Preparation method of electro-optical modulator

Abstract

The invention relates to a preparation method of an electro-optical modulator. The preparation method of the electro-optical modulation device comprises the following steps: forming a graphical barrier layer on one side of an electro-optical material film of an electro-optical material film wafer, grinding multiple columns of electro-optical material films exposed by the graphical barrier layer along an opening area by using a grinding wheel until a buried layer is exposed, and forming a strip-shaped groove with slope structures on two sides; cutting a plurality of electro-optical material film units from the structure from which the graphical barrier layer is removed; the electro-optical material film unit comprises a part, limited by two adjacent strip-shaped grooves, of the electro-optical material film; the electro-optical material film unit is bonded to the surface of the side, back on to the waveguide core, of the bonding dielectric layer; wherein the electro-optical material film unit corresponds to the waveguide core; the slope structures are located on the two sides of the waveguide core in the length direction. According to the preparation method of the electro-optical modulator, the technological process can be simplified, the technological difficulty is reduced, the technological efficiency is improved, and the light field transition loss of the electro-optical modulator is effectively reduced.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a method for preparing an electro-optical modulation device. Background Art

[0002] Stoichiometric silicon nitride (SiN) prepared by low pressure chemical vapor deposition (LPCVD) 3 N 4 ) film / waveguide core has a wide wavelength range (400nm ~ 2350nm) transparency, high optical power and low optical propagation loss, using wafer-level manufacturing process, silicon nitride waveguide core and silicon (Si) substrate, silicon dioxide (SiO 2 ) cladding has realized a wide range of planar integrated devices and chip-level solutions. Phase modulator is one of the core devices of photonic integrated circuits. Photonic platforms based on silicon nitride can usually use thermo-optical effect, stress-optical effect, etc. to achieve optical phase modulation. However, due to the limitations of material properties such as heat conduction speed, charging and discharging time, and device structure, these modulators are still insufficient in speed, power, and efficiency. A popular alternative is electro-optic modulation, but the electro-optic effect of silicon nitride is very weak, and it must be combined with materials with significant electro-optical effect to achieve efficient electro-optic phase modulation. Among them, single crystal lithium niobate (LiNbO 3 ) has a strong electro-optical effect (1550nm: r 33 =30.8pm / V), larger refractive index (1550nm: n o =2.21,n e =2.14), a wide light transmission window (400nm~5μm) and stable physical and chemical properties, making it the most competitive electro-optical modulation material.

[0003] One of the challenges facing heterogeneous integration of lithium niobate and silicon nitride waveguide platforms is the low-loss transition of the optical field between silicon nitride waveguide and silicon nitride-lithium niobate composite waveguide. The existing technical solutions for realizing the light field transition between lithium niobate and silicon nitride waveguide all have certain defects: Solution 1: Integrate lithium niobate with a two-dimensional conical structure into a silicon nitride platform through a micro-transfer process to realize the light field transition, but this solution requires that the two-dimensional conical structure and the silicon nitride optical waveguide core have a high alignment accuracy, which increases the process difficulty; Solution 2: Perform multiple dry etching on lithium niobate so that lithium niobate forms multiple steps along both sides of the silicon nitride waveguide core to realize the light field transition. Since dry etching of lithium niobate is relatively difficult, the process difficulty is high, and there is a potential contamination problem that will lead to incompatibility with CMOS process equipment; Solution 3: Use sputtering to form a mask with a gradient thickness on the surface of the film, and use chemical mechanical polishing (CMP) to make the lithium niobate film have a gradient thickness. However, this solution has the problems of low mask production efficiency, difficulty in forming multiple gradient thickness masks on the same substrate, or the mask size (resulting in the size of the gradient thickness film) cannot be accurately controlled.

[0004] Therefore, a method for preparing an electro-optical modulation device is needed, which uses a one-step or lithium niobate-free etching process to achieve a low-loss transition between a silicon nitride waveguide and a silicon nitride-lithium niobate composite waveguide, thereby reducing the transition loss of a heterogeneous integrated electro-optic phase modulation device. Summary of the invention

[0005] Therefore, the present invention provides a method for preparing an electro-optical modulation device to solve the problems in the existing method for preparing an electro-optical modulation device, such as high difficulty in micro-transfer of two-dimensional conical lithium niobate, high difficulty in dry etching of lithium niobate, and difficulty in accurately controlling the thickness of the mask, which leads to high light field transition loss between the silicon nitride waveguide and the silicon nitride-lithium niobate composite waveguide.

[0006] The present invention provides a method for preparing an electro-optical modulation device, comprising:

[0007] Providing an electro-optical material thin film wafer, the electro-optical material thin film wafer sequentially comprising a stacked first substrate, a buried layer and an electro-optical material thin film;

[0008] forming a blocking layer on the side of the electro-optic material film facing away from the buried layer, etching the blocking layer to form a patterned blocking layer, wherein the opening area of ​​the patterned blocking layer exposes a plurality of columns of the electro-optic material film;

[0009] Using a grinding wheel to grind the exposed multiple rows of electro-optical material films along the opening area until the buried layer is exposed, forming a strip groove with a slope structure on both sides; the strip groove penetrates the electro-optical material film in the depth direction and penetrates into the buried layer;

[0010] removing the patterned barrier layer;

[0011] Cutting a plurality of electro-optical material thin film units from the structure after removing the patterned blocking layer; the electro-optical material thin film unit includes a portion of the electro-optical material thin film defined by two adjacent strip-shaped grooves;

[0012] Providing a second substrate, and sequentially forming a lower cladding layer, a waveguide core, and a bonding dielectric layer on a surface of one side of the second substrate, wherein the bonding dielectric layer covers a surface of the waveguide core that is away from the second substrate and a side surface of the waveguide core;

[0013] Bonding the electro-optical material film unit to the surface of the bonding medium layer on one side facing away from the waveguide core; wherein the electro-optical material film unit corresponds to the waveguide core; and the slope structure is located on both sides of the length direction of the waveguide core;

[0014] Electrodes are formed on a surface of the electro-optical material film unit that is opposite to the bonding medium layer, and the electrodes are located at corresponding positions on both sides of the waveguide core.

