CN103956266A - A lead-free Bi0.5Na0.5TiO3 based film capacitor with high energy storage density and its preparation method - Google Patents

Abstract

The invention relates to a lead-free Bi _0.5 Na _0.5 TiO ₃ -based high energy storage density film capacitor and a preparation method thereof, comprising sputtering a metal lower electrode on a substrate silicon chip, sputtering a Bi _0.5 Na _0.5 TiO ₃ -based high energy storage density The middle layer of the film and the sputtered metal upper electrode on the film form a three-layer structure. The Bi _0.5 Na _0.5 TiO ₃ -based high energy storage density film layer is specifically composed of (1-x)(0.94Bi _0.5 Na _0.5 TiO ₃ -0.06BaTiO ₃ )-xK _0.5 Na _0.5 NbO ₃ (0.01≤x≤0.1); The upper and lower electrode materials are one of metal Ag, Au and Pt. Prepare the (1-x)(0.94Bi _0.5 Na _0.5 TiO ₃ -0.06BaTiO ₃ )-xK _0.5 Na _0.5 NbO ₃ ceramic target first, and then use the magnetron sputtering process to sputter it onto the sputtered metal lower electrode A Bi _0.5 Na _0.5 TiO ₃ -based high energy storage density thin film layer is formed on a silicon wafer substrate; and then a metal upper electrode is prepared on the thin film by sputtering process. The high-energy-storage-density film capacitor prepared by the invention has a small volume, a film layer thickness of 0.5-1.5 μm, and an energy-storage density of 20-45J/cm ³ .

Description

A lead-free Bi0.5Na0.5TiO3 based film capacitor with high energy storage density and its preparation method

technical field

The invention belongs to the field of energy storage capacitor manufacturing, and in particular relates to a lead-free Bi _0.5 Na _0.5 TiO ₃ -based film capacitor with high energy storage density and a preparation method thereof.

Background technique

According to the definition of classical electromagnetic theory, the energy storage density of a material refers to the electric energy contained in a unit volume, and the commonly used unit is J/cm ³ . Under the electric field whose electric field strength is E, the energy change caused by the small change dD of the electric displacement D is EdD. The energy storage density can be expressed by formula (1):

$\mathrm{<span\; class="notranslate">\; J</span>}<span\; class="notranslate">\; =</span>{<span\; class="notranslate">\; \&Integral;</span>}_{\mathrm{<span\; class="notranslate">\; 0</span>}}^{{\mathrm{<span\; class="notranslate">\; D.</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}}\mathrm{<span\; class="notranslate">\; EdD</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

In the formula: J is the energy storage density, and _Dmax is the electric displacement under the saturation field strength.

For ferroelectric and antiferroelectric dielectrics, the energy storage density depends on the size of the breakdown field strength, the difference between the remnant polarization and the saturation polarization, and the closed area of the hysteresis loop. Therefore, it is necessary to make the saturation polarization P _s of the upper section of the hysteresis loop of the material as large as possible (that is, E as high as possible), and the remanent polarization P _r as small as possible, so as to increase the energy storage value. For the dielectric in which the hysteresis loop is approximately a straight line, the energy storage density is:

$\mathrm{<span\; class="notranslate">\; D.</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}{\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}{\mathrm{<span\; class="notranslate">\; E.</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

Formula (2) means that the energy storage material whose hysteresis loop is approximately linear, the greater the dielectric constant, the greater the withstand voltage E, and the higher the energy storage density. Therefore, high energy storage density materials should have the characteristics of high dielectric constant, high withstand voltage, large area above the hysteresis loop, and low loss.

High-density energy storage capacitors have the advantages of high energy storage density, fast charge and discharge speed, anti-cycle aging, suitable for extreme environments such as high temperature and high pressure, and stable performance. They meet the requirements of new energy development and utilization, and are widely used in electronic power equipment. It plays an increasingly important role in the pulse power system, especially the large beam excitation system generated by high-energy laser. The development and application of high energy storage density dielectric materials has a history of more than 50 years, and has been used in military applications such as laser tanks, directed energy weapons, electrified launch platforms, and comprehensive all-electric propulsion ships. In terms of civil use, high-density energy storage capacitors are also an indispensable part of new energy power generation systems such as wind energy and solar energy, and inverter equipment for hybrid vehicles. However, due to the low energy storage density of existing dielectric materials, energy storage capacitors account for the entire inverter. The volume of the variable equipment is quite large. In order to meet the needs of future lightweight, miniaturized and highly integrated electronic equipment, it means that energy storage capacitors with higher storage density must be developed to meet military and civilian applications.

