阅读说明：本技术 铁电薄膜的制备方法、铁电存储器及其制备方法 (Preparation method of ferroelectric film, ferroelectric memory and preparation method thereof ) 是由 廖敏 郇延伟 戴思维 刘兆通 曾斌建 周益春 于 2020-05-13 设计创作，主要内容包括：本申请实施例提供一种铁电薄膜的制备方法、铁电存储器及其制备方法。其中铁电薄膜的制备方法包括：以主元素源作为反应前驱体进行原子层沉积,将主元素沉积到衬底表面,通过控制沉积时间,以吸附衬底表面大部分自由键合点；继而使用惰性气体作为净化气体进行清除吹扫腔室；然后以掺杂元素源作为反应前驱体进行原子层沉积,使掺杂元素吸附衬底表面剩余的自由键合点；使用惰性气体作为净化气体进行清除吹扫；此时两种前驱体同时存在于衬底表面,然后使用氧化性气体一同进行氧化处理；继而使用惰性气体作为净化气体进行清除吹扫；重复以上步骤,得到目标厚度的铁电薄膜。本申请实施例的方法能够实现较好的低浓度均匀性掺杂。(The embodiment of the application provides a preparation method of a ferroelectric film, a ferroelectric memory and a preparation method thereof. The preparation method of the ferroelectric film comprises the following steps: carrying out atomic layer deposition by taking a main element source as a reaction precursor, depositing the main element on the surface of the substrate, and adsorbing most of free bonding points on the surface of the substrate by controlling the deposition time; then using inert gas as purge gas to clean and purge the chamber; then, taking a doping element source as a reaction precursor to carry out atomic layer deposition, so that the doping element adsorbs the residual free bonding points on the surface of the substrate; purge purging using an inert gas as a purge gas; at the moment, the two precursors exist on the surface of the substrate at the same time, and then oxidation treatment is carried out by using oxidizing gas; then using inert gas as purge gas to perform scavenging purging; repeating the steps to obtain the ferroelectric film with the target thickness. The method of the embodiment of the application can realize better low-concentration uniformity doping.)

1. A method for preparing a ferroelectric thin film, comprising:

carrying out atomic layer deposition by taking a main element source as a reaction precursor, and depositing the main element on the surface of the substrate to adsorb most of free bonding points;

using inert gas as purge gas to perform purge purging;

carrying out atomic layer deposition by taking a doping element source as a reaction precursor, so that the doping element adsorbs the residual free bonding points on the surface of the substrate;

using inert gas as purge gas to perform purge purging;

performing oxidation treatment with an oxidizing gas;

using inert gas as purge gas to perform purge purging;

repeating the steps to obtain the ferroelectric film with the target thickness.

2. The method of claim 1, wherein the primary elemental source comprises a hafnium source; the hafnium source is selected from hafnium tetramethyamine, hafnium tetra-tert-butoxide and the like.

3. The method of claim 1, wherein the chamber temperature is set to 280-300 ℃, the reaction precursor heating temperature is 75-80 ℃, and the pressure inside the chamber is maintained at 150-185 mtorr during atomic layer deposition using the main element source as the reaction precursor.

4. The method of claim 1, wherein the ferroelectric thin film has a target thickness of 3 to 100 nm.

5. The method of claim 1, wherein the source of doping element is selected from the group consisting of trimethylaluminum, tris (dimethylamino) silane, and tris (isopropylcyclopentylalkyl) lanthanum.

6. The method of claim 1, wherein the chamber temperature is set to 280-300 ℃, the reaction precursor heating temperature is 75-80 ℃, and the pressure inside the chamber is maintained at 150-185 mtorr during the atomic layer deposition using the dopant source as the reaction precursor.

7. The method of claim 1, wherein the purge gas is an inert gas comprising argon.

8. The method of claim 1, wherein the oxidizing gas comprises H₂O、O₂And/or O₃。

9. A method for manufacturing a ferroelectric memory, comprising preparing a ferroelectric thin film obtained by the method of any one of claims 1 to 8.

