Optical chip and preparation method of optical chip

Abstract

The invention discloses an optical chip and a preparation method of the optical chip. The optical chip comprises a substrate and an optical device structure layer which is located above the substrate and formed based on a top silicon layer in an SOI substrate. The optical device structure layer formed on the basis of a top silicon layer in the SOI substrate sequentially comprises a protective layer, a reflecting layer, a first spacing layer and an optical device layer from bottom to top, wherein the protective layer is positioned above the substrate and is fixedly connected with the substrate; the reflecting layer is located above the protective layer, the reflecting layer comprises a reflecting structure, and the reflecting structure is used for reflecting the detection light beams emitted from the optical device layer upwards; the first spacing layer is positioned above the reflecting layer, covers the reflecting layer and is used for spacing the reflecting layer and the optical device layer; the optical device layer is located above the first spacing layer, comprises at least one optical device and is used for emitting a detection light beam; wherein the substrate and the protection layer are fixedly connected after an optical device structure layer is formed on the basis of a top silicon layer in the SOI substrate.

Description

Technical Field

[0001] This application belongs to the technical field of lidar. Specifically, it relates to an optical chip and a method for manufacturing the optical chip. Background Art

[0002] For existing silicon optical chips, SOI is usually used as the substrate, and integrated optical devices are processed on the top layer of silicon. After completion, a silicon dioxide layer is grown on the top to protect the optical devices. Grating couplers or optical antennas in the integrated optical devices need to emit light into space, or spatial light needs to be coupled into the optical chip. To improve the emission efficiency or coupling efficiency, the light emitted by the grating coupler or optical antenna can be reflected by adding a reflection structure, so that the emitted light of the optical antenna can only be emitted from one side, increasing the emission power, improving the emission efficiency of the optical antenna, reducing light loss, and improving the utilization efficiency of the input light.

[0003] There are usually three existing methods. The first is to grow a reflection structure under the integrated optical device first, and then fabricate the integrated optical device above it. The second is also to fabricate a reflection structure under the integrated optical device, but a specific area at the bottom of the SOI substrate is partially hollowed out until the silicon dioxide layer, and then the reflection structure is fabricated. The third is to fabricate a reflection structure on the top of the integrated optical device to make all the light emit downward. All these three methods can also achieve the improvement of the emission efficiency. However, the first two schemes have high manufacturing difficulty, bringing difficulties to production and manufacturing, reducing the product yield, and increasing the cost. The last scheme has low manufacturing difficulty, but all the emitted light emits downward, passing through the thick substrate silicon (about 720μm), resulting in additional light loss, and the uniformity or internal defects of the substrate silicon inevitably exist, all of which will more or less affect the spot quality of the emitted light. Summary of the Invention

[0004] The embodiments of this application provide an optical chip and a method for manufacturing the optical chip to solve the problem of large light loss in the prior art and reduce the difficulty of the manufacturing process at the same time.

[0005] According to one aspect of the embodiments of the present application, an optical chip is provided, including: a substrate, and an optical device structure layer formed on the top silicon layer in the SOI substrate above the substrate; wherein, the optical device structure layer formed on the top silicon layer in the SOI substrate includes, from bottom to top in sequence, a protective layer, a reflective layer, a first spacer layer, and an optical device layer; wherein, the protective layer is located above the substrate and fixedly connected to the substrate; the reflective layer is located above the protective layer, and the reflective layer includes a reflective structure for reflecting the detection beam emitted from the optical device layer upward; the first spacer layer is located above the reflective layer and covers the reflective layer for spacing apart the reflective layer and the optical device layer; the optical device layer is located above the first spacer layer and includes at least one optical device for emitting the detection beam; wherein, the substrate and the protective layer are fixedly connected after the optical device structure layer is formed on the top silicon layer in the SOI substrate.

[0006] As an optional solution, the optical device structure layer further includes: an optical correction structure located between the protective layer and the reflective layer for changing the refractive index of the optical antenna in the optical device layer; and a second spacer layer disposed between the optical correction structure and the reflective layer for spacing apart the optical correction structure and the reflective layer.

[0007] As an optional solution, the optical device layer includes: a first device layer formed in the top silicon layer of the SOI substrate, wherein the first device layer includes a first coupler, a first beam splitter, a first phase shifter, and a first optical antenna; or a first device layer, a second device layer, and a third spacer layer disposed between the first device layer and the second device layer, wherein the first device layer is formed in the top silicon layer of the SOI substrate, the first device layer includes a first coupler, a first beam splitter, a first phase shifter, and a first optical antenna, the second device layer is formed in a silicon nitride material layer above the third spacer layer, and the second device layer includes a second coupler, a second beam splitter, a second phase shifter, and a second optical antenna; when the optical devices in the first device layer are combined with the optical devices in the second device layer, at least part of a third interlayer coupler, a third beam splitter, a third phase shifter, and a third optical antenna is formed.

[0008] As an optional solution, the projection of the reflective layer in the vertical direction partially overlaps or completely overlaps with the projection in the vertical direction of any one or more of the first optical antenna, the second optical antenna, and the third optical antenna.

[0009] As an alternative, after the optical device structure layer is formed on the top silicon layer in the SOI substrate, the substrate and the protective layer are fixedly connected by bonding; or, after the optical device structure layer is formed on the top silicon layer in the SOI substrate, the substrate and the protective layer are fixedly connected by using an adhesive.

[0010] As an alternative, the thermal conductivity of the adhesive is less than 10 W / (m·K), and the thickness of the adhesive layer and the sum of its thickness and the thickness of the silicon dioxide material layer are greater than 3 μm; wherein, both the protective layer and the first spacer layer are made of silicon dioxide material.

[0011] As an alternative, the substrate is made of silicon, glass, diamond or an SOI substrate.

[0012] As an alternative, the optical chip further includes a window located above the optical device structure layer, and the window is made of a transparent material with a thermal conductivity less than 100 W / (m·K).

[0013] As an alternative, the window is a single-layer material structure or a laminated structure including multiple material layers

[0014] As an alternative, the preparation materials of the window include one or more of silicon dioxide, quartz, and ordinary glass.

[0015] As an alternative, the reflection structure is a metal reflection structure, a dielectric film or a reflection grating.

[0016] According to another aspect of the embodiments of the present application, there is also provided a method for manufacturing an optical chip, including: providing an SOI substrate; forming an optical device layer in the top silicon layer of the SOI substrate, wherein the optical device layer includes at least one optical device, and the optical device layer is used for emitting a detection beam; forming a first spacer layer on the SOI substrate on which the optical device layer is formed, wherein the first spacer layer covers the optical device layer; forming a reflection layer on the first spacer layer, wherein the reflection layer includes a reflection structure, and the reflection structure is used for reflecting the detection beam emitted from the optical device layer toward the light-emitting side, and the light-emitting side is the side of the optical device layer facing away from the first spacer layer; forming a protective layer on the SOI substrate on which the reflection layer is formed, wherein the protective layer covers the reflection layer, and the optical device layer, the first spacer layer, the reflection layer and the protective layer are sequentially stacked to form an optical device structure layer; providing a substrate, fixing the substrate to the protective layer, and removing part or all of the substrate silicon in the SOI substrate.

[0017] As an alternative, fixing the substrate to the protective layer includes: bonding the substrate to the protective layer; or, adhering the substrate to the protective layer by an adhesive.

[0018] As an alternative, the adhesive has a thermal conductivity less than 10 W / (m·K), and the thickness of the adhesive layer and the sum of its thickness and the thickness of the silicon dioxide material layer are greater than 3 μm; wherein, both the protective layer and the first spacer layer are made of silicon dioxide material.

[0019] As an alternative, when the optical device structure layer further includes an optical correction structure, the method further includes: forming a second spacer layer on the SOI substrate having the reflective layer formed thereon before forming the protective layer, the second spacer layer covering the reflective layer; forming an optical correction structure on the second spacer layer, wherein the optical correction structure is configured to change the refractive index of the optical antenna in the optical device layer.

[0020] As an alternative, forming the optical device layer in the top silicon layer of the SOI substrate includes: forming a first device layer in the top silicon layer of the SOI substrate by a patterning process, wherein the first device layer includes a first coupler, a first beam splitter, a first phase shifter, and a first optical antenna; or, forming a first device layer in the top silicon layer of the SOI substrate by a patterning process, wherein the first device layer includes a first coupler, a first beam splitter, a first phase shifter, and a first optical antenna; depositing silicon dioxide on the SOI substrate having the first device layer formed thereon to form a third spacer layer, wherein the third spacer layer covers the first device layer; forming a silicon nitride material layer on the third spacer layer, and then patterning the silicon nitride material layer to form a second device layer, wherein the second device layer includes a second coupler, a second beam splitter, a second phase shifter, and a second optical antenna; wherein, when the optical devices in the first device layer are combined with the optical devices in the second device layer, at least part of a third interlayer coupler, a third beam splitter, a third phase shifter, and a third optical antenna are formed.

