Waveguide
By forming a beveled profile at the edge of the waveguide cladding and depositing a thicker waveguide core layer, the problem of waveguide breakage was solved, optical performance and yield were improved, and the manufacturing process was simplified.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-19
- Publication Date
- 2026-04-07
AI Technical Summary
In existing technologies, waveguides are prone to cracking due to stress concentration during formation, especially when the deposition thickness is large, which affects optical performance and manufacturing yield.
By forming a beveled profile, especially a stepped profile, at the edge of the waveguide cladding layer to reduce stress concentration, a thick waveguide core layer is deposited using low-pressure chemical vapor deposition. Combined with etching and planarization processes, a waveguide core layer with a high refractive index difference is formed.
It effectively reduces the risk of waveguide breakage, improves optical performance and manufacturing yield, simplifies the manufacturing process, and reduces process costs.
Smart Images
Figure CN224096039U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present utility model relates to a waveguide and a forming method thereof, in particular to a bevel profile. BACKGROUND
[0002] Electronic signals and processes are a technology for signal transmission and processes. In recent years, optical signals and processes are used for more applications, particularly due to the use of fiber optic related applications as signal transmission. Generally, optical signals and processes are combined with electronic signals and processes to provide mature applications. For example, waveguides can be used as optical signal transmission. The optical signals within the waveguide can be controlled by optical modulators, such as optical phase shifters or other similar devices. SUMMARY
[0003] The present utility model provides a waveguide, comprising: a substrate having a circular edge portion; a waveguide cladding layer on the front side of the substrate, the outer edge of the waveguide cladding layer having a bevel profile, the bevel profile overlapping the substrate having the circular edge portion; and a waveguide core in the waveguide cladding layer, the top surface of the waveguide core being substantially coplanar with the top surface of the waveguide cladding layer.
[0004] In some embodiments, the bevel profile is a stepped profile.
[0005] In some embodiments, the stepped profile comprises a plurality of steps, each step having a different bevel depth measured from the outer edge of the substrate.
[0006] In some embodiments, the bevel depth of each step increases in a direction extending away from the substrate.
[0007] In some embodiments, the bevel profile is a sloped profile.
[0008] In some embodiments, the waveguide core has a thickness in the range of 600 nm to 800 nm.
[0009] In some embodiments, the back side of the substrate is free of the waveguide cladding layer.
[0010] In some embodiments, the waveguide further comprises a waveguide core layer conformally formed on the outer edge of the waveguide cladding layer, wherein the top surface of the waveguide cladding layer can be coplanar with the top surface of the waveguide core layer.
[0011] In some embodiments, the length of the edge portion of the substrate is in the range of 0.2 mm to 3.0 mm.
[0012] In some embodiments, the edge portion of the substrate surrounds each side of the central portion of the substrate. BRIEF DESCRIPTION OF DRAWINGS
[0013] The embodiments of this utility model will be described in detail below with reference to the accompanying drawings. It should be noted that, in accordance with industry standard practice, the various features are not drawn to scale. In fact, the dimensions of various components can be arbitrarily enlarged or reduced to clearly demonstrate the features of the embodiments of this utility model.
[0014] Figure 1 , Figure 2A , Figure 2B , Figure 3 , Figure 4 , Figure 5 ,and Figure 6 This is a cross-sectional schematic diagram of an intermediate stage in the fabrication of a waveguide, according to some embodiments.
[0015] Figure 7A and Figure 7B The diagram illustrates the bevel cleaning module and related bevel processes.
