Integrated multiplexed multi-physics acousto-optic cross modulation waveguide and method of manufacture thereof

Abstract

The present application relates to a kind of integrated multiplexing multi-physical field acousto-optic cross modulation waveguide and its preparation method, the multi-physical field acousto-optic cross modulation waveguide includes: providing a support substrate;Dielectric layer on the support substrate;Piezoelectric film on the dielectric layer;Patterned metal structure on the piezoelectric film;The piezoelectric film is etched to form waveguide above the dielectric layer;The piezoelectric film is etched to form first grating coupler and second grating coupler on the support substrate;The patterned metal structure includes first piezoelectric transducer, second piezoelectric transducer, first modulation electrode and second modulation electrode;The first modulation electrode and second modulation electrode are located on the both sides of waveguide and parallel to waveguide.The present application limits sound field and light field to a waveguide, propagates two kinds of physical field simultaneously and modulates, can increase the density of information propagation, and increase the efficiency of modulation.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor devices, and specifically relates to an integrated and multiplexed multi-physics field acousto-optic intermodulation waveguide and its fabrication method. Background Technology

[0002] Lithium niobate is a powerful ferroelectric material. Polarized lithium niobate crystals possess a variety of properties, including piezoelectricity, ferroelectricity, photoelectricity, nonlinear optics, and thermoelectricity, as well as photorefractive effects. Lithium niobate crystals are among the most widely used new inorganic materials. They are excellent piezoelectric transducers, ferroelectric materials, and electro-optic materials. As an electro-optic material, lithium niobate plays a role in optical modulation in optical communication. Its single crystals are important materials for optical waveguides, mobile phones, piezoelectric sensors, optical modulators, and various other linear and nonlinear optical applications.

[0003] The electro-optic effect refers to the change in the refractive index of a crystal when an electric field is applied. Due to the strong pockels effect of lithium niobate, integrated optical waveguides based on lithium niobate show great potential in confined optical modes and optical modulation.

[0004] Meanwhile, lithium niobate performs excellently in piezoelectric transducers, and acoustic filters based on lithium niobate are already very mature. Lithium niobate waveguides also have many applications in delay lines and integrated acoustic circuits. Researchers generally apply the piezoelectric effect of lithium niobate to the excitation of sound waves, modulating the sound waves to directly achieve information modulation.

[0005] However, the acoustic and optical applications of lithium niobate are often separated, resulting in the use of only one dimension of the physical field for modulation, and the modulation efficiency cannot be optimized to a maximum value. The shape of lithium niobate waveguides allows them to confine both optical and acoustic fields. If the acoustic and optical fields could be confined to a single waveguide, and both physical fields could be propagated and modulated simultaneously, the density of information propagation and the modulation efficiency could be increased. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide an integrated and multiplexed multi-physics field acousto-optic intermodulation waveguide and its fabrication method. The waveguide confines the acoustic field and the optical field to one waveguide, and simultaneously propagates and modulates the two physical fields, which can increase the density of information propagation and increase the efficiency of modulation.

[0007] This invention provides an integrated and multiplexed multi-physics field acousto-optic intermodulation waveguide, the multi-physics field acousto-optic intermodulation waveguide comprising:

[0008] Provide a supporting substrate;

[0009] The dielectric layer located on the supporting substrate;

[0010] a piezoelectric thin film on the dielectric layer;

[0011] a patterned metal structure on the piezoelectric thin film;

[0012] etching the piezoelectric thin film to form a waveguide above the dielectric layer;

[0013] etching the piezoelectric thin film to form a first grating coupler and a second grating coupler on the support substrate; the patterned metal structure includes a first piezoelectric transducer, a second piezoelectric transducer, a first modulation electrode and a second modulation electrode; the first modulation electrode and the second modulation electrode are located on both sides of the waveguide and parallel to the waveguide.

[0014] Preferably, the material of the support substrate is silicon, and the electrical resistance is greater than 10000 Ω·cm.

[0015] Preferably, the material of the dielectric layer is silicon dioxide.

[0016] Preferably, the material of the piezoelectric thin film is selected from one of lithium niobate or lithium tantalate; the crystal cut type of the piezoelectric thin film is a rotated Y-cut, X-cut or Z-cut thin film.

[0017] Preferably, the material of the patterned metal structure is one or an alloy of several of aluminum, copper, gold, titanium, nickel, molybdenum, platinum.

