Substrate processing method and substrate processing device

Abstract

To prevent a failure of film deposition in forming and filling a ruthenium film into a recessed part that is formed in a substrate.SOLUTION: A substrate processing method according to the present disclosure comprises: a step of supplying a film formation gas to a substrate having a recessed part formed therein to form a ruthenium film in the recessed part, and stopping the supply of the film formation gas to the substrate before the filling of the ruthenium film into the recessed part is completed; an etching step of supplying an oxidation gas to the substrate in order to oxidize and remove the ruthenium film formed on the side surface of the recessed part; a reduction step of supplying a first reduction gas, which is a carbon monoxide gas, to the substrate in order to reduce the surface of the ruthenium film remaining on the bottom side of the recessed part oxidized by the oxidation gas; and a step of supplying the film formation gas again to the substrate in order to fill the recessed part with the ruthenium film.SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

[0002] In manufacturing a semiconductor device, a ruthenium film forming wiring may be formed by supplying a film-forming gas to recesses formed on the surface of a semiconductor wafer (hereinafter referred to as the wafer) as a substrate, thereby filling the recesses. According to the film-forming method described in Patent Document 1, the supply of the film-forming gas to the wafer is temporarily stopped during film formation to prevent voids from being formed in the ruthenium film due to blockage of the recesses during film formation. Ozone gas is then supplied to the wafer so that the portions of the ruthenium film formed on the side surfaces of the recesses are etched. Hydrogen gas is then supplied to the wafer to reduce the surface of the ruthenium film remaining in the recesses that has been oxidized by the ozone gas, and the film-forming gas is then supplied to the wafer again. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2023-45017 Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides a technique that can prevent film formation defects when forming a ruthenium film to fill a recess formed in a substrate. [Means for solving the problem]

[0005] The film formation method of the present disclosure includes a step of supplying a film formation gas to a substrate having a recess formed therein to form a ruthenium film in the recess, and stopping the supply of the film formation gas to the substrate before the recess is completely filled with the ruthenium film; an etching step of supplying an oxidation gas to the substrate to oxidize and remove the ruthenium film formed on the side surface of the recess; a reduction step of supplying a first reducing gas, which is carbon monoxide gas, to the substrate in order to reduce the surface of the ruthenium film remaining on the bottom side of the recess, which surface has been oxidized by the oxidizing gas; supplying the film-forming gas to the substrate again to fill the recess with the ruthenium film; Equipped with. [Effects of the Invention]

[0006] The present disclosure can prevent film formation defects when forming and filling a ruthenium film in a recess formed in a substrate. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a vertical cross-sectional side view of a wafer to which a substrate processing method according to an embodiment of the present disclosure is applied; [Figure 2] FIG. 2 is a vertical cross-sectional side view showing an outline of processing performed on the wafer. [Figure 3] 3A and 3B are schematic diagrams showing changes in the ruthenium film formed on the wafer. [Figure 4] FIG. 2 is a longitudinal sectional side view of the wafer. [Figure 5] FIG. 1 is a flow chart showing processing on a wafer. [Figure 6] FIG. 1 is a flow chart showing processing on a wafer. [Figure 7] 1 is a vertical cross-sectional side view showing an example of an apparatus for performing the substrate processing method. [Figure 8] FIG. 2 is a vertical cross-sectional side view of a gas shower head provided in the apparatus. [Figure 9] FIG. 2 is a cross-sectional plan view of the gas shower head. [Figure 10] FIG. 1 is an explanatory diagram showing an image of a ruthenium film obtained in an evaluation test. [Figure 11] FIG. 1 is an explanatory diagram showing an image of a ruthenium film obtained in an evaluation test. [Figure 12] FIG. 10 is a graph showing the concentration of oxygen atoms contained in a ruthenium film obtained in an evaluation test. [Figure 13] FIG. 1 is a graph showing the amount of ruthenium etched obtained in an evaluation test. [Figure 14] FIG. 1 is a graph showing the amount of ruthenium etched obtained in an evaluation test. [Figure 15] FIG. 1 is a graph showing the amount of ruthenium etched obtained in an evaluation test. DETAILED DESCRIPTION OF THE INVENTION

[0008] An embodiment of a substrate processing method according to the present disclosure will be described. Fig. 1 is a longitudinal side view of the surface of a wafer W, which is a circular substrate to which this film formation method is applied. An underlayer film 11 is formed on the wafer W, and this underlayer film 11 is a metal film made of, for example, ruthenium or tungsten. An upper layer film 12 is formed on the underlayer film 11. The upper layer film 12 is composed of, for example, a silicon nitride film and a silicon oxide film, and the silicon oxide film is formed on the silicon nitride film.

[0009] Holes are drilled in the thickness direction in the upper layer film 12, exposing the base film 11. Therefore, a recess 13 is provided on the surface of the wafer W, and the bottom wall of the recess 13 is formed by the base film 11, and the side wall is formed by the upper layer film 12. This recess 13 forms a hole or a trench. In the following description, the side on which the upper layer film 12 is formed may be referred to as the upper side, but processing of the wafer W is not limited to being performed in such a state where the wafer W is positioned so that the upper layer film 12 is on the upper side relative to the base film 11.

[0010] In the process of this embodiment, thermal CVD is performed on the wafer W stored in a processing chamber by supplying a film formation gas containing a compound containing Ru (ruthenium), and a Ru film 14 forming metal wiring is formed so as to fill the recess 13. That is, the Ru film 14 is grown in the recess 13 until the top surface of the Ru film 14 reaches at least the upper edge of the recess 13. In order to fill the recess 13, etching and reduction processes, which will be described later, are also performed in addition to the film formation process of the Ru film 14. These processes are performed on the wafer W stored in a processing chamber that has been evacuated to a vacuum atmosphere of a predetermined pressure, and the wafer W is heated to a predetermined temperature during processing.

