CN115440756A

CN115440756A - Optical transceiver and manufacturing method thereof

Info

Publication number: CN115440756A
Application number: CN202211153119.3A
Authority: CN
Inventors: 胡晓; 刘阳; 刘晔; 刘佳; 肖希; 陈代高; 王磊
Original assignee: Wuhan Optical Valley Information Optoelectronic Innovation Center Co Ltd
Current assignee: Wuhan Optical Valley Information Optoelectronic Innovation Center Co Ltd
Priority date: 2022-09-21
Filing date: 2022-09-21
Publication date: 2022-12-06

Abstract

The disclosed embodiments provide an optical transceiver and a method of manufacturing the same. The optical transceiver includes: a three-dimensionally integrated first semiconductor structure and second semiconductor structure; the first semiconductor structure includes: the photoelectric detector, the driving chip, the first waveguide structure, the plurality of first metal electrodes and the plurality of first conductive through hole structures; the driving chip is electrically connected to the first metal electrodes through the first conductive through hole structures; the second semiconductor structure includes: an electro-optic modulation layer overlying the first waveguide structure and the plurality of first metal electrodes; wherein the electro-optical modulation layer is electrically connected to the plurality of first metal electrodes; the electro-optical modulation layer, the first waveguide structure, and the plurality of first metal electrodes constitute a modulator.

Description

Optical transceiver and manufacturing method thereof

Technical Field

The disclosed embodiments relate to the field of optoelectronic device technologies, and in particular, to an optical transceiver and a method for manufacturing the same.

Background

The silicon photonic technology is a new generation technology for developing and integrating optical devices based on silicon and silicon-based substrate materials (such as SiGe/Si, silicon-on-insulator, etc.) by using the existing Complementary Metal Oxide Semiconductor (CMOS) process. The silicon photon technology combines the characteristics of ultra-large scale and ultra-high precision manufacturing of an integrated circuit technology and the advantages of ultra-high speed and ultra-low power consumption of the photon technology, and is a subversive technology for coping with the Moore's law failure. This combination contributes to scalability of semiconductor wafer fabrication, thereby enabling cost reduction.

However, the bandwidth of the pure silicon optical modulator based on the carrier dispersion effect is limited to about 80GHz, and it is difficult to increase the bandwidth.

Disclosure of Invention

Accordingly, the embodiments of the present disclosure provide an optical transceiver and a method for manufacturing the same to solve at least one technical problem in the prior art.

In order to achieve the purpose, the technical scheme of the disclosure is realized as follows:

in a first aspect, embodiments of the present disclosure provide an optical transceiver comprising: a three-dimensionally integrated first semiconductor structure and second semiconductor structure;

the first semiconductor structure includes: the photoelectric detector, the driving chip, the first waveguide structure, the plurality of first metal electrodes and the plurality of first conductive through hole structures; wherein the driving chip is electrically connected to the plurality of first metal electrodes through the plurality of first conductive via structures;

the second semiconductor structure includes: an electro-optic modulation layer overlying the first waveguide structure and the plurality of first metal electrodes; wherein the electro-optical modulation layer is electrically connected to the plurality of first metal electrodes; the electro-optical modulation layer, the first waveguide structure, and the plurality of first metal electrodes constitute a modulator.

In some embodiments, the first semiconductor structure and the second semiconductor structure are connected by flip-chip bonding.

In some embodiments, the driving chip is formed on a first substrate; the photodetector, the first waveguide structure, and the plurality of first metal electrodes are formed on a silicon-on-insulator, SOI; the SOI is located on the driving chip.

In some embodiments, the first semiconductor structure further comprises: a dielectric layer located on the SOI; the first conductive through hole structure penetrates through the dielectric layer and the SOI in sequence.

In some embodiments, the photodetector comprises:

a silicon layer; the SOI comprises bottom silicon, an oxygen buried layer and top silicon in sequence, wherein the silicon layer is formed by etching the top silicon;

a germanium absorption layer on the silicon layer;

the N-type doped structure and the P-type doped structure are positioned on the buried oxide layer; the silicon layer and the germanium absorption layer are positioned between the N-type doped structure and the P-type doped structure;

the two second metal electrodes are respectively positioned on the N-type doped structure and the P-type doped structure;

and the two second conductive through hole structures are respectively and electrically connected with the two second metal electrodes.

In some embodiments, the first semiconductor structure further comprises:

the transimpedance amplifier chip is formed on the first substrate and is electrically connected to the two second metal electrodes through the two second conductive through hole structures.

In some embodiments, the first semiconductor structure further comprises:

the first conductive through hole structure is electrically connected with the driving chip through the first solder ball;

and the second conductive through hole structure and the trans-impedance amplifier chip are electrically connected through the second solder ball.

In some embodiments, the first semiconductor structure further comprises:

a second waveguide structure located within the dielectric layer; wherein orthographic projections of the first waveguide structure and the second waveguide structure on the first substrate at least partially overlap.

In some embodiments, the first semiconductor structure further comprises:

the resistance unit is positioned in the medium layer and positioned below the modulator; the resistor unit is used for heating the first waveguide structure and the second waveguide structure, or the resistor unit is used for realizing impedance matching of the modulator and the first metal electrode.

In some embodiments, the first waveguide structure includes, in a transmission direction of an optical signal: the device comprises an optical beam splitter, an optical beam combiner and a double-path waveguide structure positioned between the optical beam splitter and the optical beam combiner; the optical beam splitter splits input light and then respectively couples the split input light into the electro-optical modulation layer through the two-way waveguide structure, the light modulated by the electro-optical modulation layer is coupled into the two-way waveguide structure again, and the light is output after being interfered by the optical beam combiner.

In some embodiments, the material of the electro-optical modulation layer is lithium niobate.

