Selective orientational electrode thin film, and manufacturing method thereof

Abstract

To provide a selective orientational electrode thin film, and a manufacturing method thereof.SOLUTION: The present invention relates to a thin film manufacturing technique field. A thin film includes a silicon substrate, and a first seed layer, a second seed layer and a lower electrode layer sequentially grown on the silicon substrate. The first seed layer is an AxB1-xN thin film, where A=Cu, Fe, B=Pd, Pt, and 0<x<1. One or more kinds of thin films among a chromium nitride thin film, a titanium nitride thin film, a tantalum nitride thin film and a magnesium oxide thin film are used for the second seed layer. One or more kinds of thin films among a platinum thin film, a titanium nitride thin film, a gold thin film, a ruthenium thin film and a niobium-doped strontium titanate thin film are used for a lower electrode thin film. They have a selective orientation in a (001) crystal direction, thereby solving such a problem that a conventional silicon substrate cannot acquire a (001) selective orientation thin film.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to the field of thin film manufacturing technology, and more particularly to a selective orientation electrode thin film and a method for manufacturing the same. [Background technology]

[0002] Many studies have demonstrated that thin films with (00l) crystal orientation have a wide range of applications in microelectronics and nanoelectronics. Compared with thin films with (111) crystal orientation and polycrystalline thin films, thin films with (001) crystal orientation have superior piezoelectric, ferroelectric, magnetic memory, and other properties.

[0003] For example, in the field of magnetic random memory, epitaxial growth of a bottom electrode with (001) crystal orientation can enhance the tunneling magnetoresistance (TMR) of devices by up to 50% or more compared to a bottom electrode with (111) crystal orientation or hybrid crystal orientation. In addition, in the structural compound of strontium titanate, thin films with (001) preferred orientation also have better piezoelectric performance than thin films with (111) preferred orientation and polycrystalline thin films. However, most of the previous research results have focused on substrates such as magnesium oxide and strontium titanate (STO), which have a relatively good match with the electrode crystal lattice, and cannot be applied to the silicon semiconductor field. Therefore, integrating thin films with (001) crystal orientation into the current silicon-based large-scale integrated circuit industry is a major challenge. Summary of the Invention

[0004] In order to overcome the above technical deficiencies, the object of the present invention is to provide a selective orientation electrode thin film and a manufacturing method thereof, which aims to solve the problem that a thin film with a (001) preferential orientation cannot be obtained on a substrate in the conventional silicon semiconductor field.

[0005] The present invention discloses a selective orientation electrode thin film,

[0006] a silicon substrate; and a first seed layer, a second seed layer, and a lower electrode layer sequentially grown on the silicon substrate;

[0007] The first seed layer is A x B 1-x N thin film, A=Cu, Fe, B=Pd, Pt, 0 <x<1であり

[0008] The second seed layer is made of one or more of a chromium nitride thin film, a titanium nitride thin film, a tantalum nitride thin film, and a magnesium oxide thin film;

[0009] The lower electrode thin film is one or more of a platinum thin film, a titanium nitride thin film, a gold thin film, a ruthenium thin film, and a niobium-doped strontium titanate thin film, which has a preferred orientation in the (001) direction.

[0010] Preferably, the substrate includes a silicon substrate, a silicon surface oxide substrate, a silicon surface nitride substrate, a silicon carbide substrate, a metal substrate, a glass substrate, and a magnesium oxide substrate.

[0011] Preferably, the first seed layer and the second seed layer each have a thickness of 2 nm to 500 nm.

[0012] Preferably, a buffer layer is disposed between the substrate and the first seed layer, and the buffer layer is a metal thin film or a metal nitride thin film.

[0013] Preferably, the buffer layer includes a tantalum thin film, a chromium thin film, a titanium thin film, a titanium nitride thin film, or a tantalum nitride thin film, and the thickness of the buffer layer is 2 nm to 50 nm.

