Thin film structure and preparation method thereof, and electronic device

Abstract

This application provides a thin film structure, a method for preparing it, and an electronic device, relating to the field of semiconductor component technology. The thin film structure comprises a support structure and thin film layers disposed on the support structure; the thin film layers comprise a lithium niobate thin film layer and a doped lithium niobate thin film layer arranged in parallel. This application is intended to reduce the resistance of the lithium niobate crystal while ensuring the electro-optical modulation efficiency of the electronic device, thereby improving the performance of the electronic device.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor devices, in particular to a thin film structure and a method for preparing the same, and an electronic device. Background Art

[0002] Electro-optic modulators are core components in optical communication systems. With the increasing demand for communication capacity and speed, new-generation electro-optic modulators must simultaneously meet the requirements of high integration density, low cost, and high performance. Lithium niobate crystals have attracted considerable attention due to their excellent physicochemical stability, wide low-optical-loss window, and large linear electro-optic coefficient. However, in practical applications, electro-optic modulators are affected by external conditions such as temperature and humidity fluctuations, abnormal physical stress, and external interfering electric fields, resulting in phase drift and a subsequent shift in the device's DC bias operating point. This phenomenon is known as "DC drift." When a modulator operating point experiencing DC drift falls within the nonlinear region, it distorts the modulated optical signal, leading to device failure and limiting its practical application.

[0003] In order to suppress DC drift, the related art usually reduces the resistance of the lithium niobate crystal; however, while reducing the resistance of the lithium niobate crystal, it also leads to a decrease in the electro-optical modulation efficiency of the electro-optical modulator, thereby reducing the performance of the electro-optical modulator. Summary of the Invention

[0004] In view of the above problems, the embodiments of the present application provide a thin film structure and a preparation method thereof, and an electronic device, which can reduce the resistance of the lithium niobate crystal while ensuring the electro-optical modulation efficiency of the electronic device, thereby improving the performance of the electronic device.

[0005] A first aspect of an embodiment of the present application provides a thin film structure, comprising:

[0006] A support structure and a film layer disposed on the support structure;

[0007] The thin film layer includes a lithium niobate thin film layer and a doped lithium niobate thin film layer arranged in parallel.

[0008] In a possible implementation, the thin film layer includes a waveguide structure, and the waveguide structure spans the lithium niobate thin film layer and the doped lithium niobate thin film layer.

[0009] In a possible implementation, the lithium niobate thin film layer and the doped lithium niobate thin film layer are arranged along a first direction.

[0010] In a possible implementation, the support structure is a strip structure; the first direction is the length direction of the support structure, and the dimensions of the lithium niobate thin film layer and the doped lithium niobate thin film layer in the second direction are equal to the width of the support structure;

[0011] Alternatively, the first direction is the width direction of the support structure, and the dimensions of the lithium niobate thin film layer and the doped lithium niobate thin film layer in the second direction are equal to the length of the support structure;

[0012] The first direction intersects with the second direction.

[0013] A second aspect of the embodiments of the present application provides a method for preparing a thin film structure, comprising:

[0014] Providing a lithium niobate wafer and a doped lithium niobate wafer arranged side by side along a first direction;

[0015] Bonding the lithium niobate wafer and the doped lithium niobate wafer in parallel to form a bonding structure; wherein the top surface of the lithium niobate wafer is flush with the top surface of the doped lithium niobate wafer;

[0016] performing an ion implantation process on the bonding structure so that the bonding structure forms a thin film layer, an implantation layer and a residual layer that are stacked;

[0017] The thin film layer of the bonding structure after the ion implantation process is bonded to the support structure, and the implantation layer and the residual layer are removed to form a bonding body; wherein the thin film layer includes a lithium niobate thin film layer and a doped lithium niobate thin film layer arranged in parallel.

[0018] In a possible implementation, the method further includes patterning the thin film layer of the bonding body to form a waveguide structure in the thin film layer, wherein the waveguide structure spans the lithium niobate thin film layer and the doped lithium niobate thin film layer.

[0019] In a possible implementation, the lithium niobate wafer has a first bonding surface, and the doped lithium niobate wafer has a second bonding surface;

[0020] After the step of providing the lithium niobate wafer and the doped lithium niobate wafer arranged in parallel, and before the step of performing an ion implantation process on the bonded structure, the method further includes:

[0021] The first bonding surface and the second bonding surface are respectively activated to improve the activities of the first bonding surface and the second bonding surface.

[0022] In a possible implementation, the support structure is a strip-shaped structure;

[0023] The first direction is the length direction of the supporting structure; or, the first direction is the width direction of the supporting structure.

