阅读说明：本技术 一种硅基光电子单片式异质集成方法 (Silicon-based photoelectron monolithic heterogeneous integration method ) 是由 齐志强 王晨晟 张智杰 吴新建 龙瀚凌 于 2020-12-31 设计创作，主要内容包括：本发明提供了一种硅基光电子单片式异质集成方法,涉及硅基光子集成技术领域。基于硅基光电子平台将III-V化合物半导体和硅基光电子器件进行单片式集成,可应用于光电微系统应用领域。本发明针对光电微系统小型化、集成化和多功能化发展趋势对单片集成不同材料体系有源和无源半导体光子器件的迫切需求,提出了一种基于硅基的单片式异质集成方法,利用该方法可以实现基于同一硅片平台上激光器、调制器和探测器等有源光电器件和分束器、耦合器和光学微腔等无源光电器件的异质集成。(The invention provides a silicon-based photoelectron monolithic heterogeneous integration method, and relates to the technical field of silicon-based photonic integration. The III-V compound semiconductor and the silicon-based optoelectronic device are integrated in a single chip mode based on the silicon-based optoelectronic platform, and the silicon-based optoelectronic device can be applied to the field of photoelectric micro-system application. The invention provides a silicon-based single-chip heterogeneous integration method aiming at the urgent requirements of miniaturization, integration and multi-functionalization development trend of a photoelectric microsystem on active and passive semiconductor photonic devices of different material systems integrated by single chips.)

1. A monolithic heterogeneous integration method of silicon-based photoelectrons, comprising:

s1, selecting an SOI substrate, and manufacturing a passive optical device on the top silicon of the SOI substrate; the SOI substrate is composed of back silicon, a buried oxide layer and top silicon which are arranged from bottom to top;

s2, etching a deep hole for placing a source chip on the reserved position of the SOI substrate, and growing a solder metal layer on the surface of the silicon material at the bottom of the etched deep hole;

s3, bonding the pre-prepared active chip to the solder metal layer in the deep hole, wherein the active layer of the active chip and the top silicon are in the same horizontal plane;

s4, selectively growing silicon dioxide in the deep hole gap after the active chip is bonded, wherein the top of the grown silicon dioxide and the oxygen buried layer are in the same horizontal plane;

s5, selectively growing an amorphous silicon layer at the gap between the top silicon and the passive optical device, wherein the thickness of the amorphous silicon layer is consistent with that of the top silicon;

s6, manufacturing interconnection optical waveguides on the active chip and the amorphous silicon layer to realize optical interconnection of the active chip and the passive optical device;

and S7, forming an electrode contact hole above the optical waveguide of the active chip, and depositing a metal electrode in the contact hole.

2. The silicon-based optoelectronic monolithic heterogeneous integration method of claim 1, wherein prior to step S3, the method further comprises:

preparing an active chip: selecting a III-V active photoelectric device epitaxial wafer, wherein the substrate is a highly doped substrate, and the doping type is consistent with that of SOI back silicon; and thinning the back substrate of the epitaxial wafer, wherein the thickness of the epitaxial wafer is deep hole depth-a and the thickness of the gold-tin solder, and a is [0.25, 0.9], manufacturing a back metal electrode after thinning the back substrate, and obtaining the active chip by utilizing dissociation or dicing by a dicing saw.

3. The monolithic heterogeneous integrated silicon-based optoelectronic integration method as claimed in claim 2, wherein the device types of said active optoelectronic devices include but are not limited to semiconductor lasers, photodetectors and optoelectronic modulators.

4. The monolithic heterogeneous silicon-based optoelectronic integration method of claim 1, wherein the passive optical devices of step S1 are of the device types including, but not limited to, ring resonator, beam splitter, and grating coupler.

5. The monolithic heterogeneous silicon-based optoelectronic integration method as claimed in claim 1, wherein the back silicon is highly doped, and the substrate of the epitaxial wafer of the active optoelectronic device is a highly doped substrate, and the doping type is consistent with that of the back silicon of the SOI.

6. The silicon-based optoelectronic monolithic heterogeneous integration method of claim 1, wherein prior to step S7, the method further comprises:

and growing a layer of silicon dioxide material with the thickness of 300-800 nm on the top silicon by using a deposition technology to serve as a passivation layer of the active chip.

