Ferroelectric film preparation method and ferroelectric capacitor
By magnetron sputtering, a ferroelectric film layer with covalent bonds of Hf and Y2O3 on the substrate, and ferroelectricity is induced by annealing, the problem of difficulty in preparing a Y-doped ferroelectric film with R3 phase is solved, and the efficient preparation of a ferroelectric capacitor is achieved.
Patent Information
- Application Number
- CN202411622807.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-14
- Publication Date
- 2025-02-25
AI Technical Summary
It is difficult to prepare Y-doped ferroelectric films with R3 phase.
The ferroelectric film layer is formed on the first electrode layer by magnetron sputtering using the Hf target and the Y2O3 target. The ferroelectric film layer includes a compound and a free Hf atom. The compound is formed based on a covalent bond between Hf and Y2O3 and annealed under an inert atmosphere to induce ferroelectricity.
The target ferroelectric film layer with R3 phase and doped with Y was successfully formed, achieving efficient preparation of ferroelectric capacitors.
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Figure CN119506802A_ABST
Abstract
Description
Technical Field
[0001] The present disclosure relates to the field of semiconductor technology, and in particular, to a method for preparing a ferroelectric thin film and a ferroelectric capacitor. Background Art
[0002] Hafnium oxide-based ferroelectric materials are good candidates for making non-volatile memory, with excellent ductility and CMOS (Complementary Metal Oxide Semiconductor) compatibility. In the process of producing ferroelectric capacitors containing ferroelectric films, the method of preparing ferroelectric films is mainly atomic layer deposition (ALD, Atomic Layer Deposition) method. For example, there are many elements that can be doped into HfO by atomic layer deposition method. 2 and form ferroelectricity, such as zirconium (Zr), yttrium (Y), silicon (Si), aluminum (Al), lanthanum (La), etc.
[0003] In the process of realizing the inventive concept of the present disclosure, the inventors found that the method for preparing ferroelectric thin films in the related art is difficult to prepare Y-doped ferroelectric thin films having an R3 phase. Summary of the invention
[0004] In view of this, the present disclosure provides a method for preparing a ferroelectric thin film and a ferroelectric capacitor.
[0005] One aspect of the present disclosure provides a method for preparing a ferroelectric thin film, comprising: forming a first electrode layer on a substrate; using a Hf target and a Y 2 O 3 The target material is formed on the first electrode layer by magnetron sputtering, wherein the ferroelectric thin film layer includes a compound and free Hf atoms, and the compound is based on Hf and Y 2 O 3 forming a covalent bond between the ferroelectric film layer; forming a second electrode layer on the ferroelectric film layer; and annealing the ferroelectric film layer to induce ferroelectricity of the ferroelectric film layer to form a target ferroelectric film having an R3 phase.
[0006] According to an embodiment of the present disclosure, Hf target and Y 2 O 3 The target material is used to form a ferroelectric thin film layer on the first electrode layer by magnetron sputtering, comprising: using the Hf target material and the Y 2 O 3 The target material is formed on the first electrode layer by magnetron sputtering, wherein the first mixed gas includes Ar and O 2 .
[0007] According to an embodiment of the present disclosure, the flow rate of Ar in the first mixed gas is in the range of 35 to 45 sccm; and the flow rate of O in the first mixed gas is in the range of 35 to 45 sccm. 2 The flow rate range is 0.5~0.7 sccm.
[0008] According to an embodiment of the present disclosure, the purity of the Hf target is greater than 99%; and 2 O 3 The purity of the target material is greater than 99%.
[0009] According to an embodiment of the present disclosure, the sputtering power of the Hf target is in the range of 20 to 30 W; and 2 O 3 The sputtering power ranges from 40 to 60 W.
[0010] According to an embodiment of the present disclosure, forming a first electrode layer on a substrate includes: forming the first electrode layer on the substrate by a sputtering process while introducing a second mixed gas; wherein the parameters of the sputtering process include a beam voltage, a beam current, and an acceleration voltage, wherein the beam voltage ranges from 700 to 900 V, the beam current ranges from 40 to 60 mA, and the acceleration voltage ranges from 150 to 170 V; the second mixed gas includes Ar and N 2 The flow rate of Ar in the second mixed gas is in the range of 7 to 9 sccm, and the flow rate of N in the second mixed gas is in the range of 1. 2 The flow rate range is 4~6 sccm.