In a second aspect, embodiments of the present disclosure provide a method of manufacturing an optical transceiver, the optical transceiver comprising: a three-dimensionally integrated first semiconductor structure and second semiconductor structure; the manufacturing method comprises the following steps:

forming the first semiconductor structure, including: providing a first substrate; forming a photodetector and a driving chip on the first substrate; forming a dielectric layer on the photoelectric detector and the driving chip; forming a plurality of first conductive through hole structures, a plurality of first metal electrodes and a first waveguide structure in the dielectric layer; the driving chip is electrically connected to the first metal electrodes through the first conductive through hole structures;

forming the second semiconductor structure, including: providing a second substrate; forming an electro-optical modulation layer on the second substrate;

flip-chip bonding the second semiconductor structure to the first semiconductor structure such that the electro-optical modulation layer covers the first waveguide structure and the plurality of first metal electrodes; wherein the electro-optical modulation layer is electrically connected to the plurality of first metal electrodes; the electro-optical modulation layer, the first waveguide structure, and the plurality of first metal electrodes constitute a modulator.

In some embodiments, the forming of the photodetector and the driving chip on the first substrate includes:

forming a transimpedance amplifier chip and a driving chip on the first substrate;

forming a silicon-on-insulator SOI on the transimpedance amplifier chip and the driving chip; the SOI comprises bottom silicon, a buried oxide layer and top silicon in sequence;

the photodetector is formed on the SOI.

In some embodiments, the forming the photodetector on the SOI comprises:

etching the top silicon layer to form a silicon layer;

forming an N-type doped structure and a P-type doped structure on the buried oxide layer, wherein the silicon layer is positioned between the N-type doped structure and the P-type doped structure;

forming two second conductive through hole structures and two second metal electrodes, wherein the two second metal electrodes are respectively contacted with the N-type doped structure and the P-type doped structure; the two second conductive through hole structures are electrically connected with the two second metal electrodes respectively;

and forming a germanium absorption layer on the silicon layer, wherein the germanium absorption layer is positioned between the two second metal electrodes.

In some embodiments, the forming a plurality of first conductive via structures within the dielectric layer includes:

forming a first dielectric layer on the photoelectric detector and the driving chip;

etching to form a plurality of first through holes which sequentially penetrate through the first dielectric layer, the oxygen buried layer and the bottom silicon;

and filling a conductive material in the first through holes to form a plurality of first conductive through hole structures.

In some embodiments, forming a plurality of first metal electrodes within the dielectric layer comprises:

forming a second dielectric layer on the plurality of first conductive through hole structures;

etching the second dielectric layer to form a plurality of first grooves; each first groove exposes the first conductive via structure;

and filling a metal material in the first grooves to form a plurality of first metal electrodes.

In some embodiments, forming a first waveguide structure within the dielectric layer comprises:

etching the second dielectric layer to form a plurality of first grooves, and simultaneously etching the second dielectric layer to form second grooves;

and filling waveguide materials in the second groove to form a first waveguide structure.

The disclosed embodiments provide an optical transceiver and a method of manufacturing the same. The optical transceiver includes: a three-dimensionally integrated first semiconductor structure and second semiconductor structure; the first semiconductor structure includes: the photoelectric detector, the driving chip, the first waveguide structure, the plurality of first metal electrodes and the plurality of first conductive through hole structures; wherein the driving chip is electrically connected to the plurality of first metal electrodes through the plurality of first conductive via structures; the second semiconductor structure includes: an electro-optical modulation layer covering the first waveguide structure and the plurality of first metal electrodes; wherein the electro-optical modulation layer is electrically connected to the plurality of first metal electrodes; the electro-optical modulation layer, the first waveguide structure, and the plurality of first metal electrodes constitute a modulator. In the embodiment of the disclosure, the driving chip is electrically connected to the first metal electrodes through the first conductive through hole structures, and the integration between the driving chip and the modulator is realized by using the first conductive through hole structures, which is beneficial to reducing the loss of high-frequency signals and improving the quality of the signals.

In addition, in the embodiment of the disclosure, the first semiconductor structure includes a photodetector and a driving chip, the first waveguide structure, the plurality of first metal electrodes, the plurality of first conductive via structures, and the electro-optical modulation layer, which are disposed in the first semiconductor structure, together form a modulator, and the photodetector, the modulator, and the chip are three-dimensionally integrated, so that not only can the integration level of the device be improved, but also the transmission rate and bandwidth of signals can be improved.

Drawings

Fig. 1 is a schematic cross-sectional view of an optical transceiver according to an embodiment of the present disclosure;

fig. 2 is a schematic perspective structural diagram of a modulator provided in an embodiment of the present disclosure;

fig. 3 is a schematic perspective structural view of a first waveguide structure and a second waveguide structure provided by an embodiment of the present disclosure;

fig. 4 is a schematic flow chart illustrating a method of manufacturing an optical transceiver according to an embodiment of the present disclosure;

the figure includes: 100. a first semiconductor structure; 101. a first substrate; 102. an isolation layer; 103. a driving chip; 104. a transimpedance amplifier chip; 105. bottom layer silicon; 106. burying an oxygen layer; 107. a dielectric layer; 108. a first waveguide structure; 109. a first metal electrode; 110. a first conductive via structure; 111. a first solder ball; 112. a resistance unit; 113. a silicon layer; 114. a germanium absorption layer; 115. an N-type doped structure; 116. a P-type doped structure; 117. a second metal electrode; 118. a second conductive via structure; 119. a second waveguide structure; 120. a second solder ball; 121. an optical splitter; 122. a first branch waveguide structure; 123. a second branch waveguide structure; 124. a beam combiner; 200. a second semiconductor structure; 201. a second substrate; 202. an electro-optical modulation layer.

Detailed Description

The technical solutions in the embodiments of the present disclosure will be clearly and completely described below with reference to the embodiments of the present disclosure and the accompanying drawings, and it is obvious that the described embodiments are only some embodiments of the present disclosure, not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments disclosed herein without inventive step, are within the scope of the present disclosure.

In the following description, numerous specific details are set forth in order to provide a more thorough understanding of the present disclosure. It will be apparent, however, to one skilled in the art, that the present disclosure may be practiced without one or more of these specific details. In other instances, well-known features have not been described in order not to obscure the present disclosure; that is, not all features of an actual embodiment are described herein, and well-known functions and structures are not described in detail.

