WO2022161413A1 - Optical module and manufacturing method for silicon optical chip - Google Patents

Abstract

An optical module (200), comprising a circuit board (300) and a silicon optical chip (400) electrically connected to the circuit board (300). The silicon optical chip (400) comprises a silicon substrate (410), an optical coupler (430) provided on the silicon substrate (410), input waveguides (440), coupling waveguides (450), a PN-type doped region (460), a Ge absorption region (4603), and metal electrodes (470, 480). The input waveguides (440) are provided on the silicon substrate (410) and are connected to an output end of the optical coupler (430). The coupling waveguides (450) are provided below the input waveguides (440) and are connected to output ends of the input waveguides (440), and the thickness of each coupling waveguide (450) is less than that of each input waveguide (440). The PN-type doped region (460) is provided on the coupling waveguides (450) and is connected to the coupling waveguides (450). The Ge absorption region (4603) is provided in the PN-type doped region (460), is connected to the PN-type doped region (460), and is used for absorbing a transmitted optical signal and converting the optical signal to an electrical signal. The metal electrodes (470, 480) are provided on the silicon substrate (410), are in contact with the PN-type doped region (460), and are configured to transmit electrical signals.

Description

Optical module and manufacturing method of silicon optical chip

The present disclosure claims priority of application No. 202110118787.1 filed with the China Patent Office on Jan. 28, 2021, the entire contents of which are incorporated herein by reference.

technical field

The present disclosure relates to the technical field of optical communication, and in particular, to a manufacturing method of an optical module and a silicon optical chip.

Background technique

With the development of new business and application models such as cloud computing, mobile Internet, and video, the development and progress of optical communication technology has become more and more important. In the optical communication technology, the optical module is a tool for realizing the mutual conversion of photoelectric signals, and it is one of the key components in the optical communication equipment. With the development of the optical communication technology, the transmission rate of the optical module continues to increase.

Silicon photonics integration technology, which can integrate modulators, detectors, and passive waveguide devices in the same SOI chip, has been widely used in the field of optical communications because of its advantages of being compatible with CMOS, high integration, and low cost. With the development and construction of data centers, high-speed and high-capacity silicon photonics integration technology has received extensive attention, and has huge application scenarios in the field of data communication, especially in high-density packaging integration.

SUMMARY OF THE INVENTION

In a first aspect, some embodiments of the present disclosure disclose an optical module. The optical module includes: a circuit board and a silicon photonics chip. The silicon photonic chip is electrically connected to the circuit board, and is configured to receive the signal light transmitted by the optical fiber and perform electro-optical conversion on the signal light. The silicon optical chip includes: a silicon substrate, an optical coupler, an input waveguide, a coupling waveguide, a PN type doped region, a Ge absorption region and a metal electrode. The optical coupler is arranged on the silicon substrate, and is configured to couple the signal light transmitted by the optical fiber to the silicon optical chip; the input waveguide is arranged on the silicon substrate and is connected to the optical fiber. The output end of the coupler is electrically connected, and is configured to transmit the optical signal received by the optical coupler; the coupling waveguide is arranged under the input waveguide, is electrically connected with the output end of the input waveguide, and has a thickness smaller than the thickness dimension of the input waveguide; the coupling waveguide is configured to transmit the optical signal output by the input waveguide; the PN-type doped region is disposed on the coupling waveguide, is connected to the coupling waveguide, and is configured In order to receive the optical signal transmitted by the coupling waveguide; the Ge absorption region is disposed on the PN-type doped region, is electrically connected to the PN-type doped region, and is configured to absorb the transmitted optical signal and absorb the The optical signal is converted into an electrical signal; the metal electrode is disposed on the silicon substrate, is in contact with the PN-type doped region, and is configured to transmit the electrical signal.

In a second aspect, some embodiments of the present disclosure further provide a method for fabricating a silicon photonics chip. The method includes: providing a silicon substrate; fabricating an input waveguide on the silicon substrate; fabricating an optical coupler at the input end of the input waveguide and fabricating a coupling waveguide at the output end; fabricating a P-type on the coupling waveguide , N-type doped regions; Ge absorption regions are made in the P-type and N-type doped regions; N-region metal electrodes and P-region metal electrodes are set on the silicon substrate, and the N-region metal electrodes and the N-region metal electrodes The P-type doped region is in contact, and the P-region metal electrode is in contact with the P-type doped region.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present disclosure.

Description of drawings

In order to illustrate the technical solutions in the present disclosure more clearly, the following briefly introduces the accompanying drawings that need to be used in some embodiments of the present disclosure. Obviously, the accompanying drawings in the following description are only the appendixes of some embodiments of the present disclosure. For those of ordinary skill in the art, other drawings can also be obtained from these drawings. In addition, the accompanying drawings in the following description may be regarded as schematic diagrams, and are not intended to limit the actual size of the product involved in the embodiments of the present disclosure, the actual flow of the method, the actual timing of signals, and the like.

FIG. 1 is a connection diagram of an optical communication system according to some embodiments;

FIG. 2 is a structural diagram of an optical network terminal according to some embodiments;

3 is a structural diagram of an optical module according to some embodiments;

4 is an exploded view of an optical module according to some embodiments;

5 is a schematic structural diagram of a silicon photonics chip in an optical module according to some embodiments;

6 is a schematic cross-sectional structure diagram of an optical module according to some embodiments;

7 is a flowchart of a method for fabricating a silicon photonics chip in an optical module according to some embodiments;

8 is a process flow diagram of a manufacturing process of a silicon photonics chip in an optical module according to some embodiments;

9 is a flow chart of another fabrication process of a silicon photonics chip in an optical module according to some embodiments;

10 is another schematic structural diagram of a silicon photonics chip in an optical module according to some embodiments;

FIG. 11 is still another schematic structural diagram of a silicon photonics chip in an optical module according to some embodiments.