7. The silicon-based optoelectronic monolithic heterogeneous integration method as claimed in claim 1, wherein in step S2, the etching depth of the deep hole reaches to the back silicon material, and the etching depth of the deep hole is 50-200 um.

8. The monolithic heterogeneous silicon-based optoelectronic integration method as claimed in claim 1, wherein the thickness of the solder metal layer in step S2 is 2-30 um.

Technical Field

The invention relates to the technical field of silicon-based photonic integration, in particular to a silicon-based photoelectron monolithic heterogeneous integration method.

Background

The photon integration technology is to prepare the laser, the detector, the optical waveguide, the modulator, the optical switch, the splitter, the coupler and other photonic devices on the same substrate, so as to achieve the purposes of improving the speed, compressing the size, expanding the function and the like.

The photonic integrated device comprises devices with various complex structures such as active devices (lasers, detectors, amplifiers, modulators and the like) and passive devices (optical waveguides, couplers and the like), and the material types comprise InP group compound semiconductors, Si elementary substance semiconductors, silicon-on-insulator (SOI) and silicon dioxide (SiO)₂) Silicon nitride (SiN)_x) And the like, which are much larger than those of microelectronic devices. Therefore, the integration level of the current photonic integration is far lower than that of a microelectronic device, and the difficulty of the photonic device integration is far higher than that of a traditional microelectronic chip.

Silicon material has wide application in microelectronic chips, and simultaneously, silicon is also a good optical passive material, and a plurality of photoelectric devices with excellent performance, such as passive waveguides, modulators, detectors and the like, are manufactured on the basis of the silicon material. In addition, silicon has a mature CMOS process, and the precision of the existing silicon process can reach 7nm, so that the low-cost photonic integrated chip can be prepared on a large scale by means of the CMOS process, and the photoelectric integration with a microelectronic chip is facilitated. However, since silicon is a non-direct transition bandgap material, some silicon-based active optoelectronic devices (especially silicon-based lasers) cannot be industrialized, and their performance cannot exceed that of semiconductor lasers based on InP materials, the combination of silicon-based photonic chips and semiconductor lasers based on InP is still a promising solution for industrialization.

The silicon photon monolithic heterogeneous integration is an integration technology for integrating a plurality of heterogeneous material photon devices with the same or different functions on the same silicon wafer by a silicon-based CMOS manufacturing process, and integrates a multifunctional device on a single chip by utilizing the advantages of respective materials to realize the subsystem on the photoelectric chip, and has the advantages of compact structure, small size, low power consumption, strong reliability and the like. With the development trend of continuous miniaturization, integration and multi-functionalization of photoelectron microsystems, great demands are put forward on heterogeneous integration technologies.

Disclosure of Invention

To address the above problems, embodiments of the present invention provide a silicon-based optoelectronic monolithic heterogeneous integration method that overcomes, or at least partially solves, the above problems.

The embodiment of the invention provides a silicon-based photoelectron monolithic heterogeneous integration method, which comprises the following steps:

s1, selecting an SOI substrate, and manufacturing a passive optical device on the top silicon of the SOI substrate; the SOI substrate is composed of back silicon, a buried oxide layer and top silicon which are arranged from bottom to top;

s2, etching a deep hole for placing a source chip on the reserved position of the SOI substrate, and growing a solder metal layer on the surface of the silicon material at the bottom of the etched deep hole;

s3, bonding the pre-prepared active chip to the solder metal layer in the deep hole, wherein the active layer of the active chip and the top silicon are in the same horizontal plane;

s4, selectively growing silicon dioxide in the deep hole gap after the active chip is bonded, wherein the top of the grown silicon dioxide and the oxygen buried layer are in the same horizontal plane;

s5, selectively growing an amorphous silicon layer at the gap between the top silicon and the passive optical device, wherein the thickness of the amorphous silicon layer is consistent with that of the top silicon;

s6, manufacturing interconnection optical waveguides on the active chip and the amorphous silicon layer to realize optical interconnection of the active chip and the passive optical device;

and S7, forming an electrode contact hole above the optical waveguide of the active chip, and depositing a metal electrode in the contact hole.

