Method and apparatus for embedding ruthenium into recesses formed on a substrate surface

Abstract

To realize embedding of ruthenium while suppressing an increase in resistance for a recess formed on a substrate surface.SOLUTION: When embedding ruthenium in a recess formed on a substrate surface, gas containing a ruthenium compound, for example, Ru (PF3)4H2 that does not contain oxygen atoms and carbon atoms is supplied to the substrate in which metal is exposed on a bottom surface of the recess to form a ruthenium layer in an area including the bottom surface of the recess. Then, gas containing Ru3(CO)12 is supplied to the substrate and ruthenium is embedded in the recess so as to cover the ruthenium layer. A ruthenium raw material with a low specific resistance on an interface between the bottom surface of the recess and the metal and a ruthenium raw material for embedding with a low specific resistance are selected, ruthenium is embedded in the recess while switching these two types of ruthenium raw materials, therefore, ruthenium with the low resistance can be embedded in the recess.SELECTED DRAWING: Figure 4A

Description

[Technical Field]

[0001] The present disclosure relates to a method and apparatus for implanting ruthenium into recesses formed in a substrate surface. [Background technology]

[0002] In the manufacturing process of semiconductor devices, a process of forming a metal film on a semiconductor wafer, which is a substrate for manufacturing a semiconductor device, is performed, and a ruthenium film may be formed as the metal film. Patent Documents 1 and 2 disclose a process of filling recesses formed in a wafer with ruthenium. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2018-147949 [Patent Document 2] Japanese Patent Application Publication No. 2020-47864 Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides a technique that can embed ruthenium into recesses formed on the surface of a substrate while suppressing an increase in resistance. [Means for solving the problem]

[0005] The present disclosure provides a method for embedding ruthenium into a recess formed on a substrate surface, the method comprising: supplying a gas containing a ruthenium compound containing no oxygen atoms or carbon atoms as a ruthenium source to the substrate having metal exposed on the bottom surface of the recess, thereby forming a ruthenium layer in a region including the bottom of the recess; Next, Ru3(CO) was added to the substrate as a ruthenium source. 12and a step of supplying a gas containing ruthenium to fill the recessed portion with ruthenium so as to cover the ruthenium layer. [Effects of the Invention]

[0006] According to the present disclosure, it is possible to embed ruthenium in recesses formed on the surface of a substrate while suppressing an increase in resistance. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic plan view illustrating one embodiment of a ruthenium implanting device of the present disclosure. [Figure 2] FIG. 3 is a vertical cross-sectional side view showing an example of a first film formation processing unit provided in the apparatus. [Figure 3] FIG. 3 is a vertical cross-sectional side view showing an example of a second film formation processing unit provided in the apparatus. [Figure 4A] 1A-1C are first cross-sectional side views of a wafer surface according to a first embodiment of a process for implanting ruthenium of the present disclosure. [Figure 4B] FIG. 2 is a second longitudinal cross-sectional side view of the wafer surface. [Figure 4C] FIG. 10 is a third longitudinal side view of the wafer surface. [Figure 5A] 10 is a first longitudinal side view of a wafer surface according to a step of a second embodiment of the method. FIG. [Figure 5B] FIG. 2 is a second longitudinal cross-sectional side view of the wafer surface. [Figure 5C] FIG. 10 is a third longitudinal side view of the wafer surface. [Figure 6] FIG. 4 is a characteristic diagram showing the relationship between the film formation temperature and the film formation rate in the formation of a ruthenium layer. DETAILED DESCRIPTION OF THE INVENTION

[0008] In the manufacturing process of semiconductor devices, there is a step of forming recesses in an insulating film by etching, and then filling the recesses with a metal for wiring. With the miniaturization of semiconductor devices, ruthenium, a low-resistivity material, has attracted attention as a filling metal. This disclosure relates to a process for filling ruthenium into recesses formed on the surface of a semiconductor wafer (hereinafter referred to as "wafer"), which is a substrate.

[0009] <Film forming equipment> An embodiment of an apparatus (hereinafter referred to as a "film formation apparatus") for filling recesses formed on a wafer surface with ruthenium (Ru) will be described below with reference to Figures 1 and 2. Figure 1 is a schematic plan view showing an example of the configuration of a film formation apparatus 1. This film formation apparatus 1 is configured to include an atmospheric transfer chamber 11, a load lock chamber 12, a first substrate transfer chamber 13, a second substrate transfer chamber 14, a plurality of pre-treatment units 15, and a plurality of Ru film formation units 2.

[0010] The first substrate transfer chamber 13 and the second substrate transfer chamber 14 are each configured to have a rectangular shape in a plan view and are connected via, for example, two transfer units 17. The interiors of the first and second substrate transfer chambers 13, 14 and the transfer unit 17 are set to a vacuum pressure atmosphere, and the pressures are configured to be the same. The transfer unit 17 is configured to transfer wafers between the first transfer mechanism 131 provided in the first substrate transfer chamber 13 and the second transfer mechanism 141 provided in the second substrate transfer chamber 14.