Detailed ways

The technical solutions in some embodiments of the present disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present disclosure, but not all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments provided by the present disclosure fall within the protection scope of the present disclosure.

Unless the context otherwise requires, throughout the specification and claims, the term "comprise" and its other forms such as the third person singular "comprises" and the present participle "comprising" are used It is interpreted as the meaning of openness and inclusion, that is, "including, but not limited to". In the description of the specification, the terms "one embodiment", "some embodiments", "exemplary embodiments", "example", "specific example" example)" or "some examples" and the like are intended to indicate that a particular feature, structure, material or characteristic related to the embodiment or example is included in at least one embodiment or example of the present disclosure. The schematic representations of the above terms are not necessarily referring to the same embodiment or example. Furthermore, the particular features, structures, materials or characteristics described may be included in any suitable manner in any one or more embodiments or examples.

Hereinafter, 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 number of indicated technical features. Thus, a feature defined as "first" or "second" may expressly or implicitly include one or more of that feature. In the description of the embodiments of the present disclosure, unless otherwise specified, "plurality" means two or more.

In describing some embodiments, the expressions "coupled" and "connected" and their derivatives may be used. For example, the term "connected" may be used in describing some embodiments to indicate that two or more components are in direct physical or electrical contact with each other. As another example, the term "coupled" may be used in describing some embodiments to indicate that two or more components are in direct physical or electrical contact. However, the terms "coupled" or "communicatively coupled" may also mean that two or more components are not in direct contact with each other, yet still co-operate or interact with each other. The embodiments disclosed herein are not necessarily limited by the content herein.

"At least one of A, B, and C" has the same meaning as "at least one of A, B, or C", and both include the following combinations of A, B, and C: A only, B only, C only, A and B , A and C, B and C, and A, B, and C.

"A and/or B" includes the following three combinations: A only, B only, and a combination of A and B.

The use of "adapted to" or "configured to" herein means open and inclusive language that does not preclude devices adapted or configured to perform additional tasks or steps.

As used herein, "about", "approximately" or "approximately" includes the stated value as well as the average value within an acceptable deviation of the specified value, as described by one of ordinary skill in the art Determined taking into account the measurement in question and the errors associated with the measurement of a particular quantity (ie, limitations of the measurement system).

In optical communication technology, light is used to carry the information to be transmitted, and the optical signal carrying the information is transmitted to information processing equipment such as computers through information transmission equipment such as optical fibers or optical waveguides to complete the transmission of information. Since optical signals have passive transmission characteristics when transmitted through optical fibers or optical waveguides, low-cost and low-loss information transmission can be achieved. In addition, the signals transmitted by information transmission equipment such as optical fibers or optical waveguides are optical signals, while the signals that can be recognized and processed by information processing equipment such as computers are electrical signals. To establish an information connection between them, it is necessary to realize the mutual conversion of electrical signals and optical signals.

The optical module realizes the mutual conversion function of the above-mentioned optical signal and electrical signal in the technical field of optical fiber communication. The optical module includes an optical port and an electrical port. The optical module realizes optical communication with information transmission equipment such as optical fibers or optical waveguides through the optical port, and realizes electrical connection with an optical network terminal (for example, an optical cat) through the electrical port. It is mainly used to realize power supply, I2C signal transmission, data signal transmission and grounding; optical network terminals transmit electrical signals to information processing equipment such as computers through network cables or wireless fidelity technology (Wi-Fi).

FIG. 1 is a connection diagram of an optical communication system according to some embodiments. As shown in FIG. 1 , the optical communication system mainly includes a remote server 1000, a local information processing device 2000, an optical network terminal 100, an optical module 200, an optical fiber 101 and a network cable 103;

One end of the optical fiber 101 is connected to the remote server 1000 , and the other end is connected to the optical network terminal 100 through the optical module 200 . The optical fiber itself can support long-distance signal transmission, such as signal transmission of several kilometers (6 kilometers to 8 kilometers). On this basis, if repeaters are used, ultra-long distance transmission can theoretically be achieved. Therefore, in a common optical communication system, the distance between the remote server 1000 and the optical network terminal 100 can usually reach several kilometers, tens of kilometers or hundreds of kilometers.

One end of the network cable 103 is connected to the local information processing device 2000 , and the other end is connected to the optical network terminal 100 . The local information processing device 2000 may be any one or more of the following devices: a router, a switch, a computer, a mobile phone, a tablet computer, a television, and the like.

The physical distance between the remote server 1000 and the optical network terminal 100 is greater than the physical distance between the local information processing device 2000 and the optical network terminal 100 . The connection between the local information processing device 2000 and the remote server 1000 is completed by the optical fiber 101 and the network cable 103 ; and the connection between the optical fiber 101 and the network cable 103 is completed by the optical module 200 and the optical network terminal 100 .

The optical module 200 includes an optical port and an electrical port. The optical port is configured to be connected to the optical fiber 101, so that the optical module 200 and the optical fiber 101 can establish a two-way optical signal connection; electrical signal connection. The optical module 200 realizes the mutual conversion of optical signals and electrical signals, so as to establish a connection between the optical fiber 101 and the optical network terminal 100 . For example, the optical signal from the optical fiber 101 is converted into an electrical signal by the optical module 200 and then input into the optical network terminal 100 , and the electrical signal from the optical network terminal 100 is converted into an optical signal by the optical module 200 and input into the optical fiber 101 .

