CN113534341A

CN113534341A - Tunable waveguide grating filter based on femtosecond laser direct writing and manufacturing method thereof

Info

Publication number: CN113534341A
Application number: CN202010315538.7A
Authority: CN
Inventors: 訾幸壮; 尹小杰; 杨堃; 赵青; 李彩云; 孙静雯; 常夏森
Original assignee: HENAN SHIJIA PHOTONS TECHNOLOGY CO LTD
Current assignee: HENAN SHIJIA PHOTONS TECHNOLOGY CO LTD
Priority date: 2020-04-21
Filing date: 2020-04-21
Publication date: 2021-10-22
Anticipated expiration: 2040-04-21
Also published as: CN113534341B

Abstract

The invention discloses a tunable waveguide grating filter based on femtosecond laser direct writing and a manufacturing method thereof, wherein the tunable waveguide grating filter comprises a wafer substrate, an upper cladding layer is arranged at the upper part of the wafer substrate, an electrode layer and a lead layer are sequentially arranged at the upper part of the upper cladding layer, and the widths of the electrode layer and the lead layer are both smaller than the width of the upper cladding layer; and a waveguide core layer is arranged in the upper cladding layer, and a waveguide grating which is directly written by femtosecond laser is arranged on the waveguide core layer. The invention combines the quartz-based PLC optical waveguide technology with the femtosecond laser direct writing, improves the prior process and reduces the development and process cost; various grating filters can be manufactured on the wafer, wavelength tuning can be achieved through the electrode layer, and flexibility of the optical chip system is improved; by controlling the power of the femtosecond laser, the width of a scanning area, the repeated scanning times and the like, the size of the refractive index change can be controlled, and the accurate control of grating parameters is realized.

Description

Tunable waveguide grating filter based on femtosecond laser direct writing and manufacturing method thereof

Technical Field

The invention belongs to the technical field of integrated photoelectron, and particularly relates to a tunable waveguide grating filter based on femtosecond laser direct writing and a manufacturing method thereof.

Background

With the rapid development of services such as a 5G technology, internet +, artificial intelligence, cloud computing and the like, the demand of the services on transmission network bandwidth capacity is greatly increased, and the development of optical communication and optical sensing technologies is greatly promoted. One important device in the field of optical communications and optical sensing is a fiber grating filter. In a wdm system, an optical filter is a key device for processing a specific channel optical signal, and generally requires low insertion loss and high out-of-band rejection ratio. In a fiber optic sensing system, where the fiber grating is subjected to an external field (e.g., temperature or stress), the grating period or effective index of refraction of the fiber mode may change, which changes the resonant wavelength of the grating. In addition, the fiber grating has the advantages of small volume, corrosion resistance, electromagnetic interference resistance and the like, so that the fiber grating is widely applied.

However, communication networks have evolved to an era centered on data centers, and optical interconnections have been a necessary trend. Semiconductor manufacturing processes are approaching physical limits gradually, and transmission resistance in short-distance communication inside and outside a chip is increased; at the same time, the reduction of the electrical interconnect pitch is highly susceptible to parasitic capacitance. For optical interconnects, optical signals can be transmitted without interference and at higher rates. Like integrated circuits, integrated circuits are also made up of a variety of basic optical elements. Compared with an optical system consisting of discrete optical elements, the integrated optical path system has smaller size and stability, the optical filter is a key unit of the integrated optical path system, and the tunable grating filter can bring greater flexibility to the optical system. Due to the rapid development of semiconductor technology, the micro-electronic technologies such as photolithography, ion beam etching, Plasma Enhanced Chemical Vapor Deposition (PECVD) and the like have made great progress, resulting in a novel fabrication process of waveguide grating based on Planar Lightwave Circuit (PLC).

At present, there are two main methods for manufacturing gratings on a wafer:

etching: when the etching method is adopted, the current limit etching width is 1um (the etching depth is 4 um), the yield is extremely low, and low-order Bragg gratings cannot be manufactured to meet certain special requirements;

ultraviolet exposure: although the photosensitivity of an optical waveguide (wafer) can be enhanced by a method such as hydrogen loading, the improvement of photosensitivity is very limited, and although the accuracy of manufacturing a grating is very high, the manufacturing cost of the grating is high and the modulation depth (refractive index variation) is very small, and therefore a grating with high reflectivity cannot be manufactured.