Among the high-density energy storage capacitors currently researched and developed, ceramics, glass, and ceramic organic composites are mostly three types. However, these three types are all bulk materials. Although the withstand voltage is high, the energy storage density achieved is lower than 5J/cm ^3. It is difficult to realize the industrial demand for high-power drive of small devices. Based on this, the researchers developed a high-density energy storage film capacitor, using the antiferroelectric Pb(Zr,Ti)O ₃ system as the film dielectric matrix, and initially achieved a high energy storage density value of nearly 60J/cm ³ . However, the high toxicity of lead also means that it is difficult to be used in the civilian field, so it is necessary to find new lead-free materials with high energy storage density as the substrate for the preparation of thin films.

Contents of the invention

The object of the present invention is to provide a lead-free Bi _0.5 Na _0.5 TiO ₃ based high energy storage density film capacitor and its preparation method, the thickness of the middle film layer of the capacitor is between 0.5-1.5 μm, and the energy storage density can reach 20-20 μm. 45J/cm ³ .

The purpose of the present invention is achieved through the following technical solutions:

A lead-free Bi _0.5 Na _0.5 TiO ₃ based high energy storage density thin film capacitor consists of a sputtered metal lower electrode sequentially stacked on the substrate material, a sputtered Bi _0.5 Na _0.5 TiO ₃ based high energy storage density thin film intermediate layer It consists of a three-layer structure of a metal upper electrode sputtered on a thin film.

The specific composition of the Bi _0.5 Na _0.5 TiO ₃ -based high energy storage density film is (1-x)(0.94Bi _0.5 Na _0.5 TiO ₃ -0.06BaTiO ₃ )-xK _0.5 Na _0.5 NbO ₃ , wherein the value of the molar ratio x 0.01≤x≤0.1, and the thickness of the film is between 0.5 and 1.5 μm.

The metal upper and lower electrode materials are one of metal Ag, Au and Pt, and the thickness thereof is 200nm to 500nm.

A method for preparing a lead-free Bi _0.5 Na _0.5 TiO ₃ based high energy storage density film capacitor, comprising the steps of:

1) Preparation of (1-x)(0.94Bi _0.5 Na _0.5 TiO ₃ -0.06BaTiO ₃ )-x K _0.5 Na _0.5 NbO ₃ ceramic target for sputtering: select high-purity (≧99.8%) Bi ₂ O ₃ , TiO ₂ , Na ₂ CO ₃ , BaCO ₃ , K ₂ CO ₃ , and Nb ₂ O ₅ powders are used as raw materials, according to Bi ₂ O ₃ : TiO ₂ : Na ₂ CO ₃ : BaCO ₃ : K ₂ CO ₃ : Nb ₂ O ₅ =0.235(1-x):(1-x):[0.235(1-x)+0.25x]:0.06(1-x):0.25x:0.5x molar ratio mixing, and then fully mixed in a high energy ball mill , taken out, dried, ground, and kept at 900°C for 4 hours to synthesize (1-x)(0.94Bi _0.5 Na _0.5 TiO ₃ -0.06BaTiO ₃ )-x K _0.5 Na _0.5 NbO ₃ powder; Secondary ball milling in the ball mill, drying, adding 5wt% polyvinyl alcohol (PVA) as a binder, drying, pressing on a hydraulic press to form a green body with a diameter of 80mm and a thickness of 5mm, and keeping the green body at 1100°C for 12 Sintering at high temperature for 1 hour to obtain a highly dense (1-x) (0.94Bi _0.5 Na _0.5 TiO ₃ -0.06BaTiO ₃ )-x K _0.5 Na _0.5 NbO ₃ ceramic target for sputtering;

2) Put the cleaned substrate silicon wafer and metal target into the magnetron sputtering apparatus, and prepare the lower electrode by DC magnetron sputtering the metal target. The DC power is 80W, the argon pressure is 0.8Pa, and the substrate temperature is room temperature. The thickness of the bottom electrode is 200nm to 500nm;

3) Put the machined sputtering target (Φ60×3mm) into the magnetron sputtering apparatus, clean the substrate silicon wafer that has sputtered the lower electrode and put it into the sputtering chamber, use RF power 150W, argon The gas pressure is 0.6Pa, and the substrate temperature is 300°C. The (1-x)(0.94Bi _0.5 Na _0.5 TiO ₃ -0.06BaTiO ₃ )-x K _0.5 Na _0.5 NbO ₃ film prepared by sputtering has a thickness of 0.5-1.5 μm. Finally, the in-situ film is annealed in air at a temperature ranging from 500 to 800°C for 60 minutes, and then the crystalline state (1-x) (0.94Bi _0.5 Na _0.5 TiO ₃ -0.06BaTiO ₃ )-x K _0.5 Na _0.5 NbO ₃ high energy storage density film;

4) Using a metal mask, the diameter of the round hole is 1mm, and the magnetron sputtering is used in (1-x)(0.94Bi _0.5 Na _0.5 TiO ₃ -0.06BaTiO ₃ )-x K _0.5 Na _0.5 NbO ₃ high energy storage Prepare the metal upper electrode on the surface of the density film, the DC power is 80W, the argon pressure is 0.8Pa, the substrate temperature is room temperature, the thickness of the upper electrode is 200nm to 500nm, and finally the metal lower electrode/Bi _0.5 Na _0.5 TiO ₃ base with high energy storage density is formed Lead-free Bi _0.5 Na _0.5 TiO ₃ -based high energy storage density film capacitor with film/metal top electrode three-layer structure.

