Substrate processing apparatus and substrate processing method

Abstract

A substrate processing apparatus comprising a processing tank, a discharge port group, an overflow tank, a circulation flow path, a liquid feed unit, a first gas supply unit, a second gas supply unit, a first adjustment unit, a second adjustment unit, and a control unit. The processing tank performs etching processing by immersing a substrate having a metal film in a processing liquid. The discharge port group discharges the processing liquid into the processing tank. The liquid feed unit feeds the processing liquid stored in the overflow tank to the circulation flow path. The first gas supply unit discharges a gas into the processing tank. The second gas supply unit discharges a gas into the overflow tank. The control unit adjusts at least one of the flow rate of the processing liquid discharged from the discharge port group, the flow rate of the gas discharged from the first gas supply unit, and the flow rate of the gas discharged from the second gas supply unit, to thereby adjust the concentration of an intermediate on the surface of the substrate, the intermediate contributing to the reaction of the metal film.

Description

[Technical Field]

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

[0002] BACKGROUND ART Conventionally, a technique for etching a metal film formed on a substrate such as a semiconductor wafer (hereinafter also referred to as a wafer) has been known (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-180253 Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides a technique that can improve the controllability of the etching rate of a metal film. [Means for solving the problem]

[0005] A substrate processing apparatus according to one aspect of the present disclosure includes a processing tank, a discharge port group, an overflow tank, a circulation flow path, a liquid delivery unit, a first gas supply unit, a second gas supply unit, a first adjustment unit, a second adjustment unit, and a control unit. The processing tank performs an etching process by immersing a substrate having a metal film in a processing liquid. The discharge port group is located below the substrate inside the processing tank and discharges the processing liquid into the processing tank. The overflow tank stores the processing liquid that overflows from the processing tank. The circulation flow path connects the overflow tank and the discharge port group. The liquid delivery unit sends the processing liquid stored in the overflow tank to the circulation flow path. The first gas supply unit is located below the substrate inside the processing tank and discharges gas into the processing tank. The second gas supply unit is located inside the overflow tank and discharges gas into the overflow tank. The first adjustment unit adjusts the flow rate of the gas discharged from the first gas supply unit. The second adjustment unit adjusts the flow rate of the gas discharged from the second gas supply unit. The control unit controls the liquid delivery unit, the first adjustment unit, and the second adjustment unit to adjust at least one of the flow rate of the processing liquid discharged from the discharge port group, the flow rate of the gas discharged from the first gas supply unit, and the flow rate of the gas discharged from the second gas supply unit, thereby performing a concentration adjustment process to adjust the concentration on the surface of the substrate of an intermediate that contributes to the reaction of the metal film. [Effects of the Invention]

[0006] According to the present disclosure, it is possible to improve the controllability of the etching rate of a metal film. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram showing an example of substrate processing. [Figure 2] FIG. 2 is a diagram showing an example of substrate processing. [Figure 3] FIG. 3 is a diagram showing an example of how nitric acid consumed by the oxidation reaction of the molybdenum film is regenerated. [Figure 4] FIG. 4 is a diagram showing the configuration of the substrate processing apparatus according to the first embodiment. [Figure 5]FIG. 5 is a diagram showing the configuration of a processing liquid supply unit according to the first embodiment. [Figure 6] FIG. 6 is a diagram showing the first gas supply unit and the second gas supply unit according to the first embodiment as viewed from above. [Figure 7] FIG. 7 is a flowchart showing the procedure of processing executed by the substrate processing apparatus according to the embodiment. [Figure 8] FIG. 8 is an explanatory diagram of the density adjustment process according to the embodiment. [Figure 9] FIG. 9 is an explanatory diagram of the density adjustment process according to the first modification of the embodiment. [Figure 10] FIG. 10 is an explanatory diagram of the density adjustment process according to the second modification of the embodiment. [Figure 11] FIG. 11 is an explanatory diagram of the density adjustment process according to the third modification of the embodiment. [Figure 12] FIG. 12 is an explanatory diagram of the density adjustment process according to the fourth modification of the embodiment. [Figure 13] FIG. 13 is an explanatory diagram of the density adjustment process according to the fifth modification of the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, embodiments (hereinafter referred to as "embodiments") for carrying out a substrate processing apparatus and a substrate processing method according to the present disclosure will be described in detail with reference to the drawings. Note that the present disclosure is not limited to these embodiments. Furthermore, the embodiments can be appropriately combined within the scope of not causing any contradiction in the processing content. Furthermore, the same components in the following embodiments will be given the same reference numerals, and redundant explanations will be omitted.

[0009] Furthermore, in the following embodiments, expressions such as "constant," "orthogonal," "perpendicular," or "parallel" may be used, but these expressions do not necessarily mean "constant," "orthogonal," "perpendicular," or "parallel" in the strict sense. In other words, the above expressions allow for deviations due to, for example, manufacturing precision, installation precision, etc.

[0010] In addition, for ease of understanding, the drawings referred to below may show an orthogonal coordinate system in which the X-axis, Y-axis, and Z-axis directions are defined as being orthogonal to each other, with the positive Z-axis direction being the vertically upward direction. Also, the direction of rotation around the vertical axis may be referred to as the θ direction.

[0011] <About substrate processing> First, an example of substrate processing according to the present disclosure will be described with reference to Figures 1 and 2. Figures 1 and 2 are diagrams showing an example of substrate processing.

[0012] 1, the substrate processing according to the present disclosure involves etching a semiconductor wafer (hereinafter referred to as wafer W) having a molybdenum film (an example of a metal film) 101 and multiple silicon oxide films 102 formed on a polysilicon film 100. The multiple silicon oxide films 102 are formed in multiple layers on the polysilicon film 100 at intervals from one another. The molybdenum film 101 is formed so as to cover each of the silicon oxide films 102.

[0013] As described above, the wafer W according to the embodiment has a laminated film in which the molybdenum films 101 and the silicon oxide films 102 are alternately stacked, and before the etching process, the silicon oxide films 102 are covered with the molybdenum films 101. The wafer W may have a laminated film including at least the molybdenum film 101, and the configuration of the laminated film is not particularly limited to the example shown in Fig. 1. For example, the laminated film may include a titanium nitride film or a molybdenum nitride film between the molybdenum film 101 and the silicon oxide film 102.

[0014] Furthermore, a plurality of grooves 103 are formed in the wafer W so that a processing liquid (etchant) can penetrate therein and etch the deposited molybdenum film 101. Note that only one groove 103 is shown in FIG.

[0015] In the substrate processing according to the embodiment, the molybdenum film 101 of the wafer W is etched to expose a portion (edge) of the silicon oxide film 102 from the molybdenum film 101, as shown in Figure 2. A processing liquid containing at least nitric acid (HNO), phosphoric acid (HPO), and water (H0) as components is used as the processing liquid for etching the molybdenum film 101. The processing liquid may further contain acetic acid (CHCOOH).

[0016] The etching mechanism of the molybdenum film 101 proceeds as follows: First, as shown in chemical reaction formula (1), nitric acid (HNO3) in the processing solution oxidizes molybdenum to produce molybdic acid (H2MoO4) (oxidation reaction of the molybdenum film 101).

[0017] Mo+2HNO3→H2MoO4+2NO ··· (1)

[0018] Next, as shown in chemical reaction formula (2), molybdic acid (H2MoO4) converts to hydroxide ions (OH - ) As a result, the molybdic acid (H2MoO4) is ionized. In other words, the molybdenum film 101 is dissolved (etched).

[0019] H2MoO4+OH - →HMoO4 - +H2O (2)

[0020] Furthermore, nitric acid (HNO3) consumed by the oxidation reaction of the molybdenum film 101 is regenerated on the surface of the wafer W, as shown in Figure 3. Figure 3 is a diagram showing an example of how nitric acid (HNO3) consumed by the oxidation reaction of the molybdenum film 101 is regenerated. That is, first, nitric oxide (NO) generated together with molybdic acid (H2MoO4) by the oxidation reaction of the molybdenum film 101 reacts with oxygen (O2) dissolved in the processing solution to generate nitrogen dioxide (NO2) as an intermediate. Next, the intermediate nitrogen dioxide (NO2) reacts with water (H2O) in the processing solution to regenerate nitric acid (HNO3) on the surface of the wafer W. A series of reactions related to the regeneration of nitric acid (HNO3) are expressed by chemical reaction formulas (3) and (4).

