Method and apparatus for embedding ruthenium in recesses

Abstract

To embed ruthenium in the recess while minimizing the formation of voids.SOLUTION: In embedding ruthenium in a recess formed in an insulating film on a substrate, ruthenium material is supplied to the substrate and after the first ruthenium film is deposited so that the ruthenium is embedded in the recess, the recess stops the deposition of the first ruthenium film. Then, ozone gas is supplied to the substrate to etch the first ruthenium film until the sidewalls of said recess are exposed, leaving the first ruthenium on the bottom side within the recess. Next, ruthenium material is supplied to the substrate and a second ruthenium film is deposited to fill the recess with ruthenium.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] In the manufacturing process of semiconductor devices, a process of forming a ruthenium film is performed to form recesses such as holes and trenches in an insulating film formed on a substrate for manufacturing a semiconductor device, and to fill these recesses with ruthenium (Ru), which is a wiring material.

[0003] Patent Document 1 describes a technique for selectively forming a target film (e.g., a Ru film) on a substrate having a first region where a conductive material (e.g., Ru) is exposed and a second region where an insulating material (e.g., a low-k material) is exposed on the surface of the substrate. Patent Document 1 also describes supplying ozone gas to the substrate before forming the target film, thereby increasing OH groups on the surface of the insulating material, thereby improving the selectivity of forming the target film on the first region. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2020-147829 Summary of the Invention [Problem to be solved by the invention]

[0005] The present disclosure provides a technique for filling recesses with ruthenium while suppressing the formation of voids. [Means for solving the problem]

[0006] The present disclosure provides a method for filling a recess formed in an insulating film on a substrate with ruthenium, the method comprising: supplying a ruthenium source to the substrate and depositing a first ruthenium film so that the ruthenium is embedded in the recess; stopping the step of forming the first ruthenium film, and supplying ozone gas to the substrate to etch the first ruthenium film until the sidewall of the recess is exposed, while leaving the ruthenium embedded in the bottom side of the recess; Then, a ruthenium source is supplied to the substrate, and a second ruthenium film is formed so as to fill the recess with ruthenium. fruit, the deposition rate of ruthenium from the bottom side of the recess is higher than the deposition rate of ruthenium from the sidewall side, and the difference in deposition rate between the sidewall side and the bottom side is larger in the step of depositing the second ruthenium film than in the step of depositing the first ruthenium film; It is a method. [Effects of the Invention]

[0007] According to the present disclosure, ruthenium can be embedded in the recesses while suppressing the formation of voids. [Brief explanation of the drawings]

[0008] [Figure 1A] 1 is a first example of a recess structure in which ruthenium implantation according to the present disclosure is performed. [Figure 1B] 10 is a second example of a structure within a recess in which the ruthenium filling is performed. [Figure 2] 10 is a diagram showing an example of the configuration of a film forming apparatus for carrying out the ruthenium filling. [Figure 3] 3A to 3C are first operational diagrams of the film forming process according to the embodiment; [Figure 4] FIG. 4 is a second operational diagram of the film forming process. [Figure 5] FIG. 10 is a third operational diagram of the film forming process. [Figure 6] FIG. 10 is a fourth operational diagram of the film forming process. [Figure 7] FIG. 5 is a fifth operational diagram of the film forming process. [Figure 8] FIG. 6 is a sixth operational diagram of the film forming process. [Figure 9] 10 is a graph showing the change in ruthenium film thickness with respect to the film formation cycle in a reference example. [Figure 10] 1 is a graph showing the change in ruthenium film thickness with respect to the film formation cycle in an example. DETAILED DESCRIPTION OF THE INVENTION

[0009] <Wafer surface structure> 1A and 1B show examples of the structure of recesses formed in a silicon wafer (hereinafter referred to as "wafer"), which is the substrate into which ruthenium is embedded according to the present disclosure. For example, in MOS-FETs (field-effect transistors) used in logic devices, metal wiring is embedded in recesses formed in the interlayer insulating film to connect to the diffusion layer. As semiconductor devices become more miniaturized, there is a demand for lower resistance metal wiring, and ruthenium, a low-resistance material, has attracted attention.

