A method for preparing titanium nitride film, titanium nitride film and semiconductor structure

Abstract

The present application provides a method for preparing a titanium nitride film, a titanium nitride film and a semiconductor structure. Tetramethylammonium titanium is introduced into a reaction chamber, and the tetramethylammonium titanium is adsorbed on the surface of a substrate, and the substrate is located in the reaction chamber; the tetramethylammonium titanium is heated and decomposed to obtain dimethylamine gas and a first titanium nitride film located on the surface of the substrate; a metal salt is introduced into the reaction chamber, and the metal salt reacts with dimethylamine to obtain a second titanium nitride film located on the surface of the substrate; the second titanium nitride film is a first titanium nitride film doped with a metal. The titanium nitride film doped with a metal is prepared by using tetramethylammonium titanium and a metal salt, and the operation steps are simple and the cost is low. Moreover, by doping the metal, the intrinsic resistivity of the titanium nitride film can be reduced, and the conductivity of the titanium nitride film can be improved, thereby improving the overall conductivity of the tungsten plug.

Description

Technical Field

[0001] The present application relates to the field of semiconductor technology, and in particular to a method for preparing a titanium nitride film, a titanium nitride film and a semiconductor structure. Background Art

[0002] In semiconductor applications, tungsten plugs (W Plugs) can achieve connections between adjacent metal layers. There is generally a dielectric layer such as a silicon dioxide layer between adjacent metal layers. Holes can be punched in the dielectric layer to make tungsten plugs. Specifically, titanium (Ti) film, titanium nitride (TiN) film and metal tungsten (W) can be deposited in sequence in the through hole. The metal tungsten completely fills the through hole. The titanium nitride film is mainly used as a metal barrier layer. It can not only prevent the corrosion of the reaction raw material tungsten hexafluoride (WF6) on the adhesion layer titanium film during the chemical vapor deposition of metal tungsten film (Chemical Vapor Deposition W, CVD W) process, but also prevent the metal tungsten from diffusing to the adjacent dielectric layer. However, the intrinsic resistivity of the titanium nitride film is higher than that of the titanium film and the tungsten film. The resistivity of the titanium nitride film is about 220×10 -8 , the resistivity of tungsten film is about 5.3×10 -8 , the resistivity of titanium film is about 42×10 -8 , affecting the overall conductivity of the tungsten plug. Especially with the continuous miniaturization of the process, the hole structure of the tungsten plug is getting smaller and smaller, and the influence of the intrinsic resistivity of the titanium nitride film is getting greater and greater, which restricts the overall conductivity of the tungsten plug. Summary of the invention

[0003] In view of this, the purpose of this application is to provide a method for preparing a titanium nitride film, a titanium nitride film and a semiconductor structure, which can reduce the intrinsic resistivity of the titanium nitride film by doping metal, improve the conductivity of the titanium nitride film, and thus improve the overall conductivity of the tungsten plug. The specific scheme is as follows:

[0004] The present application provides a method for preparing a titanium nitride film, comprising:

[0005] introducing tetrakis dimethylammonium titanium into a reaction chamber, wherein the tetrakis dimethylammonium titanium is adsorbed on a surface of a substrate, and the substrate is located in the reaction chamber;

[0006] heating the tetradimethylammonium titanium to decompose it to obtain dimethylamine gas and a first titanium nitride film located on the surface of the substrate;

[0007] A metal salt is introduced into the reaction chamber, and the metal salt reacts with the dimethylamine to obtain a second titanium nitride film located on the surface of the substrate; the second titanium nitride film is the first titanium nitride film doped with a metal.

[0008] In a possible implementation, the metal salt is at least one of a vanadium salt, an antimony salt, a germanium salt, a chromium salt, a yttrium salt, a manganese salt or a cobalt salt.

[0009] In one possible implementation, the vanadium salt is vanadium tetrachloride or vanadium fluoride.

[0010] In a possible implementation manner, the content of the doped metal element in the second titanium nitride film is less than or equal to 10%.

[0011] In one possible embodiment, the vaporized tetrakis dimethylammonium titanium is introduced into the reaction chamber using a target gas as a carrier gas, wherein the first gas includes at least one of nitrogen or helium. In one possible embodiment, the temperature at which the tetrakis dimethylammonium titanium is heated is greater than or equal to 350° C. and less than or equal to 500° C.