The optical network terminal 100 includes a substantially rectangular housing, and an optical module interface 102 and a network cable interface 104 disposed on the housing. The optical module interface 102 is configured to access the optical module 200, so that the optical network terminal 100 and the optical module 200 can establish a bidirectional electrical signal connection; the network cable interface 104 is configured to access the network cable 103, so that the optical network terminal 100 and the network cable 103 are connected. Establish a two-way electrical signal connection. A connection is established between the optical module 200 and the network cable 103 through the optical network terminal 100 . For example, the optical network terminal 100 transmits the electrical signal from the optical module 200 to the network cable 103, and transmits the signal from the network cable 103 to the optical module 200. Therefore, the optical network terminal 100, as the host computer of the optical module 200, can monitor the optical module 200. work. In addition to the optical network terminal 100, the host computer of the optical module 200 may also include an optical line terminal (Optical Line Terminal, OLT) and the like.

A bidirectional signal transmission channel is established between the remote server 1000 and the local information processing device 2000 through the optical fiber 101 , the optical module 200 , the optical network terminal 100 and the network cable 103 .

FIG. 2 is a structural diagram of an optical network terminal according to some embodiments. In order to clearly show the connection relationship between the optical module 200 and the optical network terminal 100 , FIG. 2 only shows the optical network terminal 100 related to the optical module 200 . structure. As shown in FIG. 2 , the optical network terminal 100 further includes a PCB circuit board 105 disposed in the housing, a cage 106 disposed on the surface of the PCB circuit board 105 , and an electrical connector disposed inside the cage 106 . The electrical connector is configured to be connected to the electrical port of the optical module 200 ; the heat sink 107 has protrusions such as fins that increase the heat dissipation area.

The optical module 200 is inserted into the cage 106 of the optical network terminal 100 , and the optical module 200 is fixed by the cage 106 . After the optical module 200 is inserted into the cage 106 , the electrical port of the optical module 200 is connected to the electrical connector inside the cage 106 , so that the optical module 200 and the optical network terminal 100 establish a bidirectional electrical signal connection. In addition, the optical port of the optical module 200 is connected to the optical fiber 101 , so that the optical module 200 and the optical fiber 101 establish a bidirectional electrical signal connection.

FIG. 3 is a structural diagram of an optical module according to some embodiments, and FIG. 4 is an exploded view of an optical module according to some embodiments. As shown in FIGS. 3 and 4 , the optical module 200 according to some embodiments includes an upper casing 201 , a lower casing 202 , an unlocking part 203 , a circuit board 300 and a silicon photonics chip 400 .

The casing includes an upper casing 201 and a lower casing 202. The upper casing 201 is covered on the lower casing 202 to form the above casing with two openings 204 and 205; the outer contour of the casing generally presents a square body.

In some embodiments of the present disclosure, the lower casing 202 includes a bottom plate and two lower side plates located on both sides of the bottom plate and perpendicular to the bottom plate; the upper casing 201 includes a cover plate, and two sides of the cover plate are perpendicular to the cover plate. The two upper side plates are combined with the two side plates by the two side walls to realize that the upper casing 201 is covered on the lower casing 202 .

The direction of the connection between the two openings 204 and 205 may be consistent with the length direction of the optical module 200 , or may be inconsistent with the length direction of the optical module 200 . Illustratively, the opening 204 is located at the end of the optical module 200 (the right end in FIG. 3 ), and the opening 205 is also located at the end of the optical module 200 (the left end in FIG. 3 ). Alternatively, the opening 204 is located at the end of the optical module 200 , and the opening 205 is located at the side of the optical module 200 . The opening 204 is an electrical port, and the golden fingers of the circuit board 300 protrude from the electrical port 204 and are inserted into the host computer (such as the optical network terminal 100 ); The optical fiber 101 is connected to the optical transceiver device inside the optical module 200 .

The combination of the upper case 201 and the lower case 202 is used to facilitate the installation of the circuit board 300, optical transceivers and other devices into the case, and the upper case 201 and the lower case 202 can form encapsulation protection for these devices. In addition, when assembling components such as the circuit board 300, it is convenient to deploy the positioning components, heat dissipation components and electromagnetic shielding components of these components, which is conducive to the implementation of automated production.

In some embodiments, the upper casing 201 and the lower casing 202 are generally made of metal material, which is beneficial to achieve electromagnetic shielding and heat dissipation.

In some embodiments, the optical module 200 further includes an unlocking component 203 located on the outer wall of the housing thereof, and the unlocking component 203 is configured to realize a fixed connection between the optical module 200 and the upper computer, or release the connection between the optical module 200 and the upper computer fixed connection.

For example, the unlocking components 203 are located on the outer walls of the two lower side panels 2022 of the lower casing 202, and include engaging components matching with the cage of the upper computer (eg, the cage 106 of the optical network terminal 100). When the optical module 200 is inserted into the cage of the upper computer, the optical module 200 is fixed in the cage of the upper computer by the engaging part of the unlocking part 203; when the unlocking part 203 is pulled, the engaging part of the unlocking part 203 moves accordingly, thereby changing the The connection relationship between the engaging member and the host computer is used to release the engaging relationship between the optical module 200 and the host computer, so that the optical module 200 can be pulled out from the cage of the host computer.

The circuit board 300 includes circuit traces, electronic components and chips, and the electronic components and chips are connected together according to the circuit design through the circuit traces to realize functions such as power supply, electrical signal transmission, and grounding. The electronic components may include, for example, capacitors, resistors, triodes, and metal-oxide-semiconductor field-effect transistors (Metal-Oxide-Semiconductor Field-Effect Transistor, MOSFET). The chip may include, for example, a Microcontroller Unit (MCU), a limiting amplifier (limiting amplifier), a clock and data recovery chip (Clock and Data Recovery, CDR), a power management chip, and a digital signal processing (Digital Signal Processing, DSP) chip .

