Substrate processing method and substrate processing apparatus

Abstract

Provided is a substrate processing method for forming a TiSiN film in which a titanium nitride film and a silicon nitride film are laminated on the surface of a substrate, the method including (a) preparing the substrate on a stage in a processing chamber, (b) alternately supplying a Ti starting material gas, which contains a Ti starting material, and a nitriding gas into the processing chamber X times so as to form the titanium nitride film, and (c) supplying an Si starting material gas, which contains an Si starting material, and a nitriding gas into the processing chamber, with the Si starting material gas being supplied at least Y times, so as to form the silicon nitride film. With respect to this substrate processing method, (d) the step (b) and the step (c) are executed in this order Z times, X and Z are an integer of 1 or more, and Y is an integer of 2 or more.

Description

Substrate processing method and substrate processing apparatus

[0001] The present disclosure relates to a substrate processing method and a substrate processing apparatus.

[0002] Patent Document 1 proposes a first film formation process including a first step of supplying a first source gas containing a metal into a processing vessel and removing the first source gas from the processing vessel, a second step of supplying a second source gas that reduces the first source gas into the processing vessel and removing the second source gas from the processing vessel, and a third step of supplying a third source gas containing silicon into the processing vessel and removing the third source gas from the processing vessel, and further includes a second film formation process of forming a conductive layer on the layer containing metal, nitrogen, and silicon formed by the first film formation process.

[0003] Patent Document 2 proposes a film formation method including the steps of placing a substrate in a processing vessel, depositing a metal film on the substrate in the processing vessel, and then supplying a Si-containing gas into the processing vessel with the substrate placed in the processing vessel.

[0004] JP 2005-011940 A JP 2021-110030 A

[0005] The present disclosure provides a substrate processing method and a substrate processing apparatus that can improve the coverage of a TiSiN film.

[0006] According to one aspect of the present disclosure, there is provided a substrate processing method for forming a TiSiN film having a titanium nitride film and a silicon nitride film stacked on a surface of a substrate, the method including: (a) preparing the substrate on a stage in a processing vessel; (b) alternately supplying a Ti source gas containing a Ti source and a nitriding gas into the processing vessel X times to form the titanium nitride film; (c) supplying a Si source gas containing a Si source and a nitriding gas into the processing vessel, and supplying the Si source gas at least Y times to form the silicon nitride film; and (d) performing steps (b) and (c) in this order Z times, wherein X and Z are integers equal to or greater than 1, and Y is an integer equal to or greater than 2.

[0007] According to one aspect, the coverage of the TiSiN film can be improved.

[0008] 1 is a cross-sectional view showing an example of a film structure of a TiSiN film; FIG. 2 is a schematic cross-sectional view showing an example of a substrate processing apparatus according to an embodiment; FIG. 3 is a flowchart showing an example of a substrate processing method according to an embodiment; FIG. 4 is a flowchart showing an example of a film formation method according to a first embodiment; FIG. 5 is a time chart showing an example of a film formation method according to the first embodiment; FIG. 6 is a graph showing an example of an experiment result of coverage versus cycle ratio; FIG. 7 is a graph showing an example of an experiment result of film formation rate versus cycle ratio; FIG. 8 is a cross-sectional view of a film showing an example of coverage effect versus cycle ratio; FIG. 9 is a graph showing an example of an experiment result of coverage versus cycle ratio and gap; FIG. 10 is a diagram for explaining the relationship between the continuity of a TiN film and the formation of a SiN film; FIG. 11 is a diagram for explaining the relationship between the continuity of a TiN film and the formation of a SiN film; FIG. 12 is a flowchart showing an example of a film formation method according to a second embodiment; FIG. 13 is a time chart showing an example of a film formation method according to a second embodiment; FIG. 14 is a flowchart showing an example of a film formation method according to a third embodiment; FIG. 15 is a time chart showing an example of a film formation method according to the third embodiment.

[0009] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the drawings, the same components are denoted by the same reference numerals, and redundant explanations may be omitted.

[0010] [TiSiN Film] A TiN film (titanium nitride film) is used for, for example, a capacitor electrode of a memory cell. The TiN film is formed by, for example, using TiCl ４ (Titanium tetrachloride) gas was used as the Ti source gas, and NH ３ Atomic Layer Deposition (ALD) using ammonia gas as the nitriding gas is used. Furthermore, in order to improve the chemical resistance and oxidation resistance of the TiN film, it has been proposed to form a TiSiN film by doping the TiN film with silicon (Si).

[0011] 1 is a cross-sectional view showing an example of the film structure of a TiSiN film 201 formed on the surface of a substrate W. By repeating the process of alternately forming TiN films 101 and SiN films 102 Z times on the surface of a silicon substrate 200, a TiSiN film 201 is formed in which Z layers of TiN films 101 and SiN films 102 are alternately stacked. The SiN film can be formed, for example, by using a SiH ４(Silane) gas is used as the Si source gas, and NH ３ The ALD method using a nitriding gas is used. Note that the TiN film and the SiN film may be formed by a CVD (Chemical Layer Deposition) method.

[0012] Each layer of the TiN film 101 is formed by repeating the film formation sequence of the TiN film 101 X times. Each layer of the SiN film 102 is formed by repeating the film formation sequence of the SiN film 102 Y times. The film formation sequence of the TiN film 101 repeated X times is also referred to as the "TiN sequence," and the film formation sequence of the SiN film 102 repeated Y times is also referred to as the "SiN sequence." Then, the TiN sequence repeated X times and the SiN sequence repeated Y times are combined as a whole, and the whole is executed Z times. As a result, as shown in FIG. 1 , a TiSiN film 201 is formed, which is a laminated film in which Z layers of TiN films 101 and Z layers of SiN films 102 are alternately stacked.

[0013] In forming the TiSiN film 201, due to the self-decomposition of the Si source gas, there may arise a problem that the coverage of the SiN film 102 is inferior to the coverage of the TiN film 101. For example, on a substrate having a recess pattern due to the self-decomposition of the Si source gas, this is caused by the fact that a large amount of the SiN film is formed on the upper surface side of the recess.