[0012] The present application also provides a titanium nitride film layer, including the second titanium nitride film prepared by the method described.

[0013] The present application also provides a semiconductor structure, comprising:

[0014] substrate;

[0015] A dielectric layer located on one side of the substrate, the dielectric layer having a through hole;

[0016] a barrier layer, the barrier layer being located in the through hole, the barrier layer comprising the titanium nitride film layer as claimed in claim 7;

[0017] A conductive metal layer covers a surface of the barrier layer and fills the through hole.

[0018] In a possible implementation, the semiconductor structure further includes: an adhesion layer, wherein the adhesion layer covers the inner wall of the through hole, and the titanium nitride film layer covers the surface of the adhesion layer.

[0019] In a possible implementation manner, along the thickness direction of the barrier layer, the doping content of the metal element in the second titanium nitride film gradually changes.

[0020] The embodiment of the present application provides a method for preparing a titanium nitride film, a titanium nitride film and a semiconductor structure, wherein tetradimethylammonium titanium is introduced into a reaction chamber, and the tetradimethylammonium titanium is adsorbed on the surface of a substrate, and the substrate is located in the reaction chamber; the tetradimethylammonium titanium is heated and decomposed to obtain dimethylamine gas and a first titanium nitride film located on the surface of the substrate; a metal salt is introduced into the reaction chamber, and the metal salt reacts with dimethylamine to obtain a second titanium nitride film located on the surface of the substrate; the second titanium nitride film is a first titanium nitride film doped with a metal. The titanium nitride film doped with a metal is prepared by using tetradimethylammonium titanium and a metal salt, and the operation steps are simple and the cost is low. Moreover, by doping metal, the intrinsic resistivity of the titanium nitride film can be reduced, and the conductivity of the titanium nitride film can be improved, thereby improving the overall conductivity of the tungsten plug. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0022] Figure 1 A schematic diagram of a process for preparing a titanium nitride thin film provided in an embodiment of the present application is shown;

[0023] Figure 2 A schematic diagram of a reaction process provided in an embodiment of the present application is shown;

[0024] Figure 3 A schematic diagram of another reaction process provided in an embodiment of the present application is shown;

[0025] Figure 4 A schematic diagram of a semiconductor structure provided by an embodiment of the present application is shown. DETAILED DESCRIPTION

[0026] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below with reference to the accompanying drawings.

[0027] In the following description, many specific details are set forth to facilitate a full understanding of the present application, but the present application may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present application. Therefore, the present application is not limited to the specific embodiments disclosed below.

[0028] Secondly, the present application is described in detail with reference to the schematic diagram. When describing the embodiments of the present application in detail, for the sake of convenience, the cross-sectional diagrams showing the device structure will not be partially enlarged according to the general scale, and the schematic diagrams are only examples, which should not limit the scope of protection of the present application. In addition, in actual production, the three-dimensional dimensions of length, width and depth should be included.

[0029] As described in the background technology, the influence of the intrinsic resistivity of titanium nitride film is also increasing, which restricts the overall conductivity of tungsten plugs. Doping trace elements to change the material structure to achieve material multifunctionality is one of the common ways to improve materials, and is widely used in various industries. In the lithium battery industry, improving the conductivity of electrode materials by metal doping is one of the common means. At present, the preparation of metal-doped titanium nitride films in other thin film fields is a two-step method: first low-temperature doping, using vanadium salt as a dopant, doping into titanium precursors or titanium dioxide (TiO2), and then high-temperature nitriding, passing NH3 or N2 / H2 to nitridate the vanadium-doped titanium precursor or vanadium-doped TiO2, and preparing a vanadium-doped TiN film, but the operation steps of this method are relatively cumbersome and the cost is high. In the field of metal thin films of semiconductors, no solution for improving the conductivity of thin films by metal doping has been proposed.

[0030] The embodiment of the present application provides a method for preparing a titanium nitride film, a titanium nitride film and a semiconductor structure, wherein tetradimethylammonium titanium is introduced into a reaction chamber, and the tetradimethylammonium titanium is adsorbed on the surface of a substrate, and the substrate is located in the reaction chamber; the tetradimethylammonium titanium is heated and decomposed to obtain dimethylamine gas and a first titanium nitride film located on the surface of the substrate; a metal salt is introduced into the reaction chamber, and the metal salt reacts with dimethylamine to obtain a second titanium nitride film located on the surface of the substrate; the second titanium nitride film is a first titanium nitride film doped with a metal. The titanium nitride film doped with a metal is prepared by using tetradimethylammonium titanium and a metal salt, and the operation steps are simple and the cost is low. Moreover, by doping metal, the intrinsic resistivity of the titanium nitride film can be reduced, and the conductivity of the titanium nitride film can be improved, thereby improving the overall conductivity of the tungsten plug.

