Because laser light 193 is infrared laser light and silicon is at least partially transparent to infrared light, laser light 193 propagates to focusing lens 133. Focusing lens 133 focuses laser light 193 onto input grating 163 , which incouples laser light 193 onto PIC wafer 160 as incoupled laser light 195 .

[0051] The incoupled laser light 195 can propagate to the SOA 151, confined by a waveguide (not specifically shown) formed in the PIC wafer 160. The PIC wafer 160 can include an edge coupler (not specifically shown in FIG. 1a) that can receive the incoupled laser light 195 and facilitate incoupling the laser light 195 to one or more inputs of the SOA 151. The SOA 151 amplifies the incoupled laser light 195 and outputs amplified laser light 197. The PIC wafer 160 can include an edge coupler (not specifically shown in FIG. 1a) that can facilitate outputting the amplified laser light 197 to the PIC wafer 160. The amplified laser light 197 can propagate to the output grating 165, confined by a waveguide (not specifically shown) formed in the PIC wafer 160. The output grating 165 receives the amplified laser light 197 and redirects the light as output light 198. Exit feature 169 receives output light 198 and outcouples the light as output light 199 .

[0052] 2 illustrates an apparatus 200 including a laser assembly layer 110 and a PIC layer 250 including an exit lens 271 as an exit feature of a PIC wafer 260 according to an embodiment of the present disclosure. While some structures of apparatus 200 are the same as apparatus 100, the exit feature of PIC wafer 260 is an exit lens 271 rather than a prism. Exit lens 271 is integrated into PIC wafer 260. The lensing curvature of exit lens 271 can be formed by a subtractive process (e.g., plasma etching technique) that forms exit lens 271 in PIC wafer 260. The lensing curvature can be spherical or aspherical and can be configured to output output light 299 at a specific angle.

[0053] FIG. 3 illustrates an apparatus 300 including a laser assembly layer 110 and a wafer layer 330 including a focusing lens 333 included in a laser carrier wafer 331 of the wafer layer 330 according to an embodiment of the present disclosure. The structure of some parts of the apparatus 300 is the same as that of the apparatus 100, except that instead of the focusing lens 133 being integrated into the SOA cap wafer 132 as in FIG. 1a, the focusing lens 333 is integrated into the laser carrier wafer 331. In FIG. 3, the focusing lens 333 is formed in the laser carrier wafer 331, and a corresponding void 339 is formed in the SOA cap wafer 332 to accommodate the focusing lens 333 protruding into the SOA cap wafer 332. The lensing curvature of the focusing lens 333 can be formed in a subtractive process (e.g., plasma etching technique) that forms the focusing lens 333 in the laser carrier wafer 331. The lensing curvature can be spherical or aspherical and can be configured to focus the laser light 193 onto the input grating 163 at a specific angle.

[0054] FIG. 4 illustrates an apparatus 400 including a focusing lens 433 included in a PIC wafer 460 of the laser assembly layer 110 and the PIC layer 450 according to an embodiment of the present disclosure. The structure of some of the apparatus 400 is the same as that of apparatus 100, except that instead of the focusing lens 133 being integrated into the SOA cap wafer 132 as in FIG. 1a, the focusing lens 433 is integrated into the PIC wafer 460. In FIG. 4, the focusing lens 433 is formed in the PIC wafer 460, and a corresponding void 439 is formed in the SOA cap wafer 432 to accommodate the focusing lens 433 protruding into the SOA cap wafer 432. The lensing curvature of the focusing lens 433 can be formed in a subtractive process (e.g., plasma etching technique) that forms the focusing lens 433 in the PIC wafer 460. The lensing curvature can be spherical or aspherical and can be configured to focus the laser light 193 onto the input grating 163 at a specific angle.

[0055] FIG. 5 illustrates an apparatus 500 including a focusing lens 533 included in an integrated wafer 531 of the laser assembly layer 110 and wafer layer 530 according to an embodiment of the present disclosure. The integrated wafer 531 functions as both the laser carrier wafer and the SOA cap layer. The wafer layer 530 may be formed of a continuous layer of silicon. In FIG. 5, the focusing lens 533 is formed in the integrated wafer 531. The lensing curvature of the focusing lens 533 may be formed in a subtractive process (e.g., plasma etching technique) that forms the focusing lens 533 in the integrated wafer 531. The lensing curvature may be spherical or aspherical and is configured to focus the laser light 193 onto the input grating 163 at a specific angle.

