Flip-chip bonded laser to silicon optical waveguide coupling structure and method

Abstract

The application relates to a flip-chip laser and silicon optical waveguide coupling structure and method, which comprises a silicon substrate, the silicon substrate is provided with a first placing groove, the bottom surface of the silicon substrate is provided with a second placing groove, a step is formed at the joint of the first placing groove and the second placing groove, and solder is placed in the second placing groove; a silicon optical chip is fixed on the silicon substrate and located at one side of the first placing groove, the silicon optical chip is provided with a first waveguide structure; a laser chip is placed in the first placing groove and supported on the step, the laser chip is electrically connected with the silicon substrate through the solder, the laser chip is provided with a second waveguide structure, and the second waveguide structure is coupled with the first waveguide structure. The step is formed by opening two grooves to support the laser chip, accurate coupling alignment can be realized, volatile substances and filling glue can be effectively blocked from polluting the waveguide structure, and the coupling efficiency is improved.

Description

Technical Field

[0001] This application relates to the field of optical communication technology, specifically to a flip-chip bonded laser coupling structure and method with silicon optical waveguide. Background Technology

[0002] Currently, photonic integrated chips are a key technology for high-speed communication systems, enabling the integration of various optical or optoelectronic devices. The integration of lasers and silicon photonic chips is one of the important factors affecting the integration level of photonic integrated chips. Lasers serve as light sources, while silicon itself cannot emit light; therefore, the key lies in how to integrate lasers with silicon photonic chips.

[0003] Among related technologies, there are three main integration techniques for lasers and silicon photonic chips: First, heterogeneous integration, which involves bonding III-V group materials to silicon photonic chips via laser chip bonding, and then fabricating the laser; second, hybrid integration, which involves first fabricating the laser, and then integrating the laser with the silicon photonic chip via flip-chip bonding or external laser connection, so that the waveguide of the laser is coupled with the waveguide of the silicon photonic chip; and third, monolithic integration, which involves directly growing the laser on a silicon substrate via epitaxy.

[0004] Traditional flip-chip bonding coupling methods typically involve placing the laser chip directly onto the solder, electrically connecting the laser chip to the solder, and simultaneously coupling the waveguides of the laser chip and the silicon photonics chip. However, when the laser chip is soldered to the solder, the solder may melt and collapse or deform due to heat. The changes in solder collapse or deformation are generally tens of micrometers, while the waveguides of the laser and silicon photonics chips typically have diameters of only a few micrometers. This makes it difficult to precisely control the height of the waveguides of the laser and silicon photonics chips in the Z-axis direction, thus affecting the coupling accuracy.

[0005] Therefore, it is necessary to design a new flip-chip bonded laser-silicon waveguide coupling structure and method to overcome the above problems. Summary of the Invention

[0006] This application provides a flip-chip bonded laser-silicon photonic waveguide coupling structure and method, which solves the technical problem in related technologies where the height of the waveguide in the Z-axis direction of the laser and silicon photonic chip is difficult to control precisely, thus affecting the coupling accuracy. Furthermore, the steps provided in this application effectively prevent volatile substances such as flux from diffusing to the coupling end face of the laser chip and silicon photonic chip during the flip-chip bonding process, thus preventing contamination of the waveguide structure. It also effectively prevents underfill adhesive from overflowing to the coupling end face of the laser chip and silicon photonic chip during the underfill process based on capillary principle, thereby improving coupling efficiency.

[0007] In a first aspect, embodiments of this application provide a flip-chip bonded laser-silicon waveguide coupling structure, comprising: a silicon substrate having a first placement groove and a second placement groove on the bottom surface of the first placement groove, forming a step at the junction of the first placement groove and the second placement groove, wherein solder is placed in the second placement groove; a silicon photonic chip fixed to the silicon substrate and located on one side of the first placement groove, wherein a first waveguide structure is disposed in the silicon photonic chip; and a laser chip placed in the first placement groove and supported on the step, wherein the laser chip is electrically connected to the silicon substrate through the solder, wherein a second waveguide structure is disposed in the laser chip and coupled to the first waveguide structure.

[0008] In conjunction with the first aspect, in one embodiment, the step includes a first step and a second step supported on opposite sides of the laser chip, the first step being located on the side of the laser chip closer to the silicon photonic chip, and the second step being located on the other side of the laser chip.

