Stray light control module, preparation method thereof and photonic integrated chip

Abstract

The invention provides a stray light control module, a preparation method thereof and a photon integrated chip, and the side wall of a groove facing the incident direction of stray light is set to be a tooth-shaped side wall, and the tooth-shaped side wall is set to be a non-arc-shaped tooth structure in which non-arc-shaped convex teeth and non-arc-shaped concave teeth are combined. Therefore, the metal reflecting layer arranged in the groove is provided with a non-arc tooth structure of the groove tooth-shaped side wall, the structure can scatter stray light entering the semiconductor top layer out in multiple directions in a non-directional mode, the spatial coherence of the stray light can be effectively damaged, the reflecting efficiency of the stray light is improved, and the service life of the stray light is prolonged. The problems of insufficient stray light absorption and easy formation of hot spots due to stray light absorption by doping are avoided, and the overall performance and stability of the PIC are improved. The preparation method of the stray light control module is prepared through a multi-mask photonics process, can be compatible with a traditional silicon optical device manufacturing process, is easy to prepare and realize industrial production, and has good market value.

Description

Technical Field

[0001] The present invention belongs to the technical field of integrated optical device design and manufacturing, and in particular relates to a stray light control module and a preparation method thereof, and a photon integrated chip. Background Art

[0002] In today's optical communication and photonic integration fields, as technology develops towards higher performance and smaller size, photonic integration (PIC) plays a core role. Photonic integrated chips are designed to integrate multiple optical functional devices on a single chip to achieve complex and efficient optical signal processing.

[0003] PIC includes various photonic components that receive and / or output optical signals. Some optical components in PIC, such as optical waveguides, optical input / output couplers, laser couplers, etc., may generate stray optical signals. Stray optical signals can cause crosstalk between optical components or form parasitic optical paths in the detector, forming background optical noise. For example, the laser source in PIC, especially the reflective semiconductor optical amplifier (RSOA) in the laser cavity, is the main source of stray light. Although precise alignment can couple light into the waveguide, such as Figure 1 As shown in Figure 2, a large portion of light (stray light) is still trapped in the waveguide chip. Therefore, effective management of stray light is crucial to improving the signal-to-noise ratio of PIC.

[0004] Currently, semiconductor doping regions are often used to absorb this stray light, but this method has limitations. First, the doping concentration is often not enough to absorb all stray light. Second, the absorbed light will be converted into heat, forming hot spots on the photonic integrated circuit.

[0005] It should be noted that the above introduction to the technical background is only for the convenience of providing a clear and complete description of the technical solutions of the present application and for the convenience of understanding by those skilled in the art. It cannot be considered that the above technical solutions are well known to those skilled in the art simply because they are described in the background technology section of the present application. Summary of the invention

[0006] In view of the shortcomings of the prior art described above, the object of the present invention is to provide a stray light control module and a preparation method thereof and a photonic integrated chip, which are used to solve the problem that the prior art method of absorbing the stray light generated in the PIC by setting a semiconductor doped region has a doping concentration that is insufficient to absorb all the stray light and the absorbed light is converted into heat, forming a hot spot on the photonic integrated circuit.

[0007] In order to achieve the above-mentioned object and other related objects, the present invention provides a stray light control module, the stray light control module comprising:

[0008] A substrate, comprising a base, an insulating layer and a semiconductor top layer arranged in sequence;

[0009] Two grooves are arranged in the semiconductor top layer at intervals, and the grooves extend from the surface of the semiconductor top layer to the bottom of the semiconductor top layer, and a waveguide is formed between two adjacent grooves;

[0010] A metal reflective layer, at least disposed on the sidewall and bottom of the groove;

[0011] Among them, the side wall of the groove facing the incident direction of stray light is set as a toothed side wall, and the cross-section of the toothed side wall includes a plurality of non-arc-shaped raised teeth extending outward along the long side direction of the groove and arranged at intervals, and a non-arc-shaped recessed tooth extending inward along the long side direction of the groove is formed between two adjacent non-arc-shaped raised teeth.

[0012] Optionally, the waveguide is a straight waveguide or a curved waveguide.

[0013] Furthermore, the length direction of the groove has an inclination angle with the light propagation direction in the waveguide; when the waveguide is a straight waveguide, the inclination angle is 40° to 70°; when the waveguide is a curved waveguide, the inclination angle is 20° to 75°.

[0014] Optionally, the stray light control module further includes a stray light absorption region for absorbing stray light, the groove is located in a middle area of ​​the stray light absorption region, and the waveguide is formed between two adjacent stray light absorption regions.

[0015] Furthermore, the width of the groove is 5 μm to 30 μm, and the width of the stray light absorption region is 25 μm to 50 μm.

[0016] Furthermore, the dopant of the stray light absorption region includes one of boron, arsenic, boron difluoride, phosphorus and antimony, and the doping concentration of the stray light absorption region is 1×10 18 / cm3~5×10 19 / cm3.

[0017] Optionally, an adhesion barrier layer is further disposed under the surface of the metal reflective layer; and a metal passivation layer is disposed on the surface of the metal reflective layer.

[0018] Furthermore, the metal reflective layer is also provided on the semiconductor top layer in a preset area connected to the groove.

[0019] Furthermore, the material of the metal reflective layer includes aluminum; the thickness of the metal reflective layer located on the side wall of the groove is 350nm~450nm, the thickness of the metal reflective layer located on the top layer of the semiconductor is 1μm~1.4μm, and the width of the preset area is 3μm~5μm.

[0020] Optionally, the non-arc-shaped raised teeth and the non-arc-shaped recessed teeth on the toothed side wall are arranged in a non-periodic manner.

[0021] Optionally, the horizontal cross-sectional shape of the non-arc convex teeth and the non-arc concave teeth on the toothed side wall is a triangle, a rectangle or a polygon.

