Electro-optical thin film wafer and preparation method thereof, and preparation method of heterogeneous integrated electro-optical modulator

Abstract

The present invention belongs to the field of semiconductors and relates to electro-optic modulator preparation technology. It discloses an electro-optic thin film wafer, a preparation method, and a heterogeneous integrated electro-optic modulator preparation method. The electro-optic thin film wafer includes a first substrate and an electro-optic thin film layer. The first substrate is provided with a plurality of protrusions, with gaps between adjacent protrusions; each protrusion is provided with a first bonding dielectric layer. The protrusion includes an etching layer with a removal rate greater than that of the first substrate and the first bonding dielectric layer, and the electro-optic thin film layer is bonded to the first bonding dielectric layer. The preparation method includes: slicing the prepared electro-optic thin film wafer and bonding it to an optical waveguide wafer; successively removing the remaining protrusions on the first substrate and the first bonding dielectric layer; and forming electrodes to obtain a heterogeneous integrated electro-optic modulator. The present invention can shorten the first substrate removal time, reduce costs, improve removal uniformity, reduce the impact of substrate residue on optical waveguide propagation loss, and reduce etching damage to the optical waveguide substrate.

Description

Technical Field

[0001] The present invention belongs to the field of semiconductors and relates to a technology for preparing an electro-optic modulator, in particular to an electro-optic thin film wafer and a preparation method thereof, and a method for preparing a heterogeneous integrated electro-optic modulator. Background Art

[0002] Modulators are key components of photonics platforms. For silicon nitride (Si3N4) and silicon (Si) photonics platforms, optical phase modulation can be achieved using thermo-optical and elasto-optical effects. However, these modulators suffer from limitations in modulation speed, power consumption, and efficiency. Electro-optic modulation is an alternative that can significantly increase the speed of optical phase modulation. Since silicon nitride and silicon materials themselves cannot achieve efficient electro-optic modulation, they must be integrated with materials that exhibit significant electro-optic effects. Electro-optic crystal materials such as lithium niobate (LiNbO3), lithium tantalate, and barium titanate are the most competitive materials for electro-optic modulation due to their strong Pockels effect, low optical loss, and wide optical transparency windows.

[0003] However, the significant difference in thermal expansion coefficients between electro-optic crystal materials such as lithium niobate and silicon creates etching difficulties and potential contamination risks. Therefore, improving the CMOS process compatibility of silicon nitride-lithium niobate electro-optic modulator fabrication processes has become a current research area. In existing electro-optic modulator designs, a thin-film lithium niobate wafer or die is typically bonded to a silicon nitride or silicon waveguide core during fabrication. The silicon substrate is then removed from the thin-film lithium niobate wafer to achieve heterogeneous integration of the lithium niobate and silicon nitride.

[0004] Currently, silicon substrates are typically removed by grinding and thinning the backside of the silicon substrate followed by dry or wet etching of the silicon. Because grinding, thinning, and etching are required to remove the entire silicon substrate, a longer process time and a larger amount of etching gas or etching liquid are required, reducing removal efficiency and increasing process costs. Furthermore, problems such as poor etching uniformity, increased optical waveguide propagation loss due to residual silicon substrate, and damage to the optical waveguide substrate are also prone to occur. Summary of the Invention

[0005] In order to solve the technical problems of low removal efficiency, high cost, poor removal uniformity and poor removal effect caused by removing the silicon substrate of electro-optical crystal materials (such as thin-film lithium niobate wafers) by grinding and dry / wet etching, such as increased optical waveguide propagation loss and damage to the optical waveguide substrate, the present invention discloses an electro-optical thin-film wafer, which includes a first substrate and an electro-optical thin-film layer.

[0006] Among them, a plurality of protrusions are provided on the first substrate, and there are gaps between adjacent protrusions; a first bonding dielectric layer is provided on each of the protrusions, and the protrusions include an etching layer, and the removal rate of the etching layer is greater than the removal rate of the first substrate and the first bonding dielectric layer, and the electro-optical thin film layer is bonded to the first bonding dielectric layer.

[0007] An embodiment of the present invention further provides a method for preparing an electro-optical thin film wafer, the method comprising the following steps:

[0008] Step 1: forming an etched surface on the surface or inside of a first substrate;

[0009] Step 2: forming a first bonding medium surface on the first substrate or the etched surface;

[0010] Step 3: performing patterning along the direction from the first bonding medium surface to the first substrate to obtain a plurality of protrusions, wherein the protrusions include an etching layer, and each protrusion is provided with a first bonding medium layer;

[0011] Step 4: forming an electro-optical thin film layer on the first bonding dielectric layer to obtain an electro-optical thin film wafer.