The advantages of the invention are: the high energy storage density film capacitor prepared by the invention has small volume, the thickness of the film layer is 0.5-1.5 μm, and the energy storage density is 20-45J/cm ³ .

Detailed ways

The present invention is described below based on seven specific embodiments. Those skilled in the art can understand that these examples are only for the purpose of illustrating the present invention, rather than limiting the scope of the present invention.

Example 1:

1) Preparation of 0.99(0.94Bi _0.5 Na _0.5 TiO ₃ -0.06BaTiO ₃ )-0.01K _0.5 Na _0.5 NbO ₃ ceramic target for sputtering: select high-purity (≧99.8%) Bi ₂ O ₃ , TiO ₂ , Na ₂ CO ₃ , BaCO ₃ , K ₂ CO ₃ , Nb ₂ O ₅ powder as raw materials, according to Bi ₂ O ₃ : TiO ₂ : Na ₂ CO ₃ : BaCO ₃ : K ₂ CO ₃ : Nb ₂ O ₅ =0.23265:0.99 : 0.23515: 0.0594: 0.0025: 0.005 molar ratio mixed, then fully mixed in a high-energy ball mill, taken out, dried, ground, and kept at 900 ° C for 4 hours to synthesize 0.99 (0.94Bi _0.5 Na _0.5 TiO ₃ -0.06BaTiO ₃ )- 0.01K _0.5 Na _0.5 NbO ₃ powder; mill the resulting powder in a high-energy ball mill for a second time, dry it, add 5wt% polyvinyl alcohol (PVA) as a binder, dry it, and press it into a diameter of 80mm on a hydraulic press , a green body with a thickness of 5mm, and the green body was sintered at 1100°C for 12 hours at a high temperature to obtain a highly dense 0.99(0.94Bi _0.5 Na _0.5 TiO ₃ -0.06BaTiO ₃ )-0.01K _0.5 Na _0.5 NbO ₃ for sputtering Ceramic target.

2) Put the cleaned substrate silicon wafer and the metal Pt target into the magnetron sputtering apparatus, and prepare the lower electrode by DC magnetron sputtering the metal Pt target. The DC power is 80W, the argon pressure is 0.8Pa, and the substrate temperature is At room temperature, the Pt thickness of the bottom electrode is 220nm.

3) Put the machined sputtering target (Φ60×3mm) into the magnetron sputtering apparatus, clean the substrate silicon wafer on which the Pt lower electrode has been sputtered and put it into the sputtering chamber, using a radio frequency power of 150W, The argon pressure is 0.6Pa, and the substrate temperature is 300°C. Finally, the in-situ film was annealed in air at a temperature of 800°C for 60 minutes, and then a crystalline 0.99(0.94Bi _0.5 Na _0.5 TiO ₃ -0.06BaTiO ₃ )-0.01K _0.5 Na _0.5 NbO ₃ high energy storage density film was obtained .

4) Using a metal mask, the diameter of the round hole is 1mm, and magnetron sputtering is used on the surface of the 0.99(0.94Bi _0.5 Na _0.5 TiO ₃ -0.06BaTiO ₃ )-0.01K _0.5 Na _0.5 NbO ₃ high energy storage density film The metal Ag upper electrode was prepared, the DC power was 80W, the argon pressure was 0.8Pa, the substrate temperature was room temperature, and the Ag thickness of the upper electrode was 250nm. Finally, a high energy storage density film capacitor with a three-layer structure of metal Pt bottom electrode/0.99 (0.94Bi _0.5 Na _0.5 TiO ₃ -0.06BaTiO ₃ )-0.01K _0.5 Na _0.5 NbO ₃ high energy storage density film/metal Ag top electrode is formed.

Performance test results: the thickness of the film is about 0.5 μm, and the energy storage density is about 26J/cm ³ .