[0010] 1A and 1B show a structure in which an insulating film 202 is formed on the upper side of a silicon layer 401, which is the main body of a wafer W, and a recess penetrating the insulating film 202 is formed. 1A, an epitaxial layer 402 for making electrical contact with the silicon layer 401, a TiSix layer 403, and contact ruthenium 30a are stacked in this order from the bottom up in the recess formed in the insulating film 202. Furthermore, ruthenium 30b for a plug filling the remaining recess is stacked on the upper side of the ruthenium 30a. In the configuration shown in FIG. 1A, the region where ruthenium 30a is stacked on the TiSix layer 403 and the region where ruthenium 30b is stacked on the ruthenium 30a correspond to ruthenium embedded regions 3A and 3B to which the present disclosure is applied.

[0011] 1B, a metal gate 404 for making electrical contact with the silicon layer 401 and a tungsten layer 405 are stacked in this order from the bottom up. Furthermore, ruthenium 30c is stacked on the top side of the tungsten layer 405. In the configuration shown in FIG. 1B, Tungsten layer 405 The region on which ruthenium 30c is deposited corresponds to the ruthenium buried region 3C to which the present disclosure is applied.

[0012] When ruthenium source gas is supplied to the wafer W to fill the recesses with ruthenium 30a-30c, film formation tends to proceed preferentially near the openings of the recesses rather than inside the recesses (see also the first ruthenium film 31 in FIG. 4, which will be described later). Continuing to form the ruthenium film under these conditions prevents the source gas from entering the recesses, eventually blocking the openings of the recesses. The ruthenium film thus formed is likely to form voids in the ruthenium 30a-30c filling the recesses. The formation of voids increases the resistance of the ruthenium 30a-30c, which is the wiring material.

[0013] Therefore, in the present disclosure, in the process of filling the recesses with ruthenium 30a to 30c, a process of etching part of the ruthenium film with ozone (O3) gas is carried out to suppress the formation of voids in the ruthenium 30a to 30c filled in the recesses. Hereinafter, with reference to FIG. 2, an example of the configuration of a film forming apparatus 1, which is an apparatus for filling recesses with ruthenium, will be described.

[0014] <Film forming equipment> 2 is a vertical cross-sectional side view showing the overall configuration of the film formation apparatus 1. The film formation apparatus 1 of this example is configured as an apparatus that continuously supplies a source gas of ruthenium material to the surface of the wafer W, forms a ruthenium film by thermal CVD, and fills the recesses.

[0015] 2, the processing vessel 110 is a generally cylindrical vessel with an open top. The lid 131 is disposed to airtightly close the opening of the processing vessel 110 and supports the gas shower head 13 (described later) from the top. An exhaust line 112 is connected to the side surface of the lower portion of the processing vessel 110. A vacuum exhaust unit 113 including a pressure adjustment valve such as a butterfly valve is connected to the exhaust line 112, and is configured to reduce the pressure inside the processing vessel 110 to a preset pressure.

[0016] A loading / unloading port 114 is formed on the side of the processing vessel 110 for loading / unloading the wafer W between the processing vessel 110 and a vacuum transfer chamber (not shown). The loading / unloading port 114 is configured to be freely opened and closed by a gate valve 115.

[0017] A mounting table 12 for holding the wafer W substantially horizontally is provided within the processing vessel 110. For example, the mounting table 12 is configured in a disk shape, and a heater 120 serving as a heating unit for heating the wafer W is embedded within the mounting table 12. The heater 120 is configured, for example, by a sheet-like resistance heating element, and generates heat when supplied with power from a power supply unit (not shown), thereby heating the wafer W mounted on the mounting table 12.

[0018] A support part 121 extending downward is connected to the center of the underside of the mounting table 12. The support part 121 penetrates the bottom of the processing vessel 110, and its lower end is connected to a lift plate 124 arranged below the processing vessel 110. The lift plate 124 is supported from below by a lift shaft of a lift mechanism 122. A bellows 123 is provided between the processing vessel 110 and the lift plate 124 so as to surround the periphery of the support part 121, thereby keeping the inside of the processing vessel 110 airtight.