The circuit board 300 is generally a rigid circuit board. Due to its relatively hard material, the rigid circuit board can also realize the bearing function. For example, the rigid circuit board can carry chips smoothly; the rigid circuit board can also be inserted into the electrical connector in the upper computer cage. .

The circuit board 300 further includes a gold finger 301 formed on the end surface thereof, and the gold finger 301 is composed of a plurality of pins which are independent of each other. The circuit board 300 is inserted into the cage 106 , and the gold fingers 301 are electrically connected to the electrical connectors in the cage 106 . The golden fingers 301 can be arranged only on the surface of one side of the circuit board 300 (eg, the upper surface shown in FIG. 4 ), or can be arranged on the upper and lower surfaces of the circuit board 300 to meet the needs of large number of pins. The golden finger 301 is configured to establish an electrical connection with the upper computer, so as to realize power supply, grounding, I2C signal transmission, data signal transmission, and the like. Of course, flexible circuit boards are also used in some optical modules. Flexible circuit boards are generally used in conjunction with rigid circuit boards as a supplement to rigid circuit boards.

Silicon photonics integration technology enables the integration of modulators, detectors, and passive waveguide devices in the same SOI (silicon-on-insulator) chip because of its CMOS compatibility, high integration, and low cost advantages in optical It has been widely used in the field of communication. In recent years, with the development and construction of data centers, high-speed and high-capacity silicon photonics integration technology has received extensive attention, and has huge application prospects in the field of data communication, especially in high-density packaging integration. In the next generation of high-speed optoelectronic integrated chips, a single-wavelength transmission capacity of 200Gbps can be achieved, and the device bandwidth is required to be greater than 70GHz. In the current silicon photonics integrated chips, Ge/Si high-speed detectors can achieve 1A/W responsivity and 3dB modulation bandwidth of 40GHz, which cannot meet the application requirements of the next generation greater than or equal to 200Gbps for a single wave.

In order to solve the above problems, an embodiment of the present disclosure provides an optical module, which is based on a silicon photonics integration platform and integrates an optical coupler, an input waveguide, a coupling waveguide, a PN-type doped region, a Ge The absorption region and the metal electrode, the input waveguide and the coupling waveguide are located on the upper and lower layers, and the PN-type doped region is fabricated on the coupling waveguide, so that the thickness of the Ge absorption region can be reduced, and the optical modulation bandwidth and high optical responsivity of the optical module can be realized. complex waveguide process.

FIG. 5 is a schematic structural diagram of a silicon photonic chip in an optical module according to some embodiments, and FIG. 6 is a schematic cross-sectional structural schematic diagram of an optical module according to some embodiments. As shown in FIGS. 5 and 6 , the silicon photonics chip 400 according to some embodiments includes a silicon substrate 410 and a SiO ₂ layer 420 , and the SiO ₂ layer 420 is disposed above the silicon substrate 410 to facilitate the connection between the silicon substrate 410 and the SiO 2 layer 420 . Etching is performed on the _SiO2 layer 420, thereby realizing the reception of signal light.

On the silicon photonic chip 400 formed by the silicon substrate 410 and the _SiO2 layer 420, an optical coupler 430, an input waveguide 440, a coupling waveguide 450, a PN-type doped region 460, a Ge absorption region 4603 and a metal electrode are provided, and the optical coupler 430 is provided On one side of the silicon substrate 410 , the signal light transmitted by the optical fiber 101 is coupled to the silicon photonic chip 400 . In some embodiments of the present disclosure, an optical fiber adapter is provided between the silicon optical chip 400 and the optical fiber 101 , one end of the optical fiber adapter is connected with the optical fiber 101 , and the other end is connected with the optical coupler 430 on the silicon optical chip 400 , and the optical fiber adapter is connected through the optical fiber. The adapter optically couples the signal transmitted by the optical fiber 101 into the optical coupler 430 . In the embodiment of the present disclosure, the optical coupler 430 may be a grating coupler, an end-face coupler, or other optical coupling devices.

The input end of the input waveguide 440 is connected to the output end of the optical coupler 430 , and the signal light received by the optical coupler 430 is transmitted through the input waveguide 440 in the silicon optical chip 400 . In the embodiment of the present disclosure, the input waveguide 440 adopts a multi-layer or multi-layer vertical waveguide structure design, and uses a tapered adiabatic waveguide design, that is, the width of the input end of the input waveguide 440 is greater than the width of the output end, so that the output end of the input waveguide 440 is designed. Tapered to optically couple high-speed optical signals into the coupling waveguide 450 from the outside in the silicon photonic chip 400 or into the optical fiber 101 .

The input waveguide 440 is located in the direction of the optical signal receiving optical path, and the distance between the boundary on both sides of the input waveguide 440 at the connection with the coupling waveguide 450 from the centerline gradually decreases, thereby forming a tapered structure, and the refractive index remains unchanged. Based on the coupling film theory, when an optical waveguide with a smaller core size is coupled into an optical waveguide with a larger core size, the coupling efficiency can reach 100%. The high-speed optical signal from the outside or in the optical fiber is coupled into the lower thin coupling waveguide 450 for transmission.

