Grating coupler

Abstract

The embodiment of the utility model relates to a grating coupler. According to some embodiments of the utility model, a grating coupler comprises: a tapered section comprising a pair of tapers configured to transmit light of different polarizations; and a grating section coupled to optically couple to an optical fiber wherein the grating section includes an array of gratings wherein a degree of difference in shape, area, and thickness between a central grating of the gratings and a first grating other than the central grating is determined based on a distance between the central grating and the first grating, wherein the center grating comprises a first non-convex octagonal shape, a first edge grating comprises a second non-convex octagonal shape different from the first non-convex octagonal shape, and a second edge grating arranged near an interface between the grating section and the tapered section comprises a convex octagonal or quadrilateral shape.

Description

Technical Field

[0001] The embodiment of the utility model relates to a two-dimensional grating coupler. Background Art

[0002] Modern technological advances such as big data, cloud computing, cloud storage, and the Internet of Things (IoT) have driven exponential growth in various applications in data processing and communication, such as high-performance computers, data centers, and long-distance telecommunications. To address the emerging demand for high data rate transmission, modern semiconductor structures may include optical elements for providing optical data links to improve the data transmission rate of existing electrical data links. In the development of incorporating optical data links into semiconductor devices, the challenge of improving the coupling efficiency of optical data links has attracted great attention. Utility Model Content

[0003] An embodiment of the utility model relates to a method for forming a grating coupler, comprising: providing an initial design layout of the grating coupler, wherein the initial design layout comprises: a tapered section comprising a pair of tapered shapes; and a grating section coupled to the tapered section, the grating section comprising a grating array, wherein the grating comprises a gradually changing shape from a first non-convex octagonal shape of a central grating at the center of the grating section to a second non-convex octagonal shape of an edge grating near an edge of the grating section, a convex octagonal shape, and a quadrilateral shape from a top view perspective; converting the initial design layout into a revised design layout through an optical proximity correction operation; and manufacturing the grating coupler using the revised design layout.

[0004] An embodiment of the utility model relates to a method for forming a grating coupler, which comprises: providing a silicon-on-insulator (SOI) substrate; forming a grating segment and a pair of cones in a silicon layer of the SOI substrate, wherein each of the pair of cones extends from a first end to a second end; and depositing an insulating material to cover the grating segment and the pair of cones, wherein the grating segment comprises a grating array, wherein the grating comprises a gradually changing shape from a top view perspective, wherein a central grating comprises a first non-convex octagonal shape, a first edge grating comprises a second non-convex octagonal shape different from the first non-convex octagonal shape, and a second edge grating arranged near an interface between the grating segment and the cone segment comprises a quadrilateral shape.

[0005] An embodiment of the utility model relates to a grating coupler, comprising: a tapered section, comprising a pair of cones configured to transmit light of different polarizations; and a grating section, configured to be optically coupled to an optical fiber, wherein the grating section comprises a grating array, wherein the degree of difference in shape, area and thickness between the central grating and a first grating other than the central grating is determined according to the distance between the central grating of the grating and the first grating, wherein the central grating comprises a first non-convex octagonal shape, the first edge grating comprises a second non-convex octagonal shape different from the first non-convex octagonal shape, and the second edge grating arranged near the interface between the grating section and the tapered section comprises a convex octagonal or quadrilateral shape. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0007] Figure 1 Block diagram showing top and cross-sectional views of a grating coupler according to some embodiments of the present disclosure.

[0008] Figure 2 According to some embodiments of the present disclosure, the Figure 1 Schematic diagram of the position diagram of the grating of the grating coupler shown in FIG.

[0009] Figure 3A Demonstrating some embodiments of the present disclosure Figure 1 An enlarged view of a portion of a grating segment of a grating coupler shown in FIG.

[0010] Figure 3B Demonstrating some embodiments of the present disclosure Figure 1 Top view of the various gratings of the grating coupler shown in .

[0011] Figure 4A , Figure 4B , Figure 4C , Figure 4D , Figure 4E , Figure 4F and Figure 4G According to some embodiments of the present disclosure Figure 1 Top view of the grating in different positions of the grating segments shown in .

[0012] Figure 5A A top view and a cross-sectional view of a tapered section of a grating coupler according to some embodiments of the present disclosure are shown.

[0013] Figure 5BA top view of a tapered section of a grating coupler is shown according to some embodiments of the present disclosure.

[0014] Figure 6 A top view and a cross-sectional view of a grating coupler according to some embodiments of the present disclosure are shown.

[0015] Fig. 7A , Figure 7B and Figure 7C Schematic diagram showing position diagrams of gratings of various grating couplers according to some embodiments of the present disclosure.

[0016] Fig. 8A A top view and a cross-sectional view of a grating coupler according to some embodiments of the present disclosure are shown.

[0017] Figure 8B and Figure 8C Top views of various grating couplers according to some embodiments of the present disclosure are shown.

[0018] Fig.9A , Fig. 9B and Fig. 9C Demonstrating some embodiments of the present disclosure Fig. 8A , Figure 8B or Figure 8C Cross-sectional view of the grating coupler shown in FIG.

[0019] Fig. 10A , Fig. 10B and Fig. 10C A top view of a grating coupler according to some embodiments of the present disclosure is shown.

[0020] Fig.11A An initial design layout of a grating coupler according to some embodiments of the present disclosure is shown.

[0021] Fig. 11B A revised design layout according to some embodiments of the present disclosure is shown.

[0022] FIG. 11C to FIG. 11J is a cross-sectional view of an intermediate stage of a method of forming a grating coupler according to some embodiments of the present disclosure.

[0023] Fig.12 is a flow chart of a method of forming a grating coupler according to some embodiments of the present disclosure. DETAILED DESCRIPTION

[0024] The following disclosure provides many different embodiments or examples of different components for implementing the subject matter provided. The following describes the specific examples of components and arrangements to simplify the present disclosure. Of course, these are only examples and do not wish to limit. For example, the first component in the following description is formed above or on the second component and may include an embodiment in which the first component and the second component are formed to be directly in contact, and may also include an embodiment in which an additional component may be formed between the first component and the second component so that the first component and the second component may not be directly in contact. In addition, the present disclosure may repeat element symbols and / or letters in each example. This repetition is for the purpose of simplification and clarity and does not itself indicate the relationship between the various embodiments and / or configurations discussed.

[0025] Additionally, for ease of description, spatially relative terms, such as "below," "beneath," "below," "above," "over," "on," and the like, may be used herein to describe the relationship of one element or component to another element or components, as illustrated in the figures. The spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein should be interpreted likewise.

[0026] As used herein, although terms such as "first," "second," and "third" describe various elements, components, regions, layers, and / or sections, these elements, components, regions, layers, and / or sections should not be limited by these terms. These terms may only be used to distinguish one element, component, region, layer, or section from another element, component, region, layer, or section. Unless clearly indicated by the context, terms such as "first," "second," and "third" when used herein do not imply a sequence or order.

[0027] Although the numerical ranges and parameters stating the wide range of the present disclosure are approximate values, the numerical values ​​stated in the specific examples are reported as accurately as possible. However, any numerical value essentially contains certain errors that are necessarily caused by the deviations usually found in the corresponding test measurements. Furthermore, as used herein, the terms "approximately", "substantially" or "substantially" generally mean within 10%, 5%, 1% or 0.5% of a given value or range. Alternatively, the terms "approximately", "substantially" or "substantially" mean within the acceptable standard error of the mean value when considered by a person of ordinary skill in the art. Except in the operating / working examples, or unless otherwise explicitly specified, all numerical ranges, quantities, values ​​and percentages, such as for the quantity, duration, temperature, operating conditions, ratio of quantities and the like of the materials disclosed herein, should be understood to be modified by the terms "approximately", "substantially" or "substantially" in all examples. Therefore, unless otherwise indicated, the numerical parameters stated in the present disclosure and the appended claims are approximate values ​​that can be changed as needed. At a minimum, each numerical parameter should at least be understood in light of the number of reported significant digits and by applying ordinary rounding techniques. Ranges may be expressed herein as from one endpoint to the other or between two endpoints. Unless otherwise specified, all ranges disclosed herein include the endpoints.

