Method for forming film on substrate and apparatus for forming film on substrate

Abstract

To suppress an effect on a film thickness of a metal film caused by transfer between processing containers when a metal nitride film and a metal film are respectively formed in different processing containers.SOLUTION: A method for forming a metal film includes steps of: supplying, in a first processing container, a metal source gas containing chlorine and a reaction gas containing nitrogen to the substrate to form a metal nitride film; subsequently, in the first processing container, supplying a processing gas containing ammonia gas or oxygen gas to the substrate to perform post-treatment; holding the substrate subjected to the post-treatment on a substrate holding portion heated to 300°C or more and transferring the substrate from the first processing container to a second processing container in which formation of the metal film is performed; and forming, in the second processing container, the metal film on a surface side of the metal nitride film.SELECTED DRAWING: Figure 6A

Description

[Technical Field]

[0001] The present disclosure relates to a method for depositing a film on a substrate and an apparatus for depositing a film on a substrate. [Background technology]

[0002] For example, when depositing a metal film such as Ru (ruthenium) on a substrate by CVD, a metal nitride film may be deposited first to improve the adhesion of the metal film, and then another metal film may be deposited on the surface of the metal nitride film. In order to perform such film depositions continuously without exposing the substrate to the atmosphere, it is known that the substrate is transported between each processing chamber via a vacuum transfer module connected to each processing chamber for depositing the metal film and the metal nitride film.

[0003] Patent Document 1 describes a vacuum transfer chamber configured to connect multiple chambers and transfer wafers to each chamber, and describes the formation of a Ru film on a TiN (titanium nitride) film, which is a metal nitride film. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2018-014477 Summary of the Invention [Problem to be solved by the invention]

[0005] The present disclosure provides a technique that can suppress the influence of transfer between processing vessels on the thickness of a metal film when a metal nitride film and a metal film are formed in different processing vessels. [Means for solving the problem]

[0006] The method for forming a metal film according to the present disclosure includes: supplying a chlorine-containing metal source gas and a nitrogen-containing reaction gas to the substrate in a first processing vessel to form a metal nitride film; Then, a process gas containing ammonia gas or oxygen gas is supplied to the substrate in the first process container to perform post-processing; holding the post-processed substrate on a substrate holder heated to 300° C. or higher and transporting the substrate from the first processing chamber to a second processing chamber in which a metal film is formed; forming the metal film on a surface side of the metal nitride film in the second processing chamber; Includes: [Effects of the Invention]

[0007] According to the present disclosure, when a metal nitride film and a metal film are formed in different processing chambers, the influence of transfer between the processing chambers on the thickness of the metal film can be suppressed. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a plan view illustrating a film forming apparatus according to a first embodiment. [Figure 2] FIG. 2 is a vertical cross-sectional side view showing a processing module of the film forming apparatus. [Figure 3] 10 is a vertical cross-sectional side view showing the transfer operation of the substrate W by the transport arm. FIG. [Figure 4] FIG. 2 is a plan view showing a substrate holding portion of the transfer arm. [Figure 5A] 2A to 2C are schematic diagrams showing the surface of a substrate that changes due to film formation in the first embodiment. [Figure 5B] 2A to 2C are schematic diagrams showing the surface of a substrate that changes due to film formation in the first embodiment. [Figure 5C] 2A to 2C are schematic diagrams showing the surface of a substrate that changes due to film formation in the first embodiment. [Figure 6A] 10A and 10B are schematic diagrams showing the surface of a substrate that changes due to film formation in a second embodiment. [Figure 6B] 10A and 10B are schematic diagrams showing the surface of a substrate that changes due to film formation in a second embodiment. [Figure 7A] 10A and 10B are schematic diagrams showing the surface of a substrate that changes due to film formation in a third embodiment. [Figure 7B] 10A and 10B are schematic diagrams showing the surface of a substrate that changes due to film formation in a third embodiment. [Figure 8A] 10 is an image showing the distribution of sheet resistance on the wafer surface in Experiment 1. [Figure 8B] 10 is an image showing the distribution of sheet resistance on the wafer surface in Experiment 2. [Figure 8C] 10 is an image showing the distribution of sheet resistance on the wafer surface in Experiment 3. [Figure 9] 10 is a graph showing standard film thickness values ​​for each Ru film at a diameter position in Experiments 1 to 3. [Figure 10A] 10 is an image showing the distribution of sheet resistance on the wafer surface in Experiment 4. [Figure 10B] 10 is an image showing the distribution of sheet resistance on the wafer surface in Experiment 5. [Figure 11] 10 is a graph showing standard film thickness values ​​at diameter positions of each Ru film in Experiments 4 and 5. DETAILED DESCRIPTION OF THE INVENTION

[0009] (First embodiment) Fig. 1 is a plan view illustrating a film formation apparatus according to this embodiment. The film formation apparatus 1 shown in Fig. 1 is configured to form a metal film after forming a metal nitride film to improve adhesion of the metal film on a substrate W. The film formation apparatus 1 is configured as a multi-chamber vacuum processing system including a processing module 101 for forming the metal nitride film, a processing module 102 for forming the metal film, and a vacuum transfer chamber 24 for transferring the substrate W between these modules.

