CN111864535A

CN111864535A - Optical frequency comb device and manufacturing method thereof

Info

Publication number: CN111864535A
Application number: CN202010575729.7A
Authority: CN
Inventors: 孙朝阳; 朱振东; 王雪深; 刘唱; 白本锋; 屈继峰
Original assignee: National Institute of Metrology
Current assignee: National Institute of Metrology
Priority date: 2020-06-22
Filing date: 2020-06-22
Publication date: 2020-10-30
Anticipated expiration: 2040-06-22
Also published as: CN111864535B

Abstract

The invention relates to an optical frequency comb device and a manufacturing method thereof. The optical frequency comb layer is arranged on the surface, far away from the substrate, of the dielectric layer. And a stress release unit is arranged on the surface of the dielectric layer, which is in contact with the optical frequency comb layer. The stress relief unit includes a V-shaped structure. The V-shaped structure blocks the direction and the path of stress generation to a greater extent, and the stress transmitted from the silicon nitride film to the surface of the dielectric layer can be blocked by the V-shaped structure, so that the dielectric layer and the silicon nitride film can be prevented from cracking, and the product yield can be improved.

Description

Optical frequency comb device and manufacturing method thereof

Technical Field

The invention relates to the technical field of chips, in particular to an optical frequency comb device and a manufacturing method of the optical frequency comb device.

Background

Optoelectronic chips are the national core competitiveness and backbone industry. The capacity of the photonic integrated manufacturing industry in China is insufficient, and the photonic integrated manufacturing industry is not only backward of high-end manufacturing equipment of large-scale integrated circuits, but also has the difference of advanced integration processes, growth of key thin film materials and microlithography. These technical barriers make the overall performance of optoelectronic chips in our country restricted by developed countries.

An on-chip Kerr optical frequency comb, named Kerr optical comb for short, is a wideband optical frequency comb which converts pump light with a certain single frequency into a pulse sequence containing a large number of equally spaced frequencies and outputting an ultrashort soliton pulse sequence in a time domain by utilizing the nonlinear optical Kerr effect in a novel optical micro-ring resonant cavity. Technically, the on-chip optical frequency comb is based on an advanced optical thin film which is grown, and an advanced semiconductor process is adopted. Therefore, the Kerr optical comb can realize the outstanding advantages of on-chip integration, high pulse repetition frequency, good coherence, high single comb tooth power and the like, and is a subversive technology. The on-chip optical frequency comb has extremely high time frequency precision, can redefine a basic physical constant 'second', can construct monochromatic laser, can construct a clock and frequency chain with the highest precision, can improve a global positioning system and the like. By utilizing the on-chip optical frequency comb chip, people are expected to know the substance world and the ultrahigh sensitive chemical detection at the single molecule and single atom level, and can be widely applied to public safety, biomedical detection and identification of bacteria and viruses and the like. By using the on-chip optical frequency comb chip, people can synthesize a super laser, which is expected to realize coherent control and laser with specific waveform on the electromagnetic spectrum from radio waves to X rays, and improve the sensitivity and detection range of the radar by several orders of magnitude. The method has great strategic significance in the fields of basic science of forewords, national defense safety and the like. The NASA, DARPA, NIST, Germany, Sweden and the like in the United states invest billions of dollars to develop on-chip optical frequency combs from the beginning of the 21 st century by virtue of the technical advantages of semiconductor processes, and form better technical accumulation. The research on the on-chip optical frequency comb in China starts late, the process technology is backward, and large equipment is short, so that the research on the on-chip optical frequency comb integration is urgent.

However, stress is easily generated in the manufacturing process of the conventional on-chip optical frequency comb device, so that the stability of the on-chip optical frequency comb device is affected.

Disclosure of Invention

In view of the above, it is necessary to provide an optical frequency comb device and a method for manufacturing the optical frequency comb device.

An optical-frequency comb device, comprising:

a substrate;

the dielectric layer is arranged on the surface of the substrate layer;

the optical frequency comb layer is arranged on the surface, far away from the substrate, of the dielectric layer, a stress release unit is arranged on the surface, in contact with the optical frequency comb layer, of the dielectric layer, and the stress release unit comprises a V-shaped structure.