[0009] In conjunction with the first aspect, in one embodiment, the first placement slot has a first side and a second side connected to its bottom surface, the first side and the second side being parallel to each other, and the first side being located at the coupling point between the second waveguide structure and the first waveguide structure; the first step is connected to the first side, and the first step extends from one end of the first side to the other end of the first side in a direction parallel to the first side.

[0010] In conjunction with the first aspect, in one embodiment, the second step connects to the second side surface, and the second step extends from one end of the second side surface to the other end of the second side surface in a direction parallel to the second side surface.

[0011] In conjunction with the first aspect, in one embodiment, the silicon substrate further has a third groove on the bottom surface of the first placement groove, the third groove being separated from the second placement groove by the step, and one of the third grooves being located at the coupling point between the second waveguide structure and the first waveguide structure.

[0012] In conjunction with the first aspect, in one embodiment, the first placement slot has a first side and a second side connected to its bottom surface, the first side and the second side being parallel to each other, and the first side being located at the coupling point between the second waveguide structure and the first waveguide structure; the step includes a first step and a second step spaced apart, the first step and one of the third slots being located between the first side and the second placement slot, and the first step extending from one end of the first side to the other end of the first side in a direction parallel to the first side.

[0013] In conjunction with the first aspect, in one embodiment, the second step is located between the second placement groove and the second side, and at least two second steps are provided between the second placement groove and the second side, the at least two second steps being spaced apart along a direction parallel to the second side, so that the third groove located between the second step and the second side is connected to the second placement groove.

[0014] In conjunction with the first aspect, in one embodiment, the distance d between the first step and the first side surface is in the range of 1.5um ≤ d ≤ 4um.

[0015] Secondly, embodiments of this application provide a flip-chip bonding coupling method between a laser and a silicon optical waveguide, which includes the following steps:

[0016] A first placement groove is formed on a silicon substrate, and a second placement groove is formed on the bottom surface of the first placement groove, so that a step is formed at the junction of the first placement groove and the second placement groove.

[0017] Solder is placed in the second placement groove, and a silicon photonic chip is fixed on the silicon substrate, such that the silicon photonic chip is located on one side of the first placement groove, wherein the silicon photonic chip is provided with a first waveguide structure;

[0018] A laser chip is placed in the first placement slot, supported on the step, and electrically connected to the silicon substrate through the solder. At the same time, the second waveguide structure in the laser chip is coupled to the first waveguide structure in the silicon photonic chip.

[0019] In conjunction with the second aspect, in one embodiment, the step of forming a first placement groove on a silicon substrate and forming a second placement groove on the bottom surface of the first placement groove, such that a step is formed at the junction of the first placement groove and the second placement groove, includes:

[0020] The first placement trench and the second placement trench are formed on the silicon substrate using a photolithography mask and plasma etching methods; or...

[0021] The first placement groove and the second placement groove are formed on the silicon substrate using laser micro-nano processing methods.

[0022] The beneficial effects of the technical solutions provided in this application include at least the following:

[0023] By creating two grooves on the silicon substrate, a step is formed at the junction of the first and second placement grooves. This step can support the laser chip, and even if the solder collapses or is deformed by compression, the height of the laser chip in the Z-axis direction will not change. Furthermore, the depth of the first and second placement grooves in the Z-axis direction can be precisely controlled by creating grooves, thereby precisely controlling the height of the step and the laser chip in the Z-axis direction. This achieves precise coupling and alignment between the laser chip and the silicon photonic chip, solving the technical problem in related technologies where the height of the waveguides of the laser and silicon photonic chip in the Z-axis direction is difficult to control precisely, thus affecting the coupling accuracy. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 A schematic diagram of the first flip-chip bonded laser-silicon waveguide coupling structure using a solder ball, provided in the embodiments of this application;

[0026] Figure 2 A schematic diagram of a copper pillar used in the first flip-chip bonded laser-silicon waveguide coupling structure provided in this application embodiment;

[0027] Figure 3 A schematic diagram showing that the side of the first step in the second flip-chip bonded laser-silicon waveguide coupling structure provided in this application embodiment is flush with the second coupling end face of the laser chip in the Z direction;

[0028] Figure 4 A schematic diagram showing that the side of the first step and the second coupling end face of the laser chip are not flush in the Z direction in the second flip-chip bonded laser-silicon waveguide coupling structure provided in the embodiments of this application.