[0016] The reference numerals in the attached figures are explained as follows:
[0017] 100: Base
[0018] 100C: Central part
[0019] 100E: Edge
[0020] 101: Waveguide cladding
[0021] 101B: Backside waveguide cladding
[0022] 101F: Front waveguide cladding
[0023] 200: Bevel process
[0024] 201: Inclined Plane Profile
[0025] 203A: First Step
[0026] 203B: Second Step
[0027] 203C: The Third Tier
[0028] 301: Groove
[0029] 401: Waveguide core layer
[0030] 501: Waveguide Core
[0031] 503: Waveguide
[0032] 600: Backside Removal Process
[0033] 700: Angled surface cleaning module
[0034] 701: Clamping Plate
[0035] 703: front nozzles
[0036] 705: back nozzles
[0037] 707: feed
[0038] 709: discharge
[0039] 750: cleaning solution
[0040] BD1 : first bevel depth
[0041] BD2: second bevel depth
[0042] BD3: third bevel depth
[0043] D1 : first depth
[0044] L1 : first length
[0045] L2: second length
[0046] TH1 : thickness
[0047] TH2: thickness
[0048] TH3: thickness
[0049] W1 : first width
[0050] W2: second width DETAILED DESCRIPTION
[0051] The following disclosure provides many different embodiments, or examples, for implementing different components of the provided concepts. For purposes of explanation and ease of understanding, specific examples of configurations and components are set forth herein. Of course, those are just examples and are not intended to limit the application to the specific configurations illustrated and described. For example, references in the specification to a first component forming a first part of a second component can include embodiments where the first and second components are formed in direct contact, and can also include embodiments where additional components are formed between the first and second components such that the first and second components are not in direct contact. Further, the application can refer to various examples using reference numerals and / or letters. Such repetition is for the purpose of simplification and clarity and is not to be construed as a limitation of the various embodiments and / or configurations discussed.
[0052] Furthermore, spatially related terms such as “below,” “below,” “lower,” “higher,” “above,” and similar terms may be used here to describe the relationship between an element or component and other elements or components, as shown in the accompanying drawings. The spatially related terms attempt to encompass different orientations of these elements beyond those depicted in the drawings. When the device is rotated to other orientations (90° rotation or other orientations), the spatially relative descriptions used herein can also be interpreted according to the orientation after rotation.
[0053] According to various embodiments, a waveguide is formed on a substrate. The waveguide includes a waveguide core and a cladding layer surrounding it. A reshaping process is performed to modify the profile of the cladding layer, particularly by forming a bevel profile at the edges of the cladding layer. Forming a bevel profile at the edges of the cladding layer can better influence the crack dynamics between the cladding layer and the waveguide core layer (used to form the waveguide core). This can reduce the risk of cladding layer breakage. To reduce the risk of breakage, the cladding layer can be formed to a very large thickness. Therefore, the waveguide core can have a large thickness, which can improve optical performance.
[0054] Figure 1 , Figure 2A , Figure 2B , Figure 3 , Figure 4 , Figure 5 ,and Figure 6 Waveguide 503 is manufactured according to some embodiments (see reference). Figure 6 This is a cross-sectional view of the intermediate stage of the waveguide 503. The waveguide 503 includes a portion of the waveguide cladding 101 and the waveguide core 501. As detailed later, the bevel profile of the waveguide cladding 101 is reshaped before the waveguide core 501 is formed. In particular, reshaping the bevel profile of the waveguide cladding 101 reduces stress in the waveguide cladding 101, thus reducing the risk of breakage when the waveguide core layer (used to form the waveguide core 501) is deposited. The manufacturing yield of the waveguide 503 can therefore be improved. The reduced risk of breakage allows the waveguide core layer to be deposited to a considerable thickness, which improves the optical performance of the waveguide 503.
[0055] exist Figure 1In some embodiments, a substrate 100 is formed or provided. The substrate 100 can include a semiconductor substrate, such as a bulk semiconductor, an active layer of a semiconductor-on-insulator (SOI) substrate, or other similar structure, which can be doped or undoped. The semiconductor substrate can include other semiconductor materials, such as germanium (Ge); compound semiconductors, including silicon carbide (SiC), gallium arsenide (GaAs), gallium phosphide (GaP), indium phosphide (InP), indium arsenide (InAs), and / or indium antimonide (InSb); alloy semiconductors, including silicon germanium (SiGe), gallium arsenide phosphide (GaAsP), aluminum indium arsenide (AlInAs), aluminum gallium arsenide (AlGaAs), gallium indium arsenide (GaInAs), gallium indium phosphide (GaInP), and / or gallium indium arsenide phosphide (GaInAsP); or combinations thereof. Other substrates (such as multilayer or graded substrates) can also be used. The substrate 100 can be a wafer.
