Compound and preparation method thereof, ferroelectric film and preparation method thereof, and memory

Abstract

The invention provides a compound and a preparation method thereof, a ferroelectric film and a preparation method thereof, and a memory. The compound provided by the invention has a structure as shown in a formula (1): in the formula (1), M is a group IV transition metal. The compound disclosed by the invention can be used as a precursor material for preparing a ferroelectric film, so that the thermal stability of a Zr source precursor is improved, and the impurity concentration in the ferroelectric film is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of storage devices, in particular to a compound and a preparation method thereof, a ferroelectric thin film and a preparation method thereof, and a memory. BACKGROUND

[0002] Ferroelectric random access memory (FeRAM) has gradually become one of the most potential devices of new generation storage technology due to the characteristics of high-speed reading and writing, non-volatility, low power consumption level, and compatibility with complementary metal-oxide-semiconductor (CMOS) process. The core part of the ferroelectric memory is a device structure of metal-ferroelectric thin film-metal, and the ferroelectric thin film serves as the insulating medium of the capacitor. The ferroelectric thin film undergoes polarization reversal under electric field in different directions, causing the charging and discharging of the capacitor, thereby realizing the storage state of “0” or “1”. The traditional ferroelectric thin film is mainly represented by PbTiO3 perovskite ferroelectric material. The band gap of this material is small, resulting in large leakage and inability to be miniaturized, and the preparation process is not compatible with CMOS, which greatly limits its application. Compared with the traditional ferroelectric material, the hafnium oxide-based ferroelectric material has a wide band gap, small leakage, low power consumption, good cycle performance, and can be miniaturized. The ferroelectricity is still possessed when the thickness is reduced to below 10 nm, and the device preparation process is compatible with CMOS. These characteristics make the hafnium oxide-based ferroelectric material have unique advantages in constructing high-density storage chips.

[0003] The hafnium oxide-based ferroelectric material is usually a thin film material of 10 nm order of magnitude obtained by depositing hafnium oxide (HfO2) doped with zirconium oxide (ZrO2) at high temperature using atomic layer deposition technology. Generally speaking, higher deposition temperature can reduce the content of impurities such as C, N, H in the thin film, and the uniformity of the thin film will also be improved, which is beneficial to the formation of ferroelectric phase O-phase, so that the ferroelectric material thin film has excellent ferroelectric flip characteristics. However, the insufficient thermal stability of the precursor will cause thermal decomposition at high temperature, thereby destroying the self-limited thin film growth mechanism, which will affect the quality of film formation. Therefore, improving the thermal stability of the precursor of atomic layer deposition is crucial for growing ferroelectric thin films with excellent performance. Through the optimization design of the molecular structure of the precursor, a HfO2 precursor source with high thermal stability can be obtained. However, the thermal stability of the Zr source precursor for forming ZrO2 is significantly lower than that of the Hf-source precursor, which makes the deposition of hafnium oxide-based ferroelectric thin film (H 0.5 Z 0.5The temperature of the Zr source precursor is limited by the thermal stability of the zirconium oxide source precursor. Therefore, during the deposition and growth of the hafnium oxide-based ferroelectric thin film, the thermal stability of the Zr source precursor is difficult to match that of the Hf source precursor, thereby limiting the deposition of the thin film at a higher temperature, resulting in an increase in impurity atoms in the thin film, a small O-phase ratio, and a reduction in the ferroelectric switching characteristics of the ferroelectric thin film material. SUMMARY

[0004] The present application provides a compound and a preparation method thereof, a ferroelectric thin film and a preparation method thereof, and a memory, to improve the thermal stability of the Zr source precursor and reduce the impurity concentration in the ferroelectric thin film.

[0005] In a first aspect, the present application provides a compound having a structure as shown in formula (1):

[0006]

[0007] wherein M is a group IV transition metal;

[0008] R1, R2, R3, R4, R5, and R6 are each independently selected from one of C1-C3 alkyl groups;

[0009] Cp is a cyclopentadienyl group, and Z is N or Cp;

[0010] When Z is N, the value of a is 2; when Z is Cp, the value of a is 1-5;

[0011] The value of b is 1-5.

[0012] When Z is N, two amine groups are present in the compound of the present application. When Z is a cyclopentadienyl group, two cyclopentadienyl groups are present in the compound of the present application. When Z is a cyclopentadienyl group, the hydrogen in Z can also be substituted with a C1-C3 alkyl group.