[0022] Optionally, the side wall of the groove on the other side opposite to the side wall facing the incident direction of the stray light is also configured as the toothed side wall.

[0023] The present invention further provides a photonic integrated chip, wherein the photonic integrated chip comprises the stray light control module as described in any one of the above items.

[0024] The present invention also provides a method for preparing a stray light control module, the method comprising the following steps:

[0025] Providing a substrate, the substrate comprising a base, an insulating layer and a semiconductor top layer arranged in sequence;

[0026] Two grooves and a waveguide between the two grooves are formed on the semiconductor top layer; wherein the groove extends from the surface of the semiconductor top layer to the bottom of the semiconductor top layer, and the side wall of the groove facing the incident direction of stray light is set as a toothed side wall, and the cross section of the toothed side wall includes a plurality of non-arc-shaped raised teeth extending outwardly along the long side direction of the groove and arranged at intervals, and a non-arc-shaped recessed tooth extending inwardly along the long side direction of the groove is formed between two adjacent non-arc-shaped raised teeth;

[0027] A metal reflective layer is formed at least on the sidewall and the bottom of the trench.

[0028] Optionally, before forming the groove and the waveguide, the method further includes forming a stray light absorption region in the semiconductor top layer; wherein the groove is located in the middle area of ​​the stray light absorption region, and the waveguide is formed between two adjacent stray light absorption regions.

[0029] Optionally, the method of forming the groove and the waveguide includes:

[0030] A hard mask layer and a photoresist layer are sequentially formed on the surface of the semiconductor top layer, and the photoresist layer is patterned by photolithography to form a patterned photoresist layer;

[0031] Etching the hard mask layer based on the patterned photoresist layer to obtain a patterned hard mask layer and then removing the patterned photoresist layer; wherein the patterned hard mask layer defines a groove area and limits a waveguide area;

[0032] Using a photolithography process and based on an etching selectivity ratio between the patterned hard mask layer and the semiconductor top layer, the semiconductor top layer is respectively etched to form the groove and the waveguide in the groove region and the defined waveguide region;

[0033] The remaining patterned hard mask layer is removed.

[0034] Furthermore, the material of the semiconductor top layer includes silicon; and the material of the hard mask layer includes silicon oxide.

[0035] Optionally, the metal reflective layer is further disposed on the semiconductor top layer in the preset area where two grooves are connected, and the method for forming the metal reflective layer includes:

[0036] Depositing a metal reflective material layer on the surface of the groove and the surface of the semiconductor top layer;

[0037] forming a photoresist layer on the surface of the metal reflective material layer, and performing photolithography patterning on the photoresist layer to form a patterned photoresist layer;

[0038] Wet etching the metal reflective material layer based on the patterned photoresist layer to obtain the metal reflective layer;

[0039] The remaining patterned photoresist layer is removed.

[0040] Furthermore, before forming the metal reflective material layer, a step of depositing an adhesion barrier layer on the surface of the groove and the surface of the semiconductor top layer is included; after forming the metal reflective layer, a step of depositing a metal passivation layer on the surface of the metal reflective layer is included.

[0041] Furthermore, the metal passivation layer is also formed on the surface of the waveguide as a cladding of the waveguide.

[0042] As described above, the stray light control module of the present invention is provided by setting the groove sidewall facing the incident direction of the stray light as a toothed sidewall, and the toothed sidewall is provided as a non-arc tooth structure combining a non-arc convex tooth and a non-arc concave tooth, and the depth of the non-arc tooth is consistent with the groove depth, so that the metal reflective layer filled in the groove has a non-arc tooth structure of the groove toothed sidewall, that is, a metal reflector interface with a non-arc tooth structure, which can scatter the stray light entering the semiconductor top layer toward the waveguide in multiple directions in an undirected manner, and can effectively destroy the spatial coherence of the stray light, improve the reflection efficiency of the stray light, avoid the problem of insufficient absorption of the stray light caused by absorbing the stray light by doping and the problem of easy formation of hot spots by absorption, and easily improve the performance of the PIC, and improve the overall performance and stability of the PIC. The stray light control module prepared by the preparation method of the stray light control module of the present invention is a groove structure, prepared by a multi-mask photonics process, compatible with the traditional silicon photonic device manufacturing process, easy to prepare and realize industrial production, and has good market value. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The included drawings are used to provide a further understanding of the embodiments of the present application, which constitute a part of the specification, are used to illustrate the implementation of the present application, and together with the text description, explain the principles of the present application. Obviously, the drawings described below are only some embodiments of the present application.

[0044] Figure 1 Shown is a schematic structural diagram of a stray light control module according to an embodiment of the present invention, including a top view structural diagram (left figure) and a cross-sectional structural diagram at AA (right figure).

[0045] Figure 2 Display as Figure 1 Schematic diagram of the top view structure of the grooves and the metal reflective layer in the stray light control module.

[0046] Figure 3 Display as Figure 1 Schematic diagram of the top view structure of the groove in the stray light control module.

[0047] Figure 4 It is a schematic diagram of a top view of the structure in which the stray light control module of the present invention scatters the stray light emitted from the laser cavity.

[0048] Figure 5 It is a schematic diagram of the top view of the structure in which the stray light control module of the present invention scatters the stray light emitted from the Euler bend waveguide.

[0049] Figures 6 to 18 It is a schematic diagram showing the structure of each step in the method for preparing a stray light control module according to an embodiment of the present invention, Figure 6 , Fig. 9 , Fig.12 , Fig.13 , Fig.15 , Fig.17 They include a top view structure schematic diagram (left) and a cross-sectional structure schematic diagram at AA (right). Figure 7 , Figure 8 , Fig.10 , Fig.11 , Fig.14 , Fig.16 and Fig.18 It is a schematic diagram of the cross-sectional structure at the corresponding AA.