[0010] The film forming apparatus 1 also includes an atmospheric pressure transfer chamber 22, the interior of which is maintained under atmospheric pressure. A load port 21 is installed in front of the atmospheric pressure transfer chamber 22, for example, to transfer the substrate W to and from a transfer container C accommodating the substrate W. A door 27 is installed on the front wall of the atmospheric pressure transfer chamber 22, and is opened when the substrate W is transferred into or out of the transfer container C. A transfer arm 25 is also installed inside the atmospheric pressure transfer chamber 22, for transferring the substrate W. When viewing the atmospheric pressure transfer chamber 22 from the load port 21 side, an alignment chamber 26 is installed on the left wall of the atmospheric pressure transfer chamber 22, for adjusting the orientation and eccentricity of the substrate W.

[0011] Two load lock chambers 23, lined up on the left and right, are connected to the wall of the atmospheric pressure transfer chamber 22 opposite the load port 21. The load lock chambers 23 have the function of switching the internal atmosphere between an atmospheric pressure atmosphere and a vacuum atmosphere while accommodating a substrate W. When viewed from the atmospheric pressure transfer chamber 22, a vacuum transfer chamber 24 is disposed at the rear of these load lock chambers 23. The atmospheric pressure transfer chamber 22 and the vacuum transfer chamber 24 are connected to each load lock chamber 23 via a gate valve 29.

[0012] An exhaust mechanism (not shown) is connected to the vacuum transfer chamber 24 to create a vacuum atmosphere within the interior space, and a transfer arm 28 is provided therein. One processing module 101 and three processing modules 102 are connected to the sidewall of the vacuum transfer chamber 24, lined up in this order clockwise. In this example, the processing module 101 is configured to deposit a TiN (titanium nitride) film corresponding to a metal nitride film, and the processing module 102 is configured to deposit a Ru (ruthenium) film corresponding to a metal film. The transfer of the substrate W between the processing modules 101, 102 and each load lock chamber 23 is performed by the transfer arm 28 as described below.

[0013] The film forming apparatus 1 includes a control unit 20, which is a computer, and the control unit 20 includes a program. The program incorporates instructions (steps) for carrying out the above-described processing of the substrate W and the transport process of the substrate W. The program is stored in a storage medium, such as a compact disc, a hard disk, a DVD, or a nonvolatile memory, and is read from the storage medium and installed in the control unit 20.

[0014] The control unit 20 uses the program to output control signals to each part of the film forming apparatus 1, thereby controlling the operation of each part. Specifically, the control unit 20 controls operations such as opening and closing of each gate valve 29, operation of the transfer arms 25 and 28, operation of the exhaust mechanism, switching of the pressure inside the load lock chamber 23, and each operation in the processing modules 101 and 102, which will be described later.

[0015] Regarding the transfer path of the substrate W in the film formation apparatus 1, the substrate W is first transferred in the order of transfer container C → load port 21 → atmospheric pressure transfer chamber 22 → load lock chamber 23 → vacuum transfer chamber 24 → processing module 101. Then, the substrate W on which the TiN film has been formed in the processing module 101 is transferred in the order of processing module 101 → vacuum transfer chamber 24 → any of the processing modules 102. The substrate W on which the Ru film has been formed in the processing module 102 is transferred in the order of processing module 102 → vacuum transfer chamber 24 → load lock chamber 23 → atmospheric pressure transfer chamber 22, and then returned to the transfer container C.

[0016] Next, the processing modules 101 and 102 will be described with reference to the longitudinal side view of FIG. 2, which shows an example of the configuration of the processing module 101. The processing module 101 is, for example, an apparatus for forming a TiN film by ALD (Atomic Layer Deposition). The processing vessel (first processing vessel) 51 of the processing module 101 is made of, for example, aluminum. A transfer port for a substrate W is formed in a sidewall of the processing vessel 51, and a gate valve G1 for opening and closing the transfer port is provided. An exhaust pipe 52, the upstream end of which forms an exhaust hole 52a, is connected to the bottom of the processing vessel 51, and a pressure control valve, for example, an APC valve (not shown), is provided in the exhaust pipe 52. An exhaust mechanism 52b is provided at the downstream end of the exhaust pipe 52.

[0017] A substrate mounting table 55 is provided inside the processing vessel 51 and is mounted on a support member provided at the bottom of the processing vessel 51. The substrate mounting table 55 supports the substrate W mounted thereon and horizontally, and has a heater 56 embedded therein for heating the mounted substrate W. The heater 56 generates heat when supplied with power from a power supply (not shown), and heats the substrate W mounted on the substrate mounting table 55 to a temperature of, for example, 300°C or higher, specifically, within a range of 380°C to 460°C.

[0018] Three support pins 58 (only two shown) are provided below the substrate mounting table 55 in the processing vessel 51 so as to be movable up and down by an elevating mechanism 59 provided below the processing vessel 51. The support pins 58 are inserted into through-holes in the substrate mounting table 55 at the transfer position and protrude and retract relative to the upper surface of the substrate mounting table 55, thereby enabling the transfer of the substrate W between the transfer arm 28 of the vacuum transfer chamber 24 shown in FIG.

[0019] 2, a shower head 61 is provided at the top of the processing vessel 51 to close the top opening of the processing vessel 51. The shower head 61 is disposed in the processing vessel 51 so as to face the substrate mounting table 55, and the interior thereof forms a gas diffusion space 62. A shower plate 63 having a plurality of through holes formed therein is provided below the shower head 61 so as to uniformly release various gases toward the surface of the substrate W. A gas discharge hole 64 is formed in the center of the top of the shower head 61, to which a gas supply mechanism 7 (described later) is connected.

[0020] The gas supply mechanism 7 includes a metal source gas supply unit 71 configured to supply a metal source gas, and a reactive gas supply unit 72 configured to supply a reactive gas. The metal source gas is a gas containing a metal and chlorine, such as TiCl4 (titanium tetrachloride) gas. The reactive gas is a gas containing nitrogen, such as NH3 (ammonia) gas.