[0014] Therefore, we propose a substrate processing method using the ALD method that can improve the coverage of the SiN film in the TiSiN film. ４ Gas and NH ３ The SiN film is formed by alternately supplying the SiH ４ Gas and NH ３ The TiN film 101 and the SiN film 102 are alternately supplied Y times to form the film 102. By changing the ratio (hereinafter also referred to as the "cycle ratio") between the number of repetitions X when forming one layer of the TiN film 101 and the number of repetitions Y when forming one layer of the SiN film 102, it is possible to form a TiSiN film with improved coverage while adjusting the silicon concentration.

[0015] Below, an example of a substrate processing apparatus capable of performing the substrate processing will be described with reference to FIG. 2, and then a substrate processing method for forming a TiSiN film with improved coverage will be described with reference to FIG. 3 and subsequent figures.

[0016] 2 is a cross-sectional view showing an example of a substrate processing apparatus 10 according to an embodiment. The substrate processing apparatus 10 is an ALD apparatus that forms a TiSiN film 201, which is a stacked film of a TiN film 101 and a SiN film 102, on the surface of a substrate W, e.g., a wafer. The substrate processing apparatus 10 alternately forms one layer of the TiN film 101 and then one layer of the SiN film 102, thereby forming the TiSiN film 201 shown in FIG.

[0017] The substrate processing apparatus 10 includes a processing vessel 1, a stage 2, a shower head 3, an exhaust unit 4, a processing gas supply unit 5, and a control device 7. The processing vessel 1 is made of a metal such as aluminum and has a generally cylindrical shape. A sidewall of the processing vessel 1 is formed with a loading / unloading port 11 for loading and unloading a substrate W, and the loading / unloading port 11 can be opened and closed by a gate valve 12. An annular exhaust duct 13 having a generally rectangular cross section is provided on the main body of the processing vessel 1. A slit 13a is formed along the inner circumferential surface of the exhaust duct 13. A ring-shaped exhaust space 13b is also formed in the exhaust duct 13. An exhaust port 13c is also formed in the outer wall of the exhaust duct 13. A ceiling wall 14 is provided on the upper surface of the exhaust duct 13 to close the upper opening of the processing vessel 1. A seal ring 15 provides an airtight seal between the ceiling wall 14 and the exhaust duct 13.

[0018] The stage 2 supports the substrate W horizontally within the processing chamber 1. The stage 2 is disk-shaped and sized to accommodate the substrate W, and is supported by a support member 23. The stage 2 is made of a ceramic material such as aluminum nitride (AlN) or a metal material such as aluminum or a nickel-based alloy, and has a heater 21 embedded therein for heating the substrate W. The heater 21 generates heat when power is supplied from a heater power supply (not shown). The output of the heater 21 is controlled by a temperature signal from a thermocouple (not shown) provided near the wafer-mounting surface on the top surface of the stage 2, thereby controlling the temperature of the substrate W at a predetermined level.

[0019] A cover member 22 made of ceramics such as alumina is provided on the stage 2 to cover the outer peripheral region of the wafer mounting surface and the side surfaces of the stage 2. A support member 23 extends from the center of the bottom surface of the stage 2 below the processing vessel 1 through a hole formed in the bottom wall of the processing vessel 1, and its lower end is connected to an elevation mechanism 24. The elevation mechanism 24 enables the stage 2 to be raised and lowered via the support member 23 between a processing position shown in FIG. 1 and a transfer position, shown by a two-dot chain line below, where a wafer can be transferred. A flange 25 is attached to the support member 23 below the processing vessel 1, and a bellows 26 is provided between the bottom surface of the processing vessel 1 and the flange 25 to separate the atmosphere inside the processing vessel 1 from the outside air. The bellows 26 expands and contracts as the stage 2 is raised and lowered.

[0020] Three support pins 27 (only two shown) are provided near the bottom of the processing vessel 1 so as to protrude upward from a lift plate 27a. The support pins 27 can be raised and lowered via the lift plate 27a by a lift mechanism 28 provided below the processing vessel 1, and are inserted into through holes 2a provided in the stage 2 at the transfer position so as to be able to protrude and retract relative to the upper surface of the stage 2. By raising and lowering the support pins 27 in this manner, the substrate W is transferred between a wafer transfer mechanism (not shown) and the stage 2.

[0021] The shower head 3 supplies a processing gas into the processing vessel 1 in a shower-like manner. The shower head 3 is made of metal, is provided facing the stage 2, and has approximately the same diameter as the stage 2. The shower head 3 has a main body 31 fixed to the ceiling wall 14 of the processing vessel 1, and a shower plate 32 connected below the main body 31. A gas diffusion space 33 is formed between the main body 31 and the shower plate 32, and a gas inlet hole 36 is provided in the gas diffusion space 33 so as to penetrate the center of the main body 31 and the ceiling wall 14 of the processing vessel 1. A downwardly protruding annular protrusion 34 is formed on the periphery of the shower plate 32, and gas outlet holes 35 are formed on the flat surface inside the annular protrusion 34 of the shower plate 32.

[0022] When the stage 2 is in the processing position, a processing space 37 is formed between the shower plate 32 and the stage 2, and the annular protrusion 34 and the upper surface of the cover member 22 of the stage 2 are close to each other to form an annular gap 38. The width (length) of the gap between the lower surface of the annular protrusion 34 and the upper surface of the cover member 22 is indicated by "gap G."

[0023] The exhaust unit 4 exhausts the interior of the processing chamber 1. The exhaust unit 4 includes an exhaust line 41, a pressure adjustment unit (APC: Auto Pressure Controller) 42, a valve 43, and a vacuum pump 44. One end of the exhaust line 41 is connected to the exhaust port 13c of the exhaust duct 13, and the other end is connected to the suction port of the vacuum pump 44. Between the exhaust duct 13 and the vacuum pump 44, the pressure adjustment unit 42 and the valve 43 are installed, in this order from upstream to downstream. The pressure adjustment unit 42 adjusts the conductance of the exhaust path to adjust the pressure of the processing space 37. The valve 43 switches the exhaust line 41 on and off. During processing, gas in the processing space 37 reaches the exhaust space 13b of the exhaust duct 13 through the annular gap 38 and the slit 13a, and is then exhausted through the exhaust line 41 by the vacuum pump 44 of the exhaust unit 4 from the exhaust port 13c of the exhaust duct 13.

[0024] The process gas supply unit 5 includes a Ti source gas supply line L1, a Si source gas supply line L2, and an NH ３ It has a gas supply line L3 and a purge line L4.