[0019] In the above-described configuration, when the lifting mechanism 122 raises and lowers the lifting plate 124, the mounting table 12 rises and lowers between a processing position and a transfer position set below the processing position for the wafer W. The wafer W is transferred to and from a transfer mechanism (not shown) using transfer pins provided on the mounting table 12, but the illustration of the transfer pins is omitted.

[0020] A gas shower head 13 is provided at a position facing the wafer W placed on the mounting table 12. As described above, the gas shower head 13 in this example is supported by a lid 131 that closes the opening in the top surface of the processing vessel 110. For example, the gas shower head 13 includes a diffusion chamber for diffusing gas and a number of discharge holes for discharging gas toward the wafer W. In FIG. 2, the diffusion chamber and discharge holes are not shown.

[0021] The downstream end of a gas supply line 130 is connected to the gas shower head 13. A source gas supply pipe 141 for supplying a ruthenium source gas joins the upstream side of this gas supply line 130. The source gas supply pipe 141 is provided with a valve V14 and a flow meter 142 in this order from the downstream side, and its upstream end is connected to a source container 143. The source container 143 is configured to be heated by a heater (not shown), and contains solid triruthenium dodecacarbonyl (Ru3(CO)) as a ruthenium source 144 therein. 12 The ruthenium source 144 is Ru3(CO) 12 The examples are not limited to these, and for example, bisethylcyclopentadienyl ruthenium (Ru(EtCp)2) may also be used.

[0022] The source material container 143 is provided with a carrier gas supply pipe 145 such that one end of the carrier gas supply pipe 145 is inserted into the source material container 143. The other end of the carrier gas supply pipe 145 is connected to a gas supply source 140 of CO gas, which is a carrier gas, via a flow rate regulator M14. The source material gas supply pipe 141, the carrier gas supply pipe 145, the source material container 143, the gas supply source 140, etc. constitute a ruthenium source material supply unit in this example.

[0023] In the above-described configuration, by adjusting the heating temperature of the ruthenium source 144 in the source container 143 and the supply flow rate of the CO gas from the gas supply source 140, the carrier gas (CO gas) and Ru(CO) supplied to the processing container 110 via the gas shower head 13 can be 12 The supply flow rate is adjusted.

[0024] 2, a CO gas supply pipe 151 for supplying the CO gas joins the gas supply pipe 130. A CO gas supply source 150 is connected to the upstream end of the CO gas supply pipe 151, and a flow rate regulator M15 and a valve V15 are disposed in this order from the upstream side.

[0025] Furthermore, an ozone gas supply pipe 171 for supplying ozone gas for etching the first ruthenium film 31 merges with the gas supply path 130. An ozone gas supply source 170 is connected to the upstream end of the ozone gas supply pipe 171, and a flow rate regulator M17 and a valve V17 are installed in this order from the upstream side. The ozone gas supply pipe 171, ozone gas supply source 170, etc. constitute the ozone gas supply unit of this example.

[0026] In addition, a hydrogen gas supply pipe 161 joins the gas supply path 130 to supply hydrogen gas used to remove reaction products generated during etching of the first ruthenium film 31. A hydrogen gas supply source 160 is connected to the upstream end of the hydrogen gas supply pipe 161, and a flow rate adjuster M16 and a valve V16 are installed in this order from the upstream side. The hydrogen gas supply pipe 161, the hydrogen gas supply source 160, the flow rate adjuster M16, and the valve V16 configure the hydrogen gas supply unit of this example.

[0027] The film forming apparatus 1 includes a control unit 100 that controls the transfer of wafers W between the vacuum transfer chamber and the film forming apparatus 1, as well as the operation of each component of the film forming apparatus 1. The control unit 100 is, for example, a computer including 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 film. The program is stored on a storage medium such as a hard disk, compact disk, magnetic optical disk, memory card, or nonvolatile memory, and is installed into the computer from there.

[0028] <Film formation process> A process of filling recesses formed in an insulating film 202 on a wafer W with ruthenium using the film forming apparatus 1 having the above-described configuration will be described with reference to Figures 3 to 8. Figures 3 to 8 schematically show the filling regions 3A to 3C illustrated in Figures 1A and 1B, showing a state in which recesses 21 are formed in the insulating film 202 on the underlying film 201.