The coupling waveguide 450 is arranged below the input waveguide 440, and the input end of the coupling waveguide 450 is connected to the output end of the input waveguide 440. The width dimension of the input end of the coupling waveguide 450 is larger than the width dimension of the output end of the input waveguide 440, so that the input waveguide 440 transmits the The optical signals can all be transmitted into the coupling waveguide 450 . In the embodiment of the present disclosure, the coupling waveguide 450 and the input waveguide 440 are disposed on the upper and lower layers, the coupling waveguide 450 is located on the upper layer of the input waveguide 440, the thickness dimension of the coupling waveguide 450 is smaller than the thickness dimension of the input waveguide 440, and the input waveguide 440, the coupling waveguide 450 The thickness dimension at the junction is the same as the thickness dimension at the input end of the input waveguide 440 .

On the silicon photonics integration platform, the thickness dimension of the input end of the input waveguide 440 is generally 220 nm, and the thickness dimension of the connection between the input waveguide 440 and the coupling waveguide 450 is the same as the thickness dimension of the input end of the input waveguide 440, so the thickness dimension of the coupling waveguide 450 is less than 220 nm , can be 90nm, or 130nm.

The PN-type doped region 460 is disposed on the coupling waveguide 450 and is electrically connected to the coupling waveguide 450 . In some embodiments of the present disclosure, the side of the thinner coupling waveguide 450 away from the input waveguide 440 may be a square waveguide, and the PN-type doped region 460 is placed on the square waveguide, and the PN-type doped region 460 includes N Type lightly doped region 4601 and P-type lightly doped region 4604, N-type lightly doped region 4601 and P-type lightly doped region 4604 are arranged in sequence along the direction of the light receiving optical path. That is, P-type and N-type ions are respectively doped in the square waveguide region on one side of the coupling waveguide 450 to form the P-type and N-type regions of the detector. They can be spaced apart by a certain distance, as long as a PN structure can be formed.

In the embodiment of the present disclosure, P-type and N-type ions are doped in the square waveguide region on one side of the coupling waveguide 450 along the width direction of the silicon photonic chip 400 , so that the input waveguide 440 couples the high-speed optical signal into the coupling waveguide 450 During transmission, when the optical signal is transmitted to the square waveguide region, the N-type lightly doped region 4601 and the P-type lightly doped region 4604 cause ions to move after receiving the optical signal.

The Ge absorption region 4603 is disposed on the PN-type doped region 460 and is electrically connected to the PN-type doped region 460 for absorbing the transmitted optical signal and converting the optical signal into an electrical signal. In some embodiments of the present disclosure, the Ge absorption region 4603 is disposed above the N-type lightly doped region 4601 and the P-type lightly doped region 4604 , and the Ge absorption region 4603 is respectively connected to the N-type lightly doped region 4601 and the P-type lightly doped region 4601 and P-type Lightly doped regions 4604 are electrically connected. That is, a Ge thin film is selectively generated above the N-type lightly doped region 4601 and the P-type lightly doped region 4604 as the light absorption region of the detector, and when the optical signal passes through the N-type lightly doped region 4601 and the P-type lightly doped region 4604 , will be absorbed by the Ge absorption region 4603 to generate electron-hole pairs, and these photo-generated carriers will move to the electrodes on both sides under the action of the electric field, thereby forming a photo-generated current. The cross-sectional shape of the Ge thin film is triangular or trapezoidal according to the crystal growth angle requirements, so that the width of the Ge absorption region 4603 can be reduced, so that under the N-type lightly doped region 4601 and the P-type lightly doped region 4604, the Ge absorption A strong electric field strength is formed inside the region 4603, which increases the moving speed of the ions, thereby realizing a modulation bandwidth greater than 100 GHz.

When the thickness of the Ge absorption region 4603 is higher, the absorption rate of the ions in the Ge absorption region 4603 is lower, resulting in a lower modulation bandwidth; when the thickness of the Ge absorption region 4603 is lower, the absorption rate of the ions in the Ge absorption region 4603 The rate is higher, resulting in a higher modulation bandwidth. In the embodiment of the present disclosure, the Ge absorbing region 4603 is placed on the upper layer of the coupling waveguide 450 and the PN-type doped region 460, which can reduce the thickness of the Ge absorbing region 4603, thereby increasing the modulation bandwidth of the Ge absorbing region 4603 and achieving modulation greater than 100 GHz bandwidth.

In addition, due to the small thickness of the coupling waveguide 450, the effective refractive index of the waveguide in the Ge absorption region 4603 is larger than that of the coupling waveguide 450, and under evanescent wave coupling, most of the optical field can be coupled into the Ge absorption region 4603 The detection absorption is carried out in , so high photoresponsivity can be achieved.

In the embodiment of the present disclosure, the connection width between the Ge absorption region 4603 and the N-type lightly doped region 4601 and the connection width between the Ge absorption region 4603 and the P-type lightly doped region 4604 may be the same, that is, the central axis of the Ge absorption region 4603 is the same as the The connection between the N-type lightly doped region 4601 and the P-type lightly doped region 4604 coincide; the connection width of the Ge absorption region 4603 and the N-type lightly doped region 4601, the connection between the Ge absorption region 4603 and the P-type lightly doped region 4604 The width can also be different, for example, the connection width between the Ge absorption region 4603 and the N-type lightly doped region 4601 is larger than the connection width between the Ge absorption region 4603 and the P-type lightly doped region 4604, and the Ge absorption region 4603 and the N-type lightly doped region 4601. The connection width is smaller than the connection width between the Ge absorption region 4603 and the P-type lightly doped region 4604 . In the embodiment of the present disclosure, the width of the Ge absorption region 4603 is very small, which may be 1 micrometer.