[0025] The Ti source gas supply line L1 supplies, as the Ti source gas, for example, TiCl ４ The gas source is TiCl ４ The Ti source gas supply line L1 extends from the supply source GS1 and is connected to a junction pipe L5. The junction pipe L5 is connected to a gas inlet 36. The Ti source gas supply line L1 contains TiCl ４ A mass flow controller (MFC) M1, a buffer tank T1, and an on-off valve V1 are provided in this order from the supply source GS1 side. The mass flow controller M1 controls the TiCl 2 flowing through the Ti source gas supply line L1. ４ The buffer tank T1 controls the flow rate of the gas. ４ Gas is temporarily stored and the required TiCl ４ The on-off valve V1 supplies TiCl gas during the ALD process. ４ Switches gas supply on and off.

[0026] The Si source gas supply line L2 supplies, as the Si source gas, for example, SiH ４ The gas source is SiH ４ The Si source gas supply line L2 extends from the supply source GS2 and is connected to the junction pipe L5. ４ A mass flow controller M2, a buffer tank T2, and an on-off valve V2 are provided in this order from the supply source GS2 side. The mass flow controller M2 controls the SiH ４ The buffer tank T2 controls the flow rate of the gas. ４ Gas is temporarily stored and SiH required in a short time is ４ The on-off valve V2 supplies SiH gas during the ALD process. ４ Switches gas supply on and off.

[0027] NH ３ The gas supply line L3 supplies a nitrogen-containing gas, for example, NH ３ It extends from the gas supply source GS3 and is connected to the junction pipe L5. ３ The gas supply line L3 contains NH ３A mass flow controller M3, a buffer tank T3, and an on-off valve V3 are provided in this order from the gas supply source GS3 side. ３ NH flowing through the gas supply line L3 ３ The buffer tank T3 controls the flow rate of the NH ３ Temporarily stores gas and supplies NH3 needed in a short time ３ The on-off valve V3 supplies NH ３ Switches gas supply on and off.

[0028] Purge line L4 is N ２ N, the gas source ２ The purge line L4 extends from the gas supply source GS4 and is connected to the junction pipe L5. The purge line L4 is used to purify N ２ The purge line L4 is supplied with N ２ A mass flow controller M4, a buffer tank (not shown), and an on-off valve V4 are provided in this order from the gas supply source GS4 side. The mass flow controller M4 controls the N ２ The buffer tank controls the gas flow rate. ２ Gas is temporarily stored and N required for a short time is obtained. ２ The on-off valve V4 supplies N gas during purging of the ALD process. ２ Switches gas supply on and off.

[0029] The ceiling wall 14 is connected to an RF (Radio Frequency) power supply 50 via a matching box 51. The RF power supply 50 supplies high frequency (RF) power for generating plasma.

[0030] The control device 7 controls the operation of each part of the substrate processing apparatus 10. The control device 7 has a CPU (Central Processing Unit), ROM (Read Only Memory), and RAM (Random Access Memory). The CPU executes substrate processing according to a recipe stored in a storage area such as the RAM. The recipe sets control information for the apparatus with respect to various process conditions such as film formation conditions. The control information may be, for example, gas flow rate, pressure, temperature, and process time. The recipe and the program used by the control device 7 may be stored in, for example, a hard disk or semiconductor memory. The recipe and the like may also be stored in a portable, computer-readable storage medium such as a CD-ROM or DVD, which is set in a predetermined position and read out.

[0031] [Film Formation Method] Next, a substrate processing method for forming a TiSiN film by stacking a TiN film (titanium nitride film) and a SiN film (silicon nitride film) on the surface of a substrate by ALD will be described. Figure 3 is an example of a flowchart showing an example of a substrate processing method according to an embodiment. The substrate processing method of Figure 3 is controlled by a control device 7 and executed by a substrate processing apparatus 10.

[0032] First, in step S1, a substrate W is loaded into the processing chamber 1 of the substrate processing apparatus 10. Specifically, the stage 2, which has been heated to a predetermined temperature (e.g., 300°C to 700°C) by the heater 21, is lowered to the transfer position (shown by the two-dot chain line in FIG. 1), and the gate valve 12 is opened. Next, the substrate W is loaded into the processing chamber 1 through the loading / unloading port 11 by a transfer arm (not shown), and is supported by the support pins 27. When the transfer arm retracts from the loading / unloading port 11, the gate valve 12 is closed. The support pins 27 are then lowered, and the substrate W is placed on the stage 2, thereby preparing the substrate W.

[0033] Subsequently, in step S2, the stage 2 is raised to the processing position (shown by the solid line in FIG. 2), and the gap G between the lower surface of the annular protrusion 34 and the upper surface of the cover member 22 is controlled. The gap G may be controlled to 0.5 mm or less.

[0034] Next, in step S3, the temperature of the substrate W on the stage 2 is increased, and the opening degree of the pressure adjusting unit 42 is adjusted. That is, the temperature of the substrate W on the stage 2 is increased by the heater 21 heated to, for example, 300°C to 700°C. Furthermore, the control device 7 controls the exhaust unit 4 to adjust the interior of the processing vessel 1 to a predetermined vacuum level. Thereafter, the control device 7 opens the on-off valve V4 and closes the on-off valves V1 to V3. As a result, N ２ Gas supply source GS4 to N ２ N through gas supply line L4 ２ The gas is supplied into the processing space 37 to increase the pressure. The control device 7 also adjusts the opening of the pressure adjusting unit 42 so that the pressure in the processing space 37 becomes the desired pressure based on a pressure sensor (not shown) that detects the pressure in the processing space 37. At this time, TiCl ４ TiCl from source GS1 ４ The gas is supplied to the buffer tank T1, and the pressure in the buffer tank T2 is maintained at a substantially constant level. ４ SiH from source GS2 ４ The gas is supplied to the buffer tank T2, and the pressure in the buffer tank T3 is maintained at a substantially constant level. ３ Gas supply source GS3 to NH ３ Gas is supplied to maintain the pressure in the buffer tank T3 at a substantially constant level.

[0035] In step S4, a film formation process is performed. In this film formation process, a TiSiN film is formed on the substrate W, the specific process of which will be described later. When the film formation process is completed, the process proceeds to step S5.

[0036] In step S5, the control device 7 controls the lifting mechanism 24 to lower the stage 2 to the transfer position.