[0056] FIG. 6 shows a side view and a top view of an optical structure 601 for fabricating laser and photonics devices according to an embodiment of the present disclosure. The left side of FIG. 6 shows a side view of the optical structure 601 including a laser carrier wafer 131. The right side of FIG. 6 shows a top view of the optical structure 601 including a temperature sensor 640 and an under-bump metal (UBM) pad 642. Metal traces and pads may be formed on the laser carrier wafer 131 to facilitate powering the device and transmitting and receiving electrical signals. Solder traces help hermetically seal the electrical and / or optical components from the environment of the device being fabricated by enclosing or surrounding the traces and pads for the electrical and / or optical components. Fabrication of the optical structure 601 may include fabricating a laser carrier wafer with thin-film structures such as the temperature sensor 640, a metal film stack for soldering, and electrical traces for power supply and device monitoring.

[0057] Figure 7 shows a side view and a top view of an optical structure 701 for fabricating lasers and photonics devices according to an embodiment of the present disclosure. The left side of Figure 7 shows a side view of the optical structure 701 having a photodiode 121 and a laser 123 coupled to a laser carrier wafer 131. The photodiode 121 and the laser 123 may be wire-bonded with gold wires to electrical pads formed on the laser carrier wafer 131. The right side of Figure 7 shows a top view of the optical structure 701 including the photodiode 121 and the laser 123 wire-bonded to electrical pads formed on the laser carrier wafer 131.

[0058] FIG. 8 shows a side view and a top view of an optical structure 801 for fabricating laser and photonics devices according to an embodiment of the present disclosure. The left side of FIG. 8 shows a side view of the optical structure 801 having a photodiode 121, a laser 123, a laser lens 125, and an isolator 127 coupled to a laser carrier wafer 131. The laser lens 125 and the isolator 127 can be considered passive photonics devices. Collimation and alignment of the laser beam can be achieved with active alignment during the assembly process. The laser 123 emits laser light 191, and the laser lens 125 collimates the laser light 191 into a collimated laser beam. The right side of FIG. 8 shows a top view of the optical structure 801.

[0059] FIG. 9 shows a side view and a top view of an optical structure 901 for fabricating laser and photonics devices according to an embodiment of the present disclosure. The left side of FIG. 9 shows a side view of the optical structure 901 with a capping layer 111 that caps and encapsulates the electrical and optical components of the optical structure 901. The capping process of FIG. 9 can be performed in a vacuum or an inert atmosphere to provide a hermetic seal for the laser. The capping layer 111 also includes a built-in mirror 115 that redirects the laser light toward the PIC layer (not shown in FIG. 9). The right side of FIG. 9 shows a top view of the optical structure 901. The capping layer 111 can be sized to match the solder traces to encapsulate the electrical and optical components included in the optical structure 901.

[0060] FIG. 10 shows side and top views of an optical structure 1001 including an exemplary PIC wafer 1060 according to an embodiment of the present disclosure. The left side of FIG. 10 (the side view of the optical structure 1001) shows that a deep trench 1064 and support pedestals 1066 can be formed in the PIC wafer 1060 to accommodate (and align) the SOA 151. The deep trench 1064 is configured to accommodate solder that electrically couples the SOA 151 to traces / pads on the PIC wafer 1060. The support pedestals 1066 are configured to aid in vertical alignment of a laser beam propagating between the SOA 151 and the PIC wafer 1060. The PIC wafer 1060 can also include built-in prisms and / or lenses formed therein to steer the laser light. The side view of the optical structure 1001 also shows that in some embodiments, the output grating 1065 can be positioned deeper in the PIC wafer 1060 than the input grating 1063. Laser light propagates between the PIC wafer 1060 and the SOA 151 (added in FIG. 12) via edge coupler 1068. The right side of FIG.

[0061] 11 shows a side view and a top view of an optical structure 1101 including solder balls formed in deep trenches 1064 of a PIC wafer 1060 according to an embodiment of the present disclosure. The solder balls can be injected (bumped) into the deep trenches 1064 and pressed (coined) to lower the height of the old ball below the height of the support pedestal 1066.