[0014] The present invention further provides a method for producing a selective orientation electrode thin film,

[0015] providing a substrate, pretreating the substrate, and mounting the substrate on a sample stage in a magnetron sputtering apparatus;

[0016] A first target was connected to a magnetron sputtering device, and a first seed layer was grown under nitrogen and inert gas. The first seed layer thus formed was A x B 1-x N thin film, A=Cu, B=Pd, Pt, 0 <x<1であるステップと、

[0017] finishing the sputtering of the first seed layer, connecting a second target, and growing a second seed layer under nitrogen, oxygen, and an inert gas, the formed second seed layer being one or a combination of a chromium nitride thin film, a titanium nitride thin film, a tantalum nitride thin film, and a magnesium oxide thin film;

[0018] and finishing sputtering the second seed layer and connecting a third target to grow a bottom electrode layer having a preferred orientation in a (001) crystal orientation, the bottom electrode layer being one or a combination of a chromium thin film, a titanium nitride thin film, a gold thin film, a ruthenium thin film, or a niobium-doped strontium titanate thin film.

[0019] Preferably, before connecting the first target

[0020] A fourth target is connected and a buffer layer is pre-grown on the substrate.

[0021] Preferably, the substrate temperature, the flow rate and the pressure of the gas to be introduced are determined based on the first seed layer or the second seed layer formed.

[0022] Preferably, the first seed layer and the second seed layer formed have a thickness of 2 nm to 500 nm.

[0023] Preferably, the substrate includes a silicon substrate, a silicon surface oxide substrate, a silicon surface nitride substrate, a silicon carbide substrate, a metal substrate, a glass substrate, and a magnesium oxide substrate.

[0024] Compared with the prior art, the above technical solutions have the following beneficial effects:

[0025] The electrode thin film and the method for producing the same provided by the present application are A x B 1-x By using a N thin film as the first seed layer and chromium nitride, titanium nitride, tantalum nitride, magnesium oxide, etc. as the second seed layer, a bottom electrode thin film structure with a highly preferred orientation in the (001) crystal direction can be obtained. Not only does element diffusion not occur even at high temperatures, but it can also be used as a high-quality bottom electrode in the semiconductor field to improve device performance, and can also provide the effect of controlling the crystal orientation for the growth of crystalline bodies of functional thin films such as piezoelectric, ferroelectric, and magnetic memories with a (001) crystal orientation that are subsequently grown. [Brief description of the drawings]

[0026] [Figure 1] FIG. 1 is a schematic diagram showing the structure of a selective orientation electrode thin film according to a first embodiment of the present invention.

[0027] [Diagram 2] FIG. 2 is a structural schematic diagram showing a buffer layer of a first embodiment of the selective orientation electrode thin film of the present invention.

[0028] [Diagram 3] FIG. 3 is a flow diagram of a second embodiment of the method for producing a selective orientation electrode thin film of the present invention.

[0029] [Figure 4] FIG. 4 is an XRD diagram of the thin film produced in Example 2 of the method for producing the selective orientation electrode thin film of the present invention.

[0030] [Diagram 5] FIG. 5 is a transmission electron microscope image of the thin film manufactured by the method for manufacturing the selective orientation electrode thin film according to the second embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] The advantages of the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0032] DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. Where the following description refers to the accompanying drawings, unless otherwise indicated, like numerals in different accompanying drawings refer to the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present disclosure. On the contrary, they are merely examples of apparatus and methods consistent with certain aspects of the present disclosure, as set forth in the appended claims.

[0033] The terms used in this disclosure are used only for the purpose of describing certain embodiments and are not intended to limit the disclosure. As used in this disclosure and the appended claims, the singular forms "a," "the," and "said" are also intended to include the plural forms unless the context clearly indicates otherwise. The term "and / or" as used herein should be understood to refer to and include any or all possible combinations of one or more associated listed items.

[0034] It should be understood that although the disclosure uses the terms first, second, third, etc. to describe various types of information, such information is not limited to these terms. These terms are only used to distinguish one type of information from another. Depending on the context, the word "for example" as used herein may be interpreted as "when" or "when" or "based on a determination."

