Hafnium-based ferroelectric laminated structure with high response speed and preparation method thereof
Through hafnium-based ferroelectric stacked structure and PEALD technology, the proportion of Hf and Zr elements is adjusted and combined into a stacked structure, which solves the problems of response speed and polarization strength of ferroelectric devices, and achieves rapid response and low power consumption performance optimization .
Patent Information
- Application Number
- CN202411340099.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-25
- Publication Date
- 2024-12-27
AI Technical Summary
Ferroelectric devices have low response speeds at the same operating voltage and cannot provide greater polarization strength at lower voltages, limiting their performance in ultra-high speed and low power consumption.
Using a hafnium-based ferroelectric stack structure, by forming a spaced bottom electrode on the substrate, a multi-layer hafnium-based ferroelectric film serves as a ferroelectric functional stack, and vertically arranged top electrodes are formed thereon, and plasma reinforcement is used. Atomic layer deposition (PEALD) technology accurately adjusts the proportion of Hf and Zr elements, combines them into a stacked structure, reduces the flipped electric field, and passes rapid thermal annealing.
It achieves rapid response speed and obtains greater polarization strength under low electric fields, optimizes the performance of ferroelectric films, ensures the purity of the material and the stability of electrical characteristics, and avoids pollution and leakage problems.
Smart Images
Figure CN119212549A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of ferroelectric memory manufacturing process, and in particular to a hafnium-based ferroelectric stacked structure with fast response speed and a preparation method thereof. Background Art
[0002] As a material compatible with CMOS processes, ferroelectric devices based on hafnium oxide (HfO2) exhibit excellent scaling capabilities and are highly compatible with existing very large scale integration (VLSI) technologies. These features have promoted ferroelectric (FE) devices as potential candidates for future electronic products. Researchers have successfully demonstrated a variety of ferroelectric (FE) devices based on hafnium-zirconium-oxide (HZO), including ferroelectric capacitors, ferroelectric field effect transistors (FEFETs), and ferroelectric tunnel junctions (FTJs). These devices are seen as promising candidates for various emerging and high-demand applications such as non-volatile memory, electronic synapses, and neurons.
[0003] Ferroelectric random access memory and ferroelectric tunnel junction devices are typical metal-insulator-metal (MIM) capacitor structures. However, due to the high switching electric field of the device, the device response speed is reduced at the same operating voltage, and a large polarization intensity value cannot be provided at a lower voltage, which limits the performance of the device in achieving ultra-high speed and low power consumption. Summary of the invention
[0004] The invention discloses a hafnium-based ferroelectric stacked structure with fast response speed, comprising: a substrate; a bottom electrode formed on the substrate and arranged at intervals along a first direction; a ferroelectric functional stack formed on the bottom electrode and composed of a plurality of hafnium-based ferroelectric films with different doping ratios; and a top electrode formed on the ferroelectric functional stack and arranged at intervals along a second direction, perpendicular to the first direction.
[0005] In the hafnium-based ferroelectric laminated structure with fast response speed of the present invention, preferably, the doping element of the hafnium-based ferroelectric film is Zr, Al, La, Y or Si.
[0006] In the hafnium-based ferroelectric laminated structure with fast response speed of the present invention, preferably, the doping ratio of Zr:Hf in each layer of hafnium-based ferroelectric thin film is in the range of 1:1 to 2:8.
[0007] In the hafnium-based ferroelectric laminated structure with fast response speed of the present invention, preferably, the total thickness of each layer of the hafnium-based ferroelectric thin film is less than 15 nm.
[0008] The present invention also discloses a method for preparing a hafnium-based ferroelectric stacked structure with a fast response speed, comprising the following steps: forming a bottom electrode arranged at intervals along a first direction on a substrate; forming a multilayer hafnium-based ferroelectric film with different doping ratios and thicknesses as a ferroelectric functional stack on the bottom electrode; forming a top electrode arranged at intervals along a second direction on the ferroelectric functional stack, which is perpendicular to the first direction; and performing rapid thermal annealing.