[0011] 2 shows an overview of the process in this embodiment. By supplying a film-forming gas containing Ru (indicated by solid arrows in the figure) to the wafer W as described above, Ru deposits on the bottom wall of the recess 13 (i.e., on the base film 11) to form a Ru film 14, and the thickness of the Ru film 14 gradually increases (left side of FIG. 2). Meanwhile, Ru also adheres to the sidewall of the wafer W, forming a Ru film on the sidewall. For convenience, the Ru film formed on the sidewall of the recess 13 is indicated as 15 in the figure to distinguish it from the Ru film 14 formed on the bottom wall.

[0012] If the supply of the deposition gas were to continue, the thickness of the Ru film 15 on the sidewall would increase. In other words, the Ru film 15 would grow laterally. This could result in the opening of the recess 13 being blocked before the Ru film 14 is fully filled, potentially preventing the deposition gas from being supplied to the recess 13. In this case, voids would form in the Ru film 14. To prevent this, the supply of the deposition gas to the wafer W is temporarily stopped before the Ru film 14 is completely filled into the recess 13. O3 (ozone) gas is then supplied to the wafer W as an etching gas (oxidizing gas) to remove the Ru film 15. The supply of O3 gas oxidizes the surface of the Ru film 14, generating RuO2 (ruthenium oxide), and a reducing gas is then supplied to reduce the surface. The right side of Figure 2 shows the state after the etching and reduction have been performed. The dotted arrows in the figure collectively indicate the oxidizing and reducing gases.

[0013] After this reduction, deposition gas is again supplied to the wafer W, and Ru is deposited on the Ru film 14 formed by the previous supply of deposition gas, thereby increasing the thickness of the Ru film 14. If the Ru film 14 is not sufficiently filled into the recess 13 when this second supply of deposition gas is completed, the etching gas and reducing gas, and the deposition gas are sequentially supplied again after this second supply of deposition gas to complete the filling. However, in this embodiment, it is assumed that the Ru film 14 is completely filled into the recess 13 by the second supply of deposition gas, as shown in FIG.

[0014] 3, for convenience of explanation, the portion of the Ru film 14 filled in the recess 13 that is formed by the first supply of the film formation gas may be referred to as Ru film 14A, and the portion that is formed by the second supply of the film formation gas may be referred to as Ru film 14B. Therefore, the Ru film 14B is formed on the Ru film 14A, and the reduction described above is performed as reduction of the surface of the Ru film 14A.

[0015] If the surface of the Ru film 14A is not sufficiently reduced, the resistance of the Ru film 14 after filling the recesses 13 may be high, or the Ru film 14B may not be formed on the surface, making it impossible to fill the recesses 13 with the Ru film 14. Therefore, it is necessary to prevent these defects in the formation of the Ru film 14. As will be explained in the evaluation tests described later, it has been shown that the use of CO (carbon monoxide) gas can more reliably perform this reduction. Therefore, in this embodiment, CO gas is used as the reducing gas.

[0016] A specific example (referred to as a first processing example) of processing the wafer W performed after the formation of the Ru film 14A and before the formation of the Ru film 14B, and reactions that are presumed to occur on the surface of the wafer W, will be described below with reference to the schematic diagram of the wafer W in Fig. 4. In this first processing example, the supply of O3 gas and CO gas into the processing chamber is started at the same time, so that the above-mentioned etching and reduction are performed in parallel.

[0017] The O3 gas supplied to the wafer W oxidizes the surface of the Ru film 14A, partially vaporizing it as RuO4, and etching proceeds. During this process, the Ru film 15 formed on the sidewall of the recess 13 is also etched, along with the surface of the Ru film 14A. This oxidation by the O3 gas converts a portion of the surface of the Ru film 14A into RuO2. Furthermore, some of the vaporized RuO4 decomposes, releasing oxygen, turning it into RuO2, which is then deposited on the Ru film 14A. Therefore, as shown in Figure 4, a RuO2 film 16 is formed on the surface of the Ru film 14A during etching. However, a reaction occurs between the CO gas and RuO2, as shown in Equation 1 below, and RuO2 is reduced to Ru. Therefore, the RuO2 film 16 quickly disappears. RuO2+2CO→Ru+2CO2...Formula 1

[0018] After a predetermined time has elapsed since the start of the supply of O gas and CO gas, the supply of these gases is stopped, and a film formation gas is supplied to form the Ru film 14B. As described above, in this first processing example, after the film formation gas is supplied to the wafer W and before the next film formation gas is supplied to the wafer W, an etching process using O gas and a reduction process using CO gas are performed in parallel.

[0019] The supply start timings of O gas and CO gas may be staggered and not coincident with each other, and similarly, the supply stop timings of O gas and CO gas may be staggered and not coincident with each other. When the supply stop timings are staggered, for example, the supply of CO gas is stopped later than the supply of O gas to prevent the Ru film 14B from being formed in a state where the RuO film 16 has already been formed.

[0020] Next, as another example of etching and reduction performed during film formation, a second processing example in which O3 gas and CO gas are supplied sequentially to the wafer W will be described with reference to Figure 5. First, O3 gas is supplied to the wafer W to etch the Ru film 15 on the sidewall of the recess 13 as described above (step S1). After a predetermined time has elapsed since the start of the O3 gas supply, the supply of O3 gas is stopped to complete step S1, and N2 (nitrogen gas) is supplied into the processing chamber and exhausted, thereby purging the O3 gas (step S2).

