Wiring forming method and substrate processing apparatus

Abstract

To provide a technique capable of suppressing an increase in a resistance value of a metal wiring portion due to an oxide film formed by oxidation while etching a part of the metal wiring portion by oxidation.SOLUTION: A wiring formation method includes a carry-in step S1, an etching step S3, and a reduction step S6. In the carry-in step S1, a substrate on which a metal wiring portion is formed is carried into a chamber. In the etching step S3, oxidizing gas is supplied to the substrate to etch a part of the metal wiring portion. In the reduction step S6, reducing gas is supplied to the substrate to reduce an oxide film of the metal wiring portion formed by the etching step S3.SELECTED DRAWING: Figure 4

Description

[Technical field]

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

[0002] As the wiring of semiconductor devices becomes finer, short circuits between wirings due to misalignment between wirings and vias are more likely to occur. In other words, if a via formed on a first wiring is misaligned in the horizontal direction and a part of the via is formed on the insulating film between the first wiring and the second wiring, the distance between the second wiring and the via becomes shorter, and the first wiring and the second wiring may be short-circuited through the via.

[0003] As a method for solving this problem, a self-aligned via has been proposed (for example, Patent Document 1). In Patent Document 1, a metal film (for example, copper wiring) that will become wiring is formed inside each trench formed in an insulating film, and the upper surface of the metal film is etched to set the upper surface of each metal film back from the upper surface of the insulating film. This makes it possible to increase the distance between the upper surface of the metal film and the upper surface of the insulating film.

[0004] According to this, even if a part of the via is formed on the upper surface of the insulating film between the first metal film and the second metal film due to the via being horizontally shifted with respect to the first metal film, the upper surface of the second metal film is recessed from the upper surface of the insulating film, so that a distance between the via and the second metal film can be secured, thereby making it possible to suppress a short circuit between the first metal film and the second metal film through the via. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2019-61978 A Summary of the Invention [Problem to be solved by the invention]

[0006] The wiring formed on the substrate (hereinafter referred to as the metal wiring portion) is formed of a single metal film or a plurality of metal films. Such metal wiring portions are appropriately etched in the manufacturing process to adjust their shape. For example, in Patent Document 1, the upper surface of the metal film is etched.

[0007] In such etching, the metal wiring portion may be oxidized during etching. In this case, an oxide film may be partially formed on the metal wiring portion. Such an oxide film is not preferable because it increases the resistance value of the metal wiring portion.

[0008] Therefore, an object of the present application is to provide a technique capable of etching a part of a metal wiring portion by oxidation while suppressing an increase in the resistance value of the metal wiring portion due to an oxide film formed by oxidation. [Means for solving the problem]

[0009] A first aspect of the wiring forming method is a method for forming wiring, comprising: a carrying-in step of carrying a substrate on which a metal wiring portion is formed into a chamber; an etching step of supplying an oxidizing gas to the substrate to etch a part of the metal wiring portion; and a reduction step of supplying a reducing gas to the substrate to reduce an oxide film of the metal wiring portion formed by the etching step. The metal wiring portion includes a wiring body located in a trench of an insulating film of the substrate, and a barrier film provided between the wiring body and the insulating film, and in the etching step, a part of the barrier film is etched as the part of the metal wiring portion, and in the reduction step, the oxide film formed on the wiring body by the etching step is reduced. .

[0011] The first step of the wiring formation method 2 The embodiment is 1 In the wiring forming method according to the aspect of the present invention, in the etching step, a protruding portion of the barrier film protruding from the surface of the wiring body is etched as the part of the metal wiring portion, and in the reduction step, the oxide film formed on the surface of the wiring body by the etching step is reduced.

[0012] The first step of the wiring formation method 3 The embodiment is 1 Or 2 In the wiring forming method according to the aspect of the present invention, the barrier film contains ruthenium.

[0013] The first wiring formation method 4 The embodiment is 1 From 3 In the method for forming a wiring according to any one of the above aspects, the wiring body contains at least one of copper, molybdenum, cobalt, tungsten, platinum, and indium.

[0015] The first wiring formation method 5 The aspects are as follows: 4 This is a wiring forming method according to any one of the above aspects, wherein the etching process includes a detection process of detecting a product gas generated by a reaction between the oxidizing gas and the metal wiring portion using a gas sensor, and a judgment process of judging whether or not to stop the etching process based on a detection value of the gas sensor.

[0016] The first wiring formation method 6 The aspects are as follows: 5 The wiring formation method according to any one of the above aspects further includes an oxidizing gas exhaust step that is carried out between the etching step and the reduction step and that supplies an inert gas into the chamber and exhausts the oxidizing gas from the chamber.

[0017] The first wiring formation method 7 The aspects are as follows: 6 In the wiring forming method according to any one of the above aspects, in the etching step, a first step of supplying the oxidizing gas and a second step of supplying an inert gas are alternately repeated.

[0018] The first wiring formation method 8 The aspects are as follows: 7 In the etching step, the substrate is heated to a temperature of 50 degrees or more and 200 degrees or less.

[0019] The first wiring formation method 9 The aspects are as follows: 8In the reduction step, the substrate is heated to a temperature of 100° C. or more and 300° C. or less.

[0020] The first step of the wiring formation method 10 The aspects are as follows: 9 The wiring forming method according to any one of the above aspects further comprises a cooling step of cooling the substrate after the reducing step, and a carrying-out step of carrying the substrate out of the chamber after the cooling step.

[0021] An embodiment of the substrate processing apparatus is a substrate processing apparatus including a chamber, a substrate holding section provided in the chamber for holding a substrate having a metal wiring portion formed thereon, an oxidizing gas supply section for supplying an oxidizing gas to the substrate in the chamber to etch a part of the metal wiring portion, and a reducing gas supply section for supplying a reducing gas to the substrate to reduce an oxide film formed on the metal wiring portion by the oxidizing gas. The metal wiring portion includes a wiring body located in a trench of an insulating film of the substrate, and a barrier film provided between the wiring body and the insulating film, the oxidizing gas supply unit etches a protruding portion of the barrier film protruding from a surface of the wiring body as the part of the metal wiring portion, and the reducing gas supply unit reduces the oxide film formed on the surface of the wiring body by the oxidizing gas supply unit. . Effect of the Invention

[0022] First to fourth wiring forming methods 10 According to the above aspect and the aspect of the substrate processing apparatus, the oxide film of the metal wiring portion generated in the etching process is reduced, so that the oxide film can function as the metal wiring portion again, and therefore the resistance value of the metal wiring portion can be reduced.

[0023] The first step of the wiring formation method 2 According to this aspect, in the etching step, the protruding portion of the barrier film is removed by etching. Therefore, when the via portion is formed on the insulating film, the via portion and the metal wiring portion can be formed with lower resistance.

[0024] The first step of the wiring formation method 3 According to this aspect, ruthenium tetroxide gas is generated by oxidation, which contributes to etching of the barrier film.

[0026] The first step of the wiring formation method 5According to this aspect, the amount of etching for the metal wiring portion can be controlled with higher accuracy.

