Laminated film and preparation and application thereof

Abstract

The invention discloses a laminated film as well as preparation and application thereof. The laminated film comprises a (100) crystal orientation Si layer, a ZrO2 layer, a (200) crystal orientation Pt layer and a (001) crystal orientation PbZr0. 52Ti0. 48O3 layer which are sequentially laminated, the ZrO2 / Pt thin film is prepared on the silicon wafer through multiple thin film deposition methods, Pt (200) crystal face orientation growth is achieved, and a single (001) orientation PZT thin film is successfully induced.

Description

Technical Field

[0001] The present invention relates to the field of micro-electromechanical technology, and in particular to a laminated film and its preparation and application. Background Art

[0002] PZT thin film has excellent piezoelectric properties and is easy to integrate with semiconductor CMOS technology. It is currently a commonly used piezoelectric thin film material. The crystal orientation of the film is an important factor affecting the piezoelectric properties of PZT thin film. PZT thin film with (001) preferred orientation has better piezoelectric properties.

[0003] In order to obtain a PZT film with a (001) preferred orientation, a conductive oxide is first deposited as a seed layer, such as PbTiO3, PbO, etc., before preparing the PZT film; or PZT is directly induced to grow preferentially along the (001) crystal direction on the Pt (111) bottom electrode. Although a PZT film with a high (001) orientation can be obtained by depositing a seed layer, this method is relatively complex and costly, and it is not easy to induce a single orientation (001) of the PZT film on Pt (111). There are other orientations, such as (101), (110), and (111), but it is known that the (001) oriented tetragonal phase PZT film has excellent piezoelectric properties and is used in the field of micro-electromechanical systems.

[0004] Therefore, it is necessary to provide a stacked film including a single oriented (001) PZT layer to improve the piezoelectric properties of the film. Summary of the invention

[0005] In view of this, the present application provides a laminated film and its preparation and application, which are used to solve the problem of how to induce a single-oriented (001) PZT film.

[0006] In order to achieve the above technical objectives, this application adopts the following technical solutions: In a first aspect, the present application provides a laminated film, comprising a Si layer with a (100) crystal orientation, a ZrO2 layer, a Pt layer with a (200) crystal orientation, and a PbZr layer with a (001) crystal orientation, which are sequentially stacked. 0.52 Ti 0.48 O3 layer.

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

[0008] In a second aspect, the present application provides a method for preparing a laminated film, comprising the following steps: S1. Obtaining a ZrO2 layer; S2. A Pt layer with (200) crystal orientation is obtained on the surface of the ZrO2 layer; S3. In a vacuum state, the Si substrate layer with (100) crystal orientation is heated, and at the same time, the PZT colloid is prepared on the surface of the Pt layer with (200) crystal orientation by using the sol-gel method with lead acetate, zirconium nitrate, and tetrabutyl titanate as raw materials. Then, PbZr with (001) crystal orientation is deposited by spin coating, thermal decomposition, annealing and other processes. 0.52 Ti 0.48 O3 layer, a laminated film is obtained.

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

[0010] Preferably, step S1 comprises: using tetrakis(dimethylamino)zirconium (TDMAZ) and ozone (O3) as raw materials, and 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 purge time is 10-20 s, the ALD cycle number is between 40 and 400 times, the heating temperature of the Si substrate is 300-500°C; and the annealing temperature is 700-1100°C.

[0011] Preferably, step S1 comprises: using ZrO2 particles as raw material, preparing a ZrO2 layer by 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 flow rate is 2-50 sccm; the oxygen pressure is 1×10 -3 -6×10 -2 Pa.

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

[0013] Preferably, step S2 comprises: heating the Si substrate layer with a (100) crystal orientation under a vacuum state, and at the same time, sputtering a Pt layer with a (200) crystal orientation on the surface of the ZrO2 layer using a magnetron sputtering coating method with a metal Pt target as a raw material; wherein the heating temperature of the Si substrate is 100-800 °C; the sputtering power is 20-100 W, the argon gas flow rate is 20-50 sccm, and the pressure is 1.5-4 Pa.

