CN114214732B

CN114214732B - Method for improving polarization reversal phenomenon on surface of composite film and composite film

Info

Publication number: CN114214732B
Application number: CN202210159139.5A
Authority: CN
Inventors: 郑姗姗; 胡卉; 胡文; 李真宇; 刘桂银; 刘金鹏
Original assignee: Jinan Jingzheng Electronics Co Ltd
Current assignee: Jinan Jingzheng Electronics Co Ltd
Priority date: 2022-02-22
Filing date: 2022-02-22
Publication date: 2022-04-29
Anticipated expiration: 2042-02-22
Also published as: CN114214732A

Abstract

The application discloses a method for improving the polarization reversal phenomenon of the surface of a composite film and the composite film, which belong to the field of semiconductor preparation, wherein the method utilizes an ion implantation-bonding method or a bonding-thinning method to prepare the composite film, and comprises the steps of preparing a bonding body and carrying out heat treatment on the bonding body; and irradiating the surface of the ferroelectric wafer by a UV ultraviolet lamp in the process of thermally treating the bonding body. The UV ultraviolet lamp can provide necessary photon-generated carriers for the bonding body, so that the conductivity of the bonding body is improved, sufficient ultraviolet irradiation can effectively conduct away charges accumulated in the bonding body in the heat treatment process, the polarization reversal phenomenon is prevented, and the prepared composite film has good piezoelectric property, pyroelectric property and electrooptical modulation efficiency.

Description

Method for improving polarization reversal phenomenon on surface of composite film and composite film

Technical Field

The application belongs to the field of semiconductor preparation, and particularly relates to a method for improving the surface polarization reversal phenomenon of a composite film and the composite film.

Background

Lithium niobate and lithium tantalate crystals have been widely used in various core electronic devices such as surface acoustic wave devices, film bulk acoustic resonators, photoelectric sensors, ferroelectric memories, and the like, due to their excellent optical properties such as piezoelectricity, ferroelectricity, photoelectricity, photoelastic, pyroelectric, photorefractive, nonlinearity, and the like.

Because the lithium niobate and lithium tantalate crystals are ferroelectric crystals, the lithium niobate and lithium tantalate crystals have spontaneous polarization, and the direction of the electric dipole moment can be changed under the action of an external electric field, so that a polarization reversal phenomenon is presented.

Taking lithium niobate as an example, the lithium niobate is grown under a high temperature condition. During its growth there is a paraelectric phase as shown in fig. 1 (a), and when it is cooled below the phase transition temperature, i.e. the curie temperature, the crystal structure changes from the paraelectric phase shown in fig. 1 (a) to the ferroelectric phase shown in fig. 1 (b). As shown in fig. 1 (a), in the paraelectric phase, Li and Nb are located at the oxygen plane and the center of the oxygen octahedron, respectively, and have no spontaneous polarization; as shown in fig. 1 (b), in the ferroelectric phase, electric dipole moments along the Z-axis, i.e., a spontaneous polarization phenomenon occurs in both Li and Nb, and a spontaneous polarization vector Ps is along the Z-axis.

From this fact, it is found that the lithium niobate crystal obtained by the Z-direction slicing (hereinafter, simply referred to as Z-tangential lithium niobate crystal) has a phenomenon in which spontaneous polarization occurs and polarization reversal can occur by the action of an external electric field. In addition, the Z-tangential lithium niobate crystal not only has the spontaneous polarization and polarization reversal phenomena, but also has optical properties such as piezoelectricity, photoelectricity, photoelastic, pyroelectric, photorefractive, nonlinearity and the like. Therefore, Z-tangential lithium niobate wafers and Z-tangential lithium tantalate wafers are common base materials used in the art for preparing composite films.

When the Z-tangential lithium niobate wafer is used for preparing the composite film, if heat treatment exists in the preparation process, when the temperature is changed rapidly, the Z-tangential lithium niobate wafer has a pyroelectric effect, so that charges can be formed on the surface of the Z-tangential lithium niobate wafer; and because the substrate base plate in the composite film has low conductivity, formed charges are accumulated between the substrate base plate and the Z-tangential lithium niobate wafer, and an electric field is further formed. Thus, the spontaneous polarization vector Ps of the Z-tangential lithium niobate wafer can be subjected to polarization reversal under the action of the electric field, and finally the Z-tangential lithium niobate wafer forms a polarization defect in the preparation process of the composite film, particularly, a plurality of polarization spots are shown on the surface of the Z-tangential lithium niobate wafer, the polarization spots may not affect the ferroelectric property of the composite film, but the piezoelectric property, the pyroelectric property and the electro-optic modulation efficiency of the composite film are reduced, so that if the composite film is applied to the piezoelectric property, the pyroelectric property and the electro-optic modulation direction, the corresponding performance requirements are difficult to meet.

Therefore, how to solve the defect of polarization reversal formed by lithium niobate and lithium tantalate in the process of preparing the piezoelectric substrate is a technical problem which needs to be solved urgently at present.