[0027] The first wiring formation method 6 According to this aspect, the concentration of the oxidizing gas is reduced before the reducing gas is supplied, thereby making it possible to suppress the reaction between the reducing gas and the oxidizing gas, and to suppress or avoid a decrease in the amount of the reducing gas acting on the substrate.

[0028] The first wiring formation method 7 According to this embodiment, the supply of an inert gas in the second step causes non-uniformity in the concentration of the oxidizing gas. Therefore, the oxidizing gas that has reacted with the substrate quickly leaves the substrate due to concentration diffusion. In the subsequent first step, fresh oxidizing gas is again supplied to the substrate, so that the old oxidizing gas is easily replaced with new oxidizing gas, and the new oxidizing gas easily acts on the substrate. This allows etching to be performed more quickly.

[0029] The first wiring formation method 8 According to this aspect, the metal wiring portion can be etched more appropriately.

[0030] The first wiring formation method 9 According to this aspect, oxides can be reduced more appropriately.

[0031] The first wiring formation method 10 According to this aspect, natural oxidation of the substrate outside the chamber can be suppressed. [Brief description of the drawings]

[0032] [Figure 1] FIG. 1 is a diagram illustrating an example of a configuration of a substrate processing apparatus according to a first embodiment. [Diagram 2] FIG. 2 is a cross-sectional view illustrating an example of a configuration of a substrate. [Diagram 3] 2 is a block diagram showing an example of an internal configuration of a control unit; [Figure 4] 10 is a flowchart showing an example of an operation of the substrate processing apparatus. [Diagram 5] 1 is a cross-sectional view illustrating an example of a configuration of a substrate after an etching process. [Figure 6] FIG. 2 is a cross-sectional view illustrating an example of a configuration of a substrate after a reduction step. [Figure 7] 1 is a cross-sectional view illustrating an example of a configuration of a substrate on which a connection layer is formed. [Figure 8] FIG. 1 is a cross-sectional view illustrating an example of a configuration of a substrate according to a comparative example. [Figure 9] FIG. 11 is a diagram illustrating an example of a configuration of a substrate processing apparatus according to a second embodiment. [Figure 10] 4 is a graph showing a schematic example of a change over time in generated gas. [Figure 11] 10 is a flowchart showing an example of a specific operation of an etching process. [Figure 12] 1 is a timing chart showing an example of an etching process. [Figure 13] FIG. 11 is a cross-sectional view illustrating another example of the configuration of the substrate. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0033] Hereinafter, an embodiment will be described with reference to the accompanying drawings. Note that the components described in the embodiment are merely examples, and are not intended to limit the scope of the present disclosure. In the drawings, the dimensions or numbers of each part may be exaggerated or simplified as necessary for ease of understanding.

[0034] Expressions indicating relative or absolute positional relationships (e.g., "in one direction," "along one direction," "parallel," "orthogonal," "center," "concentric," "coaxial," etc.) not only strictly indicate the positional relationship, but also indicate a state in which the two are relatively displaced in terms of angle or distance within a range in which a tolerance or similar function is obtained, unless otherwise specified. Expressions indicating an equal state (e.g., "same," "equal," "homogeneous," etc.) not only strictly indicate a state in which the two are quantitatively equal, but also indicate a state in which there is a difference in which a tolerance or similar function is obtained, unless otherwise specified. Expressions indicating a shape (e.g., "square shape" or "cylindrical shape," etc.) not only strictly indicate the shape geometrically, but also indicate a shape having, for example, unevenness or chamfering, within a range in which a similar effect is obtained, unless otherwise specified. The expressions "comprise," "include," "have," "includes," "includes," or "has" a component are not exclusive expressions that exclude the presence of other components. The expression "at least one of A, B, and C" includes A only, B only, C only, any two of A, B, and C, and all of A, B, and C.

[0035] <First embodiment> <Outline of substrate processing equipment> 1 is a diagram illustrating an example of a configuration of a substrate processing apparatus 100 according to a first embodiment. The substrate processing apparatus 100 is used when forming wiring on a substrate W.

[0036] FIG. 2 is a cross-sectional view showing an example of the configuration of a substrate W to be loaded into the substrate processing apparatus 100. The substrate W in FIG. 2 is the substrate W before processing by the substrate processing apparatus 100. A first wiring layer 90 is formed on the substrate W. The first wiring layer 90 includes an insulating film 91 and a metal wiring portion 92. The insulating film 91 is also called an interlayer insulating film, and ensures insulation between the metal wiring portion 92 and the surroundings. The insulating film 91 may be, for example, a low dielectric film (a so-called low-k film). As a more specific example of the low dielectric film, a SiOC film in which carbon is added to silicon oxide can be adopted.

[0037] In the example of Fig. 2, trenches 91a are formed in the upper surface of the insulating film 91. The trenches 91a are grooves formed in the upper surface of the insulating film 91. In the example of Fig. 2, a plurality of trenches 91a are arranged at intervals from one another. The pitch of the trenches 91a is, for example, about 20 nm or more and 40 nm or less.

[0038] A metal wiring portion 92 is embedded in each trench 91a. In the example of FIG. 2, the metal wiring portion 92 includes a wiring body 93 and a barrier film 94. The wiring body 93 is formed of a metal material. As the metal material, a material that forms an oxide film by oxidation is adopted. More specifically, as the metal material, at least one of copper (Cu), molybdenum (Mo), cobalt (Co), tungsten (W), platinum (Pt), and indium (Ir) can be adopted.

[0039] The wiring body 93 is located in the trench 91a. The barrier film 94 is provided between the wiring body 93 and the insulating film 91, and suppresses diffusion of the wiring body 93 into the insulating film 91. The barrier film 94 adheres to the surface of the insulating film 91 in the trench 91a, and also adheres to the wiring body 93. The material of the barrier film 94 is different from the material of the wiring body 93, and a metal material that can suppress diffusion of the wiring body 93 into the insulating film 91 is used as the material of the barrier film 94. In addition, a material that is etched by oxidation is used as the metal material of the barrier film 94. More specifically, for example, ruthenium (Ru) can be used as the metal material. The barrier film 94 may also be called a barrier metal.

[0040] The barrier film 94 is formed along the side and bottom surfaces of the trench 91a. Therefore, the barrier film 94 has the same shape as the trench 91a, and has a concave shape. The wiring main body 93 is buried in the concave portion of the barrier film 94.

[0041] The thickness of the barrier film 94 is, for example, about a few nm (e.g., 2 nm) or less. Since the barrier film 94 is very thin, the main component of the metal wiring portion 92 is the wiring body 93. Therefore, it is preferable to adopt a material having a resistivity value smaller than that of the barrier film 94 as the material for the wiring body 93. This makes it possible to reduce the resistance value of the metal wiring portion 92. For example, since the resistivity value of copper is very small, the resistance value of the metal wiring portion 92 can be reduced by adopting copper, which has a low resistivity value, as the material for the wiring body 93. The wiring body 93 may also be called a plug.

[0042] 2, the upper surface of the wiring main body 93 is recessed from the upper surface of the insulating film 91. In other words, the portions of the insulating film 91 between the trenches 91a protrude upward from the wiring main body 93.