[0021] 2NO+O2→2NO2 (3) 3NO2+H2O→2HNO3+NO ··· (4)

[0022] Thus, etching of the molybdenum film 101 proceeds through the oxidation and dissolution of the molybdenum film 101. Furthermore, nitric acid (HNO) consumed by the oxidation of the molybdenum film 101 is regenerated by the reaction of nitrogen dioxide (NO), an intermediate, with water (HO) in the treatment solution. Therefore, as the concentration of nitrogen dioxide (NO), an intermediate, in the treatment solution increases, the oxidation of the molybdenum film 101 is accelerated, resulting in an increased etching rate of the molybdenum film 101. On the other hand, as the concentration of nitrogen dioxide (NO), an intermediate, decreases, the oxidation of the molybdenum film 101 is suppressed, resulting in a decreased etching rate of the molybdenum film 101. Based on these mechanisms, the inventors of the present application discovered that the etching rate of the molybdenum film 101 changes in response to changes in the concentration of nitrogen dioxide (NO), an intermediate that contributes to the oxidation of the molybdenum film 101, on the surface of the wafer W.

[0023] Therefore, in the substrate processing apparatus according to the embodiment, the etching rate of the molybdenum film 101 is increased or decreased by adjusting the concentration of nitrogen dioxide (NO2), which is an intermediate in the processing liquid, on the surface of the wafer W.

[0024] In addition, parameters for adjusting the concentration of nitrogen dioxide (NO2) as an intermediate on the surface of the wafer W include the concentration of oxygen (O2) dissolved in the processing liquid, the flow rate of the liquid in the processing tank, etc. These parameters can be adjusted by adjusting at least one of the flow rate of the processing liquid and the flow rate of the gas supplied into the processing tank.

[0025] Therefore, in the substrate processing apparatus according to the embodiment, at least one of the flow rate of the processing liquid and the flow rate of the gas supplied into the processing tank is adjusted to adjust the concentration of nitrogen dioxide (NO2), which is an intermediate, on the surface of the wafer W. This improves the controllability of the etching rate of the molybdenum film 101.

[0026] (Embodiment) <Configuration of the substrate processing apparatus> First, the configuration of the substrate processing apparatus according to the first embodiment will be described with reference to Fig. 4. Fig. 4 is a diagram showing the configuration of the substrate processing apparatus according to the first embodiment.

[0027] 4 immerses a plurality of wafers W held in a vertical position in a processing liquid, thereby simultaneously performing an etching process on the plurality of wafers W. As described above, the etching process uses a processing liquid containing at least nitric acid, phosphoric acid, and water as components, and the molybdenum film 101 is etched by the etching process.

[0028] As shown in FIG. 4, the substrate processing apparatus 1 according to the embodiment includes an inner bath 11, an outer bath 12, a substrate holding unit 20, processing liquid supply units 30_1 to 30_3, a circulation flow path 50, a flow rate adjustment unit 60, a first gas supply unit 70, a second gas supply unit 80, and a control device 90.

[0029] In the following description, when the processing liquid supply units 30_1 to 30_3 are not to be distinguished from one another, they may be simply referred to as processing liquid supply unit 30.

[0030] (Inner tank 11 and outer tank 12) The inner tank 11 is a box-shaped tank with an open top, and stores a processing liquid therein. A lot formed by a plurality of wafers W is immersed in the inner tank 11. In this way, the inner tank 11 corresponds to an example of a processing tank in which a substrate having a metal film is immersed in the processing liquid to perform an etching process.

[0031] The outer tank 12 is disposed around the upper portion of the inner tank 11. The outer tank 12 is open at the top and stores the processing liquid that has overflowed from the inner tank 11. In this way, the outer tank 12 corresponds to an example of an overflow tank that stores the processing liquid that has overflowed from the processing tank.

[0032] A new liquid supply unit for supplying new processing liquid may be connected to the outer tank 12. Also, individual supply units for individually supplying nitric acid, phosphoric acid, and water, which are components of the processing liquid, may be connected to the outer tank 12.

[0033] (Substrate holding part 20) The substrate holding unit 20 holds multiple wafers W in a vertical position (vertical orientation). The substrate holding unit 20 also holds multiple wafers W arranged at regular intervals in the horizontal direction (here, the Y-axis direction). The substrate holding unit 20 is connected to an elevation mechanism (not shown), and can move the multiple wafers W between a processing position inside the inner tank 11 and a standby position above the inner tank 11.

[0034] (Processing liquid supply unit 30) The processing liquid supply unit 30 is disposed inside the inner tank 11 below the plurality of wafers W, and discharges the processing liquid into the inner tank 11.

[0035] Here, the configuration of the processing liquid supply unit 30 will be described with reference to Fig. 5. Fig. 5 is a diagram showing the configuration of the processing liquid supply unit 30 according to the first embodiment.

[0036] 5, the processing liquid supply units 30_1 to 30_3 include nozzles 31_1 to 31_3. The nozzles 31_1 to 31_3 are, for example, cylindrical members and extend along the arrangement direction (Y-axis direction) of the plurality of wafers W. A plurality of discharge ports 32_1 to 32_3 are provided at the top of the nozzles 31_1 to 31_3 along the extension direction of the nozzles 31_1 to 31_3. The discharge ports 32_1 to 32_3 are, for example, circular, and have an opening diameter of, for example, about 0.5 mm to 1.0 mm. The discharge ports 32_1 to 32_3 discharge the processing liquid, for example, vertically upward (positive direction of the Z-axis).

[0037] The nozzles 31_1 to 31_3 are connected to supply paths 52_1 to 52_3, which will be described later, and eject the processing liquid supplied from the supply paths 52_1 to 52_3 from a plurality of ejection ports 32_1 to 32_3.

[0038] (Circulation flow path 50) Returning to Fig. 4, the circulation flow path 50 connects the outer bath 12 and the treatment liquid supply units 30_1 to 30_3. Specifically, the circulation flow path 50 includes a discharge path 51, a plurality of supply paths 52_1 to 52_3, and a bypass path 53. The discharge path 51 is connected to the bottom of the outer bath 12.

[0039] The discharge path 51 is provided with a pump (an example of a liquid delivery unit) 55, a heater 56, and a filter 57. The pump 55 delivers the processing liquid in the outer bath 12 to the circulation path 50 (discharge path 51). The heater 56 heats the processing liquid flowing through the discharge path 51 to a temperature suitable for etching. The filter 57 removes impurities from the processing liquid flowing through the discharge path 51. The discharge path 51 is provided with a filter bypass path 58 that bypasses the filter 57, and the filter bypass path 58 is provided with an on-off valve 59 that switches the open / close state of the filter bypass path 58. The on-off valve 59 is electrically connected to and controlled by a control device 90. The on-off valve 59 switches the open / close state of the filter bypass path 58 to adjust the flow rate of the processing liquid flowing through the circulation path 50 (discharge path 51).

[0040] The pump 55 and the heater 56 are electrically connected to and controlled by the control device 90. The pump 55 can adjust the flow rate of the processing liquid supplied to the processing liquid supply unit 30 under the control of the control device 90. That is, the pump 55 adjusts the flow rate of the processing liquid supplied from the supply paths 52_1 to 52_3 to the processing liquid supply units 30_1 to 30_3 by changing the liquid sending pressure of the pump 55. In this way, the pump 55 adjusts the flow rate of the processing liquid discharged from the plurality of discharge ports 32_1 to 32_3 provided in the processing liquid supply units 30_1 to 30_3.

[0041] A plurality of supply paths 52_1 to 52_3 branch off from the discharge path 51. Of these, the supply path 52_1 is connected to the processing liquid supply unit 30_1, the supply path 52_2 is connected to the processing liquid supply unit 30_2, and the supply path 52_3 is connected to the processing liquid supply unit 30_3.

[0042] The bypass path 53 branches off from the discharge path 51 and is connected to the outer tank 12 .

[0043] (Flow rate adjustment section 60) The flow rate adjusting unit 60 is, for example, an LFC (Liquid Flow Controller), and adjusts the flow rate of the processing liquid supplied to the processing liquid supply units 30_1 to 30_3. That is, the flow rate adjusting unit 60 adjusts the flow rate of the processing liquid discharged from the plurality of discharge ports 32_1 to 32_3 provided in the processing liquid supply units 30_1 to 30_3.

[0044] Specifically, the flow rate adjusting unit 60 is provided in the bypass path 53, and adjusts the flow rate of the processing liquid flowing through the bypass path 53, thereby adjusting the flow rate of the processing liquid supplied from the supply paths 52_1 to 52_3 to the processing liquid supply units 30_1 to 30_3.