[0015] Optionally, the method of sequentially forming a lower cladding layer, a waveguide core, and a bonding dielectric layer on a surface of one side of the second substrate includes:

[0016] forming a lower cladding layer on a surface of one side of the second substrate;

[0017] A waveguide core and a bonding dielectric layer are formed on a surface of the lower cladding layer facing away from the second substrate, and the bonding dielectric layer covers a surface of the waveguide core facing away from the second substrate and a side surface of the waveguide core.

[0018] Optionally, the width of the grinding wheel is greater than the width of the electro-optical material film exposed in the opening area;

[0019] The ratio of the projection length of the slope structure in the horizontal direction to the thickness of the electro-optical material film is 10:1 to 500:1.

[0020] Optionally, the cross section of the strip-shaped groove is V-shaped, and the slope structure is a plane slope structure;

[0021] The cross section at the lowest position where the grinding wheel contacts the electro-optical material film and the buried layer is an obtuse angle.

[0022] Optionally, the obtuse angle is 165° to 179.8°;

[0023] The width of the opening area is greater than or equal to 2×L×(H+h) / h, where L is the projection length of the slope structure on the horizontal plane, h is the thickness of the electro-optical material film, and H is the thickness of the blocking layer.

[0024] Optionally, the cross section of the strip-shaped groove is arc-shaped, and the slope structure is a curved slope structure;

[0025] The cross section of the lowest position where the grinding wheel contacts the electro-optical material film and the buried layer is an arc.

[0026] Optionally, the radius of curvature of the arc is 5 μm to 6.5 cm;

[0027] The width of the opening area is greater than or equal to Wherein, L is the projection length of the slope structure on the horizontal plane, h is the thickness of the electro-optical material film, and H is the thickness of the barrier layer.

[0028] Optionally, the electro-optical material film unit is a small electro-optical material film sheet having a slope structure;

[0029] The step of cutting a plurality of electro-optical material thin film units from the structure after removing the patterned blocking layer comprises:

[0030] The electro-optical material film remaining after grinding by the grinding wheel is patterned to form a plurality of electro-optical material film pieces, wherein the electro-optical material film pieces include a first electro-optical material film piece and a second electro-optical material film piece; wherein both sides of the non-slope surface of the first electro-optical material film piece are connected to two adjacent second electro-optical material film pieces through fine electro-optical material connection points;

[0031] Wet etching is used to remove the buried layer under the electro-optic material thin film piece; wherein the width of the first electro-optic material thin film piece is smaller than the width of the two second electro-optic material thin film pieces connected thereto, the first electro-optic material thin film piece is connected to the two adjacent second electro-optic material thin film pieces only through the electro-optic material connection point and is suspended in the air, while the two adjacent second electro-optic material thin film pieces are still connected to the first substrate through the buried layer;

[0032] The electro-optic material connection points between the electro-optic material film pieces are disconnected by using a micro-transfer printing device, so that the electro-optic material film pieces are separated from the first substrate.

[0033] Optionally, the step of bonding the electro-optical material thin film unit to a surface of the bonding dielectric layer on a side facing away from the waveguide core comprises:

[0034] A micro-transfer device is used to bond a small piece of electro-optical material film to a surface of a bonding medium layer facing away from the waveguide core; wherein the small piece of electro-optical material film corresponds to the waveguide core; and the slope surface of the small piece of electro-optical material film faces away from the waveguide core.

[0035] Optionally, the electro-optical material film unit includes a stacked portion of electro-optical material films having a slope structure and a corresponding buried layer and a first substrate in sequence;

[0036] The step of cutting a plurality of electro-optical material thin film units from the structure after removing the patterned blocking layer comprises:

[0037] The electro-optical material film wafer is cut along the strip grooves and in a direction perpendicular to the strip grooves to obtain a plurality of electro-optical material film units.

[0038] Optionally, the step of bonding the electro-optical material thin film unit to a surface of the bonding dielectric layer on a side facing away from the waveguide core includes:

[0039] Bonding the electro-optic material film unit to the surface of the bonding dielectric layer on the side facing away from the waveguide core; wherein the electro-optic material film contacts and bonds with the bonding dielectric layer; the electro-optic material film corresponds to the waveguide core; and the slope surface of the electro-optic material film faces the side of the waveguide core;

[0040] The first substrate is removed.

[0041] Optionally, the step of forming an electrode on a surface of the electro-optical material film unit that is opposite to the electro-optical material film includes:

[0042] An electrode is formed on the surface of the buried layer which faces away from the electro-optical material film.

[0043] The technical solution of the present invention has the following advantages:

[0044] (1) The preparation method of the electro-optical modulator provided by the present invention, on the one hand, accurately defines the size of the electro-optical material film unit and the position of the slope structure through the graphical (photolithography + etching process) barrier layer, and controls the grinding rate through (rigid) grinding wheel grinding and barrier layer, so that the efficiency of obtaining the slope structure on the electro-optical material film unit is higher and the slope consistency is better. At the same time, only one step or no etching of the optoelectronic material film is required in the preparation process, which simplifies the preparation process flow and reduces the process difficulty; on the other hand, the slope structure preparation method in this scheme has low requirements for alignment accuracy, the surface roughness of the formed slope structure is small and the slope is easy to control, and there is no absorption loss caused by additional materials, so that the electro-optical modulator has lower transition loss. Therefore, the preparation method of the electro-optical modulator provided by the present invention, through the method of grinding wheel grinding and the barrier layer controlling the grinding depth and uniformity, manufactures an electro-optical material film with a slope structure, and at the same time makes the slope structure of the electro-optical material film located on both sides of the length direction of the waveguide core, which can simplify the process flow, reduce the process difficulty, improve the process efficiency, and effectively reduce the light field transition loss of the electro-optical modulator.

[0045] (2) The preparation method of the electro-optic modulation device provided by the present invention heterogeneously integrates a small piece of electro-optic material with a slope structure into the corresponding position of the waveguide core through a micro-transfer process, so that the slope of the slope structure of the small piece of electro-optic material can be turned away from the waveguide core, which is beneficial to reducing the transition loss between the waveguide core and the waveguide core-electro-optic material hybrid waveguide.

