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

Abstract

The invention belongs to the field of semiconductors, relates to an electro-optical modulator preparation technology, and discloses an electro-optical film wafer, a preparation method and a preparation method of a heterogeneous integrated electro-optical modulator. The electro-optical thin film wafer comprises a first substrate and an electro-optical thin film layer, a plurality of protruding parts are arranged on the first substrate, and gaps are formed between the adjacent protruding parts; and a first bonding dielectric layer is arranged on each protruding part. The protruding part comprises an etching layer of which the removal rate is greater than that of the first substrate and the first bonding dielectric layer, and the electro-optical thin film layer is in bonding connection with the first bonding dielectric layer. The preparation method comprises the following steps: slicing a prepared electro-optical thin film wafer and bonding the sliced electro-optical thin film wafer on an optical waveguide wafer; successively removing the residual protruding parts on the first substrate and the first bonding dielectric layer; and forming an electrode to obtain the heterogeneous integrated electro-optical modulator. The method can shorten the removal time of the first substrate, reduce the cost, improve the removal uniformity, reduce the influence of substrate residues on the propagation loss of the optical waveguide, and reduce the etching damage of the optical waveguide substrate.

Description

Technical Field

[0001] The invention belongs to the field of semiconductors and relates to a technology for preparing an electro-optic modulator, and 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 important components of photonic platforms. For silicon nitride (Si3N4) and silicon (Si) photonic platforms, thermo-optical effects, photoelastic effects, etc. can be used to achieve optical phase modulation. These modulators have deficiencies in modulation speed and / or power consumption and / or efficiency. Electro-optic modulation is an alternative that can greatly increase the speed of optical phase modulation. Since silicon nitride and silicon materials themselves cannot achieve efficient electro-optical modulation, they must be integrated with materials with significant electro-optical effects. Electro-optical crystal materials such as lithium niobate (LiNbO3), lithium tantalate, and barium titanate are the most competitive materials in electro-optical modulation because of their strong Pockels effect, low optical loss, and wide optical transparency window.

[0003] However, the thermal expansion coefficients of electro-optic crystal materials such as lithium niobate and silicon are quite different, and there are difficulties in etching and potential contamination risks. Therefore, how to improve the CMOS process compatibility of the silicon nitride-lithium niobate electro-optical modulation device manufacturing process has become one of the current research directions. In the existing design of electro-optic modulators, during preparation, a thin-film lithium niobate wafer or a small piece of lithium niobate film / buried oxide layer / silicon substrate is usually bonded on top of a silicon nitride or silicon waveguide core, and then the silicon substrate of the thin-film lithium niobate wafer is removed to achieve heterogeneous integration of lithium niobate and silicon nitride.

[0004] At present, the silicon substrate is usually removed by grinding and thinning the back of the silicon substrate and dry or wet etching of silicon. Since grinding, thinning and etching are required to remove the entire silicon substrate, a longer process time and more etching gas or etching liquid are required, which reduces the removal efficiency and increases the process cost. At the same time, it is also prone to problems such as poor etching uniformity, increased optical waveguide propagation loss due to residual silicon substrate, and damage to the optical waveguide substrate. 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, 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 medium 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 medium layer, and the electro-optical thin film layer is bonded to the first bonding medium layer.

[0007] The 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 etching surface on the surface or inside of the 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 the protrusions, wherein the protrusions include an etching layer, and each of the protrusions is provided with a first bonding medium layer;

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

[0012] The embodiment of the present invention further provides a method for preparing a heterogeneous integrated electro-optic 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 protruding portion to remove the first substrate of the electro-optical thin film wafer slice;

[0017] S5, removing the protrusions remaining on the first bonding medium 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-optic thin film wafer provided by the present invention has a protruding portion with an etching layer (such as an ion implantation damage layer or a sacrificial layer) between the electro-optic thin film layer and the substrate. When using it to make a heterogeneous integrated electro-optic modulation device, the electro-optic thin film wafer or the first substrate of the electro-optic thin film wafer slice can be quickly separated from the protruding portion, thereby improving the preparation efficiency and reducing the cost. Compared with the prior art, it has the following advantages:

[0020] 1. By introducing a protruding portion of an ion-implanted damaged layer or sacrificial layer under 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, without etching the entire substrate, because the damaged layer or sacrificial layer has a faster removal rate. Therefore, less process time is required, and the amount of etching liquid and etching gas used is saved, which helps to solve the problems of uneven substrate etching, increased propagation loss caused by substrate residue, and damage to optical waveguide wafers;

[0021] 2. By designing the gap between the protrusions, it is helpful for the etching solution or solvent to contact the protrusions near the center of the electro-optical thin film wafer (or chip), thereby shortening the separation time of 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 drawings required for use in the embodiments will be briefly introduced below. 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 paying creative work.