[0035] In describing the present invention, it should be understood that the directions or positional relationships indicated by the terms "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "lower", "inner", "outer" and the like are based on the orientations or positional relationships shown in the accompanying drawings, but are intended to facilitate and simplify the description of the present invention, and do not necessarily indicate or imply that the indicated devices or elements have a specific orientation, structure and operation in a specific orientation, and this should not be understood as limiting the present invention.

[0036] In the description of the present invention, unless otherwise specified and limited, it should be noted that the terms "mounted", "connected", and "connected" should be understood broadly. For example, it may be a mechanical connection or an electrical connection, or it may be the internal communication of two elements, a direct connection, or an indirect connection via an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms based on the specific situation.

[0037] In the following description, suffixes such as "module", "member", or "unit" are used to represent elements only for the convenience of explaining the present invention, and they have no specific meaning in themselves. Therefore, "module" and "member" may be used interchangeably.

[0038] Example 1. The present invention discloses a selectively oriented electrode thin film and is used to provide a lower electrode thin film structure that realizes (001) high-degree selective orientation on a silicon substrate. Specifically, referring to FIG. 1, it includes a silicon substrate, a first seed layer, a second seed layer, and a lower electrode layer that are sequentially grown on the silicon substrate. The first seed layer is an A x B px N thin film, where A = Cu, Fe, B = Pd, Pt, 0 < x < 1. The second seed layer is one or more thin films selected from chromium nitride thin film, titanium nitride thin film, tantalum nitride thin film, and magnesium oxide thin film, but not limited thereto. The lower electrode thin film is one or more thin films selected from platinum thin film, titanium nitride thin film, gold thin film, ruthenium thin film (SrRuO3 thin film or niobium-doped strontium titanate (Nb·doped·SrTiO3) thin film), but not limited thereto, and it has a selective orientation in the (001) crystal direction.

[0039] As an example, the electrode thin film provided in this embodiment is an A that is easy to form in the (001) crystal direction x B 1-xAn N film is used as the first seed layer, where A = Cu, Fe, B = Pd, Pt, and 0 < x < 1. This improves the problem that lattice mismatches are likely to occur between the silicon substrate and the lower electrode, and provides a template that grows in the (001) crystal direction for the growth of subsequent thin films. Then, chromium nitride, tantalum nitride, magnesium oxide, etc. are used as the second seed layer to not only solve the diffusion problem of copper elements (used in the first seed layer) at high temperatures, but also the crystal structure of which is also in the (001) crystal orientation, and the lattice constant is closer to that of the lower electrode used in this embodiment such as platinum and titanium nitride, further reducing the problem of lattice mismatch between the silicon substrate and the lower electrode layer, thus growing a high-quality (001) crystal orientation lower electrode thin film.

[0040] As described above, the highly selectively oriented lower electrode thin film structure in the (001) crystal direction in this embodiment not only does not cause element diffusion even at high temperatures, but can also be used as a high-quality lower electrode in the semiconductor field, enhancing the performance of the device, and further providing the function of controlling the crystal orientation for the growth of crystals of functional thin films such as piezoelectric, ferroelectric, and magnetic memory with a subsequent growth (001) crystal orientation, that is, obtaining thin films with other high degrees of selective orientation.

[0041] In this embodiment, the above substrate includes, but is not limited to, a silicon substrate, a surface-oxidized silicon substrate, a surface-nitrided silicon substrate, a silicon carbide substrate, a metal substrate, and a glass substrate. Conventional substrates such as a magnesium oxide substrate may also be used. As described above, it may be formed so as to easily have a (001) crystal orientation in the first seed layer. For this reason, the problem that conventional (001) highly selectively oriented thin films are mainly applied on substrates such as magnesium oxide and strontium titanate (STO) that match the lower electrode crystal lattice and cannot be applied in the silicon semiconductor field can be overcome.

