Substrate processing method and substrate processing device

Abstract

(Task) No ruthenium tetroxide is formed, and the ruthenium-containing layer is properly etched. (Solution) A substrate processing method comprises a process of preparing a substrate (9) having a ruthenium-containing layer (93) formed on its surface, a process of contacting an etching solution (71) containing chlorine and water and not containing an oxidizing agent with the ruthenium-containing layer (93) on the substrate (9), and a process of irradiating an excitation light that excites ruthenium with respect to the ruthenium-containing layer (93) to which the etching solution (71) is in contact. Accordingly, gaseous ruthenium tetroxide is not generated, and the ruthenium-containing layer (93) can be properly etched.

Description

Technology Field

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

[0002] [Reference to related applications]

[0003] The present application claims the benefit of priority from Japanese patent application JP 2022-179859 filed on November 9, 2022, and all disclosures of said application are incorporated herein. Background Technology

[0004] Conventionally, in the manufacturing process of a semiconductor substrate (hereinafter simply referred to as "substrate"), various treatments are performed on the substrate. For example, after forming a conductive film on the main surface of the substrate, a treatment is performed to remove the conductive film attached to the bevel portion of the substrate. Recently, due to the miniaturization of devices on the substrate, ruthenium (Ru) is attracting attention as a material for the conductive film. Ruthenium is difficult to remove by merely immersing it in an aqueous solution of an acid or alkali, such as hydrochloric acid or sodium hydroxide. Therefore, International Publication No. 2019 / 138814 (Reference 1) proposes an etching solution for ruthenium containing orthoperiodic acid and ammonia and having a pH of 4.5 (Table 1, Example A32) to etch ruthenium.

[0005] In addition, Japanese Patent Publication No. 2016-107272 (Reference 2) discloses a substrate processing apparatus for effectively removing a film from the periphery of a substrate. The apparatus comprises a liquid supply means for supplying liquid to the periphery of a rotating substrate, a liquid holding member that is positioned in close proximity to a part of the periphery and temporarily maintains liquid in the gap space with the periphery to make the gap space liquid-tight, and a laser irradiation means for irradiating laser light through the liquid onto a portion of the periphery covered by the liquid and removing the film. Furthermore, in “The Photoelectric Effect at the Metal-Electrolyte Boundary” by LI Korshunov et al. (Russian Chemical Reviews, 1971, Vol. 40, No. 8, pp. 699-714) (Reference 3), it is described that when a polar solution covers the surface of a material, the work function in the photoelectric effect decreases.

[0006] However, when etching ruthenium using the etching solution of Literature 1, a high etching rate is obtained, but there is a risk that toxic gaseous ruthenium tetroxide (RuO4) will be produced. The problem to be solved

[0007] The present invention relates to a substrate processing method, and aims to properly etch a ruthenium-containing layer without generating ruthenium tetroxide. means of solving the problem

[0008] An embodiment 1 of the present invention comprises a substrate treatment method comprising: a) a step of preparing a substrate having a ruthenium-containing layer formed on its surface; b) a step of contacting an etching solution containing chlorine and water and not containing an oxidizing agent with the ruthenium-containing layer on the substrate; and c) a step of irradiating the ruthenium-containing layer in contact with the etching solution with an excitation light that excites ruthenium.

[0009] According to the present invention, ruthenium tetroxide is not generated, and the ruthenium-containing layer can be properly etched.

[0010] Aspect 2 of the present invention is a substrate treatment method of Aspect 1, wherein in process c), a water-soluble compound containing ruthenium and chlorine is produced.

[0011] Aspect 3 of the present invention is a substrate treatment method of Aspect 1 (it may be Aspect 1 or Aspect 2), wherein the etching solution contains a surfactant.

[0012] Aspect 4 of the present invention is a substrate treatment method of Aspect 1 (which may be any one of Aspects 1 to 3), wherein the wavelength of the excitation light is 270 nm or less.

[0013] Aspect 5 of the present invention is a substrate processing method of any one of embodiments 1 to 4, wherein in process b), the etching solution contacts the periphery of the substrate, and in process c), the excitation light is irradiated onto the periphery.

[0014] Aspect 6 of the present invention is a substrate treatment method of any one of embodiments 1 to 4, wherein the ruthenium-containing layer is formed on one main surface of the substrate, in step b), the pudding of the etching solution is formed on the main surface of the substrate, and in step c), the excitation light is irradiated on the main surface.

[0015] The present invention also relates to a substrate processing device.

[0016] Aspect 7 of the present invention is a substrate processing apparatus comprising: a substrate holding part that holds a substrate having a ruthenium-containing layer formed on its surface; a liquid supply part that supplies an etching solution containing chlorine and water and not containing an oxidizing agent onto the substrate to bring it into contact with the ruthenium-containing layer; and a light irradiation part that irradiates an excitation light to excite ruthenium onto the ruthenium-containing layer to which the etching solution is in contact.

[0017] The above-described objectives and other objectives, features, embodiments, and advantages will become apparent from the detailed description of the present invention below with reference to the attached drawings. Brief explanation of the drawing

[0018] Figure 1 is a diagram showing the layout of a substrate processing system. FIG. 2 is a diagram showing the configuration of a substrate processing device related to the first embodiment. FIG. 3 is a plan view showing a substrate and a cover member. FIG. 4 is a cross-sectional view showing a substrate and a cover member. FIG. 5 is a cross-sectional view showing a substrate and a cover member. FIG. 6 is a diagram showing the processing flow of a substrate in a substrate processing apparatus. Figure 7 is a cross-sectional view showing a part of the substrate. FIG. 8 is a diagram showing the configuration of a substrate processing device related to a second embodiment. FIG. 9 is a diagram showing a part of the processing flow of a substrate in a substrate processing apparatus. FIG. 10 is a drawing showing the configuration of a substrate processing device related to the third embodiment. FIG. 11 is a drawing showing a plurality of divided regions on the upper surface of a substrate. FIG. 12a is a cross-sectional view showing a ruthenium-containing layer formed on a substrate. FIG. 12b is a cross-sectional view showing a ruthenium-containing layer formed on a substrate. Specific details for implementing the invention

[0019] FIG. 1 is a diagram showing the layout of a 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) is equipped with an indexer block (101) and a processing block (102) coupled to the indexer block (101).