[0045] The flow rate adjusting unit 60 is electrically connected to the control device 90 and is controlled by the control device 90.

[0046] (First gas supply unit 70 and second gas supply unit 80) The first gas supply unit 70 is disposed below the plurality of wafers W and the plurality of processing liquid supply units 30_1 to 30_3 inside the inner tank 11. The first gas supply unit 70 includes a plurality of nozzles 71, and discharges gas from the nozzles 71 into the inner tank 11. This allows the first gas supply unit 70 to adjust the flow rate of the processing liquid inside the inner tank 11 and the concentration of oxygen dissolved in the processing liquid.

[0047] The second gas supply unit 80 is disposed inside the outer bath 12. The second gas supply unit 80 includes a plurality of nozzles 81, and discharges gas from the nozzles 81 into the outer bath 12. This allows the second gas supply unit 80 to adjust the concentration of oxygen dissolved in the treatment liquid.

[0048] Here, the configurations of the first gas supply unit 70 and the second gas supply unit 80 will be described with reference to Fig. 6. Fig. 6 is a diagram showing the first gas supply unit 70 and the second gas supply unit 80 according to the first embodiment as viewed from above.

[0049] 6, the plurality of nozzles 71 included in the first gas supply unit 70 are, for example, cylindrical members and extend along the arrangement direction (Y-axis direction) of the plurality of wafers W. A plurality of discharge ports 72 are provided in the upper part of the nozzle 71 along the extension direction of the nozzle 71. Note that the plurality of discharge ports 72 do not necessarily have to be provided in the upper part of the nozzle 71. For example, the plurality of discharge ports 72 may be provided in the lower part of the nozzle 71 and configured to discharge gas obliquely downward.

[0050] The plurality of nozzles 71 are connected to a gas supply source 74a via a flow rate adjuster 73a. The gas supply source 74a supplies gas to the plurality of nozzles 71. Here, nitrogen (N2) gas is supplied from the gas supply source 74a to the plurality of nozzles 71, but the gas supplied from the gas supply source 74a to the plurality of nozzles 71 may be an inert gas other than nitrogen gas, such as a rare gas. As the rare gas, for example, argon (Ar) gas or neon (Ne) gas can be used.

[0051] The flow rate adjusting unit 73a is configured by, for example, an LFC, an on-off valve, or the like, and adjusts the flow rate of the nitrogen gas supplied to the plurality of nozzles 71 from the gas supply source 74a.

[0052] The plurality of nozzles 71 are connected to a gas supply source 74b via a flow rate adjuster 73b. The gas supply source 74b supplies gas to the plurality of nozzles 71. Here, oxygen (O2) gas is supplied from the gas supply source 74b to the plurality of nozzles 71, but the gas supplied from the gas supply source 74b to the plurality of nozzles 71 may be an oxygen-containing gas other than oxygen gas, such as air or ozone (O3) gas.

[0053] The flow rate adjusting unit 73b is configured by, for example, an LFC, an on-off valve, or the like, and adjusts the flow rate of oxygen gas supplied to the plurality of nozzles 71 from the gas supply source 74b.

[0054] In this way, the first gas supply unit 70 can selectively discharge nitrogen gas, which is an inert gas, or oxygen gas, which is an oxygen-containing gas. The flow rate adjusters 73a and 73b can adjust the flow rate of the nitrogen gas or oxygen gas discharged from the first gas supply unit 70. The flow rate adjusters 73a and 73b correspond to an example of a first adjuster that adjusts the flow rate of the gas discharged from the first gas supply unit 70.

[0055] The plurality of nozzles 81 included in the second gas supply unit 80 are, for example, cylindrical members, and extend along the arrangement direction (Y-axis direction) of the plurality of wafers W. A plurality of discharge ports 82 are provided in the upper part of the nozzle 81 along the extension direction of the nozzle 81. Note that the plurality of discharge ports 82 do not necessarily have to be provided in the upper part of the nozzle 81. For example, the plurality of discharge ports 82 may be provided in the lower part of the nozzle 81 and configured to discharge gas obliquely downward.

[0056] The plurality of nozzles 81 are connected to a gas supply source 84a via a flow rate adjuster 83a. The gas supply source 84a supplies gas to the plurality of nozzles 81. Here, nitrogen gas is supplied from the gas supply source 84a to the plurality of nozzles 81, but the gas supplied from the gas supply source 84a to the plurality of nozzles 81 may be an inert gas other than nitrogen gas, such as a rare gas. As the rare gas, for example, argon gas or neon gas can be used.

[0057] The flow rate adjusting unit 83a is configured by, for example, an LFC, an on-off valve, or the like, and adjusts the flow rate of the nitrogen gas supplied to the plurality of nozzles 81 from the gas supply source 84a.

[0058] The plurality of nozzles 81 are connected to a gas supply source 84b via a flow rate adjuster 83b. The gas supply source 84b supplies gas to the plurality of nozzles 81. Here, oxygen gas is supplied from the gas supply source 84b to the plurality of nozzles 81, but the gas supplied from the gas supply source 84b to the plurality of nozzles 81 may be an oxygen-containing gas other than oxygen gas, such as air or ozone gas.

[0059] The flow rate adjusting unit 83b is configured by, for example, an LFC, an on-off valve, or the like, and adjusts the flow rate of oxygen gas supplied to the plurality of nozzles 81 from the gas supply source 84b.

[0060] In this way, the second gas supply unit 80 can selectively discharge nitrogen gas, which is an inert gas, or oxygen gas, which is an oxygen-containing gas. The flow rate adjusters 83a and 83b can adjust the flow rate of the nitrogen gas or oxygen gas discharged from the second gas supply unit 80. The flow rate adjusters 83a and 83b correspond to an example of a second adjuster that adjusts the flow rate of the gas discharged from the second gas supply unit 80.

[0061] (Control device 90) Returning to Fig. 4, the control device 90 is, for example, a computer, and includes a control unit 91 and a storage unit 92. The storage unit 92 is realized by, for example, a semiconductor memory element such as a RAM or a flash memory, or a storage device such as a hard disk or an optical disk, and stores programs that control various processes executed in the substrate processing apparatus 1. The control unit 91 includes a microcomputer having a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), input / output ports, etc., and various circuits, and controls the operation of the substrate processing apparatus 1 by reading and executing the programs stored in the storage unit 92.

[0062] Such a program may be recorded on a computer-readable storage medium and installed from that storage medium into the storage unit 92 of the control device 90. Examples of computer-readable storage media include a hard disk (HD), a flexible disk (FD), a compact disk (CD), a magnetic optical disk (MO), and a memory card.

[0063] (Specific Operation of Substrate Processing Apparatus 1) Next, a specific operation of the substrate processing apparatus 1 according to the embodiment will be described with reference to Fig. 7. Fig. 7 is a flowchart showing the procedure of processes executed by the substrate processing apparatus 1 according to the embodiment. Each process shown in Fig. 7 is executed under the control of a control unit 91.

[0064] 7, in the substrate processing apparatus 1, first, a concentration adjustment process is started (step S101) to adjust the concentration of nitrogen dioxide (NO), an intermediate that contributes to the oxidation reaction of the molybdenum film 101 in the processing liquid stored in the inner tank 11, on the surface of the wafer W. The details of this concentration adjustment process will be described later.

[0065] Next, in the substrate processing apparatus 1, a load process is performed in which the plurality of wafers W are immersed in the inner bath 11 (step S102). In the load process, the control unit 91 controls a lifting mechanism (not shown) provided in the substrate holding unit 20 to lower the substrate holding unit 20, thereby immersing the plurality of wafers W in the processing liquid stored in the inner bath 11.

[0066] Before the start of the loading process, the control unit 91 controls the pump 55 to start supplying the processing liquid from the outer bath 12 to the processing liquid supply units 30_1 to 30_3. Before the start of the loading process, the control unit 91 controls the flow rate adjustment unit 60 to close the bypass path 53. Before the start of the loading process, the control unit 91 controls the on-off valve 59 to close the filter bypass path 58. That is, before the start of the loading process, all of the processing liquid flowing through the circulation flow path 50 is supplied to the processing liquid supply units 30_1 to 30_3.

[0067] Subsequently, an etching process is performed (step S103) in the substrate processing apparatus 1. In the etching process, the plurality of wafers W are immersed in the processing liquid in the inner tank 11 for a predetermined time, thereby etching the molybdenum film 101.