[0013] The compound of the present application has the following advantages: 1) the compound of the present application has at least one amine group -N(R1)2, so that the compound has high reactivity and certain volatility, facilitating deposition. In the compound, R1 is selected from C1-C3 alkyl, so that the elimination reaction of β-carbon and H at high temperature can be avoided, and the decomposition of the alkyl chain can be avoided, thereby making the compound have high stability. 2) In the compound of the present application, at least one amidine group exists, and the amidine group forms a cyclic structure with the central atom M. This chelating structure can effectively stabilize the central atom and is more stable in energy, so that the compound of the present application has excellent thermal stability. In addition, in the compound of the present application, there is only one amidine group, so as to prevent the space steric hindrance of the compound from being too large, thereby causing the formation rate of the ferroelectric thin film to be too slow during deposition. 3) In the compound of the present application, at least one cyclopentadienyl ligand Cp exists. Cp is an electron-donating group, and has good binding force with the electron-deficient metal atom M. The electron-donating ability of the Cp ligand can be adjusted by changing the number of alkyl groups on the Cp ligand, so as to further improve the thermal stability. At the same time, the ligand has good growth rate and reactivity, so that the ferroelectric thin film has a fast formation rate.

[0014] In the compound of the present application, the C1-C3 alkyl group can be selected from at least one of methyl, ethyl and isopropyl.

[0015] In an optional implementation, the number of substituted hydrogens in the cyclopentadienyl group can be 1-5. In the cyclopentadienyl group, at least one R3 exists in the substituent group, so that the cyclopentadienyl group has high electron-donating ability, and the reactivity of the compound of the present application is improved. It can be understood that, in the cyclopentadienyl group, in addition to the substituent group R3, other substituent groups can also exist, and the number of the other substituent groups can be 0-4.

[0016] In an optional implementation, the substituent groups in the cyclopentadienyl group are all methyl groups. When the substituent groups in the cyclopentadienyl group are all methyl groups, the stability of the compound can be improved, and the heat resistance of the compound is further improved.

[0017] In an optional implementation, R4, R5 and R6 are all methyl groups. When R4, R5 and R6 are all methyl groups, the amidine group has higher stability, and the decomposition of the alkyl chain that is too long can be avoided, thereby reducing the thermal stability of the compound.

[0018] In an optional implementation, Z is N, and R2 is a methyl group or an ethyl group. In an optional implementation, R1 is a methyl group or an ethyl group.

[0019] In a second aspect, the present application provides a preparation method of a compound with a structure shown in formula (1), and the preparation method comprises the following steps:

[0020] The compound M(NAr2)4 is obtained by substituting m -NAr2 groups in the compound M(NAr2)4, wherein one -NAr2 group in the compound M(NAr2)4 is substituted by an amidine group, and the remaining -NAr2 groups in the m -NAr2 groups are substituted by cyclopentadienyl groups with substituents, wherein Ar is selected from C1-C3 alkyl, and m is 2 or 3.

[0021] In a third aspect, the present application provides a preparation method of a ferroelectric thin film, which comprises the following steps:

[0022] Depositing at least a plurality of precursor layers comprising a compound of the present application on a surface of a substrate, and forming the ferroelectric thin film by oxidizing or nitriding the precursor layers.

[0023] As an optional implementation, the preparation method specifically comprises the following steps:

[0024] Depositing a hafnium source precursor on the surface of the substrate, and forming a hafnium oxide layer by oxidizing the hafnium source precursor; wherein, the hafnium source precursor can be CpHf(NMe2)3 or a compound having a structure shown in formula (1), and M in the structure shown in formula (1) is Hf.

[0025] Depositing a zirconium source precursor on the surface of the hafnium oxide layer, and forming the zirconium oxide layer by oxidizing the zirconium source precursor; the zirconium source precursor is a zirconium source compound having a structure shown in formula (1), and M in the structure shown in formula (1) is Zr.

[0026] Repeating the above process to form the hafnium oxide layer and the zirconium oxide layer arranged alternately, and obtaining the ferroelectric thin film.

[0027] As another optional implementation, the preparation method specifically comprises the following steps:

[0028] Depositing a zirconium source compound having a structure shown in formula (1) on a surface of a substrate, and forming a zirconium oxide thin film or a zirconium nitride thin film by oxidizing or nitriding;

[0029] Repeating the above process to form the ferroelectric thin film, and the ferroelectric thin film has a plurality of zirconium oxide thin films or zirconium nitride thin films arranged in layers.

[0030] In the implementation of the present application, the deposition temperature of the compound shown in formula (1) is 330-380℃. In the preparation method of the present application, the deposition of the precursor compound can be realized at high temperature, which can reduce impurities such as C, N, H, O, etc. in the ferroelectric thin film, so as to improve the 0 phase ratio and further improve the flipping characteristics of the ferroelectric thin film.

[0031] In a fourth aspect, the present application provides a ferroelectric thin film prepared by the preparation method of the present application.