Disclosure of Invention

The invention provides a tunable waveguide grating filter based on femtosecond laser direct writing and a manufacturing method thereof, aiming at the problems of low process precision, high cost and low yield caused by poor product consistency in the prior art of manufacturing waveguide gratings on quartz-based PLC wafers, and solving the problem that low-order Bragg gratings or high-reflectivity gratings cannot be manufactured on the prior wafers.

In order to solve the technical problems, the technical scheme adopted by the invention is as follows:

a tunable waveguide grating filter based on femtosecond laser direct writing comprises a wafer substrate, wherein an upper cladding layer is arranged on the upper part of the wafer substrate, an electrode layer and a lead layer are sequentially arranged on the upper part of the upper cladding layer, and the widths of the electrode layer and the lead layer are both smaller than the width of the upper cladding layer; and a waveguide core layer is arranged in the upper cladding layer, and a waveguide grating which is directly written by femtosecond laser is arranged on the waveguide core layer.

The wafer substrate is made of quartz glass; the waveguide core layer is made of germanium-doped silicon dioxide; the upper cladding is made of silicon dioxide doped with boron and phosphorus; the electrode layer is made of chromium and gold; the lead layer is made of titanium and tungsten.

The refractive indexes of the wafer substrate and the upper cladding are smaller than that of the waveguide core layer, and the refractive indexes of the waveguide grating are changed periodically.

The waveguide core layer is arranged in the middle of the upper cladding layer, and the electrode layer and the lead layer are both arranged right above the waveguide core layer.

The waveguide grating is a bragg grating or a long period grating.

The period of the waveguide grating is uniform or chirped, and the apodized version of the waveguide grating is apodized or not.

A manufacturing method of a tunable waveguide grating filter based on femtosecond laser direct writing comprises the following steps:

s1, preprocessing the surface of the wafer substrate;

s2, manufacturing a waveguide core layer on the wafer substrate by adopting a PECVD method;

s3, annealing the wafer obtained in the step S2;

s4, preprocessing the surface of the waveguide core layer;

s5, manufacturing a hard mask layer on the upper surface of the waveguide core layer by adopting a PECVD method;

s6, spin-coating a first photoresist layer on the hard mask layer, and manufacturing a mask pattern of the waveguide core layer on the first photoresist layer by adopting a photoetching method;

s7, etching the hard mask layer according to the mask pattern of the waveguide core layer by utilizing an ICP (inductively coupled plasma) etching principle, and then removing the first photoresist layer on the hard mask layer by utilizing corrosive liquid;

s8, etching the waveguide core layer on the wafer substrate by utilizing an ICP (inductively coupled plasma) etching principle to obtain a new waveguide core layer;

s9, removing the hard mask layer on the new waveguide core layer by utilizing an ICP etching principle;

s10, manufacturing an upper cladding on the wafer substrate and the new waveguide core layer by using a PECVD method, and carrying out high-temperature reflow treatment on the upper cladding;

s11, focusing the femtosecond laser to a new waveguide core layer by using a microscope to write the waveguide grating, and irradiating by using the femtosecond laser to change the refractive index of the waveguide core layer;

s12, spin-coating a second photoresist layer on the upper cladding layer, and manufacturing a mask pattern of the electrode layer on the second photoresist layer by adopting a photoetching method;

s13, manufacturing an electrode layer on the second photoresist layer and the upper cladding layer by using evaporation equipment;

s14, stripping the second photoresist layer by adopting an ultrasonic method to obtain a new electrode layer;

s15, spin-coating a third photoresist layer on the upper cladding layer and the new electrode layer, and manufacturing a mask pattern of the lead layer on the third photoresist layer by adopting a photoetching method;

s16, manufacturing lead layers on the third photoresist layer and the new electrode layer by using a magnetron sputtering instrument;

and S17, stripping the third photoresist layer by an ultrasonic method, and then completing the manufacture of the tunable waveguide grating filter.