Example 2:

1) Preparation of 0.97(0.94Bi _0.5 Na _0.5 TiO ₃ -0.06BaTiO ₃ )-0.03K _0.5 Na _0.5 NbO ₃ ceramic target for sputtering: select high-purity (≧99.8%) Bi ₂ O ₃ , TiO ₂ , Na ₂ CO ₃ , BaCO ₃ , K ₂ CO ₃ , Nb ₂ O ₅ powder as raw materials, according to Bi ₂ O ₃ : TiO ₂ : Na ₂ CO ₃ : BaCO ₃ : K ₂ CO ₃ : Nb ₂ O ₅ =0.22795:0.97 : 0.23545: 0.0582: 0.0075: 0.015 molar ratio mixed, then fully mixed in a high-energy ball mill, taken out, dried, ground, and kept at 900 ° C for 4 hours to synthesize 0.97 (0.94Bi _0.5 Na _0.5 TiO ₃ -0.06BaTiO ₃ )- 0.03K _0.5 Na _0.5 NbO ₃ powder; mill the resulting powder in a high-energy ball mill for a second time, dry it, add 5wt% polyvinyl alcohol (PVA) as a binder, dry it, and press it into a diameter of 80mm on a hydraulic press , a green body with a thickness of 5mm, and the green body was sintered at 1100°C for 12 hours at a high temperature to obtain a highly dense 0.97(0.94Bi _0.5 Na _0.5 TiO ₃ -0.06BaTiO ₃ )-0.03K _0.5 Na _0.5 NbO ₃ for sputtering Ceramic target.

2) Put the cleaned substrate silicon wafer and the metal Pt target into the magnetron sputtering apparatus, and prepare the lower electrode by DC magnetron sputtering the metal Pt target. The DC power is 80W, the argon pressure is 0.8Pa, and the substrate temperature is At room temperature, the Pt thickness of the bottom electrode is 360nm.

3) Put the machined sputtering target (Φ60×3mm) into the magnetron sputtering apparatus, clean the substrate silicon wafer on which the Pt lower electrode has been sputtered and put it into the sputtering chamber, using a radio frequency power of 150W, The argon pressure is 0.6Pa, and the substrate temperature is 300°C. Finally, the in-situ film was annealed in air at a temperature of 650°C for 60 minutes to obtain a crystalline 0.97(0.94Bi _0.5 Na _0.5 TiO ₃ -0.06BaTiO ₃ )-0.03K _0.5 Na _0.5 NbO ₃ high energy storage density film .

4) Using a metal mask, the diameter of the round hole is 1mm, and the surface of the 0.97(0.94Bi _0.5 Na _0.5 TiO ₃ -0.06BaTiO ₃ )-0.03K _0.5 Na _0.5 NbO ₃ high energy storage density film is sputtered by magnetron The metal Au upper electrode was prepared, the DC power was 80W, the argon pressure was 0.8Pa, the substrate temperature was room temperature, and the Au thickness of the upper electrode was 310nm. Finally, a high energy storage density film capacitor with a three-layer structure of metal Pt bottom electrode/0.97(0.94Bi _0.5 Na _0.5 TiO ₃ -0.06BaTiO ₃ )-0.03K _0.5 Na _0.5 NbO ₃ high energy storage density film/metal Au top electrode is formed.

Performance test results: the thickness of the film is about 1.5 μm, and the energy storage density is about 45J/cm ³ .

Example 3:

1) Preparation of 0.97(0.94Bi _0.5 Na _0.5 TiO ₃ -0.06BaTiO ₃ )-0.03K _0.5 Na _0.5 NbO ₃ ceramic target for sputtering: select high-purity (≧99.8%) Bi ₂ O ₃ , TiO ₂ , Na ₂ CO ₃ , BaCO ₃ , K ₂ CO ₃ , Nb ₂ O ₅ powder as raw materials, according to Bi ₂ O ₃ : TiO ₂ : Na ₂ CO ₃ : BaCO ₃ : K ₂ CO ₃ : Nb ₂ O ₅ =0.22795:0.97 : 0.23545: 0.0582: 0.0075: 0.015 molar ratio mixed, then fully mixed in a high-energy ball mill, taken out, dried, ground, and kept at 900 ° C for 4 hours to synthesize 0.97 (0.94Bi _0.5 Na _0.5 TiO ₃ -0.06BaTiO ₃ )- 0.03K _0.5 Na _0.5 NbO ₃ powder; mill the resulting powder in a high-energy ball mill for a second time, dry it, add 5wt% polyvinyl alcohol (PVA) as a binder, dry it, and press it into a diameter of 80mm on a hydraulic press , a green body with a thickness of 5mm, and the green body was sintered at 1100°C for 12 hours at a high temperature to obtain a highly dense 0.97(0.94Bi _0.5 Na _0.5 TiO ₃ -0.06BaTiO ₃ )-0.03K _0.5 Na _0.5 NbO ₃ for sputtering Ceramic target.

2) Put the cleaned substrate silicon wafer and the metal Pt target into the magnetron sputtering apparatus, and prepare the lower electrode by DC magnetron sputtering the metal Pt target. The DC power is 80W, the argon pressure is 0.8Pa, and the substrate temperature is At room temperature, the Pt thickness of the bottom electrode is 360nm.