[0043] On the other hand, the upper end of the barrier film 94 is substantially flush with the upper surface of the insulating film 91. In the following, the portion of the barrier film 94 that protrudes above the upper surface of the wiring body 93 is referred to as a protruding portion 941. Since the cross section of the barrier film 94 has a substantially U-shape, both side portions thereof protrude above the wiring body 93 as the protruding portions 941.

[0044] Here, the substrate processing apparatus 100 etches the protruding portion 941 of the barrier film 94. With reference to FIG.

[0045] The chamber 1 has a hollow box shape. The internal space of the chamber 1 corresponds to a processing space in which a substrate W is processed.

[0046] 1, the substrate processing apparatus 100 may be provided with a suction unit 7. The suction unit 7 reduces the pressure in the chamber 1 by sucking in gas within the chamber 1 and discharging it to the outside. The suction unit 7 adjusts the pressure in the chamber 1 so that the pressure in the chamber 1 is within a pressure range suitable for processing.

[0047] The substrate holding part 2 is provided in the chamber 1 and holds the substrate W, for example, in a horizontal position. The horizontal position here means that the thickness direction of the substrate W is aligned with the vertical direction. Since an insulating film 91 and a metal wiring part 92 are formed on the upper surface of the substrate W held by the substrate holding part 2, the insulating film 91 and the metal wiring part 92 are exposed in the chamber 1.

[0048] 1, the substrate processing apparatus 100 further includes a heater 22. The heater 22 is provided in the chamber 1, and heats the substrate W held by the substrate holder 2. The heater 22 heats the substrate W so that the temperature of the substrate W falls within a temperature range suitable for processing.

[0049] The gas supply unit 3 supplies various gases into the chamber 1. As shown in FIG. 1, the gas supply unit 3 includes an oxidizing gas supply unit 4 and a reducing gas supply unit 5. The oxidizing gas supply unit 4 supplies an oxidizing gas to the substrate W in the chamber 1. The oxidizing gas is, for example, a gas containing oxygen, and a more specific example is ozone gas. The oxidizing gas acts on the upper surface of the substrate W, thereby etching the protruding portion 941 of the barrier film 94. In other words, the barrier film 94 is formed of a material that is etched by oxidation. For example, when the barrier film 94 is made of ruthenium, a reaction between the oxidizing gas such as ozone and ruthenium generates ruthenium tetroxide (RuO4) gas, and the protruding portion 941 is etched.

[0050] On the other hand, as the oxidizing gas acts on the upper surface of the substrate W, an oxide film is formed on the wiring body 93. In other words, the wiring body 93 is made of a material that forms an oxide film by oxidation. For example, if the wiring body 93 is made of copper, a thin film of copper oxide is formed on the upper surface. This reduces the cross-sectional area of ​​the wiring body 93 and increases the resistance value of the wiring body 93.

[0051] Therefore, the reducing gas supply unit 5 supplies a reducing gas to the substrate W in the chamber 1. The reducing gas is, for example, a gas containing hydrogen, and a more specific example is hydrogen gas. The reducing gas supply unit 5 may supply a carrier gas together with the hydrogen gas. The carrier gas is, for example, an inert gas such as nitrogen. A forming gas can be used as a mixed gas of hydrogen gas and an inert gas. In the forming gas, the ratio of hydrogen gas is, for example, about 3% to 4%. The reducing gas acts on the upper surface of the substrate W, and the oxide film formed on the wiring body 93 is reduced and returned to a part of the wiring body 93. This makes it possible to suppress or avoid a decrease in the cross-sectional area of ​​the wiring body 93 due to the oxide film, and to suppress or avoid an increase in the resistance value of the wiring body 93.

[0052] As described above, according to the substrate processing apparatus 100, the protruding portion 941 of the barrier film 94 can be etched by supplying an oxidizing gas. Meanwhile, the supply of the oxidizing gas forms an oxide film on the surface of the wiring body 93. The subsequent supply of a reducing gas can reduce the oxide film of the wiring body 93. Thus, the oxide film can be restored to a part of the wiring body 93. That is, the oxide film can be made to function as the wiring body 93 again. Therefore, an increase in the resistance value of the metal wiring portion 92 can be suppressed or avoided.

[0053] Next, a specific example of each component of the substrate processing apparatus 100 and a specific example of the operation of the substrate processing apparatus 100 will be described in detail.

[0054] <Substrate holding part> 1, the substrate holding unit 2 includes a mounting table 21. The substrate W is placed on the mounting table 21 in a horizontal position. The upper surface of the substrate W (specifically, the upper surface of the insulating film 91 and the upper surface of the metal wiring portion 92) is exposed in the chamber 1 with the substrate W placed on the mounting table 21.

[0055] <Heater> The heater 22 is controlled by the control unit 10 and heats the substrate W in the chamber 1. In the example of Fig. 1, the heater 22 is provided vertically below the substrate W held by the substrate holding unit 2. In the example of Fig. 1, the heater 22 is built into the mounting table 21. The heater 22 may be, for example, an electric resistance type heater including a heating wire, or may be an optical type heater including a light source that irradiates light for heating.

[0056] <Suction part> The suction unit 7 sucks gas from within the chamber 1. In the example of FIG. 1, the suction unit 7 includes a suction pipe 71 and a suction mechanism 72. The upstream end of the suction pipe 71 is connected to the chamber 1. In the example of FIG. 1, the suction pipe 71 includes branch pipes 711 and 712 and a junction pipe 713. The upstream end of the branch pipe 711 and the upstream end of the branch pipe 712 are connected to the chamber 1 vertically below the substrate W held by the substrate holding unit 2. In the example of FIG. 1, the upstream end of the branch pipe 711 and the upstream end of the branch pipe 712 are connected to the bottom of the chamber 1 on opposite sides to each other with respect to the substrate holding unit 2.

[0057] The downstream end of branch pipe 711 and the downstream end of branch pipe 712 are commonly connected to the upstream end of junction pipe 713, and the downstream end of junction pipe 713 is connected to suction mechanism 72. Suction mechanism 72 is, for example, a pump. Suction mechanism 72 is controlled by control unit 10, and suctions gas in chamber 1 through suction pipe 71.

[0058] <Gas supply section> The gas supply unit 3 includes a supply pipe 31. A downstream end of the supply pipe 31 is connected to the chamber 1. In the example of FIG. 1, the downstream end of the supply pipe 31 is connected to the ceiling of the chamber 1 and faces the substrate W held by the substrate holding unit 2 in the vertical direction. The downstream end of the supply pipe 31 functions as an air inlet for supplying gases into the chamber 1. In the example of FIG. 1, various gases are supplied into the chamber 1 from the air inlets of the supply pipe 31, and each gas flows toward the upper surface of the substrate W.

[0059] 1, the oxidizing gas supply unit 4 supplies an oxidizing gas into the chamber 1 through a supply pipe 31. For example, the oxidizing gas supply unit 4 includes a supply pipe 41, a valve 42, and a flow rate adjustment unit 43. The downstream end of the supply pipe 41 is connected to the supply pipe 31, and the upstream end of the supply pipe 41 is connected to an oxidizing gas supply source 44. The oxidizing gas supply source 44 supplies the oxidizing gas to the downstream end of the supply pipe 41.

