CN119846862A

CN119846862A - Electro-optic film wafer and preparation method thereof, and preparation method of heterogeneous integrated electro-optic modulator

Info

Publication number: CN119846862A
Application number: CN202510124220.3A
Authority: CN
Inventors: 刘敬伟; 李超; 李春龙; 周良; 蔡丰任; 张彦乐; 花晓强
Original assignee: Guoke Guangxin Jinxing Beijing Laboratory Technology Co ltd
Current assignee: Guoke Guangxin Jinxing Beijing Laboratory Technology Co ltd
Priority date: 2025-01-26
Filing date: 2025-01-26
Publication date: 2025-04-18

Abstract

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

Description

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

Technical Field

The invention belongs to the field of semiconductors, and relates to an electro-optical modulator preparation technology, in particular to an electro-optical film wafer and a preparation method thereof and a heterogeneous integrated electro-optical modulator preparation method.

Background

Modulators are important elements of photonics platforms for which thermal-optical effects, elasto-optical effects, etc. can be utilized to achieve optical phase modulation, which have disadvantages in terms of modulation speed and/or power consumption and/or efficiency. The electro-optic modulation is an alternative scheme, which can greatly improve the speed of optical phase modulation, and because silicon nitride and silicon materials cannot realize high-efficiency electro-optic modulation, the electro-optic modulation must be integrated with materials with obvious electro-optic effect, and electro-optic crystal materials such as lithium niobate (LiNbO ₃), lithium tantalate, barium titanate and the like are materials with the highest competitiveness in the electro-optic modulation because of strong Pockels effect, lower optical loss and wide optical transparent window.

However, the difference of thermal expansion coefficients between the electro-optic crystal material such as lithium niobate and silicon is relatively large, and there are etching difficulties and potential pollution risks, so how to improve the CMOS process compatibility of the manufacturing process of the silicon nitride-lithium niobate electro-optic modulation device is one of the current research directions. In prior designs of electro-optic modulators, thin film lithium niobate wafers or dice of lithium niobate thin film/buried oxide layer/silicon substrate are typically bonded over a silicon nitride or silicon waveguide core at the time of fabrication, and then the silicon substrate of the thin film lithium niobate wafer is removed to achieve heterogeneous integration of lithium niobate-silicon nitride.

At present, the silicon substrate is usually removed by a mode of grinding thinning the back surface of the silicon substrate and dry or wet etching of silicon, and the whole silicon substrate is required to be removed by grinding thinning and etching, so that longer process time and more etching gas or etching liquid are required, the removal efficiency is reduced, the process cost is increased, and meanwhile, the problems of poor etching uniformity, increased optical waveguide propagation loss caused by residual silicon substrate, damage to the optical waveguide substrate and the like are also easy to occur.

Disclosure of Invention

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

The electro-optical film comprises a first substrate, a second substrate, a first bonding medium layer, a second bonding medium layer, a first electro-optical film layer, a second electro-optical film layer, a first bonding medium layer, a second bonding medium layer, a third bonding medium layer and a fourth bonding medium layer, wherein a plurality of protruding parts are arranged on the first substrate, gaps are reserved between the adjacent protruding parts, each protruding part is provided with the first bonding medium layer, the protruding parts comprise an etching layer, the removal rate of the etching layer is larger than that of the first substrate and the first bonding medium layer, and the electro-optical film layer is in bonding connection with the first bonding medium layer.

The embodiment of the invention also provides a preparation method of the electro-optic film wafer, which comprises the following steps:

step 1, forming an etching surface on the surface or inside a first substrate;

step 2, forming a first bonding medium surface on the first substrate or the etching surface;

Step 3, carrying out graphical processing along the direction from the first bonding medium surface to the first substrate to obtain a plurality of protruding parts, wherein each protruding part comprises an etching layer, and each protruding part is provided with a first bonding medium layer;

And 4, forming an electro-optic film layer on the first bonding medium layer to obtain the electro-optic film wafer.