[0032] In a fifth aspect, the present application provides a memory, which comprises the ferroelectric thin film of the present application, and electrodes are arranged on two surfaces of the ferroelectric thin film respectively.

[0033] The memory of the present application may, for example, be a planar ferroelectric random access memory (FeRAM), a 3D FeRAM, or a dynamic random access memory (DRAM).

[0034] The technical effects achieved by the second to fifth aspects described above can be referred to the corresponding effect descriptions of the first aspect, which will not be repeated here. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 Structure diagram of a core component of FeRAM;

[0036] Figure 2 Preparation flow diagram of the ferroelectric thin film material of Example 1;

[0037] Figure 3 Structure diagram of a planar FeRAM of an embodiment;

[0038] Figure 4 Preparation flow diagram of the ferroelectric thin film material of Example 2;

[0039] Figure 5 Structure diagram of a 3D FeRAM of an embodiment;

[0040] Figure 6 Preparation flow diagram of the ferroelectric thin film material of Example 3;

[0041] Figure 7 Preparation flow diagram of the ferroelectric thin film material of Example 4.

[0042] Reference signs:

[0043] 10 - substrate; 11 - metal electrode; 12 - ferroelectric thin film; 13 - first metal electrode; 14 - second metal electrode. DETAILED DESCRIPTION

[0044] In order to make the purposes, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings.

[0045] The terms used in the following embodiments are only for the purpose of describing specific embodiments and are not intended to limit the present application. As used in the specification and appended claims of this application, the singular expressions "a", "an", "above", "the", and "this" are intended to also include expressions such as "one or more", unless the context clearly indicates otherwise.

[0046] References to "one embodiment" or "some embodiments" in this specification mean that a particular feature, structure, or characteristic described in conjunction with that embodiment is included in one or more embodiments of the present application. Thus, phrases such as "in one embodiment," "in some embodiments," "in other embodiments," and "in yet other embodiments" appearing in various places in this specification do not necessarily refer to the same embodiment, but rather mean "one or more but not all embodiments," unless otherwise specifically emphasized. The terms "including," "comprising," "having," and variations thereof mean "including but not limited to," unless otherwise specifically emphasized.

[0047] In the field of ferroelectric storage, FeRAM has gradually become one of the most promising devices for the new generation of storage technology due to its high-speed reading and writing, non-volatility, low power consumption and compatibility with CMOS processes. Figure 1 The schematic diagram of the structure of the core components of FeRAM is as follows: Figure 1 As shown, the metal electrode 11-ferroelectric film 12-metal electrode 11 constitutes a ferroelectric capacitor. Its main working principle is that an electric field is applied to the ferroelectric film 12 through the metal electrodes 11 on both sides of the ferroelectric film 12. The ferroelectric film 12 undergoes polarization reversal under electric fields in different directions, causing the capacitor to charge and discharge, thereby realizing the storage state of "0" or "1". In the ferroelectric film 12, the hafnium oxide-based ferroelectric material has the advantages of a wide band gap, low leakage, low power consumption, and good cycle performance, which makes the hafnium oxide-based ferroelectric material have unique advantages in constructing high-density memory chips. However, the hafnium oxide-based ferroelectric film (H 0.5 Z 0.5 During the deposition and growth process of O2, the thermal stability of the Zr source precursor is difficult to match that of the Hf source precursor, which in turn limits the deposition of thin films at higher temperatures, making it difficult to obtain ferroelectric films with fewer impurities and a higher proportion of the O-phase. If the precursor ligand uses a single ligand, its properties will become single. For example, using only -NEtMe as a ligand will result in too low thermal stability; using only amidine as a ligand will result in too low a growth rate. Even if a heteroleptic strategy such as cyclopentadienyl Cp and -NMe2 is adopted, the molecular structure still needs to be optimized to meet the high-temperature resistance of the precursor.

[0048] The compound provided by the embodiment of the present application can be used as a Zr source precursor and a Hf source precursor, etc. The compound has high thermal stability, so that the deposition temperature of the precursor can be increased when the ferroelectric thin film is prepared, the impurities in the ferroelectric thin film are reduced, the 0-phase proportion in the ferroelectric thin film is increased, and the flipping characteristic of the ferroelectric thin film is improved.

[0049] The structure of the compound provided by the embodiment of the present application is shown in the following formula (1):

[0050]

[0051] wherein M is a group IV transition metal. For example, M is Zr or Hf.

[0052] Cp is a cyclopentadienyl group, and Z is N or Cp. When Z is N, a is 2; when Z is Cp, a is 1-5. b is 1-5.