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

[0024] Figure 2 A second structural schematic diagram 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 operation;

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

[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-sectional view at AA in the middle;

[0031] Fig. 9 A top view of an electro-optical thin film wafer with a strip-shaped protrusion according to an embodiment of the present invention;

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

[0033] Fig.11 It is a flow chart of a method for preparing a heterogeneous integrated electro-optic modulator disclosed in an embodiment of the present invention;

[0034] Fig.12 A top view of a small electro-optical thin film layer formed by patterning the electro-optical thin film wafer of the present invention;

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

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

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

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

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

[0040] Fig.18 It is a schematic diagram of the groove on the lower cladding disclosed in the present invention;

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

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

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

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

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

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

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

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

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

[0050] Fig.28 It is a schematic diagram that only the first bonding medium layer and the electro-optical thin film layer are retained after etching;

[0051] Fig.29 is a schematic diagram of a heterogeneous integrated electro-optic modulator of the present invention;

[0052] Among them, 1. first substrate; 2. protrusion; 3. gap; 4. first bonding medium layer; 5. electro-optical thin film layer; 41. first bonding medium 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 medium 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 implementation methods of the present application through specific 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 implementation methods, and the various 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 the following embodiments and the features of the embodiments can be combined with each other without conflict. Based on the embodiments in the present application, other embodiments obtained by ordinary technicians in the field 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-optic thin film wafer includes a first substrate 1 and an electro-optic thin film layer 5. A plurality of protrusions 2 are provided on the first substrate 1, and gaps 3 are provided between adjacent protrusions 2; a first bonding medium layer 4 is provided on each protrusion 2, and the protrusion 2 includes an etching layer 202, and the removal rate of the etching layer 202 is greater than the removal rate of the first substrate 1 and the first bonding medium layer 4, and the electro-optic thin film layer 5 is bonded to the first bonding medium 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, so as to shorten the removal time of the first substrate 1 on the electro-optical thin film wafer, reduce the cost, improve the uniformity of substrate removal, reduce the influence of substrate residue on the propagation loss of the optical waveguide, and reduce the etching damage of the optical waveguide substrate.

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

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

[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, and the first substrate film layer 203 is located between the first bonding medium layer 4 and the etching layer 202. The etching layer 202 is a damaged layer formed by ion implantation, and the implanted ions are H + and / or He + The implantation energy is 50-1000 keV, and the total implantation dose is 5×10 15 cm -2 ~5×10 17 cm -2 , the material of the first bonding medium 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 arranged at a position where the protrusion 2 is formed on the first substrate 1, and the first substrate 1 is exposed in the gap 3 between two adjacent sacrificial layers. Figure 3 As shown, the raw material for forming a sacrificial layer can also be arranged on the entire surface of the first substrate 1, and then a graphic process is performed to remove part of the sacrificial layer to form a protrusion 2. At this time, the first substrate 1 is not exposed in the gap 3 between two adjacent protrusions 2, that is, there is a sacrificial layer on the surface. The thickness of the sacrificial layer can be set to 0.5 to 5um. The material of the first bonding medium layer 4 is any one of amorphous silicon, silicon dioxide, aluminum oxide and bonding glue, and the thickness of the first bonding medium layer 4 can be set to 10 to 500nm. The material of the first substrate 1 can be selected from 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 etching surface on the surface or inside of the 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 the protrusions, wherein the protrusions include an etching layer, and each of the protrusions is provided with a first bonding medium layer;

[0065] Step 4: forming an electro-optical thin film layer on the first bonding medium 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, ion implantation is performed 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, a plurality of protrusions 2 are obtained by patterning along the direction from the first bonding medium surface 41 to the first substrate 1, 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 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 medium layer 4 to obtain Fig. 9 or Fig.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 in FIG. 1 , 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 medium layer 4 of the protruding portion 2, and obtaining a top view as shown in FIG. Fig. 9 or Fig.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-optic modulator. Fig.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 the two protrusions 2 on the electro-optical thin film wafer slice, and the structure after bonding is as follows Fig.26 and Fig. 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 protrusion 2 remaining on the first bonding medium layer 4 of the electro-optical thin film wafer slice, and obtaining the following Fig.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: Fig.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, and the structure of the electro-optical thin film wafer slices is as follows: Figures 12 to 16 As shown. When cutting, the first substrate 1 is cut along the gaps of the electro-optical thin film layer pieces to form electro-optical thin film wafer slices. The electro-optical thin film layer pieces correspond to a plurality of protrusions 2. When cutting, in order to reduce the possibility of the electro-optical thin film layer pieces breaking during the process of dividing the first substrate into pieces, part (for strip-shaped protrusions or columnar protrusions) or all (for columnar protrusions) of the gaps of the electro-optical thin film layer pieces are completely located within the gap 3 of the protrusion 2.

