CN107422420B - A three-dimensional photonic device interconnection method based on fused direct writing - Google Patents

Abstract

The invention discloses a kind of three-dimensional photon device interconnection methods based on melting direct write, comprising: step 1, the light-guide material of the high grade of transparency is melt into liquid in the heated molten bath with micro nozzle；Step 2, by high precision position moving stage mobile micro nozzle to the first bonding point, under static pressure effect, melting light-guide material is continuously squeezed out from micro nozzle, is bonded with the first bonding point；Step 3, mobile micro nozzle carries out bottom-up direct write, forms photon transmission optical fiber, then mobile micro nozzle to the second bonding point is bonded photon transmission optical fiber with the second bonding point, realizes the level interconnection of multilayer integrated optical circuit.Reproducible due to using melt liquid bonding techniques, production precision can reach nanoscale and fiber coupling is compatible, and three-dimensional glass light guide surface scattering loss obtained is small, be suitable for high integration three-dimensional photon device and high sensor.

Description

A three-dimensional photonic device interconnection method based on fused direct writing

technical field

The invention relates to the field of integrated optical circuits and integrated optical waveguide devices, in particular to a three-dimensional photonic device interconnection method based on fusion direct writing.

Background technique

The integrated optical circuit is an integrated optical system formed by integrating and miniaturizing a series of discrete optical devices, such as prisms, lenses, gratings, and optical couplers. In the integrated optical path, each optical element is formed on a wafer substrate and connected with an optical waveguide formed inside or on the surface of the substrate, which is an important way to solve the miniaturization of the original optical system and improve the overall performance. The information capacity processed by the integrated optical circuit is much larger than that of the integrated circuit. At the same time, the integrated optical circuit also has multi-dimensional information processing capabilities, and will be the basic device of the next generation of optical communication.

In order to increase the density of information transmission, a three-dimensional integrated optical circuit can be used to form a free-space integrated optical circuit, so that the scope of the integrated optical circuit is not limited to optical waveguides. Data transmission through light beams propagating in free space is suitable for hierarchical connections between chips, making the interconnection density close to the diffraction limit of light, there is no channel limitation on bandwidth, and it is easy to realize reconfigurable interconnections. In addition to the common advantages of general optical interconnection, free space optical interconnection switching network also has the advantages of easy realization of three-dimensional network, large number of interconnections, high interconnection density, and contactless interconnection. This technology is the most attractive among optical interconnect technologies.

For the free-space optical interconnection technology, the early research mainly focused on how to use technology to form a multi-level optical interconnection network, Crossbar and Mesh and other interconnection networks (US Patent 10460389), and how to use the technology in the three-dimensional space of the traditional two-dimensional planar structure electronic plug-in Realize optical communication. For free-space optical interconnection, the alignment problem of the optical path is particularly prominent. Although there are many related technologies such as active and passive alignment, self-alignment, etc., none of them are ideal. Moreover, many optical interconnection technologies are based on hybrid integration, and the monolithic integration of optoelectronic chips is very difficult.

Using waveguide interconnection can provide high-density interconnection channels. The most mature optical waveguide is optical fiber, which is suitable for interconnection at this level within a chip or between chips. The most studied is the preparation of lithium niobate (LiNbO ₃ ) optical waveguides and devices by solid-state diffusion, and the preparation of semiconductor heterojunction optical waveguides and devices by epitaxy. Semiconductor is the material with the largest nonlinear optical value, but the response time is limited by the carrier recombination time and is longer. Glass has the characteristics of extremely low optical loss and easy processing, which enables the integration of optical waveguides on glass substrates. This optical waveguide is generally prepared by ion exchange technology or chemical vapor deposition. In terms of technology, fast and convenient processing of optical waveguides is the key to the preparation of ultrafast all-optical modulation integrated optical devices. Therefore, optical interconnection still needs a more applicable and flexible process technology to promote its practical application.

Contents of the invention

The purpose of the present invention is to provide a method for interconnection of three-dimensional photonic devices based on fused direct writing, which is used to form a free-space interconnection optical path between three-dimensional integrated optical path levels, so that the interconnection density is close to the diffraction limit of light, and the multi-layer integrated optical On the way, a multifunctional photon transmission channel with small volume, compact structure and high integration is prepared.

Technical scheme of the present invention is:

A three-dimensional photonic device interconnection method based on fused direct writing, comprising:

Step 1, melting the high-transparency photoconductive material into a liquid state in a heated molten pool with micro-nozzles;

Step 2, moving the micro-nozzle to the first bonding point through a high-precision translation stage, and under the action of static pressure, the molten photoconductive material is continuously extruded from the micro-nozzle to bond with the first bonding point;

Step 3, move the micro-nozzle to perform bottom-up direct writing to form a photon transmission fiber, and then move the micro-nozzle to the second bonding point to bond the photon transmission fiber to the second bonding point to realize the hierarchical interconnection of multi-layer integrated optical circuits .