[0031] For ease of understanding, a method for preparing a titanium nitride film, a titanium nitride film, and a semiconductor structure provided in an embodiment of the present application are described in detail below with reference to the accompanying drawings.

[0032] refer to Figure 1 , which is a schematic flow chart of a method for preparing a titanium nitride film provided in an embodiment of the present application, the method comprises the following steps.

[0033] S101, introducing tetrakis dimethylammonium titanium into a reaction chamber, and adsorbing the tetrakis dimethylammonium titanium on a surface of a substrate, and the substrate is located in the reaction chamber.

[0034] In the embodiment of the present application, the titanium nitride film can be prepared by metal-organic chemical vapor deposition (MOCVD), or other methods can be used. A substrate is provided in the reaction chamber, and the substrate can include a silicon dioxide layer deposited on a silicon substrate. Subsequently, a titanium nitride film can be formed on the silicon dioxide layer, or a through hole can be formed in the silicon dioxide layer, and a titanium nitride film can be formed in the through hole. The following is an example of forming a titanium nitride film on a silicon dioxide layer.

[0035] Specifically, tetradimethylammonium titanium (C8H 24 N4Ti, TDMAT), tetradimethylammonium titanium forms a layer of TDMAT molecules on the substrate surface through chemical surface adsorption and reaction, thereby achieving the adsorption of tetradimethylammonium titanium on the substrate surface, which is convenient for the subsequent preparation of titanium nitride film.

[0036] In a possible implementation, the vaporized tetradimethylammonium titanium can be transported into the reaction chamber by a carrier gas, and a target gas can be used as the carrier gas, and the target gas can be nitrogen (N2), helium (He), or a mixture of nitrogen and helium. In this way, after the tetradimethylammonium titanium enters the transmission pipeline, it is vaporized by high pressure treatment, and then the vaporized tetradimethylammonium titanium is passed into the reaction chamber by the carrier gas, and the operation is relatively simple.

[0037] S102, heating the tetradimethylammonium titanium to decompose it to obtain dimethylamine gas and a first titanium nitride film located on the surface of the substrate.

[0038] In the embodiment of the present application, the tetramethylammonium tetraoxide can be heated. Under high temperature conditions, the tetramethylammonium tetraoxide can undergo a decomposition reaction to obtain dimethylamine gas and a first titanium nitride film. The first titanium nitride film can be formed on the surface of the substrate. The dimethylamine gas can be used for subsequent metal doping, thereby improving the utilization rate of the reaction products and saving materials. In addition, the tetramethylammonium tetraoxide can also be decomposed to obtain by-products such as hydrocarbons, which need to be removed later to avoid affecting the titanium nitride film.

[0039] The temperature for heating the tetradimethylammonium titanium can be greater than or equal to 350°C and less than or equal to 500°C, so as to avoid the situation where the temperature is too low and the dimethylamine gas and the first titanium nitride film cannot be decomposed, and the process waste caused by excessively high temperature can be avoided. For example, the temperature for heating the tetradimethylammonium titanium can be 380°C, 400°C, 420°C, 450°C or 480°C.

[0040] S103, introducing a metal salt into the reaction chamber, the metal salt reacts with dimethylamine to obtain a second titanium nitride film located on the surface of the substrate; the second titanium nitride film is the first titanium nitride film doped with a metal.

[0041] In an embodiment of the present application, after the decomposition reaction of the tetradimethylamine titanium occurs, a metal salt can be introduced into the reaction chamber, for example, the metal salt can be introduced within 10 seconds after the tetradimethylamine titanium is introduced. The metal salt can be a salt compound composed of metal ions, and the metal salt can react with dimethylamine, and the product can be doped into the first titanium nitride film, thereby obtaining a first titanium nitride film doped with a metal, which can be recorded as a second titanium nitride film. In this way, the metal doping of the titanium nitride film can be achieved, and the metal can provide a doping energy level, which can reduce the intrinsic resistivity of the titanium nitride film, improve the conductivity of the titanium nitride film, and then improve the overall conductivity of the tungsten plug. In addition, the use of tetradimethylamine titanium and metal salts to prepare a titanium nitride film doped with a metal has simple operation steps and low cost.

