Method and apparatus for forming metal nitride film containing oxygen

Abstract

In forming a metal nitride film containing oxygen, in the first step, a first cycle is performed in which a raw material gas containing a metal and a nitriding gas are sequentially supplied to the substrate once each in one cycle, thereby forming a metal nitride layer on the substrate. In the second step, a second cycle is performed in which the raw material gas, the nitriding gas and an oxidizing gas are sequentially supplied to the substrate with the raw material gas and the nitriding gas being supplied once each in one cycle, thereby forming a metal oxynitride layer on the substrate. The first step and the second step are alternately repeated, and the metal nitride layer and the metal oxynitride layer are laminated to form a metal nitride film containing oxygen.

Description

Method and apparatus for forming metal nitride film containing oxygen

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

[0002] Semiconductor manufacturing equipment includes a process for forming a metal nitride film, such as a titanium nitride film (TiN film), on a substrate. TiN films are known to have high stress, raising concerns that a large stress may be applied to the substrate during subsequent heat treatments and other processes. Patent Document 1 proposes forming a TiON film by supplying an oxidizing agent to the TiN 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 also describes a stacked film in which a TiON film with an oxygen content of 50 at% or more and a TiN film are stacked together, with the TiON film underneath.

[0003] JP 2018-14477 A JP 2018-80349 A

[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.

[0005] The present disclosure provides a method for forming an oxygen-containing metal nitride film, comprising: a first step of performing a first cycle in which a metal-containing source gas and a nitriding gas are each supplied once to a substrate in that order in one cycle, thereby forming a metal nitride layer on the substrate; a second step of performing a second cycle in which the source gas and the nitriding gas are each supplied once to the substrate in that order in one cycle, thereby forming a metal oxynitride layer on the substrate; and a step of alternately repeating one of the first step and the second step to stack the metal nitride layer and the metal oxynitride layer to form a film.

[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.

[0007] FIG. 1 is a longitudinal sectional view showing a first configuration example of a metal nitride film containing oxygen; FIG. 2 is a longitudinal sectional view showing an embodiment of a film forming apparatus; FIG. 3 is a timing chart showing a first embodiment of a film forming method; FIG. 4 is a longitudinal sectional view showing a metal nitride film containing oxygen; FIG. 5 is a timing chart showing a first modified example of the film forming method; FIG. 6 is a timing chart showing a second modified example of the film forming method; FIG. 7 is a longitudinal sectional view showing a second configuration example of a metal nitride film containing oxygen; FIG. 8 is a characteristic diagram showing the results of evaluation test 1; and FIG. 9 is a characteristic diagram showing the results of evaluation test 2.

[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 this example, the metal nitride film is a titanium nitride film (TiN film). FIG. 1 shows a first configuration example of an oxygen-containing TiN film 1 (hereinafter referred to as "TiN film 1") of the present disclosure. Note that "containing oxygen (O)" does not mean containing oxygen that is inevitably mixed in. The TiN film 1 is formed 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 formed on a substrate, for example, a semiconductor wafer W (hereinafter referred to as "wafer W"), with the TiN layer 11 facing downward and the TiON layer 12 stacked thereon. 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 formed 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, a 3D NAND flash memory. The reason why the TiN film is formed so as to contain oxygen by forming the TiON layer 12 as described above will be explained. 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 tends to decrease 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 above-mentioned Patent Document 2 discloses a TiN film formed on a substrate so 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, TiCl ４ Gas, NH ３ After forming a TiN layer by ALD (Atomic Layer Deposition), which repeats a cycle of supplying each gas, an oxidizing agent, O ２ After the thickness of the TiN layer becomes relatively large by repeating the cycle, the TiN layer is oxidized by supplying O ２ Oxidation is carried out by supplying gas.