[0028] Embodiments of the present disclosure relate to a grating coupler and a method of forming the grating coupler. Modern optical waveguides and grating couplers can be implemented using silicon-based materials due to their low transmission loss and compatibility with existing semiconductor processes. Grating couplers are useful in optical transmission / reception systems because they are used to convert light beams from optical fibers to optical waveguides, where there is a difference in the optical field diameter between the optical fiber and the optical waveguide. In addition, due to design constraints, polarization dependent loss (PDL) of grating couplers due to modal mismatch is often observed. Therefore, the optical coupling performance of the grating coupler may be affected by the size of the device.

[0029] The present disclosure proposes a two-dimensional (2D) grating coupler to effectively enhance the optical coupling performance of the grating coupler. The 2D grating coupler generally includes a tapered section and a grating section coupled to the tapered section to serve as a composite coupling medium between an optical fiber and an optical waveguide. The proposed grating coupler incorporates one or more design criteria when implementing an apodized grating pattern to improve the coupling efficiency of both the transverse electric (TE) mode and the transverse magnetic (TM) mode of the optical beam, and reduce the polarization dependent loss (PDL). Therefore, compared with the existing grating coupler, the coupling performance of the grating coupler can be improved.

[0030] Figure 1A block diagram showing a top view and a cross-sectional view of a grating coupler 100 according to some embodiments of the present disclosure. According to various embodiments, the cross-sectional view is taken along the section line AA of the top view. The grating coupler 100 can be used to couple a light beam from an optical fiber 104 to a waveguide 206 in a semiconductor device or an integrated chip (IC), or from a waveguide 206 to an optical fiber 104. According to some embodiments of the present disclosure, the grating coupler 100 is formed in a semiconductor device in which the waveguide 206 is formed. The grating coupler 100 can be integrated with the waveguide 206. According to some embodiments of the present disclosure, the grating coupler 100 and the waveguide 206 are formed of a semiconductor material such as bulk silicon. According to some embodiments of the present disclosure, a lower silicon layer 210 is provided as a base layer in a semiconductor substrate or a semiconductor silicon wafer. In addition, an insulating layer 220 is formed over the lower silicon layer 210. The insulating layer 220 can be formed of a dielectric material such as silicon dioxide. An upper silicon layer 230 is formed over the insulating layer 220 to serve as a circuit layer in which a device can be formed. According to some embodiments of the present disclosure, the upper silicon layer 230 is formed on the insulating layer 220 by epitaxy to provide better performance. The composite structure of the lower silicon layer 210, the insulating layer 220 and the upper silicon layer 230 can be collectively referred to as a silicon-on-insulator (SOI) substrate, wherein the insulating layer 220 serves as an electrical insulating layer between the lower silicon layer 210 and the upper silicon layer 230.

[0031] According to some embodiments of the present disclosure, most semiconductor devices or optical devices (e.g., grating coupler 100) are formed in the upper silicon layer 230, and the cladding layer 240 is formed above the upper silicon layer 230. The cladding layer 240 may be formed of an insulating dielectric material (e.g., silicon oxide) having a refractive index less than that of silicon. The cladding layer 240 and the insulating layer 220 may together form a cladding structure to wrap around the grating coupler 100, so that the light beam in the grating coupler 100 may propagate according to the law of total internal reflection.

[0032] refer to Figure 1 , the grating coupler 100 includes a tapered section 202 and a grating section 204, wherein the tapered section 202 and the grating section 204 are coupled to each other. According to some embodiments, the grating coupler 204 has a quadrilateral shape with four sides 204A, 204B, 204C, and 204D. The grating coupler 204 may be coupled to the tapered section 202 at sides 204A and 204B, and sides 204C and 204D face away from the interface between the tapered section 202 and the grating coupler 204. The tapered section 202 and the grating section 204 may be formed in the same layer, such as an upper silicon layer 230.

[0033] According to some embodiments, the grating segment 204 is configured to be optically coupled to the optical fiber 104. According to some embodiments, the tapered segment 202 is configured to be optically coupled to another optical device formed in the semiconductor device, for example, an optical waveguide 206. The optical fiber 104 may be arranged close to the upper surface 100S of the grating coupler 100. The longitudinal axis of the optical fiber 104 may be arranged to be orthogonal to the surface of the grating coupler 100, or a tilt angle α is formed between the longitudinal axis of the optical fiber 104 and the normal to the upper surface 100S of the grating coupler 100. The tilt angle α may be less than 10 degrees, for example, about 8 degrees. The tilt angle α may promote most of the light beam to propagate toward the waveguide 206. In addition, by the arrangement of the grating coupler 100, the light beam propagating in the optical waveguide 206 may be optically coupled to or from the optical fiber 104 with a higher optical coupling efficiency by matching the mode field diameter between the optical waveguide 206 and the optical fiber 104.

[0034] According to some embodiments, the tapered section 202 includes a first tapered section 202A and a second section 202B. The tapered sections 202A and 202B may extend in different directions. The longitudinal axes of the tapered sections 202A and 202B may intersect at a center point of the grating section 204. According to some embodiments, the tapered sections 202A and 202B may form an angle of substantially 90 degrees or other degrees. The tapered sections 202A and 202B are arranged to extend from a first end (see FIG. 1 ) proximate to the sides 204A, 204B of the grating section 204. Figure 5A The label 502 shown in FIG. 1 is tapered to a second end portion of the optical fiber 104 (see FIG. Figure 5A ) for achieving optical coupling with the optical waveguide 206.

[0035] Figure 2 According to some embodiments of the present disclosure, the Figure 1 FIG. 2 is a schematic diagram of a position diagram 200 of a grating unit or grating 214 of a grating coupler 204 shown in FIG. Figure 1 and Figure 2 , two sets of concentric ellipses C1 and C2 are arranged to intersect each other, wherein each of the two sets of concentric ellipses C1 or C2 has a plurality of ellipses having a common focus P1 or P2, respectively. The two sets of ellipses C1, C2 are formed to conform to the optical refraction law of the light beam transmitted from the optical fiber 104. In addition, the positions of the focal points P1 and P2 are determined to coincide with the second ends of the cones 202B and 202A, respectively, to achieve optimal focusing of the light beam. The position of the intersection position Qi (i is the refractive index of the grating 214) of the two sets of ellipses C1, C2 determines the center of the grating 214 or Gi (i is the refractive index of the grating 214). For example, two representative gratings G1 and G2 are arranged near the interface between the grating segment 204 and the cone segment 202, and the two representative intersection points or intersection points Q1 and Q2 are determined according to Figure 2and coincide with the (geometric) centers of the gratings G1 and G2, respectively. According to some embodiments, the area occupied by the array of intersection points Qi of the concentric ellipses covers most of the beam energy propagating through the optical fiber 104 to capture most of the beam energy. The size and spacing of the gratings 214 determine the duty cycle and spacing of the gratings 214, and are associated with the refractive index of the material of the grating coupler 100 and the wavelength of the beam. The concentric ellipses C1, C2 may alternatively be formed by concentric circles or other suitable curves.