[0009] In the method for preparing the hafnium-based ferroelectric laminated structure with fast response speed of the present invention, preferably, the doping element of the hafnium-based ferroelectric film is Zr, Al, La, Y or Si.
[0010] In the method for preparing the hafnium-based ferroelectric laminated structure with fast response speed of the present invention, preferably, the doping ratio of Zr:Hf in each layer of the hafnium-based ferroelectric thin film is in the range of 1:1 to 2:8.
[0011] In the method for preparing the hafnium-based ferroelectric laminated structure with fast response speed of the present invention, preferably, the total thickness of each layer of the hafnium-based ferroelectric thin film is less than 15 nm.
[0012] Beneficial effects:
[0013] Plasma enhanced atomic layer deposition (PEALD) is used to prepare mixed oxide (HfxZr1-XO) ferroelectric films of Hf and Zr in different proportions by precisely adjusting the growth ratio of Hf and Zr elements, and they are combined into a stacked structure to reduce the switching electric field without introducing other elements for doping, thus avoiding pollution and leakage problems.
[0014] By adjusting the number of film cycles and element ratios during the growth process, the thickness of the stack and the ratio of film elements at different levels in the stack can be easily controlled, thereby exploring the effects of different structures on improving the speed of Hf-based ferroelectric films and obtaining greater polarization strength under low electric fields. This precise control method provides an effective way to optimize the performance of ferroelectric films while ensuring the purity of the material and the stability of its electrical properties. BRIEF DESCRIPTION OF THE DRAWINGS
[0015] Figure 1 The present invention is a flow chart of a method for preparing a hafnium-based ferroelectric laminated structure with a fast response speed.
[0016] Figure 2 to Figure 4 It is a schematic diagram of the structure of each stage in the preparation process of HZO ferroelectric stacked structure.
[0017] Figure 5 and Figure 6 It is a comparison chart of the performance test results of the three-layer HZO stacked structure of the present invention and the traditional HZO ferroelectric device. DETAILED DESCRIPTION
[0018] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. The described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.
[0019] In the description of the present invention, it should be noted that the terms "upper", "lower", "vertical", "horizontal", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.
[0020] In addition, many specific details of the present invention are described below, such as the structure, materials, dimensions, processing technology and techniques of the device, so that the present invention can be more clearly understood. However, as can be understood by those skilled in the art, the present invention can be implemented without following these specific details. Unless otherwise specified below, the various parts of the device can be made of materials known to those skilled in the art, or can be made of materials with similar functions developed in the future.
[0021] Figure 1 The flowchart of the method for preparing a hafnium-based ferroelectric laminated structure with a fast response speed is shown below. The preparation of the HZO ferroelectric laminated structure is used as an example for explanation.
[0022] like Figure 1 As shown, the method for preparing a hafnium-based ferroelectric laminated structure with a fast response speed comprises the following steps:
[0023] Step S1, provide a Si substrate 100, clean it by conventional RCA process, define the shape of the bottom electrode by photolithography, grow 80nm thick W by PVD process, and perform lift-off process to form the bottom electrodes 101 arranged at intervals. The obtained structure is as follows: Figure 2 shown.
[0024] Step S2, forming a HZO ferroelectric functional layer by atomic layer deposition. By alternately exposing different precursors to the substrate surface to adjust the cycle ratio of Hf and Zr, performing a specific number of ALD cycles, and growing multiple layers of HZO ferroelectric thin film stacks 102 with different ratios and thicknesses, the resulting structure is as shown in FIG. Figure 3As shown. According to specific needs, different doping ratios and ferroelectric layer thicknesses need to be adjusted. Generally, ferroelectric films with higher Zr content produce smaller switching electric fields, but have poorer ferroelectric properties; conversely, layers with lower Zr content weaken the degree of reduction in the switching electric field, but relatively improve the ferroelectric properties. Preferably, different layers have different Hf and Zr doping ratios ranging from 1:1 to 2:8, and the total thickness is kept below 15nm, thereby improving the ferroelectric properties while reducing the switching electric field. In this embodiment, a three-layer HZO stacked structure is adopted, and the Zr:Hf ratios of each layer from bottom to top are 7:3; 1:1; 7:3, respectively, and the thickness of each layer is 4nm. This design exhibits good ferroelectric properties and successfully reduces the impact of the switching electric field.
[0025] In addition, in the present invention, under the premise of maintaining the total thickness of 12nm, comparative experiments were carried out on the stacked structures with HZO layer thicknesses of 3nm / 6nm / 3nm and 5nm / 2nm / 5nm. The experimental results show that for the ferroelectric layer with a higher Zr content, as its thickness ratio increases, the reversal electric field also decreases accordingly. Therefore, this structure can show a higher polarization intensity when working at a lower voltage. For HZO film with uniform thickness, for ferroelectric devices of the same thickness, the larger its thickness ratio is, the larger the reversal electric field is, but its polarization intensity performance is better at a higher voltage. According to specific application requirements, the working performance of the device can be optimized by adjusting the thickness ratio of the ferroelectric layer.
[0026] Step S3, the shape of the top electrode is then defined by photolithography, W with a thickness of 90 nm is grown by PVD process, and the stripping process is performed again to form the top electrodes 103 arranged at intervals. The obtained structure is as follows: Figure 4 As shown in FIG. 1 , the top electrode and the bottom electrode are arranged vertically and crosswise.
[0027] Step S4, performing rapid thermal annealing at 500° C. for 30 seconds to obtain a hafnium-based ferroelectric stacked structure having ferroelectricity.
[0028] Figure 5 and Figure 6 The performance test results of the three-layer HZO stacked structure (Zr:Hf ratios of 7:3, 1:1, and 7:3, respectively) and the MIM device of the conventional HZO are shown in FIG. It can be seen that the HZO stacked structure of the present invention has a lower switching electric field, a greater polarization intensity at low voltage, and a faster speed.
[0029] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.
Claims
1. A hafnium-based ferroelectric laminated structure with fast response speed, characterized in that: include: substrate; Bottom electrodes are formed on the substrate and arranged at intervals along a first direction; A ferroelectric functional stack, formed on the bottom electrode, is composed of multiple hafnium-based ferroelectric thin films with different doping ratios; The top electrodes are formed on the ferroelectric functional stack and are arranged at intervals along the second direction, which is perpendicular to the first direction.
2. The hafnium-based ferroelectric laminated structure with fast response speed according to claim 1, characterized in that: The doping element of the hafnium-based ferroelectric film is Zr, Al, La, Y or Si.
3. The hafnium-based ferroelectric laminated structure with fast response speed according to claim 1, characterized in that: The doping ratio of Zr:Hf in each layer of hafnium-based ferroelectric thin film ranges from 1:1 to 2:
8.
4. The hafnium-based ferroelectric laminated structure with fast response speed according to claim 1, characterized in that: The total thickness of each layer of the hafnium-based ferroelectric thin film is less than 15 nm.
5. A method for preparing a hafnium-based ferroelectric laminated structure with a fast response speed, characterized in that: The following steps are involved: forming bottom electrodes arranged at intervals along a first direction on a substrate; forming a multilayer hafnium-based ferroelectric thin film with different doping ratios on the bottom electrode as a ferroelectric functional stack; forming top electrodes arranged at intervals along a second direction on the ferroelectric functional stack, perpendicular to the first direction; Perform rapid thermal annealing.
6. The method for preparing a hafnium-based ferroelectric laminated structure with a fast response speed according to claim 5, characterized in that: The doping element of the hafnium-based ferroelectric film is Zr, Al, La, Y or Si.
7. The method for preparing a hafnium-based ferroelectric laminated structure with a fast response speed according to claim 5, characterized in that: The doping ratio of Zr:Hf in each layer of hafnium-based ferroelectric thin film ranges from 1:1 to 2:
8.
8. The method for preparing a hafnium-based ferroelectric laminated structure with a fast response speed according to claim 5, characterized in that: The total thickness of each layer of the hafnium-based ferroelectric thin film is less than 15 nm.