[0060] Valve 42 is disposed in supply pipe 41. Valve 42 is controlled by control unit 10, and when valve 42 is opened, oxidizing gas is supplied from oxidizing gas supply source 44 through supply pipe 41 and supply pipe 31 into chamber 1. When valve 42 is closed, the supply of oxidizing gas is stopped.

[0061] The flow rate adjustment unit 43 is disposed in the supply pipe 41. The flow rate adjustment unit 43 is controlled by the control unit 10, and adjusts the flow rate of the oxidizing gas flowing through the supply pipe 41. The flow rate adjustment unit 43 is, for example, a mass flow controller.

[0062] 1, the reducing gas supply unit 5 supplies reducing gas into the chamber 1 through the supply pipe 31. For example, the reducing gas supply unit 5 includes a supply pipe 51, a valve 52, and a flow rate adjustment unit 53. The downstream end of the supply pipe 51 is connected to the supply pipe 31, and the upstream end of the supply pipe 51 is connected to a reducing gas supply source 54. The reducing gas supply source 54 supplies reducing gas to the downstream end of the supply pipe 51.

[0063] Valve 52 is provided in supply pipe 51. Valve 52 is controlled by control unit 10, and when valve 52 is opened, reducing gas is supplied from reducing gas supply source 54 through supply pipe 51 and supply pipe 31 into chamber 1. When valve 52 is closed, the supply of reducing gas is stopped.

[0064] The flow rate adjustment unit 53 is provided in the supply pipe 51. The flow rate adjustment unit 53 is controlled by the control unit 10, and adjusts the flow rate of the reducing gas flowing through the supply pipe 51. The flow rate adjustment unit 53 is, for example, a mass flow controller.

[0065] 1, the gas supply unit 3 further includes an inert gas supply unit 6. The inert gas supply unit 6 supplies an inert gas into the chamber 1. The inert gas includes, for example, at least one of a rare gas such as argon and nitrogen gas.

[0066] 1, the inert gas supply unit 6 supplies an inert gas into the chamber 1 through a supply pipe 31. For example, the inert gas supply unit 6 includes a supply pipe 61, a valve 62, and a flow rate adjustment unit 63. A downstream end of the supply pipe 61 is connected to the supply pipe 31, and an upstream end of the supply pipe 61 is connected to an inert gas supply source 64. The inert gas supply source 64 supplies an inert gas to the downstream end of the supply pipe 61.

[0067] A valve 62 is provided in the supply pipe 61. The valve 62 is controlled by the control unit 10, and when the valve 62 is opened, an inert gas is supplied from an inert gas supply source 64 through the supply pipe 61 and the supply pipe 31 into the chamber 1. When the valve 62 is closed, the supply of the inert gas is stopped.

[0068] The flow rate adjustment unit 63 is disposed in the supply pipe 61. The flow rate adjustment unit 63 is controlled by the control unit 10, and adjusts the flow rate of the inert gas flowing through the supply pipe 61. The flow rate adjustment unit 63 is, for example, a mass flow controller.

[0069] <Control Unit> FIG. 3 is a block diagram showing an example of the configuration of the control unit 10. The control unit 10 is an electronic circuit device and may have, for example, a data processing device 101 and a storage medium 102. The data processing device 101 may be, for example, an arithmetic processing device such as a CPU (Central Processor Unit). The storage medium 102 may have a non-transitory storage medium 1021 (for example, a ROM (Read Only Memory) or a hard disk) and a temporary storage medium 1022 (for example, a RAM (Random Access Memory)). The non-transitory storage medium 1021 may store, for example, a program that defines the processing executed by the control unit 10. The data processing device 101 executes this program, so that the control unit 10 can execute the processing defined in the program. Of course, a part or all of the processing executed by the control unit 10 may be executed by a hardware circuit such as a logic circuit.

[0070] <Operation of the substrate processing apparatus> Next, a description will be given of an example of the operation of the substrate processing apparatus 100. Fig. 4 is a flowchart showing an example of the operation of the substrate processing apparatus 100. In other words, Fig. 4 is a flowchart showing an example of a wiring forming method.

[0071] First, the substrate W is transferred into the chamber 1 by a transfer device (not shown) (step S1: loading step). As a result, the substrate W is placed on the mounting table 21 of the substrate holder 2. An insulating film 91 and a metal wiring portion 92 are formed on the upper surface of the substrate W.

[0072] Next, the suction unit 7 sucks the gas inside the chamber 1, and the heater 22 heats the substrate W (step S2: reduced pressure heating step). Specifically, the control unit 10 causes the suction mechanism 72 to perform a suction operation, and the heater 22 to perform a heating operation.

[0073] When the suction mechanism 72 performs a suction operation, gas in the chamber 1 is sucked into the suction mechanism 72 through the suction pipe 71, and the pressure in the chamber 1 decreases. The suction unit 7 adjusts the pressure in the chamber 1 to a predetermined process pressure suitable for processing. The predetermined process pressure is, for example, 400 Torr or more and 760 Torr or less. Note that 760 Torr indicates standard atmospheric pressure. In other words, the suction unit 7 does not necessarily have to be provided, and reducing the pressure in the chamber 1 is not a required step.

[0074] When depressurizing the chamber 1, the substrate processing apparatus 100 may be provided with a pressure sensor that measures the pressure in the chamber 1, and in this case, the control unit 10 may control the suction mechanism 72 based on a detection value of the pressure sensor. The suction unit 7 adjusts the pressure in the chamber 1 until the processing is completed.

[0075] The heater 22 performs a heating operation, thereby increasing the temperature of the substrate W. The heater 22 adjusts the temperature of the substrate W to a first predetermined temperature suitable for etching the metal wiring portion 92. The first predetermined temperature is, for example, 50° C. or more and 200° C. or less. The substrate processing apparatus 100 may be provided with a temperature sensor that detects the temperature of the substrate W. In this case, the control unit 10 may control the heater 22 based on a value detected by the temperature sensor. The heater 22 adjusts the temperature of the substrate W until the processing is completed.

[0076] Next, the oxidizing gas supply unit 4 supplies the oxidizing gas into the chamber 1 (step S3: etching step). Specifically, the control unit 10 opens the valve 42. As a result, the oxidizing gas is supplied from the oxidizing gas supply source 44 through the supply pipe 41 and the supply pipe 31 into the chamber 1, and flows through the chamber 1 toward the substrate W. Here, the oxidizing gas is ozone gas.

[0077] The oxidizing gas acts on the upper surface of the substrate W, and the barrier film 94 is oxidized and etched. Specifically, a protruding portion 941 of the barrier film 94 is etched. When the barrier film 94 is made of ruthenium, the protruding portion 941 of the barrier film 94 reacts with the ozone gas to generate ruthenium tetroxide gas, and the protruding portion 941 is etched. More specifically, the ozone gas in the chamber 1 decomposes into oxygen atoms and oxygen molecules on the high-temperature substrate W, the oxygen atoms react with ruthenium to generate ruthenium monoxide (RuO), and the ruthenium monoxide reacts with ozone to generate ruthenium tetroxide gas.