When the optical signal transmitted by the coupling waveguide 450 enters the N-type lightly doped region 4601 and the P-type lightly doped region 4604 of the PN-type doped region 460 , electrical currents in the N-type lightly doped region 4601 and the P-type lightly doped region 4604 are induced. Ion movement, under the movement of ions in the N-type lightly doped region 4601 and the P-type lightly doped region 4604, the Ge absorption region 4603 absorbs the optical signal transmitted by the coupling waveguide 450, and a strong electric field is formed inside the Ge absorption region 4603 Intensity, while realizing the functions of high modulation bandwidth and high photoresponsivity.

In the embodiment of the present disclosure, the N-type lightly doped region 4601 of the PN-type doped region 460 is provided with an N-type heavily doped region 4602, and the P-type lightly doped region 4604 is provided with a P-type heavily doped region 4605. Both the N-type heavily doped region 4602 and the P-type heavily doped region 4605 are far away from the Ge absorption region. The silicon substrate 410 is also provided with a metal electrode, the metal electrode includes an N-region metal electrode and a P-region metal electrode, the N-region metal electrode is in contact with the N-type heavily doped region 4602, and the P-region metal electrode is heavily doped with the P-type region. The regions 4605 are in contact, so that electrical signals are transmitted through the N-region metal electrodes and the P-region metal electrodes.

Based on the optical module described in the above embodiments, an embodiment of the present disclosure further provides a method for fabricating a silicon photonics chip in an optical module. FIG. 7 is a flowchart of a manufacturing method of a silicon photonics chip according to some embodiments, and FIG. 8 is a flowchart of a manufacturing process of a silicon photonics chip according to some embodiments. As shown in FIG. 7 , the method for fabricating a silicon photonics chip according to some embodiments includes S100 to S600.

S100: Provide a silicon substrate.

As shown in FIG. 8 , the silicon substrate 410 and the SiO ₂ layer 420 are arranged together according to the upper and lower layers, that is, the SiO ₂ layer 420 is placed on the upper layer of the silicon substrate 410 . In some embodiments of the present disclosure, SiO ₂ is deposited on the surface of the silicon substrate 410 to form a SiO ₂ layer 420 ; then Si is deposited on the surface of the SiO ₂ layer 420 to form a silicon layer. The SiO ₂ layer 420 can be grown on the surface of the silicon substrate 410 by a two-step chemical vapor deposition method of low temperature and high temperature respectively, and a silicon layer can be grown on the surface of the SiO ₂ layer 420 by chemical vapor deposition to form a standard thickness. SOI wafers. The specific thicknesses of the SiO ₂ layer 420 and the silicon layer can be selected by those skilled in the art according to actual needs.

S200: Fabricate an input waveguide on a silicon substrate.

The silicon layer is etched to form the input waveguide 440, and the output end of the input waveguide 440 adopts a tapered adiabatic waveguide structure.

S300 : fabricating an optical coupler at the input end of the input waveguide, and fabricating a coupling waveguide at the output end.

After the input waveguide 440 is formed by etching, the optical coupler 430 and the coupling waveguide 450 are respectively etched on the SiO ₂ layer 420. One end of the coupling waveguide 450 is a strip waveguide and the other end is a square waveguide. The coupling waveguide 450 is located in the lower layer of the input waveguide 440. On the SiO ₂ layer 420 , the output end of the optical coupler 430 is connected with the input end of the input waveguide 440 , and the output end of the input waveguide 440 is connected with the input end of the coupling waveguide 450 .

S400 : forming P-type and N-type doped regions on the coupled waveguide.

N-type ions and P-type ions are respectively implanted on both sides of the square waveguide region of the etched coupling waveguide 450 to form N-type lightly doped regions 4601, N-type heavily doped regions 4602, P-type lightly doped regions 4604 and P-type ions Type heavily doped region 4605. The N-type heavily doped region 4602 is formed in the N-type lightly doped region 4601, the P-type heavily doped region 4605 is formed in the P-type lightly doped region 4604, and the N-type lightly doped region 4601 and the P-type lightly doped region 4601 are formed. The regions 4604 can be connected and distributed symmetrically in the center, or can be spaced apart by a certain distance, as long as a PN structure can be formed.

S500 : forming a Ge absorption region in the P-type and N-type doped regions.

A selective epitaxial growth method can be used to grow a Ge absorption region 4603 on the N-type lightly doped region 4601 and the P-type lightly doped region 4604. The cross-sectional shape of the Ge absorption region 4603 is triangular or trapezoidal according to the crystal growth angle. The thickness and width of the Ge absorption region 4603 can be set according to actual conditions.

S600 : setting an N-region metal electrode and a P-region metal electrode on the silicon substrate, the N-region metal electrode is in contact with the N-type doping region, and the P-region metal electrode is in contact with the P-type doping region.

A first conductive material is deposited on the surface of the _SiO2 layer 420 to form an N-region metal electrode 470, which is in contact with the N-type heavily doped region 4602; a second conductive material is deposited on the surface of the _SiO2 layer 420, A P-region metal electrode 480 is formed, and the P-region metal electrode 480 is in contact with the P-type heavily doped region 4605 to realize electrical signal transmission.

