Substrate processing apparatus and substrate processing method

Abstract

A substrate processing apparatus according to the present disclosure is configured to etch a molybdenum film of a substrate having a device structure that includes a multilayer film including the molybdenum film in a plurality of stages. A processing tank stores an etching solution including as components thereof acetic acid, phosphoric acid, nitric acid, and water. A control unit determines a discharge amount of the etching solution from the processing tank and a replenishment amount of the acetic acid, the phosphoric acid, and the nitric acid to the processing tank, on the basis of the concentration of each component measured by a concentration-measuring unit, the amount of the etching solution measured by a solution-amount-measuring unit, the target amount of the etching solution set in advance, and the target concentration for each component set in advance, controls an on-off valve to discharge the determined discharge amount of the etching solution from the processing tank, and controls a supply unit to replenish the processing tank with the determined replenishment amount of the acetic acid, the phosphoric acid, and the nitric acid.

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 tungsten 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] Japanese Patent Application Laid-Open No. 2003-234307 Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides a technique for stably etching a molybdenum film formed on a substrate. [Means for solving the problem]

[0005] A substrate processing apparatus according to one aspect of the present disclosure etches a molybdenum film on a substrate having a device structure including multiple layers of a molybdenum film, and includes a processing tank, a supply unit, an on-off valve, a concentration measurement unit, a liquid volume measurement unit, and a control unit. The processing tank stores an etching solution containing acetic acid, phosphoric acid, nitric acid, and water as components. The supply unit supplies the acetic acid, phosphoric acid, nitric acid, and water to the processing tank individually or as an etching solution. The on-off valve opens and closes a drainage path of the processing tank. The concentration measurement unit measures the concentration of each component of the etching solution stored in the processing tank. The liquid volume measurement unit measures the amount of the etching solution stored in the processing tank. The control unit controls the on-off valve and the supply unit to perform a discharge and replenishment process in which a portion of the etching solution is discharged from the processing tank and the processing tank is replenished with acetic acid, phosphoric acid, and nitric acid. In the discharge and replenishment process, the control unit determines the amount of etching solution to be discharged from the treatment tank and the amount of acetic acid, phosphoric acid, and nitric acid to be replenished to the treatment tank based on the concentration of each component measured by the concentration measurement unit, the amount of etching solution measured by the liquid volume measurement unit, a predetermined target amount of etching solution, and a predetermined target concentration of each component, controls the on-off valve to discharge the determined amount of etching solution from the treatment tank, and controls the supply unit to replenish the determined replenishment amounts of acetic acid, phosphoric acid, and nitric acid to the treatment tank. [Effects of the Invention]

[0006] According to the present disclosure, a molybdenum film formed on a substrate can be stably etched. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is an explanatory view of a substrate processing according to an embodiment. [Figure 2] FIG. 2 is an explanatory view of the substrate processing according to the embodiment. [Figure 3] FIG. 3 is a graph showing the change over time in the etching rate of the etching solution for the molybdenum film. [Figure 4] FIG. 4 is a graph showing the change over time in the water concentration and acetic acid concentration of the etching solution. [Figure 5]FIG. 5 is a diagram showing the configuration of a substrate processing apparatus according to an embodiment. [Figure 6] FIG. 6 is a schematic explanatory view of the liquid exchange process, the concentration adjustment process, and the discharge and replenishment process performed by the substrate processing apparatus according to this embodiment. [Figure 7] FIG. 7 is a flowchart showing the procedure of the liquid exchange process and the concentration adjustment process according to the embodiment. [Figure 8] FIG. 8 is a flowchart showing the procedure of the discharge and replenishment process according to 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 manufacturing precision, installation precision, etc.

[0010] <About substrate processing> First, the contents of the substrate processing according to the embodiment will be described with reference to Figures 1 and 2. Figures 1 and 2 are explanatory views of the substrate processing according to the embodiment.

[0011] As shown in FIG. 1, a semiconductor wafer (hereinafter referred to as wafer W) to be subjected to the substrate processing according to the embodiment has a device structure including multiple stages of multilayer films including molybdenum films.

[0012] As an example, the wafer W has a molybdenum film 11 and a plurality of silicon oxide films 12 on a polysilicon film 10. The plurality of silicon oxide films 12 are formed at intervals on the polysilicon film 10. The molybdenum film 11 is located in the gaps between the silicon oxide films 12 and is formed so as to entirely cover the plurality of silicon oxide films 12.

[0013] As described above, the device structure of the wafer W according to the embodiment includes a multilayer film in which the molybdenum film 11 and the silicon oxide film 12 are stacked in multiple stages. The multilayer film may include a film other than the molybdenum film 11 and the silicon oxide film 12. For example, the multilayer film may include a titanium nitride film between the molybdenum film 11 and the silicon oxide film 12.

[0014] Furthermore, a plurality of grooves 15 are formed in the wafer W so that an etching solution can penetrate therein and etch the deposited molybdenum film 11. Note that only one groove 15 is shown in FIG.

[0015] In the substrate processing according to the embodiment, the molybdenum film 11 of the wafer W is etched to expose a part (edge) of the silicon oxide film 12 from the molybdenum film 11, as shown in FIG.

[0016] An etching solution containing acetic acid, phosphoric acid, nitric acid, and water is used to etch the molybdenum film 11. The inventors have found that the etching rate of the etching solution for the molybdenum film 11 increases over time. The inventors have also found that this is due to an increase in the water concentration in the etching solution.

[0017] FIG. 3 is a graph showing the change over time in the etching rate of the etching solution for the molybdenum film 11. FIG. 4 is a graph showing the change over time in the water concentration and acetic acid concentration of the etching solution. Note that "time" here means, for example, the time elapsed from the time when the etching solution was adjusted to a desired concentration. Alternatively, "time" here may mean the time elapsed from the time when processing of the wafer W was started using the etching solution adjusted to the desired concentration.

[0018] As shown in Figure 3, the etching rate of the etching solution for the molybdenum film 11 increases with time. Also, as shown in Figure 4, the water concentration of the etching solution increases with time, while the acetic acid concentration of the etching solution decreases with time.

[0019] Thus, a correlation was observed between an increase in the water concentration of the etching solution and an increase in the etching rate of the etching solution for the molybdenum film 11. Also, a correlation was observed between an increase in the water concentration of the etching solution and a decrease in the acetic acid concentration of the etching solution.

[0020] The reason for this result is considered to be, for example, as follows. That is, etching of the molybdenum film 11 proceeds as a result of molybdenum oxide reacting with water. Specifically, nitric acid in the etching solution reacts with molybdenum to produce molybdenum oxide, which then reacts with water in the etching solution, dissolving the molybdenum oxide (i.e., etching). For this reason, it is believed that the higher the water concentration in the etching solution, the higher the etching rate of the molybdenum film 11.

[0021] Regarding the correlation between the water concentration and acetic acid concentration of the etching solution, the following two points can be considered. First, it is thought that the evaporation of acetic acid in the etching solution caused a relative increase in the water concentration of the etching solution. Second, because acetic acid is hygroscopic, it is thought that the acetic acid in the etching solution absorbed moisture from the air, causing the water concentration of the etching solution to increase.

[0022] As described above, the etching solution according to the embodiment contains acetic acid, which tends to increase the water concentration, and the increased water concentration increases the etching rate for the molybdenum film 11. Molybdenum is a base metal, has a high ionization tendency, and is relatively easily oxidized. Therefore, the molybdenum film 11 is more easily etched than, for example, a tungsten film, and an increased etching rate may result in greater variation in the amount of etching in the stacking direction, for example. Therefore, it is desirable to minimize the increase in the etching rate.