[0020] The indexer block (101) is equipped with a carrier holding part (104), an indexer robot (105), and an IR moving mechanism (106). The carrier holding part (104) holds a plurality of carriers (107), each capable of holding a plurality of substrates (9). The plurality of carriers (107) (e.g., FOUP) are held in the carrier holding part (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 outgoing operation to remove the substrate (9) from the carrier (107) and an incoming operation to bring the substrate (9) into the carrier (107). The substrate (9) is conveyed in a horizontal position by the indexer robot (105).

[0021] The processing block (102) is equipped with a plurality (e.g., four or more) processing units (108) and a center robot (109) for processing a substrate (9). The plurality of processing units (108) are arranged to surround the center robot (109) when viewed from a plane. Various processing operations on the substrate (9) are performed in the plurality of processing units (108). The substrate processing device described below is one of the plurality of processing units (108). The center robot (109) performs the exchange of the substrate (9) with the indexer robot (105). Additionally, the center robot (109) performs an incoming operation to bring the substrate (9) into the processing unit (108) and an outgoing operation to take the substrate (9) out of the processing unit (108). The center robot (109) also carries the substrate (9) between multiple processing units (108). The substrate (9) is carried in a horizontal position by the center robot (109).

[0022] FIG. 2 is a diagram showing the configuration of a substrate processing device (1) related to a first embodiment. In FIG. 2, a part of the configuration of the substrate processing device (1) is shown as a cross-section on a plane including a predetermined central axis (J1). The substrate processing device (1) is a single-wafer type device that processes substrates (9) one by one. The substrate processing device (1) performs wet etching on the periphery of the substrate (9). The periphery of the substrate (9) includes an edge cross section (apex), a bevel section, and a portion near the bevel section on the upper surface (91) and lower surface (92) described later.

[0023] A substrate processing device (1) comprises a substrate holding part (21), a substrate rotation mechanism (22), a supply head (3), a light irradiation part (4), a liquid supply part (5), a cover member (6), a housing (11), and a control part (8). The substrate holding part (21), the substrate rotation mechanism (22), a part of the supply head (3) and the light irradiation part (4), and the cover member (6), etc., are accommodated in the internal space of the housing (11). The control part (8) is positioned outside the housing (11) and controls each component of the substrate processing device (1). The control part (8) is realized, for example, by a computer having a CPU, memory, etc., executing a predetermined program. Part or all of the control part (8) may be realized by a programmable logic controller (PLC), etc.

[0024] The substrate holding part (21) and substrate rotation mechanism (22) shown in FIG. 2 are part of a spin chuck that holds and rotates a substrate (9) in a roughly disc shape. The substrate holding part (21) holds the substrate (9) in a horizontal state from the bottom. The substrate holding part (21) is, for example, a vacuum chuck that holds the substrate (9) by adsorbing it. The substrate holding part (21) is provided with a roughly disc-shaped base part (211) that is adsorbed by contacting the central part of the lower surface of the substrate (9) (hereinafter also referred to as the "bottom surface (92)"). The diameter of the base part (211) is smaller than the diameter of the substrate (9). Depending on the design of the substrate processing device (1), the substrate holding part (21) may hold the substrate (9) by a mechanical chuck, etc.

[0025] A ruthenium-containing layer (93) containing ruthenium (Ru) is formed on the surface of the substrate (9). In the example shown in FIG. 2, the ruthenium-containing layer (93) is a film-like structure (i.e., a ruthenium-containing film) that is spread over the entire upper surface of the substrate (9) (hereinafter also referred to as the "upper surface (91)"). In FIG. 2, the ruthenium-containing layer (93) is indicated by a thick line. The ruthenium-containing layer (93) may be a layer containing ruthenium, and may be a layer containing a compound of ruthenium in addition to a layer of ruthenium as a single substance. The ruthenium-containing layer (93) may be, for example, a film-like structure formed over the entire upper surface (91) and / or lower surface (92) of the substrate (9), or a pattern-like structure covering only a part of the surface of the substrate (9). In this embodiment, the ruthenium-containing layer (93) is a ruthenium-containing film formed over the entire upper surface (91) of the substrate (9), and the periphery of the substrate (9) is also covered by said ruthenium-containing film. Furthermore, the ruthenium-containing layer (93) is a ruthenium film formed entirely of ruthenium. The substrate holding portion (21) of FIG. 2 holds the substrate (9) from below while the upper surface (91) on which said ruthenium-containing film is formed faces upward. Additionally, a diffusion barrier film (94), etc., may be formed between the ruthenium-containing layer (93) and the substrate (9) (see FIG. 7 described later).

[0026] The substrate rotation mechanism (22) is positioned below the substrate holding part (21). The substrate rotation mechanism (22) rotates the substrate (9) together with the substrate holding part (21) around a central axis (J1) that extends approximately parallel in the vertical direction. The substrate rotation mechanism (22) is equipped with a shaft (221) and a motor (222). The shaft (221) is a member having an approximately cylindrical or approximately cylindrical shape centered around the central axis (J1). The shaft (221) extends in the vertical direction and is connected to the lower central part of the base part (211) of the substrate holding part (21). The motor (222) is an electric rotary motor that rotates the shaft (221). Additionally, the substrate rotation mechanism (22) may be a motor having a different structure (e.g., a hollow motor).

