Substrate processing method and substrate processing device

Abstract

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.

Description

Substrate processing method and substrate processing apparatus

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

[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 as to etch the portions of the ruthenium film formed on the side surfaces of the recesses. 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.

[0003] Japanese Patent Application Laid-Open No. 2023-45017

[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.

[0005] The film formation method of the present disclosure includes the steps 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 to reduce the surface of the ruthenium film remaining on the bottom side of the recess that has been oxidized by the oxidation gas; and a step of supplying the film formation gas to the substrate again to fill the recess with the ruthenium film.

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

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

[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 such as 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. Note that 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 in which 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 at least until the upper surface of the Ru film 14 reaches the upper edge of the recess 13. In order to achieve this filling, 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 designated as 15 in the figure to distinguish it from the Ru film 14 formed on the bottom wall.

[0012] If the supply of the film-forming 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. If this were to happen, the opening of the recess 13 would be blocked before the Ru film 14 was filled into the recess 13, which could prevent the film-forming gas from being supplied into the recess 13. In this case, voids would be formed in the Ru film 14. To prevent this, the supply of the film-forming gas to the wafer W is temporarily stopped before the recess 13 is completely filled with the Ru film 14. Then, O 2 is supplied to the wafer W as an etching gas (oxidizing gas). ３ (ozone) gas is supplied to remove the Ru film 15. ３ The surface of the Ru film 14 is oxidized by the gas supply to form RuO ２Since ruthenium oxide is generated, a reducing gas is supplied to reduce the surface. The right side of Figure 2 shows the state after etching and reduction. The dotted arrows in the figure indicate the oxidizing gas and reducing gas together.

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

[0014] 3, for the sake of convenience, the portion of the Ru film 14 filled in the recess 13 that is formed by the first supply of film formation gas may be referred to as Ru film 14A, and the portion that is formed by the second supply of 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 below, 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. ３The supply of the SiO 2 gas and the CO gas into the processing chamber is started so that the etching and reduction are carried out in parallel.

[0017] O supplied to the wafer W ３ The surface of the Ru film 14A is oxidized by the gas, and part of it becomes RuO. ４ At this time, the Ru film 15 formed on the side wall of the recess 13 is also etched in the same manner as the surface of the Ru film 14A. ３ Due to oxidation by gas, part of the surface of the Ru film 14A becomes RuO ２ In addition, the vaporized RuO ４ A part of the ２ As a result, RuO is deposited on the surface of the Ru film 14A during etching, as shown in FIG. ２ However, the CO gas and RuO ２ The reaction shown in the following formula 1 occurs between RuO ２ is reduced to Ru. Therefore, RuO ２ The film 16 disappears quickly. ２ +2CO→Ru+2CO ２ ...Formula 1

[0018] O ３ After a predetermined time has elapsed since the start of supplying the O and CO gases, the supply of these gases is stopped, and a film formation gas is supplied to form the Ru film 14B. ３ The etching step using the gas and the reduction step using the CO gas are carried out in parallel.

[0019] In addition, O ３ The timings at which the O and CO gases are supplied may not coincide with each other but may be shifted. ３ The timings at which the supply of the RuO gas and the CO gas is stopped may not coincide with each other but may be shifted. ２ In order to prevent the Ru film 14B from being formed in the state where the film 16 is formed, for example, O ３The timing for stopping the supply of CO gas is set later than the timing for stopping the supply of other gases.

[0020] Next, as another example of etching and reduction performed between film formation processes, O ３ A second processing example in which O gas and CO gas are supplied to the wafer W in this order will be described with reference to FIG. ３ Gas is supplied to the wafer W, and the Ru film 15 on the sidewall of the recess 13 is etched as described above (step S1). ３ After a predetermined time has elapsed since the start of gas supply, ３ The gas supply is stopped to complete step S1, and the inside of the processing vessel is filled with N ２ (nitrogen gas) is supplied and exhausted, ３ The gas is purged (step S2).