[0021] The metal source gas supply unit 71 includes a metal source gas supply source 73 and a supply path 74, and the reactive gas supply unit 72 includes a reactive gas supply source 75 and a supply path 76. The supply paths 74 and 76 are respectively provided with flow rate adjusters M1 and M2 and valves V1 and V2 from the upstream side, and are joined at their downstream sides and connected to the gas outlet hole 64. A purge gas supply unit (not shown) configured to supply a purge gas such as an inert gas is preferably provided downstream of the supply paths 74 and 76. Thus, the metal source gas supply unit 71, the reactive gas supply unit 72, and the purge gas supply unit are configured to supply the metal source gas, the reactive gas, and the purge gas individually into the processing vessel 51. Specifically, the metal source gas and the reactive gas are alternately supplied via the supply of the purge gas.

[0022] The processing module 102 has a configuration generally similar to that of the processing module 101 described above, and therefore only a brief description will be given of the differences from the processing module 101. The processing module 102 includes a processing vessel (second processing vessel) similar to the processing vessel 51, and is configured to form a Ru film by thermal CVD.

[0023] In the gas supply mechanism, for example, the reactive gas supply unit is configured to supply CO (carbon monoxide) gas, and a Ru raw material gas supply unit is provided instead of the metal raw material gas supply unit. The Ru raw material gas supply unit supplies, for example, Ru3(CO) 12 The processing chamber is configured to supply a Ru source gas such as (dodecacarbonyltriruthenium) gas into the processing chamber. The gas supply mechanism supplies the Ru source gas and CO gas, for example, simultaneously. A heater provided on the substrate mounting table heats the substrate W to a temperature in the range of, for example, 150°C to 200°C.

[0024] Fig. 3 is a longitudinal side view showing the transfer operation of a substrate W by a transfer arm 28 and support pins 58 according to the present disclosure, and Fig. 4 is a plan view showing a substrate holder 31a according to the present disclosure. The transfer arm 28 is composed of a tip arm section 31 having a substrate holder 31a formed at its tip, a swivel arm section 32, a main body section 33, and a rotary shaft section 34 that rotatably connects these. The transfer arm 28, which is a so-called SCARA (Selective Compliance Assembly Robot Arm) type substrate transfer mechanism, moves the substrate holder 31a supporting the substrate W in the X and Y directions and rotates it in the XY plane. An intermediate arm section (not shown in Fig. 3) is provided between the tip arm section 31 and the swivel arm section 32.

[0025] As shown in Fig. 4, the substrate holder 31a has, for example, a bifurcated fork shape in a plan view so as to support the peripheral edge of the disk-shaped substrate W. As shown in Fig. 3, the substrate holder 31a is positioned above the substrate mounting table 55 while supporting the substrate W, and then the support pins 58 protrude to support the central side of the substrate W, thereby transferring the substrate W. The substrate W is received from the substrate mounting table 55 by positioning the substrate holder 31a below the substrate W supported by the protruding support pins 58 of the processing modules 101, 102, and displacing the support pins 58 to their downward positions.

[0026] Two heaters (heating units) 35, each made of, for example, a sheet-like resistance heating element, are attached to the underside of the substrate holding unit 31a. Specifically, each heater 35 is attached in an area capable of heating the entire contact area of ​​the substrate holding unit 31a with the substrate W to approximately the same temperature, and specifically, is arranged to cover the entire contact area with the substrate W. Each heater 35 is connected to an external power supply 37 via wiring 36 extending from the distal arm unit 31 to the main body unit 33. The external power supply 37 supplies power to the heaters 35 under the control of the control unit 20, and the substrate holding unit 31a is heated to 300°C or higher, specifically, 380°C to 460°C. In this way, the heating temperature of the substrate holding unit 31a is preferably set to a temperature similar to that of the substrate mounting table 55 of the processing module 101 immediately after TiN film formation.

[0027] Before describing the method for forming a TiN film and a Ru film using the film formation apparatus 1 of the present disclosure having the above-described configuration, the problem to be solved by the present disclosure will be described in detail. The inventors have been studying a method for improving the uniformity of the film thickness within the surface of a substrate W when forming a Ru film. In this study, they analyzed the technical key to improving the uniformity of the film thickness, believing that it resides in the film formation conditions of the Ru film. However, when RS measurement (sheet resistance measurement) was performed on a substrate W on which a Ru film had been formed, it was confirmed that the Ru film was relatively thin in the contact region with the substrate holder 31a (FIGS. 8A and 9). Therefore, the inventors believed that the key to improving the uniformity of the Ru film thickness lies in the transfer by the transfer arm 28, and proceeded with the following study.

[0028] Immediately after the TiN film is formed, the substrate W before being transferred to the transfer arm 28 is heated by the heater 56 provided on the substrate mounting table 55 to a relatively high temperature for forming the TiN film (for example, a temperature in the range of 380°C to 460°C). On the other hand, the conventional transfer arm 28 is not provided with a heater as in the present disclosure, and the temperature of the substrate holding part 31a is lower than that of the substrate W immediately after film formation. Therefore, during the transfer period from when the substrate W is transferred to the substrate holding part 31a in the process module 101 where the TiN film is formed until when the substrate W is transferred to the substrate mounting table 55 of the process module 102 where the Ru film is formed, the substrate W is partially cooled by the substrate holding part 31a.