[0062] 12 shows side and top views of an optical structure 1201 including bonding an SOA 151 to a PIC wafer 1060 according to an embodiment of the present disclosure. In some embodiments, the SOA 151 is flip-chip bonded (P-side down) to the PIC wafer 1060. The SOA 151 includes input and output ports on the same edge that couple to edge couplers 1068 of the PIC wafer 1060. Horizontal alignment is achieved by the flip-chip bonding, while vertical alignment is adjusted by the preset height of the support pedestal 1066. When the solder balls reflow with heat, they expand and rise to contact the metal film on the surface of the SOA 151, thereby soldering the SOA 151 to the PIC wafer 1060.

[0063] 13 shows a side view and a top view of an optical structure 1301 that includes capping an SOA 151 with an SOA capping wafer 132 that includes a lens 133 according to an embodiment of the present disclosure. The operations shown in FIG. 13 can be performed in a vacuum or inert atmosphere to provide a hermetic seal of the SOA 151.

[0064] 14 shows a side view and a top view of an optical structure 1401 including optical structures 901, 1301 bonded together according to an embodiment of the present disclosure. Bonding of the optical structures 901, 1301 can be done by wafer-to-wafer bonding or die-to-wafer bonding. After the bonding process, the wafers can be diced and known good die can be picked for integration with other devices in a system. Electrical connections can be provided by wirebonding or soldering to the TSVs.

[0065] Embodiments of the present disclosure enable the fabrication of silicon photonic packages using micromachined silicon micro-optical benches (MOBs) as device carriers and enclosures. Electrical and / or optical components can be assembled at the wafer level to increase production scale. Additionally, capping the entire completed assembly on a wafer with another cap wafer via a wafer bonding process in a vacuum or inert atmosphere using a cap (e.g., capping layer 111 and / or SOA cap wafer 132) helps seal the disclosed device from the device environment.

[0066] The unique physical and chemical properties of single-crystal silicon wafers lend themselves to fabricating packages for silicon photonic components. For example, the transparency of single-crystal silicon at infrared wavelengths enables the use of the disclosed devices in many sensing applications, including optical communications and LIDAR. Single-crystal silicon can also be chemically etched to form atomically flat facets at specific angles that are used to create mirrors and prisms. Single-crystal silicon can also be plasma etched to form microlenses integrated into the wafer. Single-crystal silicon has a highly stable oxide as a robust passivation layer, high thermal conductivity, and excellent mechanical strength. As a result, designers can integrate many key functions, such as photonic integrated circuits, micro-optical devices, heat sinks, and mechanical supports, onto a single silicon wafer, as described in this disclosure.

[0067] Figure 1a shows a hybrid integrated silicon package. One starts by constructing a PIC wafer (e.g., PIC wafer 160) with all the major functions for the target application. Micro-optical components such as mirrors, lenses, and prisms for light steering can be fabricated on this same wafer. It can also be used as a chip carrier for mounting laser diode (LD) or SOA chips, with light coupled between the PIC and a light source via edge or grating couplers. The LD and SOA are heat-generating elements, and the silicon wafer acts as a heat sink. Using a wafer-level packaging approach, designers can leverage well-developed automated wafer testing methods to probe and screen completed assemblies across the wafer and map known good die (KGD) for later use. Maintaining the assembly on the wafer makes wafer bonding an accessible technique for hermetically enclosing the assembly in a vacuum or inert atmosphere. In fact, multiple multifunctional silicon wafers can be fabricated and bonded together.

[0068] Figures 1a-5 show different embodiments of package designs that share structures including a laser assembly layer, a PIC layer, and a wafer layer located between the laser assembly layer and the PIC layer. Figures 6-9 illustrate the assembly process for constructing a laser assembly. The assembly process begins with the fabrication of a laser carrier wafer, which is provided with various thin-film features such as temperature sensors, a metal film stack for soldering, and metal traces for electrical connection. Designers may also include through-silicon vias (TSVs) (not shown) for electrical connection. Onto this carrier, designers can first attach active devices such as laser diodes (LDs) by soldering, since these devices are power-intensive and offer heat dissipation benefits. If there are no TSVs to electrically connect these devices, wire bonds are used. Next, passive components such as lenses and isolators can be attached with UV adhesive in an active alignment process to ensure precise placement. This assembly process is applicable to die-level and wafer-level assembly. Wafer-level assembly may enable automated testing and sealing. In the wafer-level assembly process, soldering may be performed with localized heating to prevent interference with any pre-deposited solder at adjacent locations. After assembly is complete and the wafer is hermetically capped, wafer testing can be performed and the KGD can be diced for later use.