[0024] In a possible implementation, before the step of bonding the thin film layer of the bonding structure after ion treatment to the support structure, the following steps are further included:

[0025] providing a substrate;

[0026] A capture layer and an isolation layer are stacked on the substrate. The capture layer and the isolation layer are made of different materials, and the capture layer has a thickness of 300 nm to 5000 nm.

[0027] In a possible implementation, the step of bonding the thin film layer of the bonding structure after ion treatment to the support structure further includes:

[0028] At least one heat treatment process is performed on the bonded bonding structure and the supporting structure to peel off the implantation layer and the residual layer of the bonding structure.

[0029] In a possible implementation, a first heat treatment process is performed on the bonded bonding structure and the supporting structure to peel off the injection layer and the residual layer; wherein the temperature of the first heat treatment process is 100° C. to 600° C., and the heat treatment time is 1 minute to 48 hours;

[0030] A second heat treatment process is performed on the peeled bonding structure and the supporting structure, wherein the temperature of the second heat treatment process is 300° C. to 600° C., and the heat treatment time is 1 minute to 100 hours.

[0031] A third aspect of the embodiments of the present application provides an electronic device comprising the thin film structure described in the second aspect.

[0032] In the thin film structure, preparation method, and electronic device provided in the embodiments of the present application, a lithium niobate wafer and a doped lithium niobate wafer are bonded in parallel to form a bonded structure, and the top surface of the bonded lithium niobate wafer is flush with the top surface of the doped lithium niobate wafer. This allows the bonded structure to be made of both lithium niobate and doped lithium niobate, combining the advantages of both materials. The doped lithium niobate can be used to reduce the resistance of the formed thin film structure, thereby better suppressing drift. The high linear electro-optic coefficient of lithium niobate can also be used to improve the electro-optic modulation efficiency of the thin film structure, resulting in electronic devices with superior performance in areas such as photoelectric conversion and optical signal processing.

[0033] In addition to the technical problems solved by the embodiments of the present application described above, the technical features that constitute the technical solutions, and the beneficial effects brought about by the technical features of these technical solutions, the thin film structure and its preparation method, other technical problems that can be solved by the electronic device provided by the embodiments of the present application, other technical features included in the technical solutions, and the beneficial effects brought about by these technical features will be further described in detail in the specific implementation methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, a brief introduction will be given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are 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.

[0035] Figure 1 Equivalent circuit diagrams of electronic devices provided for related technologies;

[0036] Figure 2 A process flow chart of a method for preparing a thin film structure provided in an embodiment of the present application;

[0037] Figure 3 A structural diagram designed for the method for preparing the thin film structure provided in an embodiment of the present application;

[0038] Figure 4 Schematic diagram of the film structure provided in the embodiment of this application Figure 1 ;

[0039] Figure 5 Schematic diagram of the film structure provided in the embodiment of this application Figure 2 .

[0040] Reference numerals:

[0041] 100: bonding structure; 110: lithium niobate wafer; 111: first bonding surface; 120: doped lithium niobate wafer; 121: second bonding surface; 130: thin film layer; 131: lithium niobate thin film layer; 132: doped lithium niobate thin film layer; 140: injection layer; 150: residual layer; 160: waveguide structure; 171: positive electrode; 172: negative electrode; 173: ground electrode; 174: signal electrode;

[0042] 200: support structure; 210: substrate; 220: capture layer; 230: isolation layer;

[0043] 300: bonding body;

[0044] 400: Thin film structure. DETAILED DESCRIPTION

[0045] DC drift is a key factor that affects the performance stability of lithium niobate electro-optic modulators and limits their practical applications. In related technologies, the DC drift performance of electro-optic modulators is usually studied using the "equivalent circuit model". Figure 1The figure shows a schematic diagram of the cross-sectional structure of a lithium niobate thin film waveguide modulator, in which the modulation voltage signal is applied to the waveguide through the Au electrode, and the modulation electric field direction is parallel to the z-axis direction of the lithium niobate crystal to utilize its maximum linear electro-optic coefficient γ 33 .

