Method and apparatus for forming metal nitride film containing oxygen

Abstract

To provide a technique capable of highly accurately adjusting stress of a film when forming a metal nitride film containing oxygen.SOLUTION: In forming a metal nitride film containing oxygen, in a first step, a metal nitride layer is formed on a substrate by performing a first cycle in which a raw material gas containing metal and a nitriding gas are sequentially supplied to the substrate once in one cycle. And forming a metal oxynitride layer on the substrate by performing a second cycle in which each of the raw material gas and the nitriding gas is supplied once and the raw material gas, the nitriding gas, and the oxidizing gas are sequentially supplied to the substrate. The first step and the second step are alternately repeated to stack the metal nitride layer and the metal oxynitride layer to form a metal nitride film containing oxygen.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a method and apparatus for forming a metal nitride film containing oxygen. [Background technology]

[0002] In semiconductor manufacturing equipment, there is a process for depositing a metal nitride film, such as a titanium nitride (TiN) film, on a substrate. TiN films are known to have high stress, and there is a concern that the substrate may be subjected to large stress during subsequent heat treatments and other processes. Patent Document 1 proposes supplying an oxidizing agent to a TiN film to form a TiON film, and describes that stress can be reduced by setting the O content of the TiON film to 50 at % or more. Patent Document 2 describes a laminated film in which a TiON film with an oxygen content of 50 at % or more and a TiN film are stacked with the TiON film underneath. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-14477 [Patent Document 2] Japanese Patent Application Laid-Open No. 2018-80349 Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides a technique that enables precise adjustment of the stress of a metal nitride film that contains oxygen when the film is formed. [Means for solving the problem]

[0005] The present disclosure provides: a first cycle in which a metal-containing source gas and a nitriding gas are sequentially supplied to a substrate once each in one cycle, thereby forming a metal nitride layer on the substrate; a second cycle in which the source gas and the nitriding gas are each supplied once in one cycle, and the source gas, the nitriding gas, and the oxidizing gas are supplied to the substrate in this order, thereby forming a metal oxynitride layer on the substrate; a step of alternately repeating one of the first step and the second step to form a film by stacking the metal nitride layer and the metal oxynitride layer; The present invention provides a method for forming a metal nitride film containing oxygen, comprising: [Effects of the Invention]

[0006] According to the present disclosure, when forming a metal nitride film containing oxygen, the stress of the film can be adjusted with high precision. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a longitudinal sectional view showing a first configuration example of a metal nitride film containing oxygen. [Figure 2] 1 is a vertical cross-sectional view showing an embodiment of a film forming apparatus. [Figure 3] 4 is a timing chart showing a first embodiment of a film forming method. [Figure 4] FIG. 2 is a longitudinal cross-sectional view showing a metal nitride film containing oxygen. [Figure 5] 10 is a timing chart showing a first modified example of the film forming method. [Figure 6] 10 is a timing chart showing a second modified example of the film forming method. [Figure 7] FIG. 10 is a longitudinal sectional view showing a second configuration example of a metal nitride film containing oxygen. [Figure 8] FIG. 10 is a characteristic diagram showing the results of evaluation test 1. [Figure 9] FIG. 10 is a characteristic diagram showing the results of evaluation test 2. DETAILED DESCRIPTION OF THE INVENTION

[0008] The oxygen-containing metal nitride film of the present disclosure will be described using an example in which the metal is titanium (Ti), in which case the metal nitride film is a titanium nitride film (TiN film). FIG. 1 shows a first structural example of an oxygen-containing TiN film 1 (hereinafter referred to as "TiN film 1") according to the present disclosure. Incidentally, "containing oxygen (O)" here does not mean containing oxygen that is inevitably mixed in. The TiN film 1 is configured by vertically stacking a TiN layer 11, which is a metal nitride layer, and a TiON layer 12, which is a metal oxynitride layer. In this example, the TiN layer 11 is placed on the bottom of a substrate, such as a semiconductor wafer W (hereinafter referred to as "wafer W"), and the TiON layer 12 is stacked on top of the TiN layer 11. If a stacked film including the TiN layer 11 and the TiON layer 12 is defined as a TiN unit layer 10, the TiN film 1 is configured by stacking multiple TiN unit layers 10, four in this example.