[0068] Thereafter, an unloading process is performed in the substrate processing apparatus 1 (step S104). In the unloading process, the control unit 91 controls a lifting mechanism (not shown) provided in the substrate holding unit 20 to raise the substrate holding unit 20, thereby lifting the plurality of wafers W from the inner bath 11.

[0069] Thereafter, the substrate processing apparatus 1 ends the concentration adjustment process (step S105), and the series of substrate processing operations in the substrate processing apparatus 1 is completed.

[0070] Next, the density adjustment process will be described with reference to Fig. 8. Fig. 8 is an explanatory diagram of the density adjustment process according to the embodiment.

[0071] 8 shows the time variations of the "circulation flow rate," "discharge flow rate (processing liquid)," "inner tank discharge flow rate (gas)," "outer tank discharge flow rate (gas)," "liquid supply pressure," "inner tank valve opening," and "outer tank valve opening" during substrate processing performed by the substrate processing apparatus 1. The "circulation flow rate" refers to the flow rate of the processing liquid flowing through the circulation flow path 50, and the "discharge flow rate (processing liquid)" refers to the flow rate of the processing liquid discharged from the processing liquid supply units 30_1 to 30_3. The "inner tank discharge flow rate (gas)" refers to the flow rate of the gas discharged from the first gas supply unit 70 into the inner tank 11, and the "outer tank discharge flow rate (gas)" refers to the flow rate of the gas discharged from the second gas supply unit 80 into the outer tank 12. The "liquid supply pressure" refers to the liquid supply pressure of the pump 55, i.e., the pressure at which the pump 55 delivers the processing liquid to the circulation flow path 50. Furthermore, the "inner tank valve opening degree" is the opening degree of the on-off valve (solenoid valve) possessed by the flow rate adjustment unit 73a or the flow rate adjustment unit 73b, and the "outer tank valve opening degree" is the opening degree of the on-off valve (solenoid valve) possessed by the flow rate adjustment unit 83a or the flow rate adjustment unit 83b.

[0072] In FIG. 8, the first gas supply unit 70 and the second gas supply unit 80 discharge nitrogen (N2) gas, which is an inert gas.

[0073] The control unit 91 adjusts the liquid sending pressure of the pump 55, the inner tank valve opening of the flow rate adjustment unit 73a, and the outer tank valve opening of the flow rate adjustment unit 83a to adjust the discharge flow rate of the processing liquid supply unit 30, the inner tank discharge flow rate of the first gas supply unit 70, and the outer tank discharge flow rate of the second gas supply unit 80. In this way, the control unit 91 adjusts the concentration of nitrogen dioxide (NO2), which contributes to the reaction of the molybdenum film 101, on the surface of the wafer W.

[0074] 8, the control unit 91 reduces the concentration of nitrogen dioxide on the surface of the wafer W. That is, at time t1 before time t2 at which the loading process is started, the control unit 91 increases the liquid supply pressure of the pump 55 from pressure P0 to pressure P1 (>P0), thereby increasing the discharge flow rates of the processing liquid supply units 30_1 to 30_3 from flow rate F4 to flow rate F5 (>F4). The pressure P0 and the flow rate F4 may be, for example, the liquid supply pressure of the pump 55 and the discharge flow rates of the processing liquid supply units 30_1 to 30_3 used in the previous substrate processing, respectively. The control unit 91 may also further increase the discharge flow rates of the processing liquid supply units 30_1 to 30_3 by controlling the on-off valve 59 to switch the filter bypass path 58 from a closed state to an open state. The control unit 91 can increase the flow rate of the processing liquid in the inner tank 11 by increasing the discharge flow rates of the processing liquid supply units 30_1 to 30_3.

[0075] Furthermore, at time t1, the control unit 91 increases the inner tank valve opening of the flow rate adjustment unit 73a from 0 to opening V1, thereby increasing the inner tank discharge flow rate of the first gas supply unit 70 from 0 to flow rate F7. By increasing the inner tank discharge flow rate of the first gas supply unit 70 to generate bubbling of nitrogen gas in the inner tank 11, the control unit 91 can reduce the concentration of oxygen (O2) dissolved in the treatment liquid in the inner tank 11.

[0076] Furthermore, at time t1, the control unit 91 increases the outer tank valve opening of the flow rate adjustment unit 83a from 0 to opening V2, thereby increasing the outer tank discharge flow rate of the second gas supply unit 80 from 0 to flow rate F8. By increasing the outer tank discharge flow rate of the second gas supply unit 80 to generate bubbling of nitrogen gas in the outer tank 12, the control unit 91 can reduce the concentration of oxygen (O2) dissolved in the treatment liquid in the inner tank 11.

[0077] In this way, in the substrate processing apparatus 1, the flow rate of the processing liquid in the inner bath 11 is increased to diffuse nitrogen dioxide present on the surface of the wafer W. Furthermore, in the substrate processing apparatus 1, the generation of nitrogen dioxide is suppressed by reducing the concentration of oxygen (O2) dissolved in the processing liquid in the inner bath 11 (see chemical reaction formula (3) above). In this way, the control unit 91 can reduce the concentration of nitrogen dioxide, an intermediate that contributes to the oxidation reaction of the molybdenum film 101, on the surface of the wafer W before starting the etching process. This suppresses the oxidation reaction of the molybdenum film 101, thereby reducing the etching rate of the molybdenum film 101. In other words, the substrate processing apparatus 1 according to this embodiment can improve the controllability of the etching rate of the molybdenum film 101.

[0078] Next, the control unit 91 performs a loading process from time t2 to time t3. In the loading process, the control unit 91 controls an elevation mechanism (not shown) of the substrate holding unit 20 to lower the substrate holding unit 20, thereby immersing the wafers W in the processing liquid stored in the inner tank 11. From time t2 to time t3, the control unit 91 reduces the inner tank valve aperture of the flow rate adjuster 73a from aperture V1 to 0, thereby reducing the inner tank discharge flow rate of the first gas supply unit 70 from flow rate F7 to 0. Furthermore, from time t2 to time t3, the control unit 91 reduces the outer tank valve aperture of the flow rate adjuster 83a from aperture V2 to 0, thereby reducing the outer tank discharge flow rate of the second gas supply unit 80 from flow rate F8 to 0.

[0079] In this manner, in the substrate processing apparatus 1, during the period in which the plurality of wafers W are immersed in the processing liquid (the period from time t2 to time t3), the discharge of nitrogen gas from the first gas supply unit 70 and the second gas supply unit 80 is stopped. This temporarily reduces the flow rate of the processing liquid in the inner tank 11, thereby preventing the wafers W from falling off the substrate holder 20.

[0080] Next, at time t3 when the etching process starts, the control unit 91 again increases the inner tank valve aperture of the flow rate adjuster 73a from 0 to aperture V1, thereby again increasing the inner tank discharge flow rate of the first gas supply unit 70 from 0 to a flow rate F7. At time t3, the control unit 91 also again increases the outer tank valve aperture of the flow rate adjuster 83a from 0 to aperture V2, thereby again increasing the outer tank discharge flow rate of the second gas supply unit 80 from 0 to a flow rate F8. This allows the control unit 91 to reduce the concentration of nitrogen dioxide, an intermediate that contributes to the oxidation reaction of the molybdenum film 101, on the surface of the wafer W during the etching process. This suppresses the oxidation reaction of the molybdenum film 101, thereby reducing the etching rate of the molybdenum film 101. That is, the substrate processing apparatus 1 according to this embodiment can improve the controllability of the etching rate of the molybdenum film 101.

[0081] Next, the control unit 91 performs an etching process during the period from time t3 to time t4.

[0082] Next, the control unit 91 performs an unloading process during the period from time t4 to time t5. During the unloading process, the control unit 91 controls an elevation mechanism (not shown) provided in the substrate holding unit 20 to raise the substrate holding unit 20, thereby lifting the wafers W from the processing solution in the inner tank 11. During the period from time t4 to time t5, the control unit 91 reduces the inner tank valve aperture of the flow rate adjuster 73a from aperture V1 to 0, thereby reducing the inner tank discharge flow rate of the first gas supply unit 70 from flow rate F7 to 0. During the period from time t2 to time t3, the control unit 91 reduces the outer tank valve aperture of the flow rate adjuster 83a from aperture V2 to 0, thereby reducing the outer tank discharge flow rate of the second gas supply unit 80 from flow rate F8 to 0.