[0050] Component number description

[0051] 10 Substrate

[0052] 100 Base

[0053] 101 Insulation layer

[0054] 102 Semiconductor Top Layer

[0055] 103 Stray light absorption area

[0056] 11 Hard mask layer

[0057] 110 Patterned hard mask layer

[0058] 111 Groove area

[0059] 112 Waveguide outer groove area

[0060] 12 Photoresist layer

[0061] 120 Patterned photoresist layer

[0062] 13 Groove

[0063] 130 Toothed side wall

[0064] 131 Non-arc raised teeth

[0065] 132 Non-arc recessed teeth

[0066] 14 Waveguide outer groove

[0067] 15 Waveguide

[0068] 16 Adhesion barrier layer

[0069] 17 Metal reflective layer

[0070] 18 Metal passivation layer

[0071] 19 Laser Cavity

[0072] 20 Stray light

[0073] 21 Direction of light propagation DETAILED DESCRIPTION

[0074] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0075] It should be emphasized that the term “include / comprises” when used herein refers to the presence of features, integers, steps or components, but does not exclude the presence or addition of one or more other features, integers, steps or components.

[0076] Features described and / or illustrated with respect to one embodiment may be used in the same or similar manner in one or more other embodiments, combined with features in other embodiments, or substituted for features in other embodiments.

[0077] For example, when describing the embodiments of the present invention in detail, for the sake of convenience, the cross-sectional view showing the device structure will not be partially enlarged according to the general scale, and the schematic view is only an example, which should not limit the scope of protection of the present invention. In addition, in actual production, the three-dimensional space dimensions of length, width and depth should be included.

[0078] For ease of description, spatially relative terms such as "under", "below", "below", "below", "above", "on", etc. may be used herein to describe the relationship of one element or feature shown in the drawings to other elements or features. It will be understood that these spatially relative terms are intended to encompass other orientations of the device in use or operation in addition to the orientation depicted in the drawings. In addition, when a layer is referred to as being "between" two layers, it can be the only layer between the two layers, or one or more intervening layers may also be present.

[0079] In the context of the present application, a structure in which a first feature is described as being "above" a second feature may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features are formed between the first and second features, such that the first and second features may not be in direct contact.

[0080] It should be noted that the illustrations provided in this embodiment are only used to illustrate the basic concept of the present invention in a schematic manner, and therefore the illustrations only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0081] Embodiment 1

[0082] like Figures 1 to 3 As shown, this embodiment provides a stray light control module, and the stray light control module includes:

[0083] The substrate comprises a base 100, an insulating layer 101 and a semiconductor top layer 102 arranged in sequence;

[0084] Two grooves 13 are disposed in the semiconductor top layer 102 at intervals, and the grooves 13 extend from the surface of the semiconductor top layer 102 to the bottom of the semiconductor top layer 102, and a waveguide 15 is formed between two adjacent grooves 13;

[0085] A metal reflective layer 17, at least disposed on the sidewall and bottom of the groove 13;

[0086] Among them, Figure 3 As shown, the side wall of the groove 13 facing the incident direction of the stray light is set as a toothed side wall 130, and the cross-section of the toothed side wall 130 includes a plurality of non-arc-shaped raised teeth 131 extending outwardly along the long side direction of the groove 13 and arranged at intervals, and a non-arc-shaped recessed tooth 132 extending inwardly along the long side direction of the groove 13 is formed between two adjacent non-arc-shaped raised teeth 131.

[0087] It should be noted that the non-arc-shaped raised teeth 131 extend outwardly along the long side of the groove 13, and the non-arc-shaped recessed teeth 132 extend inwardly along the long side of the groove 13, which refers to a two-dimensional plane perpendicular to the depth direction of the groove 13. Taking the groove 13 as a reference object, the non-arc-shaped raised teeth 131 are defined as extending away from the long side of the groove 13, and the non-arc-shaped recessed teeth 132 are defined as extending toward the long side of the groove 13. In addition, the metal reflective layer 17 is at least provided on the sidewall and bottom of the groove 13. Figure 2 In the embodiment, the metal reflective layer 17 is disposed on the sidewall and bottom of the groove 13 and is also disposed in a predetermined area (such as Figure 2 The semiconductor top layer 102 is formed in the area of ​​width W3 in the semiconductor top layer 102. Figure 2 In the top view, the groove 13 is shown with a dotted line to facilitate understanding of the contour shape of the groove 13.

[0088] The stray light control module of the present embodiment sets the groove sidewall facing the incident direction of the stray light as a toothed sidewall, and the toothed sidewall is set as a non-arc tooth structure combining a non-arc convex tooth and a non-arc concave tooth, and the depth of the non-arc tooth is consistent with the groove depth. Therefore, the metal reflective layer filled in the groove has the non-arc tooth structure of the groove toothed sidewall, that is, the metal reflector interface with the non-arc tooth structure. This structure can scatter the stray light entering the semiconductor top layer toward the waveguide in multiple directions in an undirected manner, and can effectively destroy the spatial coherence of the stray light, improve the reflection efficiency of the stray light, avoid the problem of insufficient absorption of the stray light caused by absorbing the stray light by doping and the problem of easy formation of hot spots by absorption, and easily improve the performance of the PIC, and improve the overall performance and stability of the PIC.

[0089] As an example, the substrate 100 may be a silicon substrate, a germanium substrate, a silicon germanium substrate, a silicon carbide substrate, etc.; the insulating layer 101 may be any suitable dielectric layer; the semiconductor top layer 102 may be a silicon top layer, and the thickness of the silicon top layer may be 2 μm to 5 μm, etc., specifically 3 μm. In this embodiment, the substrate is selected as an SOI substrate, so that the substrate 100 is a silicon substrate, the insulating layer 101 is a silicon dioxide layer, and the semiconductor top layer 102 is an unintentionally doped intrinsic silicon layer.

