Method and apparatus for forming a ruthenium silicide film on a substrate surface

Abstract

To form a ruthenium silicide film containing Ru2Si3 on a surface of a substrate at a temperature of less than 500°C.SOLUTION: A gas containing a ruthenium compound is supplied to a surface of a substrate where a diffusion layer is exposed to form a ruthenium film so as to cover the diffusion layer. Next, by supplying gas containing a silicon compound to the substrate, the ruthenium film is made into silicide to form a ruthenium silicide film containing Ru2Si3.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a method and apparatus for forming a ruthenium silicide film on a surface of a substrate. [Background technology]

[0002] In the manufacturing process of semiconductor devices, a process for forming a metal film on a substrate for manufacturing a semiconductor device is performed, and a ruthenium film (Ru film) may be formed as the metal film. Patent Document 1 discloses a process for forming a RuSi film by supplying a silicon-containing gas into a recessed portion on which a Ru film has been formed. This RuSi film is a wiring material, and a process with good step coverage is disclosed so that the entire surface of the recessed portion can be covered. Patent Document 2 discloses a process for forming a diffusion barrier layer made of RuSix (x is approximately 0.01 to 10). The diffusion barrier layer is described as being formed by forming RuSix by chemical vapor deposition, or by forming a Ru layer on a silicon region and then performing an annealing process. However, Patent Documents 1 and 2 do not disclose that the RuSi film or RuSix is ​​Ru2Si3. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-15947 [Patent Document 2] Special Publication No. 2002-524847 Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides techniques for forming a ruthenium silicide film, including Ru2Si3, on a surface of a substrate at a temperature below 500°C. [Means for solving the problem]

[0005] The present disclosure provides: 1. A method for forming a ruthenium silicide film on a surface of a substrate, comprising: supplying a gas containing a ruthenium compound to the surface of the substrate where the diffusion layer is exposed, to form a ruthenium film so as to cover the diffusion layer; Next, the substrate is heated to a temperature in the range of 420°C or higher and lower than 500°C, and a gas containing a silicon compound is supplied to the substrate to silicide the ruthenium film, thereby forming a ruthenium silicide film containing Ru2Si3. [Effects of the Invention]

[0006] According to the present disclosure, a ruthenium silicide film containing Ru2Si3 can be formed on the surface of a substrate at a temperature of less than 500°C. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 2 is a vertical cross-sectional side view showing an example of the configuration of the surface of a silicon substrate. [Figure 2A] This is an example of a band structure diagram of a junction between a p-type semiconductor and a metal. [Figure 2B] 1 is an example of a band structure diagram of a junction between a p-type semiconductor and a semiconductor. [Figure 3] 1 is a schematic plan view illustrating one embodiment of an apparatus for forming a ruthenium silicide film according to the present disclosure. [Figure 4] FIG. 3 is a vertical cross-sectional side view showing an example of a first processing module provided in the apparatus. [Figure 5] FIG. 3 is a vertical cross-sectional side view showing an example of a second processing module provided in the apparatus. [Figure 6] FIG. 1 is a first explanatory view showing the content of wafer processing according to the first embodiment. [Figure 7] FIG. 2 is a second explanatory diagram showing the details of the wafer processing. [Figure 8] FIG. 10 is a characteristic diagram showing the results of a preliminary test. [Figure 9] FIG. 10 is a characteristic diagram showing the results of evaluation test 1. [Figure 10] FIG. 10 is a characteristic diagram showing the results of evaluation test 2. [Figure 11] 1 is an SEM image showing the surface state of a ruthenium film treated in Evaluation Test 2. DETAILED DESCRIPTION OF THE INVENTION

[0008] <Wafer surface structure> In MOS-FETs (field-effect transistors) for logic elements, metal wiring is embedded in recesses formed in interlayer insulating films to connect to diffusion layers. As semiconductor devices become increasingly miniaturized, lower resistance metal wiring is required, and ruthenium (Ru), a low-resistance material, has attracted attention. An example of the surface structure of a substrate embedded with ruthenium as a metal wiring is described with reference to FIG. 1 , using a silicon substrate including a p-type diffusion layer as an example. An insulating film 13 with a recess 12 formed therein is stacked on the silicon substrate 11, which has an exposed p-type diffusion layer, to cover the upper surface. Examples of insulating film 13 include a silicon nitride film (SiN film) and a silicon oxide film (SiO film). Here, we will describe the case where a SiN film is used. The p-type diffusion layer of silicon substrate 11 is exposed at the bottom of recess 12. A contact layer 14 is formed on the bottom of recess 12, and a ruthenium film (Ru film) is embedded thereon as wiring layer 15.

[0009] The contact layer 14 has the function of providing electrical continuity between the substrate 11 and the wiring layer 15, and has conventionally been formed of titanium silicide (TiSi), nickel silicide (NiSi), or the like. However, as the resistance of the wiring metal decreases, it is preferable to use a material with even lower contact resistance for the contact layer. Therefore, the inventors are searching for a constituent material for the contact layer 14 that can replace TiSi or NiSi.

[0010] In searching for such a low-resistance material, the inventors focused on the band structure at the junction between the contact layer 14 and the p-type silicon substrate 11. Figure 2A shows the band structure at the junction between the metal contact metal and the semiconductor p-type silicon substrate (p-type silicon) when the contact layer 14 is made of metal.