The invention has the beneficial effects that:

the quartz-based PLC optical waveguide technology is combined with femtosecond laser direct writing, the existing process is improved, and the development and process cost is reduced; various grating filters can be manufactured on the wafer, wavelength tuning can be achieved through the electrode layer, and flexibility of the optical chip system is improved; in addition, the quartz glass has the advantages of good heat resistance, high transparency and the like, so that the manufactured grating filter has good consistency; the refractive index change can be controlled by controlling the power of the femtosecond laser, the width of a scanning area, the repeated scanning times and the like, so that the precise control of grating parameters is realized; the invention has the advantages of high process precision, high side die rejection ratio, low cost, good product consistency and suitability for large-scale production.

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 described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is a schematic structural diagram of the present invention.

FIG. 2 is a flow chart of a manufacturing method of the present invention.

FIG. 3 is a schematic view of a wafer substrate.

Fig. 4 is a schematic diagram of the step S2.

Fig. 5 is a schematic diagram of the step S5.

Fig. 6 is a schematic diagram of spin-coating a photoresist layer in step S6.

Fig. 7 is a schematic diagram of a mask pattern for fabricating the waveguide core layer in step S6.

Fig. 8 is a schematic diagram of the step S7.

Fig. 9 is a schematic diagram of the step S8.

Fig. 10 is a schematic diagram illustrating the manufacturing process of step S9.

Fig. 11 is a schematic diagram illustrating the manufacturing process of step S10.

Fig. 12 is a schematic diagram of spin-coating a photoresist layer in step S12.

Fig. 13 is a schematic diagram of the mask pattern for forming the electrode layer in step S12.

Fig. 14 is a schematic diagram illustrating the manufacturing process of step S13.

Fig. 15 is a schematic diagram illustrating the manufacturing process of step S14.

Fig. 16 is a diagram illustrating the spin-on of a photoresist layer in step S15.

Fig. 17 is a schematic diagram of a mask pattern for manufacturing the lead layer in step S15.

Fig. 18 is a schematic diagram illustrating the production in step S16.

Fig. 19 is a schematic diagram illustrating the production in step S17.

In the figure, 1 is a lead layer, 2 is an electrode layer, 3 is an upper cladding layer, 4 is a waveguide core layer, 5 is a wafer substrate, 6 is a hard mask layer, 7 is a first photoresist layer, 8 is a second photoresist layer, and 9 is a third photoresist layer.

Detailed Description

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 only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without inventive effort based on the embodiments of the present invention, are within the scope of the present invention.

Example 1: a tunable waveguide grating filter based on femtosecond laser direct writing is disclosed, as shown in fig. 1, and comprises a wafer substrate 5, wherein an upper cladding 3 is arranged on the upper part of the wafer substrate 5, so that light is totally reflected on the boundary of a core layer, and the light wave is confined in a dielectric film and is transmitted; the upper part of the upper cladding 3 is sequentially provided with an electrode layer 2 and a lead layer 1, the widths of the electrode layer 2 and the lead layer 1 are both smaller than the width of the upper cladding 3, an electrode region is arranged in the electrode layer 2, the electrode region corresponds to the waveguide grating in the waveguide core layer 4, and the electrode region is only used for heating the waveguide grating region; the middle part of the upper cladding 3 is provided with a waveguide core layer 4, the waveguide core layer 4 is in contact with a wafer substrate 5, and the wafer substrate 5 is used as a lower cladding to ensure that light is totally reflected on the boundary of the core layer so as to limit the light wave in a dielectric film for propagation; and a waveguide grating which is directly written by femtosecond laser is arranged on the waveguide core layer 4 and has a filtering effect. The refractive index of the waveguide core layer 4 is larger than that of the wafer substrate 5 and that of the upper cladding layer 3, so that the total reflection principle is satisfied, and bound light can be conveniently transmitted along the waveguide core layer 4.

The wafer substrate 5 is made of quartz glass, the refractive index of the quartz glass is 1.4448, and the quartz substrate is made of a transparent material, so that the direct writing alignment of a subsequent femtosecond laser is facilitated; the waveguide core layer 4 is made of germanium-doped silicon dioxide, and the refractive index of the germanium-doped silicon dioxide is 1.4651-1.4811; the upper cladding 3 is made of silicon dioxide doped with low-concentration boron and phosphorus, and the refractive index of the silicon dioxide doped with low-concentration boron and phosphorus is 1.4448; the electrode layer 2 is made of chromium and gold, the lead layer 1 is made of titanium and tungsten, in the embodiment, the thicknesses of the chromium and the gold are respectively 50 nm and 500 nm, the thicknesses of the titanium and the tungsten are respectively 50 nm and 500 nm, and in a specific production process, the thicknesses of the materials in the electrode layer 2 and the lead layer 1 can be manufactured according to specific production requirements.