[0042] In the above embodiment, the thickness of the first seed layer and the second seed layer is preferably 2nm-500nm. Most preferably, the thickness of the first seed layer is 50nm, the thickness of the second seed layer is 30nm, the first seed layer and the second seed layer have a certain thickness limit, the lattice constants of the first seed layer and the second seed layer are identical or similar, so that the subsequently grown bottom electrode thin film (or other thin film) has a highly preferred crystal orientation of (001), and the whole structure of the grown thin film is a high-quality device with a highly preferred (001) orientation, and the crystal orientation of the first seed layer and the second seed layer is also (001).

[0043] In this embodiment, optionally, referring to FIG. 2, a buffer layer may be provided between the substrate and the first seed layer, and the buffer layer is provided to improve the surface roughness and adhesion of the substrate, specifically, the buffer layer includes but is not limited to tantalum thin film, tantalum nitride, chromium thin film, titanium thin film or titanium nitride thin film, and the thickness of the buffer layer is 2 nm to 50 nm, and the buffer layer may be provided before growing the first seed layer, the second seed layer and the lower electrode layer, so as to enhance the stability of the connection between the subsequent first seed layer and the substrate. The subsequently grown first seed layer, the second seed layer and the lower electrode layer and the lower electrode thin film are stably arranged on the substrate, and the highly selectively oriented crystal orientation of (001) formed can provide the function of controlling the crystal orientation for the growth of the subsequent functional thin film such as piezoelectric, ferroelectric, and magnetic memory.

[0044] In embodiment 2, the present invention further provides a method for manufacturing a selectively oriented electrode thin film, which is used to manufacture the electrode thin film highly selectively oriented in the (001) crystal direction in embodiment 1 above, referring to FIG. 3, including:

[0045] Step S10 of providing a substrate, pretreating the substrate, and mounting the substrate on a sample stage of a magnetron sputtering apparatus;

[0046] In this embodiment, the substrate includes silicon substrate, surface-oxidized silicon substrate, surface-nitrided silicon substrate, silicon carbide substrate, metal substrate, glass substrate, magnesium oxide substrate, as described below. As described in the above embodiment, the substrate may also include other conventional substrates. It should be noted that the above pretreatment is specifically for the cleaning process of the substrate, including but not limited to RCA standard cleaning of the substrate surface, and may specifically be cleaning the substrate surface with a suitable reagent according to the substrate material.

[0047] A first target was connected to a magnetron sputtering apparatus, and a first seed layer was grown under nitrogen and inert gas. The first seed layer thus formed was A x B 1-x N thin film, A=Cu, Fe, B=Pd, Pt, 0 <x<1であるステップS20と、

[0048] Specifically, before the first seed layer is grown by magnetron sputtering, the magnetron sputtering cavity is subjected to a vacuum pumping process, and the vacuum of the specific cavity is 7*10 -8 When the pressure is less than mTorr (or adjusted based on the substrate or sputtering first seed layer), the substrate is mounted on a sample stage in a magnetron sputtering apparatus, and the first target can be an alloy target.

[0049] Step S30: finishing the sputtering of the first seed layer, connecting a second target, and growing a second seed layer under nitrogen, oxygen, and an inert gas, the formed second seed layer being one or a combination of chromium nitride thin film, titanium nitride thin film, tantalum nitride thin film, and magnesium oxide thin film, and the second target may be a metal target;

[0050] Step S40: terminate sputtering of the second seed layer, connect a third target, and grow a bottom electrode layer with a preferred orientation in the (001) crystal direction, where the formed bottom electrode layer is one or more of a chromium thin film, a titanium nitride thin film, a gold thin film, a ruthenium thin film, or a niobium-doped strontium titanate thin film, and the third target can be a metal target.