[0009] Such a TiN film 1 is used as a sacrificial film (hard mask) during etching in the manufacturing process of, for example, 3D NAND flash memory. The reason for forming the TiN film so as to contain oxygen by forming the TiON layer 12 as described above will be explained below. As mentioned above, the TiN layer 11 (i.e., a TiN film that does not contain oxygen) has a large tensile stress, which may cause defects in the structure of the substrate or each film on the substrate, such as warping of the substrate during heat treatment.

[0010] On the other hand, as oxygen is added to the TiN film and the amount of oxygen added increases, the tensile stress decreases while the compressive stress tends to increase. For this reason, by stacking the TiN layer 11 and the TiON layer 12, the stress in the TiN layer 11 and the stress in the TiON layer 12 are balanced, and the TiN film 1 is formed so that the film as a whole has an appropriate stress.

[0011] Incidentally, the aforementioned Patent Document 2 discloses a TiN film formed on a substrate in such a way that TiN layers (TiN films) and TiON layers (TiON films) are alternately laminated, similar to the TiN film 1. In Patent Document 2, when forming the TiON layer on the substrate, the TiN layer is formed by ALD (Atomic Layer Deposition), which repeats a cycle of supplying TiCl4 gas and NH3 gas, and then the TiN layer is oxidized by supplying O2 gas as an oxidizer. In other words, after the TiN layer becomes relatively thick through repeated cycles, oxidation by supplying O2 gas is performed.

[0012] However, with this method of forming a TiON layer, the amount of oxygen that penetrates into the TiN layer varies depending on the processing conditions when supplying O2 gas, making it difficult to control the oxygen content in the TiON layer. Therefore, it is desirable to more precisely control the oxygen content in the TiN film and adjust the stress of the TiN film as described above. Furthermore, when laminating a TiN film on another film, it is preferable to be able to control the stress of the TiN film 1 over a wide range in order to balance the stress of the TiN film with the stress of the other film and prevent problems such as the warpage of the substrate described above. The method for forming the TiN film 1 of this embodiment meets this requirement.

[0013] <Film forming equipment> Next, one embodiment of a film formation apparatus 2 for performing the film formation process of the TiN film 1 described above will be described with reference to Fig. 2. The film formation apparatus 2 in this example is configured to form the TiN film 1 by successively forming a TiN layer 11 and a TiON layer 12 on a wafer W by ALD. As shown in this figure, the film forming apparatus 2 includes a substantially cylindrical processing chamber 21 that stores and processes a wafer W, and a mounting table 3 on which the wafer W is placed is provided inside the processing chamber 21. The mounting table 3 is configured, for example, in a flat cylindrical shape and includes a built-in heater 31. A support part 32 extending downward is provided at the center of the underside of the mounting table 3.

[0014] In this example, the processing vessel 21 has a bottom wall 22 with a central portion thereof protruding downward to form an exhaust chamber 23, and the lower end of the support portion 32 is connected to the bottom of the exhaust chamber 23. An exhaust mechanism 25 is connected to the side wall of the exhaust chamber 23 via an exhaust path 24, and the exhaust mechanism 25 includes a vacuum pump, a valve for opening and closing the exhaust path 24, and the like. A shower head 4 is disposed in a region facing the mounting table 3 within the processing chamber 21. The shower head 4 is configured to discharge gas in a shower-like manner toward the wafer W placed on the mounting table 3 from a number of discharge ports 41 formed on the lower surface thereof.

[0015] Furthermore, a supply path 42 for supplying gas to the shower head 4 is formed in the processing vessel 11, and a base end of the supply path 42 is connected to a gas supply unit 5 via a supply pipe 43. The gas supply unit 5 is configured to supply a source gas containing a metal, a nitriding gas, and an oxidizing gas into the processing vessel 21. For example, the base end of the supply pipe 43 branches into supply pipes 431, 432, 433, and 434, which are connected to supply sources 51, 52, 53, and 54 of the source gas, nitriding gas, purge gas, and oxidizing gas, respectively. Furthermore, the supply pipes 431, 432, 433, and 434 are equipped with valves V1, V2, V3, and V4 that open and close the respective flow paths, gas flow rate adjusters M1, M2, M3, and M4, etc.

