A laminated film and preparation and application thereof

Abstract

The application discloses a laminated film and preparation and application thereof, which comprises a Si layer with a (100) crystal direction, a ZrO2 layer, a Pt layer with a (200) crystal direction and a PbZr 0.52 Ti 0.48 O3 layer arranged in sequence; the ZrO2 / Pt film is prepared on a silicon wafer through a plurality of film deposition methods, Pt (200) crystal surface orientation growth is realized, and a single (001) oriented PZT film is successfully induced.

Description

Technical Field

[0001] This invention relates to the field of microelectromechanical technology, and in particular to a multilayer thin film and its preparation and application. Background Technology

[0002] PZT thin films possess excellent piezoelectric properties and are easily integrated with semiconductor CMOS technology, making them a commonly used piezoelectric thin film material. The crystal orientation of the thin film is an important factor affecting the piezoelectric performance of PZT thin films, and PZT thin films with preferred orientation (001) exhibit superior piezoelectric performance.

[0003] To obtain PZT films with a (001) preferred orientation, conductive oxides, such as PbTiO3 and PbO, are deposited as seed layers before PZT film preparation; or PZT is preferentially grown along the (001) crystal direction directly on the Pt (111) bottom electrode. Although PZT films with a high degree of (001) orientation can be obtained by depositing seed layers, this method is relatively complex and costly. Furthermore, it is not easy to induce a single (001) orientation of PZT films on Pt (111), and other orientations, such as (101), (110), and (111), exist. However, it is known that tetragonal PZT films with a (001) orientation have excellent piezoelectric properties and are used in the field of microelectromechanical systems (MEMS).

[0004] Therefore, it is necessary to provide a laminated thin film containing a single-oriented (001) PZT layer to improve the piezoelectric properties of the thin film. Summary of the Invention

[0005] In view of this, this application provides a multilayer thin film and its preparation and application, which solves the problem of how to induce a single-oriented (001) PZT thin film.

[0006] To achieve the above technical objectives, this application adopts the following technical solution: In a first aspect, this application provides a multilayer thin film comprising a (100) oriented Si layer, a ZrO2 layer, a (200) oriented Pt layer, and a (001) oriented PbZr layer stacked sequentially. 0.52 Ti 0.48 O3 layer.

[0007] Preferably, the thickness of the ZrO2 layer is 10-100 nm.

[0008] Secondly, this application provides a method for preparing a multilayer thin film, comprising the following steps: S1. Obtain the ZrO2 layer; S2. A Pt layer with a (200) crystal orientation was obtained on the surface of the ZrO2 layer; S3. Under vacuum, heat the (100) oriented Si substrate layer, and simultaneously prepare PZT colloid on the (200) oriented Pt layer surface using the sol-gel method with lead acetate, zirconium nitrate, and tetrabutyl titanate as raw materials. Then, deposit (001) oriented PbZr through spin coating, thermal decomposition, annealing, and other processes. 0.52 Ti 0.48 The O3 layer yields the laminated thin film.

[0009] Preferably, in steps S1 and S2, the vacuum degree is ≤1×10⁻⁶. -3 Pa.

[0010] Preferably, step S1 includes: using tetrakis(dimethylamino)zirconium (TDMAZ) and ozone (O3) as raw materials, a ZrO2 layer is obtained by atomic layer deposition; wherein the TDMAZ heating temperature is 57-63 ℃, the TDMAZ pulse time is 0.5-1 s, the O3 pulse time is 1-3 s, the fixed N2 purging time is 10-20 s, the number of ALD cycles is between 40 and 400, the Si substrate heating temperature is 300-500 ℃, and the annealing temperature is 700-1100 ℃.

[0011] Preferably, step S1 includes: preparing a ZrO2 layer using ZrO2 particles as raw material via electron beam evaporation; wherein the heating temperature of the Si substrate is 600-1100 ℃; the evaporation rate is 1-3 Å / s; the oxygen injection rate is 2-50 sccm; and the oxygen pressure is 1×10⁻⁶. -3 -6×10 -2 Pa.

[0012] Preferably, step S1 includes: preparing a ZrO2 layer using a ZrO2 target as raw material by magnetron sputtering; wherein the heating temperature of the Si substrate is 600-1100 ℃; the sputtering frequency is 30-120 W; the argon gas flow rate is 20-50 sccm, the oxygen gas flow rate is 5-20 sccm; and the sputtering pressure is 1-4 Pa.