[0029] The lower layer 201 corresponds to the "metal-containing film" in this example, and may be selected from the group of metal-containing films consisting of titanium silicide (TiSix), ruthenium (Ru), tungsten (W), copper (Cu), titanium (Ti), and ruthenium oxide (RuO2). On the other hand, the insulating film 202 may be a silicon oxide (SiO2) or silicon nitride (SiN) film.

[0030] First, a wafer W to be processed is taken out of a carrier (not shown) containing multiple wafers W and transferred to the film forming apparatus 1 via a vacuum transfer chamber. At this time, a pre-treatment apparatus (not shown) connected to the vacuum transfer chamber may be used to perform a process to remove a metal oxide film (native oxide film) covering the surface of the underlying film 201 (a process to remove the metal oxide film). Examples of the process to remove the metal oxide film include a COR (Chemical Oxide Removal) process that uses hydrogen fluoride (HF) gas and ammonia (NH) gas to remove the metal oxide film, and a PHT (Post Heat Treatment) process that sublimates and removes reaction products generated during the COR process.

[0031] When the wafer W to be processed is transferred, the gate valve 115 of the film forming apparatus 1 is opened, and the wafer W is loaded into the processing chamber 110 using a wafer transfer mechanism (not shown) installed in the vacuum transfer chamber. Inside the processing chamber 110, the mounting table 12 is waiting in a state where it has been lowered to a transfer position, and the wafer W is transferred to the mounting table 12 via transfer pins (not shown). Thereafter, the wafer transfer mechanism is withdrawn, the gate valve 115 is closed, and the pressure inside the processing chamber 110 is adjusted. Furthermore, the mounting table 12 is raised from the transfer position to the processing position, and the wafer W on the mounting table 12 is heated by the heater 120 to 150°C within a range of 130 to 200°C.

[0032] As shown schematically in FIG. 3, a recess 21 is formed in the insulating film 202 on the surface of the wafer W on the mounting table 12, and the upper surface of the underlying film 201, which is a "film containing metal" after the metal oxide film has been removed, is exposed at the bottom of the recess 21.

[0033] Next, a carrier gas is supplied from the gas supply source 140 to the source container 143 heated to a predetermined temperature. By this operation, Ru3(CO) 12 The gas is picked up and supplied together with the carrier gas from the gas shower head 13 to the processing vessel 110. At this time, CO gas, which is a reaction control gas, may be supplied to the gas shower head 13 from a CO gas supply source 150 connected in parallel to the source vessel 143. The CO gas is a Ru3(CO) 12 This has the function of suppressing the decomposition of ruthenium and adjusting the deposition rate of the ruthenium film.

[0034] By the above operation, Ru3(CO) 12 is decomposed, and ruthenium is deposited on the surface of the wafer W. A first ruthenium film 31 is formed by this deposition of ruthenium, and the ruthenium is gradually embedded in the recesses 21 (step of forming a first ruthenium film).

[0035] Here, titanium silicide film, ruthenium film, tungsten film, etc., exemplified as metal films constituting the underlayer film 201, have a higher film formation selectivity for the first ruthenium film 31 than the silicon oxide film or silicon nitride film constituting the insulating film 202. For this reason, there is a tendency for the film formation rate of ruthenium from the bottom side of the recess 21 to be higher than the film formation rate of ruthenium from the sidewall side of the recess 21. In Figure 4, the difference in film formation rate is schematically shown by the different lengths of the dashed arrows. Furthermore, as described above, in the recess 21, film formation tends to proceed preferentially near the opening compared to the inside.

[0036] Due to these film formation characteristics, in the process of forming the first ruthenium film, the formation of the first ruthenium film 31 proceeds while leaving a long, narrow space in the vertical direction, as shown in Fig. 4. Furthermore, near the opening of the recess 21, the opening width narrows while leaving the long, narrow space. If the formation of the first ruthenium film 31 is continued in this state, the opening will be closed and voids will be formed in the ruthenium 30a-30c embedded in the recess 21.