FIG. 9 is a process flow diagram of another silicon photonics chip according to some embodiments. As shown in FIG. 9 , the silicon photonics chip according to some embodiments can also be fabricated by another fabrication method, and the fabrication process is as follows:

SiO2 is deposited on the surface of the silicon substrate 410 by chemical vapor deposition to form a _SiO2 layer 420; then Si is deposited on the surface of the _SiO2 layer 420 by chemical vapor deposition to form a silicon layer; then on the silicon layer, The coupling waveguide 450 is etched on the _SiO2 layer 420, and one end of the coupling waveguide 450 is a strip waveguide and the other end is a square waveguide; then N-type ions and P-type ions are injected into the square waveguide region on both sides respectively to form N-type lightly doped Region 4601, N-type heavily doped region 4602, P-type lightly doped region 4604 and P-type heavily doped region 4605, N-type heavily doped region 4602 is formed in N-type lightly doped region 4601, P-type heavily doped region The region 4605 is formed in the P-type lightly doped region 4604, and the N-type lightly doped region 4601 and the P-type lightly doped region 4604 can be connected in a center-symmetric distribution, or can be separated by a certain distance, as long as a PN structure can be formed Then, a selective epitaxial growth method can be used to grow a Ge absorption region 4603 on the N-type lightly doped region 4601 and the P-type lightly doped region 4604. The cross-sectional shape of the Ge absorption region 4603 is a triangle or a triangle according to the crystal growth angle. Then, the input waveguide 440 and the optical coupler 430 are formed by etching on the silicon layer, the input end of the input waveguide 440 is connected with the output end of the optical coupler 430, and the output end of the input waveguide 440 adopts a tapered adiabatic waveguide structure, and Connect with the strip waveguide of the coupling waveguide 450; then deposit a first conductive material on the surface of the SiO ₂ layer 420 to form an N-region metal electrode 470, which is in contact with the N-type heavily doped region 4602; A second conductive material is deposited on the surface of the SiO ₂ layer 420 to form a P-region metal electrode 480 , and the P-region metal electrode 480 is in contact with the P-type heavily doped region 4605 to realize electrical signal transmission.

The optical module according to some embodiments is based on a silicon photonics integration platform. The upper and lower layers of the input waveguide and the coupling waveguide are arranged, and the Ge absorption region is arranged above the coupling waveguide with a smaller thickness, which can reduce the thickness of the Ge absorption region and improve the absorption of electrons in the Ge. In addition, due to the small thickness of the coupling waveguide, the effective refractive index of the waveguide in the Ge absorption region is larger than that of the coupling waveguide, which can couple most of the optical field into the Ge absorption region. The detection absorption is carried out in , so high photoresponsivity can be achieved. The present disclosure can achieve high modulation bandwidth and high photoresponsivity at the same time through special waveguide structure and Ge detector design, and does not require additional complicated processes.

FIG. 10 is another schematic structural diagram of a silicon photonics chip 400 in an optical module according to some embodiments. As shown in FIG. 10 , in order to further increase the stability of the silicon photonic chip 400 , the photoresponsivity of the device can also be further improved by means of double-ended input of the Ge detector.

In some embodiments of the present disclosure, the silicon photonic chip 400 is provided with an optical coupler 430 , a first input waveguide 440 , a first coupling waveguide 450 , a second input waveguide 490 , a second coupling waveguide 4110 , and PN-type doping. The region 460 , the Ge absorption region 4603 and the metal electrode, the optical coupler 430 is arranged on one side of the silicon substrate on the silicon photonic chip 400 , and is used for coupling the signal light transmitted by the optical fiber 101 to the silicon photonic chip 400 .

The first input waveguide 440 and the second input waveguide 490 are symmetrically disposed on both sides of the optical coupler 430 , that is, the optical coupler 430 has two output ends, the input end of the first input waveguide 440 and an output end of the optical coupler 430 The input end of the second input waveguide 490 is connected to the other output end of the optical coupler 430, so that the optical coupler 430 divides the received signal light into two, one beam of signal light is transmitted into the first input waveguide 440, and the other is transmitted into the first input waveguide 440. A beam of signal light is transmitted to the second input waveguide 490 .

The output end of the first input waveguide 440 adopts a tapered adiabatic waveguide structure, which is connected to the input end of the first coupling waveguide 450, and the thickness of the first coupling waveguide 450 is smaller than that of the first input waveguide 440; The output end adopts a tapered adiabatic waveguide structure and is connected to the input end of the second coupling waveguide 4110 , and the thickness of the second coupling waveguide 4110 is smaller than that of the second input waveguide 490 .

The thinner first coupling waveguide 450 and the second coupling waveguide 4110 share the same square waveguide region, and the PN-type doped region 460 is placed on the square waveguide region. The PN-type doped region 460 includes the N-type lightly doped region 4601 and the The P-type lightly doped region 4604, the N-type lightly doped region 4601 and the P-type lightly doped region 4604 are arranged in sequence along the direction of the light receiving optical path, and the P-type and N-type doped regions can be connected to form a center-symmetric distribution, or They can be spaced apart by a certain distance, as long as a PN structure can be formed.

The Ge absorption region 4603 is disposed above the N-type lightly doped region 4601 and the P-type lightly doped region 4604, and the Ge absorption region 4603 is electrically connected to the N-type lightly doped region 4601 and the P-type lightly doped region 4604, respectively. The cross-sectional shape of the absorption region 4603 is triangular or trapezoidal according to the crystal growth angle, and the width of the Ge absorption region 4603 is reduced, so that the Ge absorption region can be under the N-type lightly doped region 4601 and the P-type lightly doped region 4604. A strong electric field strength is formed inside 4603, which increases the moving rate of ions, thereby achieving a modulation bandwidth greater than 100 GHz; in addition, due to the small thickness of the coupling waveguide 450, the effective refractive index of the waveguide in the Ge absorption region 4603 is greater than that of the coupling waveguide 450. The effective refractive index, under evanescent wave coupling, can couple most of the light field into the Ge absorption region 4603 for detection and absorption, so high photoresponsivity can be achieved.

According to some embodiments, the Ge detector in the silicon photonics chip adopts a double-ended input method to detect and absorb optical signals, so that the optical signals transmitted by the first coupling waveguide 450 and the second coupling waveguide 4110 are both coupled into the Ge absorption region 4603 for processing. Absorption is detected, so the optical responsivity of the optical module can be further improved.