[0011] In the structure shown in FIG. 1, in the case of p-type silicon in which the carriers are holes, there is a gap of size φ B This is a Schottky junction in which a barrier (Schottky barrier) is formed. Therefore, in order to pass current from the p-type silicon side to the contact metal side, the Schottky barrier φ B Therefore, the contact metal must be thick enough to provide a Schottky barrier φ between the p-type silicon and the metal. B It is preferable to select a material with as small a height as possible. Here, the work function φ of the metal constituting the contact metal is M The higher the Schottky barrier φ B can be reduced.

[0012] As a result of literature research, etc., it is found that the work function φ M The Schottky barrier φ B We focused on the semiconductor Ru2Si3 as a material that is likely to minimize the height of the lattice (Figure 2B). Ru2Si3 is known to have several types of crystal structures, but the orthorhombic or tetragonal crystal structure has a work function φ M is high. However, because Ru2Si3 is a semiconductor, energy must be applied to allow electrons to be transferred across the band gap. B The sum of the height of the Schottky barrier φ between TiSi and p-type silicon and the band gap is B When the height is smaller than this, the effect of reducing the contact resistance compared to conventional methods can be obtained, and Ru2Si3 satisfies this requirement.

[0013] On the other hand, there are thermal constraints in the manufacture of logic elements, and when a process involving heating of the silicon substrate on which the logic elements are formed is performed, it is sometimes required to keep the heating temperature below 500° C. For example, the aforementioned TiSi is formed by forming a titanium film on a silicon substrate, and then heat-treating the silicon substrate to thermally diffuse the silicon into the titanium.

[0014] Therefore, when forming Ru2Si3, it is possible to consider forming a Ru film on a silicon substrate and then thermally diffusing the silicon through a heat treatment. However, as will be shown in the results of the evaluation test described later, it was found that forming Ru2Si3 using this method requires heat treatment at a temperature of 550°C or higher. Based on such preliminary considerations, the present disclosure has discovered a method for forming a ruthenium silicide film containing Ru2Si3 at a temperature of less than 500°C.

[0015] <Film forming equipment> Hereinafter, one embodiment of a film forming apparatus for forming a ruthenium silicide film on the surface of a substrate will be described with reference to the drawings. The substrate is a semiconductor wafer (hereinafter referred to as "wafer") W on which a field effect transistor for a logic element including a p-type diffusion layer is formed. Here, the case of forming a wafer W having the surface structure shown in FIG. 1 will be described as an example.

[0016] 3 is a schematic plan view showing an example of the configuration of a film formation apparatus 1. The film formation apparatus 1 includes an atmospheric transfer module 2 for loading and unloading wafers W, load lock modules 31 and 32, a vacuum transfer module 4, and multiple, for example, four, processing modules 5, 6, 7, and 8. The atmospheric transfer module 2 includes an atmospheric transfer mechanism 22 in an atmospheric transfer chamber 21. The atmospheric transfer chamber 21 is connected to, for example, three carriers 20, each of which accommodates multiple wafers W, and the load lock modules 31 and 32, respectively, and the wafers W are transferred between these modules by the atmospheric transfer mechanism 22. In FIG. 1, reference numeral 23 denotes a carrier placement unit on which the carriers 20 are placed, and reference numeral 24 denotes an orienter for aligning the wafers W.

[0017] The vacuum transfer module 4 is configured by providing a substrate transfer mechanism 42 inside a vacuum transfer chamber 41. The vacuum transfer chamber 41 is connected to processing modules 5, 6, 7, and 8 and load lock modules 31 and 32, respectively, and is configured so that the substrate transfer mechanism 42 transfers wafers W between these modules. As described above, the two load lock modules 31 and 32 are connected to the atmospheric transfer chamber 31 and the vacuum transfer chamber 41, respectively, and are configured so that the interior thereof can be switched between atmospheric pressure and vacuum pressure.

[0018] Each of the processing modules 5, 6, 7, and 8 includes a processing chamber connected to the vacuum transfer chamber 41, and is configured to perform vacuum processing in each processing chamber. For example, the processing modules are configured as a pre-processing module 5, a first processing module 6, a second processing module 7, and a third module 8. Furthermore, in each of the modules 2 to 8 of the film forming apparatus 1, a gate valve GV is provided between each of the modules that are connected to each other.

[0019] Next, each of the processing modules 5, 6, 7, and 8 will be described. The pre-treatment module 5 is a module that performs pre-treatment before forming a Ru film. The pre-treatment is a pre-cleaning process that removes a native oxide film (SiOx) formed on the wafer surface, and is configured to perform, for example, a COR (Chemical Oxide Removal) process and a PHT (Post Heat Treatment) process. The COR process is a process that alters the native oxide film using, for example, hydrogen fluoride (HF) gas and ammonia (NH3) gas, and the PHT process is a process that heats the wafer to sublimate and remove reaction products generated in the COR process.

[0020] <First processing module> The first processing module 6 is configured as a module for depositing a Ru film for a contact layer by, for example, a CVD (Chemical Vapor Deposition) method. The Ru film for the contact layer is a Ru film formed on the bottom side of the recess 12 so as to cover the p-type diffusion layer exposed at the bottom of the recess 12, and will be described here as a first Ru film.

[0021] 4 is a vertical cross-sectional side view showing an example of the configuration of the first processing module 6. This processing module 6 includes a processing vessel (first processing vessel) 61, the lower part of which is configured as an exhaust chamber 62. The processing vessel 61 is connected to the vacuum transfer chamber 41 via a transfer port 60 for the wafer W formed so as to be freely opened and closed by a gate valve GV, and the wafer W is transferred in and out by a substrate transfer mechanism 42. The exhaust chamber 62 is connected to a vacuum exhaust mechanism 623 by an exhaust pipe 621 provided with a pressure adjustment unit 622.