[0046] In order to study the effect of the buffer layer in the LNOI film on the DC drift phenomenon and exclude other influencing factors, no buffer layer is set between the modulation electrode and the lithium niobate film layer. The corresponding equivalent circuit model is as follows: Figure 1 As shown, where E0 is the voltage across the electrodes, V t is the voltage across the optical waveguide region, R LN1 (C LN1 ) and R LN2 (C LN2 ) are the lateral and longitudinal resistances (capacitances) of the lithium niobate film waveguide region, R SIO1 (C SIO1 ) and R SIO2 (C SIO2 ) are the horizontal and vertical resistance (capacitance) of the buffer layer, R Sub (C Sub ) is the resistance (capacitance) of the substrate region. Similar to the equivalent circuit model of the titanium diffused waveguide modulator, the effective voltage actually applied to the optical waveguide is not constant, but varies with time. This phenomenon is called DC drift. When t→∞, V t It will tend to a stable value:

[0047]

[0048] Among them, R a is the total effective lateral resistance:

[0049]

[0050] R b is the effective lateral resistance of the buffer layer and substrate region:

[0051]

[0052] According to the equivalent circuit model and formula (1), in order to suppress the DC drift phenomenon, the simplest method is to reduce the longitudinal resistance R of the lithium niobate crystal. LN2 , so that R LN2 < <R a , thus achieving V ∞ Approaching E0.

[0053] Based on the above theory, in related technologies, metal elements (Mg) are usually doped into lithium niobate crystals to significantly reduce the resistivity of lithium niobate crystals. For example, the resistivity of pure CLN crystals is 10 18-19 Ω·cm, the resistivity of MgO-doped CLN crystal is 10 12 Ω·cm, and the resistivity of lithium niobate crystal can be reduced by 6-7 orders of magnitude by doping MgO with a threshold concentration. However, compared with pure CLN crystal, the linear electro-optic coefficient γ of CLN crystal doped with MgO is 33 It dropped by 20-30%, resulting in a decrease in electro-optical modulation efficiency.

[0054] To address the above technical issues, embodiments of the present application provide a thin film structure, a method for preparing the same, and an electronic device, wherein a lithium niobate wafer and a doped lithium niobate wafer are bonded in parallel to form a bonded structure, wherein the top surface of the bonded lithium niobate wafer is flush with the top surface of the doped lithium niobate wafer. This allows the bonded structure to be made of both lithium niobate and doped lithium niobate, combining the advantages of both materials. The doped lithium niobate can be used to reduce the resistance of the resulting thin film structure, thereby better suppressing drift. Furthermore, the high linear electro-optic coefficient of lithium niobate can be utilized to improve the electro-optic modulation efficiency of the thin film structure, resulting in electronic devices with superior performance in areas such as photoelectric conversion and optical signal processing.

[0055] In order to make the above-mentioned purposes, features and advantages of the embodiments of the present application more obvious and easy to understand, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0056] Please refer to the attached Figure 1 and attached Figure 2 , a method for preparing a thin film structure provided in an embodiment of the present application includes the following steps:

[0057] Step S100: providing a lithium niobate wafer and a doped lithium niobate wafer arranged side by side along a first direction.

[0058] In this embodiment, lithium niobate wafer 110 is pure lithium niobate, without any doping elements. For example, lithium niobate wafer 110 is 0.5 mm thick and has a relatively smooth surface. Lithium niobate single-crystal thin films not only possess the excellent properties of bulk materials but also exhibit a high refractive index and contrast ratio, enabling dense integration, reducing electronic device size, lowering power consumption, and improving performance. This is a key area of ​​materials research, with significant application value and prospects in fields such as fiber-optic communications and data centers.

[0059] The doping element in the doped lithium niobate wafer 120 (CLN) can be a highly conductive metal element, such as magnesium, zinc, or another metal element. In one possible embodiment, the doping element in the doped lithium niobate wafer 120 is magnesium, and the magnesium exists in the form of an oxide. Specifically, the material of the doped lithium niobate wafer 120 includes a mixture of magnesium oxide and lithium niobate, and the molar percentage concentration of magnesium in the doped lithium niobate wafer 120 is 5%; that is, the ratio of the molar mass of magnesium to the molar mass of niobium in the doped lithium niobate wafer 120 is 5%.

[0060] In the embodiment of the present application, the lithium niobate wafer 110 and the doped lithium niobate wafer 120 are arranged side by side along a first direction. The first direction can be understood as a direction parallel to a horizontal plane, or in other words, the first direction can be any direction within the horizontal plane. For example, the first direction can be the X direction within the horizontal plane, or the Y direction within the horizontal plane, or can be at a certain angle to the X or Y direction within the horizontal plane.

[0061] Step S200: bonding a lithium niobate wafer and a doped lithium niobate wafer in parallel to form a bonding structure; wherein the top surface of the lithium niobate wafer is flush with the top surface of the doped lithium niobate wafer.