[0021] End of step S2 (O ３ After a predetermined time has elapsed since the gas supply was stopped, CO gas is supplied to the wafer W to remove the RuO formed on the surface of the Ru film 14A. ２ The film 16 is reduced (step S3). After a predetermined time has elapsed since the start of the supply of CO gas, the supply of CO gas is stopped, and step S3 is completed. ２ After a predetermined time has elapsed since the end of step S3 (stop of CO gas supply), the O ３ Gas is supplied to the wafer W and step S1 is performed again, and then steps S2 to S4 are performed again.

[0022] In this way, in the second processing example, the cycle consisting of steps S1 to S4 is repeated. In one cycle, the Ru film 15 formed on the side wall of the recess 13 is etched, and the RuO ２The film 16 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, after step S4, as shown in FIG. 5, 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, O is supplied to the wafer W after the film formation gas is supplied to the wafer W and before the next film formation gas is supplied. ３ The etching step using gas and the reduction step using CO gas are repeated in sequence.

[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, which is preferable from the viewpoint of increasing throughput by preventing a long time from being required from the end of formation of the Ru film 14A to the start of formation of the Ru film 14B.

[0024] The reducing gas is not limited to the first reducing gas, CO gas, but may be, for example, the second reducing gas, H ２ (hydrogen) gas may also be used. ２ A third processing example, which also uses gas, is shown in Fig. 6. This third processing example is a modification of the second processing example. The differences from the second processing example will be explained mainly in the following. First, after steps S1 to S4 are performed as in the second processing example, the wafer W is heated with H ２ Step S3' is performed to supply gas. Following step S3', a step (referred to as S4') is performed to purge the processing vessel for a predetermined time, similar to steps S2 and S4. This cycle consisting of steps S1 to S4, S3', and S4' is repeated as many times as necessary.

[0025] In the flow of FIG. 6, CO gas and H ２ Among the gases, CO gas is supplied to the wafer W first. ２ Either of the gases may be supplied to the wafer W first, and therefore the order of steps S3 and S3' may be reversed. ２The gas and CO gas may be supplied into the processing chamber simultaneously to increase throughput.

[0026] Next, as in the third processing example, ２ A fourth processing example using gas will be described. First, as in the first processing example, O ３ A step of simultaneously supplying H2O gas and CO2 gas to the wafer W is then performed. Thereafter, a step of purging the inside of the processing vessel is performed in the same manner as steps S2 and S4 of the third processing example. Thereafter, steps S3' and S4' of the third processing example are performed. That is, H2O gas and CO2 gas are simultaneously supplied to the wafer W. Thereafter, a step of purging the inside of the processing vessel is performed in the same manner as steps S2 and S4 of the third processing example ２ The gas is supplied to the wafer W, and the processing chamber is purged. These steps are repeated a predetermined number of times. As described above, in this fourth processing example and the third processing example, the reducing gas, CO gas, and H ２ The gases are supplied to the wafer W in this 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 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, through which a wafer W is loaded and unloaded into and from the processing vessel 21. 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 is provided for opening and closing the transfer port 22, and the transfer port 22 is kept 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 exhausts the inside of 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 a 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. Gas supplied to the gas shower head 31 is dispersed in a diffusion space 33 that is circular in a 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 a 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 the 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 is capable of heating a solid ruthenium source 44 stored therein. An example of this ruthenium source 44 is dodecacarbonyltriruthenium (DCR, Ru ３ (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 adjustment unit 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 adjustment unit M1 and other flow rate adjustment units, 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 source to the downstream side of the pipe to 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 shower head 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 on the upstream side of the junction pipe 53 are pipes 54, 55, 56, and 57. The upstream side of the pipe 54 is connected to the flow rate regulator M1 in the pipe 45 and the CO gas supply source 61 via a valve V6 and a flow rate regulator M2 in this order. The upstream side of the pipe 55 is connected to the H ２ The upstream side of the pipe 56 is connected to a gas supply source 62. The upstream side of the pipe 56 is connected to an O 2 gas supply source 62 via a valve V8, an ozonizer 58, and a flow rate adjusting unit M4 in this order. ２ The ozonizer 58 is connected to an oxygen gas supply source 63. ２ O supplied from the gas supply source 63 ２ Gas to O ３ Generate gas and O ２ It is supplied downstream together with the gas. ３ The gas is O ２ The mixed gas containing O and O2 is supplied to the wafer W. ３ The ozonizer 58 is configured so that the gas concentration can be changed as needed. The upstream side of the pipe 57 is supplied with N via a valve V9 and a flow rate adjusting unit M5 in this order. ２ This N ２The gas is a purge gas for purging the inside of the processing vessel 21 as described above, as well as CO gas, H ２ Gas, O ３ This gas is a carrier gas for the gas, and is constantly supplied into the processing chamber 21 while etching and reduction of the wafer W are 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 in this order 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 third plate 73 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 number of slits opening at different radial positions varies among the first plate 22, the second plate 23, and the third plate 24, with the number of slits increasing toward the lower plate. 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 gap between the slits in the adjacent lower plate. Therefore, the slits of adjacent plates do not overlap in a plan view. Note that 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 above-mentioned discharge port 32.