[0023] Therefore, in the substrate processing apparatus according to the embodiment, an increase in the water concentration of the etching solution is suppressed, thereby suppressing an increase in the etching rate, thereby stabilizing the etching of the molybdenum film 11.

[0024] <Configuration of the substrate processing apparatus> Next, the configuration of a substrate processing apparatus for performing the above-mentioned substrate processing will be described with reference to Fig. 5. Fig. 5 is a diagram showing the configuration of a substrate processing apparatus according to an embodiment.

[0025] 5, the substrate processing apparatus 1 includes a processing bath 3, a holding unit 4, and a supply unit 5. The substrate processing apparatus 1 also includes a control unit .

[0026] The processing tank 3 includes an inner tank 31, an outer tank 32, a circulation section 33, and a drainage section 34. The inner tank 31 is open at the top and stores an etching liquid therein. A plurality of wafers W are immersed in the inner tank 31. The outer tank 32 is disposed around the upper portion of the inner tank 31. The outer tank 32 is open at the top and stores the etching liquid that overflows from the inner tank 31.

[0027] A liquid level sensor 35 is provided in the outer tank 32. The liquid level sensor 35 measures the liquid level of the etching liquid stored in the outer tank 32. A differential pressure level sensor, for example, can be used as such a liquid level sensor 35. A control unit 71, which will be described later, detects the liquid amount of the etching liquid stored in the processing tank 3 based on the liquid level in the outer tank 32 measured by the liquid level sensor 35.

[0028] That is, the interior of the inner tank 31 and the circulation path 33a, which will be described later, are filled with the etching solution. Therefore, the amount of etching solution in the inner tank 31 and the circulation path 33a can be considered to be constant at all times. Therefore, the amount of etching solution in the entire processing tank 3 can be calculated by adding the amount of solution in the outer tank 32, which is determined from the liquid level of the etching solution in the outer tank 32, to the amount of solution in the inner tank 31 and the circulation path 33a, which is a known value.

[0029] In this way, the liquid level sensor 35 corresponds to an example of a liquid amount measuring unit that measures the amount of etching liquid stored in the processing tank 3.

[0030] The circulation unit 33 circulates the etching liquid between the inner bath 31 and the outer bath 32. The circulation unit 33 includes a circulation path 33a, a nozzle 33b, a pump 33c, a filter 33d, a temperature adjustment unit 33e, and a concentration sensor 33f.

[0031] The circulation path 33a connects the outer bath 32 and the inner bath 31. One end of the circulation path 33a is connected to the outer bath 32, and the other end of the circulation path 33a is connected to a nozzle 33b arranged inside the inner bath 31.

[0032] Pump 33c, filter 33d, temperature adjuster 33e, and concentration sensor 33f are provided in circulation path 33a. Pump 33c sends the etching liquid in outer bath 32 to circulation path 33a. Filter 33d removes impurities from the etching liquid flowing through circulation path 33a. Temperature adjuster 33e is, for example, an electronic thermostat, and adjusts the temperature of the etching liquid flowing through circulation path 33a to a temperature of 10°C or higher and 40°C or lower. Preferably, temperature adjuster 33e adjusts the temperature of the etching liquid to a temperature of 10°C or higher and room temperature or lower. Pump 33c and temperature adjuster 33e are controlled by control unit 71.

[0033] The concentration sensor 33f measures the concentration of each component of the etching solution circulating through the circulation path 33a. That is, the concentration sensor 33f measures the acetic acid concentration, phosphoric acid concentration, nitric acid concentration, and water concentration of the etching solution. The measurement results by the concentration sensor 33f are transmitted to the control unit 71, which will be described later.

[0034] In this way, the concentration sensor 33f corresponds to an example of a concentration measuring unit that measures the concentration of each component of the etching liquid stored in the processing tank 3.

[0035] The circulation unit 33 sends the etching liquid from the outer tank 32 into the inner tank 31 via the circulation path 33a. The etching liquid sent into the inner tank 31 overflows from the inner tank 31 and flows back into the outer tank 32. In this way, the etching liquid circulates between the inner tank 31 and the outer tank 32.

[0036] As described above, molybdenum is relatively easily etched, and therefore, if the temperature of the etching solution is increased, the etching rate of the molybdenum film 11 becomes too fast, which may result in large variations in the etching amount in the stacking direction of the molybdenum film 11. Therefore, the substrate processing apparatus 1 uses an etching solution cooled to a temperature of 10°C or higher and 40°C or lower, preferably 10°C or higher and room temperature or lower. The reason for setting the temperature at 10°C or higher is to suppress solidification of acetic acid (which has a melting point of approximately 17°C).

[0037] The drainage unit 34 includes a drainage channel 34a, an on-off valve 34b, and a flow rate adjustment valve 34c. The drainage channel 34a is connected to, for example, the bottom surface of the inner tank 31. The etching liquid stored in the processing tank 3 is discharged to the outside through the drainage channel 34a. The on-off valve 34b opens and closes the drainage channel 34a. The flow rate adjustment valve 34c is, for example, a needle valve, and adjusts the flow rate of the etching liquid discharged from the drainage channel 34a.

[0038] In this way, by providing the flow rate adjustment valve 34c in the drainage path 34a, the drainage speed can be adjusted. Specifically, the drainage speed can be slowed. This makes it possible to control with high precision the amount of etching liquid discharged from the processing tank 3 when discharging part of the etching liquid stored in the processing tank 3 in the discharge and replenishment process described below.

[0039] The holder 4 holds a plurality of wafers W in an upright position, arranged one behind the other. The holder 4 is connected to a lifting mechanism (not shown), and can move the held wafers W between a processing position in the inner bath 31 and a retracted position above the inner bath 31.

[0040] The supply unit 5 includes an etching solution supply unit 6 and an individual supply unit 8. The etching solution supply unit 6 supplies the etching solution to the processing tank 3. The individual supply units 8 supply each component of the etching solution (acetic acid, phosphoric acid, nitric acid, and water) to the processing tank 3 individually.

[0041] The etching liquid supply unit 6 includes an etching liquid supply source 6a, a supply path 6b, a temperature adjustment unit 6c, a first on-off valve 6d, a flow meter 6e, a constant pressure valve 6f, a flow rate adjustment valve 6g, and a second on-off valve 6h.

[0042] The supply path 6b connects the etching liquid supply source 6a and the outer tank 32 of the processing tank 3. The temperature adjustment unit 6c, the first on-off valve 6d, the flow meter 6e, the constant pressure valve 6f, the flow rate adjustment valve 6g, and the second on-off valve 6h are connected to the supply path 6b. In the embodiment, the temperature adjustment unit 6c, the first on-off valve 6d, the flow meter 6e, the constant pressure valve 6f, the flow rate adjustment valve 6g, and the second on-off valve 6h are provided in this order from the upstream side (the side closer to the etching liquid supply source 6a).

[0043] The temperature adjusting unit 6c is, for example, an electronic thermostat, and adjusts the temperature of the etching liquid flowing through the supply path 6b to a temperature of 10° C. or higher and 40° C. or lower. Preferably, the temperature adjusting unit 6c adjusts the temperature of the etching liquid to a temperature of 10° C. or higher and room temperature or lower.

