CN117991448B - Method for integrating grating and lithium niobate thin film waveguide - Google Patents
Method for integrating grating and lithium niobate thin film waveguide Download PDFInfo
- Publication number
- CN117991448B CN117991448B CN202410407840.3A CN202410407840A CN117991448B CN 117991448 B CN117991448 B CN 117991448B CN 202410407840 A CN202410407840 A CN 202410407840A CN 117991448 B CN117991448 B CN 117991448B
- Authority
- CN
- China
- Prior art keywords
- lithium niobate
- thin film
- grating
- niobate thin
- wafer
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
- GQYHUHYESMUTHG-UHFFFAOYSA-N lithium niobate Chemical compound [Li+].[O-][Nb](=O)=O GQYHUHYESMUTHG-UHFFFAOYSA-N 0.000 title claims abstract description 141
- 239000010409 thin film Substances 0.000 title claims abstract description 91
- 238000000034 method Methods 0.000 title claims abstract description 50
- 239000010408 film Substances 0.000 claims abstract description 92
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims abstract description 66
- 238000005530 etching Methods 0.000 claims abstract description 37
- 239000000377 silicon dioxide Substances 0.000 claims abstract description 35
- 235000012239 silicon dioxide Nutrition 0.000 claims abstract description 31
- 238000005498 polishing Methods 0.000 claims abstract description 21
- 239000000126 substance Substances 0.000 claims abstract description 21
- 238000000151 deposition Methods 0.000 claims abstract description 20
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims abstract description 13
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 13
- 239000010703 silicon Substances 0.000 claims abstract description 13
- 238000001259 photo etching Methods 0.000 claims abstract description 11
- 238000005468 ion implantation Methods 0.000 claims description 18
- 238000009616 inductively coupled plasma Methods 0.000 claims description 8
- 238000000609 electron-beam lithography Methods 0.000 claims description 6
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 claims description 5
- 238000001459 lithography Methods 0.000 claims description 3
- 150000002500 ions Chemical class 0.000 claims description 2
- 230000003746 surface roughness Effects 0.000 abstract description 12
- 238000004519 manufacturing process Methods 0.000 abstract description 10
- 230000005540 biological transmission Effects 0.000 abstract description 9
- 230000008878 coupling Effects 0.000 abstract description 4
- 238000010168 coupling process Methods 0.000 abstract description 4
- 238000005859 coupling reaction Methods 0.000 abstract description 4
- 235000012431 wafers Nutrition 0.000 description 43
- 239000000463 material Substances 0.000 description 13
- 230000008569 process Effects 0.000 description 13
- 230000003287 optical effect Effects 0.000 description 10
- XKRFYHLGVUSROY-UHFFFAOYSA-N argon Substances [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 8
- 229910052681 coesite Inorganic materials 0.000 description 8
- 229910052906 cristobalite Inorganic materials 0.000 description 8
- 229910052682 stishovite Inorganic materials 0.000 description 8
- 229910052905 tridymite Inorganic materials 0.000 description 8
- 238000010586 diagram Methods 0.000 description 6
- 229910052786 argon Inorganic materials 0.000 description 5
- 239000007789 gas Substances 0.000 description 5
- 238000005516 engineering process Methods 0.000 description 4
- 230000005693 optoelectronics Effects 0.000 description 4
- 239000000758 substrate Substances 0.000 description 4
- 238000006243 chemical reaction Methods 0.000 description 3
- 239000013078 crystal Substances 0.000 description 3
- 238000009792 diffusion process Methods 0.000 description 3
- 238000010438 heat treatment Methods 0.000 description 3
- 239000001307 helium Substances 0.000 description 3
- 229910052734 helium Inorganic materials 0.000 description 3
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 description 3
- 229910052751 metal Inorganic materials 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- 239000000243 solution Substances 0.000 description 3
- JBRZTFJDHDCESZ-UHFFFAOYSA-N AsGa Chemical compound [As]#[Ga] JBRZTFJDHDCESZ-UHFFFAOYSA-N 0.000 description 2
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 2
- 229910001218 Gallium arsenide Inorganic materials 0.000 description 2
- GPXJNWSHGFTCBW-UHFFFAOYSA-N Indium phosphide Chemical compound [In]#P GPXJNWSHGFTCBW-UHFFFAOYSA-N 0.000 description 2
- 229910013641 LiNbO 3 Inorganic materials 0.000 description 2
- -1 argon ions Chemical class 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 239000000460 chlorine Substances 0.000 description 2
- 229910052801 chlorine Inorganic materials 0.000 description 2
- 238000005253 cladding Methods 0.000 description 2
- 238000005520 cutting process Methods 0.000 description 2