[0021] As an alternative, the manufacturing method further includes: forming a window on top of the optical device layer using a transparent material having a thermal conductivity less than 100 W / (m·K).

[0022] In the embodiments of the present application, for an optical chip, it includes a substrate and an optical device structure layer located above the substrate. The optical device structure layer is formed based on the top silicon layer in an SOI substrate. From bottom to top, the optical device structure layer sequentially includes a protective layer, a reflective layer, a first spacer layer, and an optical device layer. Through the reflective structure in the reflective layer, the detection beam emitted from the optical device layer in the optical chip will be reflected by the reflective structure and can only be emitted from one side (the side opposite to the reflective layer), thereby reducing optical loss, improving the emission power of the optical antenna, ensuring the detection performance of the lidar, and avoiding additional loss caused by light passing through the SOI substrate and spot distortion caused by defects existing inside the substrate. In addition, the optical chip sequentially includes from bottom to top: a substrate, a protective layer, a reflective layer, a first spacer layer, and an optical device layer. Among them, the reflective layer is fabricated on the top of the SOI integrated with the optical device structure layer. The overall process is simple, the integration degree of the optical device is high, the structure is compact, which is conducive to mass production, and can greatly reduce the cost of the product. Description of the Drawings

[0023] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The schematic embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation to the present application. In the drawings:

[0024] Figure 1 It is a schematic diagram of an optional optical chip according to an embodiment of the present application;

[0025] Figure 2 It is a schematic diagram of the emitted light rays of an optional optical chip according to an embodiment of the present application;

[0026] Figure 3 It is a schematic diagram of another optional optical chip according to an embodiment of the present application;

[0027] Figure 4 It is a schematic diagram of an optional optical device layer according to an embodiment of the present application;

[0028] Figure 5 It is a schematic diagram of another optional optical device layer according to an embodiment of the present application;

[0029] Figure 6 It is a schematic diagram of yet another optional optical chip according to an embodiment of the present application;

[0030] Figure 7 It is a schematic diagram of yet another optional optical chip according to an embodiment of the present application;

[0031] Figure 8 It is a schematic flowchart of a preparation method of an optional optical chip according to an embodiment of the present application;

[0032] Figure 9Schematic diagram of an optional method for fabricating an optical chip according to an embodiment of the present application;

[0033] Figure 10 Schematic diagram of another optional method for fabricating an optical chip according to an embodiment of the present application;

[0034] Figure 11 Schematic diagram of yet another optional method for fabricating an optical chip according to an embodiment of the present application;

[0035] Figure 12 Schematic diagram of yet another optional method for fabricating an optical chip according to an embodiment of the present application;

[0036] Figure 13 Schematic diagram of yet another optional method for fabricating an optical chip according to an embodiment of the present application;

[0037] Figure 14 Schematic diagram of yet another optional method for fabricating an optical chip according to an embodiment of the present application. Detailed implementation manners

[0038] The embodiments of the present application will be described in detail below. Examples of the embodiments are shown in the accompanying drawings, where the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to explain the present application, and should not be construed as limiting the present application.

[0039] In the description of the present application, it should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as limiting the present application.

[0040] In addition, the terms "first" and "second" are only used for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present application, "a plurality" means two or more unless otherwise specifically defined.

[0041] In this application, unless otherwise clearly specified and defined, terms such as "installed", "connected", "linked", "fixed", etc. shall be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0042] In order to make the purpose, technical solutions and advantages of this application clearer, the following further elaborates on this application in conjunction with the drawings and embodiments.

[0043] According to one aspect of the embodiments of this application, an optical chip is provided. An optical chip is an integrated circuit that uses optical technology to process and transmit information. It uses photons to transmit data and can achieve high-speed, high-bandwidth, and low-power consumption data transmission and processing. As a type of optical chip, a silicon photonics chip is an optical chip made of silicon material and can be used in fields such as optical communication, optical sensing, and lidar. A silicon photonics chip can convert optical signals into electrical signals or electrical signals into optical signals and has excellent optoelectronic performance.

[0044] The silicon photonics chip includes a substrate and a functional layer. Among them, the substrate is the basic part of the silicon photonics chip, usually made of silicon material, and plays a role of support and carrier during the manufacturing process of the silicon photonics chip; the functional layer of the silicon photonics chip is the pattern and structure formed based on the silicon-based material layer and CMOS (Complementary Metal Oxide Semiconductor) process. These patterns and structures can include optical devices such as couplers, beam splitters, phase shifters, and optical antennas, as well as electrodes connected to each optical device, etc., which form the functional part of the chip.

[0045] Currently, silicon photonics chips usually use SOI as the substrate, and integrated optical devices are processed and fabricated on the top silicon layer. After completion, a silicon dioxide layer is grown on the top to protect the optical devices. However, the substrate silicon in the SOI substrate is usually silicon with a thickness of about 700 μm. Even though it can be thinned to about 400 μm through grinding and polishing processes, it still differs by two to three orders of magnitude compared to the 220 nm thick top silicon layer and the 2 μm or 3 μm thick silicon dioxide layer in the SOI substrate.

[0046] The above optical chip can be applied to a lidar to implement the detection function of the lidar. When applying the optical chip to the detection process, the emitted light of the optical antenna in the optical device layer of the optical chip needs to pass through a very thick SOI substrate before being emitted, which increases additional optical losses, reduces the emission power of the optical antenna, and thus affects the detection performance of the lidar. In addition, the defects existing inside the substrate silicon may also affect the spot quality of the emitted light.

[0047] To at least partially solve the above technical problems, in this embodiment, for the optical chip, a reflective layer is provided between the substrate and the optical device layer. Through the reflection structure in the reflective layer, the detection beam emitted from the optical device layer of the optical chip will be reflected by the reflection structure and can only be emitted from one side (the side opposite to the reflective layer), thereby reducing optical losses, increasing the emission power of the optical antenna, ensuring the detection performance of the lidar, and at the same time avoiding the additional losses caused by light passing through the SOI substrate and the spot distortion caused by the defects existing inside the substrate silicon.

[0048] As an optional implementation manner, Figure 1 is a schematic diagram of an optional optical chip according to an embodiment of the present application. As Figure 1 shown, the optical chip may include: a substrate 11 and an optical device structure layer 12.

[0049] The substrate 11 can be the bottom structure of the optical chip, which can provide support for other components in the optical chip except the substrate 11 and can play a certain isolation role to ensure the operation safety of other components. The material of the substrate 11 can be selected according to needs, and its material can be but not limited to one of the following: silicon, glass, diamond, SOI substrate.

[0050] The optical device structure layer 12 can be located above the substrate 11 and can be formed based on the top silicon layer in the SOI substrate. Here, the SOI substrate can include a top silicon layer, a buried oxide layer (i.e., a silicon dioxide buried layer), and a substrate silicon layer. The optical device structure layer 12 can be formed on the top silicon layer of the SOI substrate. The detection beam emitted through the optical device structure layer 12 can be emitted upward into the detection space, as Figure 2 shown ( Figure 2 the upward arrow in it is used to represent the direction of the emitted light). It can be understood that the beam being emitted upward means that the beam is emitted along the direction from the substrate to the optical device structure layer. Figure 2 In the optical chip shown, the substrate is at the bottom and the optical device structure layer is at the top. Therefore, the beam being emitted upward means that the beam is emitted along the direction from the substrate to the optical device structure layer.

[0051] It should be noted that the term "substrate" can refer to the substrate of a diced wafer or the substrate of an undiced wafer. The term "layer" includes thin films and should not be construed as indicating a vertical or horizontal thickness unless otherwise specified. SOI substrates are readily available and have good characteristics for integrated photonic devices.

[0052] The substrate silicon layer of the SOI substrate is made of silicon material. The thermal conductivity of silicon is about 150 W / (m·K), which is a material with good heat conduction. If there are optical devices with local heat generation in the optical chip, the heat will be quickly conducted through the thick substrate silicon to the entire optical chip, resulting in serious thermal crosstalk.

[0053] In related technologies, a TEC (Thermo Electric Cooler) can be added at the bottom of the optical chip as a heat dissipation device to quickly dissipate the heat generated in the optical chip and reduce the internal heat accumulation. However, although the above solution can partially solve the problem of thermal crosstalk, if a better effect is desired, the electrical power consumption of the TEC needs to be increased to the watt level, and in this case, the TEC will generate more heat, which is also unacceptable for the optical chip.