[0021] After a predetermined time has elapsed since the end of step S1 (stopping the supply of O3 gas), CO gas is supplied to the wafer W to reduce the RuO2 film 16 formed on the surface of the Ru film 14A. After a predetermined time has elapsed since the start of the CO gas supply, the supply of CO gas is stopped, completing step S2, and N2 is supplied into the processing chamber and exhausted, thereby purging the CO gas (step S4). After a predetermined time has elapsed since the end of step S3 (stopping the supply of CO gas), O3 gas is supplied to the wafer W and step S1 is performed again, and then steps S2 to S4 are performed again.

[0022] As described above, in the second processing example, a cycle consisting of steps S1 to S4 is repeatedly performed. During one cycle, the Ru film 15 formed on the sidewall of the recess 13 is etched, and the RuO2 film 16 formed by the etching is reduced. The number of cycle repetitions is preset so that the Ru film 15 is sufficiently removed. Therefore, when this cycle is performed by the control unit of the apparatus described later, as shown in FIG. 5, after step S4, it is determined whether the cycle has been repeated a preset number of times (step S5), and if it is determined that the cycle has been repeated the set number of times, the repetition is stopped. As described above, in this second processing example, after the film formation gas is supplied to the wafer W, the etching process using O3 gas and the reduction process using CO gas are sequentially repeated before the next film formation gas is supplied.

[0023] Either the first or second process example described above may be used, but the first process example, which simultaneously performs oxidation and reduction, requires a shorter processing time. In other words, the first process example is preferable from the viewpoint of increasing throughput by preventing a long time from being required between the end of formation of the Ru film 14A and the start of formation of the Ru film 14B.

[0024] The reducing gas is not limited to CO gas, which is the first reducing gas, but may also be H (hydrogen) gas, which is the second reducing gas. A third process example using H gas in addition to CO gas is shown in FIG. 6. This third process example is a modification of the second process example. The differences from the second process example are as follows: First, steps S1 to S4 are performed as in the second process example. Then, step S3′ is performed, in which H gas is supplied to the wafer W for a predetermined time. Following step S3′, a step (referred to as S4′) is performed to purge the processing chamber for a predetermined time, similar to steps S2 and S4. This cycle consisting of steps S1 to S4, S3′, and S4′ is repeated a required number of times.

[0025] 6, CO gas is supplied to the wafer W first out of CO gas and H gas, but either CO gas or H gas may be supplied to the wafer W first, and therefore the order of steps S3 and S3′ may be reversed. Note that H gas and CO gas may be supplied into the processing chamber simultaneously to increase throughput.

[0026] Next, a fourth process example will be described, which uses H2 gas as in the third process example. First, a step of simultaneously supplying O3 gas and CO gas to the wafer W is performed, as in the first process example. Then, a step of purging the processing vessel is performed, as in steps S2 and S4 of the third process example. After that, steps S3' and S4' of the third process example are performed. That is, H2 gas is supplied to the wafer W, and the processing vessel is purged, in that order. These steps are then repeated a predetermined number of times. As described above, in this fourth process example and the third process example described above, CO gas, which is a reducing gas, and H2 gas are supplied to the wafer W in that order.

[0027] Next, a substrate processing apparatus 2, which is an example of an apparatus capable of carrying out the above-described first to fourth processing examples, will be described with reference to the vertical cross-sectional side view of Fig. 7. The substrate processing apparatus 2 includes a processing vessel 21. A transfer port 22 is formed in the sidewall of the processing vessel 21 for loading and unloading a wafer W into and from the processing vessel 21, and a transfer mechanism provided outside the processing vessel 21 loads and unloads the wafer W into and from the processing vessel 21 through the transfer port 22. A gate valve 23 for opening and closing the transfer port 22 is provided, and the transfer port 22 is closed except when necessary for loading and unloading the wafer W.

[0028] The upstream end of an exhaust pipe 24 opens into the processing vessel 21. The downstream side of the exhaust pipe 24 is connected to a vacuum exhaust mechanism 25 including a valve, a vacuum pump, etc. The vacuum exhaust mechanism 25 evacuates the processing vessel 21 through the exhaust pipe 24 and adjusts the amount of exhaust to maintain the pressure inside the processing vessel 21 at a desired vacuum pressure.

[0029] A mounting table 26 on which a wafer W is placed is provided within the processing vessel 21. A heater 27 is embedded inside the mounting table 26 as a heating unit for heating the wafer W on the mounting table 26. Note that the processing vessel 21 is provided with a plurality of pins that protrude and sink into the upper surface of the mounting table 26 to transfer the wafer W to and from the transfer mechanism described above, but these are not shown in the drawing.

[0030] The ceiling of the processing vessel 21 is configured as a gas shower head 31 that is circular in plan view. The lower surface of the gas shower head 31 faces the upper surface of the mounting table 26. An outlet port 32 is formed in the lower surface of the gas shower head 31, and gas supplied to the gas shower head 31 is dispersed in a diffusion space 33 that is circular in plan view and provided within the gas shower head 31, and is then discharged from the outlet port 32 onto the wafer W on the mounting table 26. The gas shower head 31 is shown in a simplified form in FIG. 7 , and its detailed configuration will be described later.