[0046] (3) The method for preparing the electro-optic modulation device provided by the present invention is to cut out a plurality of electro-optic material thin film units from the structure after removing the patterned barrier layer, wherein the electro-optic material thin film units sequentially include a stacked portion of the electro-optic material thin film with a slope structure and a corresponding buried layer and a first substrate, and bond the electro-optic material thin film units to the corresponding position of the waveguide core, thereby avoiding the etching process of the electro-optic material thin film (such as lithium niobate) and improving the utilization rate of the electro-optic material thin film. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0048] Figure 1 A schematic diagram of a process for preparing an electro-optical modulation device according to an embodiment of the present invention;

[0049] Figure 2 to Figure 8B A schematic structural diagram of each process of a method for preparing an electro-optical modulation device according to an embodiment of the present invention;

[0050] FIG. 9A to FIG. 15D A schematic diagram of the structures of the steps in a specific process of a method for preparing an electro-optical modulation device according to an embodiment of the present invention;

[0051] FIG. 16A to FIG. 20D The present invention is a structural schematic diagram of each step in a specific process of a method for preparing another electro-optical modulation device according to an embodiment of the present invention.

[0052] Fig.21 A schematic diagram of a specific process of a method for preparing an electro-optical modulation device according to an embodiment of the present invention;

[0053] Fig. 22 The figure is a schematic diagram of a specific process of a method for preparing another electro-optical modulation device according to an embodiment of the present invention.

[0054] Description of reference numerals:

[0055] 11-first substrate; 12-buried layer; 13-electro-optic material film; 130-electro-optic material film piece; 131-electro-optic material connection point; 132-slope electro-optic material film; 14-barrier layer; 21-second substrate; 22-lower cladding; 23-waveguide core; 24-bonding dielectric layer; 26-electrode; 27-upper cladding; 100-grinding wheel; 200-micro-transfer device; 300-an electro-optic modulation device; 400-another electro-optic modulation device. DETAILED DESCRIPTION

[0056] In the prior art, one of the problems faced by heterogeneous integration of lithium niobate and silicon nitride waveguide platforms is the low-loss transition of the optical field between the silicon nitride waveguide and the silicon nitride-lithium niobate composite waveguide. The existing technical solutions for realizing the light field transition between lithium niobate and silicon nitride waveguide all have certain defects: Solution 1: Integrate lithium niobate with a two-dimensional conical structure into a silicon nitride platform through a micro-transfer process to realize the light field transition, but this solution requires that the two-dimensional conical structure and the silicon nitride optical waveguide core have a high alignment accuracy, which increases the process difficulty; Solution 2: Perform multiple dry etching on lithium niobate so that lithium niobate forms multiple steps along both sides of the silicon nitride waveguide core to realize the light field transition. Since dry etching of lithium niobate is relatively difficult, the process difficulty is high, and there is a potential contamination problem that will lead to incompatibility with CMOS process equipment; Solution 3: Use sputtering to form a mask with a gradient thickness on the surface of the film, and use chemical mechanical polishing (CMP) to make the lithium niobate film have a gradient thickness. However, this solution has the problems of low mask efficiency, difficulty in forming multiple gradient thickness masks on the same substrate, or the mask size (resulting in the size of the gradient thickness film) cannot be accurately controlled.

[0057] In addition, there is another solution that uses grayscale lithography and dry etching to form a slope structure on lithium niobate or a material with a refractive index similar to that of lithium niobate to achieve light field transition. However, it is difficult to form a gradually changing slope structure on a thinner (several hundred nanometers thick) electro-optical material film using grayscale lithography + etching process: first, grayscale lithography requires a costly mask or a complex encoding process; second, dry etching of lithium niobate is relatively difficult, and it is not easy to control the thickness and surface roughness. Third, when forming a slope structure on lithium niobate, its dry etching is usually based on physical etching (the etching selectivity for photoresist, optoelectronic materials, and waveguide substrate surface materials is relatively low), which can easily cause damage to the waveguide substrate itself; fourth, when forming a slope structure on other materials with a refractive index similar to that of lithium niobate, the refractive index and thickness deviations of other materials and optoelectronic materials will also cause light scattering and increase the light transition loss.

[0058] In order to solve the problems in the existing preparation method of electro-optical modulation device that the micro-transfer of two-dimensional conical structure lithium niobate is difficult, the thickness of the mask is difficult to accurately control, and the lithium niobate etching step cannot be reduced or avoided, and to achieve low light field transition loss between silicon nitride waveguide and silicon nitride-lithium niobate composite waveguide, the present invention provides a preparation method of electro-optical modulation device, comprising: providing an electro-optical material film wafer, the electro-optical material film wafer sequentially comprising a stacked first substrate, a buried layer and an electro-optical material film; forming a blocking layer on the side of the electro-optical material film facing away from the buried layer, etching the blocking layer to form a patterned blocking layer, and exposing multiple columns of electro-optical material films in the opening area of ​​the patterned blocking layer; using a grinding wheel to grind the exposed multiple columns of electro-optical material films along the opening area until the buried layer is exposed to form a surface with a slope structure on both sides. Strip grooves; the strip grooves penetrate the electro-optic material film in the depth direction and penetrate into the buried layer; remove the patterned barrier layer; cut a number of electro-optic material film units from the structure after removing the patterned barrier layer; the electro-optic material film unit includes a portion of the electro-optic material film defined by two adjacent strip grooves; provide a second substrate, and sequentially form a lower cladding layer, a waveguide core and a bonding dielectric layer on a surface of one side of the second substrate, the bonding dielectric layer covers a surface of the waveguide core facing away from the second substrate and a side surface of the waveguide core; bond the electro-optic material film unit to a surface of the bonding dielectric layer facing away from the waveguide core; wherein the electro-optic material film unit corresponds to the waveguide core; the slope structure is located on both sides of the length direction of the waveguide core; electrodes are formed on a surface of the electro-optic material film unit facing away from the bonding dielectric layer, and the electrodes are located at corresponding positions on both sides of the waveguide core.

[0059] The technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. In the description of the present invention, it should be noted that the terms "first", "second" and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0060] Example 1

[0061] like Figure 1 As shown, this embodiment provides a method for preparing an electro-optic modulation device, including steps S101 to S108.