In one embodiment, the V-shaped structure includes two first linear regions with coincident vertexes, and a set angle is formed between the two first linear regions, and the stress release unit further includes a first cross-shaped structure disposed between the two first linear regions.

In one embodiment, the stress relief unit further comprises a second linear area located between the two first linear areas, and the two first cross structures are respectively located on two sides of the second linear area and located between the two first linear areas.

In one embodiment, the elongation direction of the second rectilinear area coincides with the vertex.

In one embodiment, the first and second linear regions have the same width, and the length of the second linear region is 1.2 to 1.5 times the length of the first linear region.

In one embodiment, the surface of the dielectric layer, which is in contact with the optical frequency comb layer, is provided with a stress relief region, and the stress relief region is provided with a plurality of stress release units.

In one embodiment, a mark region is arranged between the stress release units on the surface of the medium layer, which is in contact with the optical frequency comb layer.

In one embodiment, the marker region is provided with a second cross-structure.

In one embodiment, the marking area further comprises a third cross structure, the third cross structure dividing the marking area into four quadrants, the third cross structure being located in one of the quadrants.

In one embodiment, the stress relieving device further comprises a plurality of sparse regions, and the sparse regions are arranged among the stress relieving regions.

In one embodiment, the stress relief region comprises:

The first stress eliminating areas are arranged at intervals to form a plurality of first stress eliminating area rows, and a waveguide area is formed between every two adjacent first stress eliminating area rows;

a plurality of second stress relief regions, one of the second stress relief regions being disposed between two adjacent first stress relief regions in the row of first stress relief regions; the frequency sparse region is formed among the second stress relieving region, the two adjacent first stress relieving regions and the waveguide region.

A method for manufacturing an optical frequency comb device comprises the following steps:

providing a substrate;

forming a dielectric layer on the surface of the substrate, wherein a stress release unit is arranged on the surface of the dielectric layer, which is far away from the substrate, and the stress release unit comprises a V-shaped structure;

and forming an optical frequency comb layer on the surface of the dielectric layer far away from the substrate.

According to the optical frequency comb device and the manufacturing method of the optical frequency comb device, the dielectric layer is arranged on the surface of the substrate layer. The optical frequency comb layer is arranged on the surface, far away from the substrate, of the dielectric layer. And a stress release unit is arranged on the surface of the dielectric layer, which is in contact with the optical frequency comb layer. The stress relief unit includes a V-shaped structure. The V-shaped structure blocks the direction and the path of stress generation to a greater extent, and the stress transmitted from the silicon nitride film to the surface of the dielectric layer can be blocked by the V-shaped structure, so that the dielectric layer and the silicon nitride film can be prevented from cracking, and the product yield can be improved.

Drawings

In order to more clearly illustrate the embodiments of the present application 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 application, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

Fig. 1 is a schematic cross-sectional view of an optical frequency comb device provided in an embodiment of the present application;

FIG. 2 is a schematic diagram of a surface pattern of a dielectric layer according to an embodiment of the present disclosure;

fig. 3 is a mirror image of an optical frequency comb disposed in a waveguide region on a surface of a dielectric layer according to an embodiment of the present disclosure;

FIG. 4 is a schematic view of a V-shaped structure provided in an embodiment of the present application;

FIG. 5 is a schematic cross-sectional view of an optical-frequency comb device according to another embodiment of the present application

FIG. 6 is a schematic view of a stress relief unit according to an embodiment of the present disclosure;

FIG. 7 is a crack mirror image of an optical frequency comb device according to an embodiment of the present disclosure;

FIG. 8 is a schematic diagram of a marking area provided in an embodiment of the present application;

fig. 9 is a flow chart of a manufacturing process of an optical frequency comb device according to an embodiment of the present application.

Description of reference numerals:

Optical frequency comb device 10

Substrate 110

Dielectric layer 120

Groove 122

Optical frequency comb layer 130

Optical frequency comb 132

Stress relief region 200

First stress relief zone line 210

First stress relief region 212

Waveguide region 220

Second stress relief region 214

Stress relief unit 230

V-shaped structure 232

First linear region 234

Vertex 236

First cross structure 238

Second straight section 240

Marking area 250

A second cross-shaped structure 252

Thirty-first structure 254

Frequency sparse region 260

Ultraviolet glue layer 300

Aluminum oxide layer 310

Electron beam glue 320

Detailed Description

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

In the description of the present invention, it is to be understood that the terms "central," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," and the like are used in the orientations and positional relationships indicated in the drawings for convenience in describing the invention and to simplify the description, and are not intended to indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and are not to be considered limiting of the invention.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.

