Substrate processing method and substrate processing apparatus

Abstract

A substrate processing method according to the present invention appropriately etches a ruthenium-containing layer without generating ruthenium tetroxide. This substrate processing method is provided with: a step for preparing a substrate (9), the surface of which is provided with a ruthenium-containing layer (93); bringing an etching solution (71), which contains chlorine and water and does not contain an oxidizing agent, into contact with the ruthenium-containing layer (93) on the substrate (9); and irradiating the ruthenium-containing layer (93) in contact with the etching solution (71) with excitation light that excites ruthenium. This makes it possible to suitably etch the ruthenium-containing layer (93) without generating gaseous ruthenium tetroxide.

Description

[0001] [CROSS - REFERENCE TO RELATED APPLICATIONS]

[0002] This application claims the benefit of priority of Japanese Patent Application JP2022 - 179859 filed on November 9, 2022, and all disclosures of this application are incorporated herein by reference. TECHNICAL FIELD

[0003] The present invention relates to a substrate processing method and a substrate processing apparatus. BACKGROUND ART

[0004] Conventionally, in the manufacturing process of a semiconductor substrate (hereinafter simply referred to as "substrate"), various processes are performed on the substrate. For example, after forming a conductive film on the main surface of the substrate, a process of removing the conductive film attached to the inclined surface portion or the like of the substrate is performed. In recent years, with the miniaturization of devices on the substrate, ruthenium (Ru) has attracted attention as a material for the conductive film. Ruthenium is difficult to remove simply by immersing it in an aqueous solution of an acid or a base such as hydrochloric acid or sodium hydroxide. Therefore, in International Publication No. 2019 / 138814 (Document 1), in order to etch ruthenium, an etching solution for ruthenium containing periodic acid and ammonia and having a pH value of 4.5 is proposed (Table 1, Example A32).

[0005] In addition, in Japanese Unexamined Patent Application Publication No. 2016 - 107272 (Document 2), a substrate processing apparatus for removing a film well from the peripheral portion of a substrate is disclosed. The apparatus includes: a liquid supply member that supplies liquid to the peripheral portion of a rotating substrate; a liquid holding member that is disposed close to a part of the peripheral portion and temporarily holds the liquid in the gap space with the peripheral portion to make the gap space liquid - tight; and a laser irradiation member that irradiates the part of the peripheral portion covered with the liquid with laser through the liquid to remove the film. In addition, in "The Photoelectric Effect at the Metal - Electrolyte Boundary" by L.I. Korshunov et al. 2 persons (Russian Chemical Reviews, 1971, Vol. 40, No. 8, pages 699 - 714) (Document 3), it is described that when a polar solution covers the surface of a substance, the work function of the photoelectric effect decreases.

[0006] However, when etching ruthenium using the etching solution of Document 1, although a high etching rate is obtained, there is a possibility of generating toxic gaseous ruthenium tetroxide (RuO4). SUMMARY OF THE INVENTION

[0007] The present invention is directed to a substrate processing method, and an object thereof is to appropriately etch a ruthenium-containing layer without generating ruthenium tetroxide.

[0008] Mode 1 of the present invention is a substrate processing method, which includes the following steps: step a), preparing a substrate having a ruthenium-containing layer provided on the surface; step b), bringing an etching solution containing chlorine and water and not containing an oxidizing agent into contact with the ruthenium-containing layer on the substrate; and step c), irradiating the ruthenium-containing layer contacted by the etching solution with excitation light that excites ruthenium.

[0009] According to the present invention, it is possible to appropriately etch a ruthenium-containing layer without generating ruthenium tetroxide.

[0010] Mode 2 of the present invention is the substrate processing method of Mode 1, wherein, in the step c), a water-soluble compound containing ruthenium and chlorine is generated.

[0011] Mode 3 of the present invention is the substrate processing method of Mode 1 (which may also be Mode 1 or 2), wherein the etching solution contains a surfactant.

[0012] Mode 4 of the present invention is the substrate processing method of Mode 1 (which may also be any one of Modes 1 to 3), wherein the wavelength of the excitation light is 270 nm or less.

[0013] Mode 5 of the present invention is the substrate processing method of any one of Modes 1 to 4, wherein, in the step b), the etching solution comes into contact with the peripheral portion of the substrate, and in the step c), the peripheral portion is irradiated with the excitation light.

[0014] Mode 6 of the present invention is the substrate processing method of any one of Modes 1 to 4, wherein the ruthenium-containing layer is provided on one main surface of the substrate, in the step b), a puddle of the etching solution is formed on the main surface of the substrate, and in the step c), the main surface is irradiated with the excitation light.

[0015] The present invention is also directed to a substrate processing apparatus.

[0016] Mode 7 of the present invention is a substrate processing apparatus, which includes: a substrate holding portion that holds a substrate having a ruthenium-containing layer provided on the surface; a liquid supply portion that supplies an etching solution containing chlorine and water and not containing an oxidizing agent onto the substrate to bring the etching solution into contact with the ruthenium-containing layer; and a light irradiation portion that irradiates the ruthenium-containing layer contacted by the etching solution with excitation light that excites ruthenium.

[0017] The above object and other objects, features, modes and advantages will become clearer by referring to the accompanying drawings in the following detailed description of the present invention. Description of the Drawings

[0018] Figure 1 It is a diagram showing the layout of the substrate processing system.

[0019] Figure 2 It is a diagram showing the configuration of the substrate processing apparatus according to the first embodiment.

[0020] Figure 3 It is a top view showing the substrate and the cover member.

[0021] Figure 4 It is a cross-sectional view showing the substrate and the cover member.

[0022] Figure 5 It is a cross-sectional view showing the substrate and the cover member.

[0023] Figure 6 It is a diagram showing the process flow of the substrate in the substrate processing apparatus.

[0024] Figure 7 It is a cross-sectional view showing a part of the substrate.

[0025] Figure 8 It is a diagram showing the configuration of the substrate processing apparatus according to the second embodiment.

[0026] Figure 9 It is a diagram showing a part of the substrate processing flow in the substrate processing apparatus.