[0027] The supply head (3) is positioned 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 separated upward from the upper surface (91) of the substrate (9). The supply head (3) is equipped with a head lower portion (31), a head upper portion (32), and a center nozzle (33). The head lower portion (31) is a portion shaped like a roughly toroidal plate centered on a central axis (J1). The lower surface of the head lower portion (31) is a roughly horizontal plane that expands approximately 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 edge of the head lower portion (31) when viewed in a plane is smaller than the diameter of the substrate (9). The head upper portion (32) is a roughly cylindrical portion centered on 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 the upper side. An arm is connected to the head upper portion (32), and due to the movement of the arm by a mechanism having a motor or the like, the supply head (3) can move, for example, in the vertical direction and the radial direction (radial direction centered on the central axis (J1)).

[0028] The center nozzle (33) is positioned within a through hole formed in the center of the lower part of the head (31). A processing liquid (here, rinse liquid) is supplied to the center nozzle (33) through a pipe formed inside the upper part of the head (32). The rinse liquid supplied to the center nozzle (33) is discharged from the center nozzle (33) toward the center of the substrate (9) and spreads toward the periphery on the upper surface (91) of the rotating substrate (9). The rinse liquid scattered from the periphery of the substrate (9) is recovered on the bottom surface of the housing (11) and discharged to the waste liquid recovery unit (12) (the same applies to the etching liquid described later). The rinse liquid is, for example, DIW (deionized water). The rinse liquid is not limited to DIW and may be changed in various ways. In addition, various types of processing fluid other than rinse fluid may be discharged from the center nozzle (33).

[0029] The light irradiation unit (4) has a light source (41) and an optical system (42). The light source (41) is placed outside the housing (11). The light source (41) emits light that excites ruthenium (i.e., excitation light). The light is, for example, ultraviolet light. The wavelength of the light is preferably 270 nm or less, and more preferably less than 264 nm (the reason will be described later). In this embodiment, the light source (41) is a laser that emits laser light (L), for example, an excimer laser (KrF: wavelength 248 nm, ArF: wavelength 193 nm), or a DUV-YAG 4x wavelength laser (wavelength: 266 nm), etc. The power of the laser may be appropriately determined. The light source (41) may be a semiconductor laser, etc. A window (111) is formed on the side of the housing (11), and the window (111) is formed by a material (e.g., quartz glass, etc.) that is transparent to laser light (L) from a light source (41). The laser light (L) is incident into the housing (11) through the window (111). In FIG. 2, the path of the laser light (L) is indicated by a dashed line with the same symbol (the same applies to the path of the laser light (L1, L2) described later). The light emitted from the light source (41) may be other than laser light.

[0030] The optical system (42) is disposed inside the housing (11) and is equipped with a beam splitter (421) and a plurality of reflective mirrors (422, 423, 424). Laser light (L) incident into the housing (11) is split into two rays L1 and L2 (hereinafter likewise referred to as "laser light") by the beam splitter (421). One of the two laser rays (L1, L2), laser light (L1), is reflected by the reflective mirror (422) and incident on the periphery of the upper surface (91) from an oblique upper side of the substrate (9). The path (optical axis) of the laser light (L1) between the reflective mirror (422) and the substrate (9) is inclined with respect to the upper surface (91) of the substrate (9). Additionally, the laser light (L2) from the other side is reflected sequentially by the reflecting mirrors (423, 424) and is incident on the periphery of the lower surface (92) from the oblique downward side of the substrate (9). The path (optical axis) of the laser light (L2) between the reflecting mirror (424) and the substrate (9) is inclined with respect to the lower surface (92) of the substrate (9). As described below, the laser light (L1, L2) is irradiated onto the periphery of the substrate (9) through the cover member (6). The configuration of the light irradiation unit (4) in FIG. 2 is merely an example and may be appropriately modified. For example, a light source that irradiates the laser light onto the periphery of the upper surface (91) and a light source that irradiates the laser light onto the periphery of the lower surface (92) may be formed separately. In this case, it is possible to simplify the configuration of the optical system (42), such as by omitting the beam splitter (421).

[0031] FIGS. 3 to 5 are drawings for explaining the structure of the cover member (6). FIG. 3 shows the substrate (9) and the cover member (6) as viewed from above toward below, that is, as viewed from a planar perspective. FIG. 4 shows a cross-section of the substrate (9) and the cover member (6) at the position of arrow IV-IV in FIG. 3 (upstream end (611) described later). FIG. 5 shows a cross-section of the substrate (9) and the cover member (6) at the position of arrow VV in FIG. 3 (downstream end (612) described later).

[0032] As shown in FIG. 3, 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 periphery of the substrate (9). When viewed from a plane, the cover portion (61) overlaps with a part of the periphery of the substrate (9). The cover portion (61) has an upstream end (611) and a downstream end (612). In the example of FIG. 3, as indicated by arrow A1, the substrate (9) is rotated counterclockwise, and with respect to the direction of movement of the periphery due to the rotation of the substrate (9), the downstream end (612) is located downstream of the upstream end (611). That is, each part of the main portion of the substrate (9) moves from the upstream end (611) to the downstream end (612) when passing through the position of the cover portion (61).

[0033] As shown in FIGS. 4 and 5, the shape of the cover portion (61) in a cross-section parallel to the diameter direction is an arc shape along the periphery of the substrate (9). In other words, the cover portion (61) has a cross-sectional shape that is curved in a C shape to surround the periphery of the substrate (9). A gap space (G) is formed between the opposing surface (616) of the cover portion (61) that faces the periphery of the substrate (9) and the periphery said. The gap between the opposing surface (616) of the cover portion (61) and the periphery of the substrate (9) is, for example, 0.5 mm to 1 mm. The said gap may be appropriately changed according to the magnitude of the surface tension of the etching solution described later. An arm is connected to the cover member (6), and due to the movement of the arm by a mechanism having a motor or the like, the cover member (6) can move, for example, in the up and down direction and in the diameter direction.