[0037] In step S6, the substrate W is unloaded from the processing vessel 1 of the substrate processing apparatus 10. Specifically, the support pins 27 are raised to lift the substrate W placed on the stage 2 and support it on the support pins 27. The gate valve 12 is also opened. Next, the inserted transfer arm (not shown) unloads the substrate W from the processing vessel 1 through the load / unload port 11. When the transfer arm retracts from the load / unload port 11, the gate valve 12 is closed. This completes the process of forming a TiSiN film on the substrate W in the substrate processing apparatus 10.

[0038] First Embodiment [TiSiN Film Formation Example 1] In the first embodiment, TiSiN film formation example 1 in step S4 of Fig. 3 will be further described with reference to Fig. 4 and Fig. 5. Fig. 4 is a flowchart showing an example of the film formation method according to the first embodiment. Fig. 5 is a time chart showing an example of the film formation method according to the first embodiment.

[0039] (TiN Film Formation) Steps S11 to S15 in FIG. 4 show an example of a TiN sequence. ４ Gas and NH ３ The gases are alternately supplied X times to form a TiN film by the ALD process.

[0040] In step S11, with the on-off valve V4 open and the on-off valves V1 to V3 closed, the on-off valve V1 is opened, and TiCl is supplied from the TiCl4 supply source GS1 through the Ti raw material gas supply line L1. ４ The gas is supplied to the processing space 37. At this time, TiCl ４ The gas is temporarily stored in the buffer tank T1 and then supplied into the processing chamber 1. As a result, TiCl ４ The gas is adsorbed.

[0041] Next, in step S12, excess TiCl in the processing space 37 is ４ In step S12, the on-off valve V1 is closed, and the TiCl ４ The supply of gas is stopped. Also, the on-off valve V4 is in an open state. ２ N gas is supplied from the gas supply source GS4 through the purge line L4. ２The gas is supplied into the processing chamber 1. As a result, the TiCl ４ Gas N ２ The purge gas is replaced with N ２ The gas is not limited to an inert gas, but may be an inert gas such as Ar gas.

[0042] Next, in step S13, the on-off valve V4 is opened and the on-off valves V1 to V3 are closed, and the on-off valve V3 is opened. ３ Gas supply source GS3 to NH ３ NH via gas supply line L3 ３ Gas is supplied to the processing space 37. At this time, NH ３ The gas is temporarily stored in the buffer tank T3 and then supplied into the processing chamber 1. As a result, NH ３ The gas is supplied. ４ A TiN film can be formed by a thermal process using a gas precursor.

[0043] Next, in step S14, excess NH ３ In step S14, the on-off valve V3 is closed and NH ３ The supply of gas is stopped. Also, the on-off valve V4 is in an open state. ２ N gas is supplied from the gas supply source GS4 through the purge line L4. ２ The NH gas is supplied into the processing chamber 1. ３ Gas N ２ Replace with gas.

[0044] Next, in step S15, it is determined whether the process has been repeated a set number of times X (X is a positive integer equal to or greater than 1). In step S15, the processes of steps S11 to S15 are repeated until it is determined that the process has been repeated X times. When it is determined that the process has been repeated X times in step S15, the process proceeds to step S16. As a result, a first layer of the TiN film 101 having a desired thickness is formed on the substrate W (see FIG. 1).

[0045] "TiN Xcycle (X=4)" in FIG. 5 shows a time chart in which steps S11 to S14 are repeated X times, i.e., four times, in the TiN sequence, with one execution of steps S11 to S14 being one cycle.

[0046] (SiN Film Formation) Steps S16 to S20 in FIG. 4 show an example of a SiN sequence. ４ Gas and NH ３ The gases are alternately supplied Y times to form a SiN film by the ALD process.

[0047] In step S16, the on-off valve V2 is opened with the on-off valve V4 open and the on-off valves V1 to V3 closed, and SiH ４ SiH is supplied from the supply source GS2 through the Si source gas supply line L2. ４ Gas is supplied to the processing space 37. At this time, SiH ４ The gas is temporarily stored in the buffer tank T2 and then supplied into the processing chamber 1. As a result, SiH ４ The gas is adsorbed.

[0048] Next, in step S17, excess SiH ４ In step S17, the on-off valve V2 is closed, and the SiH ４ The supply of gas is stopped. Also, the on-off valve V4 is in an open state. ２ N gas is supplied from the gas supply source GS4 through the purge line L4. ２ The gas is supplied into the processing chamber 1. As a result, the SiH ４ Gas N ２ The purge gas is replaced with N ２ The gas is not limited to an inert gas, but may be an inert gas such as Ar gas.

[0049] Next, in step S18, the on-off valve V4 is opened and the on-off valves V1 to V3 are closed, and the on-off valve V3 is opened. ３ Gas supply source GS3 to NH ３ NH via gas supply line L3 ３ Gas is supplied to the processing space 37. At this time, NH ３The gas is temporarily stored in the buffer tank T3 and then supplied into the processing chamber 1. As a result, NH ３ The gas is supplied. ４ A SiN film can be formed by a thermal process using a gas precursor.

[0050] Next, in step S19, excess NH ３ In step S19, the on-off valve V3 is closed and NH ３ The supply of gas is stopped. Also, the on-off valve V4 is in an open state. ２ N gas is supplied from the gas supply source GS4 through the purge line L4. ２ The NH gas is supplied into the processing chamber 1. ３ Gas N ２ Replace with gas.

[0051] Next, in step S20, it is determined whether the process has been repeated a set number of times Y (Y is a positive integer equal to or greater than 2). In step S20, the processes of steps S16 to S20 are repeated until it is determined that the process has been repeated Y times. When it is determined that the process has been repeated Y times in step S20, the process proceeds to step S21. As a result, a first layer of SiN film 102 having a desired thickness is formed on the first layer of TiN film 101 (see FIG. 1).

[0052] "SiN Y cycle (Y≧2)" in FIG. 5 shows a time chart in which steps S16 to S19 are repeated Y times, that is, twice, in the SiN sequence, with one execution of steps S16 to S19 being one cycle.

[0053] Next, in step S21, it is determined whether steps S11 to S20 have been repeated a set number of times Z (Z is a positive integer equal to or greater than 1). In step S21, the processing of steps S11 to S20 is repeated until it is determined that the processing has been repeated Z times, and when it is determined that the processing has been repeated Z times, this processing is terminated. As a result, a TiSiN film is formed on the substrate W, in which TiN films 101 and SiN films 102 are alternately stacked in Z layers (see FIG. 1).