[0014] Preferably, step S2 comprises: heating the Si substrate layer with a (100) crystal orientation under vacuum, and at the same time, using an electron beam evaporation coating method on the surface of the ZrO2 layer, using metal Pt particles as a raw material to evaporate a Pt layer with a (200) crystal orientation; wherein the heating temperature of the Si substrate is 100-800 °C; and the evaporation rate is 1-3 Å / s.

[0015] In a third aspect, the present application provides an application of a laminated film in the field of preparing piezoelectric film materials.

[0016] The beneficial effects of the present application are as follows: the present application successfully prepares a zirconium oxide film by atomic layer deposition combined with a post-annealing heat treatment process, a magnetron sputtering method or an electron beam evaporation coating method. The oxide film successfully induces the growth of the (200) crystal plane of metal Pt through temperature control. The Pt lattice constant of the (200) crystal plane has a small lattice mismatch with the PZT lattice, and a single-oriented (001) crystal orientation PZT film can be induced. The bottom electrode buffer layer of the present 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. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Schematic diagram of thin film heterostructure; Figure 2 XRD patterns of PZT films grown on Pt (111) and Pt (200) orientations. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0019] In a first aspect, the present application provides a laminated film, comprising a Si layer with a (100) crystal orientation, a ZrO2 layer, a Pt layer with a (200) crystal orientation, and a PbZr layer with a (001) crystal orientation, which are sequentially stacked. 0.52 Ti 0.48 O3 layer.

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

[0021] In a second aspect, the present application provides a method for preparing a laminated film, comprising the following steps: S1. Obtaining a ZrO2 layer; S2. A Pt layer with (200) crystal orientation is obtained on the surface of the ZrO2 layer; S3. In a vacuum state, the Si substrate layer with (100) crystal orientation is heated, and at the same time, the PZT colloid is prepared on the surface of the Pt layer with (200) crystal orientation by using the sol-gel method with lead acetate, zirconium nitrate, and tetrabutyl titanate as raw materials. Then, PbZr with (001) crystal orientation is deposited by spin coating, thermal decomposition, annealing and other processes. 0.52 Ti 0.48 O3 layer, a laminated film is obtained.

[0022] The method for obtaining the ZrO2 layer in step S1 includes but is not limited to atomic layer deposition, electron beam evaporation, and magnetron sputtering coating; the method for obtaining the (200) crystal oriented Pt layer in step S2 includes but is not limited to electron beam evaporation and magnetron sputtering.

[0023] In some embodiments, step S1 includes: using tetrakis(dimethylamino)zirconium (TDMAZ) and ozone (O3) as raw materials, and using atomic layer deposition to obtain a ZrO2 layer; 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 purge time is 10-20 s, the ALD cycle number is between 40 and 400 times, and the heating temperature of the Si substrate is 300-500 °C; the thickness of the ZrO2 layer is 10-100 nm; and the annealing temperature is 700-1100 °C.

[0024] In some embodiments, step S1 includes: using ZrO2 particles as raw materials, preparing a ZrO2 layer by 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 flow rate is 2-50 sccm; the oxygen pressure is 1×10 -3 -6×10 -2 Pa.

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

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

[0027] In some embodiments, step S2 includes: heating a Si substrate layer with a (100) crystal orientation under a vacuum state, and at the same time, using an electron beam evaporation coating method on the surface of the ZrO2 layer, using metal Pt particles as a raw material to evaporate a Pt layer with a (200) crystal orientation; wherein the heating temperature of the Si substrate is 100-800 °C; and the evaporation rate is 1-3 Å / s.