[0029] It is assumed that molecules derived from the metal source gas, reactive gas, and molecules resulting from their chemical reactions are distributed uniformly across the surface of the substrate W immediately after the TiN film is formed. The inventors have recognized that Cl residues in TiCl4 derived from the metal source gas (hereinafter, also referred to as "Cl-containing molecules" because they contain chlorine and constitute the metal source gas) have properties that inhibit the growth of the Ru film. The inventors have also recognized that such Cl-containing molecules are difficult to decompose below the thermal decomposition temperature of Cl, e.g., 300°C, making it difficult for Cl residues to desorb from the surface of the substrate W. In regions of the substrate W where Cl residues exist, the growth of the Ru film may be slowed. Based on the above, the inventors have inferred that the temperature of the substrate decreases in the contact region with the substrate holder 31a, which is relatively low, and the Cl residues are suppressed from desorbing, leaving a relatively large amount of Cl residues remaining, resulting in a relatively thin Ru film being subsequently formed compared to other regions.

[0030] If such a partially cooled region were not formed on the substrate W, the Cl-containing molecules derived from the metal source gas would be uniformly desorbed from the surface of the substrate W over time, maintaining a more uniform distribution within the surface while reducing the amount of Cl residues per unit area. If the Cl residues are distributed generally uniformly within the surface, the in-plane thickness uniformity of the Ru film subsequently formed would also be improved. The film formation apparatus 1 and film formation method using the same described below were developed based on the above findings. Figures 5A to 5C are schematic diagrams showing the surface of the substrate W changing during the film formation process of the TiN film and Ru film of the present disclosure. These figures and Figures 2 to 4 will be used to explain the process.

[0031] First, the formation of the TiN film 11 in the processing module 101 will be described. The gas supply mechanism 7 alternately supplies a metal source gas and a reactive gas multiple times onto, for example, a Si (silicon)-containing layer 10 constituting the surface of the substrate W to be processed, thereby forming the TiN film 11. Thereafter, a processing gas is supplied to the TiN film 11 (solid arrows in FIG. 5A). In this example, the processing gas is a gas containing NH3, which is the same as the reactive gas. Therefore, the processing gas is supplied by the reactive gas supply unit 72. Thus, in the film formation method disclosed herein, immediately after the TiN film 11 is formed, the processing gas is supplied to the surface of the substrate W in the same processing chamber 51 in which the TiN film 11 was formed. As a result, immediately after the TiN film 11 is formed, some of the Cl-containing molecules distributed approximately uniformly on the surface of the substrate W react with NH3 molecules and are uniformly desorbed and removed as reactive molecules R from the surface of the substrate W (FIG. 5A). Therefore, the Cl residues present on the surface of the TiN film 11 are uniformly reduced across the surface of the substrate W. The reactive molecule R contains Cl and at least one of N (nitrogen) and H (hydrogen), and is assumed to be, for example, NH4Cl (ammonium chloride).

[0032] This reduces the total amount of Cl residues on the surface of the substrate W, so that even if a partial low-temperature region is formed on the surface of the substrate W during loading and unloading as shown in the comparative example, the difference in the progress of desorption of Cl residues from the surface of the TiN film 11 due to the temperature difference can be made relatively small. As a result, it is presumed that the difference in film thickness of the Ru film to be subsequently formed within the surface of the substrate W will be relatively reduced.

[0033] Next, as shown in FIG. 5B , the substrate W, with the process gas supplied to the TiN film 11, is placed on a substrate holder 31a heated by a heater 35 to a temperature approximately equal to that of the substrate support table 55, and then transported. This prevents a temperature drop in the contact area of ​​the substrate W held by the heated substrate holder 31a, allowing the temperature to be maintained at approximately the same level as during the formation of the TiN film 11. By preventing a temperature drop in the contact area of ​​the substrate W with the substrate holder 31a, as shown in the comparative example, during transport from process module 101 to process module 102, the Cl-containing molecules M in the contact area are desorbed in the same manner as in other areas, thereby reducing Cl residues in the same manner as in other areas ( FIG. 5B ). Furthermore, by maintaining the temperature of the entire TiN film 11 during transport at a temperature at which the decomposition of the Cl-containing molecules can proceed, the desorption of the Cl-containing molecules M from the entire surface of the TiN film 11 can proceed more uniformly across the surface of the substrate W.

[0034] As shown in FIG. 5C, a substrate W transported to the processing module 102 is supplied with a Ru source gas, and a Ru film 12 is formed on the TiN film 11. As described above, the number of Cl residues per unit area on the surface of the TiN film 11 is reduced by processing the substrate W with a processing gas containing NH3, and the Cl residues are distributed approximately uniformly within the surface of the substrate W by heating the substrate holder 31a. Therefore, the Cl residues on the surface of the TiN film 11 are less likely to inhibit film formation, and the Ru film 12 grows efficiently and has an approximately uniform film thickness within the surface of the substrate W. This improves the uniformity of the film thickness and film formation efficiency of the Ru film 12 formed on the TiN film 11 (FIG. 5C).

[0035] 1 and 2, the operation of the film formation apparatus 1 that performs a series of processes in the substrate film formation method of this embodiment described above will be described. In the vacuum transfer chamber 24, the substrate holder 31a of the transfer arm 28 is heated to a predetermined temperature by the heater 35, and the inside of the vacuum transfer chamber 24 is set to a vacuum atmosphere of a predetermined pressure. In each of the process modules 101 and 102, the substrate mounting table 55 is heated to a predetermined temperature, and the inside of the process container 51 is adjusted to a predetermined vacuum atmosphere by the exhaust mechanism 52b.