[0090] like Figure 4 As shown, as a preferred example, the length direction of the groove 13 has an inclination angle θ with the optical signal propagation direction 21 in the waveguide 15; when the waveguide 15 is a straight waveguide, the inclination angle θ is 40° to 70°, for example, it can be 40°, 50°, 58°, 64°, 67°, or 70°. Figure 4 The waveguide 15 is a straight waveguide, so the light propagation direction 21 is consistent with the length direction of the waveguide 15. When the inclination angle θ is in the range of 40° to 70°, the best suppression effect of stray light can be achieved; when the waveguide is a curved waveguide, the inclination angle is 20° to 75°, for example, 20°, 40°, 58°, 64°, 70°, 75°. Figure 5 In the embodiment, when the waveguide 15 is an Euler bend waveguide (EB, a single-mode strip waveguide), the preferred value of the inclination angle θ of the inner bend groove 13 is 30° to 75°, and the preferred value of the inclination angle θ of the outer bend groove 13 is 20° to 50°. In different types of waveguide components, the optimal inclination angle θ of the groove 13 is different according to the high-order mode of the propagated optical signal and the propagation path of the stray light in the component.

[0091] The stray light control module of this embodiment can be applied near any location in the photonic integrated circuit where stray light may be generated. Figure 4The embodiment is directed to the reflective semiconductor optical amplifier (RSOA) in the laser cavity 19. RSOA is the main source of stray light 20. Although precise alignment can couple light into the straight waveguide 15, a large portion of the light is still trapped in the waveguide chip. By setting the stray light control module of this embodiment in the waveguide chip adjacent to the laser cavity 19, and setting the inclination angle θ between the length direction of the groove 13 in the stray light control module and the light propagation direction 21 in the waveguide 15 to 40° to 70°, the stray light 20 emitted by the RSOA can be effectively diffusely reflected in a direction away from the straight waveguide 15, preventing the reflected light from returning to the laser cavity 19 or continuing to propagate forward to form background light noise, thereby increasing the signal-to-noise ratio.

[0092] like Figure 5 The figure is about the application of the stray light control module of this embodiment in the Euler bend waveguide. By arranging the stray light control module of this embodiment around the EB and arranging the serrated side wall of the groove 13 on the side facing the incident direction of the stray light, any stray light 20 close to the EB will be quickly scattered out, thereby improving the signal-to-noise ratio of the EB transmitted light.

[0093] As a preferred example, the side wall of the groove 13 on the other opposite side of the side wall facing the incident direction of the stray light can also be set as the toothed side wall 130, that is, the long sides of both sides of the groove 13 are set as the toothed side wall 130, and the cross-section of each toothed side wall 130 includes a plurality of non-arc convex teeth 131 extending outwardly along the long side direction of the groove 13 and arranged at intervals, and a non-arc concave tooth 132 extending inwardly along the long side direction of the groove 13 is formed between two adjacent non-arc convex teeth 131. In addition, the depth of the non-arc tooth is consistent with the depth of the groove. In this way, the toothed side wall 130 of the groove 13 in the incident direction of the stray light can scatter most of the stray light, and the small part of the scattered light that is transmitted can be further diffusely reflected and scattered by the long side of the toothed side wall on the opposite side, so as to further suppress the stray light and improve the signal-to-noise ratio.

[0094] Generally, the incident direction of the stray light 20 is not fixed, and most of the stray light 20 is incident toward one side of the length direction of the groove 13, so the groove sidewall on this side is set as a toothed sidewall 130 to scatter most of the stray light 20. Furthermore, a small amount of stray light 20 may be incident toward one side of the width of the groove 13, such as the width side of the groove 13 close to the waveguide 15, so the groove sidewall on the width side may also be set as a toothed sidewall 130 to further achieve scattering of the stray light 20.

[0095] As another preferred example, Figure 1As shown, the stray light control module also includes a stray light absorption region 103 for absorbing stray light 20, the groove 13 is located in the middle area of ​​the stray light absorption region 103, and the waveguide 15 is formed between two adjacent stray light absorption regions 103. The stray light absorption region 103 can assist the metal reflective layer 17 in further improving the suppression of stray light by absorbing stray light. Since the metal reflective layer 17 suppresses stray light by scattering the stray light out of the substrate, the stray light absorbed by the stray light absorption region 103 can further improve the suppression of stray light and suppress the generation of local hot spots, thereby significantly reducing the system noise in the PIC. In one embodiment, the dopant of the stray light absorption region 103 includes one of boron, arsenic, boron difluoride, phosphorus and antimony, and the doping concentration of the stray light absorption region 103 is 1×10 18 / cm3~5×10 19 / cm3, the specific dopant and doping concentration may depend on the design requirements, such as the wavelength of light to be absorbed.

[0096] Specifically, Figure 6 and Fig. 9 As shown, the width x and length of the stray light absorption region 103 can be adjusted according to the width W1 and length of the groove. For example, for a groove with a width W1 of 5 μm to 30 μm, the width x of the stray light absorption region can be between 25 μm and 50 μm. It should be noted that since the sidewalls of the groove 13 are configured as toothed sidewalls, the width W1 of the groove here refers to the minimum width of the groove 13.

[0097] As an example, Figure 1 As shown, an adhesion barrier layer 16 is further provided under the surface of the metal reflective layer 17; and a metal passivation layer 18 is provided on the surface of the metal reflective layer 17. The adhesion barrier layer 16 can improve the adhesion of the metal reflective layer 17 and prevent the metal elements in the metal reflective layer 17 from diffusing into the semiconductor top layer 102. As a specific example, when the material of the semiconductor top layer 102 is silicon, the material of the adhesion barrier layer 16 is selected as silicon oxide. The metal passivation layer 18 can serve as a passivation protection layer of the metal reflective layer 17, and can also be formed on the surface of the waveguide 15 as a cladding of the waveguide 15. As a specific example, when the material of the semiconductor top layer 102 is silicon, the material of the metal passivation layer 18 is selected as silicon oxide.