[0016] In this example, titanium tetrachloride (TiCl4) gas is used as the metal-containing source gas, ammonia (NH3) gas is used as the nitriding gas, nitrogen (N2) gas is used as the purge gas, and oxygen (O2) gas is used as the oxidizing gas. These gases are supplied into the processing chamber 21 via the shower head 4 at preset timings based on control signals from the control unit 100 (described later).

[0017] Although not shown, a gas supply pipe is provided in addition to the purge gas supply pipe 433, which is provided with the valve V3 and the flow rate adjuster M3, for supplying N2 gas into the processing vessel 21 via the shower head 4. This N2 gas is constantly supplied into the processing vessel 21 during processing of the wafer W, and acts as a carrier gas for each of the TiCl4 gas, NH3 gas, and O2 gas, and also contributes to purging the TiCl4 gas and NH3 gas from the processing vessel 21.

[0018] In addition, when the supply of TiCl4 gas and the supply of NH3 gas are repeated in the second step described later, O2 gas is supplied between the supply of one of TiCl4 gas and NH3 gas and the supply of the other, thereby acting as a purge gas for one of the gases. However, unless otherwise specified, the purge gas refers to the N2 gas supplied from the supply source 53 into the processing vessel 21 via the supply pipes 433 and 433.

[0019] Furthermore, a transfer port 26 is formed in the sidewall of the processing vessel 21, through which the wafer W is loaded into and unloaded from the processing vessel 21, and this transfer port 26 is configured to be freely opened and closed by a gate valve 27. Furthermore, the processing vessel 21 is provided with transfer pins 28 that can be freely raised and lowered by a lifting mechanism 29 for transferring the wafer W between an external transfer mechanism (not shown) and the mounting table 3.

[0020] The substrate processing apparatus 1 having the above-described configuration includes a control unit 100. The control unit 100 is configured with a computer including a storage unit, a memory, and a CPU that stores a program. The program is configured to output control signals from the control unit 100 to each part of the film forming apparatus 2 to perform control necessary for processing the wafer W. Such a program is stored in a storage unit of a computer, such as a flexible disk, compact disk, hard disk, MO (magneto-optical disk), or nonvolatile memory, and is read from the storage unit and installed in the control unit 100. The start and stop of supply of the raw material gas (TiCl), nitriding gas (NH), oxidizing gas (O), and purge gas (N) from the gas supply unit 5, as well as adjustment of the flow rates, are also performed based on control signals from the control unit 100.

[0021] <Film formation method> 3, an example of a film formation method performed in the film formation apparatus 2 will be described. First, a wafer W having a predetermined film structure formed thereon is loaded into the processing chamber 21 through the transfer port 26 and placed on the mounting table 3.

[0022] <First Process (First Step)> Next, N2 gas is supplied into the processing chamber 21 while being evacuated through the exhaust path 24, and the pressure inside the processing chamber 21 is adjusted to a predetermined pressure, and the wafer W on the mounting table 3 is heated to a predetermined temperature by the heater 31. Then, TiCl4 gas is supplied from the gas supply unit 5 into the processing chamber 21 via the shower head 4 to adsorb the TiCl4 gas onto the surface of the wafer W (step S1). After supplying the TiCl4 gas for a predetermined period, the supply of the TiCl4 gas is stopped, and purging is performed with N2 gas for a predetermined period (step S2).

[0023] Next, NH3 gas is supplied from the gas supply unit 5 into the processing vessel 21 to react with TiCl4 adsorbed on the wafer surface to form TiN (step S3). After supplying NH3 gas for a preset period, the supply of NH3 gas is stopped and purging is performed with N2 gas for a preset period (step S4). In this way, a first cycle is executed in which TiCl4 gas and NH3 gas are sequentially supplied once each to the wafer W in the order of TiCl4 gas → purge gas → NH3 gas → purge gas. A first process (first step) is executed in which this first cycle (steps S1 to S4) is repeated X times, which is a preset number of times, to form a TiN layer 11 having a set thickness.