- 238000010894 electron beam technology Methods 0.000 description 2
- 239000010931 gold Substances 0.000 description 2
- 239000007769 metal material Substances 0.000 description 2
- 239000004065 semiconductor Substances 0.000 description 2
- WSMQKESQZFQMFW-UHFFFAOYSA-N 5-methyl-pyrazole-3-carboxylic acid Chemical compound CC1=CC(C(O)=O)=NN1 WSMQKESQZFQMFW-UHFFFAOYSA-N 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- 230000004913 activation Effects 0.000 description 1
- 238000001994 activation Methods 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 239000002872 contrast media Substances 0.000 description 1
- 230000032798 delamination Effects 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 239000003989 dielectric material Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000007772 electrode material Substances 0.000 description 1
- 238000000407 epitaxy Methods 0.000 description 1
- 239000000835 fiber Substances 0.000 description 1
- 230000004907 flux Effects 0.000 description 1
- 239000005350 fused silica glass Substances 0.000 description 1
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 1
- 229910052737 gold Inorganic materials 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- 229910000449 hafnium oxide Inorganic materials 0.000 description 1
- WIHZLLGSGQNAGK-UHFFFAOYSA-N hafnium(4+);oxygen(2-) Chemical compound [O-2].[O-2].[Hf+4] WIHZLLGSGQNAGK-UHFFFAOYSA-N 0.000 description 1
- 230000001939 inductive effect Effects 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 230000010354 integration Effects 0.000 description 1
- 238000005342 ion exchange Methods 0.000 description 1
- 238000002164 ion-beam lithography Methods 0.000 description 1
- 238000010884 ion-beam technique Methods 0.000 description 1
- 238000011031 large-scale manufacturing process Methods 0.000 description 1
- 238000003698 laser cutting Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 150000004767 nitrides Chemical class 0.000 description 1
- 239000012788 optical film Substances 0.000 description 1
- SIWVEOZUMHYXCS-UHFFFAOYSA-N oxo(oxoyttriooxy)yttrium Chemical compound O=[Y]O[Y]=O SIWVEOZUMHYXCS-UHFFFAOYSA-N 0.000 description 1
- 238000000059 patterning Methods 0.000 description 1
- 238000000206 photolithography Methods 0.000 description 1
- 238000000678 plasma activation Methods 0.000 description 1
- 238000001020 plasma etching Methods 0.000 description 1
- 239000010453 quartz Substances 0.000 description 1
- 239000012495 reaction gas Substances 0.000 description 1
- 238000002310 reflectometry Methods 0.000 description 1
- 238000000992 sputter etching Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 238000004381 surface treatment Methods 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
- 239000010936 titanium Substances 0.000 description 1
Abstract
The application provides a method for integrating a grating and a lithium niobate thin film waveguide, which comprises the following steps of photoetching and etching the grating on a silicon-based lithium niobate thin film wafer A; depositing a silicon dioxide dielectric film on the lithium niobate thin film layer with the grating and performing chemical mechanical polishing to planarize the surface and reduce the surface roughness; combining the wafer A and the ion-implanted lithium niobate wafer B, and simultaneously finishing bonding of the wafer A-B and stripping of the lithium niobate film at high temperature; forming a ridge waveguide on the top layer lithium niobate thin film; a silicon dioxide dielectric film is deposited on the ridge waveguide and the desired electrode is formed. The application can effectively integrate the grating and the lithium niobate thin film waveguide to form a compact photoelectric device, can achieve low transmission loss while obtaining high grating coupling efficiency, reduces manufacturing cost, and can be applied to the manufacture of various photoelectronic integrated devices.
Description
Technical Field
The invention relates to the technical field of semiconductors, in particular to a method for integrating a grating and a lithium niobate thin film waveguide.
Background
Bragg gratings (DBRs) are an essential component of functional optical devices with a variety of applications in communication, laser and sensing in various photonic platforms (fiber, silicon and other semiconductors). The combination of nonlinear optical and electro-optical properties of materials such as Bragg gratings and lithium niobate (LiNbO 3, LN) is particularly unique. Such as frequency conversion, optical switching, modulators and quantum optics can greatly benefit from the embedding of bragg grating reflectors and filter functions in lithium niobate thin film waveguides, as this can enable ultra-compact electrically modulated optical switches and modulators as well as compact nonlinear optics (e.g., optical parametric oscillators).