[0098] like Figure 1 , Figure 2 and Fig.15 As shown, as another preferred example, the metal reflective layer 17 is further disposed on the semiconductor top layer 102 in the preset area connected to the groove 13. Figure 2 and Fig.15 The W3 region in the groove 13. The metal reflective layer 17 is arranged in the W3 region to further realize the specular reflection of the scattered light. When the groove width W1 is 5 μm to 30 μm, the width W3 of the preset region is 3 μm to 5 μm, the thickness of the metal reflective layer 17 located on the side wall of the groove 13 is 350 nm to 450 nm, and the thickness of the metal reflective layer 17 located on the semiconductor top layer 102 is 1 μm to 1.4 μm.

[0099] From the perspective of achieving the function of metal mirror reflection, the material of the metal reflective layer 17 is not overly limited. On this basis, considering the cost, the material of the metal reflective mirror 17 is preferably aluminum.

[0100] like Figure 3 As shown, as another preferred example, the non-arc convex teeth 131 and the non-arc concave teeth 132 on the toothed side wall 130 are arranged non-periodically, that is, the sizes of the non-arc convex teeth 131 and the non-arc concave teeth 132 on the toothed side wall 130 are randomly set, and the cross-sectional size of the non-arc teeth ranges from submicron to 5 microns, without a certain periodic arrangement rule. This non-periodic arrangement minimizes the dependence of the stray light suppression effect on the spectrum, so that the scattering effect of the stray light can be effectively exerted in a wider wavelength range, and the spatial coherence of the stray light can be better destroyed, that is, the wide spectrum applicability of the stray light control module of this embodiment is improved.

[0101] In this embodiment, the horizontal cross-sectional shape of the non-arc-shaped raised teeth 131 and the non-arc-shaped recessed teeth 132 on the toothed side wall 130 is required to be non-arc-shaped as a whole, that is, the contour thereof is a non-smooth contour, for example Figure 3 The horizontal cross-sectional shape of the non-arc convex teeth 131 and the non-arc concave teeth 132 is a triangle, or other non-smooth contour shapes, such as a rectangle or a polygon. The horizontal cross-sectional shape of the non-arc convex teeth 131 and the non-arc concave teeth 132 can be unified into a non-smooth contour shape, such as Figure 3 The triangles in the figure may be rectangles or other shapes, or a combination of two or more different non-smooth contour shapes, such as a combination of a triangle and a rectangle, that is, a part of the non-arc convex teeth 131 and the non-arc concave teeth 132 have a horizontal cross-sectional shape of a triangle, and another part of the non-arc convex teeth 131 and the non-arc concave teeth 132 have a horizontal cross-sectional shape of a rectangle, and the specific selection is made according to actual needs.

[0102] This embodiment also provides a photon integrated chip, which includes the stray light control module of the above embodiment. The photon integrated chip may also include other optical components, such as a light detector, an avalanche photodiode, an optical waveguide, an optical beam splitter, an optical input / output coupler, an optical resonator, etc. The photon integrated chip may also include other optical components, and is not limited to the examples listed here.

[0103] Embodiment 2

[0104] The present embodiment provides a method for preparing a stray light control module, and the preparation method can be used to prepare the stray light control module described in Example 1. The beneficial effects that can be achieved by the stray light control module prepared by the preparation method of the present embodiment can be found in Example 1, and will not be described in detail below. The present embodiment focuses on describing the preparation method and the beneficial effects that can be achieved.

[0105] The preparation method comprises the following steps:

[0106] S1, providing a substrate, wherein the substrate comprises a base, an insulating layer and a semiconductor top layer arranged in sequence;

[0107] S2, forming two grooves and a waveguide between the two grooves on the semiconductor top layer; wherein the groove extends from the surface of the semiconductor top layer to the bottom of the semiconductor top layer, and the side wall of the groove facing the incident direction of the stray light is set as a toothed side wall, and the cross section of the toothed side wall includes a plurality of non-arc-shaped raised teeth extending outward along the long side direction of the groove and arranged at intervals, and a non-arc-shaped recessed tooth extending inward along the long side direction of the groove is formed between two adjacent non-arc-shaped raised columns;

[0108] S3, forming a metal reflective layer at least on the sidewall and bottom of the trench.

[0109] The method for preparing the stray light control module of this embodiment is described in detail below with reference to the specific drawings.

[0110] like Figure 6 As shown, firstly, step S1 is performed to provide a substrate 10 , wherein the substrate 10 comprises a base 100 , an insulating layer 101 and a semiconductor top layer 102 which are arranged in sequence.

[0111] As an example, the substrate 100 may be a silicon substrate, a germanium substrate, a silicon germanium substrate, a silicon carbide substrate, etc.; the insulating layer 101 may be any suitable dielectric layer; the semiconductor top layer 102 may be a silicon top layer, and the thickness of the silicon top layer may be 2 μm to 5 μm, etc., specifically 3 μm. In this embodiment, the substrate 10 is selected as an SOI substrate, so that the substrate 100 is a silicon substrate, the insulating layer 101 is a silicon dioxide layer, and the semiconductor top layer 102 is an unintentionally doped intrinsic silicon layer.

[0112] As an example, after providing the substrate 10 and before performing the subsequent step S2, a stray light absorption region 103 may be formed in the semiconductor top layer 102. In the early stage of design, the design idea is to first determine the position of the groove, and then determine the position of the stray light absorption region 103 according to the position of the groove, wherein the stray light absorption region 103 is located at the periphery of the groove, and the groove is located at the central position area of ​​the stray light absorption region 103, and the extension directions of the two are consistent. In the actual process, the stray light absorption region 103 is prepared first, and then the groove is formed.