[0054] In response to this, at least part of the substrate silicon layer can be removed, and a material with a low thermal conductivity substrate can be used as the base layer. Without introducing additional electrical power consumption, the heat conducted from the substrate to the entire optical chip can be reduced, thereby effectively preventing the problem of thermal crosstalk. In this case, the substrate can be a thermal isolation substrate. The thermal isolation substrate can specifically be a single-layer material structure or a laminated structure including multiple material layers, and the thermal isolation substrate includes at least one material layer formed of a material with a thermal conductivity less than 100 W / (m·K) (for example, quartz, glass, etc., but not limited to this). Compared with the thermal conductivity of silicon of about 150 W / (m·K), this material layer has a better thermal isolation effect and can effectively reduce the heat conducted through the substrate to the entire optical chip, effectively preventing thermal crosstalk.

[0055] Due to factors such as the different structures of the thermal isolation substrate and the materials used in the material layers, the thickness of the thermal isolation substrate is not fixed. Although the thermal isolation substrate uses materials with a low thermal conductivity, its thermal isolation ability is not only related to the thermal conductivity of the material but also related to the thickness of the thermal isolation substrate (the thermal conductivity of the thermal isolation substrate and the thickness of the thermal isolation substrate can be negatively correlated). To improve the thermal resistance ability of the thermal isolation substrate, the thickness of the thermal isolation substrate can be greater than 100 μm. At the same time, setting the thickness of the thermal isolation substrate to be greater than 100 μm can also take into account the mechanical stress requirements and improve the mechanical strength of the thermal isolation substrate.

[0056] Optionally, for the thermal isolation substrate of the stacked structure, the thickness of the material layer formed of a material with a thermal conductivity less than 100 W / (m·K) can be controlled to be greater than or equal to 10 μm to improve the thermal isolation effect of the thermal isolation substrate. When combined with the design that the thickness of the thermal isolation substrate is greater than 100 μm, the support ability and thermal resistance ability of the thermal isolation substrate can be ensured simultaneously. The materials of the single-layer material structure or each material layer in the stacked structure forming the thermal isolation substrate can include one or more of silicon dioxide, quartz, glass, low-density silicon, and plastic.

[0057] Among them, the thermal conductivity of silicon dioxide is about 1.4 W / (m·K), the thermal conductivity of quartz is about 7 W / (m·K), the thermal conductivity of low-density silicon can be controlled to be less than 100 W / (m·K), and the thermal conductivity of plastic is generally in the range of 0.1 - 0.5 W / (m·K). The material used for the material layer formed of a material with a thermal conductivity less than 100 W / (m·K) can be one of silicon dioxide, quartz, glass, low-density silicon (e.g., amorphous silicon), and plastic, but is not limited thereto, and can also be other materials with a thermal conductivity less than 100 W / (m·K). Optionally, the isolation substrate can use a glass substrate (which can be silicon dioxide glass or quartz glass) because the glass substrate not only has a low thermal conductivity but is also easier to obtain and has a lower cost.

[0058] The optical device structure layer 12 can be obtained in the following way: during the preparation of the optical chip, first form the optical device structure layer 12 on the top silicon layer in the SOI substrate, and then remove all or part of the substrate silicon layer in the SOI substrate. It can also be obtained by other means as long as the optical device structure layer 12 formed based on the top silicon layer in the SOI substrate can be obtained.

[0059] The optical device structure layer 12 includes, from bottom to top (in the direction from close to the substrate to far from the substrate): a protective layer 121, a reflective layer 122, a first spacer layer 123, and an optical device layer 124. The following will explain each part of the optical device structure layer 12 separately.

[0060] The protective layer 121 is located above the substrate 11 and is fixedly connected to the substrate 11 to play a role of fixing and protecting, improving the structural stability of the optical chip. The substrate 11 and the protective layer 121 are fixedly connected after the optical device structure layer is formed based on the top silicon layer in the SOI substrate. The material of the protective layer 121 can be silicon dioxide (SiO2).

[0061] The reflective layer 122 is located above the protective layer 121 and may include a reflective structure for reflecting upward the detection beam emitted from the optical device layer 124 (which may be the detection beam emitted by the optical antenna in the optical device layer 124, i.e., the emitted light). The detection beam reflected by the reflective structure is emitted upward into the detection space, which can improve the emission efficiency of the optical antenna, reduce light loss, and improve the utilization efficiency of the input light.

[0062] It can be understood that the optical antenna emits beams upward and downward, and only the upward beam can be used for target detection, while the beams in other directions will be wasted and even become noise, affecting the detection accuracy. In this embodiment, a reflective layer is added to the optical device structure layer to reflect the detection beam emitted from the optical device layer upward, so that the reflected light is emitted upward into the detection space, which can improve the emission efficiency of the optical antenna, reduce light loss, improve the utilization efficiency of the input light, and at the same time avoid the additional loss caused by light passing through the SOI substrate and the spot distortion caused by the defects existing in the substrate.

[0063] It should be noted that the reflective layer can be a laminated structure, one of which is the reflective structure, and the other structures can be structures with other functions, that is, at least part of the structure in the reflective layer can be capable of light reflection, rather than necessarily the entire reflective layer. Optionally, the reflective structure can be a metal reflective structure, a dielectric film or a reflective grating, which can be formed by depositing metal (forming a metal material layer, which can be the first metal material layer), evaporating a dielectric film or fabricating a reflective grating.

[0064] The first spacer layer 123 is located above the reflective layer 122 and can be used to separate the reflective layer 122 and the optical device layer 124. The first spacer layer 123 can cover the reflective layer 122 and can be formed of silicon dioxide material. The thickness of the first spacer layer 123 can be several tens of nanometers (e.g., 50 nm) to hundreds of nanometers (e.g., 100 nm) and other thicknesses that meet the device spacing requirements. The light transmittance of the first spacer layer 123 can be the light transmittance that meets the requirement for the beam to pass through or high transmittance therein (the light transmittance of the spacer layer meets the light transmittance requirement of the emitted beam).

[0065] The optical device layer 124 is located above the first spacer layer 123 and includes at least one optical device for emitting a detection beam. The optical devices included in the optical device layer 124 can be one or more, and can include an optical antenna, and can also include other optical devices, such as all or part of a light source, a coupler, a beam splitter, and a phase shifter. Here, through the above design of the optical chip, the overall process of the optical chip is simple, the integration degree of the optical devices is high, the structure is compact, which is conducive to mass production, and can greatly reduce the cost of the product.

[0066] It should be noted that a protective layer (formed of, for example, silicon dioxide) is usually covered above the optical device to prevent the optical device layer from being directly exposed to the air. At the same time, after the optical device is formed, corresponding metal wiring is also carried out. After the metal wiring, by adding a protective layer, the metal wires can be prevented from oxidizing or being damaged due to contact with the air. The thickness of the protective layer is usually 1 to 2 μm, or 3 μm, as long as it can play a protective role. In short, the protective layer can protect both the optical device and the metal device. While achieving electrical isolation, it prevents the optical device from being directly exposed to the air, and can also prevent the optical device from being soiled and avoid being damaged by humans. The light transmittance of the protective layer is the light transmittance that meets the requirement for the light beam to pass through or have high transmittance therein (that is, the light transmittance of the protective layer meets the light transmittance requirement of the emitted light beam).

[0067] Through the embodiments provided in the present application, the optical chip includes: a substrate, and an optical device structure layer formed based on the top silicon layer in the SOI substrate above the substrate; wherein, the optical device structure layer formed based on the top silicon layer in the SOI substrate includes, from bottom to top, a protective layer, a reflective layer, a first spacer layer, and an optical device layer; wherein, the protective layer is located above the substrate and fixedly connected to the substrate; the reflective layer is located above the protective layer, and the reflective layer includes a reflective structure for reflecting the detection light beam emitted from the optical device layer upward; the first spacer layer is located above the reflective layer and covers the reflective layer, and is used to space apart the reflective layer and the optical device layer; the optical device layer is located above the first spacer layer and includes at least one optical device for emitting a detection light beam; wherein, the substrate and the protective layer are fixedly connected after the optical device structure layer is formed based on the top silicon layer in the SOI substrate, which solves the problem in the related art that the optical chip has a low emission power of the optical antenna due to large optical loss of the light emitted by the optical antenna, reduces the optical loss, improves the emission power and emission efficiency of the optical antenna, and can also improve the utilization efficiency of the input light.

[0068] As an alternative solution, in order to improve the detection ability of the optical antenna, an optical correction structure can be provided in the optical device structure layer. As Figure 3 shown, the optical device structure layer 12 further includes:

[0069] An optical correction structure 125, located between the protective layer 121 and the reflective layer 122, for changing the refractive index of the optical antenna in the optical device layer 124.

[0070] The optical device layer 124 may include one or more device layers, and each device layer may include optical antennas. The above-mentioned optical correction structure 125 may be used to change the refractive index of any one or more optical antennas in the optical device layer 124. The way to change the refractive index of the optical antenna may be to heat the optical antenna (which may be all or part of the optical antennas), and the way to heat the optical antenna can be flexibly configured according to requirements, so as to adjust the refractive index of the optical antenna according to different requirements, achieve spot alignment, and thus improve the accuracy of target detection.