Disclosure of Invention

In order to solve the above technical problems, the present application provides a method for improving the phenomenon of polarization reversal on the surface of a composite film and a composite film.

In a first aspect, the present application provides a method for improving a phenomenon of polarization reversal on a surface of a composite film, including:

preparing a ferroelectric wafer and a substrate, wherein the ferroelectric wafer is a Z-tangential non-component lithium niobate wafer or a Z-tangential non-component lithium tantalate wafer, or the ferroelectric wafer is a Z-tangential component lithium niobate wafer or a Z-tangential component lithium tantalate wafer;

preparing a composite film by using an ion implantation-bonding method or a bonding-thinning method, wherein the method comprises the steps of preparing a bonded body and carrying out heat treatment on the bonded body;

and irradiating the surface of the ferroelectric wafer by a UV ultraviolet lamp in the process of thermally treating the bonding body.

In one implementation mode, the wavelength of the UV ultraviolet lamp is 310-400 nm.

In one implementation, the time for irradiating the surface of the ferroelectric wafer by the UV lamp does not exceed the time for the heat treatment.

In one implementation mode, the temperature of the heat treatment is 100-600 ℃, and the time of the heat treatment is 1 minute-48 hours.

In one implementation, the preparing the composite thin film by using the ion implantation-bonding method includes:

implanting ions into the ferroelectric wafer through an ion implantation method, and sequentially dividing the ferroelectric wafer into a residual layer, a separation layer and a thin film layer;

bonding the ferroelectric wafer and the substrate to obtain a bonded body;

and carrying out heat treatment on the bonding body to separate the residual layer from the thin film layer.

In one implementation manner, the preparing the composite film by using the bonding-thinning method includes:

bonding the ferroelectric wafer and the substrate to obtain a bonded body;

carrying out heat treatment on the bonding body to obtain a composite film prefabricated body;

and thinning the ferroelectric wafer in the composite film prefabricated body, and forming a film layer with a target thickness on the substrate base plate.

In one implementation, the method further comprises:

and preparing an isolation layer between the ferroelectric wafer and the substrate, wherein the isolation layer is made of silicon dioxide, silicon oxynitride or silicon nitride.

In one implementation manner, the substrate base plate is made of lithium niobate, lithium tantalate, a silicon wafer, a silicon carbide wafer, silicon nitride, quartz, sapphire or quartz glass.

In a second aspect, the present application provides a composite film prepared by the method for improving the phenomenon of polarization reversal on the surface of the composite film according to any of the first aspect.

In a third aspect, the present application provides an electronic component comprising the composite film of the second aspect.

According to the method for improving the polarization reversal phenomenon on the surface of the composite film, in the heat treatment step, the surface of the ferroelectric wafer is irradiated by the UV ultraviolet lamp, and the UV ultraviolet lamp can provide necessary photon-generated carriers for the bonding body, so that the conductivity of the bonding body is improved.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and those skilled in the art can also obtain other drawings according to the drawings without creative efforts.

FIG. 1 is a schematic diagram of the structure of a lithium niobate crystal;

FIG. 2A is a flowchart of a method for improving polarization reversal phenomenon on a surface of a composite film according to an embodiment of the present disclosure;

FIG. 2B is a flowchart of another method for improving the polarization reversal phenomenon on the surface of the composite thin film according to an embodiment of the present disclosure;

fig. 3A is a schematic structural diagram of a Z-tangential non-component lithium niobate wafer according to an embodiment of the present application;

fig. 3B is a schematic structural diagram of a Z-direction fractional lithium niobate wafer according to an embodiment of the present application;

FIG. 4 is a flowchart of another method for improving the polarization reversal phenomenon on the surface of the composite thin film according to an embodiment of the present disclosure;

FIG. 5A is an electron microscope image of a lithium niobate thin film in a composite thin film prepared by the method provided in the embodiment of the present application;

FIG. 5B is an electron microscope photograph of a lithium niobate thin film in a composite thin film prepared without irradiation of a UV ultraviolet lamp;

FIG. 6 is a graph showing the test results of the PFM test performed on the M region of FIG. 5B;

FIG. 7 is a graph showing the results of PFM testing of the N region of FIG. 5B.

Description of the reference numerals

100-ferroelectric wafer, 200-substrate, 300-bonding body, 400-UV ultraviolet lamp, 110-residual layer, 120-separation layer and 130-thin film layer.

Detailed Description

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

For the purpose of facilitating understanding of the technical solutions provided in the present application, the following technical terms of paraelectric phase, ferroelectric phase, spontaneous polarization, polarization inversion, and the like will be first described.

Lithium niobate and lithium tantalate are ferroelectric crystals, which are grown under high temperature conditions. During their growth there is a paraelectric phase as shown in fig. 1 (a), and when they are cooled below the phase transition temperature, i.e. the curie temperature, the crystal structure changes from the paraelectric phase shown in fig. 1 (a) to the ferroelectric phase shown in fig. 1 (b). Wherein the horizontal line in fig. 1 represents an oxygen plane.