The light guide material is a transparent material that should have high third-order polarization tensor, fast response time, minimum absorption coefficient and high environmental stability, including: quartz, glass, transparent plastic, infrared material, etc. These light-guiding materials have extremely low optical loss and are easy to melt process, making them particularly suitable for integrated optical waveguides.

Preferably, the glass is inorganic glass, which has stable chemical properties, diverse components, low loss, easy processing, and low cost. More preferably, the glass is oxide glass, fluoride glass, chalcogenide glass, sulfur It is a halide glass and multi-component glass. Preferably, the transparent material is polymethyl methacrylate (PMMA), polycarbonate (PC) and the like.

Preferably, the way of heating the photoconductive material is one or more combination of resistance heating, arc heating, induction heating, electron beam heating, dielectric heating and plasma heating. Further preferably, according to the properties of the photoconductive material, an appropriate heating method is used to heat and melt the photoconductive material. When the photoconductive material is transparent plastic, resistance heating is used; when the photoconductive material is glass, induction heating is used. The melting point of the glass is higher, the heating efficiency of the induction heating method is higher, and the heating speed is faster. Using the induction heating glass can quickly make the glass Melted into liquid, saving energy.

When the optical guide material is melted, it is one of the key factors to improve the performance of the optical waveguide to accurately and stably control the ejection of the molten optical guide material from the micro nozzle. Therefore, in the direct writing process, according to the diameter of the nozzle and the length of the channel, heating to The melt viscosity of the material reaches 100-1000Pa·s, and the static pressure of 0.1-1000kPa at the back end is assisted, so that the molten light-guiding material is uniformly and continuously extruded through the micro nozzle. If the pressure is not enough, bubbles will appear on the surface of the optical fiber written directly, which is not smooth enough, or even intermittent, and cannot be connected in a straight line. If the pressure is too high, it will agglomerate or block. Therefore, according to the viscosity of the melt at the melting temperature, an appropriate static pressure condition must be set to ensure that the melt of the photoconductive material can be extruded stably, and the interconnected optical fiber obtained by direct writing has no bubbles, smooth surface, and low loss.

The micro-nozzle is connected with the heating molten pool and is the discharge end of the photoconductive material melt. In order to improve the quality of interconnection fibers obtained by direct writing (no bubbles, smooth surface, low loss), the micro nozzle needs to have a smooth inner surface and no bonding with the molten light-guiding material. Preferably, the micro-nozzle can be one of ceramic nozzle, metal nozzle, alloy nozzle or composite nozzle made of ceramic, metal and alloy materials.

The method of the invention is mainly used for the free interconnection between three-dimensional integrated optical circuit levels. Preferably, the photonic transmission fiber connects optical signals at different parts of the same chip layer, or connects optical signals at different chip layers. That is, the first bonding point and the second bonding point are output ends or input ends of optical signals at different parts of the same chip layer, or the first bonding point and the second bonding point are usually output ends or input ends of optical signals at different chip layers. input. In this way, the photon transmission path is formed between the input end and the output end of the optical signal through the movement of the micro nozzle.

Since the direct writing method has the characteristics of optical interconnection in any direction or in multiple different directions in free space, the photon transmission fiber can be freely oriented in space according to the photon transmission direction or the requirements of the integrated optical circuit architecture. Therefore, preferably, the The photon transmission fiber usually has a diameter of 0.1-100 μm. The shape of the photon transmission fiber is one or a combination of straight lines, broken lines, and helical lines, and it can also be an irregular curved shape, so as to meet the requirements of achieving high-precision, high-efficiency multi-layer integrated optical circuits in free space. even.

The three-dimensional photonic device interconnection method of the present invention can realize photon interconnection between different positions and different levels only through simple fusion direct writing technology, does not require overlay engraving, improves graphic conversion accuracy, low cost, and simple manufacturing method Mature.

Due to the use of molten liquid bonding technology, the repeatability is good, the manufacturing accuracy can reach the nanometer level, and it is compatible with optical fiber coupling. The surface scattering loss of the prepared three-dimensional glass optical waveguide is small, and it is suitable for highly integrated three-dimensional photonic devices and high-sensitivity sensors. Therefore, the present invention reduces the technical difficulty of free space processing optical path, simplifies the hierarchical interconnection process of three-dimensional integrated optical path; meanwhile, it can suppress the increase of surface roughness caused by traditional ion exchange technology, and the obtained three-dimensional glass optical waveguide has a large refractive index contrast , improving yield and performance.