[0036] refer to Figure 1 According to some embodiments, the grating segment 204 includes a plurality of gratings 214 arranged in an array on the surface of the upper silicon layer 230. According to some embodiments, the gratings 214 are similar in shape to each other but have a certain degree of variation. The gratings 214 are arranged to have a gradually changing shape and / or area from the grating Gc at the center position of the grating segment 204 toward the edge grating Ge near the edge (e.g., the sides 204A to 204D of the grating segment 204), a process referred to herein as apodization. By apodization of the gratings 214, the overall optical coupling efficiency and quality of the light beam refracted by the gratings 214 can be improved.

[0037] Figure 3A Demonstrating some embodiments of the present disclosure Figure 1 FIG. 2 is an enlarged view of a portion A1 of a grating section 204 of a grating coupler 100 shown in FIG. Four representative gratings 214 (e.g., G1, G2, G3, and G4) with respective apodization arrangements are illustrated in portion A1. Each of the gratings 214 has its respective center Q1, Q2, Q3, and Q4, whose positions are determined according to the position diagram 200, as described with reference to FIG. Figure 2 As discussed. Each of the gratings 214 has a shape similar to its neighboring gratings 214. According to some embodiments, the gratings 214 (especially the gratings 214 at the center of the grating section 204) include a non-convex octagonal shape, for example, a four-piece star. The term "non-convex" of the shape refers to at least one internal angle of the shape having a measurement between 180° and 360°, or equivalently referred to as a reflection angle. The star shape may be characterized by four slices or protrusions radiating from its body or center having four tips, and each of the four slices or protrusions tapers from the center of the star to the tip of the corresponding slice or protrusion. Therefore, the non-convex octagonal shape may include four reflection internal angles formed between two adjacent slices. According to some embodiments, the non-convex octagonal shape also has four sharp internal angles at the corresponding four slices. According to some embodiments, the grating Gc has a non-convex octagonal shape that is symmetrical around its geometric center.

[0038] The arrangement of the grating 214 is formed at least at a first ratio D11, wherein the first ratio D11 is referred to as a first duty cycle of the grating 214 and is formed at 2*a / A. The first dimension "a" represents a first length of the slice measured from the center Qi to the tip of the slice along a first axis (e.g., the Y axis). The second dimension "A" represents a first distance of the grating 214 measured between the centers Qi of two adjacent gratings 214 along the first axis. The arrangement of the grating 214 is further characterized by at least a second ratio D12, wherein the second ratio D12 is referred to as a second duty cycle of the grating 214 and is formed at 2*b / B. The third dimension "b" represents a second length of the slice measured from the center Qi to the tip of the slice along a second axis (e.g., the X axis). The fourth dimension "B" represents a second distance of the grating 214 measured between the centers Qi of two adjacent gratings 214 along the second axis.

[0039] The arrangement of the grating 214 is further characterized by a third ratio D21, wherein the third ratio D21 is referred to as a first pitch of the grating 214 and is formed as 2*c / C. A fifth dimension "c" represents a third length of the grating 214 measured from the center Qi to the vertex connecting two adjacent slices along the first diagonal axis W1. A sixth dimension "C" represents a third distance between the centers of adjacent gratings 214 along the first diagonal axis W1. The first diagonal axis W1 may include an angle of 45° or 135° with the first axis (e.g., the Y axis) or the second axis (e.g., the X axis). The arrangement of the grating 214 is further characterized by a fourth ratio D22, wherein the fourth ratio D22 is referred to as a second pitch of the grating 214 and is formed as 2*d / D. A seventh dimension "d" represents a fourth length of the grating 214 measured from the center Qi to the vertex connecting two adjacent slices along the second diagonal axis W2. The second diagonal axis W2 may be orthogonal to the first diagonal axis W1. The eighth dimension "D" represents a fourth distance between centers of adjacent gratings 214 along the second diagonal axis W2. The second diagonal axis W2 may include an angle of 45° or 135° with the first axis (eg, Y axis) or the second axis (eg, X axis).

[0040] A light beam or a transverse electromagnetic wave usually propagates in two polarizations (also referred to as components or modes), namely, a transverse electric (TE) mode and a transverse magnetic (TM) mode. The light or electromagnetic wave components in both the TE mode and the TM mode constitute a transverse electromagnetic wave, wherein the TE mode and the TM mode are perpendicular to each other. Therefore, a single polarization grating (e.g., a bar or line grating) may have optical coupling of only one of the TE and TM modes. During the optical coupling process, the energy of the other mode will be easily lost. Dual-mode optical coupling is able to collect all light energy through dual polarizations, but in practical implementations, it may suffer performance degradation not only in terms of coupling efficiency, but also in terms of polarization dependent loss (PDL). PDL may be caused by at least the tilt angle α of the optical fiber 104 relative to the upper surface 100S of the grating coupler. Therefore, in order to achieve the desired optical coupling efficiency while maintaining a low PDL, the dual polarization grating 214 may need to be carefully configured to capture as much energy as possible of the refracted light beam while reducing the PDL to an acceptable level.

[0041] According to some embodiments, the gratings 214 positioned in different intersections Qi of the position diagram 200 include respective first duty cycles D11, second duty cycles D12, first pitches D21, and second pitches D22 to implement apodized gratings 214 in the grating sections 204. According to some embodiments, the first duty cycle D11, second duty cycle D12, first pitches D21, and second pitches D22 of each grating 214 and each pair of gratings 214 may be tuned according to incident light energy received from these gratings 214. The tuning of the first duty cycle D11, second duty cycle D12, first pitches D21, and second pitches D22 should achieve the goal of matching the energy distribution of the light beam across the array of gratings 214 in an attempt to maximize the optical coupling efficiency while maintaining equality between the components of the light beam on the TE polarization and the TM polarization in an attempt to minimize the PDL. The greater the incident light energy received, the greater the first duty cycle D11, second duty cycle D12, first pitches D21, and second pitches D22 of the gratings 214 may be. According to some embodiments, the greater the incident light energy received, the larger the surface area of ​​the grating 214 can be. According to some embodiments, the tuning of the first duty cycle D11, the second duty cycle D12, the first spacing D21, and the second spacing D22 of the target grating 214 depends on factors including each of the following: the received light beam energy; the distance between the target grating 214 and the center grating 214; the distance between the target grating 214 and the cone 202A or 202B; the wavelength of the light beam; the refractive index of the material of the grating coupler 100 (e.g., silicon and silicon oxide); and the like.

[0042] According to some embodiments, reference Figure 1, the trends of the apodization of the gratings 214 (e.g., the increase or decrease of the dimensions “a”, “b”, “c”, and “d” and the spacings “A”, “B”, “C”, and “D”) are the same or symmetrical with respect to the central grating Gc. For example, the subsets of the gratings 214 may have substantially equal lengths “a”, “b”, “c”, or “d”, wherein each of the subsets of the gratings 214 is separated from the central grating Gc by substantially equal distances. The lengths “a”, “b”, “c”, or “d” may decrease or increase monotonically in a concentric manner from the central grating Gc and toward the edge of the grating array. In other words, the area of ​​the gratings 214 may gradually change from the central grating Gc to (e.g., increase or decrease to) the edge gratings 214 near the edge of the grating segment 204. Similarly, a subset of adjacent grating pairs in gratings 214 may have a substantially equal first spacing "A", "B", "C", or "D", wherein the center of each of the grating pairs of gratings 214 is separated from the central grating Gc by a substantially equal distance. The spacing "A", "B", "C", or "D" may decrease or increase monotonically in a concentric circular manner from the central grating Gc and toward the edge of the grating array.