FIG. 11 is a schematic diagram of a third structure of a silicon photonics chip 400 in an optical module according to some embodiments. As shown in FIG. 11 , multiple Ge detectors can also be integrated in the silicon photonics chip 400 , which are connected to the Ge detectors one by one through multiple input waveguides, so as to realize multi-channel light receiving optical paths in the silicon photonics chip 400 , and simultaneously realize multiple High modulation bandwidth and high optical responsivity at 1 wavelength.

In some embodiments of the present disclosure, the optical module according to some embodiments includes an optical fiber array 500, the optical fiber array 500 may include four optical fibers, and the silicon optical chip 400 integrates four input waveguides 440 and four Ge detectors , one end of each fiber is connected to the input end of an input waveguide 440, and the output end of the input waveguide 440 is connected to a Ge detector, so that the optical signal transmitted by each fiber is transmitted to the Ge detector through the input waveguide 440, The detector converts the optical signal into an electrical signal.

The silicon photonic chip according to some embodiments integrates multiple input waveguides and multiple Ge detectors to simultaneously receive multiple different optical signals and convert multiple different optical signals into multiple different electrical signals.

It should be noted that, in this specification, the terms "comprising", "comprising" or any other variation thereof are intended to cover non-exclusive inclusion, so that a circuit structure, article or device comprising a series of elements includes not only those elements, It also includes other elements not expressly listed, or elements inherent to such a circuit structure, article or device. Without further limitation, an element qualified by the phrase "comprising a..." does not preclude the presence of additional identical elements in the circuit structure, article or device that includes the element.

Other embodiments of the present disclosure will readily suggest themselves to those skilled in the art upon consideration of the specification and practice of the disclosure disclosed herein. This disclosure is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common general knowledge or techniques in the technical field not disclosed by this disclosure . The specification and examples are to be regarded as exemplary only, with the true scope and spirit of the disclosure being indicated by the content of the claims.

The above are only specific embodiments of the present disclosure, but the protection scope of the present disclosure is not limited thereto. Any person skilled in the art who is familiar with the technical scope disclosed in the present disclosure, think of changes or replacements, should cover within the scope of protection of the present disclosure. Therefore, the protection scope of the present disclosure should be based on the protection scope of the claims.

Claims (10)

An optical module, comprising: circuit board; a silicon photonic chip, electrically connected to the circuit board, and configured to receive the signal light transmitted by the optical fiber and perform electro-optical conversion on the signal light; Wherein, the silicon photonics chip includes: silicon substrate; an optical coupler, disposed on the silicon substrate, configured to couple the signal light transmitted by the optical fiber to the silicon optical chip; an input waveguide, disposed on the silicon substrate, connected to the output end of the optocoupler, and configured to transmit the optical signal received by the optocoupler; a coupling waveguide, which is arranged under the input waveguide, is connected to the output end of the input waveguide, and has a thickness smaller than that of the input waveguide; the coupling waveguide is configured to transmit the optical signal output by the input waveguide ; a PN-type doped region, disposed on the coupling waveguide, connected to the coupling waveguide, and configured to receive the optical signal transmitted by the coupling waveguide; A Ge absorption region is disposed on the PN-type doped region, is electrically connected to the PN-type doped region, and is configured to absorb the transmitted optical signal and convert the optical signal into an electrical signal; A metal electrode, disposed on the silicon substrate, in contact with the PN-type doped region, is configured to transmit the electrical signal. The optical module of claim 1, wherein the input waveguide has an input width greater than its output width. The optical module according to claim 1, wherein the thickness of the input waveguide and the connection of the coupling waveguide is the same as the thickness of the input end of the input waveguide. The optical module according to claim 1, wherein the PN-type doped region comprises an N-type lightly doped region and a P-type lightly doped region, the N-type lightly doped region and the P-type lightly doped region The zones are arranged in sequence along the direction of the light receiving optical path; The Ge absorption region is disposed above the N-type lightly doped region and the P-type lightly doped region, and the Ge absorption region is electrically connected to the N-type lightly doped region and the P-type lightly doped region, respectively. The optical module of claim 4, wherein the N-type lightly doped region is connected to the P-type lightly doped region. The optical module according to claim 4, wherein a connection width between the Ge absorption region and the N-type lightly doped region and a connection width between the Ge absorption region and the P-type lightly doped region are the same. The optical module according to claim 1, wherein the cross-sectional shape of the Ge absorption region is a triangle or a trapezoid. The optical module according to claim 4, wherein an N-type heavily doped region is provided in the N-type lightly doped region, a P-type heavily doped region is provided in the P-type lightly doped region, and the Both the N-type heavily doped region and the P-type heavily doped region are far away from the Ge absorption region; The metal electrode includes an N-region metal electrode and a P-region metal electrode, the N-region metal electrode is in contact with the N-type heavily doped region, and the P-region metal electrode is in contact with the P-type heavily doped region . The optical module according to claim 1, wherein the optical coupler is a grating coupler or an end-face coupler. A manufacturing method of a silicon photonics chip, comprising: providing a silicon substrate; fabricating an input waveguide on the silicon substrate; Making an optical coupler at the input end of the input waveguide and making a coupling waveguide at the output end; making P-type and N-type doped regions on the coupling waveguide; forming a Ge absorption region in the P-type and N-type doped regions; An N-region metal electrode and a P-region metal electrode are arranged on the silicon substrate, the N-region metal electrode is in contact with the N-type doped region, and the P-region metal electrode is in contact with the P-type doped region .

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