Wherein, before step S3, the method further comprises:

preparing an active chip: selecting a III-V active photoelectric device epitaxial wafer, wherein the substrate is a highly doped substrate, and the doping type is consistent with that of SOI back silicon; and thinning the back substrate of the epitaxial wafer, wherein the thickness of the epitaxial wafer is deep hole depth-a and the thickness of the gold-tin solder, and a is [0.25, 0.9], manufacturing a back metal electrode after thinning the back substrate, and obtaining the active chip by utilizing dissociation or dicing by a dicing saw.

The device types of the active optoelectronic device include, but are not limited to, a semiconductor laser, a photodetector, and an optoelectronic modulator.

The device types of the passive optical device in step S1 include, but are not limited to, a ring resonator, a beam splitter, and a grating coupler.

The back silicon is highly doped in an N type, the substrate of the epitaxial wafer of the active photoelectric device is a highly doped substrate, and the doping type of the substrate is consistent with that of the back silicon of the SOI.

Wherein, before step S8, the method further comprises:

and growing a layer of silicon dioxide material with the thickness of 300-800 nm on the top silicon by using a deposition technology to serve as a passivation layer of the active chip.

In the step S2, the etching depth of the deep hole reaches the back silicon material, and the etching depth of the deep hole is 50-200 um.

In step S2, the thickness of the solder metal layer is 2-30 um.

The silicon-based photoelectron monolithic heterogeneous integration method provided by the embodiment of the invention is based on the processes of etching and digging, eutectic implantation, coating film filling, alignment and the like, the epitaxial full structure of chips of different material systems is implanted into a single chip, the waveguide is manufactured for optical interconnection, complex secondary epitaxy and substrate transfer are not needed, the process is simple, the reliability is good, and the original performance of the chip is fully reserved.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.

FIG. 1 is a flow chart of a silicon-based optoelectronic monolithic heterogeneous integration method according to an embodiment of the present invention;

FIG. 2 is a schematic cross-sectional view of an SOI substrate provided in accordance with an embodiment of the present invention;

FIG. 3 is a schematic diagram of a cross-section (bottom view) and a top view (top view) of a silicon-based grating coupler and optical waveguide fabricated on an SOI substrate according to an embodiment of the present invention;

FIG. 4 is a schematic diagram of an etched via cut-away (bottom) and top view (top) provided by an embodiment of the present invention;

FIG. 5 is a schematic diagram of a cross-section (bottom view) and a top view (top view) of a magnetron sputtered Au-Sn solder on the bottom of a via provided by an embodiment of the present invention;

FIG. 6 is a schematic diagram of a eutectic bonded active die shown in cross-section (bottom view) and in top view (top view) in accordance with an embodiment of the present invention;

FIG. 7 is a schematic diagram of a cross-section (bottom view) and a top view (top view) of an embodiment of the present invention after depositing silicon dioxide in a deep via gap;

FIG. 8 is a schematic diagram of a cross-section (bottom view) and a top view (top view) after growing an amorphous silicon layer according to an embodiment of the present invention;

fig. 9 is a schematic structural diagram after an active chip interconnection optical waveguide is manufactured and optical interconnection between an active chip and a passive optical device is implemented according to an embodiment of the present invention;

FIG. 10 is a schematic diagram of a cross-sectional view (bottom view) and a top view (top view) of an SOI substrate having a silicon dioxide passivation layer deposited thereon according to an embodiment of the present invention;

FIG. 11 is a schematic diagram of a cross-sectional view (bottom view) and a top view (top view) of an electrode contact hole etched in a silicon dioxide layer over an active die according to an embodiment of the present invention;

fig. 12 is a schematic cross-sectional (bottom) and top (top) view of a structure for fabricating an active chip metal electrode according to an embodiment of the present invention.

In the drawings, the components represented by the respective reference numerals are listed below:

1. back silicon, 2, an oxygen buried layer, 3, top silicon, 4, a grating coupler, 5, an optical waveguide, 6, a deep hole, 7, a solder metal layer, 8, an active chip, 9, an active chip active layer, 10, silicon dioxide, 11, an amorphous silicon layer, 12, an interconnection optical waveguide, 13, a silicon dioxide passivation layer, 14, an electrode contact hole, 15 and a metal electrode.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearances of the phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. It is explicitly and implicitly understood by one skilled in the art that the embodiments described herein can be combined with other embodiments.