[0071] Optionally, the optical correction structure 125 may include a heating electrode and a heating structure (for example, a heating resistor). By applying a bias voltage to the heating electrode, the heating structure generates heat and conducts it to the optical antenna, thereby realizing the heating of the optical antenna, changing the refractive index of the optical antenna, and further changing the outgoing light direction corresponding to the optical antenna to achieve spot alignment.

[0072] The optical correction structure 125 may include multiple groups of heating structures, and each group of heating structures can be independently controlled for heating to achieve precise control of the optical antennas that need to be heated, compensate for the inconsistencies within the aperture of the optical antennas caused by the process, and thus improve the spot quality of the outgoing light beam. The heating structures are uniformly distributed above the corresponding optical antennas, and the specific quantity can be set according to needs, and this is not limited in this embodiment.

[0073] For example, as Figure 4 shown, the optical correction structure 125 may include multiple groups of heating structures to heat the optical antennas as needed.

[0074] Optionally, when the optical correction structure 125 includes multiple groups of heating structures, the heating parameters (such as the applied bias voltage, heating time, etc.) of different groups of heating structures among the multiple groups of heating structures may be the same or different. Different groups of heating structures can be used to heat different local parts of the optical antenna. The optical antenna can be divided into an antenna matrix (including a group of local antennas), and a local antenna into which the optical antenna is divided can be heated by a group of heating structures, or there may be no corresponding heating structure. The heating parameters of the heating structures corresponding to different local antennas of the optical antenna may be the same or different.

[0075] Optionally, as Figure 3As shown, in addition to the optical correction structure 125, the optical device structure layer 12 may further include: a second spacer layer 126. The second spacer layer 126 is disposed between the optical correction structure 125 and the reflective layer 122 for spacing apart the optical correction structure 125 and the reflective layer 122. The material and thickness of the second spacer layer 126 may be the same as or similar to those of the first spacer layer 123, which will not be elaborated here. Generally, silicon dioxide material is used to prepare the spacer layer and the protective layer. Here, the second spacer layer 126 can space apart the reflective layer 122 and the optical correction structure 125, preventing damage to the optical correction structure 125 during the formation of the reflective layer and reducing the manufacturing difficulty of the optical chip.

[0076] As an alternative solution, as Figure 5 shown, the optical device layer 124 further includes:

[0077] a first device layer 1241 formed in the top silicon layer of the SOI substrate, where the first device layer 1241 includes a first coupler, a first beam splitter, a first phase shifter, and a first optical antenna. The positional relationship of each optical device may be as Figure 5 shown.

[0078] The first device layer 1241 may be formed of silicon material. The SOI substrate is a stacked structure formed by a substrate silicon, a buried oxide layer, and a top silicon layer. The first device layer 1241 is formed in the SOI top silicon layer. Although silicon material has the advantages of being common and low-cost, silicon material is a strong nonlinear material. In particular, it has a strong two-photon absorption effect and free carrier absorption effect, and its low-order nonlinear coefficient is also large. Therefore, it is not suitable for high-power optical injection. In this regard, a device layer of another material can be used to adapt to high-power optical injection.

[0079] Optionally, the device layer of another material may be a second device layer, which may be formed of a material having a relatively low nonlinear coefficient compared to silicon (for example, silicon nitride material). The light coupled to the optical chip is first split in the second optical device layer. After splitting, the optical power of each portion of the light decreases significantly compared to the light coupled to the chip. When the light is split into a sufficient number of portions, the optical power of each portion of the light is small enough so that each portion of the light can be normally transmitted in the optical device layer. Therefore, it can adapt to better optical injection power.

[0080] Correspondingly, the optical device layer 124 may further include a second device layer. Here, the two device layers may be adjacent structures, that is, the two device layers may be directly grown together. In this manufacturing method, the two device layers may affect each other, and the requirements for manufacturing accuracy and the like are relatively high. In this regard, a spacer layer (buffer layer) can be added between the first device layer and the second device layer to physically isolate the adjacent device layers (space apart the adjacent device layers). AsFigure 6 As shown, the optical device layer 124 may further include: a second device layer 1242, and a third spacer layer 1243 disposed between the first device layer 1241 and the second device layer 1242.

[0081] The third spacer layer 1243 may be formed of a silicon dioxide material, and its thickness may be in the range of several tens of nanometers (e.g., 50 nm) to hundreds of nanometers (e.g., 100 nm), etc., which meets the thickness requirements for optical device coupling. The light transmittance of the third spacer layer 1243 is the light transmittance that meets the requirement for the light beam to pass through or have high transmittance therein (i.e., the light transmittance of the spacer layer meets the light transmittance requirement of the emitted light beam).

[0082] The second device layer 1242 is formed in a silicon nitride material layer located above the third spacer layer 1243. It may include at least one optical device. The type, quantity, and position of the optical devices included in the second device layer 1242 may be the same or corresponding to those of the optical devices included in the first device layer 1241, or may be at least partially different. Here, the optical device structure layer includes multiple device layers formed of different materials, which can combine the advantages of different materials to improve the reliability of light beam propagation; a spacer layer is disposed between adjacent device layers to separate adjacent device layers, which can reduce the manufacturing difficulty of the device layers.

[0083] The second device layer 1242 may include a second coupler, a second beam splitter, a second phase shifter, and a second optical antenna. The positional relationship of the respective optical devices in the second device layer 1242 may be as Figure 6 shown. It should be particularly noted that Figure 6 is only an example. The same optical devices may also have partially overlapping or completely non - overlapping projections in the vertical direction; for example, the projections of the first optical antenna and the second optical antenna in the vertical direction may completely overlap, may partially overlap, or may completely not overlap.

[0084] When the optical devices in the first device layer 1241 are combined with the optical devices in the second device layer 1242, at least part of a third interlayer coupler, a third beam splitter, a third phase shifter, and a third optical antenna are formed. Here, the first coupler and the second coupler can be combined to form a third interlayer coupler, through which light can be coupled onto an optical chip, improving the optical coupling efficiency while reducing the volume of the coupling device; the first beam splitter and the second beam splitter can be combined to form a third beam splitter, and through the coupling of the beam splitters, it is possible to cascade a SiN beam splitter + a Si beam splitter, allowing the light beam to be split by the SiN beam splitter first to reduce the optical power, ensuring that each light beam can be normally transmitted in the optical device layer, and thus greatly increasing the optical power input into the optical chip; the first phase shifter and the second phase shifter can be combined to form a third phase shifter, which changes the phase of the light beam using the electro-optic / thermo-optic effect; the first optical antenna and the second optical antenna can be combined to form a third optical antenna, and through the coupling of the optical antennas, the optical output power can be increased. Here, the third interlayer coupler, the third beam splitter, the third phase shifter, and the third optical antenna formed by coupling can be used as a third device layer, that is Figure 6 the structure within the dashed box in

[0085] It should be noted that the first optical antenna and the second optical antenna can be locally coupled. The part of the first optical antenna that is not coupled to the second optical antenna remains the first optical antenna, and the part coupled to the second optical antenna is coupled into the third optical antenna. The part of the second optical antenna that is not coupled to the first optical antenna remains the second optical antenna, and the part coupled to the first optical antenna is coupled into the third optical antenna. That is to say, the part of the first optical antenna that is not coupled to the second optical antenna remains the first optical antenna, the part of the second optical antenna that is not coupled to the first optical antenna remains the second optical antenna, and the part where the first optical antenna is coupled to the second optical antenna is the third optical antenna.

[0086] The second device layer contains a second beam splitter, and an interlayer coupling structure, such as a wedge coupler or a grating coupler, is provided between the first beam splitter and the second beam splitter. Therefore, after coupling high-power light onto the optical chip, the light beam is first split by the second beam splitter (for example, one into two, two into four, four into eight, etc.). After the splitting is completed, it is ensured that a single light beam can be normally transmitted in the device layer; at this time, the split light beam is introduced into the silicon material through the interlayer coupling structure for propagation, which can avoid situations such as two-photon absorption. By adopting the above method, the advantages of different materials can be combined to improve the reliability of light beam propagation. Of course, the first device layer and the second device layer can also be used separately and do not have to be combined.

[0087] As an alternative, for the case where the optical device layer includes a second device layer, the reflective layer can be located between the second device layer and the protective layer. The position of the reflective layer can be set based on the positions of the first optical antenna, the second optical antenna, and the third optical antenna. The projection of the reflective layer in the vertical direction overlaps at least partially or completely with the projection of at least some of the first optical antenna, the second optical antenna, and the third optical antenna in the vertical direction. To ensure that the reflective layer can be adapted to the first optical antenna, the second optical antenna, and the third optical antenna, the projection of the reflective layer in the vertical direction overlaps at least partially with any one of the first optical antenna, the second optical antenna, and the third optical antenna in the vertical direction. For example, the projection of the reflective layer in the vertical direction completely covers the projection of the first optical antenna, the second optical antenna, and the third optical antenna in the vertical direction. An interlayer can be provided between the reflective layer and the second device layer to space apart the reflective layer and the second device layer.