[0029] Figure 5 A schematic diagram of a copper pillar used in the second flip-chip bonded laser-silicon waveguide coupling structure provided in this application embodiment;

[0030] Figure 6 A three-dimensional structural schematic diagram of another flip-bonded laser-silicon waveguide coupling structure provided in this application embodiment.

[0031] In the picture:

[0032] 1. Silicon substrate; 11. First placement groove; 111. First side surface; 112. Second side surface; 113. Bottom surface; 12. Second placement groove;

[0033] 13. Steps; 131. First step; 132. Second step; 14. Third groove;

[0034] 2. Solder; 3. Silicon photonic chip; 31. First waveguide structure;

[0035] 4. Laser chip; 41. Second waveguide structure. Detailed Implementation

[0036] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present application.

[0037] Current laser-to-silicon photonic chip integration technologies suffer from high alignment precision requirements and low coupling efficiency. Therefore, precise and efficient coupling between laser chips and silicon photonic chip waveguides is a critical issue that urgently needs to be addressed.

[0038] This application provides a flip-chip bonded laser-silicon waveguide coupling structure and method, which can solve the technical problem in related technologies where the height of the waveguide of the laser and silicon photonic chip in the Z-axis direction is difficult to control precisely, thus affecting the coupling accuracy.

[0039] See Figure 1 and Figure 2The diagram illustrates a flip-chip bonded laser-silicon waveguide coupling structure according to an embodiment of this application. It includes a silicon substrate 1, with a first placement groove 11 recessed from the surface of the substrate 1. A second placement groove 12 is formed on the bottom surface 113 of the first placement groove 11, creating a step 13 at the junction of the first and second placement grooves. Solder 2 is placed in the second placement groove 12. Specifically, a second placement groove 12 is formed in addition to the first placement groove 11. Both the first and second placement grooves are recessed downwards, with their concave directions aligned. The second placement groove 12 is used to hold the solder 2, which can be a solder ball or a copper ball. Pillar (i.e., copper pillar); silicon photonic chip 3, which is fixed to the silicon substrate 1 and located on one side of the first placement groove 11, the silicon photonic chip 3 is provided with a first waveguide structure 31, and the silicon photonic chip 3 can be fixed to the surface of the silicon substrate 1; laser chip 4, which is placed in the first placement groove 11 and supported by the step 13, the laser chip 4 is electrically connected to the silicon substrate 1 through the solder 2, the laser chip 4 is provided with a second waveguide structure 41, and the second waveguide structure 41 is coupled to the first waveguide structure 31. In this embodiment, after the laser chip 4 is supported on the step 13, the second waveguide structure 41 in the laser chip 4 and the first waveguide structure 31 in the silicon photonic chip 3 are located on the same plane, so that the first waveguide structure 31 and the second waveguide structure 41 can be precisely coupled and aligned.

[0040] The dimensions and precise depths of the first placement groove 11 and the second placement groove 12 can be designed based on the specific chip dimensions. The methods for forming the placement grooves include, but are not limited to, dry etching, wet etching, and laser micro / nano fabrication. The width of the second waveguide structure 41 on the laser chip 4 ranges from 50 nm to 2000 nm, and the height ranges from 200 nm to 3000 nm (including but not limited to); the width of the first waveguide structure 31 on the silicon photonics chip 3 ranges from 300 nm to 1200 nm, and the height ranges from 100 nm to 600 nm (including but not limited to).

[0041] In this embodiment, by creating two slots on the silicon substrate 1, namely a first placement slot 11 and a second placement slot 12, a step 13 is formed at the junction of the first placement slot 11 and the second placement slot 12. This step 13 can support the laser chip 4, fixing the height of the laser chip 4 in the Z-axis direction. Even if the solder 2 collapses or is deformed by compression, the height of the laser chip 4 in the Z-axis direction will not change. Furthermore, by using a conventional and mature slotting method, the depth of the first placement slot 11 and the second placement slot 12 in the Z-axis direction can be precisely controlled, thereby precisely controlling the step 13 and the height of the laser chip 4 in the Z-axis direction. This achieves precise coupling and alignment between the laser chip 4 and the silicon photonic chip 3, with accuracy controllable at the nanometer level. This solves the technical problem in related technologies where the height of the waveguides of the laser and the silicon photonic chip 3 in the Z-axis direction is difficult to control precisely, thus affecting the coupling accuracy.