[0056] The semiconductor substrate has an active surface (e.g., an upward-facing surface in Figure 1 some embodiments) and an inactive surface (e.g., a downward-facing surface in Figure 1 some embodiments). The active surface is on a front side of the substrate 100, while the inactive surface is on a back side of the substrate 100. Elements are on the active surface of the semiconductor substrate. The elements can be active elements (e.g., transistors, diodes, or other similar components), capacitors, resistors, etc. The inactive surface can be free of elements. The elements can be formed in a suitable front end of line (FEOL).
[0057] Interconnect structures (not specifically shown) may be located on the active surface of a semiconductor substrate. Interconnect structures interconnect components on the semiconductor substrate to form an integrated circuit (IC). Interconnect structures may be formed in a suitable back-end of line (BEOL) process. Interconnect structures may include one or more dielectric layers and individual metal patterns within the dielectric layers. Acceptable dielectric materials for the dielectric layers include oxides (such as silicon oxide (SiO), aluminum oxide (Al2O3), or other similar materials), nitrides (such as silicon nitride (SiN), silicon oxynitride (SiON)), combinations thereof, or other similar materials. Low-k dielectric materials (such as carbon-doped silicon oxide), very low-k dielectric materials (such as porous carbon-doped silicon oxide), or other similar materials may be used to form the dielectric layers. Other acceptable dielectric materials may be utilized. Metal patterns may include vias and / or wires to interconnect components on the semiconductor substrate. Metallic patterns can be formed using conductive materials such as copper (Cu), cobalt (Co), aluminum (Al), gold (Au), combinations thereof, or other similar metals. Metallic patterns can also be formed through damascene processes (such as single damascene, double damascene, or other similar methods).
[0058] In the cross-sectional view, the base 100 has an elongated elliptical shape. In the cross-sectional view, the central portion 100C of the base 100 has a rectangular shape, while the edge portion 100E of the base 100 has a circular shape. In the top view, the base 100 may be circular (not specifically shown), with the edge portion 100E extending around each side of the central portion 100C. Thus, in the cross-sectional view, the edge portion 100E is adjacent to either side of the central portion 100C.
[0059] A waveguide cladding layer 101 is formed on a substrate 100. A portion of the waveguide cladding layer 101 will be a component of the waveguide. The waveguide cladding layer 101 can be formed from an optically suitable dielectric material. In some embodiments, the waveguide cladding layer 101 is formed from an oxide dielectric material (such as silicon oxide, germanium oxide, combinations thereof, or other similar materials), which can be formed using deposition methods (such as chemical vapor deposition, atomic layer deposition, or other similar methods). However, any suitable material and fabrication method can be used to form the waveguide cladding layer 101. The waveguide cladding layer 101 can be formed to any suitable thickness TH1. In some embodiments, the waveguide cladding layer 101 is formed to a thickness TH1 in the range of 2.0 μm to 4.0 μm (e.g., about 2.5 μm).
[0060] In the cross-sectional view, each edge portion 100E of the substrate 100 has a first length L1. In some embodiments, the first length L1 ranges from 0.2 mm to 3.0 mm. If the first length L1 of the edge portion 100E is less than 0.2 mm, there may not be enough space to form the desired geometry of the waveguide cladding layer 101 (described later) on the edge portion 100E of the substrate 100. If the first length L1 of the edge portion 100E is greater than 3.0 mm, the central portion 100C of the substrate 100 may be too small to accommodate the desired component. In the cross-sectional view, the central portion 100C of the substrate 100 has a second length L2. In some embodiments, the second length L2 ranges from 280 mm to 299.6 mm.
[0061] exist Figure 2A In the process, the contour of the waveguide cladding layer 101 (in the cross-sectional view) is reshaped by a bevel process 200. The waveguide cladding layer 101 is removed from the outer edge of the substrate 100 by the bevel process 200. As a result, the waveguide cladding layer 101 is divided into a front waveguide cladding layer 101F (retained on the front side of the substrate 100) and a back waveguide cladding layer 101B (retained on the back side of the substrate 100). The front waveguide cladding layer 101F and the back waveguide cladding layer 101B may be collectively referred to as the waveguide cladding layer 101.