[0062] Illustratively, a bonding process is used to bond a lithium niobate wafer 110 and a doped lithium niobate wafer 120 to form a bonded structure 100. It should be understood that before bonding, the lithium niobate wafer 110 and the doped lithium niobate wafer 120 are cleaned to remove contaminants, such as dust or grease, that the wafers may have come into contact with during production, transportation, or other processes. This helps to form good chemical bonds or physical adsorption, thereby improving the strength and stability of the bonded structure.

[0063] It should be noted that the cleaning process in this embodiment may include organic solvent cleaning, ultrasonic cleaning, or deionized water rinsing, etc. In addition, parallel bonding can be understood as the lithium niobate wafer 110 and the doped lithium niobate wafer 120 being arranged horizontally, not stacked.

[0064] In order to further improve the bonding strength between the lithium niobate wafer 110 and the doped lithium niobate wafer 120 , the embodiment of the present application further processes the bonding surfaces of the lithium niobate wafer 110 and the doped lithium niobate wafer 120 .

[0065] Illustratively, the lithium niobate wafer 110 has a first bonding surface 111, and the doped lithium niobate wafer 120 has a second bonding surface 121. The first bonding surface 111 and the second bonding surface 121 are each activated to increase their activity and facilitate bonding between the first bonding surface 111 and the second bonding surface 121.

[0066] For example, oxygen plasma can be used to perform plasma activation treatment on the first bonding surface 111 and the second bonding surface 121. High-energy particles (such as oxygen atoms and oxygen ions) in the oxygen plasma bombard the surfaces of the first bonding surface 111 and the second bonding surface 121, breaking existing chemical bonds and forming new, more active chemical bonds (such as hydroxyl groups and carboxyl groups), thereby improving the bonding strength between the first bonding surface 111 and the second bonding surface 121. At the same time, the plasma can also remove trace organic matter and oxides on the surface, further cleaning the surfaces of the first bonding surface 111 and the second bonding surface 121.

[0067] Step S300 : performing an ion implantation process on the bonding structure, so that the bonding structure forms a thin film layer, an implantation layer, and a residual layer that are stacked.

[0068] The ion implantation process may be a conventional process, for example, a plasma implantation process. The implanted ions may be ions capable of generating a gas by heat treatment, for example, hydrogen ions, helium ions, nitrogen ions, oxygen ions, or argon ions.

[0069] It should be understood that the layer where the ions reside is the implantation layer 140, or the implantation layer 140 is the region within the bonded structure 100 where the implanted ions stop. The implantation layer 140 divides the bonded structure 100 into a thin film layer 130 and a residual layer 150. The residual layer 150 refers to the region that the implanted ions failed to reach during the ion implantation process. This layer typically retains the properties of the original material because it is not directly affected by the ions. The thin film layer 130 generally refers to the region below the implantation layer 140 and may be formed due to energy deposition during the implantation process and subsequent processing (such as heat treatment).

[0070] In the embodiment of the present application, the diffusion width of the injection layer 140 can be adjusted by adjusting the ion implantation dose. Specifically, the larger the ion implantation dose, the wider the diffusion width of the injection layer 140; conversely, the smaller the ion implantation dose, the narrower the diffusion width of the injection layer.

[0071] In addition, the thickness of the thin film layer 130 can also be adjusted by adjusting the ion implantation depth. Specifically, the greater the depth of the ion implantation, the thicker the prepared thin film layer 130; conversely, the smaller the depth of the ion implantation, the thinner the thickness of the prepared thin film layer 130.

[0072] It should be understood that the ion implantation dose and / or implantation energy needs to be adaptively adjusted according to the type of implanted ions.

[0073] In one example, the implanted ions are hydrogen ions, and the implantation dose can be 3×10 16 ions / cm 2 ~8×10 16 ions / cm 2 , the implantation energy can be 100keV to 400keV. In another example, the implanted ions are helium ions, and the implantation dose can be 1×10 16 ions / cm 2 ~1×10 17 ions / cm 2 The implantation energy can be 50keV to 1000keV. In another example, the implanted ions are argon ions. At this time, the implantation dose of the argon ions is controlled. For example, the implantation dose of the argon ions is 4×10 16 ions / cm 2 The implantation energy is such that the implantation depth of the argon ions in the lithium niobate wafer 110 and the doped lithium niobate wafer 120 is consistent.

[0074] Step S400: bonding the thin film layer of the bonding structure after the ion implantation process to the support structure, and removing the implantation layer and the residual layer to form a bonding body; wherein the thin film layer includes a lithium niobate thin film layer and a doped lithium niobate thin film layer arranged in parallel.