[0054] "Zcycle" in FIG. 5 indicates that Z is a positive integer of 1 or more, and that one cycle is defined as one complete execution of the TiN sequence and the SiN sequence, and that the cycle is repeated Z times (Z cycles).

[0055] As described above, the substrate processing method according to the first embodiment is a substrate processing method for forming a TiSiN film by stacking a TiN film and a SiN film on a surface of a substrate, and includes the steps of (a) preparing the substrate on a stage in a processing vessel, (b) alternately supplying a Ti source gas containing a Ti source and a nitriding gas into the processing vessel X times to form a TiN film, and (c) alternately supplying a Si source gas containing a Si source and a nitriding gas into the processing vessel Y times to form a SiN film, and (d) performing steps (b) and (c) in this order Z times, where X and Z may be integers equal to or greater than 1, and Y may be an integer equal to or greater than 2.

[0056] The fact that Y is 2 or more, that is, the SiN sequence is repeated two or more times, will be explained based on the experimental results shown in FIGS.

[0057] [Experimental Result 1] Figure 6 shows Experimental Result 1. Figure 6 is a graph showing an example of experimental results of the SiN film coverage versus the cycle ratio of X to Y (the ratio of X, which is the number of repetitions required to form one layer of TiN film, to Y, which is the number of repetitions required to form one layer of SiN film). According to this graph, when the TiN sequence is repeated X times and the SiN sequence is repeated Y times, increasing the ratio of Y to X does not result in the SiN film 102, which has poorer coverage than the TiN film 101, continuing to be deposited as Y increases. Instead, a thin SiN film 102 is formed on the remaining adsorption sites on the surface of the TiN film 101, continuously supplementing them. This improves the coverage of the SiN film 102. In other words, as the ratio of X to Y increases, such as when the cycle ratio of TiN:SiN on the horizontal axis, that is, X:Y, is 4:1, 4:10, and 4:20, the amount of SiH is increased on the upper surface of the TiN film 101 where no adsorption sites remain and on the vicinity of the opening of the recess 202 after the SiN film is formed. ４The gas is not adsorbed, but is adsorbed to the bottom of the recess 202 where adsorption sites remain on the surface of the TiN film 101. As a result, it was possible to finally form the SiN film 102 with good coverage. As a result, as shown on the vertical axis of FIG. 6, the step coverage of the SiN film 102 with respect to the pattern of the recess 202 was improved as Y was increased relative to X.

[0058] [Experimental Result 2] Fig. 7 shows Experimental Result 2. Fig. 7 is a graph showing an example of experimental results of the film formation rate of Z cycles versus the cycle ratio of X to Y. The horizontal axis of Fig. 7 represents the cycle ratio. The notation "TiN:SiN = 4:Y (cycles)" on the horizontal axis indicates that in this experiment, X was fixed at "4" and Y was varied to the value on the horizontal axis.

[0059] 7 shows the film formation rate per cycle of forming a TiN film and a SiN film in a Z-layer TiSiN film formation process, which is referred to as the Z cycle rate. The Z cycle rate is the total film thickness of the TiN film and the SiN film per cycle.

[0060] 7, with X fixed at 4, the Z cycle rate increases as Y increases, but when Y is 2 or greater, the Z cycle rate does not change significantly even with an increase in Y. In other words, in the example of FIG. 7, it was found that the coverage of the SiN film 102 can be sufficiently improved by setting Y to 2 or greater.

[0061] 8A is a cross-sectional view of a film showing an example of the coverage effect of a SiN film relative to the cycle ratio of X to Y. For example, in FIG. 8A, when the number of repetitions X of the TiN film 101 is 4 and the number of repetitions Y of the SiN film 102 is 1, the SiN film 102 is formed on the top surface and the side surfaces near the opening of a recess 202 formed in a substrate W. On the other hand, the SiN film 102 is not sufficiently formed on the bottom surface of the recess 202 and the side surfaces near the bottom. Note that the TiN film 101 is formed with good coverage on the top surface, side surfaces, and bottom surface of the recess 202 by setting the number of repetitions X to 4.

[0062] In contrast, in FIG. 8B, when X remains 4 and Y is set to 20, the SiN film 102 is sufficiently formed on the top, side, and bottom surfaces of the recess 202, and the coverage of the SiN film 102 is improved.

[0063] The reason for the control of the cycle ratio of X and Y and the improvement of the coverage of the SiN film in these experiments will be considered. ４ The gas self-decomposes to form SiH ４ The SiN film 102 is likely to be formed on the top surface of the recess 202 and on the side surface near the opening where the gas can easily reach. ４ On the other hand, when Y is increased to 20, SiH gas is not easily delivered to the bottom of the recess 202 where the adsorption sites remain on the surface of the TiN film 101. ４ The gas reaches the recess 202, and the SiN film 102 is formed at the bottom of the recess 202. On the other hand, the SiN film 102 is not formed on the upper surface of the recess 202 where the SiN film 102 has already been formed, or on the SiN film 102 near the opening. ４ It is clear that gas adsorption requires the surface of the TiN film 101 on which the SiN film 102 is not formed. From the above, when Y is 2 or more, the coverage of the SiN film can be improved.

[0064] 9 is a graph showing an example of experimental results of the coverage of the SiN film 102 with respect to the cycle ratio and the gap G. The horizontal axis of Fig. 9, SiN / (TiN+SiN), represents the ratio of the number of SiN cycles Y to the total number of cycles (X+Y). The vertical axis represents step coverage (step coverage in the recess pattern).

[0065] 9 indicates the step coverage when X is fixed at 4 and Y is varied under the conditions of SiN film formation, where the gap G is 0.5 mm, the stage temperature (heater 21 temperature) is 520° C., and the cycle ratio of TiN:SiN (X:Y) is 4:Y. The percentage values ​​in the graph indicate the Si concentration in the TiSiN film.

[0066] The two-dot chain line B (black ●) indicates that the gap G is 3 mm, and the other film formation conditions for the SiN film are the same as those for the one-dot chain line A.

[0067] The dashed line C (white circle) shows the step coverage when the cycle ratio of TiN:SiN (X:Y) is 1:Y, X is fixed at 1, and Y is varied. The other film formation conditions for the SiN film are the same as those of the two-dot chain line B.

[0068] Point D (△) indicates the step coverage when the SiN film deposition conditions are a gap G of 3 mm, a stage temperature of 440° C., and a cycle ratio of TiN:SiN (X:Y) fixed at 1:5.