[0062] The beveling process 200 alters the geometry of the edge 100E of the waveguide cladding layer 101 overlapping the substrate 100 to form a bevel profile 201 at the outer edge of the waveguide cladding layer 101. The beveling process 200 may include an oxide cleaning process. The oxide cleaning process may include an etching process (such as wet etching) using a suitable cleaning solution. The etching process may be performed in multiple steps, such that various portions of the waveguide cladding layer 101 are removed during each step of the etching process to form the desired geometry of the edge 100E of the waveguide cladding layer 101 overlapping the substrate 100. The beveling process 200 will be described in detail below with reference to Figures 7A and 7B.
[0063] The outer edges of the front waveguide cladding layer 101F and the back waveguide cladding layer 101B are reshaped using a beveling process 200. After beveling process 200, the outer edge of the substrate 100 extends beyond the outer edge of the waveguide cladding layer 101. The distance between the outer edge of the substrate 100 and the corresponding outer edge of the waveguide cladding layer 101 can be referred to as the “beveling depth” of the waveguide cladding layer 101. In the illustrated embodiment, the beveling depth of the front waveguide cladding layer 101F is substantially equal to (within process variations) the beveling depth of the back waveguide cladding layer 101B. In another embodiment, the beveling depth of the front waveguide cladding layer 101F differs from the beveling depth of the back waveguide cladding layer 101B. For example, the beveling depth of the front waveguide cladding layer 101F may be greater than the beveling depth of the back waveguide cladding layer 101B. In some embodiments, the minimum slope depth of the front waveguide cladding layer 101F is about 1 nm, while the minimum slope depth of the back waveguide cladding layer 101B is about 0.2 mm.
[0064] Figure 2B A detailed schematic diagram of the bevel profile 201 of the waveguide cladding 101 is shown after the bevel process 200. In this example, each bevel profile 201 is a stepped profile with multiple steps. For example, the stepped profile includes a first step 203A, a second step 203B, and a third step 203C. Each step may have its own bevel depth, which increases in the direction extending away from the substrate 100. In some embodiments, the first step 203A has a first bevel depth BD1 in the range of 0.5 mm to 1.5 mm (e.g., about 1 mm), the second step 203B has a second bevel depth BD2 in the range of 1.8 mm to 2.5 mm (e.g., about 2 mm), and the third step 203C has a third bevel depth BD3 in the range of 2.8 mm to 5 mm (e.g., about 3 mm). If the bevel depth of the steps is too large, an insufficient number of steps may be formed on the edge 100E of the substrate 100. If the slope depth is too small, it may not be possible to achieve individual stepped profiles.
[0065] Although Figure 2BThe stepped profile shown depicts three stepped profiles, which is merely one example of a stepped profile. A stepped profile can have any number of steps. Additionally, the stepped profile is merely one example of a bevel profile 201, and any suitable bevel profile can be formed for the waveguide cladding 101. For example, bevel profile 201 can be an inclined profile, each having a bevel depth that increases continuously in the direction extending away from the substrate 100.
[0066] exist Figure 3 In the process, a groove 301 is formed in the front waveguide cladding layer 101F using a suitable patterning process. The groove 301 can only be formed on the front side of the substrate 100. The patterning process may include one or more photolithography masking and etching processes.
[0067] Each groove 301 is formed to a first depth D1. In some embodiments, the first depth D1 is in the range of 100 nm to 1500 nm (e.g., about 350 nm or about 600 nm). Additionally, each groove 301 is formed to a first width W1. In some embodiments, the first width W1 is in the range of 800 nm to 5000 nm. If the groove 301 is formed to a first depth D1 that is too large or a first width W1 that is too large, the risk of breakage between the front waveguide cladding layer 101F and the structure subsequently formed in the groove 301 may be too great. If the groove 301 is formed to a first depth D1 that is too small or a first width W1 that is too small, the waveguide core subsequently formed in the groove 301 may be too small to perform the desired function.
[0068] exist Figure 4 In this process, a waveguide core layer 401 is formed in the groove 301 and on the waveguide cladding layer 101. The waveguide core layer 401 extends along the beveled profile 201 of the waveguide cladding layer 101. The waveguide core layer 401 can be formed from an optically suitable dielectric material. In some embodiments, the waveguide core layer 401 is formed from a nitride dielectric material (such as silicon nitride or other similar materials), which can be formed using deposition methods (such as chemical vapor deposition, atomic layer deposition, or other similar methods). However, any suitable material and manufacturing method can be used to form the waveguide core layer 401.