The refractive index of the waveguide grating changes periodically, different grating periods correspond to different resonant wavelengths, the electrode layer 2 is arranged in the middle of the waveguide grating area, and the electrode layer 2 adjusts the resonant wavelength of the waveguide grating filter through a thermo-optic effect.

The waveguide grating is a Bragg grating or a long-period grating; the period of the waveguide grating is uniform or chirped; the apodized type of waveguide grating 4 includes non-apodized or apodized.

Example 2: a method for manufacturing a tunable waveguide grating filter based on femtosecond laser direct writing, as shown in fig. 2, includes the following steps:

s1, as shown in fig. 3, pre-treating the surface of the wafer substrate 5;

firstly, putting the wafer substrate 5 into a mixed solution of hydrochloric acid and hydrogen peroxide, carrying out ultrasonic treatment for 30 minutes, then putting the wafer substrate into deionized water, carrying out ultrasonic treatment for 15 minutes, and finally drying the wafer substrate 5.

S2, as shown in fig. 4, fabricating the waveguide core layer 4 on the wafer substrate 5 by PECVD;

the PECVD refers to a plasma enhanced chemical vapor deposition method, and relevant parameters of PECVD equipment are set as follows: the air pressure of the chamber is 350-; the thickness of the waveguide core layer 4 may be set to 4-8 μm.

S3, annealing the wafer obtained in the step S2;

the annealing temperature of the annealing treatment is 1000-1200 ℃, the annealing time is 4-5 hours, and the lattice defects and the internal stress of the wafer can be eliminated through the high-temperature annealing treatment, so that the silicon dioxide layer becomes compact and uniform, and the yield and the consistency of the product are improved; the wafer refers to a product after the waveguide core layer 4 is manufactured on the wafer substrate 5.

S4, pretreating the surface of the waveguide core layer 4, and respectively performing ultrasonic treatment for 10 minutes by using deionized water and alcohol.

S5, as shown in fig. 5, fabricating a hard mask layer 6 on the upper surface of the waveguide core layer 4 by using a PECVD method;

the hard mask layer 6 is a polysilicon mask layer deposited by a PECVD method, so that the waveguide pattern can be etched subsequently.

S6, as shown in fig. 6-7, spin-coating a first photoresist layer 7 on the hard mask layer 6, and fabricating a mask pattern of the waveguide core layer 4 on the first photoresist layer 7 by using a photolithography method;

firstly, a first photoresist layer 7 is spin-coated on a hard mask layer 6, and then the hard mask layer is placed in an oven at 80 ℃ for baking; finally, the first photoresist layer 7 is exposed and developed by using a photoetching plate with a pattern manufactured in advance, and two sides of the first photoresist layer 7 are removed to obtain a mask pattern of the waveguide core layer 4; the first photoresist layer 7 may use a negative photoresist or a positive photoresist.

S7, as shown in fig. 8, etching the hard mask layer 6 according to the mask pattern of the waveguide core layer 4 by using the ICP etching principle, and then removing the first photoresist layer 7 on the hard mask layer 6 by using an etching solution;

the corrosive liquid is a low-concentration sodium hydroxide solution.

S8, as shown in fig. 9, etching the waveguide core layer 4 on the wafer substrate 5 by using the ICP etching principle to obtain a new waveguide core layer 4;

the width of the waveguide core layer 4 is consistent with that of the hard mask layer 6, and the waveguide core layer can be conveniently etched to obtain the core layer with the same width.