[0042] Preferred, see Figure 4 As shown, in this embodiment, the vertical height of step 13 along the Z-axis is equal to the depth H of the second placement groove 12, and the length of step 13 along the Y-axis can be greater than the dimension of laser chip 4 along the Y-axis. When the solder 2 placed in the second placement groove 12 is a solder ball, the depth H of the second placement groove 12 is in the range of 1 / 4 of the solder ball's height ≤ H ≤ the height of the solder ball; when the solder 2 placed in the second placement groove 12 is a copper pillar, the depth H of the second placement groove 12 is in the range of 1 / 2 of the copper pillar's solder cap thickness ≤ H ≤ the height of the copper pillar. In this embodiment, the mounting accuracy of laser chip 4 is greater than or equal to 0.2µm.

[0043] See Figure 1 and Figure 2 As shown, in some embodiments, the step 13 includes a first step 131 and a second step 132 supported on opposite sides of the laser chip 4. The first step 131 is located on the side of the laser chip 4 closer to the silicon photonics chip 3, and the second step 132 is located on the other side of the laser chip 4. Figure 1 Taking the positional relationship shown as an example, the first step 131 and the second step 132 are distributed at intervals along the X-axis. The first step 131 is located on the right side of the laser chip 4, and the second step 132 is located on the left side of the laser chip 4. In this embodiment, by setting the first step 131 and the second step 132 on opposite sides of the laser chip 4, the laser chip 4 can be stably supported on opposite sides. The step 13 can be omitted at the middle position directly below the laser chip 4 and at the front and rear positions, which can reduce the impact on the pad area of ​​the laser chip 4.

[0044] In this embodiment, the first step 131 and the second step 132 are spaced apart. Of course, in other embodiments, steps 13 can also be provided on the front and rear edges of the laser chip 4 to support the laser chip 4, and the steps 13 located on the front and rear edges can also be connected to the first step 131 and the second step 132.

[0045] Further, see Figure 1 and Figure 2 As shown, in some optional embodiments, the first placement slot 11 has a first side surface 111 and a second side surface 112 connected to its bottom surface 113. The first side surface 111 and the second side surface 112 are parallel to each other, and the first side surface 111 is located at the coupling point between the second waveguide structure 41 and the first waveguide structure 31. In this embodiment, the silicon photonic chip 3 has a first coupling end face. The first coupling end face can be coplanar with the first side surface 111, or it can be slightly offset from the first side surface 111 in the left-right direction. Preferably, the first coupling end face and the first side surface 111 are set to be coplanar. The first step 131 connects to the first side surface 111, and the first step 131 extends from one end of the first side surface 111 to the other end of the first side surface 111 in a direction parallel to the first side surface 111. That is, in this embodiment, the first step 131 is integrated with the first side surface 111, and the first step 131 extends from one end of the first side surface 111 to the other end along the Y-axis. The first step 131 is provided along the entire length of the first side surface 111. After the laser chip 4 is placed on the first step 131 and the second step 132, the first step 131 can completely separate the second placement groove 12 from the first placement groove 11 on the right side of the laser chip 4. This allows the first step 131 to prevent volatile substances such as flux from diffusing to the coupling end face of the laser chip 4 and the silicon photonic chip 3 during the flip-chip soldering process. In addition, the first step 131 can effectively prevent the laser chip 4 from overflowing during the bottom filling process after mounting, avoiding the bottom filler from overflowing to the coupling end face of the laser chip 4 and the silicon photonic chip 3 based on capillary principle. This can reduce the contamination of the first waveguide structure 31 and the second waveguide structure 41 and improve the coupling efficiency.

[0046] See Figure 1As shown, in some optional embodiments, the second step 132 connects to the second side surface 112, and the second step 132 extends from one end of the second side surface 112 to the other end of the second side surface 112 in a direction parallel to the second side surface 112. That is, in this embodiment, the second step 132 is integrally connected to the second side surface 112, and the second step 132 extends from one end of the second side surface 112 to the other end. The second step 132 is provided along the entire length of the second side surface 112. After the laser chip 4 is placed on the first step 131 and the second step 132, the second step 132 can completely separate the second placement slot 12 from the first placement slot 11 on the left side of the laser chip 4.