[0037] Therefore, in the film forming apparatus 1 of this example, after the start of the formation of the first ruthenium film 31, Ru3(CO) 12 The supply of the gas and CO gas is stopped to stop the formation of the first ruthenium film 31. Thereafter, for example, while maintaining the heating temperature of the wafer W at 150°C within a range of 130 to 200°C, ozone gas is supplied into the processing vessel 110 to etch a portion of the bottom-side ruthenium 31a (FIG. 5(a), step of etching the first ruthenium film). In the description of FIGS. 5 to 8, the first ruthenium film 31 after the etching is referred to as the bottom-side ruthenium 31a.

[0038] When ozone gas reacts with solid ruthenium within the above-mentioned heating temperature range, gaseous RuO4 and solid RuO2 are generated. The gaseous RuO4 is exhausted to the outside of the processing vessel 110 through the exhaust line 112. Most of the solid RuO2 is exhausted to the outside of the processing vessel 110 in the form of fine particles, carried by the exhaust flow. Meanwhile, some of the solid RuO2 also adheres to the surface of the underlayer film 201 as reaction product 32.

[0039] Therefore, in the film forming apparatus 1 of this example, during the period in which the first ruthenium film 31 is etched, etching of the first ruthenium film 31 by supplying ozone gas and removal of the reaction product 32 by supplying hydrogen gas to the wafer W are alternately and repeatedly carried out. The supply of hydrogen gas reduces RuO4 to return it to the state of ruthenium (Ru), thereby removing the reaction product 32 (FIG. 5(b)), and then the reduced ruthenium is removed from the surface of the lower film 201 by etching while supplying ozone gas.

[0040] 5(a) and 5(b) also show the outline of the longitudinal cross section of the first ruthenium film 31 before etching begins, indicated by a dashed line. In the example shown in the figures, the supply of ozone gas begins before the openings of the recesses 21 are blocked, and etching of the first ruthenium film 31 progresses. However, in the numerous recesses 21 formed on the surface of the wafer W, the progress of etching of the first ruthenium film 31 may differ from one another. Therefore, in some recesses 21, the first ruthenium film 31 is formed quickly, and the openings of the recesses 21 are blocked and voids are formed when the supply of ozone gas begins. Even in this case, after the first ruthenium film 31 forming the blocked portions is etched by ozone gas, the same process as in FIGS. 5(a) and 5(b) proceeds.

[0041] In this way, ruthenium (bottom-side ruthenium 31a) is left on the bottom side of the recess 21 of the underlayer film 201, and the side wall ( insulation membrane 20 2 ) is exposed. Here, the bottom side can be exemplified as the range below half the depth of the recess 21. Furthermore, the range of the first ruthenium film 31 removed by etching can be exemplified as the case where the entire portion constituting the above-mentioned "vertically elongated space" is removed.

[0042] By etching the first ruthenium film 31 with the above-described ozone gas for a preset time, a structure is obtained in which the bottom-side ruthenium 31a remains at the bottom of the recess 21 while the sidewall of the recess 21 is exposed (FIG. 6). Note that the range of first ruthenium film 31 removed by etching may be set slightly higher, leaving a recess corresponding to the lower end of the "vertically elongated space" described above on the upper surface of the bottom-side ruthenium 31a shown in FIG. 6. Even in this case, there is no significant effect on the filling of the second ruthenium film 31b described below.

[0043] Next, the film forming apparatus 1 stops the supply of ozone gas and completes etching of the first ruthenium film 31. Thereafter, for example, while maintaining the heating temperature of the wafer W at 150° C. within a range of 130 to 200° C., Ru3(CO) 12 The supply of the ozone gas and CO gas is then resumed, and deposition of the second ruthenium film 31b is initiated (FIG. 7, step of depositing a second ruthenium film). By performing the deposition of the first ruthenium film 31, etching the first ruthenium film 31 with ozone gas, and deposition of the second ruthenium film 31b at a common heating temperature, these different processes can be performed in the common processing chamber 110 without waiting for temperature adjustment.