S9, as shown in fig. 10, removing the hard mask layer 6 on the new waveguide core layer 4 by using the ICP etching principle;

s10, as shown in fig. 11, fabricating an upper cladding layer 3 on the wafer substrate 5 and the waveguide core layer 4 by using a PECVD method, and performing a high temperature reflow process on the upper cladding layer 3;

in this embodiment, the thickness of the upper cladding is 20 um, the material of the upper cladding 3 is silica doped with low-concentration boron and phosphorus, and the refractive index of the silica doped with low-concentration boron and phosphorus is 1.4448;

the parameters of the PECVD equipment are set as follows: the pressure of the chamber is 2600-3100 mTorr, the temperature is 330-380 ℃, the radio frequency power of the lower electrode is 1800-2100W, the flow rate of the mixed gas of borane and nitrogen is 120-150 sccm, the molar fraction of borane in the mixed gas is 8-12%, the flow rate of the mixed gas of phosphine and nitrogen is 36-53sccm, and the molar fraction of phosphine in the mixed gas is 8-13%; the high-temperature reflux temperature is 950 ℃ and 1200 ℃, the reflux time is 7-10 hours, and the high-temperature reflux treatment can ensure that the upper cladding 3 has high deposition rate, good film-forming quality, fewer pinholes and difficult cracking.

S11, focusing the femtosecond laser on the new waveguide core layer 4 by using a microscope to write the waveguide grating, and irradiating by using the femtosecond laser to change the refractive index of the waveguide core layer 4;

firstly, fixing a wafer on a three-dimensional electric translation table, focusing femtosecond laser on a new waveguide core layer 4 by using a microscope to write a waveguide grating, and irradiating the new waveguide core layer 4 in an irradiation area by using the femtosecond laser to change the refractive index of the new waveguide core layer 4 so as to obtain the waveguide grating with a corresponding period and length; the position of the written waveguide grating can be controlled by a three-dimensional electric translation table, and the length of the manufactured waveguide grating is scanned by moving a femtosecond laser or a wafer;

the waveguide grating is a Bragg grating (FBG) or a Long Period Grating (LPG); the refractive index of the waveguide core layer 4 is larger than the refractive indices of the wafer substrate 5 and the upper cladding layer 3.

S12, as shown in fig. 12-13, spin-coating a second photoresist layer 8 on the upper cladding layer 3, and forming a mask pattern of the electrode layer 2 on the second photoresist layer 8 by photolithography;

firstly, a second photoresist layer 8 is spin-coated on the upper cladding layer 3, then the upper cladding layer is placed in an oven with the temperature of 80 ℃ for baking, finally, the second photoresist layer 8 is exposed and developed, and the middle part of the second photoresist layer 8 is removed to obtain a mask pattern of the electrode layer 2.

S13, as shown in fig. 14, forming the electrode layer 2 on the second photoresist layer 8 and the upper cladding layer 3 by using an evaporation apparatus;

using an evaporation device to sequentially evaporate a layer of chromium (Cr) and gold (Au) to manufacture an electrode layer 2; in this example, the thickness of the chromium is 50 nm to increase the adhesion of gold to other metals, and the thickness of gold is 500 nm.

S14, as shown in fig. 15, ultrasonically stripping the second photoresist layer 8 to obtain a new electrode layer 2;

s15, as shown in fig. 16-17, spin-coating a third photoresist layer 9 on the upper cladding layer 3 and the new electrode layer 2, and forming a mask pattern of the lead layer 1 on the third photoresist layer 9 by photolithography;

first, a third photoresist layer 9 is spin-coated on the upper cladding layer 3 and the electrode layer 2, then the upper cladding layer and the electrode layer are placed in an oven at 80 ℃ for baking, finally, the third photoresist layer 9 is exposed and developed, and the middle part of the third photoresist layer 9 is removed to obtain a mask pattern of the lead layer 1.

S16, as shown in fig. 18, manufacturing a lead layer 1 on the third photoresist layer 9 and the new electrode layer 2 by using a magnetron sputtering apparatus;

sputtering a layer of titanium (Ti) and tungsten (W) on the third photoresist layer 9 and the new electrode layer 2 in sequence by using a magnetron sputtering apparatus to manufacture a lead layer 1, wherein in the embodiment, the thickness of the titanium is 50 nm, and the titanium has better adhesiveness with silicon dioxide; tungsten has a thickness of 500 nm, has a high melting point, and is not easily broken in electrode operation.

S17, as shown in fig. 19, the third photoresist layer 9 is stripped by ultrasonic method, and the tunable waveguide grating filter is completed.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.

Claims

1. A tunable waveguide grating filter based on femtosecond laser direct writing comprises a wafer substrate (5), and is characterized in that an upper cladding (3) is arranged on the upper portion of the wafer substrate (5), an electrode layer (2) and a lead layer (1) are sequentially arranged on the upper portion of the upper cladding (3), and the widths of the electrode layer (2) and the lead layer (1) are smaller than the width of the upper cladding (3); a waveguide core layer (4) is arranged in the upper cladding layer (3), and a waveguide grating which is directly written by femtosecond laser is arranged on the waveguide core layer (4).

