Device structure

Abstract

An optical beam splitter includes a multi-order nested network of waveguide furcation branches including each first order waveguide furcation branch including a pair of first order waveguide sections and each second stage waveguide furcation branch including a pair of second order waveguide sections. Each pair of first order waveguide sections includes a first common end, a pair of first split ends, and a pair of first interconnects. Each first common end points to a first width direction. Each pair of second order waveguide sections includes a second common end and a pair of second split ends and a pair of second interconnects. Each second common end and each second split end of the optical beam splitter point to a second width direction, and the second width direction is opposite to the first width direction.

Description

Technical Field

[0001] Embodiments of the present disclosure relate to semiconductor technology, and more particularly to a device structure having an optical beam splitter. Background Art

[0002] The waveguide fan-out structure for an optical device may occupy a large portion of the overall coverage area of the device. To reduce the overall coverage area of the device, it is necessary to reduce the coverage area of the waveguide fan-out structure. Summary of the Utility Model

[0003] A device structure includes an optical beam splitter, wherein the optical beam splitter includes a multi-stage nested network of waveguide bifurcation branches. The multi-stage nested network of waveguide bifurcation branches includes: a plurality of first-stage waveguide bifurcation branches, each first-stage waveguide bifurcation branch including a pair of first-stage waveguide segments, wherein each pair of first-stage waveguide segments includes a first common end and a pair of first split ends and a pair of first interconnecting portions, the first interconnecting portions connecting the first common end to respective ones of the first split ends within the first split ends, wherein each first common end of the optical beam splitter points in a first width direction of the optical beam splitter, and each first interconnecting portion of the optical beam splitter includes respective first outwardly convex sidewall segments, the first outwardly convex sidewall segments generally facing a second width direction, the second width direction being opposite to the first width direction; and a plurality of second-stage waveguide bifurcation branches, each second-stage waveguide bifurcation branch including a pair of second-stage waveguide segments, wherein each pair of second-stage waveguide segments includes a second common end and a pair of second split ends and a pair of second interconnecting portions, the second interconnecting portions connecting the second common end to respective ones of the second split ends within the second split ends. In some embodiments, in a planar view, the total angular propagation direction change within each of the first interconnecting portions of the optical beam splitter is no greater than 180 degrees.

[0004] In some embodiments, the first-stage waveguide bifurcation branches include a plurality of optical channels connected to a plurality of optical ports; each of the optical ports is nested within the multi-stage nested network of the waveguide bifurcation branches in respective horizontal directions; and each bending segment of the first interconnecting portions of the optical beam splitter has a respective first inwardly convex sidewall segment, the first inwardly convex sidewall segment having a first radius of curvature.

[0005] In some embodiments, each bending segment of the second interconnecting portions of the optical beam splitter has a respective second inwardly convex sidewall segment, the second inwardly convex sidewall segment having a second radius of curvature; and each of the second interconnecting portions of the optical beam splitter has a pair of bending segments, the bending segments each having a total angular propagation direction change of 90 degrees and a straight-line segment connecting the pair of bending segments.

[0006] In some embodiments, the multi - order nested network of the entire waveguide bifurcation branches consists of a single continuous waveguide structure that has a uniform height throughout.

[0007] In some embodiments, the device structure includes a first die that includes: a plurality of first dielectric material layers in which the multi - order nested network of the waveguide bifurcation branches is formed; a plurality of optical devices optically connected to respective first split ends of the first - order waveguide bifurcation branches; and a plurality of first metal interconnect structures electrically connected to a plurality of electrical nodes of the optical devices and formed within the first dielectric material layers.

[0008] A device structure includes an optical beam splitter, where the optical beam splitter includes a multi - order nested network of waveguide bifurcation branches. For each of at least two consecutive positive integers i that include 1 and 2, the multi - order nested network of waveguide bifurcation branches includes: a plurality of (2i - 1) - th order waveguide bifurcation branches, each (2i - 1) - th order waveguide bifurcation branch including a pair of (2i - 1) - th order waveguide segments, where each pair of (2i - 1) - th order waveguide segments includes a (2i - 1) - th common end and a pair of (2i - 1) - th split ends and a pair of (2i - 1) - th interconnect portions that connect the (2i - 1) - th common end to respective (2i - 1) - th split ends within the pair of (2i - 1) - th split ends, where each (2i - 1) - th common end of the optical beam splitter points in a first width direction of the optical beam splitter, and each (2i - 1) - th interconnect portion of the optical beam splitter includes a respective (2i - 1) - th outwardly convex sidewall segment that generally faces a second width direction, the second width direction being opposite to the first width direction; and a plurality of 2i - th order waveguide bifurcation branches, each 2i - th order waveguide bifurcation branch including a pair of 2i - th order waveguide segments, where each pair of 2i - th order waveguide segments includes a 2i - th common end and a pair of 2i - th split ends and a pair of 2i - th interconnect portions that connect the 2i - th common end to respective 2i - th split ends within the pair of 2i - th split ends, where each 2i - th split end of the optical beam splitter is connected to a respective (2i - 1) - th common end of the (2i - 1) - th order waveguide bifurcation branches, and where each 2i - th common end and each 2i - th split end of the optical beam splitter point in the second width direction of the optical beam splitter.

[0009] In some embodiments, each of the first-order waveguide bifurcation branches has a first lateral range along a length direction of the optical beam splitter, the length direction being perpendicular to the first width direction; each of the second-order waveguide bifurcation branches has a second lateral range along the length direction, the second lateral range being greater than the first lateral range; and each of the third-order waveguide bifurcation branches has a third lateral range along the length direction, the third lateral range being greater than the second lateral range.

[0010] In some embodiments, the third lateral range is greater than twice the second lateral range.

[0011] In some embodiments, the first lateral range is greater than half of the third lateral range.

[0012] At least one embodiment of the present utility model has the following advantages or technical effects: It can reduce the overall footprint of the waveguide fan-out structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The various aspects of the present disclosure will be described in detail below in conjunction with the accompanying drawings. It should be noted that, in accordance with standard practices in the industry, the various components are not drawn to scale and are only used for illustration. In fact, the dimensions of the elements can be arbitrarily enlarged or reduced to clearly show the components of the embodiments of the present disclosure.

[0014] Figures 1A to 1C is a vertical cross-sectional view showing a manufacturing process for forming a first die in accordance with an embodiment of the present disclosure. Figure 1D is Figure 1A a top view of the structure of

[0015] Figures 2A to 2B is a vertical cross-sectional view showing a manufacturing process for forming a second die in accordance with an embodiment of the present disclosure.

[0016] Figure 3 is a vertical cross-sectional view showing a bonded assembly in accordance with an embodiment of the present disclosure.

[0017] Figures 4A to 4D is a sequential vertical cross-sectional view of the region corresponding to region M in Figure 3 during the manufacturing process.

[0018] Figures 5A to 5C is Figure 4B various top views of a portion of the optical beam splitter after the process step of Figure 5A The vertical section X-X' in Figure 4B corresponds to the plane of the vertical section in

[0019] Figure 6 According to an embodiment of the present disclosure, a flowchart showing a series of process steps that can be used to fabricate a device structure is illustrated.