[0018] Preferably, the first piezoelectric transducer and the second piezoelectric transducer include interdigital electrodes, a first bus bar and a second bus bar; wherein the first bus bar and the second bus bar form a rectangular structure for the electrical port of electro-acoustic excitation.

[0019] The acoustic mode excited in the piezoelectric transducer is consistent with the acoustic mode transmitted in the waveguide, which can be a zero-order horizontal shear wave mode, a Rayleigh mode or a longitudinal leaky mode; the optical mode transmitted in the waveguide includes but is not limited to TE00, TE10, TM00. The optical mode needs to satisfy that the volume integral of the overlapping effect with the acoustic mode is maximum.

[0020] Preferably, the first grating coupler and the second grating coupler are composed of a plurality of rectangular periodic waveguides on the piezoelectric thin film.

[0021] Preferably, the first modulation electrode and the second modulation electrode apply voltages of opposite potentials or opposite phases.

[0022] Further, the patterned metal structure further comprises a third modulation electrode and a fourth modulation electrode, and the third modulation electrode and the fourth modulation electrode need to apply opposite electric potential or opposite phase voltage. The voltage is direct current or alternating current sine signal, and the frequency is less than 1 kHz. The signal is added in the first grating coupler and the first piezoelectric transducer respectively, and after the voltage is applied, the signal phase in the second grating coupler and the second piezoelectric transducer is changed. If the signal is only applied in the first piezoelectric transducer, only mechanical waves propagate in the waveguide; if the signal is only applied in the first grating coupler, only electromagnetic waves propagate in the waveguide. If the signal is applied in the first grating coupler and the first piezoelectric transducer at the same time, mechanical waves and electromagnetic waves propagate in the waveguide at the same time, and stimulated Brillouin scattering occurs under suitable conditions.

[0023] The application further provides a preparation method of the integrated multiplexed multi-physical field acousto-optic intermodulation waveguide.

[0024] (1) preparing a piezoelectric film and a supporting substrate;

[0025] (2) ion implanting the piezoelectric film; and forming a dielectric layer on the supporting substrate;

[0026] (3) bonding the piezoelectric film and the supporting substrate;

[0027] (4) annealing to form a piezoelectric film-dielectric layer-supporting substrate structure; and then thinning the piezoelectric film;

[0028] (5) defining a waveguide pattern, and etching the piezoelectric film to form a waveguide structure;

[0029] (6) patterning a metal electrode, and depositing metal to form a patterned metal structure, so as to obtain the integrated multiplexed multi-physical field acousto-optic intermodulation waveguide.

[0030] Preferably, the ion implantation type in the step (2) is hydrogen ion or helium ion.

[0031] Preferably, the dielectric layer forming mode in the step (2) is chemical vapor deposition, physical vapor deposition or thermal evaporation.

[0032] Preferably, the bonding in the step (3) is as follows: before bonding, plasma activation is needed, the gas includes at least one of argon, oxygen and nitrogen, the energy range is 500 eV to 2000 eV, and at least one of an argon-rich layer, an oxygen-rich layer and a nitrogen-rich layer can be formed on the film surface after activation; the film surface after activation is directly bonded, and the bonding environment conditions include but are not limited to vacuum environment, normal temperature and normal pressure; and the bonding temperature is 20-700 ℃.

[0033] Preferably, the annealing in the step (4) is specifically: the annealing atmosphere is nitrogen, the annealing temperature is 500-1400 DEG C, and the annealing time is 1 min-24 h.

[0034] Preferably, the thinning in the step (4) is specifically: first using mechanical grinding to 5-8 mu m, using chemical mechanical polishing to grind to 200-1000 nm, and ensuring that the thin film surface roughness is less than 0.3 nm.