[0078] In step S3, the heater 22 heats the substrate W so that the temperature of the substrate W becomes a temperature suitable for etching (50° C. or higher and 200° C. or lower), so that the metal wiring portion 92 is etched more appropriately.

[0079] On the other hand, the oxidizing gas acts on the upper surface of the substrate W, thereby forming an oxide film on the upper surface of the wiring body 93. When the wiring body 93 is made of copper, a thin film of copper oxide is formed on the upper surface of the wiring body 93.

[0080] 5 is a cross-sectional view illustrating an example of the configuration of the substrate W after step S3. As illustrated in FIG. 5, in step S3, the protruding portion 941 of the barrier film 94 is removed by the oxidizing gas, while an oxide film 931 is formed on the upper surface of the wiring body 93.

[0081] When the protruding portion 941 is sufficiently removed, the oxidizing gas supply unit 4 stops the supply of the oxidizing gas (step S4: etching stop step). That is, the etching stops when the upper end of the barrier film 94 becomes substantially flush with the upper surface of the wiring body 93 (here, the upper surface of the oxide film 931). As a specific example, the control unit 10 judges whether or not the elapsed time from the start of the supply of the oxidizing gas is equal to or greater than a predetermined time, and closes the valve 42 when the elapsed time is equal to or greater than the predetermined time. The predetermined time is the time required to remove the protruding portion 941, and is set in advance, for example, by an experiment or a simulation.

[0082] Next, the oxidizing gas is discharged from the chamber 1 (step S5: oxidizing gas exhaust process). For example, the inert gas supply unit 6 supplies the inert gas into the chamber 1. Specifically, the control unit 10 opens the valve 62. This causes the inert gas to be supplied from the inert gas supply source 64 into the chamber 1 through the supply pipe 61 and the supply pipe 31. Thus, the inert gas pushes the oxidizing gas in the chamber 1 out toward the suction pipe 71. This can promote the exhaust of the oxidizing gas. When the oxidizing gas has been sufficiently discharged from the chamber 1, the inert gas supply unit 6 stops supplying the inert gas. Specifically, the control unit 10 closes the valve 62.

[0083] When a second predetermined temperature of the substrate W suitable for a reduction step (step S6) described later is different from the first predetermined temperature, the heater 22 heats the substrate W after step S4 so that the temperature of the substrate W becomes the second predetermined temperature (temperature changing step). The second predetermined temperature is, for example, 100°C or more and 300°C or less.

[0084] Next, the reducing gas supply unit 5 supplies reducing gas into the chamber 1 (step S6: reduction step). Specifically, the control unit 10 opens the valve 52. As a result, the reducing gas is supplied from the reducing gas supply source 54 through the supply pipe 51 and the supply pipe 31 into the chamber 1, and flows inside the chamber 1 toward the substrate W. Here, the reducing gas contains hydrogen gas.

[0085] When the reducing gas acts on the upper surface of the substrate W, the oxide film 931 is reduced and returns to a part of the wiring body 93. For example, if the oxide film 931 is copper oxide, the copper oxide reacts with the reducing gas and returns to copper (the wiring body 93).

[0086] 6 is a cross-sectional view showing an example of the configuration of the substrate W after step S6. Since the oxide film 931 returns to a part of the wiring body 93 by step S6, the oxide film 931 is not shown in the example of FIG. 6, and the upper end of the barrier film 94 is approximately flush with the upper surface of the wiring body 93.

[0087] In step S6, the heater 22 heats the substrate W so that the temperature of the substrate W becomes a temperature suitable for reducing the oxide film 931 (100° C. or higher and 300° C. or lower), so that the oxide film 931 is reduced more appropriately.

[0088] When the oxide film 931 is reduced and returns to a part of the wiring body 93, the reducing gas supply unit 5 stops the supply of the reducing gas (step S7: reduction stopping step). Specifically, the control unit 10 closes the valve 52. This stops the supply of the reducing gas.

[0089] Next, the substrate W is cooled (Step S8: cooling step). For example, the heater 22 finishes the heating operation, and the inert gas supply unit 6 supplies the inert gas to the substrate W in the chamber 1. This causes the inert gas to flow toward the upper surface of the substrate W, and the substrate W is air-cooled.

[0090] When the temperature of the substrate W has sufficiently decreased, the substrate W is unloaded from the chamber 1 by the transport device (step S9: unloading step). For example, the transport device unloads the substrate W from the chamber 1 when the temperature of the substrate W is 50° C. or less, more preferably 40° C. or 30° C. or less, and even more preferably 25° C. or less. As a more specific example, the transport device may unload the substrate W when a predetermined cooling time has elapsed since the start of step S8. The predetermined cooling time is the time for the temperature of the substrate W to become a predetermined value (e.g., 50° C.) or less, and is set in advance by experiment or simulation. Alternatively, in the case where a temperature sensor for detecting the temperature of the substrate W is provided, the transport device may unload the substrate W when the detected value of the temperature sensor becomes a predetermined value (e.g., 50° C.) or less.

[0091] According to this, even if the external space of the chamber 1 contains oxygen gas, natural oxidation of the metal wiring portion 92 can be suppressed.

[0092] As described above, according to the substrate processing apparatus 100, in a state in which the upper surface of the wiring body 93 of the substrate W and the protruding portion 941 of the barrier film 94 are exposed in the chamber 1, an oxidizing gas is supplied into the chamber 1 (step S3). Thus, the oxidizing gas acts on both the upper surface of the wiring body 93 of the substrate W and the protruding portion 941 of the barrier film 94. Therefore, the protruding portion 941 of the barrier film 94 can be etched by the oxidizing gas, while an oxide film 931 is formed on the upper surface of the wiring body 93.

[0093] After removing the protruding portion 941, a reducing gas is supplied to the substrate W in the chamber 1 in order to reduce the oxide film 931 generated in step S3 (step S6). This allows the reducing gas to react with the oxide film 931, and the oxide film 931 can be returned to a part of the wiring body 93.

[0094] Therefore, the protruding portion 941 of the barrier film 94 can be removed while suppressing or avoiding an increase in the resistance value of the wiring body 93.

[0095] A connection layer and a second wiring layer are formed in this order on the substrate W processed by the substrate processing apparatus 100. Fig. 7 shows an example of the configuration of the substrate W on which a connection layer 95 is formed. The connection layer 95 is a layer that electrically connects a second wiring layer (not shown) formed on the connection layer 95 and the first wiring layer 90. In the example of Fig. 7, the connection layer 95 includes a liner film 961, an insulating film 96, and a via portion 97.

[0096] The liner film 961 has insulating properties and functions as an etching stopper film for the insulating film 96. The liner film 961 is formed on the insulating film 91 and the metal wiring portion 92. The liner film 961 may be a multilayer film composed of a plurality of insulating films. For example, the liner film 961 may be a multilayer film including a nitrogen-added silicon carbide film (SiCN) and an aluminum oxide (Al2O3) film.