[0069] Figures 10-13 show the assembly process for attaching an SOA chip to a PIC wafer. The PIC wafer (e.g., PIC wafer 1060) provides a deep trench (e.g., trench 1064) to accommodate the solder and a support (e.g., support 1066) to mechanically support the SOA 151 and provide a vertical alignment reference. The use of solder balls allows for introduction by laser jetting or screening. Solder can also be electroplated at the bottom of the trench and reflowed to form a ball. The volume and shape of the solder deposit can be determined to satisfy two conditions: (1) the solder must not touch the SOA when it is placed on the support, and (2) the solder must expand and rise upon reflow to contact the SOA 151 and form a joint. A practical approach is to make the diameter of the under-bump metal (UBM) pad smaller than the solder ball that will rest on it and press the solder ball flat (a process known as "coining"). This technique allows the solder height to be lower than the support platform. Upon heating, the solder will collect on the UBM pad, and the limited pad area will allow the solder to ball up and reach the SOA. This arrangement is done to ensure precise alignment by avoiding placing the SOA directly above the solder before reflow, which can cause slight slippage of the SOA when the solder melts. Other features on the PIC wafer may include input / output gratings and edge couplers, prisms / lenses for light steering, and wire bond pads for electrical connections.

[0070] In the embodiment shown in Figures 10-13, light is input / output to / from the PIC via a diffraction grating coupler, and light travels between the PIC and SOA via an edge coupler. Therefore, the SOA and PIC are assembled to enable direct coupling (Butt coupling), which may require precise alignment of the SOA relative to the PIC's edge coupler. To achieve this, the height of the support platform is precisely adjusted to provide proper vertical alignment, while horizontal alignment can be controlled using a high-precision flip-chip bonder. Thus, the assembly process can be applied to die-level or wafer-level assembly. Wafer-level assembly may enable automated testing and sealing. In the wafer-level assembly process, soldering may be performed with localized heating to prevent interference with any pre-adhesion of solder to adjacent sites. After assembly is complete and the wafer is hermetically capped, wafer testing can be performed and the KGD can be mapped.

[0071] Figure 14 shows the final assembly operation of attaching the laser unit to the SOA / PIC unit. This can be achieved by wafer-to-wafer or die-to-wafer bonding. Electrical connections can be provided by two-level wirebonds as shown or by soldering to TSVs (not specifically shown).

[0072] 1a-14 in accordance with aspects of the present disclosure. The illustrated autonomous vehicle 1500 includes an array of sensors configured to capture one or more objects in an environment external to the autonomous vehicle and generate sensor data related to the captured one or more objects for the purpose of controlling operation of the autonomous vehicle 1500. FIG. 15a illustrates sensors 1533A, 1533B, 1533C, 1533D, and 1533E. FIG. 15b illustrates a top view of the autonomous vehicle 1500 including sensors 1533A, 1533B, 1533C, 1533D, and 1533E, as well as sensors 1533F, 1533G, 1533H, and 1533I. Any of sensors 1533A, 1533B, 1533C, 1533D, 1533E, 1533F, 1533G, 1533H, and / or 1533I may include a LIDAR device, including the designs of Figures 1a-14. Figure 15c shows a block diagram of an example system 1599 for an autonomous vehicle 1500. For example, autonomous vehicle 1500 may include a powertrain 1502 including a prime mover 1504, which may be powered by an energy source 1506 and provide power to a drivetrain 1508. Autonomous vehicle 1500 may further include a control system 1510 including a directional control device 1512, a powertrain control device 1514, and a brake control device 1516. Autonomous vehicle 1500 may be embodied as any number of different vehicles, including vehicles capable of transporting people and / or cargo and navigating a variety of different environments. It will be appreciated that the aforementioned components 1502-1516 may vary greatly depending on the type of vehicle in which they are utilized.

