A method for fabricating an electro-optic modulating device

Abstract

The application relates to a preparation method of an electro-optic modulation device. The preparation method of the electro-optic modulation device comprises the following steps: forming a patterned blocking layer on one side of an electro-optic material film wafer; using a grinding wheel to grind a plurality of columns of electro-optic material films exposed by the patterned blocking layer along an opening area until a buried layer is exposed, so as to form a strip-shaped groove with a slope structure on both sides; cutting a plurality of electro-optic material film units from the structure after the patterned blocking layer is removed; the electro-optic material film unit comprises a part of the electro-optic material film defined by two adjacent strip-shaped grooves; and bonding the electro-optic material film unit to a surface of a bonding medium layer opposite to one side of a waveguide core; wherein the electro-optic material film unit corresponds to the waveguide core; and the slope structure is located on both sides of the waveguide core in the length direction. The preparation method of the electro-optic modulation device provided by the application can simplify the process flow, reduce the process difficulty, improve the process efficiency, and effectively reduce the optical field transition loss of the electro-optic modulation device.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor technology, and particularly relates to a preparation method of an electro-optical modulation device. BACKGROUND

[0002] The stoichiometric silicon nitride (Si3N4) thin film / waveguide core prepared by low pressure chemical vapor deposition (LPCVD) has the transparency in a wide wavelength range (400nm-2350nm), low light propagation loss of high optical power, and uses a wafer-level manufacturing process. The silicon nitride waveguide core and the waveguide platform composed of a silicon (Si) substrate and a silicon dioxide (SiO2) cladding realize extensive planar integrated devices and chip-level solutions. The phase modulator is one of the core devices of a photonic integrated circuit. The photonic platform based on silicon nitride can usually use thermal-optic effect, stress-optic effect, etc. to realize 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 still have deficiencies in speed, power and efficiency. A popular alternative is electro-optical modulation, but the electro-optical effect of silicon nitride is very weak, and it must be combined with materials with significant electro-optical effect to achieve efficient electro-optical phase modulation. Among them, single-crystal lithium niobate (LiNbO3) has strong electro-optical effect (1550nm: r 33 =30.8pm / V), large refractive index (1550nm: n o =2.21, n e =2.14), wide light transmission window (400nm-5μm) and stable physical and chemical properties, and becomes the most competitive electro-optical modulation material.

[0003] One of the problems faced by the heterogeneous integration of lithium niobate and silicon nitride waveguide platform 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 transition of the optical field between lithium niobate and silicon nitride waveguide all have certain defects: scheme one: a two-dimensional tapered structure of lithium niobate is integrated into a silicon nitride platform by a micro-transfer printing process to realize the transition of the optical field, but this scheme requires a high alignment accuracy between the two-dimensional tapered structure and the silicon nitride optical waveguide core, increasing the process difficulty; scheme two: lithium niobate is etched multiple times by dry etching to form multiple steps along the two sides of the silicon nitride waveguide core to realize the transition of the optical field. Since the dry etching of lithium niobate is relatively difficult, the process difficulty is high, and there is a potential pollution problem which will lead to the incompatibility of CMOS process equipment; scheme three: a thickness-graduated mask is formed on the surface of the thin film by sputtering, and the lithium niobate thin film is formed to have a thickness gradient by chemical mechanical grinding (CMP). However, in this scheme, there are problems such as low production efficiency of the mask, difficulty in forming multiple thickness-graduated masks on the same substrate, or difficulty in accurately controlling the size of the mask (resulting in the size of the thickness-graduated thin film).

[0004] Therefore, a preparation method of an electro-optical modulation device is needed, which uses one-step or lithium niobate-free etching process to realize low-loss transition between silicon nitride waveguide and silicon nitride-lithium niobate composite waveguide, thereby reducing transition loss of hetero-integrated electro-optical phase modulation device. SUMMARY

[0005] Therefore, the present application provides a preparation method of an electro-optical modulation device to solve the problems of high difficulty in micro-transferring two-dimensional tapered structure lithium niobate, high difficulty in dry etching of lithium niobate, difficulty in accurately controlling the thickness of the mask, and high optical field transition loss between silicon nitride waveguide and silicon nitride-lithium niobate composite waveguide in the preparation method of the existing electro-optical modulation device.