[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 the ceiling 74 of the gas shower head 31, and the aforementioned pipe 41 opens in 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 shower head 31 so as to surround the downstream end of the pipe 41.

[0040] A second ring 81, which is an annular ring, 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, and the outer periphery of the second ring 81 is connected to the side wall 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 flowed 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 of the gas shower head 31 and the first plate 71 taken along the line A-A'. 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 that is obtained by equally dividing a ring centered at the center of the first plate 71 into multiple parts.

[0043] 8 , the gas flow passage 84 extends from the ceiling 74 of the gas shower head 31 through the sidewall to the second ring 81. The upstream side of the gas flow passage 84 is designated as a gas flow passage 85, and the downstream side is designated as a gas flow passage 86. The gas flow passage 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 86 a, which is the upstream end of the gas flow passage 86.

[0044] The gas flow path 86 branches from a gas inlet 86a into two circumferentially extending gas paths 86b, which then branch into two circumferentially extending gas paths 86d via a radially extending gas path 86c at its tip. Gas is supplied to the buffer region 87 from four gas paths 86e connected to the tips. The gas paths 86's connection ports (outlets of the gas paths 86e) to the buffer region 87 are evenly spaced around the circumference of the ring-shaped buffer region 87. Thus, the gas flow path 86 is shaped like a curved tournament diagram in plan view, and branches from the gas inlet 86a into four paths that connect to the buffer region 87. However, the number of branches of the gas flow path 86 is not limited to four, and any number more than one may be used. This gas flow path 86 allows gas to be evenly supplied to each circumferentially separated location in the buffer region 87.

[0045] By configuring the piping system and the gas shower head 31 as described above, the diffusion space 33 is filled with CO gas, H gas, and the like in addition to the film forming gas (DCR gas). ２ Gas, O ３ Gas, N ２ The gases CO, H, and H can be supplied independently. ２ Gas, O ３ Gas, N ２ By combining the open and closed states of the valves V4 and V5, it is possible to select whether the gas is supplied to only one of the center and 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 one of the center and periphery before processing the wafer W. When reduction and etching are performed at different times as in the third processing example shown in Figure 6, it is also possible to set whether to supply gas to the center and periphery or to one of the center and periphery for each of reduction and etching. Furthermore, when processing one wafer W, the etching gas and the reducing gas may be supplied to one of the center and periphery for a predetermined time and then to the other for a predetermined time. Note that in the evaluation test described below, O ３Although preferable results were obtained by supplying the gas to the peripheral portion of the diffusion space 33, the gas may be supplied to the center portion, or may be supplied to both the center portion and the peripheral portion.