[0047] Preferred, see Figure 3 As shown, the silicon substrate 1 also has a third groove 14 formed on the bottom surface 113 of the first placement groove 11. The third groove 14 is separated from the second placement groove 12 by the step 13. That is, the second placement groove 12 and the third groove 14 are located at different positions on the bottom surface 113 of the first placement groove 11. One of the third grooves 14 is located at the coupling point between the second waveguide structure 41 and the first waveguide structure 31. The number of third grooves 14 can be one or more. When one third groove 14 is provided, it is located at the coupling point between the second waveguide structure 41 and the first waveguide structure 31, that is, between the step 13 and the first side surface 111. In this embodiment, by providing the third groove 14, the width of the step 13 (i.e., the width along the X direction) can be reduced, making it easier to accurately position the laser chip 4 when it is placed on the step 13.

[0048] Further, see Figure 3As shown, in some embodiments, the first placement slot 11 has a first side surface 111 and a second side surface 112 connecting its bottom surface 113. The first side surface 111 and the second side surface 112 are parallel to each other, and the first side surface 111 is located at the coupling point between the second waveguide structure 41 and the first waveguide structure 31. The step 13 includes a first step 131 and a second step 132 spaced apart. The first step 131 and one of the third slots 14 are located between the first side surface 111 and the second placement slot 12. Specifically, the third slot 14 is located between the first step 131 and the first side surface 111, and the first step 131 is located between the third slot 14 and the second slot. The first step 131 extends from one end of the first side surface 111 to the other end of the first side surface 111 in a direction parallel to the first side surface 111. In this embodiment, the first step 131 and the first side 111 are spaced apart and not connected. The first step 131 extends along the Y-axis from one side of the first placement groove 11 to the other side. After the laser chip 4 is placed on the first step 131 and the second step 132, the first step 131 can completely separate the second placement groove 12 and the third placement groove on the right side of the laser chip 4. This allows the first step 131 to prevent volatile substances such as flux from diffusing to the coupling end face of the laser chip 4 and the silicon photonic chip 3 during the flip-chip soldering process. In addition, the first step 131 can effectively prevent the underfill adhesive from overflowing to the coupling end face of the laser chip 4 and the silicon photonic chip 3 based on capillary principle during the bottom filling process of the laser chip 4. This can reduce the contamination of the first waveguide structure 31 and the second waveguide structure 41 and improve the coupling efficiency.

[0049] See Figure 5 and Figure 6 As shown, in some optional embodiments, the second step 132 is located between the second placement groove 12 and the second side surface 112, and at least two second steps 132 are provided between the second placement groove 12 and the second side surface 112. The at least two second steps 132 are spaced apart along a direction parallel to the second side surface 112, so that the third groove 14 located between the second step 132 and the second side surface 112 is connected to the second placement groove 12. In this embodiment, multiple spaced second steps 132 are provided on the side of the laser chip 4 away from the silicon photonic chip 3, and there is a gap between two adjacent second steps 132, so that the third groove 14 on this side is connected to the second placement groove 12. The space between two adjacent second steps 132 can not only be used to set solder 2 to achieve electrical connection with the laser chip 4, improving the space utilization on the silicon substrate 1, but also allow volatile substances such as flux during the flip-chip bonding process of the laser chip 4 to diffuse away from this side, further reducing the contamination of the waveguide structure.

[0050] Preferably, the laser chip 4 has a second coupling end face, and the side of the first step 131 can be flush with the second coupling end face of the laser chip 4 in the Z direction (see...). Figure 3 It can also be uneven (see...) Figure 4 When the side of the first step 131 is flush with the second coupling end face of the laser chip 4 in the Z direction, the distance d between the first step 131 and the first side 111 is in the range of 1.5um≤d≤4um. This range can maximize the coupling efficiency and reduce the coupling insertion loss.