In the drawings, the size of layers, regions, elements, and relative sizes may be exaggerated for clarity. Like reference numerals refer to like elements throughout.

It will be understood that when an element or layer is referred to as being "on" \8230; \8230 ";," - \8230;, "\8230"; "adjacent to," "connected to," or "coupled to" other elements or layers, it can be directly on, adjacent to, connected to, or coupled to the other elements or layers, or intervening elements or layers may be present. In contrast, when an element is referred to as being "directly on," 8230; \8230 ";," "directly adjacent," "directly connected to," or "directly coupled to" another element or layer, there are no intervening elements or layers present. It will be understood that, although the terms first, second, third, etc. may be used to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the present disclosure. And the discussion of a second element, component, region, layer or section does not necessarily imply that a first element, component, region, layer or section is necessarily present in the disclosure.

Spatial relational terms such as "in 8230," "below," "in 8230," "below," "8230," "above," "above," and the like may be used herein for convenience of description to describe the relationship of one element or feature to another element or feature illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements or features described as "below" or "beneath" other elements or features would then be oriented "above" the other elements or features. Thus, the exemplary terms "at 8230; \8230; below" and "at 8230; \8230; below" may include both upper and lower orientations. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatial descriptors used herein interpreted accordingly.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. As used herein, the term "and/or" includes any and all combinations of the associated listed items.

In order to thoroughly understand the present disclosure, detailed steps and detailed structures will be set forth in the following description so as to explain the technical aspects of the present disclosure. The following detailed description of the preferred embodiments of the disclosure, however, the disclosure can be practiced otherwise than as specifically described.

Referring to fig. 1, fig. 1 is a schematic cross-sectional structural diagram of an optical transceiver according to an embodiment of the disclosure. As shown in fig. 1, an optical transceiver provided by an embodiment of the present disclosure includes: a three-dimensionally integrated first semiconductor structure 100 and second semiconductor structure 200;

the first semiconductor structure 100 includes: the photoelectric detector, the driving chip 103, the first waveguide structure 108, the plurality of first metal electrodes 109 and the plurality of first conductive via structures 110; the driving chip 103 is electrically connected to the first metal electrodes 109 through the first conductive via structures 110;

the second semiconductor structure 200 includes: an electro-optical modulation layer 202, the electro-optical modulation layer 202 covering the first waveguide structure 108 and the plurality of first metal electrodes 109; wherein, the electro-optical modulation layer 202 is electrically connected with the plurality of first metal electrodes 109; the electro-optical modulation layer 202, the first waveguide structure 108 and the plurality of first metal electrodes 109 constitute a modulator.

Here, the modulator includes a first waveguide structure and a plurality of first metal electrodes disposed within a first semiconductor structure, and an electro-optic modulation layer disposed within a second semiconductor structure.

Here, a Driver chip (Driver) may be used to provide the modulator with a driving signal.

In some embodiments, the first semiconductor structure 100 and the second semiconductor structure 200 are connected by Flip Chip bonding (Flip Chip). Here, the electro-optical modulation layer is hybrid-integrated with a Silicon On Insulator (SOI) in the first semiconductor by a flip-chip technology, and has a high process tolerance.

Here, the second semiconductor structure 200 includes: a second substrate 201 and an electro-optical modulation layer 202 on the second substrate 201. And after the second semiconductor structure is manufactured on other process platforms, the second semiconductor structure is inversely bonded on the first semiconductor structure at the position corresponding to the first waveguide structure and the plurality of first metal electrodes, so that the electro-optical modulation layer covers the first waveguide structure and the plurality of first metal electrodes. As shown in fig. 1, the electro-optical modulation layer 202 is inverted over the first waveguide structure 108 and the plurality of first metal electrodes 109.

In one particular example, the second substrate may be a quartz substrate.

Here, the electro-optical modulation layer may be a slab waveguide structure or a ridge waveguide structure. For example, a lithium niobate thin film is formed as an electro-optical modulation layer on a second substrate. Compared with a silicon optical modulator, the theoretical bandwidth of the lithium niobate thin film optical modulator can reach 500GHz, and the bandwidth of the modulator is favorably improved.

And if the electro-optical modulation layer is of a slab waveguide structure, inversely bonding the second semiconductor structure on the first semiconductor structure so that the electro-optical modulation layer covers the first waveguide structure and the plurality of first metal electrodes. For another example, after a lithium niobate thin film is formed on the second substrate, the lithium niobate is etched to form a ridge waveguide structure. If the electro-optical modulation layer is a ridge waveguide structure, the second semiconductor structure is inversely bonded on the first semiconductor structure, and at the moment, a groove is arranged at the corresponding position of the first semiconductor structure, so that the ridge of the ridge waveguide structure on the second semiconductor structure corresponds to the groove on the first semiconductor structure, the ridge and the groove of the ridge waveguide structure are mutually embedded, and the ridge of the ridge waveguide structure on the second semiconductor structure corresponds to the position of the first waveguide structure in the first semiconductor structure. In other words, the ridge of the ridge waveguide structure and the orthographic projection of the first waveguide structure on the second substrate at least partially overlap.

As also shown in fig. 1, the first semiconductor structure 100 includes: a first substrate 101 and an isolation layer 102 on the first substrate 101; the isolation layer 102 is provided with a driving chip 103 and a transimpedance amplifier chip 104.

Here, the first substrate may be divided into a first region for forming a modulator and a second region for forming a photodetector; the driving chip is located in the first area, and the transimpedance amplifier chip is located in the second area.

Here, the photodetector is used to convert an optical signal into an electrical signal, and a Trans Impedance Amplifier (TIA) chip is used to amplify and output the electrical signal.

Here, the first substrate may be a semiconductor substrate; specifically including at least one elemental semiconductor material (e.g., a silicon (Si) substrate, a germanium (Ge) substrate, etc.), at least one III-V compound semiconductor material (e.g., a gallium nitride (GaN) substrate, a gallium arsenide (GaAs) substrate, an indium phosphide (InP) substrate, etc.), at least one II-VI compound semiconductor material, at least one organic semiconductor material, or other semiconductor materials known in the art.