[0053] When Z is N, two amine groups exist in the compound provided by the embodiment of the present application. When Z is a cyclopentadienyl group, two cyclopentadienyl groups exist in the compound provided by the embodiment of the present application. When Z is a cyclopentadienyl group, the hydrogen in Z can also be substituted by a C1-C3 alkyl group.

[0054] R1, R2, R3, R4, R5, and R6 are each independently selected from one of C1-C3 alkyl groups. The C1-C3 alkyl group can be selected from at least one of a methyl group, an ethyl group, and an isopropyl group. For example, R1 can be a methyl group or an ethyl group. When Z is N, R2 can be a methyl group or an ethyl group. When Z is a cyclopentadienyl group, R2 can be a methyl group. R3 can be a methyl group. R4, R5, and R6 are each a methyl group. When R1 to R6 are selected from the above groups, the compound can have a more stable structure, and can have better reaction activity and volatilization performance. When the compound is used as a precursor of a deposition material, the heat resistance and dispersion uniformity of the precursor can be improved, so that a uniform and dense ferroelectric thin film can be obtained.

[0055] In formula (1), the hydrogen in the ring structure of the cyclopentadienyl group can be substituted by a C1-C3 alkyl group. When Z is a cyclopentadienyl group, the hydrogen in Z can also be substituted by a C1-C3 alkyl group.

[0056] In addition, in formula (1), the total number of substituents R3 in the cyclopentadienyl group is 1-5. Of the 1-5 substituents, R3 is one of them. In addition to R3, the number of other substituents on the cyclopentadienyl group is 0-4, that is, in addition to R3, the hydrogen at other positions in the ring structure of the cyclopentadienyl group can be substituted or not substituted. When Z is a cyclopentadienyl group, the total number of substituents is also 1-5. Of the 1-5 substituents, R2 is one of them. In addition to R2, the number of other substituents on the cyclopentadienyl group is 0-4, that is, in addition to R2, the hydrogen at other positions in the ring structure of the cyclopentadienyl group can be substituted or not substituted. When there is only one substituent on the cyclopentadienyl group, the remaining position is hydrogen.

[0057] The compound of the embodiment of the present application has at least one amine group -N(R1)2, one amidine group, and one cyclopentadienyl group with a substituent R3. Among them, the amine group can keep the compound with high reactivity and certain volatility, facilitating deposition. Among them, R1 is selected from C1-C3 alkyl, which can avoid the elimination reaction of β-carbon and H at high temperature, avoid the decomposition of the alkyl chain, so that the compound has high stability. The amidine group forms a ring structure with the central atom M, and this chelate structure can effectively stabilize the central atom, which is more stable in energy, so that the compound of the present application has excellent thermal stability. In addition, in the compound of the present application, there is only one amidine group, so as to prevent the space steric hindrance of the compound from being too large, causing the formation rate of the ferroelectric thin film to be too slow during deposition. The cyclopentadienyl ligand can act as an electron-donating group and has good binding force with the electron-deficient metal atom M, and the electron-donating ability of the cyclopentadienyl ligand can be adjusted by changing the number of alkyl groups on the cyclopentadienyl ligand, so as to further improve the thermal stability. At the same time, the ligand has good growth rate and reactivity, so that the ferroelectric thin film has a faster formation rate.

[0058] The compound of the structure shown in formula (1) can be obtained by using the following preparation method, which specifically comprises the following steps:

[0059] The compound is obtained by substituting m -NAr2 groups in the compound M(NAr2)4, wherein one -NAr2 group in the compound M(NAr2)4 is substituted by an amidine group, and the remaining -NAr2 groups in the m -NAr2 groups are substituted by cyclopentadienyl groups with substituents, wherein Ar is selected from C1-C3 alkyl, and m is 2 or 3.

[0060] For example, the compound M(NAr2)4 is the compound Zr(NMe2)4. The following will take the compound Zr(NMe2)4 as an example to explain the substitution process.

[0061] As an example, the preparation method of one embodiment of the compound of the present application can include the following reaction process:

[0062] 1) Zr(NMe2)4 + HCpMe → (CpMe)Zr(NMe2)3 + NHMe2

[0063] 2) (CpMe)Zr(NMe2)3 + NMe(CMe)NMeH → (CpMe)Zr(NMe2)2 amd + NHMe2.

[0064] In the compounds involved in the above reaction process, Me is methyl, anmd is amidine, and Cp is cyclopentadienyl.

[0065] The compound of the embodiment of the present application can be used to prepare a ferroelectric thin film. The preparation method of the ferroelectric thin film can include the following steps: depositing at least a plurality of precursor layers containing the compound of the present application on the surface of a substrate, and forming the ferroelectric thin film after oxidation or nitridation of the precursor layers. In the preparation method, the deposition method can be an atomic layer deposition method.

[0066] Illustratively, in one embodiment, the preparation method of the ferroelectric thin film includes the following steps:

[0067] S1, depositing a hafnium source precursor on the surface of the substrate, and oxidizing the hafnium source precursor to form a hafnium oxide layer; illustratively, the hafnium source precursor is CpHf(NMe2)3 or a compound having the structure shown in formula (1), wherein M in the structure shown in formula (1) is Hf;

[0068] S2, depositing a zirconium source precursor on the surface of the hafnium oxide layer, and oxidizing the zirconium source precursor to form the zirconium oxide layer; the zirconium source precursor is a zirconium source compound having the structure shown in formula (1), wherein M in the structure shown in formula (1) is Zr;

[0069] S3, repeating the above process to form alternating hafnium oxide layers and zirconium oxide layers to obtain the ferroelectric thin film.

[0070] In the above process, the deposition temperature of the hafnium source precursor and the zirconium source precursor having the structure shown in formula (1) can be 330-380°C, such as 340-360°C.

[0071] Illustratively, in another embodiment, the preparation method of the ferroelectric thin film includes the following steps:

[0072] S1, depositing a zirconium source compound having the structure shown in formula (1) on the surface of a substrate, and forming a zirconium oxide thin film or a zirconium nitride thin film after oxidation or nitridation;

[0073] S2, repeating the above process to form a ferroelectric thin film having a plurality of layers of zirconium oxide thin films or zirconium nitride thin films arranged in a stack.

[0074] The deposition temperature of the zirconium source precursor can be 330-380°C, such as 340-360°C.

[0075] In the preparation method of the above embodiment, the deposition of the precursor compound can be achieved at high temperature, which can reduce impurities such as C, H, and O in the ferroelectric thin film, thereby increasing the O phase ratio and improving the 0-1 phase switching characteristics of the ferroelectric thin film.

[0076] The ferroelectric thin film obtained by the preparation method of the present application can be used to manufacture a memory, such as a planar FeRAM, a 3D FeRAM, a dynamic random access memory, and the like. In the manufactured memory, the two sides of the ferroelectric thin film are provided with a conductive layer, such as a metal conductive layer, specifically, a silver layer, a copper layer, a gold layer, and the like.

[0077] The structure, performance, and preparation process of the ferroelectric thin film of the present application will be described in detail below in combination with specific embodiments and comparative examples.

[0078] Embodiment 1

[0079] This embodiment is a preparation method of a ferroelectric thin film material in a planar FeRAM, and the specific process is as shown in Figure 2 The structure of the obtained planar FeRAM is as shown in Figure 3 As shown in Figure 3 The structure of the planar FeRAM includes a substrate 10 and a first metal electrode 13 with a planar structure provided on the substrate 10. The surface of the first metal electrode 13 is provided with the ferroelectric thin film 12 of the present embodiment, and the surface of the ferroelectric thin film 12 is provided with a second metal electrode 14.

[0080] Specifically, the preparation method of the ferroelectric thin film material includes the following steps:

[0081] S11, the reaction chamber is controlled at 350°C, and a high-temperature-resistant CpHf(NMe2)3 is first introduced as a hafnium source precursor to deposit a layer of hafnium source precursor intermediate product attached to the surface of the substrate, and then an inert gas is introduced to remove excess gas and products.

[0082]

[0083] S12, ozone is introduced to oxidize the C, N, H, and other elements of the intermediate product, and generate corresponding oxide gas for removal.

[0084] S13, a new zirconium source precursor (CpMe)Zr(NMe2)2amd is introduced into the reaction chamber, and the structure of (CpMe)Zr(NMe2)2amd is as shown in the following formula. The intermediate product of the zirconium source is obtained by reaction at high temperature, and then an inert gas is introduced to remove excess gas and products.

[0085]

[0086] S14, finally, ozone is introduced to oxidize the C, N, H and other elements of the intermediate product to generate corresponding oxide gas to be discharged.

[0087] S15, thus, the HfO2 and ZrO2 atomic layers are alternated to obtain Hf 0.5 Zr 0.5 O2 ferroelectric thin film.

[0088] Embodiment 2

[0089] This embodiment is a preparation method of a ferroelectric thin film material in a 3D structure FeRAM, and the specific process is shown in Figure 4 The structure of the obtained 3D structure FeRAM is shown in Figure 5 As shown in Figure 5 The structure of the 3D structure FeRAM includes a substrate 10, a first metal electrode 13 with a groove structure arranged on the substrate 10, and a second metal electrode 14 matched with the first metal electrode 13. The second metal electrode 14 is in a T-shaped structure and is inserted into the groove structure of the first metal electrode 13. The ferroelectric thin film 12 of the embodiment of the present application is arranged between the inner wall of the groove structure of the first metal electrode 13 and the outer wall of the second metal electrode 14. In the groove structure of the first metal electrode 13, the first metal electrode 13 and the second metal electrode 14 are insulated by the ferroelectric thin film 12.

[0090] Specifically, the preparation method of the ferroelectric thin film material includes the following steps:

[0091] S11, the reaction chamber is controlled at 350°C, and first, a high-temperature-resistant CpHf(NMe2)3 is introduced as a hafnium source precursor to deposit a layer of hafnium source precursor on the surface of the substrate with a 3D structure to form an intermediate product, and then an inert gas is introduced to discharge excess gas and products.

[0092] S12, then, ozone is introduced to oxidize the C, N, H and other elements of the intermediate product to generate corresponding oxide gas to be discharged.

[0093] S13, a new zirconium source precursor (CpMe)Zr(NMe2)2amd is introduced into the reaction chamber, and a zirconium source is obtained by reacting at high temperature to adhere to the intermediate product of the substrate, and then an inert gas is introduced to discharge excess gas and products.

[0094] S14, finally, ozone is introduced to oxidize the C, N, H and other elements of the intermediate product to generate corresponding oxide gas to be discharged.

[0095] S15, thus alternately growing HfO2 and ZrO2 atomic layers to obtain Hf 0.5 Zr 0.5 O2 ferroelectric thin film.

[0096] Example 3

[0097] This example is a method for preparing a ferroelectric thin film material in a planar FeRAM, and the specific process is shown in Figure 6 The structure of the obtained 3D structure FeRAM is shown in Figure 5 Specifically, the preparation method comprises the following steps:

[0098] S11, the reaction chamber is controlled at 350°C, and a zirconium source precursor (CpMe)Zr(NMe2)2amd is introduced into the chamber. After several seconds of reaction, the hydrogen atoms in the hydroxyl groups of the hydroxylated substrate surface will combine with the two -NMe2 ligands of the precursor.

[0099] S12, the reaction product is discharged by introducing an inert gas to obtain an intermediate product in which the zirconium precursor is attached to the substrate.

[0100] S13, ozone is introduced to provide an oxygen source, and the C, N, and H elements in the intermediate product are oxidized to form the corresponding oxides. Subsequently, an inert gas is introduced to discharge the gas product, thereby obtaining a layer of ZrO2 thin film.

[0101] S14, thus alternately growing HfO2 and ZrO2 atomic layers to obtain Hf

[0102] Example 4

[0103] This example is a method for preparing a ferroelectric thin film material in a planar FeRAM, and the specific process is shown in Figure 7 The structure of the obtained planar FeRAM is shown in Figure 3 Specifically, the preparation method comprises the following steps:

[0104] S11, the reaction chamber is controlled at 350°C, and a zirconium source precursor (CpMe)Zr(NMe2)2amd is introduced into the chamber. After several seconds of reaction, the hydrogen atoms in the hydroxyl groups of the hydroxylated substrate surface will combine with the two -NMe2 ligands of the precursor.

[0105] S12, nitrogen plasma is introduced to provide a nitrogen source, which can break the coordination bond of the precursor to form new Zr-N bonds. Subsequently, a carrier gas is introduced to discharge excess gas and product, thereby obtaining a layer of ZrN thin film.

[0106] S13, thus alternately growing HfO2 and ZrO2 atomic layers to obtain Hf

[0107] Comparative Example 1

[0108] The comparative example is a preparation method of a ferroelectric thin film material in a planar FeRAM, comprising the following steps:

[0109] S11, the reaction chamber is controlled at 240°C, Zr(NMe2)4 is introduced into the chamber as a zirconium source precursor, the structural formula of Zr(NMe2)4 is as shown below, the zirconium source precursor is chemisorbed on the substrate, and then inert gas is introduced to discharge the extra zirconium source precursor and the gas product.

[0110]

[0111] S12, ozone is introduced as an oxygen source to oxidize C, N and H elements in the intermediate product to generate corresponding oxides, and then inert gas is introduced to discharge the gas product, thereby obtaining a ZrO2 thin film.

[0112] S13, the above steps are repeated to grow layer by layer until the target thickness is reached.

[0113] Comparative Example 2

[0114] The comparative example is a preparation method of a ferroelectric thin film material in a planar FeRAM, comprising the following steps:

[0115] S11, the reaction chamber is controlled at 300°C, Zr(amd)4 is introduced into the chamber as a zirconium source precursor, the structural formula of Zr(amd)4 is as shown below, the zirconium source precursor is chemisorbed on the substrate, and then inert gas is introduced to discharge the extra zirconium source precursor and the gas product.

[0116]

[0117] S12, ozone is introduced as an oxygen source to oxidize C, N and H elements in the intermediate product to generate corresponding oxides, and then inert gas is introduced to discharge the gas product, thereby obtaining a ZrO2 thin film.

[0118] S13, the above steps are repeated to grow layer by layer until the target thickness is reached.

[0119] Comparative Example 3

[0120] The comparative example is a preparation method of a ferroelectric thin film material in a planar FeRAM, comprising the following steps:

[0121] S11, the reaction chamber is controlled at 300°C, CpZr(NMe2)3 is introduced into the chamber as a zirconium source precursor, the structural formula of CpZr(NMe2)3 is as shown below, the zirconium source precursor is chemisorbed on the substrate, and then inert gas is introduced to discharge the extra zirconium source precursor and the gas product.

[0122]

[0123] S12, ozone is introduced as the oxygen source to oxidize the C, N, H elements in the intermediate product to generate corresponding oxides, and then inert gas is introduced to discharge the gas product to obtain a ZrO2 film.

[0124] S13, the cycle is repeated until the target thickness is reached.

[0125] The growth rate of the ferroelectric film of each example and the comparative example is recorded respectively, and the specific values are listed in Table 1. In addition, the ferroelectric film of each example and the comparative example is used to make a memory. The leakage performance and ferroelectric flip characteristics of each sample memory are tested. The test results are listed in Table 1.

[0126] Table 1

[0127]

[0128] Example 1 by depositing Hf 0.5 Z 0.5 O2 ferroelectric film at a high temperature of 350°C in a planar FeRAM, as shown in Figure 3 , since the deposition temperature is high, the density of the ferroelectric film can be effectively improved, and the possibility of impurity contamination can be reduced, promoting the formation of ferroelectric phase.

[0129] Example 2 by depositing a new zirconium source precursor with high thermal stability at a high temperature of 350°C in combination with a hafnium source precursor with high thermal stability, can grow Hf 0.5 Z 0.5 O2 ferroelectric film with excellent ferroelectric properties on a 3D FeRAM at a high temperature, as shown in Figure 5 , solving the problem of poor thermal stability of zirconium source that cannot be co-deposited with hafnium source precursor.

[0130] Example 3 by depositing ZrO2 film at a high temperature of 350°C in a 3D-DRAM, as shown in Figure 5 , can effectively improve the density of the film, and reduce the possibility of impurity contamination, and improve the dielectric constant.

[0131] Example 4 by depositing ZrN film as the electrode and element barrier layer of FeRAM at a high temperature of 350°C, as shown in Figure 3 , can effectively improve the density of the film, and reduce the possibility of impurity contamination, thereby reducing the resistivity and improving the barrier ability.

[0132] The bond energy between the metal atom and the nitrogen atom of the amine-based ligand in the zirconium source precursor in Comparative Example 1 is low and easy to break, and therefore, the main disadvantage of such a precursor is poor thermal stability, and only self-limited ALD type thin film growth can be performed at a temperature of not more than 250°C. When the temperature exceeds this temperature, the thin film deposition rate will greatly increase, and the thin film quality will greatly decrease. At the same time, due to thermal decomposition of the precursor, the impurity content such as C, N, H and the like in the generated thin film will be significantly increased, affecting the formation of the ferroelectric phase and thus affecting the ferroelectric performance.

[0133] In Comparative Example 2, due to the large molecular size of each amidine-based ligand, the steric hindrance is large, resulting in a too low growth rate GPC, which is only per cycle, which seriously reduces the production efficiency of the ferroelectric thin film. In addition, due to the high intermolecular force, the precursor of such a ligand is usually solid at room temperature, which will generate the risk of introducing particles to the substrate, reducing the uniformity of the ferroelectric thin film, and thus affecting the performance of the ferroelectric thin film.

[0134] In Comparative Example 3, since the HfO2thin film generated by the precursor CpHf(NMe2)3of HfO2at a temperature of ≥300°C has a purity and O / Hf ratio that are both lower than those of the thin film generated at a temperature of <300°C, even if the thermal stability of the zirconium source precursor in Comparative Example 3 is improved by using the method of “hetero-matching” stacking the cyclopentadienyl Cp, the thermal stability of the zirconium source precursor can still not match the optimal growth temperature of CpHf(NMe2)3, which is about 300°C.

[0135] From the above comparative data of Examples 1-4 and Comparative Examples 1-3, if the thermal stability of the zirconium source is not enough, the zirconium source precursor will decompose during the deposition process, and thus the leakage current of the ferroelectric thin film will be greatly increased, and the uniformity and conformality of the ferroelectric thin film will also be greatly reduced, ultimately affecting the performance of the device. Using the compound of the present application as a zirconium source precursor to grow a high dielectric constant ferroelectric thin film material provides the possibility for preparing a higher performance memory device. The ferroelectric thin film grown using the compound of the present application as a precursor not only has very low impurity pollution, facilitating the formation of a ferroelectric phase, but also greatly improves the leakage current, which provides a material-based guarantee for the performance indicators such as the remanent polarization, leakage current, and ferroelectric switching speed of the new generation of ferroelectric memory devices.

[0136] In summary, the compound of the present application as a precursor for a ferroelectric thin film can achieve deposition of high-temperature hafnium source precursors and zirconium source precursors, so that the hafnium source precursor and the zirconium source precursor both have high deposition rates and reactivity, saving deposition time and improving film formation efficiency. At the same time, the Hf 0.5 Zr 0.5The prepared ferroelectric thin film has the advantages of low impurity content, low leakage current, and multiple ferroelectric phases, and meets the requirements of a new generation of ferroelectric memory for excellent ferroelectric thin film performance. In addition, when the compound of the present application is used as a precursor for atomic layer deposition, it is compatible with the CMOS deposition process, providing an effective new way to manufacture high-efficiency, low-cost, high-density ferroelectric memory devices.

[0137] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can easily think of changes or replacements within the technical scope disclosed in the present application, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A compound, characterized in that having a structure as shown in formula (1): wherein M is a group IV transition metal; R1, R2, R3, R4, R5, R6 are each independently selected from at least one of C1-C3 alkyl groups; Cp is cyclopentadienyl, and Z is N or Cp; Z is N, and a is 2; Z is Cp, and a is 1-5; b is 1-5.

2. The compound of claim 1, wherein The C1-C3 alkyl group can be selected from at least one of methyl, ethyl, and isopropyl.

3. The compound of claim 1 or 2, wherein The number of substituted hydrogens in the cyclopentadienyl group is 1-5.

4. The compound according to any one of claims 1 to 3, characterized in that, The substituents in the cyclopentadienyl group are all methyl groups.

5. The compound of any one of claims 1-4, wherein R4, R5, and R6 are all methyl groups.

6. The compound of any one of claims 1-5, wherein, Z is N, and R2 is a methyl or ethyl group.

7. The compound of any one of claims 1-6, wherein, R1 is a methyl or ethyl group.

8. A process for the preparation of a compound according to any one of claims 1 to 7, characterized in that, comprises: the compound obtained after substituting m -NAr2 groups in the compound M(NAr2)4, wherein one -NAr2 group in the compound M(NAr2)4 is substituted by an amidine group, and the remaining -NAr2 groups in the m -NAr2 groups are substituted by cyclopentadienyl groups with substituents, wherein Ar is selected from C1-C3 alkyl groups, and m is 2 or 3.

9. A method of producing a ferroelectric thin film, characterized by, comprises: depositing at least a plurality of layers of a precursor layer comprising the compound as claimed in any one of claims 1-7 on a substrate surface, and forming the ferroelectric thin film after oxidizing or nitriding the precursor layer.

10. The method of claim 9, wherein, The preparation method comprises: depositing a hafnium source precursor on the substrate surface, and oxidizing the hafnium source precursor to form a hafnium oxide layer; depositing a zirconium source precursor on the surface of the hafnium oxide layer, and oxidizing the zirconium source precursor to form the zirconium oxide layer; the zirconium source precursor is a zirconium source compound having a structure as shown in formula (1), wherein M is Zr in the structure as shown in formula (1); repeating the above process to form alternating hafnium oxide layers and zirconium oxide layers, and obtaining the ferroelectric thin film.

11. The preparation method according to claim 9, characterized in that The preparation method comprises: depositing a zirconium source compound having a structure as shown in formula (1) on the surface of a substrate, and forming a zirconium oxide thin film or a zirconium nitride thin film after oxidizing or nitriding; repeating the above process to form a ferroelectric thin film, wherein the ferroelectric thin film has a plurality of layers of zirconium oxide thin films or zirconium nitride thin films arranged in a stack.

12. The method of any one of claims 9-11, wherein, The deposition temperature of the compound as shown in formula (1) is 330-380°C.

13. A ferroelectric thin film, characterized by, The ferroelectric thin film is prepared using the preparation method as claimed in any one of claims 9-11.

14. A memory, comprising: The ferroelectric thin film as claimed in claim 13, wherein two surfaces of the ferroelectric thin film are respectively provided with electrodes.

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