[0088] As an alternative, the substrate 11 and the protective layer 121 can be fixedly connected after forming the optical device structure layer based on the top silicon layer in the SOI substrate. There can be various ways to fixedly connect the two together, which can include but are not limited to at least one of the following: fixedly connected by a bonding method; fixedly connected using an adhesive. It can also be fixedly connected by other means, which is not limited in this embodiment. Here, the bonding process used for bonding can be a low-temperature bonding process or other bonding processes, as long as the substrate 11 and the protective layer 121 can be tightly connected together.

[0089] As an alternative, for the method of fixedly connecting the substrate 11 and the protective layer 121 using an adhesive, the thermal conductivity of the adhesive is less than 10 W / (m·K), and the sum of the thickness of the adhesive layer and the thickness of the silica material layer added thereto is greater than 3 μm. Here, connecting the substrate 11 and the protective layer 121 using an adhesive with low thermal conductivity can improve the thermal resistance ability of the adhesive. Moreover, the sum of the thickness of the adhesive layer of the adhesive and the thickness of the silica material layer being greater than 3 μm can improve the fixing ability of the adhesive and avoid device separation caused by insufficient fixing ability of the adhesive. In addition, the thick adhesive can also play a certain supporting role.

[0090] Optionally, the above-mentioned silica material layer can include a protective layer and a first interlayer, that is, both the protective layer and the first interlayer can be made of silica material. Correspondingly, the sum of the thickness of the adhesive layer of the adhesive and the thickness of the protective layer and the first interlayer added thereto can be greater than 3 μm.

[0091] The following explains the optical chip in the embodiments of the present application in combination with optional examples. As Figure 7As shown in the figure, the optical chip includes: an optical device structure layer 12 and a substrate 11; the optical device structure layer 12 includes, from top to bottom, an optical device layer 124, a first spacer layer 123, a reflective layer 122, a second spacer layer 126, an optical correction structure 125, and a protective layer 121; the optical device layer 124 includes, from top to bottom, a first device layer 1241, a third spacer layer 1243, and a second device layer 1242. Here, the substrate 11 can be a thermal isolation substrate, the material of which can be glass, and the material of the protective layer 121 can be silicon dioxide. Here, the thermal isolation substrate includes at least one material layer formed of a material with a thermal conductivity less than 100 W / (m·K). Through the above structure, not only can a better thermal isolation effect be achieved, but also the emission efficiency of the optical antenna can be improved, and the optical loss can be reduced.

[0092] As an alternative solution, the optical chip further includes a window 14 located above the optical device structure layer, and the window 14 is made of a transparent material with a thermal conductivity less than 100 W / (m·K). It can be understood that in this embodiment, since the window is light-transmissive, it can ensure that the light beam can pass through normally. At the same time, since the material used for the window has a thermal conductivity less than 100 W / (m·K) and has a strong thermal barrier ability, the thermal isolation effect on the optical antenna can be further improved, thereby improving the spot quality. In addition, it can also protect the optical chip, facilitate subsequent cleaning, and prevent damage to the optical chip by external forces.

[0093] As an alternative solution, the window is a single-layer material structure or a laminated structure including multiple material layers.

[0094] As an alternative solution, the preparation materials of the window include one or more of silicon dioxide, quartz, and ordinary glass. Usually, due to the advantages of quartz such as low thermal conductivity, high light transmittance, high hardness, and easy availability, quartz is generally used to form the window.

[0095] According to another aspect of the embodiments of the present application, a method for preparing an optical chip is further provided. The method for preparing an optical chip can be used to prepare the optical chip in any of the above embodiments, and those that have been described will not be repeated here. Figure 8 is a schematic flowchart of an alternative method for preparing an optical chip according to the embodiments of the present application. As Figure 8 shown, the process of the above method can include the following steps:

[0096] Step S802, provide an SOI substrate.

[0097] In this embodiment, after the front process (optical device structure) is completed on the SOI substrate, the device is fixed to another carrier substrate (substrate, e.g., thermal isolation substrate) from the front, and then all or part of the SOI substrate silicon layer is removed to complete the preparation of the optical chip. That is, first, an optical device structure layer is formed on the top silicon layer in the SOI substrate, then a substrate is fixed on the formed optical device structure layer, and finally all or part of the SOI substrate silicon layer is removed. Through the above preparation setup of the optical chip, the support ability of the SOI substrate is utilized, improving the efficiency and convenience of optical chip preparation.

[0098] Based on the above optical chip preparation scheme, an SOI substrate can be provided first. Here, the SOI substrate can be provided by a robotic arm or other control components. The SOI substrate is placed on an insulator placed on the operating table. The SOI substrate can be pre-produced and placed at a designated position, or other SOI substrate providing methods can also be adopted.

[0099] Step S804, form an optical device layer in the top silicon layer of the SOI substrate, where the optical device layer includes at least one optical device, and the optical device layer is used to emit a detection beam.

[0100] The SOI substrate can include a top silicon layer, a buried oxide layer, and a substrate silicon layer. An optical device structure layer can be formed on the top silicon layer of the provided SOI substrate. For example, the aforementioned optical device structure layer. The optical device structure layer can include an optical device layer, and the optical device layer includes at least one optical device (integrated optical device, e.g., a first coupler, a first optical waveguide, a first beam splitter, a first phase shifter, a first optical antenna, etc., a first integrated optical device, and also, a second coupler, a second optical waveguide, a second beam splitter, a second phase shifter, a second optical antenna, etc., a second integrated optical device). The optical device layer can be used to emit a detection beam. Correspondingly, forming an optical device structure layer on the top silicon layer of the SOI substrate can include: forming an optical device layer in the top silicon layer of the SOI substrate.

[0101] There can be one or more ways to form the optical device layer on the top silicon layer. For different optical devices, their forming methods can be the same or different. The forming methods of the optical devices can include but are not limited to at least one of the following: microfabrication processes (e.g., bulk silicon processing processes), patterning processes, and other processing processes. This is not limited in this embodiment.

[0102] Optionally, the optical devices in the optical device layer may include couplers, which can be fabricated using any suitable microfabrication process. Taking the bulk silicon processing technology as an example, a part of the silicon material is selectively removed in the top silicon layer according to the designed pattern to form the designed micro three-dimensional structure. The patterning process of the coupler may include etching, such as wet etching and dry etching. Depending on the etching rate along different crystal orientations in the etching solution, wet etching can be divided into isotropic etching and anisotropic etching. Dry etching uses physical methods (e.g., sputtering, ion etching) or chemical methods (e.g., reactive ion etching). The optical devices in the optical device layer may also include optical waveguides (which can be optically coupled to the coupler, e.g., strip optical waveguides) and other optical devices, such as end face couplers, beam splitters, and optical antennas. It may also include active devices based on optical waveguides (e.g., phase shifters), which are not limited in this embodiment.

[0103] After forming the optical device layer, the removed part on the top silicon layer can be filled with a suitable dielectric material (e.g., silicon dioxide) to prevent voids from appearing in the top silicon layer. Exemplarily, silicon dioxide can be deposited in the patterned top silicon layer through an HDP (High Density Plasma) deposition process.

[0104] Step S806, form a first spacer layer on the SOI substrate with the optical device layer formed thereon, where the first spacer layer covers the optical device layer.

[0105] A first spacer layer can be formed on the SOI substrate with the optical device layer formed thereon. For example, the first spacer layer in the foregoing embodiment, the material, thickness, light transmittance, etc. of the first spacer layer are similar to those in the foregoing embodiment (the description of the protective layer can also be referred to), which will not be elaborated here. The first spacer layer can be formed by depositing silicon oxide material or silicon dioxide material. For example, silicon dioxide material or silicon dioxide material is deposited through a PECVD (Plasma Enhanced Chemical Vapor Deposition) process to form the first spacer layer. Here, the formed first spacer layer can cover the optical device layer, and its size (projection in the vertical direction) can be the same as that of the optical device layer or slightly larger than the optical device layer, which is not limited in this embodiment.

[0106] The thickness of the first spacer layer is adjustable and can be achieved, for example, by oxide deposition and planarization. Here, the planarization can be achieved through a CMP (Chemical Mechanical Polishing) process to meet different thickness requirements for the first spacer layer and at the same time meet the flatness requirements for the upper surface of the first spacer layer.

[0107] Step S808, form a reflective layer on the first spacer layer. The reflective layer includes a reflection structure for reflecting the detection beam emitted from the optical device layer towards the light output side, where the light output side is the side of the optical device layer facing away from the first spacer layer.