The embodiment of the invention also provides a preparation method of the heterogeneous integrated electro-optic modulator, which comprises the following steps:

s1, preparing the electro-optic film wafer, and cutting the electro-optic film wafer to obtain electro-optic film wafer slices, wherein each electro-optic film wafer slice comprises a plurality of protruding parts;

s2, preparing an optical waveguide wafer;

S3, bonding the electro-optical film wafer slice on the optical waveguide wafer, so that the waveguide core of the optical waveguide wafer corresponds to the protruding part or the gap between the two protruding parts on the electro-optical film wafer slice;

S4, etching the protruding portion to remove the first substrate of the electro-optical film wafer slice;

S5, removing the residual protruding parts on the first bonding medium layer of the electro-optic film wafer slice;

And S6, forming electrodes on the electro-optical film layer or the optical waveguide wafer and positioned on two sides of the waveguide core of the optical waveguide wafer to obtain the heterogeneous integrated electro-optical modulator.

According to the electro-optical film wafer, the protruding part with the etching layer (such as the ion implantation damage layer or the sacrificial layer) is arranged between the electro-optical film layer and the substrate. When the heterogeneous integrated electro-optical modulation device is manufactured, the electro-optical film wafer or the first substrate sliced by the electro-optical film wafer can be quickly separated from the protruding part, so that the preparation efficiency is improved and the cost is reduced. Compared with the prior art, the method has the following advantages:

1. By introducing the bulge of the ion implantation damage layer or the sacrifice layer below the electro-optic film layer of the electro-optic film wafer, the substrate of the electro-optic film wafer can be separated from the electro-optic film layer from the damage layer or the sacrifice layer without etching the whole substrate, so that less process time is required, the use amount of etching liquid and etching gas is saved, and the problems of propagation loss increase, damage to the optical waveguide wafer and the like caused by uneven etching of the substrate and residual substrate are solved;

2. by designing the gap of the protruding part, the etching liquid or solvent is facilitated to contact with the protruding part near the center of the electro-optic film wafer (or small piece), and the separation time of the electro-optic film wafer substrate is shortened.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and that other drawings can be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a schematic view of a first configuration of an electro-optic Bao Mojing circle according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of a second configuration of an electro-optic Bao Mojing circle according to an embodiment of the present invention;

FIG. 3 is a schematic view of a third configuration of an electro-optic Bao Mojing circle according to an embodiment of the present invention;

FIG. 4 is a schematic illustration of a first bonding medium surface formed on a first substrate in the circle of electro-optics Bao Mojing shown in FIG. 1;

FIG. 5 is a schematic view of the structure of FIG. 4 after an ion implantation operation;

FIG. 6 is a top view of a first raised portion structure resulting from the patterning of the structure shown in FIG. 5;

FIG. 7 is a top view of a second bump structure resulting from the patterning of the structure shown in FIG. 5;

FIG. 8 is a cross-sectional view at AA in FIGS. 6 and 7;

FIG. 9 is a top view of an electro-optic Bao Mojing circle with a stripe-shaped raised portion according to an embodiment of the present invention;

FIG. 10 is a top view of an electro-optic thin film wafer with columnar protrusions according to an embodiment of the present invention;

FIG. 11 is a flow chart of a method of fabricating a heterogeneous integrated electro-optic modulator according to an embodiment of the present invention;

FIG. 12 is a top view of an electro-optic film layer die formed by patterning an electro-optic film wafer of the present invention;

FIG. 13 is a cross-sectional view of the electro-optic thin film wafer of FIG. 1 at AA shown in FIG. 12;

FIG. 14 is a schematic view of an electro-optic film wafer slice cut from the electro-optic film wafer shown in FIG. 1;

FIG. 15 is a cross-sectional view of the electro-optic thin film wafer of FIG. 2 at AA shown in FIG. 12;

FIG. 16 is a schematic illustration of an electro-optic thin film wafer slice cut from the electro-optic Bao Mojing wafer shown in FIG. 2;

FIG. 17 is a cross-sectional view of a first configuration of an optical waveguide wafer in accordance with the present invention;

FIG. 18 is a schematic illustration of a lower cladding upper groove of the present disclosure;

FIG. 19 is a top view of a second structure of an optical waveguide wafer without a second bonding medium layer formed therein in accordance with the present invention;

FIG. 20 is a cross-sectional view of the structure of FIG. 19 at AA after formation of a second bonding dielectric layer;

FIG. 21 is a cross-sectional view of the structure of FIG. 19 at BB after formation of a second bonding dielectric layer;

FIG. 22 is a top view of a third configuration of an optical waveguide wafer without a second bonding medium layer formed in accordance with the present invention;