[0027] Figure 10 It is a diagram showing the configuration of the substrate processing apparatus according to the third embodiment.

[0028] Figure 11 It is a diagram showing a plurality of divided regions on the upper surface of the substrate.

[0029] Figure 12A It is a cross-sectional view showing the ruthenium-containing layer provided on the substrate.

[0030] Figure 12B It is a cross-sectional view showing the ruthenium-containing layer provided on the substrate. Detailed Embodiments

[0031] Figure 1 It is a diagram showing the layout of the substrate processing system 10. The substrate processing system 10 is a system for processing a semiconductor substrate 9 (hereinafter simply referred to as "substrate 9"). The substrate processing system 10 includes an indexer block 101 and a processing area 102 coupled to the indexer block 101.

[0032] The indexer area 101 includes a carrier holding unit 104, an indexer robot 105, and an IR moving mechanism 106. The carrier holding unit 104 holds a plurality of carriers 107 each capable of accommodating a plurality of substrates 9. The plurality of carriers 107 (e.g., FOUP (front opening unified pod)) are held by the carrier holding unit 104 in a state arranged in a predetermined carrier arrangement direction. The IR moving mechanism 106 moves the indexer robot 105 in the carrier arrangement direction. The indexer robot 105 performs an unloading operation of unloading the substrate 9 from the carrier 107 and a loading operation of loading the substrate 9 into the carrier 107. The substrate 9 is transported by the indexer robot 105 in a horizontal posture.

[0033] The processing area 102 includes a plurality of (e.g., four or more) processing units 108 for processing the substrate 9 and a central robot 109. The plurality of processing units 108 are arranged so as to surround the central robot 109 in a plan view. Among the plurality of processing units 108, various processes are performed on the substrate 9. The following substrate processing apparatus is one of the plurality of processing units 108. The central robot 109 exchanges the substrate 9 with the indexer robot 105. In addition, the central robot 109 performs a loading operation of loading the substrate 9 into the processing unit 108 and an unloading operation of unloading the substrate 9 from the processing unit 108. The central robot 109 also transports the substrate 9 between the plurality of processing units 108. The substrate 9 is transported by the central robot 109 in a horizontal posture.

[0034] Figure 2 It is a diagram showing the configuration of the substrate processing apparatus 1 according to the first embodiment. In Figure 2 it, a part of the configuration of the substrate processing apparatus 1 is shown in a cross section of a plane including a predetermined central axis J1. The substrate processing apparatus 1 is a single wafer type apparatus that processes the substrate 9 one by one. The substrate processing apparatus 1 performs wet etching on the peripheral portion of the substrate 9. The peripheral portion of the substrate 9 includes an edge end face (apex), a beveled surface, and a portion near the beveled surface in the following upper surface 91 and lower surface 92.

[0035] The substrate processing apparatus 1 includes a substrate holding portion 21, a substrate rotating mechanism 22, a supply head 3, a light irradiation portion 4, a liquid supply portion 5, a cover member 6, a housing 11, and a control portion 8. The substrate holding portion 21, the substrate rotating mechanism 22, the supply head 3, a part of the light irradiation portion 4, and the cover member 6 are accommodated in the internal space of the housing 11. The control portion 8 is arranged outside the housing 11 and controls each component of the substrate processing apparatus 1. The control portion 8 is implemented, for example, by a computer having a CPU (Central Processing Unit), a memory, etc. executing a prescribed program. A part or all of the control portion 8 can also be implemented using a programmable logic controller (PLC: Programmable Logic Controller) or the like.

[0036] Figure 2 The substrate holding portion 21 and substrate rotating mechanism 22 shown are part of a rotating chuck that holds and rotates a roughly disk-shaped substrate 9. The substrate holding portion 21 holds the substrate 9 in a horizontal state from the bottom. The substrate holding portion 21 is, for example, a vacuum chuck that holds the substrate 9 by adsorption. The substrate holding portion 21 has a roughly disk-shaped base portion 211 in the central portion of the main surface (hereinafter, also referred to as the "lower surface 92") on the lower side of the substrate 9 that contacts and adsorbs. The diameter of the base portion 211 is smaller than the diameter of the substrate 9. Depending on the design of the substrate processing device 1, the substrate holding portion 21 may also be a mechanical chuck that holds the substrate 9.

[0037] A ruthenium-containing layer 93 containing ruthenium (Ru) is provided on the surface of the substrate 9. Figure 2 In the example shown, the ruthenium-containing layer 93 is in the form of a film (i.e., a ruthenium-containing film) extending over the entire main surface of the upper side of the substrate 9 (hereinafter also referred to as "upper surface 91"). Figure 2 In the figure, the ruthenium-containing layer 93 is represented by a bold line. The ruthenium-containing layer 93 only needs to be a layer containing ruthenium, and in addition to a layer of ruthenium simple substance, it can also be a layer containing a ruthenium compound. The ruthenium-containing layer 93 can be, for example, a film-like shape provided on the entire upper surface 91 and / or lower surface 92 of the substrate 9, or a pattern-like shape covering only a portion of the surface of the substrate 9. In the present embodiment, the ruthenium-containing layer 93 is a ruthenium-containing film provided on the entire upper surface 91 of the substrate 9, and the peripheral portion of the substrate 9 is also covered by the ruthenium-containing film. In addition, the ruthenium-containing layer 93 is a ruthenium film formed entirely of ruthenium simple substance. Figure 2 The substrate holding portion 21 holds the substrate 9 from below in a state where the upper surface 91 on which the ruthenium-containing film is formed faces upward. In addition, a diffusion prevention film 94 or the like may be provided between the ruthenium-containing layer 93 and the substrate 9 (see the following). Figure 7 ).

[0038] The substrate rotation mechanism 22 is disposed below the substrate holding portion 21. The substrate rotation mechanism 22 rotates the substrate 9 together with the substrate holding portion 21 about a central axis J1 that extends substantially parallel in the vertical direction. The substrate rotation mechanism 22 includes a shaft 221 and a motor 222. The shaft 221 is a member having a substantially cylindrical or substantially cylindrical shape about the central axis J1. The shaft 221 extends in the vertical direction and is connected to the central portion of the lower surface of the base portion 211 of the substrate holding portion 21. The motor 222 is an electric rotary motor that rotates the shaft 221. In addition, the substrate rotation mechanism 22 may also be a motor having other configurations (for example, a hollow motor, etc.).