[0012] However, this method of forming a TiON layer ２ The amount of oxygen that penetrates into the TiN layer varies depending on the processing conditions during gas supply, making it difficult to control the oxygen content contained in the TiON layer. Therefore, it is desirable to more accurately control the oxygen content in the TiN film and adjust the stress of the TiN film as described above. Furthermore, when stacking 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 defects 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 Apparatus> Next, one embodiment of a film forming apparatus 2 that performs the film forming process for the TiN film 1 described above will be described with reference to Fig. 2. The film forming apparatus 2 in this example is configured to successively form a TiN layer 11 and a TiON layer 12 on a wafer W by ALD, thereby forming the TiN film 1. As shown in this figure, the film forming apparatus 2 includes a substantially cylindrical processing chamber 21 that stores and processes the wafer W. Inside the processing chamber 21, a mounting table 3 on which the wafer W is placed is provided. The mounting table 3 is configured, for example, in a flat cylindrical shape and includes a built-in heater 31. A support portion 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 and a valve for opening and closing the exhaust path 24. A shower head 4 is disposed in an area facing the mounting table 3 within the processing vessel 21. The shower head 4 is configured to eject gas in a shower-like manner from multiple ejection ports 41 formed in its lower surface toward the wafer W placed on the mounting table 3.

[0015] Furthermore, a supply path 42 for supplying gas to the shower head 4 is formed in the processing vessel 21, 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, and the like.

[0016] In this example, titanium tetrachloride (TiCl) is used as a source gas containing metal. ４ ) gas, and ammonia (NH ３) gas, nitrogen (N ２ ) gas, and oxygen (O ２ These gases are supplied into the processing chamber 21 via the shower head 4 at preset timings based on control signals from a control unit 100, which will be described later.

[0017] Although not shown in the figure, a N 2 gas is supplied through the shower head 4 in addition to the supply pipe 433 for the purge gas, which is provided with the valve V3 and the flow rate adjusting unit M3. ２ A gas supply pipe is provided to supply gas into the processing vessel 21. ２ The gas is constantly supplied into the processing vessel 21 during processing of the wafer W, and TiCl ４ Gas, NH ３ Gas, O ２ In addition to acting as a carrier gas for each of the gases, TiCl ４ Gas, NH ３ It also helps to purge gases from the process vessel 21 .

[0018] Also, O ２ The gas is TiCl in the second step described below. ４ Gas supply and NH ３ When the gas supply is repeated, TiCl ４ Gas and NH ３ When supplied between the supply of one of the gases and the supply of the other, the N gas also acts as a purge gas for the other gas. However, unless otherwise specified, the purge gas is N 2 O 3 supplied into the processing vessel 21 from the supply source 53 through the supply pipes 433 and 434. ２ It is assumed that this refers to gas.

[0019] Furthermore, a transfer port 26 is formed in the sidewall of the processing vessel 21, through which the wafer W is loaded 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 by 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 unit of the film forming apparatus 2 for performing control necessary for processing the wafer W. Such a program is stored in a storage unit of the computer, such as a flexible disk, a compact disk, a hard disk, an MO (magneto-optical disk), a non-volatile memory, etc., and is read from the storage unit and installed in the control unit 100. A source gas (TiCl ４ ), nitriding gas (NH ３ ), oxidizing gas (O ２ ), purge gas (N ２ The start and stop of supply and adjustment of the flow rate of the gas 102 are also carried out based on control signals from the control unit 100.

[0021] 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, N ２ While supplying the gas, the inside of the processing chamber 21 is evacuated through the exhaust path 24 to adjust the pressure inside the processing chamber 21 to a preset value, and the wafer W on the mounting table 3 is heated to a preset temperature by the heater 31. Then, TiCl is supplied from the gas supply unit 5 through the shower head 4 into the processing chamber 21. ４ Gas is supplied to the surface of the wafer W to form TiCl ４ The gas is adsorbed (step S1). In this way, TiCl ４ After supplying the gas, TiCl ４ The gas supply is stopped, and N ２ Purging is performed with gas (step S2).

[0023] Next, NH ３ The gas was supplied to remove TiCl adsorbed on the wafer surface.４ and form TiN (step S3). ３ After supplying the gas, NH ３ The gas supply is stopped, and N ２ Purging is performed with gas (step S4). ４ Gas → Purge gas → NH ３ In the order of gas → purge gas, TiCl ４ Gas and NH ３ A first cycle is executed in which the first and second gases are sequentially supplied once to the wafer W. This first cycle (steps S1 to S4) is repeated a predetermined number of times, i.e., X times, to form a TiN layer 11 having a set thickness.