However, lithium niobate single crystal materials have no suitable lattice matching DBR material and are difficult to use epitaxial growth technology, so that gallium arsenide or indium phosphide DFB lasers widely used in the light market, for example, cannot be realized by bottom grating etching and secondary epitaxy technology like gallium arsenide or indium phosphide materials. At present, the integrated manufacturing technology of the grating and the lithium niobate thin film waveguide mainly comprises the following methods:
1) Titanium diffusion refraction, proton exchange refraction, femtosecond laser injection, or surface deposition of a heterogeneous material grating (see IEEE Photonics and Technology Letters, Vol. 14,2002, pp. 1430-1432, Applied Physics B Vol. 106, 2021, pp. 51-56, Electronic Letters Vol.35, 1999, pp. 1636 and Journal of Optics A, vol. 2, 2000, pp. 481-487). Although relatively easy to implement, these methods have the common disadvantage of small refractive index differences, low coupling efficiency, and inability to make compact and efficient devices. The diffusion and ion exchange at the same time also present process controllability challenges.
2) Gratings are etched on waveguides (see Optics Letters, vol. 39, 2014, pp. 371-374). The method adopts ion beam etching to deeply etch the gratings on the titanium-diffused waveguide, and utilizes the refractive index difference between air and lithium niobate, and the reflectivity of a plurality of grating pairs can reach more than 50 percent, so that the device is more compact. However, the method has very high requirements on the etching angle of the grating, and under the condition of etching an ideal angle of 90 degrees, the angle larger than 90+/-2 degrees can cause complete loss of waveguide light flux. The condition of large-scale production cannot be achieved.
3) The grating is etched in the sides of the ridge waveguide (see ACS Photonics, vol.8, 2021, pp. 2923-2930). The method adopts electron beam lithography waveguide to form zigzag edge, and the subsequent ion beam lithography beam forms grating on the side of the waveguide, but the method has high production cost and low efficiency, and the transmission loss is as high as 2.9dB/cm, so that the method can only be used on extremely short waveguide devices.
Disclosure of Invention
The application aims to provide an integration method of a lithium niobate thin film grating and a waveguide in a grating and waveguide integrated device. The method can reduce the difficulty of the integrated manufacture of the current grating and the lithium niobate thin film waveguide, and the high-contrast grating formed at the bottom of the lithium niobate thin film waveguide can reduce the transmission loss to below 0.1dB/cm while obtaining high reflection because the grating is not required to be formed on the ridge waveguide, thereby improving the photoelectric performance of the device, such as the frequency conversion efficiency, the intensity modulation efficiency of the modulator and the electro-optic effect of the waveguide device. The method can be widely applied to the manufacture of photoelectric devices of nonlinear materials, such as ultra-compact electric modulation optical switches and modulators and compact nonlinear optical parametric oscillators.
The application provides a method for integrating a grating and a lithium niobate thin film waveguide, which comprises the following steps:
providing a first wafer, wherein the first wafer comprises a first base layer, a first bonding layer and a first lithium niobate thin film which are sequentially arranged;
Forming a grating pattern on a first lithium niobate thin film of a first wafer by photoetching, and forming a grating layer by etching;
Depositing a first dielectric film on the grating layer and performing chemical mechanical polishing;
Providing a second wafer, wherein the second wafer layer comprises a second base layer and a second lithium niobate thin film which are sequentially arranged;
ion implantation is carried out on a second lithium niobate thin film of the second wafer, and a second dielectric film is deposited on the second lithium niobate thin film subjected to the ion implantation and chemical mechanical polishing is carried out;
Bonding a first dielectric film side of the first wafer and a second dielectric film side of the second wafer, and simultaneously peeling the second lithium niobate thin film from the second wafer;
Etching the stripped second lithium niobate thin film to planarize the surface of the second lithium niobate thin film;
Depositing chromium metal on the surface of the second lithium niobate thin film to be used as a mask for ridge etching;
photoetching the second lithium niobate thin film, and forming a ridge waveguide by etching;
A third dielectric film is deposited on the ridge waveguide, and then electrodes are deposited on both sides of the ridge waveguide.
Optionally, the thickness of the first lithium niobate thin film is 300-900nm, and the etching depth of the grating layer is 20-500nm.
Optionally, the first dielectric film thickness is not less than three times the grating layer thickness.
Optionally, after depositing a first dielectric film on the grating layer and performing a chemical mechanical polishing step, the first dielectric film has a thickness greater than 100nm;
After depositing a second dielectric film on the ion-implanted second lithium niobate thin film and performing a chemical mechanical polishing step, the second dielectric film has a thickness of greater than 100nm.
Optionally, in the step of ion implantation of the second lithium niobate thin film of the second wafer, the ion implantation depth is between 0.3 and 20 um.