[0006] The present application provides a preparation method of an electro-optical modulation device, comprising:

[0007] An electro-optical material thin film wafer is provided, which comprises a first substrate, a buried layer and an electro-optical material thin film in sequence;

[0008] A barrier layer is formed on the side of the electro-optical material thin film away from the buried layer, the barrier layer is etched to form a patterned barrier layer, and the opening region of the patterned barrier layer exposes a plurality of columns of electro-optical material thin films;

[0009] A grinding wheel is used to grind the exposed plurality of columns of electro-optical material thin films along the opening region until the buried layer is exposed, forming a strip-shaped groove with a slope structure on both sides; the strip-shaped groove penetrates the electro-optical material thin film in the depth direction and extends into the buried layer;

[0010] The patterned barrier layer is removed;

[0011] A plurality of electro-optical material thin film units are cut from the structure after the patterned barrier layer is removed; the electro-optical material thin film unit comprises a portion of the electro-optical material thin film defined by the adjacent two strip-shaped grooves;

[0012] A second substrate is provided, and a lower cladding layer, a waveguide core and a bonding medium layer are sequentially formed on one side surface of the second substrate, and the bonding medium layer covers the side surface of the waveguide core away from the second substrate and the side surface of the waveguide core;

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

[0014] An electrode is formed on the side surface of the electro-optical material thin film unit away from the bonding medium layer, and the electrode is located at the corresponding position on both sides of the waveguide core.

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

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

[0017] forming a waveguide core and a bonding medium layer on the one side surface of the lower cladding layer away from the second substrate, the bonding medium layer covering the one side surface of the waveguide core away from the second substrate and the 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 by the opening region.

[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 10:1-500:1.

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

[0021] The cross section of the lowest position of the grinding wheel in contact with the electro-optical material film and the buried layer is an obtuse angle.

[0022] Optionally, the size of the obtuse angle is 165°-179.8°.

[0023] The width of the opening region is greater than or equal to 2×L×(H+h) / h, wherein L is the projection length of the slope structure in 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 of the grinding wheel in contact with the electro-optical material film and the buried layer is a circular arc.

[0026] Optionally, the radius of curvature of the circular arc is 5μm-6.5cm.

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

[0028] Optionally, the electro-optical material film unit is an electro-optical material film piece with a slope structure.

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

[0030] The electro-optical material film remaining after the grinding of the grinding wheel is patterned to form a plurality of electro-optical material film pieces, the electro-optical material film pieces including first electro-optical material film pieces and second electro-optical material film pieces; wherein the two sides of the first electro-optical material film piece without slope are connected to the two adjacent second electro-optical material film pieces through small electro-optical material connecting points.

[0031] wet etching to remove the buried layer under the small pieces of electro-optical material film; wherein the width of the first small piece of electro-optical material film is smaller than the width of the two second small pieces of electro-optical material film connected thereto, the first small piece of electro-optical material film is suspended by the electro-optical material connecting points and connected to the two adjacent second small pieces of electro-optical material film, and the two adjacent second small pieces of electro-optical material film are still connected to the first substrate through the buried layer;

[0032] using a micro transfer device to disconnect the electro-optical material connecting points between the small pieces of electro-optical material film, and to separate the small pieces of electro-optical material film from the first substrate.

[0033] Optionally, the step of bonding the small piece of electro-optical material film to the side surface of the waveguide core opposite to the bonding medium layer includes:

[0034] using a micro transfer device to bond the small piece of electro-optical material film to the side surface of the waveguide core opposite to the bonding medium layer; 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 small piece of electro-optical material film sequentially includes a partial electro-optical material film with a slope surface structure, a corresponding buried layer, and a first substrate.

[0036] The step of cutting the small piece of electro-optical material film from the structure after removing the patterned blocking layer includes:

[0037] cutting the electro-optical material film wafer along the strip-shaped groove and the direction perpendicular to the strip-shaped groove to obtain the small piece of electro-optical material film.

[0038] Optionally, the step of bonding the small piece of electro-optical material film to the side surface of the waveguide core opposite to the bonding medium layer includes:

[0039] bonding the small piece of electro-optical material film to the side surface of the waveguide core opposite to the bonding medium layer; wherein the electro-optical material film is in contact with and bonded to the bonding medium layer; the electro-optical material film corresponds to the waveguide core; and the slope surface of the electro-optical material film faces the waveguide core.

[0040] removing the first substrate.

[0041] Optionally, the step of forming an electrode on the side surface of the small piece of electro-optical material film opposite to the electro-optical material film includes:

[0042] forming an electrode on the side surface of the buried layer opposite to the electro-optical material film.

[0043] The technical scheme of the present application has the following advantages:

[0044] (1) The preparation method of the electro-optical modulation device provided by the application, on the one hand, the size and the position of the slope structure of the electro-optical material film unit are accurately defined by the patterned (photolithography + etching process) blocking layer, and the efficiency of the slope structure on the electro-optical material film unit is higher and the slope consistency is better through (rigid) grinding wheel grinding and blocking layer control grinding rate, at the same time, only one step or no etching process is needed for the photoelectric material film in the preparation process, which simplifies the preparation process and reduces the process difficulty; on the other hand, the slope structure preparation method in the present scheme has lower alignment accuracy, the surface roughness of the formed slope structure is smaller and the slope is easy to control, and there is no absorption loss caused by additional materials, so that the electro-optical modulation device has lower transition loss. Therefore, the preparation method of the electro-optical modulation device provided by the application, by the method of grinding wheel grinding and blocking layer controlling grinding depth and uniformity, the electro-optical material film with slope structure is made, and the slope structure of the electro-optical material film is located on both sides of the waveguide core length direction, which can simplify the process, reduce the process difficulty, improve the process efficiency, and effectively reduce the optical field transition loss of the electro-optical modulation device.