Taking lithium niobate as an example, in a paraelectric phase, Li and Nb are respectively positioned in an oxygen plane and an oxygen octahedron center, and spontaneous polarization is avoided; in the ferroelectric phase, electric dipole moment along the Z axis occurs in Li and Nb, namely, spontaneous polarization phenomenon occurs, and the spontaneous polarization vector Ps is along the Z axis direction.

Lithium niobate and lithium tantalate crystal crystals are not only capable of spontaneous polarization, but also the direction of the electric dipole moment can be changed under the action of an external electric field, and this phenomenon is generally referred to as polarization reversal. From this, it is known that the Z-tangential lithium niobate wafer and the Z-tangential lithium tantalate wafer have spontaneous polarization and can exhibit a phenomenon of polarization reversal under the action of an external electric field.

In addition, the Z-tangential lithium niobate wafer and the Z-tangential lithium tantalate wafer not only have the spontaneous polarization and polarization reversal phenomena, but also have optical properties such as piezoelectricity, photoelectricity, photoelastic, pyroelectricity, photorefractive and nonlinearity. Therefore, Z-tangential lithium niobate wafers and Z-tangential lithium tantalate wafers are common base materials used in the art for preparing composite films.

When the Z-tangential lithium niobate wafer is used for preparing the composite film, if a heat treatment step exists in the preparation process, when the temperature is changed rapidly, the Z-tangential lithium niobate wafer has a pyroelectric effect, so that charges can be formed on the surface of the Z-tangential lithium niobate wafer; and because the substrate base plate in the composite film has low conductivity, formed charges are accumulated between the substrate base plate and the Z-tangential lithium niobate wafer, and an electric field is further formed. Thus, the spontaneous polarization vector Ps of the Z-tangential lithium niobate wafer can be subjected to polarization reversal under the action of the electric field, so that the Z-tangential lithium niobate wafer forms a polarization defect in the preparation process of the composite film, and particularly, a plurality of polarization spots are shown on the surface of the Z-tangential lithium niobate wafer, and the polarization spots may not affect the ferroelectric property of the composite film, but can cause the piezoelectric property, the pyroelectric property and the electro-optic modulation efficiency of the prepared composite film to be reduced, so that if the composite film is applied to the piezoelectric property, the pyroelectric property and the electro-optic modulation direction, the corresponding performance requirements are difficult to meet.

In order to solve the problem that polarization reversal occurs in the process of preparing the composite film by adopting the Z-tangential lithium niobate wafer or the Z-tangential lithium tantalate wafer, the embodiment of the application provides a method for improving the polarization reversal phenomenon on the surface of the composite film, and the method can reduce the polarization reversal phenomenon in the preparation process, even eliminate the polarization reversal phenomenon in the preparation process, so that the prepared composite film has good piezoelectric property, pyroelectric property and electro-optic modulation efficiency.

The following describes in detail a method for improving the phenomenon of polarization reversal on the surface of a composite film according to an embodiment of the present application with reference to the drawings.

As shown in fig. 2A, a method for improving a phenomenon of polarization reversal on a surface of a composite film according to an embodiment of the present application includes the following steps:

step S100, preparing a ferroelectric wafer 100 and a substrate base plate 200, wherein the ferroelectric wafer 100 is a Z-tangential non-component lithium niobate wafer or a Z-tangential non-component lithium tantalate wafer, or the ferroelectric wafer is a Z-tangential component lithium niobate wafer or a Z-tangential component lithium tantalate wafer.

In the embodiment of the present application, the ferroelectric wafer 100 is a base material having a certain thickness for preparing a thin film layer.

As shown in fig. 3A, the Z-tangential non-component lithium niobate wafer and the Z-tangential non-component lithium tantalate wafer mean that when the crystal pillar is cut into a wafer, a normal direction of a cutting plane perpendicular to the Z-axis has no projection component on the Z-axis.

As shown in fig. 3B, the Z-direction component lithium niobate wafer and the Z-direction component lithium tantalate wafer mean that when the crystal pillar is cut into a wafer, a projection component is present in the Z-direction in a direction perpendicular to a normal line of a cutting plane of the Z-axis.

As is apparent from the above description of the ferroelectric crystal, as long as the ferroelectric wafer includes a cut surface in the Z-tangential direction, i.e., perpendicular to the Z-axis, there is a phenomenon of polarization inversion.

In the embodiment of the present application, the substrate base 200 may be a single-layer substrate or a composite substrate, that is, the substrate base 200 includes at least one substrate layer. The material of each substrate layer may be the same or different, and the present application does not limit this. For example: the substrate layer material may be lithium niobate, lithium tantalate, a silicon wafer, a silicon carbide wafer, silicon nitride, quartz, sapphire, quartz glass, or the like, which is not limited in the present application.

And S200, preparing the composite film by using an ion implantation-bonding method or a bonding-thinning method.

The process of preparing the composite film by using either the ion implantation-bonding method or the bonding-thinning method includes the steps of forming a bonded body 300, and performing heat treatment on the bonded body 300, wherein the bonded body 300 includes the ferroelectric wafer 100 and the substrate 200 which are sequentially stacked.