Optionally, after the bonding step is performed on the first dielectric film side of the first wafer and the second dielectric film side of the second wafer, the total thickness of the first dielectric film and the second dielectric film is 200-1000 nm.
Optionally, the lithium niobate thin film of the first wafer is a silicon-based lithium niobate thin film.
Optionally, the lithography is electron beam lithography.
Optionally, the etching is inductively coupled plasma etching.
Optionally, the first dielectric film and the second dielectric film are silicon dioxide dielectric films.
The application also provides a method for integrating the grating and the lithium niobate thin film waveguide, which comprises the following steps:
(1) Forming a grating pattern on the silicon-based lithium niobate thin film wafer by using electron beam lithography, and then etching a grating structure on the lithium niobate thin film by using inductive coupling plasma etching to form a grating layer;
(2) Depositing a silicon dioxide dielectric film on the lithium niobate grating and performing chemical mechanical polishing to planarize the surface and reduce the surface roughness for bonding with the (B) wafer lithium niobate thin film waveguide layer;
(3) Depositing a silicon dioxide dielectric film on the lithium niobate wafer (B) subjected to ion implantation, performing chemical mechanical polishing to reduce the surface roughness, bonding the silicon dioxide dielectric film with the wafer (A) with the grating layer, forming SiO2-SiO2 bonds on the surface of the silicon dioxide dielectric film, and heating the silicon dioxide dielectric film to be more than 220C; to strengthen the bonding strength and realize the stripping of the ion implantation lithium niobate monocrystal film;
(4) Etching the surface of the stripped lithium niobate film by adopting argon ions to reduce the surface roughness, then depositing a chromium metal film on the surface of the stripped lithium niobate film as a mask for ridge etching, and etching a ridge waveguide on the lithium niobate film by using inductively coupled plasma etching after photoetching patterning;
(5) And depositing a silicon dioxide dielectric film on the lithium niobate thin film ridge waveguide, and then depositing required electrodes on two sides of the ridge to form the integrated photoelectric device.
Wherein said; and forming a grating structure on the silicon-based lithium niobate film (A), wherein the thickness of the lithium niobate film is 300-900nm, and the etching depth of the grating is 20-500nm, so as to form the bottom grating structure of the lithium niobate waveguide.
Wherein the other lithium niobate wafer (B) is subjected to ion implantation process, and the depth of the ion implantation damage layer can be between 0.3 and 20um.
When the integrated lithium niobate waveguide device is manufactured by adopting the method, a silicon dioxide dielectric film with the etching depth of more than 3 times of the grating is deposited on the grating layer of the wafer (A), and the waveform profile caused by the grating is removed by adopting a chemical mechanical polishing method, so that the surface of the silicon dioxide is flattened, and meanwhile, the surface roughness is less than 1nm (RMS).
When the integrated lithium niobate waveguide device is manufactured by adopting the method, a silicon dioxide dielectric film is deposited on the ion implantation surface of the lithium niobate wafer (B), and the thickness of the silicon dioxide film can be set according to the performance requirement of the device. The deposited silicon dioxide dielectric film reduces the surface roughness by chemical mechanical polishing means and reaches less than 1nm (RMS).
When the integrated lithium niobate waveguide device is manufactured by adopting the method, the silicon dioxide surfaces of the wafers (A) and (B) are directly bonded and slowly heated to the temperature higher than 220 ℃. The purpose is to strengthen the interfacial adhesion between SiO2 and SiO2 while stripping the ion-implanted lithium niobate film.
When the integrated lithium niobate waveguide device is manufactured by adopting the method, the surface roughness of the stripped lithium niobate film surface is reduced to 4-6nm (RMS) by argon ion etching, and the transmission loss of the waveguide is reduced.
The application is characterized in that a special grating forming and surface leveling process is carried out on a (A) silicon-based film lithium niobate substrate, and SiO2-SiO2 direct combination is realized by the special grating forming and surface leveling process and a (B) ion cutting film lithium niobate wafer, so that a lithium niobate waveguide device with a bottom grating is formed. The method avoids the requirement of forming the grating on the special profile of the ridge waveguide, can obviously reduce the cost of the integrated device, reduce the transmission loss of the waveguide and improve the photoelectric performance of the device. The method has universality and can be popularized and applied to the integrated manufacture of waveguides and grating structures of various materials.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the prior art, a brief description of the drawings is provided below, wherein it is apparent that the drawings in the following description are some, but not all, embodiments of the present invention. Other figures may be derived from these figures without inventive effort for a person of ordinary skill in the art.
