A method for blackening a piezoelectric composite film and a blackened piezoelectric composite film

Abstract

The application discloses a method for blackening a piezoelectric composite film and a blackened piezoelectric composite film. The method comprises the following steps: firstly, performing ion implantation on the blackened piezoelectric wafer, and sequentially dividing the blackened piezoelectric wafer into a residual layer, a separation layer and a piezoelectric film layer; then, bonding the blackened piezoelectric wafer after ion implantation with a substrate to obtain a bonding body; thereafter, performing a first annealing treatment on the bonding body in an oxygen atmosphere to obtain a piezoelectric composite film; finally, performing a second annealing treatment on the piezoelectric composite film in a hydrogen atmosphere to blacken the piezoelectric film layer and obtain a blackened piezoelectric composite film. In the application, the piezoelectric film layer in the piezoelectric composite film is treated by the second annealing treatment in the hydrogen atmosphere, so that the oxygen vacancy concentration of the piezoelectric film layer is increased and the resistivity of the piezoelectric film layer is reduced, and the blackening of the piezoelectric film layer is realized.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of semiconductor preparation, and particularly relates to a method for blackening a piezoelectric composite film and a blackened piezoelectric composite film. BACKGROUND

[0002] Lithium niobate and lithium tantalate crystals have been widely used in various core electronic components such as surface acoustic wave devices, thin film bulk acoustic resonators, and photoelectric sensors due to their excellent optical properties such as piezoelectricity, ferroelectricity, photoelectricity, photoelasticity, pyroelectricity, photorefractivity, and nonlinearity.

[0003] Since lithium niobate and lithium tantalate crystals are both ferroelectric crystals, they have high pyroelectric coefficients and resistivities. Thus, when electronic components are prepared using lithium niobate and lithium tantalate wafers, a large amount of static electricity is easily accumulated on the surface of the lithium niobate and lithium tantalate wafers, and the release of the static electricity can damage the lithium niobate and lithium tantalate wafers, thereby affecting the performance and yield of the prepared electronic components.

[0004] To solve the above problems, in one implementation, the lithium niobate and lithium tantalate wafers are pre-treated by blackening. The blackening treatment refers to treating the lithium niobate and lithium tantalate wafers by high-temperature chemical reduction or the like to reduce the pyroelectric effect and resistivity of the lithium niobate and lithium tantalate wafers. After the blackening treatment, the lithium niobate and lithium tantalate wafers change from colorless and transparent to brown. Further, the lithium niobate and lithium tantalate wafers after the blackening treatment are used to prepare electronic components, thereby solving the problem that the release of static electricity can damage the lithium niobate or lithium tantalate wafers.

[0005] However, the applicant found that for electronic components using piezoelectric composite films, although the lithium niobate and lithium tantalate wafers after the pre-blackening treatment are used, when the prepared piezoelectric composite films are applied to the electronic components, the release of static electricity still damages the electronic components, that is, the blackening effect of the film layer in the piezoelectric composite film is faded and becomes white.

[0006] At this time, if the film layer in the piezoelectric composite film is re-blackened by using the traditional blackening method (such as coating and patching), damage layers will be caused to the film layer, and problems such as difficult removal of particles on the film layer, uneven surface blackening, and the like will be caused. Therefore, the film layer needs to be further chemically polished (usually several microns to tens of microns are polished off), and the film layer cannot tolerate high removal amount chemical polishing on the surface. SUMMARY

[0007] To solve the above technical problems, the application provides a method for blackening a piezoelectric composite film and a blackened piezoelectric composite film.

[0008] In a first aspect, the application provides a method for blackening a piezoelectric composite film, comprising: preparing a blackened piezoelectric wafer and a substrate substrate, wherein the piezoelectric wafer is a lithium niobate wafer or a lithium tantalate wafer; ion implantation on the blackened piezoelectric wafer, and sequentially separating the blackened piezoelectric wafer into a residual layer, a separation layer and a piezoelectric film layer; bonding the ion-implanted blackened piezoelectric wafer and the substrate substrate to obtain a bonding body; and performing at least one alternating whitening treatment and blackening treatment on the bonding body to blacken the piezoelectric film layer and obtain a blackened piezoelectric composite film, wherein the blackened piezoelectric composite film comprises a substrate substrate and a blackened piezoelectric film layer which are sequentially stacked; wherein the whitening treatment comprises: performing one annealing treatment on the bonding body in an oxygen atmosphere to whiten the piezoelectric film layer and obtain a piezoelectric composite film, wherein the piezoelectric composite film comprises a substrate substrate and a whitened piezoelectric film layer which are sequentially stacked; and the blackening treatment comprises: performing two annealing treatments on the piezoelectric composite film in a hydrogen atmosphere to blacken the whitened piezoelectric film layer and obtain a blackened piezoelectric composite film, wherein the blackened piezoelectric composite film comprises a substrate substrate and a blackened piezoelectric film layer which are sequentially stacked.

[0009] In an implementation, if the piezoelectric wafer is a lithium niobate wafer or a lithium tantalate wafer which has not been blackened, the at least one alternating whitening treatment and blackening treatment on the bonding body comprises: performing a first blackening treatment on the bonding body; and performing 2-3 alternating whitening treatments and blackening treatments on the bonding body after the first blackening treatment to blacken the piezoelectric film layer.

[0010] In an implementation, if the piezoelectric wafer is a lithium niobate wafer or a lithium tantalate wafer which has been blackened, the at least one alternating whitening treatment and blackening treatment on the bonding body comprises: performing 2-3 alternating whitening treatments and blackening treatments on the bonding body to blacken the piezoelectric film layer.

[0011] In an implementation, the annealing temperature of the second annealing treatment is greater than a first temperature and less than a second temperature, wherein the first temperature is a lattice recovery temperature of the piezoelectric film layer, and the second temperature is a Curie temperature of the piezoelectric film layer.

[0012] In an implementation, the annealing temperature of the first annealing treatment is 100-400℃, and the holding time of the first annealing treatment is 0.5-100 hours.

[0013] In an implementation, the first temperature is at least 450℃, and the holding time of the second annealing treatment is 1-100 hours.

[0014] In an implementation, after the piezoelectric composite film is cooled to a preset temperature, the piezoelectric composite film is subjected to secondary annealing treatment, wherein the preset temperature is 20-40℃.

[0015] In an implementation, after the piezoelectric composite film is cooled to a preset temperature, the piezoelectric composite film is subjected to secondary annealing treatment, wherein the preset temperature is 20-40℃.

[0016] In an implementation, the temperature increasing speed of the primary annealing treatment is lower than that of the secondary annealing treatment.

[0017] In an implementation, the temperature increasing speed of the primary annealing treatment is 0.5-1℃ / min, and the temperature increasing speed of the secondary annealing treatment is 5-10℃ / min.

[0018] In a second aspect, the application provides a blackened piezoelectric composite film, which is prepared by the method for blackening a piezoelectric composite film according to any one of the first aspect.

[0019] In a third aspect, the application provides an electronic component, which comprises the blackened piezoelectric composite film according to the second aspect.