[0024] <Second process (second step)> After the first step described above is completed, the second step is carried out. In this second step, first, TiCl4 gas, which is the same source gas as in the first step, is supplied into the processing vessel 21, and the TiCl4 gas is adsorbed onto the surface of the wafer W (step S5). After the TiCl4 gas is supplied for a predetermined period, the supply of TiCl4 gas is stopped. Next, O2 gas is supplied into the processing vessel 21 for a predetermined period, and the supply of O2 gas is stopped (step S6). As a result, the TiCl4 gas that is not adsorbed onto the wafer W is purged from the processing vessel 21 by the O2 gas, and the wafer surface is oxidized.

[0025] Next, NH3 gas, which is the same nitriding gas as in the first step, is supplied into the processing chamber 21 and reacts with the oxidized TiCl4 on the wafer surface to form a TiON layer 12 (step S7). Then, after the NH3 gas is supplied for a preset period, the supply of the NH3 gas is stopped. Next, O gas is supplied into the processing vessel 21 for a preset period of time, and then the supply of O gas is stopped (step S8). As a result, NH gas that has not reacted with the oxidized TiCl on the wafer surface is purged from the processing vessel 21 by the O gas, and the oxidation of the TiON layer 12 progresses.

[0026] In this way, a second cycle is executed in which the gases are sequentially supplied to the wafer W in the order of TiCl4 gas → O2 gas → NH3 gas → O2 gas. Then, a second process (second step) is executed in which this second cycle (steps S5 to S8) is repeated a predetermined number of times (Y times) to form a TiON layer 12 having a set thickness. As described above, the second cycle is a cycle in which TiCl4 gas and NH3 gas are supplied once each, and TiCl4 gas, NH3 gas, and O2 gas are supplied in sequence, and O2 gas is supplied each time a layer of TiN is formed by the reaction between TiCl4 gas and NH3 gas. As a result, the thin TiN film is oxidized by the O2 gas, ensuring that the oxidation of TiN proceeds reliably.

[0027] By performing the first and second steps described above once each, a TiN unit layer 10 is formed, in which a TiN layer 11 and a TiON layer 12 are stacked. In this way, by alternately repeating the first and second steps a predetermined number of times, Z times, a TiN film 1 is formed in which the TiN unit layers 10 are stacked in Z layers. Here, taking an example of the TiN film 1 used as a sacrificial film, the thickness of the TiN film 1 is set to, for example, 50 nm to 200 nm, and the thickness of the TiON layer 12 in the TiN unit layer 10 is set to, for example, 1 to 50 nm.

[0028] As described above, when the first and second processes are performed, the next step S is performed upon completion of each of steps S1 to S8 included in these processes. Therefore, when the first and second processes are performed in sequence, the second process starts upon completion of the first process. Specifically, the second process starts upon completion of step S4 of the first process. Then, when the first and second processes are repeated, the first process resumes upon completion of the second process. Specifically, the first process starts upon completion of step S8 of the second process. Note that a process of purging the processing vessel 21 by supplying only N2 gas may be performed between the completion of step S8 and step S1 of the first process.

[0029] In this way, the TiN film 1 is formed in which the TiN layers 11 and the TiON layers 12 are alternately laminated in this order from the bottom. After the film formation process of the TiN film 1 is completed, the inside of the processing chamber 21 is purged with N2 gas, for example. Then, the gate valve 26 is opened, and the wafer W is unloaded from the transfer port 25.

[0030] In the above processing example, the temperature of the wafer W and the pressure inside the processing chamber 21 are the same in the first process and the second process, but they may be different. However, if the temperature and pressure are different in the first process and the second process, the next process cannot be performed from the end of one process until the temperature and pressure adjustment is completed, which may result in a decrease in throughput, so it is preferable that the temperature and pressure are the same in the first process and the second process.