[0011] The direction in which these substrate transfer chambers 13, 14 are lined up is the length direction, with the first substrate transfer chamber 13 on the front side and the second vacuum transfer chamber 14 on the rear side. In this case, an atmospheric transfer chamber 11 set to an atmospheric pressure atmosphere is connected to the front side of the first substrate transfer chamber 13 via, for example, three load lock chambers 12. Wafer transfer ports and gate valves for opening and closing the transfer ports are respectively located between the first and second substrate transfer chambers 13, 14 and the transfer unit 17, between the load lock chamber 12 and the first substrate transfer chamber 13, and between the load lock chamber 12 and the atmospheric transfer chamber 11, but are not shown in the figure.

[0012] For example, four load ports 101 are connected to the atmospheric transfer chamber 11, and a carrier C containing a plurality of wafers 10 is placed on each load port 101. The atmospheric transfer chamber 11 is provided with an atmospheric transfer mechanism 111, which can transfer wafers 10 between the carrier C connected to the atmospheric transfer chamber 11 and the load lock chamber 12.

[0013] For example, two pre-processing units 15 are connected to the remaining two walls of the first substrate transfer chamber 13. A first transfer mechanism 131 provided in the first substrate transfer chamber 13 is configured to transfer wafers 10 between these four pre-processing units 15, the transfer unit 17, and the load lock chamber 12. In FIG. 1, symbol GV1 indicates a gate valve.

[0014] In this example, the pretreatment unit 15 includes an etching unit 151 that performs COR (Chemical Oxide Removal) processing, a heating unit 152 that performs PHT (Post Heat Treatment) processing, and a Ti film formation unit 153 that forms a titanium (Ti) film to serve as a contact layer between the underlying silicon wafer. The COR processing, PHT processing, and Ti film formation processing correspond to pretreatments performed before ruthenium is embedded in recesses on the wafer surface. The COR processing and PHT processing are pre-cleaning processes that remove native oxide films (SiOx) formed on the silicon wafer surface and on the inner surfaces of the recesses.

[0015] The etching processing unit 151 is configured to perform an etching process (COR process) of the native oxide film using, for example, hydrogen fluoride (HF) gas and ammonia (NH3) gas. The heating processing unit 152 is configured to perform a PHT process in which reaction products generated in the COR process are sublimated and removed by heating the wafer 10, thereby removing the native oxide film. The Ti film forming processing unit 153 is configured to introduce a film forming gas for Ti film formation into a processing chamber and form a Ti film by a CVD (Chemical Vapor Deposition) method.

[0016] For example, two sets of Ru film formation units 2 are connected to the remaining two walls of the second substrate transfer chamber 14, respectively. A second transfer mechanism 141 is configured to transfer wafers 10 between these four Ru film formation units 2 and the transfer unit 17. In FIG. 1, symbols GV2 and GV3 each indicate a gate valve. In this example, the second substrate transfer chamber 14 corresponds to the substrate transfer chamber of the present disclosure, and the second transfer mechanism 141 corresponds to the transfer mechanism of the present disclosure.

[0017] Each Ru film forming unit 2 includes, for example, a first film forming unit 2A for forming a first ruthenium film (first Ru film) and a second film forming unit 2B for forming a second ruthenium film (second Ru film). The first Ru film is a ruthenium thin film formed in a region including the bottom of a recess on the wafer surface using a gas containing a ruthenium compound that does not contain oxygen atoms or carbon atoms as a ruthenium source. The second Ru film is formed using Ru(CO) as a ruthenium source. 12 The ruthenium film is embedded in the recess so as to cover the ruthenium layer (first Ru film) using a gas containing the above.

[0018] <First film forming processing section> Next, a configuration example of the first film formation processing unit 2A will be described with reference to Fig. 2. The first film formation processing unit 2A includes a first processing vessel 21, the lower part of which is configured as an exhaust chamber 211. A transfer port 20 is formed in the sidewall of the first processing vessel 21, which is connected to the second substrate transfer chamber 14 and through which the wafer 10 is transferred between the first processing vessel 21 and the second substrate transfer chamber 14. The transfer port 20 is configured to be freely opened and closed by a gate valve GV2. The exhaust chamber 211 is connected to a vacuum exhaust mechanism 25 by an exhaust pipe 23 provided with a pressure adjustment unit 24.

[0019] A susceptor 3 for horizontally supporting a wafer 10 is provided in the first processing chamber 21, and is supported from below by support columns 32. The susceptor 3 includes a heater 31 and is configured to heat the wafer 10 to a preset temperature. A shower head 4 is disposed on the ceiling of the first processing chamber 21 so as to face the wafer 10 placed on the susceptor 3. The shower head 4 includes a gas diffusion space 41, and gas outlet ports 42 are formed in a dispersed manner on the lower surface thereof.