[0045] (2) The preparation method of the electro-optical modulation device provided by the application, by the micro-transfer printing process, the electro-optical material small piece with slope structure is heterogeneously integrated to the corresponding position of the waveguide core, which can make the slope of the electro-optical material small piece slope away from the waveguide core, which is beneficial to reduce the transition loss between the waveguide core and the waveguide core-electro-optical material hybrid waveguide.

[0046] (3) The preparation method of the electro-optical modulation device provided by the application, by cutting a plurality of electro-optical material film units from the structure after removing the patterned blocking layer, the electro-optical material film unit sequentially includes a part of the electro-optical material film with slope structure and the corresponding buried layer and the first substrate, and the electro-optical material film unit is bonded to the corresponding position of the waveguide core, which can avoid etching process for the electro-optical material film (such as lithium niobate), and at the same time, the utilization rate of the electro-optical material film can be improved. BRIEF DESCRIPTION OF DRAWINGS

[0047] In order to more clearly illustrate the specific embodiments of the application or the technical solutions in the prior art, the drawings needed in the following specific embodiments or prior art description will be briefly introduced. Obviously, the drawings in the following description are some embodiments of the application, and those skilled in the art can also obtain other drawings according to these drawings without creating labor.

[0048] Figure 1 The flowchart of the preparation method of the electro-optical modulation device of an embodiment of the application;

[0049] Figures 2-8BA structure schematic diagram of each flow of a preparation method of an electro-optical modulation device according to an embodiment of the present application;

[0050] Figures 9A-15D A structure schematic diagram of each step in a specific flow of a preparation method of an electro-optical modulation device according to an embodiment of the present application;

[0051] Figures 16A-20D A structure schematic diagram of each step in a specific flow of a preparation method of another electro-optical modulation device according to an embodiment of the present application.

[0052] Figure 21 A structure schematic diagram of each flow of a preparation method of an electro-optical modulation device according to an embodiment of the present application;

[0053] Figure 22 A structure schematic diagram of each flow of a preparation method of another electro-optical modulation device according to an embodiment of the present application.

[0054] BRIEF DESCRIPTION OF DRAWINGS

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

[0056] In the prior art, one of the problems faced by the heterogeneous integration of lithium niobate and silicon nitride waveguide platform is the low-loss transition of optical field between the silicon nitride waveguide and the silicon nitride-lithium niobate composite waveguide. The existing technical solutions for realizing the transition of optical field between lithium niobate and silicon nitride waveguide all have certain defects: Solution one: a two-dimensional tapered structure of lithium niobate is integrated into a silicon nitride platform by a micro transfer process to realize the transition of optical field, but this solution requires a high alignment accuracy between the two-dimensional tapered structure and the silicon nitride optical waveguide core, which increases the process difficulty; Solution two: lithium niobate is etched by dry etching multiple times to form multiple steps along the two sides of the silicon nitride waveguide core to realize the transition of optical field. Since dry etching of lithium niobate is relatively difficult, the process difficulty is high, and there is a potential pollution problem which will lead to incompatibility with CMOS process equipment; Solution three: a thickness-graduated mask is formed on the surface of the thin film by sputtering, and the lithium niobate thin film is formed to have a thickness gradient by chemical mechanical grinding (CMP), but this solution has problems such as low efficiency of the mask, difficulty in forming multiple thickness-graduated masks on the same substrate, or inaccurate control of the size of the mask (resulting in the size of the thickness-graduated thin film).

[0057] In addition, there is a solution that gray scale lithography and dry etching process form slope structure on lithium niobate or material with similar refractive index to lithium niobate to realize light field transition. However, it is difficult to form a slowly-varying slope structure on a thin film of electro-optic material (a few hundred nanometers thick) by gray scale lithography + etching process: first, gray scale lithography needs a high-cost mask or a complex coding process; second, dry etching of lithium niobate is relatively difficult, and it is not easy to control the thickness and surface roughness. Third, the dry etching of the slope structure on the lithium niobate is usually dominated by physical etching (with low etching selectivity for photoresist, electro-optic material, and waveguide substrate surface material), which can easily damage the waveguide substrate itself; fourth, forming a slope structure on other materials with similar refractive index to lithium niobate will also cause light scattering and increase light transition loss due to the refractive index and thickness deviation between the other materials and the electro-optic material.