[0108] Similar to the foregoing embodiments, a reflective layer can be added to the optical device structure layer. The reflective layer includes a reflection structure for reflecting the detection beam (which can be the beam emitted from at least some of the first optical antenna, the second optical antenna, and the third optical antenna) emitted from the optical device layer towards the light output side, where the light output side is the side of the optical device layer facing away from the first spacer layer. For example, the detection beam is emitted upward into the detection space.

[0109] When forming the reflective layer, a metal can be grown or deposited on the first spacer layer (forming a metal material layer, which can be the first metal material layer), or a dielectric film can be evaporated, or a reflective grating can be fabricated to form the reflective layer, so that the signal light emitted upward is reflected downward, passes through the SOI substrate, and is then emitted into the space. Here, the signal light that is reflected downward, passes through the SOI substrate, and is then emitted into the space only needs to pass through the remaining part of the SOI substrate to be emitted into the detection space.

[0110] Here, when the reflective layer is prepared, the substrate has not been formed (fixed above the protective layer), and the device is in a flipped orientation. During actual use, the substrate is below the protective layer, and at this time, the emitted beam is reflected upward into the detection space. The detection beam emitted from the optical device layer (such as the first device layer, the second device layer, the third device layer, etc.) being emitted upward into the detection space means that in the placement mode where the optical device layer is on top and the reflective layer is below, the detection beam emitted from the optical device layer is emitted upward into the detection space. When the optical chip is fabricated, the reflective layer reflecting the signal light emitted upward downward, passing through the SOI substrate, and then being emitted into the space means that in the placement mode where the optical device layer is below and the reflective layer is above, the reflective layer reflects the signal light emitted upward downward, passes through the SOI substrate, and then is emitted into the space.

[0111] Step S810, form a protective layer on the SOI substrate on which the reflective layer is formed. The protective layer covers the reflective layer, and the optical device layer, the first spacer layer, the reflective layer, and the protective layer are stacked in sequence to form an optical device structure layer.

[0112] A protective layer can be formed on the SOI substrate on which the reflective layer is formed. The material, thickness, light transmittance, etc. of the protective layer are similar to those in the foregoing embodiments and will not be elaborated here. The protective layer can be formed by depositing a silicon dioxide material. For example, a protective layer is formed through the silicon dioxide material. Here, the formed protective layer covers the reflective layer (the projection of the protective layer in the vertical direction can be larger than the projection of the reflective layer in the vertical direction), and the optical device layer, the first spacer layer, the reflective layer, and the protective layer are stacked in sequence to obtain an optical device structure layer.

[0113] Optionally, before forming the protective layer, other device layers can be formed. For example, an optical correction structure. The optical correction structure and the reflective layer can be spaced apart by a spacer layer. The formation method of the spacer layer can be the same as or similar to that of the protective layer.

[0114] Step S812: Provide a substrate, fix the substrate to the protective layer, and remove part or all of the substrate silicon in the SOI substrate.

[0115] After forming the protective layer, a substrate can be provided, and the provided substrate is fixed above the protective layer. After fixing the substrate above the protective layer, the device (semi-finished product, at this time the optical chip is not fabricated) can be inverted (i.e., flipped) to expose the substrate silicon layer in the lowermost SOI substrate, and all or part of the substrate silicon layer in the SOI substrate is removed to obtain the optical chip structure in the foregoing embodiments.

[0116] The process of removing at least part of the substrate silicon layer can be achieved by etching. TMAH (TetraMethyl Ammonium Hydroxide) solution can be used for etching, or the substrate silicon layer can be thinned by wet etching first, and then part of the substrate silicon layer can be removed by dry etching. If part of the substrate silicon layer in the SOI substrate is removed, the remaining thickness of the substrate silicon layer is less than 100 μm.

[0117] The provided substrate can be a thermal isolation substrate. The thermal isolation substrate can be a single-layer material structure or a laminated structure including multiple material layers. The thermal isolation substrate includes at least one material layer formed of a material with a thermal conductivity less than 100 W / (m·K). For example, the thermal isolation substrate can be a material with a thermal conductivity less than 100 W / (m·K), such as quartz glass. Another example is that the thermal isolation substrate can be a laminated structure of quartz glass + silicon dioxide material layer; it should be noted that when the above thermal isolation substrate is a laminated structure, the thickness of the material layer formed of a material with a thermal conductivity less than 100 W / (m·K) is greater than or equal to 10 μm.

[0118] The optical chip formed by the method provided in this embodiment reflects the detection beam emitted from the optical device layer through the reflection structure in the reflection layer, and the detection beam can only be emitted from one side (the side opposite to the reflection layer), avoiding the influence of the substrate on the beam emission quality, thereby reducing optical loss, improving the emission power of the optical antenna, ensuring the detection performance of the lidar, and effectively solving the problem of low emission power of the optical antenna. In addition, the optical chip sequentially includes a substrate, a protective layer, a reflection layer, a spacer layer, and an optical device layer from bottom to top. The overall process is simple, the integration degree of the optical device is high, the structure is compact, which is conducive to mass production, and can greatly reduce the cost of the product.

[0119] As an alternative solution, fixing the substrate to the protective layer includes:

[0120] Bonding the substrate to the protective layer; or,

[0121] Gluing the substrate to the protective layer with an adhesive.

[0122] There are various ways to fix the substrate above the protective layer, which may include but are not limited to the following: fixing the substrate above the protective layer by bonding, or fixing the substrate above the protective layer by gluing (for example, gluing the substrate to the protective layer with glue). In addition, the substrate can also be fixed above the protective layer by other means, which are not limited in this embodiment. Here, the bonding process used for bonding can be a low-temperature bonding process or other bonding processes, as long as the substrate and the protective layer can be tightly connected together.

[0123] As an alternative solution, similar to the foregoing embodiment, when the substrate is glued to the protective layer with an adhesive, the thermal conductivity of the adhesive is less than 10 W / (m·K), and the sum of the thickness of the adhesive layer and the thickness of the silicon dioxide material layer plus it is greater than 3 μm; wherein, both the protective layer and the first spacer layer are made of silicon dioxide material. What has been described before will not be elaborated here.

[0124] As an alternative solution, forming an optical device layer in the top silicon layer of the SOI substrate includes:

[0125] In the top silicon layer of the SOI substrate, a first device layer is formed by using a patterning process, wherein the first device layer includes a first coupler, a first beam splitter, a first phase shifter, and a first optical antenna.

[0126] The optical device layer may include at least one device layer, and the at least one device layer includes a first device layer. The first device layer may be formed in the top silicon layer of the SOI substrate by using a patterning process. There may be one or more ways to form the first device layer on the top silicon layer. For different optical devices, the forming methods may be the same or different. The forming methods of the optical devices may include but are not limited to at least one of the following: microfabrication processes (e.g., bulk silicon processing processes), patterning processes, and other processing processes, which are not limited in this embodiment. Here, the first device layer includes a first coupler, a first beam splitter, a first phase shifter, and a first optical antenna, and may also include some of them, or more optical devices than those described above.

[0127] Optionally, a coupler (e.g., the first coupler) can be fabricated by using any suitable microfabrication process. Taking the bulk silicon processing process as an example, a part of the silicon material is selectively removed in the top silicon layer according to the designed pattern to form the designed micro three-dimensional structure. The patterning process of the coupler may include etching, such as wet etching and dry etching. Depending on the etching rate along different crystal orientations in the etching solution, wet etching can be divided into isotropic etching and anisotropic etching. Dry etching uses physical methods (e.g., sputtering, ion etching) or chemical methods (e.g., reactive ion etching). Other optical devices can be formed by using similar processes, which will not be elaborated here.

[0128] Optionally, the optical devices on the first device layer may further include optical waveguides (which can be optically coupled to the coupler, e.g., strip optical waveguides) and other optical devices, such as end face couplers, beam splitters, and optical antennas, and may also include active devices based on optical waveguides (e.g., phase shifters), which are not limited in this embodiment.

[0129] After the first device layer is formed, the removed part on the top silicon layer can be filled with a suitable dielectric material (e.g., silicon dioxide) to prevent voids from appearing in the top silicon layer. Exemplarily, silicon dioxide can be deposited in the patterned top silicon layer by using the HDP (High Density Plasma) deposition process.

[0130] In this embodiment, in addition to the first device layer, the optical device layer may further include a second device layer. Before forming the second device layer, silicon dioxide can be deposited on the SOI substrate on which the first device layer is formed to form a third spacer layer, and the third spacer layer can cover the first device layer to better separate the two device layers. The forming method of the third spacer layer is the same as or similar to that of the protective layer, the first spacer layer, and the second spacer layer, which will not be elaborated here.