[0039] The supply head 3 is disposed above the central portion of the substrate 9. The supply head 3 faces the upper surface 91 of the substrate 9 in the vertical direction at a position spaced upward from the upper surface 91 of the substrate 9. The supply head 3 includes a head lower portion 31, a head upper portion 32, and a central nozzle 33. The head lower portion 31 is a substantially circular ring plate-shaped portion about the central axis J1. The lower surface of the head lower portion 31 is a substantially horizontal plane that extends substantially parallel to the upper surface 91 of the substrate 9 and faces the upper surface 91 of the substrate 9 in the vertical direction. The diameter of the outer peripheral edge of the head lower portion 31 in plan view is smaller than the diameter of the substrate 9. The head upper portion 32 is a substantially cylindrical portion about the central axis J1 and extends upward from the upper surface of the head lower portion 31. The head upper portion 32 is also a support portion that supports the head lower portion 31 from above. An arm is connected to the head upper portion 32, and by moving the arm using a mechanism having a motor or the like, the supply head 3 can move, for example, in the vertical direction and the radial direction (the radial direction about the central axis J1).

[0040] The central nozzle 33 is disposed in a through hole provided in the central portion of the head lower portion 31. A processing liquid (here, a rinsing liquid) is supplied to the central nozzle 33 via a pipe provided inside the head upper portion 32. The rinsing liquid supplied to the central nozzle 33 is ejected from the central nozzle 33 toward the central portion of the substrate 9 and spreads toward the peripheral portion on the upper surface 91 of the rotating substrate 9. The rinsing liquid scattered from the peripheral portion of the substrate 9 is recovered on the bottom surface of the housing 11 and discharged to the waste liquid recovery portion 12 (the same applies to the etching liquid described below). The rinsing liquid is, for example, DIW (deionized water). The rinsing liquid is not limited to DIW and can be variously changed. In addition, various processing liquids other than the rinsing liquid may be ejected from the central nozzle 33.

[0041] The light irradiation unit 4 includes a light source 41 and an optical system 42. The light source 41 is disposed outside the housing 11. The light source 41 emits light that excites ruthenium (i.e., excitation light). This light is, for example, ultraviolet light. The wavelength of this light is preferably 270 nm or less, more preferably less than 264 nm (the reason will be described below). In the present embodiment, the light source 41 is a laser that emits a laser beam L, such as an excimer laser (KrF: wavelength 248 nm, ArF: wavelength 193 nm), or a DUV - YAG (deep ultra violet - yttrium aluminum garnet) fourth - harmonic laser (wavelength: 266 nm), etc. The power of this laser can be determined appropriately. The light source 41 can also be a semiconductor laser or the like. A window portion 111 is provided on the side surface portion of the housing 11, and the window portion 111 is formed of a material (e.g., quartz glass, etc.) that is transparent to the laser beam L from the light source 41. The laser beam L enters the housing 11 through the window portion 111. In Figure 2 the figure, the path of the laser beam L is indicated by a single - dotted line with the same reference numeral (the same applies to the paths of the following laser beams L1 and L2). The light emitted from the light source 41 can also be light other than a laser beam.

[0042] The optical system 42 is disposed inside the housing 11 and includes a beam splitter 421 and a plurality of reflectors 422, 423, 424. The laser beam L that enters the housing 11 is branched into two laser beams L1 and L2 (hereinafter, also simply referred to as "laser") through the beam splitter 421. One of the two laser beams L1 and L2, the laser beam L1, is reflected by the reflector 422 and enters the peripheral portion of the upper surface 91 obliquely from above the substrate 9. The path (optical axis) of the laser beam L1 between the reflector 422 and the substrate 9 is inclined with respect to the upper surface 91 of the substrate 9. In addition, the other laser beam L2 is sequentially reflected by the reflectors 423 and 424 and enters the peripheral portion of the lower surface 92 obliquely from below the substrate 9. The path (optical axis) of the laser beam L2 between the reflector 424 and the substrate 9 is inclined with respect to the lower surface 92 of the substrate 9. As described below, the laser beams L1 and L2 are irradiated to the peripheral portion of the substrate 9 through the cover member 6. Figure 2 The configuration of the light irradiation unit 4 described above is merely an example and can be changed appropriately. For example, the light source for irradiating the peripheral portion of the upper surface 91 with a laser and the light source for irradiating the peripheral portion of the lower surface 92 with a laser can also be provided individually. In this case, the beam splitter 421 and the like can be omitted, and the configuration of the optical system 42 can be simplified.

[0043] Figures 3 to 5 FIG. is for explaining the structure of the cover member 6. Figure 3 FIG. shows the substrate 9 and the cover member 6 when viewed from above the substrate 9 downward, that is, in a plan view. Figure 4 FIG. shows Figure 3The cross-section of the substrate 9 and the cover member 6 at the position of arrow IV-IV (the upstream-side end portion 611 described below). Figure 5 It shows Figure 3 The cross-section of the substrate 9 and the cover member 6 at the position of arrow V-V (the downstream-side end portion 612 described below).

[0044] As Figure 3 shown, the cover member 6 has a cover portion 61 and a liquid introduction portion 62. The cover portion 61 is an arc-shaped portion that extends along the peripheral portion of the substrate 9. In a plan view, the cover portion 61 overlaps a part of the peripheral portion of the substrate 9. The cover portion 61 has an upstream-side end portion 611 and a downstream-side end portion 612. In the example of Figure 3 , as shown by arrow A1, the substrate 9 rotates counterclockwise. Regarding the moving direction of the peripheral portion due to the rotation of the substrate 9, the downstream-side end portion 612 is located downstream of the upstream-side end portion 611. That is, when each part of the peripheral portion of the substrate 9 passes through the position of the cover portion 61, it moves from the upstream-side end portion 611 toward the downstream-side end portion 612.