[0043] Apodization is adjusted by all gratings 214 throughout grating segment 204, Figure 2 The grating 214 in each position of the position diagram 200 shown in FIG. 2 can accommodate slight differences in energy distribution and profile of a light beam in TE polarization or TM polarization propagating through each of the apodized gratings 214, which can further improve the optical coupling efficiency of each of the TE mode and the TM mode, while reducing the PDL. Each of the two polarizations of the light beam (i.e., TE mode and TM mode) is transmitted through the cones 202A and 202B, respectively, or vice versa. According to some embodiments, the lengths "a", "b", "c", or "d" or distances "A", "B", "C", or "D" determined in the design layout of the grating coupler 100 may include process-induced variations or errors in the manufactured grating coupler 100. These process-induced variations or errors may exist due to practical limitations of manufacturing tools (e.g., fidelity limitations of exposure tools or etching tools). Process-induced variations or errors in the layout of grating 214 may be at least partially compensated by, for example, optical proximity correction (OPC); however, the ideal shape of grating 214 (eg, the angled tips of a slice or the vertices between adjacent slices) may be rounded.

[0044] Figure 3B Demonstrating some embodiments of the present disclosure Figure 1 302 and 304 of the grating coupler 100 shown in FIG. Figure 3BIn the left sub-figure of FIG. 1 , the grating 302 can be viewed as a combination of two rhombuses or oblique squares, wherein the two rhombuses are oriented in different directions, for example, one rhombus is oriented in the direction of the X axis and the other rhombus is oriented in the direction of the Y axis. The two rhombuses intersect each other and their centers overlap each other to form the grating 302. According to some embodiments, the shape of the grating 302 is formed by straight lines and sharp vertices and can be viewed as Figure 1 The ideal version of grating 214 can be manufactured using advanced photolithography tools and / or etching tools. According to some embodiments, Figure 3B The grating 302 shown in the left sub-figure of FIG. 3 is a layout with a desired OPC operation prior to lithography and etching operations.

[0045] refer to Figure 3B , grating 304 can be viewed as a combination of two ellipses or ovals, where the two ellipses are oriented in different orientations, for example, one ellipse is oriented in the direction of the X-axis and the other ellipse is oriented in the direction of the Y-axis. The two ellipses intersect each other and their centers overlap each other to form grating 214. According to some embodiments, the effect of grating 304 can be similar to that of grating 214, but with curved sides and rounded vertices. The layout of grating 304 can be viewed as a manufactured version of grating 214, because the layout of grating 304 is more friendly to the process of grating 304 and is limited to the process constraints of currently available lithography and etching tools. According to some embodiments, the better the results that the OPC operation can present, the closer the layout of grating 304 will be to grating 214.

[0046] According to some embodiments, a ratio of a length difference or a pitch difference determined by the apodization configuration to a process-induced dimensional error is at least 5 times, such as between about 5 times and about 1000 times, between about 10 times and about 500 times, or between about 10 times and about 100 times.

[0047] Figure 4A , Figure 4B , Figure 4C , Figure 4D , Figure 4E , Figure 4F and Figure 4G According to some embodiments of the present disclosure Figure 1 A top view of the grating 214 in the different positions of the grating segment 204 shown in FIG. Figure 3A As discussed, the shape of the grating 214 will be determined from the shape of the central grating Gc (e.g., Figure 3A The shape shown in the left sub-figure of ) gradually changes to apodized shape. Figures 4A to 4G The apodization shape shown in Figures 4A to 4G Omit Figure 3A Labels for the lengths “a,” “b,” “c,” and “d,” and the spacings “A,” “B,” “C,” and “D” shown.

[0048] refer to Figure 4A , the shape of the grating 214A is apodized from a star or non-convex octagonal shape to a quadrilateral shape (e.g., a square shape). In the case, the lengths "a" and "b" of each grating 214A are substantially equal, and the lengths "c" and "d" of each grating 214A are substantially equal and less than the lengths "a" and "b". The ratio between the lengths "a" and "b" of each grating 214A is substantially equal to And the vertex of each grating 214A has an angle substantially equal to 90°.

[0049] refer to Figure 4B , the shape of the grating 214B is apodized from a star or non-convex octagonal shape to a convex octagonal shape (e.g., a square shape). In the case, the lengths "a" and "b" of each grating 214B are substantially equal, and the lengths "c" and "d" of each grating 214B are substantially equal and equal to the lengths "a" and "b". The ratio between the lengths "a" and "c" of each grating 214B is substantially equal to 1, and the apex of each grating 214B has an angle substantially equal to 135°.

[0050] refer to Figure 4C , the shape of the grating 214C is apodized from a star or non-convex octagonal shape to a rectangular shape. In the case, the lengths "a" and "b" of each grating 214C are not equal, and the lengths "c" and "d" of each grating 214C are not equal. The length "a" may be greater than the lengths "c" and "d", and the length "d" may be greater than the length "c". The vertices of each grating 214C have an angle substantially equal to 90°.

[0051] refer to Figure 4D , the shape of the grating 214D is apodized from a star or non-convex octagonal shape to a rectangular shape. In the case, the lengths "a" and "b" of each grating 214D are not equal, and the lengths "c" and "d" of each grating 214D are not equal. Unlike the apodized grating 214C, in the grating 214D, the length "c" may be greater than the length "a", and the length "c" may be greater than the length "d". The vertices of each grating 214D have an angle substantially equal to 90°.

[0052] refer to Figure 4E , the shape of the grating 214E is maintained as a star or non-convex octagonal shape. However, unlike Figure 3A, wherein the lengths "a" and "b" of each grating 214 are substantially equal, and the lengths "c" and "d" of each grating 214 are substantially equal, the lengths "a" and "b" of each grating 214E may be equal or unequal, and the lengths "c" and "d" of each grating 214E may be equal or unequal. The length "b" in each grating 214E may be greater than the length "a" of the same grating 214E. According to some embodiments, the lengths "a" within the same grating 214E measured on both sides of the corresponding center Qi may also be different from each other. In addition, the length "a" on one side of the center Qi and closer to the center Qi may be greater than the length "a" on the other side of the center Qi and farther from the center Qi. According to some embodiments, the distance between the geometric centers of the upper and lower gratings 214E is less than the first distance "A" between the upper and lower gratings 214E. According to some embodiments, the distance between the geometric centers of the left and right gratings 214E is greater than the second distance "B" between the left and right gratings 214E. According to some embodiments, the centers Qi of the upper and lower gratings 214E deviate from their respective geometric centers and are further away from the center (midpoint) of the upper and lower gratings 214E. The centers Qi of the left and right gratings 214E deviate from their respective geometric centers and are closer to the center (midpoint) of the left and right gratings 214E. The vertices of each grating 214E have an acute angle.

[0053] refer to Figure 4F , the shape of the grating 214F remains a star or non-convex octagon shape and is similar to the grating 214E. The lengths "a" and "b" of each grating 214F may be equal or unequal, and the lengths "c" and "d" of each grating 214F may be equal or unequal. The length "a" in each grating 214F may be greater than the length "b" of the same grating 214F. According to some embodiments, the lengths "a" within the same grating 214E measured on both sides of the corresponding center Qi may also be different from each other. In addition, the length "a" on one side of the center Qi and closer to the center Qi may be smaller than the length "a" on the other side of the center Qi and farther away from the center Qi. According to some embodiments, the distance between the geometric centers of the upper and lower gratings 214F is greater than the first distance "A" between the upper and lower gratings 214F. According to some embodiments, the distance between the geometric centers of the left and right gratings 214F is less than the second distance "B" between the left and right gratings 214F. According to some embodiments, the centers Qi of the upper and lower gratings 214F are offset from their respective geometric centers and closer to the centers (midpoints) of the upper and lower gratings 214F. The centers Qi of the left and right gratings 214F are offset from their respective geometric centers and farther from the centers (midpoints) of the left and right gratings 214E. The vertices of each grating 214F have an acute angle.