[0075] In this embodiment, the support structure 200 may be a single-layer support structure, such as a silicon substrate; other structures may also be used.

[0076] Exemplarily, a substrate is provided. The substrate 210 may be a silicon (Si) substrate, an epitaxial silicon (epi-Si) substrate, a silicon germanium (SiGe) substrate, a silicon carbide (SiC) substrate, or a silicon-on-insulator (SOI) substrate. Preferably, the substrate 210 may be pure single crystal silicon.

[0077] The thickness of the substrate 210 is 0.5 mm. It should be understood that the substrate 210 may be cleaned in this step to improve the cleanliness of the surface of the substrate 210 .

[0078] Afterwards, please refer to the attached Figure 3A capture layer 220 and an isolation layer 230 are stacked on a substrate 210. The capture layer 220 and the isolation layer 230 are made of different materials, and the thickness of the capture layer 220 is 300 nm to 5000 nm.

[0079] The capture layer 220 can be prepared by a deposition process or other methods. For example, the capture layer 220 and the substrate 210 are separate film layers. In this case, the capture layer 220 can be formed on the substrate 210 through a deposition process to a certain thickness. The capture layer 220 is made of at least one of polycrystalline silicon, amorphous silicon, or polycrystalline germanium.

[0080] For another example, the capture layer 220 may be formed from a portion of the substrate 210. In this case, the capture layer 220 is formed in the substrate 210. For example, the capture layer 220 may be formed by etching the substrate 210 or implanting the substrate 210 to generate implantation damage.

[0081] Thereafter, an isolation layer 230 is formed on the capture layer 220. The material of the isolation layer 230 is different from that of the capture layer 220. For example, the material of the isolation layer 230 includes at least one of silicon dioxide, silicon oxynitride, or silicon nitride.

[0082] The isolation layer 230 may be prepared by a deposition process or an oxidation process. The deposition process may include chemical vapor deposition (CVD), physical vapor deposition (PVD), or atomic layer deposition (ALD). The oxidation process may include an in-situ formation process or a thermal oxidation process.

[0083] Specifically, when an oxidation process is used to form isolation layer 230, the capture layer 220 is made of polycrystalline silicon. In this case, the capture layer 220 is oxidized. The side of the capture layer 220 facing away from the substrate 210 is oxidized to form a silicon dioxide layer, forming isolation layer 230. The side of the capture layer 220 facing the substrate 210 remains unoxidized. The oxidation temperature for preparing the isolation layer using the oxidation process can be between 900°C and 1000°C.

[0084] In this example, there is a certain density of lattice defects in the capture layer 220, which can capture carriers between the isolation layer 230 and the substrate 210, preventing these carriers from causing carrier aggregation at the interface between the isolation layer 230 and the substrate 210, thereby reducing the loss of the thin film structure.

[0085] Furthermore, the thickness of the capture layer 220 can be between 300 nm and 5000 nm. For example, the thickness of the capture layer 220 is 300 nm, 400 nm, 500 nm, 550 nm, 600 nm, 1000 nm, 1300 nm, 1500 nm, 2000 nm, 3500 nm, 4000 nm, 4500 nm, 5000 nm, or any range between two values. By precisely controlling the thickness of the capture layer 220, its carrier capture effect can be further optimized while avoiding material waste caused by excessive thickness or insufficient capture capacity caused by excessive thinness. This thickness adjustability enables the capture layer 220 to be adapted to different application scenarios and performance requirements.

[0086] In one possible implementation, please refer to the attached Figure 4 and attached Figure 5 , the support structure 200 is a strip structure; illustratively, the strip structure can be rectangular or square. Preferably, the support structure 200 is rectangular.

[0087] This embodiment will define and explain the first direction based on the shape of the support structure 200. In one example, the first direction is the length direction of the support structure 200, and the lithium niobate wafer 110 and the doped lithium niobate wafer 120 are arranged along the length direction of the support structure 200. Figure 3 As an example, the first direction is the direction of Figure 3 Middle X direction.

[0088] In another example, the first direction is the width direction of the support structure 200, and the lithium niobate wafer 110 and the doped lithium niobate wafer 120 are arranged along the width direction of the support structure 200. Figure 3 As an example, the first direction is the direction of Figure 3 Center Y direction.

[0089] Please continue to refer to the attached Figure 3 In this embodiment, the isolation layer 230 of the support structure 200 is bonded to the thin film layer 130 of the bonding structure 100 using a bonding process, so that the support structure 200 and the bonding structure 100 are fixedly connected. In this way, the support structure 200 can be used to provide support for the bonding structure 100.