[0058] To solve the problems of high difficulty in micro-transferring two-dimensional tapered structure lithium niobate, difficulty in accurately controlling the thickness of the mask, and inability to reduce or avoid the lithium niobate etching step in the existing preparation method of electro-optic modulation device, and to realize low light field transition loss between silicon nitride waveguide and silicon nitride-lithium niobate composite waveguide, the present application provides a preparation method of an electro-optic modulation device, comprising: providing an electro-optic material thin film wafer, the electro-optic material thin film wafer comprising a first substrate, a buried layer and an electro-optic material thin film stacked in sequence; forming a barrier layer on the side of the electro-optic material thin film away from the buried layer, etching the barrier layer to form a patterned barrier layer, and the opening region of the patterned barrier layer exposes a plurality of columns of electro-optic material thin film; using a grinding wheel to grind the exposed plurality of columns of electro-optic material thin film along the opening region until the buried layer is exposed, forming a strip-shaped groove with slope structures on both sides; the strip-shaped groove penetrates the electro-optic material thin film in the depth direction and extends into the buried layer; removing the patterned barrier layer; cutting a plurality of electro-optic material thin film units from the structure after removing the patterned barrier layer; the electro-optic material thin film unit comprises a portion of the electro-optic material thin film defined by two adjacent strip-shaped grooves; providing a second substrate, forming a lower cladding layer, a waveguide core and a bonding medium layer on one side surface of the second substrate in sequence, and the bonding medium layer covers the side surface of the waveguide core away from the second substrate and the side surface of the waveguide core; bonding the electro-optic material thin film unit to the side surface of the bonding medium layer away from the waveguide core; wherein the electro-optic material thin film unit corresponds to the waveguide core; the slope structure is located on both sides of the waveguide core in the length direction; forming an electrode on the side surface of the electro-optic material thin film unit away from the bonding medium layer, and the electrode is located at the corresponding position on both sides of the waveguide core.

[0059] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort 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 should not be construed as indicating or implying relative importance.

[0060] Example 1

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

[0062] S101, provides an electro-optic material thin film wafer, the electro-optic material thin film wafer comprising a first substrate 11, a buried layer 12 and an electro-optic material thin film 13 stacked in sequence.

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

[0064] S102, a barrier layer 14 is formed on the side of the electro-optic material thin film 13 facing away from the buried layer 12, and the barrier layer is etched to form a patterned barrier layer 14; the opening area of ​​the patterned barrier layer 14 exposes multiple rows of electro-optic material thin films 13.

[0065] In specific implementation, a barrier layer 14 is first formed on the side of the electro-optic material thin film 13 facing away from the buried layer 12, such as... Figure 3 As shown; then the barrier layer 14 is etched to form a patterned barrier layer 14, as shown. Figure 4A and Figure 4B As shown, where Figure 4A This is a top view of the graphical blocking layer 14. Figure 4B From an overhead view Figure 4A A cross-sectional view at position ①. The patterned barrier layer has parallel stripes, and the opening area exposes multiple rows of parallel electro-optic material films 13. The barrier layer material has a higher hardness than the electro-optic material film. In one embodiment, the electro-optic material film is made of lithium niobate, the barrier layer is made of chromium, and the barrier layer thickness is 0.1 μm to 2 μm.

[0066] S103, using a grinding wheel 100, the exposed multi-row electro-optic material film 13 is ground along the opening area until the buried layer 12 is exposed, forming a strip-shaped groove with a sloping structure on both sides, such asFigure 5A and Figure 5B or Figure 6A and Figure 6B as shown; the bar-shaped groove penetrates the electro-optical material film 13 in the depth direction and extends into the buried layer 12.

[0067] S104, removing the patterned blocking layer, as shown in Figure 7A and Figure 7B or Figure 8A and Figure 8B as shown.

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

[0069] S106, providing a second substrate 21, sequentially forming a lower cladding layer 22, a waveguide core 23 and a bonding medium layer 24 on one side surface of the second substrate 21, the bonding medium layer 24 covering the side surface of the waveguide core 23 away from the second substrate 21 and the side surface of the waveguide core 23, as shown in Figures 12A-12C .

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

[0071] S108, forming an electrode on the side surface of the electro-optical material film unit away from the bonding medium layer 24, the electrode being located at the corresponding position on both sides of the waveguide core 23.

[0072] In specific implementation, the material of the electrode can be Au, Al, Cu, W, ITO and other conductive materials, the distance between the two electrodes is preferably 4 μm to 10 μm, the thickness of the electrode is 0.3 μm to 1.2 μm, 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 modulation device provided by the embodiment has the following advantages: on the one hand, the size of the electro-optical material film unit and the position of the slope structure are accurately defined by the patterned (lithography + etching process) blocking layer, and the slope structure is obtained on the electro-optical material film unit with higher efficiency and better slope consistency through (rigid) grinding wheel grinding and blocking layer controlled grinding rate, and the preparation process only needs one step or does not need to etch the photoelectric material film, thereby simplifying the preparation process and reducing the process difficulty; on the other hand, the slope structure preparation method in the scheme has lower alignment accuracy, the surface roughness of the formed slope structure is smaller and the slope is easy to control, and there is no absorption loss caused by additional materials, so that the electro-optical modulation device has lower transition loss. Therefore, the preparation method of the electro-optical modulation device provided by the embodiment can simplify the process, reduce the process difficulty, improve the process efficiency, and effectively reduce the optical field transition loss of the electro-optical modulation device by the method of grinding wheel grinding and blocking layer controlling grinding depth and uniformity, and the slope structure of the electro-optical material film is located on both sides of the waveguide core length direction.