[0012] An embodiment of the present invention further provides a method for preparing a heterogeneous integrated electro-optical modulator, the method comprising the following steps:

[0013] S1, preparing the electro-optical thin film wafer, cutting the electro-optical thin film wafer to obtain electro-optical thin film wafer slices, each of the electro-optical thin film wafer slices comprising a plurality of protrusions;

[0014] S2, preparing an optical waveguide wafer;

[0015] S3, bonding the electro-optical thin film wafer slice to the optical waveguide wafer, so that the waveguide core of the optical waveguide wafer corresponds to the protrusion or the gap between two protrusions on the electro-optical thin film wafer slice;

[0016] S4, etching the protrusion to remove the first substrate of the electro-optical thin film wafer slice;

[0017] S5, removing the remaining protrusions on the first bonding dielectric layer of the electro-optical thin film wafer slice;

[0018] S6. Forming electrodes on the electro-optical thin film layer or the optical waveguide wafer and on both sides of the waveguide core of the optical waveguide wafer to obtain a heterogeneous integrated electro-optical modulator.

[0019] The electro-optical thin film wafer provided by the present invention has a protrusion with an etched layer (such as an ion implantation damage layer or sacrificial layer) disposed between the electro-optical thin film layer and the substrate. When using it to fabricate heterogeneous integrated electro-optical modulation devices, the electro-optical thin film wafer or the first substrate of a slice of the electro-optical thin film wafer can be quickly separated from the protrusion, thereby improving production efficiency and reducing costs. Compared with existing technologies, it has the following advantages:

[0020] 1. By introducing a protrusion of an ion-implanted damaged layer or sacrificial layer beneath the electro-optical thin film layer of the electro-optical thin film wafer, the substrate of the electro-optical thin film wafer can be separated from the electro-optical thin film layer at the damaged layer or sacrificial layer due to the faster removal rate of the damaged layer or sacrificial layer, without having to etch the entire substrate. This reduces process time and saves on etching solution and etching gas usage, helping to solve problems such as uneven substrate etching, increased propagation loss caused by substrate residue, and damage to the optical waveguide wafer.

[0021] 2. By designing the gaps between the protrusions, it is helpful for the etching liquid or solvent to contact the protrusions near the center of the electro-optical thin film wafer (or chip), thereby shortening the time for separating the electro-optical thin film wafer substrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0023] Figure 1 This is a schematic diagram of the first structure of the electro-optical thin film wafer disclosed in an embodiment of the present invention;

[0024] Figure 2 A schematic diagram of a second structure of the electro-optical thin film wafer disclosed in an embodiment of the present invention;

[0025] Figure 3 A third structural schematic diagram of the electro-optical thin film wafer disclosed in an embodiment of the present invention;

[0026] Figure 4 for Figure 1 A schematic diagram of forming a first bonding medium surface on a first substrate in an electro-optical thin film wafer is shown;

[0027] Figure 5 For Figure 4 Schematic diagram of the structure shown in after ion implantation;

[0028] Figure 6 For Figure 5 A top view of a first protrusion structure obtained by patterning the structure shown in FIG.

[0029] Figure 7 For Figure 5 A top view of a second protrusion structure obtained by patterning the structure shown in ;

[0030] Figure 8 for Figure 6 and Figure 7 Cross-section at AA;

[0031] Figure 9 A top view of an electro-optical thin film wafer with strip-shaped protrusions disclosed in an embodiment of the present invention;

[0032] Figure 10 A top view of an electro-optical thin film wafer with a cylindrical protrusion disclosed in an embodiment of the present invention;

[0033] Figure 11 A flowchart of a method for preparing a heterogeneous integrated electro-optical modulator disclosed in an embodiment of the present invention;

[0034] Figure 12 A top view of an electro-optical thin film layer chip formed by patterning the electro-optical thin film wafer of the present invention;

[0035] Figure 13 for Figure 12 shown Figure 1 Cross-sectional view of the electro-optical thin film wafer at AA;

[0036] Figure 14 For Figure 1 Schematic diagram of electro-optical thin film wafer slices obtained by cutting the electro-optical thin film wafer shown;

[0037] Figure 15 for Figure 12 shown Figure 2 Cross-sectional view of the electro-optical thin film wafer at AA;

[0038] Figure 16 For Figure 2 Schematic diagram of electro-optical thin film wafer slices obtained by cutting the electro-optical thin film wafer shown;