[0062] S101 , providing an electro-optic material thin film wafer, wherein the electro-optic material thin film wafer includes a stacked first substrate 11 , a buried layer 12 , and an electro-optic material thin film 13 .

[0063] In specific implementation, the structure of the electro-optical material thin film wafer is as follows: Figure 2As shown, the material of the buried layer 12 can be silicon dioxide with a thickness of 50nm to 5um; the electro-optical material film 13 can be a single crystal film of lithium niobate, lithium tantalate, barium titanate or the like, and the thickness of the electro-optical material film 13 is 100nm to 500nm.

[0064] S102, forming a barrier layer 14 on the side of the electro-optic material film 13 facing away from the buried layer 12, etching the barrier layer to form a patterned barrier layer 14; the opening area of ​​the patterned barrier layer 14 exposes a plurality of columns of the electro-optic material film 13;

[0065] In a specific implementation, a barrier layer 14 is first formed on the side of the electro-optical material film 13 facing away from the buried layer 12. Figure 3 Then the barrier layer 14 is etched to form a patterned barrier layer 14, as shown Figure 4A and Figure 4B As shown, Figure 4A is a top view of the patterned barrier layer 14, Figure 4B To overlook Figure 4A The cross-sectional view at position ① in the middle. The pattern of the graphic barrier layer is in the shape of parallel strips, and the opening area exposes multiple parallel rows of electro-optical material films 13. The hardness of the material of the barrier layer is higher than that of the electro-optical material film. In one embodiment, the material of the electro-optical material film is lithium niobate, the material of the barrier layer is chromium, and the thickness of the barrier layer is 0.1μm to 2μm.

[0066] S103, using a grinding wheel 100 to grind the exposed multiple rows of electro-optical material films 13 along the opening area until the buried layer 12 is exposed, forming a strip groove with a slope structure on both sides, such as Figure 5A and Figure 5B or Fig. 6A and Figure 6B As shown; the strip-shaped groove penetrates the electro-optical material film 13 and penetrates into the buried layer 12 in the depth direction.

[0067] S104, removing the patterned barrier layer, such as Fig. 7A and Figure 7B or Fig. 8A and Figure 8B shown.

[0068] S105, cutting out a plurality of electro-optical material thin film units from the structure after removing the patterned blocking layer; the electro-optical material thin film unit includes a portion of the electro-optical material thin film defined by two adjacent strip-shaped grooves.

[0069] S106, providing a second substrate 21, and sequentially forming a lower cladding layer 22, a waveguide core 23, and a bonding dielectric layer 24 on a side surface of the second substrate 21, wherein the bonding dielectric layer 24 covers a side surface of the waveguide core 23 facing away from the second substrate 21 and a side surface of the waveguide core 23, such as Figures 12A to 12C shown.

[0070] S107, bonding the electro-optical material thin film unit to the surface of the bonding medium layer 24 facing away from the waveguide core 23; wherein the electro-optical material thin film unit corresponds to the waveguide core 23; and the slope structure is located on both sides of the length direction of the waveguide core 23;

[0071] S108 , forming electrodes on a surface of the electro-optical material thin film unit that faces away from the bonding dielectric layer 24 , and the electrodes are located at corresponding positions on both sides of the waveguide core 23 .

[0072] In specific implementation, the material of the electrode can be a conductive material such as Au, Al, Cu, W, ITO, etc., the distance between the two electrodes is preferably 4μm to 10μm, the thickness of the electrode is 0.3μm to 1.2μm, and the length direction of the electrode is consistent with the length direction of the waveguide core;

[0073] The preparation method of the electro-optical modulator provided in this embodiment, on the one hand, accurately defines the size of the electro-optical material film unit and the position of the slope structure through the graphical (photolithography + etching process) barrier layer, and through (rigid) grinding wheel grinding and barrier layer to control the grinding rate, the efficiency of obtaining the slope structure on the electro-optical material film unit is higher and the slope consistency is better. At the same time, only one step or no etching of the optoelectronic material film is required in the preparation process, which simplifies the preparation process flow and reduces the process difficulty; on the other hand, the slope structure preparation method in this scheme has low requirements for alignment accuracy, the surface roughness of the formed slope structure is small and the slope is easy to control, and there is no absorption loss caused by additional materials, so that the electro-optical modulator has lower transition loss. Therefore, the preparation method of the electro-optical modulator provided by the present invention, through the method of grinding wheel grinding and the barrier layer to control the grinding depth and uniformity, to prepare an electro-optical material film with a slope structure, and at the same time, the slope structure of the electro-optical material film is located on both sides of the length direction of the waveguide core, which can simplify the process flow, reduce the process difficulty, improve the process efficiency, and effectively reduce the light field transition loss of the electro-optical modulator.

[0074] Furthermore, in some embodiments, Figures 12A to 12C As shown, the method of sequentially forming a lower cladding layer 22, a waveguide core 23 and a bonding medium layer 24 on a surface of one side of a second substrate 21 includes:

[0075] A lower cladding layer 22 is formed on one side surface of the second substrate 21;

[0076] A waveguide core 23 is formed on a surface of the lower cladding layer 22 that faces away from the second substrate 21 .

[0077] A bonding dielectric layer 24 is formed on the surface of the waveguide core 23 facing away from the lower cladding layer 22 ; the bonding dielectric layer 24 also covers the surface of the lower cladding layer 22 facing away from the second substrate 21 and the side surface of the waveguide core 23 .

[0078] When implementing it, Figures 12A to 12C As shown, first, a lower cladding layer 22 is formed on the surface of the second substrate 21, and then a waveguide core layer (such as Fig. 12A As shown), the waveguide core layer is patterned again to form a waveguide core 23 (as shown Fig. 12B Finally, a bonding dielectric layer 24 (as shown) is formed on the surface of the waveguide core 23 facing away from the lower cladding layer 22. Fig. 12C The bonding dielectric layer 24 also covers the side surface of the lower cladding layer 22 facing away from the second substrate 21 and the side surface of the waveguide core 23.