[0020] The first film formation processing unit 2A includes a gas supply mechanism 5 including a first gas supply unit. The first gas supply unit is configured to supply a gas containing a ruthenium compound containing neither oxygen nor carbon atoms, such as Ru(PF3)4H2, to the first processing chamber 21. The gas supply mechanism 5 in this example includes a source container 51 that contains a film formation source material S1, and is configured to heat the film formation source material S1 in the source container 51 by a heater 52. The source container 51 contains solid Ru(PF3)4H2 as the film formation source material S1 for the first Ru film.

[0021] The source material container 51 is provided with a carrier gas supply pipe 53, one end of which is inserted into the film-forming source S1. The other end of the supply pipe 53 is connected to a carrier gas supply source 531 via a valve V11, a mass flow controller M1, and a valve V12, in that order from downstream. An inert gas such as argon (Ar) gas or nitrogen (N2) gas can be used as the carrier gas. The upper end surface of the source material container 51 is connected to the gas inlet 43 of the showerhead 4 via a gas supply pipe 54, which is equipped with a valve V21, a flow meter 541, and a valve V22, in that order from the source material container 51 side. The source material container 51, the carrier gas supply source 531, the carrier gas supply pipe 53, the gas supply pipe 54, etc., constitute a first gas supply unit in this example.

[0022] Furthermore, the gas inlet 43 of the showerhead 4 is connected to a reactive gas supply source 551 via a gas supply pipe 55 equipped with a valve V31, a mass flow controller M2, and a valve V32, in that order from the downstream side. In this example, hydrogen (H2) gas, which is a reducing gas, is used as the reactive gas. In addition to H2 gas, NH3 gas, H2 plasma, NH3 plasma, monomethylhydrazine (MMH), hydrazine (N2H4), etc. can also be used as the reactive gas.

[0023] <Second film forming processing section> Next, a configuration example of the second film formation processing unit 2B will be described with reference to FIG. 3. The second film formation processing unit 2B includes a second processing vessel 22. A transfer port (not shown) is formed in the sidewall of the second processing vessel 22. The transfer port is connected to the second substrate transfer chamber 14 and allows the wafer 10 to be transferred between the second processing vessel 22 and the second substrate transfer chamber 14. The transfer port is configured to be freely opened and closed by a gate valve GV3. In this example, the other components in the second processing vessel 22 are similar to those in the first processing vessel 21 described above, and therefore will not be described or illustrated. In the following description, when referring to equipment provided in the second processing vessel 22, the reference numerals assigned to the equipment in the first processing vessel 21 shown in FIG. 2 may be used.

[0024] The second film forming unit 2B includes a gas supply mechanism 6 including a second gas supply unit. The second gas supply unit supplies, for example, Ru3(CO) 12 and CO gas. The gas supply mechanism 6 in this example includes a source container 61 that contains a film-forming source S2 and is configured to be heated by a heater 62. The source container 61 contains solid Ru3(CO) 12 is housed there.

[0025] The source material container 61 is provided with a carrier gas supply pipe 63, one end of which is inserted into the film forming source material S2. The other end of the supply pipe 63 is connected to a carrier gas supply source 631, for example, CO gas, via a valve V41, a mass flow controller M3, and a valve V42, in that order from the downstream side. However, instead of CO gas, an inert gas such as Ar gas or N2 gas can also be used as the carrier gas.

[0026] The upper end surface of the source material container 61 and the gas inlet 43 of the showerhead 4 are connected via a gas supply pipe 64 equipped with a valve V51, a flow meter 641, and a valve V52, in that order from the source material container 61 side. Furthermore, the gas supply pipe 64 is connected to a reaction control gas supply source 651, such as CO gas, between the valve V52 and the gas inlet 43 via a gas supply pipe 65 equipped with a valve V61, a mass flow controller M4, and a valve V62, in that order from the downstream side. As the reaction control gas, N2 gas, H2 gas, Ar gas, etc. can be used in addition to CO gas. In the example shown in Figure 3, Ru3(CO) 12 The raw material container 61, carrier gas supply source 631, carrier gas supply pipe 63, gas supply piping 64, CO gas supply source 651 for reaction control, gas supply pipe 65, etc. constitute a second gas supply unit in this example.

[0027] <Control unit> The film formation apparatus 1 includes a control unit 100 that controls the operation of each unit constituting the film formation apparatus 1, such as various processes in the pretreatment unit 15 and the Ru film formation unit 2, and wafer transport. The control unit 100 is, for example, a computer equipped with a CPU and a storage unit (not shown), and the storage unit stores a program that includes a group of steps (commands) for control required to form a ruthenium layer (first Ru film) and a ruthenium for embedding (second Ru film), which will be described later. The program is stored on a storage medium such as a hard disk, compact disk, magnet optical disk, memory card, or nonvolatile memory, and is installed from there into the computer.