As also shown in fig. 1, the first semiconductor structure 100 further includes: the SOI is positioned on the driving chip 103 and sequentially comprises bottom silicon 105, a buried oxide layer 106 and top silicon; the top layer silicon is etched during the formation of the photodetector to form the silicon layer 113 in the photodetector. The dielectric layer 107 is positioned on the SOI, a first waveguide structure 108, a plurality of first metal electrodes 109 and a plurality of first conductive through hole structures 110 are arranged in the dielectric layer 107, the upper surface of the dielectric layer 107 is flush with the upper surfaces of the plurality of first metal electrodes 109, and the plurality of first conductive through hole structures 110 sequentially penetrate through the dielectric layer 107 and the SOI (including a buried oxide layer 106 and a bottom layer silicon 105).

Here, the first through hole may be formed by sequentially etching the dielectric layer, the buried oxide layer, and the bottom silicon; and filling the first through hole with a conductive material to form a first conductive through hole structure. The first conductive through hole structure is used for electrically connecting the modulator and the driving chip.

In one specific example, the first conductive Via structure may be a Through Silicon Via (TSV). Here, the metallic copper vias have an interconnect characteristic of 3dB bandwidth ≧ 110 GHz.

In the related technical scheme, the integration mode of the modulator and the driving chip is limited to gold wire bonding, and additional high-frequency loss and signal quality reduction are introduced. In the embodiment of the disclosure, the driving chip is electrically connected to the first metal electrodes through the first conductive through hole structures, and the integration between the driving chip and the modulator is realized by using the first conductive through hole structures, so that the loss of high-frequency signals is reduced, and the quality of the signals is improved.

In addition, in the optical transceiver provided by the embodiment of the disclosure, in the process of forming the first semiconductor structure, the first through hole is obtained only by etching the dielectric layer, the buried oxide layer and the bottom layer silicon, the first through hole is subsequently filled to obtain the first conductive through hole structure, and the first conductive through hole structure which only penetrates through the dielectric layer, the buried oxide layer and the bottom layer silicon is connected with the first metal electrode and the driving chip of the modulator. That is, embodiments of the present disclosure provide an optical transceiver in which the first conductive via structure has been formed before the first and second semiconductor structures are flip-chip bonded.

Here, the upper surface of the dielectric layer is flush with the upper surface of the first waveguide structure, or a predetermined distance is provided between the upper surface of the dielectric layer and the upper surface of the first waveguide structure. If the upper surface of the dielectric layer is flush with the upper surface of the first waveguide structure (as shown in fig. 1), the first waveguide structure and the electro-optic modulation layer are in direct contact at this time. If a preset distance exists between the upper surface of the dielectric layer and the upper surface of the first waveguide structure, a preset distance exists between the first waveguide structure and the electro-optical modulation layer, and a dielectric layer material is filled between the first waveguide structure and the electro-optical modulation layer, so that the range of the preset distance is ensured to be 100 nm-300 nm, and an optical signal in the first waveguide structure can be coupled into the electro-optical modulation layer.

Referring to fig. 2, fig. 2 is a schematic perspective structural diagram of a modulator provided in the embodiment of the present disclosure. For ease of illustration, fig. 2 only illustrates the first waveguide structure 108 of fig. 1 within the modulator. As shown in fig. 2, in the transmission direction of the optical signal, the first waveguide structure includes: an optical beam splitter 121, an optical beam combiner 124, and a dual-path waveguide structure (i.e., a first branch waveguide structure 122 and a second branch waveguide structure 123) between the optical beam splitter 121 and the optical beam combiner 124; the optical beam splitter 121 splits input light and couples the split input light into the electro-optical modulation layer 202 through the two-way waveguide structure, and the light modulated by the electro-optical modulation layer 202 is coupled into the two-way waveguide structure again and is output after being interfered by the optical beam combiner 124. Wherein the first metal electrode 109 may provide an electrical modulation signal for the first waveguide structure.

Here, the optical beam splitter, the optical beam combiner, and the two-way waveguide structure between the optical beam splitter and the optical beam combiner, and the electro-optical modulation layer constitute a Mach-Zehnder interferometer (MZI) structure. The optical beam splitter is used for equally dividing input light into two beams, the two beams of light respectively enter two arms (namely a two-way waveguide structure) of the Mach-Zehnder interferometer structure, then the two beams of light are respectively coupled and enter the electro-optical modulation layer, the light is influenced by the electrical modulation signal when being transmitted in the electro-optical modulation layer, therefore, the phase of the light is modulated, then the two beams of light modulated by the electro-optical modulation layer are coupled and enter the two-way waveguide structure, then the light is interfered by the optical beam combiner, and finally the output light is the modulated light signal.

Still referring to fig. 2, the optical splitter 121 has a first input terminal and a second input terminal through which the optical source inputs the optical signal into the optical splitter 121; the first output end of the optical splitter 121 is connected to the first branch waveguide structure 122, and the second output end of the optical splitter is connected to the second branch waveguide structure 123; after the optical signal is input into the optical combiner 124 by the first branch waveguide structure 122 and the second branch waveguide structure 123, the optical signal is output through the first output end and the second output end of the optical combiner 124, so that a 2 × 2 optical splitter/combiner is constructed.

Fig. 2 illustrates that, in the transmission direction of the optical signal, the width of the first branch waveguide structure in the direction perpendicular to the transmission direction of the optical signal decreases first and then increases, and the width of the second branch waveguide structure in the direction perpendicular to the transmission direction of the optical signal decreases first and then increases. Here, the first branched waveguide structure, a width direction of the first branched waveguide structure is parallel to a plane where the first substrate is located, and the width direction of the first branched waveguide structure, the first branched waveguide structure is perpendicular to a transmission direction of the optical signal.

In one particular example, the material of the first waveguide structure may be silicon. In another specific example, the material of the first waveguide structure may also be silicon nitride.

