Embedding method and processing system

Abstract

To provide an embedding method and a processing system that can embed a ruthenium film in a recessed part with good embedding properties.SOLUTION: An embedding method comprise the steps of: preparing a substrate having an insulation film having a recessed part formed and a metal film provided to be exposed to a bottom part of the recessed part; embedding a first ruthenium film from the bottom part to the middle of the recessed part through CVD using a ruthenium-containing gas while heating the substrate to a first temperature; and embedding a second ruthenium film on the first ruthenium film in the recessed part through CVD using the ruthenium-containing gas while heating the substrate to a second temperature lower than the first temperature.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present disclosure relates to an embedding method and processing system. [Background technology]

[0002] The manufacturing process of semiconductor devices includes a process of filling recesses such as trenches and holes with a metal film. For example, Patent Document 1 describes that when filling recesses with a tungsten (W) film by CVD, a part of the W film is formed at a first temperature, and the remaining part of the W film is formed at a second temperature that is higher than the first temperature.

[0003] As a filling metal, ruthenium (Ru), a low-resistance material, has attracted attention, and Patent Document 2 proposes a method of filling a substrate having a metal film at the bottom of a recess with a Ru film by CVD in a bottom-up manner starting from the metal film at the bottom. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2010-199349 A [Patent Document 2] JP 2020-43139 A Summary of the Invention [Problem to be solved by the invention]

[0005] The present disclosure provides a filling method and processing system capable of filling a ruthenium film with good filling properties in a recess. [Means for solving the problem]

[0006] According to one aspect of the present disclosure Embedding MethodThe method includes the steps of: preparing a substrate having an insulating film having a recess formed therein and a metal film provided so as to be exposed at the bottom of the recess; filling a first ruthenium film from the bottom of the recess to a middle of the recess by CVD using a ruthenium-containing gas while heating the substrate to a first temperature; and filling a second ruthenium film in the recess on the first ruthenium film by CVD using a ruthenium-containing gas while heating the substrate to a second temperature lower than the first temperature. a pressure when the first ruthenium film is embedded is set to a first pressure, and a pressure when the second ruthenium film is embedded is set to a second pressure higher than the first pressure. . Effect of the Invention

[0007] According to the present disclosure, there is provided a filling method and processing system capable of filling a ruthenium film with good filling properties in a recess. [Brief description of the drawings]

[0008] [Figure 1] FIG. 2 is a horizontal cross-sectional view showing a schematic example of a processing system used in an embedding method according to an embodiment. [Diagram 2] 1 is a cross-sectional view showing a schematic diagram of a first embedding apparatus for carrying out an embedding step which is a main step of an embedding method according to one embodiment. [Diagram 3] 1 is a cross-sectional view showing a schematic structure of a wafer used in a filling method according to an embodiment of the present invention; [Figure 4] 1A to 1C are cross-sectional views showing a process for embedding a Ru film by a embedding method according to an embodiment. [Diagram 5] FIG. 2 is a cross-sectional view for explaining bottom-up film formation. [Figure 6] FIG. 11 is a cross-sectional view showing a state in which embedding properties have deteriorated due to bottom-up film formation. [Figure 7] FIG. 2 is a cross-sectional view for explaining conformal film formation. [Figure 8] FIG. 11 is a cross-sectional view showing a state in which embedding properties have deteriorated due to conformal film formation. [Figure 9] FIG. 2 is a cross-sectional view showing the structure of a wafer used in an experimental example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment will be described with reference to the accompanying drawings.

[0010] <Film formation system> First, an example of a processing system used in the embedding method according to an embodiment will be described below. Fig. 1 is a horizontal cross-sectional view showing a schematic example of such a processing system.

[0011] The processing system 1 is for embedding a ruthenium (Ru) film in recesses such as trenches and holes formed in a semiconductor wafer (hereinafter simply referred to as a wafer) W, which is a substrate, and is configured as a cluster tool.

[0012] The processing system 1 has, as its main components, four processing devices for processing wafers W, three load lock chambers 14, a vacuum transfer chamber 10, an atmospheric transfer chamber 15, and an overall control unit 21.

[0013] Specifically, the four processing devices are a pre-cleaning device 11, an annealing device 12, a first filling device 13a, and a second filling device 13b. The pre-cleaning device 11 performs pre-processing such as removing a natural oxide film on the surface of the wafer W. The annealing device 12 performs annealing after filling the Ru film. The first and second filling devices 13a and 13b form a Ru film on the wafer W by CVD to fill the recesses. The first filling device 13a fills the recesses halfway at a first temperature, and the second filling device 13b fills the remaining part of the recesses at a temperature lower than the first temperature. The filling devices 13a and 13b will be described in detail later.

[0014] The load lock chamber 14 is provided between the vacuum transfer chamber 10 and the atmospheric transfer chamber 15, and adjusts the pressure between atmospheric pressure and vacuum when transferring the wafer W between the vacuum transfer chamber 10 and the atmospheric transfer chamber 15.