2. The femtosecond laser direct writing based tunable waveguide grating filter according to claim 1, wherein the material of the wafer substrate (5) is quartz glass; the waveguide core layer (4) is made of silicon dioxide doped with germanium; the upper cladding (3) is made of silicon dioxide doped with boron and phosphorus; the electrode layer (2) is made of chromium and gold; the lead layer (1) is made of titanium and tungsten.

3. The tunable waveguide grating filter based on femtosecond laser direct writing according to claim 1 or 2, wherein the refractive index of the wafer substrate (5) and the upper cladding (3) is smaller than that of the waveguide core layer (4), and the refractive index of the waveguide grating varies periodically.

4. The tunable waveguide grating filter based on femtosecond laser direct writing according to claim 3, wherein the waveguide core layer (4) is arranged in the middle of the upper cladding layer (3), and the electrode layer (2) and the lead layer (1) are both arranged right above the waveguide core layer (4).

5. The femtosecond laser direct-writing based tunable waveguide grating filter according to claim 1 or 4, wherein the waveguide grating is a Bragg grating or a long period grating.

6. The femtosecond laser direct-write based tunable waveguide grating filter according to claim 5, wherein the period of the waveguide grating is uniform or chirped, and the apodization type of the waveguide grating is apodized or not.

7. A manufacturing method of a tunable waveguide grating filter based on femtosecond laser direct writing is characterized by comprising the following steps:

s1, preprocessing the surface of the wafer substrate (5);

s2, manufacturing a waveguide core layer (4) on the wafer substrate (5) by adopting a PECVD method;

s3, annealing the wafer obtained in the step S2;

s4, preprocessing the surface of the waveguide core layer (4);

s5, manufacturing a hard mask layer (6) on the upper surface of the waveguide core layer (4) by adopting a PECVD method;

s6, spin-coating a first photoresist layer (7) on the hard mask layer (6), and manufacturing a mask pattern of the waveguide core layer (4) on the first photoresist layer (7) by adopting a photoetching method;

s7, etching the hard mask layer (6) according to the mask pattern of the waveguide core layer (4) by utilizing an ICP (inductively coupled plasma) etching principle, and then removing the first photoresist layer (7) on the hard mask layer (6) by utilizing an etching solution;

s8, etching the waveguide core layer on the wafer substrate (5) by utilizing an ICP (inductively coupled plasma) etching principle to obtain a new waveguide core layer (4);

s9, removing the hard mask layer (6) on the new waveguide core layer (4) by utilizing an ICP (inductively coupled plasma) etching principle;

s10, manufacturing an upper cladding (3) on the wafer substrate (5) and the new waveguide core layer (4) by using a PECVD method, and carrying out high-temperature reflow treatment on the upper cladding (3);

s11, focusing the femtosecond laser to the new waveguide core layer (4) by using a microscope to write the waveguide grating, and irradiating by using the femtosecond laser to change the refractive index of the waveguide core layer (4);

s12, spin-coating a second photoresist layer (8) on the upper cladding layer (3), and manufacturing a mask pattern of the electrode layer (2) on the second photoresist layer (8) by adopting a photoetching method;

s13, manufacturing an electrode layer (2) on the second photoresist layer (8) and the upper cladding layer (3) by using evaporation equipment;

s14, stripping the second photoresist layer (8) by adopting an ultrasonic method to obtain a new electrode layer (2);

s15, a third photoresist layer (9) is spin-coated on the upper cladding layer (3) and the new electrode layer (2), and a mask pattern of the lead layer (1) is manufactured on the third photoresist layer (9) by adopting a photoetching method;

s16, manufacturing a lead layer (1) on the third photoresist layer (9) and the new electrode layer (2) by using a magnetron sputtering instrument;

and S17, stripping the third photoresist layer (9) by an ultrasonic method, and then finishing the manufacture of the tunable waveguide grating filter.

8. The method as claimed in claim 7, wherein the annealing temperature of the annealing process is 1000-1200 ℃ and the annealing time is 4-5 hours in step S2.