[0074] Further, in some embodiments, as shown in FIG. 1, the method for forming the lower cladding layer 22, the waveguide core 23 and the bonding medium layer 24 on the one side surface of the second substrate 21 in sequence comprises: Figures 12A-12C

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

[0076] forming the waveguide core 23 on the one side surface of the lower cladding layer 22 away from the second substrate 21.

[0077] forming the bonding medium layer 24 on the one side surface of the waveguide core 23 away from the lower cladding layer 22; the bonding medium layer 24 also covers the one side surface of the lower cladding layer 22 away from the second substrate 21 and the side surface of the waveguide core 23.

[0078] Specifically, as shown in FIG. 2, first, the lower cladding layer 22 is formed on the surface of the second substrate 21, then the waveguide core layer is formed on the one side surface of the lower cladding layer 22 away from the second substrate 21, then the waveguide core 23 is formed by patterning the waveguide core layer, and finally, the bonding medium layer 24 is formed on the one side surface of the waveguide core 23 away from the lower cladding layer 22; the bonding medium layer 24 also covers the one side surface of the lower cladding layer 22 away from the second substrate 21 and the side surface of the waveguide core 23. Figures 12A-12C Figure 12A Figure 12B Figure 12C

[0079] ​​​​​The second substrate 21 is made of silicon, silicon carbide, etc., the lower cladding layer 22 is made of silicon dioxide, etc., the thickness of the lower cladding layer 22 is 4-20 μm, the waveguide core 23 is made of 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, the width and height of the waveguide core 23 are determined according to optical requirements. The bonding medium layer 24 is made of inorganic or organic materials such as silicon dioxide, aluminum oxide, benzocyclobutene (BCB) and derivatives thereof or a combination thereof. The thickness of the bonding medium layer above the waveguide core is 10-300 nm.

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

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

[0082] In particular implementation, as shown in Figure 5A , Figure 5B , Figure 6A and Figure 6B , the width of the grinding wheel 100 is greater than the width of the exposed electro-optical material film 13 in the opening region, so that the grinding depth and uniformity of the grinding wheel 100 can be better controlled by the patterned barrier layer 14 in the process of grinding the exposed columns of electro-optical material film along the opening region with the grinding wheel 100. 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 from left to right (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] Further, in some embodiments, as shown in Figure 5A , Figure 5B , Figure 7A and Figure 7B , the cross section of the strip-shaped groove is V-shaped, and the slope structure is a planar slope structure.

[0084] The cross section of the lowest position of the grinding wheel 100 in contact with the electro-optical material film 13 and the buried layer 12 is an obtuse angle.

[0085] In particular implementation, Figure 5A , Figure 5B , Figure 7A and Figure 7B , the cross section of the lowest position of the grinding wheel 100 is an obtuse angle, the cross section of the formed strip-shaped groove is V-shaped, and the formed slope structure is a planar slope structure. In particular implementation, Figure 5Aa top view of the V-shaped strip-shaped groove formed after the grinding of the grinding wheel, Figure 5B a top view of the V-shaped strip-shaped groove formed after the grinding of the grinding wheel, Figure 5A a cross-sectional view at the middle position ①. Figure 7A a top view of the V-shaped strip-shaped groove formed after the grinding of the grinding wheel, Figure 7B a top view of the V-shaped strip-shaped groove formed after the grinding of the grinding wheel, Figure 7A a cross-sectional view at the middle position ①.

[0086] Further, in some embodiments, the obtuse angle is 165°-179.8°.

[0087] The width of the opening region is greater than or equal to 2xLx(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] Further, in some embodiments, as shown in Figure 6A , Figure 6B , Figure 8A and Figure 8B , the cross section of the strip-shaped groove is arc-shaped, and the slope structure is a curved slope structure.

[0089] The cross section of the lowest position of the grinding wheel in contact with the electro-optical material film 13 and the buried layer 12 is a circular arc.

[0090] In particular implementation, Figure 6A , Figure 6B , Figure 8A and Figure 8B are the formation process of the curved slope structure, the cross section of the lowest position of the grinding wheel 100 is a circular arc, the cross section of the strip-shaped groove formed is arc-shaped, and the slope structure formed is a curved slope structure. Among them, Figure 6A a top view of the arc-shaped strip-shaped groove formed after the grinding of the grinding wheel, Figure 6B a top view of the arc-shaped strip-shaped groove formed after the grinding of the grinding wheel, Figure 6A a cross-sectional view at the middle position ①.

[0091] Figure 8A a top view of the arc-shaped strip-shaped groove formed after the grinding of the grinding wheel, Figure 8B a top view of the arc-shaped strip-shaped groove formed after the grinding of the grinding wheel, Figure 8A a cross-sectional view at the middle position ①.