The following describes methods for producing a composite film by using an ion implantation-bonding method and a bonding-thinning method, respectively.

As shown in fig. 2B, the method for preparing the composite film by using the ion implantation-bonding method includes the following steps:

step S210, implanting ions into the ferroelectric wafer 100 by ion implantation, and sequentially dividing the ferroelectric wafer 100 into the residual layer 110, the separation layer 120, and the thin film layer 130.

The ion implantation method in the embodiments of the present application is not particularly limited, and any ion implantation method in the prior art may be used, and the implanted ions may be ions that can generate gas by heat treatment, for example: the implanted ions may be hydrogen ions, helium ions, nitrogen ions, oxygen ions, or argon ions. When implanting ions, the implantation dose can be 2 × 10¹⁶ions/cm²~4×10¹⁶ions/cm²The implantation energy may be 40KeV to 400KeV, for example, 50 KeV.

In the embodiment of the present application, the thickness of the thin film layer 130 may be adjusted by adjusting the ion implantation depth, specifically, the greater the ion implantation depth, the greater the thickness of the prepared thin film layer 130; conversely, the smaller the depth of ion implantation, the smaller the thickness of the thin film layer 130 is produced.

Step S220, bonding the ferroelectric wafer 100 and the substrate 200 to obtain a bonded body 300.

After bonding, the thin film layer 130 of the ferroelectric wafer 100 is in contact with the substrate 200 and stacked on the substrate 200, such that the bonded body 300 has the remainder layer 110, the separation layer 120, the thin film layer 130, and the substrate 200 stacked in this order from top to bottom.

The bonding method is not particularly limited in the present application, and any bonding method in the prior art, for example, surface activation bonding, may be used to obtain a bonded body. The surface activation method is not limited in the present application, and for example, plasma activation or chemical solution activation may be used.

It should be noted that, the present application may further include a step of preparing an isolation layer on the base substrate 200 before step S200, so that in step S200, the ferroelectric wafer 100 is bonded to the base substrate 200 with the isolation layer to obtain a bonded body.

The material of the isolation layer is not limited in this application, and for example, the material of the isolation layer may be silicon dioxide, silicon oxynitride, or silicon nitride. The method for preparing the isolation layer is not limited, and Chemical Vapor Deposition (CVD), Physical Vapor Deposition (PVD), magnetron sputtering and other deposition methods can be adopted, and a thermal oxidation method can also be adopted. For example, the base substrate 200 is a single-layer silicon substrate on which silicon dioxide is prepared by a thermal oxidation method, and the resulting silicon dioxide layer serves as an isolation layer.

It should be noted that the isolation layer prepared on the base substrate 200 may be a single layer or a plurality of layers, which is not limited in this application. For example, silicon oxide layers and silicon nitride layers are alternately stacked on the base substrate 200.

It should be noted that, before the step of preparing the isolation layer, a step of preparing a dielectric layer may be further included, for example, polysilicon or amorphous silicon may be deposited on the surface of the substrate 200 by a deposition method; or an etching damage layer is generated on the surface of the base substrate 200 by an etching method.

Step S230, performing heat treatment on the bonded body 300, and separating the residual layer 110 from the thin film layer 130 to obtain a composite thin film, wherein in the process of performing heat treatment on the bonded body 300, the surface of the ferroelectric wafer 100 is irradiated by the UV ultraviolet lamp 400.

And (2) performing heat treatment on the bonded body 300, wherein the heat treatment temperature can be 100-600 ℃, the heat treatment time can be 1 minute-48 hours, bubbles are formed in the separation layer 120 in the heat treatment process, for example, H ions form hydrogen, He ions form helium and the like, the bubbles in the separation layer 120 are connected into a piece along with the progress of the heat treatment, finally, the separation layer 120 is cracked, and the residual layer 110 is separated from the thin film layer 130, so that the residual layer 110 is stripped from the bonded body 300, and a composite film is obtained, wherein the thin film layer 130 and the substrate 200 are sequentially laminated from top to bottom.

Since the substrate 200 in the bonded body 300 has low conductivity, when the temperature is abruptly changed by heat treatment, charges are generated and accumulated in the vicinity of the bonding surface between the ferroelectric wafer 100 and the substrate 200, and an electric field is formed. And because the ferroelectric wafer 100 has spontaneous polarization and can have polarization reversal under the action of an external electric field, the ferroelectric wafer 100 has polarization reversal under the action of an electric field formed near the bonding surface of the ferroelectric wafer 100 and the substrate 200, thereby affecting the piezoelectric property, pyroelectric property and electro-optic modulation efficiency of the prepared composite film.

Therefore, the present application irradiates the surface of the ferroelectric wafer 100 with a UV lamp during the heat treatment of the bond 300. The UV lamp can provide necessary photogenerated carriers for the bonding body 300, so as to improve the conductivity of the bonding body 300, and thus, during the heat treatment process, sufficient UV light irradiation can effectively conduct away charges accumulated in the bonding body 300, thereby preventing the polarization reversal phenomenon.