In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; they may be directly connected or indirectly connected through intervening media, or they may be connected internally or in any other suitable relationship, unless expressly stated otherwise. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

In the present invention, unless otherwise expressly stated or limited, the first feature "on" or "under" the second feature may be directly contacting the first and second features or indirectly contacting the first and second features through an intermediate. Also, a first feature "on," "over," and "above" a second feature may be directly or diagonally above the second feature, or may simply indicate that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature may be directly under or obliquely under the first feature, or may simply mean that the first feature is at a lesser elevation than the second feature.

It will be understood that when an element is referred to as being "secured to" or "disposed on" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and the like as used herein are for illustrative purposes only and do not denote a unique embodiment.

Referring to fig. 1-4, embodiments of the present application provide an optical frequency comb device 10. The optical-frequency comb device 10 includes a substrate 110, a dielectric layer 120, and an optical-frequency comb layer 130. The dielectric layer 120 is disposed on the surface of the substrate 110. The optical frequency comb layer 130 is disposed on the surface of the dielectric layer 120 away from the substrate 110. The surface of the dielectric layer 120 contacting the optical frequency comb layer 130 is provided with a stress relief unit 230. The stress relief unit 230 includes a V-shaped structure 232.

The substrate 110 may be made of silicon, single crystal silicon, polycrystalline silicon, silicon carbide, sapphire, fused silica, magnesium fluoride, or the like.

The optical comb layer 130 may be PECVD silicon dioxide, thermal oxidation silicon dioxide (TEOS), CaF2, MgF2, silicon oxynitride, titanium dioxide, CuO, ZnO, or the like.

In one embodiment, the optical frequency comb layer 130 may be a silicon nitride film. The silicon nitride film has excellent photoelectric properties, passivation properties and mechanical properties such as wide optical window, extremely low optical loss and the like. The optical frequency comb device 10 requires that the stoichiometric ratio of the silicon nitride film is 3: 4, i.e. Si₃N₄The component ratio of (A) is 3: 4. due to the requirement of low loss required stoichiometric ratio, the two-photon absorption of H and Si by plasma enhanced chemical vapor deposition in CMOS process can hardly meet the requirement, so the low pressure chemical vapor deposition process technology under high temperature condition needs to be adopted. In one embodiment, the silicon nitride film may have a thickness of 700 to 1000 nanometers. Anomalous dispersion requires a thickness greater than 800nm, and thus the silicon nitride thin film can have a thickness of 800 nm.

The dielectric layer 120 may be made of silicon nitride, aluminum nitride, titanium nitride, gallium arsenide, gallium oxide, indium phosphide, CIGS, IGZO, silicon oxynitride, metal Ge film, metal Ni film, or other III-V semiconductor thin film materials. The dielectric layer 120 may have a thickness of 400nm to 1500 nm.

In one embodiment, the dielectric layer 120 may be a low refractive index oxide dielectric layer 120 such as fused silica, silicon dioxide, sapphire, etc. The dielectric layer 120 may be a wet oxidized silicon dioxide. Based on the requirement of low refractive index required by silicon optical integration, the thickness of the silicon oxide is not less than 2 microns, so that the requirement of low refractive index of silicon optical integration can be met. In one embodiment, the dielectric layer 120 may be a 3 micron thick silicon dioxide material.

Since the closer the stoichiometric ratio of the silicon nitride film is to 3: 4, the greater the stress. The greater the thickness of the thin silicon nitride film, the greater the stress. And the thicker the dielectric layer 120, the more unfavorable the stress relief. And the silicon nitride film is easy to crack spontaneously during processing due to large stress, so that the device fails, namely, optoelectronic devices such as an optical frequency comb and the like cannot be generated.