[0092] Further, in some embodiments, the radius of curvature of the circular arc is 5 μm-6.5 cm.

[0093] The width of the opening region is greater than or equal to 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.

[0094] Further, in some embodiments, after the step of using the grinding wheel 100 to grind the exposed multiple columns of electro-optical material thin film 13 along the opening area until the buried layer 12 is exposed, forming a strip-shaped groove with slope structure on both sides, further comprising:

[0095] Performing a chemical mechanical polishing process on the slope structure to reduce the roughness of the slope structure.

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

[0097] In the step of cutting a plurality of electro-optical material thin film units from the structure after removing the patterned barrier layer, comprising:

[0098] Performing patterning on the electro-optical material thin film remaining after grinding with the grinding wheel, forming a plurality of electro-optical material thin film pieces 130, as shown in Figures 9A-9C The electro-optical material thin film piece includes a first electro-optical material thin film piece and a second electro-optical material thin film piece; wherein the non-slope sides of the first electro-optical material thin film piece are connected to the adjacent two second electro-optical material thin film pieces through small electro-optical material connecting points 131;

[0099] Performing wet etching to remove the buried layer 12 under the electro-optical material thin film piece 130, as shown in Figure 10 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, and the first electro-optical material thin film piece is suspended only by the electro-optical material connecting points connected to the adjacent two second electro-optical material thin film pieces, while the adjacent two second electro-optical material thin film pieces are still connected to the first substrate 11 through the buried layer 12;

[0100] Using a micro-transfer printing device 200 to break the electro-optical material connecting points 131 between the electro-optical material thin film pieces 130, so that the electro-optical material thin film pieces 130 are separated from the first substrate 11, as shown in Figure 11 .

[0101] In specific implementation, the electro-optical material thin film piece 130 has two sides of slope electro-optical material thin film 132, and the slope structure on both sides causes the edge thickness of the electro-optical material thin film piece 130 to gradually decrease (linearly or nonlinearly) from inside to outside, preferably to 0. Among them, Figure 9A is a top view of the electro-optical material thin film piece 130 being cut, Figure 9B is Figure 9A is an enlarged top view of the dashed box in Figure 9C is Figure 9B is a cross-sectional view at position ② in

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

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

[0104] In specific implementation, the electro-optic material thin film 130 corresponds to the waveguide core in position. The electro-optic material thin film 130 has a sloping structure on both sides along the length of the waveguide core 23, with the sloping surfaces of the electro-optic material thin film 130 facing away from the waveguide core 23. The sloping electro-optic material thin film 132 makes the edge thickness of the electro-optic material thin film 130 gradually decrease from the inside to the outside (linear or nonlinear), thereby making the transition between the waveguide core and the waveguide core-electro-optic material composite waveguide smoother and reducing 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-optic material thin film unit opposite to the bonding dielectric layer, the method further includes:

[0106] An upper cladding layer 27 is formed on the side surface of the bonding dielectric layer 24 opposite to the lower cladding layer 22. The upper cladding layer 27 covers the bonding dielectric layer 24, the electro-optic material thin film 130, and the electrode 26. Figure 15A , Figure 15B , Figure 15C and Figure 15D As shown;

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

[0108] In specific implementation, the material of the upper cladding layer 27 is silicon dioxide, and the thickness of the upper cladding layer 27 is 4-10 μm; Figure 15A This is a top view of an electro-optic modulation device 300. Figure 15B for Figure 15A Side view of direction ④ in the middle. Figure 15C and Figure 15D for Figure 15A Side view of direction ③ in the middle. Figure 15C The electro-optic material thin film 130 has a planar sloping structure on both sides. Figure 15D The 130 thin film of Zhongdian Optoelectronic Materials has curved slope structure on both sides.

[0109] Furthermore, in some embodiments, such as Figure 17 As shown, the electro-optic material thin film unit sequentially includes a partially electro-optic material thin film 13 with a slope structure, a corresponding buried layer 12, and a first substrate 11.

[0110] cutting a plurality of electro-optical material film units from the structure after removing the patterned blocking layer, comprising:

[0111] cutting the electro-optical material film wafer along the strip-shaped groove and the direction perpendicular to the strip-shaped groove respectively to obtain a plurality of electro-optical material film units, as shown in Figure 16A 、 Figure 16B and Figure 16C .

[0112] In specific implementation, Figure 16A is a top view of the electro-optical material film wafer, Figure 16B and Figure 16C are cross-sectional views of the cutting position in Figure 16A , the electro-optical material film 13 in Figure 16B has a planar slope surface structure on both sides thereof; Figure 16C has a curved slope surface structure on both sides thereof. The electro-optical material film 13 in the electro-optical material film unit has a slope electro-optical material film 132 on both sides thereof.

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

[0114] bonding the electro-optical material film unit to the side surface of the bonding medium layer 24 away from the waveguide core 23, as shown in Figure 18 ; 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 slope surface of the electro-optical material film 13 faces the side of the waveguide core 23;

[0115] removing the first substrate, as shown in Figure 19 .

