CN115084360A - Ferroelectric multivalued memory with local regulation and control characteristics and preparation method thereof - Google Patents

Abstract

The invention discloses a ferroelectric multi-value memory with local regulation characteristics and a preparation method thereof. The ferroelectric multi-value memory with local control characteristics of the present invention comprises: a substrate; a channel material formed on the substrate; a source electrode and a drain electrode formed on both ends of the channel material; hafnium-based iron Electric material, covering the above-mentioned device, as a gate dielectric layer; separating gate electrodes, four gate electrodes are arranged in parallel with each other on the gate dielectric layer and above the channel material, and an electrical pulse is used as the excitation source of the ferroelectric memory , respectively, applying voltages to the four gate electrodes to obtain four different resistance states "00", "01", "10", and "11", realizing the multi-value storage function based on local regulation characteristics.

Description

A ferroelectric multi-value memory with local control characteristics and preparation method thereof

technical field

The invention belongs to the technical field of semiconductors, and in particular relates to a ferroelectric multi-value memory with local regulation characteristics and a preparation method thereof.

Background technique

Memory plays an important role in the field of integrated circuits, and data can be written and erased by controlling the high and low resistance states. However, traditional memories only have two storage states of "0" and "1", and the storage capacity can only be realized by integrating more device units per unit area. With the continuous reduction of the semiconductor feature size, the size of the memory will gradually face physical limits, and it is difficult to increase the storage capacity through the improvement of the integration density. Therefore, it is necessary to develop a new type of storage device with multi-value storage capability, starting from the improvement of the storage capability of a single device unit, to achieve an increase in the overall storage capacity.

As a typical memory device, ferroelectric memory has become a research hotspot in recent years. Traditional ferroelectric memories are mostly based on PbZr _x Ti _1-x O ₃ (PZT), BaTiO ₃ (BTO) and other material systems, which have poor CMOS process compatibility and environmental pollution problems. Doped hafnium-based ferroelectric materials (Hf _0.5 Zr _0.5 O ₂ , HfAlO _x , HfLaO _x , HfSiO _x , etc.) have applications as an environmentally friendly ferroelectric material system compatible with CMOS processes.

Based on the principle of domain polarization inversion, the doped hafnium-based ferroelectric memory can realize stable resistance state transition and information storage. Under the regulation of voltage, most of the current doped hafnium-based ferroelectric memories realize multi-value storage state transition based on incomplete inversion of electrical domains. However, this mode of operation is faced with problems such as the uncertainty of the inversion of the electrical domain and the instability and randomness of the intermediate state, which is not suitable for the application of multi-valued memory. It is necessary to develop ferroelectric multi-value memories with local regulation characteristics, quantitative regulation of electrical domain inversion, and realization of stable stepped polymorphic transitions, which is of great significance for commercial applications.

SUMMARY OF THE INVENTION

The present invention is a ferroelectric multi-value memory with local control characteristics, comprising: a substrate; a channel material formed on the substrate; a source electrode and a drain electrode formed on both ends of the channel material; hafnium The base ferroelectric material covers the above-mentioned device as a gate dielectric layer; the gate electrode is separated, and four gate electrodes are arranged in parallel on the gate dielectric layer and located above the channel material, and the electrical pulse is used as the gate dielectric layer of the ferroelectric memory. The excitation source applies voltages to the four gate electrodes respectively, and obtains four different resistance states "00", "01", "10", and "11", and realizes the multi-value storage function based on the local regulation characteristics.

In the ferroelectric multi-value memory with local control characteristics of the present invention, preferably, the channel material is InGaZnO ₄ , ZnO or SnO ₂ .

In the ferroelectric multi-value memory with local control characteristics of the present invention, preferably, the hafnium-based ferroelectric material is Hf _0.5 Zr _0.5 O ₂ , HfAlO _x , HfLaO _x or HfSiO _x .

In the ferroelectric multi-value memory with local control characteristics of the present invention, preferably, the distance between adjacent gate electrodes is 5 μm˜20 μm.

The invention also discloses a method for preparing a ferroelectric multi-value memory with local control characteristics, comprising the following steps: forming a channel material on a substrate; forming a source electrode and a drain electrode at both ends of the channel material; A hafnium-based ferroelectric material is formed on the device as a gate dielectric layer; a separate gate electrode is formed on the gate dielectric layer, four gate electrodes are arranged in parallel with each other and are located above the channel material, and electrical pulses are used as the ferroelectric The excitation source of the memory applies voltages to the four gate electrodes respectively to obtain four different resistance states "00", "01", "10", and "11", realizing the multi-value storage function based on the local regulation characteristics.