[0028] <Wafer surface structure> An example of the surface structure of a wafer to be subjected to the ruthenium embedding process will now be described with reference to Fig. 4A. An insulating film, such as a silicon oxide film (SiO film) 73, having a recess 72 is formed on the surface of a silicon wafer 71, which is a substrate. A silicon nitride layer (SiN layer) 74 is formed on a sidewall 721 of the recess 72 so as to cover the SiO film 73. Furthermore, the surface of a titanium silicide layer (TiSi layer) 75, which is a metal layer containing, for example, titanium (Ti) and silicon (Si), is exposed on a bottom surface 722 of the recess 72. The TiSi layer 75 functions as a contact layer for establishing electrical conduction with the silicon wafer 71. As an example of the dimensions of the recess 72, the recess 72 is formed to have a width W of 5 to 20 nm and a depth D of 50 to 200 nm, with an aspect ratio (depth D / width W) of 2.5 to 40.

[0029] Such a wafer surface structure is formed, for example, as follows: First, an SiO film 73 is formed on the surface of a silicon wafer 71, and then a recess 72 is formed by etching. Next, a SiN layer 74 is formed so as to cover the inner surface of the recess 72. Next, a bottom surface 722 of the recess 72 is removed by anisotropic etching to form a TiSi layer region. Thereafter, the wafer is transferred to the film forming apparatus 1, where a Ti film is formed, thereby forming a TiSi layer 75.

[0030] First Embodiment Next, a first embodiment of a method for filling recesses 72 formed on a wafer surface with ruthenium will be described together with the operation of the film forming apparatus 1. In the film forming apparatus 1, first, the atmospheric transfer mechanism 111 removes the wafer 10 accommodated in the carrier C and transfers it to the load lock chamber 12, which is under atmospheric pressure, and adjusts the load lock chamber 12 to a vacuum pressure atmosphere. Next, the first transfer mechanism 131 transfers the wafer 10 in the load lock chamber 12 to the etching treatment section 151 and the heating treatment section 152 in that order, where the pre-cleaning process described above is performed to remove the native oxide film formed on the inner surface of the recess 72.

[0031] Next, the wafer 10 is transported by the first transport mechanism 131 to the Ti film deposition processing unit 153, where a Ti film is deposited on the TiSi layer region. When the Ti film is deposited, Si from the silicon wafer 71 diffuses into the Ti film, forming a TiSi layer 75. As a result, the surface of the TiSi layer 75 is exposed at the bottom surface 722 of the recess 72. The wafer 10 that has undergone the COR treatment, PHT treatment, and Ti film deposition processing has the structure shown in FIG. 4A, and this wafer 10 is then filled with ruthenium.

[0032] <Formation of ruthenium layer (first Ru film)> Subsequently, the wafer 10 is transferred to the first film formation processing unit 2A via the first transfer mechanism 131, the delivery unit 17, and the second transfer mechanism 141. In the first film formation processing unit 2A, a step of forming a ruthenium layer in an area including the bottom of the recess 72 is carried out. Specifically, the wafer 10 is loaded into the first processing chamber 21 and placed on the susceptor 3, the wafer 10 is heated, and the inside of the first processing chamber 21 is evacuated to a vacuum. As will be apparent from the evaluation test described later, the deposition rate of the first Ru film at the same deposition temperature varies depending on the type of reducing gas.

[0033] At this time, Ru(PF3)4H2 is heated by heater 52 in source container 51. By supplying a carrier gas to source container 51, Ru(PF3)4H2 vaporized by heating is picked up and supplied to first processing container 21 as a ruthenium source. Furthermore, H gas, which is a reducing gas, is supplied to the first processing chamber 21, and a first Ru film 81, which is a ruthenium layer, is formed in the region including the bottom of the recess 72 by CVD using Ru(PF3)4H2 gas and H2 gas, as shown in Fig. 4B. In this film formation process, Ru(PF3)4H2 adsorbed on the surface of the wafer 10 is reduced by H2 gas, thereby forming a ruthenium film.

[0034] In the first embodiment, the ruthenium film (first Ru film 81) is formed so that the ruthenium film thickness is greater on the bottom surface 722 side of the recess 72 where the TiSi layer 75 is exposed than on the side wall portion 721 side of the recess 72 covered with the SiN layer 74. For this reason, in this example, the first Ru film 81 is formed under conditions such that the film formation rate is higher on the bottom surface 722 side of the recess 72 than on the SiN layer 74 side (side wall portion). This condition can be achieved by adjusting the heating temperature of the wafer 10, the pressure inside the processing chamber 21, the supply ratio of the ruthenium raw material and the reducing gas, and the like, as described above. This condition can be identified by a preliminary experiment or the like. The inventors have reported that the Ru3(CO) 12 It has been confirmed that when a Ru film is formed using the above method, a Ru film having the above-mentioned structure can be obtained.

[0035] In this way, the first Ru film 81 is formed in the recess 72 so that it is thicker on the bottom side than on the sidewall 721 side. In this example, the film thickness of the first Ru film 81 formed on the bottom of the recess 72 is, for example, 2 nm within a range of 1 nm to 5 nm. The bottom of the recess 72 refers to a region including the bottom surface 722, and will be explained in the second embodiment described later. The film thickness of the first Ru film 81 formed on the sidewall 721 is such that the recess 72 is not closed and the subsequent filling of ruthenium (the formation of the second Ru film 82 in the recess 72) can be performed. This film thickness varies depending on the width W and aspect ratio of the recess 72.