[0031] Here, examples of the treatment conditions for the first step and the second step are as follows. <Processing conditions for the first step> TiCl4 gas supply time (time of step S1): 0.03 to 5.0 seconds NH3 gas supply time (time of step S3): 0.03 to 5.0 seconds Pressure inside the processing vessel 21: 100 to 3000 Pa Processing temperature (temperature of mounting table 3): 300 to 650°C <Processing conditions for the second step> TiCl4 gas supply time (time of step S5): 0.03 to 5.0 seconds NH3 gas supply time (time in step S7): 0.03 to 5.0 seconds O2 gas supply time in steps S6 and S8: 0.03 to 5.0 seconds Pressure inside the processing vessel 21: 100 to 3000 Pa Processing temperature (temperature of mounting table 3): 300 to 650°C

[0032] In such a TiN film 1, the thickness of the TiN layer 11 constituting the TiN unit layer 10 is determined by the number of times (X times) the first cycle is performed in the first step. Also, the thickness of the TiON layer 12 constituting the TiN unit layer 10 is determined by the number of times (Y times) the second cycle is performed in the second step. And the thickness of the TiN film 1 in which the TiN unit layers 10 are stacked in Z stages is determined by the number of times (Z times) the first step and the second step are repeated.

[0033] Figure 4 is a schematic diagram showing TiN films 1 formed with the same thickness by varying the combination of X, Y, and Z. The left side of Figure 4 shows TiN film 1A, where the number of first cycles X is set to 5 and the number of second cycles Y is set to 1. The right side of Figure 4 shows TiN film 1B, where the number of first cycles X is set to 20 and the number of second cycles Y is set to 1. As shown in this figure, TiN film 1A, which has a smaller number of first cycles X, has a thinner TiN layer 11. Therefore, for the same TiN film thickness, TiN film 1A has a larger number of repetitions Z of the first and second steps, resulting in a larger total thickness of the TiON layer 12 and a higher oxygen concentration in the film compared to TiN film 1B, which has a larger number of first cycles X. In this way, the oxygen concentration in TiN film 1 can be controlled by adjusting the combination of X, Y, and Z.

[0034] As described above, the stress of the TiN film 1 varies depending on the oxygen concentration. Therefore, even if the TiN films 1A and 1B have the same thickness, the stress of the TiN films varies depending on the ratio of the total thickness of the TiN layers 11 to the total thickness of the TiON layers 12 (the composition ratio of the TiN layers 11 and the TiON layers 12 in the TiN film 1). That is, according to this method, by appropriately setting the parameters X, Y, and Z that determine the number of cycle repetitions, a TiN film 1 having a desired thickness and appropriate stress can be formed on the wafer W on which the film is to be formed. Note that the values ​​of X, Y, and Z in the description of FIG. 4 are merely examples for ease of understanding and are not limited to these values; X, Y, and Z can each be set to a value within the ranges described above.

[0035] Note that multiple combinations of X, Y, and Z may be stored in the memory of the control unit 100 of the film forming apparatus 2, for example. Specifically, the values ​​of X, Y, and Z (referred to as recipe A) for forming the TiN film 1A of FIG. 4 and the values ​​of X, Y, and Z (referred to as recipe B) for forming the TiN film 1B of FIG. 4 may be stored in the memory. When information about the lot of wafers W to be transferred to the film forming apparatus 2 (e.g., information about the type of film already formed on the wafers W) is transmitted from a host computer of a factory where the film forming apparatus 2 is installed to the control unit 100, the control unit 100 selects one of recipes A and B based on the information and executes the process. This recipe selection may be performed, for example, based on a database that associates the above information with recipes and that database is stored in advance in the memory of the control unit 100. In other words, the film forming apparatus 2 may be configured so that a recipe is automatically selected and film formation is performed according to the lot of wafers W so that the TiN film 1 to be formed has an appropriate stress.

[0036] As described above, the number of first cycles X and the number of second cycles Y can be freely set depending on the oxygen concentration of the target TiN film 1. However, if an excessive amount of oxygen is contained, the properties of the TiN film (conductivity, barrier properties, etching resistance, etc.) will be significantly different from those of a TiN film that does not contain oxygen. Therefore, in order to ensure the properties of the TiN film 1, it is preferable to set the number of first cycles X to be greater than the number of second cycles Y.

[0037] The first and second cycles have been described as being repeatedly performed. That is, X and Y have been described as integers of 2 or greater, but either or both of X and Y may be 1. Therefore, the first and / or second cycles do not have to be repeatedly performed, and one of the first and second cycles may be performed once before starting the other cycle. Note that Z is an integer of 2 or greater. As described above, the TiN layer 11 and the TiON layer 12 are alternately and repeatedly stacked. This allows oxygen to be introduced so that it is dispersed throughout the thickness of the TiN film 1, adjusting the stress of the TiN film 1.