[0039] Figure 17 is a cross-sectional view of a first structure of an optical waveguide wafer in the present invention;

[0040] Figure 18 Schematic diagram of the groove on the lower cladding disclosed in the present invention;

[0041] Figure 19 is a top view of a second structure of an optical waveguide wafer without forming a second bonding dielectric layer in the present invention;

[0042] Figure 20 for Figure 19A cross-sectional view at AA after forming a second bonding dielectric layer in the structure shown;

[0043] Figure 21 for Figure 19 A cross-sectional view at BB after forming a second bonding dielectric layer in the structure shown;

[0044] Figure 22 is a top view of a third structure of an optical waveguide wafer without forming a second bonding dielectric layer in the present invention;

[0045] Figure 23 for Figure 22 A cross-sectional view at AA after forming a second bonding dielectric layer in the structure shown;

[0046] Figure 24 for Figure 22 A cross-sectional view at BB after forming a second bonding dielectric layer in the structure shown;

[0047] Figure 25 for Figure 22 A cross-sectional view at CC after forming a second bonding dielectric layer in the structure shown;

[0048] Figure 26 For the electro-optical thin film wafer slicing of the present invention and Figure 17 A schematic diagram of optical waveguide wafer bonding;

[0049] Figure 27 For the electro-optical thin film wafer slicing of the present invention and Figure 17 Another schematic diagram of optical waveguide wafer bonding;

[0050] Figure 28 Schematic diagram showing that only the first bonding dielectric layer and the electro-optical thin film layer remain after etching;

[0051] Figure 29 is a schematic diagram of a heterogeneous integrated electro-optical modulator of the present invention;

[0052] Among them, 1. first substrate; 2. protrusion; 3. gap; 4. first bonding dielectric layer; 5. electro-optical thin film layer; 41. first bonding dielectric surface; 2021. damaged surface; 201. first substrate protrusion layer; 202. etching layer; 203. first substrate thin film layer; 6. second substrate; 7. lower cladding; 8. groove; 81. middle equal-width groove; 82. end tapered groove; 9. silicon-rich silicon nitride waveguide core; 10. middle layer; 11. second bonding dielectric layer; 12. first silicon nitride waveguide core; 13. second silicon nitride waveguide core; 14. waveguide core; 15. electrode. DETAILED DESCRIPTION

[0053] The embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0054] The following describes the embodiments of the present application through specific examples, and those skilled in the art can easily understand other advantages and effects of the present application from the contents disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The present application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that, in the absence of conflict, the following embodiments and the features of the embodiments can be combined with each other. Based on the embodiments in the present application, other embodiments obtained by those of ordinary skill in the art without making creative work are all within the scope of protection of the present application.

[0055] The embodiment of the present invention discloses an electro-optical thin film wafer, see Figure 1 、 Figure 2 and Figure 3 As shown, the electro-optical thin film wafer includes a first substrate 1 and an electro-optical thin film layer 5. The first substrate 1 is provided with a plurality of protrusions 2, with gaps 3 between adjacent protrusions 2. A first bonding dielectric layer 4 is provided on each protrusion 2. The protrusions 2 include an etching layer 202, the removal rate of which is greater than the removal rate of the first substrate 1 and the first bonding dielectric layer 4. The electro-optical thin film layer 5 is bonded to the first bonding dielectric layer 4.

[0056] The present invention forms an etching layer 202 in the first substrate 1 of the electro-optical thin film wafer and separates the first substrate 1 and the electro-optical thin film layer 5 by etching the etching layer 202, thereby shortening the removal time of the first substrate 1 on the electro-optical thin film wafer, reducing costs, improving the uniformity of substrate removal, reducing the influence of substrate residue on optical waveguide propagation loss, and reducing etching damage to the optical waveguide substrate.

[0057] Further, see Figure 6 and Figure 7 As shown, the protrusions 2 can be strip-shaped, column-shaped, or a combination of the two, and are distributed in an array on the first substrate 1. The gaps 3 between the protrusions 2 can be set to 1 to 10 μm, the width of the protrusions 2 can be set to 1 to 5 μm, and the height can be set to 0.5 to 5 μm.

[0058] Furthermore, the electro-optical thin film layer 5 can be made of an electro-optical crystal material such as lithium niobate, lithium tantalate, or barium titanate, and its thickness can be set to 100 to 500 nm. Furthermore, a protective film can be provided on the side of the electro-optical thin film layer 5 facing the first bonding dielectric layer 4. The material of the protective film is the same as that of the first bonding dielectric layer 4. The provision of the protective film can protect the electro-optical thin film layer 5 from being damaged by the etching solution during the preparation of the electro-optic modulator.