[0079] The material of the second substrate 21 is silicon, silicon carbide, etc., the material of the lower cladding 22 is silicon dioxide, etc., the thickness of the lower cladding 22 is 4μm to 20μm, the waveguide core 23 can be silicon nitride, silicon, etc., the waveguide core 23 can be a strip waveguide, a double strip waveguide or a combination thereof, the waveguide core 23 can be straight or curved, and the width and height of the waveguide core 23 are determined according to optical needs. The material of the bonding dielectric layer 24 can be inorganic or organic materials such as silicon dioxide, aluminum oxide, benzocyclobutene (BCB) and its derivatives, or a combination thereof. The thickness of the bonding dielectric layer above the waveguide core is 10nm to 300nm.

[0080] Further, in some embodiments, the width of the grinding wheel 100 is greater than the width of the electro-optical material film 13 exposed in the opening area;

[0081] The ratio of the projection length of the slope structure in the horizontal direction to the thickness of the electro-optical material film is 10:1 to 500:1, for example, 10:1, 100:1, 250:1, 400:1 or 500:1.

[0082] When implementing it, Figure 5A , Figure 5B , Fig. 6A and Figure 6B As shown, the width of the grinding wheel 100 is greater than the width of the electro-optical material film 13 exposed in the opening area, so that in the process of grinding the multiple rows of electro-optical material films exposed along the opening area with the grinding wheel 100, the grinding depth and uniformity of the grinding wheel 100 can be better controlled by the patterned barrier layer 14. In some examples, the axis of the grinding wheel 100 is horizontal (the grinding wheel rotates vertically), and the width of the grinding wheel 100 refers to the width of the grinding wheel (excluding the axis); in other examples, the axis of the grinding wheel 100 is vertical (the grinding wheel rotates horizontally), and the width of the grinding wheel 100 refers to the diameter of the grinding wheel.

[0083] Furthermore, in some embodiments, Figure 5A , Figure 5B , Fig. 7A and Figure 7B As shown, the cross section of the strip groove is V-shaped, and the slope structure is a plane slope structure;

[0084] The cross section of the lowest position where the grinding wheel 100 contacts the electro-optical material film 13 and the burying layer 12 is an obtuse angle.

[0085] When it comes to specific implementation, Figure 5A , Figure 5B , Fig. 7A and Figure 7B The process of forming a planar slope structure is that the cross section of the lowest position of the grinding wheel 100 is an obtuse angle, the cross section of the formed strip groove is a V-shape, and the formed slope structure is a planar slope structure. Figure 5A This is a top view of the V-shaped groove formed after grinding by the grinding wheel. Figure 5B for Figure 5A Cross-sectional view at position ① in the middle; Fig. 7A The top view of the V-shaped strip groove after removing the patterned barrier layer. Figure 7B for Fig. 7A Cross-sectional view at position ① in the middle.

[0086] Further, in some embodiments, the obtuse angle is 165° to 179.8°;

[0087] The width of the opening area is greater than or equal to 2×L×(H+h) / h, where L is the projection length of the slope structure on the horizontal plane, h is the thickness of the electro-optical material film 13 , and H is the thickness of the blocking layer 14 .

[0088] Furthermore, in some embodiments, Fig. 6A , Figure 6B , Fig. 8A and Figure 8B As shown, the cross section of the strip groove is arc-shaped, and the slope structure is a curved slope structure;

[0089] The cross section of the lowest position where the grinding wheel contacts the electro-optical material film 13 and the burying layer 12 is an arc.

[0090] When it comes to specific implementation, Fig. 6A , Figure 6B , Fig. 8A and Figure 8B In the process of forming a curved slope structure, the cross section of the lowest position of the grinding wheel 100 is an arc, the cross section of the formed strip groove is an arc, and the formed slope structure is a curved slope structure. Fig. 6A This is a top view of the arc-shaped strip groove formed after grinding with a grinding wheel. Figure 6B for Fig. 6A Cross-sectional view at position ① in the middle;

[0091] Fig. 8A The top view of the arc-shaped strip groove after removing the patterned barrier layer. Figure 8B for Fig. 8A Cross-sectional view at position ① in the middle.

[0092] Further, in some embodiments, the radius of curvature of the arc is 5 μm to 6.5 cm;

[0093] The width of the opening area is greater than or equal to Wherein, L is the projection length of the slope structure on the horizontal plane, h is the thickness of the electro-optical material film 13 , and H is the thickness of the barrier layer 14 .

[0094] Furthermore, in some embodiments, after the step of grinding the exposed multiple rows of electro-optical material films 13 along the opening area using a grinding wheel 100 until the buried layer 12 is exposed to form a strip groove with slope structures on both sides, the method further includes:

[0095] The slope structure is subjected to a chemical mechanical polishing process to reduce the roughness of the slope structure.

[0096] Furthermore, in some embodiments, the electro-optical material film unit is an electro-optical material film piece 130 having a slope structure;

[0097] The step of cutting a plurality of electro-optical material thin film units from the structure after removing the patterned blocking layer comprises:

[0098] The electro-optic material film remaining after grinding by the grinding wheel is patterned to form a plurality of electro-optic material film pieces 130, such as Figures 9A to 9C As shown; the electro-optical material thin film sheet comprises a first electro-optical material thin film sheet and a second electro-optical material thin film sheet; wherein both sides of the non-slope surface of the first electro-optical material thin film sheet are connected to two adjacent second electro-optical material thin film sheets through fine electro-optical material connection points 131;

[0099] Wet etching removes the buried layer 12 below the electro-optical material thin film chip 130, such as Fig.10 As shown; wherein the width of the first electro-optical material thin film piece is smaller than the width of the two second electro-optical material thin film pieces connected thereto, the first electro-optical material thin film piece is connected to the two adjacent second electro-optical material thin film pieces only through the electro-optical material connection point and is suspended in the air, while the two adjacent second electro-optical material thin film pieces are still connected to the first substrate 11 through the buried layer 12;

[0100] The electro-optic material connection points 131 between the electro-optic material thin film pieces 130 are disconnected by using the micro-transfer printing device 200, so that the electro-optic material thin film pieces 130 are separated from the first substrate 11. Fig.11 shown.