[0038] The number of first cycles X and the number of second cycles Y may be changed during the formation of the TiN film 1. Taking the first cycle as an example, the number of first cycles X for the first TiN unit layer 10 may be 5, and the number of first cycles X for the second TiN unit layer 10 may be 3, so that the film thicknesses of the TiN layers 11 and TiON layers 12 constituting the TiN unit film 10 may be changed for each TiN unit layer 10.

[0039] According to this embodiment, the oxygen-containing TiN film 1 is formed by stacking the TiN layer 11 and the TiON layer 12. In this case, by adjusting the composition ratio of the TiN layer 11 and the TiON layer 12 that constitute the TiN film 1, the oxygen concentration of the TiN film 1 can be adjusted, and the stress of the film can be adjusted with high precision.

[0040] As described above, in the second cycle, O gas is supplied each time a TiN layer is formed, allowing the formation of a thin TiON layer 12. This allows the composition ratio of the TiN layer 11 and the TiON layer 12 to be adjusted with high precision, and accordingly, the stress of the TiN film 1 can be controlled with high precision over a wide range. Furthermore, since the TiN film 1 is formed by alternately stacking the TiN layers 11 and the TiON layers 12 in multiple stages, the TiON layers 12 are arranged in multiple stages in the thickness direction of the TiN film 1, ensuring good uniformity of the oxygen concentration in the thickness direction of the TiN film 1.

[0041] Next, a modification of the above embodiment will be described. <First Modification> In the film forming method of the present disclosure, the second cycle may be a cycle in which TiCl4 gas and NH3 gas are supplied to the wafer W, and then O2 gas is supplied, as shown in the timing chart of Fig. 5. In this example, the second cycle is performed by supplying TiCl4 gas, N2 gas as a purge gas, NH3 gas, and O2 gas into the processing chamber 21 in this order. The second cycle is similar to the above-described embodiment except that O2 gas is not supplied after the supply of TiCl4 gas, and purging is performed using only N2 gas. In the second cycle of this example, after the supply of NH3 gas, O2 gas is supplied together with N2 gas, so that the formed TiN is quickly oxidized and a TiON layer 12 is formed.

[0042] Incidentally, when oxidizing TiN on the wafer W to form the TiON layer 12, the O gas supplied in step S8 after the supply of NH gas plays a significant role. Experiments have confirmed that supplying O gas only in step S6 of steps S6 and S8 (i.e., when the cycle is performed as TiCl gas → O gas → NH gas → purge gas) results in low oxidizing properties for TiN. Therefore, although O gas may be supplied only in step S6 of steps S6 and S8, it is preferable to supply O gas at least in step S8, as shown in the timing charts of FIGS. 3 and 5. To ensure the oxidation of TiN and the introduction of oxygen into the TiN film to adjust stress, it is preferable to supply O gas in each of steps S6 and S8, as shown in the timing chart of FIG. 3.

[0043] <Second Modification> Furthermore, although the first step was performed before the second step in the first embodiment, the second step may be performed before the first step to form a TiN film. A timing chart of this example is shown in Figure 6. In this way, after the second step in which the second cycle is performed Y times, the first step in which the first cycle is performed X times may be performed, and the second step and the first step may be repeated Z times to form a TiN film.

[0044] In this case, as shown in Figure 7, a TiN unit layer 13 is formed by stacking a TiON layer 12 and a TiN layer 11 in this order from the bottom up, and the TiN unit layers 13 are stacked in a Z-stage configuration to form a TiN film 1C. Therefore, the TiN film 1C in this example is formed by alternately stacking the TiON layer 12 and the TiN layer 11 in this order from the bottom up. In this way, either the TiN layer 11 or the TiON layer 12 constituting the TiN films 1 and 1C on the upper surface of the wafer W can be formed first. Also in this example, the second cycle can be performed in the following order: TiCl4 gas supply → N2 gas purge → NH3 gas supply → O2 gas supply.

[0045] <Example> <Evaluation Test 1> 3, the first cycle was performed X times and the second cycle was performed Y times, and the first and second steps were repeated to form the TiN film 1 with a total thickness of 100 nm. The number of first cycles, X, was 20, 5, 2, and 0, and the number of second cycles, Y, was 1.