[0011] According to an embodiment of the present disclosure, a second electrode layer is formed on a ferroelectric thin film layer, including: coating a photoresist on the ferroelectric thin film layer according to a predetermined pattern; baking the photoresist; developing the baked photoresist to form a photoresist film; sputtering an electrode material in an area not covered by the photoresist film; removing the photoresist film and using the electrode material remaining in the area as a second electrode layer.
[0012] According to an embodiment of the present disclosure, annealing the ferroelectric thin film layer includes: annealing in an inert gas atmosphere, the annealing temperature range is 400° C. to 550° C., and the annealing time is 25 to 35 s.
[0013] According to an embodiment of the present disclosure, the thickness of the first electrode layer is greater than or equal to 10 nm; the thickness of the second electrode layer is greater than or equal to 10 nm; and the thickness of the ferroelectric thin film layer is greater than or equal to 10 nm.
[0014] Another aspect of the present disclosure provides a ferroelectric capacitor, wherein a target ferroelectric thin film layer in the ferroelectric capacitor is manufactured by any of the above-mentioned manufacturing methods.
[0015] According to an embodiment of the present disclosure, by using Hf and Y 2 O3 Magnetron sputtering can be used to make Y 2 O 3 It forms a covalent bond with Hf to form HYO, and obtains a ferroelectric thin film layer doped with Y, and makes the Hf that has not formed a covalent bond exist in the ferroelectric thin film layer in a free state, thereby forming a target ferroelectric thin film layer having a crystal structure phase of R3 phase and doped with Y after annealing. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] The above and other objects, features and advantages of the present disclosure will become more apparent through the following description of the embodiments of the present disclosure with reference to the accompanying drawings, in which:
[0017] Figure 1 A flow chart schematically shows a method for preparing a ferroelectric thin film according to an embodiment of the present disclosure;
[0018] Figure 2 A schematic diagram of a substrate according to an embodiment of the present disclosure is schematically shown;
[0019] Figure 3 Schematically shows a schematic diagram of forming a first electrode layer according to an embodiment of the present disclosure;
[0020] Figure 4 Schematically shows a schematic diagram of forming a ferroelectric thin film layer according to an embodiment of the present disclosure;
[0021] Figure 5 Schematically shows a schematic diagram of forming a second electrode layer according to an embodiment of the present disclosure;
[0022] Figure 6 Schematic diagram of HfO in the ferroelectric thin film layer according to an embodiment of the present disclosure 2 Schematic diagram representing the intensity;
[0023] Fig. 7A and Figure 7B A schematic diagram schematically shows an R3 phase in a target ferroelectric thin film layer according to an embodiment of the present disclosure;
[0024] Figure 8 A schematic diagram schematically shows a hysteresis curve of a ferroelectric capacitor according to an embodiment of the present disclosure. DETAILED DESCRIPTION
[0025] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the present disclosure. In the following detailed description, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of the embodiments of the present disclosure. However, it is apparent that one or more embodiments may also be implemented without these specific details. In addition, in the following description, descriptions of known structures and technologies are omitted to avoid unnecessary confusion of the concepts of the present disclosure.
[0026] The terms used herein are only for describing specific embodiments and are not intended to limit the present disclosure. The terms "comprise", "include", etc. used herein indicate the existence of the features, steps, operations and / or components, but do not exclude the existence or addition of one or more other features, steps, operations or components.
[0027] All terms (including technical and scientific terms) used herein have the meanings commonly understood by those skilled in the art unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.
[0028] When using expressions such as "at least one of A, B, and C, etc.", they should generally be interpreted according to the meaning of the expression commonly understood by those skilled in the art (for example, "a system having at least one of A, B, and C" should include but is not limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc.).
[0029] Magnetron sputtering has many advantages such as non-equilibrium process, cost-effectiveness, no carbon contamination from precursor residues, and room temperature deposition.
[0030] On this basis, the present disclosure provides a method for preparing a ferroelectric thin film, which can form a Y-doped ferroelectric thin film having an R3 phase by magnetron sputtering. Specifically, the method for preparing the ferroelectric thin film includes: forming a first electrode layer on a substrate. Using a Hf target and Y 2 O 3 The target material is formed on the first electrode layer by magnetron sputtering, wherein the ferroelectric thin film layer includes a compound and free Hf atoms, and the compound is based on Hf and Y 2 O 3 The second electrode layer is formed on the ferroelectric thin film layer. The ferroelectric thin film layer is annealed to induce ferroelectricity of the ferroelectric thin film layer to form a target ferroelectric thin film having an R3 phase.
[0031] The method for manufacturing a sidewall spacer according to an embodiment of the present disclosure will be described in more detail below in conjunction with the embodiments.
[0032] Figure 1 The flowchart of the method for preparing the ferroelectric thin film according to the embodiment of the present disclosure is schematically shown. Figures 2 to 5 The structure of some stages in the method is schematically shown.
[0033] like Figure 1 As shown, a first electrode layer 102 is formed on a substrate 101 in operation S110 .
[0034] refer to Figure 2 , a substrate 101 may be provided. The material of the substrate 101 may include materials such as silicon and / or silicon oxide. For example, the substrate 101 may be a substrate 101 made of silicon or silicon oxide alone, or may be a multilayer substrate 101 composed of alternately stacked silicon and silicon oxide, which is not limited here.
[0035] In the case of using silicon to make the substrate 101, the thickness of silicon in the substrate 101 may range from 450 to 550 um, specifically 475 um, 500 um, 525 um, etc.; in the case of using a multilayer substrate 101 composed of silicon and silicon oxide stacked alternately, the thickness of silicon in the substrate 101 may range from 450 to 550 um, specifically 450, 475 um, 500 um, 525 um, 550 um, etc. The thickness of silicon oxide may range from 250 to 350 nm, specifically 250 nm, 275 nm, 300 nm, 325 nm, 350 nm, etc.
[0036] refer to Figure 3 , when the second mixed gas is introduced, a first electrode layer 102 can be formed on the substrate 101 by a sputtering process. For example, the sputtering process in the embodiment of the present disclosure may include ion beam sputtering, DC sputtering or reactive sputtering, etc., which are not limited here. The target material used to make the first electrode layer 102 may be TiN. The parameters of the sputtering process include beam voltage, beam current and acceleration voltage, etc. For example, the range of beam voltage is 700~900 V (volts, voltage unit), specifically 700 V, 750 V, 800 V, 850 V, 900 V. The range of beam current is 40~60 mA (milliamperes, current unit), specifically 40 mA, 45 mA, 50 mA, 55 mA, 60 mA. The range of acceleration voltage is 150~170 V, specifically 150 V, 155 V, 160 V, 165 V, 170 V. The second mixed gas includes Ar and N 2 The flow rate of Ar in the second mixed gas is in the range of 7 to 9 sccm, specifically 7.5 sccm, 8 sccm, 8.5 sccm, and 9 sccm.2 The flow rate range is 4-6 sccm, specifically 4.5 sccm, 5 sccm, 5.5 sccm, 6 sccm. The material of the first electrode may include but is not limited to TiN, W, TaN, Si, Ir, Ru, RuO 2 At least one of Pt and Pd. The thickness of the first electrode layer is greater than or equal to 10 nm.
[0037] The method may further include using the Hf target and the Y 2 O 3 The target material is used to form a ferroelectric thin film layer 103 on the first electrode layer 102 by magnetron sputtering.
[0038] refer to Figure 4 , by combining Hf target and Y 2 O 3 The target material is installed on the magnetron sputtering coating equipment, and then magnetron sputtering is carried out under the excitation of AC power supply, so that Hf atoms and Y 2 O 3 The ferroelectric thin film 103 formed on the substrate 101 includes a compound and free Hf atoms. The compound is based on Hf and Y 2 O 3 For example, the purity of the Hf target is greater than 99%. 2 O 3 The purity of the target material is greater than 99%. The sputtering power of the Hf target material ranges from 20 to 30 W, specifically 20 W, 22 W, 24 W, 26 W, 28 W, and 30 W. 2 O 3 The sputtering power of Hf is in the range of 40-60 W, and can be specifically 40 W, 45 W, 50 W, 55 W, and 60 W. The thickness of the ferroelectric thin film layer 103 is greater than or equal to 10 nm. Preferably, the sputtering power of Hf is 24 W, and the sputtering power of Y 2 O 3 The sputtering power is 50W.
[0039] Specifically, when the first mixed gas is introduced, the Hf target and Y 2 O 3 The target material is used to form a ferroelectric thin film layer 103 on the first electrode layer 102 by magnetron sputtering. For example, the first mixed gas includes Ar and O 2 The flow rate of Ar in the first mixed gas is in the range of 35 to 45 sccm, and specifically can be 35 sccm, 37 sccm, 39 sccm, 41 sccm, 43 sccm, and 45 sccm.2 The flow rate range is 0.5-0.7 sccm, specifically 0.55 sccm, 0.6 sccm, 0.65 sccm, 0.7 sccm. Preferably, the amount of Ar introduced is 40 sccm, and the amount of O introduced is 40 sccm. 2 The amount of ferroelectric thin film layer 103 is 0.6 sccm. The thickness of ferroelectric thin film layer 103 is 10 nm.
[0040] By controlling the O 2 By adjusting the flow rate of Hf, the oxidation state of Hf can be controlled, thereby adjusting the relative content of the above compounds and free Hf atoms in the ferroelectric thin film layer 103. Based on this, the content of R3 phase and Y in the target ferroelectric thin film layer can be flexibly adjusted.
[0041] The method may further include forming a second electrode layer 104 on the ferroelectric thin film layer 103 in operation S130 .
[0042] refer to Figure 5 , a photoresist, such as a negative resist, can be coated on the ferroelectric thin film layer 103 according to a predetermined pattern. Then, the photoresist is baked, such as baking at 150°C for 2 minutes, and baking at 120°C for 2 minutes after exposure. The baked photoresist is developed, such as soaking in a developer for 45 seconds to develop, thereby forming a photoresist film, and then rinsed and dried with deionized water to remove the developer on the device surface.
[0043] The electrode material can be sputtered in the area not covered by the photoresist film. For example, in the case of introducing the second mixed gas, the second electrode layer 104 is formed on the ferroelectric thin film layer 103 by using the sputtering process. For example, the target material used to make the second electrode layer 104 can be TiN. The parameters of the sputtering process include beam voltage, beam current and acceleration voltage, etc. For example, the range of the beam voltage is 700~900 V, and can be specifically 700 V, 750 V, 800 V, 850 V, 900 V. The range of the beam current is 40~60mA, and can be specifically 40 mA, 45 mA, 50 mA, 55 mA, 60 mA. The range of the acceleration voltage is 150~170 V, and can be specifically 150 V, 155V, 160 V, 165 V, 170 V. The flow rate of Ar in the second mixed gas ranges from 7~9 sccm, and can be specifically 7.5 sccm, 8 sccm, 8.5 sccm, 9 sccm. The flow rate of N2 in the second mixed gas ranges from 4 to 6 sccm, specifically 4.5 sccm, 5 sccm, 5.5 sccm, and 6 sccm. The thickness of the second electrode layer 104 is greater than or equal to 10 nm.
[0044] Then, the photoresist film is removed, and the electrode material remaining in the region is used as the second electrode layer 104. For example, the ferroelectric capacitor having the substrate 101, the first electrode layer 102, the ferroelectric film layer 103, and the second electrode layer 104 can be immersed in an acetone solution until the photoresist film and excess metal fall off; then immersed in anhydrous ethanol to remove the acetone; and then rinsed with deionized water and blown dry.
[0045] The method may further include annealing the ferroelectric thin film layer 103 to induce ferroelectricity of the ferroelectric thin film layer 103 to form a target ferroelectric thin film having an R3 phase in operation S140.
[0046] Annealing can be performed in an inert gas atmosphere, with the annealing temperature ranging from 400°C to 550°C and the annealing time being 25 to 35 seconds. For example, the rinsed and dried ferroelectric capacitor is annealed in a nitrogen N2 atmosphere at 500°C for 30 seconds to induce the ferroelectricity of the ferroelectric thin film layer 103, thereby obtaining a ferroelectric capacitor with ferroelectric properties. Figure 6 It can be seen that hafnium oxide exists in the ferroelectric thin film layer of the present disclosure. Figure 6 Intensity in represents intensity. Fig. 7A and Figure 7B It can be seen that a large amount of R3 phase exists in the obtained target ferroelectric thin film.
[0047] Another aspect of the present disclosure provides a ferroelectric capacitor, wherein the target ferroelectric thin film layer in the ferroelectric capacitor is prepared by any of the preparation methods described above. Figure 8 shown.
[0048] According to an embodiment of the present disclosure, by using Hf and Y 2 O 3 Magnetron sputtering can be used to make Y 2 O 3 A covalent bond is formed with Hf to form HYO, thereby obtaining a ferroelectric thin film layer 103 doped with Y, and the Hf that has not formed a covalent bond exists in the ferroelectric thin film layer 103 in a free state, thereby forming a target ferroelectric thin film layer having a crystal structure phase of R3 phase and doped with Y after annealing.
[0049] It will be appreciated by those skilled in the art that the features described in the various embodiments of the present disclosure may be combined and / or combined in a variety of ways, even if such combinations or combinations are not explicitly described in the present disclosure. In particular, without departing from the spirit and teachings of the present disclosure, the features described in the various embodiments of the present disclosure may be combined and / or combined in a variety of ways. All of these combinations and / or combinations fall within the scope of the present disclosure.
[0050] The embodiments of the present disclosure are described above. However, these embodiments are only for illustrative purposes and are not intended to limit the scope of the present disclosure. Although the embodiments are described above, this does not mean that the measures in the various embodiments cannot be used in combination to advantage. Without departing from the scope of the present disclosure, those skilled in the art may make a variety of substitutions and modifications, which should all fall within the scope of the present disclosure.
Claims
1. A method for preparing a ferroelectric thin film, comprising: forming a first electrode layer on a substrate; Using Hf target and Y2O3 target, forming a ferroelectric thin film layer on the first electrode layer by magnetron sputtering, wherein the ferroelectric thin film layer includes a compound and free Hf atoms, and the compound is formed based on the covalent bond between Hf and Y2O3; forming the second electrode layer on the ferroelectric thin film layer; as well as The ferroelectric thin film layer is annealed to induce ferroelectricity of the ferroelectric thin film layer to form a target ferroelectric thin film having an R3 phase.
2. The method according to claim 1, wherein: The method of forming a ferroelectric thin film layer on the first electrode layer by magnetron sputtering using a Hf target material and a Y2O3 target material comprises: The ferroelectric thin film layer is formed on the first electrode layer by magnetron sputtering using a Hf target and a Y2O3 target while introducing a first mixed gas, wherein the first mixed gas includes Ar and O2.
3. The method according to claim 2, wherein: The flow rate of Ar in the first mixed gas is in the range of 35-45 sccm; and The flow rate of O2 in the first mixed gas is in the range of 0.5-0.7 sccm.
4. The method according to any one of claims 1 to 3, wherein The purity of the Hf target is greater than 99%; and The purity of the Y2O3 target material is greater than 99%.
5. The method according to any one of claims 1 to 3, wherein The sputtering power of the Hf target is in the range of 20-30 W; and The sputtering power of Y2O3 is in the range of 40~60W.
6. The method according to any one of claims 1 to 3, wherein The step of forming a first electrode layer on a substrate comprises: Under the condition of introducing the second mixed gas, forming the first electrode layer on the substrate by using a sputtering process; The parameters of the sputtering process include beam voltage, beam current and acceleration voltage. The range of the beam voltage is 700-900 V, the range of the beam current is 40-60 mA, and the range of the acceleration voltage is 150-170 V. The second mixed gas includes Ar and N2, the flow rate of Ar in the second mixed gas ranges from 7 to 9 sccm, and the flow rate of N2 in the second mixed gas ranges from 4 to 6 sccm.
7. The method according to any one of claims 1 to 3, wherein The forming of the second electrode layer on the ferroelectric thin film layer comprises: coating a photoresist on the ferroelectric thin film layer according to a predetermined pattern; Baking the photoresist; Developing the baked photoresist to form a photoresist film; sputtering electrode material in the area not covered by the photoresist film; The photoresist film is removed, and the electrode material remaining in the region is used as the second electrode layer.
8. The method according to any one of claims 1 to 3, wherein The annealing of the ferroelectric thin film layer comprises: Annealing is performed in an inert gas atmosphere, the annealing temperature range is 400° C. to 550° C., and the annealing time is 25 to 35 s.
9. The method according to any one of claims 1 to 3, wherein The thickness of the first electrode layer is greater than or equal to 10 nm; The thickness of the second electrode layer is greater than or equal to 10 nm; and The thickness of the ferroelectric thin film layer is greater than or equal to 10 nm.
10. A ferroelectric capacitor, wherein the target ferroelectric thin film layer in the ferroelectric capacitor is prepared by the preparation method according to any one of claims 1 to 9.