[0020] In summary, the method for blackening a piezoelectric composite film and the blackened piezoelectric composite film provided by the application are as follows: first, ion implantation is performed on the blackened piezoelectric wafer, and the blackened piezoelectric wafer is sequentially divided into a residual layer, a separation layer and a piezoelectric film layer; then, the blackened piezoelectric wafer after ion implantation is bonded with the substrate to obtain a bonding body; thereafter, the bonding body is subjected to primary annealing treatment in an oxygen atmosphere to obtain a piezoelectric composite film; finally, the piezoelectric composite film is subjected to secondary annealing treatment in a hydrogen atmosphere, so that the piezoelectric film layer is blackened to obtain a blackened piezoelectric composite film. In the application, after the hydrogen atmosphere contacts the piezoelectric film layer, hydrogen can react with oxygen in the piezoelectric film layer to form oxygen vacancies at the positions where oxygen originally exists. With the reaction proceeding, oxygen in the piezoelectric film layer diffuses from the positions with high oxygen concentration to the positions with low oxygen concentration, i.e., oxygen below the piezoelectric film layer gradually diffuses to the upper part of the piezoelectric film layer. The oxygen diffused to the upper part of the piezoelectric film layer is gradually reduced by hydrogen, so that more oxygen vacancies are formed in the piezoelectric film layer. Therefore, after the piezoelectric film layer in the piezoelectric composite film is subjected to secondary annealing treatment in the hydrogen atmosphere, the oxygen vacancy concentration increases and the resistivity decreases, so that the piezoelectric film layer is blackened. The blackening by hydrogen is more uniform and does not cause local blackening and local whitening. The operation is simple, no other impurities are introduced, and the surface of the film layer is not damaged. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings described below are only some embodiments of the present application, and all other drawings obtained by those of ordinary skill in the art without creative effort based on these drawings also belong to the protection scope of the present application.

[0022] Figure 1 A process flow chart of a method for blackening a piezoelectric composite film provided by the present application is shown in Figure 1.

[0023] Figure 2A A schematic diagram of the blackened piezoelectric film layer prepared in Experimental Example One is shown in Figure 2.

[0024] Figure 2B A schematic diagram of the blackened piezoelectric film layer prepared in Comparative Example Five is shown in Figure 5.

[0025] Figure 3A A schematic diagram of the blackened piezoelectric film layer prepared in Experimental Example Ten is shown in Figure 10.

[0026] Figure 3B A schematic diagram of the blackened piezoelectric film layer prepared in Experimental Example Eleven is shown in Figure 11.

[0027] Figure 3C A schematic diagram of the blackened piezoelectric film layer prepared in Experimental Example Twelve is shown in Figure 12.

[0028] Explanation of reference signs

[0029] 100 - blackened piezoelectric wafer, 200 - substrate base plate, 300 - bonding body, 110 - residual layer, 120 - separation layer, 130 - film layer, 130A - blackened piezoelectric film layer, 130B - whitened piezoelectric film layer. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, rather than all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort belong to the protection scope of the present application.

[0031] Reference Figure 1 , Figure 1 A process flow chart of a method for blackening a piezoelectric composite film provided by the present application is shown in Figure 1. The method comprises the following steps:

[0032] Step S100, preparing a blackened piezoelectric wafer 100 and a substrate base plate 200, wherein the blackened piezoelectric wafer 100 is a lithium niobate wafer or a lithium tantalate wafer.

[0033] The piezoelectric wafer in the embodiments of the present application refers to a base material with a certain thickness for preparing a piezoelectric thin film layer. The blackened piezoelectric wafer 100 refers to a piezoelectric wafer after blackening treatment.

[0034] In one implementation manner, the blackened piezoelectric wafer 100 in the embodiments of the present application can be obtained by direct purchase.

[0035] In one implementation manner, the blackened piezoelectric wafer 100 in the embodiments of the present application can be prepared by the following implementation manner: directly purchasing or manufacturing a piezoelectric wafer, and then blackening the piezoelectric wafer to obtain the blackened piezoelectric wafer.

[0036] It should be noted that the blackening method of the piezoelectric wafer is not limited in the present application, and any method for blackening the wafer can be used. For example, the blackened piezoelectric wafer can be obtained by alternately stacking and contacting the deep blackened piezoelectric wafer and the piezoelectric wafer without blackening; for another example, the blackened piezoelectric wafer can be obtained by directly burying the piezoelectric wafer without blackening in the reducing powder by using the burying method.

[0037] It should be further noted that in the blackening process of the piezoelectric wafer, some damages and particles may be formed on the surface of the blackened piezoelectric wafer. Therefore, in order to remove the damages and particles on the surface of the blackened piezoelectric wafer, the blackened piezoelectric wafer needs to be further chemically polished, and generally, several microns to tens of microns of thickness need to be polished off.

[0038] The substrate 200 in the embodiments of the present application can be a single-layer substrate or a composite substrate, that is, the substrate 200 includes at least one substrate layer. The material of each substrate layer can be the same or different, which is not limited in the present application. For example, the material of the substrate layer can be lithium niobate, lithium tantalate, silicon wafer, silicon carbide wafer, silicon nitride, quartz, sapphire or quartz glass, which is not limited in the present application.

[0039] Then, the bonding body is prepared by using the ion implantation-bonding method.

[0040] Firstly, it should be noted that the ion implantation-bonding method refers to ion implantation on the blackened piezoelectric wafer 100, and the blackened piezoelectric wafer 100 is sequentially divided into the residual layer 110, the separation layer 120 and the thin film layer 130; then, the blackened piezoelectric wafer 100 after ion implantation is bonded with the substrate 200 to obtain the bonding body 300.

[0041] The process of preparing the bonding body 300 by using the ion implantation-bonding method will be described in detail below.

[0042] Step S200, ion implantation is performed on the blackened piezoelectric wafer 100, and the blackened piezoelectric wafer 100 is sequentially divided into the residual layer 110, the separation layer 120 and the piezoelectric film layer 130.

[0043] The ion implantation method is not particularly limited in the embodiments of the present application, and any ion implantation method in the prior art can be used. The implanted ions can be ions that can generate gas through heat treatment, for example, hydrogen ions, helium ions, nitrogen ions, oxygen ions or argon ions. When the ions are implanted, the implantation dose can be 2×10 16 ions / cm 2 ~ 4×10 16 ions / cm 2 , and the implantation energy can be 40 KeV ~ 400 KeV.

[0044] In the embodiments of the present application, the thickness of the piezoelectric film layer 130 can be adjusted by adjusting the ion implantation depth. Specifically, the greater the ion implantation depth, the greater the thickness of the prepared piezoelectric film layer 130; on the contrary, the smaller the ion implantation depth, the smaller the thickness of the prepared piezoelectric film layer 130.

[0045] Step S300, the blackened piezoelectric wafer 100 after ion implantation is bonded with the substrate 200 to obtain a bonding body 300.