[0013] Preferably, step S2 includes: heating a (100) oriented Si substrate layer under vacuum, and simultaneously sputtering a (200) oriented Pt layer on the ZrO2 layer surface using a magnetron sputtering method with a Pt metal target as the raw material; wherein the heating temperature of the Si substrate is 100-800 ℃; the sputtering power is 20-100 W, the argon flow rate is 20-50 sccm, and the pressure is 1.5-4 Pa.

[0014] Preferably, step S2 includes: heating a (100) oriented Si substrate layer under vacuum, and simultaneously evaporating a (200) oriented Pt layer on the surface of the ZrO2 layer using an electron beam evaporation deposition method with Pt particles as raw material; wherein the heating temperature of the Si substrate is 100-800 ℃; and the evaporation rate is 1-3 Å / s.

[0015] Thirdly, this application provides an application of a multilayer thin film in the preparation of piezoelectric thin film materials.

[0016] The beneficial effects of this application are as follows: This application successfully prepared a zirconium oxide thin film by atomic layer deposition combined with post-annealing heat treatment, magnetron sputtering or electron beam evaporation coating. The oxide thin film successfully induced the growth of the (200) crystal plane of metal Pt by temperature control. The lattice constant of Pt on the (200) crystal plane has a small mismatch with the lattice of PZT, and a single-oriented (001) crystal orientation PZT thin film can be induced. The bottom electrode buffer layer of this application is prepared by atomic layer deposition, electron beam evaporation coating or magnetron sputtering coating. The preparation method is simple and can be prepared on a 4-inch wafer. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of a thin film heterostructure; Figure 2 XRD of PZT films grown in Pt(111) and Pt(200) orientations, respectively. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0019] In a first aspect, this application provides a multilayer thin film comprising a (100) oriented Si layer, a ZrO2 layer, a (200) oriented Pt layer, and a (001) oriented PbZr layer stacked sequentially. 0.52 Ti 0.48 O3 layer.

[0020] Preferably, the thickness of the ZrO2 layer is 10-100 nm.

[0021] Secondly, this application provides a method for preparing a multilayer thin film, comprising the following steps: S1. Obtain the ZrO2 layer; S2. A Pt layer with a (200) crystal orientation was obtained on the surface of the ZrO2 layer; S3. Under vacuum, heat the (100) oriented Si substrate layer, and simultaneously prepare PZT colloid on the (200) oriented Pt layer surface using the sol-gel method with lead acetate, zirconium nitrate, and tetrabutyl titanate as raw materials. Then, deposit (001) oriented PbZr through spin coating, thermal decomposition, annealing, and other processes. 0.52 Ti 0.48 The O3 layer yields the laminated thin film.

[0022] The methods for obtaining the ZrO2 layer in step S1 include, but are not limited to, atomic layer deposition, electron beam evaporation, and magnetron sputtering; the methods for obtaining the Pt layer with the (200) crystal orientation in step S2 include, but are not limited to, electron beam evaporation and magnetron sputtering.

[0023] In some embodiments, step S1 includes: obtaining a ZrO2 layer using tetrakis(dimethylamino)zirconium (TDMAZ) and ozone (O3) as raw materials via atomic layer deposition; wherein the TDMAZ heating temperature is 57-63 °C, the TDMAZ pulse time is 0.5-1 s, the O3 pulse time is 1-3 s, the fixed N2 purging time is 10-20 s, the number of ALD cycles is between 40 and 400, the Si substrate heating temperature is 300-500 °C, the ZrO2 layer thickness is 10-100 nm, and the annealing temperature is 700-1100 °C.

[0024] In some embodiments, step S1 includes: preparing a ZrO2 layer using ZrO2 particles as raw material via electron beam evaporation; wherein the heating temperature of the Si substrate is 600-1100 °C; the evaporation rate is 1-3 Å / s; the oxygen injection rate is 2-50 sccm; and the oxygen pressure is 1×10⁻⁶. -3 -6×10 -2 Pa.

[0025] In some embodiments, step S1 includes: preparing a ZrO2 layer using a ZrO2 target as raw material by magnetron sputtering; wherein the heating temperature of the Si substrate is 600-1100 ℃; the sputtering power is 30-120 W; the argon gas flow rate is 20-50 sccm, the oxygen gas flow rate is 5-20 sccm; and the sputtering pressure is 1-4 Pa.