[0045] As Figure 4 and Figure 5 shown, the shape of the cover portion 61 in a cross-section parallel to the radial direction is an arc shape along the peripheral portion of the substrate 9. In other words, the cover portion 61 has a cross-sectional shape that is bent in a C shape so as to surround the peripheral portion of the substrate 9. A gap space G is formed between the opposing surface 616 of the cover portion 61 that faces the peripheral portion of the substrate 9 and the peripheral portion. The interval between the opposing surface 616 of the cover portion 61 and the peripheral portion of the substrate 9 is, for example, 0.5 mm to 1 mm. This interval can be appropriately changed according to the magnitude of the surface tension of the etching solution described below, etc. An arm is connected to the cover member 6, and the cover member 6 can be moved, for example, in the vertical direction and the radial direction by the movement of this arm caused by a mechanism having a motor or the like.

[0046] As Figure 3 and Figure 4 shown, the liquid introduction portion 62 is tubular and extends radially outward from the upstream-side end portion 611 of the cover portion 61. One end of the liquid introduction portion 62 opens on the opposing surface 616 of the cover portion 61 and is connected to the gap space G. The etching solution is supplied to the other end of the liquid introduction portion 62 from the liquid supply portion 5. As a result, the etching solution 71 is injected into the gap space G, and the gap space G becomes a state filled with the etching solution 71 (a liquid-tight state). In other words, the etching solution 71 is supplied to the peripheral portion of the substrate 9 via the cover member 6 by the liquid supply portion 5. As described above, each part of the peripheral portion of the substrate 9 enters the inside of the cover portion 61 (gap space G) from the upstream-side end portion 611, that is, the opening side of the liquid introduction portion 62.

[0047] Here, the etching solution 71 supplied by the liquid supply unit 5 is a chlorine-based electrolytic solution, containing chlorine and water (solvent). An example of the etching solution 71 is an aqueous solution containing hydrogen chloride (HCl) or ammonium chloride (NH4Cl) etc. as a solute. The concentration of this solute is, for example, 0.7 wt% or more, preferably 1.8 wt% or more. The upper limit of the concentration of this solute is not particularly limited, for example, it is 3.6 wt%. The etching solution 71 may also contain a surfactant. An example of the surfactant is ethanol or isopropyl alcohol (IPA) etc. In addition, for the following reasons, the etching solution 71 does not contain an oxidizing agent. The oxidizing agent in this specification reacts with ruthenium to produce ruthenium oxide.

[0048] Figure 5 The shown cover part 61 is formed of a material (for example, quartz glass etc.) having permeability to the laser beams L1, L2 from the light irradiation part 4. In addition, the etching solution 71 also has permeability to the laser beams L1, L2. The laser beams L1, L2 are irradiated to the peripheral part of the substrate 9 via the downstream end part 612 of the cover part 61 and the etching solution 71 in the gap space G. In Figure 5 In the cross-section of the shown substrate 9, the irradiation range of the laser beam L1 extends from the edge end face of the substrate 9 to the part near the inclined face part in the upper surface 91. In addition, the irradiation range of the laser beam L2 extends from the edge end face of the substrate 9 to the part near the inclined face part in the lower surface 92. In the edge end face, the irradiation range of the laser beam L1 overlaps with the irradiation range of the laser beam L2. Therefore, in the cross-section of the substrate 9, the range from the part near the inclined face part in the upper surface 91 via the edge end face to the part near the inclined face part in the lower surface 92, that is, the entire peripheral part in this cross-section is included in the irradiation range of the laser beams L1, L2.

[0049] In the following process, the part of the ruthenium-containing layer 93 on the substrate 9 irradiated with the laser is etched. Therefore, in the peripheral part of the substrate 9, when the ruthenium-containing layer 93 exists only on one side of the upper surface 91 side and the lower surface 92 side, only one of the laser beams L1, L2 can also be used. In the cover member 6, the cover part 61 and the liquid introduction part 62 may be integrally formed of the same material, or the two may be formed as different individuals. When the cover part 61 and the liquid introduction part 62 are formed as different individuals, the two may also be formed of different materials.

[0050] Next, refer to Figure 6, the processing flow of the substrate 9 in the substrate processing apparatus 1 will be described. When processing the substrate 9, first, the substrate 9 is carried into the substrate processing apparatus 1 and held substantially horizontally by the substrate holding unit 21 (step S11). Thus, a substrate 9 having a ruthenium-containing layer 93 (in this embodiment, a ruthenium film) on its surface is prepared. In step S11, the position of the substrate 9 is adjusted so that the center of the substrate 9 coincides with the central axis J1 in a plan view. When the substrate 9 is carried in, the supply head 3 and the cover member 6 are arranged at retracted positions that do not obstruct the loading and unloading of the substrate 9 (for example, positions radially outward from the substrate 9 in a plan view). When the substrate 9 is held by the substrate holding unit 21, the substrate 9 is started to be rotated by the substrate rotation mechanism 22. In addition, the cover member 6 moves from the above retracted position to the Figure 2 position shown, and a gap space G is formed between the opposing surface 616 of the cover portion 61 and the peripheral portion of the substrate 9.

[0051] Furthermore, the control unit 8 controls the liquid supply unit 5, thereby starting to introduce the etching liquid 71 into the liquid introduction portion 62 of the cover member 6, and supplying the etching liquid 71 to the gap space G at the upstream end portion 611 of the cover portion 61. The etching liquid 71 in the gap space G is transported to the downstream side in the moving direction toward the peripheral portion by the rotation of the substrate 9, and is discharged to the outside of the gap space G on the downstream side of the downstream end portion 612 of the cover portion 61. The discharged etching liquid 71 is thrown off by the centrifugal force and scattered radially outward from the peripheral portion of the substrate 9. In fact, the etching liquid 71 is continuously supplied to the gap space G by the liquid supply unit 5, and the state where the gap space G is filled with the etching liquid 71 is maintained. In this way, the etching liquid 71 comes into contact with the ruthenium-containing layer 93 on the peripheral portion of the substrate 9 (step S12). In addition, if only the etching liquid 71 is contacted, the ruthenium-containing layer 93 is hardly etched.