[0083] Thus, in the substrate processing apparatus 1, during the period of lifting a plurality of wafers W from the processing liquid (the period from time t4 to time t5), the discharge of nitrogen gas from the first gas supply unit 70 and the second gas supply unit 80 is stopped. Thereby, the flow velocity of the liquid flow of the processing liquid in the inner tank 11 can be temporarily decreased, and as a result, it is possible to suppress the wafers W from falling off the substrate holding unit 20.

[0084] Subsequently, when the control unit 91 finishes the unloading process at time t5, it decreases the liquid feed pressure of the pump 55 from pressure P1 to pressure P0 (<P1), thereby decreasing the discharge flow rate of the processing liquid supply units 30_1 to 30_3 from flow rate F5 to flow rate F4 (<F5). Further, the control unit 91 may further decrease the discharge flow rate of the processing liquid supply units 30_1 to 30_3 by controlling the on-off valve 59 to switch the filter bypass path 58 from the open state to the closed state. By decreasing the discharge flow rate of the processing liquid supply units 30_1 to 30_3, the control unit 91 can return the flow velocity of the liquid flow of the processing liquid in the inner tank 11 to the initial flow velocity.

[0085] In the example shown in FIG. 8, the control unit 91 adjusted the concentration of nitrogen dioxide contributing to the reaction of the molybdenum film 101 on the surface of the wafer W by adjusting the discharge flow rate of the processing liquid supply unit 30, the inner tank discharge flow rate of the first gas supply unit 70, and the outer tank discharge flow rate of the second gas supply unit 80. Not limited to this, the control unit 91 may adjust the concentration of nitrogen dioxide on the surface of the wafer W by adjusting at least one of the discharge flow rate of the processing liquid supply unit 30, the inner tank discharge flow rate of the first gas supply unit 70, and the outer tank discharge flow rate of the second gas supply unit 8,0. In this case, the control unit 91 may decrease the concentration of nitrogen dioxide on the surface of the wafer W by performing at least one of the processes of increasing the discharge flow rate of the processing liquid supply unit 30, increasing the inner tank discharge flow rate of the first gas supply unit 70, and increasing the outer tank discharge flow rate of the second gas supply unit 80.

[0086] Next, a modified example of the concentration adjustment process shown in FIG. 8 will be described with reference to FIGS. 9 to 13. FIG. 9 is an explanatory diagram of the concentration adjustment process according to Modified Example 1 of the embodiment. [[ID=*]] [[ID=*]]

[0087] The concentration adjustment process according to Modification 1 differs from the concentration adjustment process shown in FIG. 8 in that the outer tank valve opening of the flow rate adjustment unit 83a is maintained at zero, and the outer tank discharge flow rate of the second gas supply unit 80 is maintained at zero, thereby preventing bubbling of nitrogen gas in the outer tank 12. That is, the control unit 91 increases only the inner tank discharge flow rate of the first gas supply unit 70 to generate only bubbling of nitrogen gas in the inner tank 11. This reduces the degree of decrease in the concentration of oxygen (O2) dissolved in the processing liquid in the inner tank 11 compared to the concentration adjustment process shown in FIG. 8, thereby reducing the degree of decrease in the concentration of nitrogen dioxide on the surface of the wafer W. Therefore, Modification 1 reduces the degree of decrease in the etching rate of the molybdenum film 101 compared to the embodiment.

[0088] FIG. 10 is an explanatory diagram of the density adjustment process according to the second modification of the embodiment.

[0089] The concentration adjustment process according to Modification 2 differs from the concentration adjustment process shown in FIG. 8 in that the inner tank valve opening of the flow rate adjuster 73a is maintained at zero, and the inner tank discharge flow rate of the first gas supply unit 70 is maintained at zero, thereby preventing nitrogen gas bubbling in the inner tank 11. That is, the control unit 91 increases only the outer tank discharge flow rate of the second gas supply unit 80 to generate only nitrogen gas bubbling in the outer tank 12. This reduces the decrease in the concentration of oxygen (O2) dissolved in the processing liquid in the inner tank 11 while decreasing the flow rate of the processing liquid, thereby reducing the decrease in the concentration of nitrogen dioxide on the surface of the wafer W, compared to the concentration adjustment process shown in FIG. 8. Therefore, Modification 2 reduces the decrease in the etching rate of the molybdenum film 101 compared to the embodiment.

[0090] 11 is an explanatory diagram of the concentration adjustment process according to Modification 3 of the embodiment. In FIG. 11, the first gas supply unit 70 and the second gas supply unit 80 discharge oxygen (O2) gas, which is an oxygen-containing gas, as the gas.

[0091] The control unit 91 adjusts the liquid feed pressure of the pump 55, the inner tank valve opening degree of the flow rate adjustment unit 73b, and the outer tank valve opening degree of the flow rate adjustment unit 83b to adjust the discharge flow rate of the processing liquid supply unit 30, the inner tank discharge flow rate of the first gas supply unit 70, and the outer tank discharge flow rate of the second gas supply unit 80. Thereby, the control unit 91 adjusts the concentration of nitrogen dioxide on the surface of the wafer W that contributes to the reaction of the molybdenum film 101.

[0092] For example, in the example shown in FIG. 11, the control unit 91 increases the concentration of nitrogen dioxide on the surface of the wafer W. That is, the control unit 91 lowers the liquid feed pressure of the pump 55 from the pressure P0 to the pressure P2 (<P0) at a time t1 before the time t2 when the loading process starts, thereby lowering the discharge flow rate of the processing liquid supply units 30_1 to 30_3 from the flow rate F4 to the flow rate F6 (<F4). The pressure P0 and the flow rate F4 may be, for example, the liquid feed pressure of the pump 55 and the discharge flow rates of the processing liquid supply units 30_1 to 30_3 used in the previous substrate processing. Further, the control unit 91 may further lower the discharge flow rate of the processing liquid supply units 30_1 to 30_3 by controlling the flow rate adjustment unit 60 to increase the flow rate of the processing liquid flowing through the bypass path 53. The control unit 91 can lower the flow velocity of the liquid flow of the processing liquid in the inner tank 11 by lowering the discharge flow rate of the processing liquid supply units 30_1 to 30_3.

[0093] Also, the control unit 91 increases the inner tank discharge flow rate of the first gas supply unit 70 from 0 to the flow rate F7 by increasing the inner tank valve opening degree of the flow rate adjustment unit 73b from 0 to the opening degree V1 at the time t1. The control unit 91 can increase the concentration of oxygen (O2) dissolved in the processing liquid in the inner tank 11 by increasing the inner tank discharge flow rate of the first gas supply unit 70 to generate oxygen gas bubbling in the inner tank 11.

[0094] Furthermore, at time t1, the control unit 91 increases the outer tank valve opening of the flow rate adjustment unit 83b from 0 to opening V2, thereby increasing the outer tank discharge flow rate of the second gas supply unit 80 from 0 to flow rate F8. By increasing the outer tank discharge flow rate of the second gas supply unit 80 to generate bubbling of oxygen gas in the outer tank 12, the control unit 91 can increase the concentration of oxygen (O2) dissolved in the treatment liquid in the inner tank 11.

[0095] As described above, in the substrate processing apparatus 1 according to the third modification, the flow rate of the processing liquid in the inner tank 11 is reduced, thereby causing nitrogen dioxide to remain on the surface of the wafer W. Furthermore, in the substrate processing apparatus 1, the concentration of oxygen (O2) dissolved in the processing liquid in the inner tank 11 is increased to promote the generation of nitrogen dioxide (see chemical reaction formula (3) above). As a result, the control unit 91 can increase the concentration of nitrogen dioxide, an intermediate that contributes to the oxidation reaction of the molybdenum film 101, on the surface of the wafer W before starting the etching process. This promotes the oxidation reaction of the molybdenum film 101, thereby increasing the etching rate of the molybdenum film 101. In other words, the substrate processing apparatus 1 according to the third modification can improve the controllability of the etching rate of the molybdenum film 101.

[0096] Next, the control unit 91 performs a loading process from time t2 to time t3. In the loading process, the control unit 91 controls an elevation mechanism (not shown) of the substrate holding unit 20 to lower the substrate holding unit 20, thereby immersing the wafers W in the processing liquid stored in the inner tank 11. From time t2 onward, the control unit 91 reduces the inner tank valve aperture of the flow rate adjuster 73b from aperture V1 to 0, thereby reducing the inner tank discharge flow rate of the first gas supply unit 70 from flow rate F7 to 0. Furthermore, from time t2 to time t3, the control unit 91 reduces the outer tank valve aperture of the flow rate adjuster 83b from aperture V2 to 0, thereby reducing the outer tank discharge flow rate of the second gas supply unit 80 from flow rate F8 to 0.