[0026] In some embodiments, step S2 includes: heating a (100) oriented Si substrate layer under vacuum, and simultaneously sputtering a (200) oriented Pt layer on the surface of the ZrO2 layer using a magnetron sputtering method with a metal Pt target as the raw material; wherein the heating temperature of the Si substrate is 100-800 ℃; the sputtering power is 20-100 W, the argon flow rate is 20-50 sccm, and the pressure is 1.5-4 Pa.

[0027] In some embodiments, step S2 includes: heating a (100) oriented Si substrate layer under vacuum, and simultaneously evaporating a (200) oriented Pt layer on the surface of the ZrO2 layer using an electron beam evaporation deposition method with Pt particles as raw material; wherein the heating temperature of the Si substrate is 100-800 ℃; and the evaporation rate is 1-3 Å / s.

[0028] The following is a detailed description of one method for preparing laminated thin films: A method for preparing a multilayer thin film includes the following steps: S1. Under vacuum, heat the (100) crystal orientation Si substrate and simultaneously deposit a ZrO2 layer using tetra(dimethylamino)zirconium (TDMAZ) and ozone (O3) as raw materials by atomic layer deposition, and then perform rapid annealing. S2. Under vacuum, heat the (100) crystal orientation Si substrate layer, and at the same time, use magnetron sputtering to deposit a (200) crystal orientation Pt layer on the ZrO2 layer surface using a metal Pt target as raw material. S3. Under vacuum, heat the (100) oriented Si substrate layer, and simultaneously prepare PZT colloid on the (200) oriented Pt layer surface using the sol-gel method with lead acetate, zirconium nitrate, and tetrabutyl titanate as raw materials. Then, deposit (001) oriented PbZr through spin coating, thermal decomposition, annealing, and other processes. 0.52 Ti 0.48 The O3 layer yields the laminated thin film.

[0029] In step S1, high-quality ZrO2 is generated through atomic layer deposition and post-annealing processes, and then Pt electrode layer is grown by magnetron sputtering. Finally, PZT (001) single orientation is directly induced by Pt (200). The advantage of this application is that, due to the presence of Pt (200), no seed layer is needed between the bottom electrode of the stacked film and PZT, so that PZT (001) single orientation growth can be achieved.

[0030] In steps S1 and S2, the vacuum level under vacuum conditions is ≤1×10⁻⁶. -3 Pa. In step S1, the heating temperature of the Si substrate is 300-500 ℃. The above method uses high temperature to facilitate the formation of tetragonal and cubic ZrO2 phases, thereby forming Pt(200) orientation.

[0031] In step S1, the TDMAZ heating temperature is 57-63 ℃, the TDMAZ pulse time is 0.5-1 s, the O3 pulse time is 1-3 s, the fixed N2 purging time is 10-20 s, and the ALD cycle number is between 40 and 400 times, which is used to grow thin films with a thickness of 10-100 nm.

[0032] In step S1, the annealing temperature is 700-1100 ℃.

[0033] In step S2, the heating temperature of the Si substrate is 100-800 ℃. Within this temperature range, it is advantageous to obtain a single orientation of Pt(200).

[0034] The above method grows ZrO2 by controlling the annealing temperature, which in turn can grow a Pt (200) single-oriented thin film, ultimately inducing a PZT (001) single-oriented film.

[0035] Thirdly, this application provides an application of a multilayer thin film in the preparation of piezoelectric thin film materials.

[0036] The PZT thin film prepared in this application has spontaneous polarization with a (001) single orientation, and the PZT thin film with this orientation has excellent piezoelectric properties.

[0037] The following specific embodiments further illustrate this solution.