It should be noted that the electric charges are mainly accumulated near the bonding surface of the ferroelectric wafer 100 and the substrate 200, and therefore, a UV lamp is required to irradiate the bonding surface of the ferroelectric wafer 100 and the substrate 200. Generally, the light transmission range of the Z-tangential lithium niobate wafer and the Z-tangential lithium tantalate wafer is generally 300-5000 nm, so that theoretically, visible light, infrared light and UV ultraviolet lamps can be adopted to irradiate the bonding surface of the ferroelectric wafer 100 and the substrate 200; however, experiments prove that visible light and infrared light are not enough to generate photo-generated carriers at the bonding interface, and only ultraviolet light with shorter wavelength, higher frequency and larger energy can transmit the ferroelectric wafer 100 and reach the bonding surface of the ferroelectric wafer 100 and the substrate 200 to generate photo-generated carriers. Wherein, the wavelength of the UV ultraviolet lamp is preferably 310-400 nm.

It should be noted that the irradiation time of the UV lamp to the surface of the ferroelectric wafer generally does not exceed the time of the thermal treatment, so as to avoid wasting resources.

As shown in fig. 4, the bonding-thinning method is adopted, and the method for preparing the composite film comprises the following steps:

step S310, bonding the ferroelectric wafer 100 and the substrate 200 to obtain a bonded body 300.

In the bonding-thinning method, the ferroelectric wafer 100 and the substrate base plate 200 are directly bonded, and for the method for bonding the ferroelectric wafer 100 and the substrate base plate 200, reference may be made to the description of step S220, which is not described herein again.

Step S320, performing heat treatment on the bonded body 300 to obtain a composite film pre-prepared body, wherein in the process of performing heat treatment on the bonded body 300, the surface of the ferroelectric wafer 100 is irradiated by a UV ultraviolet lamp.

In the bonding-thinning method, the purpose of the heat treatment on the bonded body 300 is to enhance the bonding force between the ferroelectric wafer and the substrate, and the present application does not limit the heat treatment process conditions in step S320, for example, the heat treatment temperature may be 100 ℃ to 600 ℃, and the heat treatment time may be 1 minute to 48 hours.

In the heat treatment process, the method of irradiating the surface of the ferroelectric wafer 100 with the UV lamp may refer to the description of step S230, and will not be described herein again.

And S330, thinning the ferroelectric wafer in the composite film prefabricated body, and forming a film layer with a target thickness on the substrate base plate.

The specific thinning method used in the present application is not limited, and may be, for example, grinding, polishing, thinning, or mechanical cutting and thinning. And thinning the ferroelectric wafer in the composite film prefabricated body until a film layer with a target thickness is formed on the substrate, wherein the film layer is made of the same material as the ferroelectric wafer and has a thickness far smaller than that of the ferroelectric wafer before grinding and polishing.

Please refer to fig. 5A and 5B, wherein fig. 5A is an electron microscope image of a lithium niobate thin film in a composite thin film prepared by a method provided in an embodiment of the present application, and fig. 5B is an electron microscope image of a lithium niobate thin film in a composite thin film prepared without UV lamp irradiation.

As can be seen from a comparison of FIGS. 5A and 5B, there are many white spots distributed on the surface of the film in FIG. 5B, and no white spots are shown in FIG. 5A. These white spots are referred to as polarization spots, and are polarization defects formed due to polarization reversal of the ferroelectric wafer 100 during the heat treatment process, that is, the white spots in fig. 5B are defect regions, and the other regions are non-defect regions; in fig. 5A, the non-defective regions are all absent. Therefore, the method for preparing the composite film obviously improves the polarization reversal phenomenon.

To demonstrate that the white spots in fig. 5A are due to polarization defects formed by polarization reversal, the present application further performed piezoelectric force microscope (also referred to as PFM) tests on the M-region and N-region, respectively, in fig. 5B.

Please refer to fig. 6 and fig. 7, wherein fig. 6 is a schematic diagram illustrating the result of the piezoelectric force microscope (also referred to as PFM) test performed on the M region in fig. 5B, and fig. 7 is a schematic diagram illustrating the result of the piezoelectric force microscope (also referred to as PFM) test performed on the N region in fig. 5B. Wherein, (a) in fig. 6 and (a) in fig. 7 are topographic maps by PFM test, (b) in fig. 6 and (b) in fig. 7 are graphs showing amplitude results by PFM test, and (c) in fig. 6 and (c) in fig. 7 are graphs showing phase results by PFM test.

As is apparent from (b), (c) in fig. 6 and (b), (c) in fig. 7, the defective region and the non-defective region are not on the same plane, and thus, the defective region appears as a pit defect; from the phase result diagram, it can also be seen that the polarity directions of the defective region and the non-defective region are just different by 180 °, which also proves that the white spot in fig. 5A is a polarization defect due to polarization inversion.