[0054] According to some embodiments, the gratings 214E and 214F are configured so that the intersection point Qi of the position map 200 of each grating 214E or 214F does not coincide with the intersection point of the lines measuring lengths "a" and "b". In other words, the intersection point Qi of the grating 214E or 214F is offset by a distance from the geometric center of the corresponding grating 214E, 214F.

[0055] refer to Figure 4G , the shape of grating 214G is maintained as a star or non-convex octagonal shape and is similar to gratings 214E and 214F. However, unlike gratings 214E and 214F, the lengths "a" and "b" of each grating 214G may be equal or unequal, and the lengths "c" and "d" of each grating 214 may be equal or unequal. The vertices of each grating 214G have an acute angle. The gratings 214G are configured so that the intersection point Qi of the position map 200 of each grating 214G still coincides with the intersection point of the line measuring the lengths "a" and "b". In other words, the intersection point Qi of the grating 214G does not deviate from the geometric center of the corresponding grating 214G.

[0056] refer to Figure 1 , the top view of the grating 214 is shown as a combination having the apodized grating 214. For example, the grating 214 near the interface between the grating section 204 and the tapered section 202 or near the sides 204A and 204B adopts the shape of the grating 214A, 214B, 214C, or 214D, for example, in a quadrilateral shape or a convex octagonal shape, and the grating 214 near the sides 204C and 204D of the grating section 204 opposite to the tapered section 202 adopts the shape of the grating 214E, 214F, or 214G. However, the grating 214 shown is for illustrative purposes only. Figure 1 Layout of the grating 214 in the grating section 204 shown in FIG. Other combinations of apodized gratings 214A-214G are also within the contemplated scope of the present disclosure.

[0057] According to some embodiments, the degree of difference in shape, area, and thickness between the central grating Gc and the target grating 214 is determined according to the distance between the central grating Gc of the grating 214 and the target grating 214. According to some embodiments, the grating 214 includes a gradually decreasing surface area and thickness / depth from the central grating Gc to the edge grating Ge. According to some embodiments, the area ratio between the sum of the areas of all gratings 214 and the area of ​​the grating segment 204 is greater than about 60% or about 70% (e.g., in the range of about 75% to about 85%) to ensure high optical coupling efficiency and sufficient spacing margin of adjacent gratings 214.

[0058] Figure 5AShows a top view and a cross-sectional view of the tapered section 202 of the grating coupler 100 according to some embodiments of the present disclosure. According to various embodiments, the cross-sectional view is taken along the section line BB of the top view. Although only the cross-sectional view shown in the taper 202A is taken Figure 5A The configuration discussed below regarding the taper 202A is also applicable to the taper 202B.

[0059] The taper 202A or 202B has two ends, where the first end 502 coupled to the grating section 204 through the side 204A or 204B has a first height H1 and the second end 504 coupled to the waveguide 206 has a second height H2. The first height H1 and the second height H2 greater than the first height H1 are determined for achieving modal matching in the vertical direction. Referring to Figure 1 and Figure 5A , the upper surface of the first end 502 can be coplanar with the bottom surface of the grating 214 of the grating section 204. According to some embodiments, the taper 202 tapers from the first end 502 to the second end 504 for achieving optical modal matching and increasing the taper height. According to some embodiments, the height of the middle portion 506 between the first end 502 and the second end 504 of the taper 202A increases from the first end 502 to the second end 504. The middle portion 506 can have different topographical shapes on its upper surface. The first end 502 and the second end 504 of the taper 202A can have a flat or planar shape, while the middle portion 506 of the taper 202A can have a curved shape (shown in subfigure (a)), a ramp shape (shown in subfigure (b)), or a stepped shape with intermediate steps 512, 514, and 516 (shown in subfigure (c)). According to some embodiments, due to a smoother height increase, the curved shape (a) of the middle portion 506 can achieve better vertical modal conversion than the ramp shape (b) or the stepped shape (c). However, the curved shape may require a more complex (etching) processing operation than the ramp shape or the stepped shape. According to some embodiments, the stepped shape of the middle portion 506 has a third height H3 and a fourth height H4 of the steps 514 and 516 respectively, where the step heights are configured as H1 < H3 < H4 < H2. The step 512 can have a step height H1 that is substantially equal to the height of the first end 502. The stepped shape can use a simpler forming operation; however, the corners formed between adjacent steps can introduce more coupling losses.

[0060] Figure 5B Shows a top view of the tapered section 202 of the grating coupler 100 according to some embodiments of the present disclosure. Figure 5B The tapers 202A and 202B shown in Figure 5A are similar to the tapers 202A and 202B shown in subfigure (c) of Figure 5AThe subgraph (c) and Figure 5B The difference between the two is that, from a top view perspective, the sidewalls of the intermediate steps 512, 514, and 516 are not flush with the sidewalls of the cones 202A, 202B. According to some embodiments, the sidewalls of the intermediate steps 512, 514, and 516 taper from the first end 502 toward the second end 504. The sidewalls of the intermediate steps 512, 514, and 516 may be aligned with each other to form a common sidewall between the sidewalls of the cones 202A or 202B. The extension lines of the tapered common sidewalls of the intermediate steps 512, 514, and 516 may meet and form an angle θ, wherein the angle θ may be greater than the included angle γ of the focal points P1, P2 of the cones 202A, 202B. According to some embodiments, the sidewalls of the intermediate steps 512, 514, and 516 taper more than the tapered sidewalls of the cones 202A, 202B. According to some embodiments, the intermediate steps 512 , 514 , 516 have curved sidewalls on the side facing the grating segment 204 or the second end 504 .

[0061] Figure 6 A top view and a cross-sectional view of a grating coupler 100 according to some embodiments of the present disclosure are shown. The cross-sectional view is taken along the section line BB of the top view. The grating 214 may have different depths based on its relative position in the position diagram 200 for achieving optimal optical coupling efficiency. According to some embodiments of the present disclosure, the central grating Gc is aligned with the center of the optical fiber 104 and therefore receives the highest light energy. Therefore, the central grating Gc has the highest refraction level. According to some embodiments, the thickness or depth T1 of the central grating Gc is set to be substantially half of the total thickness T of the upper silicon layer 230 of the grating segment 204. According to some embodiments, since the remaining gratings 214 are positioned further away from the central grating Gc, the light energy they receive is reduced more. In order to achieve the highest optical coupling efficiency, when the grating 214 is arranged in a position corresponding to a portion of the optical fiber 104 other than the center of the optical fiber 104, its thickness or depth should be appropriately reduced. Reference Figure 6 , the depths T2, T3 of the gratings 214 are inversely proportional to their relative distances to the central grating Gc. In other words, the first grating 214-1 that is farther away from the central grating Gc than the second grating 214-2 will have a thickness or depth T3 that is less than the thickness or depth T2 of the second grating 214-2. According to some embodiments, the gratings 214 that are arranged closest to the four corners of the grating segment 204 have the lowest thickness or depth. According to some embodiments, each of the gratings 214 including the central grating Gc has a substantially flat bottom surface.