[0036] The inventors have found that almost no Ru film is deposited on the exposed surface of the SiO film 73. Therefore, if the SiN layer 74 covering the SiO film 73 is not formed on the sidewall portion 721 of the recess 72, even if the film is formed by the above-described method, almost no first Ru film 81 is formed on the sidewall portion 721. Here, although FIGS. 4B and 4C show an example in which a Ru film is deposited on the upper surface of the SiO film 73, a Ru film may also be deposited on the upper surface of the SiO film 73 in this manner depending on the film formation conditions.

[0037] The first Ru film 81 is formed using a gas containing a ruthenium compound that does not contain oxygen atoms or carbon atoms as the ruthenium source. Therefore, the first Ru film 81 does not contain oxygen atoms, and there is little concern that the metal layer exposed on the bottom surface 722 of the recess 72 will be oxidized. Furthermore, there is little risk of carbon atoms remaining in the first Ru film 81. In contrast, if the ruthenium source is a ruthenium compound that contains oxygen atoms or carbon atoms, there is a high risk that the Ru film formed will contain oxygen atoms and carbon atoms. As a result, the metal layer is oxidized by the oxygen atoms, forming a metal oxide, which leads to an increase in resistivity. Furthermore, if the Ru film contains carbon atoms, this can increase the resistivity and cause film quality degradation.

[0038] In this way, by forming the first Ru film 81 using a ruthenium raw material that does not contain oxygen atoms or carbon atoms, an increase in resistivity at the interface with the TiSi layer (contact layer) 75, which is a metal layer exposed on the bottom surface 722 of the recess 72, is suppressed, and deterioration of the film quality related to the conductivity of the first Ru film 81 is suppressed.

[0039] <Ruthenium filling (forming a second Ru film)> Subsequently, the wafer 10 on which the first Ru film 81 has been formed is transported to the second film formation processing unit 2B by the second transport mechanism 141. In the second film formation processing unit 2B, a step of filling the recesses 72 with ruthenium is performed so as to cover the ruthenium layer (first Ru film 81) formed in the recesses 72.

[0040] Specifically, the wafer 10 is loaded into the second processing chamber 22 and placed on the susceptor 3, and the wafer 10 is heated to a temperature lower than the film formation temperature of the first Ru film 81, for example, 120°C to 300°C. Furthermore, the pressure inside the second processing chamber 22 is adjusted to, for example, 1.3 Pa. At this time, in the source container 61, Ru3(CO) 12 is heated. By supplying CO gas as a carrier gas to the source container 61, Ru3(CO) vaporized by heating is 12is picked up and supplied as a ruthenium source to the second processing vessel 22. Furthermore, CO gas for reaction control is supplied to the second processing vessel 22.

[0041] As a result, vaporized Ru3(CO)12 is supplied to the wafer 10. Then, thermal CVD proceeds, in which Ru3(CO)12 is thermally decomposed on the wafer 10. The second Ru film 82 is formed on the SiO film 73 to a preset thickness. During this film formation, the second Ru film 82 is formed so as to fill the recesses 72 as shown in FIG. 4C. Note that CO gas for reaction adjustment is used during the thermal decomposition process. degree In this way, the second Ru film 82 is formed so as to cover the first Ru film 81 and to fill the recesses 72.

[0042] As described above, the first Ru film 81 is formed not only on the bottom surface 722 but also on the sidewall portion 721 within the recess 72. This first Ru film 81 functions as a liner film that serves as an adhesive layer for the second Ru film 82. Therefore, the second Ru film 82 is deposited in the same manner on the sidewall portion 721 and bottom surface 722 of the recess 72, and ruthenium is quickly embedded in the recess 72.

[0043] Ru3(CO) which is the ruthenium source of the second Ru film 82 12 contains oxygen atoms and carbon atoms, but when it is formed as a bulk film on the first Ru film 81, there is no risk of oxidizing the TiSi layer 75 on the bottom surface 722 of the recess 72. 12 It is understood that the upper limit of the resistivity of a bulk film formed using Ru(PF3)4H2 is about 20 μΩ·cm, and the upper limit of the resistivity of a bulk film formed using Ru(PF3)4H2 is about 100 μΩ·cm. Therefore, in the region where there is no concern about oxidation of the TiSi layer 75, Ru3(CO) 12 When the second Ru film 82 is formed using the above, the resistivity of the entire ruthenium filling the recess 72 can be kept low.