[0034] As shown in FIGS. 3 and 4, the liquid introduction section (62) is tubular in shape and extends outward in the radial direction from the upstream end (611) of the cover section (61). One end of the liquid introduction section (62) is open at the opposite surface (616) of the cover section (61) and connected to the gap space (G). Etching liquid is supplied from the liquid supply section (5) to the other end of the liquid introduction section (62). Accordingly, the etching liquid (71) is injected into the gap space (G), and the gap space (G) becomes filled with the etching liquid (71) (liquid-packed state). In other words, the etching liquid (71) is supplied to the periphery of the substrate (9) through the cover member (6) by the liquid supply section (5). As previously described, each part of the main portion of the substrate (9) enters the cover portion (61) (gap space (G)) from the upstream end (611), that is, the opening side of the liquid introduction portion (62).

[0035] Here, the etching solution (71) supplied by the liquid supply unit (5) is a chlorine-based electrolyte and contains 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 said solute is, for example, 0.7 wt% or more, and preferably 1.8 wt% or more. The upper limit of the concentration of said solute is not particularly limited, but is, for example, 3.6 wt%. The etching solution (71) may contain a surfactant. An example of a surfactant is ethanol or isopropyl alcohol (IPA), etc. Also, for reasons described later, the etching solution (71) does not contain an oxidizing agent. The oxidizing agent in this specification is one that reacts with ruthenium to produce ruthenium oxide.

[0036] The cover portion (61) shown in FIG. 5 is formed by a material (e.g., quartz glass, etc.) that is transparent to laser light (L1, L2) from the light irradiation portion (4). Additionally, the etching solution (71) is also transparent to laser light (L1, L2). Laser light (L1, L2) is irradiated onto the periphery of the substrate (9) through the downstream end (612) of the cover portion (61) and the etching solution (71) in the gap space (G). In the cross-section of the substrate (9) shown in FIG. 5, the irradiation range of the laser light (L1) is extended from the edge cross-section of the substrate (9) to a region near the bevel portion on the upper surface (91). Additionally, the irradiation range of the laser light (L2) extends from the edge cross-section of the substrate (9) to the area near the bevel portion on the lower surface (92). At the edge cross-section, the irradiation range of the laser light (L1) and the irradiation range of the laser light (L2) overlap. Therefore, in the cross-section of the substrate (9), the range from the area near the bevel portion on the upper surface (91) through the edge cross-section to the area near the bevel portion on the lower surface (92), that is, the entire peripheral portion of the said cross-section, is included in the irradiation range of the laser light (L1, L2).

[0037] In the processing described below, the portion of the ruthenium-containing layer (93) on the substrate (9) that is irradiated with laser light is etched. Therefore, in the periphery of the substrate (9), if the ruthenium-containing layer (93) exists only on the upper surface (91) side or the lower surface (92) side, only the laser light (L1, L2) from one side may be used. In the cover member (6), the cover portion (61) and the liquid introduction portion (62) may be integrally formed by the same material, or both may be formed as separate bodies. If the cover portion (61) and the liquid introduction portion (62) are formed as separate bodies, both may be formed by different materials.

[0038] Next, the processing flow of the substrate (9) in the substrate processing device (1) will be explained with reference to FIG. 6. When the substrate (9) is processed, first, the substrate (9) is introduced into the substrate processing device (1) and is held approximately horizontally by the substrate holding part (21) (step S11). Accordingly, 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) and the central axis (J1) coincide when viewed from a plane. When the substrate (9) is introduced, the supply head (3) and the cover member (6) are placed in a retractable position that does not hinder the entry and exit of the substrate (9) (for example, a position separated radially outward from the substrate (9) when viewed from a plane). When the substrate (9) is held by the substrate holding part (21), rotation of the substrate (9) by the substrate rotation mechanism (22) is initiated. Additionally, the cover member (6) is moved from the retracted position described above to the position shown in FIG. 2, and a gap space (G) is formed between the opposing surface (616) of the cover part (61) and the peripheral part of the substrate (9).

[0039] Subsequently, the control unit (8) controls the liquid supply unit (5), thereby initiating the introduction of the etching liquid (71) into the liquid introduction unit (62) of the cover member (6), and the etching liquid (71) is supplied to the gap space (G) at the upstream end (611) of the cover part (61). The etching liquid (71) in the gap space (G) is transported to the downstream side in the direction of movement of the periphery by the rotation of the substrate (9), and is discharged to the outside of the gap space (G) at the downstream side of the downstream end (612) of the cover part (61). The discharged etching liquid (71) is shaken off by centrifugal force and scattered outward in the radial direction from the periphery of the substrate (9). In reality, the liquid supply unit (5) continuously supplies the etching solution (71) to the gap space (G), thereby maintaining the state in which the gap space (G) is filled with the etching solution (71). In this way, the etching solution (71) comes into contact with the ruthenium-containing layer (93) on the periphery of the substrate (9) (step S12). Furthermore, the etching of the ruthenium-containing layer (93) hardly proceeds with only the contact of the etching solution (71).

[0040] At this time, due to the centrifugal force resulting from the rotation of the substrate (9), the etching liquid (71) attached to the periphery is suppressed from flowing inward in the radial direction. Additionally, the range in which the etching liquid (71) spreads in the circumferential direction centered on the central axis (J1) is approximately limited to the range of the periphery facing the cover portion (61). In the substrate processing device (1), an inert gas (e.g., nitrogen gas) may be ejected from the supply head (3) positioned at the location of FIG. 2 toward the center of the substrate (9), and the etching liquid (71) attached to the periphery may be more reliably suppressed from flowing inward in the radial direction. Additionally, the rotation speed of the substrate (9) may be appropriately changed within a range where it is possible to fill the gap space (G) with the etching liquid (71).