The stress relief unit 230 may function to relieve stress. The stress relief unit 230 may be a pattern formed by protrusions or depressions formed on the surface of the dielectric layer 120. The stress relief unit 230 may include the V-shaped structure 232. The plane in which V-shaped structures 232 lie may be parallel to the surface of dielectric layer 120. The V-shaped structure 232 includes two first linear regions 234 that intersect at an angle. Therefore, since the direction of the stress transmitted from the silicon nitride film to the surface of the dielectric layer 120 is not easy to judge, and the two first linear regions 234 of the V-shaped structure 232 intersecting at a certain angle largely block the direction and path of the stress, the stress transmitted from the silicon nitride film to the surface of the dielectric layer 120 is blocked by the first linear regions 234, thereby preventing the dielectric layer 120 from cracking, and further preventing the silicon nitride film from cracking. Thereby improving the yield of the product.

The optical frequency comb device 10 provided by the embodiment of the application. The dielectric layer 120 is disposed on the surface of the substrate 110. The optical frequency comb layer 130 is disposed on the surface of the dielectric layer 120 away from the substrate 110. The surface of the dielectric layer 120 contacting the optical frequency comb layer 130 is provided with a stress relief unit 230. The stress relief unit 230 includes a V-shaped structure 232. The V-shaped structure 232 largely blocks the direction and path of stress generation, and the stress transmitted from the silicon nitride film to the surface of the dielectric layer 120 is blocked by the V-shaped structure 232, so that the dielectric layer 120 and the silicon nitride film can be prevented from cracking, and the product yield can be improved.

Referring to fig. 5, in one embodiment, the dielectric layer 120 is etched to form grooves 122, and the optical-frequency comb layer 130 can fill the groove pattern to form optical-frequency combs 132. In one embodiment, the dielectric layer 120 is etched to a depth of 1.5 microns or more. At this depth, the stress during the production of the optical frequency comb layer 130 can be transferred into the grooves of the dielectric layer 120, thereby reducing the overall stress of the optical frequency comb layer 130. The stability and lifetime of the optical frequency comb device 10 are improved. Referring to fig. 6, in one embodiment, the V-shaped structure 232 includes a first linear region 234 with two apexes 236 coincident. The two first linear regions 234 are at a set angle. The stress relief unit 230 further comprises a first cross-shaped structure 238. The first cross-shaped structure 238 is disposed between the two first linear regions 234.

The end where the two first linear regions 234 intersect may be the vertex 236. The set angle can be set as required. In one embodiment, the set angle may be 30 ° to 180 °. In one embodiment, the set angle may be 60 ° to 145 °. In one embodiment, the set angle may be 70 ° to 120 °. In one embodiment, the set angle may be 80 ° to 110 °. Further, the set angle may be 90 °. It will be appreciated that when the set angle is 90, the apex 236 will form a rounded chamfer during the photolithography process, thereby making it easier to relieve stress.

The set angle determines the extending direction of the first linear region 234, and thus the direction in which the first linear region 234 blocks stress conduction can be determined. The plane of the first cross-shaped structure 238 may be parallel to the plane of the V-shaped structure 232. The first cross-shaped structure 238 is disposed in the area formed by the two first straight regions 234, so that the first cross-shaped structure 238 can block the stress transmitted from the opening of the V-shaped structure 232, and further release the stress transmitted from different directions. It is understood that the first cross-shaped structure 238 may also block stress conduction in the area formed by the half-surrounded first linear region 234, further blocking the path of stress conduction.

In one embodiment, the optical-frequency comb device 10 further includes two of the first cross structures 238. The stress relief unit 230 further comprises a second linear region 240. The second linear region 240 is located between the two first linear regions 234. The two first cross structures 238 are respectively located on both sides of the second linear region 240 and between the two first linear regions 234.

Referring to fig. 7, when the optical frequency comb device 10 cracks due to stress, the first cross structure 238 and the second straight line region 240 may function to guide stress dissipation. The two first linear regions 234 may form a triangular structure, and the two first linear regions 234 and the second linear region 240 may form a triangular structure respectively. The triangular structure has a stable characteristic, and thus the stability of the structure of the optical frequency comb device 10 can be increased.

The second linear region 240 divides the area enclosed by the V-shaped structure 232 into two parts. Wherein one of the first linear regions 234 and the second linear region 240 are half-enclosed to form one portion. Another of the first and second

linear regions

234 and 240 is half-enclosed to form another portion. The two first cross-shaped structures 238 and the second straight-line region 240 further subdivide the area within the V-shaped structure 232 into different small areas, further cutting off the path of stress conduction generated at different locations. The reliability of the optical frequency comb device 10 is further improved.