[0113] As a specific example, the method of forming the stray light absorption region 103 includes: Figure 7 As shown, first, a photoresist layer 12 is coated on the surface of the semiconductor top layer 102; Figure 8 As shown, then, the photoresist layer 12 is patterned by photolithography to obtain a patterned photoresist layer 120, wherein the patterned photoresist layer 120 exposes the surface of the stray light absorption region 103; Figure 8 As shown, then, an ion implantation process is performed based on the patterned photoresist layer 120, for example, dopants (such as boron, arsenic, boron difluoride, phosphorus and antimony, etc.) are implanted into the semiconductor top layer 102, and high-temperature annealing is performed to diffuse the dopants from the implantation area into the inside of the semiconductor top layer 102, so as to form the stray light absorption region 103 with the required ion doping concentration in the semiconductor top layer 102; Figure 6 As shown, finally, the remaining patterned photoresist layer 120 is removed. From the perspective of the absorption of stray light, the deeper the depth y of the stray light absorption region, the better, and the greater the doping concentration of the stray light absorption region 103, the better. However, from the perspective of process implementation, the depth y of the stray light absorption region and the doping concentration of the stray light absorption region are based on the actual process limit and the principle of not causing other deterioration effects. For example, the doping concentration of the stray light absorption region is 1×10 18 / cm3~5×10 19 / cm3.

[0114] like Figure 3 , Fig.13 and Fig.14 As shown, step S2 is then performed to form two grooves 13 and a waveguide 15 between the two grooves 13 in the semiconductor top layer 102; wherein the groove 13 extends from the surface of the semiconductor top layer 102 to the bottom of the semiconductor top layer 102 (such as Fig.13d2), the side wall of the groove 13 facing the incident direction of the stray light is set as a toothed side wall 130, and the surface of the toothed side wall 130 includes a plurality of non-arc-shaped raised teeth 131 extending outwardly in the horizontal direction of the groove 13 and arranged at intervals, and a non-arc-shaped recessed tooth 132 extending inwardly in the horizontal direction of the groove 12 is formed between two adjacent non-arc-shaped raised teeth 131 (such as Figure 3 shown).

[0115] As a preferred example, the side wall on the other opposite side of the side wall of the groove 13 facing the incident direction of stray light can also be set as the toothed side wall 130, that is, the long sides of both sides of the groove 13 are set as the toothed side wall 130, and the cross-section of each toothed side wall 130 includes a plurality of non-arc-shaped raised teeth 131 extending outwardly along the long side direction of the groove 13 and arranged at intervals, and a non-arc-shaped recessed tooth 132 extending inwardly along the long side direction of the groove 13 is formed between two adjacent non-arc-shaped raised teeth 131.

[0116] It should be noted here that the non-arc convex tooth 131 extends outward along the long side direction of the groove 13, and the non-arc concave tooth 132 extends inward along the long side direction of the groove 13, which refers to a two-dimensional plane perpendicular to the depth direction of the groove 13. Taking the groove 13 as a reference object, the non-arc convex tooth 131 is defined as extending away from the long side direction of the groove 13, and the non-arc concave tooth 132 is defined as extending toward the long side direction of the groove 13.

[0117] As a specific example, the method of forming the groove 13 and the waveguide 15 includes:

[0118] like Fig.10 and Fig.11 As shown, firstly, step S21 is performed to sequentially form a hard mask layer 11 and a photoresist layer 12 on the surface of the semiconductor top layer 102, and the photoresist layer 12 is patterned by photolithography to form a patterned photoresist layer 120. Preferably, the photoresist layer 12 can be patterned by photolithography using a high-resolution 248nmDUV photolithography technique. The hard mask layer 11 is used as a mask layer for subsequent etching of the semiconductor top layer 102, and its material selection has a high selective etching ratio with the semiconductor top layer 102. For example, when the material of the semiconductor top layer is silicon, the material of the hard mask layer 11 is preferably silicon oxide. In addition, any existing suitable deposition process, such as a PECVD process, can be used to form the hard mask layer 11. The thickness of the hard mask layer 11 is usually selected between 500nm and 700nm.

[0119] like Fig. 9 and Fig.11As shown, step S22 is then performed, wherein the hard mask layer 11 is etched based on the patterned photoresist layer 120 to obtain a patterned hard mask layer 110 and then the patterned photoresist layer 120 is removed; wherein the patterned hard mask layer 110 defines a groove region 111 and defines a waveguide region (such as Fig.11 shown), i.e. Fig.11 The area defined between the two waveguide outer regions 112 is the waveguide region. Fig. 9 and Fig.11 , the typical size range of the width W2 of the waveguide outer region is 0.2μm to 10μm, and the typical size range of the width W1 of the groove region is 5μm to 30μm. It should be noted here that the shape of the groove 13 formed subsequently is formed by transferring the patterned photoresist layer 120 to the patterned hard mask layer 110, and then transferring the patterned hard mask layer 110 to the top semiconductor layer 102, and the side wall of the groove 13 formed subsequently needs to be a toothed side wall, that is, the shape of the patterned hard mask layer 110 in the groove region 111 of this step is the same as the shape of the groove 13 formed subsequently, so the groove region width W1 here refers to the minimum width of the groove region width 111. The groove region 111 and the waveguide outer region 112 are formed by etching the hard mask layer 11 at the same time, avoiding any lithography alignment error caused by etching the groove region 111 and the waveguide outer region 112 separately, thereby forming a self-alignment effect, effectively improving the etching yield.

[0120] like Fig.12 and Fig.13 As shown, step S23 is then performed, in which the semiconductor top layer 102 is etched separately using a photolithography process based on an etching selectivity between the patterned hard mask layer 110 and the semiconductor top layer 102 to form the groove 13 and the waveguide 15 in the groove area 111 and the defined waveguide area, and the waveguide 15 has outer waveguide grooves 14 formed on both sides corresponding to the outer waveguide area 112.