[0036] First, the transfer arm 28 in the vacuum transfer chamber 24 receives the substrate W, on whose surface the aforementioned Si-containing layer 10 is exposed, from the load lock chamber 23 shown in Fig. 1 and transfers the substrate W toward the processing module 101. Then, the gate valve G1 of the processing module 101 is opened, and the transfer arm 28 causes the substrate W to enter the processing vessel 51 through the loading port. Then, the substrate W is delivered to the substrate mounting table 55, and the transfer arm 28 is withdrawn from the processing vessel 51, and the gate valve G1 is closed.

[0037] In the processing vessel 51, a metal source gas and a reactive gas are supplied to form the TiN film 11 (a process of forming a metal nitride film) while adjusting the pressure inside the processing vessel 51 and the temperature of the substrate mounting table 55 as described above in accordance with the film formation recipe for the TiN film 11. At this time, the gases are alternately supplied from the shower head 61 to the surface of the substrate W.

[0038] Next, a processing gas is supplied to the substrate W in the processing vessel 51 of the processing module 101 (step of performing post-processing, FIG. 5A). In this example, the processing gas is supplied by supplying the final reactive gas (NH3 gas) in the TiN film formation process for a longer time than the reactive gas supply times in the other times. The final reactive gas supply time (process gas supply time) is, for example, 50 seconds or more, specifically, approximately 180 seconds. In this way, by supplying a gas of the same type as the reactive gas as the processing gas following the supply of the reactive gas, there is no need to consider gas replacement in the processing vessel 51, and the processing gas supply time can be relatively short. Furthermore, by using the same type of reactive gas and processing gas, the device configuration is simplified.

[0039] Before the supply of the processing gas, a large number of Cl-containing molecules derived from the metal source gas were uniformly distributed on the surface of the TiN film 11, but some of these molecules become reactive molecules R upon the supply of the processing gas and are desorbed from the surface of the substrate W. It is believed that the supply of the processing gas in this manner results in Cl residues on the surface of the TiN film 11 being distributed at a relatively low density and more uniformly on the surface of the substrate W (FIG. 5A).

[0040] After the TiN film formation and the supply of the processing gas are completed, the substrate W is transferred from the processing module 101 to the waiting processing module 102 by the transfer arm 28 equipped with the substrate holder 31a heated to approximately the same temperature as the TiN film 11 formation temperature (transfer step, FIG. 5B). During this transfer, the substrate W is transferred through the vacuum transfer chamber 24, which is insulated from the atmosphere by a vacuum, so that a temperature drop of the substrate W is suppressed. Meanwhile, because the substrate holder 31a is heated as described above, a temperature drop in the contact area of ​​the substrate W with the substrate holder 31a is prevented, and a temperature drop in the entire area is prevented. Therefore, even during transfer, desorption of Cl-containing molecules from the entire surface of the substrate W progresses, thereby maintaining a uniform distribution within the surface and reducing the amount of Cl residues (FIG. 5B).

[0041] In this manner, the substrate W is loaded into the processing module 102 in a state in which the amount of Cl residues remaining on the surface of the TiN film 11 is reduced and the distribution of the Cl residues is small. A Ru source gas is supplied to the substrate W placed on the substrate mounting table of the processing module 102 while adjusting the pressure in the processing chamber 51 and the temperature of the substrate mounting table in accordance with a film formation recipe for the Ru film 12, to form the Ru film 12 on the surface of the TiN film 11 (a process of forming a metal film). The Ru source gas is supplied to the surface of the TiN film 11 in the same manner as when forming the TiN film 11. Since the Ru film 12 is supplied onto the surface of the TiN film 11, where the Cl residues that inhibit the growth of Ru are relatively small and the distribution is small, the Ru film 12 is formed relatively quickly and more uniformly within the surface of the substrate W ( FIG. 5C ).

[0042] As described above, according to the film formation method and film formation apparatus of the present disclosure, supplying a processing gas after forming a TiN film can reduce Cl residues that inhibit the growth of a Ru film. Then, transporting the substrate W from processing module 101 to processing module 102 using the transport arm 28 with the substrate holder 31a heated prevents the TiN film 11 from being partially cooled during transport, and promotes further desorption of Cl-containing molecules throughout the entire film. Supplying a Ru source gas to the TiN film 11 with reduced Cl residues in this manner allows the Ru film 12 to grow quickly and suppresses non-uniformity in film thickness.

[0043] In each semiconductor chip manufactured using such a substrate W, the Ru film 12 is formed to approximately the same thickness and at the same growth rate within the surface of the substrate W, so that the electrical performance such as the same resistance value and resistivity can be achieved at any position in the conductive path formed by the Ru film 12. As a result, the electrical performance can be stabilized between each semiconductor chip.

[0044] In the film formation method according to the above embodiment, the processing gas is supplied for 50 seconds or more, specifically, for about 180 seconds. However, it is known that even if the processing gas supply time is further increased, it is difficult to remove all of the Cl residues, and a certain proportion of the Cl residues remain. In such a case, the distribution of the Cl residues can be further reduced by using the film formation method according to the third embodiment described below.

[0045] (Second embodiment) 6A and 6B are schematic diagrams showing the surface of the substrate W that changes according to the film formation method of the second embodiment. The process module 101 in the second embodiment is configured to supply a process gas containing O2 (oxygen) gas that is different from the reactive gas (NH3 gas). Therefore, the gas supply mechanism 7 further includes a process gas supply unit configured to supply a process gas containing O2 gas, and supplies the process gas into the process vessel 51 of the process module 101 after the formation of the TiN film 11 is completed. The process gas supply unit may have a supply path that merges with the supply path 74 of the metal source gas supply unit 71, similar to the reactive gas supply unit 72, or may be separated from the supply path 74 and supply a second process gas directly into the process vessel 51.