[0035] Advantages

[0036] The application has good application prospect by optimizing the waveguide design, propagating local mechanical wave and light wave in the waveguide, monolithic integrating the on-chip electro-acoustic transducer and grating coupler, enabling mechanical wave and light wave to be introduced to the on-chip simultaneously, limiting the sound field and light field to a waveguide, propagating two physical fields simultaneously and modulating, increasing the density of information propagation and the efficiency of modulation. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 It is a front view of the integrated multiplexed multi-physical field acousto-optic intermodulation waveguide of the application;

[0038] Figure 2 It is a top view of the integrated multiplexed multi-physical field acousto-optic intermodulation waveguide of the application;

[0039] Figure 3 It is a structure schematic view of the first bus bar and the second bus bar used by the application;

[0040] Figure 4 It is a structure schematic view of the interdigital electrode used by the application;

[0041] Figure 5 It is a top view of the modulation metal electrode and the waveguide used by the application;

[0042] Figure 6 It is a front view of the modulation metal electrode and the waveguide used by the application;

[0043] Figure 7 It is a structure schematic view of the grating coupler used by the application;

[0044] Figure 8 It is a schematic view of the waveguide used by the application;

[0045] Figure 9 It is a principle schematic view of the integrated multiplexed multi-physical field acousto-optic intermodulation waveguide of the application;

[0046] Figure 10 It is a preparation process flow chart of the integrated multiplexed multi-physical field acousto-optic intermodulation waveguide of the application;

[0047] Figure 11 This invention relates to the zero-order horizontal shear wave mode of the multi-physics field acousto-optic intermodulation waveguide integrated and reused in this invention.

[0048] Figure 12 This invention integrates and reuses the Rayleigh mode of a multi-physics field acousto-optic intermodulation waveguide.

[0049] Figure 13 This invention relates to the longitudinal leakage mode of the multi-physics field acousto-optic intermodulation waveguide integrated and reused in this invention.

[0050] Figure 14 This invention relates to the TE00 mode of a multi-physics field acousto-optic intermodulation waveguide that integrates and reuses multiplexing.

[0051] Figure 15 This invention relates to the TE10 mode of a multi-physics field acousto-optic intermodulation waveguide that is integrated and reused in this invention.

[0052] Figure 16 This invention relates to the TM00 mode of a multi-physics field acousto-optic intermodulation waveguide that integrates and reuses multiplexing. Detailed Implementation

[0053] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0054] Example 1

[0055] This embodiment proposes an integrated and multiplexed multi-physics field acousto-optic intermodulation waveguide (such as... Figure 1 , Figure 2 As shown), the structure includes: a supporting substrate;

[0056] Provide a supporting substrate;

[0057] The dielectric layer located on the supporting substrate;

[0058] A piezoelectric thin film located on the dielectric layer;

[0059] Patterned metal structures located on the piezoelectric thin film;

[0060] The piezoelectric thin film is etched to form a waveguide over the dielectric layer;

[0061] The piezoelectric film is etched to form a first grating coupler and a second grating coupler on the support substrate; the patterned metal structure includes a first piezoelectric transducer, a second piezoelectric transducer, a first modulation electrode and a second modulation electrode; the first modulation electrode and the second modulation electrode are located on both sides of the waveguide and parallel to the waveguide.

[0062] The piezoelectric transducer (including a first piezoelectric transducer and a second piezoelectric transducer) can realize the conversion of signals from electrical signals to mechanical waves, and also can realize the conversion of signals from mechanical waves to electrical signals. It includes interdigital electrodes, a first bus bar and a second bus bar; wherein the first bus bar and the second bus bar form a rectangular structure for electrical port of electroacoustic excitation (such as Figure 3 shown); the interdigital electrodes are arranged by alternating voltage and ground electrode cycles. Define the distance between the centers of two adjacent electrodes as λ, λ is in the range of 500 nm to 5 um, and define the distance between the two bus bars as Wa, which is in the range of 5 um to 50 um (such as Figure 4 shown).

[0063] The waveguide width W is in the range of 200 nm to 5 um, the metal modulation electrode of the waveguide is parallel to the waveguide, the distance D between the modulation electrode and the waveguide is in the range of 500 nm to 2 um, the waveguide height H is in the range of 100 nm to 600 nm, and the height of the modulation metal electrode is in the range of 200 nm to 2 um (such as Figure 5 , Figure 6 shown).

[0064] The material of the patterned metal structure can include one of aluminum, copper, gold, titanium, nickel, molybdenum, platinum, or an alloy material composed of two of the above materials or a multi-layer electrode.

[0065] The material of the piezoelectric film can be selected from one of lithium niobate or lithium tantalate; the crystal cut type of the piezoelectric film is a rotated Y-cut, and the corresponding Euler angle is (0, -β, 0), or an X-cut, and the corresponding Euler angle is (α, -90, -90), where α is an arbitrary angle; or a Z-cut film, and the corresponding Euler angle is (α, 0, 0).