[0051] The present embodiment provides a manufacturing method, in which a first seed layer, a second seed layer and a lower electrode layer are sputtered on a substrate in order, the first seed layer formed improves the problem of lattice mismatch between a silicon substrate and a lower electrode, the second seed layer grown from it not only solves the element diffusion problem (used in the first seed layer) under high temperature, but also has a crystalline structure with a (001) crystal orientation, and grows a high-quality (001) crystal orientation lower electrode thin film, whose lattice constants are all the same or similar, and the thicknesses of the first seed layer and the second seed layer formed are 2nm to 500nm, and most preferably, the thickness of the first seed layer is 50nm, and the thickness of the second seed layer is 30nm. Specifically, the time, temperature, etc. of the sputtering growth of the first seed layer, the second seed layer and the lower electrode layer described below are all different.

[0052] In a preferred embodiment, before connecting the first target, a fourth target may be connected, and a buffer layer may be grown on the substrate in advance, the buffer layer may be a metal thin film or a metal nitride thin film. The buffer layer includes a tantalum thin film, a tantalum nitride thin film, a chromium thin film, a titanium thin film or a titanium nitride thin film, and the thickness of the buffer layer is 2 nm to 50 nm. The buffer layer may be prepared in advance before growing the first seed layer, the second seed layer and the lower electrode layer, so as to improve the roughness and adhesiveness of the substrate surface and to increase the stability of the connection between the subsequent first seed layer and the substrate.

[0053] It should be noted that in the above steps S10 - S40, based on the formed first seed layer, second seed layer, and lower electrode layer, the substrate temperature, the flow rate and pressure of the introduced gas are determined. That is, based on the different thin films of the formed first seed layer, second seed layer, and lower electrode layer, the sputtering conditions to be controlled are different. Specifically, by way of example, it will be explained that the lower electrode thin film manufactured by the manufacturing method provided using the present embodiment in the following specific manufacturing example has a highly selective orientation of (001) crystal orientation.

[0054] Provide a silicon (Si) substrate, and it may be subjected to pretreatment such as cleaning. Perform a vacuum pumping process in the magnetron sputtering cavity, attach the Si substrate to the sample stage in the magnetron sputtering apparatus, and connect a Cu x Pd 1-x (0 < x < 1) alloy target, introduce nitrogen and oxygen respectively, turn on the DC sputtering power supply, grow at an output of 30w - 80w, and finish the sputtering of the first seed layer. The first seed layer Cu x Pd 1-x N (Cu x Pd 1-x N, 0 < x < 1) thin film is obtained, and its thickness is 50nm. Connect a metal chromium target, introduce nitrogen and oxygen respectively, the flow rate ratio of nitrogen to oxygen is 0.1 - 0.5, grow under an output of 20w - 80w, and finish the sputtering of the second seed layer. A chromium nitride (CrN) thin film of the second seed layer is obtained, and its thickness is 30nm. Connect a metal chromium target, introduce pure oxygen, raise the temperature to 100°C - 300°C and then keep it warm, turn on the DC sputtering power supply, grow under an output of 10w - 50w, turn off the sputtering power supply, and finish the sputtering of the platinum thin film. A thin film with a highly selective orientation of (001) is obtained, and its thickness is 40nm. Finish the growth of the thin film and take out the grown thin film.

[0055] The thin film manufactured in this example is the first seed layer Cu on the silicon substrate x Pd 1-x N (Cu x Pd 1-xAn N (0 < x < 1) thin film, a second seed layer chromium nitride (CrN) thin film, are grown on a (001) highly selectively oriented lower electrode platinum thin film. All of them have a high (001) crystal orientation. At the same time, the (001) highly selectively oriented lower electrode layer platinum thin film can also guide the subsequent thin films to grow along the (001) crystal orientation. FIG. 4 shows the XRD measurement diagram of the thin films grown in this embodiment. It is fully explained that not only there is a (001) peak of the thin film, but also there is no (111) peak, and the manufactured lower electrode thin film has a high selectively oriented (001) crystal orientation.