[0044] After the film formation process is completed, the wafer 10 is transferred to the load lock chamber 12 via the second transfer mechanism 141, the delivery unit 17, and the first transfer mechanism 131. Next, the atmosphere in the load lock chamber 12 is switched to an atmospheric pressure atmosphere, and then the processed wafer 10 is returned to the carrier C by the atmospheric transfer mechanism 111. Thereafter, the wafer 10 is transferred to a CMP (Chemical Mechanical Polishing) device provided outside the film forming device 1, where the surface thereof is polished to remove the second Ru film 82 on the upper surface of the recess 72 and the upper portion of the SiO film 73 that constitutes the recess 72. Therefore, the depth and the like of the recess 72 after CMP become smaller than the above-mentioned dimensions.

[0045] According to the above-described embodiment, it is possible to embed ruthenium in the recesses 72 formed on the wafer surface while suppressing an increase in resistance. In order to fill the deep recesses 72 with ruthenium having a large aspect ratio, it is necessary to lower the resistivity of the bulk film that is the filling material and also to lower the resistivity of the interface with the metal layer (TiSi layer 75 in this example) exposed at the bottom surface 722 of the recesses 72. As mentioned above, Ru3(CO) 12 The Ru film formed using Ru3(CO) has low resistivity as a bulk film, but contains oxygen atoms. 12 If the recess 72 is filled using Ru(PF3)4H2, an oxide film is formed at the interface with the metal layer, which may increase the resistivity of the interface. On the other hand, the Ru film formed using Ru(PF3)4H2 does not contain oxygen atoms, so the increase in resistivity at the interface is suppressed. However, the resistivity of the bulk film increases as described above. 12 The film thickness is higher than that of the Ru film formed using the method described above.

[0046] Therefore, two types of ruthenium raw materials are combined, and the raw materials are switched between the first Ru film 81 formed at the interface with the bottom surface 722 of the recess 72 and the second Ru film 82 formed as a bulk film. This reduces the resistivity at the interface of the metal exposed at the bottom surface of the recess 72, and also allows the selection of a material with low resistivity as a bulk film, making it possible to fill the recess with low-resistivity ruthenium. As a result, metal wiring with low resistivity can be realized.

[0047] Furthermore, when the sidewall 721 of the recess 72 is formed of the SiN layer 74, the first Ru film 81 also functions as a liner film, as described above. Therefore, the second Ru film 82 is quickly formed in the recess 72, and the time required to form the second Ru film 82 is reduced compared to when the first Ru film 81 is not formed on the sidewall 721 of the recess 72.

[0048] In this way, when the sidewall 721 of the recess 72 is formed of the SiN layer 74, there is no need to form a separate liner film, and the ruthenium that is filled into the recess 72 only needs to be two layers, the first Ru film 81 and the second Ru film 82. Therefore, since a separate step of forming a liner film is not required, even if these films are formed by switching the ruthenium source gas, there is no concern that the total effort and time required for the process of filling the recess 72 with ruthenium will increase.

[0049] Furthermore, in the above-described film formation apparatus 1, removal of the native oxide film in the recess 72, formation of the TiSi layer, formation of the first Ru film 81, and formation of the second Ru film 82 are all performed within the same film formation apparatus 1. Because the processing sections for these processes are connected to a substrate transfer chamber in a vacuum atmosphere, there is little risk of native oxide film forming in the recess due to contact with the atmosphere during transfer between the processing sections. This allows ruthenium with low resistivity to be quickly formed in the recess 72 from which the native oxide film has been removed.

[0050] <Second embodiment> Next, regarding the second embodiment of the present disclosure, FIG. A to Figure 5CThe second embodiment will be described with reference to the first embodiment. The second embodiment differs from the first embodiment in the film formation conditions for the first Ru film. Therefore, as shown in FIG. 5A, the process up to the step of forming the TiSi layer 75 exposed on the bottom surface of the recess 72 is performed in the same manner as in the first embodiment.

[0051] In this embodiment, the wafer 10 is also transferred to the first processing chamber 21 of the first film formation processing unit 4A, and a gas containing Ru(PF3)4H2 as a ruthenium source and H2 gas as a reducing gas are supplied to form a first Ru film (ruthenium layer) 83 on the wafer by CVD. 。 In the second embodiment, the Ru film (first Ru film 81) is formed so that the thickness of the ruthenium is uniform on the sidewall 721 of the recess 72 covered with the SiN layer 74 and on the bottom surface 722 of the recess 72 where the TiSi layer 75 is exposed.

[0052] 5B, the first Ru film 83 has a substantially uniform thickness, which is formed by the Ru layer 831 on the sidewall portion 721 side and the Ru layer 832 on the bottom side. The thickness of the first Ru film 83 formed in this example is, for example, 1 nm, within a range of 0.5 nm to 5 nm.

[0053] Similar to the film formation method described with reference to FIG. 4B in which the film thickness is made thicker on the bottom side than on the sidewall portion 721, the formation of the first Ru film 83 in this embodiment can also be achieved by adjusting the heating temperature of the wafer 10, the pressure inside the processing vessel 21, the supply ratio of the ruthenium raw material to the reducing gas, etc. In addition, Ru3(CO) 12 In film formation using this as a raw material, lowering the pressure during film formation and decreasing the CO supply ratio makes it possible to form Ru films with different thicknesses, as in the example shown in Figure 4B. On the other hand, increasing the pressure during film formation makes it possible to form Ru films with a uniform thickness, as in the example shown in Figure 5B.