[0085] In an alternative embodiment of preparing an optical waveguide wafer, see Fig.17 The structure shown is a traditional optical waveguide wafer, and its preparation process is as follows: a lower cladding 7 is formed on the second substrate 6, a waveguide core 14 is formed on the lower cladding 7, and a second bonding medium layer 11 is formed to cover the waveguide core 14 and the lower cladding 7. Among them, the material of the second substrate 6 can be silicon; the material of the lower cladding 7 can be silicon dioxide, with a thickness of 2 to 20 um. In a specific implementation, the second substrate 6 is a silicon substrate completely covered by a thermal oxide layer, and the thermal oxide layer serves as the lower cladding 7; the material of the waveguide core 14 can be a material with a refractive index greater than that of the lower cladding 7, such as a single layer or a stacked layer of silicon nitride, silicon, etc. (for example, silicon nitride / silicon dioxide / silicon nitride); the second bonding medium layer 11 can be silicon dioxide, aluminum oxide, bonding glue or a combination thereof, and the thickness of the second bonding medium 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 shown in 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 of the middle equal-width grooves 81 to obtain a groove 8;

[0088] S22, sequentially forming a first silicon nitride layer and a silicon-rich silicon nitride layer 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 intermediate layer 10 and the second silicon nitride layer on the first silicon nitride layer and the silicon-rich silicon nitride waveguide core 9, 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 comprises:

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

[0093] S2212, forming 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, Figure 22 to Figure 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 comprises 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 of the second sub-silicon nitride waveguide cores are invertedly 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 prevent the etching solution from dissolving the first substrate 1 and consuming the etching solution.

[0103] More specifically, during the first wet etching of step S4, since 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 from the damaged layer before the first substrate 1 and the second bonding medium layer 11 are severely etched, and the time of the first wet etching can be set to 5 to 50 minutes. During etching, the gap 3 between the protrusions 2 helps the etching solution to contact the damaged layer / sacrificial layer near the center of the first substrate 1, so as to shorten the time required for the first substrate 1 to be separated.

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

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

[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 usage of the etching solution and reducing the cost, 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, in the specific implementation of step S6, the electrode material may be Au, Al, Cu, etc., the electrode spacing is 4 to 10 um, and the electrode thickness is 0.5 to 2 um.

[0109] The electro-optic thin film wafer provided by the present invention has a protruding portion with an ion implantation damage layer or a sacrificial layer between the electro-optic thin film layer and the substrate. When using it to make a heterogeneous integrated electro-optic modulation device, the electro-optic thin film wafer or the first substrate of the electro-optic thin film wafer slice can be quickly separated from the protruding portion, thereby improving the preparation efficiency and reducing the cost. Compared with the prior art, it has the following advantages:

[0110] 1. By introducing a protruding portion of an ion-implanted damaged layer or sacrificial layer under 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 from the damaged layer or sacrificial layer, without etching the entire substrate, because the damaged layer or sacrificial layer has a faster removal rate. Therefore, less process time is required, and the amount of etching liquid and etching gas used is saved, which helps to solve the problems of uneven substrate etching, increased propagation loss caused by substrate residue, and damage to optical waveguide wafers;

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

[0112] Obviously, those skilled in the art should understand that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the embodiments of the present invention may have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope 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), and gaps (3) are provided between adjacent protrusions (2); a first bonding medium layer (4) is provided on each of the protrusions (2), and 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 medium 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: The protrusions (2) are strip-shaped and / or column-shaped, and the protrusions (2) are distributed on the first substrate (1) in an array.

3. 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).

4. The electro-optical thin film wafer according to any one of claims 1 to 3, characterized in that: The protruding portion (2) comprises a first substrate protruding layer (201), the etching layer (202) and a first substrate thin film layer (203) along a direction facing away from the first substrate (1); the first substrate thin 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.

5. The electro-optical thin film wafer according to any one of claims 1 to 3, 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).

6. A method for preparing an electro-optical thin film wafer according to any one of claims 1 to 5, characterized in that: include: forming an etched surface on the surface or inside of 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.

7. A method for preparing a heterogeneous integrated electro-optic modulator, characterized in that: The preparation method comprises: Prepare an electro-optical thin film wafer as claimed in any one of claims 1 to 5, 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 onto 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; Etching the protruding portion (2) to remove the first substrate (1) of the electro-optical thin film wafer slice; Removing the protruding portion (2) remaining on the first bonding medium 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.

8. The method for preparing a heterogeneous integrated electro-optic modulator according to claim 7, characterized in that: Prepare optical waveguide wafers, including: A lower cladding layer (7) is formed on a second substrate (6), at least two middle equal-width grooves (81) are formed on the lower cladding layer (7), and end tapered grooves (82) with tapered widths are formed 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 located outside the groove (8) by chemical mechanical polishing to form a silicon-rich silicon nitride waveguide core (9); 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; 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.

9. The method for preparing a heterogeneous integrated electro-optic modulator according to claim 8, characterized in that: A first silicon nitride layer and a silicon-rich silicon nitride layer are sequentially formed on the lower cladding layer (7), comprising: A first silicon nitride layer is formed on the bottom wall and side wall 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 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).

10. The method for preparing a heterogeneous integrated electro-optic modulator according to any one of claims 8 to 10, 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 an 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 are invertedly superimposed on the tapered portion of the silicon-rich silicon nitride waveguide core (9); 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.

11. The method for preparing a heterogeneous integrated electro-optic modulator according to claim 7, characterized in that: 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).

Images