[0046] It should be noted that the bonding surface bonded with the substrate 200 is the surface of the piezoelectric film layer 130 in the blackened piezoelectric wafer 100 after ion implantation.

[0047] After bonding, the piezoelectric film layer 130 in the blackened piezoelectric wafer 100 is in contact with the substrate 200 and is laminated on the substrate 200, so that the bonding body 300 has the residual layer 110, the separation layer 120, the piezoelectric film layer 130 and the substrate 200 laminated in order from top to bottom.

[0048] The bonding method is not particularly limited in the present application, and any bonding method in the prior art can be used, for example, surface activation is used to bond and obtain a bonding body. The surface activation method is also not limited in the present application, for example, plasma activation or chemical solution activation can be used.

[0049] Step S400, the bonding body 300 is subjected to one-time annealing treatment in an oxygen atmosphere, the piezoelectric film layer 130 is whitened, and a piezoelectric composite film is obtained, which includes the substrate 200 and the whitened piezoelectric film layer 130B laminated in order.

[0050] Step S500, the piezoelectric composite film is subjected to secondary annealing treatment under a hydrogen atmosphere, so that the whitened piezoelectric film layer 130B is blackened to obtain a blackened piezoelectric composite film, wherein the blackened piezoelectric composite film comprises the substrate substrate 200 and the blackened piezoelectric film layer 130A which are sequentially stacked.

[0051] In the embodiments of the present application, step S400 is a whitening treatment step, and step S500 is a blackening treatment step.

[0052] In the embodiments of the present application, the bonding body 300 is subjected to whitening treatment before blackening treatment, so that the whitening effect of the piezoelectric film layer 130 in the bonding body 300 is close to uniform, thereby being more conducive to obtaining a blackened piezoelectric film layer 130A with more uniform blackening effect on the basis of the piezoelectric film layer 130 with uniform whitening effect.

[0053] During the primary annealing treatment of the bonding body 300, bubbles are formed in the separation layer 120, for example, H ions form hydrogen gas, He ions form helium gas, etc. With the progress of the primary annealing treatment, the bubbles in the separation layer 120 are connected together, and finally the separation layer 120 is cracked, separating the excess layer 110 from the piezoelectric film layer 130, so that the excess layer 110 is peeled off from the bonding body 300, and the piezoelectric film layer 130 remains on the substrate substrate 200, to obtain a piezoelectric composite film, wherein the piezoelectric composite film has the piezoelectric film layer 130 and the substrate substrate 200 which are sequentially stacked from top to bottom.

[0054] The annealing temperature and the annealing time of the primary annealing treatment are determined according to the peeling of the excess layer 110 from the bonding body 300. In one implementation, the annealing temperature of the primary annealing treatment is 100-400℃, and the holding time of the primary annealing treatment is 0.5-100 hours.

[0055] In addition, since the above-mentioned primary annealing treatment is carried out in an oxygen atmosphere, the piezoelectric film layer 130 originally blackened on the substrate substrate 200 loses its blackening effect and becomes white after the primary annealing treatment. That is, the piezoelectric film layer 130 in the piezoelectric composite film obtained after the primary annealing treatment is whitened.

[0056] It should be noted that the whitening of the piezoelectric film layer 130 will cause the pyroelectric effect and the resistivity of the piezoelectric film layer 130 to increase, so if the piezoelectric composite film obtained after the primary annealing treatment is directly applied to downstream electronic components, it will seriously affect the performance of the downstream electronic components.

[0057] However, if the white piezoelectric film layer 130B is re-blackened in the same way as the blackened piezoelectric wafer, since the thickness of the piezoelectric film layer 130 at this time is very small, generally a few hundred nanometers, the chemical polishing operation of a few microns to tens of microns in thickness cannot be allowed. That is, the existing blackening treatment method for the piezoelectric wafer is not applicable to the blackening treatment of the piezoelectric composite film.

[0058] In one implementation, the piezoelectric film layer 130 in the piezoelectric composite film is re-blackened, and the following implementation (burial method) can be used: laying a reducing paper on the piezoelectric film layer 130, and then burying the piezoelectric composite film with the reducing paper in blackening powder, wherein the blackening powder includes reducing powder and lithium carbonate powder; performing blackening reduction heat treatment on the piezoelectric composite film buried in the blackening powder in a reducing furnace; and finally removing the reducing paper to obtain a blackened piezoelectric composite film. This implementation can re-blacken the piezoelectric film layer 130 and obtain a piezoelectric film layer 130 with a clean surface, and the blackened piezoelectric film layer 130 does not need to be chemically polished to a thickness of a few microns to tens of microns. However, the blackening treatment of the piezoelectric film layer 130 is not uniform, specifically: the color of the outer surface of the blackened piezoelectric film layer 130 prepared by using this burial method is not uniform, that is, the blackening degree is inconsistent at different positions, that is, the resistivity is inconsistent at different positions.

[0059] Therefore, in the embodiment of the present application, the piezoelectric composite film is subjected to secondary annealing treatment in a hydrogen atmosphere to blacken the white piezoelectric film layer 130B, and a blackened piezoelectric composite film is obtained, wherein the blackened piezoelectric composite film includes a substrate 200 and a blackened piezoelectric film layer 130A stacked in sequence.

[0060] First of all, it should be pointed out that ion implantation and peeling of the residual layer 110 will cause certain damage to the crystal lattice of the prepared piezoelectric film layer 130. In the secondary annealing treatment, the crystal lattice of the piezoelectric film layer 130 can also be restored, wherein the crystal lattice restoration temperature refers to the temperature at which the crystal lattice of the piezoelectric film layer 130 can be restored, for example, the crystal lattice restoration temperature of the piezoelectric film layer 130 in the embodiment of the present application is at least 450°C.

[0061] Secondly, it should be pointed out that if the annealing temperature of the secondary annealing treatment is higher than the Curie temperature of the piezoelectric film layer 130, the piezoelectric film layer 130 will appear depolarization phenomenon, and further cause the piezoelectric film layer 130 to have no piezoelectricity. The Curie temperature of lithium niobate is 1140°C, and the Curie temperature of lithium tantalate is 650°C.

[0062] Therefore, the annealing temperature of the second annealing process is greater than the first temperature and less than the second temperature, wherein the first temperature is the lattice recovery temperature of the piezoelectric film layer 130, and the second temperature is the Curie temperature of the piezoelectric film layer 130. For example, when the material of the piezoelectric film layer 130 is lithium niobate, the annealing temperature of the second annealing process is 450-1140°C; for another example, when the material of the piezoelectric film layer 130 is lithium tantalate, the annealing temperature of the second annealing process is 450-650°C.

[0063] The annealing temperature of the second annealing process can not only recover the lattice of the piezoelectric film layer 130 and maintain the piezoelectric performance of the piezoelectric film layer 130, but also re-blacken the whitened piezoelectric film layer, and a piezoelectric film layer with very uniform blackening can be obtained.