As shown in fig. 1, a second waveguide structure 119 is further disposed in the dielectric layer 107, wherein orthographic projections of the first waveguide structure 108 and the second waveguide structure 119 on the first substrate 101 at least partially overlap.

Referring to fig. 3, fig. 3 is a schematic perspective structural diagram of a first waveguide structure and a second waveguide structure provided in an embodiment of the present disclosure. Fig. 3 shows that the first waveguide structure 108 and the second waveguide structure 119 are partially overlapped, and the dimension of the overlapped portion of the first waveguide structure 108 and the second waveguide structure 119 along the extending direction of the first waveguide structure 108 or the second waveguide structure 119 is L ₁ 。

If the materials of the first waveguide structure 108 and the second waveguide structure 119 are both silicon nitride, the thickness of the first waveguide structure 108 along the direction perpendicular to the first substrate is 300nm to 500nm; the thickness of the second waveguide structure 119 in a direction perpendicular to the first substrate is 100nm to 300nm; the dimension of the portion where the first waveguide structure 108 and the second waveguide structure 119 overlap each other along the extending direction of the first waveguide structure 108 or the second waveguide structure 119 is 10 μm to 150 μm. In addition, the first waveguide structure and the second waveguide structure made of silicon nitride, and the electro-optical modulation layer made of lithium niobate are all materials supporting the light transparent band of 400nm to 2000nm, so the modulator and the photodetector in the optical transceiver provided by the embodiment of the disclosure will also support 400nm to 2000nm.

If the materials of the first waveguide structure 108 and the second waveguide structure 119 are both silicon, the thickness of the first waveguide structure 108 in the direction perpendicular to the first substrate is 150nm to 300nm; the thickness of the second waveguide structure 119 in a direction perpendicular to the first substrate is 100nm to 200nm; the size of the portion where the first waveguide structure 108 and the second waveguide structure 119 overlap each other in the extending direction of the first waveguide structure 108 or the second waveguide structure 119 is 30 μm to 200 μm.

Here, a part of the second waveguide structure may be located below the first waveguide structure, and the optical signal input into the second waveguide structure may be coupled to the first waveguide structure and further coupled to the modulator; and another part of the second waveguide structure may be located above the photodetector, and the optical signal may also be coupled to the photodetector after being input into the second waveguide structure.

In one particular example, the material of the first and second waveguide structures may be silicon. In another specific example, the material of the first waveguide structure and the second waveguide structure may be silicon nitride. Since the refractive index of silicon nitride is 1.98 and the refractive index of silicon is 3.4, the use of silicon as a waveguide structure provides better confinement of optical signals and the waveguide structure is relatively smaller in size.

In some embodiments, the first waveguide structure and the second waveguide structure are spaced apart in a direction perpendicular to the first substrate in a range of 100nm to 600nm to ensure suitable coupling efficiency.

Here, the upper surface of the dielectric layer is flush with the upper surfaces of the plurality of first metal electrodes, and the electro-optical modulation layer covers the upper surfaces of the dielectric layer and the plurality of first metal electrodes. In this manner, the electro-optical modulation layer is in direct contact with the plurality of first metal electrodes, which provide the first waveguide structure with an electrical modulation signal.

Here, the first metal electrode of the lithium niobate modulator is fabricated by a silicon optical CMOS process on SOI. For example, after a dielectric layer is deposited and formed on the SOI and the dielectric layer is etched and filled to form the first conductive via structure, a first metal material layer may be deposited and formed on the upper surfaces of the first conductive via structure and the dielectric layer, and the first metal electrode may be formed after the first metal material layer is etched. For another example, a first dielectric layer is deposited on the SOI, and the first dielectric layer is etched and filled to form a first conductive through hole structure; forming a second dielectric layer, and etching the second dielectric layer to form a first groove exposing the first conductive through hole structure; and filling a metal material in the first groove to form a first metal electrode.

Here, the first metal electrode may be driven in a single-end manner or in a differential manner.

Here, high efficiency modulation is achieved by properly positioning the electro-optical modulation layer and the first metal electrode. For example, the center of the electro-optical modulation layer is located at the center of the electrode pitch of the first metal electrode.

In one specific example, the material of the first metal electrode may be copper. In another specific example, the material of the first metal electrode may also be aluminum.

In the embodiment of the disclosure, the driving chip transmits the high-frequency electrical signal to the first metal electrode on the upper layer through the first conductive through hole structure, and the electro-optical modulation layer has an electro-optical effect, that is, when a voltage is applied to the electro-optical modulation layer, the refractive index of the electro-optical modulation layer changes, so as to modulate the phase, amplitude, intensity and polarization state of the optical signal. Here, the electro-optical effect includes a linear electro-optical effect, i.e., a Pockels (Pockels) effect, and a quadratic electro-optical effect, i.e., a Kerr (Kerr) effect.

In some embodiments, the first semiconductor structure 100 further comprises: a resistance unit 112 located in the dielectric layer 107, wherein the resistance unit 112 is located below the modulator; the resistance unit 112 is used to heat the first waveguide structure 108 and the second waveguide structure 119, or the resistance unit 112 is used to implement impedance matching between the modulator and the first metal electrode 109.

Here, the resistance unit is located below the two-way waveguide structure. The resistance unit may be used to achieve impedance matching between the modulator and the first metal electrode to improve modulation efficiency of the modulator.

The resistance unit is positioned below the double-path waveguide structure, and the first waveguide structure and the second waveguide structure are heated by heat energy of the resistance unit through heat radiation, so that the temperature distribution near the first waveguide structure and the second waveguide structure is improved, and the mode field distribution in the first waveguide structure and the second waveguide structure is further influenced, so that the phase adjustment of the optical signal is realized.

In the embodiment of the present disclosure, the material of the resistance unit includes, but is not limited to, titanium nitride.

As shown in fig. 1, the first semiconductor structure 100 further includes: the first solder balls 111, the first conductive via structures 110 and the driving chip 103 are electrically connected through the first solder balls 111.

In the embodiment of the present disclosure, the material of the first solder ball may include a metal or a metal alloy having a conductive property, for example, silver, copper, or an alloy containing copper and silver.