[0097] The insulating film 96 is also called an interlayer insulating film, and ensures insulation between the via portion 97 and the surroundings. The insulating film 96 is formed on a liner film 961. The insulating film 96 is, for example, a low dielectric film, similar to the insulating film 91. A via hole 96a is formed in the insulating film 96 and the liner film 961. The hole 96a penetrates the insulating film 96 and the liner film 961 in the thickness direction of the substrate W. In the example of FIG. 7, the via hole 96a is formed shifted from the metal wiring portion 92 in the horizontal direction. Specifically, the via hole 96a is formed straddling a part of the metal wiring portion 92 and a part of the insulating film 91 adjacent to the part.

[0098] The via portion 97 is provided inside the via hole 96a. The via portion 97 includes a via body 98 and a barrier film 99. The barrier film 99 is formed on the side and bottom surface of the via hole 96a, and has a thin thickness of about several nm. The barrier film 99 has a concave shape corresponding to the shape of the side and bottom surface of the via hole 96a, and has a stepped shape corresponding to the stepped shape of the metal wiring portion 92 and the insulating film 91 at the bottom surface of the via hole 96a.

[0099] The via body 98 is embedded inside the recessed portion of the barrier film 99. The via body 98 is formed of a metal material. As the metal material, for example, at least one of copper, molybdenum, cobalt, tungsten, platinum, and indium can be used. If copper, which has a low resistivity, is used as the metal material, the resistance value of the via body 98 can be reduced.

[0100] The barrier film 99 is made of a metal material capable of suppressing diffusion of the via body 98 into the insulating film 96 and the insulating film 91. More specifically, for example, ruthenium can be used as the metal material.

[0101] 7, the via portion 97 is formed offset from the metal wiring portion 92, and therefore a part of the via portion 97 is also formed on the upper surface of the insulating film 91. However, the upper surface of the metal wiring portion 92 is lower than the upper surface of the insulating film 91, and therefore a distance can be ensured between the via portion 97 and the metal wiring portion 92 adjacent to the via portion 97 (the metal wiring portion 92 on the right end in the figure). Therefore, a short circuit between the metal wiring portions 92 via the via portion 97 can be suppressed or avoided.

[0102] Moreover, in the example of FIG. 7, since the protruding portion 941 of the metal wiring portion 92 is removed, the area where the barrier film 99 of the via portion 97 and the barrier film 94 of the metal wiring portion 92 contact each other is small.

[0103] For comparison, a substrate W0 in which the protruding portion 941 of the barrier film 94 is not removed will be described. FIG. 8 is a cross-sectional view that shows an example of the configuration of the substrate W0 according to the comparative example. The substrate W0 has the same configuration as the substrate W except for the presence or absence of the protruding portion 941. In the substrate W0, since the protruding portion 941 of the barrier film 94 exists, the barrier film 99 of the via portion 97 is formed to overlap the protruding portion 941 in the thickness direction. Therefore, the width D0 of the portion of the lower surface of the via body 98 that is closest to the wiring body 93 of the metal wiring portion 92 is narrowed by the amount of the protruding portion 941. Therefore, the metal wiring portion 92 and the via portion 97 are electrically connected to each other with a higher resistance value.

[0104] In contrast, in the substrate W, the protruding portion 941 is removed (see FIG. 7). Therefore, the width D1 of the portion of the lower surface of the via body 98 closest to the wiring body 93 is increased by the amount of the protruding portion 941. Therefore, the metal wiring portion 92 and the via portion 97 are electrically connected to each other with a lower resistance value. In other words, by removing the protruding portion 941, the metal wiring portion 92 and the via portion 97 can be formed with a lower resistance. This can improve the performance of the semiconductor device.

[0105] <How to remove protruding parts of the barrier film> Incidentally, when etching the protruding portion 941 of the barrier film 94, in order to avoid oxidation of the wiring body 93, it is possible to form a temporary protective film on the upper surface of the wiring body 93 in advance and remove the protective film after etching. However, since the barrier film 94 is very thin, at a thickness of several nm, the position of the protective film also requires a similar accuracy of several nm. It is difficult to form a protective film with such positional accuracy.

[0106] In contrast, in the present embodiment, when etching with an oxidizing gas (step S3) is performed, the upper surface of the wiring body 93 is exposed, and no protective film has been formed in advance. As a result, an oxide film 931 is formed on the upper surface of the wiring body 93, but the oxide film 931 is returned to part of the wiring body 93 by the subsequent reduction treatment (step S6). This makes it possible to remove the protruding portion 941 of the barrier film 94 while omitting the difficult formation of a protective film.

[0107] Moreover, in this embodiment, the oxide film 931 formed on the wiring body 93 is not removed but is reduced, so that the oxide film 931 is restored to part of the wiring body 93. Thus, the resistance value of the wiring body 93 can be reduced.

[0108] <Oxidizing gas exhaust process> In the above example, step S5 (oxidizing gas exhaust step) is performed between step S3 (etching step) and step S6 (reduction step). In step S5, an inert gas is supplied into chamber 1 while the supply of oxidizing gas and reducing gas is stopped. This allows the oxidizing gas to be quickly exhausted from chamber 1. Then, after most of the oxidizing gas has been exhausted from chamber 1, the supply of reducing gas is started (step S6). In other words, the concentration of the oxidizing gas in chamber 1 is reduced before the supply of reducing gas is started. reductionAn oxidizing gas is supplied into the chamber 1. This makes it possible to suppress or avoid a reaction between the oxidizing gas and the reducing gas in the chamber 1, and to suppress or avoid a decrease in the amount of the reducing gas acting on the substrate W. Therefore, the oxide film 931 of the wiring body 93 can be reduced more efficiently.

[0109] <Cooling process> In the above example, step S8 (cooling step) is performed before step S9 (unloading step). Therefore, even if oxygen gas is present outside the chamber 1, the substrate W (more specifically, the metal wiring portion 92) is not likely to be naturally oxidized. In other words, natural oxidation of the substrate W can be suppressed by step S8.

[0110] <Second embodiment> 9 is a diagram illustrating an example of a configuration of a substrate processing apparatus 100A according to the second embodiment. The substrate processing apparatus 100A has a similar configuration to the substrate processing apparatus 100, except for the presence or absence of a gas sensor 8.

[0111] The gas sensor 8 is a sensor that detects a generated gas generated by a reaction between an oxidizing gas and the metal wiring portion 92 (more specifically, the barrier film 94). When the barrier film 94 is made of ruthenium, the gas sensor 8 detects, for example, ruthenium tetroxide gas. The gas sensor 8 is provided downstream of the substrate W held by the substrate holder 2 in the flow of the gas supplied by the gas supply portion 3. The gas sensor 8 may be provided in the chamber 1 or in the suction pipe 71. In the example of FIG. 9, the gas sensor 8 is provided in the chamber 1 near the upstream end (exhaust port) of the suction pipe 71. The generated gas generated on the upper surface of the substrate W flows to the exhaust port of the suction pipe 71 and is sucked into the suction pipe 71, so that the gas sensor 8 can effectively detect the generated gas.

