Preparation method for alloy thin film

Abstract

A preparation method for an alloy thin film, comprising: providing a reaction chamber, wherein a spraying device and a bearing platform are arranged in the reaction chamber; placing a front-end-of-line structure on the surface of the bearing platform; forming, on the surface of the front-end-of-line structure, an alloy thin film in which a first element to the M-th element have a characteristic atomic ratio, wherein the step comprises: configuring the spraying device to have a characteristic temperature, setting a characteristic distance between the spraying device and the bearing platform, configuring a flow stabilizing device to have a characteristic flow, and introducing a first precursor to the M-th precursor into the chamber under the conditions of the characteristic temperature, the characteristic distance and the characteristic flow, wherein M is an integer greater than or equal to 2; and adjusting the characteristic atomic ratio by adjusting the value of any one or more parameters, i.e., the characteristic temperature, the characteristic distance and the characteristic flow. The preparation method for an alloy thin film has a simple process, and the alloy thin film can achieve controllable adjustment of the atomic ratio between different elements.

Description

A method for preparing alloy thin film

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to the Chinese patent application filed with the Patent Office of China on June 13, 2023, with application number 202310703009.8 and invention name “A method for preparing an alloy film”, the entire contents of which are incorporated by reference into this application. Technical Field

[0003] The present application relates to the field of semiconductor manufacturing technology, and in particular to a method for preparing an alloy thin film. Background Art

[0004] As the integration density of semiconductor integrated circuits continues to increase, the process dimensions of complementary metal oxide semiconductor (CMOS) devices are becoming smaller and smaller, and the thickness of polysilicon gate dielectrics is also constantly decreasing. The gate leakage current caused by direct electron tunneling increases accordingly, which can easily lead to excessive power consumption of complementary metal oxide semiconductor devices and even device failure. Since high-k dielectrics can increase the physical thickness of the gate dielectric while maintaining the gate capacitance unchanged, replacing traditional silicon oxynitride dielectrics with high-k dielectrics has become a development trend in semiconductor technology. However, high-k dielectrics represented by hafnium-based materials have poor compatibility with polysilicon gates, which affects the electrical performance of semiconductor devices. Metal gates can better solve the above problems, thus developing process technologies for replacing silicon oxynitride gate dielectrics with high-k dielectric materials and replacing polysilicon gates with metal gates.

[0005] The effective work function is one of the most important parameters in a metal gate structure and the primary factor affecting threshold voltage. The effective work function of a metal gate structure is related to the work function of the material that makes up the metal gate structure, which in turn must match the energy of the carriers in the channel. Titanium-aluminum-based metal gates are the preferred metal gate structure for small-scale NMOS devices because the work functions of titanium and aluminum are close to the silicon conduction band. For high-performance devices, the work function of the metal gate structure must be adjustable.

[0006] Currently, physical vapor deposition (PVD) or atomic layer deposition (ALD) is generally used to prepare titanium aluminum thin films to obtain titanium aluminum-based metal gates, and the effective work function of the metal gate is adjusted by changing the titanium / aluminum ratio of the titanium aluminum-based metal gate. However, the PVD process will damage the gate dielectric, and the thickness of the obtained film varies greatly, affecting the quality of the subsequent process and thus reducing the electrical performance of the device. The ALD process adjusts the growth temperature so that the titanium-aluminum ratio in the titanium aluminum film is difficult to control and the process of adjusting the precursor pulse time is relatively complicated, affecting the stability of mass production. Therefore, it is necessary to provide a method for preparing an alloy film.

[0007] Summary of the Invention

[0008] Therefore, the technical problem to be solved by the present application is to overcome the defects of the alloy film preparation method in the prior art that the process cannot be simple and the atomic ratio between different elements in the formed alloy film is difficult to control and the batch production stability is poor, thereby providing a method for preparing alloy films.

[0009] The present application provides a method for preparing an alloy film, which includes a first element to an Mth element. The method for preparing the alloy film includes: providing a reaction chamber, the reaction chamber is provided with a spray device and a supporting platform, optionally, a spray device is set on the top of the reaction chamber, and a supporting platform is set below the spray device; a front-process structure is placed on the surface of the supporting platform; an alloy film with a characteristic atomic ratio of the first element to the Mth element is formed on the surface of the front-process structure, the steps including: setting the spray device to have a characteristic temperature; setting a characteristic distance between the spray device and the supporting platform; setting a flow stabilization device to have a characteristic flow rate; under the conditions of characteristic temperature, characteristic distance, and characteristic flow rate, introducing a first precursor to an Mth precursor into the reaction chamber through the spray device, where M is an integer greater than or equal to 2, and any mth precursor includes the mth element, and m is an integer greater than or equal to 1 and less than or equal to M; the characteristic atomic ratio is adjusted by adjusting the values ​​of any one or several parameters among the characteristic temperature, characteristic distance, and characteristic flow rate.