FIG. 1 is a schematic diagram of a grating formed on (A) a silicon-based lithium niobate thin film and a silicon dioxide cap film planarized by chemical mechanical polishing;
FIG. 2 is a schematic diagram of depositing a silicon dioxide dielectric film on the ion implantation surface of a lithium niobate wafer (B);
FIG. 3 is a schematic diagram of the bonded wafers of (A) and (B);
FIG. 4 is a schematic illustration of a bonded high temperature treated lithium niobate thin film after delamination;
fig. 5 is a schematic diagram of the structure of an integrated grating and lithium niobate thin film waveguide optoelectronic device.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments of the present invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The technical scheme of the invention is described in detail below by specific examples. The following embodiments may be combined with each other, and some embodiments may not be repeated for the same or similar concepts or processes.
In one embodiment of the present application, a method for integrating a grating and a lithium niobate thin film waveguide is provided, comprising the steps of:
Forming a grating pattern on a first lithium niobate thin film of a first wafer by photoetching, and forming a grating layer by etching;
Depositing a first dielectric film on the grating layer and performing chemical mechanical polishing;
ion implantation is carried out on a second lithium niobate thin film of the second wafer, and a second dielectric film is deposited on the second lithium niobate thin film subjected to the ion implantation and chemical mechanical polishing is carried out;
Bonding a first dielectric film side of the first wafer and a second dielectric film side of the second wafer, and simultaneously stripping the second lithium niobate from the second wafer;
Etching the stripped second lithium niobate thin film to planarize the surface of the second lithium niobate thin film;
Depositing chromium metal on the surface of the second lithium niobate thin film to be used as a mask for ridge etching;
photoetching the second lithium niobate thin film, and forming a ridge waveguide by etching;
A third dielectric film is deposited on the ridge waveguide, and then electrodes are deposited on both sides of the ridge waveguide.
Optionally, the thickness of the first lithium niobate thin film is 300-900nm, and the etching depth of the grating layer is 20-500nm.
Optionally, the first dielectric film thickness is not less than three times the grating layer thickness.
Optionally, after depositing a first dielectric film on the grating layer and performing a chemical mechanical polishing step, the first dielectric film has a thickness greater than 100nm;
After depositing a second dielectric film on the ion-implanted second lithium niobate thin film and performing a chemical mechanical polishing step, the second dielectric film has a thickness of greater than 100nm.
Optionally, in the step of ion implantation of the second lithium niobate thin film of the second wafer, the ion implantation depth is between 0.3 and 20 um.
Optionally, after the bonding step is performed on the first dielectric film side of the first wafer and the second dielectric film side of the second wafer, the total thickness of the first dielectric film and the second dielectric film is between 200 nm and 1000 nm.
Optionally, the lithium niobate thin film of the first wafer is a silicon-based lithium niobate thin film.
Optionally, the lithography is electron beam lithography.
Optionally, the etching is inductively coupled plasma etching.
Optionally, the first dielectric film and the second dielectric film are silicon dioxide dielectric films
Referring to fig. 1 to 4, in another embodiment of the present application, a method for integrating a grating and a lithium niobate thin film waveguide is provided, which includes the following steps:
Step 1: as shown in fig. 1, first, electron beam lithography is performed on (a) a silicon-based thin film lithium niobate wafer 110-130 to form a surface pattern of a grating, and then an inductively coupled plasma etching is used to etch a grating structure on the lithium niobate thin film 130 to form a grating layer, wherein the silicon-based thin film is 110 layers, the silicon dioxide bonding layer is 120, and the lithium niobate thin film is 130.
In practice, the grating layer may be formed on a lithium niobate-based, quartz-based, fused quartz-based thin film lithium niobate wafer, or directly on a lithium niobate substrate.
In particular embodiments, the present application selects the lithium niobate thin film 130 as a high refractive grating material having a thickness of 300-900nm, while matching the light transmission range of the subsequent lithium niobate waveguide (fig. 3, 151). Other optical film materials, such as lithium tantalate, hafnium oxide, yttrium oxide, etc., may also be selected depending on the application requirements.
In the implementation, as the grating is formed on the flat surface, the photoetching process can be realized by adopting the process means such as nano imprinting, laser interference and the like besides the direct writing of the electron beam, and compared with the existing electron beam photoetching process, the photoetching process cost can be effectively reduced, and the manufacturing flexibility and the grating quality can be improved.
In practice, the grating etch uses an inductively coupled plasma process, and the chemically reactive gas may be chlorine-containing gases, argon and helium, or combinations of these gases. And etching the substrate to a depth ranging from 20 nm to 500nm to form a bottom grating structure of the lithium niobate waveguide.