The silicon photon monolithic heterogeneous integration is an integration technology for integrating a plurality of heterogeneous material photon devices with the same or different functions on the same silicon wafer by a silicon-based CMOS manufacturing process, and integrates a multifunctional device on a single chip by utilizing the advantages of respective materials to realize the subsystem on the photoelectric chip, and has the advantages of compact structure, small size, low power consumption, strong reliability and the like. With the development trend of continuous miniaturization, integration and multi-functionalization of photoelectron microsystems, great demands are put forward on heterogeneous integration technologies.

The invention provides a silicon-based photoelectron monolithic heterogeneous integration method, and relates to the technical field of silicon-based photonic integration. The III-V compound semiconductor and the silicon-based optoelectronic device are integrated in a single chip mode based on the silicon-based optoelectronic platform, and the silicon-based optoelectronic device can be applied to the field of photoelectric micro-system application.

The invention provides a silicon-based single-chip heterogeneous integration method aiming at the urgent requirements of miniaturization, integration and multi-functionalization development trend of a photoelectric microsystem on active and passive semiconductor photonic devices of different material systems integrated by single chips. The following description and description of various embodiments are presented in conjunction with the following drawings.

Fig. 1 is a flowchart of a method for silicon-based optoelectronic monolithic heterogeneous integration according to an embodiment of the present invention, and as shown in fig. 1, the method for silicon-based optoelectronic monolithic heterogeneous integration according to an embodiment of the present invention includes, but is not limited to, the following steps:

s1, selecting an SOI (Silicon-On-Insulator, Silicon On an insulating substrate) substrate, and manufacturing a passive optical device On the top Silicon of the SOI substrate; the SOI substrate is composed of back silicon 1, a buried oxide layer 2 and top silicon 3 which are arranged from bottom to top. The buried oxide layer 2 is made of silicon dioxide.

Fig. 2 is a schematic cross-sectional view of an SOI substrate according to an embodiment of the present invention. Among them, the back silicon of the SOI substrate is preferably highly doped N-type.

In step S1, a passive optical device is fabricated on the top silicon using uv lithography and dry etching techniques. Device types of passive optical devices include, but are not limited to, ring resonators, beam splitters, and grating couplers. Preferably, the passive optical device in this embodiment employs a grating coupler 4 and an optical waveguide 5. Figure 3 is a cross-sectional (bottom view) and top view (top view) schematic diagram of a silicon-based grating coupler and optical waveguide fabricated on an SOI substrate in accordance with an embodiment of the present invention.

S2, etching a deep hole for placing a source chip on the reserved position of the SOI substrate, and growing a solder metal layer 7 on the surface of the silicon material at the bottom of the etched deep hole 6;

specifically, in this embodiment, a deep hole 6 for placing the source chip is etched in the reserved position of the SOI substrate by using photolithography and etching techniques, and the etching depth reaches the back silicon material. The etching depth of the deep hole is 50-200 um. Preferably, the etching depth of the deep hole in the present embodiment is 100 um. Fig. 4 is a schematic diagram of a cross-sectional (bottom) and a top view (top) of an etched via provided by an embodiment of the present invention.

Further, a solder metal layer 7 is grown on the surface of the silicon material at the bottom of the etched deep hole by utilizing a magnetron sputtering coating technology, and the thickness of the solder metal layer 7 is 2-30 um. Preferably, the solder metal layer is 10um thick Au80Sn20 gold-tin solder metal layer. Fig. 5 is a schematic cross-sectional (bottom) and top view (top) views of a gold-tin solder magnetron sputtered on the bottom of a dug hole according to an embodiment of the present invention.

And S3, bonding the pre-prepared active chip 8 to the solder metal layer 7 in the deep hole 6, wherein the active layer of the active chip and the top silicon are at the same horizontal plane.