3) Put the machined sputtering target (Φ60×3mm) into the magnetron sputtering apparatus, clean the substrate silicon wafer on which the Pt lower electrode has been sputtered and put it into the sputtering chamber, using a radio frequency power of 150W, The argon pressure is 0.6Pa, and the substrate temperature is 300°C. Finally, the in-situ film was annealed in air at a temperature of 650°C for 60 minutes to obtain a crystalline 0.97(0.94Bi _0.5 Na _0.5 TiO ₃ -0.06BaTiO ₃ )-0.03K _0.5 Na _0.5 NbO ₃ high energy storage density film .

4) Using a metal mask, the diameter of the round hole is 1mm, and the surface of the 0.97(0.94Bi _0.5 Na _0.5 TiO ₃ -0.06BaTiO ₃ )-0.03K _0.5 Na _0.5 NbO ₃ high energy storage density film is sputtered by magnetron The metal Pt upper electrode was prepared, the DC power was 80W, the argon pressure was 0.8Pa, the substrate temperature was room temperature, and the Pt thickness of the upper electrode was 310nm. Finally, a high energy storage density film capacitor with a three-layer structure of metal Pt bottom electrode/0.97(0.94Bi _0.5 Na _0.5 TiO ₃ -0.06BaTiO ₃ )-0.03K _0.5 Na _0.5 NbO ₃ high energy storage density film/metal Pt top electrode is formed.

Performance test results: The thickness of the film is about 0.82μm, and the energy storage density is about 39J/cm ³ .

Example 4:

1) Preparation of 0.97(0.94Bi _0.5 Na _0.5 TiO ₃ -0.06BaTiO ₃ )-0.03K _0.5 Na _0.5 NbO ₃ ceramic target for sputtering: select high-purity (≧99.8%) Bi ₂ O ₃ , TiO ₂ , Na ₂ CO ₃ , BaCO ₃ , K ₂ CO ₃ , Nb ₂ O ₅ powder as raw materials, according to Bi ₂ O ₃ : TiO ₂ : Na ₂ CO ₃ : BaCO ₃ : K ₂ CO ₃ : Nb ₂ O ₅ =0.22795:0.97 : 0.23545: 0.0582: 0.0075: 0.015 molar ratio mixed, then fully mixed in a high-energy ball mill, taken out, dried, ground, and kept at 900 ° C for 4 hours to synthesize 0.97 (0.94Bi _0.5 Na _0.5 TiO ₃ -0.06BaTiO ₃ )- 0.03K _0.5 Na _0.5 NbO ₃ powder; mill the resulting powder in a high-energy ball mill for a second time, dry it, add 5wt% polyvinyl alcohol (PVA) as a binder, dry it, and press it into a diameter of 80mm on a hydraulic press , a green body with a thickness of 5mm, and the green body was sintered at 1100°C for 12 hours at a high temperature to obtain a highly dense 0.97(0.94Bi _0.5 Na _0.5 TiO ₃ -0.06BaTiO ₃ )-0.03K _0.5 Na _0.5 NbO ₃ for sputtering Ceramic target.

2) Put the cleaned substrate silicon wafer and the metal Au target into the magnetron sputtering apparatus, and prepare the lower electrode by DC magnetron sputtering the metal Au target. The DC power is 80W, the argon pressure is 0.8Pa, and the substrate temperature is At room temperature, the Au thickness of the lower electrode is 350nm.

3) Put the machined sputtering target (Φ60×3mm) into the magnetron sputtering apparatus, clean the substrate silicon wafer on which the Au lower electrode has been sputtered and put it into the sputtering chamber, using a radio frequency power of 150W, The argon pressure is 0.6Pa, and the substrate temperature is 300°C. Finally, the in-situ film was annealed in air at a temperature of 700°C for 60 minutes to obtain a crystalline 0.97(0.94Bi _0.5 Na _0.5 TiO ₃ -0.06BaTiO ₃ )-0.03K _0.5 Na _0.5 NbO ₃ high energy storage density film .

4) Using a metal mask, the diameter of the round hole is 1mm, and the surface of the 0.97(0.94Bi _0.5 Na _0.5 TiO ₃ -0.06BaTiO ₃ )-0.03K _0.5 Na _0.5 NbO ₃ high energy storage density film is sputtered by magnetron The metal Ag upper electrode was prepared, the DC power was 80W, the argon gas pressure was 0.8Pa, the substrate temperature was room temperature, and the Ag thickness of the upper electrode was 500nm. Finally, a high energy storage density film capacitor with a three-layer structure of metal Au bottom electrode/0.97(0.94Bi _0.5 Na _0.5 TiO ₃ -0.06BaTiO ₃ )-0.03K _0.5 Na _0.5 NbO ₃ high energy storage density film/metal Ag top electrode is formed.

Performance test results: The thickness of the film is about 0.64μm, and the energy storage density is about 34J/cm ³ .