FIG. 23 is a cross-sectional view of the structure of FIG. 22 at AA after forming a second bonding dielectric layer;

FIG. 24 is a cross-sectional view of the structure shown in FIG. 22 at BB after formation of a second bonding dielectric layer;

FIG. 25 is a cross-sectional view of the structure of FIG. 22 at CC after formation of a second bonding dielectric layer;

FIG. 26 is a schematic illustration of an electro-optic thin film wafer slice of the present invention bonded to the optical waveguide wafer of FIG. 17;

FIG. 27 is another schematic illustration of an electro-optic thin film wafer slice of the present invention bonded to the optical waveguide wafer of FIG. 17;

FIG. 28 is a schematic illustration of only the first bonding dielectric layer and the electro-optic thin film layer remaining after etching;

FIG. 29 is a schematic diagram of a heterogeneous integrated electro-optic modulator of the present invention;

1, a first substrate; 2, a convex part, 3, a gap, 4, a first bonding medium layer, 5, an electro-optical film layer, 41, a first bonding medium surface, 2021, a damaged surface, 201, a first substrate convex layer, 202, an etching layer, 203, a first substrate film layer, 6, a second substrate, 7, a lower cladding layer, 8, a groove, 81, a middle equal-width groove, 82, an end tapered groove, 9, a silicon-rich silicon nitride waveguide core, 10, an intermediate layer, 11, a second bonding medium layer, 12, a first silicon nitride waveguide core, 13, a second silicon nitride waveguide core, 14, a waveguide core, 15 and an electrode.

Detailed Description

Embodiments of the present application will be described in detail below with reference to the accompanying drawings.

Other advantages and effects of the present application will become apparent to those skilled in the art from the following disclosure, which describes the embodiments of the present application with reference to specific examples. It will be apparent that the described embodiments are only some, but not all, embodiments of the application. The application may be practiced or carried out in other embodiments that depart from the specific details, and the details of the present description may be modified or varied from the spirit and scope of the present application. It should be noted that the following embodiments and features of the embodiments may be combined with each other without conflict. Based on the embodiments of the present application, other embodiments that may be obtained by those of ordinary skill in the art without making any inventive effort are within the scope of the present application.

The embodiment of the invention discloses an electro-optic film wafer, which is shown in fig. 1, 2 and 3, and comprises a first substrate 1 and an electro-optic film layer 5. The electro-optical film comprises a first substrate 1, a plurality of convex parts 2 are arranged on the first substrate 1, gaps 3 are reserved between the adjacent convex parts 2, a first bonding medium layer 4 is arranged on each convex part 2, the convex part 2 comprises an etching layer 202, the removal rate of the etching layer 202 is larger than the removal rates of the first substrate 1 and the first bonding medium layer 4, and the electro-optical film layer 5 is in bonding connection with the first bonding medium layer 4.

According to the invention, the etching layer 202 is formed in the first substrate 1 of the electro-optical film wafer, and the first substrate 1 and the electro-optical film layer 5 are separated by etching the etching layer 202, so that the removing time of the first substrate 1 on the electro-optical film wafer is shortened, the cost is reduced, the substrate removing uniformity is improved, the influence of substrate residues on the propagation loss of the optical waveguide is reduced, the etching damage of the optical waveguide substrate is reduced, and the like.

Further, referring to fig. 6 and 7, the protrusions 2 may be stripe-shaped, pillar-shaped, or a combination of both, and the protrusions 2 are distributed in an array on the first substrate 1. The gap 3 between the protruding portions 2 may be set to 1-10 um, the width of the protruding portions 2 may be set to 1-5 um, and the height may be set to 0.5-5 um.

Further, the electro-optical thin film layer 5 may be made of electro-optical crystal materials such as lithium niobate, lithium tantalate, barium titanate, and the like, and the thickness thereof may be set to 100-500 nm. Meanwhile, a protective film can be arranged on one surface 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, and the electro-optical film layer 5 can be protected during preparation of the electro-optical modulator through the arrangement of the protective film, so that the electro-optical film layer 5 is prevented from being damaged by etching liquid.