[0015] The vacuum transfer chamber 10 is evacuated by a vacuum pump, maintained at a vacuum level suited to the pressure inside the processing vessels of the four processing devices, and has an internal transfer mechanism 18. The vacuum transfer chamber 10 is connected to the four processing devices via gate valves G, and to three load lock chambers 14 via gate valves G1.

[0016] The transfer mechanism 18 transfers the wafer W to the pre-cleaning device 11, the annealing device 12, the first embedding device 13a, the second embedding device 13b, and the load lock chamber 14. The transfer mechanism 18 has two transfer arms 19a and 19b that are independently movable. The atmospheric transfer chamber 15 is maintained in an atmospheric atmosphere, and one wall portion is connected to three load lock chambers 14 via gate valves G2. The wall portion of the atmospheric transfer chamber 15 opposite to the mounting wall portion of the load lock chamber 14 has three carrier mounting ports 16 for mounting carriers (FOUP, etc.) C that accommodate wafers W. In addition, an alignment chamber 17 for aligning the wafers W is provided on a side wall of the atmospheric transfer chamber 15. A downflow of clean air is formed inside the atmospheric transfer chamber 15.

[0017] A transfer mechanism 20 is provided in the atmospheric transfer chamber 15. The transfer mechanism 20 transfers the wafer W to the carrier C, the load lock chamber 14, and the alignment chamber 17.

[0018] The overall control unit 21 controls the entire processing system 1, and sends control commands to the pre-cleaning device 11, the annealing device 12, the first embedding device 13a, and the second embedding device 13b. It also controls the exhaust mechanism and gas supply mechanism of the vacuum transfer chamber 10 and the load lock chamber 14, as well as the transfer mechanisms 18 and 20, and the drive systems of the gate valves G, G1, and G2. The overall control unit 21 includes a main control unit having a CPU (computer) that actually performs these controls, an input device (keyboard, mouse, etc.), an output device (printer, etc.), a display device (display, etc.), and a storage device (storage medium). The main control unit causes the processing system 1 to execute a desired processing operation based on a processing recipe stored in the storage medium of the storage device.

[0019] Next, an outline of the operation of the processing system 1 configured as above will be described. The following operation is performed based on a processing recipe stored in a storage medium.

[0020] First, the transfer mechanism 20 removes the wafer W from the carrier C connected to the atmospheric transfer chamber 15, and the gate valve G2 of one of the load lock chambers 14 is opened to load the wafer W into that load lock chamber 14. After closing the gate valve G2, the load lock chamber 14 is evacuated, and when the load lock chamber 14 reaches a predetermined vacuum level, the gate valve G1 is opened and the transfer mechanism 18 removes the wafer W from the load lock chamber 14.

[0021] The removed wafer W is then transferred in sequence to the pre-processing device 11, the first embedding device 13a, the second embedding device 13b, and the annealing device 12, where a predetermined process is performed. When the wafer W is transferred into and out of each device, a gate valve G is opened and closed. Note that the pre-processing device 11 performs pre-processing and the annealing device 12 performs annealing as necessary.

[0022] For the wafer W for which a series of processes has been completed, the gate valve G1 of one of the load lock chambers 14 is opened, and the wafer W is loaded into that load lock chamber 14 by the transfer mechanism 18. Then, the interior of that load lock chamber 14 is returned to the atmosphere, the gate valve G2 is opened, and the wafer W in the load lock chamber 14 is returned to the carrier C by the transfer mechanism 20. The above-mentioned processes are performed simultaneously in parallel for multiple wafers W until the processing of a predetermined number of wafers W is completed.

[0023] In the processing system 1, a series of processes can be performed without exposing the wafer W to the atmosphere.

[0024] <Embedding device> Next, an example of the first embedding device 13a and the second embedding device 13b for performing the embedding step, which is a main step of the embedding method according to the embodiment, will be described. Note that the first embedding device 13a and the second embedding device 13b have the same configuration, so only the first embedding device 13a will be described below.

[0025] FIG. 2 is a cross-sectional view that illustrates a schematic example of the first embedding device 13a. As described above, the first filling apparatus 13a fills the recesses by forming a Ru film on the wafer W by CVD.

[0026] The first embedding device 13a has a bottomed processing vessel 101 having an opening at the top. The top opening of the processing vessel 101 is closed by a support member 102 that supports a gas discharge mechanism 103. In addition, the support member 102 closes the upper opening of the processing vessel 101, so that the inside of the processing vessel 101 becomes a sealed processing space S.

[0027] The gas discharge mechanism 103 discharges gas, which is supplied from a gas supply unit 104 via a gas supply path 102a penetrating the support member 102, toward the processing space.