Example 5:

1) Preparation of 0.96(0.94Bi _0.5 Na _0.5 TiO ₃ -0.06BaTiO ₃ )-0.04K _0.5 Na _0.5 NbO ₃ ceramic target for sputtering: select high-purity (≧99.8%) Bi ₂ O ₃ , TiO ₂ , Na ₂ CO ₃ , BaCO ₃ , K ₂ CO ₃ , Nb ₂ O ₅ powder as raw materials, according to Bi ₂ O ₃ : TiO ₂ : Na ₂ CO ₃ : BaCO ₃ : K ₂ CO ₃ : Nb ₂ O ₅ =0.2256:0.94 : 0.2356: 0.0576: 0.01: 0.02 molar ratio mixed, then fully mixed in a high-energy ball mill, taken out, dried, ground, and kept at 900 ° C for 4 hours to synthesize 0.96 (0.94Bi _0.5 Na _0.5 TiO ₃ -0.06BaTiO ₃ )- 0.04K _0.5 Na _0.5 NbO ₃ powder; mill the resulting powder in a high-energy ball mill for a second time, dry it, add 5wt% polyvinyl alcohol (PVA) as a binder, dry it, and press it into a diameter of 80mm on a hydraulic press , a green body with a thickness of 5mm, and the green body was sintered at 1100°C for 12 hours at a high temperature to obtain a highly dense 0.96(0.94Bi _0.5 Na _0.5 TiO ₃ -0.06BaTiO ₃ )-0.04K _0.5 Na _0.5 NbO ₃ for sputtering Ceramic target.

2) Put the cleaned substrate silicon wafer and the metal Au target into the magnetron sputtering apparatus, and prepare the lower electrode by DC magnetron sputtering the metal Au target. The DC power is 80W, the argon pressure is 0.8Pa, and the substrate temperature is At room temperature, the Au thickness of the bottom electrode is 230nm.

3) Put the machined sputtering target (Φ60×3mm) into the magnetron sputtering apparatus, clean the substrate silicon wafer on which the Au lower electrode has been sputtered and put it into the sputtering chamber, using a radio frequency power of 150W, The argon pressure is 0.6Pa, and the substrate temperature is 300°C. Finally, the in-situ film was annealed in air at a temperature of 650°C for 60 minutes to obtain a crystalline 0.96(0.94Bi _0.5 Na _0.5 TiO ₃ -0.06BaTiO ₃ )-0.04K _0.5 Na _0.5 NbO ₃ high energy storage density film .

4) Using a metal mask, the diameter of the round hole is 1mm, and the surface of the 0.96(0.94Bi _0.5 Na _0.5 TiO ₃ -0.06BaTiO ₃ )-0.04K _0.5 Na _0.5 NbO ₃ high energy storage density film is deposited by magnetron sputtering The metal Ag upper electrode was prepared, the DC power was 80W, the argon gas pressure was 0.8Pa, the substrate temperature was room temperature, and the Ag thickness of the upper electrode was 320nm. Finally, a high energy storage density film capacitor with a three-layer structure of metal Au lower electrode/0.96(0.94Bi _0.5 Na _0.5 TiO ₃ -0.06BaTiO ₃ )-0.04K _0.5 Na _0.5 NbO ₃ high energy storage density film/metal Ag upper electrode is formed.

Performance test results: the thickness of the film is about 0.96μm, and the energy storage density is about 28J/cm ³ .

Embodiment 6:

1) Preparation of 0.92(0.94Bi _0.5 Na _0.5 TiO ₃ -0.06BaTiO ₃ )-0.08K _0.5 Na _0.5 NbO ₃ ceramic target for sputtering: select high-purity (≧99.8%) Bi ₂ O ₃ , TiO ₂ , Na ₂ CO ₃ , BaCO ₃ , K ₂ CO ₃ , Nb ₂ O ₅ powder as raw materials, according to Bi ₂ O ₃ : TiO ₂ : Na ₂ CO ₃ : BaCO ₃ : K ₂ CO ₃ : Nb ₂ O ₅ =0.2162:0.92 : 0.2326: 0.0552: 0.02: 0.04 molar ratio mixed, then fully mixed in a high-energy ball mill, taken out, dried, ground, and kept at 900°C for 4 hours to synthesize 0.92 (0.94Bi _0.5 Na _0.5 TiO ₃ -0.06BaTiO ₃ )- 0.08K _0.5 Na _0.5 NbO ₃ powder; mill the resulting powder in a high-energy ball mill for a second time, dry it, add 5wt% polyvinyl alcohol (PVA) as a binder, dry it, and press it into a diameter of 80mm on a hydraulic press , a green body with a thickness of 5mm, and the green body was sintered at 1100°C for 12 hours at a high temperature to obtain a highly dense 0.92(0.94Bi _0.5 Na _0.5 TiO ₃ -0.06BaTiO ₃ )-0.08K _0.5 Na _0.5 NbO ₃ for sputtering Ceramic target.