[0051] This application employs a conventional and mature grooving method. Based on the specific dimensions of the laser chip 4 and the solder ball or copper pillar, two grooves are cleverly created on the silicon substrate 1. This method can achieve precise coupling alignment while ensuring sufficient electrical interconnection of the metal bonding layer. Furthermore, the grooving process is simple, mature, and low-cost. Additionally, the depth and width of the grooves can be flexibly designed according to the specific dimensions of the chip.

[0052] This application also provides a flip-chip bonding method for a laser and a silicon optical waveguide, which includes the following steps:

[0053] Step 1: A first placement groove 11 is formed on the silicon substrate 1, and a second placement groove 12 is formed on the bottom surface 113 of the first placement groove 11, so that a step 13 is formed at the junction of the first placement groove 11 and the second placement groove 12.

[0054] Step 2: Place solder 2 in the second placement groove 12 and fix silicon photonic chip 3 on the silicon substrate 1, so that the silicon photonic chip 3 is located on one side of the first placement groove 11, wherein the silicon photonic chip 3 is provided with a first waveguide structure 31.

[0055] Step 3: Place the laser chip 4 in the first placement slot 11, so that the laser chip 4 is supported on the step 13, and the laser chip 4 is electrically connected to the silicon substrate 1 through the solder 2. At the same time, the second waveguide structure 41 in the laser chip 4 is coupled to the first waveguide structure 31 in the silicon photonic chip 3.

[0056] Furthermore, the step of forming a first placement groove 11 on the silicon substrate 1 and forming a second placement groove 12 on the bottom surface 113 of the first placement groove 11, such that a step 13 is formed at the junction of the first placement groove 11 and the second placement groove 12, may include:

[0057] The first placement trench 11 and the second placement trench 12 are formed on the silicon substrate 1 using a photolithography mask and plasma etching methods; or...

[0058] The first placement groove 11 and the second placement groove 12 are formed on the silicon substrate 1 using laser micro-nano processing.

[0059] There are three methods for creating grooves on the silicon substrate 1: Method 1, using a photomask and plasma dry etching. This method offers high precision, controllable at the nanometer scale; good morphology, with perpendicularity controllable above 89°; and good sidewall and bottom roughness. The etching rate is lower than wet etching, making this method the preferred choice. Method 2, using a photomask and plasma wet etching. This method offers a faster etching rate and good sidewall and bottom roughness. However, the morphology is worse than dry etching, and side cutouts are more likely. Method 3, using laser micro / nano processing. The processing efficiency is much faster than the aforementioned plasma dry and wet etching methods, but compared to the two methods above, it is a rougher process with some deviations in morphology and dimensions.

[0060] In this application, electrical interconnection is ensured by precisely controlling the etching depth of each groove, while improving coupling accuracy; Step 13 can block the volatilization of organic matter such as flux, and can also prevent the bottom underfill adhesive from diffusing to the coupling end face of the laser chip 4 and the silicon photonic chip 3, thus preventing contamination of the waveguide structure; This application can achieve efficient coupling between the semiconductor laser chip 4 and the silicon photonic chip 3, and can solve the problem of light source in silicon-based photonics.

[0061] In the description of this application, it should be noted that the terms "upper," "lower," etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Unless otherwise expressly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two elements. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0062] It should be noted that in this application, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0063] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A flip-chip bonded laser-silicon waveguide coupling structure, characterized in that, It includes: A silicon substrate (1) is provided with a first placement groove (11), and a second placement groove (12) is provided on the bottom surface (113) of the first placement groove (11), so that a step (13) is formed at the junction of the first placement groove (11) and the second placement groove (12), and solder (2) is placed in the second placement groove (12). A silicon photonic chip (3) is fixed on the silicon substrate (1) and located on one side of the first placement groove (11). A first waveguide structure (31) is provided in the silicon photonic chip (3). A laser chip (4) is placed in the first placement slot (11) and supported on the step (13). The laser chip (4) is electrically connected to the silicon substrate (1) through the solder (2). A second waveguide structure (41) is provided in the laser chip (4) and the second waveguide structure (41) is coupled to the first waveguide structure (31). The silicon substrate (1) also has a third groove (14) on the bottom surface (113) of the first placement groove (11), and the third groove (14) is separated from the second placement groove (12) by the step (13); The first placement slot (11) has a first side surface (111) and a second side surface (112) connected to its bottom surface (113). The first side surface (111) and the second side surface (112) are parallel to each other, and the first side surface (111) is located at the coupling point between the second waveguide structure (41) and the first waveguide structure (31). The step (13) includes a first step (131) and a second step (132) spaced apart. The first step (131) and one of the third grooves (14) are located between the first side (111) and the second placement groove (12). The first step (131) extends from one end of the first side (111) to the other end of the first side (111) in a direction parallel to the first side (111). The second step (132) is located between the second placement groove (12) and the second side (112), and at least two second steps (132) are provided between the second placement groove (12) and the second side (112). The at least two second steps (132) are distributed at intervals along a direction parallel to the second side (112), so that the third groove (14) located between the second step (132) and the second side (112) is connected to the second placement groove (12).