In one embodiment of the protrusion 2, as shown in fig. 1, the protrusion 2 includes a first substrate protrusion layer 201, the etching layer 202, and a first substrate thin film layer 203 in a direction facing away from the first substrate 1, and the first substrate thin 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, the implanted ions are H ⁺ and/or He ⁺, the implantation energy is 50-1000 keV, the total implantation dose is 5×10 ¹⁵cm^-2～5×10¹⁷cm^-2, and the material of the first bonding medium layer 4 is silicon dioxide or aluminum oxide.

In another embodiment of the protrusion 2, as shown in fig. 2 and 3, 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 temporary bonding glue on the surface of the first substrate 1. As shown in fig. 2, the sacrificial layers may be disposed at positions where the protrusions 2 are formed on the first substrate 1, and the first substrate 1 is exposed in the gap 3 between adjacent two sacrificial layers. Referring to fig. 3, a material for forming a sacrificial layer may be disposed on the entire surface of the first substrate 1, and then patterning is performed to remove a portion of the sacrificial layer to form the protruding portions 2, where the first substrate 1 is not exposed in the gaps 3 between two adjacent protruding portions 2, i.e., the surface has a sacrificial layer. The thickness of the sacrificial layer may be set to 0.5-5 um. 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 be 10-500 nm. The material of the first substrate 1 may be silicon, quartz, or the like.

The embodiment of the invention also provides a preparation method of the electro-optic film wafer shown in fig. 1 to 3, which comprises the following steps:

step 1, forming an etching surface on the surface or inside a first substrate;

The preparation method of the electro-optic film wafer shown in fig. 1 specifically comprises the following steps:

Step 1.1, referring to fig. 4, forming a first bonding medium face 41 on a first substrate 1;

Step 1.2, performing ion implantation on the first substrate 1 below the first bonding medium surface 41, and forming a damaged surface 2021 parallel to the first bonding medium surface 41 in the first substrate 1 as shown in fig. 5;

Step 1.3, performing a patterning process along the direction from the first bonding medium surface 41 to the first substrate 1 to obtain a plurality of protruding portions 2, where each protruding portion 2 is provided with a first bonding medium layer 4, and the protruding portion 2 includes a first substrate protruding 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 performing the patterning process is shown in fig. 8.

And step 1.4, forming an electro-optical film layer 5 on the first bonding medium layer 4 to obtain the electro-optical film wafer shown in fig. 9 or 10.

In the process of preparing the electro-optical thin film wafer shown in fig. 1, the order of steps 1 and 2 may be changed, that is, the damaged surface 2021 may be formed in the first substrate 1, and then the first bonding medium surface 41 may be formed on the surface of the first substrate 1.

The preparation method of the electro-optical film wafer shown in fig. 2 and 3 specifically comprises the following steps:

step 2.1, amorphous silicon, silicon dioxide or metal is deposited on the first substrate 1, or temporary bonding glue is coated to form a sacrificial layer;

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

And 2.3, carrying out patterning along the direction from the first bonding medium surface 41 to the first substrate 1 to obtain a plurality of protruding parts 2, and forming a first bonding medium layer 4 on each protruding part 2 after the first bonding medium surface 41 is patterned.

Step 2.4, bonding the electro-optical film layer 5 on the first bonding medium layer 4 of the protruding portion 2, so as to obtain the electro-optical film wafer shown in fig. 9 or 10 in a top view and in fig. 2 or 3 in a cross-section.

The embodiment of the invention also provides a preparation method of the heterogeneous integrated electro-optic modulator, which is shown in fig. 11, and comprises the following steps:

S1, preparing the electro-optic film wafer, and cutting the electro-optic film wafer to obtain electro-optic film wafer slices, wherein each electro-optic film wafer slice comprises a plurality of protruding parts 2;

s2, preparing an optical waveguide wafer;

s3, bonding the electro-optical film wafer slice on the optical waveguide wafer, so that the waveguide core 14 of the optical waveguide wafer corresponds to the convex part 2 or the gap between the two convex parts 2 on the electro-optical film wafer slice, and the bonded structure is shown in fig. 26 and 27;

S4, etching the protruding portion 2 to remove the first substrate 1 of the electro-optical film wafer slice;

s5, removing the residual protruding part 2 on the first bonding medium layer 4 of the electro-optic film wafer slice, and obtaining a structure shown in fig. 28 after removal;

And S6, forming electrodes 15 on the electro-optical film layer 5 or the optical waveguide wafer and positioned on two sides of the waveguide core 14 of the optical waveguide wafer to obtain a heterogeneous integrated electro-optical modulator, wherein the structure of the heterogeneous integrated electro-optical modulator is shown in fig. 29.