[0031] Next, the pipes connected to the gas shower head 31 will be described. The downstream end of pipe 41 is connected to the center of the gas shower head 31 so that gas can be introduced into the center of the diffusion space 33. The upstream side of pipe 41 is connected to a source container 43 via a flow meter 42 and a valve V1, and opens into the source container 43. The source container 43 is equipped with a heating unit (not shown) and can heat a solid ruthenium source 44 stored therein. An example of this ruthenium source 44 is dodecacarbonyltriruthenium (DCR, Ru3(CO) 12 )

[0032] The downstream end of pipe 45 is connected to and opens into raw material container 43. The upstream side of pipe 45 is connected to a CO gas supply source 61 that supplies CO gas to the downstream side via valves V2, V3, and flow rate adjuster M1. Note that gas supply sources other than CO gas supply source 61, which will be described later, also supply gas to the downstream side in the same manner as CO gas supply source 61. Note that flow rate adjuster M1 and other flow rate adjusters, which will be described later, are configured, for example, with mass flow controllers, and adjust the flow rate of gas supplied from the gas supply sources so that the flow rate to the downstream side of the pipe becomes a desired flow rate.

[0033] With the above-described configuration, CO gas can be supplied from the CO gas supply source 61 into the source container 43. When the CO gas is supplied in this manner, the ruthenium source 44 is vaporized and supplied as a film formation gas together with the CO gas into the processing container 21 via the diffusion space 33. Therefore, the CO gas supplied to the source container 43 serves as a carrier gas for the film formation gas.

[0034] The downstream ends of pipes 51 and 52 are connected to the gas showerhead 31 so that gas can be introduced into the center and periphery of the diffusion space 33. Valves V4 and V5 are provided in the pipes 51 and 52, respectively. The pipes 51 and 52 are connected to each other upstream of the positions where the valves V4 and V5 are provided to form a junction pipe 53. The upstream side of the junction pipe 53 branches into five branches, one of which is connected to the pipe 45 between the valves V2 and V3.

[0035] The other four branches upstream of the junction pipe 53 are designated pipes 54, 55, 56, and 57. The upstream side of pipe 54 is connected between flow rate regulator M1 in pipe 45 and a CO gas supply source 61 via a valve V6 and a flow rate regulator M2. The upstream side of pipe 55 is connected to an H gas supply source 62 via a valve V7 and a flow rate regulator M3. The upstream side of pipe 56 is connected to an O (oxygen) gas supply source 63 via a valve V8, an ozonizer 58, and a flow rate regulator M4. The ozonizer 58 generates O gas from O gas supplied from the O gas supply source 63 and supplies it downstream together with the O gas. Therefore, the O gas is supplied to the wafer W as a mixed gas with O gas. The ozonizer 58 is configured so that the concentration of O gas in this mixed gas can be appropriately changed. The upstream side of the pipe 57 is connected to an N2 gas supply source 64 via a valve V9 and a flow rate regulator M5 in this order. The N2 gas serves as a purge gas for purging the processing vessel 21 and also as a carrier gas for CO gas, H2 gas, and O3 gas, and is constantly supplied into the processing vessel 21 while etching and reduction of the wafer W are being performed between film formation processes, for example.

[0036] Next, the configuration of the gas showerhead 31 will be described in detail with reference to the vertical cross-sectional side view of FIG. 8 . The gas showerhead 31 includes a horizontal, circular first plate 71, a second plate 72, and a third plate 73, which are arranged downward with a gap between them. The third plate 73 forms the lower surface of the gas showerhead 31 and has an outlet 32 ​​formed therein. The first plate 71 and the second plate 72 divide the space formed within the gas showerhead 31 into upper and lower sections. The diffusion space 33 described above is a three-tiered space formed by a space 71A between the first plate 71 and the ceiling 74 of the gas showerhead 31, a space 72A between the first plate 71 and the second plate 72, and a space 73A between the first plate 71 and the second plate 72.

[0037] The first plate 71, the second plate 72, and the third plate 73 each have through holes. These through holes are arc-shaped slits formed along the circumferential direction of each plate, and each slit is formed, for example, so that a circle centered at the center of the plate is divided into multiple equal parts. The first plate 22, the second plate 23, and the third plate 24 have different numbers of slits at different radial positions, with the lower plates having more slits. In a plan view, the center of the width of the slits in the adjacent upper plate among the first plate 71, the second plate 72, and the third plate 73 coincides with the center of the slits in the adjacent lower plate. Therefore, the slits of adjacent plates do not overlap in a plan view. The slits in the first plate 71 and the second plate 72 are indicated as 71B and 72B, respectively, in the figure, and the slit in the third plate 73 is the discharge port 32 described above.

[0038] The first plate 71 is provided with an outlet port 82, which is a slit for discharging gas supplied from the pipe 52, as described below. The slit 71B of the first plate 71 is formed separately from the outlet port 82 and is a slit for allowing gas supplied from the pipes 41 and 51 to flow.

[0039] A first ring 75 is provided at the center of the underside of a ceiling 74 of the gas showerhead 31, and the aforementioned pipe 41 opens into the area surrounded by the first ring 75, allowing gas to be introduced from the pipe 41 to the center of the diffusion space 33. The aforementioned pipe 51 is connected to the center of the ceiling 74 so as to supply gas to an outlet 76 formed on the underside of the ring body 75, and gas is introduced from the pipe 51 through the outlet 76 to the center of the diffusion space 33. The pipe 51 and the outlet 76 form a first flow path that supplies gas to the center of the diffusion space 33. Although not shown in FIG. 7 , as shown in FIG. 8 , for example, the downstream end of the pipe 51 branches into multiple parts, which are connected to the gas showerhead 31 so as to surround the downstream end of the pipe 41.

[0040] A second ring 81, which is a ring shape and extends along the periphery of the first plate 71, is provided on the upper surface of the periphery of the first plate 71, closer to the periphery than the slit 71B closest to the periphery. The outer periphery of the second ring 81 is connected to the sidewall of the gas shower head 31. A flow path is formed in the second ring 81 and the wall of the gas shower head 31 to allow the gas supplied from the piping 52 to flow. The gas that has passed through this flow path is supplied from an outlet 82 provided on the periphery of the first plate 71 to a space 72A between the first plate 71 and the second plate 72.