Before performing step S3, an active chip needs to be prepared: selecting a III-V active photoelectric device epitaxial wafer, wherein the substrate is a highly doped substrate, and the doping type is consistent with that of SOI back silicon; and thinning the back substrate of the epitaxial wafer, wherein the thickness of the epitaxial wafer is deep hole depth-a and the thickness of the gold-tin solder, and a is [0.25, 0.9], manufacturing a back metal electrode after thinning the back substrate, and obtaining the active chip by utilizing dissociation or dicing by a dicing saw. The device types of the active optoelectronic device include, but are not limited to, a semiconductor laser, a photodetector, and an optoelectronic modulator. The substrate of the epitaxial wafer of the active photoelectric device adopts a highly doped substrate, and the doping type is consistent with that of the silicon on the back surface of the SOI. Preferably, the active chip employed herein is an InGaAs semiconductor laser chip.

After the active chip is prepared, step S3 is executed, the active chip 8 is bonded to the solder metal layer 7 in the deep hole 6 by using eutectic bonding technology, the active chip active layer 9 and the top silicon are in the same horizontal plane, and the top silicon 3 and the top electrode of the active chip 8 are connected through the solder metal layer 7. Fig. 6 is a schematic cross-sectional (bottom) and top (top) view of a eutectic bonded active chip according to an embodiment of the present invention.

And S4, selectively growing silicon dioxide in the deep hole gap after the active chip is bonded, wherein the top of the grown silicon dioxide and the buried oxide layer are positioned on the same horizontal plane.

Specifically, by using an ultraviolet lithography mask and LPCVD deposition equipment, silicon dioxide 10 is selectively grown to fill deep hole gaps after bonding of an active chip, and the top of the grown silicon dioxide and the buried oxide layer are in the same horizontal plane. Fig. 7 is a schematic diagram of a cross-section (bottom) and a top view (top) of a deep via gap after silicon dioxide deposition according to an embodiment of the present invention.

And S5, selectively growing an amorphous silicon layer 11 at the gap between the top silicon and the passive optical device by using an ultraviolet lithography mask and a coating technology, wherein the thickness of the amorphous silicon layer 11 is consistent with that of the top silicon.

Fig. 8 is a schematic cross-sectional (bottom) and top (top) views of an amorphous silicon layer grown according to an embodiment of the present invention.

S6, manufacturing interconnection optical waveguide 12 on the active chip 8 and the amorphous silicon layer 11 to realize optical interconnection of the active chip and the passive optical device;

specifically, the interconnection optical waveguide 12 is manufactured on the active chip 8 and the amorphous silicon layer 11 by using ultraviolet lithography and RIE etching technology, so as to realize optical interconnection of the active chip and the passive optical device. Fig. 9 is a schematic structural diagram after an active chip interconnection optical waveguide is manufactured and optical interconnection between an active chip and a passive optical device is implemented according to an embodiment of the present invention.

S7, forming an electrode contact hole 14 above the interconnection optical waveguide 12 of the active chip 8, and depositing a metal electrode 15 in the electrode contact hole.

Specifically, in step S7, electrode contact holes 14 are made above the interconnection optical waveguide 12 of the active chip 8 using RIE etching technique. And depositing a P-type metal electrode in the contact hole by using electron beam evaporation equipment to finish the preparation. The material of the P-type metal electrode is Ti/Pt/Au. FIG. 11 is a schematic diagram of a cross-sectional view (bottom view) and a top view (top view) of a metal electrode opening etched in a silicon dioxide layer over an active chip according to an embodiment of the present invention; fig. 12 is a schematic cross-sectional (bottom) and top (top) view of a structure for fabricating an active chip metal electrode according to an embodiment of the present invention.

In one embodiment, before step S7, the method further comprises:

and growing a layer of silicon dioxide material with the thickness of 300-800 nm on the top silicon by utilizing a PECVD deposition technology and a deposition technology to be used as a passivation layer of the active chip. FIG. 10 is a schematic diagram of a cross-sectional view (bottom view) and a top view (top view) of an SOI substrate having a silicon dioxide passivation layer deposited thereon according to an embodiment of the present invention;

in summary, the embodiments of the present invention provide a silicon-based optoelectronic monolithic heterogeneous integration method, which is based on the steps of etching and digging, eutectic implantation, film coating and filling, and alignment processes, and the like, and the epitaxial full structures of chips of different material systems are implanted onto a single chip to manufacture waveguides for optical interconnection, without complex secondary epitaxy and substrate transfer, and the method has the advantages of simple process, good reliability, and fully retaining the original performance of the chip.

The embodiments of the present invention can be arbitrarily combined to achieve different technical effects.

Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.