[0044] The first on-off valve 6d and the second on-off valve 6h open and close the supply path 6b. The flow meter 6e measures the flow rate of the etching liquid flowing through the supply path 6b. The constant pressure valve 6f adjusts the pressure in the supply path 6b downstream of the constant pressure valve 6f. The flow rate adjustment valve 6g adjusts the flow rate of the etching liquid flowing through the supply path 6b.

[0045] The temperature adjustment unit 6c, the first on-off valve 6d, the flow rate adjustment valve 6g, and the second on-off valve 6h are controlled by a control unit 71. For example, the control unit 71 controls the flow rate adjustment valve 6g based on the flow rate of the etching liquid measured by the flow meter 6e, thereby adjusting the flow rate of the etching liquid flowing through the supply path 6b to a preset flow rate. This allows the substrate processing apparatus 1 to accurately adjust the replenishment amount of the etching liquid in the discharge and replenishment process described below.

[0046] Next, a description will be given of the individual supply unit 8. The individual supply unit 8 includes a first acetic acid supply unit 81, a phosphoric acid supply unit 82, a nitric acid supply unit 83, a water supply unit 84, and a second acetic acid supply unit 85.

[0047] The first acetic acid supply unit 81 includes an acetic acid supply source 81a, a supply path 81b, a temperature adjustment unit 81c, and a metering pump 81d.

[0048] Supply path 81b connects acetic acid supply source 81a and outer bath 32. Temperature adjustment unit 81c is, for example, an electronic thermostat, and adjusts the temperature of the acetic acid aqueous solution flowing through supply path 81b to a temperature of 10°C or higher and 40°C or lower. Preferably, temperature adjustment unit 81c adjusts the temperature of the acetic acid aqueous solution to a temperature of 10°C or higher and room temperature or lower. Metering pump 81d delivers a constant amount of acetic acid aqueous solution to supply path 81b located downstream of metering pump 81d.

[0049] The phosphoric acid supply unit 82 includes a phosphoric acid supply source 82a, a supply path 82b, a temperature adjustment unit 82c, and a metering pump 82d.

[0050] Supply path 82b connects phosphoric acid supply source 82a and outer tank 32. Temperature adjustment unit 82c is, for example, an electronic thermostat, and adjusts the temperature of the aqueous phosphoric acid solution flowing through supply path 82b to a temperature of 10°C or higher and 40°C or lower. Preferably, temperature adjustment unit 82c adjusts the temperature of the aqueous phosphoric acid solution to a temperature of 10°C or higher and room temperature or lower. Metering pump 82d delivers a constant amount of aqueous phosphoric acid solution to supply path 82b located downstream of metering pump 82d.

[0051] The nitric acid supply unit 83 includes a nitric acid supply source 83a, a supply path 83b, a temperature adjustment unit 83c, and a metering pump 83d.

[0052] Supply path 83b connects nitric acid supply source 83a and outer bath 32. Temperature adjustment unit 83c is, for example, an electronic thermostat, and adjusts the temperature of the aqueous nitric acid solution flowing through supply path 83b to a temperature of 10°C or higher and 40°C or lower. Preferably, temperature adjustment unit 83c adjusts the temperature of the aqueous nitric acid solution to a temperature of 10°C or higher and room temperature or lower. Metering pump 83d delivers a constant amount of aqueous nitric acid solution to supply path 83b located downstream of metering pump 83d.

[0053] The water supply unit 84 includes a water supply source 84a, a supply path 84b, a temperature adjustment unit 84c, and a metering pump 84d.

[0054] Supply path 84b connects water supply source 84a and outer bath 32. Temperature adjustment unit 84c is, for example, an electronic thermostat, and adjusts the temperature of water (e.g., deionized water) flowing through supply path 84b to a temperature of 10°C or higher and 40°C or lower. Preferably, temperature adjustment unit 84c adjusts the temperature of the water to a temperature of 10°C or higher and room temperature or lower. Metering pump 84d delivers a fixed amount of water to supply path 84b located downstream of metering pump 84d.

[0055] The second acetic acid supply unit 85 includes an acetic acid supply source 85a, a supply path 85b, a temperature adjustment unit 85c, a first on-off valve 85d, a flow meter 85e, a constant pressure valve 85f, a flow rate adjustment valve 85g, and a second on-off valve 85h.

[0056] The supply path 85b connects the acetic acid supply source 85a and the outer tank 32 of the treatment tank 3. A temperature adjustment unit 85c, a first on-off valve 85d, a flow meter 85e, a constant pressure valve 85f, a flow rate adjustment valve 85g, and a second on-off valve 85h are connected to the supply path 85b. In the embodiment, the temperature adjustment unit 85c, the first on-off valve 85d, the flow meter 85e, the constant pressure valve 85f, the flow rate adjustment valve 85g, and the second on-off valve 85h are provided in this order from the upstream side (the side closer to the acetic acid supply source 85a).

[0057] Temperature adjustment unit 85c is, for example, an electronic thermostat, and adjusts the temperature of the acetic acid aqueous solution flowing through supply path 85b to a temperature of 10° C. or higher and 40° C. or lower. Preferably, temperature adjustment unit 85c adjusts the temperature of the acetic acid aqueous solution to a temperature of 10° C. or higher and room temperature or lower.

[0058] First and second on-off valves 85d and 85h open and close supply path 85b. Flow meter 85e measures the flow rate of the acetic acid aqueous solution flowing through supply path 85b. Constant pressure valve 85f adjusts the pressure in supply path 85b downstream of constant pressure valve 85f. Flow rate adjustment valve 85g adjusts the flow rate of the acetic acid aqueous solution flowing through supply path 85b.

[0059] The temperature adjustment unit 85c, the first on-off valve 85d, the flow rate adjustment valve 85g, and the second on-off valve 85h are controlled by the control unit 71. For example, the control unit 71 controls the flow rate adjustment valve 85g based on the flow rate of the acetic acid aqueous solution measured by the flow meter 85e, thereby adjusting the flow rate of the acetic acid aqueous solution flowing through the supply path 85b to a preset flow rate. This allows the substrate processing apparatus 1 to accurately adjust the replenishment amount of the acetic acid aqueous solution in the discharge and replenishment process described below.

[0060] The flow rate of the aqueous acetic acid solution supplied from the second acetic acid supply unit 85 is greater than the flow rate of the aqueous acetic acid solution supplied from the first acetic acid supply unit 81.

[0061] The content of acetic acid in the etching solution is higher than that of other components. Specifically, the content of acetic acid in the etching solution is 50% or more. In contrast, the substrate processing apparatus 1 includes, in addition to the first acetic acid supply unit 81, a second acetic acid supply unit 85 that supplies more acetic acid than the first acetic acid supply unit 81, thereby preventing the time required to replenish acetic acid from becoming a bottleneck in the processing time during the discharge and replenishment process. In other words, the time required for the discharge and replenishment process can be shortened.

[0062] The substrate processing apparatus 1 further includes a control device 7. The control device 7 controls the operation of each part of the substrate processing apparatus 1. The control device 7 is, for example, a computer, and includes a control unit 71 and a storage unit 72.

[0063] The control unit 71 is a controller. The control unit 71 is realized, for example, by a CPU (Central Processing Unit) or an MPU (Micro Processing Unit) executing various programs stored in a storage device inside the control device 7 using RAM as a work area. The control unit 71 may also be realized, for example, by an integrated circuit such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array).