[0054] The bottom of the recess 72 is a region where the first Ru film 83 is formed on the bottom surface 722 of the recess 72. If the thickness of the first Ru film 83 is too small, oxygen atoms contained in the second Ru film 82 formed on the first Ru film 83 may diffuse toward the TiSi layer 75, whereas if the thickness of the first Ru film 83 is too large, the region where the second Ru film 82 is formed may become small, raising concerns about an increase in resistivity. Therefore, the thickness of the first Ru film 83 is preferably greater than 1 nm. Moreover, "uniform thickness" means that the ratio of thickness T1 of Ru layer 831 on sidewall 721 of recess 72 to thickness T2 of Ru layer 832 on the bottom side of recess 72 is within a range of 0.8 to 1.2.

[0055] After the first Ru film 83 is formed in this manner, the wafer 10 is transferred to the second film formation processing unit 2B. Then, in the second processing chamber 22, a process is performed in which a second Ru film 82 is embedded in the recess 72 so as to cover the first Ru film 83 by the same method as in the first embodiment. (Figure 5C) In the next step, the wafer 10 having the recesses 72 filled with ruthenium is subjected to CMP in the same manner as in the first embodiment.

[0056] In this embodiment, a first Ru film 83 containing no oxygen atoms or carbon atoms is also formed at the interface between the bottom surface 722 of the recess 72 and the TiSi layer 75. 12 The second Ru film 83 is formed as a bulk film using ruthenium. Therefore, the recesses 72 can be filled with ruthenium while suppressing an increase in resistance. In this embodiment, the first Ru film 83 is formed with a substantially uniform thickness on the sidewall 721 and bottom surface 722 of the recess 72, and serves as a liner film. Therefore, the step of forming a separate liner film between the first Ru film 83 and the second Ru film 82 can be omitted.

[0057] <Evaluation test> Next, the evaluation of the deposition of a ruthenium layer using Ru(PF3)4H2, a ruthenium raw material, will be described with reference to Figure 6. The ruthenium layer was deposited by varying the deposition temperature and the type of reactive gas (H2 gas and NH3 gas) within the range of deposition conditions described in the first embodiment, and the deposition rate was measured. The pressure inside the processing chamber during the deposition process was set to 933 Pa. The results are shown in Figure 6.

[0058] In Figure 6, the horizontal axis represents the reciprocal of the absolute temperature T multiplied by 1000, and the smaller the value, the higher the film formation temperature. The value "1.6" on the horizontal axis is 352°C, and "1.7" is 352°C. teeth 315℃, "1.8" teeth "283°C" and "1.9" correspond to 253°C, respectively. The vertical axis represents the natural logarithm of the deposition rate DR (nm / mm). Data when H2 gas was used as the reactive gas is plotted with black circles (●), and data when NH3 gas was used is plotted with black squares (■).

[0059] The results of the film formation experiment confirmed that a ruthenium layer can be formed by CVD using a gas containing Ru(PF3)4H2, regardless of whether H2 gas or NH3 gas is used as the reactive gas. It was also confirmed that the film formation rate changes by changing the temperature during the film formation process, and that the higher the film formation temperature, the higher the film formation rate is, regardless of the reactive gas used. Furthermore, even at the same film formation temperature, the film formation rate varies depending on the type of reactive gas, and the rate of change in film formation rate with changes in film formation temperature also differs. This indicates that the optimal film formation temperature range varies depending on the type of reactive gas, even when the same ruthenium source is used.

[0060] In each of the above-described embodiments, the second gas supply unit supplies Ru3(CO) 12 It is only necessary to supply a gas containing CO, and it is not essential to supply CO gas for reaction control. The ruthenium source for forming the ruthenium layer is not limited to Ru(PF3)4H2, and may be any ruthenium compound containing no oxygen or carbon atoms. Furthermore, the ruthenium layer may be formed by atomic layer deposition (ALD), which alternately supplies a source gas and a reactive gas, in addition to CVD. Plasma may be used to activate the source gas and reactive gas during CVD or ALD.

[0061] 1, it is not essential that the first and second Ru films 81, 83, 82 are formed in different processing chambers 21, 22 in the first and second film formation processing units 2A, 2B. For example, the film formation apparatus may be configured to form the ruthenium layers (first Ru films 81, 83) and the ruthenium for embedding (second Ru film 82) in a common processing chamber. In this case, the processing chamber may include a first gas supply unit that supplies a gas containing a ruthenium compound that does not contain oxygen atoms and carbon atoms, and a second gas supply unit that supplies a gas containing Ru(CO) 12 and a second gas supply unit that supplies a gas containing the ruthenium compound. A gas containing the ruthenium compound is supplied from the first gas supply unit to form a ruthenium layer in a region including the bottom of the recess 72 of the wafer 10. Next, the gas supply is switched from the first gas supply unit to the second gas supply unit to form Ru(CO). 12 A gas containing the above is supplied to the wafer 10 to embed ruthenium in the recesses 72 so as to cover the ruthenium layer.