[0020] The reference numerals are explained as follows:

[0021] 9: Carrier substrate

[0022] 10: First dielectric material layer

[0023] 20: Optical beam splitter

[0024] 20L: Waveguide material layer

[0025] 27: Photoresist layer

[0026] 40: Optical device

[0027] 100: First die

[0028] 180: First metal interconnect structure

[0029] 198: First metal bonding pad

[0030] 200: Second die

[0031] 201: Semiconductor substrate

[0032] 202: Source region

[0033] 205: Gate electrode

[0034] 208: Drain region

[0035] 210: Field effect transistor

[0036] 230: Second dielectric material layer

[0037] 240: Control circuit / semiconductor device

[0038] 280: Second metal interconnect structure [[ID=6l]]

[0039] 298: Second metal bonding pad

[0040] 300: Third die

[0041] 398: Third metal bonding pad

[0042] 610 / 6ll: Steps

[0043] DC / DC’: Cutting channel

[0044] icss1 / icss2 / icss3: Inner convex sidewall section

[0045] ld1 / ld2: Length direction

[0046] LSS: Length of the straight section

[0047] M: Area

[0048] ocss1 / ocss2 / ocss3: Outer convex sidewall section

[0049] R1 / R2 / R3 / R4 / R5 / R6: Radius of curvature

[0050] VP1 / VP2: Vertical plane

[0051] wd1 / wd2: Width direction

[0052] WS: Spacing between adjacent waveguide section pairs

[0053] WW: Width of the waveguide section

[0054] 2T: 2 channels

[0055] 4T: 4 channels

[0056] 8T: 8 channels

[0057] 16T: 16 channels

[0058] A: Common port

[0059] B: Connected to the adjacent group of 16 channels

[0060] C: Connected to the adjacent group of 32 channels

[0061] 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16: Optical ports

[0062] 20A: First-order waveguide bifurcation branch

[0063] 20B: Second-order waveguide bifurcation branch

[0064] 20C: Third-order waveguide bifurcation branch

[0065] 20D: Fourth-order waveguide bifurcation branch

[0066] 1S: First splitting end

[0067] 2S: Second splitting end

[0068] 3S: Third splitting end

[0069] 4S: Fourth splitting end

[0070] 1C: First common end

[0071] 2C: Second common terminal

[0072] 3C: Third common terminal

[0073] 4C: Fourth common terminal

[0074] 1I: First Internet Department

[0075] 2I: Second Interconnection Department

[0076] 3I: Third Internet Department

[0077] 4I: Fourth Interconnection Department. DETAILED DESCRIPTION

[0078] The following disclosure provides many embodiments or examples for implementing different elements of the subject matter provided. Specific examples of each element and its configuration are described below to simplify the description of the embodiments of the present disclosure. Of course, these are merely examples and are not intended to limit the embodiments of the present disclosure. For example, if the description refers to a first element formed on a second element, it may include an embodiment in which the first and second elements are in direct contact, and it may also include an embodiment in which an additional element is formed between the first and second elements so that they are not in direct contact. In addition, the embodiments of the present disclosure may repeat reference numbers and / or letters in various examples. Such repetition is for the purpose of simplicity and clarity, and is not intended to indicate the relationship between the different embodiments and / or configurations discussed.

[0079] Furthermore, spatially relative terms such as "under," "below," "lower," "above," "higher," and the like may be used to facilitate description of the relationship between one (or some) component or parts and another (or some) component or parts in the accompanying drawings. Spatially relative terms are used to include different orientations of the device in use or operation, as well as the orientations described in the accompanying drawings. When the device is turned to a different orientation (rotated 90 degrees or other orientations), the spatially relative adjectives used therein will also be interpreted based on the orientation after turning. Unless otherwise expressly stated, elements with the same reference number refer to the same element and are assumed to have the same material composition and the same thickness range. As used herein, an element or system "configured for" a function or operation, or "configured to" provide or perform a function or operation, refers to an element or system equipped with hardware and applicable software to provide such function or such operation as described in this disclosure, and if any details of such hardware or such software are not expressly described herein, they are known to those of ordinary skill in the art.

[0080] Embodiments of the present disclosure provide a high-channel density waveguide fan-out structure using a nested enveloping bifurcation structure. The waveguide fan-out structure can provide an optical connection between optical devices and / or optical input / output ports in a configuration where the waveguide path surrounds the connection points to the optical devices and / or optical input / output ports. The bifurcation structure connected to a smaller number of optical ports or optical devices can be nested within the bifurcation structure connected to a larger number of optical ports or optical devices to provide an enveloping configuration and reduce the overall footprint of the waveguide fan-out structure. The various embodiments of the waveguide fan-out structure disclosed herein can be used to form compact optical devices. Various aspects of the present disclosure will now be described with reference to the accompanying drawings.

[0081] Figures 1A to 1C is a vertical cross-sectional view showing a manufacturing process for forming a first die 100, according to an embodiment of the present disclosure. Figure 1D is Figure 1A a top view of the structure of.

[0082] Reference Figure 1A and Figure 1D, a two-dimensional array of first grains 100 can be formed on a carrier substrate 9. The carrier substrate 9 can include any substrate that can subsequently be removed. For example, the carrier substrate 9 can include a semiconductor substrate, an insulating substrate, or a conductive substrate. Each first grain 100 can include at least one optical beam splitter 20 and an optical device 40. The optical device 40 can be any type of optical device known in the art and can include one or more of silicon photonic devices, optical switches, optical amplifiers, optical filters, optical modulators, photodetectors, and non-branching waveguides. An optical beam splitter is a device that can be used to split an incident light beam into two or more separate light beams, or can be used to combine two or more separate light beams into a superposed output light beam. In some embodiments, the two or more separate light beams can be separated at a specific intensity ratio and propagation direction. Optical beam splitters can be used for signal routing, beam combination, interferometry, and optical power distribution. According to one aspect of the present disclosure, the optical beam splitter 20 can be formed with a geometry that provides beam splitting and / or beam combination in a manner that minimizes the lateral extent of each optical beam splitter 20 in the width direction, while increasing the routing distribution density within the respective rectangular regions occupied by the respective optical beam splitters 20. The construction of the optical beam splitter 20 is described in detail subsequently.

[0083] The optical beam splitter 20 and the optical device 40 can be formed above the carrier substrate 9. The first metal interconnect structure 180 can be formed in the first dielectric material layer 10. In some embodiments, a first subset of the first metal interconnect structure 180 can be formed as components of the optical device 40, and a second subset of the first metal interconnect structure 180 can be used to provide metal wiring for the optical device 40. The first metal bonding pad 198 can be formed on the top level of the first dielectric material layer 10. The first metal bonding pad 198 can be configured for metal-to-metal bonding, controlled collapse chip connection (C4) bonding with controllable collapse welding height, or micro-bump bonding (also known as C2 bonding).

[0084] Reference Figure 1B , the carrier substrate 9 can be removed. For example, the carrier substrate 9 can be removed by cleaving the carrier substrate 9 from the first dielectric material layer 10 and the components of the structures formed therein. Alternatively, the carrier substrate 9 can be removed by backside grinding, polishing, anisotropic etching processes, and / or isotropic etching processes.

[0085] Reference Figure 1C , the two-dimensional array of the first dies 100 can be diced along the dicing channels (DC) to provide a plurality of first dies 100. Each first die 100 can include an optical device 40 formed in the first dielectric material layer 10, at least one optical beam splitter 20, a first metal interconnect structure 180, and a first metal bonding pad 198.

[0086] Figures 2A to 2B is a vertical cross-sectional view illustrating a manufacturing process for forming a second die 200 according to an embodiment of the present disclosure.