[0044] Before forming the second ruthenium film 31b, the first ruthenium film 31 is etched using ozone gas as the etching gas. The use of ozone gas has a modifying effect of increasing the difference in film formation rate between the top surface of the bottom-side ruthenium 31a and the sidewall surface of the recess 21, i.e., the surface of the insulating film 202.

[0045] That is, the surface of the etched bottom-side ruthenium 31a is in a state where the reaction product 32 is removed by the supply of hydrogen gas as described above, and the ruthenium is exposed. Here, it has been found that etching with ozone gas has the effect of increasing the surface roughness of the bottom-side ruthenium 31a compared to the state in which the first ruthenium film 31 is as-deposited. As a result, Ru3(CO) 12 The adsorption area of ​​the activated species generated from the gas becomes larger, and the deposition rate of the second ruthenium film 31b is increased.

[0046] On the other hand, ozone gas reacts with dangling bonds in the silicon oxide film and silicon nitride film that make up the insulating film 202 to form Si-O bonds, thereby reducing the content of dangling bonds. As a result, Ru3(CO) 12 The adsorption of activated species generated from the gas is inhibited, and the deposition rate of the second ruthenium film 31b is significantly reduced.

[0047] 4, between the metal-containing film constituting the underlayer film 201 and the insulating film 202, the rate at which ruthenium is formed from the bottom of the recess 21 tends to be higher than the rate at which ruthenium is formed from the sidewall of the recess 21. Then, as described above, when the second ruthenium film 31b is etched using ozone gas, the sidewall and bottom surfaces of the recess 21 are modified. As a result, the difference in film formation rate between the sidewall and bottom of the recess 21 is greater during the formation of the second ruthenium film 31b than during the formation of the first ruthenium film 31.

[0048] In particular, the formation of the second ruthenium film 31b hardly progresses from the surface of the insulating film 202 modified by ozone gas, and a highly anisotropic film formation process can be performed in which the formation of the second ruthenium film 31b progresses mainly from the upper surface side of the bottom-side ruthenium 31a, as shown in Fig. 7. Then, by this highly anisotropic film formation process, the second ruthenium film 31b is formed upward from the surface of the bottom-side ruthenium 31a so as to fill the recesses 21, and ruthenium can be embedded in the recesses 21 while suppressing the formation of voids (Fig. 8).

[0049] After the second ruthenium film 31b is formed for a predetermined time, Ru3(CO) 12 The supply of gas and CO gas is stopped, and heating of the wafer W is stopped. Next, the mounting table 12 is lowered from the processing position to the transfer position, and the wafer W is unloaded from the processing vessel 110 in the reverse order of the loading operation. The processed wafer W is then transferred via a vacuum transfer chamber (not shown) or the like, and placed back into the original carrier.

[0050] According to the film forming apparatus 1 of this embodiment, the formation of ruthenium (first ruthenium film 31 and second ruthenium film 31b) to be filled in the recesses 21 is divided into two stages. Then, between these film formation stages, a portion of the first ruthenium film 31 is removed by etching using ozone gas. These processes make it possible to fill the recesses 21 with ruthenium while suppressing the formation of voids.

[0051] Here, for example, supplying ozone gas to the recesses 21 and performing a process to modify the surface of the insulating film 202 before depositing the first ruthenium film 31 leads to the formation of an oxide film on the surface of the insulating film 202 exposed at the bottom of the recesses 21. This is undesirable because it increases the contact resistance with the ruthenium to be embedded in the recesses 21. By depositing the first ruthenium film 31 on the insulating film 202 from which the metal oxide film has been removed in advance by COR treatment or PHT treatment, and then modifying the surfaces of the bottom-side ruthenium 31a and the insulating film 202 with ozone gas, it is possible to embed ruthenium while suppressing the formation of voids and suppressing an increase in contact resistance.