[0022] A susceptor 63 for horizontally supporting a wafer W is provided in the processing chamber 61, with the susceptor 63 being supported from below by support columns 631. The susceptor 63 includes a heater 632 and is configured to heat the wafer W to a preset temperature, for example, a temperature within a range of 150°C to 200°C. A shower head 64 is disposed on the ceiling of the processing vessel 61 so as to face the wafer W placed on the susceptor 63. The shower head 64 includes a gas diffusion space 641, and a plurality of gas discharge ports 642 are formed in a dispersed manner on the lower surface thereof.

[0023] The first processing module 6 includes a gas supply mechanism 65, and is configured to supply a gas containing a ruthenium compound to the processing chamber 61. The ruthenium compound is, for example, Ru(CO). 12 Alternatively, dicarbonyl-bis(5-methyl-2,4-hexanedionato)ruthenium can be used. In this example, the ruthenium compound is Ru(CO). 12 The case where the gas containing the ruthenium compound contains CO gas will be described. The gas supply mechanism 65 includes a source container 651 that contains a film-forming source S, and is configured so that the film-forming source S in the source container 651 is heated by a heater 652. The source container 651 contains solid Ru3(CO) 12 is housed there.

[0024] The source material container 651 is provided with a carrier gas supply pipe 66, one end of which is inserted into the film-forming source material S. The other end of the supply pipe 66 is connected to a carrier gas supply source 661, e.g., CO gas, via a valve V11, a mass flow controller M1, and a valve V12, in that order from downstream. However, an inert gas such as Ar gas or N2 gas can be used as the carrier gas instead of CO gas. The upper end surface of the source material container 651 is connected to a gas inlet 643 of the shower head 64 via a gas supply pipe 67, which includes a valve V21, a flow meter 671, and a valve V22, in that order from the source material container 651 side. The source material container 651, the carrier gas supply source 661, the carrier gas supply pipe 66, and the gas supply pipe 67 constitute a first gas supply unit.

[0025] Furthermore, the gas inlet 643 of the showerhead 64 is connected to a supply source 681 of a reaction control gas, such as CO gas, via a gas supply pipe 68 equipped with a valve V31, a mass flow controller M2, and a valve V32 in this 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.

[0026] <Second processing module> The second processing module 7 is a module that supplies a gas containing a silicon compound to the wafer W on which the first Ru film has been formed in the first processing module 6 to form a ruthenium silicide film containing Ru2Si3. Here, the processing performed in the second processing module 7 will be described as a silicide treatment process (hereinafter referred to as the treatment process).

[0027] An example of the second processing module 7 will be described with reference to Fig. 5. The processing module 7 includes a processing vessel (second processing vessel) 71, which is connected to a vacuum exhaust mechanism 722 via an exhaust pipe 72 provided with a pressure adjustment unit 721. The processing vessel 71 is also connected to a vacuum transfer chamber 41 via a transfer port 70 for a wafer W formed so as to be freely opened and closed by a gate valve GV, and the wafer W is transferred in and out by a substrate transfer mechanism 42. A mounting table 73 on which a wafer W is placed substantially horizontally is disposed inside the processing vessel 71. The mounting table 73 is configured, for example, to have a substantially circular shape in a plan view, and includes a heating unit 731 formed, for example, by a heater therein, which is configured to heat the wafer W placed on the mounting table 73 to a temperature in the range of 420°C or higher and lower than 500°C.

[0028] A shower head 74 is disposed on the ceiling of the processing vessel 71 so as to face the wafer W placed on the mounting table 73. The shower head 74 includes a gas diffusion space 741, and a plurality of gas discharge ports 742 are formed in a dispersed manner on the lower surface thereof. The second process module 7 includes a gas supply mechanism 75 and is configured to supply a gas containing a silicon compound to the process vessel 71. In this example, the gas containing a silicon compound contains hydrogen gas (H gas) as a reducing agent, and the silicon compound may be, for example, monosilane gas (SiH gas).

[0029] The gas supply mechanism 75 includes a monosilane gas supply unit 76 and a hydrogen gas supply unit 77, and these monosilane gas supply unit 76 and hydrogen gas supply unit 77 form a second gas supply unit. The monosilane gas supply unit 76 includes a SiH4 gas supply source 761 and a supply pipe 762 with a supply control unit 763 installed therein, and is configured to supply SiH4 gas to the processing vessel 71. The hydrogen gas supply unit 77 includes a H2 gas supply source 771 and a supply pipe 772 with a supply control unit 773 installed therein, and is configured to supply H2 gas to the processing vessel 71. The supply control units 763 and 773 each include, for example, a mass flow controller, a valve, etc.

[0030] As the silicon compound, in addition to SiH4, one selected from the group of silicon compounds consisting of Si2H6, Si2I6, SiI4, SiHI3, SiH2I2, SiH3I, Si2Cl6, SiCl4, SiHCl3, SiH2Cl2, SiH3Cl, Si2Br6, SiBr4, SiHBr3, SiH2Br2, SiH3Br, Si2F6, SiF4, SiHF3, SiH2F2, and SiH3F can be used. In addition, deuterium (D2) gas may be used as the gas acting as a reducing gas.

[0031] <Third Processing Module> The third processing module 8 is configured as a module for depositing a Ru film for wiring by, for example, a CVD method. The Ru film for wiring is a Ru film that is embedded in the recesses 12 on the upper surface side of the ruthenium silicide film, and will be described here as a second Ru film.