[0101] In a specific implementation, the electro-optical material film piece 130 has sloped electro-optical material films 132 on both sides. The sloped structures on both sides make the edge thickness of the electro-optical material film piece 130 gradually decrease (linearly or nonlinearly) from the inside to the outside, preferably decreasing to 0. Fig.9A To cut out the top view of the electro-optical material film piece 130, Fig. 9B for Fig.9A The enlarged top view of the dotted box in the middle, Fig. 9C for Fig. 9B Cross-sectional view at position ② in the middle.

[0102] Furthermore, in some embodiments, the step of bonding the electro-optical material thin film unit to the surface of the bonding dielectric layer on one side facing away from the waveguide core includes:

[0103] The electro-optical material thin film chip 130 is bonded to the surface of the bonding medium layer 24 facing away from the waveguide core 23 using a micro-transfer printing device 200. Fig.13 As shown; wherein, the electro-optical material thin film piece 130 corresponds to the waveguide core 23; the slope of the electro-optical material thin film piece 130 faces away from the waveguide core 23.

[0104] In a specific implementation, the electro-optic material film piece 130 corresponds to the position of the waveguide core, and the electro-optic material film piece 130 has a slope structure on both sides along the length direction of the waveguide core 23, and the slope of the electro-optic material film piece 130 faces away from the waveguide core 23. The sloped electro-optic material film 132 makes the edge thickness of the electro-optic material film piece 130 gradually decrease from the inside to the outside (linearly or nonlinearly), thereby making the transition between the waveguide core and the waveguide core-electro-optic material composite waveguide smoother, which can reduce the optical field transition loss of the electro-optic modulation device.

[0105] Furthermore, in some embodiments, after the step of forming an electrode on the surface of the electro-optical material film unit facing away from the bonding dielectric layer, the method further includes:

[0106] An upper cladding layer 27 is formed on the surface of the bonding dielectric layer 24 facing away from the lower cladding layer 22. The upper cladding layer 27 covers the bonding dielectric layer 24, the electro-optical material film piece 130 and the electrode 26. Fig.15A , Fig. 15B , Fig. 15C and Fig.15D As shown;

[0107] The upper cladding layer 27 is subjected to a planarization process.

[0108] In a specific implementation, the material of the upper cladding layer 27 is silicon dioxide, and the thickness of the upper cladding layer 27 is 4 to 10 um; Fig.15A is a top view of an electro-optic modulation device 300, Fig. 15B for Fig.15A Side view from the middle direction ④, Fig. 15C and Fig.15D for Fig.15A Side view from the middle direction ③, Fig. 15C The electro-optical material thin film piece 130 has a flat slope structure on both sides. Fig.15D Both sides of the electro-optical material film piece 130 have curved slope structures.

[0109] Furthermore, in some embodiments, Fig.17 As shown, the electro-optical material film unit sequentially includes a stacked portion of the electro-optical material film 13 having a slope structure and a corresponding buried layer 12 and a first substrate 11;

[0110] The step of cutting a plurality of electro-optical material thin film units from the structure after removing the patterned blocking layer comprises:

[0111] The electro-optic material film wafer is cut along the strip groove and in the direction perpendicular to the strip groove to obtain a plurality of electro-optic material film units, such as Fig.16A , Fig. 16B and Fig. 16C shown.

[0112] When it comes to specific implementation, Fig.16A This is a top view of the electro-optical material thin film wafer. Fig. 16B and Fig. 16C for Fig.16A Cross-sectional view of the cutting position, Fig. 16B The electro-optical material film 13 has a planar slope structure on both sides; Fig. 16C The electro-optical material film 13 in the electro-optical material film unit has curved surface and slope surface structures on both sides. The electro-optical material film 13 in the electro-optical material film unit has slope surface electro-optical material films 132 on both sides.

[0113] Furthermore, in some embodiments, the step of bonding the electro-optical material thin film unit to the surface of the bonding medium layer 24 facing away from the waveguide core 23 includes:

[0114] The electro-optical material thin film unit is bonded to the surface of the bonding medium layer 24 facing away from the waveguide core 23, such as Fig.18 As shown; wherein the electro-optic material film 13 is in contact with and bonded to the bonding dielectric layer 24; the electro-optic material film 13 corresponds to the waveguide core 23; the slope of the electro-optic material film 13 faces one side of the waveguide core 23;

[0115] Remove the first substrate, such as Fig.19 shown.

[0116] Furthermore, in some embodiments, the step of forming an electrode on a surface of the electro-optical material film unit that is opposite to the electro-optical material film includes:

[0117] An electrode 26 is formed on the surface of the buried layer 12 facing away from the electro-optical material film 13. Fig. 20A , Fig. 20B , Fig. 20C and Fig.20D shown.

[0118] Fig. 20A is a top view of another electro-optic modulation device 400, Fig. 20B for Fig. 20A Side view from the middle direction ⑥, Fig. 20C and Fig.20D for Fig. 20A Side view from the middle direction ⑤, Fig. 20C The electro-optical material film 13 has a planar slope structure on both sides. Fig.20D The two sides of the electro-optical material film 13 have curved slope structures.

[0119] Example 2

[0120] refer to Fig.21 This embodiment provides a specific process of a method for preparing an electro-optic modulation device 300, including steps S201-S212:

[0121] S201 to S204 are the same as steps S101 to S104 and will not be described in detail here. Figure 2 to Figure 5B The material of the buried layer 12 is silicon dioxide, with a thickness of 50nm to 5μm; the material of the electro-optical material film 13 is lithium niobate, with a thickness of 100nm to 500nm; the material of the blocking layer 14 is chromium, with a thickness of 0.1μm to 2μm.

[0122] S205, patterning the electro-optical material film remaining after grinding by the grinding wheel 100 to form a plurality of electro-optical material film pieces 130, such as Figures 9A to 12C As shown; the electro-optical material film sheet 130 includes a first electro-optical material film sheet and a second electro-optical material film sheet; wherein both sides of the non-slope surface of the first electro-optical material film sheet are connected to two adjacent second electro-optical material film sheets through fine electro-optical material connection points.