[0047] 7, the gas shower head 31, the source container 43, the flow rate adjusting unit M1, and the CO gas supply source 61 constitute a film formation processing unit, and the gas shower head 31, the flow rate adjusting unit M2, and the CO gas supply source 61 constitute a reduction processing unit. ２ The gas supply source 63 constitutes an etching processing section. Therefore, the gas shower head 31 is a gas shower head common to the film forming processing section, the etching processing section, and the reduction processing section.

[0048] The substrate processing apparatus 2 includes a control unit 20, which is a computer, and this control unit 20 includes a program, a memory, a CPU, etc. The program contains instructions (steps) for performing the above-described wafer W processing and wafer W transfer. 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 component of the substrate processing apparatus 2 based on the program, thereby controlling the operation of each component. Specifically, the 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 was stopped, N ２ The gas is supplied, and the O ３ Gas supply, O３ The process chamber 21 is purged by stopping the supply of gas, the CO gas is supplied, and the process chamber 21 is purged by stopping the supply of CO gas. This cycle is repeated. That is, the cycle consisting of steps S1 to S4 described above is repeated. ３ The O gas and CO gas are supplied to the wafer W through the second diffusion space 33 of the gas shower head 31. ３ When the gas is supplied, the pressure inside 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 the CO gas is supplied in step S3, the pressure inside 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, N ２ The gas supply 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 Fig. 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 process example is performed between film formation processes instead of the second process example, the operation of each part of the apparatus is controlled using control signals from the control unit 20.

[0052] In the first and fourth processing examples, ３ The process includes a step in which both H gas and CO gas are supplied to the wafer W, and in this step, the pressure inside the processing 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. In the third and fourth processing examples, H ２ This step includes a step of supplying gas to the wafer W. In this step, the pressure inside 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.

[0053] The above description assumes that the Ru film 14 is formed as Ru films 14A and 14B when filling the recess 13. That is, the description assumes that the film formation process is performed in two separate steps. The film formation process is not limited to two separate steps, and 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 repeated, 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 Tests] Evaluation tests carried out in relation to the present technology will be described below. Evaluation Test 1 In Evaluation Test 1, as described in the embodiment, Ru films 14A and 14B were formed by performing film formation processing on the wafer W in two separate steps, thereby filling the Ru film 14 into the recess 13. Between the film formation processes for forming the Ru films 14A and 14B, the third processing example described in FIG. 6 was carried out. That is, O ３ Gas, CO gas, H ２ The cycle of supplying the gases in order to the wafer W was repeated multiple times. After filling with the Ru film 14, an image of the longitudinal cross-section of the recess 13 was obtained using a transmission electron microscope (TEM). ３ Gas, H ２ Except for the gas cycle being performed in order, the same processing as in Evaluation Test 1 was performed. Therefore, in Comparative Test 1, CO gas was not supplied to the wafer W between film forming 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 Test 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. The processing performed on the wafer W between the formation of the Ru film 14A and the formation of the Ru film 14B differed between Evaluation Tests 2-1 to 2-6. After the Ru film 14 was filled into the recesses 13 of 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 treatments performed between the formation of the Ru film 14A and the formation of the Ru film 14B in each of the evaluation tests 2-1 to 2-6 will be described. ３ supplying H gas and CO gas to the wafer W; ２ The cycle of supplying the gas to the wafer W is repeated nine times. ３ The pressure inside the processing vessel during the supply of O and CO gases was 1 Torr (133.3 Pa). ３ supplying H gas and CO gas to the wafer W; ２ This cycle of supplying the gas to the wafer W is repeated 12 times. ３ The pressure inside the processing chamber during supply of O gas and CO gas was 1 Torr.３ The supply time of the O gas and CO gas to the wafer W was 20 seconds. ３ The O gas and the CO gas are supplied to the wafer W at the same time for the same period. ３ The timings at which the supply of the gas and the CO gas is started and stopped are synchronized.