[0062] Fig. 7A , Figure 7B and Figure 7C Schematic diagram showing a position diagram 700 of the grating 214 of the grating coupler 100 according to some embodiments of the present disclosure. Fig. 7A , Figure 7B and Figure 7C The location diagrams 700A, 700B and 700C shown in FIG. 700 are similar to those shown in FIG. Figure 2 , and the main difference therebetween is that the equations applied to the position diagram 700 are different from those for concentric ellipses. Fig. 7A , the position diagram 700A comprises two sets of concentric circles, wherein the two sets of circles have respective common centers or focal points P1, P2, which serve as the focal points of the light beams of the grating cone 100. The region 710 marked by the intersection of the dashed circles represents the set of positions of the center of the grating 214 ( Fig. 7A not shown).

[0063] Similarly, refer to Figure 7B , the position diagram 700B includes two sets of concentric parabolas, wherein the two sets of parabolas have corresponding common foci P1, P2. The region 720 of the intersections marked by the dashed circles represents the set of positions of the center of the grating 214 ( Figure 7B not shown).

[0064] Similarly, refer to Figure 7C , the position diagram 700C includes two sets of concentric hyperbolas, wherein the two sets of hyperbolas have corresponding common foci P1, P2. The region 730 of the intersections marked by the dashed circles represents the set of positions of the center of the grating 214 ( Figure 7C not shown).

[0065] Fig. 8A A top view and a cross-sectional view of a grating coupler 800A according to some embodiments of the present disclosure are shown. The cross-sectional view is taken along the section line CC' of the top view of the grating coupler 800A. The grating coupler 800A is similar to the grating coupler 100 discussed previously, and these similar features will not be repeated for the sake of brevity. The difference of the grating coupler 800A is that reflectors 802 and 804 formed in the grating segment 204 are introduced. Figure 1 and Fig. 8A , the reflectors 802, 804 are used to reflect the light beams propagating toward the sides 204C, 204D opposite to the tapered section 202. Therefore, the light beams incident on the reflectors 802, 804 can be reflected back to the grating section 204 and propagate into the cone 202 by refraction of the grating 214. Therefore, the optical coupling efficiency can be increased. The reflectors 802 and 804 can be configured to form an arc shape adjacent to the edge grating 214.

[0066] According to some embodiments, reflectors 802, 804 are formed of a conductive material such as a metal. Exemplary metals forming reflectors 802, 804 may include tungsten, titanium, copper, aluminum, or the like. According to some embodiments, Fig. 8AAs shown in FIG. 8 , the reflector 802 or 804 has a curved shape from a top view perspective to increase the collection and focusing performance of the reflected light beam. Referring to the cross-sectional view of the grating coupler 800A, the reflector 802 or 804 is deposited on the sidewall of the upper silicon layer 230. Fig. 8A Although not illustrated in the figure, the reflectors 802 and 804 are arranged at the same level of the grating 214 so as to reflect the light beam into the grating 214 to enhance the refraction of the grating 214. According to some embodiments, the reflector 802 or 804 has a sidewall 802S including an L-shape formed on the upper surface and a sidewall of the upper silicon layer 230. The reflector 802 or 804 may be laterally surrounded by the upper silicon layer 230 and the cladding layer 240 from both sides of the reflector 802 or 804. The sidewall of the reflector 802 or the upper silicon layer 230 may form an angle β with the horizontal surface of the upper silicon layer 230, wherein the angle β may be less than 90 degrees to help reflect the light beam into the interior of the grating coupler 800A.

[0067] Figure 8B and Figure 8C 800B and 800C are similar to the top views of various grating couplers according to some embodiments of the present disclosure. Figure 1 or Fig. 8A , and for the sake of brevity these similar features will not be repeated. The difference between the grating coupler 800B and the grating coupler 800A is the arrangement of the reflectors 812, 814 formed in the grating segment 204. The reflectors 812, 814 each have a straight line or a strip shape. The reflectors 812, 814 may be parallel to the adjacent edge of the grating segment 204. Therefore, the light beam incident on the reflectors 812, 814 may be reflected back to the grating segment 204 and propagated into the cone 202 by refraction of the grating 214. Therefore, the optical coupling efficiency may be increased. The reflectors 812 and 814 may be arranged at an angle adjacent to the grating 214. According to some embodiments, the formation of the strip reflectors 812, 814 is simpler and more reliable than the formation of the arc reflectors 802, 804.

[0068] refer to Figure 8C, the difference between the grating coupler 800C and the grating coupler 800A or 800B lies in the arrangement of the reflectors 822, 824 formed in the grating section 204. The reflectors 822, 824 are formed by a plurality of individual reflective blocks arranged in a straight line or a curve. The reflectors 822, 824 may be parallel or non-parallel to the adjacent edge of the grating section 204. From a top view perspective, each of the reflective blocks may be in a quadrilateral shape, a circular shape, a polygonal shape, a strip shape, or the like. Therefore, the light beam incident on the reflectors 822, 824 may be reflected back to the grating section 204 and propagated into the cone 202 by refraction of the grating 214. Therefore, the optical coupling efficiency may be increased. The reflective blocks of the reflectors 822 or 824 may be arranged spaced apart from each other and formed into lines, rows, or arbitrary shapes as required and provide more design and manufacturing flexibility.

[0069] Fig.9A , Fig. 9B and Fig. 9C Demonstrating some embodiments of the present disclosure Fig. 8A , Figure 8B or Figure 8C 800 (including grating couplers 800A, 800B and 800C). Fig.9A , a reflector 902 is shown, which is similar to the reflectors 802, 804, 812, 814, 822, and 824 discussed previously. The reflector 902 may include a vertical portion having a sidewall 902S facing the upper silicon layer 230 and a horizontal portion arranged above the horizontal portion of the upper silicon layer 230, wherein the sidewall 902S of the vertical portion is perpendicular to the horizontal portion. The vertical arrangement of the sidewall 902S of the reflector 902 may help reflect the light beam back to the interior of the grating segment 204 and increase the optical coupling efficiency.

[0070] refer to Fig. 9B and Fig. 9C , the grating coupler 800 includes reflectors 904 and 906 shown with respective sidewalls 904S and 906S. According to some embodiments, from a cross-sectional view, the sidewalls 904S and 906S include curved shapes. The sidewall 904S includes a convex shape, while the sidewall 906S includes a concave shape. The curved shapes of the sidewalls 904S, 906S can be configured to direct and focus the reflected light beam toward a specific direction in the grating section 214 for improved light energy collection efficiency.

[0071] Fig. 10A , Fig. 10B and Fig. 10C 1 shows a top view of a grating coupler 1000 according to some embodiments of the present disclosure. The grating coupler 1000 is a one-dimensional grating coupler and is used in Figure 11000 is formed by a tapered section 1002 and a grating section 1004 coupled to the tapered section 1002. Different from the two-dimensional grating coupler 100 discussed previously, the grating coupler 1000 generally includes a single taper 1002 for guiding a main mode of the TE mode and the TM mode of the optical beam into or from the grating section 1002. In addition, the grating section 1002 includes a 3D grating 1014 configured to refract the optical beam into or from the tapered section 1002. According to some embodiments, the grating 1014 has a curved shape to increase the focusing effect of the refracted optical beam.

[0072] According to some embodiments, the grating coupler 1000 further includes reflectors 1022, 1032, and 1042, which correspond to the reflectors 802, 812, and 822 of the two-dimensional grating coupler 800, respectively. The materials, configurations, and methods of forming the reflectors 1022, 1032, and 1042 are similar to those of the reflectors 802, 812, and 822, and these similar aspects will not be repeated for the sake of brevity. According to some embodiments, the reflectors 1022, 1032, and 1042 can help capture a light beam propagating toward the side opposite to the grating section 1004 and the tapered section 1002, and reflect this light beam into the grating section 1004 and the tapered section 1002. Therefore, the optical coupling efficiency of the one-dimensional grating coupler 1000 can be improved.