[0024] <Second Process (Second Step)> After the first process described above is completed, the second process is carried out. In this second process, first, TiCl 4 , which is the same source gas as in the first process, is introduced into the processing vessel 21. ４ Gas is supplied to the surface of the wafer W to form TiCl ４ The gas is adsorbed (step S5). In this way, TiCl ４ After supplying the gas, TiCl ４ The supply of gas is stopped. Then, O is introduced into the processing vessel 21 for a predetermined period of time. ２ After supplying the gas, ２ The supply of gas is stopped (step S6). As a result, TiCl 2 that is not adsorbed on the wafer W is removed. ４ Gas is O ２ The gas is purged from the processing vessel 21 and the wafer surface is oxidized.

[0025] Next, the same nitriding gas as in the first step, NH ３ The gas is supplied to oxidize TiCl on the wafer surface. ４ and form the TiON layer 12 (step S7). ３ After supplying the gas, NH ３ The supply of gas is stopped. Then, O is introduced into the processing vessel 21 for a predetermined period of time. ２After supplying the gas, ２ The gas supply is stopped (step S8), whereby the oxidized TiCl 2 on the wafer surface is removed. ４ NH that did not react with ３ Gas is O ２ The gas is purged from the processing vessel 21, and the oxidation of the TiON layer 12 progresses.

[0026] Thus, TiCl ４ Gas → O ２ Gas → NH ３ Gas → O ２ The second cycle is then performed, in which the gases are supplied to the wafer W in the order of the TiCl 2 and TiCl 3 gases. Then, the second cycle (steps S5 to S8) is repeated a predetermined number of times (Y times) to form the TiON layer 12 having a predetermined thickness. ４ Gas and NH ３ gas once and TiCl ４ Gas, NH ３ Gas, O ２ This is a cycle in which gases are supplied in sequence, and TiCl ４ Gas and NH ３ Each time a layer of TiN is formed by reaction with the gas, O ２ As a result, the thin TiN film is ２ Since the TiN is oxidized by the gas, the oxidation of the TiN can be reliably promoted.

[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 manner, by alternately repeating the first and second steps Z times, which is a preset number of times, a TiN film 1 in which the TiN unit layers 10 are stacked in Z layers is formed. Here, taking an example of the TiN film 1 used as a sacrificial film, the film thickness of the TiN film 1 is set to, for example, 50 nm to 200 nm, and the film 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 steps are performed, for steps S1 to S8 included in these steps, the next step S is performed upon completion of one step S. Therefore, when the first and second steps are performed in order, the second step is started upon completion of the first step. Specifically, step S5 of the second step is started upon completion of step S4 of the first step. Then, when the first and second steps are repeated, the first step is resumed upon completion of step S2. Specifically, step S1 of the first step is started upon completion of step S8 of the second step. Note that, between the completion of step S8 and step S1 of the first step, N ２ A process of purging the inside of the processing vessel 21 by supplying only gas may be performed.

[0029] In this way, the TiN film 1 is formed by alternately laminating the TiN layers 11 and the TiON layers 12 in this order from the bottom. After the film formation process of the TiN film 1 is completed, the inside of the processing vessel 21 is purged with N ２ The gas is purged, and the gate valve 27 is opened to transfer the wafer W out through the transfer port 26 .

[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 and second processes, but they may be different. However, if the temperature and pressure are different in the first and second processes, 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. Therefore, it is preferable that the temperature and pressure are the same in the first and second processes.