[0090] Afterwards, the implant layer 140 and the residual layer 150 of the bonding structure 100 need to be removed to form the bonding body 300. That is, the bonding body 300 includes the support structure 200 and the thin film layer 130, so that the thin film layer 130 is exposed.

[0091] Exemplarily, at least one heat treatment process is performed on the bonded bonding structure and support structure to debond the implant layer and residual layer of the bonding structure. It should be understood that the heat treatment process in this embodiment can be performed once, twice, three times, or even more times. The following uses two heat treatment processes as an example to describe in detail the debonding process of the implant layer 140 and the residual layer 150.

[0092] A first heat treatment process is performed on the bonded bonding structure 100 and the supporting structure 200. The temperature of the first heat treatment process is 100°C to 600°C, and the heat treatment time is 1 minute to 48 hours. For example, the first heat treatment process is performed on the bonded bonding structure 100 and the supporting structure 200 at a heat treatment temperature of 180°C to 300°C to peel off the injection layer 140 and the residual layer 150 from the above-mentioned product. During this process, H ions form hydrogen, He ions form helium, etc. As the heat treatment progresses, the bubbles in the injection layer 140 are connected together, and finally the injection layer 140 is cracked, separating the residual layer 150 from the thin film layer 130, thereby peeling the residual layer 150 from the bonding body 300.

[0093] Afterwards, a second heat treatment process is performed on the peeled bonding structure and support structure. The temperature of the second heat treatment process is 300°C to 600°C, and the heat treatment time is 1 minute to 100 hours. For example, it is carried out in a vacuum environment or in a protective atmosphere formed by at least one gas among nitrogen and inert gas, the heat treatment temperature is 400°C, and the holding time is 3 hours. This step can improve the bonding force (greater than 10MPa) and can restore the damage to the thin film layer 130 caused by ion implantation, so that the obtained lithium niobate (or) thin film layer is close to the properties of pure lithium niobate or doped lithium niobate single crystal.

[0094] In one possible implementation, after bonding is completed, the bonded body needs to be processed. Exemplarily, the thin film structure fabrication method further includes patterning the thin film layer of the bonded body to form a waveguide structure within the thin film layer, where the waveguide structure spans the lithium niobate thin film layer and the doped lithium niobate thin film layer.

[0095] For example, a mask layer (not shown) is formed on the thin film layer 130 of the bonding body 300, and then the mask layer is patterned to form a mask pattern on the mask layer, and the mask pattern is used to define the waveguide structure 160. The mask layer can be a photoresist or a hard mask layer. For example, a photoresist layer of a certain thickness is spin-coated on the thin film layer 130 by a coating process, and then the waveguide structure 160 is defined in the photoresist layer by electron beam lithography (EBL) technology. The structure of the waveguide structure 160 can be referred to in the attached figure. Figure 4 and attached Figure 5 .

[0096] Then, the mask layer is used as a mask to etch the thin film layer 130, thereby transferring the mask pattern in the mask layer to the thin film layer 130 to form the waveguide structure 160. The etching process can be dry etching or wet etching. For example, the waveguide structure 160 is transferred from the photoresist to the surface of the thin film layer 130 using inductively coupled plasma dry etching (ICP).

[0097] During the plasma dry etching process, the thin film layer 130 protected by the photoresist is not etched, while the thin film layer 130 exposed outside is etched to a certain depth, thereby forming the waveguide structure 160 .

[0098] It should be noted that during the waveguide formation process, metal electrodes can be fabricated on both sides of the ridged waveguide structure using a lift-off process. Au is used as the electrode material and is deposited by electron beam evaporation. The electrode thickness is 600 nm (a 15 nm Cr electrode is typically deposited below the Au electrode as an adhesion layer). The input and output ends of the electro-optic modulator also require end-face polishing and coating to improve the end-face coupling efficiency of the optical signal.

[0099] The electrodes may include a positive electrode 171, a negative electrode 172, a ground electrode 173, and a signal electrode 174. The positive electrode 171 and the negative electrode 172 are disposed in the lithium niobate thin film layer 131 and are located on either side of the waveguide structure 160 of the lithium niobate thin film layer 131. The ground electrode 173 and the signal electrode 174 are disposed in the doped lithium niobate thin film layer 132 and are located on either side of the waveguide structure 160 of the doped lithium niobate thin film layer 132. It should be understood that the performance of each electrode can be referenced in related art and will not be further described in this embodiment.