[0056] By the manufacturing process exemplified above, the thin films manufactured in this embodiment further include a tantalum thin film grown in advance on a surface oxidized silicon (SiO2) substrate, a first seed layer Cu x Pd 1-x N (Cu x Pd 1-x An N (0 < x < 1) thin film, a second seed layer chromium nitride (CrN) thin film, and a (001) highly selectively oriented lower electrode platinum thin film are grown. Except for the tantalum thin film, they are amorphous (i.e., the above buffer layer), and all the remaining layer thin films have a high (001) crystal orientation. At the same time, the (001) highly selectively oriented lower electrode layer platinum thin film can also guide the subsequent thin films to grow along the (001) crystal orientation. FIG. 5 shows the transmission electron microscope (TEM) diagram at a high temperature (450 °C). No element diffusion occurs between the thin films of each layer.

[0057] It should be noted that the embodiments of the present invention have excellent practicability and are not limited to any form of the present invention. Those skilled in the art can use the above-disclosed technical content to change or modify equivalent effective embodiments. However, within the scope of not departing from the content of the technical solution means of the present invention, any changes or equivalent changes and modifications to the above embodiments based on the technical entity of the present invention all belong to the scope of the technical solution means of the present invention.

Claims

1. In the selective orientation electrode thin film, a substrate; and a first seed layer, a second seed layer, and a lower electrode layer, which are sequentially grown on the substrate; The first seed layer is A ｘ B １－ｘ N thin film, A=Cu, Fe, B=Pd, Pt, 0<x<1, The second seed layer is made of one or more of a chromium nitride thin film, a titanium nitride thin film, a tantalum nitride thin film, and a magnesium oxide thin film; The lower electrode thin film is one or more of a platinum thin film, a titanium nitride thin film, a gold thin film, a ruthenium thin film, or a niobium-doped strontium titanate thin film, and has a preferred orientation in the (001) crystal direction.

2. The substrate includes a silicon substrate, a silicon surface oxide substrate, a silicon surface nitride substrate, a silicon carbide substrate, a metal substrate, a glass substrate, and a magnesium oxide substrate; The electrode thin film according to claim 1 .

3. The thickness of the first seed layer and the second seed layer is 2 nm to 500 nm. The electrode thin film according to claim 1 .

4. A buffer layer is disposed between the substrate and the first seed layer, the buffer layer being a metal thin film or a metal nitride thin film; The electrode thin film according to claim 1 .

5. The buffer layer includes a tantalum thin film, a chromium thin film, a titanium thin film, a titanium nitride thin film, and a tantalum nitride thin film, and the thickness of the buffer layer is 2 nm to 50 nm; The electrode thin film according to claim 4 .

6. In the method for producing a selective orientation electrode thin film, providing a substrate, pretreating the substrate, and mounting the substrate on a sample stage in a magnetron sputtering apparatus; A first target is connected under a magnetron sputtering apparatus, and a first seed layer is grown under nitrogen and an inert gas. The first seed layer thus formed is A ｘ B １－ｘ N thin film, A=Cu, Fe, B=Pd, Pt, 0<x<1; terminate the sputtering of the first seed layer, connect a second target, and grow a second seed layer under nitrogen / oxygen and inert gas, the formed second seed layer being one or a combination of a chromium nitride thin film, a titanium nitride thin film, a tantalum nitride thin film, and a magnesium oxide thin film; and finishing sputtering the second seed layer, connecting a third target, and growing a lower electrode layer having a preferred orientation in the (001) crystal direction, the formed lower electrode layer being one or a combination of a platinum thin film, a titanium nitride thin film, a gold thin film, a ruthenium thin film, or a niobium-doped strontium titanate thin film.

7. A fourth target is connected, and a buffer layer is pre-grown on the substrate, the buffer layer being a metal thin film or a metal nitride thin film; The method according to claim 6 .

8. determining a substrate temperature, a flow rate and a pressure of the gas to be introduced based on the formed first seed layer or the formed second seed layer; The method according to claim 6 .

9. The thickness of the first seed layer and the second seed layer formed is 2 nm to 500 nm; The method according to claim 6 .

10. The substrate includes a silicon substrate, a silicon surface oxide substrate, a silicon surface nitride substrate, a silicon carbide substrate, a metal substrate, a glass substrate, and a magnesium oxide substrate; The method according to claim 6 .

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