Description of drawings

Fig. 1 is a schematic structural diagram of a direct writing system for interconnection of three-dimensional photonic devices in a preferred embodiment of the present invention;

Fig. 2 is an optical microscope diagram of the interconnection process of three-dimensional photonic devices in a preferred embodiment of the present invention;

Fig. 3 is the scanning electron micrograph of the glass structure interconnected by three-dimensional photonic devices in the present invention;

Fig. 4 is a scanning electron microscope image of the inter-level glass interconnection structure of a three-dimensional photonic device in a preferred embodiment of the present invention.

Detailed ways

In order to further clarify the purpose, technical solutions and advantages of the present invention, the present invention will be further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings. In the drawings or descriptions of the embodiments, the same reference numerals are used for similar or identical parts. Components or implementations not shown or described in the drawings are forms well known to those skilled in the art. Additionally, while illustrations of parameters including particular values may be provided herein, it should be understood that the parameters need not be exactly equal to the corresponding values, but rather may approximate the corresponding values within acceptable error margins or design constraints.

Fig. 1 is a schematic structural diagram of a direct writing system for interconnecting three-dimensional photonic devices in a preferred embodiment of the present invention. As shown in FIG. 1 , the direct writing system 100 is mainly composed of a control system, a system moving platform (ie, a three-dimensional XYZ moving platform), a melting pool 103 with micro nozzles 105 and a heating system 102 . The direct writing process is as follows: the high-transparency photoconductive material 110 is fed into the molten pool 103 by the feeding mechanism, and is melted into a liquid melt 111 under the heat of the heating system 102, and the liquid melt 111 is squeezed by the pressure 104 at the back of the molten pool 103. Press down and extrude from the micro-nozzle 105; use the high-precision piezoelectric displacement stage drive control system to move the platform under the program control, the resolution can reach the nanometer scale, and the molten photoconductive material is bonded to the bonding point by moving the micro-nozzle 105 to the chip 120 , through direct writing from the bottom to the top of the micro-nozzle 105 of the translation stage, continuous extrusion forms the photon transmission optical path-interconnecting optical fiber 130; according to the combination of the moving direction and speed of the three-dimensional XYZ translation platform, various curves or broken lines can be formed in free space transmission light path.

Fig. 2 is an optical microscope diagram of the interconnection process of three-dimensional photonic devices in a preferred embodiment of the present invention. As shown in Figure 2, when the highly transparent photoconductive material 110 is melted into a liquid melt 111 in the melting pool 103, under the action of surface tension, the liquid melt 111 can form a liquid meniscus at the outlet of the micro nozzle 105 surface, as shown in Figure 2 (a); after the meniscus contacts with the bonding point of the chip 120, due to the low temperature of the bonding point, it solidifies at the bonding point and bonds immediately, and the bonding point is usually a photoconductive material (such as glass ), the surface of the bonding point is partially melted after contact with the high-temperature liquid, so it can form a firm bond with the direct-written interconnected optical fiber, as shown in Figure 2(b); in the subsequent direct-writing process, with the movement of the micro-nozzle 105, An interconnecting fiber with a uniform diameter is formed between the bonding point and the micronozzle 105, as shown in FIG. 2(c).

In this embodiment, due to the adoption of molten liquid bonding technology, the precision can reach nanometer level. As shown in Figure 3, the interconnection fiber is welded with the substrate of the photonic device to form uniform solder joints, and the surface of the direct-written photonic interconnection fiber is smooth, especially the solder joints can form a uniform spherical shape, making the photonic interconnection line extremely Low optical loss. The diameter and spot size of the photonic interconnect fiber shown can be controlled by controlling the temperature and micronozzle 105 .

Example 1

In this embodiment, the purpose is to prepare a photon transmission fiber (optical waveguide) to connect optical signals at different parts of the same chip layer. Specifically: place vulcanized glass (As ₂ S ₃ ) in a molten pool with a micro-alloy nozzle with a diameter of 100 μm, and heat the molten pool to 1200°C by means of inductive heating to melt the vulcanized glass into a liquid state. The viscosity is 700Pa·s; then, after the melt is extruded to the first bonding point, a static pressure of 10kPa is applied to continuously extrude the melt, and at the same time, the nozzle is moved from bottom to top for direct writing, forming a straight line with a diameter of 100μm Interconnect the fibers to the second bonding point.

Example 2

In this embodiment, the purpose is to prepare a photonic transmission fiber (optical waveguide) to connect optical signals of different chip layers. Specifically, the multi-component glass (SiO ₂ -CaO-Na ₂ O) is placed in a molten pool with a micro-ceramic nozzle with a diameter of 100 μm, and the molten pool is heated to 1000°C by means of arc heating, so that SiO ₂ -CaO -Na ₂ O is melted into a liquid state. At this time, the melt viscosity is 1000Pa·s; then, after the melt is extruded to the first bonding point, a static pressure of 800kPa is applied to continuously extrude the melt while moving the nozzle Direct writing was performed from the bottom up to form a curved interconnection fiber with a diameter of 99 μm to the second bonding point.

