SUBSTRATE PROCESSING APPARATUS AND SUBSTRATE PROCESSING METHOD

Abstract

To stably execute an etching processing of a substrate.SOLUTION: A substrate processing apparatus according to an aspect of a present disclosure comprises: a processing tank that immerses a substrate into a processing liquid containing a silicic acid compound and a phosphoric acid and processes it; a liquid amount sensor that measures an accumulation amount of the processing liquid to be accumulated in the processing tank; a concentration sensor that measures phosphoric acid concentration in the processing liquid accumulated in the processing tank; a phosphoric acid supply part that supplies a phosphoric acid aqueous solution containing the phosphoric acid in the processing tank; a pure water supply part that supplies pure water to the processing tank; a discharge part that discharges the processing liquid from the processing tank; and a control part that controls each part. Also, the control part includes: a discharge amount maintaining part that maintains a discharge amount per hour of the processing liquid from the discharge part at a predetermined value; and a supply amount control part that controls supply amounts of the phosphoric acid solution and the pure water respectively supplied to the processing tank from each of the phosphoric acid supply part and the pure water supply part so that the accumulation amount of the processing liquid in the processing tank and the phosphoric acid concentration are maintained at the predetermined values.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The disclosed embodiments relate to a substrate processing apparatus and a substrate processing method. [Background technology]

[0002] Conventionally, in a substrate processing system, a technique is known in which a nitride film formed on a substrate is etched by immersing the substrate in an aqueous solution of phosphoric acid (H3PO4) (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6118739 Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides a technique that enables stable etching of a substrate. [Means for solving the problem]

[0005] A substrate processing apparatus according to an aspect of the present disclosure includes a processing tank, a liquid volume sensor, a concentration sensor, a phosphoric acid supply unit, a pure water supply unit, a discharge unit, and a control unit. The processing tank processes a substrate by immersing it in a processing liquid containing a silicic acid compound and phosphoric acid. The liquid volume sensor measures the amount of the processing liquid stored in the processing tank. The concentration sensor measures the phosphoric acid concentration in the processing liquid stored in the processing tank. The phosphoric acid supply unit supplies an aqueous phosphoric acid solution containing phosphoric acid to the processing tank. The pure water supply unit supplies pure water to the processing tank. The discharge unit discharges the processing liquid from the processing tank. The control unit controls each unit. The control unit also includes a discharge amount maintenance unit and a supply amount control unit. The discharge amount maintenance unit maintains the discharge amount of the processing liquid per hour from the discharge unit at a given value. The supply amount control unit controls the supply amounts of the phosphoric acid aqueous solution and the pure water supplied from the phosphoric acid supply unit and the pure water supply unit to the treatment tank, respectively, so that the storage amount of the treatment liquid and the phosphoric acid concentration in the treatment tank are maintained at given values, respectively. Effect of the Invention

[0006] According to the present disclosure, a substrate etching process can be stably performed. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic block diagram showing a configuration of a substrate processing system according to an embodiment. [Diagram 2] FIG. 2 is a schematic block diagram showing the configuration of the etching processing apparatus according to the embodiment. [Diagram 3] FIG. 3 is a schematic block diagram showing the configuration of the etching processing apparatus according to the embodiment. [Figure 4] FIG. 4 is a block diagram showing the configuration of the control device according to the embodiment. [Diagram 5] FIG. 5 is a timing chart showing an example of transition of the discharge amount, the storage amount, and the supply amount in the substrate processing according to the embodiment. [Figure 6]FIG. 6 is a diagram showing an example of the balance between the supply amount and the discharge amount of each liquid in the concentration maintenance process in the reference example. [Figure 7] FIG. 7 is a diagram showing an example of the transition of the silicic acid concentration in the etching solution in the reference example. [Figure 8] FIG. 8 is a diagram showing an example of the balance between the supply amount and the discharge amount of each liquid in the concentration maintenance process according to the embodiment. [Figure 9] FIG. 9 is a schematic block diagram showing the configuration of an etching processing apparatus according to a modified example of the embodiment. [Figure 10] FIG. 10 is a flowchart showing an example of a procedure of a control process executed by the substrate processing system according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, with reference to the attached drawings, an embodiment of the substrate processing apparatus and substrate processing method disclosed in the present application will be described in detail. Note that the present disclosure is not limited to the following embodiment. It should be noted that the drawings are schematic, and the dimensional relationship of each element, the ratio of each element, and the like may differ from reality. Furthermore, there may be parts in which the dimensional relationship and ratio differ between the drawings.