[0069] The solid line E (white circles) indicates the step coverage when the TiN film is formed at a stage temperature of 520° C. The step coverage of the TiN film is high at about 95%. In contrast, the coverage of the SiN film 102 is relatively poor.

[0070] From the viewpoint of productivity, it is important to form a SiN film with good step coverage while minimizing the cycle ratio of the SiN film to the TiN film. To achieve this, it was found that the number of cycles X for the TiN film is preferably 4 or more, as shown by the dashed-dotted line A and the dashed-two-dotted line B.

[0071] Conversely, when considering the case of point D and dashed line C where the number of cycles X of the TiN film is 1, if X is set to 1 and the TiN sequence is performed only once, the TiN film 101 formed by the single-wafer substrate processing apparatus 10 shown in Figure 2 generally does not reach the molecular monolayer and has an island structure. Figure 10A shows a schematic diagram of a case where the cycle ratio of TiN:SiN (X:Y) is 1:Y and the TiN film 101 becomes a discontinuous film with an island structure. In this case, the surface area of ​​the TiN film 101 becomes large, and SiH ４Since the gas adsorption area becomes larger, a larger amount of SiH4 gas needs to be supplied until the coverage of the SiN film 102 becomes good. This is disadvantageous from the viewpoint of forming the SiN film 102 with good coverage using a smaller amount of Si raw material. Therefore, as a guideline for one molecular layer of the TiN film 101, it is preferable to form the TiN film 101 four or more cycles in the single-wafer substrate processing apparatus 10. As a result, as shown in FIG. 10B, when the cycle ratio of TiN:SiN (X:Y) is 4:Y, the TiN film 101 is in a state of a continuous film formed by one molecular layer, and the surface area of ​​the TiN film 101 can be reduced. This allows less SiH to be formed on the TiN film 101. ４ By supplying the gas, the SiN film 102 can be formed with good coverage.

[0072] From the above, for example, the cycle ratio of TiN:SiN (X:Y) is controlled so that Y is twice or more of X, such as 1:5 or 4:10. In this case, by controlling X to an integer of 1 or more and Y to an integer of 2 or more, the coverage of the SiN film 102 can be improved. Furthermore, it is more preferable to control X to 4 or more. Since the TiN film 101 becomes a continuous film, less SiH ４ The supply of gas allows the SiN film 102 to be formed with good coverage.

[0073] According to the film formation method of the first embodiment, when a TiSiN film is formed by combining a TiN sequence and a SiN sequence, the cycle ratio (X:Y) of X and Y, which are the number of times the TiN sequence and the SiN sequence are repeated, is controlled. X is controlled to be an integer equal to or greater than 1, and Y is controlled to be an integer equal to or greater than 2. By controlling the cycle ratio (X:Y), the step coverage of the SiN film 102 can be improved. As a result, a TiSiN film 201 with good coverage can be formed.

[0074] Furthermore, X is preferably the number of times the TiN film becomes a continuous film, and is preferably equal to or greater than 4. This makes it possible to form the TiSiN film 201 with good coverage even if the supply amount of the Si source gas is reduced.

[0075] Second Embodiment [Film Formation Example 2 of TiSiN Film] Next, a film formation example 2 of the TiSiN film in step S4 of Fig. 3 will be further described with reference to Fig. 11 and Fig. 12. Fig. 11 is a flowchart showing an example of a film formation method according to the second embodiment. Fig. 12 is a time chart showing an example of the film formation method according to the second embodiment.

[0076] In FIG. 11, steps in which the same processes as those in the film forming method according to the first embodiment shown in FIG. 4 are performed are assigned the same step numbers, and descriptions of the processes having the same step numbers will be omitted or simplified.

[0077] (Formation of TiN Film) Steps S11 to S15 in FIG. 11 are performed by filling the processing chamber 1 with TiCl ４ Gas and NH ３ This is the step of forming a TiN film by the ALD process by alternately supplying the gas X times, and is the same step as in the first embodiment.

[0078] "TiN Xcycle (X=4)" in FIG. 12 shows a time chart in which steps S11 to S14 are repeated four times in the TiN sequence, with one cycle consisting of steps S11 to S14.

[0079] Steps S36 to S41 in FIG. 11 are performed by filling the processing chamber 1 with SiH ４ After supplying the gas Y times, NH ３ This step is a step of forming a SiN film by the ALD process by supplying gas once. ４ Gas and NH ３ This is different from the first embodiment in which the gases are alternately supplied Y times to form a SiN film by the ALD process.

[0080] In step S36, the on-off valve V2 is opened with the on-off valve V4 open and the on-off valves V1 to V3 closed, and SiH ４ SiH is supplied from the supply source GS2 through the Si source gas supply line L2. ４ Gas is supplied to the processing space 37. At this time, SiH ４ The gas is temporarily stored in the buffer tank T2 and then supplied into the processing chamber 1. As a result, SiH ４The gas is adsorbed.

[0081] Next, in step S37, excess SiH ４ In step S37, the on-off valve V2 is closed, and the SiH ４ The supply of gas is stopped. Also, the on-off valve V4 is in an open state. ２ N gas is supplied from the gas supply source GS4 through the purge line L4. ２ The gas is supplied into the processing chamber 1. As a result, the SiH ４ Gas N ２ Replace with gas.

[0082] Next, in step S38, it is determined whether steps S36 to S37 have been repeated a set number of times Y (Y is an integer equal to or greater than 2). In step S38, the processes of steps S36 to S37 are repeated until it is determined that they have been repeated Y times, and when it is determined that they have been repeated Y times in step S38, the process proceeds to step S39. As a result, a first layer of the SiN film 102 having a desired thickness is formed on the first layer of the TiN film 101 of the substrate W (see FIG. 1).

[0083] Next, in step S39, the on-off valve V4 is opened and the on-off valves V1 to V3 are closed, and the on-off valve V3 is opened. ３ Gas supply source GS3 to NH ３ NH via gas supply line L3 ３ Gas is supplied to the processing space 37. At this time, NH ３ The gas is temporarily stored in the buffer tank T3 and then supplied into the processing chamber 1. As a result, NH ３ Gas is supplied, and thus a SiN film can be formed.