[0062] 1, two substrate transfer chambers 131, 141 are connected via a transfer unit 17 to prevent the substrate transfer chamber from becoming larger as the number of modules connected to one substrate transfer chamber increases. Therefore, if the increase in size of the substrate transfer chamber can be prevented, the pre-treatment unit 15 and the Ru film formation unit 2 may be connected to a common substrate transfer chamber. Conversely, the film formation apparatus 1 may be configured to include three or more substrate transfer chambers.

[0063] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive, and the above-described embodiments may be omitted, substituted, or modified in various ways without departing from the scope and spirit of the appended claims. [Explanation of symbols]

[0064] 10 Semiconductor wafers 72 recess 81, 83 First ruthenium film (ruthenium layer) 82 Second ruthenium film (buried ruthenium film)

Claims

1. A method for embedding ruthenium into recesses formed on a substrate surface, comprising the steps of: supplying a gas containing a ruthenium compound containing no oxygen atoms or carbon atoms as a ruthenium source to the substrate having metal exposed on the bottom surface of the recess, thereby forming a ruthenium layer in a region including the bottom of the recess; Next, Ru as a ruthenium source was added to the substrate. ３ (CO) １２ and filling the recess with ruthenium to cover the ruthenium layer.

2. The ruthenium compound is Ru(PF ３ ) ４ H ２ The method of claim 1, wherein

3. The Ru ３ (CO) １２ The method according to claim 1 or 2, wherein the gas containing the component (B) includes CO gas.

4. 4. The method according to claim 1, wherein in the step of forming the ruthenium layer, the ruthenium layer is formed so that the ruthenium layer formed on the bottom of the recess is thicker than the ruthenium layer formed along the sidewall of the recess.

5. 4. The method according to claim 1, wherein in the step of forming the ruthenium layer, the ruthenium layer is formed so that the thickness of the ruthenium layer formed along the sidewall of the recess and the thickness of the ruthenium layer formed on the bottom of the recess are the same.

6. 6. The method according to claim 1, wherein the recess is formed in a silicon oxide film on the surface of the substrate, and the metal exposed at the bottom of the recess contains titanium and silicon.

7. The method according to claim 6 , wherein a silicon nitride layer covering the silicon oxide is formed on the sidewall of the recess.

8. An apparatus for filling a recess formed on a substrate surface with ruthenium, a processing vessel that accommodates the substrate having a metal exposed on the bottom surface of the recess; a first gas supply unit that supplies a gas containing a ruthenium compound that does not contain oxygen atoms or carbon atoms as a ruthenium source to the processing vessel; The processing vessel was charged with Ru as a ruthenium source. ３ (CO) １２ a second gas supply unit that supplies a gas containing a control unit, The control unit controls a step of supplying a gas containing the ruthenium compound from the first gas supply unit to the substrate in the processing chamber to form a ruthenium layer in a region including a bottom of the recess, and then controlling a step of supplying the gas containing the ruthenium compound from the second gas supply unit to the substrate. ３ (CO) １２ and outputting a control signal to perform the steps of: supplying a gas containing:

9. a first processing vessel provided with the first gas supply unit and a second processing vessel provided with the second gas supply unit are configured as separate bodies, and the first and second processing vessels are connected to a common substrate transfer chamber provided with a transfer mechanism for the substrate; 9. The apparatus according to claim 8, wherein the control unit is configured to output a control signal for, after performing the step of forming the ruthenium layer in the first processing vessel, transferring the substrate on which the ruthenium layer has been formed to the second processing vessel and performing the step of embedding the ruthenium in the second processing vessel.

10. The first gas supply unit contains Ru(PF) as the ruthenium compound. ３ ) ４ H ２ 10. The apparatus of claim 8 or 9, configured to supply

11. The second gas supply unit supplies the Ru ３ (CO) １２ 11. The apparatus of claim 8, configured to supply a gas comprising:

12. 12. The apparatus according to claim 8, wherein in the step of forming the ruthenium layer, the ruthenium layer is formed so that the ruthenium layer formed on the bottom of the recess is thicker than the ruthenium layer formed along the sidewall of the recess.

13. 12. The apparatus according to claim 8, wherein in the step of forming the ruthenium layer, the ruthenium layer is formed so that the thickness of the ruthenium layer formed along the sidewall of the recess and the thickness of the ruthenium layer formed on the bottom of the recess are the same.

14. 14. The device according to claim 8, wherein the recess is formed in a silicon oxide film on the surface of the substrate, and the metal exposed at the bottom of the recess contains titanium and silicon.

15. 15. The device of claim 14, wherein a silicon nitride layer covering the silicon oxide is formed on the sidewalls of the recess.

Images