[0052] <Variations> Here, it is not essential that the deposition of the first ruthenium film 31, the etching of the first ruthenium film 31 with ozone gas, and the deposition of the second ruthenium film 31b be performed at a common heating temperature, as in the above-described example. For example, if the optimal processing temperatures differ between the deposition of the first ruthenium film 31 and the second ruthenium film 31b and the etching of the first ruthenium film 31 with ozone gas, the heating temperature of the wafer W in these processes may be changed. Furthermore, processing vessels for performing each process may be connected to a common vacuum transfer chamber, and these processes may be performed in different processing vessels. In this case, the entire configuration including the vacuum transfer chamber and the multiple processing vessels constitutes the ruthenium embedding apparatus of the present disclosure.

[0053] 5(a) and 5(b), it is not essential to alternately and repeatedly perform etching of the first ruthenium film 31 with ozone gas and removal of the reaction products 32 with hydrogen gas. For example, if the effect of the reaction products 32 is small, etching of the first ruthenium film 31 with ozone gas for a predetermined time may be performed, and then removal of the reaction products 32 with hydrogen gas may be performed only once, or the supply of hydrogen gas may be omitted so that removal of the reaction products 32 is not performed.

[0054] 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. [Example]

[0055] (Experiment) Ruthenium (Ru) film, silicon oxide (SiO2) film, etc. were formed on the surface of a blanket wafer, and the change in the Ru film formation rate was measured before and after the modification treatment with ozone gas.

[0056] A. Experimental Conditions (Reference example) A blanket wafer with a Ru film, SiO2 film, and tungsten (W) film formed on its surface was prepared, and Ru3(CO) 12 Ruthenium films were formed using the gas Ru3(CO) 12 The film formation cycle in which the gas was supplied for 35 seconds was repeated 2 to 4 times, and the thickness of the Ru film was measured during these cycles to confirm the change in the film formation rate. The heating temperature of the wafer W during the film formation cycle was 150°C. (Example) A blanket wafer having a Ru film and a SiO2 film formed on its surface was treated with ozone gas, and then a Ru film was formed under the same conditions as in the reference example. The heating temperature of the wafer W during the ozone gas treatment was 150°C.

[0057] B. Experimental Results The results of the Reference Example are shown in Figure 2, and the results of the Example are shown in Figure 3. The horizontal axis of each graph represents the number of film formation cycles performed, and the vertical axis represents the thickness of the Ru film formed. In the reference example in which no ozone gas treatment was performed, there was no significant difference in the amount of Ru film (corresponding to the first ruthenium film 31) formed on the Ru film and on the SiO2 film (corresponding to the insulating film 202) for each number of film formation cycles. Furthermore, on the W film (corresponding to the underlayer film 201), the amount of Ru film formed increased significantly for the same number of film formations (four times), demonstrating that the film formation rate can be improved by selecting a film containing a metal that constitutes the underlayer film 201. Therefore, when starting to form the first ruthenium film 31 with the underlayer film 201 exposed, the effect of increasing the rate of ruthenium formation from the bottom side of the recess 21 is exhibited compared to the rate of ruthenium formation from the sidewall side.

[0058] On the other hand, in the examples after the ozone gas treatment, the amount of Ru film formed on the SiO2 film at each number of film formation cycles was reduced compared to the reference example. In contrast, the amount of Ru film formed on the Ru film was significantly increased compared to the reference example. Furthermore, including the origin of zero film thickness, it can be said that by performing the ozone gas treatment, the film formation rate of the Ru film (corresponding to the second ruthenium film 31b) on the Ru film (corresponding to the first ruthenium film 31) is significantly increased compared to the film formation of the Ru film on the SiO2 film (corresponding to the insulating film 202). [Explanation of symbols]

[0059] W wafer 1 Film deposition equipment 110 Processing container 143 Raw material container 144 Ruthenium raw material 160 Ozone gas source

Claims

1. A method for filling a recess formed in an insulating film on a substrate with ruthenium, comprising the steps of: supplying a ruthenium source to the substrate and depositing a first ruthenium film so that the ruthenium is embedded in the recess; stopping the step of forming the first ruthenium film, and supplying ozone gas to the substrate to etch the first ruthenium film until the sidewall of the recess is exposed, while leaving the ruthenium embedded in the bottom side of the recess; and then supplying a ruthenium source to the substrate and depositing a second ruthenium film so as to fill the recess with ruthenium, a deposition rate of ruthenium from the bottom side of the recess is higher than a deposition rate of ruthenium from the sidewall side, and a difference in deposition rate between the sidewall side and the bottom side is larger in the step of depositing the second ruthenium film than in the step of depositing the first ruthenium film.