[0073] Fig.11A is an initial design layout of the grating coupler 100 according to some embodiments of the present disclosure. Fig. 11B is a revised design layout 101B according to some embodiments of the present disclosure. FIG. 11C to FIG. 11J is a cross-sectional view of an intermediate stage of a method of forming a grating coupler 100 according to some embodiments of the present disclosure. Fig.12 is a flow chart of a method 1200 of forming a grating coupler 100 according to some embodiments of the present disclosure. It should be understood that Fig.12 Additional steps are provided before, during, and after the steps shown in , and some of the steps described below may be replaced or eliminated for additional embodiments of method 1200. The order of the steps may be changed. The same or similar materials, configurations, dimensions, processes, and / or operations as those described with respect to the previous embodiments may be used in the following embodiments, and their detailed descriptions may be omitted.

[0074] refer to Fig.11A , providing or receiving an initial design layout 101A of the grating coupler 100. The corresponding steps correspond to Fig.12 Step 1202. The initial design layout 101A may be similar to Figure 1, wherein the initial design layout 101A does not take into account the effects of lithography errors. An OPC operation has not yet been performed on the initial design layout 101A.

[0075] refer to Fig. 11B , using OPC operations to convert the initial design layout 101A into the revised design layout 101B. The corresponding steps correspond to Fig.12 Step 1204. With the help of the OPC operation, the layout of the manufactured grating coupler 100 will be more similar to the initial design layout 101A. According to some embodiments, sub-resolution auxiliary features (e.g., scattering strips 1103) are incorporated into the initial design layout 101A. According to some embodiments, the pattern of the grating coupler 100, such as the tapers 202A, 202B, or the grating segments 204, such as the edges of the grating segments 204 and the grating 214, are modified by serifs or hammerheads 1105 or rat teeth 1107.

[0076] FIG. 11C to FIG. 11J is a cross-sectional view of an intermediate stage of a method of manufacturing the grating coupler 100 based on the revised design layout 101B according to some embodiments of the present disclosure. Fig. 11C , providing, receiving or forming a substrate 1102. The corresponding steps correspond to Fig.12 Step 1206 of . According to some embodiments, substrate 1102 is a composite substrate (e.g., a silicon-on-insulator (SOI) substrate) and may include a lower silicon layer 210, an insulating layer 220, and an upper silicon layer 230 arranged in a stack. Lower silicon layer 210 may include a semiconductor material, such as silicon, germanium, silicon germanium, or other suitable materials. According to some embodiments, insulating layer 220 includes a dielectric material, such as silicon oxide, silicon nitride, or the like. Upper silicon layer 230 may be an epitaxial silicon layer.

[0077] refer to Fig.11D , defining the region of the grating coupler 100. The corresponding steps correspond to Fig.12 Step 1208. According to some embodiments, a region of the grating coupler 100 is formed and is laterally surrounded by the cladding layer 240. The grating coupler 100 may further include a tapered section 202 and a grating section 204. The cladding layer 240 may extend toward the insulating layer 220. The cladding layer 240 may include silicon oxide, silicon nitride, silicon oxynitride, or other suitable dielectric materials. According to some embodiments, the insulating layer 220 and the cladding layer 240 are formed of the same material.

[0078] refer to FIG. 11E to FIG. 11G , performing one or more patterning operations to form a taper with a stepped portion in the taper section 202. For example, forming a stepped shape of the tapers 202A and 202B of the taper section 202. The corresponding steps correspond to Fig.12Step 1210. According to some embodiments, steps 516, 514, and 512 are sequentially formed using photolithography and etching operations. The etching operations may include wet etching, dry etching, combinations thereof (e.g., reactive ion etching (RIE), or the like. Steps 516, 514, and 512 are etched to include step heights H4, H3, and H1, respectively, such as Figure 5A According to some embodiments, different photolithography and etching operations may be used to form Figure 5A The curved or sloped shape of the upper surface of the tapered section 202 shown in sub-figures (a) and (b) of FIG. According to some embodiments, the slope or curvature of the upper surface can be controlled by one or more etching and / or epitaxial growth operations. In addition, the tapered shape of the cones 202A, 202B and the converging sidewalls of the steps 512, 514, 516 from a top view perspective can be patterned during the patterning of the steps 512, 514 and 516 and the second end 502 of the cones 202A, 202B, or can alternatively be patterned in a separate patterning operation. According to some embodiments, in reference to FIG. Fig.11D and Fig.12 The tapered shape of the tapered section 202 and the quadrilateral shape of the grating section 204 are patterned during the step 1212 of defining the grating coupler 100 .

[0079] refer to Fig.11H , forming one or more patterning operations to form a grating 214 that is apodized in shape and depth. The corresponding steps correspond to Fig.12 Step 1212. The perimeter of the grating segment 204 may be determined and patterned. According to some embodiments, the top view shape and depth of the grating 214 are patterned according to its position in the position map 200 or other suitable position maps (e.g., position maps 700A, 700B, 700C). Figure 1 , Figure 2 , Figure 3A , Figure 3B , Figures 4A to 4G , Figure 5A and Figure 5B The shape of the apodization grating 214 is discussed, and reference is made to Figure 6 Discuss the depth of the apodization grating 214. The patterning operation may include photolithography and etching operations.

[0080] refer to Fig.11I , one or more reflectors 1106 are formed on the horizontal surface of the upper silicon layer 230. The corresponding steps correspond to Fig.12 Step 1214. The reflector 1106 may be similar to the reference FIG. 8A to FIG. 8C and FIG. 9A to FIG. 9C The reflectors 802, 804, 812, 814, 822, 824, 902, 904 and 906 discussed. The corresponding steps correspond to Fig.12 Step 1216 of the embodiment of the present invention is performed. The reflector 1106 may be formed by forming a trench in the upper silicon layer 230 or the insulating material 1104, followed by a deposition operation (e.g., physical vapor deposition (PVD), chemical vapor deposition (CVD), atomic layer deposition (ALD), plating, or the like). The reflector 1106 may include a metallic material (e.g., tungsten, copper, aluminum, titanium, or the like) or a dielectric material (e.g., silicon nitride) that may cause a light beam to reflect. The deposition of the reflector 1106 may be formed before or after forming the grating 214 or the tapered section 202.

[0081] refer to Fig.11J , the remaining portion of the cladding layer 240 is deposited above the grating coupler 100. The corresponding steps correspond to Fig.12 Step 1212. A cladding layer 240 is formed over the tapered section 202 and the grating section 204 of the grating coupler 100. The grating 214 is filled with the cladding layer 240. According to some embodiments, the tapered section 202 and the grating section 204 have coplanar upper surfaces.

[0082] According to some embodiments of the present disclosure, a method of forming a grating coupler includes: providing an initial design layout of the grating coupler, wherein the initial design layout includes: a tapered section including a pair of tapers; and a grating section coupled to the tapered section, the grating section having a grating array, wherein the grating includes a gradually changing shape from a first non-convex octagonal shape of a central grating at the center of the grating section to a second non-convex octagonal shape of an edge grating near an edge of the grating section, a convex octagonal shape, and a quadrilateral shape from a top view perspective. The method further includes: converting the initial design layout into a revised design layout through an optical proximity correction operation; and using the revised design layout to manufacture the grating coupler.