[0046] In this way, TiN films 1 with different composition ratios of the TiN layer 11 and the TiON layer 12 were formed, and the oxygen concentration of each TiN film 1 was measured by X-ray photoelectron spectroscopy (XPS). Tests conducted with the number of first cycles X set to 20, 5, 2, and 0 were designated Example 1, Example 2, Example 3, and Comparative Example 1, respectively. As described above, the TiN film 1 includes the TiN layer 11 and the TiON layer 12. Therefore, a film in which X is set to 0 and does not include the TiN layer 11, as in Comparative Example 1, is not TiN film 1, but for the sake of convenience, it will be referred to as TiN film 1 in the description of this evaluation test. In Evaluation Test 2 described below, a TiN film in which Y is set to 0 and does not include the TiON layer 12 (Comparative Example 2) will also be referred to as TiN film 1 only in the description of the evaluation test.

[0047] The first and second steps were carried out under the following treatment conditions. <Processing conditions for the first step> TiCl4 gas supply time (time of step S1): 0.05 seconds NH3 gas supply time (time of step S3): 0.3 seconds Purge time in step S2: 0.2 seconds Purge time in step S4: 0.3 seconds Pressure inside the processing vessel 21: 400 to 600 Pa Processing temperature (temperature of mounting table 3): 400°C <Processing conditions for the second step> TiCl4 gas supply time (time in step S5): 0.05 seconds NH3 gas supply time (time in step S7): 0.3 seconds O2 gas supply time (time in step S6): 0.2 seconds O2 gas supply time (time in step S8): 0.3 seconds Pressure inside the processing vessel 21: 400 to 600 Pa Processing temperature (temperature of mounting table 3): 400°C

[0048] The results are shown in Figure 8. In the figure, the horizontal axis represents the composition ratio of the TiN layer 11 to the TiON layer 12 (number of first cycles X: number of second cycles Y), and the vertical axis represents the oxygen concentration [%]. As shown in the graph, the oxygen concentration of the TiN film 1 was in the order Comparative Example 1 > Example 3 > Example 2 > Example 1. Therefore, the larger the value of X / Y, the lower the oxygen concentration in the TiN film 1. This evaluation test 1 confirmed that the oxygen concentration of the formed TiN film 1 could be controlled by adjusting the number of first cycles X and the number of second cycles Y.

[0049] <Evaluation Test 2> The stress of the TiN films 1 of Examples 1 to 3, Comparative Example 1, and Comparative Example 2 (X:Y=1:0) obtained in Evaluation Test 1 was measured using a specific measuring device. The results are shown in Figure 9. In the figure, the horizontal axis represents oxygen concentration [%] and the vertical axis represents stress [GPa], with Example 1 (X:Y=20:1) plotted as square, Example 2 (X:Y=5:1) as triangle, Example 3 (X:Y=2:1) ​​as circle, Comparative Example 1 (X:Y=0:1) as square, and Comparative Example 2 as circle.

[0050] 9, the stress increases in the order of Comparative Example 2 > Example 1 > Example 2 > Example 3 > Comparative Example 1, with Comparative Example 2, in which the TiON layer 12 was not formed, showing approximately +1.5 GPa, and Comparative Example 1, in which the TiN layer 11 was not formed, showing approximately -0.5 GPa. Considering the results of Evaluation Test 1, the oxygen concentration in the TiN film 1 increases as X / Y decreases. As the oxygen concentration increases, the stress in the TiN film 1 decreases, and it can be seen that the stress changes from tensile stress to compressive stress.

[0051] From the results of Evaluation Test 2 above, it is expected that when forming the TiN film 1 including the TiN layer 11 and the TiON layer 12 as described in the embodiment, the stress can be changed in a relatively wide range of about -0.5 GPa to about +1.5 GPa by adjusting the numbers X and Y of the first and second cycles, respectively. Since the stress can be changed between values ​​higher and lower than 0 Pa, it is estimated that the stress of the TiN film 11 can also be changed between tensile stress and compressive stress. As described above, Evaluation Tests 1 and 2 confirmed the effects of the present technology described in the embodiment.