[0087] Reference Figure 2A, a two-dimensional array of semiconductor dies 200 can be formed on a semiconductor substrate 201. Each semiconductor die 200 includes a control circuit 240 configured to control the operation of the optical device 40 in the first die 100 after bonding. The control circuit 240 may include field-effect transistors, such as complementary metal-oxide-semiconductor (CMOS) field-effect transistors. Each control circuit 240 may include a frequency tuner controller circuit and a current switch circuit, which will be described in detail in subsequent paragraphs. In addition, each second die 200 may include a second dielectric material layer 230 in which a second metal interconnect structure 280 is formed. A first subset of the second metal interconnect structure 280 may be used to provide electrical interconnections to the field-effect transistors of the control circuit 240, and a second subset of the second metal interconnect structure 280 may be used to provide electrical interconnections between the control circuit 240 and respective sets of second metal pads 298 located at the topmost layer of the second dielectric material layer 230. A subset of the second metal bonding pads 298 may have a pattern corresponding to the pattern of the first metal bonding pads 198 in the first die 100. The second metal bonding pads 298 may be configured for metal-to-metal bonding, controlled collapse chip connection (C4) bonding with controllable collapse welding height, or microbump bonding (also known as C2 bonding).

[0088] Reference Figure 2B , the two-dimensional array of second dies 200 can be diced along a dicing channel DC’ to provide a plurality of second dies 200. Generally, each second die 200 includes a control circuit 240 containing semiconductor devices, a second metal interconnect structure 280 formed within the second dielectric material layer 230, and second metal pads 298. The control circuit 240 including semiconductor devices such as field-effect transistors (not explicitly shown) and is configured to provide control signals to the optical device 40 in the first die 100. In one embodiment, each second die 200 includes a semiconductor substrate 201, semiconductor devices 240 located on the semiconductor substrate, a second metal interconnect structure 280 formed within the second dielectric material layer 230, and second metal pads 298 electrically connected to the second metal interconnect structure 280.

[0089] Reference Figure 3, the second metal bonding pad 298 of the second die 200 can be bonded to the first metal bonding pad 198 of the first die 100 to attach the first die 100 to the second die 200. Generally, the first die 100 can be a photon die including an optical device 40 and a non-branching waveguide (not explicitly shown) for guiding a photon propagation path. In addition, the first die 100 includes at least one optical beam splitter 20 of the present disclosure. The second die 200 includes a semiconductor die that includes semiconductor devices such as field effect transistors. The second die 200 includes a control circuit for controlling the operation of the optical device 40. Control signals can be transmitted across the first die 100 and the second die 200 through a conductive path of respective bonded pairs including the first metal bonding pad 198 and the second metal bonding pad 298. Although various embodiments can be described such that the second metal bonding pad 298 is bonded to the first metal bonding pad 198 via metal-to-metal bonding to provide a conductive path extending across the first die 100 and the second die 200, other embodiments are explicitly contemplated herein where the conductive path includes a bonding structure including solder balls. Optionally, an additional die such as a third die 300 can be attached to the second die 200. The third die 300 can include a semiconductor die including at least one field effect transistor therein. The third die 300 can include a logic die, a memory die, a passive device die, or any other type of semiconductor die. The third die 300 can include a third metal bonding pad 398 that is bonded to a subset of the second metal bonding pads 298 in the second die 200.

[0090] Figures 4A to 4D corresponds to during a manufacturing process Figure 3 successive vertical cross-sectional views of the region in region M. Figures 4A to 4D The manufacturing process shown can be used to provide Figure 1A the exemplary structure shown.

[0091] Referring to Figure 4A , a first dielectric material layer 10 can be formed over a carrier substrate 9. The first dielectric material layer 10 includes a dielectric material such as silicon oxide. The thickness of the first dielectric material layer 10 can range from 0.5 micrometers to 10 micrometers, such as from 1 micrometer to 5 micrometers, but smaller and larger thicknesses can also be used.

[0092] The waveguide material layer 20L can be deposited over the first dielectric material layer 10 as a blanket material layer with a uniform thickness. The waveguide material layer 20L includes a material having a refractive index higher than that of the material of the first dielectric material layer 10. For example, in an embodiment where the first dielectric material layer 10 includes silicon oxide, the waveguide material layer 20L can include silicon or silicon nitride. The thickness of the waveguide material layer 20L can range from 100 nanometers (nm) to 500 nm, but smaller and larger thicknesses can also be used.

[0093] The photoresist layer 27 can be applied over the waveguide material layer 20L and can be lithographically patterned into the pattern of the subsequently formed optical beam splitter. The pattern of the optical beam splitter is described in detail below.

[0094] Reference Figure 4B and Figures 5A to 5C , the pattern in the photoresist layer 27 can be transferred to the waveguide material layer 20L by performing an anisotropic etching process. Figures 5A to 5C is various top views of a portion of the optical beam splitter after the process step of Figure 4B . The photoresist layer 27 can be used as an etching mask layer, and the waveguide material layer 20L can be patterned into the optical beam splitter 20 and waveguides (not explicitly shown). Figure 5C Illustrates the position of the optical device 40 that will be formed in subsequent process steps. Subsequently, the photoresist layer 27 can be removed, for example, by ashing. The width of each segment of each optical beam splitter 20 can be uniform throughout and can range from 100 nm to 500 nm, but smaller and larger widths can also be used.

[0095] Each optical beam splitter 20 includes a multi-stage nested network of waveguide bifurcation branches. Thus, Figure 4A the waveguide material layer 20L can form a multi-stage nested network of waveguide bifurcation branches. As used herein, a waveguide bifurcation branch refers to a portion of a waveguide structure that includes a bifurcation structure. As used herein, a network of waveguide bifurcation branches refers to a plurality of waveguide bifurcation branches interconnected as a network. As used herein, a nested network refers to a network having a nested configuration, that is, a configuration in which one element is within the region or volume of another element. As used herein, a multi-stage network refers to a network that includes at least two stages, that is, a network that includes at least a first interconnection that travels to and from a first unit and a second interconnection that travels to and from a second unit, each second unit including a plurality of first units.

[0096] According to one aspect of the present disclosure, the multi - order nested network of waveguide bifurcation branches within each optical beam splitter 20 includes first - order waveguide bifurcation branches 20A, each first - order waveguide bifurcation branch 20A including a pair of first - order waveguide segments, and second - order waveguide bifurcation branches 20B, each second - order waveguide bifurcation branch 20B including a pair of second - order waveguide segments. As used herein, a "waveguide segment" refers to a segment of a structure that serves as a waveguide, that is, a structure that guides light waves.

[0097] Each pair of first - order waveguide segments includes a first common end 1C and a pair of first split ends 1S and a pair of first interconnection portions 1I, the first interconnection portions 1I connecting the first common end 1C to respective first split ends 1S within the pair of first split ends 1S. Each first common end 1C and each first split end 1S of the optical beam splitter 20 point in the first width direction wd1 of the optical beam splitter 20. As used herein, an element "points" in a specified direction if a vector representing the propagation direction of the element is parallel to the specified direction.

[0098] Each first interconnection portion 1I of the optical beam splitter 20 includes a respective first outwardly convex sidewall segment ocss1, the first outwardly convex sidewall segment ocss1 generally facing the second width direction wd2, which is opposite to the first width direction wd1. As used herein, an element "generally faces" a specified direction if the element is observable to an observer located in the specified direction and not observable to another observer located in the opposite direction of the specified direction. Thus, an element that generally faces a specified direction is physically exposed to the specified direction.

[0099] Each pair of second - order waveguide segments includes a second common end 2C and a pair of second split ends 2S and a pair of second interconnection portions 2I, the second interconnection portions 2I connecting the second common end 2C to respective second split ends 2S within the pair of second split ends 2S. Each second split end 2S of the optical beam splitter 20 is connected to the respective first common end 1C of the first - order waveguide bifurcation branch 20A. Each second common end 2C and each second split end 2S of the optical beam splitter 20 point in the second width direction wd2 of the optical beam splitter 20. In one embodiment, each second interconnection portion 2I of the optical beam splitter 20 includes a respective second outwardly convex sidewall segment ocss2, the second outwardly convex sidewall segment ocss2 generally facing the first width direction wd1.