[0064] The control unit 71 has a computer-readable storage medium. The storage medium stores the above-mentioned programs for controlling various processes executed in the substrate processing apparatus 1. The programs may be stored in a computer-readable storage medium or may be installed into the storage medium of the control unit 71 from another storage medium. 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.

[0065] The storage unit 72 is realized by, for example, a semiconductor memory device such as a RAM (Random Access Memory) or a flash memory, or a storage device such as a hard disk or an optical disk. The storage unit 72 stores set values ​​(hereinafter referred to as "target concentrations") for the acetic acid concentration, phosphoric acid concentration, nitric acid concentration, and water concentration in the etching solution. The storage unit 72 also stores physical property values ​​for the aqueous acetic acid solution, aqueous phosphoric acid solution, aqueous nitric acid solution, and water supplied from each supply source 81a, 82a, 83a, 84a, and 85a. Specifically, the storage unit 72 stores the density and concentration of the aqueous acetic acid solution, aqueous phosphoric acid solution, aqueous nitric acid solution, and water. Note that the density of the aqueous solution is stored as both the density of the aqueous solution and the density excluding water (i.e., assuming a concentration of 100%). The storage unit 72 also stores the concentration of each component in the etching solution supplied from the etching solution supply unit 6.

[0066] <Specific operation of the substrate processing apparatus> Next, specific operations of the substrate processing apparatus 1 according to the embodiment will be described with reference to Figures 6 to 8. First, an overview of the liquid exchange process, concentration adjustment process, and discharge replenishment process performed by the substrate processing apparatus 1 according to the embodiment will be described with reference to Figure 6.

[0067] 6 is a diagram illustrating an outline of the liquid exchange process, the concentration adjustment process, and the discharge and replenishment process performed by the substrate processing apparatus 1 according to this embodiment. The graph shown in FIG. 6 is a schematic diagram illustrating the change over time in the water concentration of the etching liquid stored in the processing tank 3.

[0068] 6, a liquid exchange process is first performed in the substrate processing apparatus 1. In the liquid exchange process, the control unit 71 supplies an etching liquid from the etching liquid supply unit 6 to the empty processing tank 3. The etching liquid supply unit 6 supplies an etching liquid having a water concentration lower than the target concentration ("initial concentration" shown in FIG. 6) to the processing tank 3 (time t1).

[0069] Next, in the substrate processing apparatus 1, a concentration adjustment process is performed to adjust the concentration of the etching solution stored in the processing tank 3. In the concentration adjustment process, the control unit 71 individually supplies each component of the etching solution from the individual supply unit 8 to the processing tank 3 so that the concentration of each component of the etching solution reaches the target concentration. As a result, the water concentration of the etching solution stored in the processing tank 3 reaches the target concentration (time t2). Thereafter, multiple wafers W are immersed in the processing tank 3, and etching of the molybdenum film 11 formed on the surface of the wafers W is initiated.

[0070] As described above, the water concentration of the etching solution according to the embodiment increases over time. When the water concentration exceeds a threshold value, the control unit 71 performs a discharge and replenishment process. In the discharge and replenishment process, the control unit 71 discharges a portion of the etching solution stored in the processing tank 3 from the processing tank 3, and replenishes the processing tank 3 with acetic acid, phosphoric acid, and nitric acid from the supply unit 5. In this way, by discharging a portion of the etching solution stored in the processing tank 3 from the processing tank 3 and replenishing the processing tank 3 with acetic acid, phosphoric acid, and nitric acid, the concentrations of each component of the etching solution, including the water concentration, are readjusted to the target concentrations (time t3).

[0071] The substrate processing apparatus 1 repeats the above-described discharge and replenishment process each time the moisture concentration exceeds the threshold value until the next liquid exchange process is performed. This suppresses an increase in the moisture concentration of the etching solution. In other words, it suppresses an increase in the etching rate of the etching solution for the molybdenum film 11. Therefore, the substrate processing apparatus 1 according to this embodiment can stably etch the molybdenum film 11 formed on the wafer W.

[0072] Next, specific processing procedures of the above-mentioned liquid exchange process, concentration adjustment process, and discharge and replenishment process will be described with reference to Figures 7 and 8. First, the procedures of the liquid exchange process and concentration adjustment process will be described with reference to Figure 7. Figure 7 is a flowchart showing the procedures of the liquid exchange process and concentration adjustment process according to the embodiment.

[0073] 7, the control unit 71 performs a liquid exchange process (step S101). Specifically, the control unit 71 first opens the on-off valve 34b to drain all of the etching liquid stored in the processing tank 3. Thereafter, the control unit 71 closes the on-off valve 34b. Note that if no etching liquid is stored in the processing tank 3, the above process is omitted.

[0074] Next, the control unit 71 opens the first on-off valve 6d and the second on-off valve 6h of the etching liquid supply unit 6 to supply the etching liquid from the etching liquid supply unit 6 to the outer tank 32 of the processing tank 3. The etching liquid supplied to the outer tank 32 is supplied to the inner tank 31 via the circulation unit 33. After that, the inner tank 31 is filled with the etching liquid and the etching liquid overflows from the inner tank 31, causing the etching liquid to be stored in the outer tank 32 as well. When the control unit 71 determines, based on a signal from the liquid level sensor 35, that the liquid level of the etching liquid in the outer tank 32 has reached a predetermined position, it closes the first on-off valve 6d and the second on-off valve 6h to stop supplying the etching liquid to the processing tank 3.

[0075] The etching liquid supply unit 6 is provided with a constant pressure valve 6f, which limits the flow rate of the etching liquid flowing through the supply path 6b to a constant flow rate. Furthermore, in the liquid exchange process, the control unit 71 controls the flow rate adjustment valve 6g based on the flow rate of the etching liquid measured by the flow meter 6e, thereby adjusting the flow rate of the etching liquid flowing through the supply path 6b to a preset flow rate. This allows the substrate processing apparatus 1 to appropriately control the input amount of the etching liquid in the liquid exchange process.

[0076] Next, the control unit 71 determines whether the water concentration of the etching liquid stored in the processing tank 3 is equal to the target concentration (step S102). Specifically, the control unit 71 acquires the water concentration of the etching liquid stored in the processing tank 3 based on a signal from the concentration sensor 33f. Then, the control unit 71 compares the acquired water concentration with the target water concentration stored in the memory unit 72 and determines whether the two match.

[0077] In step S102, if the water concentration of the etching liquid stored in the processing tank 3 is not equal to the target concentration (step S102), the control unit 71 shifts the process to step S103. In the embodiment, the water concentration of the etching liquid supplied from the etching liquid supply unit 6 is lower than the target concentration. For this reason, the process always shifts from step S101 to step S103. Therefore, in such a case, the determination process of step S102 may be omitted.

[0078] In step S103, the control unit 71 calculates the amount of each component to be replenished.

[0079] First, the control unit 71 acquires the concentration of each component of the etching solution from the measurement result of the concentration sensor 33f. The control unit 71 also acquires the amount of etching solution stored in the processing tank 3 from the measurement result of the liquid level sensor 35. The control unit 71 also acquires the target amount of etching solution and the target concentration of each component stored in the memory unit 72. Then, the control unit 71 determines the replenishment amounts of acetic acid, phosphoric acid, nitric acid, and water based on the acquired information.

[0080] Here, a method for determining the replenishment amounts of acetic acid, phosphoric acid, nitric acid and water will be specifically described.