Further, in the step S1, the electro-optical thin film wafer slice is obtained by cutting the electro-optical thin film wafer in the above embodiment, and the structure of the electro-optical Bao Mojing wafer slice is shown in fig. 12 to 16. When dicing, the first substrate 1 is diced along the gaps of the electro-optical film layer dice, forming electro-optical film wafer slices. The electro-optic film layer die corresponds to the plurality of projections 2, and in order to reduce the possibility of breakage of the electro-optic film layer die during dicing of the first substrate, the gaps of part (for the stripe-shaped projections or the columnar projections) or all (for the columnar projections) of the electro-optic film layer die are located entirely within the gaps 3 of the projections 2.

In an alternative embodiment for preparing an optical waveguide wafer, the structure shown in fig. 17 is a conventional optical waveguide wafer, which is prepared by forming a lower cladding layer 7 on a second substrate 6, forming a waveguide core 14 on the lower cladding layer 7, and forming a second bonding medium layer 11 to cover the waveguide core 14 and the lower cladding layer 7. The material of the second substrate 6 may be silicon, and the material of the lower cladding 7 may be silicon dioxide, with a thickness of 2-20 um. In a specific implementation, the second substrate 6 is a silicon substrate completely covered by a thermal oxide layer, the thermal oxide layer is used as the lower cladding layer 7, the material of the waveguide core 14 may be a single layer or a stacked layer (such as silicon nitride/silicon dioxide/silicon nitride) of which the refractive index is greater than that of the lower cladding layer 7, for example, silicon nitride, silicon and the like, the second bonding medium layer 11 may be silicon dioxide, aluminum oxide, bonding glue or a combination thereof, and the thickness of the second bonding medium layer 11 above the waveguide core 14 is 10-300 nm.

In an alternative embodiment for preparing an optical waveguide wafer, the structure of the optical waveguide wafer is shown in fig. 18 to 25, and the preparation process of the optical waveguide wafer includes:

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 two ends of each middle equal-width groove 81 to obtain grooves 8;

S22, sequentially forming a first silicon nitride layer and a silicon-rich silicon nitride layer on the lower cladding 7, and removing the part, located outside the groove 8, of the silicon-rich silicon nitride layer through chemical mechanical polishing to form a silicon-rich silicon nitride waveguide core 9;

S23, sequentially covering an intermediate layer 10 and a second silicon nitride layer on the first silicon nitride layer and the silicon-rich silicon nitride waveguide core 9, and performing graphical treatment to obtain a silicon nitride waveguide core;

And S24, covering the second bonding medium layer 11 on the lower cladding layer 7 and the silicon nitride waveguide core to obtain the optical waveguide wafer.

In an alternative embodiment of the above step S22, forming a first silicon nitride layer and a silicon-rich silicon nitride layer sequentially on the lower cladding layer 7 includes:

s2211, forming a first silicon nitride layer on the bottom wall and the side wall of the groove 8 and the lower cladding 7 positioned outside the groove 8;

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.

In an alternative embodiment of the above step S23, as shown in fig. 19 to 21, the first silicon nitride layer and the silicon-rich silicon nitride waveguide core 9 are covered with an intermediate layer 10 and a second silicon nitride layer in sequence, and the patterning process is performed to obtain a silicon nitride waveguide core, which includes:

s2301, covering an intermediate layer 10 on the first silicon nitride layer and the silicon-rich silicon nitride waveguide core 9, and covering a second silicon nitride layer on the intermediate layer 10;

S2302, synchronously patterning the second silicon nitride layer, the intermediate layer 10 and the first silicon nitride layer to obtain the silicon nitride waveguide cores which are projected to completely cover at least two silicon-rich silicon nitride waveguide cores 9, wherein the silicon nitride waveguide cores comprise integrated out-of-groove silicon nitride waveguide cores and in-groove silicon nitride waveguide cores;

each position of S2303, the out-of-groove silicon nitride waveguide core and the in-groove silicon nitride waveguide core includes a stacked first silicon nitride waveguide core 12, the intermediate layer 10 and a second silicon nitride waveguide core 13.