[0097] In this manner, in the substrate processing apparatus 1, during the period in which the plurality of wafers W are immersed in the processing liquid (the period from time t2 to time t3), the discharge of oxygen gas from the first gas supply unit 70 and the second gas supply unit 80 is stopped. This makes it possible to reduce the flow rate of the processing liquid in the inner tank 11, and as a result, it is possible to prevent the wafers W from falling off the substrate holder 20.

[0098] Next, at time t3 when the etching process starts, the control unit 91 again increases the outer tank valve aperture of the flow rate adjustment unit 83b from 0 to aperture V2, thereby again increasing the outer tank discharge flow rate of the second gas supply unit 80 from 0 to flow rate F8. As a result, the control unit 91 can increase the concentration of nitrogen dioxide, an intermediate that contributes to the oxidation reaction of the molybdenum film 101, on the surface of the wafer W during the etching process. This promotes the oxidation reaction of the molybdenum film 101, thereby increasing the etching rate of the molybdenum film 101. In other words, the substrate processing apparatus 1 according to Modification 3 can improve the controllability of the etching rate of the molybdenum film 101.

[0099] Furthermore, the control unit 91 maintains the inner tank discharge flow rate of the first gas supply unit 70 at 0 even after time t3 when the etching process is started. This reduces the flow rate of the processing liquid in the inner tank 11 during the etching process, allowing nitrogen dioxide to remain on the surface of the wafer W. This further accelerates the oxidation reaction of the molybdenum film 101, thereby further increasing the etching rate of the molybdenum film 101.

[0100] Next, the control unit 91 performs an etching process during the period from time t3 to time t4.

[0101] Next, the control unit 91 performs an unloading process during the period from time t4 to time t5. During the unloading process, the control unit 91 controls an elevation mechanism (not shown) provided in the substrate holding unit 20 to raise the substrate holding unit 20, thereby lifting the multiple wafers W from the processing liquid in the inner bath 11. During the period from time t4 to time t5, the control unit 91 reduces the outer bath valve aperture of the flow rate adjustment unit 83b from aperture V2 to 0, thereby reducing the outer bath discharge flow rate of the second gas supply unit 80 from flow rate F8 to 0.

[0102] In this manner, in the substrate processing apparatus 1, during the period when the wafers W are being lifted from the processing liquid (the period from time t4 to time t5), the discharge of oxygen gas from the first gas supply unit 70 and the second gas supply unit 80 is stopped. This makes it possible to reduce the flow rate of the processing liquid in the inner tank 11, and as a result, it is possible to prevent the wafers W from falling off the substrate holder 20.

[0103] Subsequently, when the control unit 91 completes the carry-out process at time t5, it increases the liquid sending pressure of the pump 55 from pressure P2 to pressure P0 (>P2), thereby increasing the discharge flow rates of the processing liquid supply units 30_1 to 30_3 from flow rate F6 to flow rate F4 (>F6). Furthermore, the control unit 91 may control the flow rate adjustment unit 60 to close the bypass path 53. By increasing the discharge flow rates of the processing liquid supply units 30_1 to 30_3, the control unit 91 can return the flow rate of the processing liquid in the inner tank 11 to the initial flow rate.

[0104] 11 , the control unit 91 adjusts the concentration of nitrogen dioxide, which contributes to the reaction of the molybdenum film 101, on the surface of the wafer W by adjusting the discharge flow rate of the processing liquid supply unit 30, the inner tank discharge flow rate of the first gas supply unit 70, and the outer tank discharge flow rate of the second gas supply unit 80. Alternatively, the control unit 91 may adjust the concentration of nitrogen dioxide on the surface of the wafer W by adjusting at least one of the discharge flow rate of the processing liquid supply unit 30, the inner tank discharge flow rate of the first gas supply unit 70, and the outer tank discharge flow rate of the second gas supply unit 80. In this case, the control unit 91 may increase the concentration of nitrogen dioxide on the surface of the wafer W by performing at least one of the following processes: decreasing the discharge flow rate of the processing liquid supply unit 30, increasing the inner tank discharge flow rate of the first gas supply unit 70, and increasing the outer tank discharge flow rate of the second gas supply unit 80.

[0105] FIG. 12 is an explanatory diagram of the density adjustment process according to the fourth modification of the embodiment.

[0106] 12 , at time t3 when the etching process is started, the control unit 91 increases the inner tank valve aperture of the flow rate adjustment unit 73b from 0 to aperture V1 again, thereby increasing the inner tank discharge flow rate of the first gas supply unit 70 from 0 to flow rate F7 again. This allows the control unit 91 to increase the concentration of nitrogen dioxide, an intermediate that contributes to the oxidation reaction of the molybdenum film 101, on the surface of the wafer W during the etching process. This promotes the oxidation reaction of the molybdenum film 101, thereby increasing the etching rate of the molybdenum film 101. That is, the substrate processing apparatus 1 according to Modification 4 can improve the controllability of the etching rate of the molybdenum film 101.

[0107] FIG. 13 is an explanatory diagram of the density adjustment process according to the fifth modification of the embodiment.

[0108] In the example shown in FIG. 13, the control unit 91 reduces the concentration of nitrogen dioxide on the surface of the wafer W before starting the wafer W loading and unloading processes, and increases the concentration of nitrogen dioxide on the surface of the wafer W during the etching process.

[0109] Specifically, at time t1, which is before time t2 when the loading process is started, the control unit 91 increases the liquid supply pressure of the pump 55 from pressure P0 to pressure P1 (>P0), thereby increasing the discharge flow rates of the processing liquid supply units 30_1 to 30_3 from flow rate F4 to flow rate F5 (>F4). The pressure P0 and the flow rate F4 may be, for example, the liquid supply pressure of the pump 55 and the discharge flow rates of the processing liquid supply units 30_1 to 30_3, respectively, used in the previous substrate processing. The control unit 91 may also further increase the discharge flow rates of the processing liquid supply units 30_1 to 30_3 by controlling the on-off valve 59 to switch the filter bypass path 58 from a closed state to an open state. By increasing the discharge flow rates of the processing liquid supply units 30_1 to 30_3, the control unit 91 can increase the flow velocity of the processing liquid in the inner tank 11.

[0110] Furthermore, at time t1, the control unit 91 increases the inner tank valve opening of the flow rate adjustment unit 73a from 0 to opening V1, thereby increasing the inner tank discharge flow rate of the first gas supply unit 70 from 0 to flow rate F7. By increasing the inner tank discharge flow rate of the first gas supply unit 70 to generate bubbling of nitrogen gas in the inner tank 11, the control unit 91 can reduce the concentration of oxygen (O2) dissolved in the treatment liquid in the inner tank 11.

[0111] Furthermore, at time t1, the control unit 91 increases the outer tank valve opening of the flow rate adjustment unit 83a from 0 to opening V2, thereby increasing the outer tank discharge flow rate of the second gas supply unit 80 from 0 to flow rate F8. By increasing the outer tank discharge flow rate of the second gas supply unit 80 to generate bubbling of nitrogen gas in the outer tank 12, the control unit 91 can reduce the concentration of oxygen (O2) dissolved in the treatment liquid in the inner tank 11.

[0112] By performing such a process, the control unit 91 can reduce the concentration of nitrogen dioxide on the surface of the wafer W before starting the loading process. As a result, before starting the loading process, the etching rate of the molybdenum film 101 can be decreased. In the loading process, since the lower end of the wafer W is first immersed in the processing liquid stored in the inner tank 11, the etching amount at the lower end of the wafer W tends to be larger than the etching amount at the upper end of the wafer W. In contrast, the control unit 91 can reduce the difference in the etching amount between the upper and lower ends of the wafer W by decreasing the etching rate of the molybdenum film 101 before starting the loading process to suppress the increase in the etching amount at the lower end of the wafer W.

[0113] Subsequently, the control unit 91 performs the loading process during the period from time t2 to time t3. The control unit 91 decreases the inner tank valve opening degree of the flow rate adjustment unit 73a from the opening degree V1 to 0, thereby decreasing the inner tank discharge flow rate of the first gas supply unit 70 from the flow rate F7 to 0 during the period from time t2 to time t3. Further, the control unit 91 decreases the outer tank valve opening degree of the flow rate adjustment unit 83a from the opening degree V2 to 0, thereby decreasing the outer tank discharge flow rate of the second gas supply unit 80 from the flow rate F8 to 0 during the period from time t2 to time t3. As a result, the flow velocity of the liquid flow of the processing liquid in the inner tank 11 can be temporarily decreased, and thus, it is possible to suppress the wafer W from falling off the substrate holding unit 20.