In one embodiment, the elongation direction of the second linear region 240 coincides with the vertex 236. I.e. the second rectilinear area 240 may be located on the bisector of the angle of the V-shaped structure 232. The uniformity of the distribution of the small areas within the area enclosed by the V-shaped structure 232 can be improved.

In one embodiment, the first linear region 234 and the second linear region 240 have the same width. The length of the second linear region 240 is 1.2 to 1.5 times the length of the first linear region 234. Thus, the second linear region 240 is longer than the first linear region 234, i.e., the second linear region 240 may protrude a certain distance from the opening of the V-shaped structure 232, such that a path blocking stress conduction may be increased. In one embodiment, the length of the second linear region 240 is 1.4 times the length of the first linear region 234.

In one embodiment, the centerline of the second linear region 240 is 10 microns from the center of the first cross-shaped structure 238. In one embodiment, the first cross-shaped structure 238 is formed of two rectangles of the same shape. The length and width of the rectangle may be 20 microns and 5 microns respectively.

In one embodiment, the surface of the dielectric layer 120 in contact with the optical-frequency comb layer 130 is provided with a stress relief region 200. The stress relief region 200 is provided with a plurality of the stress relief units 230. The stress relief units 230 may be spaced apart from each other in the stress relief region 200. The stress releasing units 230 may have a regular arrangement or an irregular arrangement.

In one embodiment, a mark region 250 is disposed between a plurality of the stress relief units 230 on a surface of the dielectric layer 120 contacting the optical-frequency comb layer 130. The marker region 250 may be used to find the keep-alive region 260 and the waveguide region 220 in an electron beam exposure. It is understood that the mark region 250 may be a raised structure or a recessed structure formed on the surface of the dielectric layer 120.

Referring to fig. 8, in one embodiment, the mark area 250 is provided with a second cross structure 252. The second cross-shaped structure 252 may be formed by two rectangles with the same size and shape that intersect perpendicularly. In one embodiment, the rectangles comprising the second cross-shaped structures 252 have a length and width of 40 to 60 microns and 10 to 15 microns, respectively. In one embodiment, the rectangles comprising the second cross-shaped structures 252 have a length and width of 50 microns and 10 microns, respectively.

In one embodiment, the marker region 250 further includes a thirty-first structure 254. The second cross-shaped structure 252 divides the marking region 250 into four quadrants. The thirty-first structure 254 is located in one of the quadrants. The size of the third cross-structure 254 may be smaller than the second cross-structure 252. Further, the size of the third cross structure 254 may be 1/5 through 1/3 of the size of the second cross structure 252. In one embodiment, the thirty-first structure 254 may be located in a first quadrant. Further, the thirty-first structure 254 may be located in the center of the first quadrant.

In one embodiment, the optical-frequency comb device 10 further includes a frequency-sparse region 260. The stress relief region 200 is plural. The frequency-sparse region 260 is disposed between a plurality of the stress relief regions 200. The keep-alive region 260 can correspond to the microcavity optical-frequency comb 132 formed in the silicon nitride layer by exposure etching. The frequency thinning region 260 is disposed between the stress relief regions 200, and stress conduction can be cut off at the periphery of the frequency thinning region 260, so that the frequency thinning region 260 can be prevented from being damaged by stress.

In one embodiment, the stress relief region 200 includes a plurality of spaced apart first stress relief regions 212 and a plurality of second stress relief regions 214. The plurality of spaced apart first stress relief areas 212 form a plurality of first stress relief area rows 210. A plurality of the first stress relief area rows 210 may form a first stress relief area 212 matrix. A waveguide region 220 is formed between two adjacent rows 210 of the first stress relief regions. One of the second stress relief regions 214 is disposed between two adjacent first stress relief regions 212 in the first stress relief region row 210. The second stress relief region 214 is spaced apart from two adjacent first stress relief regions 212. The second stress relief region 214, the two adjacent first stress relief regions 212, and the waveguide region 220 form the frequency sparse region 260 therebetween.

The second stress relief region 214 may have a width less than the width of two adjacent first stress relief regions 212. One long side of the second stress relief region 214 may be flush with one long side of the first stress relief region 212. The other long side of the second stress relief region 214 is therefore set back from the other long side of the first stress relief region 212, leaving an area. This region is also surrounded by the waveguide region 220. The keep-alive region 260 is thus formed between the second stress relief region 214, the two adjacent first stress relief regions 212, and the waveguide region 220.