[0116] Further, in some embodiments, the step of forming an electrode on the side surface of the electro-optical material film unit away from the electro-optical material film comprises:

[0117] forming an electrode 26 on the side surface of the buried layer 12 away from the electro-optical material film 13, as shown in Figure 20A 、 Figure 20B 、 Figure 20C and Figure 20D .

[0118] Figure 20A is a top view of another electro-optical modulation device 400, Figure 20B is a side view of direction ⑥ in Figure 20A , Figure 20C and Figure 20D are side views of direction ⑤ in Figure 20A , Figure 20CThe electro-optic material film 13 has a planar slope structure on both sides. Figure 20D The thin film 13 of Zhongdian Optoelectronics has curved slope structure on both sides.

[0119] Example 2

[0120] refer to Figure 21 This embodiment provides a specific process for fabricating an electro-optic modulation device 300, including steps S201-S212:

[0121] Steps S201 to S204 are the same as steps S101 to S104, and will not be repeated here. (See reference) Figures 2-5B The buried layer 12 is made of silicon dioxide and has a thickness of 50 nm to 5 μm; the electro-optic material thin film 13 is made of lithium niobate and has a thickness of 100 nm to 500 nm; the barrier layer 14 is made of chromium and has a thickness of 0.1 μm to 2 μm.

[0122] S205, patterning the remaining electro-optic material film after grinding with grinding wheel 100 to form multiple electro-optic material film pieces 130, such as... Figures 9A-12C As shown; the electro-optic material thin film 130 includes a first electro-optic material thin film and a second electro-optic material thin film; wherein, the two non-slope sides of the first electro-optic material thin film are connected to two adjacent second electro-optic material thin films through tiny electro-optic material connection points.

[0123] S206, wet etching removes the buried layer 12 beneath the electro-optic material thin film 130, such as Figure 10 As shown; wherein, the width of the first electro-optic material thin film is smaller than the width of the two second electro-optic material thin film pieces connected to it, the first electro-optic material thin film piece is suspended only by being connected to the two adjacent second electro-optic material thin film pieces through electro-optic material connection points, while the two adjacent second electro-optic material thin film pieces are still connected to the first substrate 11 through the buried layer 12.

[0124] S207, the micro-transfer device 200 is used to disconnect the electro-optic material connection points 131 between the electro-optic material film pieces 130, causing the electro-optic material film pieces 130 to detach from the first substrate 11, as shown. Figure 11 As shown.

[0125] S208, a second substrate 21 is provided, and a lower cladding layer 22, a waveguide core 23, and a bonding dielectric layer 24 are sequentially formed on one side surface of the second substrate 21. The bonding dielectric layer 24 covers the side surface of the waveguide core 23 facing away from the second substrate 21 and the side surface of the waveguide core 23, such as... Figures 12A-12C As shown;

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

[0127] S209, bonding the piece of electro-optical material film 130 to the side surface of the bonding medium layer 24 away from the waveguide core 23 by using the micro transfer device 200, as shown in FIG. 2F; wherein the piece of electro-optical material film 130 corresponds to the waveguide core 23; the piece of electro-optical material film 130 has a slope structure on both sides along the length direction of the waveguide core 23; and the slope of the piece of electro-optical material film 130 is away from the waveguide core 23. Figure 13

[0128] S210, forming an electrode 26 on the side surface of the piece of electro-optical material film 130 away from the bonding medium layer 24, and the electrode 26 is located at the corresponding position on both sides of the waveguide core 23, as shown in FIG. 2G. Figure 14

[0129] S211, forming an upper cladding layer 27 on the side surface of the bonding medium layer 24 away from the lower cladding layer 22, and the upper cladding layer 27 covers the bonding medium layer 24, the piece of electro-optical material film 130 and the electrode 26, as shown in FIG. 2H. Figures 15A-15D

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

[0131] The preparation method of the electro-optical modulation device provided in the embodiment can heterogeneously integrate the piece of electro-optical material film with the slope structure to the corresponding position of the waveguide core through the micro transfer process, so that the slope of the piece of electro-optical material film is 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] Embodiment 3

[0133] Reference Figure 22 The embodiment provides another specific flow of a preparation method of an electro-optical modulation device 400, including steps S301-S309.

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

[0135] ​​​S305, cutting the electro-optical material film wafer along the strip-shaped groove and the direction perpendicular to the strip-shaped groove respectively to obtain a plurality of electro-optical material film units, as shown in Figures 16A-16C FIG. 3B; the electro-optical material film unit sequentially comprises the partial electro-optical material film 13 with the slope structure and the corresponding buried layer 12 and the first substrate 11, as shown in Figure 17 FIG. 3C;

[0136] S306, the same as step S208, providing the second substrate 21, and sequentially forming the lower cladding layer 22, the waveguide core 23 and the bonding medium layer 24 on one side surface of the second substrate 21, the bonding medium layer 24 covering the side surface of the waveguide core 23 away from the second substrate 21, as shown in Figures 12A-12C FIG. 4B;

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

[0138] S307, bonding the electro-optical material film unit to the side surface of the bonding medium layer 24 away from the waveguide core 23, as shown in Figure 18 FIG. 5B; 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 the slope structure on both sides along the length direction of the waveguide core 23; and the slope surface of the electro-optical material film 13 faces the waveguide core 23.