[0081] The total amount of etching solution immediately after the liquid exchange process is defined as V (L). V can be obtained from the measurement results of the liquid level sensor 35. Furthermore, the amount of acetic acid contained in the etching solution immediately after the liquid exchange process is defined as A (L), and the acetic acid concentration is defined as a (wt%). Similarly, the amount and concentration of phosphoric acid contained in the etching solution immediately after the liquid exchange process are defined as B (L) and b (wt%), respectively, the amount and concentration of nitric acid are defined as C (L) and c (wt%), respectively, and the amount and concentration of water are defined as D (L) and d (wt%), respectively. a to d can be obtained from the measurement results of the concentration sensor 33f.

[0082] The total amount of etching solution immediately after the solution exchange process, V(L), can be expressed by the following formula (1).

[0083]

number

[0084] The acetic acid concentration a (wt%), phosphoric acid concentration b (wt%), and nitric acid concentration c (wt%) in the etching solution immediately after the solution exchange process can be expressed by the following formulas (2) to (4), respectively.

[0085]

number

[0086]

number

[0087]

number

[0088] Here, "D PA "," "D PB"," "D PC "," "D PD " are the densities of acetic acid, phosphoric acid, nitric acid, and water, respectively, and are stored in advance in the storage unit 72. Also, "Total cont (wt%)" is the total value of the acetic acid concentration, phosphoric acid concentration, nitric acid concentration, and water concentration.

[0089] The control unit 71 solves the simultaneous equations consisting of these formulas (1) to (4) to calculate the unknown values ​​A to D, i.e., the amount of acetic acid A (L), the amount of phosphoric acid B (L), the amount of nitric acid C (L), and the amount of water D (L) contained in the etching solution immediately after the solution change.

[0090] Next, the total volume of the etching solution after the concentration adjustment process is defined as V'(L). Furthermore, the amount of acetic acid contained in the etching solution after the concentration adjustment process is defined as A'(L), and the acetic acid concentration is defined as a'(wt%). Similarly, the amount and concentration of phosphoric acid contained in the etching solution immediately after the concentration adjustment process are defined as B'(L) and b'(wt%), respectively, the amount and concentration of nitric acid are defined as C'(L) and c'(wt%), respectively, and the amount and concentration of water are defined as D'(L) and d'(wt%), respectively. V' and A' to D' are unknown values. Meanwhile, a' to d' correspond to the target concentrations for each component stored in the memory unit 72. Therefore, a' to d' are known values.

[0091] In the concentration adjustment process, the amount (replenishment amount) of the acetic acid solution replenished to the treatment tank 3 and the concentration thereof are respectively S A (L), C A Similarly, the replenishment amount and concentration of the phosphoric acid aqueous solution are S B (L), C B (wt%), the replenishment amount and concentration of the nitric acid aqueous solution are S C (L), C C (wt%), the amount and concentration of water replenished are S D (L), C D (wt%). S A ~S D is an unknown value, and C A ~C D is a known value stored in advance in the storage unit 72. D(wt%) is 100%.

[0092] The total amount of etching solution V'(L) after the concentration adjustment process can be expressed by the following formula (5).

[0093]

number

[0094] Furthermore, the amounts A' to D' of the components contained in the etching solution after the concentration adjustment treatment can be expressed by the following formulas (6) to (9).

[0095]

number

[0096]

number

[0097]

number

[0098]

number

[0099] Here, "D G " is the density of the etching solution after concentration adjustment. D G is a known value stored in the storage unit 72. G When the target concentrations a' to d' of each component are changed, D is changed according to the changed a' to d'. A "," "D B "," "D C "," "D D " are the densities of the acetic acid aqueous solution, phosphoric acid aqueous solution, nitric acid aqueous solution, and water replenished in the treatment tank 3, respectively. D A ,D B ,D C and DD is a known value stored in the storage unit 72. D is D PD In equations (6) to (8), S A ~S C is multiplied by a coefficient to calculate the amount of each component in the aqueous solution. The amount of water excluded in equations (6) to (8) is reflected in equation (9).

[0100] The control unit 71 solves the simultaneous equations (6) to (9) to determine the replenishment amount S of the acetic acid aqueous solution. A (L), replenishment volume of phosphoric acid aqueous solution S B (L), nitric acid solution replenishment volume S C (L) and water replenishment volume S D Calculate (L).

[0101] In this way, the control unit 71 determines the replenishment amount S of each component (aqueous solution for acetic acid, phosphoric acid, and nitric acid) in the concentration adjustment process based on the measurement results (V and a to d) of the liquid level sensor 35 and the concentration sensor 33f. A ~S D can be determined.

[0102] Next, the control unit 71 replenishes the treatment tank 3 with the determined replenishment amounts of the acetic acid aqueous solution, the phosphoric acid aqueous solution, the nitric acid aqueous solution, and water (step S104). Specifically, the control unit 71 starts replenishing the acetic acid aqueous solution from the second acetic acid supply unit 85 to the outer tank 32 of the treatment tank 3 by opening the first on-off valve 85d and the second on-off valve 85h of the second acetic acid supply unit 85.

[0103] As described above, the etching solution according to the embodiment contains 50% or more acetic acid. Therefore, the amount of acetic acid solution replenished in the concentration adjustment process is greater than that of other components. In contrast, in the substrate processing apparatus 1 according to the embodiment, the acetic acid solution is replenished using an acetic acid solution with a higher flow rate than the first acetic acid supply unit 81, thereby reducing the time required to replenish the acetic acid solution and ultimately reducing the time required for the concentration adjustment process.

[0104] The control unit 71 starts replenishing the acetic acid aqueous solution from the second acetic acid supply unit 85 to the outer tank 32 of the treatment tank 3 by opening the first on-off valve 85d and the second on-off valve 85h of the second acetic acid supply unit 85. Then, based on the measurement result of the liquid level sensor 35, the control unit 71 determines whether the liquid level in the outer tank 32 reaches the replenishing amount S determined in step S103. A When it is determined that the temperature has risen by a distance corresponding to the temperature, the first on-off valve 85d and the second on-off valve 85h are closed, and the replenishment of the treatment tank 3 with the acetic acid aqueous solution is stopped.

[0105] The second acetic acid supply unit 85 is provided with a constant pressure valve 85f, which limits the flow rate of the acetic acid aqueous solution flowing through the supply path 85b to a constant flow rate. The control unit 71 also controls the flow rate adjustment valve 85g based on the flow rate of the acetic acid aqueous solution measured by the flow meter 85e, thereby adjusting the flow rate of the acetic acid aqueous solution flowing through the supply path 85b to a preset flow rate. This allows the substrate processing apparatus 1 to appropriately control the input amount of the acetic acid aqueous solution in the concentration adjustment process.

[0106] Although an example in which the aqueous acetic acid solution is replenished from the second acetic acid supply unit 85 has been described here, the control unit 71 may replenish the aqueous acetic acid solution from the first acetic acid supply unit 81. Furthermore, the control unit 71 may replenish the aqueous acetic acid solution from both the first acetic acid supply unit 81 and the second acetic acid supply unit 85.