[0083] According to some embodiments of the present disclosure, a method of forming a grating coupler includes: providing a silicon-on-insulator (SOI) substrate; forming a grating segment and a pair of cones in a silicon layer of the SOI substrate, wherein each of the pair of cones forms a first end to a second end; and depositing an insulating material to cover the grating segment and the pair of cones. The grating segment includes a grating array, wherein the grating includes a gradually changing shape from a top view perspective, wherein a central grating includes a first non-convex octagonal shape, a first edge grating includes a second non-convex octagonal shape different from the first non-convex octagonal shape, and a second edge grating arranged near an interface between the grating segment and the cone segment includes a quadrilateral shape.

[0084] According to some embodiments of the present disclosure, a grating coupler includes: a tapered section including a pair of tapered shapes configured to transmit light of different polarizations; and a grating section configured to be optically coupled to an optical fiber. The grating section includes a grating array, and the degree of difference in shape, area, and thickness between the central grating and a first grating other than the central grating is determined according to a distance between the central grating of the grating and the first grating. The central grating includes a first non-convex octagonal shape, the first edge grating includes a second non-convex octagonal shape different from the first non-convex octagonal shape, and the second edge grating arranged near the interface between the grating section and the tapered section includes a convex octagonal or quadrilateral shape.

[0085] The foregoing summarizes the structures of several embodiments so that those skilled in the art can better understand aspects of the present disclosure. Those skilled in the art will appreciate that they can easily use the present disclosure as a basis for designing or modifying other processes and structures to achieve the same purposes and / or achieve the same advantages of the embodiments described herein. Those skilled in the art will also recognize that these equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions, and modifications herein without departing from the spirit and scope of the present disclosure.

[0086] Explanation of symbols

[0087] 100: Grating coupler

[0088] 100S: Upper surface

[0089] 101A: Initial Design Layout

[0090] 101B: Revised Design Layout

[0091] 104: Fiber Optic

[0092] 200: Location Map

[0093] 202: Conical section

[0094] 202A: First cone

[0095] 202B: Second section / cone

[0096] 204: Raster section

[0097] 204A: Side

[0098] 204B: Side

[0099] 204C: Side

[0100] 204D: Side

[0101] 206: Waveguide

[0102] 210: Lower silicon layer

[0103] 214: Raster

[0104] 214-1: First grating

[0105] 214-2: Second grating

[0106] 214A: Grating

[0107] 214B: Grating

[0108] 214C: Raster

[0109] 214D: Grating

[0110] 214E: Raster

[0111] 214F: Raster

[0112] 214G: Raster

[0113] 220: Insulation layer

[0114] 230: Upper silicon layer

[0115] 240: Coating

[0116] 302: Grating

[0117] 304: Grating

[0118] 502: first end

[0119] 504: Second end

[0120] 506: Middle part

[0121] 512: Middle step

[0122] 514: Middle step

[0123] 516: Middle step

[0124] 700A: Location Map

[0125] 700B: Location Map

[0126] 700C: Location Map

[0127] 710: District

[0128] 720: District

[0129] 730: District

[0130] 800: Grating Coupler

[0131] 800A: Grating Coupler

[0132] 800B: Grating Coupler

[0133] 800C: Grating Coupler

[0134] 802: Reflector

[0135] 802S: Sidewall

[0136] 804: Reflector

[0137] 812: Reflector

[0138] 814: Reflector

[0139] 822: Reflector

[0140] 824: Reflector

[0141] 902: Reflector

[0142] 902S: Sidewall

[0143] 904: Reflector

[0144] 904S: Sidewall

[0145] 906: Reflector

[0146] 906S: Sidewall

[0147] 1000: Grating Coupler

[0148] 1002: Conical section

[0149] 1004: Raster segment

[0150] 1014: One-dimensional grating

[0151] 1022: Reflector

[0152] 1032: Reflector

[0153] 1042: Reflector

[0154] 1102: substrate

[0155] 1103: Scattering bar

[0156] 1104: Insulation material

[0157] 1105: Serif or Hammerhead

[0158] 1106: Reflector

[0159] 1107: Rat Teeth

[0160] 1200: Method

[0161] 1202: Steps

[0162] 1204: Steps

[0163] 1206: Steps

[0164] 1208: Steps

[0165] 1210: Steps

[0166] 1212: Steps

[0167] 1214: Steps

[0168] 1216: Steps

[0169] a: first size / first length

[0170] A: Second size / first distance

[0171] A1: Part

[0172] b: Third size / second length

[0173] B: Fourth size / second distance

[0174] c: Fifth size / third length

[0175] C: Sixth size / third distance

[0176] C1: Concentric ellipses

[0177] C2: Concentric ellipses

[0178] d: Seventh size / fourth length

[0179] D: Eighth Dimension / Fourth Distance

[0180] G1: Grating

[0181] G2: Grating

[0182] G3: Grating

[0183] G4: Grating

[0184] Gc: Center grating

[0185] Ge: Edge Grating

[0186] H1: First Height

[0187] H2: Second Height

[0188] H3: The third height

[0189] H4: The fourth height

[0190] P1: Common Center or Focus

[0191] P2: Common Center or Focus

[0192] Q1: Intersection / Intersection / Center

[0193] Q2: Intersection / Intersection / Center

[0194] Q3: Center

[0195] Q4: Center

[0196] T: Total thickness

[0197] T1: Thickness / Depth

[0198] T2: Thickness / Depth

[0199] T3: Thickness / Depth

[0200] TE: Transverse Electrode

[0201] TM: Transverse Magnetic

[0202] α: Tilt angle

[0203] β: Angle

[0204] θ: Angle

[0205] γ: angle.

Claims

1. A grating coupler, characterized in that It includes: a tapered section comprising a pair of cones configured to transmit light of different polarizations; and a grating segment configured to be optically coupled to an optical fiber, wherein the grating segment comprises a grating array, wherein the difference in shape, area and thickness between the central grating and the first grating is determined according to the distance between the central grating of the grating and the first grating other than the central grating, wherein the central grating comprises a first non-convex octagonal shape, a first edge grating comprises a second non-convex octagonal shape different from the first non-convex octagonal shape, and a second edge grating arranged near an interface between the grating section and the tapered section comprises a convex octagonal or quadrilateral shape.

2. The grating coupler according to claim 1, characterized in that Each pair of the gratings is spaced apart by a different spacing value from the central grating to the first or second edge grating.

3. The grating coupler according to claim 1, characterized in that Each of the tapers has a height that increases from a first end coupled to a second end.

4. The grating coupler according to claim 1, characterized in that The first or second non-convex octagonal shape includes four protrusions and four tips, wherein each of the four protrusions extends from the center of the first or second non-convex octagonal shape, and each of the four protrusions tapers from the center of the first or second non-convex octagonal shape to the tip of the protrusion.

5. The grating coupler according to claim 1, characterized in that The grating includes a gradually decreasing surface area from the central grating to the edge grating.

6. The grating coupler according to claim 1, characterized in that The grating includes a gradually decreasing depth from the central grating to the edge grating.

7. The grating coupler according to claim 1, characterized in that The quadrilateral shape is a square shape.

8. The grating coupler according to claim 1, characterized in that Each of the gratings has a substantially flat surface at a bottom of each of the gratings.

9. The grating coupler according to claim 1, characterized in that Further included is a reflector disposed on a side of the grating section opposite the tapered section and configured to reflect the light beam back to the grating section.

10. The grating coupler according to claim 1, characterized in that The reflector includes a row of reflective blocks that are spaced apart from each other.

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