[0041] Subsequently, by the control unit (8) controlling the light irradiation unit (4), laser light (L1, L2) from the light irradiation unit (4) is continuously irradiated onto the periphery of the substrate (9) through the downstream end (612) of the cover unit (61) and the etching solution (71) of the gap space (G) (Step S13). In other words, laser light (L1, L2) is irradiated onto the ruthenium-containing layer (93) that is in contact with the etching solution (71). At this time, as the substrate (9) rotates, the area in the periphery of the substrate (9) that is in contact with the etching solution (71) and is also irradiated by laser light (L1, L2) is switched sequentially along the circumferential direction. The irradiation of the laser light (L1, L2) may be intermittent (pulse irradiation).

[0042] FIG. 7 is a cross-sectional view showing a part of the substrate (9). In the example of FIG. 7, a diffusion barrier film (94), etc. is formed between the ruthenium-containing layer (93) and the main body of the substrate (9). As previously described, laser light (L1, L2) is an excitation light that excites ruthenium, and due to the photoelectric effect caused by irradiation of laser light (L1, L2), photoelectrons (e) from the surface of ruthenium contained in the ruthenium-containing layer (93) are produced, as shown in FIG. 7. － ) is emitted, and holes (h ＋ ) is formed. Then, the etching solution (71) reacts with the hole, and the etching of the ruthenium-containing layer (93) proceeds.

[0043] Although the chemical reaction involved in the etching of the ruthenium-containing layer (93) is not necessarily clear,

[0044] Ru + HCl + h ＋ →(Ru(III)-Cl(aq))+H ＋ ··· (1)

[0045] 2H ＋ +2e － →H2··· (2)

[0046] It is assumed that the reaction represented by [formula] has occurred. In the above chemical reaction equation (1), (Ru(III)-Cl(aq)) represents a water-soluble compound containing ruthenium and chlorine (hereinafter referred to as the "Ru-Cl water-soluble compound"). The Ru-Cl water-soluble compound is RuCl 2＋ , RuCl2 ＋ , RuCl3, RuCl4 － It is the back.

[0047] The reaction product, a Ru-Cl water-soluble compound, is dissolved in the etching solution (71) and removed from the substrate (9) along with the etching solution (71). Accordingly, the product containing ruthenium and chlorine is suppressed from remaining on the surface of the substrate (9). Typically, the Ru-Cl water-soluble compound is non-toxic. Also, since the etching solution (71) does not contain an oxidizing agent, gaseous ruthenium tetroxide (RuO4) is not produced. If an etching solution containing an oxidizing agent such as sodium hypochlorite is used, a layer of ruthenium dioxide (RuO2) is formed on the surface of the ruthenium-containing layer (93), and the etching rate is significantly reduced or the etching becomes insufficient. On the other hand, in the above etching solution (71) which does not contain hypochlorous acid and salts of hypochlorous acid, the formation of a layer of ruthenium dioxide is suppressed or prevented.

[0048] In addition, in this embodiment, the etching solution (71) contains a surfactant (here, ethanol), thereby suppressing or preventing large irregularities from occurring on the surface of the ruthenium-containing layer (93) after etching. Although the reason is not necessarily clear, it is thought that in an etching solution (71) that does not contain a surfactant, the generated hydrogen gas (H2) (see chemical reaction equation (2) above) remains (exists) as bubbles on the surface of the ruthenium-containing layer (93), thereby hindering the progress of etching of ruthenium, whereas in an etching solution (71) in which the surface tension is lowered due to the presence of a surfactant, the retention of hydrogen bubbles is suppressed.

[0049] Typically, holes (h) on the surface of ruthenium ＋ In order to form ), photon energy greater than the work function of ruthenium (4.71 eV) is required, and in this case, the wavelength of light irradiated onto ruthenium is required to be less than 264 nm. Meanwhile, as described in “The Photoelectric Effect at the Metal-Electrolyte Boundary” by LI Korshunov et al. (Russian Chemical Reviews, 1971, Vol. 40, No. 8, pp. 699-714) (Ibid. 3), it is known that when a polar solution covers the surface of a material, 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), photoelectrons are emitted from the surface of ruthenium even when the wavelength of the laser light (L1, L2) from the light irradiation unit (4) is 264 nm or greater. In terms of forming holes more reliably on the surface of the ruthenium-containing layer (93), it is preferable that the wavelength of the laser light (L1, L2) be 270 nm or less, and more preferable that it be less than 264 nm.

[0050] When a predetermined time has elapsed since the start of irradiation of laser light (L1, L2) (excitation light) on the periphery of the substrate (9), the supply of etching solution (71) to the periphery and the irradiation of laser light (L1, L2) are stopped. Accordingly, the etching of the ruthenium-containing layer (93) is stopped. After that, the cover member (6) moves from the position shown in FIG. 2 to the retraction position described above. In addition, a camera or the like that captures the periphery of the substrate (9) may be formed, and the end point of the etching on the periphery may be automatically detected based on the captured image (the same applies hereinafter).

[0051] Next, the supply head (3) is positioned at the location shown in FIG. 2 (it may be positioned in advance), and rinse liquid is supplied from the center nozzle (33) to the center of the upper surface (91) of the substrate (9). Additionally, the rotation speed of the substrate (9) by the substrate rotation mechanism (22) is increased. Accordingly, the rinse liquid spreads over the entire upper surface (91) of the substrate (9), and a rinse treatment is performed to wash away the etching liquid (71) attached to the periphery of the substrate (9) (Step S14). The rinse liquid is scattered outward in the radial direction from the periphery of the substrate (9) by the centrifugal force resulting from the rotation of the substrate (9), and is recovered by the waste liquid recovery unit (12).

[0052] When the rinsing treatment on the substrate (9) is performed for a predetermined time, the supply of rinsing liquid from the center nozzle (33) is stopped. After that, the rotation speed of the substrate (9) is further increased, and the rinsing liquid on the substrate (9) is shaken off and removed. That is, the drying treatment of the substrate (9) is performed (step S15). When the drying treatment of the substrate (9) is finished, the rotation of the substrate (9) is stopped, and the substrate (9) is removed from the substrate processing device (1). Also, the rinsing treatment and drying treatment of the substrate (9) may be performed by a method different from the example described above.