10. A ferroelectric memory obtained by the method for manufacturing a ferroelectric memory according to claim 9.

Technical Field

The application belongs to the technical field of ferroelectric film preparation, and particularly relates to a preparation method of a ferroelectric film, a ferroelectric memory and a preparation method of the ferroelectric memory.

Background

With the development of the information technology industry and the progress of the society, the development of the memory plays an important role in enhancing the international competitiveness, maintaining the national security and the like. So far, mainstream memories such as high-density and low-cost DRAMs and NAND Flash have been increasingly difficult to meet the requirements of high-speed computation and low power consumption, and development of new memory technologies has become a necessary trend. Meanwhile, it is currently widely considered that a ferroelectric memory is one of the most promising new memories, in which a ferroelectric thin film is used as a storage medium to store information. The conventional perovskite ferroelectric thin film material cannot meet the requirement of the electronic device towards the miniaturization direction, so that the development of new storage medium materials is always a key research topic by the semiconductor force nation. Since the 2011 discovery of ferroelectricity in silicon-doped hafnium oxide thin films, more and more institutions and researchers have been involved in the research of hafnium oxide-based ferroelectric thin films. The novel hafnium oxide-based ferroelectric thin film exhibits numerous advantages including a wide band gap, good compatibility with CMOS processes, and strong radiation resistance, and among them, the most critical problem is the preparation of the thin film.

The ferroelectric film is prepared mainly by sol-gel method, magnetron sputtering method, pulsed laser deposition method, atomic layer deposition method, etc. Compared with other preparation methods, the atomic layer deposition method has the advantages of very accurate thickness control and component control of the film, capability of growing the film in a large area, no limitation on the shape of the substrate, better step coverage and the like.

In the process of preparing some ferroelectric films with low doping concentration by an atomic layer deposition method, the doping concentration of the prepared ferroelectric film is difficult to control, the doping concentration of the prepared ferroelectric film is often far higher than the target doping concentration, and the doping uniformity of the prepared ferroelectric film is not good when some thin films are prepared.

Disclosure of Invention

An object of the embodiments of the present application is to provide a method for manufacturing a ferroelectric thin film, a ferroelectric memory, and a method for manufacturing the same, which can obtain a ferroelectric thin film with good uniformity and low doping concentration.

In one aspect, an embodiment of the present application provides a method for preparing a ferroelectric thin film, including:

carrying out atomic layer deposition by taking a main element source as a reaction precursor, and depositing the main element on the surface of the substrate to adsorb most of free bonding points on the surface;

using inert gas as purge gas to perform purge purging;

carrying out atomic layer deposition by taking a doping element source as a reaction precursor, so that the doping element adsorbs the residual free bonding points on the surface of the substrate;

using inert gas as purge gas to perform purge purging;

performing oxidation treatment with an oxidizing gas;

using inert gas as purge gas to perform purge purging;

repeating the steps to obtain the ferroelectric film with the target thickness.

Optionally, the primary element source comprises a hafnium source; the hafnium source is selected from hafnium tetramethyamine, hafnium tetra-tert-butyl and the like; when atomic layer deposition is carried out by taking a main element source as a reaction precursor, the temperature of a cavity is 280-300 ℃, the heating temperature of the reaction precursor is 75-80 ℃, and the pressure intensity in the cavity is kept at 150-185 mtorr.

Optionally, the target thickness of the ferroelectric thin film is 3-100 nm.

Optionally, the doping element source is selected from Trimethylaluminum (TMA), tris (dimethylamino) silane (3DMAS), tris (isopropylcyclopentylalkyl) lanthanum, and the like; when the doping element source is used as a reaction precursor for atomic layer deposition, the temperature of the cavity is 280-300 ℃, the heating temperature of the reaction precursor is 75-80 ℃, and the pressure intensity in the cavity is kept at 150-185 mtorr.

Optionally, the purge gas is an inert gas, and the inert gas includes argon.

Optionally, the oxidizing gas comprises H₂O、O₂And/or O₃Ozone gas is preferred.

In a second aspect, embodiments of the present application provide a method for manufacturing a ferroelectric memory, including preparing a ferroelectric thin film, where the ferroelectric thin film is obtained by using the method of any one of the above embodiments.

In a third aspect, embodiments of the present application provide a ferroelectric memory, which is obtained by the method for manufacturing a ferroelectric memory according to the foregoing embodiments.

According to the preparation method of the ferroelectric film, the main element source is used as a reaction precursor to carry out atomic layer deposition to generate a chemical adsorption effect, main element molecules are adsorbed on the surface of the substrate to occupy most of free bonding point positions of the surface of the substrate, then inert gas is selected to remove and purge molecules in the cavity, the doping element source is directly introduced to be used as the reaction precursor to carry out atomic layer deposition after the cleaning is finished, the doping element molecules are adsorbed to the remaining free bonding points on the surface of the substrate, and the two precursor molecules can be well mixed in situ before oxidation. The method is an improved deposition method provided by utilizing self-limiting and self-saturation adsorption of the atomic layer deposition surface, and the precursors are mixed in situ in advance and are adsorbed on the surface of the substrate together, so that the uniform ferroelectric film with low doping concentration can be realized on the single-layer level, and the integral doping uniformity of the film is ensured. The method reduces the process steps and can realize better uniform doping. The ferroelectric film with uniform low doping concentration can be obtained, thereby providing possibility for memory development and application.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the application.

The summary of various implementations or examples of the technology described in this application is not a comprehensive disclosure of the full scope or all features of the disclosed technology.

Drawings

In the drawings, which are not necessarily drawn to scale, like reference numerals may describe similar components in different views. Like reference numerals having letter suffixes or different letter suffixes may represent different instances of similar components. The drawings illustrate various embodiments, by way of example and not by way of limitation, and together with the description and claims, serve to explain embodiments of the application. The same reference numbers will be used throughout the drawings to refer to the same or like parts, where appropriate. Such embodiments are illustrative, and are not intended to be exhaustive or exclusive embodiments of the present apparatus or method.

FIG. 1 is a schematic diagram of a clean substrate according to an embodiment of the present invention;

FIG. 2 is a schematic structural diagram illustrating a hafnium source precursor reaching a surface of a deposition substrate to generate chemisorption and surface reaction according to an embodiment of the present invention;

FIG. 3 is a schematic diagram of the structure of the chamber after purging the remaining precursor molecules in the chamber with an inert gas according to an embodiment of the present invention;

FIG. 4 is a schematic structural diagram of a doping element precursor injected into a chamber to adsorb remaining free bonding sites on the surface of the substrate according to an embodiment of the present invention;

FIG. 5 is a schematic diagram of the structure of the chamber after purging the remaining precursor molecules in the chamber with an inert gas according to an embodiment of the present invention;

FIG. 6 is a schematic structural diagram of a chamber filled with ozone gas for oxidation treatment according to an embodiment of the present invention;

FIG. 7 is a schematic diagram of the structure of the chamber purged with the inert gas after purging residual ozone molecules in the chamber according to the embodiment of the present invention.

Reference numerals: 1-a substrate; 2-oxygen atom; 3-a main element precursor; 4-argon atom; 5-doping element precursor; 6-ozone; 7-a main element metal oxide; 8-doped elemental metal oxide.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions of the embodiments of the present application will be clearly and completely described below with reference to the drawings of the embodiments of the present application. It should be apparent that the described embodiments are only some of the embodiments of the present application, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the described embodiments of the application without any inventive step, are within the scope of protection of the application.

Unless defined otherwise, technical or scientific terms used herein shall have the ordinary meaning as understood by one of ordinary skill in the art to which this application belongs. As used in this application, the terms "first," "second," and the like do not denote any order, quantity, or importance, but rather are used to distinguish one element from another. The word "comprising" or "comprises", and the like, means that the element or item listed before the word covers the element or item listed after the word and its equivalents, but does not exclude other elements or items. The terms "connected" or "coupled" and the like are not restricted to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "upper", "lower", "left", "right", and the like are used merely to indicate relative positional relationships, and when the absolute position of the object being described is changed, the relative positional relationships may also be changed accordingly.

Detailed descriptions of known functions and known components are omitted in the present application in order to keep the following description of the embodiments of the present application clear and concise.

The embodiment of the application discloses a preparation method of a ferroelectric film. The method comprises the following steps:

carrying out atomic layer deposition by taking a main element source as a reaction precursor, and depositing a main element on the surface of the substrate; injecting a main element source precursor into a chamber with a well-set chamber temperature to perform surface reaction, and controlling the deposition time to adsorb most of free bonding points on the surface of the substrate;

using inert gas as purge gas to perform purge purging; removing redundant reactants and byproducts through purging;

carrying out atomic layer deposition by taking a doping element source as a reaction precursor, so that the doping element adsorbs the residual free bonding points on the surface of the substrate;

using inert gas as purge gas to perform purge purging;

performing oxidation treatment with an oxidizing gas;

using inert gas as purge gas to perform purge purging;

repeating the steps to obtain the ferroelectric film with the target thickness.

According to the preparation method of the ferroelectric film, the main element source is used as a reaction precursor to carry out atomic layer deposition to generate a chemical adsorption effect, main element molecules are adsorbed to the position of the free bonding points on the surface of the substrate, and the number of the free bonding points adsorbed by the main element molecules and the number of the remaining free bonding points reach a target ratio by controlling the deposition time. And then, selecting inert gas to remove molecules in the purging chamber, directly introducing a doping element source as a reaction precursor after purging to perform atomic layer deposition, wherein the doping element molecules can only be adsorbed to the residual free bonding points on the surface of the substrate, and the two precursor molecules can be well mixed in situ before oxidation. Through in-situ mixing, the doping proportion can be controlled, and the concentration of low doping can be accurately controlled. The uniformity and ferroelectric property of the film are improved by utilizing the in-situ mixing of the precursors, the uniform stoichiometric ratio of the whole film can be kept, and the ferroelectric film with low doping concentration is obtained, so that the possibility is provided for the development and application of a memory.

In some embodiments, the primary element source comprises a hafnium source. In an exemplary embodiment, the hafnium source is organohafnium. For example, the hafnium source may be selected from hafnium tetramethyamine, hafnium tetra-tert-butoxide, and the like.

In some embodiments, when atomic layer deposition is performed using the main element source as a reaction precursor, the temperature of the chamber is 280-300 ℃, the heating temperature of the reaction precursor is 75-80 ℃, and the pressure inside the chamber is maintained at 150-185 mtorr.

In some embodiments, the ferroelectric thin film has a target thickness of 3 to 100 nm.

Different ferroelectric thin films have different doping concentrations to achieve better performance. Some exhibit optimum ferroelectric properties only at very small doping concentrations. The method of the embodiment of the application can realize the uniform doping proportion with low doping concentration. In exemplary embodiments, the source of doping elements is selected from Trimethylaluminum (TMA), tris (dimethylamino) silane (3DMAS), tris (isopropylcyclopentylalkyl) lanthanum, and the like. Of course, other organometallic materials may be used as the source of the doping element.

In some embodiments, when the atomic layer deposition is performed by using the doping element source as the reaction precursor, the temperature of the chamber is 280-300 ℃, the heating temperature of the reaction precursor is 75-80 ℃, and the pressure inside the chamber is maintained at 150-185 mtorr.

In some embodiments, the purge gas is an inert gas, preferably argon.

In some embodiments, the oxidizing gas comprises H₂O、O₂And/or O₃. For example, O may be selected₃The gas acts as an oxidizing gas.

In a second aspect, embodiments of the present application provide a method for manufacturing a ferroelectric memory, including preparing a ferroelectric thin film, where the ferroelectric thin film is obtained by using the method of any of the above embodiments.

In a third aspect, embodiments of the present application provide a ferroelectric memory, which is obtained by the method for manufacturing the ferroelectric memory of the above embodiments.

Fig. 1 to 7 are process schematic diagrams illustrating a method for manufacturing a ferroelectric thin film according to an embodiment of the present application. The present application is further illustrated by way of example in connection with fig. 1-7.