[0100] Each pair of third-order waveguide sections includes a third common end 3C, a pair of third split ends 3S, and a pair of third interconnects 3I that connect the third common end 3C to respective third split ends 3S within the pair of third split ends 3S. Each third split end 3S of the optical splitter 20 is connected to a respective second common end 2C of the second-order waveguide bifurcated branch 20B. Each third common end 3C and each third split end 3S of the optical splitter 20 point in the first width direction wd1 of the optical splitter 20. In one embodiment, each third interconnect 3I of the optical splitter 20 includes a respective third outwardly convex sidewall section ocss3 that generally faces the second width direction wd2.

[0101] Each pair of fourth-order waveguide sections includes a fourth common end 4C, a pair of fourth split ends 4S, and a pair of fourth interconnects 4I that connect the fourth common end 4C to respective fourth split ends 4S within the pair of fourth split ends 4S. Each fourth split end 4S of the optical splitter 20 is connected to a respective third common end 3C of the third-order waveguide bifurcated branch 20C. Each fourth common end 4C and each fourth split end 4S of the optical splitter 20 point in the second width direction wd2 of the optical splitter 20. In one embodiment, each fourth interconnect 4I of the optical splitter 20 includes a respective fourth outwardly convex sidewall section that generally faces the first width direction wd1.

[0102] Generally, for each integer j not greater than the highest order K within the optical splitter 20, each pair of jth-order waveguide sections includes a jth common end, a pair of jth split ends, and a pair of jth interconnects that connect the jth common end to respective jth split ends within the pair of jth split ends. Each jth split end of the optical splitter 20 is connected to a respective (j - 1)th common end of the (j - 1)th-order waveguide bifurcated branch. If j is odd, each jth common end and each jth split end of the optical splitter 20 point in the first width direction wd1, or if j is even, they point in the second width direction wd2. In one embodiment, each jth interconnect of the optical splitter 20 includes a respective jth outwardly convex sidewall section that generally faces the second width direction wd2 if j is odd, or generally faces the first width direction wd1 if j is even.

[0103] According to one aspect of the present disclosure, multi-order waveguide sections can be provided within each optical splitter 20. In Figure 5A and Figure 5BIn the portion of the optical beam splitter 20 shown, the optical beam splitter 20 includes eight first-order waveguide segments, four second-order waveguide segments, two third-order waveguide segments, and one fourth-order waveguide segment. Each first-order waveguide segment includes two optical channels 2T that can be connected to two optical ports. Each second-order waveguide segment includes four optical channels 4T that can be connected to four optical ports. Each third-order waveguide segment includes eight optical channels 8T that can be connected to eight optical ports. Each fourth-order waveguide segment includes sixteen optical channels 16T that can be connected to sixteen optical ports. The fourth-order waveguide segment shown can be connected to a neighboring set of sixteen optical channels included within another fourth-order waveguide segment (denoted by B in the figure as the neighboring set connected to sixteen channels). Two fourth-order waveguide segments together form a fifth-order waveguide segment that includes thirty-two optical channels. The fifth-order waveguide segment can be connected to a neighboring fifth-order waveguide segment that includes an additional thirty-two optical channels (denoted by C in the figure as the neighboring set connected to thirty-two channels). Two fifth-order waveguide segments form a sixth-order waveguide segment, and so on.

[0104] Generally, a j-th order waveguide segment can be provided that includes 2 j optical channels, and the integer j can be any positive integer less than K + 1. In this embodiment, 2 K optical channels can be set within the optical beam splitter 20. The common end of the K-th order waveguide segments can be connected to a common port A. If the optical beam splitter 20 is used to split an input light beam, the common port A can be an optical input port. Alternatively, in an embodiment where the optical beam splitter 20 is used in the reverse mode (i.e., the light beam combining mode) to combine optical inputs from 2K optical ports (which serve as optical input ports) into a single output light beam provided at the common port A, the common port A can be an optical output port.

[0105] In one embodiment, each first interconnect portion 1I of the optical beam splitter 20 includes respective first inner convex sidewall segments icssl that generally face a first width direction wdl. In a top view, each first inner convex sidewall segment icss1 can be included within a segment of a vertical cylindrical surface having a first radius of curvature R1. As seen in the top view, the total azimuthal extension angle of each first inner convex sidewall segment icss1 around the radius center of its respective first inner cylindrical sidewall segment icss1 can range from 30 degrees to 180 degrees, such as from 60 degrees to 150 degrees, although smaller and larger total azimuthal extension angles can also be used. The first radius of curvature R1 can range from 1 micron to 10 microns, for example from 2 microns to 5 microns, but smaller and larger dimensions can also be used.

[0106] In one embodiment, each second interconnect portion 2I of the optical beam splitter 20 includes respective second inner convex sidewall segments icss2 that generally face the second width direction wd2, which is a direction opposite to the first width direction wd1. In one embodiment, each second interconnect portion 2I of the optical beam splitter 20 includes a respective pair of second outer convex sidewall segments ocs2 that generally face the first width direction wd1. A pair of second inner convex sidewall segments icss2 of each second interconnect portion 2I may be connected to each other by a straight waveguide segment extending along the length direction of the optical beam splitter 20, which may be the first length direction ld1 or the second length direction ld2 opposite to the first length direction ld1.

[0107] In one embodiment, each bent segment of the first interconnect portion 1I of the optical beam splitter 20 has a respective first inner convex sidewall segment icss1 that has a first radius of curvature R1. As seen in a top view, the total azimuthal extension angle of each first inner convex sidewall segment icss1 around the radius center of its respective first inner cylindrical sidewall segment icss1 may range from 30 degrees to 180 degrees, such as from 60 degrees to 150 degrees, although smaller and larger total azimuthal extension angles may also be used. Generally, in a plan view, the total angular propagation direction change within each first interconnect portion 1I of the optical beam splitter 20 is not greater than 180 degrees. As used herein, a plan view refers to a schematic view along a vertical direction perpendicular to both the first length direction ld1 and the first width direction wd1. The total angular propagation direction change refers to the total angular change in the propagation direction of a segment of the waveguide structure.

[0108] Generally, the optical beam splitter 20 is a waveguide structure configured to allow beam splitting or combining. The optical beam splitter 20 may be entirely within a rectangular region between a first vertical plane VP1 and a second vertical plane VP2, where the first vertical plane VP1 is perpendicular to the first width direction wd1, parallel to the first length direction ld1, and contacts the outer sidewall of the highest-order waveguide bifurcation branch, and the second vertical plane VP2 is parallel to the first vertical plane VP1 and contacts the outer sidewall of the second-highest-stage waveguide bifurcation branch.

[0109] In a top view, each second inner convex sidewall section icss2 can be included within a section of a vertical cylindrical surface having a second radius of curvature R2. In one embodiment, the second radius of curvature R2 can be the same as the first radius of curvature R1. As seen in the top view, the total azimuthal extension angle of each second inner convex sidewall section icss2 around the radius center of its respective second inner cylindrical sidewall section icss2 can be 90 degrees. Generally speaking, in a plan view, the total angular propagation direction change within each second interconnect 2I of the optical beam splitter 20 can be 180 degrees.

[0110] In one embodiment, each curved section of the first interconnect 1I of the optical beam splitter 20 has its respective first inner convex sidewall section icss1, and the first inner convex sidewall section icss1 has a first radius of curvature R1. In one embodiment, each curved section of the second interconnect 2I of the optical beam splitter 20 has its respective second inner convex sidewall section icss2, and the second inner convex sidewall section icss2 has a second radius of curvature R2. In one embodiment, each second interconnect 2I of the optical beam splitter 20 includes a pair of curved sections and a straight section connecting the pair of curved sections, and each curved section has a total angular propagation direction change of 90 degrees respectively. In one embodiment, each first interconnect 1I of the optical beam splitter 20 consists of its respective curved sections.