[0121] The order of forming the groove 13 and the waveguide 15 is not limited here. The groove 13 may be formed first and then the waveguide 15, or the waveguide 15 may be formed first and then the groove 13. In a specific example, the formation process is described by taking the formation of the waveguide 15 first and then the groove 13 as an example: Fig.12As shown, firstly, a photoresist layer is coated on the surface of the obtained structure, and then the photoresist layer is patterned by photolithography to obtain a patterned photoresist layer 120, wherein the patterned photoresist layer 120 exposes the surface of the waveguide outer region 112 and the surface of the region where the waveguide 15 is located, and may further expose a portion of the patterned hard mask layer; then, based on the etching selectivity between the patterned hard mask layer 110 and the semiconductor top layer 102, the semiconductor top layer 102 is etched, for example, dry etching is selected to form a waveguide outer groove 14 with a preset depth d1 in the waveguide outer region 112, and the two waveguide outer grooves 14 define the waveguide 15, and the typical value of the preset depth d1 is 1.1μm to 1.3μm; then, the remaining patterned photoresist layer 120 is removed; as shown Fig.13 As shown, a photoresist layer is then coated on the surface of the obtained structure, and is patterned by photolithography to obtain a patterned photoresist layer 120, wherein the patterned photoresist layer 120 exposes the surface of the groove area 111, and may further expose a portion of the patterned hard mask layer; then, based on the etching selectivity between the patterned hard mask layer 110 and the semiconductor top layer 102, the semiconductor top layer 102 is etched, for example, dry etching is selected to form a groove 13 penetrating the semiconductor top layer 102 in the groove area 111, as shown in FIG. Fig.13 finally, removing the remaining patterned photoresist layer 120.

[0122] like Fig.14 As shown, step S24 is finally performed to remove the remaining patterned hard mask layer 110 to obtain the trench 13 and the waveguide 15 .

[0123] like Fig.17 and Fig.18 As shown, step S3 is finally performed to form a metal reflective layer 17 at least on the sidewall and the bottom of the trench 13 .

[0124] As a specific example, the method of forming the metal reflective layer 17 includes:

[0125] First, step S31 is performed to deposit a metal reflective material layer on the surface of the groove 13 and the surface of the semiconductor top layer 102. The metal reflective material layer can be formed by any existing suitable metal deposition process, such as a sputtering process, a PECVD process, etc. From the perspective of realizing the function of metal mirror reflection, the material of the metal reflective material layer is not overly limited. On this basis, considering the cost, the material of the metal reflective material layer is preferably an aluminum material.

[0126] like Fig.15As shown, step S32 is then performed to form a photoresist layer on the surface of the metal reflective material layer, and the photoresist layer is patterned by photolithography to form a patterned photoresist layer 120; the patterned photoresist layer 120 covers the surface of the area where the groove 13 is located and exposes the surface of other areas. Fig.15 As shown, the patterned photoresist layer 120 may also additionally cover the surface of the semiconductor top layer 102 in the predetermined area adjacent to the groove, such as Fig.15 The surface of the semiconductor top layer 102 in the area where W3 is located.

[0127] like Fig.15 As shown, step S33 is then performed, and the metal reflective material layer is etched based on the patterned photoresist layer 120 to obtain the metal reflective layer 17. The etching method of the metal reflective material layer is not limited, and wet etching or dry etching can be used. Preferably, wet etching is used, and the etching selectivity of wet etching is higher than that of dry etching, and the damage to the semiconductor top layer 102 is smaller, which can reduce the damage to the surface of the waveguide 15. When the patterned photoresist layer 120 not only covers the surface of the area where the groove 13 is located, but also additionally covers the surface of the semiconductor top layer 102 in the preset area W3 where the groove 13 is connected, the formed metal reflective layer 17 is not only formed on the sidewall and bottom of the groove 13, but also formed on the semiconductor top layer 102 in the preset area W3 where the groove 13 is connected.

[0128] Finally, step S33 is performed to remove the remaining patterned photoresist layer 120 to obtain the metal reflective layer 17. As a typical example, the thickness of the metal reflective layer 17 on the sidewall of the groove 13 is 350nm-450nm, and the thickness of the metal reflective layer 17 on the semiconductor top layer 102 is 1μm-1.4μm.

[0129] like Fig.16 As shown, as a preferred example, before forming the metal reflective material layer in step S31, an adhesion barrier layer 16 may be deposited on the surface of the groove 13 and the surface of the semiconductor top layer 102. The adhesion barrier layer 16 can improve the adhesion of the metal reflective material layer and prevent the metal elements in the metal reflective material layer from diffusing into the semiconductor top layer 102. When the material of the semiconductor top layer 102 is silicon, the material of the adhesion barrier layer 16 is silicon oxide.

[0130] like Fig.17As shown, as a specific example, after forming the metal reflective layer 17, a metal passivation layer 18 may be deposited on the surface of the metal reflective layer 17. The metal passivation layer 18 may serve as a passivation protection layer for the metal reflective layer 17. Furthermore, the metal passivation layer 18 may also be formed on the surface of the waveguide 15 as a cladding layer of the waveguide 15. When the material of the semiconductor top layer 102 is silicon, the material of the metal passivation layer 18 is silicon oxide. For example, the metal passivation layer 18 may be formed by a PECVD process. The typical value of the thickness of the metal passivation layer 18 is 500nm to 700nm.

[0131] From the above, it can be seen that the stray light control module prepared by the preparation method of the stray light control module of this embodiment is a groove structure, which is prepared by a multi-mask photonics process, is compatible with the traditional silicon photonic device manufacturing process, is easy to prepare and realize industrial production, and has good market value.

[0132] Therefore, the present invention effectively overcomes various shortcomings in the prior art and has high industrial utilization value.