[0010] Optionally, for any m1th element and m2th element among the first element to the Mth element, the two have different atomic activities, optionally, the atomic activity of the m1th element is higher than the atomic activity of the m2th element, m1 and m2 are both integers greater than or equal to 1 and less than or equal to M, and m1 is not equal to m2; the characteristic atomic ratio of the m1th element and the m2th element increases with the increase of the characteristic temperature; the characteristic atomic ratio of the m1th element and the m2th element decreases with the increase of the characteristic distance, and the characteristic atomic ratio of the m1th element and the m2th element decreases with the increase of the characteristic flow rate.

[0011] Optionally, M is equal to 2; the alloy film includes titanium and aluminum; the process of introducing the first precursor to the Mth precursor into the reaction chamber under the conditions of characteristic temperature, characteristic distance and characteristic flow is: introducing a titanium-containing precursor and an aluminum-containing precursor into the reaction chamber under the conditions of characteristic temperature, characteristic distance and characteristic flow; adjusting the characteristic atomic ratio of titanium and aluminum elements in the alloy film by adjusting the characteristic temperature; and / or adjusting the characteristic atomic ratio of titanium and aluminum elements in the alloy film by adjusting the characteristic distance; and / or adjusting the characteristic atomic ratio of titanium and aluminum elements in the alloy film by adjusting the characteristic flow.

[0012] Optionally, the step of adjusting the characteristic atomic ratio of titanium and aluminum elements in the alloy film by adjusting the characteristic temperature includes: increasing the characteristic atomic ratio of titanium and aluminum elements in the alloy film by raising the characteristic temperature, or reducing the characteristic atomic ratio of titanium and aluminum elements in the alloy film by lowering the characteristic temperature.

[0013] Optionally, the step of adjusting the characteristic atomic ratio of titanium and aluminum elements in the alloy film by adjusting the characteristic distance includes: reducing the characteristic atomic ratio of titanium and aluminum elements in the alloy film by increasing the characteristic distance, or increasing the characteristic atomic ratio of titanium and aluminum elements in the alloy film by decreasing the characteristic distance.

[0014] Optionally, adjusting the characteristic atomic ratio of titanium and aluminum elements in the alloy film by adjusting the characteristic flow rate includes: reducing the characteristic atomic ratio of titanium and aluminum elements in the alloy film by increasing the characteristic flow rate, or increasing the characteristic atomic ratio of titanium and aluminum elements in the alloy film by reducing the characteristic flow rate.

[0015] Optionally, when forming different alloy films with different characteristic atomic ratios, the flow rate of any mth precursor remains unchanged, the temperature of the reaction chamber remains unchanged, the pulse time of any mth precursor remains unchanged, and the carrier gas flow rate when the mth precursor enters the reaction chamber remains unchanged.

[0016] Optionally, the process of forming an alloy film having a characteristic atomic ratio of the first element to the Mth element on the surface of the previous process structure includes an atomic layer deposition process; the step of introducing the first precursor to the Mth precursor into the reaction chamber under the conditions of characteristic temperature, characteristic distance, and characteristic flow includes: performing several consecutive sub-cycle depositions, any one sub-cycle deposition is used to deposit a layer of atomic layer film; in any one sub-cycle deposition, the first precursor to the Mth precursor are alternately introduced into the reaction chamber under the conditions of characteristic temperature, characteristic distance, and characteristic flow, and a purge step is also performed between the steps of introducing different precursors.

[0017] Optionally, the characteristic temperature has a value range of 120° C. to 220° C.; the characteristic distance has a value range of 2 mm to 15 mm; and the characteristic flow rate has a value range of 500 sccm to 1100 sccm.

[0018] Optionally, the temperature of the titanium-containing precursor before entering the spraying device is room temperature, optionally 18°C-35°C, and the temperature of the aluminum-containing precursor before entering the spraying device is 40°C-115°C.

[0019] Optionally, the reaction chamber includes a first sub-reaction chamber and a second sub-reaction chamber located within the first sub-reaction chamber, a heating device is provided between the first sub-reaction chamber and the second sub-reaction chamber, and the supporting platform is located in the second sub-reaction chamber. Optionally, the alloy film is a metal gate layer; the front-process structure includes a substrate layer, a high-dielectric gate dielectric layer located on one side of the substrate layer, and a barrier layer located on the side of the high-dielectric gate dielectric layer facing away from the substrate layer; the metal gate layer is located on the surface of the barrier layer facing away from the substrate layer. The technical solution of this application has the following advantages:

[0020] The preparation method of the alloy film provided in the present application includes: providing a reaction chamber, the reaction chamber being equipped with a spray device and a supporting platform; placing a pre-process structure on the surface of the supporting platform; forming an alloy film with a characteristic atomic ratio of the first element to the Mth element on the surface of the pre-process structure, the steps including: setting the spray device to have a characteristic temperature; setting a characteristic distance between the spray device and the supporting platform; setting the flow stabilization device to have a characteristic flow rate; introducing the first precursor to the Mth precursor into the reaction chamber under the conditions of the characteristic temperature, characteristic distance, and characteristic flow rate, where M is an integer greater than or equal to 2; adjusting the characteristic atomic ratio by adjusting the values ​​of any one or more parameters among the characteristic temperature, characteristic distance, and characteristic flow rate, thereby avoiding the influence of thermal instability caused by adjusting the growth temperature of the film deposition, that is, the temperature of the reaction chamber, and reducing the correlation influence between the precursor pulse and the source carrier gas during adjustment. The process is simple, the atomic ratio of different elements in the alloy film can be accurately controlled, and the batch stability is good, thereby achieving stable adjustment of the effective work function of the metal gate layer alloy film and ensuring the electrical performance of the device.

[0021] Furthermore, the process of forming an alloy film having a characteristic atomic ratio of the first element to the Mth element on the surface of the previous process structure includes an atomic layer deposition process; the atomic layer deposition process has a high conformal step coverage, and thus can improve the uniformity of the alloy film layer, ensure the processing quality of the subsequent process, and further improve the electrical performance of the device.

[0022] Furthermore, the reaction chamber includes a first sub-reaction chamber and a second sub-reaction chamber located within the first sub-reaction chamber. The heating device is located between the first and second sub-reaction chambers, and the supporting platform is located within the second sub-reaction chamber. The heating device located between the first and second sub-reaction chambers can ensure uniform temperature distribution in the first and second sub-reaction chambers, while preventing large temperature fluctuations in the reaction chambers, further reducing the impact of thermal instability and improving the quality and preparation results of the alloy thin film.

[0023] Furthermore, the alloy film is a metal gate layer; the pre-process structure includes a substrate layer, a high-K gate dielectric layer located on one side of the substrate layer, and a barrier layer located on the side of the high-K gate dielectric layer facing away from the substrate layer; the metal gate layer is located on the surface of the barrier layer facing away from the substrate layer. By adjusting the values ​​of any one or more of the characteristic temperature, characteristic distance, and characteristic flow rate to adjust the characteristic atomic ratio, the thermal instability caused by adjusting the growth temperature of the thin film deposition, that is, the temperature of the reaction chamber, can be avoided. This prevents the metal material in the metal gate layer and the material in the high-K gate dielectric layer from interdiffusion or chemical reaction when the growth temperature changes, causing the atomic ratio of the elements in the metal gate layer to change and become difficult to accurately control. It can also reduce the correlation between the precursor pulse adjustment and the source carrier gas, facilitating process adjustment. The barrier layer provided between the high-K gate dielectric layer and the metal gate layer can further prevent the metal material in the metal gate layer and the material in the high-K gate dielectric layer from interdiffusion or chemical reaction, thereby ensuring the electrical performance of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the specific implementation methods of the present application or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the specific implementation methods or the description of the prior art. Obviously, the drawings described below are some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0025] FIG1 is a flow chart of a method for preparing an alloy thin film provided in one embodiment of the present application. DETAILED DESCRIPTION

[0026] The following will clearly and completely describe the technical solution of this application in conjunction with the accompanying drawings. Obviously, the embodiments described are only part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of this application.

[0027] In the description of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate the description of this application and simplify the description. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on this application. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0028] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on the specific circumstances.

[0029] In addition, the technical features involved in the different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0030] This embodiment provides a method for preparing an alloy thin film, wherein the alloy thin film includes a first element to an Mth element. Referring to FIG1 , the method for preparing the alloy thin film includes the following steps:

[0031] Step S1: providing a reaction chamber, wherein the reaction chamber is provided with a spray device and a carrying platform; optionally, the spray device is provided on the top of the reaction chamber, and the carrying platform is located below the spray device;

[0032] Step S2: placing a pre-process structure on the surface of the carrying platform;

[0033] Step S3: forming an alloy film having a characteristic atomic ratio of the first element to the Mth element on the surface of the previous process structure, the steps comprising: setting a spray device to have a characteristic temperature; setting a characteristic distance between the spray device and the supporting platform; setting a flow stabilizing device to have a characteristic flow rate; optionally, the spray device is a spray plate, and the flow stabilizing device is a mass flow controller of the purge gas; introducing the first precursor to the Mth precursor into the reaction chamber through the spray device under the conditions of the characteristic temperature, characteristic distance and characteristic flow rate, where M is an integer greater than or equal to 2, any mth precursor includes the Mth element, and m is an integer greater than or equal to 1 and less than or equal to M;

[0034] Step S4: adjusting the characteristic atomic ratio by adjusting the values ​​of any one or more parameters among the characteristic temperature, characteristic distance and characteristic flow rate.