[0069] The waveguide core layer 401 is made of a different material than the waveguide cladding layer 101. Due to the difference in refractive index between the waveguide core layer 401 and the waveguide cladding layer 101, the waveguide core layer 401 can have high internal reflection, causing light to be confined within the waveguide core during operation, depending on the wavelength of the light and the reflectivity of the individual materials. In one embodiment, the refractive index of the waveguide core layer 401 is higher than that of the waveguide cladding layer 101.
[0070] In some embodiments, the waveguide core layer 401 is formed of silicon nitride. The waveguide core layer 401 is formed to a very large thickness TH2. In some embodiments, the waveguide core layer 401 is formed to a thickness TH2 in the range of 150 nm to 3000 nm (e.g., about 350 nm or about 400 nm). Forming a silicon nitride waveguide core layer 401 with a large thickness allows the resulting waveguide to have higher optical confinement and / or lower optical loss. This can thus improve the optical performance of the resulting waveguide. In some embodiments, the material (e.g., silicon nitride) of the waveguide core layer 401 is formed by a low-pressure chemical vapor deposition (LPCVD) process. The LPCVD process can be performed such that the waveguide core layer 401 conformally fills (and may overfill) the groove 301. In some embodiments, the LPCVD process is performed at a pressure in the range of 0.1 Pa to 0.4 Pa. Even at a large thickness, the thickness uniformity of the waveguide core layer 401 can be increased using the LPCVD process.
[0071] The coefficient of thermal expansion (CTE) of the waveguide core layer 401 material may be mismatched (e.g., significantly different) with that of the waveguide cladding layer 101 material. When the waveguide core layer 401 comprises silicon nitride and the waveguide cladding layer 101 comprises silicon oxide, the CTE of the waveguide core layer 401 may be greater than that of the waveguide cladding layer 101. In some embodiments, the waveguide core layer 401 has a CTE of approximately 3.2 ppm / °C, the waveguide cladding layer 101 has a CTE of approximately 0.5 ppm / °C, and the substrate 100 has a CTE of approximately 2.6 ppm / °C. The difference in CTE between the waveguide core layer 401 and the waveguide cladding layer 101 may be approximately 2.7 ppm / °C. The stress resulting from the CTE mismatch between the waveguide core layer 401 and the waveguide cladding layer 101 can be stored in the form of elastic energy. Forming the outer edge of the waveguide cladding 101 with a beveled profile 201 helps reduce stress caused by the coefficient of thermal expansion by altering the local stress in the waveguide cladding 101. Changing the local stress in the waveguide cladding 101 can affect fracture dynamics, reducing the risk of fracture even at large thicknesses.
[0072] exist Figure 5In this process, an excess portion of the waveguide core layer 401 is removed from outside the groove 301 in the front waveguide cladding layer 101F using a removal process, thereby forming a waveguide core 501. The waveguide core 501 includes the remaining portion of the waveguide core layer 401 in the groove 301. The removal process can be a planarization process, which planarizes the surface of the front waveguide cladding layer 101F and the portion of the waveguide core layer 401 in the groove 301. In some embodiments, the planarization process is a chemical mechanical polishing (CMP) process. After the planarization process, the top surface of the front waveguide cladding layer 101F can be substantially coplanar with the top surface of the waveguide core 501 (within process variations). However, any suitable process, such as a mechanical process (like a grinding process), can be used to planarize the material of the waveguide core layer 401 in the groove 301 with the front waveguide cladding layer 101F. After the removal process, the waveguide core layer 401 may remain on the back waveguide cladding layer 101B and on the outer edges of the substrate 100 and the front waveguide cladding layer 101F. The top surface of the front waveguide cladding layer 101F may be substantially coplanar with the portion of the waveguide core layer 401 left on the outer edge of the front waveguide cladding layer 101F (within the process variation).
[0073] The resulting waveguide 503 includes a waveguide core 501 and a portion of a front waveguide cladding layer 101F. That is, the waveguide 503 includes the waveguide core 501 and a surrounding portion of the front waveguide cladding layer 101F. In the cross-sectional view, the surrounding portion of the front waveguide cladding layer 101F may surround the waveguide core 501 on at least three sides of the waveguide core 501. The waveguide core 501 has a thickness TH3 and a second width W2. In some embodiments, the thickness TH3 is in the range of 600 nm to 800 nm, while the second width W2 is in the range of 1000 nm to 2500 nm.