[0084] Next, in step S40, excess NH ３ In step S40, the on-off valve V3 is closed and NH ３ The supply of gas is stopped. Also, the on-off valve V4 is in an open state. ２ N gas is supplied from the gas supply source GS4 through the purge line L4. ２ The NH gas is supplied into the processing chamber 1. ３Gas N ２ Replace with gas.

[0085] 12 indicates a time chart for forming a SiN film, in which steps S36 to S37 are executed once as one cycle, and steps S36 to S37 are repeated Y times, i.e., two or more times, followed by steps S39 to S40.

[0086] Next, in step S41, it is determined whether steps S11 to S15 and S36 to S40 have been repeated a set number of times Z (Z is a positive integer). In step S41, the processes of S11 to S15 and S36 to S40 are repeated until it is determined that they have been repeated Z times (see Z cycle in FIG. 12). When it is determined that they have been repeated Z times in step S41, this process is terminated. As a result, a TiSiN film is formed on the substrate W, in which TiN films 101 and SiN films 102 are alternately stacked in Z layers (see FIG. 1).

[0087] As described above, the substrate processing method according to the second embodiment is a substrate processing method for forming a TiSiN film by stacking a TiN film and a SiN film on a surface of a substrate, and includes the steps of: (a) preparing the substrate on a stage in a processing vessel; (b) alternately supplying a Ti source gas containing a Ti source and a nitriding gas X times into the processing vessel to form a TiN film; (c) supplying a Si source gas containing a Si source and a nitriding gas into the processing vessel, supplying the Si source gas Y times, and then supplying the nitriding gas to form a SiN film; and (d) performing steps (b) and (c) in this order Z times. Here, X and Z may be integers equal to or greater than 1, and Y may be an integer equal to or greater than 2.

[0088] According to the film formation method of the second embodiment, when a TiSiN film is formed by combining a TiN sequence and a SiN sequence, the cycle ratio (X:Y) between the TiN film sequence and the SiN sequence is controlled. X is controlled to be an integer equal to or greater than 1, and Y is controlled to be an integer equal to or greater than 2. This allows for improved coverage of the TiSiN film. Additionally, the same effects as those of the film formation method of the first embodiment can be obtained.

[0089] Furthermore, in the SiN sequence according to the second embodiment (FIG. 12), SiH ４ After repeatedly supplying the gas Y times, NH ３ Because of the gas supply, the execution time of the SiN sequence can be reduced.

[0090] Third Embodiment [TiSiN Film Formation Example 3] Next, TiSiN film formation example 3 of step S4 in Fig. 3 will be further described with reference to Fig. 13 and Fig. 14. Fig. 13 is a flowchart showing an example of a film formation method according to the third embodiment. Fig. 14 is a time chart showing an example of a film formation method according to the third embodiment.

[0091] In FIG. 13, steps in which the same processes as those in the film forming method according to the first embodiment shown in FIG. 4 are performed are assigned the same step numbers, and descriptions of the processes having the same step numbers will be omitted or simplified.

[0092] (Formation of TiN Film) Steps S11 to S15 in FIG. 13 are performed by filling the processing chamber 1 with TiCl ４ Gas and NH ３ This is the step of forming a TiN film by the ALD process by alternately supplying the gas X times, and is the same step as in the first embodiment.

[0093] "TiN Xcycle (X=4)" in FIG. 14 shows a time chart in which steps S11 to S14 are repeated four times in the TiN sequence, with one cycle consisting of steps S11 to S14.

[0094] Steps S46 to S51 in FIG. 14 are performed by filling the processing vessel 1 with SiH ４ After supplying the gas Y times, NH ３ This is a step in which a SiN film is formed by an ALD process by supplying gas once, and Y may be equal to or greater than 1. In this respect, this embodiment differs from the first and second embodiments in which Y is equal to or greater than 2.

[0095] In step S46, the on-off valve V2 is opened with the on-off valve V4 open and the on-off valves V1 to V3 closed, and SiH ４ SiH is supplied from the supply source GS2 through the Si source gas supply line L2. ４Gas is supplied to the processing space 37. At this time, SiH ４ The gas is temporarily stored in the buffer tank T2 and then supplied into the processing chamber 1. As a result, SiH ４ The gas is adsorbed.

[0096] Next, in step S47, excess SiH ４ In step S47, the on-off valve V2 is closed, and the SiH ４ The supply of gas is stopped. Also, the on-off valve V4 is in an open state. ２ N gas is supplied from the gas supply source GS4 through the purge line L4. ２ The gas is supplied into the processing chamber 1. As a result, the SiH ４ Gas N ２ Replace with gas.

[0097] Next, in step S48, the on-off valve V4 is opened and the on-off valves V1 to V3 are closed, and the on-off valve V3 is opened. ３ Gas supply source GS3 to NH ３ NH via gas supply line L3 ３ Gas is supplied to the processing space 37. At this time, NH ３ The gas is temporarily stored in the buffer tank T3 and then supplied into the processing chamber 1. As a result, NH ３ The gas is supplied. ４ The following chemical reaction occurs by heat treatment using a gas precursor, and a SiN film can be formed: ４ (g) + 32NH ３ (g)=6SiN+24NH ５ +N ２ (g)

[0098] Next, in step S49, the excess NH ３ In step S49, the on-off valve V3 is closed and NH ３ The supply of gas is stopped. Also, the on-off valve V4 is in an open state. ２ N gas is supplied from the gas supply source GS4 through the purge line L4. ２The NH gas is supplied into the processing chamber 1. ３ Gas N ２ Replace with gas.

[0099] Next, in step S50, it is determined whether the time of the SiN sequence (the deposition time of the SiN film), i.e., the time of steps S46 to S49 (the cumulative time of steps S46 to S49 when Y is 2 or more), is at least twice the time per cycle of the TiN sequence (the deposition time per cycle of the TiN film), i.e., the time per cycle of steps S11 to S14.

[0100] If it is determined in step S50 that the time for the SiN sequence is less than twice the time per cycle of the TiN sequence, the process returns to step S46 to repeat the SiN sequence. If it is determined in step S50 that the time for the SiN sequence is equal to or greater than twice the time per cycle of the TiN sequence, the process proceeds to step S51.

[0101] 14 shows a time chart for forming a SiN film by executing steps S46 to S50 once in the SiN sequence. If the time for one cycle of the TiN film sequence is 2 seconds, the time for the SiN sequence will be 4 seconds or more.