FIG. 4 shows the curved glass interconnection fiber obtained in this embodiment. The interconnection line is located between two different chips, so as to realize the transmission of photonic signals at different levels.

Example 3

In this embodiment, the purpose is to prepare a photonic transmission fiber (optical waveguide) to connect optical signals of different chip layers. Specifically: place quartz glass (SiO ₂ -GeO ₂ ) in a molten pool with a micro-alloy nozzle with a diameter of 10 μm, and heat the molten pool to 1200°C by means of dielectric heating to melt SiO ₂ -GeO ₂ into a liquid state , at this time, the melt viscosity is 800Pa·s; then, after the melt is extruded to the first bonding point, a static pressure of 9kPa is applied to continuously extrude the melt, and at the same time, the nozzle is moved from bottom to top for direct writing, A helical curve with a diameter of 9 μm is formed to interconnect the fiber to the second bonding point.

Example 4

In this embodiment, the purpose is to prepare a photonic transmission fiber (optical waveguide) to connect optical signals of different chip layers. Specifically, polycarbonate (PC) is placed in a molten pool with a micro-alloy nozzle with a diameter of 5 μm, and the molten pool is heated to 220 ° C by means of resistance heating to melt the PC into a liquid state. At this time, the melt viscosity is 500Pa·s; then, after the melt is extruded to the first bonding point, a static pressure of 4kPa is applied to continuously extrude the melt, and at the same time, the nozzle is moved from bottom to top for direct writing, forming a curved interconnection with a diameter of 4μm Fiber to the second bonding point.

The above-mentioned interconnection methods can be used as passive components in optical fiber communication, such as isolators, directional or star couplers, wavelength division multiplexers, and routing in integrated optical circuits.

The above-mentioned specific embodiments have described the technical solutions and beneficial effects of the present invention in detail. It should be understood that the above-mentioned are only the most preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, supplements and equivalent replacements made within the scope shall be included in the protection scope of the present invention.

Claims (8)

1. A three-dimensional photonic device interconnection method based on fused direct writing, comprising: Step 1, melting the high-transparency photoconductive material into a liquid state in a heated molten pool with micro-nozzles; Step 2, moving the micro-nozzle to the first bonding point through a high-precision translation stage, and under the action of static pressure, the molten photoconductive material is continuously extruded from the micro-nozzle to bond with the first bonding point; Step 3, move the micro-nozzle to perform bottom-up direct writing to form a photon transmission fiber, and then move the micro-nozzle to the second bonding point to bond the photon transmission fiber to the second bonding point to realize the hierarchical interconnection of multi-layer integrated optical circuits ; In the direct writing process, according to the diameter of the nozzle and the length of the channel, heat until the melt viscosity of the photoconductive material reaches 100-1000Pa·s, and then assist the static pressure of 0.1-1000kPa at the back end to make the molten photoconductive material uniformly and continuously extruded through the micro-nozzle; The diameter of the photon transmission fiber is 0.1-100 μm. 2 . The method for interconnecting three-dimensional photonic devices based on fused direct writing according to claim 1 , wherein the light-guiding material is quartz, glass or transparent plastic. 3 . The method for interconnecting three-dimensional photonic devices based on fused direct writing according to claim 1 , wherein the light-guiding material is an infrared material. 4 . 4. The three-dimensional photonic device interconnection method based on fusion direct writing as claimed in claim 1, wherein the heating method of the photoconductive material is resistance heating, arc heating, induction heating, electron beam heating, dielectric heating, plasma One or more combinations of body heating. 5. The method for interconnecting three-dimensional photonic devices based on fusion direct writing according to claim 3, wherein when the photoconductive material is transparent plastic, resistance heating is used; when the photoconductive material is glass, induction heating is used. 6. The method for interconnecting three-dimensional photonic devices based on fused direct writing as claimed in claim 1, wherein the micro nozzle can be one of ceramic nozzle, metal nozzle, alloy nozzle or ceramic, metal and alloy material Composite nozzles of any variety of materials. 7. The method for interconnecting three-dimensional photonic devices based on fused direct writing according to claim 1, wherein the shape of the photonic transmission fiber is one or a combination of straight lines, broken lines, and helical lines. 8. The method for interconnecting three-dimensional photonic devices based on fused direct writing according to any one of claims 1 to 7, wherein the photonic transmission fiber connects optical signals from different parts of the same chip layer, or connects different chip layers light signal.