[0032] The third process module 8 is configured similarly to the first process module 6 shown in FIG. 4, except that it is configured to heat the wafer W to a temperature higher than the film formation temperature of the first Ru film and lower than 500°C. Therefore, the third process module 8 includes a third process container 61 connected to the vacuum transfer chamber 41 and a third gas supply unit that supplies a source gas of a metal for wiring, such as ruthenium. The source gas is, for example, Ru3(CO) 12 The third gas supply unit supplies Ru3(CO) in the same manner as the first gas supply unit. 12 The apparatus includes a raw material container 651, a supply source 661 of CO gas which is a carrier gas, a supply pipe 66 for the carrier gas, a gas supply pipe 67, and the like.

[0033] <Control unit> The film formation apparatus 1 includes a control unit 100 that controls the operation of each component of the film formation apparatus 1, such as various processes in the process modules 5, 6, 7, and 8, and wafer transport. The control unit 100 is configured, for example, by a computer including a CPU and a storage unit (not shown). The storage unit stores a program that includes a set of steps (commands) for control required to form a ruthenium silicide film containing Ru2Si3 and a ruthenium filler 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 then installed into the computer from there.

[0034] First Embodiment Next, a first embodiment of a method for forming a ruthenium silicide film on a wafer surface will be described together with the operation of the film forming apparatus 1 with reference to FIGS. First, the wafers are placed in a carrier 20 and transported to the film forming apparatus 1. The carrier 20 contains a plurality of wafers W, each of which has an insulating film 13 made of SiN formed on the surface of a silicon substrate 11 with an exposed p-type diffusion layer, and has recesses 12 formed by etching. As shown in FIG. 6(a), each of the wafers W has a native oxide film 16 formed on the surface of the silicon substrate 11 exposed at the bottom of the recess 12 (the bottom surface of the recess 12).

[0035] In the film forming apparatus 1, the wafer W stored in the carrier 20 is removed by the atmospheric transfer mechanism 22 and aligned in the orienter 24. The wafer W is then loaded into the load lock chamber 31, which is maintained at atmospheric pressure and adjusted to a vacuum pressure. Next, the substrate transfer mechanism 42 transfers the wafer W from the load lock chamber 31 to the pre-processing module 5, where the pre-cleaning process described above is performed to remove the native oxide film 16 formed on the bottom surface of the recess 12, as shown in FIG. 6(b). This exposes a p-type diffusion layer on the bottom surface of the recess 12.

[0036] <Formation of the first Ru film> Subsequently, the wafer W is transferred by the substrate transfer mechanism 42 to the first processing module 6. In the first processing module 6, a step of forming a ruthenium film (first Ru film) on the bottom side of the recess 12 so as to cover the p-type diffusion layer is performed (FIG. 6(c)). Specifically, the wafer W is loaded into the first processing chamber 61 and placed on the susceptor 63. The wafer W is heated to, for example, 130 to 180° C., and the pressure inside the processing chamber 63 is adjusted to, for example, 2.2 Pa. At this time, in the source chamber 651, Ru3(CO) 12 is heated. By supplying CO gas as a carrier gas to the source container 651, Ru3(CO) vaporized by heating is 12 is picked up and supplied as a ruthenium source to the processing vessel 61. Furthermore, CO gas for reaction control is supplied to the processing vessel 61.

[0037] This vaporized Ru3(CO) 12 is supplied to the wafer W, and Ru3(CO) 12 As the thermal CVD proceeds, a first Ru film 17 is formed on the bottom surface of the recess 12. The Ru film 17 is formed to a predetermined thickness, for example, 10 nm or less, preferably 4 nm to 5 nm. Note that CO gas for reaction control is supplied to suppress the transient progress of the thermal decomposition.

[0038] The bottom of the recess 12 is made of silicon substrate 11, and the sidewalls are made of insulating film (SiN film) 13. The first Ru film has a different deposition rate when deposited on the silicon substrate 11 than when deposited on the insulating film 13. Here, the first Ru film 17 is deposited under conditions such that the deposition rate is faster on the bottom side of the recess 12 than on the sidewall side. These conditions can be achieved by adjusting the wafer heating temperature, the pressure inside the processing chamber 61, the supply ratio of the ruthenium raw material and the reaction adjustment gas, etc., as described above, and these conditions can be identified by preliminary experiments, etc.

[0039] By forming the film under these conditions, the thickness of the formed Ru film is small, at 4 nm to 5 nm, so that the Ru film is hardly formed on the surface of the insulating film 13, and as shown in Fig. 6(c), the first Ru film 17 is selectively formed on the bottom surface of the recess 12. The inventors have found that when the film formation temperature is 130 to 180°C, the Ru film is hardly deposited on the surface of the exposed SiN film.

[0040] <Formation of ruthenium silicide film> Next, the wafer W on which the first Ru film 17 has been formed is transferred by the substrate transfer mechanism 42 from the first process module 6 to the second process chamber 71 of the second process module 7. In this second process module 7, a step of forming a ruthenium silicide film containing RuSi on the upper surface of the first Ru film 17 is performed.

[0041] Specifically, a wafer W is loaded into the second processing chamber 71 and placed on a mounting table 73. The wafer W is heated to a temperature in the range of 420°C or higher and lower than 500°C, and the pressure inside the processing chamber 71 is adjusted to, for example, 400 Pa (3 Torr). Then, SiH4 gas and H2 gas are supplied into the processing chamber 71 as gases containing a silicon compound (FIG. 7(a)).