As shown in fig. 1, the photodetector includes: a silicon layer 113; the SOI comprises bottom silicon 105, a buried oxide layer 106 and top silicon, and a silicon layer 113 is formed by etching the top silicon; a germanium absorption layer 114 on the silicon layer 113; an N-type doped structure 115 and a P-type doped structure 116 on the buried oxide layer 106; the silicon layer 113 and the germanium absorption layer 114 are located between the N-type doped structure 115 and the P-type doped structure 116; two second metal electrodes 117, the two second metal electrodes 117 are respectively located on the N-type doped structure 115 and the P-type doped structure 116; two second conductive via structures 118, and the two second conductive via structures 118 are electrically connected to the two second metal electrodes 117, respectively.

Here, the optical signal may be coupled to the germanium absorption layer after being input into the second waveguide structure, and the optical signal may be converted into an electrical signal by the photodetector, where the electrical signal may be amplified by the transimpedance amplifier chip and then output.

In one specific example, the material of the first metal electrode may be copper.

Here, the second through hole may be formed by sequentially etching the dielectric layer, the buried oxide layer, and the bottom silicon; and filling a conductive material in the second through hole to form a second conductive through hole structure. The second conductive through hole structure is used for electrically connecting the photoelectric detector and the transimpedance amplifier chip.

In one particular example, the second conductive via structure may be a metallic copper via.

In the embodiments of the present disclosure, the radio frequency connection manner of the high-speed electrical chip (i.e., the transimpedance amplifier chip and the driver chip) and the optical chip (i.e., the lithium niobate modulator and the silicon germanium photodetector) will greatly affect the signal transmission and loading quality, including signal integrity, microwave loss, impedance continuity, parasitic capacitance, parasitic inductance, and the like. By adopting a three-dimensional integrated stacking mode based on the TSV technology, the connection distance of high-frequency signals of the electric chip and the optical chip is effectively reduced, and the realization of signal transmission with the bandwidth larger than 100GHz is facilitated. In addition, the three-dimensional integrated optoelectronic chip structure is adopted, so that the integration density is greatly improved, the higher high-frequency connection freedom degree is provided, and the expandability is strong. In the embodiment of the present disclosure, the lithium niobate modulator and the driving chip are electrically connected through the first conductive via structure, and the photodetector and the transimpedance amplifier chip are electrically connected through the second conductive via structure, so as to implement a high-density and large-bandwidth optical transceiver.

As shown in fig. 1, the first semiconductor structure 100 further includes: the second solder balls 120, the second conductive via structures 118 and the transimpedance amplifier chip 104 are electrically connected through the second solder balls 120.

In the embodiment of the present disclosure, the material of the second solder ball may include a metal or a metal alloy having a conductive property, for example, silver, copper, an alloy containing copper and silver, and the like.

The first solder balls are located on the electrodes of the driving chip and used for electrically leading out the driving chip; the second welding ball is positioned on the electrode of the transimpedance amplifier chip and used for electrically leading out the transimpedance amplifier chip.

Here, the driving chip and the transimpedance amplifier chip can be powered by being connected to a peripheral circuit.

The embodiment of the disclosure provides an optical transceiver of a three-dimensional integrated photoelectric detector and a modulator, wherein a second waveguide structure and a lateral PIN type germanium-silicon photoelectric detector jointly form an optical receiving end to receive signals; the first waveguide structure constructs a 2 multiplied by 2 beam splitter/combiner and a Mach-Zehnder interferometer waveguide structure, and forms an optical signal modulation end with the lithium niobate electro-optical modulation layer and the first metal electrode to realize the emission of signals; the second waveguide structure and the first waveguide structure can realize the mutual coupling transition of optical signals; a second metal electrode of the photoelectric detector is interconnected with the transimpedance amplifier electric chip through a second conductive through hole structure, and a first metal electrode of the modulator is interconnected with the driving chip through a first conductive through hole structure; the resistance unit (for example, a titanium nitride resistance unit) can be used for heating the second waveguide structure and the first waveguide structure, and can also be used for realizing the terminal resistance matching function of the modulator; the first metal electrode of the lithium niobate modulator is fabricated on SOI by a silicon photo CMOS process. The scheme provided by the embodiment of the disclosure for three-dimensionally integrating the lithium niobate modulator, the germanium-silicon photoelectric detector, the driving chip and the transimpedance amplifier electric chip has the characteristics of high tolerance, high integration, small size and high speed of the preparation process.

The optical transceiver provided by the embodiment of the disclosure has the following beneficial effects: (1) The optical transceiver provided by the embodiment of the disclosure can realize three-dimensional integration of an optical chip (namely, a lithium niobate modulator and a silicon germanium photodetector) and an electrical chip (namely, a transimpedance amplifier chip and a driving chip), and can greatly improve the overall bandwidth and speed of the chip; (2) According to the optical transceiver provided by the embodiment of the disclosure, a silicon optical process platform is utilized to process key core elements of a chip, and then a lithium niobate electro-optical modulation layer is integrated, so that performance advantages of all elements are fully exerted; (3) In the optical transceiver provided by the embodiment of the disclosure, the first metal electrode of the lithium niobate modulator is processed and realized on a silicon optical process platform, which is different from the electrode preparation of the previous lithium niobate modulator, thereby facilitating mass production and reducing cost; (4) In the optical transceiver provided by the embodiment of the disclosure, the second waveguide structure and the first waveguide structure are used as optical transmission and coupling functions of the receiving end and the transmitting end, so that flexibility and freedom of chip design are increased; (5) The non-etched flat lithium niobate is used as an electro-optical modulation layer, and the hybrid integration with the SOI chip is realized through the flip-chip bonding process, so that the process alignment tolerance is greatly improved, and the yield, the consistency and the comprehensive performance of the whole chip are improved.