[0059] In evaluation test 2-3, O ３ A cycle consisting of supplying gas to the wafer W and supplying CO gas to the wafer W was repeated 12 times, and the pressure inside the processing vessel during CO gas supply was 8 Torr. The time for supplying CO gas to the wafer W was 120 seconds. As described above, in evaluation tests 2-1 to 2-3, CO gas was supplied to the 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. ３ Gas is supplied to the wafer W, and H ２ The cycle of supplying the gas to the wafer W was repeated eight times. ３ Gas and H ２ The gas was supplied to the wafer W for 60 seconds, and the pressure inside the processing vessel during this 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 the evaluation tests 2-3 and 2-5, ３ The gas supply time is 5 seconds. ３ The pressure inside the processing vessel during gas supply was 100 mTorr (13.3 Pa). ２ The gas supply time is 60 seconds. ２The pressure inside the processing vessel during gas supply was 500 mTorr (66.7 Pa). The processing conditions other than those described above were the same for evaluation tests 2-1 to 2-6. Therefore, the Ru films 14A and 14B were formed under the same processing conditions for evaluation tests 2-1 to 2-6.

[0062] The substrate processing apparatus used in this evaluation test 2 is different from the substrate processing apparatus 2 described in the embodiment in that it uses CO gas and H ２ The gas is introduced only into the center of the diffusion space 33. ３ The gas is supplied to the center and periphery of the diffusion space 33. The flow rate of the gas supplied into the processing chamber during the film formation process is set as follows: ２ The flow rate of the gas is 1 slm. ２ The gas is 1 slm, and the O supplied from the ozonizer 58 ２ Gas and O ３ O in the mixed gas ３ The concentration is 300 g / m ３ It was decided.

[0063] FIG. 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 between 60 nm and 70-odd nm, shown as range L in the figure.

[0064] O ３ In evaluation test 2-4, in which etching with gas was not performed, the oxygen atom concentration in range L was approximately 0 atoms / cm 3In the range L, the oxygen atomic 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 the present 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 O after the film formation was ３ The Ru film was etched using the gas, and the Ru film thickness distribution and the Ru etching amount distribution within the surface of the wafer W were examined. To examine this distribution, measurements were taken at multiple locations within the surface of 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, respectively. ３ The gas was supplied to the peripheral portion 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 carried out using a substrate processing apparatus having a slightly different configuration from the substrate processing apparatus 2. The substrate processing apparatus used in evaluation test 3-2 was the same as the substrate processing apparatus O in evaluation test 3-1. ３ The O gas was introduced into the diffusion space 33 at a position closer to the center of the diffusion space 33 than the position where the gas was introduced. ３ 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] The results of evaluation test 3-1 showed that the average thickness of the Ru film was 24.6 nm, 1σ was 2.5%, and the average etching amount was 9.8 nm, 1σ was 2.0%. In evaluation test 3-2, the average thickness of the Ru film was 24.0 nm, 1σ was 2.3%, and the average etching amount was 9.0 nm, 1σ was 4.5%.

[0067] As described above, there is no significant difference between evaluation tests 3-1 and 3-2 in terms of the Ru film thickness in terms of both the average value and 1σ. Regarding the etching amount, there is no significant difference between evaluation tests 3-1 and 3-2 in terms of the average value, but the 1σ result was sufficiently low in both evaluation tests 3-1 and 3-2, but was very small in evaluation test 3-1. These results suggest that the shape of the flow path in the gas shower head 31 and the amount of O 2 entering the diffusion space 33 are important factors. ３ It has been shown that by appropriately setting the gas introduction position, it is possible to perform highly uniform processing on the wafer W. Furthermore, by providing at least the second ring 81, the O ３ It was shown that when a configuration is adopted in which gas can be introduced, such highly uniform processing can be performed.