[0064] It should be noted that, before the second annealing process, the piezoelectric composite film obtained by the first annealing process needs to be cooled to a preset temperature and then cleaned before the second annealing process. The cooling method of the piezoelectric composite film can be self-ignition cooling. The preset temperature is not limited in the present application. For example, the preset temperature can be room temperature, such as 20-40°C.

[0065] It should be further noted that, if the same annealing furnace is used for the first annealing process and the second annealing process, the oxygen atmosphere in the annealing process needs to be completely removed during the second annealing process, and the annealing atmosphere of the second annealing process needs to be 100% hydrogen. The holding time of the second annealing process can be 1-100 hours.

[0066] It should be further noted that, in the present application, the first annealing process and the second annealing process have different heating rates, and the heating rate of the second annealing process is greater than that of the first annealing process. The first annealing process has a slower heating rate, which can prevent the piezoelectric film layer from being broken due to the hetero-substrate; the second annealing process has a faster heating rate, which can quickly reach the temperature required for blackening reaction. For example, the heating rate of the first annealing process can be 0.5-1°C / min, and the heating rate of the second annealing process can be 5-10°C / min.

[0067] The applicant has also found that, after repeating the whitening process and the blackening process on the bonding body 300 for multiple times, a blackened piezoelectric film layer with better color uniformity and lower resistivity deviation can be obtained. However, the more the number of repeated whitening and blackening processes, the lower the resistivity and the darker the color will be; if the resistivity is too low, the blackened piezoelectric film layer prepared therefrom cannot be applied to the target scene. For example, in the application scenario of SAW devices, the resistivity of the blackened piezoelectric film layer 130A applied in the SAW devices is required to be 10 1110 10 Ω·cm, if the resistivity of the blackened piezoelectric thin film layer 130A prepared is in the range of 10 11 Ω·cm, the lithium tantalate / lithium niobate wafer with too dark color (very small resistivity) cannot be used because it will affect the insertion loss of the SAW device and easily cause poor processability of the wafer and easy breakage.

[0068] Specifically, the number of times of alternately performing the whitening treatment and the blackening treatment on the bonded body 300 can be determined according to the target resistivity of the blackened piezoelectric thin film layer 130A to be obtained and the resistivity testing method. For example, if the target resistivity of the blackened piezoelectric thin film layer 130A to be obtained is in the order of 10 11 Ω·cm, the resistivity of the blackened piezoelectric thin film layer 130A can be tested after each blackening treatment, and when the tested resistivity is in the order of 10 11 Ω·cm, the whitening treatment and the blackening treatment on the bonded body 300 are stopped.

[0069] In a specific example, the resistivity of the blackened piezoelectric thin film layer 130A prepared by repeating the above-mentioned whitening treatment and blackening treatment on the bonded body 2-3 times in the present application can satisfy 10 11 Ω·cm, and the blackened piezoelectric thin film layer 130A prepared has uniform color.

[0070] It should be noted that the piezoelectric wafer in the above-mentioned embodiments is only exemplarily described by taking the lithium niobate wafer or the lithium tantalate wafer as an example, and is not limited to the piezoelectric wafer. For example, the piezoelectric wafer in the present application can also be a lithium niobate wafer or a lithium tantalate wafer that has not been blackened. If the piezoelectric wafer in the present application can also be a lithium niobate wafer or a lithium tantalate wafer that has not been blackened, the bonded body can be blackened once before the first whitening treatment of the bonded body 300.

[0071] The effect of the blackening of the piezoelectric composite thin film provided by the embodiments of the present application is described below by using test data.

[0072] First group of experiments:

[0073] Experiment Example One

[0074] The blackened piezoelectric composite thin film is prepared by using the method for blackening the piezoelectric composite thin film provided by the embodiments of the present application, wherein the blackened piezoelectric wafer is a blackened lithium niobate wafer, the annealing temperature of the first annealing treatment (i.e., the whitening treatment) is 100°C, the holding time of the first annealing treatment is 100 hours, the annealing temperature of the second annealing treatment (i.e., the blackening treatment) is 450°C, the holding time of the second annealing treatment is 100 hours, and the amount of hydrogen gas introduced during the second annealing treatment is 1 L / min.

[0075] Experimental Example Two

[0076] Experimental Example Two is basically the same as Experimental Example One, except that the blackened piezoelectric wafer in Experimental Example Two is a blackened lithium tantalate wafer.

[0077] Experimental Example Three

[0078] Experimental Example Three is basically the same as Experimental Example One, except that in Experimental Example Three, the annealing temperature of the first annealing treatment is 200°C, and the holding time of the first annealing treatment is 50 hours; the annealing temperature of the second annealing treatment is 530°C, and the holding time of the second annealing treatment is 50 hours, wherein the amount of hydrogen gas introduced during the second annealing treatment is 2 L / min.

[0079] Experimental Example Four

[0080] Experimental Example Four is basically the same as Experimental Example Three, except that the blackened piezoelectric wafer in Experimental Example Four is a blackened lithium tantalate wafer.

[0081] Experimental Example Five

[0082] Experimental Example Five is basically the same as Experimental Example One, except that in Experimental Example Five, the annealing temperature of the first annealing treatment is 300°C, and the holding time of the first annealing treatment is 0.5 hours; the annealing temperature of the second annealing treatment is 650°C, and the holding time of the second annealing treatment is 1 hour, wherein the amount of hydrogen gas introduced during the second annealing treatment is 5 L / min.

[0083] Experimental Example Six

[0084] Experimental Example Six is basically the same as Experimental Example Five, except that the blackened piezoelectric wafer in Experimental Example Six is a blackened lithium tantalate wafer.

[0085] Comparative Example One

[0086] The method for preparing a piezoelectric composite thin film in Comparative Example One comprises the following steps: first preparing a blackened piezoelectric wafer and a substrate base plate, wherein the piezoelectric wafer is a lithium niobate wafer; then, performing ion implantation on the blackened piezoelectric wafer, and sequentially dividing the blackened piezoelectric wafer into a residual layer, a separation layer, and a piezoelectric thin film layer; bonding the blackened piezoelectric wafer after ion implantation with the substrate base plate to obtain a bonded body; performing a first annealing treatment on the bonded body under a non-hydrogen gas atmosphere to obtain a piezoelectric composite thin film, wherein the piezoelectric composite thin film comprises a substrate base plate and a piezoelectric thin film layer which are sequentially stacked. The annealing temperature of the first annealing treatment is 300°C, and the holding time is 0.5 hours. Comparative Example One does not perform a second annealing treatment.

[0087] Comparative Example Two

[0088] The comparative example two is basically the same as the comparative example one, except that the blackened piezoelectric wafer in the comparative example two is blackened lithium tantalate; the annealing temperature of the first annealing treatment is 200°C, and the holding time is 50 hours.

[0089] The piezoelectric film layers in the products prepared in the above experimental examples one to five and the comparative examples one and two are subjected to resistivity test and color observation, and the experimental results are shown in Table 1 below.