[0046] In the second embodiment, the processing gas is supplied to a substrate W having a TiN film 11 formed on its surface in a processing module 101 (step of performing post-processing, FIG. 6A). As a result, after the final supply of reactive gas for TiN film formation, a portion of the Cl residues distributed in large numbers on the surface of the TiN film 11 are replaced with oxygen in the processing gas and removed as Cl-containing molecules Ma. The Cl-containing molecules Ma contain chlorine, such as HCl (hydrogen originates from hydrogen residues on the surface of the TiN film 11). Then, a TiON film 13 is formed on the surface side of the TiN film 11 by replacing the Cl residues with oxygen. The elemental composition ratio of the TiON film 13 varies depending on the density of the Cl residues and the degree of reaction.

[0047] The processing gas is supplied for, for example, 10 seconds or more, specifically, about 30 seconds, sufficient to replace almost all of the Cl residues distributed on the TiN film 11 before the supply. This processing gas removes the Cl residues on the TiN film 11 more uniformly within the surface, and a TiON film is formed uniformly on the TiN film 11. It has been found that the TiON film has a smaller effect of inhibiting the growth of the Ru film 12 than the Cl residues. This improves the film formation efficiency of the Ru film 12 while maintaining a uniform thickness within the surface of the Ru film 12 formed on the substrate W transported by the heated substrate holder 31a (FIG. 6B).

[0048] (Third embodiment) The gas supply mechanism 7 of the processing module 101 in the third embodiment further includes a second processing gas supply unit for supplying a second processing gas containing O gas, where the first processing gas is the NH gas-containing processing gas in the first embodiment. After the first processing gas is supplied, the second processing gas is supplied into the processing chamber 51 of the processing module 101.

[0049] In the processing module 101, a first processing gas is supplied as a first post-processing to the substrate W (FIG. 5A) from which some of the Cl-containing molecules have been more uniformly removed within the surface, and a second processing gas is then supplied as a second post-processing (steps for performing the first and second post-processing, FIG. 7A). As a result, Cl residues on the surface of the TiN film 11, which have been reduced by the supply of the first processing gas, are further replaced with oxygen from the second processing gas and removed as Cl-containing molecules Ma. Then, a relatively thin TiON film 13 is formed on the surface side of the TiN film 11 by the Cl residues, which have been reduced by the supply of the first processing gas, being replaced with oxygen from the second processing gas.

[0050] The second process gas is preferably supplied long enough to replace almost all of the Cl residues remaining before the supply, for example, for 10 seconds or more, specifically, about 30 seconds, as in the second embodiment. By supplying the first and second process gases as described above, almost all of the Cl residues on the TiN film 11 are removed, thereby further improving the film formation efficiency of the Ru film 12 while ensuring uniformity of the film thickness of the Ru film 12 formed on the TiN film 11 ( FIG. 7B ). In other words, when the film formation conditions for the Ru film 12 are the same, the Ru film 12 formed by the film formation according to the third embodiment is thicker than the Ru film 12 formed by the film formation according to the first embodiment.

[0051] In this film formation method, since almost all Cl residues on the surface of the TiN film 11 are removed in the processing vessel 51 of the processing module 101, the film is less susceptible to the effect of the temperature reduction caused by the substrate holder 31a. Therefore, in the third embodiment, even if the substrate W is transported from the processing module 101 to the processing module 102 by an unheated transfer arm 28, the thickness of the Ru film 12 can be made uniform (FIGS. 10B and 11). However, it goes without saying that the substrate W may also be transported from the processing module 101 to the processing module 102 by a heated transfer arm 28.

[0052] (Variation) The post-processing method of the present disclosure is not limited to the supply of the first process gas containing NH3 gas and the second process gas containing O2 gas, as described above. For example, instead of supplying NH3 gas, O2 gas may be supplied as the process gas to reduce Cl residues on the TiN film 11. In this case, it is sufficient if the increase in resistance due to the TiON film 13 is within an acceptable range. Alternatively, NH3 gas may be supplied after O2 gas is supplied.

[0053] Furthermore, the supply of NH3 gas or O2 gas is not an essential condition. For example, a configuration may be adopted in which the entire area of ​​the TiN film 11 on the substrate W transported by the transport arm 28 is maintained at a uniform temperature by heating the substrate holder 31a with the heater 35. Even in this case, the effect of more uniformly forming the Ru film 12 on the surface of the substrate W can be achieved by more uniformly desorbing the Cl-containing molecules within the surface.

[0054] In the formation of the TiN film 11 and the Ru film 12 according to the present disclosure, the TiN film 11 and the Ru film 12 are formed on the flat surface of the Si-containing layer 10, but the present disclosure is not limited thereto. The TiN film 11 may be formed on the surface of the Si-containing layer 10 on which a plurality of recesses have been formed in advance by etching, and then the Ru film 12 may be formed to fill the recesses. In the present disclosure, before the formation of the TiN film 11, a COR (Chemical Oxide Removal) and PHT (Post Heat Treatment) process may be performed to remove a native oxide film formed on the surface of the Si-containing layer 10.

[0055] Furthermore, in forming the TiN film and the Ru film according to the present disclosure, various gases are uniformly supplied to the surface of the substrate W by the shower head 61. However, the supply of various gases is not limited to being supplied by the shower head 61. As an example, various gases may be supplied to the surface of the substrate W by arranging supply holes for the various gases at, for example, multiple locations above the periphery of the substrate W and providing an exhaust port above the center of the substrate W.