Step two: with continued reference to fig. 1, in an embodiment of the present application, on the surface of (a) a lithium niobate thin film grating, a silicon dioxide dielectric film 141 is used as a low refractive index contrast material for the grating, 3 times of the silicon dioxide dielectric film 141 is deposited on the lithium niobate grating as an etched grating filling layer and a wafer surface bonding layer, and the dielectric film 141 is subjected to chemical mechanical polishing to planarize the surface and reduce the surface roughness so as to bond with (B) a lithium niobate thin film waveguide layer wafer (see fig. 2), wherein the surface roughness is controlled below 1nm to meet the subsequent SiO2-SiO2 direct bonding requirement;
Referring to fig. 2, in an embodiment of the present application, the wafer (B) is a lithium niobate single crystal material 150, wherein the depth of the helium ion implantation surface lithium niobate film 151 may be between 0.3 um and 20 um.
In a specific implementation, a silicon dioxide dielectric film 142 is deposited on the surface of the wafer (B) and subjected to chemical mechanical polishing, and the surface roughness of the silicon dioxide dielectric film is controlled below 1nm so as to achieve the subsequent SiO2-SiO2 direct bonding;
Step three: as shown in fig. 3, the silicon dioxide surfaces of wafers (a) and (B) are directly bonded and slowly heated to above 220 degrees.
In the heating process, the lithium niobate thin film 151 is separated from the donor lithium niobate wafer (B) as a lithium niobate single crystal thin film waveguide material, and the SiO2—sio2 interface bonding is strengthened in the heating process.
In the specific implementation, the SiO2 surface can strengthen the bonding strength of SiO2-SiO2 through surface treatment process means such as plasma activation, surface activation, atomic diffusion and the like.
In a specific implementation, the donor lithium niobate wafer can be reused after the film is peeled off (150) and the surface is polished by chemical machinery to reduce the manufacturing cost.
Step four: in an embodiment of the present application, fig. 4 shows a schematic diagram of the composition of silicon-based lithium niobate gratings Bao Mojing circle (a) and 151 lithium niobate thin film waveguide. The two lithium niobate thin films are separated by a silicon dioxide dielectric film 140 bonded by 141 and 142. The thickness of 140 is determined by the combination of grating coupling strength and the bottom cladding layer of the lithium niobate waveguide, and is not limited herein.
In practice, since the stripped 151 lithium niobate waveguide film has a considerable surface roughness, it is necessary to etch a lithium niobate surface material of more than 70nm with argon ions to reduce the surface roughness to 4-6nm (rms), reducing the transmission loss of the lithium niobate waveguide.
The combination of nonlinear optical and electro-optical properties of integrated gratings and materials such as lithium niobate (LiNbO 3, LN) is a very important optoelectronic device. The Bragg grating reflector and filter functions are embedded in the lithium niobate thin film waveguide, and ultra-compact electrically modulated optical switches and modulators and compact nonlinear optical devices can be realized. The method is characterized in that a special grating forming and surface leveling process is carried out on a silicon-based thin film lithium niobate substrate, and the special grating forming and surface leveling process is directly combined with a lithium niobate wafer of an ion-cut lithium niobate thin film to form a lithium niobate waveguide device with a bottom grating. The method avoids the requirement of forming the grating on the special profile of the ridge waveguide, obviously reduces the cost of the integrated device, reduces the transmission loss of the waveguide and improves the photoelectric performance of the device.
Fig. 5 is a schematic diagram of an optoelectronic device incorporating a grating and a lithium niobate waveguide. Referring to the specific manufacturing steps (1) - (4) above, a complete optoelectronic device integrating the grating and the lithium niobate waveguide is realized on the basis of the structure of fig. 5.
In a specific implementation, a metal film is deposited on the lithium niobate film 160 in fig. 5 as a hard mask layer for ridge etching, and for example, a metal material such as chromium metal may be used. The ridge pattern is then transferred to the metal film by photolithography and inductively coupled plasma etching, and finally the lithium niobate film is etched under a metal mask by inductively coupled plasma and ridge waveguides are formed. The chemical reaction gas may be chlorine-containing gas, argon and helium, and combinations of these gases. The lithium niobate ridge structure formed after etching is shown at 152 in fig. 5.
In a specific implementation, a silicon dioxide dielectric film 160 is deposited over the lithium niobate ridge structure 152 to form a cladding layer of the lithium niobate ridge waveguide to reduce waveguide transmission losses. Other oxide or nitride dielectric materials may also be employed depending on waveguide performance requirements.