[0090] Table 1 Experimental results of experimental examples one to five and comparative examples one and two

[0091]

[0092]

[0093] As shown in Table 1, the piezoelectric film layers in the blackened piezoelectric composite films prepared in experimental examples one, three and five have blackish gray color, the piezoelectric film layers in the blackened piezoelectric composite films prepared in experimental examples two, four and six have blackish yellow color; the piezoelectric film layer prepared in the comparative example one has white color, and the piezoelectric film layer prepared in the comparative example two has yellow color. Therefore, the piezoelectric film layer in the blackened piezoelectric composite film prepared by the method for blackening piezoelectric composite film provided in the present application is a blackened piezoelectric film layer, while the piezoelectric film layers prepared in the comparative examples one and two are whitened piezoelectric film layers.

[0094] Continuing to refer to the resistivity of the piezoelectric film layer in Table 1, the resistivity of experimental examples one to five is between 1.2e 11 and 2.6e 11 , the resistivity of the comparative example one is 2.2e 14 , and the resistivity of the comparative example two is 2.4e 14 . Therefore, the resistivity of the experimental example group is much higher than that of the comparative example group.

[0095] It should be noted that the resistivity in Table 1 above refers to the average resistivity of each region of the piezoelectric film layer.

[0096] Second group of experiments:

[0097] The second group of experiments tests the breakage rate of the piezoelectric film in the blackened piezoelectric composite film prepared by adjusting the annealing speed of the first annealing treatment and the second annealing treatment.

[0098] Experimental example seven

[0099] Experimental Example Seven is basically the same as Experimental Example One in the above first group of experiments, except that the temperature increasing rate of the first annealing treatment in Experimental Example Seven is 0.5°C / min and the temperature increasing rate of the second annealing treatment is 5°C / min.

[0100] Experimental Example Eight

[0101] Experimental Example Eight is basically the same as Experimental Example Seven above, except that the temperature increasing rate of the first annealing treatment in Experimental Example Eight is 1°C / min and the temperature increasing rate of the second annealing treatment is 7°C / min.

[0102] Experimental Example Nine

[0103] Experimental Example Nine is basically the same as Experimental Example Seven above, except that the temperature increasing rate of the first annealing treatment in Experimental Example Nine is 0.8°C / min and the temperature increasing rate of the second annealing treatment is 10°C / min.

[0104] Comparative Example Three

[0105] Comparative Example Three is basically the same as Experimental Example Seven above, except that the temperature increasing rate of the first annealing treatment in Comparative Example Three is 2°C / min and the temperature increasing rate of the second annealing treatment is 10°C / min.

[0106] Comparative Example Four

[0107] Comparative Example Four is basically the same as Experimental Example Seven above, except that the temperature increasing rate of the first annealing treatment in Comparative Example Four is 5°C / min and the temperature increasing rate of the second annealing treatment is 1°C / min.

[0108] The methods provided in Experimental Examples Seven to Four above are respectively used to prepare 100 piezoelectric composite films, and then the breakage rate of the piezoelectric film layer in the 100 piezoelectric composite films prepared in each group of experiments is calculated. The breakage rate experimental results are shown in Table 2 below.

[0109] Table 2 Breakage rate experimental results

[0110]

[0111] As shown in Table 2, when the temperature increasing rate of the first annealing treatment is 0.5-1°C / min and the temperature increasing rate of the second annealing treatment is 5-10°C / min, the breakage rate of the piezoelectric film layer prepared is 0; and when the temperature increasing rate of the first annealing treatment is greater than 1°C / min, the breakage rate of the piezoelectric film layer prepared is 100%.

[0112] Third Group of Experiments

[0113] The third group of experiments compares the blackening effects of different blackening methods on the piezoelectric film layer, wherein Experimental Example uses the blackened piezoelectric composite film prepared in Experimental Example One above, and Comparative Example Five uses the blackened piezoelectric composite film prepared by the burying method.

[0114] In the blackened piezoelectric composite film prepared by Comparative Example Five, the blackened piezoelectric thin film layer includes the following steps: ion implantation is performed on the blackened piezoelectric wafer, wherein the blackened piezoelectric wafer is a blackened lithium niobate wafer, the blackened piezoelectric wafer is sequentially divided into a residual layer, a separation layer and a piezoelectric thin film layer; the blackened piezoelectric wafer after ion implantation is bonded with the substrate to obtain a bonding body; the bonding body is subjected to one-time annealing treatment under a non-hydrogen atmosphere to obtain a piezoelectric composite film, a reduction paper is laid on the piezoelectric thin film layer of the piezoelectric composite film, and then the piezoelectric composite film laid with the reduction paper is buried in blackening powder, wherein the blackening powder includes reducing powder and lithium carbonate powder; the piezoelectric composite film buried in the blackening powder is blackened and reduced in a reduction furnace; finally, the reduction paper is removed to obtain a blackened piezoelectric composite film.

[0115] Referring to Figure 2A and Figure 2B , Figure 2A the schematic diagram of the blackened piezoelectric thin film layer in the blackened piezoelectric composite film prepared by Experimental Example One is shown, Figure 2B the schematic diagram of the blackened piezoelectric thin film layer in the blackened piezoelectric composite film prepared by Comparative Example Five is shown.

[0116] Comparing Figure 2A and Figure 2B , Figure 2A the surface color of the blackened piezoelectric thin film layer shown is uniform, while Figure 2B the surface color of the blackened piezoelectric thin film layer shown is not uniform, and is obviously distributed in multiple regions.

[0117] Further, the resistivity of each part of the blackened piezoelectric thin film layer in Figure 2A and Figure 2B is tested, and it is found that Figure 2A the average resistivity of the blackened piezoelectric thin film layer in Experimental Example One is 1.8e 11 (Ω·m), Figure 2B the average resistivity of the blackened piezoelectric thin film layer in Comparative Example Five is 6.5e 11 (Ω·m).

[0118] Therefore, although the resistivity of the blackened piezoelectric thin film layer prepared by Experimental Example One and Comparative Example Five both meets the use requirements, the blackening of the blackened piezoelectric thin film layer in the blackened piezoelectric composite film prepared by Experimental Example One is more uniform, which is beneficial to the needs of cutting and using in the later stage. For example, if the blackened piezoelectric composite film needs to be etched into a target structure with a certain pattern in the later stage, the blackened piezoelectric composite film prepared by Experimental Example One can ensure the consistency of the performance of each part of the target structure, which is crucial for the electronic components using the target structure.

[0119] In combination Figure 2A , Figure 2B and Table 3, compared with the burying method, the method for blackening the piezoelectric film layer provided in the application can obtain a blackened piezoelectric film layer with uniform resistivity.