[0074] exist Figure 6In this process, a back-side removal process 600 is performed to remove the waveguide core layer 401 and the back-side waveguide cladding layer 101B from the back side of the substrate 100. As a result, the back side of the substrate 100 is free of the waveguide cladding layer 101. Alternatively, the waveguide core layer 401 may be removed from the outer edge of the substrate 100 and / or the front waveguide cladding layer 101F. In some embodiments, the back-side removal process 600 is a wet cleaning or other similar method, performed using a suitable cleaning solution. The cleaning solution may include solvents such as deionized (DI) water, alkaline solutions, ammonia-based solutions (including, for example, sodium (Na), potassium (K), carbon (C), oxygen (O), hydrogen (H), or other similar materials), combinations thereof, or other similar chemicals. The cleaning solution may be applied toward the back side of the substrate 100 while the substrate 100 is rotated to distribute the cleaning solution across the back side of the substrate 100. The cleaning solution reacts with the waveguide core layer 401 and / or the waveguide cladding layer 101. The cleaning solution used to remove the back waveguide cladding layer 101B may be the same as or different from the cleaning solution used to remove the waveguide core layer 401. The cleaning solution may cover the back side of the substrate 100 and may extend upward along the outer edge of the substrate 100 during the back-side removal process 600. Additionally, the cleaning solution may extend a small amount on the front side of the substrate 100, such as a distance ranging from 0.8 mm to 2 mm from the outer edge of the substrate 100.
[0075] After the backside removal process 600, waveguide 503 remains on the front side of substrate 100, with its waveguide core layer 401 and backside waveguide cladding layer 101B removed from the back side of substrate 100. Furthermore, after partially removing the waveguide core layer 401 via the backside removal process 600, the front side waveguide cladding layer 101F remaining on the front side of substrate 100 has a beveled profile 201.
[0076] Waveguide 503 can be used to interconnect elements of substrate 100. For example, substrate 100 may include photonic components. The photonic components transmit and receive optical signals and convert the optical signals into electrical signals. Elements of substrate 100 can be interconnected through signal paths including electrical signal paths (which pass through conductive interconnects) and optical signal paths (which pass through waveguide 503) to form an integrated circuit.
[0077] Additional components (not shown separately) may be subsequently formed. For example, another waveguide cladding layer may be formed on the waveguide core 501. The waveguide 503 may further include a surrounding portion above the waveguide cladding layer. Additionally, die connectors may be formed for external connection to an integrated circuit on the substrate 100. The die connectors may be adjacent to the waveguide 503 and may extend through the front waveguide cladding layer 101F. Similarly, a passivation layer may be formed to protect the substrate 100.
[0078] The resulting wafer (including the substrate 100 and the waveguide 503 above it) can be single-crystallized in subsequent processes to form integrated circuit dies. The single-crystallization process single-crystallizes adjacent regions of the wafer to each other. The resulting integrated circuit dies originate from the single-crystallized regions of the wafer.
[0079] Figure 7A The diagram illustrates the inclined surface cleaning module 700, which can be used in the inclined surface process 200 (see reference). Figure 2A During this process, the inclined surface cleaning module 700 is used for a wet cleaning process, but other types of processes can also be used to perform the inclined surface process 200 and achieve the inclined surface profile 201. The inclined surface cleaning module 700 includes a chuck 701, a front nozzle 703, a back nozzle 705, a feed 707, and an discharge 709. The substrate 100 is held in place by the chuck 701 within the inclined surface cleaning module 700. The chuck 701 can be a vacuum chuck, which uses decompression to fix the substrate 100. The chuck 701 holds the substrate 100 in position while the front nozzle 703 and the back nozzle 705 apply cleaning solution to the substrate 100.