[0031] Here, examples of the treatment conditions for the first step and the second step are as follows: <Treatment conditions for the first step> TiCl ４ Gas supply time (time of step S1): 0.03 to 5.0 seconds NH ３ Gas supply time (time for step S3): 0.03 to 5.0 seconds Pressure inside the processing vessel 21: 100 to 3000 Pa Processing temperature (temperature of the mounting table 3): 300 to 650° C. <Processing conditions for the second step> TiCl ４ Gas supply time (time in step S5): 0.03 to 5.0 seconds NH３ Gas supply time (time in step S7): 0.03 to 5.0 seconds O in steps S6 and S8 ２ Gas supply time: 0.03 to 5.0 seconds Pressure inside the processing vessel 21: 100 to 3000 Pa Processing temperature (temperature of the 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] FIG. 4 is a schematic diagram showing TiN films formed with the same thickness by varying the combinations of X, Y, and Z for the TiN film 1. The left side of FIG. 4 shows a TiN film 1A in which 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 FIG. 4 shows a TiN film 1B in which 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, the 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, the TiN film 1A has a larger total thickness of the TiON layer 12 due to the larger number of repetitions Z of the first and second steps, compared to the TiN film 1B, which has a larger number of cycles X, resulting in a higher oxygen concentration in the film. In this way, the oxygen concentration in the TiN film 1 can be controlled by adjusting the combinations 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 between the total thickness of the TiN layers 11 and 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 an 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 X, Y, and Z values ​​(referred to as recipe A) for forming the TiN film 1A of FIG. 4 and the X, Y, and Z values ​​(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 in 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 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 for each wafer W lot so that the TiN film 1 to be formed has an appropriate stress.

[0036] As described above, the number X of first cycles and the number Y of second cycles 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 X of first cycles to be greater than the number Y of second cycles.

[0037] Incidentally, the first and second cycles have been described as being repeatedly performed. That is, although X and Y have been described as integers of 2 or greater, 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 the first and / or second cycles may be performed once before starting the other cycle. Note that Z is an integer of 2 or greater. That is, as described above, the TiN layer 11 and the TiON layer 12 are alternately and repeatedly stacked. As a result, oxygen is introduced so as to be dispersed throughout the thickness direction 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 layer 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 constituting 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 mentioned above, in the second cycle, O ２The gas is supplied to form 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, and good uniformity of the oxygen concentration can be ensured in the thickness direction of the TiN film 1.

[0041] Next, modified examples of the above-described embodiment will be described. <First Modification> In the film forming method of the present disclosure, the second cycle is a cycle in which TiCl 2 is applied to the wafer W as shown in the timing chart of FIG. ４ Gas, NH ３ After supplying the gas, ２ In this example, the second cycle may be a cycle in which TiCl is supplied into the processing vessel 21. ４ Gas → N, the purge gas ２ Gas → NH ３ Gas → O ２ In the second cycle, TiCl ４ After gas supply, ２ No gas is supplied, and N ２ The second cycle of this example is the same as the above embodiment except that purging is performed using only NH ３ After the gas supply, ２ Gas is N ２ Since it is supplied together with the gas, the formed TiN is quickly oxidized to form the TiON layer 12 .

[0042] By the way, when TiN on the wafer W is oxidized to form the TiON layer 12, NH ３ The O supplied in step S8 after the gas supply ２ The contribution of gas is large. Of steps S6 and S8, only S6 ２ When gas is supplied (i.e., TiCl ４ Gas → O ２ Gas → NH ３It has been confirmed through experiments that the oxidizing power of the O gas to the TiN is low when the cycle is performed using the O gas → purge gas. ２ However, as shown in the timing charts of FIGS. 3 and 5, at least in step S8, O ２ In order to reliably oxidize TiN and reliably introduce oxygen into the TiN film to adjust the stress, it is preferable to supply O 2 gas in each of steps S6 and S8 as shown in the timing chart of FIG. ２ It is preferred to supply gas.

[0043] <Second Modification> Although the first step is performed before the second step in the first embodiment, the second step may be performed before the first step to form the TiN film. A timing chart of this example is shown in Fig. 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 the TiN film.

[0044] 7, a TiN unit layer 13 is formed by laminating a TiON layer 12 and a TiN layer 11 in this order from the bottom, 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 constructed by alternately laminating a TiON layer 12 and a TiN layer 11 in this order from the bottom. 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 is performed by removing TiCl ４ Gas supply → N ２ Gas purging → NH ３ Gas supply → O ２ This can be done by cycling the gas supply.