[0041] 9, which shows a cross section of the side wall and first plate 71 of the gas shower head 31 taken along the line AA'. As described above, the flow path connecting the pipe 52 and the outlet port 82 is composed of a gas flow path 84 and a buffer region 87 for diffusing the gas supplied from the gas flow path 84 in the circumferential direction of the gas shower head 31. Gas is supplied from the pipe 52 to the upstream end of the gas flow path 84. The gas flow path 84 and the buffer region 87 form a second flow path that flows from the periphery to the center of the diffusion space 33 and supplies gas to the periphery of the diffusion space 33.

[0042] 9, a buffer region 87 and a gas flow path 86 (described later) that forms part of the gas flow path 84 are indicated by a large number of dots. The buffer region 87 is a relatively wide annular space in plan view that is formed by closing a recess provided in the lower surface of the second ring 81 with the first plate 71, and the upper end of the discharge port 82 described above opens into the buffer region 87. Note that the discharge port 82 is a slit-shaped through-hole that is formed along the circumferential direction of the first plate 71 as shown in the figure, and has a shape obtained by equally dividing a ring centered at the center of the first plate 71 into multiple parts.

[0043] 8, a gas channel 84 is formed from the ceiling 74 of the gas shower head 31 through the sidewall to the second ring 81. The upstream side of this gas channel 84 is designated as a gas channel 85, and the downstream side is designated as a gas channel 86. The gas channel 85 extends vertically from the upper surface of the periphery of the gas shower head 31, then bends and extends horizontally toward the center of the gas shower head 31, and is connected to a gas inlet 86a, which is the upstream end of the gas channel 86.

[0044] The gas flow path 86 branches from a gas inlet 86a into two circumferentially directed gas flow paths 86b, which then branch into two circumferentially directed gas flow paths 86d at their tips via a radially directed gas flow path 86c. Gas is supplied to the buffer region 87 from four gas flow paths 86e connected to the tips. The connection ports of the gas flow paths 86 with the buffer region 87 (the outlets of the gas flow paths 86e) are evenly arranged around the circumference of the ring-shaped buffer region 87. In this way, the gas flow path 86 is formed like a bent tournament diagram in a plan view, and four branches from the gas inlet 86a are connected to the buffer region 87. However, the number of branches of the gas flow path 86 is not limited to four, and any plural number will do. Such gas flow paths 86 enable gas to be evenly supplied to each circumferentially separated location of the buffer region 87.

[0045] With the piping system and gas shower head 31 configured as described above, CO gas, H gas, O gas, and N gas can be independently supplied to the diffusion space 33 in addition to the film formation gas (DCR gas). By combining the open / close states of the valves V4 and V5, it is possible to select whether to supply CO gas, H gas, O gas, and N gas to only the center or periphery of the diffusion space 33, or to both.

[0046] Depending on the process conditions, the user of the apparatus can set whether to supply gas to the center and periphery of the diffusion space 33 or to either the center or periphery before processing the wafer W. When reduction and etching are performed at different times, as in the third processing example shown in FIG. 6, it is also possible to set whether to supply gas to the center and periphery or to either the center or periphery for each of the reduction and etching processes. Furthermore, when processing a single wafer W, the etching gas and the reduction gas may be supplied to either the center or periphery for a predetermined time and then to the other for a predetermined time. In the evaluation test described below, O gas was supplied to the periphery of the diffusion space 33, and favorable results were obtained. However, the gas may be supplied to the center or both the center and periphery.

[0047] 7, the gas shower head 31, the source material container 43, the flow rate adjuster M1, and the CO gas supply source 61 form a film formation processing unit, while the gas shower head 31, the flow rate adjuster M2, and the CO gas supply source 61 form a reduction processing unit. The gas shower head 31, the ozonizer 58, the flow rate adjuster M4, and the O gas supply source 63 form an etching processing unit. Therefore, the gas shower head 31 is a gas shower head common to the film formation processing unit, the etching processing unit, and the reduction processing unit.

[0048] The substrate processing apparatus 2 is equipped with a control unit 20, which is a computer, and this control unit 20 includes a program, a memory, a CPU, etc. The program incorporates commands (each step) for performing the above-described processing of the wafer W and transport of the wafer W. This program is stored on a storage medium, such as a compact disc, a hard disk, a magneto-optical disc, or a DVD, and is installed in the control unit 20. The control unit 20 outputs control signals to each part of the substrate processing apparatus 2 based on the program, thereby controlling the operation of each part. Specifically, the above control signals control operations such as opening and closing each valve to supply and cut off each gas to the gas shower head 31, adjusting the pressure inside the processing chamber 21 by the vacuum exhaust mechanism 25, and adjusting the temperature of the wafer W by controlling the output of the heater 27.

[0049] 5 is performed as an example of a process performed between film formation processes, the operation of the substrate processing apparatus 2 will be described. The pressure inside the processing chamber 21 is set to, for example, 0.5 Pa to 15 Pa. Meanwhile, the temperature of the wafer W placed on the mounting table 26 is set to 150°C to 250°C. Then, a film formation gas is supplied from the gas shower head 31, and a Ru film 14A is formed as shown in FIG.