[0035] Since adjusting the growth temperature of thin film deposition, that is, the temperature of the reaction chamber, will cause thermal instability on the alloy film, causing the elements in the alloy film to diffuse into the gate dielectric layer, not only affecting the device performance, but also the atomic ratio of different elements will change from time to time and be difficult to control. The precursor generally enters the reaction chamber through a carrier gas, resulting in the need to adjust the carrier gas flow rate accordingly when adjusting the precursor pulse. Not only is the process complicated, but it is also difficult to control the atomic ratio of different elements in the alloy film, and the batch stability is poor, which in turn affects the effective work function adjustment of the metal gate layer and the electrical performance of the device.

[0036] The preparation method of the alloy film provided in this embodiment affects the adsorption capacity of atoms of different elements by changing the temperature of the spray device and the distance between the spray device and the carrier platform, and affects the desorption capacity of atoms of different elements by changing the flow rate of the purging gas steady flow device, thereby avoiding the thermal instability effect on the elements of the alloy film caused by the growth temperature adjustment and the carrier gas flow correlation effect caused by the precursor pulse adjustment. It has been verified through experiments that the titanium-aluminum ratio in the titanium-aluminum-based alloy film, that is, the atomic ratio of titanium to aluminum, changes in a positive linear manner with the temperature of the spray device, and changes in a positive linear manner with the distance between the spray device and the carrier platform and the steady flow rate of the purging gas. Inverse linear change, that is, the titanium-aluminum ratio increases with the increase of the temperature of the spray device, decreases with the increase of the distance between the spray device and the supporting platform, and decreases with the increase of the steady flow rate of the purge gas. If the temperature or pulse time of the reaction chamber is adjusted, the titanium-aluminum ratio will show a curved change, so that the characteristic atomic ratio in the alloy film can be adjusted to the target ratio by adjusting the values ​​of any one or several parameters among the characteristic temperature, characteristic distance and characteristic flow rate. Therefore, the preparation method of the alloy film can simply realize the accurate control of the atomic ratio between the various elements in the alloy film and effectively improve the stability of mass production.

[0037] In one embodiment, for any m1th element and m2th element among the first element to the Mth element, the two have different atomic activities, optionally, the atomic activity of the m1th element is higher than the atomic activity of the m2th element, m1 is an integer greater than or equal to 1 and less than or equal to M, m2 is an integer greater than or equal to 1 and less than or equal to M, and m1 is not equal to m2; the characteristic atomic ratio of the m1th element and the m2th element increases with the increase of the characteristic temperature; the characteristic atomic ratio of the m1th element and the m2th element decreases with the increase of the characteristic distance, and the characteristic atomic ratio of the m1th element and the m2th element decreases with the increase of the characteristic flow rate.

[0038] In one embodiment, M is equal to 2; the alloy film includes titanium and aluminum; the process of introducing the first precursor to the Mth precursor into the reaction chamber through a spray device under the conditions of characteristic temperature, characteristic distance, and characteristic flow is: introducing a titanium-containing precursor and an aluminum-containing precursor into the reaction chamber through a spray device under the conditions of characteristic temperature, characteristic distance, and characteristic flow; adjusting the characteristic atomic ratio of titanium and aluminum elements in the alloy film by adjusting the characteristic temperature; and / or adjusting the characteristic atomic ratio of titanium and aluminum elements in the alloy film by adjusting the characteristic distance; and / or adjusting the characteristic atomic ratio of titanium and aluminum elements in the alloy film by adjusting the characteristic flow.

[0039] In one embodiment, the step of adjusting the characteristic atomic ratio of titanium and aluminum elements in the alloy film by adjusting the characteristic temperature includes: increasing the characteristic atomic ratio of titanium and aluminum elements in the alloy film by raising the characteristic temperature, or reducing the characteristic atomic ratio of titanium and aluminum elements in the alloy film by lowering the characteristic temperature.

[0040] In one embodiment, the step of adjusting the characteristic atomic ratio of titanium and aluminum elements in the alloy film by adjusting the characteristic distance includes: reducing the characteristic atomic ratio of titanium and aluminum elements in the alloy film by increasing the characteristic distance, or increasing the characteristic atomic ratio of titanium and aluminum elements in the alloy film by decreasing the characteristic distance.

[0041] In one embodiment, adjusting the characteristic atomic ratio of titanium and aluminum elements in the alloy film by adjusting the characteristic flow rate includes: reducing the characteristic atomic ratio of titanium and aluminum elements in the alloy film by increasing the characteristic flow rate, or increasing the characteristic atomic ratio of titanium and aluminum elements in the alloy film by reducing the characteristic flow rate.