[0120] The applicant further found that, in the hydrogen atmosphere secondary annealing process, the hydrogen atmosphere is a reducing atmosphere, and after the hydrogen atmosphere contacts the piezoelectric film layer, the hydrogen can react with oxygen in the piezoelectric film layer to form oxygen vacancies at the positions where the oxygen originally exists. With the reaction proceeding, the oxygen in the piezoelectric film layer diffuses from the positions with high oxygen concentration to the positions with low oxygen concentration, i.e., the oxygen below the piezoelectric film layer gradually diffuses to the upper part of the piezoelectric film layer, and the oxygen diffused to the upper part of the piezoelectric film layer is gradually reduced by the hydrogen, thereby forming more oxygen vacancies in the piezoelectric film layer. Therefore, after the piezoelectric film layer in the piezoelectric composite film is subjected to the hydrogen secondary annealing process, the oxygen vacancy concentration increases and the resistivity decreases, realizing the blackening of the piezoelectric film layer. The hydrogen blackening is more uniform and does not cause the phenomenon of local blackening and local whitening. The operation is simple, does not introduce other impurities, and does not damage the surface of the film layer.

[0121] In addition, the applicant found that, since the nanoscale piezoelectric film layer is subjected to the secondary annealing process in the hydrogen atmosphere, in the blackening process of the piezoelectric film layer in the application, only the hydrogen atmosphere needs to be introduced to blacken the piezoelectric film layer, and no other substances need to be introduced. That is, compared with the prior art, in the blackening process of the piezoelectric wafer, the piezoelectric wafer with deep blackening needs to be alternately stacked and contacted with the piezoelectric wafer without blackening to blacken the piezoelectric wafer. In the blackening process of the piezoelectric composite film provided in the application, only the piezoelectric composite film needs to be placed in the hydrogen atmosphere to perform the secondary annealing process to blacken the piezoelectric film layer.

[0122] The fourth group of experiments

[0123] The fourth group of experiments compares the effects of different whitening and blackening processes on the prepared blackened piezoelectric composite film.

[0124] Experiment example ten

[0125] The blackened piezoelectric composite film is prepared by the method for blackening the piezoelectric composite film provided in the application, wherein the piezoelectric wafer is a lithium tantalate wafer subjected to blackening, the annealing temperature of the first annealing process in the whitening process is 200°C, and the holding time of the first annealing process is 5 hours; the annealing temperature of the second annealing process in the blackening process is 530°C, and the holding time of the second annealing process is 3 hours, wherein the gas flow of the hydrogen gas introduced in the second annealing process is 1L / min.

[0126] In Experiment 10, a whitening and blackening treatment was performed.

[0127] Experimental Example 11

[0128] Experimental Example 11 is basically the same as Experimental Example 10, except that the whitening and blackening treatments were repeated twice in Experimental Example 11.

[0129] Experimental Example Twelve

[0130] Experimental Example 12 is basically the same as Experimental Example 10, except that the whitening and blackening treatments were repeated three times in Experimental Example 12.

[0131] The resistivity of the piezoelectric thin film layer in the products prepared in Experimental Examples 10 to 12 above was tested, and the appearance and color were observed. The experimental results are shown in Table 3 below.

[0132] Table 3. Experimental results of Experiment Examples 10 to 12

[0133]

[0134] See Figure 2A , Figure 2B and Figure 3A , Figure 3B This is a schematic diagram of the blackened piezoelectric film layer in the blackened piezoelectric composite film prepared in Experiment Example 10. Figure 3C This is a schematic diagram of the blackened piezoelectric film layer in the blackened piezoelectric composite film prepared in Experiment Example 11. Figure 3A This is a schematic diagram of the blackened piezoelectric film layer in the blackened piezoelectric composite film prepared in Experiment Example 12.

[0135] contrast Figure 3B , Figure 3C and Figure 3A It can be seen that, Figure 3B , Figure 3C and Figure 3A The blackened piezoelectric thin film layers shown all have a uniform color, however, Figure 3B There are still 10 unblackened white spots dispersed on the surface of the blackened piezoelectric thin film layer. Figure 3C In the first case, two unblackened white spots were still dispersed on the surface of the blackened piezoelectric film layer; while the blackened piezoelectric film layer prepared after three repeated whitening and blackening treatments had a uniform blackening surface and no unblackened white spots.

[0136] Furthermore, this application addresses respectively Figure 3A , Figure 3B and Figure 3A Resistivity measurements were performed at various locations on the blackened piezoelectric thin film layer to obtain... Figure 3B The average resistivity of the blackened piezoelectric thin film layer is 2.6 e.11 (Ω·m), Figure 3C The average resistivity of the blackened piezoelectric thin film layer is 1.8e 11 (Ω·m), Figure 3A Figure 3B Figure 3C The average resistivity of the blackened piezoelectric thin film layer is 1.4e 11 (Ω·m).

[0137] In summary, through the above experimental examples 10 to 12, it can be seen that after repeated whitening and blackening treatment, a blackened piezoelectric thin film layer with more uniform color can be prepared, so that the resistivity of the blackened piezoelectric thin film layer is uniform, thereby ensuring the performance indicators of the downstream product using the blackened piezoelectric composite film.

[0138] The application also provides a blackened piezoelectric composite film prepared by the method for inhibiting whitening of a piezoelectric composite film provided in the embodiments of the application.

[0139] In one implementation manner, the application provides a blackened piezoelectric composite film, which comprises a blackened piezoelectric thin film layer and a substrate substrate stacked in sequence, wherein the substrate substrate can be a single-layer substrate or a composite substrate.

[0140] In another implementation manner, the application provides a blackened piezoelectric composite film, which can further comprise one or more isolation layers between the blackened piezoelectric thin film layer and the substrate substrate.

[0141] The isolation layer can be single-layer or multi-layer, which is not limited by the application. For example, an alternating stack of silicon oxide layers and silicon nitride layers is prepared on the substrate substrate 200.

[0142] The application does not limit the method for preparing the isolation layer. For example, the substrate substrate 200 is a single-layer silicon substrate, and the silicon oxide can be prepared on the single-layer silicon substrate by a thermal oxidation method, and the generated silicon oxide layer serves as the isolation layer. For another example, the deposition method can also be used to prepare the isolation layer on the substrate substrate 200.

[0143] The application also provides an electronic component, which uses the blackened piezoelectric composite film provided in the embodiments of the application. The piezoelectric thin film layer in the blackened piezoelectric composite film provided in the embodiments of the application can effectively reduce the pyroelectric effect of the piezoelectric composite film, and the resistivity of the piezoelectric thin film layer is uniform, so that the use performance of the electronic component is not affected when used.

[0144] The preparation method provided by the application is described below through specific examples.

[0145] Example 1

[0146] A method for blackening a piezoelectric composite film, comprising the following steps:

[0147] 1. Provide a 6-inch silicon wafer and blackened lithium niobate wafer, fix the silicon wafer or lithium niobate on the porous ceramic chuck of polishing equipment respectively, and perform chemical mechanical polishing to obtain a smooth surface, and then perform semiconductor RCA cleaning to obtain a clean surface;

[0148] 2. Perform ion implantation on the lithium niobate wafer treated in step 1 to implant He + , so that the lithium niobate wafer is sequentially divided into a residual layer, a separation layer and a piezoelectric film layer from the implantation surface, and the implanted He + is distributed in the separation layer to obtain a single crystal wafer implantation sheet;

[0149] When He + is implanted, the implantation dose parameters are as follows: the implantation dose is 2×10 16 ions / cm 2 , the implantation energy is 40 keV, and the implantation depth is 220 nm.