2. 2. The method according to claim 1, wherein in the step of etching the first ruthenium film, etching of the first ruthenium film by supplying the ozone gas and removing a reaction product of ozone and ruthenium by supplying hydrogen gas to the substrate are alternately and repeatedly performed.

3. 3. The method according to claim 1, wherein the insulating film is formed on a film containing a metal, and the first ruthenium film is formed on the film containing a metal exposed at the bottom of the recess.

4. 4. The method according to claim 3, further comprising the step of removing a metal oxide film covering the metal-containing film exposed at the bottom of the recess before performing the step of forming the first ruthenium film.

5. 4. The method according to claim 3, wherein the metal-containing film has a higher film formation selectivity than the insulating film, and the film formation rate of ruthenium from the bottom side of the recess is higher than the film formation rate of ruthenium from the sidewall side of the recess.

6. 6. The method of claim 5, wherein the metal-containing film is selected from the group consisting of a titanium silicide film, a ruthenium film, a tungsten film, a copper film, a titanium film, and a ruthenium oxide film.

7. 7. The method according to claim 1, wherein the insulating film is a silicon oxide film or a silicon nitride film.

8. 8. The method according to claim 1, wherein the steps of forming the first ruthenium film, etching the first ruthenium film, and forming the second ruthenium film are performed in a state where the substrate is heated to a common temperature within a range of 130 to 200° C.

9. An apparatus for filling a recess formed in an insulating film on a substrate with ruthenium, a processing vessel that accommodates the substrate; a ruthenium source supply unit that supplies a ruthenium source to the processing vessel; an ozone gas supply unit that supplies ozone gas to the processing vessel; a control unit, the control unit is configured to output control signals to execute the following steps: supplying the ruthenium source from the ruthenium source supply unit to the substrate in the processing chamber, and depositing a first ruthenium film so that ruthenium is embedded in the recess; stopping the step of depositing the first ruthenium film, and supplying ozone gas from the ozone gas supply unit to etch the first ruthenium film until a sidewall of the recess is exposed, while leaving ruthenium embedded in a bottom side of the recess; and then supplying the ruthenium source from the ruthenium source supply unit, and depositing a second ruthenium film so that ruthenium is filled in the recess; the deposition rate of ruthenium from the bottom side of the recess is higher than the deposition rate of ruthenium from the sidewall side, and the difference in deposition rate between the sidewall side and the bottom side is larger in the step of depositing the second ruthenium film than in the step of depositing the first ruthenium film.

10. a hydrogen gas supply unit for supplying hydrogen gas to the processing vessel; 10. The apparatus according to claim 9, wherein in the step of etching the first ruthenium film, the control unit outputs a control signal for alternately and repeatedly performing etching of the first ruthenium film by supplying the ozone gas and removing a reaction product of ozone and ruthenium by supplying hydrogen gas to the substrate.

11. 11. The device according to claim 9, wherein the insulating film is formed on a film containing a metal, and the first ruthenium film is formed on the film containing a metal exposed at the bottom of the recess.

12. 12. The apparatus according to claim 11, wherein the film containing the metal has a higher film formation selectivity than the insulating film, and the film formation rate of ruthenium from the bottom side of the recess is higher than the film formation rate of ruthenium from the sidewall side of the recess.

13. 13. The apparatus of claim 12, wherein the metal-containing film is selected from the group of films consisting of titanium silicide film, ruthenium film, tungsten film, copper film, titanium film, and ruthenium oxide film.

14. 14. The device according to claim 9, wherein the insulating film is a silicon oxide film or a silicon nitride film.

15. a heating unit that heats the substrate in the processing chamber; The apparatus according to any one of claims 9 to 14, wherein the control unit outputs a control signal so that the steps of forming the first ruthenium film, etching the first ruthenium film, and forming the second ruthenium film are performed in a state in which the substrate is heated to a common temperature within a range of 130 to 200°C by the heating unit.

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