[0102] Next, in step S51, it is determined whether steps S11 to S15 and S46 to S50 have been repeated a set number of times Z (Z is a positive integer). In step S51, the processes of S11 to S15 and S46 to S50 are repeated until it is determined that they have been repeated Z times (see Z cycle in FIG. 14). When it is determined that they have been repeated Z times in step S51, this process is terminated. As a result, a TiSiN film is formed on the substrate W, in which TiN films 101 and SiN films 102 are alternately stacked in Z layers (see FIG. 1).

[0103] As described above, the substrate processing method according to the third embodiment is a substrate processing method for forming a TiSiN film by stacking a TiN film and a SiN film on a surface of a substrate, and includes the steps of: (a) preparing the substrate on a stage in a processing chamber; (b) alternately supplying a Ti source gas containing a Ti source and a nitriding gas X times into the processing chamber to form a TiN film; (c) supplying a Si source gas containing a Si source and a nitriding gas into the processing chamber, supplying the Si source gas at least Y times, to form a SiN film; and (d) performing (b) and (c) in this order for Z cycles. Here, X, Y, and Z may be integers equal to or greater than 1. The time period for (c) may be at least twice the time period for one cycle of (b).

[0104] According to the film forming method of the third embodiment, when a TiSiN film is formed by combining a TiN sequence and a SiN sequence, the time of the SiN sequence (the cumulative time of the SiN sequence when Y is 2 or more) is controlled to be at least twice the time per cycle of the TiN sequence. X and Y are 1 or more. In the third embodiment, Y may be set to 1. By controlling the time of the SiN sequence to be at least twice the time per cycle of the TiN sequence, SiH ４ By increasing the gas supply rate, a SiN film with good coverage can be formed. This improves the coverage of the TiSiN film. In addition, the same effects as those of the film formation methods according to the first and second embodiments can be obtained.

[0105] [Others] In the substrate processing methods of the first to third embodiments, the Ti source gas containing the Ti source may be TiCl ４ , TiBr ４ The gas contains Ti.

[0106] The Si source gas containing the Si source is SiH ４ (Silane), Si ２ H ６ (disilane), SiH ２ Cl ２ (dichlorosilane) or SiCl ４ The gas contains Si.

[0107] The nitriding gas used in the TiN film sequence and the nitriding gas used in the SiN sequence are NH ３ , N ２ H ４ , NH(CH ３ ) ２ or N ２ H ３ CH ３ The nitriding gas used in the TiN film sequence and the nitriding gas used in the SiN sequence may be the same gas or different gases.

[0108] The substrate processing apparatus disclosed in this specification can be applied to any of a single-wafer apparatus that processes substrates one by one, a batch apparatus that processes a plurality of substrates at once, and a semi-batch apparatus.

[0109] As described above, according to the substrate processing methods of the first to third embodiments, the coverage of the TiSiN film can be improved.

[0110] The substrate processing method and substrate processing apparatus according to the presently disclosed embodiments should be considered to be illustrative in all respects and not restrictive. The embodiments can be modified and improved in various ways without departing from the spirit and scope of the appended claims. The features described in the above embodiments can be configured in other ways as long as they are not inconsistent, and can be combined as long as they are not inconsistent.

[0111] This international application claims priority based on Japanese Patent Application No. 2023-215351, filed on December 21, 2023, the entire contents of which are incorporated herein by reference.

[0112] 1... processing vessel, 2... stage, 3... shower head, 5... processing gas supply unit, 7... control device, 10... substrate processing apparatus, 101... TiN film, 102... SiN film, 201... TiSiN film, 202... recess, L1... Ti source gas supply line, L2... Si source gas supply line, L3... NH ３ Gas supply line, L4...purge line, L5...junction pipe

Claims

1. A substrate processing method for forming a TiSiN film by stacking a titanium nitride film and a silicon nitride film on a surface of a substrate, comprising: (a) preparing the substrate on a stage in a processing vessel; (b) alternately supplying a Ti raw material gas containing a Ti raw material and a nitriding gas into the processing vessel X times to form the titanium nitride film; (c) supplying a Si raw material gas containing a Si raw material and a nitriding gas into the processing vessel, and supplying the Si raw material gas at least Y times to form the silicon nitride film; and (d) performing (b) and (c) in this order Z times, wherein X and Z are integers equal to or greater than 1, and Y is an integer equal to or greater than 2.

2. A substrate processing method for forming a TiSiN film having a titanium nitride film and a silicon nitride film stacked on a surface of a substrate, comprising: (a) preparing the substrate on a stage in a processing vessel; (b) alternately supplying a Ti raw material gas containing a Ti raw material and a nitriding gas into the processing vessel X times to form the titanium nitride film; (c) supplying a Si raw material gas containing a Si raw material and a nitriding gas into the processing vessel, and supplying the Si raw material gas at least Y times to form the silicon nitride film; and (d) performing (b) and (c) in this order Z times, wherein X, Y, and Z are integers equal to or greater than 1, and a time period for (c) is at least twice the time period for each time period for (b).

3. The substrate processing method according to claim 1, wherein in (c), the Si source gas and the nitriding gas are alternately supplied Y times.

4. The substrate processing method according to claim 1, wherein in (c), the Si source gas is supplied Y times and then the nitriding gas is supplied.

5. The substrate processing method according to any one of claims 1 to 4, wherein X is the number of times that the titanium nitride film becomes a continuous film.

6. The substrate processing method according to any one of claims 1 to 4, wherein X is 4 or more.

7. The substrate processing method according to any one of claims 1 to 4, wherein (b) and (c) are carried out by an ALD method.

8. The substrate processing method according to any one of claims 1 to 4, wherein a gap between a cover member of the stage and an annular protrusion of a shower head facing the stage is 0.5 mm or less.

9. The Ti source gas is TiCl ４ or TiBr ４ The substrate processing method according to any one of claims 1 to 4, wherein the substrate processing method is any one of the following:

10. The Si source gas is SiH ４ , Si ２ H ６ , SiH ２ C ２ or SiCl ４ The substrate processing method according to any one of claims 1 to 4, wherein the substrate processing method is any one of the following:

11. The nitriding gas is NH ３ , N ２ H ４ , NH(CH ３ ) ２ Or N ２ H ３ CH ３ The substrate processing method according to any one of claims 1 to 4, wherein the substrate processing method is any one of the following:

12. A substrate processing apparatus having a control section, the substrate processing apparatus executing the substrate processing method according to any one of claims 1 to 4 under the control of the control section.

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