[0042] When the gas is supplied to the first Ru film 17, it is reduced by the SiH4 gas and H2 gas, and silicon (Si) is incorporated into the first Ru film 17. Because the wafer W is heated to a temperature in the range of 420°C or higher and lower than 500°C, new bonds between Si and Ru are formed in the first Ru film 17, and as is clear from the evaluation test described below, Ru2Si3, which is a semiconductor, is formed. The evaluation test confirmed that this Ru2Si3 contains a cubic crystal structure.

[0043] In this way, a ruthenium silicide film containing Ru2Si3 is formed as a contact layer 14 (hereinafter, may be referred to as a ruthenium silicide film 14) so ​​as to cover the p-type diffusion layer exposed at the bottom of the recess 12. Note that the ruthenium silicide film containing Ru2Si3 may contain RuSi having a composition other than Ru2Si3. In this embodiment, since the film thickness of the first Ru film 17 is 10 nm or less, by supplying a gas containing a silicon compound to the first Ru film 17, the entire first Ru film 17 is silicided, and a ruthenium silicide film is formed.

[0044] <Formation of the second Ru film> Next, the wafer W is transferred by the substrate transfer mechanism 42 from the second process module 7 to the third process chamber 61 of the third process module 8. Then, in this process module 8, a step of forming a ruthenium film (metal film) for wiring in the recess 12 on the upper surface side of the ruthenium silicide film 14 is performed (FIG. 7(b)).

[0045] Specifically, the wafer W on which the ruthenium silicide film 14 has been formed is loaded into the third processing chamber 61 and placed on the susceptor 63. Then, the wafer W is heated to a temperature higher than the film formation temperature of the first Ru film 17, for example, 180 to 250°C, and the pressure inside the processing chamber 61 is adjusted to, for example, 2.2 Pa. In this manner, similar to the first Ru film 17, a gas containing a ruthenium compound, for example, Ru3(CO) 12 Gas and CO gas are supplied to form a second Ru film by thermal CVD.

[0046] The recess 12 has a bottom surface made of a ruthenium silicide film 14 and a side wall made of an insulating film 13. In the third processing module 8, the film is formed at a temperature range higher than that of the first Ru film 17. Therefore, Ru3(CO) 12 The deposition speed of Ru from the recess 12 is fast, and the second Ru film is deposited not only on the bottom surface but also on the portion in contact with the sidewall portion within the recess 12. In this way, the formation of the second Ru film progresses quickly so as to fill the recess 12, and the wiring layer 15 is formed.

[0047] In this process, the processing temperature for the film formation process is set to a temperature below 500°C, so that even if the wafer W is to be used to form a field effect transistor for a logic element including a p-type diffusion layer, thermal effects can be suppressed. After the film formation process is completed, the wafer W in the third process module 8 is transferred to the load lock chamber 32 by the substrate transfer mechanism 42. Next, the atmosphere in the load lock chamber 32 is switched to an atmospheric pressure atmosphere, and then the processed wafer W is returned to the carrier 20 by the atmospheric transfer mechanism 22.

[0048] According to the above-described embodiment, a ruthenium silicide film containing Ru2Si3 can be formed at a temperature of less than 500°C. In this example, after forming a ruthenium film (first Ru film), Ru2Si3 is formed by supplying a gas containing a silicon compound to the wafer W while heating the wafer W to a temperature in the range of 420° C. or higher and lower than 500° C. Therefore, as will be apparent from the evaluation test described later, a ruthenium silicide film containing orthorhombic Ru2Si3 can be formed at a lower temperature than in the method of forming Ru2Si3 by thermal diffusion by heating the wafer W on which a Ru film has been formed.

[0049] Ru2Si3 is a low-resistivity material with a low Schottky barrier for p-type silicon substrates. Furthermore, because a ruthenium silicide film containing Ru2Si3 can be formed at temperatures below 500°C, it can be used for silicon substrates on which field-effect transistors for logic elements containing p-type diffusion layers are formed. In particular, using a ruthenium silicide film containing Ru2Si3 as a contact layer formed to cover the p-type diffusion layer can keep the contact resistance low. It should be noted that Patent Documents 1 and 2 do not describe anything that suggests the contents of the present disclosure, such as the results of a search for low-resistance materials for silicon substrates with exposed p-type diffusion layers, or a ruthenium silicide film containing the semiconductor Ru2Si3.

[0050] Furthermore, in the above-described film formation apparatus 1, removal of the native oxide film in the recess 12, formation of the first Ru film 17 for the contact layer, and formation of the ruthenium silicide film 14 are all performed within the same film formation apparatus 1. Between the first and second process modules 6 and 7 where these processes are performed, the wafer W is transferred by the substrate transfer mechanism 42 via a common vacuum transfer chamber 41, so there is almost no risk of oxygen coming into contact with the wafer W during transfer. Therefore, a ruthenium silicide film 14 with a low oxygen impurity content can be formed, resulting in a film with lower resistance.

[0051] Furthermore, the film formation apparatus 1 is provided with a third process module 8 that forms a second Ru film for wiring, in addition to the first and second process modules 6 and 7. This makes it possible to reduce the oxygen impurity content not only of the ruthenium silicide film 14 but also of the wiring layer 15 made of the second Ru film. Furthermore, since the same film formation apparatus 1 can perform a series of processes, including the formation of the first Ru film 17, the formation of the ruthenium silicide film 14, and the formation of the second Ru film, there is no need for labor or time for transportation between the process modules, and the total processing time can be shortened.