[0009] 2. Description of the Related Art Conventionally, in a substrate processing system, a technique is known in which a nitride film formed on a substrate is etched by immersing the substrate in an aqueous solution of phosphoric acid (H3PO4).

[0010] For example, by immersing a substrate in an aqueous solution of phosphoric acid, it is possible to selectively etch the silicon nitride film out of a silicon nitride film (SiN) and a silicon oxide film (SiO2) laminated on the substrate.

[0011] Furthermore, in the etching process of the silicon nitride film, silicic acid compounds such as polysiloxane (hereinafter also simply referred to as "silicic acid") generated from the silicon nitride film dissolve in the etching solution.

[0012] In the etching process for the silicon nitride film, the etching rate varies depending on the concentration of silicic acid in the etching solution, so a concentration maintenance process may be performed to maintain the concentration of silicic acid in the etching solution at a given value.

[0013] Such concentration maintenance treatment is carried out, for example, by supplying an aqueous phosphoric acid solution to the treatment tank at a constant flow rate during the etching treatment, and controlling the discharge amount of the etching solution so that the amount of the etching solution stored in the treatment tank and the phosphoric acid concentration are maintained.

[0014] On the other hand, in such a concentration maintaining process, when the phosphoric acid concentration in the phosphoric acid aqueous solution supplied to the treatment tank changes, the silicic acid concentration in the etching solution may not be stably maintained, which makes it difficult to stably perform the etching process of the substrate.

[0015] Therefore, there is a need for a technology that overcomes the above-mentioned problems and enables stable etching of substrates.

[0016] <Configuration of the substrate processing system> First, a configuration of a substrate processing system 1 according to an embodiment will be described with reference to Fig. 1. Fig. 1 is a schematic block diagram showing a configuration of a substrate processing system 1 according to an embodiment. The substrate processing system 1 is an example of a substrate processing apparatus.

[0017] As shown in FIG. 1, a substrate processing system 1 according to the embodiment includes a carrier loading / unloading section 2, a lot forming section 3, a lot placing section 4, a lot transport section 5, a lot processing section 6, and a controller .

[0018] The carrier loading / unloading section 2 includes a carrier stage 20, a carrier transport mechanism 21, carrier stocks 22 and 23, and a carrier placement table 24.

[0019] The carrier stage 20 places multiple FOUPs H transported from outside. The FOUP H is a container that contains multiple (e.g., 25) wafers W arranged vertically in a horizontal position. The wafers W are an example of a substrate. The carrier transport mechanism 21 transports the FOUPs H between the carrier stage 20, carrier stocks 22 and 23, and a carrier mounting table 24.

[0020] A plurality of unprocessed wafers W are transferred from the FOUP H placed on the carrier mounting table 24 to the lot processing section 6 by the substrate transfer mechanism 30 described below. A plurality of processed wafers W are transferred from the lot processing section 6 to the FOUP H placed on the carrier mounting table 24 by the substrate transfer mechanism 30.

[0021] The lot formation section 3 has a substrate transport mechanism 30 and forms lots. A lot is composed of a plurality of (e.g., 50) wafers W that are simultaneously processed by combining wafers W accommodated in one or a plurality of FOUPs H. The plurality of wafers W that form one lot are arranged at regular intervals with their plate surfaces facing each other.

[0022] The substrate transfer mechanism 30 transfers a plurality of wafers W between the FOUP H placed on the carrier placement table 24 and the lot placement part 4.