[0050] After the supply of the film forming gas is stopped, N2 gas is supplied into the processing chamber 21, and the following cycle is repeated: supply of O3 gas from the gas shower head 31, purging of the processing chamber 21 by stopping the supply of O3 gas, supply of CO gas, and purging of the processing chamber 21 by stopping the supply of CO gas. That is, the cycle consisting of steps S1 to S4 described above is repeated. Note that the O3 gas and CO gas are supplied to the wafer W via the second diffusion space 33 of the gas shower head 31. When O3 gas is supplied in step S1, the pressure in the processing chamber 21 is set to, for example, 0.5 Pa to 15 Pa, and the temperature of the wafer W is set to, for example, 150°C to 250°C. When CO gas is supplied in step S3, the pressure in the processing chamber 21 is set to, for example, 0.5 Pa to 15 Pa, and the temperature of the wafer W is set to, for example, 150°C to 250°C.

[0051] After the above cycle is repeated a preset number of times, the supply of N2 gas into the processing vessel 21 is stopped, and a film formation gas is supplied from the gas shower head 31 under the same processing conditions as those used to form the Ru film 14A, to form the Ru film 14B, and the recess 13 is filled with the Ru film 14 as shown in Figure 3. This series of processes is performed by controlling the operation of each part of the substrate processing apparatus 2 using control signals output from the control unit 20. Similarly, when the first, third, or fourth processing example is performed between film formation processes instead of the second processing example, the operation of each part of the apparatus is controlled using control signals from the control unit 20.

[0052] The first and fourth process examples include a step in which both O gas and CO gas are supplied to the wafer W, and in this step, the pressure in the process vessel 21 is set to, for example, 0.5 Pa to 15 Pa, and the temperature of the wafer W is set to, for example, 150°C to 250°C. The third and fourth process examples include a step in which H gas is supplied to the wafer W, and in this step, the pressure in the process vessel 21 is set to, for example, 0.5 Pa to 15 Pa, and the temperature of the wafer W is set to, for example, 150°C to 250°C.

[0053] Incidentally, the Ru film 14 has been described as being formed as Ru films 14A and 14B when filling the recess 13. That is, the film formation process has been described as being performed in two separate steps. The film formation process is not limited to being performed in two separate steps, but may be performed in three or more separate steps. When performing the film formation process in three or more separate steps, the etching and reduction steps described above can be performed between each film formation process. In addition, in the second to fourth process examples described above, a purging step is performed inside the processing vessel to prevent reactions between the gases supplied to the wafer W and reliably minimize the impact on the processing of the wafer W. However, this purging step may be omitted. Furthermore, in the second to fourth process examples, the cycle is described as being performed repeatedly, but it may be performed only once without repeating.

[0054] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive, and various omissions, substitutions, modifications, and combinations may be made in the above-described embodiments without departing from the scope and spirit of the appended claims.

[0055] [Evaluation test] The following describes evaluation tests conducted in relation to this technology. Evaluation Test 1 In Evaluation Test 1, as described in the embodiment, Ru films 14A and 14B were formed by performing film formation processes on the wafer W in two separate steps, thereby filling the recess 13 with the Ru film 14. Between the film formation processes for forming the Ru films 14A and 14B, the third process example described in FIG. 6 was performed. That is, a cycle of sequentially supplying O gas, CO gas, and H gas to the wafer W was repeated multiple times. After filling with the Ru film 14, images of the longitudinal side of the recess 13 were obtained using a transmission electron microscope (TEM). In Comparative Test 1, the same process as Evaluation Test 1 was performed except that the cycle performed between the film formation processes was a cycle of sequentially supplying O gas and H gas. Therefore, in Comparative Test 1, CO gas was not supplied to the wafer W between the film formation processes.

[0056] FIG. 10 shows an image acquired from a wafer W in Comparative Test 1, and FIG. 11 shows an image acquired from a wafer W in Evaluation Test 1. In Comparative Test 1, the interface between Ru film 14A and Ru film 14B is relatively clearly observed at the position indicated by the arrow in the image. It is presumed that the reason the interface is observed in this manner is because Ru at this interface is oxidized. On the other hand, in Evaluation Test 1, the interface between Ru film 14A and Ru film 14B is observed at the position indicated by the arrow in the image, but this interface is less clear than in Comparative Test 1. From the above, it is presumed that the treatment in Evaluation Test 1 can reduce the content of oxidized Ru in Ru film 14 compared to the treatment in Comparative Test 1, thereby suppressing an increase in wiring resistance value.

[0057] Evaluation Test 2 In evaluation tests 2 (2-1 to 2-6), a substrate processing apparatus having substantially the same configuration as the substrate processing apparatus 2 was used to perform film formation processing on each wafer W in two separate steps (i.e., forming Ru films 14A and 14B) to fill the recesses 13 with the Ru film 14. Between evaluation tests 2-1 to 2-6, the processing performed on the wafer W between the formation of the Ru film 14A and the formation of the Ru film 14B was different. After the Ru film 14 was filled into the recesses 13 for each wafer W, the distribution of oxygen atom concentration in the depth direction of the recesses 13 filled with the Ru film 14 was measured by secondary ion mass spectrometry (SIMS).

[0058] The following describes the processes performed between the formation of the Ru film 14A and the formation of the Ru film 14B in each of Evaluation Tests 2-1 to 2-6. In Evaluation Test 2-1, a cycle consisting of supplying O3 gas and CO gas to the wafer W and supplying H2 gas to the wafer W was repeated nine times, with the pressure inside the processing chamber during the supply of O3 gas and CO gas being 1 Torr (133.3 Pa). In Evaluation Test 2-2, a cycle consisting of supplying O3 gas and CO gas to the wafer W and supplying H2 gas to the wafer W was repeated 12 times, with the pressure inside the processing chamber during the supply of O3 gas and CO gas being 1 Torr. In Evaluation Tests 2-1 and 2-2, the supply time of O3 gas and CO gas to the wafer W in one cycle was 20 seconds, and O3 gas and CO gas were simultaneously supplied to the wafer W for the same period in one cycle. In other words, the supply start and stop timings of O3 gas and CO gas in one cycle were synchronized.