[0028] The following is a detailed description of one method for preparing a laminated film: A method for preparing a laminated film comprises the following steps: S1. In a vacuum state, a (100) oriented Si substrate layer is heated, and a ZrO2 layer is deposited by atomic layer deposition using tetrakis(dimethylamino)zirconium (TDMAZ) and ozone (O3) as raw materials, followed by rapid annealing; S2. In a vacuum state, the Si substrate layer with a (100) crystal orientation is heated, and at the same time, a Pt layer with a (200) crystal orientation is sputtered on the surface of the ZrO2 layer using a magnetron sputtering coating method with a metal Pt target as a raw material; S3. In a vacuum state, the Si substrate layer with (100) crystal orientation is heated, and at the same time, the PZT colloid is prepared on the surface of the Pt layer with (200) crystal orientation by using the sol-gel method with lead acetate, zirconium nitrate, and tetrabutyl titanate as raw materials. Then, PbZr with (001) crystal orientation is deposited by spin coating, thermal decomposition, annealing and other processes. 0.52 Ti 0.48 O3 layer, a laminated film is obtained.

[0029] Among them, step S1 generates high-quality ZrO2 through atomic layer deposition and post-annealing process, and then uses magnetron sputtering to grow the Pt electrode layer, and finally directly induces PZT (001) single orientation through Pt (200). The advantage of this application is that due to the presence of Pt (200), no seed layer is required between the bottom electrode and PZT of the stacked film, and PZT (001) single orientation growth can be achieved.

[0030] In step S1 and step S2, the vacuum degree under vacuum state is ≤1×10 -3 Pa. In step S1, the heating temperature of the Si substrate is 300-500° C. The above method is conducive to the formation of ZrO2 tetragonal and cubic phases through high temperature, and then forms Pt (200) orientation.

[0031] In step S1, 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 purge time is 10-20 s, and the ALD cycle number is between 40 and 400 times, which is used to grow a film with a thickness of 10-100 nm.

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

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

[0034] The above method grows ZrO2 by controlling the annealing temperature, and then can grow a Pt (200) single-oriented film to ultimately induce a PZT (001) single orientation.

[0035] In a third aspect, the present application provides an application of a laminated film in the field of preparing piezoelectric film materials.

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

[0037] The present solution is further described below through specific embodiments.

[0038] Example 1 A method for preparing a laminated film, comprising the following steps: S1. Place a (100) oriented Si substrate wafer in a vacuum chamber and evacuate the chamber to a vacuum of 1×10 -3 Pa; heat the substrate to 400 °C, fix the TDMAZ heating temperature at 60 °C, under the action of carrier gas N2, the TDMAZ pulse time is 0.5 s, the O3 pulse time is 2 s, the fixed N2 purge time is 20 s, and the ALD cycle number is between 80 times. After the deposition process is completed, turn off the heating device, wait for it to drop to room temperature, and take out the sample. Put the sample in the annealing furnace, anneal at 800 °C, anneal for 5 minutes, wait for it to drop to room temperature, and take out the sample; S2. Fix the sample annealed in step S1 on the magnetron sputtering sample stage, place the Pt target in the sputtering target, and evacuate the chamber until the pressure in the chamber is ≤1×10 -3 Pa, heat the substrate to 400 °C, introduce argon (Ar), and adjust the fore valve to keep the gas pressure in the chamber at 1.5 Pa; turn on the DC power supply, set the power to 40 W, and start depositing the (200) crystal orientation Pt film; after sputtering, turn off the substrate heating, wait until the substrate cools to room temperature, and introduce N2 to 1×10 5 Pa, take out the sample; S3. Fix the sample obtained in step S2 on a coating machine, spin-coat the PZT sol on the substrate, and coat the coating at a low speed of 1200 r / min for 12 s, and then coat the coating at a high speed of 3000 r / min for 20 s. Heat treat the wet film at 450°C for 6 minutes, and then anneal at 600°C for 10 minutes to obtain a laminated film.

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

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

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

[0042] Comparative Examples 1-3 A method for preparing a laminated thin film, the other contents of which are the same as those of Example 1, except that the annealing temperature of step S1 is adjusted to 600°C, 400°C, and 200°C in sequence.