[0133] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A stray light control module, characterized in that: The stray light control module comprises: A substrate, comprising a base, an insulating layer and a semiconductor top layer arranged in sequence; Two grooves are arranged in the semiconductor top layer at intervals, and the grooves extend from the surface of the semiconductor top layer to the bottom of the semiconductor top layer, and a waveguide is formed between two adjacent grooves; A metal reflective layer, at least disposed on the sidewall and bottom of the groove; Among them, the side wall of the groove facing the incident direction of stray light is set as a toothed side wall, and the cross-section of the toothed side wall includes a plurality of non-arc-shaped raised teeth extending outward along the long side direction of the groove and arranged at intervals, and a non-arc-shaped recessed tooth extending inward along the long side direction of the groove is formed between two adjacent non-arc-shaped raised teeth.

2. The stray light control module according to claim 1, characterized in that: The waveguide is a straight waveguide or a curved waveguide.

3. The stray light control module according to claim 2, characterized in that: The length direction of the groove has an inclination angle with the light propagation direction in the waveguide; when the waveguide is a straight waveguide, the inclination angle is 40° to 70°; when the waveguide is a curved waveguide, the inclination angle is 20° to 75°.

4. The stray light control module according to claim 1, characterized in that: The stray light control module further includes a stray light absorption region for absorbing stray light, the groove is located in a middle area of ​​the stray light absorption region, and the waveguide is formed between two adjacent stray light absorption regions.

5. The stray light control module according to claim 4, characterized in that: The width of the groove is 5 μm to 30 μm, and the width of the stray light absorption region is 25 μm to 50 μm.

6. The stray light control module according to claim 4, characterized in that: The dopant of the stray light absorption region includes one of boron, arsenic, boron difluoride, phosphorus and antimony, and the doping concentration of the stray light absorption region is 1×10 18 / cm3~5×10 19 / cm3.

7. The stray light control module according to claim 1, characterized in that: An adhesion barrier layer is also arranged under the surface of the metal reflective layer; and a metal passivation layer is arranged on the surface of the metal reflective layer.

8. The stray light control module according to claim 1 or 7, characterized in that: The metal reflective layer is also arranged on the semiconductor top layer in a preset area connected to the groove.

9. The stray light control module according to claim 8, characterized in that: The material of the metal reflective layer includes aluminum; the thickness of the metal reflective layer located on the side wall of the groove is 350nm-450nm, the thickness of the metal reflective layer located on the top layer of the semiconductor is 1μm-1.4μm, and the width of the preset area is 3μm-5μm.

10. The stray light control module according to claim 1, characterized in that: The non-arc-shaped raised teeth and the non-arc-shaped recessed teeth on the toothed side wall are arranged in a non-periodic manner.

11. The stray light control module according to claim 1, characterized in that: The horizontal cross-sectional shape of the non-arc convex teeth and the non-arc concave teeth on the toothed side wall is a triangle, a rectangle or a polygon.

12. The stray light control module according to claim 1, characterized in that: The side wall of the groove on the other side opposite to the side wall facing the incident direction of the stray light is also configured as the toothed side wall.

13. A photonic integrated chip, characterized in that: The photonic integrated chip comprises the stray light control module as claimed in any one of claims 1 to 12.

14. A method for preparing a stray light control module, characterized in that: The preparation method comprises the following steps: Providing a substrate, the substrate comprising a base, an insulating layer and a semiconductor top layer arranged in sequence; Two grooves and a waveguide between the two grooves are formed on the semiconductor top layer; wherein the groove extends from the surface of the semiconductor top layer to the bottom of the semiconductor top layer, and the side wall of the groove facing the incident direction of stray light is set as a toothed side wall, and the cross section of the toothed side wall includes a plurality of non-arc-shaped raised teeth extending outwardly along the long side direction of the groove and arranged at intervals, and a non-arc-shaped recessed tooth extending inwardly along the long side direction of the groove is formed between two adjacent non-arc-shaped raised teeth; A metal reflective layer is formed at least on the sidewall and the bottom of the trench.

15. The method for preparing the stray light control module according to claim 14, characterized in that: Before forming the groove and the waveguide, the method further includes forming a stray light absorption region in the semiconductor top layer; wherein the groove is located in the middle area of ​​the stray light absorption region, and the waveguide is formed between two adjacent stray light absorption regions.

16. The method for preparing the stray light control module according to claim 14, characterized in that: The method of forming the groove and the waveguide comprises: Forming a hard mask layer and a photoresist layer in sequence on the surface of the semiconductor top layer, and performing photolithography patterning on the photoresist layer to form a patterned photoresist layer; Etching the hard mask layer based on the patterned photoresist layer to obtain a patterned hard mask layer and then removing the patterned photoresist layer; wherein the patterned hard mask layer defines a groove area and limits a waveguide area; Using a photolithography process and based on an etching selectivity ratio between the patterned hard mask layer and the semiconductor top layer, the semiconductor top layer is respectively etched to form the groove and the waveguide in the groove region and the defined waveguide region; The remaining patterned hard mask layer is removed.

17. The method for preparing the stray light control module according to claim 16, characterized in that: The material of the semiconductor top layer includes silicon; the material of the hard mask layer includes silicon oxide.

18. The method for preparing the stray light control module according to claim 14, characterized in that: The metal reflective layer is also disposed on the semiconductor top layer in the preset area where two grooves are connected, and the method for forming the metal reflective layer includes: Depositing a metal reflective material layer on the surface of the groove and the surface of the semiconductor top layer; forming a photoresist layer on the surface of the metal reflective material layer, and performing photolithography patterning on the photoresist layer to form a patterned photoresist layer; Wet etching the metal reflective material layer based on the patterned photoresist layer to obtain the metal reflective layer; The remaining patterned photoresist layer is removed.

19. The method for preparing the stray light control module according to claim 18, characterized in that: Before forming the metal reflective material layer, a step of depositing an adhesion barrier layer on the surface of the groove and the surface of the semiconductor top layer is included; after forming the metal reflective layer, a step of depositing a metal passivation layer on the surface of the metal reflective layer is included.

20. The method for preparing the stray light control module according to claim 19, characterized in that: The metal passivation layer is also formed on the surface of the waveguide, serving as a cladding layer of the waveguide.

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