[0056] The metal nitride film is not limited to a TiN film, but may be another metal nitride film formed by supplying a metal source gas containing a metal and chlorine and a reactive gas that reacts with the metal source gas. A specific example of this metal nitride film is a SiN (SiN) film formed by supplying SiH2Cl2 gas as the metal source gas and NH3 gas as the reactive gas. The metal film is not limited to a Ru film, but may be another metal film with a relatively low resistivity. In this case, the other metal film is expected to contain at least one metal, such as Al (aluminum), copper (Cu), W (tungsten), Ti (titanium), silver (Ag), or Mo (molybdenum), as a component. In this case, a gas containing the respective metal is supplied as the metal source gas, and a reactive gas is supplied as needed. [Example]

[0057] (experiment) We investigated the uniformity of the thickness of the Ru film on the TiN film and the film formation efficiency depending on whether or not the post-treatment of the present disclosure was performed, and whether or not the heating and transport was performed. For this purpose, we measured the sheet resistance of each wafer surface on which a TiN film and a Ru film were formed under the following experimental conditions, and calculated the thickness of the Ru film corresponding to the sheet resistance. Based on this, we confirmed the uniformity of the thickness of the Ru film and the film formation efficiency for each experimental condition.

[0058] A. Experimental conditions Five unpatterned, flat bare wafers were prepared. TiN and Ru films were formed on the surface of each bare wafer using the same recipe as in the embodiment. In Experiment 1, as in the comparative example, no post-processing was performed on the wafers after the TiN film was formed. In Experiment 2, NH3-containing gas was supplied to the wafers after the TiN film was formed as a post-processing. For Experiments 1 and 2, the wafers were transported through a vacuum transfer chamber at room temperature using an unheated substrate holder 31a. In Experiment 3, as in the embodiment, NH3-containing gas was supplied to the wafers after the TiN film was formed, and the wafers were transported through a vacuum transfer chamber at room temperature using a heated substrate holder 31a.

[0059] In Experiment 4, O gas was supplied to the wafer after TiN film formation, and the wafer was transported through a vacuum transfer chamber at room temperature using an unheated substrate holder 31a. In Experiment 5, similar to the third embodiment, NH gas was supplied to the wafer after TiN film formation, and then O gas was supplied, and the wafer was transported through a vacuum transfer chamber at room temperature using an unheated substrate holder 31a.

[0060] B. Experimental Results (1) Figures 8A to 8C are images showing the distribution of sheet resistance on the wafer surface in Experiments 1 to 3. As shown in Figures 8A to 8C, the resistivity of the Ru film is relatively low, so the level of sheet resistance corresponds to the thickness of the Ru film. Figure 9 is a graph showing the standard film thickness values ​​at the diameter positions of each Ru film in Experiments 1 to 3. The standard film thickness values ​​in Figure 9 are standard values ​​calculated from the sheet resistance at each center position ranging from -r to +r shown in Figures 8A to 8C, with the film thickness at the center position of each wafer set to 1. Note that a notch is provided at the +r position.

[0061] According to the sheet resistance distribution of the wafer in Experiment 1 (no post-processing, no heating of the substrate holder 31a) shown in Figure 8A, the sheet resistance was clearly high in the contact area of ​​the substrate holder 31a (see Figure 4, positions A and B in Figure 8A), confirming that the Ru film was thin. The sheet resistance was relatively low inside (position b in the same figure) and outside (positions a and c in the same figure) of the contact area, confirming that the Ru film was relatively thick. As also shown in Figure 9, the film thickness on the +r side of the wafer center tended to be thicker overall than the film thickness on the -r side. The significantly thicker film thickness at the notched position on the +r side periphery is thought to be due to the influence of the exhaust gas flow during film formation.

[0062] According to the sheet resistance distribution of the wafer in Experiment 2 (no NH3 gas post-treatment, no heating of the substrate holder 31a) in Figure 8B, the film thickness in the contact area was relatively thin, as in Experiment 1. However, as shown in Figure 9, the tendency for the film thickness to be thicker on the +r side than at the center, as seen in Experiment 1, was not observed. This is thought to be because the supply of NH3 gas more uniformly reduced the Cl residue on the TiN film 11 across the surface of the substrate W, thereby achieving a uniform growth rate of the Ru film across the surface. According to the sheet resistance distribution of the wafer in Experiment 3 (with NH3 gas post-treatment, heating of the substrate holder 31a) in Figure 8C, the film thickness in the contact area was able to approach the film thickness in the central area, and it was found that the film thickness was uniform across the entire area.

[0063] These results confirm that the growth rate of the Ru film can be made uniform by uniformly reducing the Cl residue on the TiN film by NH3 gas within the surface. Furthermore, it was confirmed that the growth rate of the Ru film in the contact area can be promoted to the same level as that in the inner area of ​​the contact area by heating the substrate holder 31a.

[0064] (2) Figures 10A and 10B are images showing the distribution of sheet resistance on the wafer surface in Experiments 4 and 5. Figure 11 is a graph showing the standard film thickness values ​​for each Ru film diameter position in Experiments 4 and 5, along with the standard film thickness values ​​for Experiment 2 for comparison.

[0065] According to the sheet resistance distribution of the wafer in Experiment 4 (without O2 gas post-treatment and heating of the substrate holder 31a) shown in Figure 10A, the film thickness in the contact region was relatively thin, as in Experiment 2. This is thought to be because Cl residues remained even after the O2 gas was supplied, and more Cl residues remained in the contact region, which had become colder, than in the central region. Therefore, it was inferred that if the wafer was transported using a heated substrate holder 31a as in the second embodiment, the film thickness in the contact region could be made closer to the film thickness in the central region, as in Experiment 3, and the film thickness could be made uniform across the entire region.