As is apparent from (a) in fig. 6 and (a) in fig. 7, if the ferroelectric wafer is not irradiated by the UV ultraviolet lamp during the heat treatment step for preparing the composite thin film, the surface of the thin film layer in the finally prepared composite thin film may be significantly damaged, which may seriously affect the piezoelectric property, pyroelectric property, electro-optic modulation efficiency, and other properties of the composite thin film.

In summary, in the method for improving the polarization reversal phenomenon on the surface of the composite film provided by the embodiment of the present application, in the heat treatment step, the UV ultraviolet lamp irradiates the surface of the ferroelectric wafer, and the UV ultraviolet lamp can provide necessary photogenerated carriers for the bonding body 300, so as to improve the conductivity of the bonding body 300, and thus, sufficient ultraviolet irradiation can effectively guide away charges accumulated in the bonding body 300 during the heat treatment process, and the polarization reversal phenomenon is prevented from occurring.

The application also provides a composite film, and the composite film is prepared by the method for improving the polarization reversal phenomenon on the surface of the composite film.

In one implementation, the present application provides a composite film, which includes a film layer and a substrate base plate stacked in sequence, wherein the substrate base plate may be a single-layer substrate or a composite substrate.

In yet another implementation, the present application provides a composite film including a thin film layer, an isolation layer, and a base substrate, which are sequentially stacked.

In yet another implementation, the present application provides a composite film including a thin film layer, an isolation layer, a dielectric layer, and a substrate base plate, which are sequentially stacked.

The application also provides an electronic component, and the electronic component adopts the composite film provided by the embodiment of the application. The thin film layer in the composite film provided by the embodiment of the application has good ferroelectricity, piezoelectricity, good pyroelectric property and electro-optic modulation efficiency. Thus, the electronic component may be a filter, a detector, a modulator, a ferroelectric memory, or the like.

Example one

Example one provides a method for improving a polarization reversal phenomenon on a surface of a composite film, comprising the following steps:

preparing a 4-inch silicon wafer and a Z-tangential lithium niobate wafer (hereinafter referred to as lithium niobate wafer), respectively fixing the silicon wafer or the lithium niobate wafer on a porous ceramic sucker of polishing equipment, carrying out chemical mechanical polishing treatment to obtain a smooth surface, and then carrying out semiconductor RCA cleaning on the two wafers to obtain a clean surface.

Secondly, injecting He into the lithium niobate wafer processed in the step one by adopting a stripping ion implantation method⁺The lithium niobate wafer is divided into a residual layer, a separation layer and a thin film layer in this order from the implantation surface, and He is implanted⁺And distributing the lithium niobate crystal particles on the separation layer to obtain the lithium niobate crystal wafer injection sheet.

Implanting He by lift-off ion implantation⁺The implantation dose parameters were: the implantation dose is 2 × 10¹⁶ions/cm²The implantation energy is 40keV and the implantation depth is 220 nm.

Thirdly, a silicon dioxide layer is manufactured on the cleaned silicon wafer by an LPCVD method, then, the silicon dioxide layer is chemically and mechanically polished to the thickness of 100nm, a smooth surface is obtained, and a clean surface is obtained by RCA cleaning.

And fourthly, contacting the lithium niobate wafer injection sheet with the silicon dioxide layer, and bonding by adopting a direct bonding method to obtain a bonded body.

And fifthly, placing the bonding body on a hot table in a nitrogen atmosphere, irradiating by a UV ultraviolet lamp with the wavelength of 363nm, annealing the bonding body at 180 ℃ for 4 hours, irradiating by the UV ultraviolet lamp for 4 hours, and separating the bonding body at the separation layer to obtain the composite film.

Sixthly, fixing the composite film on a porous ceramic sucker of polishing equipment, performing chemical mechanical polishing treatment on the film layer, and then performing RCA cleaning to obtain a clean surface.

Example two

The second embodiment provides a method for improving the polarization reversal phenomenon on the surface of the composite film, which comprises the following steps:

firstly, preparing a 6-inch silicon nitride wafer and a Z-tangential lithium niobate wafer (hereinafter referred to as lithium niobate wafer), respectively fixing the silicon nitride wafer or the lithium niobate wafer on a porous ceramic sucker of polishing equipment, carrying out chemical mechanical polishing treatment to obtain a smooth surface, and then carrying out semiconductor RCA cleaning on the two wafers to obtain a clean surface.

And secondly, implanting argon ions into the lithium niobate wafer processed in the step one by adopting a stripping ion implantation method, so that the lithium niobate wafer is sequentially divided into a residual layer, a separation layer and a thin film layer from an implantation surface, and the implanted argon ions are distributed in the separation layer to obtain a lithium niobate wafer implantation piece.

When argon ions are implanted by adopting a stripping ion implantation method, the implantation dosage parameters are as follows: the implantation dose is 3 × 10¹⁶ions/cm²The implantation energy was 400keV and the implantation depth was 285 nm.

Thirdly, polysilicon is manufactured on the cleaned silicon nitride wafer by an LPCVD method, and the thickness of the polysilicon is 1 mu m, namely the first isolating layer.