[0073] The embodiments described below focus on wheeled land vehicles, such as, for example, cars, vans, trucks, or buses. In such embodiments, the prime mover 1504 may include (among other things) one or more electric motors and / or an internal combustion engine. The energy source may include, for example, a fuel system (e.g., providing gasoline, diesel, hydrogen), a battery system, solar panels, or other renewable energy sources, and / or a fuel cell system. Drivetrain 1508 may include wheels and / or tires along with a transmission and / or any other mechanical drive components suitable for converting the output of prime mover 1504 into vehicle motion, as well as one or more brakes configured to controllably stop or slow autonomous vehicle 1500, or directional or steering components suitable for controlling the trajectory of autonomous vehicle 1500 (e.g., a rack and pinion steering linkage that allows one or more wheels of autonomous vehicle 1500 to pivot about a substantially vertical axis to change the angle of the wheel's plane of rotation relative to the vehicle's longitudinal axis). In some embodiments, a combination of powertrain and energy source can be used (e.g., in the case of an electric / gas hybrid vehicle). In some embodiments, multiple electric motors (e.g., dedicated to individual wheels or axles) can be used as prime movers.

[0074] Directional control device 1512 may include one or more actuators and / or sensors for receiving and controlling feedback from directional or steering components to enable autonomous vehicle 1500 to follow a desired trajectory. Powertrain control device 1514 may be configured to control the output of powertrain 1502, for example, by controlling the output power of prime mover 1504 and controlling transmission gears in drivetrain 1508, thereby controlling the speed and / or direction of autonomous vehicle 1500. Brake control device 1516 may be configured to control one or more brakes, for example, disc or drum brakes coupled to the vehicle's wheels, to slow or stop autonomous vehicle 1500.

[0075] As will be understood by one of ordinary skill in the art having the benefit of this disclosure, other vehicle types, including, but not limited to, off-road, all-terrain, or tracked vehicles or construction equipment, necessarily use different powertrains, drivetrains, energy sources, directional controls, powertrain controls, and brake controls. Further, in some embodiments, some of the components may be combined, for example, where the directional control of the vehicle is primarily handled by modifying the output of one or more prime movers. Accordingly, the embodiments disclosed herein are not limited to the specific application of the technology described herein in autonomous wheeled land vehicles.

[0076] In the illustrated embodiment, autonomous control for autonomous vehicle 1500 is embodied in vehicle control system 1520, which may include one or more processors within processing logic 1522 and one or more memories 1524, with processing logic 1522 configured to execute program code (e.g., instructions 1526) stored in memory 1524. Processing logic 1522 may include, for example, one or more graphics processing units (GPU(s)) and / or one or more central processing units (CPU(s)).

[0077] Sensors 1533A-1533I may include various sensors suitable for collecting data from the autonomous vehicle's environment for use in controlling the operation of the autonomous vehicle. For example, sensors 1533A-1533I may include a RADAR unit 1534, a LIDAR unit 1536, and a 3D positioning sensor 1538, which may be a satellite navigation system such as GPS, GLONASS, BeiDou, Galileo, or Compass. The LIDAR design of FIGS. 1a-14 may be included in LIDAR unit 1536. LIDAR unit 1536 may include, for example, multiple LIDAR sensors distributed around the autonomous vehicle 1500. In some embodiments, 3D positioning sensor 1538 may determine the vehicle's position on Earth using satellite signals. Sensors 1533A-1533I may optionally include one or more ultrasonic sensors, one or more cameras 1540, and / or an inertial measurement unit (IMU) 1542. In some embodiments, camera 1540 may be a monographic or stereographic camera and may record still and / or video images. Camera 1540 may include a complementary metal-oxide-semiconductor (CMOS) image sensor configured to capture images of one or more objects in the environment external to autonomous vehicle 1500. IMU 1542 may include multiple gyroscopes and accelerometers capable of detecting linear and rotational motion of autonomous vehicle 1500 in three directions. One or more encoders (not shown), such as wheel encoders, may be used to monitor the rotation of one or more wheels of autonomous vehicle 1500.