In one embodiment, the stress relieving element 230 may be periodically repeated in an X-Y two-dimensional coordinate system. The number of repetitions of the stress releasing unit 230 in the X direction is 200-1000, respectively. The number of X-direction repeating units is determined by the length of the waveguide region 220. In one embodiment, the number of X-direction repeating units may be 200. In one embodiment, the number of repetitions of the stress relief unit 230 in the Y direction is 5 to 100, respectively. In one embodiment, the number of repetitions of the stress relieving unit 230 in the Y direction is 8.

In one embodiment, the second stress relief regions 214 are arranged in 7 columns of the stress relief units 230 at intervals in the X direction, and are arranged in 3 rows of the stress relief units 230 at intervals in the Y direction.

The first stress relief region 212 includes 14 columns of stress relief units 230 arranged at intervals in the X direction, and 8 rows of stress relief units 230 arranged at intervals in the Y direction. The horizontal line of the stress relieving cells 230 in the row at the center of the second stress relieving region 214 is located between the sixth and seventh rows of stress relieving cells 230 in the first stress relieving region 212. Therefore, the rows of stress relief cells 230 in the first stress relief regions 212 and the rows of stress relief regions 214 are offset in the Y direction. Since the second stress relief region 214 is located close to the optical frequency comb 132, any stress relief element 230 in the second stress relief region 214 can be marked once a crack has occurred.

In one embodiment, one of the first stress relief regions 212, one of the second stress relief regions 214, one of the keep-alive regions 260, and one of the waveguide regions 220 may constitute a repeating unit. The repeating units may be repeatedly arranged on the surface of the dielectric layer 120.

In one embodiment, the marker region 250 may be located in the first stress relief region 212. The marker region 250 may also be located in the second stress relief region 214.

The embodiment of the application also provides a manufacturing method of the optical frequency comb device 10. The method comprises the following steps:

s10, providing a substrate 110;

s20, forming a dielectric layer 120 on the surface of the substrate 110, where a stress relief unit 230 is disposed on the surface of the dielectric layer 120 away from the surface of the substrate 110, and the stress relief unit 230 includes a V-shaped structure 232;

and S30, forming an optical frequency comb layer 130 on the surface of the dielectric layer 120 far away from the substrate 110.

In S20, the dielectric layer 120 may be cleaned to remove contaminants such as organic substances, metal deposits, and inorganic particles on the surface of the dielectric layer 120. In one embodiment, the cleaning may be performed in accordance with CMOS standard processes.

In one embodiment, a photolithography plate is used to perform the uv lithography exposure, development, and fixing processes. It is understood that the shape and pattern structure of the reticle correspond to the structure for releasing stress formed on the surface of the dielectric layer 120 contacting the optical-frequency comb layer 130 provided in the above embodiments.

And after exposure and development are carried out through the photoetching plate, the dielectric layer 120 is etched. Etching may be reactive plasma etching RIE using fluorine-based gas, or inductively coupled plasma etching ICP etching. The etching process can be a CMOS standard process parameter, and in one embodiment, the etching depth can be 100nm to 3000 nm. In one embodiment, the etch depth is required to be greater than 2 microns deep, or even deeper. In one embodiment, the dielectric layer 120 may be etched through with an etch depth of 3 microns.

After the dielectric layer 120 is etched, a photoresist removing step may be performed. Acetone may be used to remove the residual photoresist. Or the photoresist is removed by an O2 plasma photoresist remover. And then performing CMOS standard cleaning on the surface of the dielectric layer 120 to remove pollutants introduced in the processes of exposure, etching and the like.

And then, growing a silicon nitride film on the surface of the dielectric layer 120. In one embodiment, an LPCVD process may be employed. And then exposing by electron beams, etching, removing photoresist and coating film afterwards. And finally, cutting to obtain the optical frequency comb device 10.

After the optical frequency comb device 10 is manufactured, laser alignment measurement can be performed to verify the stress and the working stability of the optical frequency comb device 10.