2) Put the cleaned substrate silicon wafer and the metal Au target into the magnetron sputtering apparatus, and prepare the lower electrode by DC magnetron sputtering the metal Au target. The DC power is 80W, the argon pressure is 0.8Pa, and the substrate temperature is At room temperature, the Au thickness of the bottom electrode is 270nm.

3) Put the machined sputtering target (Φ60×3mm) into the magnetron sputtering apparatus, clean the substrate silicon wafer on which the Au lower electrode has been sputtered and put it into the sputtering chamber, using a radio frequency power of 150W, The argon pressure is 0.6Pa, and the substrate temperature is 300°C. Finally, the in-situ film was annealed in air at a temperature of 600°C for 60 minutes to obtain a crystalline 0.92(0.94Bi _0.5 Na _0.5 TiO ₃ -0.06BaTiO ₃ )-0.08K _0.5 Na _0.5 NbO ₃ high energy storage density film .

4) Using a metal mask, the diameter of the circular hole is 1mm, and magnetron sputtering is used on the surface of the 0.92(0.94Bi _0.5 Na _0.5 TiO ₃ -0.06BaTiO ₃ )-0.08K _0.5 Na _0.5 NbO ₃ high energy storage density film The metal Au upper electrode was prepared, the DC power was 80W, the argon pressure was 0.8Pa, the substrate temperature was room temperature, and the Au thickness of the upper electrode was 280nm. Finally, a high energy storage density film capacitor with a three-layer structure of metal Au lower electrode/0.92(0.94Bi _0.5 Na _0.5 TiO ₃ -0.06BaTiO ₃ )-0.08K _0.5 Na _0.5 NbO ₃ high energy storage density film/metal Au upper electrode is formed.

Performance test results: the thickness of the film is about 0.85μm, and the energy storage density is about 22J/cm ³ .

Embodiment 7:

1) Preparation of 0.9(0.94Bi _0.5 Na _0.5 TiO ₃ -0.06BaTiO ₃ )-0.1K _0.5 Na _0.5 NbO ₃ ceramic target for sputtering: select high-purity (≧99.8%) Bi ₂ O ₃ , TiO ₂ , Na ₂ CO ₃ , BaCO ₃ , K ₂ CO ₃ , Nb ₂ O ₅ powder as raw materials, according to Bi ₂ O ₃ : TiO ₂ : Na ₂ CO ₃ : BaCO ₃ : K ₂ CO ₃ : Nb ₂ O ₅ =0.2115:0.9 : 0.2365: 0.054: 0.025: 0.05 molar ratio mixed, then fully mixed in a high-energy ball mill, taken out, dried, ground, and kept at 900 ° C for 4 hours to synthesize 0.9 (0.94Bi _0.5 Na _0.5 TiO ₃ -0.06BaTiO ₃ )- 0.1K _0.5 Na _0.5 NbO ₃ powder; mill the resulting powder in a high-energy ball mill for a second time, dry it, add 5wt% polyvinyl alcohol (PVA) as a binder, dry it, and press it into a diameter of 80mm on a hydraulic press , a green body with a thickness of 5mm, and the green body was sintered at 1100°C for 12 hours at a high temperature to obtain a highly dense sputtering 0.9(0.94Bi _0.5 Na _0.5 TiO ₃ -0.06BaTiO ₃ )-0.1K _0.5 Na _0.5 NbO ₃ Ceramic target.

2) Put the cleaned substrate silicon wafer and the metal Ag target into the magnetron sputtering apparatus, and prepare the lower electrode by DC magnetron sputtering the metal Ag target. The DC power is 80W, the argon pressure is 0.8Pa, and the substrate temperature is At room temperature, the Ag thickness of the bottom electrode is 270nm.

3) Put the machined sputtering target (Φ60×3mm) into the magnetron sputtering apparatus, clean the substrate silicon wafer on which the Ag lower electrode has been sputtered and put it into the sputtering chamber, using a radio frequency power of 150W, The argon pressure is 0.6Pa, and the substrate temperature is 300°C. Finally, the in-situ film was annealed in air at a temperature of 500°C for 60 minutes to obtain a crystalline 0.9(0.94Bi _0.5 Na _0.5 TiO ₃ -0.06BaTiO ₃ )-0.1K _0.5 Na _0.5 NbO ₃ high energy storage density film .

4) Using a metal mask, the diameter of the round hole is 1mm, and the surface of the 0.9(0.94Bi _0.5 Na _0.5 TiO ₃ -0.06BaTiO ₃ )-0.1K _0.5 Na _0.5 NbO ₃ high energy storage density film is sputtered by magnetron The metal Pt upper electrode was prepared, the DC power was 80W, the argon pressure was 0.8Pa, the substrate temperature was room temperature, and the Pt thickness of the upper electrode was 290nm. Finally, a high energy storage density film capacitor with a three-layer structure of metal Ag bottom electrode/0.9(0.94Bi _0.5 Na _0.5 TiO ₃ -0.06BaTiO ₃ )-0.1K _0.5 Na _0.5 NbO ₃ high energy storage density film/metal Pt top electrode is formed.