In the preparation method of the ferroelectric multi-value memory with local control characteristics of the present invention, preferably, the step of forming the hafnium-based ferroelectric material includes: using atomic layer deposition technology to grow at a temperature of 250°C to 350°C with a thickness of 10nm～20nm doped hafnium-based material thin film; use rapid thermal annealing equipment to anneal at a temperature of 450℃～550℃ for 20s～60s under _N2 atmosphere to obtain a thin film with ferroelectricity.

In the preparation method of the ferroelectric multi-value memory with local control characteristics of the present invention, preferably, the hafnium-based ferroelectric material is Hf _0.5 Zr _0.5 O ₂ , HfAlO _x , HfLaO _x or HfSiO _x .

In the preparation method of the ferroelectric multi-value memory with local control characteristics of the present invention, preferably, the distance between adjacent gate electrodes is 5 μm˜20 μm.

Beneficial effects:

(1) By designing a memory with multi-value resistance states and increasing the storage capacity from the perspective of a single device, the problem that it is difficult to increase the storage density of integrated circuits can be solved, and a high-capacity chip with multi-bit storage capability can be developed.

(2) As a new type of inorganic ferroelectric material, doped hafnium-based thin film material can be grown and deposited by atomic layer deposition technology, which can solve the problem of environmental pollution caused by lead in traditional ferroelectric thin films and the incompatibility of CMOS technology. It is suitable for Next-generation hafnium-based ferroelectric memory.

(3) In terms of working principle, the traditional electric domain modulation method is broken, and the electric domains controlled by the design separation area are gradually inverted to replace the incomplete inversion of the electric domains in the traditional ferroelectric devices, so as to avoid the random resistance of the device during the incomplete inversion process. to obtain a stable multi-valued resistance state.

Description of drawings

FIG. 1 is a flow chart of a method for fabricating a ferroelectric multi-value memory with local control characteristics.

2 to 5 are schematic structural diagrams of each stage of a method for fabricating a ferroelectric multi-value memory with local control properties.

FIG. 6 and FIG. 7 are schematic diagrams of realizing the control of four different electric domain inversion states by using electrical pulses as the excitation source of the ferroelectric multi-value memory.

Detailed ways

In order to make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. It should be understood that the specific The embodiments are only used to explain the present invention, and are not intended to limit the present invention. The described embodiments are only some, but not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "upper", "lower", "vertical", "horizontal", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for convenience The invention is described and simplified without indicating or implying that the device or element referred to must have a particular orientation, be constructed and operate in a particular orientation, and therefore should not be construed as limiting the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed to indicate or imply relative importance.

Furthermore, numerous specific details of the present invention are described below, such as device structures, materials, dimensions, processing techniques and techniques, in order to provide a clearer understanding of the present invention. However, as can be understood by one skilled in the art, the present invention may be practiced without these specific details. Unless specifically indicated below, various parts of the device may be constructed of materials known to those skilled in the art, or materials developed in the future with similar functions may be employed.

FIG. 1 is a flow chart of a method for fabricating a ferroelectric multi-value memory with local control characteristics. As shown in Fig. 1, the preparation method of a ferroelectric multi-value memory with local control characteristics includes the following steps:

In step S1, a silicon oxide substrate is prepared for preparing a ferroelectric multi-value memory with local control properties. The silicon oxide substrate includes a silicon oxide layer 101 and a silicon wafer 100, wherein the thickness of the silicon oxide layer can be 100 nm, 200 nm, or 300 nm.

In step S2, a physical vapor deposition method is used to prepare an InGaZnO ₄ film with a thickness of 40 nm˜70 nm on the substrate as the channel 102 , as shown in FIG. 2 . The channel length is preferably 10 μm, and the range is 5 μm to 40 μm; the channel width is preferably 100 μm, and the range is 50 μm to 150 μm. The channel material can also be ZnO, SnO ₂ or the like.

In step S3, the source electrode 103 and the drain electrode 104 are prepared on both ends of the channel material by photolithography and electron beam evaporation, as shown in FIG. 3 . Among them, the thickness of Ti is preferably 5 nm to 15 nm, and the thickness of Pt is preferably 30 nm to 70 nm. The material of the source electrode and the drain electrode may be Ti/Pt, Ti/Au, Ti/Pd and the like.

In step S4, a doped hafnium-based material Hf _0.5 Zr _0.5 O ₂ thin film with a thickness of 10 nm to 20 nm is grown at a temperature of 250 to 350 ° C using atomic layer deposition technology, and rapid thermal annealing equipment is used under N ₂ atmosphere. After annealing, a ferroelectric thin film is obtained as the gate dielectric layer 105 , as shown in FIG. 4 . The annealing temperature is preferably 500°C, and the range is preferably 450°C-550°C; the annealing time is preferably 20s, and the range is 20s-60s. The doped hafnium-based material may also be HfAlO _x , HfLaO _x , HfSiO _x and the like.