[0078] The outputs of sensors 1533A-1533I may be provided to a control subsystem 1550, which includes a localization subsystem 1552, a trajectory subsystem 1556, a perception subsystem 1554, and a control system interface 1558. The localization subsystem 1552 is configured to determine the position and orientation (or "pose") of the autonomous vehicle 1500 within its surrounding environment, and generally within a particular geographic region. The autonomous vehicle's position can be compared to the positions of additional vehicles in the same environment as part of generating labeled autonomous vehicle data. The perception subsystem 1554 may be configured to detect, track, classify, and / or determine objects in the environment surrounding the autonomous vehicle 1500. The trajectory subsystem 1556 is configured to generate a trajectory for the autonomous vehicle 1500 over a particular time frame, taking into account stationary and moving objects in the environment as well as a desired destination. In some embodiments, machine learning models can be utilized to generate the vehicle trajectory. Control system interface 1558 is configured to communicate with control system 1510 to implement a trajectory for autonomous vehicle 1500. In some embodiments, machine learning models can be utilized to control the autonomous vehicle to implement a planned trajectory.

[0079] Vehicle control system 1520 may be configured to control powertrain 1502 of autonomous vehicle 1500 in response to signals generated by photodetectors included in sensor 1533. One or more photodetectors (e.g., photodiodes or image sensors) may be configured to receive infrared laser light reflected from targets (e.g., objects) in the environment of the autonomous vehicle control system that reflect the amplified laser light generated by SOA 151 and outcoupled from the device as output light 199. The photodetectors may be included in one or more LIDAR units 1536, and devices disclosed in FIGS. 1a-14 may also be included in one or more LIDAR units 1536. Vehicle control system 1520 may be configured to control powertrain 1502 of autonomous vehicle 1500 in response to outputs from multiple LIDAR sensors 1536.

[0080] It will be understood that the collection of components shown in FIG. 15c for vehicle control system 1520 is merely exemplary in nature. Individual sensors may be omitted in some embodiments. In some embodiments, different types of sensors shown in FIG. 15c may be used for redundancy and / or to cover other areas in the environment surrounding the autonomous vehicle. In some embodiments, different types and / or combinations of control subsystems may be used. Also, while subsystems 1552-1558 are shown as separate from processing logic 1522 and memory 1524, it will be understood that in some embodiments, some or all of the functionality of subsystems 1552-1558 may be embodied in program code, such as instructions 1526, resident in memory 1524 and executed by processing logic 1522, and that such subsystems 1552-1558 may, in some cases, be embodied using the same processor and / or memory. In some embodiments, the subsystems may be embodied using various dedicated circuit logic, various processors, various field programmable gate arrays (FPGAs), various application specific integrated circuits (ASICs), various real-time controllers, etc., and as previously mentioned, multiple subsystems may utilize circuits, processors, sensors, and / or other components. Additionally, the various components of vehicle control system 1520 may be networked in various ways.

[0081] In some embodiments, many different architectures, including various combinations of software, hardware, circuit logic, sensors, and networks, can be used to implement the various components shown in FIG. 15c. Each processor can be embodied, for example, as a microprocessor, and each memory can represent a random access memory (RAM) device, including main memory and any secondary levels of memory—e.g., cache memory, non-volatile or backup memory (e.g., programmable or flash memory), and read-only memory. Each memory can also be considered to include memory storage devices physically located elsewhere in autonomous vehicle 1500, such as cache memory within the processor, and any storage capacity used as virtual memory, for example, stored in a mass storage device or other computer controller. Processing logic 1522 shown in FIG. 15c, or entirely separate processing logic, can be used to implement additional functionality for autonomous vehicle 1500 outside of autonomous driving control, such as controlling an entertainment system, operating doors, lights, or convenience features, etc.

[0082] Additionally, for additional storage, autonomous vehicle 1500 may also include one or more mass storage devices, such as a removable disk drive, a hard disk drive, a direct access storage device (DASD), an optical drive (e.g., a CD drive, a DVD drive, etc.), a solid-state storage drive (SSD), a networked storage device, a storage area network, and / or a tape drive, among others. Autonomous vehicle 1500 may also include a user interface 1564, such as one or more displays, touchscreens, voice and / or gesture interfaces, buttons, and other tactile controls, that enables autonomous vehicle 1500 to receive inputs from and generate outputs for the passengers. In some embodiments, inputs from the passengers may be received via an app or web interface on another computer or electronic device, such as a mobile device.