[0111] In one embodiment, the multi - order nested network of the entire waveguide bifurcation branches consists of a single continuous waveguide structure, and the single continuous waveguide structure has a uniform height throughout. In one embodiment, each first - order waveguide bifurcation branch 20A has a first lateral extent along the length direction of the optical beam splitter 20, and the length direction is perpendicular to the first width direction wd1. Each second - order waveguide bifurcation branch 20B has a second lateral extent along the length direction of the optical beam splitter 20. The second lateral extent is greater than the first lateral extent.

[0112] In one embodiment, the multi - order nested network of waveguide bifurcation branches within each optical beam splitter 20 can include third - order waveguide bifurcation branches 20C and fourth - order waveguide bifurcation branches 20D. Each third - order waveguide bifurcation branch 20C includes a pair of third - order waveguide sections, and each fourth - order waveguide bifurcation branch 20D includes a pair of fourth - order waveguide sections, and so on.

[0113] Generally speaking, for each of at least two consecutive positive integers i including 1 and 2, the optical beam splitter 20 may include a multi-stage nested network of waveguide bifurcating branches, which includes (2i - 1)-th order waveguide bifurcating branches, each of the (2i - 1)-th order waveguide bifurcating branches includes a pair of (2i - 1)-th order waveguide sections, and (2i)-th order waveguide bifurcating branches, each of the (2i)-th order waveguide bifurcating branches includes a pair of (2i)-th order waveguide sections. The total number L of integers within at least two consecutive integers i may be 2, 3, 4, 5, 6, 7, 8, 9, 10, etc. If the highest-order waveguide bifurcating branch in the optical beam splitter 20 is the K-th order waveguide bifurcating branch, the integer K may be 2L or 2L + 1.

[0114] Each pair of (2i - 1)-th order waveguide sections includes a (2i - 1)-th common end, a pair of (2i - 1)-th split ends, and a pair of (2i - 1)-th interconnecting portions, and the (2i - 1)-th interconnecting portions connect the (2i - 1)-th common end to respective (2i - 1)-th split ends within the pair of (2i - 1)-th split ends. Each (2i - 1)-th common end of the optical beam splitter 20 points in the first width direction wd1 of the optical beam splitter 20, and each (2i - 1)-th interconnecting portion of the optical beam splitter 20 includes a respective (2i - 1)-th outwardly convex sidewall section, and the (2i - 1)-th outwardly convex sidewall sections generally face the second width direction wd2, and the second width direction wd2 is opposite to the first width direction wd1.

[0115] Each pair of (2i)-th order waveguide sections includes a (2i)-th common end, a pair of (2i)-th split ends, and a pair of (2i)-th interconnecting portions, and the (2i)-th interconnecting portions connect the (2i)-th common end to respective (2i)-th split ends within the pair of (2i)-th split ends. Each (2i)-th split end of the optical beam splitter 20 is connected to the respective (2i - 1)-th common end of the (2i - 1)-th order waveguide bifurcating branch, wherein each (2i)-th common end and each (2i)-th split end of the optical beam splitter 20 point in the second width direction wd2 of the optical beam splitter 20.

[0116] In one embodiment, for each value of i that is not greater than K / 2, each (2i - 1)th interconnecting portion of the optical beam splitter 20 includes respective (2i - 1)th inner convex sidewall sections icss(2i - 1), and the (2i - 1)th inner convex sidewall sections icss(2i - 1) generally face the first width direction wd1. In one embodiment, for each value of i that is greater than 1 and not greater than K / 2, each (2i - 1)th interconnecting portion of the optical beam splitter 20 includes respective inner convex sidewall sections icss(2i - 1) (such as a pair of third inner convex sidewall sections icss3), and the inner convex sidewall sections icss(2i - 1) generally face the first width direction wd1. A pair of (2i - 1)th inner convex sidewall sections icss(2i - 1) of each (2i - 1)th interconnecting portion can be connected to each other by a straight waveguide section that extends along the length direction of the optical beam splitter 20, which can be the first length direction ld1 or the second length direction ld2.

[0117] As seen in the top view, for each value of i that is greater than 1 and not greater than K / 2, the total azimuthal extension angle of each (2i - 1)th inner convex sidewall section icss(2i - 1) around the radius center of its respective (2i - 1)th inner cylindrical sidewall section icss(2i - 1) can be 90 degrees. Each (2i - 1)th radius of curvature R(2i - 1) can be in the range of 1 micrometer to 10 micrometers, such as 2 micrometers to 5 micrometers, but smaller and larger sizes can also be used. In one embodiment, all the radii of curvature R(2i - 1) can be the same.

[0118] In one embodiment, for each value of i that is greater than 1 and not greater than K / 2, each 2i - th interconnecting portion of the optical beam splitter 20 includes respective 2i - th inner convex sidewall sections icss(2i), and the 2i - th inner convex sidewall sections icss(2i) generally face the second width direction wd2. In one embodiment, for each value of i that is not greater than K / 2, each 2i - th interconnecting portion of the optical beam splitter 20 includes respective inner convex sidewall sections icss(2i), and the inner convex sidewall sections icss(2i) generally face the second width direction wd2. A pair of 2i - th inner convex sidewall sections icss(2i) of each 2i - th interconnecting portion can be connected to each other by a straight waveguide section that extends along the length direction of the optical beam splitter 20, which can be the first length direction ld1 or the second length direction ld2.

[0119] As seen in the top view, for each value of i greater than 1 and not greater than K / 2, the total azimuthal extension angle of each 2i-th inner convex sidewall section icss(2i) about the radius center of its respective 2i-th inner cylindrical sidewall section icss(2i) can be 90 degrees. Each 2i-th radius of curvature R(2i) can be in the range of 1 micron to 10 microns, such as 2 microns to 5 microns, although smaller and larger sizes can also be used. In one embodiment, all the radii of curvature R(2i) can be the same and can be the same as the radius of curvature R(2i - 1).

[0120] In the top view, for each value of i not greater than K / 2, each (2i - 1)-th inner convex sidewall section icss(2i - 1) can be included within a section of a vertical cylindrical surface having a (2i - 1)-th radius of curvature R(2i - 1). In one embodiment, each curved section of the (2i - 1)-th interconnect of the optical beam splitter 20 has its respective (2i - 1)-th inner convex sidewall section icss(2i - 1), and the (2i - 1)-th inner convex sidewall section icss(2i - 1) has a (2i - 1)-th radius of curvature R(2i - 1). For each value of i greater than 1 and not greater than K / 2, the total azimuthal extension angle of each (2i - 1)-th inner convex sidewall section icss(2i - 1) about the radius center of its respective (2i - 1)-th inner cylindrical sidewall section icss(2i - 1) can be 90 degrees. In the plan view, for each value of i greater than 1 and not greater than K / 2, the total angular propagation direction change within each (2i - 1)-th interconnect of the optical beam splitter 20 can be 180 degrees.

[0121] In the top view, for each value of i not greater than K / 2, each 2i-th inner convex sidewall section icss(2i) can be included within a section of a vertical cylindrical surface having a 2i-th radius of curvature R(2i). As seen in the top view, the total azimuthal extension angle of each 2i-th inner convex sidewall section icss(2i) about the radius center of its respective 2i-th inner cylindrical sidewall section icss(2i) can be 90 degrees. Generally, in the plan view, the total angular propagation direction change within each 2i-th interconnect of the optical beam splitter 20 can be 180 degrees.