[0052] <Second embodiment> Next, a second embodiment of the present disclosure will be described. The second embodiment differs from the first embodiment in the processing conditions in the second processing module 7. Therefore, the steps up to FIG. 6(a) to FIG. 6(c) are performed in the same manner as in the first embodiment. That is, the wafer W from which the native oxide film has been removed in the preprocessing module 5 undergoes formation of a first Ru film 17 in the first processing module 6 so as to cover the p-type diffusion layer, and is then transferred to the second processing module 7.

[0053] In the second processing module 7, a gas containing a silicon compound is used, and a gas containing a manganese compound is used as an additive for adjusting the band gap of Ru2Si3. As the manganese compound, for example, Mn2(CO) 10 It is preferable to supply such an additive at a flow rate of, for example, about 10% of the flow rate of the gas containing the silicon compound. Also, instead of or together with the manganese compound, a titanium compound, an antimony compound, or a platinum compound can be used as an additive.

[0054] After the ruthenium silicide film 14 is thus formed, the wafer W is transferred to the third processing module 8. Then, in the third processing chamber 61, a process of filling the recess 12 with a second Ru film is performed by the same method as in the first embodiment. In this embodiment as well, a ruthenium silicide film can be formed at a temperature of less than 500° C. Furthermore, when a gas containing a manganese compound is supplied as an additive, the semiconductor Ru2Si3 is doped with a metal as an impurity, thereby reducing the band gap and further reducing the resistance of the ruthenium silicide film 14. [Example]

[0055] Next, a preliminary test using a conventional method and an evaluation test using the method of the present disclosure, which were carried out to evaluate the Ru2Si3 formation method, will be described. <Preliminary Exam> A sample with a Ru film formed on the surface of a silicon substrate was subjected to heat treatment at different temperatures, and silicon was thermally diffused into the Ru film to form a ruthenium silicide film.The crystal structure of this ruthenium silicide film was then analyzed using X-ray diffraction (XRD).

[0056] The Ru film was formed in the first processing module 6 using Ru3(CO) 12 The heating process was carried out using CO gas at 130-180°C and 2.2 Pa to form a Ru film on the surface of a flat silicon substrate. The Ru film had a thickness of 20 nm. The heating process was carried out in the second processing module 7 by supplying N gas as an annealing gas without supplying SiH gas or H gas into the processing vessel 71, and heating the silicon substrate with a heater on the mounting table 73. The temperature conditions were 400°C, 500°C, 550°C, 600°C, and 700°C.

[0057] The results of XRD analysis of each heat-treated Ru film are shown in Figure 8. In Figure 8, the horizontal axis represents the diffraction angle, the left vertical axis represents the diffraction intensity, and the right vertical axis represents the temperature conditions. Figure 8 also shows the Miller indices (202), (312), (422), and (512) of the tetragonal system of Ru2Si3, as well as the Miller indices (100) and (101) of the hexagonal system of Ru.

[0058] As a result, it was found that the peak positions of the XRD spectrum differ when the heating temperature conditions are 400°C and 500°C and when they are 550°C, 600°C, and 700°C. Furthermore, from the peak positions and peak intensity ratios, it was found that the Ru film contains tetragonal Ru2Si3 at heating temperatures of 550°C, 600°C, and 700°C. On the other hand, at heating temperatures of 400°C and 500°C, the Ru film only contains hexagonal Ru, and the formation of Ru2Si3 could not be confirmed. Thus, it was confirmed that, according to the conventional silicidation method using thermal diffusion, it is difficult to form Ru2Si3 unless heat treatment is performed at a temperature of 550°C or higher.

[0059] <Evaluation Test 1> Next, an evaluation test of the Ru2Si3 formation method of the present disclosure will be described. In this evaluation test, a sample with a 114 nm thick Ru film formed on the top surface of a SiO2 film was used. SiH4 gas and H2 gas were supplied to the sample to perform a treatment process, and the temperature dependence of the treatment was evaluated. The Ru film was formed on the top surface of the SiO2 film to suppress the diffusion of silicon from the SiO2 film to the Ru film.

[0060] The first Ru film was formed in the first processing module 6A using Ru3(CO) 12 The reaction was carried out using CO gas at 130 to 180°C and 2.2 Pa. The treatment was carried out in the second treatment module 7 under the conditions of SiH4: 500 sccm, H2: 500 sccm, N2: 6000 sccm, pressure: 400 Pa (3 Torr), treatment time: 600 sec. The temperature conditions were 450°C for Example 1 and 500°C for the Reference Example.

[0061] The crystal structure of the treated sample was analyzed by XRD. As comparative examples, a similar analysis was also performed when only H gas was supplied. The comparative examples were performed under the same conditions as in Example 1 except that SiH gas was not supplied, and the temperature conditions were Comparative Example 1: 350°C, and Comparative Example 2: 400°C.

[0062] The results of the XRD analysis are shown in Figure 9. In the figure, the horizontal axis represents the diffraction angle, and the left vertical axis represents the diffraction intensity. The Miller indices for the orthorhombic Ru2Si3 crystal system are shown in the figure: (022), (131), (013), (200), (141), (123), (222), (240), (124), (062), (342), (106), (400), (324), (422), (226), and (440). The Miller indices for the hexagonal Ru crystal system are also shown: (100), (002), (101), (102), (110), and (103).

[0063] As a result, it was found that the Ru film in Comparative Example 1 (350°C) and Comparative Example 2 (400°C) only contained hexagonal Ru. Therefore, even when performing treatment by supplying SiH4 gas, it is presumed that Ru silicidation is unlikely to occur if the heating temperature is 400°C or less. On the other hand, it was found that Example 1 (450°C) exhibited a peak that was not present in Comparative Examples 1 and 2. Furthermore, in the Reference Example (500°C), the peak position differed from those in Comparative Examples 1 and 2, and the intensity of the peak that appeared in Example 1 was found to be greater. Furthermore, although not shown, it was found that the peak intensity was even greater in data for a temperature condition of 550°C.