[0053] FIG. 8 is a diagram showing the configuration of a substrate processing device (1a) related to a second embodiment. In the substrate processing device (1a), the cover member (6) is omitted compared to the substrate processing device (1) of FIG. 2. Additionally, a liquid supply unit (5) is connected to the center nozzle (33) of the supply head (3), and an etching liquid (71) and a rinse liquid are selectively discharged from the center nozzle (33). Other configurations of the substrate processing device (1a) are the same as those of the substrate processing device (1), and the same reference numerals are used for the same configurations.

[0054] In this embodiment, a ruthenium-containing layer (93) is formed over the entire upper surface (91) of the substrate (9), and a protective film (97) is formed on the ruthenium-containing layer (93). The protective film (97) is, for example, a spin-on-glass (SOG) film and is formed over the entire area of ​​the upper surface (91) of the substrate (9), excluding the periphery. The shape of the protective film (97) when viewed from a planar view is approximately circular.

[0055] The processing flow of the substrate (9) in the substrate processing device (1a) is the same as that shown in FIG. 6, except that steps S21 and S22 shown in FIG. 9 are performed between the rinse treatment (step S14) and the drying treatment (step S15) described above. Specifically, first, the substrate (9) having the protective film (97) described above formed on the ruthenium-containing layer (93) is prepared by being held in the substrate holding part (21) (Fig. 6: step S11). In addition, the rotation of the substrate (9) is initiated by the substrate rotation mechanism (22).

[0056] Subsequently, the control unit (8) controls the liquid supply unit (5), so that the etching liquid (71) is continuously discharged from the center nozzle (33) of the supply head (3) toward the center of the upper surface (91) of the substrate (9). The etching liquid (71) spreads outward in the radial direction on the protective film (97) by the centrifugal force due to the rotation of the substrate (9), and comes into contact with the ruthenium-containing layer (93) exposed from the protective film (97) at the periphery of the substrate (9) (Step S12). The etching liquid (71) also flows back toward the lower surface (92) of the substrate (9), so that almost the entire periphery is covered with the etching liquid (71). Additionally, by the control unit (8) controlling the light irradiation unit (4), laser light (L1, L2) from the light irradiation unit (4) is irradiated onto the periphery of the substrate (9) through the etching solution (71) (Step S13). Accordingly, a hole is formed on the surface of the ruthenium contained in the ruthenium-containing layer (93), and the etching solution (71) reacts with the hole, thereby etching the ruthenium-containing layer (93). At this time, the area of ​​the ruthenium-containing layer (93) covered by the protective film (97) is not etched.

[0057] When a predetermined time has elapsed since the start of irradiation of the laser light (L1, L2) on the periphery of the substrate (9), the supply of the etching solution (71) and the irradiation of the laser light (L1, L2) are stopped. Accordingly, the etching of the ruthenium-containing layer (93) is stopped. Subsequently, as the rinsing solution is supplied to the central part of the substrate (9) from the center nozzle (33), the rotation speed of the substrate (9) by the substrate rotation mechanism (22) is increased, and a rinsing treatment is performed (step S14).

[0058] When the rinsing treatment on the substrate (9) is 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) (Fig. 9: Step S21). As described above, if the protective film (97) is an SOG film, in Step S21, for example, hydrogen fluoride (HF) is supplied to the protective film (97) to remove the protective film (97). The hydrogen fluoride may be discharged from the center nozzle (33) or from a dedicated nozzle. Also, the type of the protective film (97) and the method of removing the protective film (97) may be changed in various ways.

[0059] When the removal of the protective film (97) is finished, a rinse liquid is supplied from the center nozzle (33) to the center of the substrate (9) and the rinsing treatment of the substrate (9) is performed (step S22). After that, the rotation speed of the substrate (9) is increased and the drying treatment of the substrate (9) is performed (Fig. 6: step S15). When the drying treatment of the substrate (9) is finished, the rotation of the substrate (9) is stopped and the substrate (9) is removed from the substrate processing device (1a).

[0060] As described above, the substrate processing method related to the first and second embodiments comprises a process (step S11) of preparing a substrate (9) having a ruthenium-containing layer (93) formed on its surface, a process (step S12) of contacting an etching solution (71) containing chlorine and water and not containing an oxidizing agent with the ruthenium-containing layer (93) on the substrate (9), and a process (step S13) of irradiating an excitation light that excites ruthenium onto the ruthenium-containing layer (93) to which the etching solution (71) is in contact. Accordingly, a layer of ruthenium tetroxide in a toxic gaseous state or ruthenium dioxide that is difficult to etch is not formed, and the ruthenium-containing layer (93) can be properly etched.

[0061] In the first and second embodiments above, in step S12, the etching solution (71) comes into contact with the periphery of the substrate (9), and in step S13, excitation light is irradiated onto the periphery. Accordingly, only the ruthenium-containing layer (93) of the periphery can be properly etched (i.e., without the ruthenium-containing layer (93) outside the periphery being etched).

[0062] Preferably, in step S13, a water-soluble compound containing ruthenium and chlorine is produced. Accordingly, the product can be excluded from the substrate (9) along with the etching solution (71) and discharged outside the housing (11). As a result, the ruthenium-containing product is prevented from remaining on the substrate (9) and within the housing (11), thereby more effectively preventing or suppressing the generation of ruthenium tetroxide.

[0063] Preferably, the etching solution (71) contains a surfactant. Accordingly, the surface irregularities after etching can be reduced, that is, uniform etching can be achieved.

[0064] Preferably, the wavelength of the excitation light is 270 nm or less. Accordingly, the ruthenium-containing layer (93) can be etched more effectively. Also, if it is possible to excite ruthenium, the wavelength of the excitation light may be greater than 270 nm.