[0114] Subsequently, the control unit 91 performs the etching process during the period from time t3 to time t4.

[0115] At the time t3 when the etching process is started, the control unit 91 decreases the liquid feed pressure of the pump 55 from the pressure P1 to the pressure P2 (<P1), thereby decreasing the discharge flow rates of the processing liquid supply units 30_1 to 30_3 from the flow rate F5 to the flow rate F6 (<F5). The control unit 91 can decrease the flow velocity of the liquid flow of the processing liquid in the inner tank 11 by decreasing the discharge flow rates of the processing liquid supply units 30_1 to 30_3.

[0116] At time t3 when the etching process starts, the control unit 91 increases the inner tank valve opening degree of the flow rate adjustment unit 73b from 0 to opening degree V1, thereby increasing the inner tank discharge flow rate of the first gas supply unit 70 from 0 to flow rate F7. By increasing the inner tank discharge flow rate of the first gas supply unit 70 to generate bubbling of oxygen gas in the inner tank 11, the control unit 91 can increase the concentration of oxygen (O2) dissolved in the processing liquid in the inner tank 11.

[0117] The control unit 91 continues bubbling oxygen gas in the inner tank 11 from time t3 to time t31, and at time t31, reduces the inner tank valve aperture of the flow rate adjustment unit 73b from aperture V1 to 0, thereby reducing the inner tank discharge flow rate of the first gas supply unit 70 from flow rate F7 to 0. This reduces the flow rate of the processing liquid in the inner tank 11 during the etching process, allowing nitrogen dioxide to remain on the surfaces of the wafers W. This further accelerates the oxidation reaction of the molybdenum film 101, thereby further increasing the etching rate of the molybdenum film 101.

[0118] The control unit 91 maintains the inner tank discharge flow rate of the first gas supply unit 70 at 0 from time t31 to time t32, and at time t32 increases the inner tank valve opening of the flow rate adjustment unit 73a from 0 to opening V1, thereby increasing the inner tank discharge flow rate of the first gas supply unit 70 from 0 to flow rate F7. By increasing the inner tank discharge flow rate of the first gas supply unit 70 to generate bubbling of nitrogen gas in the inner tank 11, the control unit 91 can reduce the concentration of oxygen (O2) dissolved in the treatment liquid in the inner tank 11.

[0119] By performing this process, the control unit 91 can reduce the concentration of nitrogen dioxide on the surface of the wafer W before starting the unloading process. This reduces the etching rate of the molybdenum film 101 before starting the unloading process. During the unloading process, the lower end of the wafer W is pulled up last from the processing solution stored in the inner tank 11, so the etching amount at the lower end of the wafer W tends to be larger than the etching amount at the upper end of the wafer W. In response to this, the control unit 91 reduces the etching rate of the molybdenum film 101 before starting the unloading process to suppress an increase in the etching amount at the lower end of the wafer W, thereby reducing the difference in etching amount between the upper and lower ends of the wafer W.

[0120] Furthermore, at time t3, the control unit 91 increases the outer tank valve opening of the flow rate adjustment unit 83b from 0 to opening V2, thereby increasing the outer layer discharge flow rate of the second gas supply unit 80 from 0 to flow rate F8. The control unit 91 increases the outer tank discharge flow rate of the second gas supply unit 80 to generate bubbling of oxygen gas in the outer tank 12, thereby increasing the concentration of oxygen (O2) dissolved in the treatment liquid in the inner tank 11.

[0121] The control unit 91 continues bubbling of oxygen gas in the outer tank 12 from time t3 to time t32, and at time t32, controls the flow rate adjustment units 83a and 83b to switch the gas discharged from the second gas supply unit 80 from oxygen gas to nitrogen gas. In this way, the control unit 91 generates bubbling of nitrogen gas in the outer tank 12, thereby enabling the concentration of oxygen (O2) dissolved in the treatment liquid in the inner tank 11 to be reduced.

[0122] Subsequently, the control unit 91 performs the unloading process during the period from time t4 to time t5. The control unit 91 reduces the inner tank valve opening degree of the flow rate adjustment unit 73a from the opening degree V1 to 0 during the period from time t4 to time t5, thereby reducing the inner tank discharge flow rate of the first gas supply unit 70 from the flow rate F7 to 0. The control unit 91 reduces the outer tank valve opening degree of the flow rate adjustment unit 83a from the opening degree V2 to 0 during the period from time t4 to time t5, thereby reducing the outer tank discharge flow rate of the second gas supply unit 80 from the flow rate F8 to 0. As a result, the flow velocity of the processing liquid flow in the inner tank 11 can be reduced, and as a result, it is possible to suppress the wafer W from falling off the substrate holding unit 20.

[0123] Subsequently, when the control unit 91 finishes the unloading process at time t5, the control unit 91 reduces the liquid feed pressure of the pump 55 from the pressure P1 to the pressure P0 (<P1), thereby reducing the discharge flow rate of the processing liquid supply units 30_1 to 30_3 from the flow rate F5 to the flow rate F4 (<F5). By reducing the discharge flow rate of the processing liquid supply units 30_1 to 30_3, the control unit 91 can return the flow velocity of the processing liquid flow in the inner tank 11 to the initial flow velocity.

[0124] (Other modifications) In the above embodiment, an example in the case of etching the molybdenum film 101 of the wafer W has been described. However, the film to be etched may be a metal film other than the molybdenum film such as a tungsten film.

[0125] In the above embodiment, an example in which the concentration adjustment process is started before the loading process of the wafer W and the concentration adjustment process is ended after the unloading process of the wafer W has been described. However, the start timing and end timing of the concentration adjustment process may be arbitrary timings.

[0126] As described above, the substrate processing apparatus (e.g., substrate processing apparatus 1) according to the embodiment includes a processing tank (e.g., inner tank 11), a group of outlets (e.g., multiple outlets 32_1-32_2 provided in processing liquid supply units 30_1-30_3), an overflow tank (e.g., outer tank 12), a circulation channel (e.g., circulation channel 50), a liquid delivery unit (e.g., pump 55), a first gas supply unit (e.g., first gas supply unit 70), a second gas supply unit (e.g., second gas supply unit 80), a first adjustment unit (e.g., flow rate adjustment units 73a and 73b), a second adjustment unit (e.g., flow rate adjustment units 83a and 83b), and a control unit (e.g., control unit 91). In the processing tank, a substrate (e.g., wafer W) having a metal film (e.g., molybdenum film 101) is immersed in a processing liquid to perform an etching process. The discharge port group is arranged below the substrate inside the processing tank and discharges the processing liquid into the processing tank. The overflow tank stores the processing liquid that overflows from the processing tank. The circulation flow path connects the overflow tank and the discharge port group. The liquid delivery unit sends the processing liquid stored in the overflow tank to the circulation flow path. The first gas supply unit is arranged below the substrate inside the processing tank and discharges gas into the processing tank. The second gas supply unit is arranged inside the overflow tank and discharges gas into the overflow tank. The first adjustment unit adjusts the flow rate of the gas discharged from the first gas supply unit. The second adjustment unit adjusts the flow rate of the gas discharged from the second gas supply unit. The control unit controls the liquid delivery unit, the first adjustment unit, and the second adjustment unit to adjust at least one of the flow rate of the processing liquid discharged from the discharge port group, the flow rate of the gas discharged from the first gas supply unit, and the flow rate of the gas discharged from the second gas supply unit, thereby performing a concentration adjustment process to adjust the concentration on the substrate surface of an intermediate (e.g., nitrogen dioxide) that contributes to the reaction of the metal film. Therefore, the substrate processing apparatus according to the embodiment can improve the controllability of the etching rate of the metal film.