[0068] Evaluation Test 4 In evaluation test 4, the Ru film 14 was formed using the substrate processing apparatus 2 described in the embodiment. ３ Both O and CO gases were supplied to the wafer W. That is, etching and reduction were simultaneously carried out as described in the first processing example of the embodiment. ３ The processing conditions for supplying the O and CO gases were changed for each wafer W, and the etching amount was measured for each wafer W after processing. ３ The pressure in the processing vessel 21 when the gas and CO gas are supplied, the O gas supplied into the processing vessel 21 through the ozonizer 58, ２ The flow rate of the gas, the O content in the gas supplied downstream from the ozonizer 58 ３ Gas concentration, etching time (O ３ The combination of the supply time of the gas and the supply time of the CO gas was changed between the wafers W.

[0069] More specifically, the pressure in the processing vessel 21, O ２ Gas flow rate, O ３ Reference values ​​were set for a total of three parameters, namely, the gas concentration, and wafers W were processed with these three parameters set to the reference values. Also, wafers W were processed with any of these three parameters changed from the reference values. ２ Gas flow rate, O ３The reference values ​​for the gas concentrations are 100 mTorr (13.3 Pa), 800 sccm, and 300 g / m ３ The etching time was set to 300 seconds, 600 seconds, or 900 seconds. Other processing conditions were the same for each wafer W, and for example, the flow rate of CO was 200 sccm. ３ When supplying the gas and CO gas, these gases were supplied only to the center of the diffusion space 33 .

[0070] 13 to 15 show the results of Evaluation Test 4. 13 shows the relationship between the pressure in the processing vessel 21 and the amount of etching at each etching time, and 14 shows the relationship between the pressure in the processing vessel 21 and the amount of etching at each etching time. ２ The relationship between the gas flow rate and the etching amount is shown in FIG. 15. ３ 11 shows the relationship between the gas concentration and the etching amount. As shown in the graph of FIG. 11, the pressure inside 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. From these results, it was confirmed that a sufficient amount of etching could be achieved by keeping the pressure inside the processing vessel 21 at least 100 mTorr or less.

[0071] Furthermore, as shown in the graphs of FIGS. 14 and 15, ２ Gas flow rate, O ３ The gas concentration is the standard value (800 sccm, 300 g / m ３ ) and 1000 sccm and 300 g / m ３ As shown in each graph, ２ The higher the gas flow rate, the higher the O ３ The higher the gas concentration, the greater the etching amount.

[0072] W wafer 13 recess 14 ruthenium film

Claims

1. A substrate processing method comprising: 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 to reduce a surface of the ruthenium film remaining on the bottom side of the recess that has been oxidized by the oxidation gas; and a step of supplying the film-forming gas to the substrate again to fill the recess with the ruthenium film.

2. The substrate processing method according to claim 1, wherein the etching step and the reduction step are repeated in sequence from the time when the film forming gas is supplied to the substrate until the time when the film forming gas is next supplied to the substrate.

3. The substrate processing method according to claim 1, wherein the etching step and the oxidation step are carried out in parallel after the film forming gas is supplied to the substrate and before the film forming gas is next supplied to the substrate.

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

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

6. A substrate processing apparatus comprising: 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 for supplying an oxidation gas into the processing vessel to oxidize and remove the ruthenium film formed on the side surface of the recess; a reduction processing unit for supplying a first reducing gas, which is carbon monoxide gas, into the processing vessel to reduce a surface of the ruthenium film remaining on the bottom side of the recess that has been oxidized by the oxidation gas; and a control unit that outputs a control signal to stop the supply of the film formation gas to the substrate before filling of the recess with the ruthenium film is complete, and to supply the film formation gas to the substrate again to fill the recess with the ruthenium film after the surface of the ruthenium film has been reduced by the first reducing gas.

7. A substrate processing apparatus according to claim 6, wherein the film forming processing section, the etching processing section, and the reduction processing section are provided with a common gas shower head, and further comprising: a first flow path that supplies gas to a center of a diffusion space provided in the gas shower head; and a second flow path that runs through the diffusion space from the periphery to the center to supply gas to the periphery of the diffusion space, and the oxidizing gas is supplied to the first flow path or the second flow path.

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