In one possible implementation, the signal electrodes 170 and 171 may be deposited on both sides of the waveguide, and the signal electrode material may be a metal material such as gold (Au), which is not limited herein.
In a specific implementation, the light input end face and the light output end face are finally formed through grinding wheel cutting and end face polishing or laser cutting, and an anti-reflection film 180 is plated on the end face, so that the whole device is manufactured.
In the foregoing embodiments, the descriptions of the embodiments are emphasized, and for parts of one embodiment that are not described in detail, reference may be made to related descriptions of other embodiments.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and not for limiting the same; although the 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 scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the invention.
Claims (10)
1. A method of integrating a grating and a lithium niobate thin film waveguide, comprising the steps of:
providing a first wafer, wherein the first wafer comprises a first base layer, a first bonding layer and a first lithium niobate thin film which are sequentially arranged;
Forming a grating pattern on the first lithium niobate thin film of the first wafer by photoetching, and forming a grating layer by etching; depositing a first dielectric film on the grating layer and performing chemical mechanical polishing;
Providing a second wafer, wherein the second wafer layer comprises a second base layer and a second lithium niobate thin film which are sequentially arranged;
ion implantation is carried out on a second lithium niobate thin film of the second wafer, and a second dielectric film is deposited on the second lithium niobate thin film subjected to the ion implantation and chemical mechanical polishing is carried out;
Bonding a first dielectric film side of the first wafer and a second dielectric film side of the second wafer, and simultaneously peeling the second lithium niobate thin film from the second wafer;
Etching the stripped second lithium niobate thin film to planarize the surface of the second lithium niobate thin film;
Depositing chromium metal on the surface of the second lithium niobate thin film to be used as a mask for ridge etching;
photoetching the second lithium niobate thin film, and forming a ridge waveguide by etching;
A third dielectric film is deposited on the ridge waveguide, and then electrodes are deposited on both sides of the ridge waveguide.
2. The method of integrating a grating and a lithium niobate thin film waveguide of claim 1, wherein the first lithium niobate thin film has a thickness of 300-900nm and the grating layer has an etch depth of 20-500nm.
3. The method of integrating a grating and a lithium niobate thin film waveguide of claim 1, wherein the first dielectric film thickness is no less than three times the grating layer thickness.
4. The method of integrating a grating and a lithium niobate thin film waveguide of claim 1,
After depositing a first dielectric film on the grating layer and performing chemical mechanical polishing, the thickness of the first dielectric film is larger than 100nm;
After depositing a second dielectric film on the ion-implanted second lithium niobate thin film and performing a chemical mechanical polishing step, the second dielectric film has a thickness of greater than 100nm.
5. The method of integrating a grating and a lithium niobate thin film waveguide of claim 1, wherein in the step of ion implanting the second lithium niobate thin film of the second wafer, the ion implantation depth is between 0.3 and 20 um.
6. The method of integrating a grating and a lithium niobate thin film waveguide of claim 1,
And after the bonding step is carried out on one side of the first dielectric film of the first wafer and one side of the second dielectric film of the second wafer, the total thickness of the first dielectric film and the second dielectric film is 200-1000 nm.
7. The method of integrating a grating and a lithium niobate thin film waveguide of claim 1, wherein the lithium niobate thin film of the first wafer is a silicon-based lithium niobate thin film.
8. The method of integrating a grating and a lithium niobate thin film waveguide of claim 1, wherein the lithography is electron beam lithography.
9. The method of integrating a grating and a lithium niobate thin film waveguide of claim 1, the etching being an inductively coupled plasma etching.