[0052] At this time, the centrifugal force caused by the rotation of the substrate 9 is used to suppress the etching liquid 71 attached to the peripheral portion from flowing toward the radially inner side. In addition, the range in which the etching liquid 71 diffuses in the circumferential direction centered on the central axis J1 is substantially limited to the range of the peripheral portion opposed to the cover portion 61. In the substrate processing apparatus 1, an inert gas (for example, nitrogen) is ejected from the supply head 3 arranged at the Figure 2 position toward the central portion of the substrate 9, and the etching liquid 71 attached to the peripheral portion can be more reliably suppressed from flowing toward the radially inner side. In addition, the rotation speed of the substrate 9 can be appropriately changed within a range capable of filling the gap space G with the etching liquid 71.

[0053] Furthermore, the light irradiation unit 4 is controlled by the control unit 8, so that the laser beams L1 and L2 from the light irradiation unit 4 are continuously irradiated onto the peripheral portion of the substrate 9 via the downstream end portion 612 of the cover portion 61 and the etching solution 71 in the gap space G (step S13). In other words, the laser beams L1 and L2 are irradiated onto the ruthenium-containing layer 93 in contact with the etching solution 71. At this time, by rotating the substrate 9, the portions of the peripheral portion of the substrate 9 that are in contact with the etching solution 71 and irradiated with the laser beams L1 and L2 are sequentially switched along the circumferential direction. The irradiation of the laser beams L1 and L2 may also be intermittent (pulse irradiation).

[0054] Figure 7 is a cross-sectional view showing a part of the substrate 9. In Figure 7 the example of, a diffusion prevention film 94 or the like is provided between the ruthenium-containing layer 93 and the main body of the substrate 9. As described above, the laser beams L1 and L2 are excitation lights for exciting ruthenium, and due to the photoelectric effect caused by the irradiation of the laser beams L1 and L2, as Figure 7 shown, photoelectrons (e - ) are released from the surface of ruthenium contained in the ruthenium-containing layer 93, forming holes (h + ). Moreover, the etching solution 71 reacts with the holes to etch the ruthenium-containing layer 93.

[0055] Although the chemical reaction for the etching of the ruthenium-containing layer 93 is not necessarily clear, the following assumption can be made, that is, the reaction represented by

[0056] Ru + HCl + h + → (Ru(III)-Cl(aq)) + H + ···(1)

[0057] 2H + + 2e - → H2 ···(2)

[0058] occurs. In the chemical reaction formula (1), (Ru(III)-Cl(aq)) represents a water-soluble compound containing ruthenium and chlorine (hereinafter, referred to as "Ru-Cl water-soluble compound"). The Ru-Cl water-soluble compound is RuCl 2+ , RuCl2 + , RuCl3, RuCl4 - and so on.

[0059] The reaction product, i.e., the Ru-Cl water-soluble compound, dissolves in the etching solution 71 and is removed from the substrate 9 together with the etching solution 71. Thereby, the product containing ruthenium and chlorine can be inhibited from remaining on the surface of the substrate 9. Typically, the Ru-Cl water-soluble compound is non-toxic. In addition, since the etching solution 71 does not contain an oxidizing agent, gaseous ruthenium tetroxide (RuO4) is not generated. Assuming that an etching solution containing an oxidizing agent such as sodium hypochlorite is used, there is a case where a layer of ruthenium dioxide (RuO2) is generated on the surface of the ruthenium-containing layer 93, and the etching rate is significantly reduced or the etching is insufficient. On the other hand, if the etching solution 71 does not contain hypochlorous acid and salts of hypochlorous acid, the generation of a layer of ruthenium dioxide can be inhibited or prevented.

[0060] In addition, in the present embodiment, by including a surfactant (here, ethanol) in the etching solution 71, the generation of large irregularities on the surface of the ruthenium-containing layer 93 after etching can be inhibited or prevented. Although the reason is not necessarily clear, it is considered that if the etching solution 71 does not contain a surfactant, the hydrogen gas (H2) generated (refer to the above chemical reaction formula (2)) stays (exists) as bubbles on the surface of the ruthenium-containing layer 93, hindering the progress of ruthenium etching. In contrast, if the etching solution 71 has a reduced surface tension due to the presence of a surfactant, the retention of hydrogen bubbles can be inhibited.

[0061] Generally, in order to form holes (h + ) on the surface of ruthenium, photon energy greater than the work function of ruthenium (4.71 eV) is required. In this case, the wavelength of the light irradiated onto ruthenium is required to be less than 264 nm. On the other hand, as described in “The Photoelectric Effect at the Metal-Electrolyte Boundary” by L I Korshunov et al. (Russian Chemical Reviews, 1971, Vol. 40, No. 8, pp. 699 - 714) (the above-mentioned Document 3), it is known that when a polar solution covers the surface of a substance, the work function in the photoelectric effect decreases. Therefore, in the present treatment example where the surface of the ruthenium-containing layer 93 is covered by the etching solution 71, even when the wavelengths of the lasers L1 and L2 from the light irradiation unit 4 are 264 nm or more, photoelectrons are released from the surface of ruthenium. From the viewpoint of more reliably forming holes on the surface of the ruthenium-containing layer 93, the wavelengths of the lasers L1 and L2 are preferably 270 nm or less, and more preferably less than 264 nm.

[0062] If a predetermined time has elapsed since the start of irradiation of the lasers L1 and L2 (excitation light) from the peripheral portion of the substrate 9, the supply of the etching solution 71 to the peripheral portion and the irradiation of the lasers L1 and L2 are stopped. Thereby, the etching of the ruthenium-containing layer 93 is stopped. Then, the cover member 6 moves from Figure 2It moves from the shown position to the above-described retracted position. In addition, a camera or the like for photographing the peripheral portion of the substrate 9 may be provided, and the end point of the etching of the peripheral portion may be automatically detected based on the photographed image (the same applies hereinafter).