[0059] In one embodiment of the projection 2, see Figure 1 As shown, the protrusion 2 includes a first substrate protrusion layer 201, the etching layer 202 and a first substrate film layer 203 along the direction facing away from the first substrate 1. The first substrate film layer 203 is located between the first bonding dielectric layer 4 and the etching layer 202. The etching layer 202 is a damaged layer formed by ion implantation. The implanted ions are H + and / or He + , the injection energy is 50~1000keV, and the total injection dose is 5×10 15 cm -2 ~5×10 17 cm -2 , the material of the first bonding dielectric layer 4 is silicon dioxide or aluminum oxide.

[0060] In another embodiment of the projection 2, see Figure 2 and Figure 3 As shown, the etching layer 202 is a sacrificial layer formed by depositing amorphous silicon, silicon dioxide or metal on the surface of the first substrate 1, or a sacrificial layer formed by coating a temporary bonding adhesive on the surface of the first substrate 1. Figure 2 As shown, the sacrificial layer can be provided at a position where the protrusion 2 is formed on the first substrate 1, and the first substrate 1 is exposed in a gap 3 between two adjacent sacrificial layers. Figure 3 As shown, a material for forming a sacrificial layer can be applied to the entire surface of the first substrate 1, and then patterned to remove portions of the sacrificial layer to form protrusions 2. In this case, the first substrate 1 is not exposed in the gaps 3 between two adjacent protrusions 2, indicating that a sacrificial layer is present on the surface. The thickness of the sacrificial layer can be set to 0.5 to 5 μm. The material of the first bonding dielectric layer 4 can be any one of amorphous silicon, silicon dioxide, aluminum oxide, and bonding adhesive, and the thickness of the first bonding dielectric layer 4 can be set to 10 to 500 nm. The material of the first substrate 1 can be silicon, quartz, etc.

[0061] The embodiment of the present invention also provides a Figures 1 to 3 The preparation method of the electro-optical thin film wafer shown in the figure comprises the following steps:

[0062] Step 1: forming an etched surface on the surface or inside of a first substrate;

[0063] Step 2: forming a first bonding medium surface on the first substrate or the etched surface;

[0064] Step 3: performing patterning along the direction from the first bonding medium surface to the first substrate to obtain a plurality of protrusions, wherein the protrusions include an etching layer, and each protrusion is provided with a first bonding medium layer;

[0065] Step 4: forming an electro-optical thin film layer on the first bonding dielectric layer to obtain an electro-optical thin film wafer.

[0066] in, Figure 1 The method for preparing the electro-optical thin film wafer shown in specifically comprises the following steps:

[0067] Step 1.1, see Figure 4 As shown, a first bonding medium surface 41 is formed on the first substrate 1;

[0068] Step 1.2: perform ion implantation on the first substrate 1 below the first bonding medium surface 41 to form a Figure 5 The damaged surface 2021 shown is parallel to the first bonding medium surface 41;

[0069] Step 1.3, patterning is performed along the direction from the first bonding medium surface 41 to the first substrate 1 to obtain a plurality of protrusions 2, each of which is provided with a first bonding medium layer 4, wherein the protrusion 2 includes a first substrate protrusion layer 201, a damaged layer and a first substrate thin film layer 203 along the direction facing away from the first substrate 1, and the structure after patterning is as follows Figure 8 shown.

[0070] Step 1.4: forming an electro-optical thin film layer 5 on the first bonding dielectric layer 4 to obtain Figure 9 or Figure 10 The electro-optical thin film wafer shown.

[0071] It should be noted that, in the preparation of Figure 1 In the case of the electro-optical thin film wafer shown, the order of step 1 and step 2 can be changed, that is, the damaged surface 2021 can be formed in the first substrate 1 first, and then the first bonding medium surface 41 can be formed on the surface of the first substrate 1.

[0072] in, Figure 2 and Figure 3 The method for preparing the electro-optical thin film wafer shown in specifically comprises the following steps:

[0073] Step 2.1: depositing amorphous silicon, silicon dioxide or metal on the first substrate 1, or coating a temporary bonding adhesive to form a sacrificial layer;

[0074] Step 2.2, forming a first bonding medium surface 41 on the sacrificial layer;

[0075] Step 2.3: Perform patterning along the direction from the first bonding medium surface 41 to the first substrate 1 to obtain a plurality of protrusions 2. After the first bonding medium surface 41 is patterned, a first bonding medium layer 4 is formed on each protrusion 2.