[0150] 3. On the cleaned silicon wafer, a silicon dioxide layer is prepared by LPCVD method, and then chemical mechanical polishing is performed to a thickness of 100 nm to obtain a smooth surface, and RCA cleaning is performed to obtain a clean surface;

[0151] 4. The piezoelectric film layer of the single crystal wafer implantation sheet is in contact with the silicon dioxide layer, and direct bonding is adopted to obtain a bonded body;

[0152] 5. The bonded body is placed in an annealing furnace, and first annealing is performed at 180℃ for 2 hours in an oxygen atmosphere, and the bonded body is separated at the separation layer to obtain a piezoelectric composite film;

[0153] 6. The piezoelectric composite film is annealed at 450℃ for 100 hours in a hydrogen atmosphere to obtain a blackened piezoelectric composite film;

[0154] 7. The blackened piezoelectric composite film is fixed on the porous ceramic chuck of the polishing equipment, and the piezoelectric film layer is subjected to chemical mechanical polishing, and then RCA cleaning is performed to obtain a clean surface.

[0155] In the blackened piezoelectric composite film prepared in Example 1, the average resistivity of the piezoelectric film layer is 1.8e 11 (Ω·m).

[0156] Example 2

[0157] A method for blackening a piezoelectric composite film, comprising the following steps:

[0158] 1. Provide a 4-inch silicon wafer and blackened lithium niobate wafer, fix the silicon wafer or lithium niobate on the porous ceramic chuck of the polishing equipment respectively, and perform chemical mechanical polishing to obtain a smooth surface, and then perform semiconductor RCA cleaning to obtain a clean surface;

[0159] 2. Perform ion implantation of H + on the lithium niobate wafer treated in step 1 to divide the lithium niobate wafer into a residual layer, a separation layer and a piezoelectric film layer in sequence from the implantation surface. + The implanted H + ions are distributed in the separation layer to obtain a single crystal wafer implant.

[0160] The ion implantation of H + is performed with an implantation dose parameter of 5×10 13 ions / cm2, an implantation energy of 15 keV, and an implantation depth of 130 nm.

[0161] 3. Perform ion implantation of argon ions on the cleaned silicon wafer to form a damage layer of single crystal silicon with a thickness of 100 nm as a dielectric layer.

[0162] 4. Form a silicon dioxide layer on the dielectric layer by LPCVD, and then perform chemical mechanical polishing to a thickness of 100 nm to obtain a smooth surface, and perform RCA cleaning to obtain a clean surface.

[0163] 5. Contact the single crystal wafer implant with the silicon dioxide layer and bond them by direct bonding to obtain a bonded body.

[0164] 6. Place the bonded body in an annealing furnace, perform primary annealing at 100°C for 100 hours in an oxygen atmosphere, and the bonded body is separated at the separation layer to obtain a piezoelectric composite film.

[0165] 7. Perform secondary annealing of the piezoelectric composite film at 450°C for 3 hours in a hydrogen atmosphere to obtain a blackened piezoelectric composite film.

[0166] 8. Fix the blackened piezoelectric composite film on the porous ceramic chuck of the polishing equipment, perform chemical mechanical polishing on the piezoelectric film layer, and then perform RCA cleaning to obtain a clean surface.

[0167] In the blackened piezoelectric composite film prepared in Example Two, the average resistivity of the piezoelectric film layer is 2.0e 11 (Ω·m).

[0168] Example Three:

[0169] A method for blackening a piezoelectric composite film, comprising the following steps:

[0170] 1. Provide a 6-inch silicon carbide wafer and a blackened lithium tantalate wafer, fix the silicon carbide wafer or the lithium tantalate wafer on a porous ceramic chuck of a polishing device respectively, and perform chemical mechanical polishing to obtain a smooth surface, and then perform semiconductor RCA cleaning to obtain a clean surface;

[0171] 2. Perform ion implantation of nitrogen ions on the lithium tantalate wafer after step 1 to divide the lithium tantalate wafer into a residual layer, a separation layer and a piezoelectric film layer in sequence from the implantation surface, and the implanted nitrogen ions are distributed in the separation layer to obtain a single crystal wafer implantation sheet;

[0172] When implanting the nitrogen ions, the implantation dose parameters are as follows: the implantation dose is 2×10 16 ions / cm 2 , the implantation energy is 400 keV, and the implantation depth is 492 nm.

[0173] 3. Use PVD to prepare amorphous silicon with a thickness of 10 μm on the cleaned silicon carbide wafer as a dielectric layer;

[0174] 4. Use LPCVD to prepare a silicon dioxide layer on the dielectric layer, and then perform chemical mechanical polishing to obtain a smooth surface with a thickness of 10 μm, and perform RCA cleaning to obtain a clean surface;

[0175] 5. Contact the single crystal wafer implantation sheet with the silicon dioxide layer, and use direct bonding to obtain a bonded body;

[0176] 6. Place the bonded body in an annealing furnace, perform primary annealing at 300℃ for 1 hour in an oxygen atmosphere, and the bonded body is separated at the separation layer to obtain a piezoelectric composite film;

[0177] 7. Perform secondary annealing of the piezoelectric composite film at 500℃ for 4 hours in a hydrogen atmosphere to obtain a blackened piezoelectric composite film;

[0178] 8. Fix the blackened piezoelectric composite film on a porous ceramic chuck of a polishing device, perform chemical mechanical polishing on the piezoelectric film layer, and then perform RCA cleaning to obtain a clean surface.

[0179] In the blackened piezoelectric composite film prepared in Example Three, the average resistivity of the piezoelectric film layer is 2.4e 11 (Ω·m).

[0180] Example Four

[0181] A method for preparing a blackened composite film, comprising the following steps:

[0182] 1. Provide a 4-inch silicon wafer and a 400μm blackened lithium tantalate wafer, fix the silicon wafer or the lithium tantalate wafer on the porous ceramic chuck of a polishing device respectively, and perform chemical mechanical polishing to obtain a smooth surface, and then perform semiconductor RCA cleaning to obtain a clean surface;

[0183] 2. Perform ion implantation of argon ions on the lithium niobate wafer treated in step 1, so that the lithium niobate wafer is sequentially divided into a residual layer, a separation layer and a piezoelectric film layer from the implantation surface, the argon ions are distributed in the separation layer, and a single crystal wafer implantation sheet is obtained;

[0184] When the ion implantation method is used to implant argon ions, the implantation dose parameters are as follows: the implantation dose is 4×10 16 ions / cm 2 , the implantation energy is 400keV, and the implantation depth is 285nm;

[0185] 3. On the cleaned silicon wafer, amorphous silicon is prepared by PVD method, with a thickness of 500nm, i.e. a dielectric layer;

[0186] 4. A silicon dioxide layer is prepared on the dielectric layer by PECVD method, with a thickness of 5μm, then chemical mechanical polishing is performed to obtain a smooth surface, and RCA cleaning is performed to obtain a clean surface;

[0187] 5. The single crystal wafer implantation sheet is contacted with the silicon dioxide layer, and direct bonding is used to obtain a bonded body;

[0188] 6. The bonded body is placed in an annealing furnace, and is annealed at 220℃ for 3 hours in an oxygen atmosphere, so that the bonded body is separated at the separation layer, and a piezoelectric composite film is obtained;

[0189] 7. The composite film is annealed at 550℃ for 5 hours in a hydrogen atmosphere, and a blackened piezoelectric composite film is obtained;

[0190] 8. The blackened piezoelectric composite film is fixed on the porous ceramic chuck of a polishing device, and the piezoelectric film layer is subjected to chemical mechanical polishing, and then RCA cleaning is performed to obtain a clean surface.