[0064] The peaks observed in Example 1 indicate the formation of orthorhombic Ru2Si3. This evaluation test confirmed that when the treatment temperature was 450°C or higher, silicidation of Ru progressed, resulting in the formation of Ru2Si3. However, because the thickness of the sample ruthenium film was 114 nm, significantly larger than the first Ru film, which was 10 nm or less, it is inferred that silicidation of the smaller first Ru film progresses at temperatures lower than 450°C. Furthermore, it is believed that Ru2Si3 can be formed at lower temperatures by using a gas containing a silicon compound with a stronger reducing power than SiH4 gas and H2 gas. Based on these findings, it can be said that silicidation of the first Ru film progresses and Ru2Si3 can be formed at temperatures higher than 400°C and lower than 450°C, for example, at temperatures higher than 420°C.

[0065] <Evaluation Test 2> Next, using the same sample as in Evaluation Test 1, treatment was performed using SiH4 gas and H2 gas while changing the temperature condition in the range of 350°C to 550°C, and the temperature dependency of this treatment was evaluated. The conditions other than the temperature in the deposition of the first Ru film and the treatment were the same as in Evaluation Test 1.

[0066] For the samples (Examples) after the treatment, the Si content in the obtained film was measured by energy dispersive X-ray spectroscopy (EDX), and the surface condition of the film was observed by a scanning electron microscope (SEM). In addition, as a reference example, a similar process was performed by supplying only H2 gas without using SiH4 gas, and the process conditions for the reference example were the same as those for the example, except that SiH4 gas was not added.

[0067] The EDX measurement results are shown in Figure 10. The horizontal axis represents the heating temperature of the treatment process, and the vertical axis represents the Si content. In Figure 10, the hatched bars represent the Examples, and the open bars represent the Reference Example. As a result, it was observed that the Si content in the film was almost constant in the Reference Example, regardless of the temperature. Meanwhile, in the Examples, the Si content in the film was higher at 450°C than in the Comparative Example, and at temperatures above 450°C, the Si content also increased with increasing temperature. Thus, it was observed that at temperatures above 450°C, the supply of SiH4 gas increased the Si content in the film, and silicon was incorporated into the film.

[0068] FIG. 11(a) shows an SEM image of the Example in which treatment was performed at 450°C, and FIG. 11(b) shows an SEM image of the Reference Example in which treatment was performed at 450°C. These images confirm that no abnormal growth of Ru2Si3 was observed even when treatment was performed using SiH4 gas. Abnormal growth refers to the occurrence of abnormal silicidation, in which silicidation progresses partially and clumps of Ru2Si3 are formed. Therefore, it is inferred that by performing treatment by supplying SiH4 gas to the Ru film, silicidation progresses uniformly from the surface side to the entire surface of the Ru film.

[0069] As a result of evaluation tests 1 and 2, it was found that at temperatures below 500°C, silicon is incorporated into the Ru film by supplying a gas containing a silicon compound, and Ru2Si3 containing a rectangular crystal structure is formed. Preliminary tests have shown that conventional heat treatment of a Ru film forms Ru2Si3 containing a tetragonal crystal structure at temperatures of 550° C. or higher. This suggests that silicidation by supplying a gas containing a silicon compound according to the present disclosure can also form Ru2Si3 containing a tetragonal crystal structure depending on the processing conditions, such as the type of gas containing the silicon compound and the pressure inside the processing vessel.

[0070] In the above, the apparatus for forming a ruthenium silicide film on the surface of a substrate is not limited to the configuration of the film formation apparatus 1 shown in FIG. 1. For example, in the first processing module, a ruthenium film for a contact layer and a ruthenium film for burying may be formed by changing the film formation temperature. Furthermore, the ruthenium film for a contact layer and the ruthenium film for burying may each be formed using different types of gas containing a ruthenium compound. Furthermore, the metal for wiring is not limited to ruthenium. Furthermore, the ruthenium silicide film may be formed on the surface of the substrate where the diffusion layer is exposed so as to cover the diffusion layer, and is not limited to being formed as a contact layer.

[0071] Furthermore, the present disclosure is not limited to silicon substrates, but can also be applied to silicon germanium substrates (SiGe substrates) or germanium substrates (Ge substrates). Furthermore, in these SiGe and Ge substrates, a ruthenium silicide film containing Ru2Si3 may be formed to cover not only p-type diffusion layers but also n-type diffusion layers. Even in such cases, it is believed that a low-resistance ruthenium silicide film can be formed.

[0072] 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]

[0073] W Semiconductor wafer 11 Silicon substrate 14 Ruthenium silicide film

Claims

1. 1. A method for forming a ruthenium silicide film on a surface of a substrate, comprising: supplying a gas containing a ruthenium compound to the surface of the substrate where the diffusion layer is exposed, to form a ruthenium film so as to cover the diffusion layer; Next, the substrate is heated to a temperature in the range of 420° C. or more and less than 500° C., and a gas containing a silicon compound is supplied to the substrate to silicide the ruthenium film, thereby forming Ru. ２ Si ３ and forming a ruthenium silicide film comprising:

2. The method of claim 1 , wherein the substrate is a silicon substrate including a p-type diffusion layer.

3. 3. The method according to claim 2, wherein the silicon substrate is one on which a field effect transistor for a logic element including the p-type diffusion layer is to be formed.