[0038] Example 1 A method for preparing a multilayer thin film, comprising the following steps: S1. Place the (100) oriented Si substrate wafer in a vacuum chamber and evacuate to 1×10⁻⁶. -3 Pa; The substrate was heated to 400 °C, the TDMAZ heating temperature was fixed at 60 °C, the TDMAZ pulse time was 0.5 s under the action of N2 carrier gas, the O3 pulse time was 2 s, the N2 purging time was fixed at 20 s, and the ALD cycle count was between 80. After the deposition process was completed, the heating device was turned off, and the sample was taken out after cooling to room temperature. The sample was then placed in an annealing furnace at 800 °C for 5 minutes, and after cooling to room temperature, the sample was taken out. S2. Fix the annealed sample from step S1 onto the magnetron sputtering sample stage, place the Pt target into the sputtering target, and evacuate the chamber until the pressure inside the chamber is ≤1×10⁻⁶. -3 At Pa, the substrate is heated to 400 °C, argon (Ar) gas is introduced, and the pre-stage valve is adjusted to maintain the gas pressure in the chamber at 1.5 Pa; the DC power supply is turned on and the power is set to 40 W, and the deposition of (200) oriented Pt thin film begins; after sputtering is completed, the substrate heating is turned off, and after the substrate cools to room temperature, N2 is introduced into the chamber to 1×10⁻⁶ Pa. 5 Pa, take out the sample; S3. Fix the sample obtained in step S2 on a spin coater, spin coat the PZT sol onto the substrate, spin coat at a low speed of 1200 r / min for 12 s, and then spin coat at a high speed of 3000 r / min for 20 s. Heat treat the wet film at 450 ℃ for 6 minutes, and then anneal at 600 ℃ for 10 minutes to obtain the laminated film.

[0039] Example 2 A method for preparing a multilayer thin film, comprising the following steps: S1. Place the (100) oriented Si substrate wafer in a vacuum chamber and evacuate to 1×10⁻⁶. -3 Pa; Heat the substrate to 700 °C, turn on the electron gun, set the evaporation rate to 2 Å / s, and introduce 10 sccm of oxygen to begin evaporating and depositing the ZrO2 layer. After the deposition process is complete, turn off the heating device, wait for it to cool to room temperature, and then remove the sample; S2. Fix the sample from step S1 onto the magnetron sputtering sample stage, place the Pt target into the sputtering target, and evacuate the chamber until the pressure inside the chamber is ≤1×10⁻⁶. -3 At Pa, the substrate is heated to 400 °C, argon (Ar) gas is introduced, and the pre-stage valve is adjusted to maintain the gas pressure in the chamber at 1.5 Pa; the DC power supply is turned on and the power is set to 40 W, and the deposition of (200) oriented Pt thin film begins; after sputtering is completed, the substrate heating is turned off, and after the substrate cools to room temperature, N2 is introduced into the chamber to 1×10⁻⁶ Pa. 5 Pa, take out the sample; S3. Fix the sample obtained in step S2 on a spin coater, spin coat the PZT sol onto the substrate, spin coat at a low speed of 1200 r / min for 12 s, and then spin coat at a high speed of 3000 r / min for 20 s. Heat treat the wet film at 450 ℃ for 6 minutes, and then anneal at 600 ℃ for 10 minutes to obtain the laminated film.

[0040] Example 3 A method for preparing a multilayer thin film, comprising the following steps: S1. Place the (100) oriented Si substrate wafer in a vacuum chamber, place the ZrO2 target and Pt target into the sputtering target, and evacuate to 1×10⁻⁶. -3 Pa; Heat the substrate to 700 °C, turn on the RF power supply, set the sputtering power to 50 W, argon flow rate to 40 sccm, oxygen flow rate to 10 sccm, and pressure to 2 Pa, and deposit a ZrO2 layer. After the deposition process is complete, stop the gas supply and turn off the heating device; S2. Heat the sample from step S1 to 400 °C, introduce argon (Ar) gas, and adjust the pre-stage valve to maintain the gas pressure in the chamber at 1.5 Pa; turn on the DC power supply, set the power to 40 W, and begin depositing the (200) oriented Pt thin film; after sputtering is complete, turn off the substrate heating, wait for the substrate to cool to room temperature, and introduce N2 into the chamber to 1 × 10⁻⁶ Pa. 5 Pa, take out the sample; S3. Fix the sample obtained in step S2 on a spin coater, spin coat the PZT sol onto the substrate, spin coat at a low speed of 1200 r / min for 12 s, and then spin coat at a high speed of 3000 r / min for 20 s. Heat treat the wet film at 450 ℃ for 6 minutes, and then anneal at 600 ℃ for 10 minutes to obtain the laminated film.