[0100] The present invention also provides a thin film structure 400 , which is manufactured by the manufacturing method described in any of the above embodiments. The thin film structure 400 includes a support structure 200 and a thin film layer 130 disposed on the support structure 200 .

[0101] The thin film layer 130 includes a lithium niobate thin film layer 131 and a doped lithium niobate thin film layer 132 arranged in parallel. The thin film layer also includes a waveguide structure 160, which spans the lithium niobate thin film layer 131 and the doped lithium niobate thin film layer 132. Specifically, one end of the waveguide structure 160 is located in the lithium niobate thin film layer 131, and the other end is located in the doped lithium niobate thin film layer 132. This arrangement allows the thin film structure's DC bias region to be located in the doped lithium niobate thin film layer 132, while the high-frequency modulation region is located in the lithium niobate thin film layer 131. This arrangement not only reduces the resistance of the resulting thin film structure by utilizing the doped lithium niobate, thus better suppressing drift, but also utilizes the high linear electro-optic coefficient of lithium niobate to improve the electro-optic modulation efficiency of the thin film structure, resulting in electronic devices with superior performance in areas such as photoelectric conversion and optical signal processing.

[0102] In the embodiment of the present application, the lithium niobate thin film layer 131 and the doped lithium niobate thin film layer 132 are arranged along a first direction. The first direction can be understood as a direction parallel to a horizontal plane, or in other words, the first direction can be any direction within the horizontal plane. For example, the first direction can be the X direction within the horizontal plane, or the Y direction within the horizontal plane, or can be at a certain angle to the X direction or the Y direction within the horizontal plane.

[0103] In this way, the arrangement direction of the lithium niobate thin film layer 131 and the doped lithium niobate thin film layer 132 can be reasonably set according to the performance requirements of the thin film structure, thereby improving the design flexibility of the thin film structure. In this embodiment, the shape of the support structure 200 is used as a reference to define and explain the first direction.

[0104] As a possible embodiment, the first direction is the length direction of the support structure 200, and the lithium niobate wafer 110 and the doped lithium niobate wafer 120 are arranged along the length direction of the support structure 200; and the dimensions of the lithium niobate thin film layer 131 and the doped lithium niobate thin film layer 132 in the second direction are equal to the width of the support structure 200, and the first direction and the second direction intersect. Figure 3 As an example, the first direction is the direction of Figure 3 The middle X direction, the second direction is the attached Figure 3 Center Y direction.

[0105] The width of the lithium niobate wafer 110 is equal to the width of the doped lithium niobate wafer 120 , and is also equal to the width of the support structure 200 .

[0106] In this way, the size of the bonding surface between the lithium niobate wafer 110 and the doped lithium niobate wafer 120 depends on the width of the support structure 200, the aspect ratio of the bonding interface is relatively small, and the bonding difficulty is low. This can improve the bonding quality of the lithium niobate wafer 110 and the doped lithium niobate wafer 120, thereby improving the quality of the prepared thin film structure.

[0107] As another possible embodiment, the first direction is the width direction of the support structure 200, the lithium niobate wafer 110 and the doped lithium niobate wafer 120 are arranged along the width direction of the support structure 200, and the dimensions of the lithium niobate thin film layer 131 and the doped lithium niobate thin film layer 132 in the second direction are equal to the length of the support structure 200; the first direction and the second direction intersect. Figure 4 As an example, the first direction is the direction of Figure 4 The middle Y direction, the second direction is the Figure 4 Middle X direction.

[0108] The length of the lithium niobate wafer 110 and the length of the doped lithium niobate wafer 120 are equal to the length of the support structure 200 , and the sum of the width of the lithium niobate wafer 110 and the width of the doped lithium niobate wafer 120 is equal to the width of the support structure 200 .

[0109] The length of the DC bias region can be very long, even comparable to the total length of the device. In this case, the DC bias voltage required to introduce a phase delay of π / 2 can be very low, thereby further suppressing DC drift.

[0110] One end of the waveguide structure of the thin film structure extends from one end of the doped lithium niobate wafer 120 to the other end of the doped lithium niobate wafer 120, then bends and extends to one end of the doped lithium niobate wafer 120, and finally extends along the length direction of the lithium niobate wafer 110 to the other end of the lithium niobate wafer 110. In this way, the waveguide structure of the thin film structure can present an S-shape or even a serpentine structure. In this way, the incident end and the output end of the optical signal can be designed on both sides of the electro-optical modulation chip, reducing the difficulty of device packaging.