Performance test results: the thickness of the film is about 0.78μm, and the energy storage density is about 20J/cm ³ .

Although the present invention has been disclosed above with preferred examples, it does not limit the present invention, and any person skilled in the art can make appropriate improvements without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention is defined by the claims range prevails.

Claims (3)

1. a lead-free Bi _0.5 Na _0.5 TiO ₃ base high energy storage density thin film capacitor, it is characterized in that, by the sputtering metal lower electrode that is sequentially stacked on the substrate material, sputtering Bi _0.5 Na _0.5 TiO ₃ base height The energy storage density film intermediate layer and the sputtered metal upper electrode on the film are composed of a three-layer structure. 2. A kind of lead-free Bi _0.5 Na _0.5 TiO ₃ based high energy storage density film capacitor according to claim 1, characterized in that, the composition of the Bi _0.5 Na _0.5 TiO ₃ based high energy storage density film intermediate layer The general formula is (1- x )(0.94Bi _0.5 Na _0.5 TiO ₃ -0.06BaTiO ₃ )- x K _0.5 Na _0.5 NbO ₃ , where x is 0.01≤ x ≤0.1 A lead-free Bi _0.5 Na _0.5 TiO ₃ -based high energy storage density film capacitor according to claim 1, characterized in that the metal upper and lower electrode materials are one of metal Ag, Au, and Pt. 3. a lead-free Bi _0.5 Na _0.5 TiO The preparation method of _base high energy storage density film capacitor, is characterized in that, comprises the steps: 1) Preparation of (1- x )(0.94Bi _0.5 Na _0.5 TiO ₃ -0.06BaTiO ₃ )- x K _0.5 Na _0.5 NbO ₃ ceramic target for sputtering: select high-purity (≧99.8%) Bi ₂ O ₃ , TiO ₂ , Na ₂ CO ₃ , BaCO ₃ , K ₂ CO ₃ , and Nb ₂ O ₅ powders are used as raw materials, according to Bi ₂ O ₃ : TiO ₂ : Na ₂ CO ₃ : BaCO ₃ : K ₂ CO ₃ : Nb ₂ O ₅ = 0.235(1- x ): (1- x ): [0.235(1- x ) + 0.25 x ]: 0.06(1- x ): 0.25 x : 0.5 x molar ratio mixed, then fully mixed in a high energy ball mill , taken out, dried, ground, and kept at 900°C for 4 hours to synthesize (1- x )(0.94Bi _0.5 Na _0.5 TiO ₃ -0.06BaTiO ₃ )- x K _0.5 Na _0.5 NbO ₃ powder; Secondary ball milling in the ball mill, drying, adding 5wt% polyvinyl alcohol (PVA) as a binder, drying, pressing on a hydraulic press to form a green body with a diameter of 80mm and a thickness of 5mm, and keeping the green body at 1100°C for 12 Sintering at high temperature for 1 hour to obtain a highly dense (1- x ) (0.94Bi _0.5 Na _0.5 TiO ₃ -0.06BaTiO ₃ )- x K _0.5 Na _0.5 NbO ₃ ceramic target for sputtering; 2) Put the cleaned substrate silicon wafer and metal target into the magnetron sputtering apparatus, and prepare the lower electrode by DC magnetron sputtering the metal target, with DC power of 80W, argon pressure of 0.8Pa, and substrate temperature of room temperature; 3) Put the machined sputtering target (Φ60×3mm) into the magnetron sputtering apparatus, clean the substrate silicon wafer that has sputtered the lower electrode and put it into the sputtering chamber, use RF power 150W, argon The gas pressure is 0.6Pa, and the substrate temperature is 300°C; the thickness of the Bi _0.5 Na _0.5 TiO ₃ -based film prepared by sputtering is 0.5-1.5 μm, and finally, the in-situ film is annealed in the air, and the temperature is in the range of 500-800°C , for 60 minutes, and then a crystalline (1- x ) (0.94Bi _0.5 Na _0.5 TiO ₃ -0.06BaTiO ₃ )- x K _0.5 Na _0.5 NbO ₃ thin film with high energy storage density was obtained; 4) Using a metal mask, the diameter of the round hole is 1mm, and the metal upper electrode is prepared on the surface of the Bi _0.5 Na _0.5 TiO ₃ -based high energy storage density film by magnetron sputtering, with a DC power of 80W and an argon pressure of 0.8Pa. The substrate temperature is room temperature, and a capacitor with a three-layer structure of metal lower electrode/Bi _0.5 Na _0.5 TiO ₃ -based high energy storage density thin film/metal upper electrode is finally formed.