[0191] In the blackened piezoelectric composite film prepared in Example Four, the average resistivity of the piezoelectric film layer is 2.3e 11 (Ω·m).

[0192] Example Five

[0193] A method for blackening a piezoelectric composite film, comprising the following steps:

[0194] 1. Provide a 3-inch silicon carbide wafer and blackened lithium niobate wafer, fix the silicon carbide wafer or lithium niobate wafer on the porous ceramic chuck of the polishing equipment respectively, and perform chemical mechanical polishing to obtain a smooth surface, and then perform semiconductor RCA cleaning to obtain a clean surface.

[0195] 2. The lithium niobate wafer treated in step 1 is ion implanted with He + The lithium niobate wafer is sequentially divided into a residual layer, a separation layer and a piezoelectric film layer from the implanted surface, and the implanted He + ions are distributed in the separation layer to obtain a single crystal wafer implant;

[0196] When the He+ ions are implanted by the implantation method, the implantation dose parameters are: the implantation dose is 3×10 16 ions / cm2, the implantation energy is 225 keV, and the implantation depth is 780 nm

[0197] 3. Argon ions are implanted on the cleaned silicon carbide wafer by ion implantation to form a damage layer of single crystal silicon, i.e. a dielectric layer, with a thickness of 5 μm;

[0198] 4. A silicon dioxide layer is formed on the dielectric layer by PECVD, and then chemically mechanically polished to obtain a smooth surface, with a thickness of 500 nm, and RCA cleaned to obtain a clean surface;

[0199] 5. The single crystal wafer implant is contacted with the silicon dioxide layer, and bonded by direct bonding to obtain a bonded body;

[0200] 6. The bonded body is placed in an annealing furnace, and annealed at 240℃ for 2 hours in an oxygen atmosphere for the first time, and the bonded body is separated at the separation layer to obtain a piezoelectric composite film;

[0201] 7. The piezoelectric composite film is annealed at 520℃ for 5 hours in a hydrogen atmosphere to obtain a blackened piezoelectric composite film;

[0202] 8. The blackened piezoelectric composite film is fixed on the porous ceramic chuck of the polishing equipment, and the piezoelectric film layer is chemically mechanically polished, and then RCA cleaned to obtain a clean surface.

[0203] In the blackened piezoelectric composite film prepared in Example 5, the average resistivity of the piezoelectric film layer is 1.4e 11 (Ω·m).

[0204] In the present specification, the same or similar parts between various embodiments are referred to each other, and in particular, the piezoelectric composite film corresponding to the embodiment part can be referred to the method part of suppressing the whitening of the piezoelectric composite film.

[0205] The application has been described in detail with specific reference to particular embodiments and exemplified examples, but it will be understood that these are only examples and are not intended to limit the application, as the application can be modified in various equivalent and / or functional ways and can be implemented in various examples. It will be appreciated that those skilled in the art will be able to devise numerous alternative arrangements and procedures for carrying out the application without departing from the spirit and scope of the application. The scope of the application is not to be limited by the specific examples given.

Claims

1. A method for blackening a piezoelectric composite thin film, characterized in that, include: Prepare a piezoelectric wafer and a substrate, wherein the piezoelectric wafer is a lithium niobate wafer or a lithium tantalate wafer; Ion implantation is performed on the piezoelectric wafer to sequentially divide the piezoelectric wafer into a residual mass layer, a separation layer, and a piezoelectric thin film layer. The ion-implanted piezoelectric wafer is bonded to the substrate to obtain a bonded body; The bond body is subjected to at least one alternating whitening and blackening treatment to blacken the piezoelectric thin film layer, thereby obtaining a blackened piezoelectric composite film, wherein the blackened piezoelectric composite film comprises a substrate and a blackened piezoelectric thin film layer stacked sequentially. Wherein, if the piezoelectric wafer is an untreated lithium niobate wafer or lithium tantalate wafer, the bond body undergoes a first blackening treatment, and the bond body after the first blackening treatment undergoes 2-3 alternating whitening and blackening treatments to blacken the piezoelectric thin film layer; if the piezoelectric wafer is a treated lithium niobate wafer or lithium tantalate wafer, the bond body undergoes 2-3 alternating whitening and blackening treatments to blacken the piezoelectric thin film layer. The whitening process includes: annealing the bonded body in an oxygen atmosphere to whiten the piezoelectric thin film layer, thereby obtaining a piezoelectric composite film. The piezoelectric composite film includes a substrate and a whitened piezoelectric thin film layer stacked sequentially. The blackening process includes: performing a secondary annealing treatment on the piezoelectric composite film under a hydrogen atmosphere, so that the hydrogen reacts with the oxygen in the piezoelectric film layer to form oxygen vacancies in the piezoelectric film layer, thereby blackening the whitened piezoelectric film layer to obtain a blackened piezoelectric composite film. The blackened piezoelectric composite film includes a substrate and a blackened piezoelectric film layer stacked sequentially.

2. The method according to claim 1, characterized in that, The annealing temperature of the secondary annealing process is greater than the first temperature and less than the second temperature, wherein the first temperature is the lattice recovery temperature of the piezoelectric thin film layer and the second temperature is the Curie temperature of the piezoelectric thin film layer.

3. The method according to claim 2, characterized in that, The annealing temperature for the first annealing treatment is 100℃~400℃, and the holding time for the first annealing treatment is 0.5~100 hours.

4. The method according to claim 2, characterized in that, The first temperature is at least 450°C, and the holding time for the secondary annealing treatment is 1 to 100 hours.

5. The method according to claim 1, characterized in that, After cooling the piezoelectric composite film to a preset temperature, the piezoelectric composite film is subjected to a secondary annealing treatment, wherein the preset temperature is 20-40°C. Clean the piezoelectric composite film.

6. The method according to claim 1, characterized in that, The heating rate of the first annealing process is less than the heating rate of the second annealing process.

7. A blackened piezoelectric composite film, characterized in that, The blackened piezoelectric composite film is prepared by a method for blackening a piezoelectric composite film as described in any one of claims 1-6, and the blackened piezoelectric composite film comprises a substrate and a blackened piezoelectric film layer stacked sequentially.

8. An electronic component, characterized in that, The electronic component includes the blackened piezoelectric composite film as described in claim 7.

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