[0122] In one embodiment, for each value of i greater than 1 and not greater than K / 2, each curved section of the (2i - 1)-th interconnect portion of the optical beam splitter 20 has a respective (2i - 1)-th inner convex sidewall section icss(2i - 1), and the (2i - 1)-th inner convex sidewall section icss(2i - 1) has a (2i - 1)-th radius of curvature R(2i - 1). In one embodiment, for each value of i not greater than K / 2, each curved section of the 2i-th interconnect portion of the optical beam splitter 20 has a respective 2i-th inner convex sidewall section icss(2i), and the 2i-th inner convex sidewall section icss(2i) has a 2i-th radius of curvature R(2i). In one embodiment, for each value of i greater than 1 and not greater than K / 2, each (2i - 1)-th interconnect portion of the optical beam splitter 20 includes a pair of curved sections, each curved section having a respective total angular propagation direction change of 90 degrees and a straight section connecting the pair of curved sections. In one embodiment, for each value of i not greater than K / 2, each 2i-th interconnect portion of the optical beam splitter 20 includes a pair of curved sections, each curved section having a respective total angular propagation direction change of 90 degrees and a straight section connecting the pair of curved sections.

[0123] In one embodiment, the multi-order nested routing of the waveguide bifurcation branches consists of a single continuous waveguide structure, and the single continuous waveguide structure has a uniform height throughout. In one embodiment, each first-order waveguide bifurcation branch 20A has a first lateral range along the length direction of the optical beam splitter 20, the length direction being perpendicular to the first width direction wd1; each second-order waveguide bifurcation branch 20B has a second lateral range along the length direction, the second lateral range being greater than the first lateral range; and the third-order waveguide bifurcation branch 20C has a third lateral range along the length direction, the third lateral range being greater than the second lateral range. In one embodiment, the third lateral range is greater than twice the second lateral range. In one embodiment, the first lateral range is greater than half of the third lateral range.

[0124] In one embodiment, all the radii of curvature (R1, R2, R3, R4, R5, R6, etc.) in the optical beam splitter 20 can be the same. In one embodiment, the total number of optical ports (which can be an input port or an output port) connected to the first splitting end 1S of the first-order waveguide bifurcation branch 20A can be 2 K , where K is an integer greater than 1, and preferably greater than 2. In this embodiment, the lateral range of the optical beam splitter 20 along the length direction (such as the first length direction ld1) of the optical beam splitter 20 can be approximately 2 Kx(2x R+WW+WS), where WW is the width of the waveguide segments of the optical beam splitter, and WS is the spacing between adjacent pairs of waveguide segments. The lateral extent of the optical beam splitter 20 along a width direction of the optical beam splitter 20 (such as the first width direction wd1) can be approximated as 2×(R+WW)+LSS+(WW+WS)×(K-2), where LSS is the length of a straight segment that connects the common end of each (j-1)-th order waveguide bifurcation branch to the split end of the respective j-th order waveguide bifurcation branch for each integer j greater than 1 and not greater than K.

[0125] The total number of optical channels N and the total number of optical ports N can be N=2 K . In the present embodiment, K=Log2N. The lateral extent of the optical beam splitter 20 along the length direction of the optical beam splitter 20 is approximately N×(2×R+WW+WS). Therefore, the lateral extent of the optical beam splitter 20 is linearly proportional to the total number of optical ports. The lateral extent of the optical beam splitter 20 along the width direction of the optical beam splitter 20 (i.e., the lateral distance between the first vertical plane VP1 and the second vertical plane VP2) is 2×(R+WW)+LSS+(WW+WS)x((Log2N)-2). Therefore, the lateral extent of the optical beam splitter 20 along the width direction of the optical beam splitter 20 increases only logarithmically with the total number of optical ports coupled to the optical beam splitter 20 of the present disclosure. In addition, the number (WW+WS) can be less than R, and therefore, the lateral extent of the optical beam splitter 20 along the width direction of the optical beam splitter 20 of various embodiments can be much smaller than the lateral extent of an optical beam splitter using a cascading branching configuration known in the art.

[0126] refer to Figure 4C as well as Figure 5C , an optical device 40 can then be formed, which is optically connected to the respective first split ends 1S of the first-order waveguide bifurcated branches 20A. The optical device 40 may include any optical device known in the art. Generally speaking, the optical device 40 is optically connected to the respective first split ends 1S of the first-order waveguide bifurcated branches 20A.

[0127] A first metal interconnect structure 180, a first metal pad 198, and an additional first dielectric material layer 10 can be formed above the multi-level nested network. The first metal interconnect structure 180 and the first metal pad 198 are formed within the additional first dielectric material layer 10 and are electrically connected to electrical nodes of the optical device 40. A first die 100 is disposed within each die region.

[0128] Generally, the first die 100 may include: a first dielectric material layer 10 in which a multi - order nested network having waveguide bifurcation branches is formed; an optical device 40 optically connected to respective first splitting ends 1S of the first - order waveguide bifurcation branches 20A; and a first metal interconnect structure 180 electrically connected to electrical nodes of the optical device 40 and formed within the first dielectric material layer 10. The exemplary structure shown in Figure 1A may be provided in this process step. Subsequently, the process steps referred to in Figure 1B and Figure 1C may be performed.

[0129] Referring to Figure 4D , a second die 200 may be provided. The second die 200 may be any type of semiconductor die, such as a system - on - integrated - circuit (SoIC) die, a central processing unit, a graphics processing unit, a memory die, etc. The second die 200 may include a control circuit 240 that includes field - effect transistors 210 and is configured to generate control signals for the optical device 40 within the first die 100. Each field - effect transistor 210 may include respective gate electrodes 205, respective gate dielectrics, respective source regions 202, and respective drain regions 208. Generally, the second die 200 includes a semiconductor substrate 201, a control circuit 240 including field - effect transistors 210, a second metal interconnect structure 280, and second metal bonding pads 298 formed within a second dielectric material layer 230.

[0130] The second metal bonding pads 298 may be bonded directly to the first metal bonding pads 198 through metal - to - metal bonding, or indirectly via an array of solder material portions (such as solder balls). The process steps described in Figure 6 may be referred to.

[0131] Figure 6 is a flowchart showing a series of process steps that may be used to fabricate a device structure according to an embodiment of the present disclosure.

[0132] Referring to step 610 and Figure 4A , a waveguide material layer 20L may be formed over the dielectric material layer 10.

[0133] Referring to step 620 and Figures 1A to 1C , Figure 2A , Figure 2B , Figure 3 , Figure 4B , Figure 4C and Figures 5A to 5C, the waveguide material layer 20L can be patterned into a multi - order nested network of waveguide bifurcation branches. The multi - order nested network of waveguide bifurcation branches includes: first - order waveguide bifurcation branches 20A, each first - order waveguide bifurcation branch 20A includes a pair of first - order waveguide segments, where each pair of first - order waveguide segments includes a first common end 1C and a pair of first split ends 1S and a pair of first interconnecting portions 1I, the first interconnecting portions 1I connect the first common end 1C to the respective first split ends 1S within the first split ends 1S, wherein each first common end 1C and each first split end 1S of the optical beam splitter 20 point in the first width direction wd1 of the optical beam splitter 20, and each first interconnecting portion 1I of the optical beam splitter 20 includes respective first outwardly convex sidewall segments ocss1, the first outwardly convex sidewall segments ocss1 generally face the second width direction wd2, the second width direction wd2 is opposite to the first width direction wd1; and second - order waveguide bifurcation branches 20B, each second - order waveguide bifurcation branch 20B includes a pair of second - order waveguide segments, where each pair of second - order waveguide segments includes a second common end 2C and a pair of second split ends 2S and a pair of second interconnecting portions 2I, the second interconnecting portions 2I connect the second common end 2C to the respective second split ends 2S within the second split ends 2S, wherein each second split end 2S of the optical beam splitter 20 is connected to the respective first common end 2C of the first - order waveguide bifurcation branches 20A, and each second common end 2C and each second split end 2S of the optical beam splitter 20 point in the second width direction wd2 of the optical beam splitter 20.