[0043] Test 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 The results of Example 1 are shown in 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 Figure 2b, 2c, 2d, the Pt (200) content gradually decreases with the decrease of temperature, while the Pt (111) content gradually increases. When Pt (111) is contained, the orientation of the grown PZT is not single. This shows that PZT grows on the Pt (111) surface with a (101) preferred orientation, and Pt (200) can induce a single-oriented PZT (002). The present application successfully induces the growth of the (200) crystal plane of metal Pt through temperature control. The Pt lattice constant of the (200) crystal plane has a small lattice mismatch with the PZT lattice, and a single-oriented (002) crystal direction PZT film can be obtained.

[0044] The above are only preferred specific implementations of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A laminated film, characterized in that: The invention comprises a Si layer with a (100) crystal orientation, a ZrO2 layer, a Pt layer with a (200) crystal orientation, and a PbZr layer with a (001) crystal orientation which are sequentially stacked. 0.52 Ti 0.48 O3 layer.

2. The laminated film according to claim 1, characterized in that: The thickness of the ZrO2 layer is 10-100 nm.

3. A method for preparing a laminated film according to any one of claims 1 to 2, characterized in that: The following steps are involved: S1. Obtaining a ZrO2 layer; S2. Obtaining a Pt layer having a (200) crystal orientation on the surface of the ZrO2 layer; S3. In a vacuum state, the Si substrate layer with a (100) crystal orientation is heated, and at the same time, a PZT colloid is prepared on the surface of the Pt layer with a (200) crystal orientation using a sol-gel method with lead acetate, zirconium nitrate, and tetrabutyl titanate as raw materials, and a PbZr with a (001) crystal orientation is deposited by spin coating, thermal decomposition, annealing, and other processes. 0.52 Ti 0.48 O3 layer, and the laminated film is obtained.

4. The method for preparing the laminated film according to claim 3, characterized in that: In step S1 and step S2, the vacuum degree is ≤1×10 -3 Pa.

5. The method for preparing a laminated film according to claim 3, characterized in that: Step S1 includes: using tetrakis(dimethylamino)zirconium (TDMAZ) and ozone (O3) as raw materials, and using atomic layer deposition to obtain a ZrO2 layer; 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 purge time is 10-20 s, the ALD cycle number is between 40 and 400 times, the heating temperature of the Si substrate is 300-500°C; and the annealing temperature is 700-1100°C.

6. The method for preparing a laminated film according to claim 3, characterized in that: Step S1 comprises: using ZrO2 particles as raw materials, preparing a ZrO2 layer by 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 flow rate is 2-50 sccm; the oxygen pressure is 1×10 -3 -6×10 -2 Pa.

7. The method for preparing a laminated film according to claim 3, characterized in that: Step S1 includes: using ZrO2 target as raw material, preparing a ZrO2 layer by magnetron sputtering; wherein the heating temperature of the Si substrate is 600-1100 °C; the sputtering frequency is 30-120 W, the argon gas flow rate is 20-50 sccm, and the oxygen flow rate is 5-20 sccm; the pressure during sputtering is 1-4 Pa.

8. The method for preparing a laminated film according to claim 3, characterized in that: Step S2 includes: heating the Si substrate layer with a (100) crystal orientation under a vacuum state, and at the same time, sputtering a Pt layer with a (200) crystal orientation on the surface of the ZrO2 layer using a magnetron sputtering coating method with a metal Pt target as a raw material; wherein the heating temperature of the Si substrate is 100-800 °C; the sputtering power is 20-100 W, the argon gas flow rate is 20-50 sccm, and the pressure is 1.5-4 Pa.

9. The method for preparing a laminated film according to claim 3, characterized in that: Step S2 comprises: heating the Si substrate layer with a (100) crystal orientation under vacuum, and at the same time, using an electron beam evaporation coating method on the surface of the ZrO2 layer, using metal Pt particles as a raw material to evaporate a Pt layer with a (200) crystal orientation; wherein the heating temperature of the Si substrate is 100-800°C; and the evaporation rate is 1-3 Å / s.

10. Use of a laminated film obtained by the preparation method according to any one of claims 3 to 9 in the field of preparing piezoelectric thin film materials.

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