[0059] In evaluation test 2-3, a cycle consisting of supplying O gas to wafer W and supplying CO gas to wafer W was repeated 12 times, and the pressure inside the processing chamber during CO gas supply was 8 Torr. The time for supplying CO gas to wafer W was 120 seconds. As described above, in evaluation tests 2-1 to 2-3, CO gas was supplied to wafer W as a reducing gas as described in the embodiment, and evaluation tests 2-1 and 2-2 were performed using the fourth processing example, and evaluation test 2-3 was performed using the second processing example shown in FIG.

[0060] In evaluation test 2-4, after the Ru film 14A was formed, the Ru film 14B was formed without etching or reduction. In evaluation test 2-5, a cycle consisting of supplying O gas to the wafer W and supplying H gas to the wafer W was repeated eight times. In evaluation test 2-6, O gas and H gas were supplied to the wafer W for 60 seconds, and the pressure inside the processing chamber during these gas supply was set to 500 mTorr. As described above, evaluation tests 2-4 to 2-6 are comparative tests in which CO gas is not supplied to the wafer W as a reducing gas.

[0061] In Evaluation Tests 2-3 and 2-5, the O3 gas was supplied for 5 seconds, and the pressure inside the processing chamber during this O3 gas supply was 100 mTorr (13.3 Pa). In Evaluation Tests 2-1, 2-2, and 2-5, the H2 gas was supplied for 60 seconds, and the pressure inside the processing chamber during this H2 gas supply was 500 mTorr (66.7 Pa). The processing conditions other than those described above were the same among Evaluation Tests 2-1 to 2-6. Therefore, the Ru films 14A and 14B were formed under the same processing conditions among Evaluation Tests 2-1 to 2-6.

[0062] The substrate processing apparatus used in Evaluation Test 2 differs from the substrate processing apparatus 2 described in the embodiment in that CO gas and H2 gas are introduced only into the center of the diffusion space 33. O3 gas is supplied to the center and periphery of the diffusion space 33. The gas flow rates supplied into the processing chamber between film formation processes are set as follows: the flow rate of H2 gas is 1 slm; the flow rate of O2 gas supplied into the processing chamber via the ozonizer 58 is 1 slm, and the O3 concentration in the mixed gas of O2 gas and O3 gas supplied from the ozonizer 58 is 300 g / m 3 It was decided.

[0063] Figure 12 shows a graph obtained by SIMS, with the horizontal axis representing depth (unit: nm) and the vertical axis representing oxygen atom concentration (unit: atoms / cm 3) are shown. Actual test results were obtained as a graph showing the oxygen atomic concentration in the depth range of 0 nm to 80 nm, but the graph shown in FIG. 12 is a partial cutout of that graph, and shows the oxygen atomic concentration at a depth of 50 nm to 80 nm, which is the range that includes the interface between the Ru films 14A and 14B. This interface is estimated to be located at a depth of 60 nm to 70-odd nm, shown as range L in the figure.

[0064] In evaluation test 2-4, where etching with O3 gas was not performed, the oxygen atom concentration was approximately 0 atoms / cm in range L. 3 In the range L, the oxygen atom concentration values ​​in the evaluation tests 2-1 to 2-3 in which reduction with CO gas was performed were lower than those in the evaluation tests 2-5 and 2-6 in which the etching was performed but reduction with CO gas was not performed. Therefore, this evaluation test 2 confirmed that reduction with CO is effective in reducing the amount of oxidized Ru in the Ru film 14 after filling, demonstrating the effectiveness of this technology.

[0065] Evaluation Test 3 In evaluation test 3-1, a Ru film was formed on a wafer W using the substrate processing apparatus 2 described above, and the Ru film was then etched using O3 gas. The Ru film thickness distribution and the Ru etching amount distribution within the wafer W were examined. To examine this distribution, measurements were taken at multiple locations within the wafer W using XRF (X-ray fluorescence analysis). After the measurements, the average values ​​and 1σ were calculated for the film thickness and etching amount. O3 gas was supplied to the periphery of the diffusion space 33. That is, the gas was discharged from the discharge port 82 described in FIG. 7. In evaluation test 3-2, a test similar to evaluation test 3-1 was conducted using a substrate processing apparatus with a slightly different configuration from the substrate processing apparatus 2. The substrate processing apparatus used in evaluation test 3-2 was configured to introduce O3 gas closer to the center of the diffusion space 33 than the position where O3 gas was introduced in evaluation test 3-1. Furthermore, the width of each outlet 32 ​​of the substrate processing apparatus 2 used in evaluation test 3-1 was uniform, whereas the width of the outlet 32 ​​of the gas shower head 31 used in evaluation test 3-2 was larger for outlets 32 located closer to the periphery of the gas shower head 31.

[0066] Looking at the results of evaluation test 3-1, the average value for the Ru film thickness was 24.6 nm, 1σ was 2.5%, and the average value for the etching amount was 9.8 nm, 1σ was 2.0%. In evaluation test 3-2, the average value for the Ru film thickness was 24.0 nm, 1σ was 2.3%, and the average value for the etching amount was 9.0 nm, 1σ was 4.5%.

[0067] As described above, there was no significant difference in the average thickness or 1σ of the Ru film between Evaluation Tests 3-1 and 3-2. Regarding the etching amount, there was no significant difference in the average thickness between Evaluation Tests 3-1 and 3-2. However, the 1σ value was sufficiently low in both Evaluation Tests 3-1 and 3-2, but was very small in Evaluation Test 3-1. These results demonstrate that highly uniform processing of wafers W can be achieved by appropriately configuring the flow path shape in the gas shower head 31 and the O3 gas introduction position into the diffusion space 33. Furthermore, it was also demonstrated that such highly uniform processing can be achieved when at least the second ring 81 is provided to allow O3 gas to be introduced to the peripheral portion of the diffusion space 33.