[0066] The material of the dielectric film is silicon dioxide;

[0067] The material of the support substrate is silicon, and the resistance is greater than 10000 Ω·cm.

[0068] The thickness of the patterned metal structure is between 50 nm and 300 nm, the thickness of the piezoelectric film is between 200 nm and 800 nm, and the thickness of the dielectric layer is between 0 and 5 um.

[0069] The acoustic mode excited in the piezoelectric transducer is consistent with the acoustic mode transmitted in the waveguide, which can be a zero-order horizontal shear wave mode, a Rayleigh mode or a longitudinal leaky mode, as shown in Figures 11-13 The optical mode transmitted in the waveguide includes but is not limited to TE00, TE10 or TM00, as shown in Figures 14-16 The optical mode needs to satisfy that the volume integral of the superposition with the acoustic mode is maximum.

[0070] As shown in Figure 7 The grating coupler (including the first grating coupler and the second grating coupler) is composed of a plurality of rectangular periodic waveguides on the piezoelectric film, the waveguide width Wg is in the range of 500 nm to 1200 nm, the waveguide repeat period Pg is in the range of 1 um to 3 um, the waveguide height Hg is in the range of 300 nm to 700 nm, and the number of unit repeats is 10 to 20.

[0071] The first modulation electrode and the second modulation electrode need to apply opposite potential or opposite phase voltage, and optionally, the third modulation electrode and the fourth modulation electrode need to apply opposite potential or opposite phase voltage. The voltage is direct current or alternating sinusoidal signal, and the frequency is less than 1 kHz. Signals are added in the first grating coupler and the first piezoelectric transducer respectively, and the phase of the signal in the second grating coupler and the second piezoelectric transducer changes after the voltage is applied. If the signal is only applied in the first piezoelectric transducer, only mechanical waves propagate in the waveguide; if the signal is only applied in the first grating coupler, only electromagnetic waves propagate in the waveguide. If the signal is applied in the first grating coupler and the first piezoelectric transducer at the same time, mechanical waves and electromagnetic waves propagate in the waveguide at the same time, and stimulated Brillouin scattering occurs under suitable conditions.

[0072] As shown in Figure 8 The waveguide structure top view can be rectangular or circular arc, and a segment taken in the circular arc; the radius of the circular arc is in the range of 50 um to 1000 um; the connection of the waveguide is a "Y" structure, and the included angle is in the range of 20° to 70°.

[0073] As shown in Figure 9 The acoustic signal is emitted and received by the piezoelectric transducer, and the optical signal is emitted and received by the grating coupler, wherein the acoustic signal path and the optical signal path intersect and overlap, and the acoustic signal and the optical signal propagate in the waveguide at the same time.

[0074] As shown in Figure 10 The process steps for manufacturing the acousto-optic interaction waveguide include:

[0075] ① Prepare piezoelectric film material and support substrate material;

[0076] ② Ion implantation of the piezoelectric film, ion type is hydrogen ion or helium ion; chemical vapor deposition or physical vapor deposition or thermal evaporation of a layer of dielectric layer on the supporting substrate;

[0077] ③ Bonding of two materials: plasma activation is required before bonding, the gas includes at least one of argon, oxygen, nitrogen, the energy range is 500eV~2000eV, at least one of argon-rich layer, oxygen-rich layer, nitrogen-rich layer can be formed on the surface of the film after activation; direct bonding of the film surface after activation, bonding environmental conditions include but are not limited to vacuum environment, normal temperature and pressure; further, the bonding temperature is 20-700℃;

[0078] ④ Annealing, stripping the piezoelectric material to form a piezoelectric film-dielectric layer-supporting substrate material, annealing atmosphere is nitrogen, annealing temperature is 500℃~1400℃, annealing time is 1min~24h; then thinning the film, first using mechanical grinding to 5μm~8μm, using chemical mechanical polishing to 200nm~1000nm, and ensuring that the surface roughness of the film is less than 0.3nm; forming the target material structure;

[0079] ⑤ Defining the waveguide pattern and etching it to form an etched waveguide structure;

[0080] ⑥ Patterning the metal electrode pattern and depositing a layer of metal to form a metal structure, forming a patterned metal structure, obtaining the integrated multiplexed multi-physical field acousto-optic intermodulation waveguide.