[0042] In a possible implementation, an inert gas such as helium (He), neon (Ne) or argon (Ar) may be used as a carrier gas to pass the metal salt into the reaction chamber.

[0043] Specifically, the metal salt can be at least one of vanadium salt, antimony salt, germanium salt, chromium salt, yttrium salt, manganese salt or cobalt salt, such as Sb (antimony), Ge (germanium), Cr (chromium), Y (yttrium), Mn (manganese), Co (cobalt) and other metal precursor compounds. The metal salt can be vanadium tetrachloride (VCl4), vanadium fluoride (F3V), antimony chloride (SbCl3), germanium chloride (GeCl4), etc.

[0044] For example, when the metal salt is VCl4, VCl4 can be introduced into the reaction chamber with an inert gas as a carrier gas, VCl4 reacts with dimethylamine, and the generated vanadium nitride (NV) is doped into the first titanium nitride film, thereby obtaining a vanadium-doped first titanium carbide film. Figure 2 and Figure 3 As shown, it is a schematic diagram of a reaction process provided in an embodiment of the present application, TDMAT is used as a precursor reactant to undergo high-temperature decomposition to obtain a first titanium nitride film and dimethylamine gas deposited on a substrate, and the introduced vanadium tetrachloride reacts with the dimethylamine gas to form a vanadium-doped first titanium nitride film on the substrate, and the by-products can be extracted from the chamber.

[0045] By using vanadium salt as a dopant, vanadium in the +3 valence state is doped into the titanium nitride film. The valence of titanium in titanium nitride is +4 valence state, so vanadium provides a doping energy level to improve the conductivity of the titanium nitride film. Specifically, when intrinsic thermal excitation occurs, electrons gain energy from the full band (E v ) transitions to the conduction band (E c ) becomes a conductive carrier, and the transition bandgap width is recorded as the first bandgap width. After vanadium doping, the hole moves from the doping energy level (E A ) jumps to the conduction band to become a conductive carrier. The bandgap width is the second bandgap width, and the second bandgap width is smaller than the first bandgap width. Therefore, the conductivity of the titanium nitride film after doping is higher than that of the titanium nitride film before doping.

[0046] In the embodiment of the present application, the content of metal doping can be controlled by controlling the gas flow rate and the time of passing the metal salt, and the content of metal doping is positively correlated with the gas flow rate or the time of passing, and the proportion of the metal doping content in the second titanium nitride film can be less than or equal to 10%, thereby ensuring the conductivity of the second titanium nitride film. For example, the proportion of the metal doping content in the second titanium nitride film can be 3%, 5% or 8%.

[0047] In an embodiment of the present application, after obtaining the second titanium nitride film, the byproducts can be evacuated. The byproducts may include at least one of halides or hydrocarbons. The byproducts can be pumped out of the reaction chamber by a pump to avoid contamination of the titanium nitride film.

[0048] The embodiment of the present application provides a method for preparing a titanium nitride film, wherein tetradimethylammonium titanium is introduced into a reaction chamber, and the tetradimethylammonium titanium is adsorbed on the surface of a substrate, and the substrate is located in the reaction chamber; the tetradimethylammonium titanium is heated and decomposed to obtain dimethylamine gas and a first titanium nitride film located on the surface of the substrate; a metal salt is introduced into the reaction chamber, and the metal salt reacts with dimethylamine to obtain a second titanium nitride film located on the surface of the substrate; the second titanium nitride film is a first titanium nitride film doped with a metal. The titanium nitride film doped with a metal is prepared by using tetradimethylammonium titanium and a metal salt, and the operation steps are simple and the cost is low. Moreover, by doping with metal, the intrinsic resistivity of the titanium nitride film can be reduced, and the conductivity of the titanium nitride film can be improved, thereby improving the overall conductivity of the tungsten plug.

[0049] Based on the method for preparing a titanium nitride film provided in the above embodiment, the embodiment of the present application further provides a titanium nitride film layer, including a second titanium nitride film prepared by the above method, which can improve the conductivity of the titanium nitride film.