[0076] Step 2.4, bonding the electro-optical thin film layer 5 on the first bonding dielectric layer 4 of the protruding portion 2, and obtaining a top view as shown in FIG. Figure 9 or Figure 10 As shown, the cross-sectional view is Figure 2 or Figure 3 The electro-optical thin film wafer shown.

[0077] The present invention also provides a method for preparing a heterogeneous integrated electro-optical modulator. Figure 11 As shown, the preparation method comprises the following steps:

[0078] S1, preparing the electro-optical thin film wafer, cutting the electro-optical thin film wafer to obtain electro-optical thin film wafer slices, each of the electro-optical thin film wafer slices comprising a plurality of protrusions 2;

[0079] S2, preparing an optical waveguide wafer;

[0080] S3, bonding the electro-optical thin film wafer slice to the optical waveguide wafer, so that the waveguide core 14 of the optical waveguide wafer corresponds to the protrusion 2 or the gap between two protrusions 2 on the electro-optical thin film wafer slice, and the structure after bonding is as follows Figure 26 and Figure 27 As shown;

[0081] S4, etching the protrusion 2 to remove the first substrate 1 of the electro-optical thin film wafer slice;

[0082] S5, removing the remaining protrusion 2 on the first bonding medium layer 4 of the electro-optical thin film wafer slice, and obtaining the following Figure 28 The structure shown;

[0083] S6, forming electrodes 15 on the electro-optical thin film layer 5 or the optical waveguide wafer and on both sides of the waveguide core 14 of the optical waveguide wafer to obtain a heterogeneous integrated electro-optical modulator. The structure of the heterogeneous integrated electro-optical modulator is as follows: Figure 29 shown.

[0084] Furthermore, in the above step S1, the electro-optical thin film wafer slices are obtained by cutting the electro-optical thin film wafer in the above embodiment. The structure of the electro-optical thin film wafer slices is as follows: Figures 12 to 16 As shown. During dicing, the first substrate 1 is cut along the gaps between the electro-optical thin film layer pieces to form electro-optical thin film wafer slices. The electro-optical thin film layer pieces correspond to multiple protrusions 2. To reduce the possibility of the electro-optical thin film layer pieces breaking during dicing, some (for strip-shaped or columnar protrusions) or all (for columnar protrusions) of the gaps between the electro-optical thin film layer pieces are completely within the gaps 3 between the protrusions 2.

[0085] In an alternative embodiment of preparing an optical waveguide wafer, see Figure 17 The structure shown is a traditional optical waveguide wafer, and its preparation process is as follows: a lower cladding layer 7 is formed on a second substrate 6, a waveguide core 14 is formed on the lower cladding layer 7, and a second bonding dielectric layer 11 is formed to cover the waveguide core 14 and the lower cladding layer 7. The second substrate 6 can be made of silicon; the lower cladding layer 7 can be made of silicon dioxide with a thickness of 2 to 20 μm. In a specific implementation, the second substrate 6 is a silicon substrate completely covered by a thermal oxide layer, which serves as the lower cladding layer 7. The waveguide core 14 can be made of a material with a greater refractive index than the lower cladding 7, such as a single layer or a stack of silicon nitride, silicon, or the like (e.g., silicon nitride / silicon dioxide / silicon nitride). The second bonding dielectric layer 11 can be made of silicon dioxide, aluminum oxide, bonding adhesive, or a combination thereof. The thickness of the second bonding dielectric layer 11 located above the waveguide core 14 is 10 to 300 nm.

[0086] In an optional embodiment of preparing an optical waveguide wafer, the structure of the optical waveguide wafer is as follows: Figures 18 to 25 As shown, the preparation process of the optical waveguide wafer includes:

[0087] S21, forming a lower cladding layer 7 on a second substrate 6, forming at least two middle equal-width grooves 81 on the lower cladding layer 7, and forming end tapered grooves 82 with tapered widths at both ends of each middle equal-width groove 81 to obtain a groove 8;

[0088] S22, forming a first silicon nitride layer and a silicon-rich silicon nitride layer in sequence on the lower cladding layer 7, and removing a portion of the silicon-rich silicon nitride layer outside the groove 8 by chemical mechanical polishing to form a silicon-rich silicon nitride waveguide core 9;

[0089] S23, sequentially covering the first silicon nitride layer and the silicon-rich silicon nitride waveguide core 9 with an intermediate layer 10 and a second silicon nitride layer, and performing patterning to obtain a silicon nitride waveguide core;

[0090] S24 , covering the lower cladding layer 7 and the silicon nitride waveguide core with a second bonding medium layer 11 to obtain an optical waveguide wafer.