[0063] Furthermore, the supply head 3 is arranged at Figure 2 the shown position (which may be pre-arranged), and the rinsing liquid is supplied from the central nozzle 33 to the central portion of the upper surface 91 of the substrate 9. In addition, the rotation speed of the substrate 9 is increased by the substrate rotation mechanism 22. Thereby, the rinsing liquid diffuses over the entire upper surface 91 of the substrate 9, and a rinsing process for rinsing the etching liquid 71 or the like adhering to the peripheral portion of the substrate 9 is performed (step S14). The rinsing liquid scatters radially outward from the peripheral portion of the substrate 9 due to the centrifugal force caused by the rotation of the substrate 9, and is recovered by the waste liquid recovery unit 12.

[0064] If the rinsing process of the substrate 9 has been performed for a prescribed time, the supply of the rinsing liquid from the central nozzle 33 is stopped. Then, the rotation speed of the substrate 9 is further increased, and the rinsing liquid on the substrate 9 is thrown off and removed. That is, a drying process of the substrate 9 is performed (step S15). If the drying process of the substrate 9 is completed, the rotation of the substrate 9 is stopped, and the substrate 9 is taken out from the substrate processing apparatus 1. In addition, the rinsing process and the drying process of the substrate 9 may also be performed by a method different from the above example.

[0065] Figure 8 FIG. is a diagram showing the configuration of the substrate processing apparatus 1a according to the second embodiment. In the substrate processing apparatus 1a, compared with the Figure 2 substrate processing apparatus 1, the cover member 6 is omitted. In addition, the liquid supply unit 5 is connected to the central nozzle 33 of the supply head 3, and the etching liquid 71 and the rinsing liquid are selectively ejected from the central nozzle 33. The other configurations of the substrate processing apparatus 1a are the same as those of the substrate processing apparatus 1, and the same reference numerals are given to the same configurations.

[0066] In the present embodiment, a ruthenium-containing layer 93 is provided on the entire upper surface 91 of the substrate 9, and a protective film 97 is provided on the ruthenium-containing layer 93. The protective film 97 is, for example, a SOG (spin-on-glass) film, and is provided in the entire area of the upper surface 91 of the substrate 9 except for the peripheral portion. The shape of the protective film 97 in a plan view is substantially circular.

[0067] The processing flow of the substrate 9 in the substrate processing apparatus 1a is the same as that of Figure 9 the shown one, except for performing the Figure 6 shown steps S21 and S22 between the above-described rinsing process (step S14) and the drying process (step S15). Specifically, first, the substrate 9 provided with the above-described protective film 97 on the ruthenium-containing layer 93 is held by the substrate holding unit 21 for preparation ( Figure 6: Step S11). Additionally, the substrate 9 is caused to start rotating by the substrate rotation mechanism 22.

[0068] Furthermore, the liquid supply unit 5 is controlled by the control unit 8, so that the etching liquid 71 is continuously ejected from the central nozzle 33 of the supply head 3 toward the central portion of the upper surface 91 of the substrate 9. The etching liquid 71 diffuses radially outward on the protective film 97 due to the centrifugal force caused by the rotation of the substrate 9, and contacts the ruthenium-containing layer 93 exposed from the protective film 97 at the peripheral portion of the substrate 9 (Step S12). The etching liquid 71 is also drawn toward the lower surface 92 side of the substrate 9, and substantially the entire peripheral portion is covered by the etching liquid 71. Additionally, the light irradiation unit 4 is controlled by the control unit 8, so that the laser beams L1, L2 from the light irradiation unit 4 are irradiated to the peripheral portion of the substrate 9 via the etching liquid 71 (Step S13). Thereby, holes are formed on the surface of the ruthenium contained in the ruthenium-containing layer 93, and the etching liquid 71 reacts with the holes to etch the ruthenium-containing layer 93. At this time, the region of the ruthenium-containing layer 93 covered by the protective film 97 is not etched.

[0069] If a predetermined time has elapsed since the laser beams L1, L2 started irradiating the peripheral portion of the substrate 9, the supply of the etching liquid 71 and the irradiation of the laser beams L1, L2 are stopped. Thereby, the etching of the ruthenium-containing layer 93 is stopped. Furthermore, a rinsing liquid is supplied from the central nozzle 33 to the central portion of the substrate 9, and the rotation speed of the substrate 9 is increased by the substrate rotation mechanism 22 to perform a rinsing process (Step S14).

[0070] If the rinsing process of the substrate 9 has been performed for a predetermined time, the supply of the rinsing liquid to the substrate 9 is stopped, and the protective film 97 is removed from the substrate 9 ( Figure 9 : Step S21). As described above, in the case where the protective film 97 is a SOG film, in Step S21, for example, the protective film 97 is removed by supplying hydrogen fluoride (HF) to the protective film 97. The hydrogen fluoride can be ejected from the central nozzle 33 or from a dedicated nozzle. In addition, the type of the protective film 97 and the method for removing the protective film 97 can be variously changed.

[0071] If the removal of the protective film 97 is completed, a rinsing liquid is supplied from the central nozzle 33 to the central portion of the substrate 9 to perform a rinsing process of the substrate 9 (Step S22). Then, the rotation speed of the substrate 9 is increased to perform a drying process of the substrate 9 ( Figure 6 : Step S15). If the drying process of the substrate 9 is completed, the rotation of the substrate 9 is stopped, and the substrate 9 is unloaded from the substrate processing apparatus 1a.

[0072] As described above, the substrate processing methods of the first embodiment and the second embodiment include the following steps: preparing a substrate 9 having a ruthenium-containing layer 93 provided on its surface (step S11); bringing an etching solution 71 containing chlorine and water and not containing an oxidizing agent into contact with the ruthenium-containing layer 93 on the substrate 9 (step S12); and irradiating the ruthenium-containing layer 93 contacted by the etching solution 71 with excitation light that excites ruthenium (step S13). Thereby, a gaseous and toxic ruthenium tetroxide and a layer of ruthenium dioxide that is difficult to etch are not generated, and the ruthenium-containing layer 93 can be appropriately etched.

[0073] In the first embodiment and the second embodiment, in step S12, the etching solution 71 comes into contact with the peripheral portion of the substrate 9, and in step S13, the peripheral portion is irradiated with excitation light. Thereby, only the ruthenium-containing layer 93 in the peripheral portion can be appropriately etched (that is, the ruthenium-containing layer 93 other than the peripheral portion is not etched).

[0074] Preferably, in step S13, a water-soluble compound containing ruthenium and chlorine is generated. Thereby, the product can be removed from the substrate 9 together with the etching solution 71 and discharged to the outside of the housing 11. As a result, the ruthenium-containing product remaining on the substrate 9 and inside the housing 11 can be suppressed, and thus the generation of ruthenium tetroxide can be more reliably prevented or suppressed.

[0075] Preferably, the etching solution 71 contains a surfactant. Thereby, the unevenness of the surface after etching can be reduced, that is, uniform etching can be achieved.

[0076] Preferably, the wavelength of the excitation light is 270 nm or less. Thereby, the ruthenium-containing layer 93 can be more reliably etched. In addition, if ruthenium can be excited, the wavelength of the excitation light can also be greater than 270 nm.

[0077] The substrate processing apparatus 1 of the first embodiment and the second embodiment includes: a substrate holding unit 21 that holds a substrate 9 having a ruthenium-containing layer 93 provided on its surface; a liquid supply unit 5 that supplies an etching solution 71 containing chlorine and water and not containing an oxidizing agent onto the substrate 9 to bring the etching solution 71 into contact with the ruthenium-containing layer 93; and a light irradiation unit 4 that irradiates the ruthenium-containing layer 93 contacted by the etching solution 71 with excitation light that excites ruthenium. Thereby, the ruthenium-containing layer 93 can be appropriately etched without generating gaseous ruthenium tetroxide or the like.

[0078] Figure 10 FIG. shows the configuration of a substrate processing apparatus 1b according to a third embodiment. The substrate processing apparatus 1b is an apparatus for wet-etching a wiring portion on the upper surface 91 of a substrate 9. In the substrate processing apparatus 1b, Figure 2Compared with the substrate processing apparatus 1, the cover member 6 is omitted, and the liquid supply unit 5 (not shown) is connected to the central nozzle 33 of the supply head 3. Further, the light irradiation unit 4a is disposed above the housing 11, and an irradiation unit moving mechanism 49 for moving the light irradiation unit 4a is provided. The other configuration of the substrate processing apparatus 1b is the same as that of the substrate processing apparatus 1, and the same reference numerals are given to the same configurations.

[0079] The light irradiation unit 4a includes a light source and an optical system, and emits light (i.e., excitation light) for exciting ruthenium. A window portion 112 is provided on the upper surface portion of the housing 11, and the window portion 112 is formed of a material (e.g., quartz glass or the like) having permeability to the light from the light irradiation unit 4a. This light enters the housing 11 through the window portion 112 and is irradiated onto a region of a predetermined size on the upper surface 91 of the substrate 9 held by the substrate holding portion 21. The irradiation unit moving mechanism 49 has a motor or the like as a drive source, and can move the light irradiation unit 4a in two directions substantially parallel to and intersecting with the upper surface 91. Thus, as Figure 11 shown, light from the light irradiation unit 4a is irradiated onto each of a plurality of divided regions 911 that divide the upper surface 91 of the substrate 9.

[0080] Figure 12A and Figure 12B are cross-sectional views showing a ruthenium-containing layer 93 provided on the upper surface 91 of the substrate 9. An insulating film 95 is provided on the substrate 9, and a wiring portion 96 as a wiring pattern is formed in the insulating film 95. A diffusion prevention film 94 formed of tantalum nitride (TaN), for example, is provided between the wiring portion 96 and the insulating film 95. In Figure 12A the example on the left side of, the main body (wiring main body) of the wiring portion 96 is the ruthenium-containing layer 93. In Figure 12B the example on the left side of, the main body of the wiring portion 96 is a metal portion 961 formed of copper (Cu) or the like, and a metal film (e.g., a lining film) covering the side surface and the bottom surface of the metal portion 961 is the ruthenium-containing layer 93.

[0081] Next, the processing flow of the substrate 9 in the substrate processing apparatus 1b will be described based on Figure 6 . First, the substrate 9 having the ruthenium-containing layer 93 on the upper surface 91 is held by the substrate holding portion 21 for preparation (step S11). Further, the etching liquid 71 is ejected from the central nozzle 33 of the supply head 3 toward the central portion of the upper surface 91 of the substrate 9 for a certain period of time, and then the ejection of the etching liquid 71 is stopped. Thus, a liquid film (liquid film of the etching liquid 71) of the etching liquid 71 is formed on the upper surface 91 of the substrate 9 held in a horizontal state, and the state where the etching liquid 71 is in contact with the ruthenium-containing layer 93 on the upper surface 91 is maintained (step S12). Typically, the liquid film of the etching liquid 71 covers the entire upper surface 91. In the formation of the liquid film of the etching liquid 71, the substrate 9 may be rotated at a low speed.

[0082] After the supply head 3 moves to the retracted position, with the rotation of the substrate 9 stopped, light is sequentially irradiated from the light irradiation unit 4a onto a plurality of divided regions 911 (step S13). That is, the ruthenium-containing layer 93 in contact with the etching solution 71 is irradiated with excitation light. Thereby, holes are formed on the surface of the ruthenium contained in the ruthenium-containing layer 93, and the etching solution 71 reacts with the holes to etch the ruthenium-containing layer 93. In Figure 12A In the example on the right side of Figure 12B In the example on the right side of

[0083] After irradiating the plurality of divided regions 911 with the excitation light a specified number of times, the supply head 3 returns to the Figure 10 position shown in , and a rinsing solution is supplied from the central nozzle 33 to the central portion of the substrate 9. In addition, the substrate 9 is caused to start rotating by the substrate rotation mechanism 22. Thereby, a rinsing process for rinsing the etching solution 71 etc. on the substrate 9 is performed (step S14).

[0084] Preferably, in the processing of the substrate 9 in the substrate processing apparatus 1b, after the rinsing process, an organic solvent such as IPA is supplied from the central nozzle 33 to the central portion of the upper surface 91 of the substrate 9. Thus, by replacing the rinsing solution with an organic solvent having a smaller surface tension, collapse of the pattern during drying of the substrate 9 can be prevented. After the supply of the organic solvent from the central nozzle 33 stops, the rotation speed of the substrate 9 is further increased, and a drying process of the substrate 9 is performed (step S15). When the drying process of the substrate 9 ends, the rotation of the substrate 9 stops, and the substrate 9 is taken out from the substrate processing apparatus 1.