In another alternative embodiment of the above step S23, as shown in fig. 22 to 25, the first silicon nitride layer and the silicon-rich silicon nitride waveguide core 9 are covered with an intermediate layer 10 and a second silicon nitride layer in sequence, and the patterning process is performed to obtain a silicon nitride waveguide core, which includes:

s2311, covering an intermediate layer 10 on the first silicon nitride layer and the silicon-rich silicon nitride waveguide core 9, and covering a second silicon nitride layer on the intermediate layer 10;

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 second sub-silicon nitride waveguide cores which are positioned between the two grooves 8 and have equal width and tapered ends, and the tapered parts at the two ends of each second sub-silicon nitride waveguide core and the tapered parts of the silicon-rich silicon nitride waveguide core 9 are in inverted superposition;

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.

Further, in the step S4, the product may be placed into an etching solution, the etching layer 202 of the protrusion 2 is rapidly dissolved by a wet etching method, the first substrate 1 on the electro-optical thin film wafer slice is removed, and the first substrate 1 is removed from the etching solution after being separated from the product, so as to avoid the etching solution consuming the etching solution by dissolving the first substrate 1 again.

More specifically, in the first wet etching in step S4, since the damaged layer/sacrificial layer has a higher etching rate, before the first substrate 1 and the second bonding dielectric layer 11 are subjected to severe etching, the first substrate 1 may be separated from the electro-optical thin film layer 5 from the damaged layer, and the time of the first wet etching may be set to 5 to 50 minutes. The gaps 3 between the projections 2 facilitate the contact of the etching liquid with the damaged layer/sacrificial layer near the center of the first substrate 1 at the time of etching to shorten the time required for separation of the first substrate 1.

Further, in the step S5, according to the method of selectively removing the damaged layer or the sacrificial layer of the etching layer 202, the etching solution or the dry etching may be selected to perform the second etching to remove the residual protrusion 2 on the first bonding medium layer 4 when the etching layer 202 is the damaged layer. When the etching layer 202 is a sacrificial layer, a wet etching method may be used to remove the residual protrusion 2 on the first bonding medium layer 4. The second etching time may be 2 to 20 minutes. Wherein, the etching liquid can be any one of KOH solution, TMAH solution, acid solution and temporary bonding peptizing agent, and the dry etching can be XeF ₂ gas phase etching.

More specifically, when the etching layer 202 is silicon or amorphous silicon, a wet etching solution such as KOH, TMAH solution, etc. may be used to remove the sacrificial layer, for example, the etching condition may be 10-40 wt% TMAH solution, the temperature may be 60-90 ℃, and the time may be 2-50 minutes. When the sacrificial layer is made of metals such as Al, cu and the like, the sacrificial layer can be removed by adopting an acid solution wet etching liquid, and when the sacrificial layer is made of temporary bonding glue, the bonding glue can be dissolved by using a solvent to remove the temporary bonding glue.

Further, in order to prevent etching from being performed on the back surfaces of the first substrate 1 and the second substrate 6 by the etching solution, thereby saving the usage amount of the etching solution and reducing the cost, the preparation method further includes:

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

Further, in the implementation of step S6, the electrode material may be Au, al, cu, etc., the electrode pitch is 4-10 um, and the electrode thickness is 0.5-2 um.

According to the electro-optical film wafer, the protruding part with the ion implantation damage layer or the sacrificial layer is arranged between the electro-optical film layer and the substrate. When the heterogeneous integrated electro-optical modulation device is manufactured, the electro-optical film wafer or the first substrate of the electro-optical film wafer slice can be rapidly separated from the convex part, so that the preparation efficiency is improved and the cost is reduced. Compared with the prior art, the method has the following advantages:

It will be apparent to those skilled in the art that the foregoing is merely a preferred embodiment of the present invention and is not intended to limit the invention, and that various modifications and variations can be made to the embodiment of the present invention by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. An electro-optical thin film wafer, comprising:

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 is characterized in that a protective film is also provided on the side of the electro-optical thin 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 protrusion (2) comprises a first substrate protrusion layer (201), the etching layer (202) and a first substrate thin film layer (203) along a direction 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 it comprises:

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 preparing an optical waveguide wafer comprises:

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 the 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 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).