[0028] The gas supply unit 104 supplies solid ruthenium carbonyl (Ru(CO)12 The film forming source container 161 contains Ru3(CO) 12 is vaporized and supplied to the gas discharge mechanism 103. A heater 162 is provided around the film forming raw material container 161, and CO gas as a carrier gas is blown into the film forming raw material container 161 from a CO gas supply source 164 via a carrier gas supply pipe 163. A film forming raw material gas supply pipe 165 is inserted into the film forming raw material container 161, and the film forming raw material gas supply pipe 165 is connected to the gas supply path 102a. As a result, CO gas as a carrier gas is blown into the film forming raw material container 161, and Ru3(CO) sublimated in the film forming raw material container 161 is vaporized and supplied to the gas discharge mechanism 103. 12 The gas is transported through the film forming source gas supply pipe 165 by the CO gas. 12 The gas flows from the source gas supply pipe 165 through the gas supply path 102a to the gas discharge mechanism 103, and is discharged into the processing space S.

[0029] The carrier gas supply pipe 163 is provided with a flow rate controller 166 such as a mass flow controller and valves 167a and 167b before and after the flow rate controller 166. The deposition source gas supply pipe 165 is provided with Ru3(CO) 12 A flow meter 168 for measuring the amount of gas and valves 169a, 169b before and after the flow meter 168 are provided.

[0030] The gas supply unit 104 also has a counter CO gas pipe 171 that is branched off from the carrier gas supply pipe 163 on the upstream side of the valve 167a. The counter CO gas pipe 171 is connected to the film forming source gas supply pipe 165. Therefore, the CO gas from the CO gas supply source 164 is converted into Ru3(CO) 12 It can be supplied as a counter gas separately from the gas to the processing space S. The counter CO gas pipe 171 is provided with a mass flow controller 172 for flow rate control and valves 173a, 173b before and after the mass flow controller 172.

[0031] Further, the gas supply unit 104 has an N2 gas supply source 174 for supplying N2 gas used as a dilution gas, a temperature rising gas, and a purge gas for purging the processing space, and an H2 gas supply source 175 for supplying H2 gas used as a heat transfer gas. An N2 gas supply pipe 176 is connected to the N2 gas supply source 174, and an H2 gas supply pipe 177 is connected to the H2 gas supply source 175, and the other ends of these are connected to the film forming source gas supply pipe 165. A flow rate controller 178 and valves 179a and 179b before and after the flow rate controller are provided in the N2 gas supply pipe 176, and a flow rate controller 180 and valves 181a and 181b before and after the flow rate controller are provided in the H2 gas supply pipe 177.

[0032] In addition, other inert gases such as Ar gas may be used instead of N2 gas as the dilution gas, etc. Also, He gas may be used instead of H2 gas as the heat transfer gas.

[0033] A side wall of the processing vessel 101 is provided with a load / unload port 101a for loading / unloading the wafer W, and a gate valve G for opening / closing the load / unload port 101a.

[0034] An exhaust unit 119 including a vacuum pump and the like is connected via an exhaust pipe 101b to a lower sidewall of the processing vessel 101. The exhaust unit 119 exhausts the inside of the processing vessel 101, and a predetermined vacuum atmosphere (e.g., 1.33 Pa) is set and maintained.

[0035] The stage 105 is a member on which the wafer W is placed. A heater 106 for heating the wafer W is provided inside the stage 105. The stage 105 extends downward from the center of the lower surface of the stage 105, and one end penetrating the bottom of the processing vessel 101 is supported by a support 105a supported by a lifting mechanism via a lift plate 109. The stage 105 is fixed on a temperature control jacket 108, which is a temperature control member, via a heat insulating ring 107. The temperature control jacket 108 has a plate portion for fixing the stage 105, a shaft portion extending downward from the plate portion and configured to cover the support portion 105a, and a hole portion penetrating the shaft portion from the plate portion.

[0036] The shaft of the temperature control jacket 108 penetrates the bottom of the processing vessel 101. The lower end of the shaft of the temperature control jacket 108 is supported by a lift plate 109 disposed below the processing vessel 101. A lift mechanism 110 is provided below the lift plate 109, and the lift mechanism 110 can raise and lower the stage 105 via the lift plate 109 and the temperature control jacket 108. The lift mechanism 110 raises and lowers the stage 105 shown in FIG. 2 between a processing position where the wafer W is processed and a transfer position (not shown) where the wafer W is transferred via the loading / unloading port 101a. A bellows 111 is provided between the bottom of the processing vessel 101 and the lift plate 109, so that the airtightness inside the processing vessel 101 is maintained even if the lift plate 109 moves up and down.

[0037] Lifting pins 112 are inserted through the plate portions of the stage 105 and the temperature control jacket 108. The lifting pins 112 have a shaft portion and a head portion having a larger diameter than the shaft portion. The shaft portion is inserted through an insertion hole formed in the plate portions of the stage 105 and the temperature control jacket 108. A groove portion is formed at a position corresponding to the through hole on the mounting surface side of the stage 105 to accommodate the head portion having a larger diameter than the through hole.