[0085] As described above, the substrate processing method of the third embodiment includes the following steps: preparing a substrate 9 having a ruthenium-containing layer 93 provided on its surface (step S11); bringing an etching solution 71 containing chlorine and water and not containing an oxidizing agent into contact with the ruthenium-containing layer 93 on the substrate 9 (step S12); and irradiating the ruthenium-containing layer 93 in contact with the etching solution 71 with excitation light that excites ruthenium (step S13). Thereby, the ruthenium-containing layer 93 can be appropriately etched without generating gaseous ruthenium tetroxide etc.

[0086] In the above-described third embodiment, a ruthenium-containing layer 93 is provided on the upper surface 91 of the substrate 9. Moreover, in step S12, a liquid film of the etching solution 71 is formed on the upper surface 91 of the substrate 9, and in step S13, the upper surface 91 is irradiated with excitation light. Thereby, the ruthenium-containing layer 93 contained in the wiring portion 96 of the upper surface 91 can be appropriately etched. Of course, the ruthenium-containing layer 93 at the peripheral portion of the substrate 9 can also be etched by irradiating the peripheral portion of the substrate 9 with excitation light.

[0087] However, in the case where the above-described grooves are formed by dry etching, etching residues (side effects) sometimes occur along the sides due to its anisotropy. In this regard, in the above-described substrate processing method, since isotropic wet etching is performed, generation of etching residuals can be suppressed, in other words, uniformity of the etching depth can be ensured.

[0088] In the above-described substrate processing method and substrate processing apparatuses 1, 1a, and 1b, various modifications can be made.

[0089] Depending on the type of the etching solution 71 and the like, the product generated in step S13 may also be a substance other than the water-soluble compound containing ruthenium and chlorine. Further, the etching solution 71 may not contain a surfactant.

[0090] In the substrate processing apparatuses 1 and 1a that etch the ruthenium-containing layer 93 on the peripheral portion of the substrate 9, a nozzle may also be provided on the side or the lower surface 92 side of the substrate 9, and the etching solution may be supplied to the peripheral portion from the nozzle. Further, the substrate 9 may be held by the substrate holding portion 21 in a state where the main surface provided with the ruthenium-containing layer 93 faces downward.

[0091] In the substrate processing apparatuses 1 and 1a, a plurality of cover members 6 may also be arranged in the circumferential direction, and the etching solution 71 may be supplied to the peripheral portion of the substrate 9 and the excitation light may be irradiated in each cover member 6. Further, as Figure 10 shown, the excitation light may also be irradiated to the peripheral portion of the stationary substrate 9 by moving the light irradiation unit 4a.

[0092] In the substrate processing apparatus 1b that etches the ruthenium-containing layer 93 on the upper surface 91 of the substrate 9, for example, a light irradiation unit that irradiates excitation light may also be provided in a linear region extending radially outward from the central portion of the substrate 9, and the excitation light may be irradiated to substantially the entire upper surface 91 by rotating the substrate 9. In this case, the etching solution 71 may also be continuously supplied to the upper surface 91 of the substrate 9.

[0093] In the substrate processing apparatuses 1, 1a, and 1b, a heater for heating the etching solution 71 may also be provided. An example of this heater is an electric heater disposed below the peripheral portion of the substrate 9 and opposed to the lower surface 92 of the substrate 9.

[0094] The substrate processed in the substrate processing apparatuses 1, 1a, and 1b is not limited to a semiconductor substrate, and may also be a glass substrate or other substrate. Further, the shape of the substrate may also be other than a disk shape.

[0095] The configurations in the above-described embodiments and each modification example can be appropriately combined as long as they do not conflict with each other.

[0096] The invention is described using detailed descriptions, but the descriptions given are illustrative and not restrictive. Therefore, it can be said that there can be multiple variations and modes as long as the scope of the present invention is not departed from.

[0097] Description of Reference Numerals

[0098] 1, 1a, 1b: Substrate processing apparatus

[0099] 4, 4a: Light irradiation unit

[0100] 5: Liquid supply unit

[0101] 9: Substrate

[0102] 21: Substrate holding unit

[0103] 71: Etching solution

[0104] 91: (Upper surface of the substrate)

[0105] 93: Ruthenium-containing layer

[0106] S11 to S15, S21, S22: Steps

Claims

1. A substrate processing method, wherein, The substrate processing method includes the following steps: Step a), preparing a substrate having a ruthenium-containing layer provided on the surface; Step b), bringing an etching solution containing chlorine and water and not containing an oxidizing agent into contact with the ruthenium-containing layer on the substrate; and Step c), irradiating the ruthenium-containing layer contacted by the etching solution with excitation light that excites ruthenium.

2. The substrate processing method according to claim 1, wherein in step c), a water-soluble compound containing ruthenium and chlorine is generated.

3. The substrate processing method according to claim 1, wherein the etching solution contains a surfactant.

4. The substrate processing method according to claim 1, wherein the wavelength of the excitation light is 270 nm or less.

5. The substrate processing method according to any one of claims 1 to 4, wherein in step b), the etching solution comes into contact with the peripheral portion of the substrate, and in step c), the peripheral portion is irradiated with the excitation light.

6. The substrate processing method according to any one of claims 1 to 4, wherein the ruthenium-containing layer is provided on one main surface of the substrate, in step b), a liquid covering of the etching solution is formed on the main surface of the substrate, and in step c), the main surface is irradiated with the excitation light.

7. A substrate processing apparatus, wherein, The substrate processing apparatus includes: a substrate holding portion that holds a substrate having a ruthenium-containing layer provided on the surface; a liquid supply portion that supplies an etching solution containing chlorine and water and not containing an oxidizing agent onto the substrate to bring the etching solution into contact with the ruthenium-containing layer; and a light irradiation portion that irradiates the ruthenium-containing layer contacted by the etching solution with excitation light that excites ruthenium.

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