[0065] A substrate processing apparatus (1) related to the first and second embodiments comprises a substrate holding portion (21) that holds a substrate (9) having a ruthenium-containing layer (93) formed on its surface, a liquid supply portion (5) that supplies an etching solution (71) containing chlorine and water and not containing an oxidizing agent onto the substrate (9) to bring it into contact with the ruthenium-containing layer (93), and a light irradiation portion (4) that irradiates an excitation light to excite ruthenium to the ruthenium-containing layer (93) to which the etching solution (71) is in contact. Accordingly, gaseous ruthenium tetroxide, etc., is not generated, and the ruthenium-containing layer (93) can be properly etched.

[0066] FIG. 10 is a diagram showing the configuration of a substrate processing device (1b) related to a third embodiment. The substrate processing device (1b) is a device that performs wet etching on the wiring portion of the upper surface (91) of a substrate (9). In the substrate processing device (1b), compared to the substrate processing device (1) of FIG. 2, the cover member (6) is omitted, and a liquid supply unit (5) (not shown) is connected to the center nozzle (33) of the supply head (3). Additionally, a light irradiation unit (4a) is positioned above the housing (11), and an irradiation unit moving mechanism (49) for moving the light irradiation unit (4a) is formed. Other configurations of the substrate processing device (1b) are the same as those of the substrate processing device (1), and the same reference numerals are used for the same configurations.

[0067] The light irradiation unit (4a) includes a light source and an optical system and emits light that excites ruthenium (i.e., excitation light). A window unit (112) is formed on the upper surface of the housing (11), and the window unit (112) is formed by a material (e.g., quartz glass, etc.) that is transparent to light from the light irradiation unit (4a). The light is incident into the housing (11) through the window unit (112) and is irradiated onto an area of ​​a predetermined size on the upper surface (91) of the substrate (9) held in the substrate holding unit (21). The irradiation unit movement mechanism (49) has a motor or the like as a driving source and can move the light irradiation unit (4a) in two directions that are nearly parallel to the upper surface (91) and also intersect each other. Accordingly, as shown in FIG. 11, light from the light irradiation unit (4a) is irradiated to each of the plurality of divided regions (911) that divide the upper surface (91) of the substrate (9).

[0068] FIGS. 12a and 12b are cross-sectional views showing a ruthenium-containing layer (93) formed on the upper surface (91) of a substrate (9). An insulating film (95) is formed on the substrate (9), and a wiring section (96), which is a wiring pattern, is formed within the insulating film (95). Between the wiring section (96) and the insulating film (95), a diffusion barrier film (94), formed, for example, by tantalum nitride (TaN), is formed. In the example on the left side of FIG. 12a, the main body (wiring main body) of the wiring section (96) is the ruthenium-containing layer (93). In the example on the left side of FIG. 12b, the main body of the wiring part (96) is a metal part (961) formed by copper (Cu), etc., and the metal film (e.g., liner film) covering the side and bottom surfaces of the metal part (961) is a ruthenium-containing layer (93).

[0069] Next, the processing flow of the substrate (9) in the substrate processing device (1b) will be explained in accordance with FIG. 6. First, a substrate (9) having a ruthenium-containing layer (93) on its upper surface (91) is held in the substrate holding part (21) and prepared (Step S11). Subsequently, an etching solution (71) is discharged from the center nozzle (33) of the supply head (3) toward the center of the upper surface (91) of the substrate (9) for a certain period of time, and then the discharge of the etching solution (71) is stopped. Accordingly, a puddle (a liquid film of the etching solution (71)) of the etching solution (71) is formed on the upper surface (91) of the substrate (9) which is held in a horizontal state, and the state in which the etching solution (71) is in contact with the ruthenium-containing layer (93) of the upper surface (91) is maintained (Step S12). Typically, the puddles of the etching solution (71) cover the entire upper surface (91). In forming the puddles of the etching solution (71), the substrate (9) may be rotated at a low speed.

[0070] After the supply head (3) moves to the withdrawal position and the rotation of the substrate (9) is stopped, light is sequentially irradiated from the light irradiation unit (4a) onto a plurality of divided regions (911) (step S13). That is, excitation light is irradiated onto the ruthenium-containing layer (93) in contact with the etching solution (71). Accordingly, a hole is formed on the surface of the ruthenium contained in the ruthenium-containing layer (93), and the etching solution (71) reacts with the hole, and the etching of the ruthenium-containing layer (93) proceeds. In the example on the right side of FIG. 12a, the ruthenium-containing layer (93) is etched, and a recess is formed. In the example on the right side of FIG. 12b, the metal part (961) and the ruthenium-containing layer (93) are etched, and a recess is formed.

[0071] When the irradiation of the excitation light on the plurality of divided regions (911) is performed a predetermined number of times, the supply head (3) returns to the position shown in FIG. 10, and a rinse liquid is supplied to the center of the substrate (9) from the center nozzle (33). In addition, the rotation of the substrate (9) is initiated by the substrate rotation mechanism (22). Accordingly, a rinse treatment is performed to wash away the etching liquid (71), etc., on the substrate (9) (step S14).

[0072] In the processing of the substrate (9) in the substrate processing device (1b), after the rinsing process, it is preferable that an organic solvent such as IPA be supplied from the center nozzle (33) to the center of the upper surface (91) of the substrate (9). By replacing the rinsing liquid with an organic solvent having low surface tension in this way, the collapse of the pattern during the drying of the substrate (9) is prevented. After the supply of the organic solvent from the center nozzle (33) is stopped, the rotation speed of the substrate (9) is further increased, and the drying process of the substrate (9) is performed (step S15). When the drying process of the substrate (9) is finished, the rotation of the substrate (9) is stopped, and the substrate (9) is removed from the substrate processing device (1).