[0080] The front nozzle 703 can be located above the substrate 100, held in place by the clamp 701, and guided to apply the cleaning solution from the interior of the substrate 100 toward the outer edge of the front side of the substrate 100. The back nozzle 705 can be positioned as a mirror image of the front nozzle 703 and located below the substrate 100, held in place by the clamp 701, and guided to apply the cleaning solution from the interior of the substrate 100 toward the outer edge of the back side of the substrate 100. Multiple etching cycles can be performed, and the positions of the front nozzle 703 and the back nozzle 705 can be adjusted to change the interface between the cleaning solution and the substrate 100 between each etching cycle.
[0081] Feed 707 is used to introduce a cleaning solution. The cleaning solution may include an etchant suitable for removing the waveguide cladding 101, such as hydrofluoric acid (HF) or other similar chemicals. In some embodiments, the cleaning solution may also include a desiccant, such as nitrogen (N2). However, during the beveling process 200, any suitable cleaning solution can be used to remove the waveguide cladding 101. Furthermore, discharge 709 can act as a drain, where the portion of the waveguide cladding 101 removed and the cleaning solution can be discharged by the beveling cleaning module 700. Discharge 709 may include the venting of process gases.
[0082] Figure 7B This is a simplified process diagram illustrating the bevel process 200 in the bevel cleaning module 700 according to some embodiments. A clamp 701 holds the substrate 100 in place, while a front nozzle 703 and a back nozzle 705 apply a cleaning solution 750 toward the outer edge of the substrate 100 to form a bevel profile 201 in the outer edge of the waveguide cladding layer 101 (see reference).Figure 2A In some embodiments, the beveling process 200 removes a portion of the waveguide cladding 101 in a series of etching cycles, with a cleaning solution 750 applied to the desired locations. The positions of the front nozzle 703 and the back nozzle 705 can be adjusted between each etching cycle to interface with the waveguide cladding 101 at different locations, thereby reshaping the outer edge of the waveguide cladding 101 into the desired beveling profile 201. For example, the front nozzle 703 and the back nozzle 705 can be moved further away from the outer edge of the substrate 100 after each etching cycle, or they can be moved closer to the outer edge of the substrate 100 after each etching cycle. In some embodiments, the substrate 100 is maintained at a process temperature in the range of about 50°C to 80°C during the beveling process 200. In some embodiments where the beveling profile 201 is a stepped profile, the etching depth of each step (e.g., the beveling etching depth) can range from 0.2 mm to 3.0 mm.
[0083] The embodiment offers several advantages. By forming a beveled profile 201 in the front waveguide cladding layer 101F, localized stress at the edge 100E of the substrate 100 can be reduced, mitigating the risk of fracture formation during the deposition of the waveguide core layer 401 with a significant thickness. As a result, the waveguide core layer 401 can be deposited to a significant thickness in a single deposition process, simplifying the manufacturing process and reducing the associated process costs of multi-step deposition processes. This, in turn, improves the optical performance and yield of the waveguide 503. Specifically, a waveguide core 501 with a significant thickness allows the resulting waveguide 503 to have higher optical confinement and / or lower optical loss.
[0084] In one embodiment, a method for forming a waveguide includes: depositing a waveguide cladding layer on a substrate, wherein, in a cross-sectional view, the substrate has a central portion and an edge portion adjacent to the central portion; reshaping the waveguide cladding layer to form a beveled profile in the waveguide cladding layer on the edge portion of the substrate; forming a groove in the waveguide cladding layer; depositing a waveguide core layer in the groove and on the waveguide cladding layer, the waveguide core layer extending along the beveled profile of the waveguide cladding layer; and planarizing the waveguide core layer and the waveguide cladding layer to form a waveguide core, the waveguide core including a portion of the waveguide core layer in the groove.
[0085] In some embodiments, the waveguide core layer is deposited using a low-pressure chemical vapor deposition process. In some embodiments, the waveguide cladding layer is formed of silicon oxide, and the waveguide core layer is formed of silicon nitride. In some embodiments, the substrate is maintained at a temperature between 50°C and 80°C during waveguide cladding remodeling. In some embodiments, remodeling the waveguide cladding layer includes performing a series of etch cycles using an etchant, wherein the interface between the etchant and the waveguide cladding layer changes between each etch cycle. In some embodiments, the bevel profile is a stepped profile. In some embodiments, the waveguide core layer has a thickness ranging from 150 nm to 3000 nm.