[0134] Referring to all the accompanying drawings and in accordance with various embodiments of the present disclosure, a device structure including an optical beam splitter 20 is provided. The optical beam splitter 20 includes a multi-stage nested network of waveguide bifurcated branches. The multi-stage nested network of waveguide bifurcated branches includes: a first-stage waveguide bifurcated branch 20A, each first-stage waveguide bifurcated branch 20A including a pair of first-stage waveguide segments, wherein each pair of first-stage waveguide segments includes a first common end 1C and a pair of first split ends 1S and a pair of first interconnecting portions 1I. The first interconnecting portions 1I connect the first common end 1C to the respective first split ends 1S within the first split ends 1S. Wherein each first common end 1C of the optical beam splitter 20 points in the first width direction wd1 of the optical beam splitter 20, and each first interconnecting portion 1I of the optical beam splitter 20 includes a respective first outwardly convex sidewall segment ocs s1, and the first outwardly convex sidewall segment ocs s1 generally faces the second width direction wd2, and the second width direction wd2 is opposite to the first width direction wd1; and a second-stage waveguide bifurcated branch 20B, each second-stage waveguide bifurcated branch 20B including a pair of second-stage waveguide segments, wherein each pair of second-stage waveguide segments includes a second common end 2C and a pair of second split ends 2S and a pair of second interconnecting portions 2I. The second interconnecting portions 2I connect the second common end 2C to the respective second split ends 2S within the second split ends 2S. Wherein each second split end 2S of the optical beam splitter 20 is connected to the respective first common end 1C of the first-stage waveguide bifurcated branch 20A, and each second common end 2C and each second split end 2S of the optical beam splitter 20 point in the second width direction wd2 of the optical beam splitter 20.

[0135] In one embodiment, each second interconnecting portion 2I of the optical beam splitter 20 includes a respective second outwardly convex sidewall segment ocs s2, and the second outwardly convex sidewall segment ocs s2 generally faces the first width direction wd1. In one embodiment, in a plan view, the total angular propagation direction change within each first interconnecting portion 2I of the optical beam splitter 20 is not greater than 180 degrees. In one embodiment, each bent segment of the first interconnecting portion 1I of the optical beam splitter 20 has a respective first inwardly convex sidewall segment ics s1, and the first inwardly convex sidewall segment ics s1 has a first radius of curvature R1. In one embodiment, each bent segment of the second interconnecting portion 2I of the optical beam splitter 20 has a respective second inwardly convex sidewall segment ics s2, and the second inwardly convex sidewall segment ics s2 has a second radius of curvature R2. In one embodiment, each second interconnecting portion 2I of the optical beam splitter 20 has a pair of bent segments and a straight segment connecting the pair of bent segments, and each bent segment has a total angular propagation direction change of 90 degrees respectively. In one embodiment, each first interconnecting portion 2I of the optical beam splitter 20 is composed of respective bent segments.

[0136] In one embodiment, the multi - order nested network of waveguide bifurcation branches is composed of a single continuous waveguide structure, and the single continuous waveguide structure has a uniform height throughout. In one embodiment, the device structure includes a first die 100, and the first die 100 includes: a first dielectric material layer 10 in which a multi - order nested network of waveguide bifurcation branches is formed; an optical device 40 optically connected to respective first splitting ends 1S of the first - order waveguide bifurcation branches 20A; and a first metal interconnect structure 180 electrically connected to the electrical nodes of the optical device 40 and formed within the first dielectric material layer 10.

[0137] In one embodiment, each first - order waveguide bifurcation branch 20A has a first lateral extent along the length direction of the optical splitter 20, the length direction being perpendicular to the first width direction wd1; each second - order waveguide bifurcation branch 20B has a second lateral extent along the length direction of the optical splitter 20; and the second lateral extent is greater than the first lateral extent.

[0138] According to another aspect of the present disclosure, a device structure including an optical splitter 20 is illustrated. The optical splitter 20 includes a multi - order nested network of waveguide bifurcation branches. For each of at least two consecutive positive integers i including 1 and 2, the multi - order nested network of waveguide bifurcation branches includes: (2i - 1) - th order waveguide bifurcation branches, each (2i - 1) - th order waveguide bifurcation branch including a pair of (2i - 1) - th order waveguide segments, where each pair of (2i - 1) - th order waveguide segments includes a (2i - 1) - th common end, a pair of (2i - 1) - th splitting ends, and a pair of (2i - 1) - th interconnects, the (2i - 1) - th interconnects connecting the (2i - 1) - th common end to respective (2i - 1) - th splitting ends within the (2i - 1) - th splitting ends, where each (2i - 1) - th common end of the optical splitter 20 points in the first width direction wd1 of the optical splitter 20, and each (2i - 1) - th interconnect of the optical splitter 20 includes a respective (2i - 1) - th outwardly convex sidewall section generally facing the second width direction wd2, the second width direction wd2 being opposite to the first width direction wd1; and 2i - th order waveguide bifurcation branches, each 2i - th order waveguide bifurcation branch including a pair of 2i - th order waveguide segments, where each pair of 2i - th order waveguide segments includes a 2i - th common end, a pair of 2i - th splitting ends, and a pair of 2i - th interconnects, the 2i - th interconnects connecting the 2i - th common end to respective 2i - th splitting ends within the 2i - th splitting ends, where each 2i - th splitting end of the optical splitter 20 is connected to the respective (2i - 1) - th common end of the (2i - 1) - th order waveguide bifurcation branches, and where each 2i - th common end and each 2i - th splitting end of the optical splitter 20 point in the second width direction wd2 of the optical splitter 20.

[0139] In one embodiment, each first-order waveguide bifurcation branch 20A has a first lateral extent along the length direction of the optical splitter 20, the length direction being perpendicular to the first width direction wd1; each second-order waveguide bifurcation branch 20B has a second lateral extent along the length direction, the second lateral extent being greater than the first lateral extent; and each third-order waveguide bifurcation branch 20C has a third lateral extent along the length direction, the third lateral extent being greater than the second lateral extent.

[0140] In one embodiment, the third lateral extent is greater than twice the second lateral extent. In one embodiment, the first lateral extent is greater than half of the third lateral extent. In one embodiment, the device structure further includes an optical device 40 optically connected to respective first splitting ends 1S of the first-order waveguide bifurcation branches 20A.

[0141] Various embodiments disclosed herein may provide a compact optical splitter 20 having a lateral extent in the width direction given by 2x(R + WW) + LSS + (WW + WS) x ((Log 2N) - 2). Thus, each optical splitter 20 of the optical splitters 20 of the present disclosure occupies less device area and, thus, provides for high-density packaging of the optical splitter 20 and / or formation of additional optical devices 40 adjacent to the optical splitter 20. High-performance beam routing may be provided by the optical splitters 20 of the various embodiments.