[0139] S308, removing the first substrate 11, as shown in Figure 19 FIG. 6B.

[0140] S309, forming the electrode 26 on the side surface of the buried layer 12 away from the electro-optical material film 13, as shown in Figures 20A-20D FIG. 7B.

[0141] The preparation method of the electro-optical modulation device provided by the embodiment can avoid etching process on the lithium niobate film, and improve the utilization rate of the electro-optical material film by cutting a plurality of electro-optical material film units from the structure after removing the patterned blocking layer, and bonding the electro-optical material film unit to the corresponding position of the waveguide core.

[0142] Obviously, the above embodiments are merely example for clearly illustrating but not limitation to the embodiments. Based on the above description, other different forms of changes or variations can be made by those skilled in the art. Here, all the embodiments need not and can not be enumerated. The obvious changes or variations derived from the above description are still within the protection scope of the present application.

Claims

1. A method for fabricating an electro-optic modulation device, characterized in that, include: An electro-optic material thin film wafer is provided, wherein the electro-optic material thin film wafer comprises, in sequence, a first substrate, a buried layer and an electro-optic material thin film; A barrier layer is formed on the side of the electro-optic material film opposite to the buried layer, and the barrier layer is etched to form a patterned barrier layer. The opening area of ​​the patterned barrier layer exposes multiple rows of the electro-optic material film. The exposed multiple rows of electro-optic material films are ground along the opening area using a grinding wheel until the buried layer is exposed, forming a strip-shaped groove with a sloping structure on both sides; The strip-shaped groove penetrates the electro-optic material film and extends into the buried layer in the depth direction; Remove the graphical blocking layer; Several electro-optic material thin film units are cut from the structure after the patterned blocking layer is removed; The electro-optic material thin film unit includes a portion of the electro-optic material thin film defined by two adjacent strip grooves; A second substrate is provided, and a lower cladding layer, a waveguide core, and a bonding dielectric layer are sequentially formed on one side surface of the second substrate. The bonding dielectric layer covers the side surface of the waveguide core facing away from the second substrate and the side surface of the waveguide core. The electro-optic material thin film unit is bonded to the bonding dielectric layer on the side surface facing away from the waveguide core; wherein the electro-optic material thin film unit corresponds to the waveguide core; the slope structure is located on both sides of the waveguide core along its length. An electrode is formed on the surface of the electro-optic material thin film unit facing away from the bonding dielectric layer, and the electrode is located at corresponding positions on both sides of the waveguide core.

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

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

1.

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

5. The method for fabricating the electro-optic modulation device according to claim 4, characterized in that, The obtuse angle is between 165° and 179.8°. The width of the opening area is greater than or equal to 2×L×(H+h) / h, where L is the projected length of the slope structure on the horizontal plane, h is the thickness of the electro-optic material film, and H is the thickness of the barrier layer.

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

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

8. The method for fabricating the electro-optic modulation device according to claim 1, characterized in that, The electro-optic material thin film unit is a small electro-optic material thin film sheet with a slope structure; The step of cutting a plurality of electro-optic material thin film units from the structure after removing the patterned blocking layer includes: The remaining electro-optic material film after grinding with a grinding wheel is patterned to form multiple electro-optic material film pieces, each of which includes a first electro-optic material film piece and a second electro-optic material film piece; wherein, the non-sloping sides of the first electro-optic material film piece are connected to two adjacent second electro-optic material film pieces through tiny electro-optic material connection points. The buried layer beneath the electro-optic material film wafer is removed by wet etching; wherein the width of the first electro-optic material film wafer is smaller than the width of the two second electro-optic material film wafers connected to it, the first electro-optic material film wafer is suspended only by being connected to the two adjacent second electro-optic material film wafers through the electro-optic material connection point, while the two adjacent second electro-optic material film wafers 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 using a micro-transfer device, causing the electro-optic material film pieces to detach from the first substrate.

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

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

11. The method for fabricating the electro-optic modulation device according to claim 10, characterized in that, The step of bonding the electro-optic material thin film unit to the side surface of the bonding dielectric layer facing away from the waveguide core includes: The electro-optic material thin film unit is bonded to the bonding dielectric layer on the side of the waveguide core that is opposite to the waveguide core; wherein the electro-optic material thin film is in contact with and bonded to the bonding dielectric layer; the electro-optic material thin film corresponds to the waveguide core; the slope of the electro-optic material thin film faces the waveguide core. Remove the first substrate.

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

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