2. The flip-chip bonded laser-silicon waveguide coupling structure as described in claim 1, characterized in that, The step (13) includes a first step (131) and a second step (132) supporting opposite sides of the laser chip (4), the first step (131) being located on the side of the laser chip (4) closer to the silicon photonic chip (3), and the second step (132) being located on the other side of the laser chip (4).

3. The flip-chip bonded laser-silicon waveguide coupling structure as described in claim 2, characterized in that, The first placement slot (11) has a first side surface (111) and a second side surface (112) connected to its bottom surface (113). The first side surface (111) and the second side surface (112) are parallel to each other, and the first side surface (111) is located at the coupling point between the second waveguide structure (41) and the first waveguide structure (31). The first step (131) connects to the first side (111), and the first step (131) extends from one end of the first side (111) to the other end of the first side (111) in a direction parallel to the first side (111).

4. The flip-chip bonded laser-silicon waveguide coupling structure as described in claim 1, characterized in that, The distance d between the first step (131) and the first side (111) is 1.5um≤d≤4um.

5. A flip-chip bonding method for a laser and a silicon optical waveguide, characterized in that, It includes the following steps: A first placement groove (11) is formed on a silicon substrate (1), and a second placement groove (12) is formed on the bottom surface (113) of the first placement groove (11), so that a step (13) is formed at the junction of the first placement groove (11) and the second placement groove (12). Solder (2) is placed in the second placement groove (12), and silicon photonic chip (3) is fixed on the silicon substrate (1), such that the silicon photonic chip (3) is located on one side of the first placement groove (11), wherein the silicon photonic chip (3) is provided with a first waveguide structure (31). A laser chip (4) is placed in the first placement slot (11) and supported on the step (13). The laser chip (4) is electrically connected to the silicon substrate (1) through the solder (2). At the same time, the second waveguide structure (41) in the laser chip (4) is coupled to the first waveguide structure (31) in the silicon photonic chip (3). The silicon substrate (1) also has a third groove (14) on the bottom surface (113) of the first placement groove (11), and the third groove (14) is separated from the second placement groove (12) by the step (13); The first placement slot (11) has a first side surface (111) and a second side surface (112) connected to its bottom surface (113). The first side surface (111) and the second side surface (112) are parallel to each other, and the first side surface (111) is located at the coupling point between the second waveguide structure (41) and the first waveguide structure (31). The step (13) includes a first step (131) and a second step (132) spaced apart. The first step (131) and one of the third grooves (14) are located between the first side (111) and the second placement groove (12). The first step (131) extends from one end of the first side (111) to the other end of the first side (111) in a direction parallel to the first side (111). The second step (132) is located between the second placement groove (12) and the second side (112), and at least two second steps (132) are provided between the second placement groove (12) and the second side (112). The at least two second steps (132) are distributed at intervals along a direction parallel to the second side (112), so that the third groove (14) located between the second step (132) and the second side (112) is connected to the second placement groove (12).

6. The flip-chip bonding coupling method as described in claim 5, characterized in that, The method of forming a first placement groove (11) on a silicon substrate (1) and forming a second placement groove (12) on the bottom surface (113) of the first placement groove (11), such that a step (13) is formed at the junction of the first placement groove (11) and the second placement groove (12), includes: The first placement trench (11) and the second placement trench (12) are formed on the silicon substrate (1) using a photolithography mask and plasma etching methods; or, The first placement groove (11) and the second placement groove (12) are formed on the silicon substrate (1) using a laser micro-nano processing method.

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