[0038] The lifting pins 112 are arranged to be capable of being raised and lowered, and when the stage 105 is in the processing position, as shown in FIG. 2, the heads are accommodated in the grooves and engaged with the bottom surface of the grooves, the lower ends of the shafts protrude below the plate portion of the temperature control jacket 108, and the wafer W is placed on the support surface of the stage 105.

[0039] When the stage 105 is lowered to the transfer position for the wafer W, the lower ends of the lift pins 112 come into contact with the contact members 113, and when the stage 105 is lowered further, the heads of the lift pins 112 protrude from the mounting surface of the stage 105. As a result, the wafer W is lifted from the mounting surface of the stage 105 with the heads of the lift pins 112 supporting the lower surface of the wafer W.

[0040] An annular member 114 is disposed above the stage 105 at a position corresponding to the outer periphery of the wafer W. As shown in Fig. 2, when the stage 105 is located at the processing position, the annular member 114 comes into contact with the outer periphery of the upper surface of the wafer W, and presses the wafer W against the mounting surface of the stage 105 by the weight of the annular member 114. On the other hand, when the stage 105 is moved to the transfer position of the wafer W, the annular member 114 is locked by a locking portion (not shown) above the transfer port 101a. This prevents the annular member 114 from interfering with the transfer of the wafer W.

[0041] Below the processing vessel 101, a chiller unit 115, a heat transfer gas supply unit 116, and a purge gas supply unit 117 are provided.

[0042] The chiller unit 115 circulates a refrigerant, for example, cooling water, through a flow path 108a provided in a plate portion of the temperature control jacket 108 via pipes 115a and 115b.

[0043] The heat transfer gas supply unit 116 supplies a heat transfer gas such as He gas between the rear surface of the wafer W and the mounting surface of the stage 105 via a pipe 116a.

[0044] The purge gas supply unit 117 supplies CO gas as a purge gas through the pipe 117a, a gap formed between the support unit 105a and the hole of the temperature control jacket 108, a flow path (not shown) formed between the stage 105 and the heat insulating ring 107 and extending radially outward, and a vertical flow path (not shown) formed on the outer periphery of the stage 105. The CO gas as a purge gas is supplied between the lower surface of the annular member 114 and the upper surface of the stage 105. This prevents the process gas from flowing into the space between the lower surface of the annular member 114 and the upper surface of the stage 105, and prevents a film from being formed on the lower surface of the annular member 114 or the upper surface of the outer periphery of the stage 105.

[0045] The control device 120 controls each component of the first embedding apparatus 13a, such as the gas supply unit 104, the heater 106, the lifting mechanism 110, the chiller unit 115, the heat transfer gas supply unit 116, the purge gas supply unit 117, the gate valve G, and the exhaust unit 119, based on a command from the overall control unit 21. The first embedding apparatus 13a can also be controlled by the overall control unit 21, in which case the control device 120 is not necessary.

[0046] The operation of the first embedding device 13a thus configured will be described. The following operation is executed under the control of the control device 120.

[0047] First, the processing space S in the processing vessel 101 is made into a vacuum atmosphere, and with the stage 105 in the delivery position, the gate valve G is opened and the wafer W is loaded by the transfer mechanism 18. Then, the wafer W is placed on the lift pins 112 protruding from the stage 105. After the transfer mechanism 18 retreats from inside the processing vessel 101, the gate valve G is closed.

[0048] Next, the stage 105 is moved to the processing position. At this time, the stage 105 is raised, so that the wafer W placed on the lift pins 112 is placed on the mounting surface of the stage 105. In addition, the annular member 114 comes into contact with the outer periphery of the upper surface of the wafer W, and the wafer W is pressed against the mounting surface of the stage 105 by the weight of the annular member 114.

[0049] In this state, the pressure in the processing space S is adjusted, and the wafer W is heated to a set temperature by the heater 106 via the stage 105. Then, ruthenium-containing gas Ru3(CO) 12 The gas is supplied from the gas discharge mechanism 103 into the processing space S together with CO gas, which is a carrier gas. As a result, a Ru film is embedded in the recesses formed in the wafer W. The processed gas passes through a flow path on the upper surface side of the annular member 114 and is exhausted by the exhaust unit 119 via the exhaust pipe 101b.

[0050] As the gases, a counter CO gas other than the carrier gas, N2 gas as a dilution gas, and H2 gas as a heat transfer gas may be supplied.

[0051] In this embedding process, a heat transfer gas is supplied between the back surface of the wafer W and the mounting surface of the stage 105. In addition, CO gas is supplied as a purge gas from a purge gas supply unit 117 between the lower surface of the annular member 114 and the upper surface of the stage 105. This prevents the process gas from flowing into the space between the lower surface of the annular member 114 and the stage 105, thereby preventing a film from being formed on the lower surface of the annular member 114 or the upper surface of the outer periphery of the stage 105. The purge gas passes through a flow path on the lower surface side of the annular member 114 and is exhausted by an exhaust unit 119.