[0123] S206, wet etching to remove the buried layer 12 below the electro-optical material thin film chip 130, such as Fig.10 As shown; wherein the width of the first electro-optical material thin film piece is smaller than the width of the two second electro-optical material thin film pieces connected thereto, the first electro-optical material thin film piece is connected to the two adjacent second electro-optical material thin film pieces only through the electro-optical material connection point and is suspended in the air, while the two adjacent second electro-optical material thin film pieces are still connected to the first substrate 11 through the buried layer 12;

[0124] S207, using the micro-transfer device 200 to disconnect the electro-optic material connection points 131 between the electro-optic material thin film pieces 130, so that the electro-optic material thin film pieces 130 are separated from the first substrate 11, as shown in FIG. Fig.11 shown.

[0125] S208, providing a second substrate 21, sequentially forming a lower cladding layer 22, a waveguide core 23 and a bonding dielectric layer 24 on a side surface of the second substrate 21, wherein the bonding dielectric layer 24 covers a side surface of the waveguide core 23 facing away from the second substrate 21 and a side surface of the waveguide core 23, such as Figures 12A to 12C As shown;

[0126] In a specific implementation, the material of the second substrate 21 is silicon; the material of the lower cladding 22 is silicon dioxide, and the thickness of the lower cladding 22 is 4μm to 20μm; the material of the waveguide core 23 is silicon nitride, and the waveguide core 23 is a strip waveguide; the material of the bonding dielectric layer 24 is silicon dioxide, and the thickness of the bonding dielectric layer 24 located above the waveguide core 23 is 10nm to 300nm.

[0127] S209, using the micro-transfer device 200 to bond the electro-optical material thin film chip 130 to the surface of the bonding medium layer 24 facing away from the waveguide core 23, such as Fig.13 As shown; wherein, the electro-optical material film piece 130 corresponds to the waveguide core 23; the electro-optical material film piece 130 has a slope structure on both sides along the length direction of the waveguide core 23; the slope of the electro-optical material film piece 130 is facing away from the waveguide core 23.

[0128] S210, forming electrodes 26 on the surface of the electro-optical material thin film chip 130 facing away from the bonding dielectric layer 24, and the electrodes 26 are located at corresponding positions on both sides of the waveguide core 23, such as Fig.14 shown.

[0129] S211, forming an upper cladding layer 27 on the surface of the bonding dielectric layer 24 facing away from the lower cladding layer 22, the upper cladding layer 27 covers the bonding dielectric layer 24, the electro-optical material film piece 130 and the electrode 26; FIG. 15A to FIG. 15D shown.

[0130] S212 , performing a planarization process on the upper cladding layer 27 .

[0131] The preparation method of the electro-optical modulation device provided in this embodiment heterogeneously integrates a small piece of electro-optical material with a slope structure into the corresponding position of the waveguide core through a micro-transfer process, so that the slope surface of the slope structure of the small piece of electro-optical material can be turned away from the waveguide core, which is beneficial to reducing the transition loss between the (silicon nitride) waveguide and the (silicon nitride-lithium niobate) composite waveguide.

[0132] Example 3

[0133] refer to Fig. 22 This embodiment provides a specific process of another method for preparing an electro-optic modulation device 400, including steps S301-S309:

[0134] S301 to S304 are the same as steps S101 to S104 and will not be described in detail here. Figure 2 to Figure 5B The material of the buried layer 12 is silicon dioxide, with a thickness of 50nm to 5μm; the material of the electro-optical material film 13 is lithium niobate, with a thickness of 100nm to 500nm; the material of the barrier layer 14 is chromium, with a thickness of 0.1μm to 2μm.

[0135] S305, cutting the electro-optic material thin film wafer along the strip grooves and in a direction perpendicular to the strip grooves to obtain a plurality of electro-optic material thin film units, such as Figures 16A to 16C As shown; the electro-optical material film unit sequentially includes a stacked portion of the electro-optical material film 13 having a slope structure and a corresponding buried layer 12 and a first substrate 11, such as Fig.17 As shown;

[0136] S306, similar to step S208, provides a second substrate 21, sequentially forms a lower cladding layer 22, a waveguide core 23 and a bonding dielectric layer 24 on one side surface of the second substrate 21, and the bonding dielectric layer 24 covers a side surface of the waveguide core 23 facing away from the second substrate 21 and a side surface of the waveguide core 23, such as Figures 12A to 12C As shown;

[0137] In a specific implementation, the material of the second substrate 21 is silicon; the material of the lower cladding 22 is silicon dioxide, and the thickness of the lower cladding 22 is 4μm to 20μm; the material of the waveguide core 23 is silicon nitride, and the waveguide core 23 is a strip waveguide; the material of the bonding dielectric layer 24 is silicon dioxide, and the thickness of the bonding dielectric layer 24 located above the waveguide core 23 is 10nm to 300nm.

[0138] S307, bonding the electro-optical material thin film unit to the surface of the bonding medium layer 24 facing away from the waveguide core 23, such as Fig.18 As shown; wherein, the electro-optical material film 13 is in contact with and bonded to the bonding medium layer 24; the electro-optical material film 13 corresponds to the waveguide core 23; the electro-optical material film 13 has a slope structure on both sides along the length direction of the waveguide core 23; the slope of the electro-optical material film 13 faces one side of the waveguide core 23.

[0139] S308, removing the first substrate 11, such as Fig.19 shown.

[0140] S309, forming an electrode 26 on the surface of the buried layer 12 facing away from the electro-optical material film 13, such as Figures 20A to 20D shown.

[0141] The method for preparing the electro-optic modulation device provided in this embodiment cuts out a plurality of electro-optic material film units from the structure after removing the patterned barrier layer. The electro-optic material film units sequentially include stacked partial electro-optic material films with a slope structure and a corresponding buried layer and a first substrate. The electro-optic material film units are bonded to corresponding positions of the waveguide core. This can avoid etching the lithium niobate film and improve the utilization rate of the electro-optic material film.

[0142] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the invention.