[0023] The lot placement unit 4 has a lot transport table 40 on which a lot transported by the lot transport unit 5 between the lot formation unit 3 and the lot processing unit 6 is temporarily placed (on standby). The lot transport table 40 has an entrance side placement table 41 on which a lot formed in the lot formation unit 3 before being processed is placed, and an exit side placement table 42 on which a lot processed in the lot processing unit 6 is placed. A plurality of wafers W for one lot are placed in an upright position lined up in front of and behind each other on the entrance side placement table 41 and the exit side placement table 42.

[0024] The lot transport section 5 has a lot transport mechanism 50, and transports lots between the lot placement section 4 and the lot processing section 6 and inside the lot processing section 6. The lot transport mechanism 50 has rails 51, a movable body 52, and a substrate holder 53.

[0025] Rails 51 are arranged along the X-axis direction across lot mounting section 4 and lot processing section 6. Mobile body 52 is configured to be able to move along rails 51 while holding a plurality of wafers W. Substrate holder 53 is arranged on mobile body 52, and holds a plurality of wafers W lined up in front of and behind each other in an upright position.

[0026] The lot processing section 6 collectively performs processes such as etching, cleaning, and drying on one lot of multiple wafers W. In the lot processing section 6, two etching processing sections 60, a cleaning processing section 70, a cleaning processing section 80, and a drying processing section 90 are arranged side by side along a rail 51.

[0027] The etching processing device 60 collectively performs an etching process on one lot of a plurality of wafers W. The cleaning processing device 70 collectively performs a cleaning process on one lot of a plurality of wafers W. The cleaning processing device 80 performs a cleaning process on the substrate holder 53.

[0028] The drying processing device 90 collectively performs drying processing on one lot of a plurality of wafers W. The numbers of the etching processing devices 60, the cleaning processing devices 70, the cleaning processing devices 80 and the drying processing devices 90 are not limited to those in the example of FIG.

[0029] The etching processing apparatus 60 includes a processing tank 61 for the etching process, a processing tank 62 for the rinsing process, and substrate lifting mechanisms 63 and 64 .

[0030] The processing tank 61 can accommodate one lot of wafers W arranged in an upright position, and stores a chemical liquid for etching (hereinafter, also referred to as an "etching liquid"). The processing tank 61 will be described in detail later.

[0031] A processing liquid (deionized water, etc.) for rinsing processing is stored in the processing bath 62. The substrate lifting mechanisms 63 and 64 hold a plurality of wafers W forming a lot in an upright position lined up one behind the other.

[0032] In the etching processing device 60, the lot transported by the lot transport unit 5 is held by a substrate lifting mechanism 63 and immersed in an etching solution L (see FIG. 2) in a processing tank 61 to perform an etching process. The etching process is performed for about 1 hour to 3 hours, for example.

[0033] The lot that has been etched in the processing tank 61 is transported to the processing tank 62 by the lot transport unit 5. The etching processing device 60 holds the transported lot by the substrate lifting mechanism 64 and immerses it in the rinsing liquid in the processing tank 62, thereby performing a rinsing process. The lot that has been rinsed in the processing tank 62 is transported by the lot transport unit 5 to the processing tank 71 of the cleaning processing device 70.

[0034] The cleaning processing device 70 includes a cleaning processing tank 71, a rinsing processing tank 72, and substrate lifting mechanisms 73 and 74. A cleaning chemical (hereinafter also referred to as a "cleaning chemical") is stored in the cleaning processing tank 71. The cleaning chemical is, for example, SC-1 (a mixture of ammonia, hydrogen peroxide, and water).

[0035] A processing liquid for rinsing (deionized water, etc.) is stored in the processing bath 72 for rinsing. The substrate lifting mechanisms 73 and 74 hold a plurality of wafers W for one lot in an upright position lined up in front of and behind each other.

[0036] In the cleaning processing device 70, the lot transferred by the lot transfer section 5 is held by a substrate lifting mechanism 73 and immersed in a cleaning liquid in a processing bath 71, thereby performing a cleaning process.