[0073] As described above, the substrate processing method related to the third embodiment comprises a process (step S11) of preparing a substrate (9) having a ruthenium-containing layer (93) formed on its surface, a process (step S12) of contacting an etching solution (71) containing chlorine and water and not containing an oxidizing agent with the ruthenium-containing layer (93) on the substrate (9), and a process (step S13) of irradiating an excitation light that excites ruthenium onto the ruthenium-containing layer (93) to which the etching solution (71) is in contact. Accordingly, gaseous ruthenium tetroxide, etc., is not generated, and the ruthenium-containing layer (93) can be properly etched.

[0074] In the above third embodiment, a ruthenium-containing layer (93) is formed on the upper surface (91) of the substrate (9). Then, in step S12, a pudding of the etching solution (71) is formed on the upper surface (91) of the substrate (9), and in step S13, excitation light is irradiated onto the upper surface (91). Accordingly, the ruthenium-containing layer (93) included in the wiring portion (96) of the upper surface (91) can be appropriately etched. Of course, excitation light may also be irradiated onto the peripheral portion of the substrate (9) so that the ruthenium-containing layer (93) of the peripheral portion is etched.

[0075] However, if the above recess is formed by dry etching, etching residues (side effects) may occur along the sides due to its anisotropy. In contrast, since isotropic wet etching is performed in the above substrate processing method, the occurrence of etching residues is suppressed, in other words, uniformity of the etching depth can be secured.

[0076] Various variations are possible in the above substrate processing method and substrate processing apparatus (1, 1a, 1b).

[0077] Depending on the type of etching solution (71), the product generated in step S13 may be other than a water-soluble compound containing ruthenium and chlorine. Additionally, the etching solution (71) may not contain a surfactant.

[0078] In a substrate processing apparatus (1, 1a) for etching a ruthenium-containing layer (93) on the periphery of a substrate (9), a nozzle may be formed on the side or lower surface (92) of the substrate (9), and an etching solution may be supplied to the periphery from the nozzle. Additionally, the substrate (9) may be held in a substrate holding portion (21) while the main surface on which the ruthenium-containing layer (93) is formed faces downward.

[0079] In a substrate processing device (1, 1a), a plurality of cover members (6) may be arranged in a circumferential direction, and in each cover member (6), the supply of an etching solution (71) to the peripheral portion of a substrate (9) and the irradiation of an excitation light may be performed. Additionally, as shown in FIG. 10, the light irradiation unit (4a) may move so that the excitation light is irradiated to the peripheral portion of a stationary substrate (9).

[0080] In a substrate processing apparatus (1b) for etching a ruthenium-containing layer (93) on the upper surface (91) of a substrate (9), for example, a light irradiation unit is formed to irradiate excitation light in a linear region extending outward in the radial direction from the central part of the substrate (9), and by rotating the substrate (9), excitation light may be irradiated over almost the entire upper surface (91). In this case, an etching solution (71) may be continuously supplied to the upper surface (91) of the substrate (9).

[0081] In the substrate processing apparatus (1, 1a, 1b), a heater for heating the etching solution (71) may be formed. An example of said heater is an electric heater positioned below the periphery of the substrate (9) and facing the lower surface (92) of the substrate (9).

[0082] In the substrate processing apparatus (1, 1a, 1b), the substrate on which processing is performed is not limited to a semiconductor substrate, but may be a glass substrate or other substrate. In addition, the shape of the substrate may be other than a disc shape.

[0083] The configurations in the above embodiments and each variant may be appropriately combined as long as they do not contradict each other.

[0084] Although the invention has been described in detail, the description provided is illustrative and not limiting. Therefore, it can be said that numerous modifications or embodiments are possible without departing from the scope of the invention. Explanation of the symbols

[0085] 1, 1a, 1b: Substrate processing device 4, 4a: Light irradiation section 5 : Liquid supply unit 9 : Substrate 21: Substrate holding part 71 : Etching solution 91 : Upper surface (of the substrate) 93: Ruthenium-containing layer S11 ~ S15, S21, S22 : Step

Claims

Claim 1 A substrate treatment method comprising: a) a step of preparing a substrate having a ruthenium-containing layer formed on its surface; b) a step of contacting an etching solution containing chlorine and water and not containing an oxidizing agent with the ruthenium-containing layer on the substrate; and c) a step of irradiating an excitation light that excites ruthenium to the ruthenium-containing layer in contact with the etching solution, wherein the etching solution contains a surfactant that lowers the surface tension of the etching solution. Claim 2 A substrate treatment method according to claim 1, wherein in process c) above, a water-soluble compound containing ruthenium and chlorine is produced. Claim 3 delete Claim 4 A substrate processing method according to claim 1, wherein the wavelength of the excitation light is 270 nm or less. Claim 5 A substrate processing method according to any one of claims 1, 2 and 4, wherein in process b) the etching solution contacts the peripheral portion of the substrate, and in process c) the excitation light is irradiated onto the peripheral portion. Claim 6 A substrate processing method according to any one of claims 1, 2 and 4, wherein the ruthenium-containing layer is formed on one main surface of the substrate, wherein in process b), a pudding of the etching solution is formed on the main surface of the substrate, and wherein in process c), the excitation light is irradiated on the main surface. Claim 7 A substrate processing apparatus comprising: a substrate holding unit for holding a substrate having a ruthenium-containing layer formed on its surface; a liquid supply unit for supplying an etching solution containing chlorine and water and not containing an oxidizing agent onto the substrate to bring it into contact with the ruthenium-containing layer; and a light irradiation unit for irradiating an excitation light that excites ruthenium to the ruthenium-containing layer in contact with the etching solution, wherein the etching solution contains a surfactant that lowers the surface tension of the etching solution. Claim 8 A substrate treatment method according to any one of claims 1, 2 and 4, wherein the surfactant is ethanol or isopropyl alcohol. Claim 9 In claim 7, the above surfactant is a substrate processing device in which ethanol or isopropyl alcohol is used.

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