Full-transparent HfO2-based ferroelectric capacitor and preparation method and application thereof

Abstract

The invention belongs to the field of microelectronics, and particularly relates to a full-transparent HfO2-based ferroelectric capacitor and a preparation method and application thereof, and the full-transparent HfO2-based ferroelectric capacitor comprises a substrate, a bottom electrode, a ferroelectric medium layer and a top electrode which are sequentially stacked from bottom to top. Insertion layers are respectively arranged between the ferroelectric medium layer and the bottom electrode and between the ferroelectric medium layer and the top electrode. And the intercalation layer is a TiOx intercalation layer. Compared with the prior art, the defects that in the prior art, the ferroelectric performance of a transparent ferroelectric device is poor, a high annealing temperature is needed, and then the thermal budget requirement of a back-end process is not met are overcome; the TiOx intercalation layers are introduced to the two sides of the ferroelectric dielectric layer, so that the grain orientation is improved, the annealing temperature can be reduced to 400 DEG C, and the method can be compatible with a back-end process.

Description

Technical Field

[0001] The present invention belongs to the field of microelectronics, and particularly relates to a fully transparent HfO2-based ferroelectric capacitor, a preparation method thereof, and an application thereof. Background Art

[0002] Transparent electronic devices have received extensive attention in transparent displays, transparent solar panels, and other consumer electronics due to their advantages such as low mass, high flexibility, and good light transmittance. In recent years, as a new type of semiconductor device, transparent electronic devices have gradually replaced silicon-based semiconductor devices in more and more fields and become a mainstream direction for the future development of electronic information, so they have received extensive attention at home and abroad. As electronic devices become more and more miniaturized and highly integrated, people also pay more and more attention to the transparency and lightness of the devices. Therefore, it is very necessary to use transparent electrodes and transparent substrates to make transparent electronic devices. For example, LG Electronics cooperated with the automatic door manufacturer Assa Abloy to design and test glass automatic doors with digital advertising displays. In 2020, China's rail transit deployed LG's interactive OLED train windows. In the aerospace field, transparent components can be used to manufacture transparent solar panels for manned aircraft. Since transparent electronic devices are light and flexible, they have important economic significance for aerospace projects with extremely high load costs. Among them, transparent electronic devices perform functions such as information storage and optoelectronic conversion in these fields. Therefore, it is of great significance to study new fully transparent ferroelectric memories.

[0003] Currently, ferroelectric memories are mainly integrated onto non-transparent silicon wafers, and non-transparent electrode materials such as TiN, Mo, and W are used to induce ferroelectricity, such as CN116390641A and CN111312898A, etc., which limits their development in the transparent electronics field. Quartz substrates have become a good choice for making transparent electronic devices because they are compatible with silicon-based devices, have good ultraviolet and visible light transmittance, and are widely used. In addition, indium tin oxide (ITO) has a wide bandgap structure (3.5 - 4.3 eV), a low film resistivity (10 -4 Ω·cm), and a high visible light transmittance, making it an ideal electrode material for making fully transparent ferroelectric devices.

[0004] Ferroelectric materials have become an ideal choice for making information storage in transparent electronic devices due to their non-volatility, low power consumption, and low latency. Among them, hafnium-based ferroelectric devices have received high attention in the transparent electronics field due to their excellent ferroelectric properties and high durability. However, the ferroelectric properties of transparent ferroelectric devices prepared by existing processes are poor, and the device performance is often optimized by increasing the annealing temperature, which in turn leads to not meeting the thermal budget requirements of the backend process (BEOL). Therefore, there is an urgent need to achieve both a reduction in the annealing temperature and an improvement in ferroelectricity through other means to expand the application of transparent electronic devices. Summary of the Invention

[0005] The purpose of the present invention is to provide a fully transparent HfO2-based ferroelectric capacitor, its preparation method and application to solve at least one of the above problems, so as to solve the defects in the prior art that the ferroelectric performance of transparent ferroelectric devices is poor and a relatively high annealing temperature is required, thus not meeting the thermal budget requirements of the backend process; the present invention realizes the improvement of grain orientation by introducing TiO x interlayers, enabling the annealing temperature to be reduced to 400 °C and being compatible with the backend process.

[0006] The purpose of the present invention is achieved through the following technical solutions:

[0007] The first aspect of the present invention discloses a fully transparent HfO2-based ferroelectric capacitor, including a substrate, a bottom electrode, a ferroelectric dielectric layer, and a top electrode stacked in sequence from bottom to top. Interlayers are respectively provided between the ferroelectric dielectric layer and the bottom electrode and between the ferroelectric dielectric layer and the top electrode; the interlayer is a TiO x interlayer.

[0008] Preferably,

[0009] the substrate is made of quartz, or polymer polyethylene naphthalate, or polyethylene terephthalate, or polyimide;

[0010] the bottom electrode is made of indium tin oxide (ITO), or fluorine-doped tin oxide (FTO), or zinc-doped tin oxide (ZTO), and the thickness of the bottom electrode is 40 - 60 nm;

[0011] the thickness of the interlayer is 0.5 - 1.0 nm; by introducing an ultra-thin Ti layer (interlayer, which is oxidized to TiO x interlayer) during annealing, while improving the polarization intensity of the transparent ferroelectric capacitor, it can also maintain a relatively high light transmittance of the device; a relatively thick Ti layer will not only reduce the light transmittance of the device, but may also lead to a relatively high oxygen vacancy concentration, making the device prone to breakdown;

[0012] the ferroelectric dielectric layer is an Hf y Zr 1-y O2 ferroelectric layer, y = 0.4 - 0.6, and the thickness of the ferroelectric dielectric layer is 8 - 12 nm;

[0013] the top electrode is an ITO electrode, and the thickness of the top electrode is 40 - 60 nm.

[0014] More preferably,

[0015] the substrate is a quartz substrate with a thickness of about 500 μm;

[0016] The bottom electrode is an ITO (In2O3:SnO2 = 9:1) electrode, and the thickness of the bottom electrode is 50 nm; and / or,

[0017] The thickness of the interlayer is 0.8 nm;

[0018] The ferroelectric dielectric layer is a Hf 0.5 Zr 0.5 O2 ferroelectric layer, and the thickness of the ferroelectric dielectric layer is 10 nm; and / or,

[0019] The top electrode is an ITO (In2O3:SnO2 = 9:1) electrode, and the thickness of the top electrode is 50 nm.

[0020] The second aspect of the present invention discloses a method for preparing the all-transparent HfO2-based ferroelectric capacitor as described above, including the following steps:

[0021] S1: Growing a bottom electrode on the surface of a substrate;

[0022] S2: Growing a Ti layer on the surface of the bottom electrode by DC magnetron sputtering;

[0023] S3: Depositing a ferroelectric dielectric layer on the surface of the Ti layer;

[0024] S4: Growing a Ti layer on the surface of the ferroelectric dielectric layer by DC magnetron sputtering;

[0025] S5: Coating a negative photoresist on the surface of the Ti layer and exposing and developing it;

[0026] S6: Growing a top electrode on the surface of the negative photoresist;

[0027] S7: Lifting off;

[0028] S8: Annealing, during which the Ti layer is converted into TiO x Intercalating to obtain the all-transparent HfO2-based ferroelectric capacitor.

[0029] Preferably, in steps S1 and S6, the bottom electrode and the top electrode are grown by DC magnetron sputtering.

[0030] More preferably, an ITO target is used for DC magnetron sputtering, the DC sputtering power is 100 W, the pressure of the argon-oxygen mixed gas is 1.5 mTorr, and the oxygen partial pressure is 20 vol%.

[0031] Preferably, in steps S2 and S4, a Ti target is used for DC magnetron sputtering, the DC sputtering power is 100 W, and the argon gas pressure is 3 mTorr.

[0032] Preferably, in step S3, the ferroelectric dielectric layer is deposited by atomic layer deposition.

[0033] More preferably, tetra(ethylmethylamino)hafnium(IV) is used as the precursor of HfO2, and tetra(ethylmethylamino)zirconium(IV) is used as the precursor of ZrO2; the precursor is heated to 80 °C, deionized water is kept at room temperature, the deposition temperature is 250 °C, N2 is selected as the carrier gas, and the gas flow rate is 400 sccm; during deposition, a layer of ZrO2 is grown first with a pulse time of 0.3 - 0.7 s, then a layer of HfO2 is grown with a pulse time of 0.3 - 0.7 s, and the cycle is repeated in turn, and deionized water is used as the oxygen source.

[0034] Preferably, in step S5, after applying negative photoresist on the Ti layer surface, it is heated at 150 °C for 2 min and exposed, then heated at 120 °C for 2 min and soaked in the developer for 45 s for development, and finally washed with deionized water and dried with inert gas.

[0035] Preferably, in step S7, stripping is carried out by soaking in acetone, then soaked in absolute ethanol to remove acetone, and finally washed with deionized water and dried with inert gas.

[0036] Preferably, in step S8, annealing is carried out in a protective gas atmosphere, the heating rate is 15 - 20 °C / s, the annealing temperature is 400 - 500 °C, and the annealing time is 30 - 600 s.

[0037] The third aspect of the present invention discloses an application of the above-mentioned all - transparent HfO2 - based ferroelectric capacitor in transparent electronic devices.

[0038] The working principle of the present invention is as follows:

[0039] The ultra - thin Ti interlayers arranged on both sides of the HZO ferroelectric dielectric layer will be oxidized during the annealing process, pulling the oxygen atoms in the HZO towards the two - layer interface, thereby generating partial oxygen vacancies inside the HZO thin film, which promotes the stabilization of the orthorhombic phase in the HZO thin film and increases the proportion of the orthorhombic phase in the HZO, and finally results in an improvement in ferroelectricity.

[0040] Compared with the prior art, the present invention has the following beneficial effects:

[0041] 1) The present invention adopts a process method of introducing a TiO x interlayer between the HZO layer and the top electrode and the bottom electrode, improving the grain orientation in the HZO, increasing the ferroelectric phase component and improving the ferroelectric performance; specifically, rapid annealing is carried out at the same annealing temperature of 400 °C, so that its remanent polarization value (2P r ) increases from the original 1 μC / cm 2 (without interlayer) to 43 μC / cm 2(With an interlayer), there is no need to increase the annealing temperature to improve ferroelectricity, thus achieving the purpose of reducing the annealing temperature. This is because the ultra-thin Ti layer is oxidized during annealing, pulling the oxygen atoms in HZO towards the interface, resulting in partial oxygen vacancies inside the HZO film, promoting the stabilization of the orthorhombic phase in the HZO film, increasing the proportion of the orthorhombic phase in HZO, and improving ferroelectricity.

[0042] 2) The present invention uses a transparent quartz substrate and a transparent oxide electrode ITO. Compared with other non-transparent metal electrodes, such as tungsten and titanium nitride, devices with the ITO / HZO / ITO structure usually require a higher annealing temperature to induce the orthorhombic phase in HZO. However, the advantage of ITO is its good transparency; by introducing an interlayer in the present invention, the disadvantage that the ITO electrode is not easy to induce the ferroelectric phase is overcome, and the annealing temperature can be reduced to 400 °C. In addition, the total light transmittance of the transparent substrate plus the transparent capacitor in the present invention can reach up to 90% (where the light transmittance of only the transparent quartz substrate reaches 90%), indicating that the transparent capacitor of the present invention has a quite high visible light transmittance.

[0043] 3) Since the annealing temperature and thermal budget are reduced, it can effectively be compatible with the back-end process (BEOL) of semiconductor manufacturing and reduce production energy consumption, contributing to the extended application of transparent electronic devices in other fields. Brief Description of the Drawings

[0044] Figure 1 is a schematic structural diagram of the fully transparent HfO2-based ferroelectric capacitor of the present invention;

[0045] Figure 2 is a P-E hysteresis loop diagram of the fully transparent HfO2-based ferroelectric capacitors prepared in Example 1 and Comparative Examples 1-3;

[0046] Figure 3 is a light transmittance test result diagram of the fully transparent HfO2-based ferroelectric capacitor prepared in Example 1;

[0047] In the figure: 1 - substrate; 2 - bottom electrode; 3 - interlayer; 4 - ferroelectric dielectric layer; 5 - top electrode. Detailed Description of the Invention

[0048] The present invention will be described in detail below with reference to the drawings and specific embodiments. Various schematic structural diagrams according to the embodiments of the present disclosure are shown in the drawings. These figures are not drawn to scale, where for the purpose of clear expression, some details are enlarged and some details may be omitted. The shapes of various regions and layers shown in the figures, as well as their relative sizes and positional relationships, are only exemplary. In practice, there may be deviations due to manufacturing tolerances or technical limitations, and those skilled in the art can design regions / layers with different shapes, sizes, and relative positions according to actual needs.

[0049] In the context of the present disclosure, when a layer / component is referred to as being "on" another layer / component, the layer / component can be directly on the other layer / component, or there can be an intermediate layer / component between them. Additionally, if a layer / component is "on" another layer / component in one orientation, then when the orientation is reversed, the layer / component can be "under" the other layer / component.

[0050] In the following examples, unless otherwise specified, the reagents used are conventional commercially available products, and the methods used are well-known means in the art.

[0051] Example 1

[0052] A method for preparing a fully transparent HfO2-based ferroelectric capacitor with a double interlayer 3, the specific process steps are as follows:

[0053] First, grow an ITO bottom electrode 2 on a quartz substrate 1 by DC magnetron sputtering; the magnetron sputtering process uses an ITO target, the DC sputtering power is 100 W, the pressure of the argon-oxygen mixed gas is 1.5 mTorr, and the oxygen partial pressure is 20%;

[0054] Second, grow a Ti layer on the bottom electrode 2 by DC magnetron sputtering; the magnetron sputtering process uses a Ti target, the DC sputtering power is 100 W, and the argon gas pressure is 3 mTorr;

[0055] Then, deposit Hf 0.5 Zr 0.5 O2 ferroelectric dielectric layer 4 on the Ti layer by atomic layer deposition, the deposition thickness is 10 nm, and the deposition temperature is 250 °C; during deposition, first grow a layer of ZrO2 with a pulse time of 0.5 s, then grow a layer of HfO2 with a pulse time of 0.5 s, and cycle in turn, using deionized water as the oxygen source; the precursors of Zr and Hf are heated to 80 °C, the deionized water is kept at room temperature of 20 °C, the carrier gas is selected as N2, and the gas flow rate is 400 sccm; the precursor of Hf (HfO2) is tetrakis(ethylmethylamino)hafnium(IV); the precursor of Zr (ZrO2) is tetrakis(ethylmethylamino)zirconium(IV);

[0056] Grow a Ti layer on the HZO layer by DC magnetron sputtering; the magnetron sputtering process uses a Ti target, the DC sputtering power is 100 W, and the argon gas pressure is 3 mTorr;

[0057] Apply photoresist, expose and develop; apply negative photoresist on the Ti interlayer 3, pre-bake at 150 °C for 2 min, post-bake at 120 °C for 2 min after exposure, soak in the developer for 45 s for development, and rinse and dry with deionized water;

[0058] The ITO top electrode 5 is grown by a DC magnetron sputtering process; the magnetron sputtering process uses an ITO target, the DC sputtering power is 100 W, the pressure of the argon-oxygen mixed gas is 1.5 mTorr, and the oxygen partial pressure is 20%;

[0059] Lift-off process; soak in acetone solution until the photoresist and the excess top electrode 5 layer fall off, then soak in absolute ethanol to remove acetone, and finally rinse and blow dry with deionized water.

[0060] The Hf 0.5 Zr 0.5 O2 all-transparent ferroelectric capacitor is processed in an N2 atmosphere (this process can oxidize the ultra-thin Ti layer to TiO x ), the heating rate is controlled at 15 - 20 °C / s, the annealing temperature is 400 °C, and the annealing time is 600 s.

[0061] The prepared all-transparent HfO2-based ferroelectric capacitor is as Figure 1 shown, from bottom to top are a quartz substrate 1, an ITO bottom electrode 2, a TiO x interlayer 3, an HZO ferroelectric dielectric layer 4, a TiO x interlayer 3, and an ITO top electrode 5. Among them, the thickness of the substrate 1 is about 500 μm, the thicknesses of the bottom electrode 2 and the top electrode 5 are both 50 nm, the thickness of the TiO x interlayer 3 is about 0.8 nm, and the thickness of the HZO ferroelectric dielectric layer 4 is 10 nm.

[0062] The electrical properties of the capacitor obtained in Example 1 are tested, and it is found that when a voltage of 5.5 V is applied, the remanent polarization is 43 μC / cm 2 , as Figure 2 shown by the solid line in; and the light transmittance is as high as 90%, as Figure 3 shown by the dashed line in.

[0063] Comparative Example 1

[0064] A preparation method of an all-transparent HfO2-based ferroelectric capacitor with a single interlayer 3 at the lower interface, and the specific process steps are as follows:

[0065] First, the ITO bottom electrode 2 is grown on the quartz substrate 1 by a DC magnetron sputtering process; the magnetron sputtering process uses an ITO target, the DC sputtering power is 100 W, the pressure of the argon-oxygen mixed gas is 1.5 mTorr, and the oxygen partial pressure is 20%;

[0066] Secondly, a Ti layer is grown on the bottom electrode 2 by a DC magnetron sputtering process; the magnetron sputtering process uses a Ti target, the DC sputtering power is 100 W, and the argon gas pressure is 3 mTorr;

[0067] Then, Hf is deposited on the Ti layer by atomic layer deposition technology0.5 Zr 0.5 The ZrO₂ ferroelectric dielectric layer 4 has a deposition thickness of 10 nm and a deposition temperature of 250 °C; during deposition, a layer of ZrO₂ is grown first, then a layer of HfO₂, and this is cycled in turn. Deionized water is used as the oxygen source; the precursors of Zr and Hf are heated to 80 °C, the deionized water is kept at room temperature of 20 °C, the carrier gas is selected as N₂, and the gas flow rate is 400 sccm; the precursor of Hf (HfO₂) is tetrakis(ethylmethylamino)hafnium(IV); the precursor of Zr (ZrO₂) is tetrakis(ethylmethylamino)zirconium(IV).

[0068] Apply photoresist, expose and develop; apply negative photoresist on the dielectric layer, pre-bake at 150 °C for 2 min, post-bake at 120 °C for 2 min after exposure, soak in the developer for 45 s for development, and rinse and blow dry with deionized water.

[0069] Grow the ITO top electrode 5 through a DC magnetron sputtering process; the magnetron sputtering process uses an ITO target, the DC sputtering power is 100 W, the pressure of the argon-oxygen mixed gas is 1.5 mTorr, and the oxygen partial pressure is 20%.

[0070] Lift-off process; soak in acetone solution until the photoresist and the excess top electrode 5 layer fall off, then soak in absolute ethanol to remove acetone, and finally rinse and blow dry with deionized water.

[0071] Adopt a rapid thermal annealing process for Hf 0.5 Zr 0.5 The ZrO₂ all-transparent ferroelectric capacitor is processed in an N₂ atmosphere (this process can oxidize the ultra-thin Ti layer to TiO x ), the annealing temperature is 400 °C, and the annealing time is 600 s.

[0072] Perform electrical property tests on the capacitor obtained in Comparative Example 1, and it is found that when a voltage of 5.5 V is applied, the remanent polarization is 34 μC / cm 2 , which is lower than the ferroelectricity of Example 1, as shown by the underlined part in Figure 2 .

[0073] Comparative Example 2

[0074] A preparation method of an all-transparent HfO₂-based ferroelectric capacitor with an upper interface single interlayer 3, and the specific process steps are as follows:

[0075] First, grow the ITO bottom electrode 2 on the quartz substrate 1 through a DC magnetron sputtering process; the magnetron sputtering process uses an ITO target, the DC sputtering power is 100 W, the pressure of the argon-oxygen mixed gas is 1.5 mTorr, and the oxygen partial pressure is 20%.

[0076] Secondly, deposit Hf 0.5 Zr0.5 The O2 ferroelectric layer 4 has a deposition thickness of 10 nm and a deposition temperature of 250 °C. During deposition, a layer of ZrO2 is grown first, followed by a layer of HfO2, cycling in turn. Deionized water is used as the oxygen source. The precursors of Zr and Hf are heated to 80 °C, the deionized water is kept at room temperature of 20 °C, the carrier gas is N2, and the gas flow rate is 400 sccm. The precursor of Hf (HfO2) is tetrakis(ethylmethylamino)hafnium(IV); the precursor of Zr (ZrO2) is tetrakis(ethylmethylamino)zirconium(IV).

[0077] A Ti layer is grown on the HZO layer by DC magnetron sputtering process. The magnetron sputtering process uses a Ti target, the DC sputtering power is 100 W, and the argon gas pressure is 3 mTorr.

[0078] Apply photoresist, expose and develop. A negative photoresist is coated on the Ti layer, pre-baked at 150 °C for 2 min, post-baked at 120 °C for 2 min after exposure, soaked in the developer for 45 s for development, and rinsed and dried with deionized water.

[0079] The ITO top electrode 5 is grown by DC magnetron sputtering process. The magnetron sputtering process uses an ITO target, the DC sputtering power is 100 W, the argon-oxygen mixed gas pressure is 1.5 mTorr, and the oxygen partial pressure is 20%.

[0080] Lift-off process; soak in acetone solution until the photoresist and the excess top electrode 5 layer fall off, then soak in anhydrous ethanol to remove acetone, and finally rinse and dry with deionized water.

[0081] The Hf 0.5 Zr 0.5 O2 all-transparent ferroelectric capacitor is processed in an N2 atmosphere (this process can oxidize the ultra-thin Ti layer to TiO x ), the annealing temperature is 400 °C, and the annealing time is 600 s.

[0082] The electrical properties of the capacitor obtained in Comparative Example 2 were tested, and it was found that when a voltage of 5.5 V was applied, the remanent polarization was 9 μC / cm 2 , and the ferroelectricity decreased sharply compared with that of Example 1, as shown by the double-dashed line in Figure 2 .

[0083] Comparative Example 3

[0084] A preparation method of an all-transparent HfO2-based ferroelectric capacitor without an interlayer 3, and the specific process steps are as follows:

[0085] First, grow the ITO bottom electrode 2 on the quartz substrate 1 by DC magnetron sputtering process; the magnetron sputtering process uses an ITO target, the DC sputtering power is 100 W, the pressure of the argon-oxygen mixed gas is 1.5 mTorr, and the oxygen partial pressure is 20%;

[0086] Secondly, deposit Hf on the ITO bottom electrode 2 by atomic layer deposition technology 0.5 Zr 0.5 O2 ferroelectric dielectric layer 4, with a deposition thickness of 10 nm and a deposition temperature of 250 °C; during deposition, first grow a layer of ZrO2, then grow a layer of HfO2, and cycle in turn, using deionized water as the oxygen source; the precursors of Zr and Hf are heated to 80 °C, the deionized water is kept at 20 °C room temperature, the carrier gas is selected as N2, and the gas flow rate is 400 sccm; the precursor of Hf (HfO2) is tetrakis(ethylmethylamino)hafnium(IV); the precursor of Zr (ZrO2) is tetrakis(ethylmethylamino)zirconium(IV);

[0087] Apply photoresist, expose and develop; apply negative photoresist on the HZO layer, pre-bake at 150 °C for 2 min, post-bake at 120 °C for 2 min after exposure, soak in the developer for 45 s for development, and rinse and dry with deionized water;

[0088] Grow the ITO top electrode 5 by DC magnetron sputtering process; the magnetron sputtering process uses an ITO target, the DC sputtering power is 100 W, the pressure of the argon-oxygen mixed gas is 1.5 mTorr, and the oxygen partial pressure is 20%;

[0089] Lift-off process; soak in acetone solution until the photoresist and the excess top electrode 5 layer fall off, then soak in anhydrous ethanol to remove acetone, and finally rinse and dry with deionized water.

[0090] Use rapid thermal annealing process to treat the Hf 0.5 Zr 0.5 O2 all-transparent ferroelectric capacitor in N2 atmosphere, the annealing temperature is 400 °C, and the annealing time is 600 s.

[0091] Perform electrical performance tests on the capacitor, and it is found that when the applied voltage is 5.5 V, the remanent polarization can be ignored and there is almost no ferroelectricity, as Figure 2 shown by the midpoint line.

[0092] As can be seen from Example 1 and Comparative Examples 1-3 and Figure 2 shown, in this solution, a layer of TiO is inserted on each side of the HZO ferroelectric dielectric layer 4 (between the ferroelectric dielectric layer 4 and the top electrode 5 and the bottom electrode 2) respectively xInterlayer 3 shows a significant increase in the remanent polarization compared to the ferroelectric capacitor without interlayer 3, and there is still at least a 20% increase compared to the ferroelectric capacitor with a single interlayer 3. This is because the ultrathin Ti layers on both sides of the HZO ferroelectric dielectric layer 4 during the preparation process are oxidized during annealing, pulling the oxygen atoms in HZO towards the two interface sides, resulting in relatively uniform partial oxygen vacancies along the thickness direction inside the HZO thin film. This further promotes the stabilization of the orthorhombic phase in the HZO thin film, thereby increasing the proportion of the orthorhombic phase in HZO and ultimately manifesting as an improvement in ferroelectricity. Additionally, as Figure 3 shown, the fully transparent HfO2-based ferroelectric capacitor prepared in Example 1 can achieve a light transmittance of 80% or even 90% under illumination in the range of 400 - 800 nm (visible light), exhibiting high light transmittance.

[0093] Example 2

[0094] This example is basically the same as Example 1, with the main difference being that the ferroelectric dielectric layer 4 is Hf 0.6 Zr 0.4 O2, with a thickness controlled at 8 nm; the thicknesses of both the bottom electrode 2 and the top electrode 5 are 60 nm; the thickness of the interlayer 3 is controlled at 0.5 nm. The performance of the fully transparent HfO2-based ferroelectric capacitor thus prepared is basically the same as that of Example 1.

[0095] Example 3

[0096] This example is basically the same as Example 1, with the main difference being that the ferroelectric dielectric layer 4 is Hf 0.4 Zr 0.6 O2, with a thickness controlled at 12 nm; the thicknesses of both the bottom electrode 2 and the top electrode 5 are 40 nm; the thickness of the interlayer 3 is controlled at 1 nm. The performance of the fully transparent HfO2-based ferroelectric capacitor thus prepared is basically the same as that of Example 1.

[0097] Example 4

[0098] This example is basically the same as Example 1, with the main difference being that when preparing the HZO ferroelectric dielectric layer 4, the pulse is 0.3 s during the growth of the ZrO2 layer and 0.3 s during the growth of the HfO2 layer; during annealing, the annealing temperature is set at 450 °C and the annealing time is 450 s. The performance of the fully transparent HfO2-based ferroelectric capacitor thus prepared is basically the same as that of Example 1.

[0099] Example 5

[0100] This embodiment is basically the same as Embodiment 1, and the main difference lies in that: when preparing the HZO ferroelectric dielectric layer 4, the pulse is 0.7 s during the growth of the ZrO2 layer and the pulse is 0.7 s during the growth of the HfO2 layer; during annealing, the annealing temperature is set at 500 °C and the annealing time is 200 s. The performance of the fully transparent HfO2-based ferroelectric capacitor thus prepared is basically the same as that of Embodiment 1.

[0101] Embodiment 6

[0102] This embodiment is basically the same as Embodiment 1, and the main difference lies in that: during annealing, the annealing temperature is set at 500 °C and the annealing time is 30 s. The performance of the fully transparent HfO2-based ferroelectric capacitor thus prepared is basically the same as that of Embodiment 1.

[0103] The above description of the embodiments is to enable those of ordinary skill in the art to understand and use the invention. It is obvious that those who are familiar with the technology in this field can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative efforts. Therefore, the present invention is not limited to the above embodiments, and all improvements and modifications made by those skilled in the art without departing from the scope of the present invention according to the disclosure of the present invention should be within the protection scope of the present invention.

Claims

1. A fully transparent HfO2-based ferroelectric capacitor, comprising a substrate (1), a bottom electrode (2), a ferroelectric dielectric layer (4), and a top electrode (5) stacked in sequence from bottom to top, characterized in that, An interlayer (3) is further respectively disposed between the ferroelectric dielectric layer (4) and the bottom electrode (2), and between the ferroelectric dielectric layer (4) and the top electrode (5); the interlayer (3) is TiO x interlayer.

2. The fully transparent HfO2-based ferroelectric capacitor according to claim 1, characterized in that, The material of the substrate (1) includes quartz, polyethylene naphthalate, polyethylene terephthalate, and polyimide; The material of the bottom electrode (2) includes indium tin oxide, fluorine-doped tin oxide, and zinc-doped tin oxide, and the thickness of the bottom electrode (2) is 40 - 60 nm; The thickness of the interlayer (3) is 0.5 - 1.0 nm; The ferroelectric dielectric layer (4) is an Hf y Zr 1-y O2 ferroelectric layer, where y = 0.4 to 0.6, and the thickness of the ferroelectric dielectric layer (4) is 8 to 12 nm; The top electrode (5) is an ITO electrode, and the thickness of the top electrode (5) is 40 - 60 nm.

3. A method for preparing the fully transparent HfO2-based ferroelectric capacitor according to claim 1 or 2, characterized in that, It includes the following steps: S1: Grow the bottom electrode (2) on the surface of the substrate (1); S2: Grow a Ti layer on the surface of the bottom electrode (2) by DC magnetron sputtering; S3: Deposit the ferroelectric dielectric layer (4) on the surface of the Ti layer; S4: Grow a Ti layer on the surface of the ferroelectric dielectric layer (4) by DC magnetron sputtering; S5: Coating a negative photoresist on the surface of the Ti layer and exposing and developing; S6: Grow the top electrode (5) on the surface of the negative photoresist; S7: Lift-off; S8: Annealing, during which the Ti layer is converted into TiO x Intercalation (3) is carried out to obtain the all-transparent HfO2-based ferroelectric capacitor described above.

4. The method for preparing the fully transparent HfO2-based ferroelectric capacitor according to claim 3, characterized in that, In step S1 and step S6, the bottom electrode (2) and the top electrode (5) are grown by DC magnetron sputtering.

5. The method for preparing the fully transparent HfO2-based ferroelectric capacitor according to claim 3, characterized in that, In step S2 and step S4, a Ti target is used for DC magnetron sputtering, the DC sputtering power is 100 W, and the argon gas pressure is 3 mTorr.

6. The method for preparing the fully transparent HfO2-based ferroelectric capacitor according to claim 3, characterized in that, In step S3, the ferroelectric dielectric layer (4) is deposited by atomic layer deposition.

7. The method for preparing the fully transparent HfO2-based ferroelectric capacitor according to claim 3, characterized in that, In step S5, after coating a negative photoresist on the surface of the Ti layer, it is heated at 150 °C for 2 min and exposed, then heated at 120 °C for 2 min and soaked in the developer for 45 s for development, and finally washed with deionized water and dried with an inert gas.

8. The method for preparing the fully transparent HfO2-based ferroelectric capacitor according to claim 3, characterized in that, In step S7, lift-off is carried out by soaking in acetone, then soaked in absolute ethanol to remove acetone, and finally washed with deionized water and dried with an inert gas.

9. The method for preparing the fully transparent HfO2-based ferroelectric capacitor according to claim 3, characterized in that, In step S8, annealing is carried out in a protective gas atmosphere, the heating rate is 15 - 20 °C / s, the annealing temperature is 400 - 500 °C, and the annealing time is 30 - 600 s.

10. Application of the fully transparent HfO2-based ferroelectric capacitor according to claim 1 or 2 in a transparent electronic device.

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