[0112] The gas sensor 8 detects the generated gas and outputs an electric signal indicating the detection result to the control unit 10. The control unit 10 determines whether or not to stop etching the metal wiring portion 92 based on the amount (e.g., concentration) of the generated gas detected by the gas sensor 8.

[0113] FIG. 10 is a graph showing an example of the change over time in the amount of generated gas detected by gas sensor 8 when protruding portion 941 of barrier film 94 is etched. At the beginning of the etching process (step S3), the surface of protruding portion 941 is exposed inside chamber 1, and so the exposed area of ​​protruding portion 941 is large. Therefore, the area on which the oxidizing gas acts is large, and a larger amount of generated gas is generated. Protruding portion 941 is gradually etched over time, and so the exposed area of ​​protruding portion 941 gradually becomes smaller over time. Therefore, gas sensor 8 detects detection The amount of gas produced gradually decreases over time.

[0114] When the protruding portion 941 is removed, the barrier film 94 is exposed only at its upper end, and the exposed area becomes very small. Even if the upper end of the barrier film 94 is removed by the oxidizing gas, the exposed area of ​​the barrier film 94 hardly changes, so the concentration of the generated gas becomes almost constant regardless of the passage of time.

[0115] In this way, the amount of generated gas detected by the gas sensor 8 has a correlation with the amount of etching of the barrier film 94. Therefore, the control unit 10 determines whether or not to stop etching, that is, whether or not to stop the supply of oxidizing gas, based on the amount of generated gas detected by the gas sensor 8.

[0116] 11 is a flow chart showing an example of a specific operation of the etching process (step S3). In the etching process, first, the oxidizing gas supply unit 4 starts supplying the oxidizing gas (step S301). Specifically, the control unit 10 opens the valve 42. Next, the gas sensor 8 detects the generated gas (e.g., ruthenium tetroxide) (step S302: detection process).

[0117] Next, the control unit 10 judges whether the amount of generated gas detected by the gas sensor 8 satisfies the stop condition (step S303: judgment step). The stop condition is not particularly limited, but may be, for example, a first condition that the amount of generated gas detected by the gas sensor 8 is equal to or less than a predetermined reference amount Rref. The reference amount Rref is, for example, a value approximately equal to the amount of generated gas generated when the protruding portion 941 is removed, and is set in advance by experiment or simulation.

[0118] If the stop condition is not met, step S302 is performed again. If the stop condition is met, the etching stop step (step S4) is performed.

[0119] As described above, according to the substrate processing apparatus 100A, the etching is stopped based on the generated gas detected by the gas sensor 8. Therefore, the protruding portion 941 can be removed more reliably, and over-etching of the barrier film 94 can be suppressed more reliably.

[0120] 10, when the protruding portion 941 of the barrier film 94 is removed, the amount of generated gas becomes almost constant over time. Therefore, a second condition may be adopted as the stop condition, that is, the time rate of change of the amount of generated gas is equal to or less than a predetermined reference rate of change. The reference rate of change is set in advance, for example, by an experiment or a simulation.

[0121] Alternatively, both the first condition and the second condition may be adopted as the stop condition. That is, the control unit 10 may determine that the stop condition is satisfied when both the first condition and the second condition are satisfied. When both the first condition and the second condition are adopted, the reference amount Rref may be, for example, a value larger than the amount of generated gas generated when the protruding portion 941 is removed, and may be set in advance by experiment or simulation. By adopting both the first condition and the second condition, etching can be more appropriately terminated. For example, in FIG. 10, even if the time rate of change is small in the early stage of the etching process, the first condition is not satisfied, so that the etching does not stop. In addition, when the protruding portion 941 is removed, both the first condition and the second condition are satisfied, so that overetching can be more reliably suppressed.

[0122] <Third embodiment> An example of the configuration of the substrate processing apparatus 100 according to the third embodiment is similar to that of the first or second embodiment. In the third embodiment, a specific example of the etching process (step S3) is different from that of the first and second embodiments.

[0123] 12 is a timing chart showing an example of the etching process according to the third embodiment. In the etching process (step S3), the substrate processing apparatus 100 alternately repeats a first process S31 in which an oxidizing gas is supplied into the chamber 1 and a second process S32 in which an inert gas is supplied into the chamber 1. Specifically, the control unit 10 opens the valve 42 and closes the valve 62 in the first process S31. Moreover, the control unit 10 closes the valve 42 and opens the valve 62 in the second process S32.

[0124] In the first step S31, an oxidizing gas is supplied into the chamber 1, so that the oxidizing gas reacts with the metal wiring portion 92 (specifically, the protruding portion 941) of the substrate W, and the metal wiring portion 92 can be etched.

[0125] In the second step S32 after the first step S31, an inert gas is supplied into the chamber 1. This causes non-uniformity in the concentration of the oxidizing gas in the chamber 1. Specifically, the oxygen concentration is reduced in the upper part of the chamber 1. Therefore, the oxidizing gas near the upper surface of the substrate W quickly leaves the upper surface of the substrate W due to concentration diffusion.

[0126] In the subsequent first step S31, fresh oxidizing gas is again supplied into the chamber 1. Thus, the old oxidizing gas near the upper surface of the substrate W is easily replaced with the new oxidizing gas, and the new oxidizing gas easily acts on the upper surface of the substrate W. In the subsequent second step S32, inert gas is again supplied into the chamber 1, and the old oxidizing gas quickly leaves the vicinity of the substrate W.

[0127] As described above, by alternately repeating the first step S31 and the second step S32, etching can be performed while quickly replacing the old oxidizing gas on the substrate W with new oxidizing gas. This makes it possible to increase the etching rate of the substrate W by the oxidizing gas.

[0128] <Fourth embodiment> In the first to third embodiments, the metal wiring portion 92 formed on the substrate W includes two different types of metal films (here, the wiring main body 93 and the barrier film 94), one of the metal films (here, the barrier film 94) is etched by an oxidizing gas, and the other metal film (here, the wiring main body 93) forms an oxide film by the oxidizing gas.

[0129] However, the metal wiring portion 92 may be formed of at least one type of metal film. When the metal wiring portion 92 is formed of one type of metal film, a material that can be removed by reaction with an oxidizing gas but can also partially form an oxide film is used as the material for the metal wiring portion 92. For example, the metal wiring portion 92 may be formed of a metal film of ruthenium. Ruthenium generates ruthenium tetraoxide (RuO4) gas in response to an oxidizing gas, but can also partially generate solid ruthenium dioxide (RuO2). Therefore, if a metal film of ruthenium is etched with an oxidizing gas, an oxide film (ruthenium dioxide) may partially remain on the surface.

[0130] Fig. 13 is a cross-sectional view that shows a schematic example of the configuration of the substrate WA. The substrate WA has the same configuration as the substrate W, except for the configuration of the metal wiring portion 92. The substrate WA is provided with a metal wiring portion 92A instead of the metal wiring portion 92. In the example of Fig. 13, the metal wiring portion 92A is embedded in a trench 91a of an insulating film 91. As shown in Fig. 13, the metal wiring portion 92A may be formed of a single metal film 93A. The metal film 93A is formed of a metal material (e.g., ruthenium) that produces an oxide film while being etched by an oxidizing gas.