10. The method of integrating a grating and a lithium niobate thin film waveguide of claim 1, the first dielectric film and the second dielectric film being silicon dioxide dielectric films.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202410407840.3A CN117991448B (en) | 2024-04-07 | Method for integrating grating and lithium niobate thin film waveguide |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202410407840.3A CN117991448B (en) | 2024-04-07 | Method for integrating grating and lithium niobate thin film waveguide |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN117991448A CN117991448A (en) | 2024-05-07 |
| CN117991448B true CN117991448B (en) | 2024-06-04 |
Family
ID=
Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001116943A (en) * | 1999-10-20 | 2001-04-27 | Fuji Xerox Co Ltd | Method for producing thin metal oxide film element |
| WO2004034108A1 (en) * | 2002-10-09 | 2004-04-22 | Agere Systems Inc. | Lithium niobate grating structure with high refractive index overlay |
| CN104914502A (en) * | 2015-06-04 | 2015-09-16 | 天津理工大学 | Method for preparing waveguide and grating on lithium niobate crystal simultaneously |
| CN107843957A (en) * | 2017-11-13 | 2018-03-27 | 上海理工大学 | The heterogeneous integrated waveguide device architecture of silicon nitride lithium niobate and preparation method |
| CN108732795A (en) * | 2017-04-14 | 2018-11-02 | 天津领芯科技发展有限公司 | A kind of silicon substrate lithium niobate high-speed optical modulator and preparation method thereof |
| CN111061072A (en) * | 2020-03-16 | 2020-04-24 | 南京南智先进光电集成技术研究院有限公司 | Photoelectric device based on lithium niobate thin film and preparation method thereof |
| CN116454170A (en) * | 2023-05-18 | 2023-07-18 | 平湖科谱激光科技有限公司 | Photoelectric device and preparation process thereof |
| CN117192686A (en) * | 2023-10-11 | 2023-12-08 | 中国科学院半导体研究所 | High-efficiency thin-film lithium niobate conical sub-wavelength grating end surface coupler and preparation method thereof |
Patent Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001116943A (en) * | 1999-10-20 | 2001-04-27 | Fuji Xerox Co Ltd | Method for producing thin metal oxide film element |
| WO2004034108A1 (en) * | 2002-10-09 | 2004-04-22 | Agere Systems Inc. | Lithium niobate grating structure with high refractive index overlay |
| CN104914502A (en) * | 2015-06-04 | 2015-09-16 | 天津理工大学 | Method for preparing waveguide and grating on lithium niobate crystal simultaneously |
| CN108732795A (en) * | 2017-04-14 | 2018-11-02 | 天津领芯科技发展有限公司 | A kind of silicon substrate lithium niobate high-speed optical modulator and preparation method thereof |
| CN107843957A (en) * | 2017-11-13 | 2018-03-27 | 上海理工大学 | The heterogeneous integrated waveguide device architecture of silicon nitride lithium niobate and preparation method |
| CN111061072A (en) * | 2020-03-16 | 2020-04-24 | 南京南智先进光电集成技术研究院有限公司 | Photoelectric device based on lithium niobate thin film and preparation method thereof |
| CN116454170A (en) * | 2023-05-18 | 2023-07-18 | 平湖科谱激光科技有限公司 | Photoelectric device and preparation process thereof |
| CN117192686A (en) * | 2023-10-11 | 2023-12-08 | 中国科学院半导体研究所 | High-efficiency thin-film lithium niobate conical sub-wavelength grating end surface coupler and preparation method thereof |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US5408566A (en) | Optical guided-wave device and manufacturing method | |
| CN111965856B (en) | Electro-optic crystal film, preparation method thereof and electro-optic modulator | |
| CN111965854B (en) | Electro-optic crystal film, preparation method thereof and electro-optic modulator | |
| JPH04213406A (en) | Lightguide tube and manufacture thereof | |
| WO2024007586A1 (en) | Method for preparing wafer having three-layer stacked structure, and application thereof | |
| CN211786214U (en) | Lithium niobate thin film optical waveguide structure and chip | |
| US11675126B1 (en) | Heterogeneous integration of an electro-optical platform | |
| CN117991448B (en) | Method for integrating grating and lithium niobate thin film waveguide | |
| CN117991448A (en) | Method for integrating grating and lithium niobate thin film waveguide | |
| JP2574606B2 (en) | Dielectric optical waveguide device and method of manufacturing the same | |
| US6856746B2 (en) | Titanium-indiffusion waveguides and methods of fabrication | |
| JP4653391B2 (en) | Manufacturing method of light control element | |
| CN111965858B (en) | Electro-optic crystal film, preparation method thereof and electro-optic modulator | |
| JPH06289347A (en) | Optical waveguide element and its manufacture | |
| CN114114538A (en) | Optical coupling structure, preparation method thereof and silicon-based chip comprising optical coupling structure | |
| CN109683354B (en) | Mid-infrared band modulator and preparation method thereof | |
| JP2581486B2 (en) | Optical waveguide device and method of manufacturing the same | |
| CN113224187A (en) | Composite film and method for producing same | |
| CN111487791B (en) | Integrated optical composite substrate | |
| WO2023238184A1 (en) | Optical modulator | |
| WO2023174190A1 (en) | Optical chip and preparation method therefor | |
| US20230059629A1 (en) | Composite Film and Fabrication Method Therefor | |
| JP2574602B2 (en) | Optical waveguide device | |
| Duan et al. | III–V on silicon transmitters | |
| CN114512893A (en) | Heterogeneous single-chip unidirectional injection locking semiconductor laser and preparation method thereof |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant |