Ferroelectric capacitor for improving initial state polarization intensity, preparation method and application

Abstract

The invention belongs to the field of microelectronics, and particularly relates to a ferroelectric capacitor for improving initial state polarization intensity and a preparation method and application thereof.The ferroelectric capacitor comprises a substrate, a bottom electrode, an ultrathin ferroelectric medium layer and a top electrode which are sequentially stacked from bottom to top; the ultra-thin ferroelectric dielectric layer is an Hf < 1-x > Zr < x > O < 2 > thin film, 0 lt; xlt; and in the atomic layer deposition process, the Hf-rich thin film is grown and formed by controlling the Hf: Zr super-cycle ratio. Compared with the prior art, the ferroelectric capacitor solves the problems that in the prior art, in order to improve the initial-state polarization intensity of the ferroelectric capacitor, a function matched with the HZO thin film is added, the thickness is increased due to layers, and the improvement effect is limited. According to the scheme, the doping proportion of Hf in the ultra-thin ferroelectric dielectric layer is properly increased, the formation energy of a non-ferroelectric T phase is remarkably improved, stable existence of a ferroelectric O phase is further promoted, and therefore the ferroelectric O phase with ferroelectric hysteresis close to the situation that awakening is not needed, a high initial state 2Pr value and a high content is achieved.

Description

Technical Field

[0001] This invention belongs to the field of microelectronics, specifically relating to a ferroelectric capacitor that enhances the initial state polarization intensity, its preparation method, and its application. Background Technology

[0002] For decades, the application of ferroelectric memories has been limited by challenges such as insufficient miniaturization and poor compatibility with complementary metal-oxide-semiconductor (CMOS) technology. Since the first report of HfO2 ferroelectricity in 2011, HfO2 thin films have regained widespread attention due to their high-k dielectric properties, which are widely used in CMOS processes. Doped HfO2 ferroelectric thin films are considered strong candidates for next-generation non-volatile memories due to their excellent CMOS process compatibility and significant miniaturization capabilities, especially showing great potential in realizing high-density ferroelectric random access memories (FeRAMs). Zr-doped HfO2 thin films (HZO) have a low crystallization temperature of approximately 400°C, enabling compatibility with CMOS back-end processes (BEOL).

[0003] However, compared with traditional ferroelectric materials such as Pb(Zr,Ti)O3 and SrBi2Ta2O9, HfO2-based ferroelectric thin films exhibit a higher coercive electric field (E). c The high operating voltage (≈1-2 MV / cm) of HfO2-based FeRAMs hinders their application in advanced technology nodes. To achieve higher storage density and lower operating voltage, HZO film thickness needs to be reduced. However, thinning causes HZO to stabilize in a non-ferroelectric tetragonal phase (T phase), resulting in a pinned antiferroelectric-like shape in the initial state polarization-voltage (PV) hysteresis. This significantly reduces the initial state remanent polarization (2Pr), leading to a smaller storage window and a more pronounced wake-up effect. For example, a 4 nm HZO film may require more than 10... 6 It takes several bipolar pulse cycles to fully open the hysteresis / memory window. The wake-up effect not only challenges the accuracy of stored information but also increases the complexity of device operation due to the reduced memory margin caused by antiferroelectric properties. This performance characteristic significantly increases the difficulty of memory design and use, limiting the practical application of hafnium-based FeRAMs in high-reliability memory applications.

[0004] Therefore, there is a need for an ultrathin HfO2-based ferroelectric capacitor and its fabrication method to enhance the initial polarization intensity. Existing technologies, such as CN120187030A, CN117881194A, CN116456816A, and CN117580445A, have provided some solutions for enhancing the initial polarization intensity. However, these existing solutions achieve the desired effect by changing the material structure and adding functional layers, which actually increases the overall thickness of the HZO film, thus limiting the improvement in the initial polarization intensity. Summary of the Invention

[0005] This invention aims to address one or more of the following problems in the prior art: In ultrathin HfO2-based ferroelectric capacitors, conventional solid solution-structured HZO films (ultrathin ferroelectric dielectric layers with an Hf:Zr doping ratio of 1:1) tend to stabilize into a non-ferroelectric tetragonal phase (T phase) as the thickness is reduced, leading to a significant decrease in the initial polarization intensity of the device. To improve the initial polarization performance of the device at ultrathin dimensions, this invention provides a method for preparing and applying an HfO2-based ferroelectric capacitor that enhances the initial polarization intensity. Specifically, this invention adjusts the Hf / Zr doping ratio to appropriately increase the Hf content in ultrathin ferroelectric dielectric layers (such as HZO films with a thickness of less than 6 nm), significantly increasing the formation energy of the non-ferroelectric T phase and suppressing its formation tendency, thereby promoting the stable formation of the ferroelectric orthorhombic phase (O phase). This control strategy effectively compensates for the structural and performance degradation caused by the reduction in film thickness and significantly improves the initial ferroelectricity.

[0006] Therefore, the ultrathin HfO2-based ferroelectric capacitor constructed in this invention has the following characteristics: it exhibits clear ferroelectric hysteresis behavior without undergoing a significant wake-up process; the initial state 2Pr value is significantly improved; and a stable ferroelectric O phase is enriched in the thin film. This strategy can achieve the construction of high-performance ferroelectric devices without introducing additional functional layers, while maintaining a low overall stack thickness, and is suitable for fields such as advanced low-power non-volatile memories.

[0007] The objective of this invention is achieved through the following technical solution:

[0008] The first aspect of the present invention discloses a ferroelectric capacitor for improving the initial state polarization intensity, comprising a substrate, a bottom electrode, an ultrathin ferroelectric dielectric layer and a top electrode stacked sequentially from bottom to top;

[0009] The ultrathin ferroelectric layer is Hf 1-x Zr x O2 thin film, 0 <x<0.5;

[0010] The ultrathin ferroelectric layer is grown into an Hf-rich film by controlling the Hf:Zr supercycle ratio during atomic layer deposition.

[0011] Preferably, the substrate comprises a SiO2 / Si wafer and a Si wafer.

[0012] Preferably, the materials of the bottom electrode and the top electrode include TiN, W, Ru, Mo, Ta, TaN, Ti, and Pt; the thickness of the bottom electrode and the top electrode is 2-100 nm.

[0013] Preferably, the ultrathin ferroelectric layer is Hf 0.6 Zr 0.4 The O2 thin film has an Hf:Zr supercycle ratio controlled at 3:2 during atomic layer deposition; the thickness of the ultrathin ferroelectric layer is 1-6 nm.

[0014] The second aspect of this invention discloses a method for preparing a ferroelectric capacitor with improved initial-state polarization intensity as described above, comprising the following steps:

[0015] Step 1: Grow the bottom electrode on the substrate surface;

[0016] Step 2: Deposit an ultrathin ferroelectric layer on the bottom electrode surface using atomic layer deposition (ALD), wherein the Hf:Zr supercycle ratio is controlled to be higher than 1:1 during the ALD deposition process.

[0017] Step 3: Coat the ultrathin ferroelectric layer with photoresist and expose and develop it, then grow the top electrode on its surface;

[0018] Step 4: Peeling process;

[0019] Step 5: Post-annealing.

[0020] Preferably, in steps 1 and 3, the growth is magnetron sputtering growth;

[0021] The magnetron sputtering growth used a TiN target, with a DC sputtering power of 100W and an Ar gas flow rate of 1.15 mTorr; or,

[0022] The magnetron sputtering process described uses a W target, a DC sputtering power of 100W, and an Ar gas flow rate of 3 mTorr; or,

[0023] The magnetron sputtering process used a Ru target, a DC sputtering power of 100W, and an Ar gas flow rate of 3mTorr.

[0024] Preferably, in step 2, the atomic layer deposition process is as follows:

[0025] In a complete supercycle, three cycles of HfO2 layers are first deposited using an Hf precursor source and an oxygen source, followed by two cycles of ZrO2 layers deposited using a Zr precursor source and an oxygen source; this process is repeated until an Hf-rich ultrathin Hf layer is formed.1-x Zr x O2 thin film.

[0026] Preferably, in step 2, the atomic layer deposition process includes:

[0027] The Zr precursor sources used include tetra(ethylmethylamino)zirconium and tetra(diethylamino)zirconium; and / or,

[0028] The Hf precursor sources used include tetra(ethylmethylamino)hafnium and tetra(diethylamino)hafnium; and / or,

[0029] The oxygen sources used include deionized water, hydrogen peroxide, and ozone.

[0030] Preferably, in step 5, the post-annealing process is carried out in an inert atmosphere, with a heating rate of 10-30℃ / s, an annealing temperature of 300-700℃, and an annealing time of 10s-10h.

[0031] The third aspect of the present invention discloses the application of a ferroelectric capacitor that enhances the initial state polarization intensity as described above in a non-volatile memory.

[0032] The working principle of this invention is as follows:

[0033] This invention improves the formation energy of the non-ferroelectric T phase by controlling the Hf:Zr supercycle ratio during the atomic layer deposition process of the ultrathin ferroelectric dielectric layer, resulting in a higher Hf doping content than Zr doping content. This compositional control effectively stabilizes the higher content of the ferroelectric O phase and achieves near-wake-up-free ferroelectric hysteresis characteristics and high initial state 2P. r value.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] 1. For ferroelectric dielectric layers (HZO), the optimal ratio of Hf:Zr is generally considered to be 1:1. However, the inventors have found that at ultrathin dimensions, this ratio leads to a decrease in the initial polarization of the ferroelectric dielectric layer due to the stabilization of the non-ferroelectric T phase. This invention addresses the issue of conventional solid solution structures (HfO) at ultrathin dimensions. 0.5 Zr 0.5 The problem of reduced initial polarization caused by the stabilization of the non-ferroelectric T phase in O2 was effectively neutralized by adjusting the Hf / Zr doping ratio, thereby effectively improving the proportion of ferroelectric O phase and the initial ferroelectric performance.

[0036] 2. The ultrathin ferroelectric capacitor of the present invention has ferroelectric hysteresis characteristics that are close to requiring no wake-up, eliminating the challenge of traditional ultrathin HfO2-based ferroelectric films needing to undergo a large number of cycles to be woken up to a normal state;

[0037] 3. The ultrathin ferroelectric capacitor of the present invention has a high initial 2P r The value ensures that the device achieves excellent ferroelectric performance in its initial state.

[0038] 4. The ultrathin ferroelectric capacitor of the present invention is fabricated entirely based on CMOS technology, has good compatibility, and is compatible with back-end processes (BEOL), meeting the needs of modern integrated circuit manufacturing. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the structure of the ultrathin HfO2-based ferroelectric capacitor prepared in Example 1;

[0040] Figure 2 A schematic diagram of the structure of the ultrathin HfO2-based ferroelectric capacitor prepared for Comparative Example 1;

[0041] Figure 3 The graph shows a comparison of the ferroelectric hysteresis characteristics of the ferroelectric capacitors in Examples 1, 2, and Comparative Example 1 in their initial state and after wake-up. The PV test frequency is 10kHz, and the wake-up operation is performed by applying a triangular wave with a frequency of 10kHz and a voltage amplitude of 2.5V for 10 cycles. 5 This is the first implementation;

[0042] Figure 4 The grazing incidence X-ray diffraction characterization results are for Example 1 and Comparative Example 1.

[0043] Figure 5 The image shows a comparison of the initial state and PV ferroelectric hysteresis characteristics of the 4nm HfO2-based ferroelectric capacitor prepared in Comparative Example 2. The PV test frequency is 50kHz, and the wake-up operation is performed by applying a triangular wave with a voltage amplitude of 2V and a frequency of 100kHz for 10 cycles. 7 This is the first implementation. Detailed Implementation

[0044] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0045] An ultrathin HfO2-based ferroelectric capacitor has a structure consisting of a substrate, a bottom electrode, an HZO thin film, and a top electrode, from bottom to top.

[0046] The method for preparing an ultrathin HfO2-based ferroelectric capacitor with improved initial-state polarization intensity according to the present invention includes the following steps:

[0047] Step 1: Grow the bottom electrode on the substrate surface;

[0048] Step 2: Deposit an ultrathin ferroelectric layer on the surface of the bottom electrode;

[0049] Step 3: Coat the surface of the ultrathin ferroelectric layer with photoresist and expose and develop it, then grow the top electrode on the surface;

[0050] Step 4: Peeling process;

[0051] Step 5: Post-annealing.

[0052] The substrate can be either SiO2 / Si wafer or Si wafer. The thickness of the SiO2 / Si wafer is 300nm, and the Si wafer can be n-type or p-type doped.

[0053] The bottom / top electrodes are grown via magnetron sputtering. The bottom / top electrode materials can be selected from TiN, W, Ru, Mo, Ta, TaN, Ti, Pt, etc., with a thickness of 2-100 nm. The magnetron sputtering process uses a TiN target with a DC sputtering power of 100 W and an Ar gas flow rate of 1.15 mTorr; or, uses a W target with a DC sputtering power of 100 W and an Ar gas flow rate of 3 mTorr; or, uses a Ru target with a DC sputtering power of 100 W and an Ar gas flow rate of 3 mTorr.

[0054] The ultrathin ferroelectric layer was prepared using atomic layer deposition (ALD) with a precisely controlled Hf:Zr supercycle ratio. Specifically, in a complete supercycle, a specific number of HfO2 cycles (e.g., 3 cycles of "Hf precursor source + oxygen source") were deposited first, followed by a specific number of ZrO2 cycles (e.g., 2 cycles of "Zr precursor source + oxygen source"). This process was repeated according to this Hf:Zr supercycle ratio (e.g., 3:2) to grow Hf-rich ultrathin Hf layers with a thickness of 1-6 nm. 1-x Zr x O2 film (0) <x<0.5)。

[0055] Zr precursor sources include tetra(ethylmethylamino)zirconium (TEMAZr) and tetra(diethylamino)zirconium (TDMAZr); Hf precursor sources include tetra(ethylmethylamino)hafnium (TEMAHf) and tetra(diethylamino)hafnium (TDMAHf); oxygen source is deionized water, hydrogen peroxide, or ozone.

[0056] The post-annealing process is carried out in an inert atmosphere, with a heating rate of 10-30℃ / s, an annealing temperature of 300-700℃, and an annealing time of 10s-10h.

[0057] Example 1

[0058] An ultrathin HfO2-based ferroelectric capacitor with enhanced initial-state polarization intensity and its preparation method are disclosed below.

[0059] First, a 40 nm TiN bottom electrode was grown on a SiO2 / Si substrate by magnetron sputtering. The magnetron sputtering process used a TiN target, a DC sputtering power of 100 W, and an Ar gas flow rate of 1.15 mTorr.

[0060] Secondly, a 5nm ultrathin Hf layer is deposited on the bottom electrode using atomic layer deposition technology. 1-x Zr x The O2 ferroelectric dielectric layer was deposited at a temperature of 250℃. Tetra(ethylmethylamino)zirconium was used as the Zr precursor, and tetra(ethylmethylamino)hafnium as the Hf precursor. The Hf:Zr supercycle ratio was 3:2, meaning that three HfO2 cycles were deposited followed by two ZrO2 cycles, alternating between the two deposition cycles, ultimately growing the Hf layer. 0.6 Zr 0.4 O2 thin film;

[0061] Then, photoresist is applied, and the surface is exposed and developed; after annealing, the ultrathin Hf... 0.6 Zr 0.4 Photoresist was coated on the O2 ferroelectric dielectric layer, pre-baked at 150°C for 2 minutes, exposed and then post-baked at 120°C for 2 minutes. The layer was then immersed in the developer for 55 seconds and developed, rinsed with deionized water and dried.

[0062] Next, a 40nm TiN top electrode was grown by magnetron sputtering. The magnetron sputtering process used a TiN target, a DC sputtering power of 100W, and an Ar gas flow rate of 1.15mTorr.

[0063] Then, a patterned top electrode is obtained through a stripping process; it is then immersed in an acetone solution until the photoresist and excess metal are removed, followed by immersion in anhydrous ethanol to remove the acetone, and then rinsed with deionized water and dried.

[0064] Finally, the ultrathin ferroelectric dielectric layer was directly treated in an N2 atmosphere using a rapid thermal annealing process, with a heating rate controlled at 15-20℃ / s, an annealing temperature of 600℃, and an annealing time of 30s; thus obtaining an ultrathin HfO2-based ferroelectric capacitor.

[0065] like Figure 1 As shown, the ultrathin HfO2-based ferroelectric capacitor prepared in Example 1 consists of, from bottom to top, a SiO2 / Si substrate, a TiN bottom electrode, and an HfO2 substrate. 0.6 Zr 0.4 An O2 ferroelectric dielectric layer and a TiN top electrode; wherein the oxide layer thickness of the SiO2 / Si substrate is 300 nm, and the thickness of the TiN bottom electrode and TiN top electrode is 40 nm, Hf 0.6 Zr 0.4 The O2 ferroelectric dielectric layer is 5 nm thick.

[0066] Example 2

[0067] An ultrathin HfO2-based ferroelectric capacitor with enhanced initial-state polarization intensity and its preparation method are disclosed below.

[0068] First, a 40 nm TiN bottom electrode was grown on a SiO2 / Si substrate by magnetron sputtering. The magnetron sputtering process used a TiN target, a DC sputtering power of 100 W, and an Ar gas flow rate of 1.15 mTorr.

[0069] Secondly, a 5nm ultrathin Hf layer is deposited on the bottom electrode using atomic layer deposition technology. 1-x Zr x An O2 ferroelectric dielectric layer was deposited at a temperature of 250℃. A 4:1 Hf:Zr supercycle ratio was used, meaning four HfO2 cycles were deposited followed by one ZrO2 cycle, alternating between the two, ultimately growing an O2 ferroelectric layer. 0.8 Zr 0.2 O2 thin film;

[0070] Then, photoresist is applied, and the surface is exposed and developed; after annealing, the ultrathin Hf... 0.8 Zr 0.2 Photoresist was coated on the O2 ferroelectric dielectric layer, pre-baked at 150°C for 2 minutes, exposed and then post-baked at 120°C for 2 minutes. The layer was then immersed in the developer for 55 seconds and developed, rinsed with deionized water and dried.

[0071] Next, a 40nm TiN top electrode was grown by magnetron sputtering. The magnetron sputtering process used a TiN target, a DC sputtering power of 100W, and an Ar gas flow rate of 1.15mTorr.

[0072] Then, a patterned top electrode is obtained through a stripping process; it is then immersed in an acetone solution until the photoresist and excess metal are removed, followed by immersion in anhydrous ethanol to remove the acetone, and then rinsed with deionized water and dried.

[0073] Finally, the ultrathin ferroelectric dielectric layer was directly treated in an N2 atmosphere using a rapid thermal annealing process, with a heating rate controlled at 15-20℃ / s, an annealing temperature of 600℃, and an annealing time of 30s; thus obtaining an ultrathin HfO2-based ferroelectric capacitor.

[0074] Example 3

[0075] An ultrathin HfO2-based ferroelectric capacitor with enhanced initial-state polarization intensity and its preparation method are disclosed below.

[0076] First, a 40 nm TiN bottom electrode was grown on a SiO2 / Si substrate by magnetron sputtering. The magnetron sputtering process used a TiN target, a DC sputtering power of 100 W, and an Ar gas flow rate of 1.15 mTorr.

[0077] Secondly, a 5nm ultrathin Hf layer is deposited on the bottom electrode using atomic layer deposition technology. 1-x Zr x An O2 ferroelectric dielectric layer was deposited at a temperature of 250℃. A 7:3 Hf:Zr supercycle ratio was used, meaning seven HfO2 cycles were deposited followed by three ZrO2 cycles, alternating between the two, ultimately growing an O2 ferroelectric dielectric layer. 0.7 Zr 0.3 O2 thin film;

[0078] Then, photoresist is applied, and the surface is exposed and developed; after annealing, the ultrathin Hf... 0.7 Zr 0.3 Photoresist was coated on the O2 ferroelectric dielectric layer, pre-baked at 150°C for 2 minutes, exposed and then post-baked at 120°C for 2 minutes. The layer was then immersed in the developer for 55 seconds and developed, rinsed with deionized water and dried.

[0079] Next, a 40nm TiN top electrode was grown by magnetron sputtering. The magnetron sputtering process used a TiN target, a DC sputtering power of 100W, and an Ar gas flow rate of 1.15mTorr.

[0080] Then, a patterned top electrode is obtained through a stripping process; it is then immersed in an acetone solution until the photoresist and excess metal are removed, followed by immersion in anhydrous ethanol to remove the acetone, and then rinsed with deionized water and dried.