Fourthly, silicon nitride is manufactured on the first isolation layer by a thermal oxidation method, namely the second isolation layer, then chemical mechanical polishing is carried out to obtain a smooth surface, the thickness of the second isolation layer is 1 mu m, and the RCA cleaning is carried out to obtain a clean surface.

And fifthly, enabling the lithium niobate wafer to be in contact with the silicon nitride layer, and bonding by adopting a direct bonding method to obtain a bonded body.

Sixthly, placing the bonding body on a hot table, irradiating by a UV ultraviolet lamp with the wavelength of 400nm, annealing the bonding body at 200 ℃ for 3 hours, irradiating by the UV ultraviolet lamp for 3 hours, and separating the bonding body in a separation layer to obtain the composite film.

And seventhly, fixing the composite film on a porous ceramic sucker of polishing equipment, performing chemical mechanical polishing treatment on the film layer, and then performing RCA cleaning to obtain a clean surface.

Example three

The third embodiment provides a method for improving the polarization reversal phenomenon on the surface of the composite film, which comprises the following steps:

preparing a 3-inch silicon wafer and a Z-tangential lithium tantalate wafer (hereinafter referred to as lithium tantalate wafer), respectively fixing the silicon wafer or the lithium tantalate wafer on a porous ceramic sucker of polishing equipment, carrying out chemical mechanical polishing treatment to obtain a smooth surface, and then carrying out semiconductor RCA cleaning on the two wafers to obtain a clean surface.

Secondly, injecting He into the lithium tantalate wafer processed in the step one by adopting a stripping ion implantation method⁺Separating the lithium tantalate wafer into a residual layer, a separation layer and a thin film layer in this order from the implantation surface, and implanting He⁺Distributing ions in the separation layer to obtain a lithium tantalate wafer injection sheet;

implanting He by lift-off ion implantation⁺The implantation dose parameters were: the implantation dose is 4X 10¹⁶ions/cm²(ii) a The implantation energy is 225keV, and the implantation depth is 706 nm;

and thirdly, manufacturing amorphous silicon on the cleaned silicon wafer by using a PVD method, wherein the thickness of the amorphous silicon is 500nm, and the amorphous silicon is the first isolating layer.

And fourthly, preparing a silicon dioxide layer on the first isolation layer by a PECVD method, wherein the thickness of the silicon dioxide layer is 5 mu m, namely a second isolation layer, then carrying out chemical mechanical polishing to obtain a smooth surface, and carrying out RCA cleaning to obtain a clean surface.

And fifthly, injecting the lithium tantalate wafer into the wafer to be in contact with the silicon dioxide layer, and bonding by adopting a direct bonding method to obtain a bonded body.

Sixthly, placing the bonding body on a hot table, irradiating by a UV ultraviolet lamp with the wavelength of 310nm, annealing the bonding body at 220 ℃ for 3 hours, irradiating by the UV ultraviolet lamp for 3 hours, and separating the bonding body on a separation layer to obtain the composite film.

Example four

Example four provides a method for improving the phenomenon of polarization reversal on the surface of a composite film, comprising the following steps:

firstly, preparing a 6-inch silicon carbide wafer and a Z-tangential lithium niobate wafer (hereinafter referred to as lithium niobate wafer), respectively fixing the silicon carbide wafer or the lithium niobate wafer on a porous ceramic sucker of polishing equipment, carrying out chemical mechanical polishing treatment to obtain a smooth surface, and then carrying out semiconductor RCA cleaning on the two wafers to obtain a clean surface.

Implanting He by lift-off ion implantation⁺The implantation dose parameters were: the implantation dose is 3 × 10¹⁶ions/cm²The implantation energy was 35keV and the implantation depth was 165 nm.

And thirdly, injecting argon ions into the cleaned silicon carbide wafer by an ion injection method to manufacture a damaged layer of the monocrystalline silicon, namely the first isolation layer, wherein the thickness of the first isolation layer is 5 microns.

And fourthly, preparing a silicon dioxide layer on the first isolation layer by using a PECVD method, namely a second isolation layer, then carrying out chemical mechanical polishing to obtain a smooth surface, wherein the thickness of the second isolation layer is 500nm, and carrying out RCA cleaning to obtain a clean surface.

And fifthly, injecting the lithium niobate wafer into the wafer to be contacted with the silicon dioxide layer, and bonding by adopting a direct bonding method to obtain a bonded body.

Placing the bonding body on a hot table, irradiating by a UV ultraviolet lamp with the wavelength of 363nm, annealing the bonding body at 240 ℃ for 2 hours, irradiating by the UV ultraviolet lamp for 2 hours, and separating the bonding body on a separation layer to obtain a composite film;

Example five

Example five provides a method for improving the phenomenon of polarization reversal on the surface of a composite film, comprising the following steps:

preparing a 3-inch silicon carbide wafer and a Z-tangential lithium niobate wafer (hereinafter referred to as lithium niobate wafer), respectively fixing the silicon carbide wafer or the lithium niobate wafer on a porous ceramic sucker of polishing equipment, carrying out chemical mechanical polishing treatment to obtain a smooth surface, and then carrying out semiconductor RCA cleaning on the two wafers to obtain a clean surface.