[0091] In an optional embodiment of the above step S22, forming a first silicon nitride layer and a silicon-rich silicon nitride layer in sequence on the lower cladding layer 7 includes:

[0092] S2211, forming a first silicon nitride layer on the bottom wall and side walls of the groove 8 and the lower cladding layer 7 located outside the groove 8;

[0093] S2212. Form a silicon-rich silicon nitride layer on the first silicon nitride layer, wherein an upper surface of the silicon-rich silicon nitride layer located in the groove 8 is higher than an upper surface of the first silicon nitride layer located outside the groove 8.

[0094] In an optional embodiment of the above step S23, as Figures 19 to 21 As shown, the intermediate layer 10 and the second silicon nitride layer are sequentially covered on the first silicon nitride layer and the silicon-rich silicon nitride waveguide core 9, and a patterning process is performed to obtain a silicon nitride waveguide core, including:

[0095] S2301, covering the first silicon nitride layer and the silicon-rich silicon nitride waveguide core 9 with an intermediate layer 10, and covering the intermediate layer 10 with a second silicon nitride layer;

[0096] S2302, synchronously patterning the second silicon nitride layer, the intermediate layer 10, and the first silicon nitride layer to obtain the silicon nitride waveguide core whose projection at least completely covers the two silicon-rich silicon nitride waveguide cores 9, wherein the silicon nitride waveguide core includes an integrated silicon nitride waveguide core outside the groove and a silicon nitride waveguide core inside the groove;

[0097] S2303 , each position of the silicon nitride waveguide core outside the groove and the silicon nitride waveguide core inside the groove includes a stacked first silicon nitride waveguide core 12 , the intermediate layer 10 , and a second silicon nitride waveguide core 13 .

[0098] In another optional embodiment of the above step S23, as Figures 22 to 25 As shown, the intermediate layer 10 and the second silicon nitride layer are sequentially covered on the first silicon nitride layer and the silicon-rich silicon nitride waveguide core 9, and a patterning process is performed to obtain a silicon nitride waveguide core, including:

[0099] S2311, covering the first silicon nitride layer and the silicon-rich silicon nitride waveguide core 9 with an intermediate layer 10, and covering the intermediate layer 10 with a second silicon nitride layer;

[0100] S2312, patterning the second silicon nitride layer to obtain a second silicon nitride waveguide core 13, wherein the second silicon nitride waveguide core 13 includes a second sub-silicon nitride waveguide core with equal width in the middle portion and tapered at both ends, located between the two grooves 8, wherein the tapered portions at both ends of each second sub-silicon nitride waveguide core are inverted and superimposed on the tapered portion of the silicon-rich silicon nitride waveguide core 9;

[0101] S2313 , patterning the intermediate layer 10 and the first silicon nitride layer to obtain a first silicon nitride waveguide core 12 , and using the first silicon nitride waveguide core 12 and the second silicon nitride waveguide core 13 as silicon nitride waveguide cores.

[0102] Furthermore, in the above step S4, the product can be placed in an etching solution, and a wet etching method can be used to quickly dissolve the etching layer 202 of the protrusion 2 to remove the first substrate 1 on the electro-optical thin film wafer slice. After the first substrate 1 is separated from the product, it is taken out of the etching solution to avoid the etching solution dissolving the first substrate 1 and consuming the etching solution.

[0103] More specifically, during the first wet etching step S4, because the damaged layer / sacrificial layer has a higher etching rate, the first substrate 1 can be separated from the electro-optical thin film layer 5 at the damaged layer before the first substrate 1 and the second bonding dielectric layer 11 are severely etched. The duration of the first wet etching step can be set to 5 to 50 minutes. During the etching, the gaps 3 between the protrusions 2 facilitate contact between the etching solution and the damaged layer / sacrificial layer near the center of the first substrate 1, thereby shortening the time required to separate the first substrate 1.

[0104] Furthermore, in the above step S5, the removal method is selected based on whether the etching layer 202 is a damaged layer or a sacrificial layer. When the etching layer 202 is a damaged layer, the above-mentioned etching solution or dry etching can be used to perform a second etching to remove the protrusion 2 remaining on the first bonding dielectric layer 4. When the etching layer 202 is a sacrificial layer, a wet etching method can be used to remove the protrusion 2 remaining on the first bonding dielectric layer 4. The second etching time can be 2 to 20 minutes. The etching solution can be any one of KOH solution, TMAH solution, acid solution and temporary bonding agent, and the dry etching can be XeF2 vapor phase etching.