[0111] The present application also provides an electronic device including the thin film structure described in any of the above embodiments, wherein the electronic device may be an electro-optical modulator.

[0112] Since the embodiments of the present application include the thin film structure of any of the above embodiments, the structure and beneficial effects of the electronic device including the thin film structure will not be further described in this embodiment.

[0113] The various embodiments or implementation methods in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments, and the same or similar parts between the various embodiments can be referenced to each other.

[0114] In the description of this specification, reference to terms such as "one embodiment", "some embodiments", "illustrative embodiment", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application.

[0115] In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any suitable manner in any one or more embodiments or examples.

[0116] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A thin film structure, characterized in that: include: A support structure and a film layer disposed on the support structure; The thin film layer includes a lithium niobate thin film layer and a doped lithium niobate thin film layer arranged in parallel, the lithium niobate thin film layer and the doped lithium niobate thin film layer are arranged along a first direction, and the DC bias region is located in the doped lithium niobate thin film layer, and the high-frequency modulation region is located in the lithium niobate thin film layer; The thin film layer further includes a waveguide structure, and the waveguide structure spans the lithium niobate thin film layer and the doped lithium niobate thin film layer.

2. The thin film structure according to claim 1, characterized in that The support structure is a strip structure; the first direction is the length direction of the support structure, and the dimensions of the lithium niobate thin film layer and the doped lithium niobate thin film layer in the second direction are equal to the width of the support structure; Alternatively, the first direction is the width direction of the support structure, and the dimensions of the lithium niobate thin film layer and the doped lithium niobate thin film layer in the second direction are equal to the length of the support structure; The first direction intersects with the second direction.

3. A method for preparing a thin film structure, characterized in that: include: Providing a lithium niobate wafer and a doped lithium niobate wafer arranged side by side along a first direction; Bonding the lithium niobate wafer and the doped lithium niobate wafer in parallel to form a bonding structure; wherein the top surface of the lithium niobate wafer is flush with the top surface of the doped lithium niobate wafer; performing an ion implantation process on the bonding structure so that the bonding structure forms a thin film layer, an implantation layer and a residual layer that are stacked; Bonding the thin film layer of the bonding structure after the ion implantation process to a support structure, and removing the implantation layer and the residual layer to form a bonded body; wherein the thin film layer includes a lithium niobate thin film layer and a doped lithium niobate thin film layer arranged in parallel, and the DC bias region is located in the doped lithium niobate thin film layer, and the high-frequency modulation region is located in the lithium niobate thin film layer; The thin film layer of the bonded body is patterned to form a waveguide structure in the thin film layer, wherein the waveguide structure spans the lithium niobate thin film layer and the doped lithium niobate thin film layer.

4. The method for preparing a thin film structure according to claim 3, wherein: The lithium niobate wafer has a first bonding surface, and the doped lithium niobate wafer has a second bonding surface; After the step of providing the lithium niobate wafer and the doped lithium niobate wafer arranged in parallel, and before the step of performing an ion implantation process on the bonded structure, the method further includes: The first bonding surface and the second bonding surface are respectively activated to improve the activities of the first bonding surface and the second bonding surface.

5. The method for preparing a thin film structure according to claim 3, wherein: The supporting structure is a strip structure; The first direction is the length direction of the supporting structure; or, the first direction is the width direction of the supporting structure.

6. The method for preparing a thin film structure according to any one of claims 3 to 5, characterized in that: Before the step of bonding the thin film layer of the bonding structure after ion treatment to the support structure, the method further includes: providing a substrate; A capture layer and an isolation layer are stacked on the substrate. The capture layer and the isolation layer are made of different materials, and the capture layer has a thickness of 300 nm to 5000 nm.

7. The method for preparing a thin film structure according to claim 6, wherein: The step of bonding the thin film layer of the bonding structure after ion treatment to the support structure further comprises: At least one heat treatment process is performed on the bonded bonding structure and the supporting structure to peel off the implantation layer and the residual layer of the bonding structure.

8. The method for preparing a thin film structure according to claim 7, wherein: Performing a first heat treatment process on the bonded bonding structure and the supporting structure to peel off the injection layer and the residual layer; wherein the temperature of the first heat treatment process is 100° C. to 600° C., and the heat treatment time is 1 minute to 48 hours; A second heat treatment process is performed on the peeled bonding structure and the supporting structure, wherein the temperature of the second heat treatment process is 300° C. to 600° C., and the heat treatment time is 1 minute to 100 hours.

9. An electronic device, characterized in that: The invention comprises the film structure according to claim 1 or 2.

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