[0083] In some embodiments, autonomous vehicle 1500 includes one or more network interfaces, such as network interface 1562, suitable for communication with one or more networks 1570 (e.g., a local area network (LAN), a wide area network (WAN), a wireless network, and / or the Internet, among others), which may allow communication of information with other computers and electronic devices, including, for example, a central service such as a cloud service from which autonomous vehicle 1500 receives environmental and other data used for its autonomous control. In some embodiments, data collected by one or more sensors 1533A-1533I may be uploaded via network 1570 to computing system 1572 for further processing. In such embodiments, a timestamp may be associated with each instance of vehicle data before uploading.

[0084] 15c and various additional controllers and subsystems disclosed herein generally operate under the control of an operating system and execute or rely on various computer software applications, components, programs, objects, modules, or data structures, as described in more detail below. Additionally, the various applications, components, programs, objects, or modules may also execute on one or more processors of other computers coupled to the autonomous vehicle 1500 via a network 1570, such as in a distributed, cloud-based, or client-server computing environment, such that the processing required to implement the functionality of a computer program is allocated across multiple computers and / or services via the network.

[0085] The routines executed to implement the various embodiments described herein, whether embodied as part of an operating system, a particular application, component, program, object, module, or sequence of instructions, or any subset thereof, are referred to herein as "program code." Program code typically resides at different times in various memory and storage devices and comprises one or more instructions that, when read and executed by one or more processors, perform the steps necessary to perform the steps or elements embodying various aspects of the present disclosure. Furthermore, while embodiments are described and illustrated below in the context of fully functional computers and systems, it will be understood that the various embodiments described herein can be distributed as program products in various forms, and that the embodiments can be embodied independently of the particular type of computer-readable medium used to effect such distribution. Examples of computer-readable media include, among others, tangible, non-transitory media such as volatile and non-volatile memory devices, floppy and other removable disks, solid-state drives, hard disk drives, magnetic tape, and optical disks (e.g., CD-ROMs, DVDs, etc.).

[0086] Additionally, various program code described below may be identified based on the application for which it is embodied in a particular embodiment. However, it should be understood that any particular program nomenclature below is used merely for convenience, and thus the present invention should not be limited to use with only any particular application identified and / or implied by such nomenclature. Furthermore, given the typically infinite number of ways in which computer programs can be organized into routines, procedures, methods, modules, objects, etc., and the various ways in which program functions are allocated among the various software layers (e.g., operating system, libraries, APIs, applications, applets, etc.) resident within a typical computer, it should be understood that the present invention is not limited to the specific organization and allocation of program functions described herein.

[0087] Those skilled in the art having the benefit of this disclosure will recognize that the exemplary environment shown in Figure 15c is not intended to limit the embodiments disclosed herein. Indeed, those skilled in the art will recognize that other alternative hardware and / or software environments may be used without departing from the scope of the embodiments disclosed herein.

[0088] The term "processing logic" (e.g., processing logic 1522) in this disclosure may include one or more processors, microprocessors, multi-core processors, ASICs, and / or FPGAs for performing the operations disclosed herein. In some embodiments, memory (not shown) is integrated with the processing logic for storing instructions for performing operations and / or storing data. Additionally, the processing logic may include analog or digital circuitry for performing operations according to embodiments of the present disclosure.

[0089] "Memory" or "memories" as described in this disclosure may include one or more volatile or non-volatile memory architectures. "Memory" or "memories" may be removable and non-removable media embodied in any method or technology for storing information such as computer-readable instructions, data structures, program modules, or other data. Exemplary memory technologies may include RAM, ROM, EEPROM, flash memory, CD-ROM, DVD (Digital Versatile Disk), high-definition multimedia / data storage disks or other optical storage devices, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices or any other non-transmitting medium that can be used to store information for access by a computing device.

[0090] The network may include any network or network system, including, but not limited to, a peer-to-peer network, a local area network (LAN), a wide area network (WAN), a public network such as the Internet, a private network, a cellular network, a wireless network, a wired network, a combined wired and wireless network, and a satellite network.

[0091] The communication channel may include or be routed by one or more wired or wireless communications utilizing the IEEE 802.11 protocol, Serial Peripheral Interface (SPI), Inter-Integrated Circuit (I2C), Universal Serial Port (USB), Controller Area Network (CAN), cellular data protocols (e.g., 3G, 4G, LTE, 5G), optical communications networks, Internet Service Providers (ISPs), peer-to-peer networks, LANs, WANs, public networks (e.g., the "Internet"), private networks, satellite networks, or others.