[0052] When the embedding process is completed, the stage 105 is moved (lowered) to a delivery position corresponding to the load / unload port 101a. At this time, the lower ends of the lift pins 112 come into contact with the contact members 113, causing the lift pins 112 to protrude from the mounting surface of the stage 105 and lift the wafer W from the mounting surface of the stage 105. Then, the gate valve G is opened, and the wafer W mounted on the lift pins 112 is transported out by the transport mechanism 18.

[0053] <Embedding method according to an embodiment> Next, an embedding method according to an embodiment will be described. In this embodiment, a Ru film is embedded in recesses formed in a wafer W. The Ru film is embedded by the processing system described with reference to FIG.

[0054] 3 is a cross-sectional view showing a schematic structure of a wafer W used in the filling method of the present embodiment. The wafer W has a silicon substrate 200, a lower structure 201 having a metal film 202 provided thereon, and an insulating film 203 having a recess 204 provided on the lower structure 201, with the metal film 202 exposed at the bottom of the recess 204.

[0055] The lower structure 201 is, for example, configured by forming a metal film 202 in an insulating film. The metal film 202 is preferably one that does not easily react with the embedded Ru film, and examples thereof include a tungsten (W) film, a cobalt (Co) film, and a titanium (Ti) film. Examples of the insulating film 203 include a Si-containing film such as a SiO2 film, a SiN film, and a low dielectric constant (Low-k) film. The insulating film 203 may be a structure in which different types of films are laminated, for example, a laminate structure of a SiN film and a SiO2 film. Examples of the recess 204 include a trench and a hole (via, contact hole, etc.).

[0056] A Ru film is formed on such a wafer W by CVD, and the Ru film is embedded in the recesses 204. FIG. 4 is a cross-sectional view showing the process of embedding the Ru film. When embedding, a first embedding step is first performed by a first embedding device 13a to embed a first Ru film 205 halfway into the recesses 204 as shown in FIG. 4(a). Next, the wafer W is transferred to a second embedding device 13b to perform a second embedding step to embed a second Ru film 206 into the remaining portion of the recesses 204 as shown in FIG. 4(b). At this time, the first embedding step is performed at a first temperature, and the second stage embedding step is performed at a second temperature lower than the first temperature.

[0057] In forming a Ru film by CVD, when the film formation temperature is higher than a certain temperature, the film has selectivity such that the film is easily formed on metals and difficult to form on insulators. Therefore, when filling the wafer W having the structure of FIG. 3 with a Ru film at a high temperature having such selectivity, the Ru film is easily formed on the metal film 202 exposed at the bottom of the recess 204 and difficult to form on the insulating film 203. For this reason, the Ru film 210 is generally filled into the recess 204 with good filling properties by bottom-up film formation in which film formation proceeds from the bottom, as shown in (a) to (c) of FIG. 5. The above-mentioned Patent Document 2 utilizes such bottom-up film formation.

[0058] However, in the case of bottom-up film formation, the smoothness (flatness) of the sidewalls when the Ru film is embedded is not sufficient, and as shown in Fig. 6(a), an overhang 210a of the Ru film 210 may occur at the frontage of the recess 204. Recently, recesses such as trenches and holes in semiconductor devices have become finer and finer, and even if a slight overhang occurs, as film formation progresses further, there is a risk that the embeddability will decrease, such as a void 211 remaining inside, as shown in Fig. 6(b).

[0059] On the other hand, when the film formation temperature is low, such selectivity decreases, and generally, as shown in (a) to (c) of FIG. 7, in the recess 204, the Ru film 210 is formed conformally with a uniform thickness on the metal film 202 at the bottom and the insulating film 203 at the sidewall. In the case of conformal film formation, the smoothness (flatness) of the sidewall is good, and overhangs and the like are unlikely to occur. However, as the film formation progresses, the opening of the recess 204 narrows as shown in FIG. 8(a), and finally, as shown in FIG. 8(b), voids 211 are likely to remain, and the filling ability is essentially poor.

[0060] Therefore, in this embodiment, the first filling step is first performed halfway into the recess 204 by the first filling device 13a set to a high temperature, and then the second filling step is performed by the second filling device 13b set to a low temperature. At this time, the timing of switching from the first filling step to the second filling step can be appropriately set within a range in which the recess 204 does not overhang.

[0061] As a result, in the initial first filling step, the first Ru film 205 can be filled with good filling properties by bottom-up film formation, and in the second filling step, the second Ru film 206 can be filled with good smoothness (flatness) by conformal film formation. Furthermore, in the second filling step, since the first Ru film 205 has already been filled in the recess 204, the filling properties are not impaired even by conformal film formation. Therefore, the Ru film can be filled in the recess 204 with good filling properties.