[0081] The process of defining the waveguide pattern includes:

[0082] ① Spin coating: depositing a layer of photoresist on the material;

[0083] ② Using electron beam lithography (EBL), or laser direct writing lithography, or ultraviolet lithography, patterning and developing the electrode;

[0084] ③ Using inductively coupled plasma etching (ICP) or ion beam etching (IBE) to etch the surface of the material;

[0085] ④ Using acetone or NMP solution immersion to remove excess photoresist.

[0086] The process of defining the patterned metal includes:

[0087] ① Spin coating: depositing a layer of photoresist on the material;

[0088] ② Using electron beam lithography (EBL), or laser direct writing lithography, or ultraviolet lithography, patterning and developing the electrode;

[0089] 3. Use electron beam evaporation metal plating process to deposit a layer of metal;

[0090] 4. Use acetone or NMP solution to soak to remove excess metal and photoresist.

Claims

1. An integrated multiplexed multi-physical field acousto-optic cross modulation waveguide, characterized by: The multi-physical field acousto-optic intermodulation waveguide comprises: a support substrate is provided; a dielectric layer is located on the support substrate; a piezoelectric thin film is located on the dielectric layer; a patterned metal structure is located on the piezoelectric thin film; the piezoelectric thin film is etched to form a waveguide above the dielectric layer; the piezoelectric thin film is etched to form a first grating coupler and a second grating coupler on the support substrate; the patterned metal structure comprises a first piezoelectric transducer, a second piezoelectric transducer, a first modulation electrode and a second modulation electrode; the first modulation electrode and the second modulation electrode are located on both sides of the waveguide and are parallel to the waveguide; the first piezoelectric transducer and the second piezoelectric transducer are used for modulating the acoustic field in the waveguide; the first modulation electrode and the second modulation electrode are used for modulating the optical field in the waveguide.

2. The multi-physics acousto-optic intermodulation waveguide of claim 1, wherein: The material of the support substrate is silicon, and the electrical resistance is greater than 10000 Ω·cm.

3. The multi-physics acousto-optic intermodulation waveguide of claim 1, wherein: The material of the dielectric layer is silicon dioxide.

4. The multi-physics acousto-optic intermodulation waveguide of claim 1, wherein: The material of the piezoelectric thin film is selected from one of lithium niobate or lithium tantalate; the crystal cut type of the piezoelectric thin film is a rotated Y-cut, X-cut or Z-cut thin film.

5. The multi-physics acousto-optic intermodulation waveguide of claim 1, wherein: The material of the patterned metal structure is one or an alloy of several of aluminum, copper, gold, titanium, nickel, molybdenum and platinum.

6. The multi-physics acousto-optic intermodulation waveguide of claim 1, wherein: The first piezoelectric transducer and the second piezoelectric transducer comprise interdigital electrodes, a first bus bar and a second bus bar; wherein the first bus bar and the second bus bar form a rectangular structure for the electrical port of electroacoustic excitation.

7. The multi-physics acousto-optic intermodulation waveguide of claim 1, wherein: The first grating coupler and the second grating coupler are composed of a plurality of rectangular periodic waveguides on the piezoelectric thin film.

8. The multi-physics acousto-optic intermodulation waveguide of claim 1, wherein: The first modulation electrode and the second modulation electrode apply opposite potentials or opposite phase voltages.

9. The multi-physics acousto-optic intermodulation waveguide of claim 1, wherein: The patterned metal structure further comprises a third modulation electrode and a fourth modulation electrode.

10. A preparation method of the integrated multiplexing multi-physical field acousto-optic intermodulation waveguide according to claim 1, comprising the following steps: (1) preparing a piezoelectric thin film and a support substrate; (2) ion implanting the piezoelectric thin film; and forming a dielectric layer on the support substrate; (3) bonding the piezoelectric thin film and the support substrate; (4) annealing to form a piezoelectric thin film-dielectric layer-support substrate structure; then thinning the piezoelectric thin film; (5) defining a waveguide pattern, and etching the piezoelectric thin film to form a waveguide structure; (6) patterning a metal electrode, and depositing metal to form a patterned metal structure, thereby obtaining the integrated multiplexing multi-physical field acousto-optic intermodulation waveguide.

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