[0127] The disclosed embodiments should be considered in all respects as illustrative and not restrictive. Indeed, the above-described embodiments may be embodied in various forms. Furthermore, the above-described embodiments may be omitted, substituted, or modified in various ways without departing from the scope and spirit of the appended claims. [Explanation of symbols]

[0128] 1. Substrate processing equipment 11 Inner tank 12 Outer tank 20 Board holding part 30_1~30_3 Processing liquid supply section 31_1~31_3 Nozzle 32_1~32_3 Discharge port 50 Circulation flow path 51 Exhaust channel 52_1~52_3 Supply route 53 Bypass Road 55 Pump 56 Heater 57 Filters 58 Filter bypass path 59 On-off valve 60 Flow rate adjustment section 70 First gas supply section 71 nozzle 72 Discharge port 73a Flow rate adjustment section 73b Flow rate adjustment section 74a Gas supply source 74b Gas supply source 80 Second gas supply section 81 nozzle 82 Discharge port 83a Flow rate adjustment section 83b Flow rate adjustment section 84a Gas supply source 84b Gas supply source 90 Control device 91 Control Unit 92 Memory section 100 Polysilicon film 101 Molybdenum film 102 Silicon oxide film W wafer

Claims

1. a treatment tank for immersing a substrate having a metal film therein in a treatment solution to perform an etching treatment; a group of outlets arranged below the substrate inside the processing tank and configured to discharge the processing liquid into the processing tank; an overflow tank for storing the processing solution that overflows from the processing tank; a circulation flow path connecting the overflow tank and the discharge port group; a liquid delivery unit that delivers the treatment liquid stored in the overflow tank to the circulation flow path; a first gas supply unit disposed inside the processing tank below the substrate and configured to discharge a gas into the processing tank; a second gas supply unit disposed inside the overflow tank and configured to discharge a gas into the overflow tank; a first adjusting unit that adjusts the flow rate of the gas discharged from the first gas supply unit; a second adjusting unit that adjusts the flow rate of the gas discharged from the second gas supply unit; a control unit that controls the liquid supply unit, the first adjustment unit, and the second adjustment unit to adjust at least one of the flow rate of the processing liquid discharged from the discharge port group, the flow rate of the gas discharged from the first gas supply unit, and the flow rate of the gas discharged from the second gas supply unit, thereby adjusting the concentration of an intermediate that contributes to a reaction of the metal film on the surface of the substrate; and Equipped with The substrate processing apparatus, wherein the intermediate is nitrogen dioxide (NO 2 ).

2. A treatment tank for immersing a substrate having a metal film in a treatment solution to perform an etching treatment; a group of outlets arranged below the substrate inside the processing tank and configured to discharge the processing liquid into the processing tank; an overflow tank for storing the processing solution that overflows from the processing tank; a circulation flow path connecting the overflow tank and the discharge port group; a liquid delivery unit that delivers the treatment liquid stored in the overflow tank to the circulation flow path; a first gas supply unit disposed inside the processing tank below the substrate and configured to discharge a gas into the processing tank; a second gas supply unit disposed inside the overflow tank and configured to discharge a gas into the overflow tank; a first adjusting unit that adjusts the flow rate of the gas discharged from the first gas supply unit; a second adjusting unit that adjusts the flow rate of the gas discharged from the second gas supply unit; a control unit that controls the liquid supply unit, the first adjustment unit, and the second adjustment unit to adjust at least one of the flow rate of the processing liquid discharged from the discharge port group, the flow rate of the gas discharged from the first gas supply unit, and the flow rate of the gas discharged from the second gas supply unit, thereby adjusting the concentration of an intermediate that contributes to a reaction of the metal film on the surface of the substrate; and Equipped with the first gas supply unit and the second gas supply unit discharge an oxygen-containing gas as the gas; The control unit In the concentration adjustment process, the substrate processing apparatus increases the concentration on the surface of the metal film of the intermediate by performing at least one of a process of reducing the flow rate of the processing liquid discharged from the group of discharge ports, a process of increasing the flow rate of the gas discharged from the first gas supply unit, and a process of increasing the flow rate of the gas discharged from the second gas supply unit.

3. The control unit The substrate processing apparatus according to claim 2 , wherein the flow rate of the processing liquid discharged from the discharge port group is reduced by reducing the liquid delivery pressure of the liquid delivery section.

4. The circulation flow path is a discharge path connected to the overflow tank; a supply path branching from the discharge path and connected to the discharge port group; a bypass path branching from the discharge path and connected to the overflow tank; a third adjusting unit provided in the bypass path and configured to adjust the flow rate of the treatment liquid flowing through the bypass path; Equipped with The control unit The substrate processing apparatus according to claim 2 , wherein the third adjusting unit controls the flow rate of the processing liquid flowing through the bypass path to decrease the flow rate of the processing liquid discharged from the discharge port group.

5. The control unit The substrate processing apparatus according to claim 2 , wherein the ejection of the gas from the first gas supply unit and the second gas supply unit is stopped during a period in which the substrate is immersed in the processing liquid and a period in which the substrate is pulled up from the processing liquid.

6. The oxygen-containing gas is air, oxygen (O ２ ) gas or ozone (O ３ 3. The substrate processing apparatus of claim 2, wherein the gas is a fluorine-containing gas.

7. A treatment tank for performing an etching treatment by immersing a substrate having a metal film in a treatment solution; a group of outlets arranged below the substrate inside the processing tank and configured to discharge the processing liquid into the processing tank; an overflow tank for storing the processing solution that overflows from the processing tank; a circulation flow path connecting the overflow tank and the discharge port group; a liquid delivery unit that delivers the treatment liquid stored in the overflow tank to the circulation flow path; a first gas supply unit disposed inside the processing tank below the substrate and configured to discharge a gas into the processing tank; a second gas supply unit disposed inside the overflow tank and configured to discharge a gas into the overflow tank; a first adjusting unit that adjusts the flow rate of the gas discharged from the first gas supply unit; a second adjusting unit that adjusts the flow rate of the gas discharged from the second gas supply unit; a control unit that controls the liquid supply unit, the first adjustment unit, and the second adjustment unit to adjust at least one of the flow rate of the processing liquid discharged from the discharge port group, the flow rate of the gas discharged from the first gas supply unit, and the flow rate of the gas discharged from the second gas supply unit, thereby adjusting the concentration of an intermediate that contributes to a reaction of the metal film on the surface of the substrate; and Equipped with The treatment solution contains at least nitric acid (HNO ３ ), phosphoric acid (H ３ P.O. ４ ) and water (H ２ O) as a component of the processing solution.

8. 8. The substrate processing apparatus according to claim 1, wherein the metal film is a molybdenum film or a tungsten film.

9. a treatment tank for immersing a substrate having a metal film therein in a treatment solution to perform an etching treatment; a group of outlets arranged below the substrate inside the processing tank and configured to discharge the processing liquid into the processing tank; an overflow tank for storing the processing solution that overflows from the processing tank; a circulation flow path connecting the overflow tank and the discharge port group; a liquid delivery unit that delivers the treatment liquid stored in the overflow tank to the circulation flow path; a first gas supply unit disposed inside the processing tank below the substrate and configured to discharge a gas into the processing tank; a second gas supply unit disposed inside the overflow tank and configured to discharge a gas into the overflow tank; a first adjusting unit that adjusts the flow rate of the gas discharged from the first gas supply unit; a second adjusting unit that adjusts the flow rate of the gas discharged from the second gas supply unit; A substrate processing method in a substrate processing apparatus comprising: adjusting a concentration of an intermediate contributing to a reaction of the metal film on the surface of the substrate by adjusting at least one of a flow rate of the processing liquid discharged from the discharge port group, a flow rate of the gas discharged from the first gas supply unit, and a flow rate of the gas discharged from the second gas supply unit; The method for processing a substrate, wherein the intermediate is nitrogen dioxide (NO 2 ).

10. A treatment tank for immersing a substrate having a metal film in a treatment solution to perform an etching treatment; a group of outlets arranged below the substrate inside the processing tank and configured to discharge the processing liquid into the processing tank; an overflow tank for storing the processing solution that overflows from the processing tank; a circulation flow path connecting the overflow tank and the discharge port group; a liquid delivery unit that delivers the treatment liquid stored in the overflow tank to the circulation flow path; a first gas supply unit disposed inside the processing tank below the substrate and configured to discharge a gas into the processing tank; a second gas supply unit disposed inside the overflow tank and configured to discharge a gas into the overflow tank; a first adjusting unit that adjusts the flow rate of the gas discharged from the first gas supply unit; a second adjusting unit that adjusts the flow rate of the gas discharged from the second gas supply unit; A substrate processing method in a substrate processing apparatus comprising: adjusting a concentration of an intermediate contributing to a reaction of the metal film on the surface of the substrate by adjusting at least one of a flow rate of the processing liquid discharged from the discharge port group, a flow rate of the gas discharged from the first gas supply unit, and a flow rate of the gas discharged from the second gas supply unit; The substrate processing method, wherein the processing liquid contains at least nitric acid (HNO 3 ), phosphoric acid (H 3 PO 4 ), and water (H 2 O) as components.

Images