[0062] Furthermore, a first embedding apparatus 13a preset to a high temperature and a second embedding apparatus 13b preset to a low temperature are used, and the first embedding step is carried out by the first embedding apparatus 13a and the second embedding step is carried out by the second embedding apparatus 13b, thereby achieving high throughput.

[0063] If the pressure during the first filling step (pressure in the processing space S) is a first pressure and the pressure during the second filling step is a second pressure, it is preferable to set the first pressure lower than the second pressure. Setting the pressure during the first filling step to a relatively low pressure facilitates bottom-up film formation, and setting the pressure during the second filling step to a relatively high pressure facilitates conformal film formation.

[0064] In addition, Ru3(CO) 12 The flow rate of the gas (i.e., the flow rate of the CO gas, which is the carrier gas) is preferably lower than the flow rate in the first embedding step. This is because the Ru source Ru3(CO) 12 This is to make it easier for the Ru(CO)4 to become in a state where it is easily adsorbed to the bottom of a recess such as a via, which is thought to make it easier to form a bottom-up structure.

[0065] The above describes a two-stage film formation in which the first filling step is performed and then the second filling step is performed, but the first filling step and the second filling step may be performed and then the second first filling step may be performed. When performing this, the second filling step may be performed in the second filling device 13b, and then the wafer W may be returned to the first filling device 13a again to perform the second first filling step, or another first filling device may be provided and the second first filling step may be performed in that device. Also, the first filling step and the second filling step may be repeated.

[0066] Next, the first and second embedding steps will be described in detail.

[0067] The first temperature in the first filling step is preferably 150 to 190°C. If the first temperature is lower than 150°C, the selectivity of the Ru film deposition on the metal film (W film) 202 and the insulating film (SiO2 film) 203 deteriorates, making it difficult to perform bottom-up deposition, and if the first temperature is higher than 190°C, the film quality tends to deteriorate. In addition, the first pressure in the first filling step is preferably 0.6 to 2.2 Pa. This is because the Ru raw material Ru3(CO) 12 This is to make it easier for the Ru(CO)4 to become in a state where it is easily adsorbed to the bottom of a recess such as a via, which is thought to facilitate bottom-up formation.

[0068] The second temperature in the second embedding step is preferably 100 to 140° C. If the second temperature is lower than 100° C., the film formation tends to proceed more slowly, and if it is higher than 140° C., the smoothness (flatness) may decrease. The second pressure in the second embedding step is preferably 13.3 to 20 Pa. Within this range, the desired conformal film formation can proceed.

[0069] Also, Ru3(CO) 12 The flow rate of the CO gas as a carrier gas for transporting the gas is preferably 100 to 500 sccm in the first embedding step, and 10 to 90 sccm in the second embedding step. 12 This is to facilitate the formation of Ru(CO)4, which is easily adsorbed to the bottom of the recess 204 such as a via, and is thought to facilitate bottom-up.

[0070] The reason why CO gas is used as a carrier gas is because Ru3(CO) 12 This is to prevent the decomposition reaction shown in the following formula (1) that occurs on the surface of the wafer W when a Ru film is formed using a gas from occurring as much as possible before the gas reaches the wafer W. Ru3(CO) 12 →3Ru+12CO (1)

[0071] Also, Ru3(CO) 12To more effectively suppress the gas decomposition reaction, Ru3(CO) 12 It is effective to reduce the / CO partial pressure ratio, and for that purpose, CO gas is supplied as a counter gas to the carrier gas into the processing space S. The flow rate of the CO gas supplied as the counter gas is preferably 50 to 100 sccm in both the first filling step and the second filling step.

[0072] Furthermore, the effect can be enhanced by using CO gas as a purge gas that prevents the process gas from flowing into the space between the lower surface of the annular member 114 and the upper surface of the stage 105. The flow rate of the CO gas supplied as the purge gas is preferably 50 to 100 sccm in both the first embedding step and the second embedding step.

[0073] In addition, Ru3(CO) 12 When supplying the gas, an appropriate amount of N2 gas may be supplied as a dilution gas as necessary. 12 Prior to the supply of gas, H2 gas, which is a heat transfer gas, may be supplied to the processing space S. At this time, N2 gas may be supplied together with H2 gas. Note that, as the dilution gas, other inert gases such as Ar gas may be used instead of N2 gas. Also, as the heat transfer gas, He gas may be used instead of H2 gas.

[0074] In the first and second filling steps, Ru3(CO) 12 It is preferable to alternately repeat the step of supplying a gas to form a film and the step of purging the processing space S with N2 gas. 12 The CO gas generated by the decomposition of the gas can be appropriately discharged, and a Ru film with good film quality can be embedded. As the purge gas, other inert gases such as Ar gas may be used.