[0042] In one embodiment, when forming different alloy films with different characteristic atomic ratios, the flow rate of any mth precursor remains unchanged, the temperature of the reaction chamber remains unchanged, the pulse time of any mth precursor remains unchanged, and the carrier gas flow rate when the mth precursor is introduced into the reaction chamber remains unchanged.

[0043] M is equal to 2; when a titanium-containing precursor and an aluminum-containing precursor are alternately introduced into the reaction chamber through a spray device under the conditions of characteristic temperature, characteristic distance, and characteristic flow rate to form different alloy films with different characteristic atomic ratios, the flow rates of the titanium-containing precursor and the aluminum-containing precursor remain unchanged, the temperature of the reaction chamber remains unchanged, the pulse time of the titanium-containing precursor and the aluminum-containing precursor remains unchanged, and the flow rate of the carrier gas carrying the titanium-containing precursor and the aluminum-containing precursor into the reaction chamber remains unchanged. In a specific embodiment, the temperature of the reaction chamber is 350°C-450°C, for example, 380°C, 400°C or 420°C; the first precursor and the second precursor are introduced into the reaction chamber through a carrier gas carrying source, such as a titanium-containing precursor and an aluminum-containing precursor are carried into the reaction chamber by a carrier gas, the carrier gas includes an inert gas, such as nitrogen, the flow rate of the carrier gas is 1000sccm, the purity of the carrier gas is 99.9999%, the pulse time of the titanium-containing precursor is 0.1s-5s, for example, 3s; the pulse time of the aluminum-containing precursor is 0.1s-35s, for example, 20s.

[0044] In one embodiment, the process of forming an alloy thin film having a characteristic atomic ratio of the first element to the Mth element on the surface of the previous process structure includes an atomic layer deposition process; the atomic layer deposition process has high conformal step coverage, thereby improving the uniformity of the deposited alloy thin film layer, ensuring the processing quality of the subsequent process, and further improving the electrical performance of the device.

[0045] In one embodiment, the step of introducing the first precursor to the Mth precursor into the reaction chamber through a spray device under the conditions of characteristic temperature, characteristic distance, and characteristic flow rate includes: performing several consecutive sub-cycle depositions, any one sub-cycle deposition is used to deposit a layer of atomic layer film; in any one sub-cycle deposition, the first precursor to the Mth precursor are alternately introduced into the reaction chamber through a spray device under the conditions of characteristic temperature, characteristic distance, and characteristic flow rate, and a purge step is also performed between the steps of introducing different precursors.

[0046] In one embodiment, the characteristic temperature ranges from 120°C to 220°C, such as 130°C, 150°C, 180°C, 200°C or 210°C.

[0047] In one embodiment, the characteristic distance has a value range of 2 mm to 15 mm, for example, 3 mm, 4 mm, 6 mm, 8 mm, 10 mm, 12 mm or 14 mm.

[0048] In one embodiment, the characteristic flow rate has a value range of 500 sccm-1100 sccm, for example, 550 sccm, 600 sccm, 650 sccm, 700 sccm, 850 sccm, 950 sccm or 1000 sccm.

[0049] In one embodiment, before the titanium-containing precursor and the aluminum-containing precursor are introduced into the reaction chamber under the conditions of characteristic temperature, characteristic distance, and characteristic flow rate, the temperature of the titanium-containing precursor is room temperature, optionally 18°C-35°C, for example, 20°C, 25°C, or 30°C; the temperature of the aluminum-containing precursor is 40°C-115°C, for example, 50°C, 65°C, 75°C, 85°C, or 100°C.

[0050] In one embodiment, the reaction chamber includes a first sub-reaction chamber and a second sub-reaction chamber located within the first sub-reaction chamber. The heating device is located between the first and second sub-reaction chambers, and the supporting platform is located within the second sub-reaction chamber. The heating device located between the first and second sub-reaction chambers can ensure uniform temperature distribution in the first and second sub-reaction chambers, thereby improving the quality and preparation results of the alloy thin film.