Referring to fig. 9, in an embodiment, the method for manufacturing the optical frequency comb device 10 further includes the following steps:

a, forming a dielectric layer 120 on a substrate through wet oxidation and atomic deposition, and forming an aluminum oxide layer 310 on the surface of the dielectric layer 120; b, spin-coating an ultraviolet adhesive layer 300 on the surface of the dielectric layer 120; c, carrying out ultraviolet photoetching; d, developing and fixing; e etching the aluminum oxide layer 310 by chlorine gas; f, etching the dielectric layer 120, wherein the etching depth of the dielectric layer 120 is more than 1.5 microns; g, spin coating electron beam glue 320; h-i, electron beam exposure overlay, j, developing and etching the aluminum oxide layer 310; k, degelatinizing and the aluminum oxide layer 310; l, LPCVD stoichiometric silicon nitride; m, annealing at 1200 ℃; and n, growing the dielectric layer 120 by PECVD.

The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims

1. An optical-frequency comb device, comprising:

a substrate (110);

a dielectric layer (120) disposed on a surface of the substrate (110) layer;

the optical frequency comb layer (130) is arranged on the surface, far away from the substrate (110), of the dielectric layer (120), a stress release unit (230) is arranged on the surface, in contact with the optical frequency comb layer (130), of the dielectric layer (120), and the stress release unit (230) comprises a V-shaped structure (232).

2. The optical-frequency comb device according to claim 1, wherein the V-shaped structure (232) comprises two first linear regions (234) having coincident vertices (236), the two first linear regions (234) forming a set angle therebetween, and the stress relief unit (230) further comprises a first cross-shaped structure (238), the first cross-shaped structure (238) being disposed between the two first linear regions (234).

3. The optical-frequency comb device according to claim 2, comprising two first cross structures (238), wherein the stress relief unit (230) further comprises a second linear region (240), wherein the second linear region (240) is located between the two first linear regions (234), and wherein the two first cross structures (238) are respectively located on both sides of the second linear region (240) and between the two first linear regions (234).

4. The optical frequency comb device according to claim 3, wherein an extension direction of the second straight line region (240) coincides with the apex (236).

5. The optical-frequency comb device according to claim 3, wherein the first linear region (234) and the second linear region (240) have the same width, and the length of the second linear region (240) is 1.2 times to 1.5 times the length of the first linear region (234).

6. The optical-frequency comb device according to any one of claims 1 to 5, wherein a surface of the dielectric layer (120) in contact with the optical-frequency comb layer (130) is provided with a stress relief region (200), and the stress relief region (200) is provided with a plurality of the stress relief units (230).

7. The optical-frequency comb device according to claim 6, wherein a mark region (250) is provided between the plurality of stress relief units (230) at a surface of the dielectric layer (120) in contact with the optical-frequency comb layer (130).

8. The optical-frequency comb device according to claim 7, wherein the mark region (250) is provided with a second cross structure (252).

9. The optical-frequency comb device of claim 8, wherein the labeling area (250) further comprises a third cross-structure (254), the second cross-structure (252) dividing the labeling area (250) into four quadrants, the third cross-structure (254) being located in one of the quadrants.

10. The optical-frequency comb device according to claim 6, further comprising a plurality of frequency-sparse regions (260), wherein the stress relief regions (200) are disposed in plurality, and wherein the frequency-sparse regions (260) are disposed between the plurality of stress relief regions (200).

11. The optical-frequency comb device according to claim 10, wherein the stress relief region (200) comprises:

a plurality of first stress relief regions (212) spaced apart to form a plurality of first stress relief region rows (210), a waveguide region (220) being formed between two adjacent first stress relief region rows (210);

a plurality of second stress relief regions (214), one second stress relief region (214) disposed between two adjacent first stress relief regions (212) in the first stress relief region row (210); the second stress relief region (214), the two adjacent first stress relief regions (212) and the waveguide region (220) form the frequency sparse region (260).

12. A method for manufacturing an optical frequency comb device is characterized by comprising the following steps:

providing a substrate (110);

forming a dielectric layer (120) on the surface of the substrate (110), wherein a stress release unit (230) is arranged on the surface of the dielectric layer (120) far away from the surface of the substrate (110), and the stress release unit (230) comprises a V-shaped structure (232);

An optical frequency comb layer (130) is formed on a surface of the dielectric layer (120) remote from the substrate (110).