[0081] Finally, the ultrathin ferroelectric dielectric layer was directly treated in an N2 atmosphere using a rapid thermal annealing process, with a heating rate controlled at 15-20℃ / s, an annealing temperature of 600℃, and an annealing time of 30s; thus obtaining an ultrathin HfO2-based ferroelectric capacitor.

[0082] Comparative Example 1

[0083] First, a 40 nm TiN bottom electrode was grown on a SiO2 / Si substrate by magnetron sputtering. The magnetron sputtering process used a TiN target, a DC sputtering power of 100 W, and an Ar gas flow rate of 1.15 mTorr.

[0084] Secondly, a 5nm ultrathin Hf layer is deposited on the bottom electrode using atomic layer deposition technology. 0.5 Zr 0.5 An O2 ferroelectric dielectric layer was deposited at a temperature of 250℃. A 1:1 Hf:Zr supercycle ratio was used, meaning one HfO2 cycle was deposited followed by one ZrO2 cycle, alternating between the two, until an Hf layer was finally grown. 0.5 Zr0.5 O2 thin film;

[0085] Then, photoresist is applied, and the surface is exposed and developed; after annealing, the ultrathin Hf... 0.5 Zr 0.5 Photoresist was coated on the O2 ferroelectric dielectric layer, pre-baked at 150°C for 2 minutes, exposed and then post-baked at 120°C for 2 minutes. The layer was then immersed in the developer for 55 seconds and developed, rinsed with deionized water and dried.

[0086] Next, a 40nm TiN top electrode was grown by magnetron sputtering. The magnetron sputtering process used a TiN target, a DC sputtering power of 100W, and an Ar gas flow rate of 1.15mTorr.

[0087] Then, a patterned top electrode is obtained through a stripping process; it is then immersed in an acetone solution until the photoresist and excess metal are removed, followed by immersion in anhydrous ethanol to remove the acetone, and then rinsed with deionized water and dried.

[0088] Finally, the ultrathin ferroelectric dielectric layer was directly treated in an N2 atmosphere using a rapid thermal annealing process, with a heating rate controlled at 15-20℃ / s, an annealing temperature of 600℃, and an annealing time of 30s; thus obtaining an ultrathin HfO2-based ferroelectric capacitor.

[0089] like Figure 2 As shown, the ultrathin HfO2-based ferroelectric capacitor prepared in Comparative Example 1 consists of, from bottom to top, a SiO2 / Si substrate, a TiN bottom electrode, and an HfO2 substrate. 0.5 Zr 0.5 An O2 ferroelectric dielectric layer and a TiN top electrode; wherein the oxide layer thickness of the SiO2 / Si substrate is 300 nm, and the thickness of the TiN bottom electrode and TiN top electrode is 40 nm, Hf 0.5 Zr 0.5 The O2 ferroelectric dielectric layer is 5 nm thick.

[0090] like Figure 3 As shown, the polarization hysteresis of Comparative Example 1 exhibits pinned antiferroelectric-like hysteresis, while the polarization hysteresis curves of Examples 1 and 2 show typical ferroelectric characteristics. Specifically, the remanent polarization intensity of Example 1 in the initial state is significantly increased to approximately 30 μC / cm. 2 .

[0091] like Figure 4 As shown, the grazing incidence X-ray diffraction results of Comparative Example 1 and Example 1 show that the device of Example 1 has a higher ferroelectric orthorhombic O phase content (~64%), which is consistent with the increase in its initial polarization intensity.

[0092] Comparative Example 2

[0093] First, a 40 nm TiN bottom electrode was grown on a SiO2 / Si substrate by magnetron sputtering. The magnetron sputtering process used a TiN target, a DC sputtering power of 100 W, and an Ar gas flow rate of 1.15 mTorr.

[0094] Secondly, a 4nm ultrathin Hf layer was deposited on the bottom electrode using atomic layer deposition technology. 0.5 Zr 0.5 An O2 ferroelectric dielectric layer was deposited at a temperature of 250℃. A 1:1 Hf:Zr supercycle ratio was used, meaning one HfO2 cycle was deposited followed by one ZrO2 cycle, alternating between the two, until an Hf layer was finally grown. 0.5 Zr 0.5 O2 thin film;

[0095] Then, photoresist is applied, and the surface is exposed and developed; after annealing, the ultrathin Hf... 0.5 Zr 0.5 Photoresist was coated on the O2 ferroelectric dielectric layer, pre-baked at 150°C for 2 minutes, exposed and then post-baked at 120°C for 2 minutes. The layer was then immersed in the developer for 55 seconds and developed, rinsed with deionized water and dried.

[0096] Next, a 40nm TiN top electrode was grown by magnetron sputtering. The magnetron sputtering process used a TiN target, a DC sputtering power of 100W, and an Ar gas flow rate of 1.15mTorr.

[0097] Then, a patterned top electrode is obtained through a stripping process; it is then immersed in an acetone solution until the photoresist and excess metal are removed, followed by immersion in anhydrous ethanol to remove the acetone, and then rinsed with deionized water and dried.

[0098] Finally, the ultrathin ferroelectric dielectric layer was directly treated in an N2 atmosphere using a rapid thermal annealing process, with a heating rate controlled at 15-20℃ / s, an annealing temperature of 600℃, and an annealing time of 30s; thus obtaining an ultrathin HfO2-based ferroelectric capacitor.

[0099] like Figure 5 As shown, the 4nm HfO2-based ferroelectric capacitor prepared in Comparative Example 2 exhibits severe initial-state pinning hysteresis, with an initial polarization intensity 2Pr < 5 μC / cm. 2 And it requires 10 7 It takes several cycles to fully wake up.

[0100] Comparative Example 3

[0101] First, a 40nm W bottom electrode was grown on a SiO2 / Si substrate by magnetron sputtering. The magnetron sputtering process used a W target, a DC sputtering power of 100W, and an Ar gas flow rate of 3mTorr.

[0102] Secondly, a 5nm ultrathin Hf layer is deposited on the bottom electrode using atomic layer deposition technology. 0.5 Zr 0.5 An O2 ferroelectric dielectric layer was deposited at a temperature of 250℃. A 1:1 Hf:Zr supercycle ratio was used, meaning one HfO2 cycle was deposited followed by one ZrO2 cycle, alternating between the two, until an Hf layer was finally grown. 0.5 Zr 0.5 O2 thin film;

[0103] Then, photoresist is applied, and the surface is exposed and developed; after annealing, the ultrathin Hf... 0.5 Zr 0.5 Photoresist was coated on the O2 ferroelectric dielectric layer, pre-baked at 150°C for 2 minutes, exposed and then post-baked at 120°C for 2 minutes. The layer was then immersed in the developer for 55 seconds and developed, rinsed with deionized water and dried.

[0104] Next, a 40nm W top electrode was grown by magnetron sputtering. The magnetron sputtering process used a W target, a DC sputtering power of 100W, and an Ar gas flow rate of 1.15mTorr.

[0105] Then, a patterned top electrode is obtained through a stripping process; it is then immersed in an acetone solution until the photoresist and excess metal are removed, followed by immersion in anhydrous ethanol to remove the acetone, and then rinsed with deionized water and dried.

[0106] Finally, the ultrathin ferroelectric dielectric layer was directly treated in an N2 atmosphere using a rapid thermal annealing process, with a heating rate controlled at 15-20℃ / s, an annealing temperature of 600℃, and an annealing time of 30s; thus obtaining an ultrathin HfO2-based ferroelectric capacitor.

[0107] Example 4

[0108] This embodiment is basically the same as Embodiment 1, the main difference being that the substrate is a Si layer.

[0109] Example 5

[0110] This embodiment is basically the same as embodiment 1, the main difference being that both the bottom and top electrodes use W electrodes.

[0111] Example 6

[0112] This embodiment is basically the same as embodiment 1, the main difference being that both the bottom and top electrodes use Ru electrodes.

[0113] Example 7

[0114] This embodiment is basically the same as Embodiment 1, the main difference being that: in the deposition of the ferroelectric dielectric layer, tetra(diethylamino)zirconium (TDMAZr) is used as the Zr precursor source and tetra(diethylamino)hafnium (TDMAHf) is used as the Hf precursor source.

[0115] Example 8

[0116] This embodiment is basically the same as Embodiment 1, the main difference being that the thickness of the ferroelectric dielectric layer is 3.5 nm.

[0117] Example 9

[0118] This embodiment is basically the same as Embodiment 1, the main difference being that the thickness of the bottom electrode and the top electrode is 10nm.

[0119] Example 10

[0120] This embodiment is basically the same as Embodiment 1, with the main difference being that: during the annealing process, the heating rate is controlled at 25-30℃ / s, the annealing temperature is 400℃, and the annealing time is 900s.

[0121] Example 11

[0122] This embodiment is basically the same as Embodiment 1, the main difference being that the temperature at which the ferroelectric layer is deposited by atomic layer deposition is 300°C.

[0123] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A ferroelectric capacitor for improving initial-state polarization intensity, characterized in that, It includes a substrate, a bottom electrode, an ultrathin ferroelectric layer, and a top electrode, which are stacked sequentially from bottom to top; The ultrathin ferroelectric layer is Hf 1-x Zr x O2 thin film, 0 <x<0.5; The ultrathin ferroelectric layer is grown into an Hf-rich film by controlling the Hf:Zr supercycle ratio during atomic layer deposition.

2. A ferroelectric capacitor for improving initial state polarization intensity according to claim 1, characterized in that, The substrate includes SiO2 / Si wafers and Si wafers.

3. A ferroelectric capacitor for improving initial state polarization intensity according to claim 1, characterized in that, The materials of the bottom electrode and the top electrode include TiN, W, Ru, Mo, Ta, TaN, Ti, and Pt; the thickness of the bottom electrode and the top electrode is 2-100 nm.

4. A ferroelectric capacitor for improving initial state polarization intensity according to claim 1, characterized in that, The ultrathin ferroelectric layer is Hf 0.6 Zr 0.4 The O2 thin film has an Hf:Zr supercycle ratio controlled at 3:2 during atomic layer deposition; the thickness of the ultrathin ferroelectric layer is 1-6 nm.

5. A method for preparing a ferroelectric capacitor with enhanced initial-state polarization intensity as described in any one of claims 1-4, characterized in that, Includes the following steps: Step 1: Grow the bottom electrode on the substrate surface; Step 2: Deposit an ultrathin ferroelectric layer on the bottom electrode surface using atomic layer deposition (ALD), wherein the Hf:Zr supercycle ratio is controlled to be higher than 1:1 during the ALD deposition process. Step 3: Coat the ultrathin ferroelectric layer with photoresist and expose and develop it, then grow the top electrode on its surface; Step 4: Peeling process; Step 5: Post-annealing.

6. The method for preparing a ferroelectric capacitor with enhanced initial-state polarization intensity according to claim 5, characterized in that, In steps 1 and 3, the growth is magnetron sputtering growth; The magnetron sputtering growth used a TiN target, with a DC sputtering power of 100W and an Ar gas flow rate of 1.15 mTorr; or, The magnetron sputtering process described uses a W target, a DC sputtering power of 100W, and an Ar gas flow rate of 3 mTorr; or, The magnetron sputtering process used a Ru target, a DC sputtering power of 100W, and an Ar gas flow rate of 3mTorr.

7. The method for preparing a ferroelectric capacitor with enhanced initial-state polarization intensity according to claim 5, characterized in that, In step 2, the atomic layer deposition process is as follows: In a complete supercycle, three cycles of HfO2 layers are first deposited using an Hf precursor source and an oxygen source, followed by two cycles of ZrO2 layers deposited using a Zr precursor source and an oxygen source; this process is repeated until an Hf-rich ultrathin Hf layer is formed. 1-x Zr x O2 thin film.

8. The method for preparing a ferroelectric capacitor with improved initial state polarization intensity according to claim 5, characterized in that, In step 2, the atomic layer deposition process includes: The Zr precursor sources used include tetra(ethylmethylamino)zirconium and tetra(diethylamino)zirconium; and / or, The Hf precursor sources used include tetra(ethylmethylamino)hafnium and tetra(diethylamino)hafnium; and / or, The oxygen sources used include deionized water, hydrogen peroxide, and ozone.

9. A method for preparing a ferroelectric capacitor with enhanced initial-state polarization intensity according to claim 5, characterized in that, In step 5, the post-annealing process is carried out in an inert atmosphere, with a heating rate of 10-30℃ / s, an annealing temperature of 300-700℃, and an annealing time of 10s-10h.

10. The application of a ferroelectric capacitor with enhanced initial-state polarization intensity as described in any one of claims 1-4 in a non-volatile memory.

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