[0041] Example 4 A method for preparing a multilayer thin film, comprising the following steps: S1. Place the (100) oriented Si substrate wafer in a vacuum chamber and evacuate to 1×10⁻⁶. -3 Pa; Heat the substrate to 700 °C, turn on the electron gun, set the evaporation rate to 2 Å / s, and introduce 10 sccm of oxygen to begin evaporating and depositing the ZrO2 layer. After the deposition process is complete, turn off the heating device; S2. Heat the sample from step S1 to 400 °C, switch to the crucible containing Pt particles, turn on the electron gun, set the evaporation rate to 1.8 Å / s, and begin evaporating and depositing the Pt layer; after evaporation is complete, turn off the substrate heating, wait for the substrate to cool to room temperature, and then introduce N2 into the chamber to 1 × 10⁻⁶ Å. 5 Pa, take out the sample; S3. Fix the sample obtained in step S2 on a spin coater, spin coat the PZT sol onto the substrate, spin coat at a low speed of 1200 r / min for 12 s, and then spin coat at a high speed of 3000 r / min for 20 s. Heat treat the wet film at 450 ℃ for 6 minutes, and then anneal at 600 ℃ for 10 minutes to obtain the laminated film.

[0042] Comparative Examples 1-3 A method for preparing a multilayer thin film is the same as in Example 1, except that the annealing temperature in step S1 is adjusted sequentially to 600 ℃, 400 ℃, and 200 ℃.

[0043] Testing and Evaluation The XRD patterns of the PZT layer in the laminated films obtained in Example 1 and Comparative Example 1 are as follows: Figure 2 As shown. The results of Example 1 are shown in [the original text]. Figure 2 a, indicating that the single orientation of Pt(200) can induce the single orientation of PZT(002); the results of comparative examples 1-3 correspond to the following respectively. Figure 2b, 2c, 2d, the Pt(200) content gradually decreases with decreasing temperature, while the Pt(111) content gradually increases. When Pt(111) is present, the orientation of the grown PZT is not uniform. This indicates that PZT growing on the Pt(111) surface has a preferred (101) orientation, and Pt(200) can induce a single-orientation PZT(002). In this application, the growth of the (200) crystal plane of metallic Pt was successfully induced by temperature control. The lattice constant of Pt on the (200) crystal plane has a small mismatch with the lattice of PZT, and a single-orientation (002) crystal orientation PZT thin film can be obtained.

[0044] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a multilayer thin film, characterized in that, Includes the following steps: S1. Obtain a ZrO2 layer on a Si substrate with a (100) crystal orientation; S2. A Pt layer with a (200) crystal orientation is obtained on the surface of the ZrO2 layer; S3. Under vacuum, the (100) oriented Si substrate is heated, and simultaneously, PZT colloid is prepared on the surface of the (200) oriented Pt layer using a sol-gel method with lead acetate, zirconium nitrate, and tetrabutyl titanate as raw materials. Then, PbZr in the (001) oriented direction is deposited through spin coating, thermal decomposition, and annealing processes. 0.52 Ti 0.48 O3 layer, thus obtaining the stacked film; Step S1 includes: heating the Si substrate to 300-500 °C, and using tetrakis(dimethylamino)zirconium (TDMAZ) and ozone (O3) as raw materials, obtaining a ZrO2 layer by atomic layer deposition; wherein, the TDMAZ heating temperature is 57-63 °C, the TDMAZ pulse time is 0.5-1 s, the O3 pulse time is 1-3 s, the fixed N2 purging time is 10-20 s, and the number of ALD cycles is between 40 and 400; after the deposition process is completed, annealing is performed at a temperature of 700-1100 °C.

2. The method for preparing the multilayer thin film according to claim 1, characterized in that, In steps S1 and S2, the vacuum degree is ≤1×10 -3 Pa.

3. The method for preparing a multilayer thin film according to claim 1, characterized in that, The thickness of the ZrO2 layer is 10-100 nm.

4. The method for preparing the multilayer thin film according to claim 1, characterized in that, Step S2 includes: heating a (100) oriented Si substrate under vacuum, and simultaneously sputtering a (200) oriented Pt layer onto the ZrO2 layer surface using a magnetron sputtering method with a Pt metal target as the raw material; wherein the heating temperature of the Si substrate is 100-800 ℃; the sputtering power is 20-100 W, the argon flow rate is 20-50 sccm, and the pressure is 1.5-4 Pa.

5. The method for preparing the multilayer thin film according to claim 1, characterized in that, Step S2 includes: heating a (100) oriented Si substrate layer under vacuum, and simultaneously evaporating a (200) oriented Pt layer on the surface of the ZrO2 layer using an electron beam evaporation deposition method with Pt particles as raw material; wherein the heating temperature of the Si substrate layer is 100-800 ℃; and the evaporation rate is 1-3 Å / s.

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