Claims

1. A method for preparing an electro-optical modulation device, characterized in that: include: Providing an electro-optical material thin film wafer, wherein the electro-optical material thin film wafer sequentially comprises a first substrate, a buried layer and an electro-optical material thin film stacked in layers; forming a blocking layer on a side of the electro-optic material film facing away from the buried layer, etching the blocking layer to form a patterned blocking layer, wherein an opening area of ​​the patterned blocking layer exposes a plurality of columns of the electro-optic material film; Using a grinding wheel to grind the exposed multiple rows of electro-optical material films along the opening area until the buried layer is exposed to form a strip-shaped groove with slope structures on both sides; The strip-shaped groove penetrates the electro-optical material film in the depth direction and penetrates into the buried layer; removing the patterned barrier layer; cutting a plurality of electro-optical material thin film units from the structure after removing the patterned blocking layer; The electro-optical material film unit includes a portion of the electro-optical material film defined by two adjacent strip-shaped grooves; Providing a second substrate, and sequentially forming a lower cladding layer, a waveguide core, and a bonding dielectric layer on a surface of one side of the second substrate, wherein the bonding dielectric layer covers a surface of the waveguide core that is away from the second substrate and a side surface of the waveguide core; Bonding the electro-optical material film unit to the surface of the bonding medium layer facing away from the waveguide core; wherein the electro-optical material film unit corresponds to the waveguide core; and the slope structure is located on both sides of the length direction of the waveguide core; Electrodes are formed on a surface of the electro-optical material film unit that is away from the bonding dielectric layer, and the electrodes are located at corresponding positions on both sides of the waveguide core.

2. The method for preparing an electro-optical modulation device according to claim 1, characterized in that: The method of sequentially forming a lower cladding layer, a waveguide core and a bonding medium layer on a surface of one side of the second substrate comprises: forming the lower cladding layer on a surface of one side of the second substrate; A waveguide core and a bonding dielectric layer are formed on a surface of the lower cladding layer facing away from the second substrate, and the bonding dielectric layer covers a surface of the waveguide core facing away from the second substrate and a side surface of the waveguide core.

3. The method for preparing an electro-optical modulation device according to claim 1, characterized in that: The width of the grinding wheel is greater than the width of the electro-optical material film exposed in the opening area; The ratio of the projection length of the slope structure in the horizontal direction to the thickness of the electro-optical material film is 10:1 to 500:

1.

4. The method for preparing an electro-optical modulation device according to claim 3, characterized in that: The cross section of the strip-shaped groove is V-shaped, and the slope structure is a plane slope structure; The cross section of the lowest position where the grinding wheel contacts the electro-optical material film and the buried layer is an obtuse angle.

5. The method for preparing an electro-optical modulation device according to claim 4, characterized in that: The obtuse angle is 165° to 179.8°; The width of the opening area is greater than or equal to 2×L×(H+h) / h, wherein L is the projection length of the slope structure on the horizontal plane, h is the thickness of the electro-optical material film, and H is the thickness of the blocking layer.

6. The method for preparing an electro-optical modulation device according to claim 3, characterized in that: The cross section of the strip-shaped groove is arc-shaped, and the slope structure is a curved slope structure; The cross section of the lowest position where the grinding wheel contacts the electro-optical material film and the buried layer is an arc.

7. The method for preparing an electro-optical modulation device according to claim 6, characterized in that: The curvature radius of the arc is 5 μm to 6.5 cm; The width of the opening area is greater than or equal to Wherein, L is the projection length of the slope structure on the horizontal plane, h is the thickness of the electro-optical material film, and H is the thickness of the barrier layer.

8. The method for preparing an electro-optical modulation device according to claim 1, characterized in that: The electro-optical material film unit is a small electro-optical material film piece with a slope structure; The step of cutting a plurality of electro-optical material thin film units from the structure after removing the patterned barrier layer comprises: The electro-optical material film remaining after grinding by a grinding wheel is patterned to form a plurality of electro-optical material film pieces, wherein the electro-optical material film pieces include a first electro-optical material film piece and a second electro-optical material film piece; wherein both sides of the non-slope surface of the first electro-optical material film piece are connected to two adjacent second electro-optical material film pieces through tiny electro-optical material connection points; Wet etching is used to remove the buried layer below the electro-optical material thin film small piece; wherein the width of the first electro-optical material thin film small piece is smaller than the width of the two second electro-optical material thin film small pieces connected thereto, the first electro-optical material thin film small piece is only connected to the two adjacent second electro-optical material thin film small pieces through the electro-optical material connection point and is suspended in the air, while the two adjacent second electro-optical material thin film small pieces are still connected to the first substrate through the buried layer; The electro-optic material connection points between the electro-optic material film pieces are disconnected by using a micro-transfer printing device, so that the electro-optic material film pieces are separated from the first substrate.

9. The method for preparing an electro-optical modulation device according to claim 8, characterized in that: The step of bonding the electro-optical material thin film unit to a surface of the bonding medium layer facing away from the waveguide core comprises: The electro-optical material thin film small piece is bonded to the surface of the bonding medium layer on the side facing away from the waveguide core using a micro-transfer device; wherein the electro-optical material thin film small piece corresponds to the waveguide core; and the slope surface of the electro-optical material thin film small piece faces away from the waveguide core.

10. The method for preparing an electro-optical modulation device according to claim 1, characterized in that: The electro-optical material film unit sequentially comprises a stacked portion of the electro-optical material film having a slope structure and the corresponding buried layer and the first substrate; The step of cutting a plurality of electro-optical material thin film units from the structure after removing the patterned blocking layer comprises: The electro-optical material film wafer is cut along the strip groove and in a direction perpendicular to the strip groove to obtain a plurality of electro-optical material film units.

11. The method for preparing an electro-optical modulation device according to claim 10, characterized in that: The step of bonding the electro-optical material thin film unit to a surface of the bonding medium layer facing away from the waveguide core comprises: Bonding the electro-optical material film unit to the surface of the bonding dielectric layer on one side facing away from the waveguide core; wherein the electro-optical material film contacts and bonds with the bonding dielectric layer; the electro-optical material film corresponds to the waveguide core; and the slope of the electro-optical material film faces one side of the waveguide core; The first substrate is removed.

12. The method for preparing an electro-optical modulation device according to claim 11, characterized in that: The step of forming an electrode on a surface of the electro-optical material film unit facing away from the electro-optical material film comprises: The electrode is formed on a surface of the buried layer that is opposite to the electro-optical material film.

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