[0107] Furthermore, the control unit 71 controls the metering pump 82d of the phosphoric acid supply unit 82 to supply the replenishment amount S determined in step S103. B The control unit 71 controls the metering pump 83d of the nitric acid supply unit 83 to supply the phosphoric acid aqueous solution from the phosphoric acid supply unit 82 to the outer tank 32. C The nitric acid aqueous solution is supplied from the nitric acid supply unit 83 to the outer tank 32. The control unit 71 also controls the metering pump 84d of the water supply unit 84 to supply the replenishment amount S D The water is supplied from the water supply unit 84 to the outer tub 32 .

[0108] In this way, the control unit 71 controls the supply unit 5 to adjust the replenishment amount S determined in step S103. A ~S D The aqueous acetic acid solution, the aqueous phosphoric acid solution, the aqueous nitric acid solution, and water are replenished to the treatment tank 3 from the supply unit 5. This allows the etching solution in which the concentrations of each component have been adjusted to the target concentrations a' to d' to be stored in the treatment tank 3.

[0109] When the process of step S104 is completed, or when it is determined in step S102 that the water concentration is equal to the target concentration (step S102, Yes), the control unit 71 shifts the process to an etching process (step S105).

[0110] Next, a specific procedure for the discharge and replenishment process will be described with reference to Fig. 8. Fig. 8 is a flowchart showing the procedure for the discharge and replenishment process.

[0111] 8, prior to the etching process, the control unit 71 determines whether the water concentration of the etching solution stored in the processing tank 3 is less than a threshold value (step S201). Specifically, the control unit 71 acquires the water concentration of the etching solution stored in the processing tank 3 based on a signal from the concentration sensor 33f. Then, the control unit 71 compares the acquired water concentration with the threshold value stored in the memory unit 72 to determine whether the water concentration is less than the threshold value.

[0112] In step S201, when it is determined that the moisture concentration is less than the threshold value (step S201, Yes), the control unit 71 executes an etching process (step S202).

[0113] Specifically, the control unit 71 uses the holder 4 to hold the plurality of wafers W, and then moves the holder 4 to a processing position using a lifting mechanism (not shown), thereby immersing the plurality of wafers W held by the holder 4 in the etching solution stored in the processing tank 3. Thereafter, the control unit 71 moves the holder 4 to a retracted position using a lifting mechanism (not shown), and then transports the plurality of wafers W to a processing tank for rinsing processing provided in the substrate processing apparatus 1.

[0114] When the etching process is completed, the control unit 71 determines whether or not the liquid exchange condition is satisfied (step S203). The liquid exchange condition can be set arbitrarily. For example, the liquid exchange condition may be the number of wafers W etched after the previous liquid exchange process, or the elapsed time since the previous liquid exchange process.

[0115] If the liquid exchange condition is not satisfied in step S203 (step S203, No), the control unit 71 returns the process to step S201. On the other hand, if it is determined that the liquid exchange condition is satisfied (step S203, Yes), the control unit 71 proceeds to the liquid exchange process (step S204). That is, the control unit 71 proceeds to the process of step S101 shown in FIG. 7.

[0116] On the other hand, if the moisture concentration is not less than the threshold value in step S201 (step S201, No), that is, if the moisture concentration exceeds the threshold value, the control unit 71 proceeds to step S205 (step S205). In step S205, the control unit 71 calculates the discharge amount and the replenishment amount.

[0117] Here, the total volume of the etching solution at the time when it is determined that the water concentration has exceeded the threshold is defined as V" (L). V" can be obtained from the measurement results of the liquid level sensor 35. Furthermore, the acetic acid concentration of the etching solution at the time when it is determined that the water concentration has exceeded the threshold is defined as a" (wt%), and the amount of acetic acid is defined as A" (L). Similarly, the phosphoric acid concentration and amount of phosphoric acid of the etching solution at the time when it is determined that the water concentration has exceeded the threshold are defined as b" (wt%) and B" (L), respectively, the nitric acid concentration and amount of nitric acid are defined as c" (wt%) and C" (L), respectively, and the water concentration and amount of water are defined as d" (wt%) and D" (L), respectively. a" to d" can be obtained from the measurement results of the concentration sensor 33f. Furthermore, A" to D" can be calculated using V" and a" to d".

[0118] In addition, the amount of etching solution discharged from the treatment tank 3 (discharge amount) is V PD V PDis an unknown value. Furthermore, the total volume of the etching solution after the discharge and replenishment process is defined as V0. V0 is a set value previously stored in the memory unit 72, i.e., a known value. Furthermore, the acetic acid concentration, phosphoric acid concentration, nitric acid concentration, and water concentration of the etching solution after the discharge and replenishment process are defined as a0 (wt%), b0 (wt%), c0 (wt%), and d0 (wt%), respectively. a0 to d0 are set values ​​stored in the memory unit 72 as target concentrations, i.e., known values. In other words, a0 to d0 are the same values ​​as a' to d', respectively. Furthermore, the amounts of acetic acid, phosphoric acid, nitric acid, and water of the etching solution after the discharge and replenishment process are defined as A0 (L), B0 (L), C0 (L), and D0 (L), respectively. A0 to D0 can be calculated from V0 and a0 to d0.

[0119] In addition, the amount of etching solution replenished from the etching solution supply unit 6 to the processing tank 3 in the discharge and replenishment process is S GE In the discharge and replenishment treatment, the amounts of acetic acid aqueous solution, phosphoric acid aqueous solution, nitric acid aqueous solution and water replenished from the individual supply units 8 to the treatment tank 3 are respectively represented by S' A (L), S' B (L), S' C (L), S' D (L). S GE , S' A , S' B , S' C , S' D is an unknown value.

[0120] The total amount V0 of the etching solution after the discharge and replenishment process can be expressed by the following formula (10).

[0121]

number

[0122] The amount of acetic acid A0, the amount of phosphoric acid B0 (L), the amount of nitric acid C0 (L), and the amount of water D0 (L) in the etching solution after the discharge and replenishment process can be expressed by the following formulas (11) to (14), respectively.

[0123]

number

[0124]

number

[0125]

number

[0126]

number

[0127] Here, "C GA "," "C GB "," "C GC "," "C GD " are the acetic acid concentration, phosphoric acid concentration, nitric acid concentration and water concentration of the etching solution supplied from the etching solution supply unit 6, respectively. C GA ,C GB ,C GC ,C GD is a set value stored in advance in the storage unit 72, i.e., a known value. GD corresponds to the “initial concentration” shown in FIG.

[0128] Furthermore, in the discharge and replenishment process, the main purpose of which is to reduce the water concentration, water is not replenished from the water supply unit 84 to the treatment tank 3. Therefore, the amount of water replenished S' from the supply unit 84 to the treatment tank 3 in the discharge and replenishment process is D can be expressed by the following equation (15).

[0129]

number

[0130] The control unit 71 solves the simultaneous equations (11) to (15) to obtain the unknown value V PD ,S GE,S' A ,S' B ,S' C That is, the control unit 71 calculates the discharge amount V of the etching solution in the discharge and replenishment process. PD The control unit 71 also calculates the replenishment amount S of the etching solution in the discharge and replenishment process. GE (L), replenishment volume S' of acetic acid solution A (L), replenishment volume S' of phosphoric acid aqueous solution B (L) and the replenishment volume S' of the nitric acid solution C Calculate (L).

[0131] In this way, in the discharge and replenishment process, the control unit 71 determines the discharge amount V of the etching solution from the processing tank 3 based on the concentrations a" to d" of each component measured by the concentration sensor 33f, the amount V" of the etching solution measured by the liquid level sensor 35, the preset target amount V0 of the etching solution, and the preset target concentrations a0 to d0 of each component. PD and the amount of acetic acid, phosphoric acid, and nitric acid replenished to the treatment tank 3 (S GE ,S' A ,S' B ,S' C ) is determined.