[0075] In this embodiment, prior to the above-described Ru film embedding step, a pre-cleaning process may be performed as necessary using a pre-cleaning device 11 to remove a natural oxide film on the surface of the metal film 202. By removing the natural oxide film, the film quality of the Ru film to be embedded can be improved. The pre-cleaning process may be performed, for example, by H2 plasma processing, Ar plasma processing, or both.

[0076] After the Ru film embedding step, an annealing process may be performed by an annealing device 12 as necessary in order to improve crystallinity, adhesion, and the like.

[0077] <Experimental Example> Next, an experimental example will be described. 9, a wafer was used having a silicon substrate 300, a lower structure 301 having a W film 302 provided thereon, a SiN film 303 provided on the lower structure 301, and a SiO2 film 304 provided on the SiN film 303. The wafer used had a structure in which a plurality of vias 305 with a diameter of 15 nm and a depth of 60 nm were formed in the SiN film 303 and the SiO2 film 304, and the W film was exposed at the bottom of the vias 305.

[0078] This wafer was subjected to a filling process using the processing system shown in Fig. 1. First, the pre-cleaning device 11 performed H2 plasma processing and Ar plasma processing to remove the native oxide film on the surface of the tungsten film.

[0079] Thereafter, the vias were filled with a Ru film in Case 1 and Case 2 described below.

[0080] In case 1, the first filling device 13a was used to fill the Ru film only under the following condition A (high temperature and low pressure condition). In the filling, the number of filling and purging cycles was set so that the film thickness was 3.5 nm in a film formation experiment using a blank wafer in advance. Condition A Temperature: 155℃ Pressure: 2.2 Pa (16.6 mTorr) Carrier CO gas flow rate: 100sccm Counter CO gas flow rate: 50sccm Purge CO gas flow rate: 100sccm

[0081] In case 2, the first filling step was performed using the first filling device 13a under the above-mentioned condition A (high temperature and low pressure), and then the wafer was transferred to the second filling device 13b, where the second filling step was performed under the following condition B (low temperature and high pressure). In this filling step, the number of filling and purging cycles was set so that the film thickness in the first filling step was 1.0 nm and the film thickness in the second filling step was 24 nm, based on a film formation experiment using a blank wafer in advance. ·Condition B Temperature: 135℃ Pressure: 13.3 Pa (100 mTorr) Carrier CO gas flow rate: 75sccm Counter CO gas flow rate: 50sccm Purge CO gas flow rate: 100sccm

[0082] After filling in Case 1 and Case 2, the filling state of 12 vias in each case was observed with an electron microscope, and the ratio of vias filled without voids was 42% in Case 1 and 50% in Case 2. In Case 1, filling was performed only by bottom-up film formation, while in Case 2, conformal film formation was performed after bottom-up film formation, confirming the superiority of the two-stage filling of the embodiment.

[0083] <Other applications> Although the embodiments have been described above, the embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The above-described embodiments may be omitted, substituted, or modified in various forms without departing from the scope and spirit of the appended claims.

[0084] For example, in the above embodiment, Ru3(CO) 12However, the present invention is not limited to this, and examples thereof include Ru3(CO) 12 Gas containing (but not containing oxygen gas), (2,4-dimethylpentadienyl)(ethylcyclopentadienyl)ruthenium :(Ru(DMPD)(EtCp)), bis(2,4-dimethylpentadienyl)Ruthenium:(Ru(DMPD)2), 4-dimethylpentadienyl)(methylcyclopentadienyl)Ruthenium:(Ru(DMPD)(MeCp)), Bis(Cyclopentadienyl)Ruthenium:(Ru(C5H5)2), Cis-dicarbonyl Bis(5-methylhexane-2,4-dionate)ruthenium(II), bis(ethylcyclopentadienyl)Ruthenium(II):Ru(EtCp)2, etc. may be used.

[0085] Moreover, the processing system in FIG. 1 is merely an example, and is not limited thereto. For example, the number of vacuum transfer chambers and load lock chambers, the number of processing devices connected to the vacuum transfer chamber, and the like are arbitrary. In the above embodiment, the processing system is shown equipped with a pre-cleaning device and an annealing device, but the processing system may not be equipped with a pre-cleaning device and an annealing device. Furthermore, the number of first embedding devices and second embedding devices is arbitrary, and it is sufficient that at least one of each is included. The embedding device in FIG. 2 is also merely an example, and is not limited thereto.