[0142] According to one aspect of the present disclosure, the optical ports of the device structure of the present disclosure may be fully enclosed, that is, fully nested within the optical channel network and, specifically, within the multi-order nested network of waveguide bifurcation branches. Each optical port may be optically coupled to a respective optical device and may serve as a respective optical output port or a respective optical input port. Thus, photons may be generated and / or captured between a first horizontal plane (including the top surfaces of the respective waveguide bifurcation branches) and a second horizontal plane (including the bottom surfaces of the respective waveguide bifurcation branches). Alternatively or additionally, photons may be generated and / or captured above the first horizontal plane or below the second horizontal plane, provided that the photons may be transmitted to the optical ports via a suitable waveguide structure (not shown). In one embodiment, each optical port may be surrounded by the multi-order nested network of waveguide bifurcation branches over the entire azimuthal range (i.e., for all azimuthal directions within a total of 360 degrees), such that every straight horizontal path signal from any optical port will be blocked by the multi-order nested network of waveguide bifurcation branches. Thus, each optical port is fully nested within the multi-order nested network of waveguide bifurcation branches in all horizontal directions.

[0143] The components of several embodiments are outlined above so that the viewpoints of the embodiments of the present disclosure can be more easily understood by those of ordinary skill in the art to which the present disclosure pertains. Each embodiment described using the term "comprises" also essentially discloses an additional embodiment in which the term "comprises" is replaced by "consists essentially of" or the term "consists of", unless expressly disclosed otherwise herein. Whenever two or more elements are listed as alternatives in the same paragraph or different paragraphs, a Markush group including the list of two or more elements is also implicitly disclosed. Whenever the auxiliary verb "can" is used in the present disclosure to describe the formation of an element or the execution of a process step, an embodiment in which such an element or such a process step is not executed is also expressly contemplated, provided that the resulting device or apparatus can provide equivalent results. Therefore, the auxiliary verb "can" applied to the formation of an element or the execution of a process step should also be interpreted as "may" or "may or may not", regardless of whether omitting the formation of such an element or such a process step can provide the same results or equivalent results, and equivalent results include slightly better results and slightly worse results. Those of ordinary skill in the art to which the present disclosure pertains should understand that they can design or modify other processes and structures based on the embodiments of the present disclosure to achieve the same purposes and / or advantages as the embodiments introduced herein. Those of ordinary skill in the art to which the present disclosure pertains should also understand that such equivalent processes and structures do not depart from the spirit and scope of the present disclosure, and they can make various changes, substitutions, and replacements without departing from the spirit and scope of the present disclosure.

Claims

1. A device structure, characterized in that, Comprising an optical beam splitter, wherein the optical beam splitter includes a multi-order nested network of waveguide bifurcated branches, and the multi-order nested network of waveguide bifurcated branches includes: A plurality of first-order waveguide bifurcated branches, each of the first-order waveguide bifurcated branches including a pair of first-order waveguide segments, wherein each pair of the first-order waveguide segments includes a first common end, a pair of first split ends, and a pair of first interconnecting portions, the first interconnecting portions connecting the first common end to respective ones of the first split ends within the first split ends, wherein each of the first common ends of the optical beam splitter points in a first width direction of the optical beam splitter, and each of the first interconnecting portions of the optical beam splitter includes a respective first outwardly convex sidewall segment, the first outwardly convex sidewall segment generally facing a second width direction, the second width direction being opposite to the first width direction; and A plurality of second-order waveguide bifurcated branches, each of the second-order waveguide bifurcated branches including a pair of second-order waveguide segments, wherein each pair of the second-order waveguide segments includes a second common end, a pair of second split ends, and a pair of second interconnecting portions, the second interconnecting portions connecting the second common end to respective ones of the second split ends within the second split ends.

2. The device structure according to claim 1, characterized in that, Wherein in a planar view, the total angular propagation direction change within each of the first interconnecting portions of the optical beam splitter is not greater than 180 degrees.

3. The device structure according to claim 1, wherein Wherein: The first-order waveguide bifurcated branches include a plurality of optical channels connected to a plurality of optical ports; Each of the optical ports is nested within the multi-order nested network of waveguide bifurcated branches in respective horizontal directions; And Each bending section of the first interconnecting portions of the optical beam splitter has a respective first inwardly convex sidewall segment, the first inwardly convex sidewall segment having a first radius of curvature.

4. The device structure according to claim 3, characterized in that, Wherein: Each bending section of the second interconnecting portions of the optical beam splitter has a respective second inwardly convex sidewall segment, the second inwardly convex sidewall segment having a second radius of curvature; And Each of the second interconnecting portions of the optical beam splitter has a pair of bending sections, the bending sections each having a total angular propagation direction change of 90 degrees and a straight-line section connecting the pair of bending sections.

5. The device structure according to claim 1, wherein, Wherein the entire multi-order nested network of waveguide bifurcated branches is composed of a single continuous waveguide structure, and the single continuous waveguide structure has a uniform height throughout.

6. The device structure according to claim 5, characterized in that Wherein the device structure includes a first die, and the first die includes: A plurality of first dielectric material layers, in which the multi-order nested network of waveguide bifurcated branches is formed; A plurality of optical devices, optically connected to respective ones of the first split ends of the first-order waveguide bifurcated branches; and A plurality of first metal interconnect structures, electrically connected to a plurality of electrical nodes of the optical devices and formed within the first dielectric material layers.

7. A device structure, characterized in that, Comprising an optical beam splitter, wherein the optical beam splitter includes a multi-order nested network of waveguide bifurcated branches, and for each of at least two consecutive positive integers i including 1 and 2, the multi-order nested network of waveguide bifurcated branches includes: A plurality of (2i - 1)th - order waveguide bifurcation branches, each of the (2i - 1)th - order waveguide bifurcation branches including a pair of (2i - 1)th - order waveguide sections, wherein each pair of the (2i - 1)th - order waveguide sections includes a (2i - 1)th common end and a pair of (2i - 1)th split ends and a pair of (2i - 1)th interconnecting portions, the (2i - 1)th interconnecting portions connecting the (2i - 1)th common end to respective ones of the (2i - 1)th split ends within the (2i - 1)th split ends, wherein each of the (2i - 1)th common ends of the optical beam splitter points in a first width direction of the optical beam splitter, and each of the (2i - 1)th interconnecting portions of the optical beam splitter includes a respective (2i - 1)th outwardly convex sidewall section, the (2i - 1)th outwardly convex sidewall section generally facing a second width direction, the second width direction being opposite to the first width direction; and A plurality of 2i - th - order waveguide bifurcation branches, each of the 2i - th - order waveguide bifurcation branches including a pair of 2i - th - order waveguide sections, wherein each pair of the 2i - th - order waveguide sections includes a 2i - th common end and a pair of 2i - th split ends and a pair of 2i - th interconnecting portions, the 2i - th interconnecting portions connecting the 2i - th common end to respective ones of the 2i - th split ends within the 2i - th split ends, wherein each of the 2i - th split ends of the optical beam splitter is connected to a respective (2i - 1)th common end of the (2i - 1)th - order waveguide bifurcation branches, wherein each of the 2i - th common ends and each of the 2i - th split ends of the optical beam splitter point in the second width direction of the optical beam splitter.

8. The device structure according to claim 7, characterized in that, Wherein: Each of the first - order waveguide bifurcation branches has a first lateral extent along a length direction of the optical beam splitter, the length direction being perpendicular to the first width direction; Each of the second - order waveguide bifurcation branches has a second lateral extent along the length direction, the second lateral extent being greater than the first lateral extent; and Each of the third - order waveguide bifurcation branches has a third lateral extent along the length direction, the third lateral extent being greater than the second lateral extent.

9. The device structure according to claim 8, wherein, Wherein the third lateral extent is greater than twice the second lateral extent.

10. The device structure according to claim 8 or 9, characterized in that, Wherein the first lateral extent is greater than half of the third lateral extent.

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