[0132] Next, the control unit 71 performs a process of discharging the etching solution of the determined discharge amount from the processing tank 3 (step S206). Specifically, the control unit 71 starts discharging the etching solution from the processing tank 3 by opening the on-off valve 34b of the drainage unit 34. Then, based on the measurement result of the liquid level sensor 35, the control unit 71 determines whether the liquid level in the outer tank 32 reaches the discharge amount V determined in step S205. PD When it is determined that the temperature has decreased by a distance corresponding to the temperature, the on-off valve 34b is closed to stop the discharge of the etching solution from the processing tank 3.

[0133] As described above, in the substrate processing apparatus 1, the drainage speed is slowed by providing the flow rate adjustment valve 34c in the drainage path 34a, so that the amount of etching liquid discharged from the processing tank 3 can be controlled with high precision.

[0134] Next, the control unit 71 performs a process of replenishing the treatment tank 3 with acetic acid, phosphoric acid, and nitric acid.

[0135] For example, the control unit 71 opens the first on-off valve 6d and the second on-off valve 6h of the etching liquid supply unit 6 to replenish the etching liquid from the etching liquid supply unit 6 to the outer tank 32 of the processing tank 3. Based on the measurement result of the liquid level sensor 35, the control unit 71 determines whether the liquid level in the outer tank 32 reaches the replenishment amount S determined in step S205. GE When it is determined that the temperature has risen by a distance corresponding to the temperature, the first on-off valve 6d and the second on-off valve 6h are closed, and the replenishment of the etching liquid into the processing tank 3 is stopped.

[0136] The etching liquid supply unit 6 is provided with a constant pressure valve 6f, which limits the flow rate of the etching liquid flowing through the supply path 6b to a constant flow rate. Furthermore, in the liquid exchange process, the control unit 71 controls the flow rate adjustment valve 6g based on the flow rate of the etching liquid measured by the flow meter 6e, thereby adjusting the flow rate of the etching liquid flowing through the supply path 6b to a preset flow rate. This allows the substrate processing apparatus 1 to appropriately control the input amount of the etching liquid in the liquid exchange process.

[0137] Next, the control unit 71 opens the first on-off valve 85d and the second on-off valve 85h of the second acetic acid supply unit 85 to start replenishing the acetic acid aqueous solution from the second acetic acid supply unit 85 to the outer tank 32 of the treatment tank 3. Then, based on the measurement result of the liquid level sensor 35, the control unit 71 determines whether the liquid level in the outer tank 32 reaches the replenishing amount S' determined in step S205. A When it is determined that the temperature has risen by a distance corresponding to the temperature, the first on-off valve 85d and the second on-off valve 85h are closed, and the replenishment of the treatment tank 3 with the acetic acid aqueous solution is stopped.

[0138] The second acetic acid supply unit 85 is provided with a constant pressure valve 85f, which limits the flow rate of the acetic acid aqueous solution flowing through the supply path 85b to a constant flow rate. The control unit 71 also controls the flow rate adjustment valve 85g based on the flow rate of the acetic acid aqueous solution measured by the flow meter 85e, thereby adjusting the flow rate of the acetic acid aqueous solution flowing through the supply path 85b to a preset flow rate. As a result, the substrate processing apparatus 1 controls the replenishment rate S' of the acetic acid aqueous solution. A can be appropriately controlled.

[0139] Although an example in which the aqueous acetic acid solution is replenished from the second acetic acid supply unit 85 has been described here, the control unit 71 may replenish the aqueous acetic acid solution from the first acetic acid supply unit 81. Furthermore, the control unit 71 may replenish the aqueous acetic acid solution from both the first acetic acid supply unit 81 and the second acetic acid supply unit 85.

[0140] Furthermore, the control unit 71 controls the metering pump 82d of the phosphoric acid supply unit 82 to supply the replenishment amount S' determined in step S205. B The phosphoric acid aqueous solution is supplied from the phosphoric acid supply unit 82 to the outer tank 32. The control unit 71 also controls the metering pump 83d of the nitric acid supply unit 83 to supply the replenishment amount S' determined in step S205. C The aqueous nitric acid solution is supplied from the nitric acid supply unit 83 to the outer tank 32 .

[0141] In this way, the control unit 71 controls the supply unit 5 to adjust the replenishment amount S determined in step S205. GE ,S' A ~S' D The acetic acid, phosphoric acid, and nitric acid are replenished from the supply unit 5 to the treatment tank 3. This allows the concentrations of each component to be readjusted to the target concentrations a0 to d0. In other words, the water concentration, which has increased over time, can be reduced to the target concentration.

[0142] After completing the process of step S207, the control unit 71 waits for a preset time to stabilize the concentration of the etching solution (step S208). In step S208, the control unit 71 circulates the etching solution using the circulation unit 33. This agitates the etching solution, stabilizing its concentration. After completing the process of step S208, the control unit 71 returns the process to step S201.

[0143] As described above, a substrate processing apparatus according to an embodiment (for example, the substrate processing apparatus 1) etches a molybdenum film on a substrate (for example, the wafer W) having a device structure including multiple layers of a multilayer film including a molybdenum film (for example, the molybdenum film 11). The substrate processing apparatus includes a processing tank (for example, the processing tank 3), a supply unit (for example, the supply unit 5), an on-off valve (for example, the on-off valve 34b), a concentration measurement unit (for example, the concentration sensor 33f), a liquid volume measurement unit (for example, the liquid level sensor 35), and a control unit (for example, the control unit 71). The processing tank stores an etching solution containing acetic acid, phosphoric acid, nitric acid, and water as components. The supply unit supplies the acetic acid, phosphoric acid, nitric acid, and water to the processing tank individually or as an etching solution. The on-off valve opens and closes a drainage path (for example, the drainage path 34a) of the processing tank. The concentration measurement unit measures the concentration of each component of the etching solution stored in the processing tank. The liquid volume measuring unit measures the volume of the etching solution stored in the treatment tank. The control unit controls the on-off valve and the supply unit to perform a discharge and replenishment process in which a portion of the etching solution is discharged from the treatment tank and acetic acid, phosphoric acid, and nitric acid are replenished to the treatment tank. In the discharge and replenishment process, the control unit determines the amount of etching solution to be discharged from the treatment tank and the amount of acetic acid, phosphoric acid, and nitric acid to be replenished to the treatment tank based on the concentrations of each component measured by the concentration measuring unit, the amount of etching solution measured by the liquid volume measuring unit, a preset target amount of etching solution, and a preset target concentration of each component. The control unit controls the on-off valve to discharge the determined amount of etching solution from the treatment tank and controls the supply unit to replenish the determined replenishment amounts of acetic acid, phosphoric acid, and nitric acid to the treatment tank.

[0144] This makes it possible to suppress an increase in the water concentration of the etching solution over time. By suppressing the increase in the water concentration in this way, an increase in the etching rate of the etching solution for the molybdenum film is suppressed, so that the substrate processing apparatus according to the embodiment can stably etch the molybdenum film formed on the substrate.

[0145] The control unit may execute a discharge and replenishment process when the moisture concentration measured by the concentration measurement unit exceeds a threshold value. This allows the moisture concentration of the etching solution to be appropriately controlled. That is, an increase in the etching rate of the etching solution for the molybdenum film can be appropriately suppressed.