[0068] Evaluation Test 4 In Evaluation Test 4, a Ru film 14 was formed using the substrate processing apparatus 2 described in the embodiment, and both O3 gas and CO gas were supplied to the wafer W. That is, etching and reduction were simultaneously performed as described in Processing Example 1 in the embodiment. The processing conditions during the supply of O3 gas and CO gas were changed for each wafer W, and the etching amount was measured for each wafer W after processing. Specifically, the pressure within the processing chamber 21 during the supply of O3 gas and CO gas, the flow rate of O2 gas supplied into the processing chamber 21 via the ozonizer 58, the concentration of O3 gas in the gas supplied downstream from the ozonizer 58, and the etching time (the supply time of O3 gas and CO gas) were each changed between wafers W.

[0069] More specifically, reference values ​​were set for three parameters, namely, the pressure inside the processing vessel 21, the flow rate of O2 gas, and the concentration of O3 gas, and wafers W were processed with these three parameters set to the reference values. In addition, wafers W were processed with any of these three parameters changed from the reference value. The reference values ​​for the pressure inside the processing vessel 21, the flow rate of O2 gas, and the concentration of O3 gas were 100 mTorr (13.3 Pa), 800 sccm, and 300 g / m, respectively. 3The etching time was set to either 300 seconds, 600 seconds, or 900 seconds. Other processing conditions were the same for each wafer W, and for example, the CO flow rate was 200 sccm. In this evaluation test 4, O3 gas and CO gas were supplied only to the center of the diffusion space 33.

[0070] 13 to 15 show the results of Evaluation Test 4. FIG. 13 shows the relationship between the pressure in the processing vessel 21 and the etching amount at each etching time, FIG. 14 shows the relationship between the O2 gas flow rate and the etching amount at each etching time, and FIG. 15 shows the relationship between the O3 gas concentration and the etching amount at each etching time. As shown in the graph in FIG. 11, the pressure in the processing vessel 21 was set to 50 mTorr (6.67 Pa), which was shifted from the reference value (100 mTorr). At each etching time, the etching amount was greater at 50 mTorr than at 100 mTorr. While a sufficient etching amount was obtained at 100 mTorr, a better etching amount was obtained at 50 mTorr. These results confirm that a sufficient amount of etching can be achieved by keeping the pressure in the processing vessel 21 at least 100 mTorr or less.

[0071] As shown in the graphs of Figures 14 and 15, the flow rate of O2 gas and the concentration of O3 gas were below the reference values ​​(800 sccm, 300 g / m 3 ) and the values ​​shifted from 1000sccm and 300g / m 3 As shown in each graph, the etching amount increased when the O2 gas flow rate and the O3 gas concentration were higher. [Explanation of symbols]

[0072] W wafer 13 Recess 14 Ruthenium film

Claims

1. a step of supplying a film-forming gas to a substrate having a recess formed therein to form a ruthenium film in the recess, and stopping the supply of the film-forming gas to the substrate before the recess is completely filled with the ruthenium film; an etching step of supplying an oxidation gas to the substrate to oxidize and remove the ruthenium film formed on the side surface of the recess; a reduction step of supplying a first reducing gas, which is carbon monoxide gas, to the substrate in order to reduce the surface of the ruthenium film remaining on the bottom side of the recess, which surface has been oxidized by the oxidation gas; supplying the film-forming gas to the substrate again to fill the recess with the ruthenium film; A substrate processing method comprising:

2. After the film formation gas is supplied to the substrate, until the film formation gas is next supplied to the substrate, 2. The substrate processing method according to claim 1, wherein the etching step and the reducing step are repeated in sequence.

3. After the film formation gas is supplied to the substrate, until the film formation gas is next supplied to the substrate, 2. The substrate processing method according to claim 1, wherein the etching step and the oxidation step are performed in parallel.

4. 2. The substrate processing method according to claim 1, wherein the reducing step includes the step of supplying a second reducing gas, which is hydrogen gas, to the substrate.

5. 5. The substrate processing method according to claim 4, wherein the reducing step includes the step of supplying a first reducing gas and a second reducing gas in that order.

6. a processing vessel for storing a substrate having a recess formed therein; a film formation processing unit for supplying a film formation gas into the processing vessel to form a ruthenium film in the recess; an etching processing unit that supplies an oxidation gas into the processing chamber to oxidize and remove the ruthenium film formed on the side surface of the recess; a reduction processing unit that supplies a first reducing gas, which is carbon monoxide gas, into the processing vessel in order to reduce a surface of the ruthenium film remaining on the bottom side of the recess that has been oxidized by the oxidizing gas; a control unit that stops the supply of the film formation gas to the substrate before the filling of the recessed portion with the ruthenium film is completed, and outputs a control signal to supply the film formation gas to the substrate again to fill the recessed portion with the ruthenium film after the surface of the ruthenium film has been reduced by the first reducing gas; A substrate processing apparatus comprising:

7. the film formation processing unit, the etching processing unit, and the reduction processing unit are provided with a common gas shower head, a first flow path for supplying gas to a center of a diffusion space provided in the gas shower head; a second flow path extending from the periphery to the center of the diffusion space to supply gas to the periphery of the diffusion space; The substrate processing apparatus according to claim 6 , wherein the oxidizing gas is supplied to the first flow path or the second flow path.

Images