[0051] In one embodiment, the alloy film is a metal gate layer; the pre-process structure includes a substrate layer, a high-K gate dielectric layer located on one side of the substrate layer, and a barrier layer located on the side of the high-K gate dielectric layer facing away from the substrate layer; the metal gate layer is located on the surface of the barrier layer facing away from the substrate layer. By adjusting the values ​​of any one or more of the characteristic temperature, characteristic distance, and characteristic flow rate to adjust the characteristic atomic ratio, the thermal instability caused by adjusting the growth temperature of the thin film deposition, i.e., the temperature of the reaction chamber, can be avoided. This prevents the metal material in the metal gate layer and the material in the high-K gate dielectric layer from interdiffusion or chemical reaction when the growth temperature changes, causing the atomic ratio of the elements in the metal gate layer to change and become difficult to accurately control. It can also reduce the impact of the precursor pulse adjustment on the source carrier gas, facilitating process adjustment. The barrier layer provided between the high-K gate dielectric layer and the metal gate layer can further prevent the metal material in the metal gate layer and the material in the high-K gate dielectric layer from interdiffusion or chemical reaction, thereby ensuring the electrical performance of the device.

[0052] In one embodiment, the substrate layer includes a silicon substrate layer; the material of the high-K gate dielectric layer includes hafnium oxide; and the material of the barrier layer includes titanium nitride.

[0053] The preparation method of the alloy film provided in this embodiment can simply adjust the characteristic atomic ratio in the alloy film to a target ratio, thereby achieving controllable adjustment of the effective work function of the metal gate layer. It can avoid the thermal instability caused by adjusting the temperature of the reaction chamber, that is, the film growth temperature, on the elements of the alloy film, which leads to uncontrollable characteristic atomic ratio in the alloy film. It improves the batch production stability of the characteristic atomic ratio of the alloy film, prevents mutual diffusion or chemical reaction between the metal material in the alloy film and the high dielectric gate dielectric in the complementary metal oxide semiconductor device, avoids the complementary metal oxide semiconductor device from causing greater leakage current and effective work function offset, and improves the electrical performance and product yield of the complementary metal oxide semiconductor device.

[0054] The preparation method of the alloy film provided in this embodiment can also avoid adjusting the pulse time from the first precursor to the Mth precursor. Since the pulse time from the first precursor to the Mth precursor will bring about related influences and the adjustment is more complicated, the preparation method of the alloy film provided in this embodiment makes the preparation of the alloy film simpler.

[0055] The preparation method of the alloy film adopts the atomic layer deposition process to avoid damage to the High-K gate dielectric layer in the complementary metal oxide semiconductor device, and can also avoid large differences in film thickness in the alloy film. Especially for high aspect ratio fin field effect transistors (FinFET devices), it can avoid leakage of the FinFET and affect the quality of the subsequent process, and can further improve the electrical performance and product yield of the FinFET or complementary metal oxide semiconductor device.

[0056] Alloy films with different characteristic atomic ratios, that is, metal gate film layers with different characteristic atomic ratios, can enable the metal gate structure to have different effective work functions close to the conduction band edge of the silicon substrate, thereby improving the process compatibility with the corresponding N-type metal-oxide-semiconductor high dielectric (High-K) dielectric material layer and silicon substrate, as well as the electrical performance of the N-type metal-oxide-semiconductor.

[0057] The following provides specific embodiments to clearly and completely describe the technical solution of the present application.

[0058] Example 1

[0059] The present embodiment provides a method for preparing an alloy film, comprising: providing a reaction chamber, wherein a spray device is provided on the top of the reaction chamber, and the reaction chamber further comprises a carrying platform located below the spray device; placing a front-process structure on the surface of the carrying platform; forming an alloy film having a characteristic atomic ratio of a first element and a second element on the surface of the front-process structure, wherein the specific steps include: setting a characteristic temperature of the spray device to 120°C; setting a characteristic distance between the spray device and the carrying platform to 8mm; and setting a characteristic flow rate of a flow stabilizing device to 1000sccm.

[0060] In one embodiment, the process further includes: setting the temperature of the reaction chamber to be constant at 420°C; setting the gas pressure in the reaction chamber to 4 torr; setting the pulse time of the first precursor to be 4s; setting the pulse time of the second precursor to be 15s; and before the first precursor and the second precursor are introduced into the reaction chamber under the conditions of characteristic temperature, characteristic distance, and characteristic flow rate, the temperature of the first precursor is 20°C and the temperature of the second precursor is 80°C.

[0061] In one embodiment, the step of introducing a first precursor to a second precursor into the reaction chamber under conditions of a characteristic temperature, a characteristic distance, and a characteristic flow rate includes: performing a plurality of consecutive sub-cycles of deposition, wherein any one of the sub-cycles is used to deposit an atomic layer film; in any one of the sub-cycles of deposition, the first precursor and the second precursor are alternately introduced into the reaction chamber under conditions of the characteristic temperature, the characteristic distance, and the characteristic flow rate, and a purge step of a purge gas is performed between the introduction of different precursors. Specifically, the purge time for the first reaction precursor is 10 seconds; the purge time for the second reaction precursor is 20 seconds; and during the purge process for the first reaction precursor and the second reaction precursor, the volume flow rate of the purge gas used is 1000 seem, and the purge gas used includes an inert gas, such as nitrogen.