[0052] In the above, the use of the oxygen-containing TiN film formed by the method of the present disclosure is not limited to a sacrificial film, but may also be a barrier film or the like. Furthermore, the metal contained in the source gas is not limited to Ti, and other metals may be appropriately selected. Therefore, the metal nitride film formed on the wafer W is not limited to a TiN film, and other metal nitride films may be used.

[0053] Furthermore, the source gas, nitriding gas, and oxidizing gas are not limited to the above examples. When the oxygen-containing metal nitride film is a TiN film, the source gas can be, in addition to TiCl4 gas, tetra(isopropoxy)titanium (TTIP), titanium tetrabromide (TiBr4), titanium tetraiodide (TiI4), tetrakisethylmethylaminotitanium (TEMAT), tetrakisdimethylaminotitanium (TDMAT), tetrakisdiethylaminotitanium (TDEAT), etc. The nitriding gas can be, in addition to NH3, monomethylhydrazine (MMH). The oxidizing agent can be, in addition to O2 gas, oxygen-containing gases such as O3 gas, H2O, and NO2. The purge gas is not limited to N2 gas, but can be an inert gas such as argon (Ar) gas.

[0054] In the above-described embodiment, the film formation apparatus is an apparatus that performs film formation processing by ALD, but it may also be an apparatus that performs plasma ALD. Furthermore, the shape of the processing chamber and the layout of the gas supply unit in the film formation apparatus described above are examples and are not limited to the above-described configuration. So far, we have used wafers as an example of substrates, but the substrates processed in the processing chamber include, in addition to wafers, substrates used in manufacturing flat panel displays, and dummy substrates processed for the purposes of testing and setting processing parameters.

[0055] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive, and the above-described embodiments may be omitted, substituted, or modified in various ways without departing from the scope and spirit of the appended claims. [Explanation of symbols]

[0056] W wafer 1. TiN film (metal nitride film containing oxygen) 10 TiN unit layers 11 TiN layer (metal nitride layer) 12 TiON layer (metal oxynitride layer)

Claims

1. a first cycle in which a metal-containing source gas and a nitriding gas are sequentially supplied to a substrate once each in one cycle, thereby forming a metal nitride layer on the substrate; a second cycle in which the source gas and the nitriding gas are each supplied once in one cycle, and the source gas, the nitriding gas, and the oxidizing gas are supplied to the substrate in this order, thereby forming a metal oxynitride layer on the substrate; a step of alternately repeating one of the first step and the second step to form a film by stacking the metal nitride layer and the metal oxynitride layer; A method for forming a metal nitride film containing oxygen, comprising:

2. 2. The method for forming a metal nitride film containing oxygen according to claim 1, wherein the second cycle is a cycle in which the source gas and the nitriding gas are supplied to the substrate, and then the oxidizing gas is supplied to the substrate.

3. 3. The method for forming an oxygen-containing metal nitride film according to claim 2, wherein the second cycle is a cycle in which the source gas, the oxidizing gas, the nitriding gas, and the oxidizing gas are supplied to the substrate in this order.

4. The first cycle in the first step is repeatedly performed, 4. The method for forming a metal nitride film containing oxygen according to claim 3, wherein the number of times the first cycle is performed in the first step is greater than the number of times the second cycle is performed in the second step.

5. 5. The method for forming a metal nitride film containing oxygen according to claim 4, wherein said metal is titanium.

6. a processing vessel for storing the substrate; a gas supply unit that supplies a metal-containing source gas, a nitriding gas, and an oxidizing gas into the processing vessel; a control unit that outputs a control signal so that the following steps are performed: a first step of forming a metal nitride layer on the substrate by performing a first cycle in which the source gas and the nitriding gas are supplied to the substrate once each in one cycle; a second step of forming a metal oxynitride layer on the substrate by performing a second cycle in which the source gas and the nitriding gas are supplied to the substrate once each in one cycle, and the source gas, the nitriding gas, and the oxidizing gas are supplied to the substrate once each in one cycle, and the metal oxynitride layer is supplied to the substrate once each in one cycle; and a step of alternately repeating one of the first step and the second step and the other to form a film by stacking the metal nitride layer and the metal oxynitride layer. An apparatus for forming an oxygen-containing metal nitride film, comprising:

Images