[0131] The metal film 93A is provided in the trench 91a of the insulating film 91, and the upper surface thereof is substantially flush with the upper surface of the insulating film 91.

[0132] An example of the operation of the substrate processing apparatus 100 is the same as that in Fig. 4. However, in step S1 (loading step), the substrate WA in Fig. 13 is loaded. Therefore, the substrate WA is held by the substrate holding part 2. At this time, the upper surface of the insulating film 91 and the upper surface of the metal film 93A of the substrate WA are exposed in the chamber 1.

[0133] In step S2 (decompression and heating step), the pressure in the chamber 1 is adjusted as necessary, while the temperature of the substrate WA is adjusted. In the next step S3 (etching step), an oxidizing gas acts on the upper surface of the metal film 93A to etch the metal film 93A. Specifically, the oxidizing gas reacts with the metal film 93A to generate ruthenium tetroxide gas, thereby etching the metal film 93A. As a result, the upper surface of the metal film 93A recedes from the upper surface of the insulating film 91. In addition, solid ruthenium dioxide may also be generated by the reaction between the oxidizing gas and the metal film 93A.

[0134] When the metal film 93A is sufficiently etched, step S4 (etching stop step) is performed. Since solid ruthenium dioxide may also be generated in step S3, ruthenium dioxide may remain on the upper surface of the metal film 93A at the end of step S4.

[0135] Therefore, for example, step S5 (oxidizing gas exhaust step) is followed by step S6 (reduction step). In step S6, a reducing gas acts on the upper surface of the substrate W, so that the ruthenium dioxide on the upper surface of the metal film 93A is reduced back to ruthenium. That is, the oxide on the upper surface of the metal film 93A can be restored to a part of the metal film 93A.

[0136] As described above, according to the substrate processing apparatus 100, the shape of the metal film 93A can be adjusted by etching the metal film 93A with an oxidizing gas, and further, oxides on the surface of the metal film 93A that may be generated by the oxidizing gas can be reduced to restore a part of the metal film 93A. Thus, the resistance value of the metal film 93A can be reduced.

[0137] As described above, the substrate processing apparatus 100, 100A and the wiring forming method have been described in detail, but the above description is merely an example in all respects, and the substrate processing apparatus 100, 100A and the wiring forming method are not limited thereto. It is understood that countless modified examples not illustrated can be imagined without departing from the scope of this disclosure. The configurations described in the above embodiments and modified examples can be appropriately combined or omitted as long as they are not mutually contradictory.

[0138] For example, the oxidizing gas is not limited to ozone gas, and gases such as halogenated oxygen gas and nitrogen oxide gas may be used. The oxidizing gas supply unit 4 may excite an oxidizing gas such as a gas containing oxygen and nitrogen oxide gas by ultraviolet light or plasma, and then supply it to the substrate W. As a specific example, a mixed gas of oxygen gas and chlorine gas may be used as the oxidizing gas, and the oxidizing gas supply unit 4 may generate plasma from the mixed gas and then supply it to the substrate W in the chamber 1. The reducing gas is not limited to hydrogen gas, and may be another gas such as carbon monoxide. [Explanation of symbols]

[0139] 1 Chamber 2 Board holding part 4. Oxidizing gas supply section 5. Reducing gas supply section 8 Gas Sensors 92,92A Metal wiring part 93 Wiring body 93A Metal film 94 Barrier Membrane 941 Projection part 2 Board holding part 4. Oxidizing gas supply section 5. Reducing gas supply section S1 Loading process S3 Etching process (step) S301 Detection process S302 Judgment process S31 1st process S32 2nd process S5 Oxidizing gas exhaust process (step) S6 Reduction step S7 Cooling process (step) S8 Unloading process (step) W substrate

Claims

1. A method for forming an interconnect, comprising the steps of: a carrying step of carrying the substrate on which the metal wiring portion is formed into a chamber; an etching step of supplying an oxidizing gas to the substrate to etch a portion of the metal wiring portion; a reduction step of supplying a reducing gas to the substrate to reduce an oxide film of the metal wiring portion formed by the etching step; Equipped with The metal wiring portion is a wiring body located within a trench in an insulating film of the substrate; a barrier film provided between the wiring body and the insulating film; Including, In the etching step, a part of the barrier film is etched as the part of the metal wiring portion; In the reducing step, the oxide film formed on the wiring body in the etching step is reduced.

2. The wiring forming method according to claim 1 , In the etching step, a protruding portion of the barrier film protruding from a surface of the wiring body is etched as the part of the metal wiring portion; In the reducing step, the oxide film formed on the surface of the wiring body by the etching step is reduced.

3. The wiring forming method according to claim 1 or 2, The method for forming a wiring, wherein the barrier film contains ruthenium.

4. The wiring forming method according to any one of claims 1 to 3, The wiring body includes at least one of copper, molybdenum, cobalt, tungsten, platinum, and indium.

5. The wiring forming method according to any one of claims 1 to 4, The etching step includes: a detection step of detecting a product gas generated by a reaction between the oxidizing gas and the metal wiring portion by a gas sensor; a determination step of determining whether or not to stop the etching step based on a detection value of the gas sensor; The wiring forming method includes:

6. The wiring forming method according to any one of claims 1 to 5, The wiring forming method further comprises an oxidizing gas exhaust step, which is performed between the etching step and the reducing step, of supplying an inert gas into the chamber and exhausting the oxidizing gas from the chamber.

7. 7. The wiring forming method according to claim 1, In the etching step, a first step of supplying the oxidizing gas; A second step of supplying an inert gas; The above steps are repeated alternately in the wiring formation method.

8. The wiring forming method according to any one of claims 1 to 7, In the etching step, the substrate is heated so that the temperature of the substrate is 50 degrees or more and 200 degrees or less.

9. 9. The wiring forming method according to claim 1, The wiring forming method, in the reducing step, wherein the substrate is heated to a temperature of 100° C. or more and 300° C. or less.

10. 10. The wiring forming method according to claim 1, a cooling step of cooling the substrate after the reducing step; a carrying-out step of carrying out the substrate from the chamber after the cooling step; The wiring forming method further comprises:

11. A substrate processing apparatus, comprising: A chamber; a substrate holder provided in the chamber for holding a substrate having a metal wiring portion formed thereon; an oxidizing gas supply unit that supplies an oxidizing gas to the substrate in the chamber to etch a portion of the metal wiring portion; a reducing gas supplying unit that supplies a reducing gas to the substrate to reduce an oxide film formed on the metal wiring portion by the oxidizing gas; Equipped with The metal wiring portion is a wiring body located within a trench in an insulating film of the substrate; a barrier film provided between the wiring body and the insulating film; Including, the oxidizing gas supply unit etches a protruding portion of the barrier film that protrudes from a surface of the wiring body as the part of the metal wiring portion; The reducing gas supply unit reduces the oxide film formed on the surface of the wiring body by the oxidizing gas supply unit.

Images