[0062] The first precursor and the second precursor are introduced into the reaction chamber and carried into the reaction chamber by a carrier gas. The carrier gas includes an inert gas, such as nitrogen. The flow rate of the carrier gas is 1000 sccm. The carrier gas is nitrogen with a purity of 99.9999%. The first precursor is a titanium-containing precursor and the second precursor is an aluminum-containing precursor. For example, the first precursor is titanium chloride and the second precursor is triethylaluminum. The atomic activity of aluminum atoms is higher than that of titanium atoms. The ratio of titanium to aluminum elements in the formed alloy film is 0.3. The effective work function of the metal gate structure formed by the alloy film is 4.46 eV.

[0063] When adjusting the characteristic atomic ratio of the first element to the second element in the alloy film, the characteristic atomic ratio can be adjusted by adjusting the characteristic temperature. For example, the characteristic atomic ratio of the first element to the second element is 0.6-1, and the characteristic temperature range is 120°C-220°C. The characteristic temperature has different effects on the adsorption capacity of atoms of different elements. In this embodiment, after increasing the characteristic temperature, the atomic activity of aluminum atoms is greater than that of titanium atoms. Therefore, increasing the characteristic temperature makes aluminum atoms more easily adsorbed, and the content of aluminum atoms in the resulting alloy film is greater than that of titanium atoms. Therefore, the characteristic atomic ratio of titanium to aluminum increases with increasing characteristic temperature.

[0064] Example 2

[0065] This embodiment provides a method for preparing an alloy thin film. This method differs from the method for preparing an alloy thin film provided in Example 1 in that the characteristic distance between the spraying device and the supporting platform is set at 6 mm. The ratio of titanium to aluminum in the resulting alloy thin film is 1.2, and the effective work function of the metal gate structure formed by the alloy thin film is 4.51 eV.

[0066] When adjusting the characteristic atomic ratio of the first element to the second element in the alloy film, this can be done by adjusting the characteristic distance between the spray device and the carrier platform. For example, the characteristic atomic ratio of the first element to the second element is 0.2-0.6, and the characteristic distance between the spray device and the carrier platform is 2 mm-15 mm. In this embodiment, because the atomic radius of titanium atoms (1.45 angstroms) is larger than that of aluminum atoms (1.43 angstroms), the characteristic distance has different effects on the adsorption capacity of aluminum and titanium atoms. Therefore, the characteristic atomic ratio of titanium to aluminum decreases as the characteristic distance between the spray device and the carrier platform increases.

[0067] Example 3

[0068] This embodiment provides a method for fabricating an alloy thin film. This method differs from the method for fabricating an alloy thin film provided in Example 1 in that the characteristic flow rate of the current stabilization device is 800 sccm. The ratio of titanium to aluminum in the resulting alloy thin film is 0.6, and the effective work function of the metal gate structure formed by the alloy thin film is 4.48 eV.

[0069] The characteristic atomic ratio of the first element to the second element in the alloy film can be adjusted by adjusting the characteristic flow rate of the balancing gas introduced into the reaction chamber. For example, if the characteristic atomic ratio of the first element to the second element is 0.7-0.9, the characteristic flow rate of the flow stabilization device ranges from 500 sccm to 1100 sccm, which is generally similar to the volumetric flow rate of the purge gas. In this embodiment, the characteristic flow rate of the flow stabilization device can affect the desorption capacity of titanium and aluminum atoms. Therefore, the characteristic atomic ratio of titanium to aluminum decreases as the characteristic flow rate increases.

[0070] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will readily appreciate that other variations or modifications based on the above descriptions are possible. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A method for preparing an alloy film, wherein the alloy film comprises a first element to an Mth element, characterized in that: include: Providing a reaction chamber, wherein a spray device and a carrying platform are arranged in the reaction chamber; Placing a previous process structure on the surface of the carrying platform; An alloy film having a characteristic atomic ratio of a first element to an Mth element is formed on the surface of the front process structure, the steps comprising: setting the spray device to have a characteristic temperature; setting a characteristic distance between the spray device and the carrying platform; setting a flow stabilizing device to have a characteristic flow rate; introducing a first precursor to an Mth precursor into the reaction chamber through the spray device under the conditions of the characteristic temperature, the characteristic distance, and the characteristic flow rate, wherein M is an integer greater than or equal to 2, any mth precursor includes the mth element, and m is an integer greater than or equal to 1 and less than or equal to M; The characteristic atomic ratio is adjusted by adjusting the values ​​of any one or several parameters among the characteristic temperature, the characteristic distance and the characteristic flow rate.