[0045] 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 having 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 a TiN film 1, but for convenience in describing this evaluation test, it will be referred to as a TiN film 1. In Evaluation Test 2 described below, a TiN film (Comparative Example 2) in which Y is set to 0 and does not include the TiON layer 12 will also be referred to as a TiN film 1 for the purposes of describing the evaluation test.

[0047] The first and second steps were carried out under the following treatment conditions: <Treatment conditions for the first step> TiCl ４ Gas supply time (time for step S1): 0.05 seconds NH ３ Gas supply time (time for 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 the mounting table 3): 400° C. <Processing conditions for the second step> TiCl ４ Gas supply time (time for step S5): 0.05 seconds NH ３ Gas supply time (time for step S7): 0.3 seconds ２ Gas supply time (time for step S6): 0.2 seconds ２ Gas supply time (time for step S8): 0.3 seconds Pressure inside the processing vessel 21: 400 to 600 Pa Processing temperature (temperature of the 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 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. From this evaluation test 1, it was confirmed that the oxygen concentration of the formed TiN film 1 can 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 having a stress of approximately +1.5 GPa, and Comparative Example 1 in which the TiN layer 11 was not formed having a stress of approximately -0.5 GPa. Considering the results of Evaluation Test 1, the oxygen concentration in the TiN film 1 increases as X / Y decreases. It can be seen that as the oxygen concentration increases, the stress in the TiN film 1 decreases, changing 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 than 0 Pa and values ​​lower than 0 Pa in this way, it is estimated that the stress of the TiN film 1 can also be changed between tensile stress and compressive stress. As described above, Evaluation Tests 1 and 2 guaranteed 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, etc. Furthermore, the metal contained in the source gas is not limited to Ti, but other metals may be appropriately selected. Therefore, the metal nitride film formed on the wafer W is not limited to a TiN film, but may be other metal nitride films.

[0053] Furthermore, the source gas, nitriding gas, and oxidizing gas are not limited to the above examples. When the metal nitride film containing oxygen is a TiN film, the source gas may be TiCl ４ In addition to gas, tetra(isopropoxy)titanium (TTIP), titanium tetrabromide (TiBr ４ ), titanium tetraiodide (TiI ４ ), tetrakisethylmethylaminotitanium (TEMAT), tetrakisdimethylaminotitanium (TDMAT), tetrakisdiethylaminotitanium (TDEAT), etc. can be used. ３ Alternatively, monomethylhydrazine (MMH) can be used. ２ In addition to gas, ３ Gas, H ２ O, NO ２ As the purge gas, N ２ The gas is not limited to this, and an inert gas such as argon (Ar) gas can be used.

[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 above-described film formation apparatus are merely examples, and are not limited to the above-described configuration. While wafers have been used as examples of substrates, substrates processed in the processing chamber include, in addition to wafers, substrates used in the manufacture of flat panel displays, dummy substrates processed for the purpose of testing or setting processing parameters, and the like.

[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.

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

Claims

1. A method for forming an oxygen-containing metal nitride film, comprising: a first step of carrying out a first cycle in which a metal-containing source gas and a nitriding gas are each supplied once to a substrate in that order in one cycle, thereby forming a metal nitride layer on the substrate; a second step of carrying out a second cycle in which the source gas and the nitriding gas are each supplied once to the substrate in that order in one cycle, and the source gas, the nitriding gas, and the oxidizing gas are each supplied once to the substrate in that order in one cycle, thereby forming a metal oxynitride layer on the substrate; and 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.

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

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

6. An apparatus for forming an oxygen-containing metal nitride film, comprising: a processing vessel for storing a substrate; a gas supply unit for supplying a metal-containing source gas, a nitriding gas, and an oxidizing gas into the processing vessel; and a control unit that outputs control signals to perform the following steps: a first step of forming a metal nitride layer on the substrate by performing a first cycle of supplying the source gas and the nitriding gas once each to the substrate in that order in one cycle; a second step of forming a metal oxynitride layer on the substrate by performing a second cycle of supplying the source gas, the nitriding gas once each, and the source gas, the nitriding gas, and the oxidizing gas in that order in one cycle to the substrate in one cycle; and 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.

Images