In step S5, photolithography and electron beam evaporation are used to prepare Al with a thickness of 30 nm to 70 nm on the gate dielectric layer 105 to form separate gate electrodes 106, 107, 108, 109 to obtain a ferroelectric multi-value memory with local control characteristics, as shown in FIG. 5 . Show. The separation gate electrodes 106 , 107 , 108 , and 109 are located above the channel 102 , that is, the projection of the separation gate electrode in the horizontal direction and the projection of the channel in the horizontal direction have an overlapping area. Preferably, the extension direction of each gate electrode is perpendicular to the extension direction of the channel material. The size of the overlapping area between each electrode and the channel is 10 μm×10 μm, and the distance between adjacent electrodes is 5 μm˜20 μm. The material of the separation gate electrode may also be Au, Pt, Pd, or the like.

In step S6, as shown in Fig. 6 and Fig. 7, the electric pulse is used as the excitation source of the ferroelectric multi-value memory, and voltages are respectively applied to the four gate electrodes to realize the local electric domain inversion of the doped hafnium-based ferroelectric material effect. Due to the difference in the area where the voltage is applied, the domain inversion will occur in the corresponding area, while the area in which the voltage is not applied will not have the domain inversion, thus realizing the control of four different electric domain inversion states, corresponding to four different stable multi-valued states. resistance state. Specifically, when a voltage is only applied to the gate electrode 106, the corresponding resistance state 1: "00"; when a voltage is applied to the gate electrodes 106, 107, the corresponding resistance state 2: "01"; When the gate electrodes 106, 107 , 108 corresponds to resistance state 3: "10" when voltage is applied; when voltage is applied to gate electrodes 106, 107, 108, 109, corresponds to resistance state 4: "11".

The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art who is familiar with the technical scope disclosed by the present invention can easily think of changes or substitutions. All should be included within the protection scope of the present invention.

Claims (8)

1. a ferroelectric multi-value memory with local regulation characteristic, is characterized in that, include: substrate; channel material formed on the substrate; a source electrode and a drain electrode, formed at both ends of the channel material; A hafnium-based ferroelectric material, covering the above-mentioned device, serves as a gate dielectric layer; separating gate electrodes, four gate electrodes are arranged in parallel on the gate dielectric layer and above the channel material, spaced apart from each other, Using electrical pulses as excitation sources, voltages are applied to the four gate electrodes, respectively, to obtain four different resistance states "00", "01", "10", and "11", and realize the multi-value storage function based on local regulation characteristics. . 2. a kind of ferroelectric multi-value memory with local regulation characteristic according to claim 1, is characterized in that, The channel material is InGaZnO ₄ , ZnO or SnO ₂ . 3. a kind of ferroelectric multi-value memory with local control characteristic according to claim 1, is characterized in that, The hafnium-based ferroelectric material is Hf _0.5 Zr _0.5 O ₂ , HfAlO _x , HfLaO _x or HfSiO _x . 4. a kind of ferroelectric multi-value memory with local regulation characteristic according to claim 1, is characterized in that, The pitch between adjacent gate electrodes is 5 μm˜20 μm. 5. A method for preparing a ferroelectric multi-valued memory with local control characteristics, characterized in that, Include the following steps: forming channel material on the substrate; forming a source electrode and a drain electrode at both ends of the channel material; A hafnium-based ferroelectric material is formed on the above device as a gate dielectric layer; Separate gate electrodes are formed on the gate dielectric layer, four gate electrodes are arranged in parallel with each other, and are located above the channel material, Using electrical pulses as excitation sources, voltages are applied to the four gate electrodes, respectively, to obtain four different resistance states "00", "01", "10", and "11", and realize the multi-value storage function based on local regulation characteristics. . 6. The method for preparing a ferroelectric multi-value memory with local control characteristics according to claim 5, characterized in that, The step of forming the hafnium-based ferroelectric material includes: Atomic layer deposition technology is used to grow a doped hafnium-based material film with a thickness of 10nm to 20nm at a temperature of 250°C to 350°C; Using rapid thermal annealing equipment, annealing at a temperature of 450 °C to 550 °C for 20 s to 60 s under N ₂ atmosphere obtains a thin film with ferroelectricity. 7. The method for preparing a ferroelectric multi-valued memory with local control characteristics according to claim 5, wherein, The hafnium-based ferroelectric material is Hf _0.5 Zr _0.5 O ₂ , HfAlO _x , HfLaO _x or HfSiO _x . 8. The method for preparing a ferroelectric multi-valued memory with local control characteristics according to claim 5, wherein, The pitch between adjacent gate electrodes is 5 μm˜20 μm.

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