[0146] The control unit may control the supply unit to execute a liquid exchange process in which an etching solution having a water concentration lower than a target concentration is supplied to an empty processing tank, and a concentration adjustment process in which the concentration of the etching solution after the liquid exchange process is adjusted. In this case, in the concentration adjustment process, the control unit may determine the amounts of acetic acid, phosphoric acid, nitric acid, and water to be replenished to the processing tank based on the concentrations of each component measured by the concentration measurement unit, the amount of etching solution measured by the liquid volume measurement unit, the target amount of etching solution, and the target concentrations of each component, and control the supply unit to replenish the determined amounts of acetic acid, phosphoric acid, nitric acid, and water from the supply unit to the processing tank.

[0147] This allows the concentration of each component in the etching solution after the solution exchange process to be adjusted to the target concentration.

[0148] The supply unit may include an individual supply unit that individually supplies acetic acid, phosphoric acid, nitric acid, and water to the treatment tank, and an etching solution supply unit that supplies an etching solution to the treatment tank. In this case, the individual supply units may include a first acetic acid supply unit that supplies acetic acid at a first flow rate, and a second acetic acid supply unit that supplies acetic acid at a second flow rate that is higher than the first flow rate.

[0149] This prevents the time required for replenishment of acetic acid from becoming a bottleneck in the processing time of the discharge and replenishment process, in other words, the time required for the discharge and replenishment process can be shortened.

[0150] The second acetic acid supply unit may be equipped with a flow rate adjustment valve, which allows the amount of acetic acid replenished to be appropriately controlled.

[0151] The etching liquid supply unit may be provided with a flow rate adjusting valve, which allows the amount of etching liquid replenished to be appropriately controlled.

[0152] The supply unit may include a temperature adjustment unit that adjusts the temperatures of the acetic acid, phosphoric acid, nitric acid, and water. In this case, the control unit may control the temperature adjustment unit to adjust the temperatures of the acetic acid, phosphoric acid, nitric acid, and water to 10°C or higher and 40°C or lower.

[0153] This can prevent the etching rate of the etching solution for the molybdenum film from becoming too high, and also can prevent the acetic acid from solidifying.

[0154] 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]

[0155] 1. Substrate processing equipment 3 Treatment tank 4 Holding part 5 Supply section 6 Etching solution supply unit 7 Control Device 8 Individual supply section 10 Polysilicon film 11 Molybdenum film 12 Silicon oxide film 31 Inner tank 32 Outer tank 33 Circulation section 33a Circulation path 33f concentration sensor 34 Drainage section 34a Drainage channel 34b On-off valve 34c Flow control valve 35 Liquid level sensor 71 Control Unit 72 Memory section 81 First Acetic Acid Supply Section 82 Phosphate supply unit 83 Nitric acid supply section 84 Water supply section 85 Second Acetic Acid Supply Section W wafer

Claims

1. 1. A substrate processing apparatus for etching a molybdenum film on a substrate having a device structure including a multi-layer film including a molybdenum film in multiple stages, the apparatus comprising: a treatment tank for storing an etching solution containing acetic acid, phosphoric acid, nitric acid, and water as components; a supply unit that supplies acetic acid, phosphoric acid, nitric acid, and water individually or as the etching solution to the treatment tank; an on-off valve for opening and closing a drainage path of the treatment tank; a concentration measuring unit for measuring the concentration of each of the components of the etching solution stored in the treatment tank; a liquid amount measuring unit that measures the amount of the etching liquid stored in the treatment tank; a control unit that controls the on-off valve and the supply unit to perform a discharge and replenishment process of discharging a part of the etching solution from the treatment tank and replenishing the treatment tank with acetic acid, phosphoric acid, and nitric acid; Equipped with In the discharge and replenishment process, the control unit determining a discharge amount of the etching solution from the treatment tank and a replenishment amount of acetic acid, phosphoric acid, and nitric acid to the treatment tank based on the concentration of each of the components measured by the concentration measuring unit, the amount of the etching solution measured by the liquid amount measuring unit, a predetermined target amount of the etching solution, and a predetermined target concentration of each of the components; controlling the on-off valve to discharge the etching solution from the treatment tank in the determined discharge amount; The substrate processing apparatus controls the supply unit to replenish the processing bath with the determined replenishment amounts of acetic acid, phosphoric acid, and nitric acid.

2. The control unit The substrate processing apparatus according to claim 1 , wherein the discharge and replenishment process is performed when the moisture concentration measured by the concentration measuring unit exceeds a threshold value.

3. The control unit a liquid exchange process in which the supply unit is controlled to supply the etching liquid having a water concentration lower than the target concentration to the empty processing tank; a concentration adjustment process for adjusting the concentration of the etching solution after the solution exchange process; Run In the density adjustment process, the control unit determining the amounts of acetic acid, phosphoric acid, nitric acid, and water to be replenished to the treatment tank based on the concentrations of the components measured by the concentration measuring unit, the amount of the etching solution measured by the liquid amount measuring unit, the target amount of the etching solution, and the target concentrations of the components; 3. The substrate processing apparatus according to claim 1, wherein the supply unit is controlled to supply the determined amounts of acetic acid, phosphoric acid, nitric acid, and water to the processing bath from the supply unit.

4. The supply unit includes: an individual supply unit that individually supplies acetic acid, phosphoric acid, nitric acid, and water to the treatment tank; an etching solution supply unit that supplies the etching solution to the processing tank; Equipped with The individual supply unit includes: a first acetic acid supply unit that supplies acetic acid at a first flow rate; a second acetic acid supply unit that supplies acetic acid at a second flow rate that is greater than the first flow rate; The substrate processing apparatus according to claim 1 , further comprising:

5. The substrate processing apparatus according to claim 4 , wherein the second acetic acid supply unit includes a flow rate adjustment valve.

6. The substrate processing apparatus according to claim 4 , wherein the etching liquid supply unit includes a flow rate adjustment valve.

7. the supply unit includes a temperature adjusting unit that adjusts the temperatures of acetic acid, phosphoric acid, nitric acid, and water; 3 . The substrate processing apparatus according to claim 1 , wherein the control unit controls the temperature adjustment unit to adjust the temperatures of the acetic acid, phosphoric acid, nitric acid, and water to 10° C. or higher and 40° C. or lower.

8. 1. A substrate processing method for etching a molybdenum film on a substrate having a device structure including a multi-layer film including a molybdenum film in multiple stages, the method comprising: measuring the concentration of each component of an etching solution containing acetic acid, phosphoric acid, nitric acid, and water as components stored in a treatment tank; measuring the amount of the etching solution stored in the treatment tank; performing a discharge and replenishment process of discharging a portion of the etching solution from the treatment tank and replenishing the treatment tank with acetic acid, phosphoric acid, and nitric acid; Including, Executing the discharge and replenishment process includes: determining a discharge amount of the etching solution from the treatment tank and a replenishment amount of acetic acid, phosphoric acid, and nitric acid to the treatment tank based on the concentration of each of the components measured in measuring the concentration, the amount of the etching solution measured in measuring the amount of the etching solution, a predetermined target amount of the etching solution, and a predetermined target concentration of each of the components; Discharging the etching solution in the determined discharge amount from the treatment tank; the substrate processing method further comprising replenishing the processing bath with the determined amounts of acetic acid, phosphoric acid, and nitric acid.

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