[0050] The present application also provides a semiconductor structure, referring to Figure 4, which is a schematic diagram of a semiconductor structure provided in an embodiment of the present application, the semiconductor structure includes a substrate 101 , a dielectric layer 102 , a barrier layer 103 and a conductive metal layer 104 .

[0051] Specifically, a dielectric layer 102 may be formed on one side of the substrate, the dielectric layer may have a through hole, a barrier layer 103 may be formed in the through hole, and the barrier layer 103 may include a titanium nitride film layer, that is, the second titanium nitride film may serve as the barrier layer 103. A conductive metal layer 104 may also be formed on the surface of the barrier layer 103, the conductive metal layer 104 may completely fill the through hole, the conductive metal layer may be a tungsten material, thereby forming a tungsten plug structure, and the second titanium nitride film 105 may block the conductive metal layer from diffusing to the adjacent dielectric layer 102, thereby improving the conductivity of the titanium nitride film and improving the overall conductivity of the tungsten plug.

[0052] In an embodiment of the present application, in the through hole, an adhesion layer 105 may also be provided between the barrier layer 103 and the dielectric layer 102, and the adhesion layer 105 covers the inner wall of the through hole, thereby forming a titanium nitride film layer on the surface of the adhesion layer 105. The adhesion layer 105 may be, for example, a titanium layer, thereby facilitating the formation of a titanium nitride film layer in the through hole.

[0053] In an embodiment of the present application, the doping content of the metal element in the second titanium nitride film can gradually change along the thickness direction of the barrier layer 103. By controlling the content of the metal salt introduced, the doping content can be controlled, such as gradually increasing, gradually decreasing, or first increasing and then decreasing, etc., so as to meet different needs.

[0054] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the method embodiment, since it is basically similar to the device embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the device embodiment.

[0055] The above is only a preferred implementation of the present application. Although the present application has been disclosed as a preferred embodiment, it is not intended to limit the present application. Any technician familiar with the art can use the above disclosed methods and technical contents to make many possible changes and modifications to the technical solution of the present application without departing from the scope of the technical solution of the present application, or modify it into an equivalent embodiment of equivalent changes. Therefore, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present application without departing from the content of the technical solution of the present application still falls within the scope of protection of the technical solution of the present application.

Claims

1. A method for preparing a titanium nitride thin film, characterized in that: include: introducing tetrakis dimethylammonium titanium into a reaction chamber, wherein the tetrakis dimethylammonium titanium is adsorbed on a surface of a substrate, and the substrate is located in the reaction chamber; heating the tetradimethylammonium titanium to decompose it to obtain dimethylamine gas and a first titanium nitride film located on the surface of the substrate; A metal salt is introduced into the reaction chamber, and the metal salt reacts with the dimethylamine to obtain a second titanium nitride film located on the surface of the substrate; the second titanium nitride film is the first titanium nitride film doped with a metal.

2. The method according to claim 1, characterized in that The metal salt is at least one of vanadium salt, antimony salt, germanium salt, chromium salt, yttrium salt, manganese salt or cobalt salt.

3. The method according to claim 2, characterized in that The vanadium salt is vanadium tetrachloride or vanadium fluoride.

4. The method according to claim 1, characterized in that: The content of the doped metal element in the second titanium nitride film is less than or equal to 10%.

5. The method according to claim 1, characterized in that The vaporized tetrakis dimethylammonium titanium is introduced into the reaction chamber by using a first gas as a carrier gas, wherein the first gas includes at least one of nitrogen and helium.

6. The method according to claim 1, characterized in that The temperature for heating the tetrakisdimethylammonium titanium is greater than or equal to 350° C. and less than or equal to 500° C.

7. A titanium nitride film layer, characterized in that: The invention comprises the second titanium nitride film prepared by the method described in any one of claims 1 to 6.

8. A semiconductor structure, characterized in that: include: substrate; A dielectric layer located on one side of the substrate, the dielectric layer having a through hole; a barrier layer, the barrier layer being located in the through hole, the barrier layer comprising the titanium nitride film layer as claimed in claim 7; A conductive metal layer covers the surface of the barrier layer and fills the through hole.

9. The structure according to claim 8, characterized in that The semiconductor structure further includes an adhesion layer, wherein the adhesion layer covers the inner wall of the through hole, and the titanium nitride film layer covers the surface of the adhesion layer.

10. The structure according to claim 8, characterized in that Along the thickness direction of the barrier layer, the doping content of the metal element in the second titanium nitride film gradually changes.

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