Referring to fig. 4, fig. 4 is a flowchart illustrating a method for manufacturing an optical transceiver according to an embodiment of the disclosure. As shown in fig. 4, an optical transceiver provided by an embodiment of the present disclosure includes a first semiconductor structure and a second semiconductor structure integrated in three dimensions, and a manufacturing method of the optical transceiver includes the following steps:

step S401: forming a first semiconductor structure comprising: providing a first substrate; forming a photodetector and a driving chip on a first substrate; forming a dielectric layer on the photoelectric detector and the driving chip; forming a plurality of first conductive through hole structures, a plurality of first metal electrodes and a first waveguide structure in the dielectric layer; the driving chip is electrically connected to the first metal electrodes through the first conductive through hole structures;

step S402: forming a second semiconductor structure comprising: providing a second substrate; forming an electro-optical modulation layer on a second substrate;

step S403: flip-chip bonding a second semiconductor structure on the first semiconductor structure so that the electro-optical modulation layer covers the first waveguide structure and the plurality of first metal electrodes; the electro-optical modulation layer is electrically connected with the plurality of first metal electrodes; the electro-optical modulation layer, the first waveguide structure and the plurality of first metal electrodes constitute a modulator.

In some embodiments, forming the photodetector and the driving chip on the first substrate includes: forming a transimpedance amplifier chip and a driver chip on a first substrate; forming a silicon-on-insulator SOI on the transimpedance amplifier chip and the driving chip; the SOI comprises bottom silicon, an oxygen buried layer and top silicon in sequence; the photodetector is formed on SOI.

In an embodiment of the present disclosure, forming the first semiconductor structure includes: providing a first substrate, wherein the first substrate comprises a first surface and a second surface arranged opposite to the first surface; a driver chip and a transimpedance amplifier chip are provided on a first surface of a first substrate. Here, the first substrate may be divided into a first region for forming a modulator and a second region for forming a photodetector; the driving chip is located in the first area, and the transimpedance amplifier chip is located in the second area.

Here, the embodiments of the present disclosure will be described taking the first substrate as a silicon substrate as an example.

Here, SOI may be formed on the driver chip and the transimpedance amplifier chip; the SOI comprises bottom silicon, a buried oxide layer and top silicon in sequence.

In some embodiments, forming a photodetector on an SOI comprises: etching the top layer silicon to form a silicon layer; forming an N-type doped structure and a P-type doped structure on the buried oxide layer, wherein the silicon layer is positioned between the N-type doped structure and the P-type doped structure; forming two second conductive through hole structures and two second metal electrodes, wherein the two second metal electrodes are respectively contacted with the N-type doped structure and the P-type doped structure; the two second conductive through hole structures are electrically connected with the two second metal electrodes respectively; and forming a germanium absorption layer on the silicon layer, wherein the germanium absorption layer is positioned between the two second metal electrodes.

In embodiments of the present disclosure, the photodetector may be formed on an SOI located on a transimpedance amplifier chip. Here, the signal of the photodetector may be amplified by the transimpedance amplifier chip.

In some embodiments, forming a plurality of first conductive via structures within a dielectric layer comprises: forming a first dielectric layer on the photoelectric detector and the driving chip; etching to form a plurality of first through holes which sequentially penetrate through the first dielectric layer, the buried oxide layer and the bottom silicon; and filling the conductive material in the first through holes to form a plurality of first conductive through hole structures.

In some embodiments, forming a plurality of first metal electrodes within the dielectric layer comprises: forming a second dielectric layer on the plurality of first conductive through hole structures; etching the second dielectric layer to form a plurality of first grooves; each first groove exposes a first conductive via structure; and filling a metal material in the first grooves to form a plurality of first metal electrodes.

Here, the material of the first dielectric layer and the material of the second dielectric layer may be the same or different.

In some embodiments, forming a first waveguide structure within the dielectric layer comprises: etching the second dielectric layer to form a plurality of first grooves, and simultaneously etching the second dielectric layer to form second grooves; and filling waveguide materials in the second groove to form a first waveguide structure.

Here, forming the first dielectric layer and the second dielectric layer may be formed using a process including, but not limited to, physical vapor deposition, chemical vapor deposition, atomic layer deposition, or any combination thereof.

Here, the forming of the plurality of first through holes, the forming of the plurality of first grooves, and the forming of the plurality of second grooves may use wet etching, dry etching, or a combination thereof.

In an embodiment of the present disclosure, forming the second semiconductor structure includes: providing a second substrate, wherein the second substrate comprises a first surface and a second surface arranged opposite to the first surface; an electro-optic modulation layer is formed on a first surface of a second substrate.

In an embodiment of the disclosure, forming an optical transceiver includes: flip-chip bonding a second semiconductor structure on the first semiconductor structure so that the electro-optical modulation layer covers the first waveguide structure and the plurality of first metal electrodes; the electro-optical modulation layer is electrically connected with the plurality of first metal electrodes; the electro-optical modulation layer, the first waveguide structure and the plurality of first metal electrodes constitute a modulator.

Here, the first semiconductor structure and the second semiconductor structure may be connected using a flip-chip bonding process.

In some embodiments, forming the first semiconductor structure further comprises: forming a first welding ball, and electrically connecting the first conductive through hole structure and the driving chip through the first welding ball; and forming a second welding ball, and electrically connecting the second conductive through hole structure and the trans-impedance amplifier chip through the second welding ball.

Here, the first solder balls are positioned on the electrodes of the driving chip and used for electrically leading out the driving chip; the second welding ball is positioned on the electrode of the transimpedance amplifier chip and used for electrically leading out the transimpedance amplifier chip.

In some embodiments, forming the first semiconductor structure further comprises: forming a second waveguide structure located within the dielectric layer; wherein orthographic projections of the first waveguide structure and the second waveguide structure on the first substrate at least partially overlap.

In some embodiments, forming the first semiconductor structure further comprises: forming a resistance unit positioned in the medium layer, wherein the resistance unit is positioned below the modulator; the resistance unit is used for heating the first waveguide structure and the second waveguide structure, or the resistance unit is used for realizing impedance matching of the modulator and the first metal electrode.