[0105] More specifically, when the etched layer 202 is silicon or amorphous silicon, a wet etchant such as KOH or TMAH solution can be used to remove the sacrificial layer. For example, the etching conditions can be a 10-40 wt% TMAH solution, a temperature of 60-90°C, and a time of 2-50 minutes. When the sacrificial layer is a metal such as Al or Cu, an acid solution wet etchant can be used for removal. When the sacrificial layer is a temporary bonding adhesive, a solvent can be used to dissolve the bonding adhesive for removal.

[0106] Furthermore, in order to prevent the etching solution from etching from the back side of the first substrate 1 and the second substrate 6, thereby saving the amount of etching solution used and reducing costs, the above preparation method further includes:

[0107] A thermal oxide layer is formed on a side of the first substrate 1 facing away from the electro-optical thin film layer 5 , and a thermal oxide layer is formed on a side of the second substrate 6 of the optical waveguide wafer facing away from the lower cladding layer 7 .

[0108] Furthermore, during the specific implementation of step S6, the electrode material may be Au, Al, Cu, etc., the electrode spacing may be 4 to 10 um, and the electrode thickness may be 0.5 to 2 um.

[0109] The electro-optical thin film wafer provided by the present invention has a protrusion with an ion-implanted damage layer or sacrificial layer disposed between the electro-optical thin film layer and the substrate. When using it to fabricate heterogeneous integrated electro-optical modulation devices, the electro-optical thin film wafer or the first substrate from which the electro-optical thin film wafer is sliced ​​can be quickly separated from the protrusion, thereby improving manufacturing efficiency and reducing costs. Compared with existing technologies, this invention has the following advantages:

[0110] 1. By introducing a protrusion of an ion-implanted damaged layer or sacrificial layer beneath the electro-optical thin film layer of the electro-optical thin film wafer, the substrate of the electro-optical thin film wafer can be separated from the electro-optical thin film layer at the damaged layer or sacrificial layer due to the faster removal rate of the damaged layer or sacrificial layer, without having to etch the entire substrate. This requires less process time and saves on the use of etching liquid and etching gas, helping to solve problems such as uneven substrate etching, increased propagation loss caused by substrate residue, and damage to the optical waveguide wafer.

[0111] 2. By designing the gaps between the protrusions, it is helpful for the etching liquid or solvent to contact the protrusions near the center of the electro-optical thin film wafer (or chip), thereby shortening the time for separating the electro-optical thin film wafer substrate.

[0112] Obviously, those skilled in the art will understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations are possible in the embodiments of the present invention. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. An electro-optical thin film wafer, characterized in that: include: A first substrate (1), wherein a plurality of protrusions (2) are provided on the first substrate (1), gaps (3) are provided between adjacent protrusions (2), the protrusions (2) are strip-shaped and / or column-shaped, and the protrusions (2) are distributed on the first substrate (1) in an array; a first bonding dielectric layer (4) is provided on each of the protrusions (2), the protrusions (2) include an etching layer (202), and a removal rate of the etching layer (202) is greater than a removal rate of the first substrate (1) and the first bonding dielectric layer (4); An electro-optical thin film layer (5), the electro-optical thin film layer (5) is bonded to the first bonding medium layer (4).

2. The electro-optical thin film wafer according to claim 1, characterized in that: A protective film is also provided on the side of the electro-optical film layer (5) facing the first bonding medium layer (4), and the material of the protective film is the same as that of the first bonding medium layer (4).

3. The electro-optical thin film wafer according to claim 1 or 2, characterized in that: The protrusion (2) comprises a first substrate protrusion layer (201), the etching layer (202) and a first substrate film layer (203) along a direction facing away from the first substrate (1); the first substrate film layer (203) is located between the first bonding medium layer (4) and the etching layer (202); and the etching layer (202) is a damaged layer formed by ion implantation.

4. The electro-optical thin film wafer according to claim 1 or 2, characterized in that: The etching layer (202) is a sacrificial layer formed by depositing amorphous silicon, silicon dioxide or metal on the surface of the first substrate (1), or a sacrificial layer formed by coating a temporary bonding adhesive on the surface of the first substrate (1).