[0131] A silicon nitride material layer can be formed on the third spacer layer, and then the silicon nitride material layer is patterned to form a second device layer. The process of forming the second device layer in the silicon nitride material layer is similar to the process of forming the first device layer in the top silicon layer, and will not be repeated here. Here, the second device layer includes a second coupler, a second beam splitter, a second phase shifter, and a second optical antenna. When the optical device in the first device layer (which may be referred to as the first optical device) is combined with the optical device in the second device layer (which may be referred to as the second optical device), at least part of the optical devices (which may be referred to as the third optical device) such as the third interlayer coupler, the third beam splitter, the third phase shifter, and the third optical antenna can be formed.

[0132] For example, when preparing an optical chip, an optical device layer may be first formed on an SOI substrate, such as Figure 9 As shown, Figure 9 A substrate (first substrate, for example, SOI substrate) is shown, and the substrate includes: a top silicon layer, a buried oxide layer, and a substrate silicon layer. When forming the optical device layer, a first optical device is manufactured on the top silicon layer to obtain a first device layer 1241. The first optical device includes a first coupler, a first beam splitter, a first phase shifter, and a first optical antenna, and may also include a first optical waveguide located between the first coupler and the first beam splitter.

[0133] Silicon dioxide is grown for the first time on the top silicon layer in the SOI substrate to form a spacer layer, i.e., the third spacer layer 1243, which is used to protect the first optical device, and a silicon nitride layer is grown on the silicon dioxide grown for the first time, and a second optical device is made on the silicon nitride layer to obtain a second device layer 1242. The second optical device includes a second coupler, a second beam splitter, a second phase shifter, and a second optical antenna, and may also include a second optical waveguide located between the second coupler and the second beam splitter. The optical device of the silicon nitride layer can be combined with the optical device of the top silicon layer to form optical devices such as a third interlayer coupler, a third beam splitter, a third phase shifter, and a third optical antenna (the third optical device integrated on the optical chip). At this point, an optical device layer 124 is formed on the SOI substrate.

[0134] Here, the optical device layer includes multiple device layers formed of different materials, which can combine the advantages of different materials to improve the reliability of light beam propagation; a spacing layer is set between adjacent device layers to separate the adjacent optical device layers, which can reduce the difficulty of preparing the optical device layer.

[0135] After forming the optical device layer 124, silicon dioxide can be grown a second time above the silicon nitride layer (the second device layer 1242) to form a spacer layer, that is, the first spacer layer 123, for protecting the second optical device and the third optical device, and a metal can be grown or deposited on the silicon dioxide grown a second time (forming a metal material layer, which can be the first metal material layer), or a dielectric film can be evaporated, or a reflection grating can be fabricated to form the reflection layer 122, as Figure 10 shown. The reflection layer 122 can reflect the signal light emitted upward downward, pass through the SOI substrate and then be emitted into space. Here, the signal light that is reflected downward and passes through the SOI substrate and then is emitted into space only needs to pass through the remaining part of the SOI substrate to be emitted into the detection space, as Figure 11 shown, Figure 11 Each optical device in can be the corresponding optical device in the first device layer, the second device layer and the third device layer. Among them, the substrate silicon layer and the buried oxide layer in the SOI substrate will be removed.

[0136] Here, when preparing the reflection layer, another substrate (the second substrate, that is, the substrate 11) has not been fixed above the protective layer yet, and the device is in a flipped orientation. During actual use, the second substrate is below the protective layer, and at this time, the emitted light beam is reflected upward into the detection space. The light beam emitted from the optical device layer upward into the detection space means that according to the placement method where the optical device structure layer is on top and the reflection layer is at the bottom, the light beam emitted from the optical device structure layer is emitted upward into the detection space. When fabricating the optical chip, the reflection layer reflects the signal light emitted upward downward, passes through the SOI substrate and then is emitted into space means that according to the placement method where the optical device structure layer is at the bottom and the reflection layer is on top, the reflection layer reflects the signal light emitted upward downward, passes through the SOI substrate and then is emitted into space.

[0137] As an alternative solution, when the optical device structure layer further includes an optical correction structure, the above method further includes:

[0138] Before forming the protective layer, a second spacer layer is formed on the SOI substrate on which the reflection layer is formed, and the second spacer layer covers the reflection layer;

[0139] An optical correction structure is formed on the second spacer layer, where the optical correction structure is used to change the refractive index of the optical antenna in the optical device layer.

[0140] To improve the beam emission ability of the optical antenna, an optical correction structure can be formed based on the position of the optical antenna in the optical device layer (for example, the first optical antenna, the second optical antenna, the third optical antenna, etc.). Here, the optical correction structure is used to change the refractive index of at least some of the optical antennas among the first optical antenna, the second optical antenna, and the third optical antenna.

[0141] The optical correction structure can be formed by a lithography process, where the lithography process refers to the process of transferring the designed patterns, structures, and circuit patterns to the chip surface through process steps such as photolithography, etching, deposition, etc. (similar to those in the foregoing embodiments). The accuracy and stability of the lithography process have an important impact on the performance and stability of the chip.

[0142] To protect the reflective layer, before forming the optical correction structure, silicon dioxide material can be first deposited on the SOI substrate on which the reflective layer is formed to form a second spacer layer that covers the reflective layer to protect the reflective layer. The formation method of the second spacer layer is the same as or similar to that of the first spacer layer and the third spacer layer, and will not be elaborated here. A metal material layer (the formed metal material layer can be the second metal material layer) can be formed on the second spacer layer, and the above-mentioned optical correction structure can be formed through a lithography process.

[0143] For example, as Figure 12 shown, silicon dioxide is grown for the third time above the reflective layer 122 to form a spacer layer, that is, the second spacer layer 126, for protecting the reflective layer 122. Metal is grown or deposited on the silicon dioxide grown for the third time to fabricate one or more thermoresistors, PZT (lead zirconate titanate thin film, that is, piezoelectric ceramic), or acoustic field devices, etc., to form an optical correction structure 125 (optical correction device), which can adjust the refractive indices of different regions of the first optical antenna, the second optical antenna, and the third optical antenna. In addition, silicon dioxide can be grown for the fourth time above the above-mentioned optical correction structure 125 to form a protective layer 121 for protecting the optical correction structure 125, as Figure 13 shown.

[0144] Optionally, a plurality of through holes can be formed in the silicon dioxide grown four times by etching. The through holes respectively extend to the required first optical device, second optical device, third optical device, and optical correction structure, and metal is grown or deposited to form electrical connections.

[0145] Optionally, metal is grown or deposited on the silicon dioxide grown for the fourth time and patterned to form a first metal wiring layer. A plurality of back holes are formed on the back surface of the SOI substrate from which the substrate silicon layer has been completely or partially removed by etching. The back holes respectively extend to the required first metal wiring layer, and metal is grown or deposited, and electrodes pads are formed on the top, and electrical connections can be made externally through wire bonding or flip-chip bonding; as Figure 7 shown, pad electrodes corresponding to the phase shifter are formed, and the working voltage is provided for the phase shifter through these electrodes. Silicon dioxide is grown for the fifth time above the first metal wiring layer for protecting the first metal wiring layer. Here, the total thickness of the silicon dioxide grown for the first, second, third, fourth, and fifth times is 0.2 μm to 20 μm.

[0146] Then, a substrate 11 (e.g., a thermal isolation substrate) can be provided and fixed to the surface of the silicon dioxide grown for the fifth time. Fixing the substrate 11 can be achieved by bonding the substrate 11 to the surface of the silicon dioxide grown for the fifth time; then the device is flipped, and all or part of the substrate silicon layer in the SOI substrate is removed. For example, removing the substrate silicon layer is as shown in Figure 14 the figure.

[0147] If there is less metal wiring, only the aforementioned first metal wiring layer can be formed. If there is more metal wiring, one or more additional metal wiring layers need to be added. For example, metal is grown or deposited on the back surface of the SOI substrate from which the substrate silicon layer has been removed in whole or in part, and then patterned to form a second metal wiring layer; silicon dioxide is grown for the sixth time above the second metal wiring layer to protect the second metal wiring layer. And so on until the formed metal wiring layers meet the requirements of the metal wiring. So far, the optical chip preparation is completed.

[0148] Through the embodiments provided in the present application, the refractive index of the optical antenna is changed by heating the optical antenna through the optical correction structure, so as to change the outgoing light direction corresponding to the antenna, and spot alignment is achieved. The optical correction structure may further include multiple groups of local heating structures, and each local heating structure can be independently controlled for heating to achieve precise control of the optical antenna to be heated, compensate for the inconsistency within the aperture of the optical antenna caused by the process, and thus improve the spot quality of the outgoing light beam. Each group of local heating structures is evenly distributed above the corresponding optical antenna, and the specific number can be set according to needs, and is not limited in this embodiment.