[0086] In one embodiment, a method for forming a waveguide includes: forming a front waveguide cladding layer on a substrate, the outer edge of the front waveguide cladding layer having a first inclined profile, the front waveguide cladding layer comprising a first material; forming a groove in the front waveguide cladding layer; and forming a waveguide core in the groove, the top surface of the waveguide core being substantially coplanar with the top surface of the front waveguide cladding layer, the waveguide core comprising a second material, the refractive index of the second material being higher than the refractive index of the first material.
[0087] In some embodiments, the first bevel profile is a stepped profile, including a plurality of steps, each step having a different bevel depth. In some embodiments, the waveguide formation method further includes forming a back waveguide cladding layer on a substrate, the outer edge of the back waveguide cladding layer having a second bevel profile. In some embodiments, the front waveguide cladding layer has a first bevel depth measured from the outer edge of the substrate, the back waveguide cladding layer has a second bevel depth measured from the outer edge of the substrate, and the first bevel depth is substantially equal to the second bevel depth. In some embodiments, the front waveguide cladding layer has a first bevel depth measured from the outer edge of the substrate, the back waveguide cladding layer has a second bevel depth measured from the outer edge of the substrate, and the first bevel depth is different from the second bevel depth. In some embodiments, the waveguide formation method further includes removing the back waveguide cladding layer from the substrate, while the front waveguide cladding layer remains on the substrate.
[0088] In one embodiment, a waveguide includes: a substrate having a circular edge portion in a cross-sectional view; a waveguide cladding layer on the front side of the substrate, the outer edge of the waveguide cladding layer having a beveled profile overlapping the circular edge portion of the substrate; and a waveguide core in the waveguide cladding layer, the top surface of the waveguide core being substantially coplanar with the top surface of the waveguide cladding layer.
[0089] In some embodiments, the slope profile is a stepped profile. In some embodiments, the stepped profile includes multiple steps, each step having a different slope depth measured from the outer edge of the substrate. In some embodiments, the waveguide core has a thickness in the range of 600 nm to 800 nm. In some embodiments, the back side of the substrate does not contain a waveguide cladding layer. In some embodiments, the waveguide cladding layer includes a first material, and the waveguide core includes a second material, wherein the refractive index of the second material is higher than that of the first material. In some embodiments, the first material is silicon oxide, and the second material is silicon nitride.
[0090] The features of several embodiments have been summarized above to enable those skilled in the art to better understand the viewpoints of the present invention. Those skilled in the art should understand that other processes and structures can be easily designed or modified based on the embodiments of the present invention to achieve the same purpose and / or advantages as the embodiments described herein. Those skilled in the art should also understand that such equivalent structures do not depart from the concept and scope of the present invention, and various changes, substitutions, and replacements can be made without departing from the concept and scope of the present invention.
Claims
1. A waveguide, characterized in that, include: A base having a circular edge; A waveguide cladding layer, on the front side of the substrate, has an outer edge with a beveled profile that overlaps the circular edge portion of the substrate; and A waveguide core is located within the waveguide cladding layer, and the top surface of the waveguide core is coplanar with the top surface of the waveguide cladding layer.
2. The waveguide as described in claim 1, characterized in that, The slope profile is a stepped profile.
3. The waveguide as described in claim 2, characterized in that, The stepped profile includes multiple steps, each with a different slope depth measured from the outer edge of the base.
4. The waveguide as described in claim 3, characterized in that, The depth of the slope of each step increases in the direction that extends away from the base.
5. The waveguide as described in claim 1, characterized in that, The slope profile is an inclined profile.
6. The waveguide as described in claim 1, characterized in that, The waveguide core has a thickness ranging from 600 nm to 800 nm.
7. The waveguide as described in claim 1, characterized in that, The back side of the substrate does not contain the waveguide cladding layer.
8. The waveguide as described in claim 1, characterized in that, It also includes a waveguide core layer, which is compliantly formed on the outer edge of the waveguide cladding layer, wherein the top surface of the waveguide cladding layer may be coplanar with the top surface of the waveguide core layer.
9. The waveguide as described in claim 1, characterized in that, The length of the edge portion of the substrate ranges from 0.2 mm to 3.0 mm.
10. The waveguide as claimed in claim 1, characterized in that, The edge of the base surrounds each side of a central portion of the base.