[0092] The computing device may include a desktop computer, a laptop computer, a tablet, a phablet, a smartphone, a feature phone, a server computer, or others. The server computer may be located remotely in a data center or stored locally.

[0093] The aforementioned processes are described in terms of computer software and hardware. The described techniques may be embodied in a tangible or non-transitory machine (e.g., computer) readable storage medium and constitute machine-executable instructions that, when executed by a machine, cause the machine to perform the described operations. Furthermore, the processes may be embodied in hardware such as an ASIC.

[0094] A tangible, non-transitory, machine-readable storage medium includes any mechanism that provides (e.g., stores) information in a form accessible by a machine (e.g., a computer, a network device, a personal digital assistant, a manufacturing tool, any device having one or more processor sets, etc.). For example, machine-readable storage media include recordable / non-recordable media (e.g., ROM, RAM, magnetic disk storage media, optical storage media, flash memory devices, etc.).

[0095] The foregoing description of illustrated embodiments of the invention, including what is described in the Abstract, is not intended to be exhaustive or to limit the invention to the precise forms disclosed. While specific embodiments of, and examples for, the invention are described herein for illustrative purposes, various modifications are possible within the scope of the invention, as will be recognized by those of ordinary skill in the relevant art.

[0096] Such modifications to the invention can be made in light of the foregoing detailed description. The terms used in the following claims should not be construed to limit the invention to the specific embodiments disclosed herein. Rather, the scope of the invention is to be determined entirely by the following claims, which are to be construed in accordance with established doctrines of claim interpretation.

Claims

1. 1. A method of assembling an optical structure for a light detection and ranging (LIDAR) system, comprising: forming a trench and one or more support pedestals in the wafer; forming a plurality of solder deposits on the surfaces of the trench; placing the chips on the wafer by positioning the chips relative to the one or more supports such that the solder deposits do not contact the chips when they are initially placed on the wafer; reflowing the solder deposit to form a plurality of joints each contacting the chip; A method comprising:

2. The method of claim 1 , wherein the solder deposit has a height less than the one or more support pedestals before being reflowed.

3. 2. The method of claim 1, further comprising providing a plurality of under bump metal (UBM) pads on a surface of the trench, the solder deposits being formed on the respective UBM pads.

4. The method of claim 3 , wherein the UBM pads are smaller in diameter than the solder deposits formed thereon.

5. 5. The method of claim 4, further comprising the step of pressing said solder deposit to flatten said solder deposit from a ball shape to a coin shape.

6. 5. The method of claim 4, wherein reflowing the solder deposits includes heating the solder deposits so that they gather on the UBM pads and rise in height to reach the chip.

7. The method of claim 1 , wherein the step of forming the plurality of solder deposits is performed by laser jetting, screening, or electroplating.

8. The method of claim 1 , wherein the one or more support stages are configured to mechanically support the chips and provide alignment for positioning the chips relative to the wafer.

9. The method of claim 1 , wherein the step of placing the chip on the wafer includes using a flip-chip bonder.

10. The method of claim 1 further comprising encapsulating the optical structure with a capping wafer.

11. The method of claim 10 , wherein sealing the optical structure is performed in a vacuum or inert atmosphere to provide a hermetic seal of the optical structure.

12. The method of claim 10 further comprising providing a lens in the capping wafer.

13. The method of claim 1 , wherein the wafer comprises a photonic integrated circuit (PIC) wafer.

14. The method of claim 13 , wherein the chip comprises a semiconductor optical amplifier (SOA) chip.

15. 15. The method of claim 14, wherein the one or more support pedestals are formed at a height that achieves vertical alignment of a laser beam propagating between the SOA chip and the PIC wafer.

16. providing an edge coupler on the PIC wafer, the edge coupler configured to transmit laser light between the PIC wafer and the SOA chip; aligning ports of the SOA chip to the edge couplers on the PIC wafer; 15. The method of claim 14, further comprising:

17. The method of claim 1 further comprising forming an input grating coupler on the wafer.

18. 20. The method of claim 17, further comprising forming one or more output grating couplers in the wafer.

19. 20. The method of claim 18, wherein the one or more output grating couplers are positioned deeper into the wafer than the input grating couplers.

20. The method of claim 1 further comprising providing wire bond pads on one or more edges of the wafer.

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