[0149] In an alternative solution, the preparation method further includes: forming a window on the upper side of the optical device layer with a transparent material having a thermal conductivity less than 100 W / (m·K). Specifically, the window can be fixed to the upper side of the optical device layer through an ultraviolet curable adhesive. The window can be a single-layer material structure or a laminated structure including multiple material layers; the preparation materials thereof can include one or more of silicon dioxide, quartz, and ordinary glass.

[0150] It can be understood that in this embodiment, since the window is light-transmissive, it can ensure that the light beam can pass through normally. At the same time, because the material used for the window has a thermal conductivity less than 100 W / (m·K) and has a strong thermal barrier ability, the thermal isolation effect on the optical antenna is further improved, and thus the spot quality is improved. It can be understood that an opening is also provided on the window, and the opening is correspondingly arranged with the electrode pad.

[0151] It should be noted that, for the foregoing method embodiments, for the sake of simple description, they are all expressed as a series of action combinations. However, those skilled in the art should know that this application is not limited by the described action sequence, because according to this application, certain steps can be performed in other sequences or simultaneously. Secondly, those skilled in the art should also know that the embodiments described in the specification are all preferred embodiments, and the actions and modules involved are not necessarily essential to this application.

[0152] If the integrated unit in the above embodiments is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in the above computer-readable storage medium. Based on such an understanding, the technical solution of this application, in essence, or the part that contributes to the related technology, or all or part of this technical solution, can be embodied in the form of a software product. This computer software product is stored in the storage medium and includes several instructions for causing one or more computer devices (which can be personal computers, servers, or network devices, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application.

[0153] In the above embodiments of this application, the descriptions of the various embodiments have their own emphases. For the parts not detailed in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0154] The unit described as a separate component may or may not be physically separated, and the component shown as a unit may or may not be a physical unit, that is, it may be located in one place, or may be distributed to multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0155] In addition, in each embodiment of this application, the various functional units can be integrated in a processing unit, or each unit can exist physically alone, or at least two units can be integrated in one unit. The above integrated unit can be implemented in the form of hardware or in the form of a software functional unit.

[0156] The above are only the optional implementation manners of this application. It should be noted that for those of ordinary skill in the art, without departing from the principle of this application, several improvements and refinements can still be made, and these improvements and refinements should also be regarded as the protection scope of this application.

Claims

1. An optical chip, characterized in that, Comprising: A substrate, and an optical device structure layer formed on a top silicon layer in a SOI substrate above the substrate; wherein, The optical device structure layer formed on the top silicon layer in the SOI substrate sequentially includes a protective layer, a reflective layer, a first spacer layer, and an optical device layer from bottom to top; wherein, The protective layer is located above the substrate and fixedly connected to the substrate; The reflective layer is located above the protective layer, and the reflective layer includes a reflective structure for reflecting the detection beam emitted from the optical device layer upward; The first spacer layer is located above the reflective layer and covers the reflective layer for spacing apart the reflective layer and the optical device layer; The optical device layer is located above the first spacer layer and includes at least one optical device for emitting the detection beam; Wherein, the substrate and the protective layer are fixedly connected after the optical device structure layer is formed on the top silicon layer in the SOI substrate.

2. The optical chip according to claim 1, characterized in that, The optical device structure layer further includes: An optical correction structure located between the protective layer and the reflective layer for changing the refractive index of the optical antenna in the optical device layer; and A second spacer layer disposed between the optical correction structure and the reflective layer for spacing apart the optical correction structure and the reflective layer.

3. The optical chip according to claim 1, characterized in that, The optical device layer includes: A first device layer formed in the top silicon layer of the SOI substrate, wherein the first device layer includes a first coupler, a first beam splitter, a first phase shifter, and a first optical antenna; or, A first device layer, a second device layer, and a third spacer layer disposed between the first device layer and the second device layer, wherein the first device layer is formed in the top silicon layer of the SOI substrate, the first device layer includes a first coupler, a first beam splitter, a first phase shifter, and a first optical antenna, the second device layer is formed in a silicon nitride material layer above the third spacer layer, and the second device layer includes a second coupler, a second beam splitter, a second phase shifter, and a second optical antenna; when the optical devices in the first device layer are combined with the optical devices in the second device layer, at least part of a third interlayer coupler, a third beam splitter, a third phase shifter, and a third optical antenna is formed.

4. The optical chip according to claim 3, characterized in that, The projection of the reflective layer in the vertical direction partially or completely overlaps with the projection of any one or more of the first optical antenna, the second optical antenna, and the third optical antenna in the vertical direction.

5. The optical chip according to claim 1, characterized in that, The substrate and the protective layer are fixedly connected by a bonding method after the optical device structure layer is formed on the top silicon layer in the SOI substrate; or, The substrate and the protective layer are fixedly connected by using an adhesive after the optical device structure layer is formed on the top silicon layer in the SOI substrate.

6. The optical chip according to claim 5, characterized in that, The thermal conductivity of the adhesive is less than 10 W / (m·K), and the sum of the thickness of the adhesive layer and the thickness of the silicon dioxide material layer plus it is greater than 3 μm; Wherein, both the protective layer and the first spacer layer are made of silicon dioxide material.

7. The optical chip according to claim 1, characterized in that, The substrate is made of silicon, glass, diamond, or a SOI substrate.

8. The optical chip according to claim 1, characterized in that, The reflection structure is a metal reflection structure, a dielectric film or a reflection grating.

9. The optical chip according to claim 1, characterized in that, The optical chip further includes a window located above the optical device structure layer, and the window is made of a transparent material with a thermal conductivity less than 100 W / (m·K).

10. The optical chip according to claim 9, characterized in that, The window is a single-layer material structure or a laminated structure including multiple material layers.

11. The optical chip according to claim 10, characterized in that, The preparation materials of the window include one or more of silicon dioxide, quartz, and ordinary glass.

12. A method for preparing an optical chip, characterized in that, Including: Providing an SOI substrate; Forming an optical device layer in the top silicon layer of the SOI substrate, wherein the optical device layer includes at least one optical device, and the optical device layer is used to emit a detection beam; Forming a first spacer layer on the SOI substrate on which the optical device layer is formed, wherein the first spacer layer covers the optical device layer; Forming a reflection layer on the first spacer layer, wherein the reflection layer includes a reflection structure, and the reflection structure is used to reflect the detection beam emitted from the optical device layer toward the light-emitting side, and the light-emitting side is the side of the optical device layer facing away from the first spacer layer; Forming a protective layer on the SOI substrate on which the reflection layer is formed, wherein the protective layer covers the reflection layer, and the optical device layer, the first spacer layer, the reflection layer, and the protective layer are stacked in sequence to form an optical device structure layer; Providing a substrate, fixing the substrate to the protective layer, and removing part or all of the substrate silicon in the SOI substrate.

13. According to the preparation method described in claim 12, wherein, The fixing the substrate to the protective layer includes: Bonding the substrate to the protective layer; or, Gluing the substrate to the protective layer through an adhesive.

14. According to the preparation method described in claim 13, wherein, The thermal conductivity of the adhesive is less than 10 W / (m·K), and the thickness of the adhesive layer and the thickness sum of the adhesive layer and the silicon dioxide material layer are greater than 3 μm; Wherein, both the protective layer and the first spacer layer are made of silicon dioxide material.

15. According to the preparation method described in claim 12, wherein, When the optical device structure layer further includes an optical correction structure, the method further includes: Before forming the protective layer, forming a second spacer layer on the SOI substrate on which the reflection layer is formed, and the second spacer layer covers the reflection layer; Forming an optical correction structure on the second spacer layer, wherein the optical correction structure is used to change the refractive index of the optical antenna in the optical device layer.

16. According to the preparation method described in claim 12, wherein, The forming the optical device layer in the top silicon layer of the SOI substrate includes: In the top silicon layer of the SOI substrate, forming a first device layer by using a patterning process, wherein the first device layer includes a first coupler, a first beam splitter, a first phase shifter, and a first optical antenna; or, In the top silicon layer of the SOI substrate, a first device layer is formed by using a patterning process. The first device layer includes a first coupler, a first beam splitter, a first phase shifter, and a first optical antenna. Silicon dioxide is deposited on the SOI substrate on which the first device layer is formed to form a third spacer layer, and the third spacer layer covers the first device layer. A silicon nitride material layer is formed on the third spacer layer, and then the silicon nitride material layer is patterned to form a second device layer. The second device layer includes a second coupler, a second beam splitter, a second phase shifter, and a second optical antenna. When the optical devices in the first device layer are combined with the optical devices in the second device layer, at least part of a third interlayer coupler, a third beam splitter, a third phase shifter, and a third optical antenna are formed.

17. According to the preparation method described in claim 12, wherein, It further includes: Above the optical device layer, a window is formed using a transparent material with a thermal conductivity less than 100 W / (m·K).

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