Implanting He by lift-off ion implantation⁺The implantation dose parameters were: the implantation dose is 3 × 10¹⁶ions/cm²The implantation energy was 400keV and the implantation depth was 1.14 μm.

Sixthly, placing the bonding body on a hot table, irradiating by a UV ultraviolet lamp with the wavelength of 363nm, annealing the bonding body at 100 ℃ for 48 hours, irradiating by the UV ultraviolet lamp for 48 hours, and separating the bonding body on a separation layer to obtain the composite film.

Example six

Example six provides a method for improving a phenomenon of polarization reversal on a surface of a composite film, comprising the following steps:

preparing a 4-inch silicon wafer and a Z-tangential lithium tantalate wafer (hereinafter referred to as lithium tantalate wafer), respectively fixing the silicon wafer or the lithium tantalate wafer on a porous ceramic sucker of polishing equipment, carrying out chemical mechanical polishing treatment to obtain a smooth surface, and then carrying out semiconductor RCA cleaning on the two wafers to obtain a clean surface.

Secondly, injecting H into the lithium tantalate wafer processed in the step one by adopting a stripping ion implantation method⁺The lithium tantalate wafer is divided into a residual layer, a separation layer and a thin film layer in this order from the implantation surface, and H is implanted⁺Ions are distributed in the separation layer to obtain a single crystal lithium tantalate wafer injection piece;

implanting H by lift-off ion implantation⁺The implantation dose parameters were: the implantation dose is 4X 10¹⁶ions/cm²(ii) a The implantation energy is 400keV and the implantation depth is 2.62 μm;

thirdly, manufacturing amorphous silicon on the cleaned silicon wafer by an LPCVD method, wherein the thickness of the amorphous silicon is 500nm, and the amorphous silicon is the first isolating layer.

Placing the bonding body on a hot table, irradiating by a UV ultraviolet lamp with the wavelength of 363nm, annealing the bonding body at 300 ℃ for 1 minute, and separating the bonding body on a separation layer after irradiating by the UV ultraviolet lamp for 1 minute to obtain a composite film;

Example seven

Example seven provides a method for improving a phenomenon of polarization reversal on a surface of a composite film, comprising the following steps:

And secondly, directly bonding the lithium tantalate wafer with the silicon wafer to obtain a bonded body.

Placing the bonding body on a hot table, irradiating by a UV ultraviolet lamp with the wavelength of 363nm, annealing the bonding body at 300 ℃ for 1 minute, and separating the bonding body at a separation layer after irradiating by the UV ultraviolet lamp for 1 minute to obtain a composite film prefabricated body;

seventhly, fixing the composite film pre-preparation body on a porous ceramic sucker of polishing equipment, and grinding, polishing and thinning the lithium tantalate wafer to form a film layer with a target thickness on the substrate; then RCA cleaning is carried out to obtain a clean surface.

The same and similar parts among the various embodiments in the present specification can be referred to each other, and especially, the corresponding embodiment parts of the composite film can be referred to the method part for improving the polarization reversal phenomenon on the surface of the composite film.

The present application has been described in detail with reference to specific embodiments and illustrative examples, but the description is not intended to limit the application. Those skilled in the art will appreciate that various equivalent substitutions, modifications or improvements may be made to the presently disclosed embodiments and implementations thereof without departing from the spirit and scope of the present disclosure, and these fall within the scope of the present disclosure. The protection scope of this application is subject to the appended claims.

Claims

1. A method for improving the polarization reversal phenomenon on the surface of a composite film is characterized by comprising the following steps:

preparing a ferroelectric wafer and a substrate base plate, wherein the ferroelectric wafer is a Z-tangential non-component lithium niobate wafer or a Z-tangential non-component lithium tantalate wafer; or the ferroelectric wafer is a Z-tangential component lithium niobate wafer or a Z-tangential component lithium tantalate wafer;

2. The method of claim 1, wherein the UV lamp has a wavelength of 310-400 nm.

3. The method of claim 1, wherein the time for irradiating the surface of the ferroelectric wafer with a UV lamp does not exceed the time for the thermal treatment.

4. The method according to claim 1, wherein the heat treatment temperature is 100 to 600 ℃ and the heat treatment time is 1 minute to 48 hours.

5. The method of claim 1, wherein the preparing the composite thin film using an ion implantation-bonding method comprises:

bonding the ferroelectric wafer and the substrate to obtain a bonded body;

6. The method of claim 1, wherein the preparing the composite film by the bonding-thinning method comprises:

bonding the ferroelectric wafer and the substrate to obtain a bonded body;

7. The method of claim 1, further comprising:

8. The method of claim 1, wherein the substrate base plate is made of lithium niobate, lithium tantalate, a silicon wafer, a silicon carbide wafer, silicon nitride, quartz, sapphire, or quartz glass.

9. A composite film prepared by the method for improving the polarization reversal phenomenon on the surface of the composite film according to any of claims 1 to 8.