2. The method for preparing the alloy thin film according to claim 1, characterized in that: For any m1th element and m2th element among the first element to the Mth element, the two have different atomic activities, m1 and m2 are both integers greater than or equal to 1 and less than or equal to M, and m1 is not equal to m2; The characteristic atomic ratio of the m1th element to the m2th element increases with the increase of the characteristic temperature; the characteristic atomic ratio of the m1th element to the m2th element decreases with the increase of the characteristic distance; the characteristic atomic ratio of the m1th element to the m2th element decreases with the increase of the characteristic flow rate.

3. The method for preparing the alloy thin film according to claim 1, characterized in that: M is equal to 2; the alloy film includes titanium and aluminum; the process of introducing the first precursor to the Mth precursor into the reaction chamber under the conditions of the characteristic temperature, the characteristic distance, and the characteristic flow rate is: introducing a titanium-containing precursor and an aluminum-containing precursor into the reaction chamber under the conditions of the characteristic temperature, the characteristic distance, and the characteristic flow rate; By adjusting the characteristic temperature, the characteristic atomic ratio of titanium element and aluminum element in the alloy film is adjusted; and / or, adjusting the characteristic atomic ratio of titanium and aluminum in the alloy film by adjusting the characteristic distance; And / or, the characteristic atomic ratio of titanium element and aluminum element in the alloy film is adjusted by adjusting the characteristic flow rate.

4. The method for preparing the alloy thin film according to claim 3, characterized in that: The step of adjusting the characteristic atomic ratio of titanium and aluminum in the alloy film by adjusting the characteristic temperature includes: increasing the characteristic atomic ratio of titanium and aluminum in the alloy film by raising the characteristic temperature, or reducing the characteristic atomic ratio of titanium and aluminum in the alloy film by lowering the characteristic temperature.

5. The method for preparing the alloy thin film according to claim 3, characterized in that: The step of adjusting the characteristic atomic ratio of titanium and aluminum in the alloy film by adjusting the characteristic distance includes: reducing the characteristic atomic ratio of titanium and aluminum in the alloy film by increasing the characteristic distance, or increasing the characteristic atomic ratio of titanium and aluminum in the alloy film by decreasing the characteristic distance.

6. The method for preparing the alloy thin film according to claim 3, characterized in that: Adjusting the characteristic atomic ratio of titanium and aluminum in the alloy film by adjusting the characteristic flow includes: reducing the characteristic atomic ratio of titanium and aluminum in the alloy film by increasing the characteristic flow, or increasing the characteristic atomic ratio of titanium and aluminum in the alloy film by reducing the characteristic flow.

7. The method for preparing an alloy thin film according to claim 1, characterized in that: When forming different alloy films with different characteristic atomic ratios, the flow rate of any m-th precursor remains unchanged, the temperature of the reaction chamber remains unchanged, the pulse time of any m-th precursor remains unchanged, and the carrier gas flow rate when the m-th precursor is introduced into the reaction chamber remains unchanged.

8. The method for preparing an alloy thin film according to claim 1, characterized in that: The process of forming an alloy film having a characteristic atomic ratio of the first element to the Mth element on the surface of the previous process structure includes an atomic layer deposition process; The step of introducing the first precursor to the Mth precursor into the reaction chamber under the conditions of the characteristic temperature, the characteristic distance and the characteristic flow rate comprises: performing a plurality of continuous sub-cycle depositions, wherein any one of the sub-cycle depositions is used to deposit an atomic layer film; In any sub-cycle deposition, the first precursor to the Mth precursor are alternately introduced into the reaction chamber under the conditions of the characteristic temperature, the characteristic distance, and the characteristic flow rate, and a purge step is performed between the steps of introducing different precursors.

9. The method for preparing an alloy thin film according to claim 1, characterized in that: The characteristic temperature range is: 120°C-220°C; The characteristic distance has a value range of 2 mm to 15 mm. The characteristic flow rate has a value range of 500 sccm-1100 sccm.

10. The method for preparing an alloy thin film according to claim 3, characterized in that: The temperature of the titanium-containing precursor before entering the spraying device is room temperature, and the temperature of the aluminum-containing precursor before entering the spraying device is 40° C.-115° C.

11. The method for preparing an alloy thin film according to claim 1, characterized in that: The reaction chamber includes a first sub-reaction chamber and a second sub-reaction chamber located in the first sub-reaction chamber, a heating device is provided between the first sub-reaction chamber and the second sub-reaction chamber, and the carrying platform is located in the second sub-reaction chamber.

12. The method for preparing an alloy thin film according to claim 1, characterized in that: The alloy film is a metal gate layer; The front process structure includes a substrate layer, a high dielectric gate dielectric layer located on one side of the substrate layer, and a barrier layer located on a side of the high dielectric gate dielectric layer away from the substrate layer; The metal gate layer is located on a surface of the barrier layer facing away from the substrate layer.

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