5. A method for preparing an electro-optical thin film wafer according to any one of claims 1 to 4, characterized in that: include: forming an etched surface on the surface or inside the first substrate (1); forming a first bonding medium surface (41) on the first substrate (1) or the etched surface; A plurality of protrusions (2) are obtained by patterning along the direction from the first bonding medium surface (41) to the first substrate (1), wherein the protrusions (2) include an etching layer (202), and each protrusion (2) is provided with a first bonding medium layer (4); An electro-optical thin film layer (5) is formed on the first bonding medium layer (4) to obtain an electro-optical thin film wafer.

6. A method for preparing a heterogeneous integrated electro-optical modulator, characterized in that: The preparation method comprises: Prepare an electro-optical thin film wafer according to any one of claims 1 to 4, cut the electro-optical thin film wafer to obtain electro-optical thin film wafer slices, each of the electro-optical thin film wafer slices comprising a plurality of protrusions (2); preparing optical waveguide wafers; Bonding the electro-optical thin film wafer slice to the optical waveguide wafer so that the waveguide core (14) of the optical waveguide wafer corresponds to the protrusion (2) or the gap between the two protrusions (2) on the electro-optical thin film wafer slice; Etching the protruding portion (2) to remove the first substrate (1) of the electro-optical thin film wafer slice; Removing the remaining protrusion (2) on the first bonding dielectric layer (4) of the electro-optical thin film wafer slice; Electrodes (15) are formed on the electro-optical thin film layer (5) or the optical waveguide wafer and located on both sides of the waveguide core (14) of the optical waveguide wafer to obtain a heterogeneous integrated electro-optical modulator.

7. The method for preparing a heterogeneous integrated electro-optical modulator according to claim 6, wherein: Prepare optical waveguide wafers, including: forming a lower cladding layer (7) on a second substrate (6), forming at least two middle equal-width grooves (81) on the lower cladding layer (7), and forming end tapered grooves (82) with tapered widths at both ends of each middle equal-width groove (81) to obtain a groove (8); forming a first silicon nitride layer and a silicon-rich silicon nitride layer in sequence on the lower cladding layer (7), and removing a portion of the silicon-rich silicon nitride layer outside the groove (8) by chemical mechanical polishing to form a silicon-rich silicon nitride waveguide core (9); Sequentially covering the first silicon nitride layer and the silicon-rich silicon nitride waveguide core (9) with an intermediate layer (10) and a second silicon nitride layer, and performing a patterning process to obtain a silicon nitride waveguide core; A second bonding medium layer (11) is covered on the lower cladding layer (7) and the silicon nitride waveguide core to obtain an optical waveguide wafer.

8. The method for preparing a heterogeneous integrated electro-optical modulator according to claim 7, wherein: A first silicon nitride layer and a silicon-rich silicon nitride layer are sequentially formed on the lower cladding layer (7), comprising: forming a first silicon nitride layer on the bottom wall and side walls of the groove (8) and the lower cladding layer (7) located outside the groove (8); A silicon-rich silicon nitride layer is formed on the first silicon nitride layer, wherein the upper surface of the silicon-rich silicon nitride layer located in the groove (8) is higher than the upper surface of the first silicon nitride layer located outside the groove (8).

9. The method for preparing a heterogeneous integrated electro-optical modulator according to claim 7 or 8, characterized in that: An intermediate layer (10) and a second silicon nitride layer are sequentially covered on the first silicon nitride layer and the silicon-rich silicon nitride waveguide core (9), and a patterning process is performed to obtain a silicon nitride waveguide core, comprising: An intermediate layer (10) is covered on the first silicon nitride layer and the silicon-rich silicon nitride waveguide core (9), and a second silicon nitride layer is covered on the intermediate layer (10); The second silicon nitride layer is patterned to obtain a second silicon nitride waveguide core (13), wherein the second silicon nitride waveguide core (13) comprises a second sub-silicon nitride waveguide core with equal width in the middle and tapered at both ends, located between the two grooves (8), wherein the tapered portions at both ends of each second sub-silicon nitride waveguide core and the tapered portion of the silicon-rich silicon nitride waveguide core (9) are inverted and superimposed on each other; The intermediate layer (10) and the first silicon nitride layer are patterned to obtain a first silicon nitride waveguide core (12), and the first silicon nitride waveguide core (12) and the second silicon nitride waveguide core (13) are used as silicon nitride waveguide cores.

10. The method for preparing a heterogeneous integrated electro-optical modulator according to claim 6, wherein: The preparation method further comprises: forming a thermal oxide layer on a side of the first substrate (1) facing away from the electro-optical thin film layer (5); A thermal oxide layer is formed on a side of the second substrate (6) of the optical waveguide wafer that is away from the lower cladding layer (7).

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