4. The ruthenium silicide film is a cubic or tetragonal Ru film. ２ Si ３ 4. The method of claim 1, comprising:

5. The silicon compound is SiH ４ , Si ２ H ６ , Si ２ I ６ , SiI ４ , SiHI ３ , SiH ２ I ２ , SiH ３ I, Si ２ Cl ６ , SiCl ４ , SiHCl ３ , SiH ２ Cl ２ , SiH ３ Cl, Si ２ Br ６ , SiBr ４ , SiHBr ３ , SiH ２ Br ２ , SiH ３ Br, Si ２ F ６ , SiF ４ , SiHF ３ , SiH ２ F ２ , SiH ３ 5. The method of claim 1, wherein the silicon compound is selected from the group consisting of F.

6. 6. The method according to claim 1, wherein the gas containing the silicon compound contains a reducing agent such as hydrogen gas or deuterium gas.

7. The silicon compound-containing gas is Ru ２ Si ３ 7. The method according to claim 1, further comprising the step of adding at least one of a manganese compound, a titanium compound, and an antimony compound as an additive for adjusting the band gap of the silicon nitride.

8. The ruthenium compound is Ru ３ (CO) １２ Alternatively, the ruthenium compound may be dicarbonyl-bis(5-methyl-2,4-hexanedionato)ruthenium, and the gas containing the ruthenium compound may contain CO gas.

9. 9. The method according to claim 1, wherein the diffusion layer on the surface of the substrate is exposed at a bottom surface of a recess formed in an insulating film covering an upper surface of the substrate, and the ruthenium film is formed on the bottom side of the recess in the step of forming the ruthenium film.

10. 10. The method according to claim 9, further comprising the step of forming a metal film by supplying a source gas of the metal to the substrate so as to fill the recesses on the upper surface side of the ruthenium silicide film with a metal for wiring after the step of forming the ruthenium silicide film is performed.

11. The method of claim 10 wherein the wiring metal is ruthenium.

12. An apparatus for forming a ruthenium silicide film on a surface of a substrate, comprising: a first processing module including a first processing chamber that accommodates the substrate with the exposed diffusion layer, and a first gas supply unit that supplies a gas containing a ruthenium compound to the first processing chamber; a second processing module including a second processing vessel that accommodates the substrate after being processed in the first processing module, a heating unit that heats the substrate accommodated in the second processing vessel, and a second gas supply unit that supplies a gas containing a silicon compound to the second processing vessel; a vacuum transfer module in which a substrate transfer mechanism for transferring the substrate is provided within a common vacuum transfer chamber to which the first processing vessel and the second processing vessel are connected; a control unit, The control unit includes a step of supplying a gas containing the ruthenium compound from the first gas supply unit to the surface of the substrate in the first processing vessel to form a ruthenium film so as to cover the diffusion layer; a step of transporting the substrate on which the ruthenium film has been formed from the first processing vessel to the second processing vessel by the substrate transport mechanism; and a step of supplying the gas containing the silicon compound from the second gas supply unit to the substrate while heating the substrate to a temperature in the range of 420° C. or higher and lower than 500° C. by the heating unit to silicide the ruthenium film to form Ru. ２ Si ３ and outputting a control signal to perform the steps of forming a ruthenium silicide film, the steps including:

13. The device of claim 12 , wherein the substrate is a silicon substrate including a p-type diffusion layer.

14. 14. The device according to claim 13, wherein the silicon substrate is one on which a field effect transistor for a logic element including the p-type diffusion layer is formed.

15. The ruthenium silicide film is a cubic or tetragonal Ru film. ２ Si ３ 15. The apparatus of any one of claims 12 to 14, comprising:

16. The silicon compound is SiH ４ , Si ２ H ６ , Si ２ I ６ , SiI ４ , SiHI ３ , SiH ２ I ２ , SiH ３ I, Si ２ Cl ６ , SiCl ４ , SiHCl ３ , SiH ２ Cl ２ , SiH ３ Cl, Si ２ Br ６ , SiBr ４ , SiHBr ３ , SiH ２ Br ２ , SiH ３ Br, Si ２ F ６ , SiF ４ , SiHF ３ , SiH ２ F ２ , SiH ３ 16. The device of any one of claims 12 to 15, comprising a silicon compound selected from the group consisting of F.

17. 17. The apparatus according to claim 12, wherein the gas containing the silicon compound contains hydrogen gas or deuterium gas as a reducing agent.

18. The ruthenium compound is Ru ３ (CO) １２ Alternatively, the device according to any one of claims 12 to 17 is dicarbonyl-bis(5-methyl-2,4-hexanedionato)ruthenium, and the gas containing the ruthenium compound contains CO gas.

19. 19. The apparatus according to claim 12, wherein the diffusion layer on the surface of the substrate is exposed at a bottom surface of a recess formed in an insulating film covering an upper surface of the substrate, and the ruthenium film is formed on the bottom side of the recess in the step of forming the ruthenium film.

20. a third processing module including a third processing vessel connected to the vacuum transfer chamber and accommodating the substrate on which the ruthenium silicide film is formed, and a third gas supply unit supplying a source gas of a metal for wiring to the third processing vessel; 20. The apparatus according to claim 19, wherein the control unit is further configured to output a control signal to execute the steps of: transporting the substrate, on which the ruthenium silicide film has been formed, from the second processing vessel to the third processing vessel by the substrate transport mechanism; and then supplying the source gas from the third gas supply unit to the substrate to form a metal film for embedding a metal for wiring in the recessed portion on an upper surface side of the ruthenium silicide film.

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