[0086] In the above embodiment, a semiconductor wafer is used as an example of the substrate, but the substrate is not limited to a semiconductor wafer and may be other substrates such as a glass substrate used in an FPD (flat panel display) or a ceramic substrate. [Explanation of symbols]

[0087] 1; Processing system 10. Vacuum transfer chamber 11; Pre-cleaning device 13a; First implantation device 13b; Second implantation device 14; Load lock chamber 15: Atmospheric transport chamber 18, 20: Transport mechanism 21: Overall control unit 101; Processing vessel 104: Gas supply section 105; Stage 106;Heater 120: Control device 200: Silicon substrate 201;Substructure 202; Metal film 203: Insulating film 204; Recess 205; First Ru film 206; Second Ru film 210;Ru film S: Processing space W: Wafer

Claims

1. A step of preparing a substrate having an insulating film having a recess formed therein and a metal film provided so as to be exposed at the bottom of the recess; filling the recess from the bottom to a middle of the recess with a first ruthenium film by CVD using a ruthenium-containing gas while heating the substrate to a first temperature; a step of filling the recess with a second ruthenium film on the first ruthenium film by CVD using a ruthenium-containing gas while heating the substrate to a second temperature lower than the first temperature; having The embedding method includes embedding the first ruthenium film at a first pressure, and embedding the second ruthenium film at a second pressure higher than the first pressure.

2. 2. The method according to claim 1, wherein, when embedding the first ruthenium film, the first ruthenium film is embedded in the recess so as to be bottom-up from the metal film at the bottom, and, when embedding the second ruthenium film, the second ruthenium film is conformally embedded in the recess.

3. 3. The embedding method according to claim 1, further comprising the steps of: using a processing system having a first embedding apparatus that embeds the first ruthenium film at the first temperature; and a second embedding apparatus that embeds the second ruthenium film at the second temperature; transporting the substrate to the first embedding apparatus to embed the first ruthenium film; and subsequently transporting the substrate to the second embedding apparatus to embed the second ruthenium film.

4. 4. The method according to claim 1, wherein the ruthenium-containing gas used when embedding the first ruthenium film and the second ruthenium film is a ruthenium carbonyl gas.

5. The embedding method according to claim 4, wherein the first temperature is between 150 and 190°C, and the second temperature is between 100 and 140°C.

6. 6. The method according to claim 4, wherein a pressure is set to 0.6 to 2.2 Pa when said first ruthenium film is embedded, and a pressure is set to 13.3 to 20 Pa when said second ruthenium film is embedded.

7. The ruthenium carbonyl gas is supplied by sublimating solid ruthenium carbonyl and using CO gas as a carrier gas, the flow rate of the carrier gas when embedding the first ruthenium film is 100 to 500 sccm, and the flow rate of the carrier gas when embedding the second ruthenium film is 10 to 90 sccm. The embedding method according to any one of claims 4 to 6.

8. 8. The method according to claim 1, further comprising the step of embedding the first ruthenium film after the step of embedding the second ruthenium film.

9. 8. The method according to claim 1, wherein after the step of embedding the second ruthenium film, the step of embedding the first ruthenium film and the step of embedding the second ruthenium film are performed once or a plurality of times.

10. 10. The method according to claim 1, further comprising the step of removing a native oxide film formed on a surface of the metal film, the step being performed prior to the step of filling the recess from the bottom to partway into the recess with a first ruthenium film.

11. The method according to claim 1 , wherein the insulating film is a Si-containing film.

12. 12. The method according to claim 1, wherein the metal film is any one of a tungsten film, a cobalt film, and a titanium film.

13. 1. A processing system for filling a ruthenium film in a recess in a substrate having an insulating film and a metal film exposed at a bottom of the recess, comprising: a first filling device for filling the recess by CVD using a ruthenium-containing gas; a second filling device for filling the recess by CVD using a ruthenium-containing gas; a vacuum transfer chamber to which the first embedding device and the second embedding device are connected and in which a transfer mechanism for transferring a substrate is provided; A control unit; having the control unit controls the first embedding device, the second embedding device, and the transport mechanism so as to transport the substrate to the first embedding device, embed a first ruthenium film from the bottom of the recess to a middle of the recess while heating the substrate to a first temperature, and then transport the substrate to the second embedding device, embed a second ruthenium film on the first ruthenium film in the recess while heating the substrate to a second temperature lower than the first temperature; The control unit further controls the first embedding device and the second embedding device so that a pressure during embedding by the first embedding device is a first pressure, and a pressure during embedding by the second embedding device is a second pressure higher than the first pressure.

14. 14. The processing system of claim 13, wherein said first implanter and said second implanter use ruthenium carbonyl gas as said ruthenium-containing gas.

15. 15. The processing system according to claim 14, wherein the control unit controls the first embedding device and the second embedding device so that the first temperature is 150 to 190°C and the second temperature is 100 to 140°C.

16. The processing system described in claim 14 or claim 15, wherein the control unit controls the first embedding device and the second embedding device so that the pressure when embedding is performed by the first embedding device is 0.6 to 2.2 Pa, and the pressure when embedding is performed by the second embedding device is 13.3 to 20 Pa.

17. A pretreatment device connected to the vacuum transfer chamber is further provided.

17. The processing system according to claim 13, wherein the control unit controls the pretreatment device to remove a native oxide film formed on a surface of the metal film prior to embedding the ruthenium film.

Images