[0066] The sheet resistance distribution in Experiment 4 was generally lower than that in Experiment 2, and the thickness of the Ru film was thicker across the entire area. This is presumably because the Cl residues distributed on the surface of the TiN film were replaced with oxygen, resulting in a relatively good growth efficiency of the Ru film on the TiON film formed on the TiN film surface. Furthermore, as shown in Figure 11, the film thickness inside the contact area was found to be more uniform compared to Experiment 2.

[0067] According to the sheet resistance distribution of the wafer in Experiment 5 (NH3 gas / O2 gas post-treatment, no heating of the substrate holder 31a) shown in Figure 10B, the sheet resistance in the contact area was almost the same as that in the central area, and the film thickness in the contact area was almost the same as that in the center (Figure 11). The sheet resistance distribution in Experiment 5 was even lower than that in Experiment 4. This is presumably because the TiON film, which has a higher resistivity than the Ru film, was thinner than in Experiment 4, and because the film formation efficiency was further improved by the post-treatment, making the Ru film thicker in the entire area.

[0068] The results of Experiments 4 and 5 above confirmed that post-treatment using O2 gas improves the Ru film deposition efficiency compared to post-treatment using NH3 gas. The results of Experiment 5 also confirmed that post-treatment using NH3 gas and O2 gas can further improve the Ru film deposition efficiency, suppress the growth inhibition of the Ru film in the low-temperature contact region, and effectively make the Ru film uniform.

[0069] It should be noted that the embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects, and various omissions, substitutions, modifications, and combinations may be made to the above-described embodiments without departing from the scope and spirit of the appended claims. [Explanation of symbols]

[0070] W substrate 11 TiN film 12 Ru membrane 31a Board holding part 51 Processing vessel

Claims

1. A method for depositing a film on a substrate, comprising: supplying a chlorine-containing metal source gas and a nitrogen-containing reaction gas to the substrate in a first processing vessel to form a metal nitride film; then, performing post-processing by supplying a processing gas containing ammonia gas or oxygen gas to the substrate in the first processing container; holding the post-processed substrate on a substrate holder heated to 300° C. or higher and transporting the substrate from the first processing chamber to a second processing chamber in which a metal film is formed; and forming the metal film on the surface side of the metal nitride film in the second processing chamber.

2. A method for depositing a film on a substrate, comprising: supplying a chlorine-containing metal source gas and a nitrogen-containing reaction gas to the substrate in a first processing vessel to form a metal nitride film; Next, performing a first post-processing step in which a first process gas containing ammonia gas is supplied to the substrate in the first process container, and a second post-processing step in which a second process gas containing oxygen gas is supplied to the substrate in the first process container; a step of holding the substrate that has been subjected to the first and second post-treatments on a substrate holder and transporting the substrate from the first treatment chamber to a second treatment chamber in which a metal film is formed; and forming the metal film on the surface side of the metal nitride film in the second processing chamber.

3. The method according to claim 1 or 2, wherein the metal nitride film is a titanium nitride film.

4. 4. The method of claim 3, wherein the metal source gas comprises titanium tetrachloride gas and the reaction gas comprises ammonia gas.

5. The method according to claim 1 or 2, wherein the metal film is a ruthenium film.

6. 6. The method of claim 5, wherein the ruthenium film is formed using a ruthenium source gas containing ruthenium dodecacarbonyltrioxide gas.

7. The method of claim 1 , wherein the substrate holder is provided with a heating element.

8. In an apparatus for forming a film on a substrate, a first processing chamber for forming a metal nitride film on the substrate; a second processing chamber for forming a metal film on the substrate; a substrate holder configured to be heated and to hold and transfer the substrate from the first processing vessel to the second processing vessel; a gas supply mechanism configured to supply into the first processing vessel a metal source gas containing chlorine, a reaction gas containing nitrogen, and a processing gas containing ammonia gas or oxygen gas; a control unit, the control unit is configured to output control signals to execute the following steps: a process step of supplying the metal source gas and the reaction gas to the substrate in the first processing vessel to form a metal nitride film; a process step of subsequently supplying the processing gas to the substrate in the first processing vessel to perform post-processing; a process step of transporting the substrate that has undergone the post-processing from the first processing vessel to the second processing vessel by the substrate holding unit heated to 300°C or higher; and a process step of forming the metal film on a surface side of the metal nitride film in the second processing vessel.

9. In an apparatus for forming a film on a substrate, a first processing chamber for forming a metal nitride film on the substrate; a second processing chamber for forming a metal film on the substrate; a substrate holder configured to hold the substrate and transfer it from the first processing vessel to the second processing vessel; a gas supply mechanism configured to supply into the first processing vessel a metal source gas containing chlorine, a reaction gas containing nitrogen, a first processing gas containing ammonia gas, and a second processing gas containing oxygen gas; a control unit, the control unit is configured to output control signals to execute the following process steps: a process step of supplying the metal source gas and the reaction gas to the substrate in the first process vessel to form the metal nitride film; a process step of subsequently performing a first post-process of supplying the first process gas to the substrate in the first process vessel and a second post-process of supplying the second process gas to the substrate in the first process vessel; a process step of holding the substrate that has been subjected to the first and second post-processes on the substrate holding unit and transferring it from the first process vessel to the second process vessel; and a process step of forming the metal film on a surface side of the metal nitride film in the second process vessel.

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