Here, the resistance unit is formed to radiate heat energy generated by the resistance unit to the outside, so as to heat the first waveguide structure and the second waveguide structure, improve temperature distribution near the first waveguide structure and the second waveguide structure, and further influence mode field distribution in the first waveguide structure and the second waveguide structure, so as to realize phase adjustment of the optical signal.

Here, forming the resistance unit may also be used to achieve impedance matching between the modulator and the first metal electrode to improve modulation efficiency of the modulator.

The disclosed embodiments provide an optical transceiver and a method of manufacturing the same. The optical transceiver includes: three-dimensionally integrated first and second semiconductor structures; the first semiconductor structure includes: the photoelectric detector, the driving chip, the first waveguide structure, the plurality of first metal electrodes and the plurality of first conductive through hole structures; wherein the driving chip is electrically connected to the plurality of first metal electrodes through the plurality of first conductive via structures; the second semiconductor structure includes: an electro-optical modulation layer covering the first waveguide structure and the plurality of first metal electrodes; wherein the electro-optical modulation layer is electrically connected to the plurality of first metal electrodes; the electro-optical modulation layer, the first waveguide structure, and the plurality of first metal electrodes constitute a modulator. In the embodiment of the disclosure, the driving chip is electrically connected to the first metal electrodes through the first conductive through hole structures, and the integration between the driving chip and the modulator is realized by using the first conductive through hole structures, so that the loss of high-frequency signals is reduced, and the quality of the signals is improved.

In addition, in the embodiment of the present disclosure, the first semiconductor structure includes a photodetector and a driving chip, the first waveguide structure, the plurality of first metal electrodes, and the plurality of first conductive via structures that are disposed in the first semiconductor structure and the electro-optical modulation layer that is disposed in the second semiconductor structure together form a modulator, and the photodetector, the modulator, and the chip are three-dimensionally integrated, which not only can improve the integration level of the device, but also can improve the transmission rate and bandwidth of signals.

It should be appreciated that reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the present disclosure. Thus, the appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. It should be understood that, in various embodiments of the present disclosure, the sequence numbers of the above-mentioned processes do not imply an order of execution, and the order of execution of the processes should be determined by their functions and inherent logic, and should not constitute any limitation to the implementation process of the embodiments of the present disclosure. The above-mentioned serial numbers of the embodiments of the present disclosure are merely for description and do not represent the merits of the embodiments.

The above description is only a preferred embodiment of the present disclosure, and does not limit the scope of the present disclosure, and all equivalent structural changes made by using the contents of the specification and drawings of the present disclosure or other related technical fields directly/indirectly applied under the inventive concept of the present disclosure are included in the scope of the present disclosure.

Claims

1. An optical transceiver, characterized in that the optical transceiver comprises: three-dimensionally integrated first and second semiconductor structures;

the first semiconductor structure includes: the photoelectric detector, the driving chip, the first waveguide structure, the plurality of first metal electrodes and the plurality of first conductive through hole structures; the driving chip is electrically connected to the first metal electrodes through the first conductive through hole structures;

the second semiconductor structure includes: an electro-optical modulation layer covering the first waveguide structure and the plurality of first metal electrodes; wherein the electro-optical modulation layer is electrically connected to the plurality of first metal electrodes; the electro-optical modulation layer, the first waveguide structure, and the plurality of first metal electrodes constitute a modulator.

2. The optical transceiver of claim 1, wherein the first semiconductor structure and the second semiconductor structure are connected by flip-chip bonding.

3. The optical transceiver of claim 1, wherein the driver chip is formed on a first substrate; the photodetector, the first waveguide structure, and the plurality of first metal electrodes are formed on a silicon-on-insulator, SOI; the SOI is located on the driving chip.

4. The optical transceiver of claim 3, wherein the first semiconductor structure further comprises: a dielectric layer located on the SOI; the first conductive through hole structure penetrates through the dielectric layer and the SOI in sequence.

5. The optical transceiver of claim 3, wherein the photodetector comprises:

a germanium absorption layer on the silicon layer;

6. The optical transceiver of claim 5, wherein the first semiconductor structure further comprises:

7. The optical transceiver of claim 6, wherein the first semiconductor structure further comprises:

8. The optical transceiver of claim 4, wherein the first semiconductor structure further comprises:

9. The optical transceiver of claim 8, wherein the first semiconductor structure further comprises:

the resistance unit is positioned in the medium layer and positioned below the modulator; the resistance unit is used for heating the first waveguide structure and the second waveguide structure, or the resistance unit is used for realizing impedance matching of the modulator and the first metal electrode.

10. The optical transceiver of claim 1, wherein the first waveguide structure comprises, in a transmission direction of an optical signal: the device comprises an optical beam splitter, an optical beam combiner and a double-path waveguide structure positioned between the optical beam splitter and the optical beam combiner; the optical beam splitter splits input light and then respectively couples the split input light into the electro-optical modulation layer through the two-way waveguide structure, the light modulated by the electro-optical modulation layer is coupled into the two-way waveguide structure again, and the light is output after being interfered by the optical beam combiner.

11. The optical transceiver of claim 1, wherein the electro-optic modulation layer is formed of lithium niobate.

12. A method of manufacturing an optical transceiver, the optical transceiver comprising: a three-dimensionally integrated first semiconductor structure and second semiconductor structure; the manufacturing method comprises the following steps:

13. The method of manufacturing an optical transceiver according to claim 12, wherein the forming a photodetector and a driver chip on the first substrate comprises:

forming the photodetector on the SOI.

14. The method of manufacturing an optical transceiver according to claim 13, wherein the forming the photodetector on the SOI comprises:

etching the top silicon layer to form a silicon layer;

15. The method of manufacturing an optical transceiver of claim 14, wherein forming a plurality of first conductive via structures within the dielectric layer comprises:

etching to form a plurality of first through holes which sequentially penetrate through the first dielectric layer, the buried oxide layer and the bottom silicon;

16. The method of manufacturing an optical transceiver of claim 15, wherein forming a plurality of first metal electrodes within the dielectric layer comprises:

17. The method of manufacturing an optical transceiver of claim 16, wherein forming a first waveguide structure within the dielectric layer comprises: