Method for inducing conversion of non-ferroelectric phase of hafnium oxide film into ferroelectric phase

Abstract

The invention relates to a method for inducing a non-ferroelectric phase of a hafnium oxide film to be converted into a ferroelectric phase based on ion implantation small-atomic-radius element doping, and the method comprises the steps: carrying out the ion implantation through employing ions with different implantation energies and implantation doses and smaller than the oxygen atomic radius, enabling the ions to be doped into an HfO2 material, inducing to generate the ferroelectric phase, and increasing the proportion of the ferroelectric phase, and furthermore, the non-ferroelectric material is converted into the ferroelectric material. The HfO2 thin film can be converted from the original non-ferroelectric polarization to certain remanent polarization, ferroelectric phase change is induced after ion implantation doping, and leakage current is increased in a controllable range under the condition that certain ferroelectric polarization is guaranteed.

Description

Technical Field

[0001] The invention is mainly applied to the field of semiconductor devices, and specifically relates to a method for inducing the transformation of a hafnium oxide film from a non-ferroelectric phase to a ferroelectric phase based on ion implantation of small atomic radius element doping. Background Art

[0002] Ferroelectric materials are a type of functional material that has spontaneous polarization, can achieve polarization reversal under an electric field, and still maintains the polarization state after the electric field is removed. They can be used in ferroelectric memory, which has the characteristics of fast read and write speed, low power consumption, and non-volatile data storage. Corresponding to modern advanced processes, the thickness of ferroelectric materials has reached more than ten nanometers or even several nanometers, which poses new challenges to the element doping method that transforms non-ferroelectric materials into ferroelectric materials.

[0003] The storage capacity of ferroelectric thin film memory is directly derived from the hysteresis characteristics of the ferroelectric layer. The coercive field and remanent polarization of the ferroelectric layer are the most important factors affecting the storage window and conductivity state. In order to meet the stable storage window, good durability and high retention time required for the memory, the ferroelectric film needs to have a certain remanent polarization strength and a controllable leakage current within a certain range.

[0004] In order to solve the compatibility problem of ferroelectric materials with CMOS process integration, it is necessary to propose a new doping method that is commonly used in CMOS process but can induce ferroelectric phase transition, so as to accurately control the ferroelectric properties of HfO2 thin film materials. Summary of the invention

[0005] The purpose of the present invention is to provide a method for realizing the transformation of a non-ferroelectric phase into a ferroelectric phase based on ion implantation of small atomic radius element doping, so as to provide a new way to induce the transformation of the non-ferroelectric phase of hafnium oxide into a ferroelectric phase and thus improve the ferroelectric properties of HfO2 materials.

[0006] The technical solution of the present invention is:

[0007] The present invention proposes a method for realizing the transformation of a non-ferroelectric phase into a ferroelectric phase by implanting an element with a small atomic radius, which is used to induce the transformation of a non-ferroelectric phase into a ferroelectric phase of metal oxides such as HfO2 and ZrO2. The method includes implanting ions with a radius smaller than that of an oxygen atom with different implantation energies and implantation doses, doping the ions into the HfO2 material, inducing the generation of a ferroelectric phase and increasing its proportion, thereby converting the non-ferroelectric material into a ferroelectric material.

[0008] The basic implementation method is to perform ion implantation on a metal oxide dielectric film capacitor structure based on elements smaller than the radius of an oxygen atom. The capacitor structure includes a metal layer, a dielectric film layer, and a metal electrode layer arranged on the dielectric film layer in sequence on the silicon substrate. After doping, a transition from zero to a residual polarization value is obtained.

[0009] The material of the first metal layer provided in the thin film capacitor structure on the substrate includes but is not limited to TiN, TaN, W, Pt, Au, Ni, Ag, and Mo;

[0010] The second dielectric film layer of the thin film capacitor structure on the substrate is HfO2 and ZrO2;

[0011] The third metal layer material of the thin film capacitor structure on the substrate includes but is not limited to TiN, TaN, W, Pt, Au, Ni, Ag, and Mo;

[0012] Furthermore, the dielectric film layer is doped with elements by ion implantation so that the metal oxide dielectric film exhibits ferroelectricity, including but not limited to doping elements with an atomic radius smaller than O such as Li, Be, B, C, and N;

[0013] In one embodiment, the implantation energy and dose, the size parameters of each layer, and the doping parameters satisfy:

[0014] The film has small roughness, high film density, and controllable leakage current range. When the applied voltage range is smaller than the saturation voltage and breakdown voltage of the ferroelectric layer, the larger the applied voltage range, the larger the residual polarization value, the larger the electric field required for ferroelectric switching, and the larger the storage window. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the experimental process of the present invention.

[0016] Figure 2 1 is a diagram showing a hysteresis loop and transient current-voltage data according to an embodiment of the present invention.

[0017] Figure 3 This is a capacitance-voltage characteristic test diagram of an embodiment of the present invention.

[0018] Figure 4 This is a leakage current test diagram of an embodiment of the present invention.

[0019] Figure 5 This is a test diagram of the anti-fatigue properties of an embodiment of the present invention.

[0020] Figure 6 This is a GIXRD characterization diagram of an embodiment of the present invention. DETAILED DESCRIPTION

[0021] The present invention will be further described in detail below in conjunction with the accompanying drawings.

[0022] In order to make the technical solution of the present invention clearer, the present invention is further described below in conjunction with the accompanying drawings. Figure 1 The structure shown in the steps is implemented:

[0023] The technical solution adopted by the present invention comprises the following steps:

[0024] (1) Select a clean and smooth substrate layer;

[0025] (2) growing a first electrode layer on the substrate layer;

[0026] (3) growing a metal oxide dielectric thin film layer of a certain thickness on the first electrode metal layer;

[0027] (4) ion doping with ions smaller than the radius of oxygen atoms is performed in the dielectric film by ion implantation. This step may occur after step (5) or before step (5);

[0028] (5) Growing a second electrode layer on the dielectric thin film layer.

[0029] (6) Performing rapid thermal annealing using RTA technology on the sample obtained in step (5) to crystallize the HfO2 film.

[0030] In step (1) of the embodiment, a clean, polished N-type silicon substrate is selected.

[0031] In step (2) of the embodiment, the first electrode layer is TiN, and magnetron sputtering is used to sputter TiN from the target material onto the substrate to deposit a TiN bottom electrode with a thickness of 20-40 nm.

[0032] In step (3) of the embodiment, the dielectric layer is HfO2, and an HfO2 film with a thickness of 10-20 nm is grown by atomic layer deposition.

[0033] In step (4) of the embodiment, ion implantation is used, and an implantation energy of 10keV-90keV and an implantation dose range of 1E11-1E17 are selected to perform elemental co-implantation of C and N ions.

[0034] In step (5) of the embodiment, the second electrode is made of TiN electrode material, and a TiN top electrode with a thickness of 60-100 nm is prepared by magnetron sputtering.

[0035] In step (6) of the embodiment, the vacuum is pumped to 10 before annealing. -4 bar, and then introduce argon to fill the environment with argon. The heating rate is 20-30℃ per second, the temperature is raised to 400-500℃, kept warm for 60s, and cooled to room temperature by water.

[0036] The structural and electrical properties of the prepared samples were tested.

[0037] The macroscopic hysteresis loop test results of the prepared injection-doped HfO2 film are shown in the attached figure. Figure 2As shown, it is obvious that compared with the paraelectricity of pure HfO2, the residual polarization intensity after ion implantation of C and N is greatly improved, which shows that the dielectric layer is a ferroelectric material.

[0038] The capacitance-voltage characteristic curve of the prepared injection-doped HfO2 film is shown in the attached figure. Figure 3 As shown, it shows the butterfly-shaped curve unique to ferroelectric materials.

[0039] The current-voltage characteristic curve of the prepared injection-doped HfO2 film is shown in the attached figure. Figure 4 As shown, it is shown that the leakage current increases slightly.

[0040] The fatigue resistance test of the prepared implanted HfO2 film is shown in the attached figure. Figure 5 As shown, it has good fatigue resistance.

[0041] The XRD characterization of the prepared implanted HfO2 thin films is shown in the attached Figure 6 As shown, it is obvious that compared with the sample without doping, the peak around 30.5° (the peak containing the ferroelectric phase) is greatly enlarged and the crystal quality is good, which proves the transformation from non-ferroelectric material to ferroelectric material from a microscopic point of view.

[0042] By using an element with an atomic radius smaller than 0 for ion implantation doping, the HfO2 film can be transformed from having no ferroelectric polarization to having a certain residual polarization strength. After ion implantation doping, a ferroelectric phase transition is induced, and the leakage current increases within a controllable range while ensuring a certain ferroelectric polarization. The HfO2 doped material prepared by the present invention has a significant improvement in ferroelectric residual polarization strength, which can provide a new way of understanding the transformation of HfO2 ferroelectric properties by element doping, and has a positive role in promoting the industrialization of modern semiconductor manufacturing that transforms metal oxide dielectric materials such as HfO2 and ZrO2 into ferroelectric materials.

[0043] The description of the above embodiments is merely illustrative and not restrictive. Any equivalent changes made according to the claims and the specification of the present invention shall fall within the protection scope of the present application.

Claims

1. A method for inducing a non-ferroelectric phase transition of a hafnium oxide film into a ferroelectric phase, the main feature of which is to use ion implantation to dope a MIM structure consisting of a metal electrode and a HfO2 film with an element of small atomic radius, the MIM structure comprising: A metal bottom electrode is grown on the silicon wafer substrate; a HfO2 dielectric film is grown on the bottom electrode; There is also a top electrode grown on the dielectric film layer. The ion implantation doping elements include but are not limited to Li, Be, B, C, N doping elements with an atomic radius smaller than O.

2. The HfO2 thin film MIM structure according to claim 1, characterized in that The bottom electrode comprises different materials and different structures.

3. HfO2 thin film MIM structure according to claim 1, characterized in that The top electrode includes different materials and different structures.

4. The method for realizing non-ferroelectric phase transition to ferroelectric phase based on doping with small atomic radius elements according to claim 1, characterized in that The small atomic radius doping method includes using an ion implantation method to implant elements with an atomic radius smaller than 0, including Li, Be, B, C, and N, with different implantation energies and different implantation doses into the HfO2 film, so that it becomes a ferroelectric material with a certain residual polarization strength.

5. The ion implanted small atomic radius element doped HfO2 thin film MIM structure according to claim 1, characterized in that The HfO2 ferroelectric film doped with ions of small atomic radius elements refers to a ferroelectric material with different material components and structures that has spontaneous polarization and maintains spontaneous polarization when the electric field is removed, can be flipped under the action of the electric field, and the polarization of the ferroelectric is nonlinearly related to the electric field.

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