[0037] The lot that has been cleaned in the processing tank 71 is transported to the processing tank 72 by the lot transport unit 5. The cleaning processing device 70 holds the transported lot by the substrate lifting mechanism 74 and immerses it in the rinsing liquid in the processing tank 72, thereby performing a rinsing process. The lot that has been rinsed in the processing tank 72 is transported by the lot transport unit 5 to the processing tank 91 of the drying processing device 90.

[0038] The drying processing apparatus 90 includes a processing tank 91 and a substrate lifting mechanism 92. A processing gas for a drying process is supplied to the processing tank 91. The substrate lifting mechanism 92 holds a plurality of wafers W for one lot in an upright position lined up in front of and behind each other.

[0039] The drying processing device 90 holds the lot transported by the lot transport unit 5 with a substrate lifting mechanism 92, and performs a drying process using a processing gas for drying process supplied into the processing tank 91. The lot that has been dried in the processing tank 91 is transported to the lot mounting unit 4 by the lot transport unit 5.

[0040] The cleaning processing device 80 performs a cleaning process on the substrate holder 53 of the lot transport mechanism 50 by supplying a cleaning processing liquid and further supplying a dry gas.

[0041] The control device 7 controls the operation of each part (such as the carrier load / unload unit 2, the lot formation unit 3, the lot placement unit 4, the lot transport unit 5, and the lot processing unit 6) of the substrate processing system 1. The control device 7 controls the operation of each part of the substrate processing system 1 based on signals from switches, various sensors, etc.

[0042] The control device 7 includes a microcomputer having a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), an input / output port, etc., and various circuits. The control device 7 controls the operation of the substrate processing system 1 by, for example, reading and executing a program stored in a storage unit 9 (see FIG. 4). The control device 7 will be described in detail later.

[0043] <Configuration of the etching processing device> Next, a configuration of an etching processing apparatus 60 that performs an etching process on a wafer W will be described with reference to Fig. 2 and Fig. 3. Fig. 2 and Fig. 3 are schematic block diagrams showing a configuration of the etching processing apparatus 60 according to an embodiment.

[0044] The etching processing apparatus 60 includes a phosphoric acid supplying unit 100 and a substrate processing unit 110. Of the etching processing apparatus 60, Fig. 2 is a diagram showing a detailed configuration of the phosphoric acid supplying unit 100, and Fig. 3 is a diagram showing a detailed configuration of the substrate processing unit 110.

[0045] First, details of the upstream phosphoric acid supplying unit 100 will be described with reference to Fig. 2. The phosphoric acid supplying unit 100 generates a mixed liquid M containing phosphoric acid and supplies it to the substrate processing unit 110. The mixed liquid M is an example of an aqueous phosphoric acid solution.

[0046] The phosphoric acid supplying section 100 includes an aqueous phosphoric acid solution supplying section 200, a precipitation inhibitor supplying section 210, a tank 220, and a circulation path 230. The circulation path 230 is an example of a third circulation path.

[0047] The aqueous phosphoric acid solution supply unit 200 supplies an aqueous phosphoric acid solution to the tank 220. The aqueous phosphoric acid solution supply unit 200 includes an aqueous phosphoric acid solution supply source 201, an aqueous phosphoric acid solution supply path 202, and a flow rate regulator 203.

[0048] The phosphoric acid aqueous solution supply source 201 is, for example, a tank that stores an aqueous phosphoric acid solution. The phosphoric acid aqueous solution supply path 202 connects the phosphoric acid aqueous solution supply source 201 and the tank 220, and supplies the aqueous phosphoric acid solution from the phosphoric acid aqueous solution supply source 201 to the tank 220.

[0049] The flow rate regulator 203 is provided in the phosphoric acid aqueous solution supply path 202, and regulates the flow rate of the phosphoric acid aqueous solution supplied to the tank 220. The flow rate regulator 203 includes an on-off valve, a flow rate control valve, a flow meter, and the like.

[0050] The precipitation inhibitor supplying unit 210 supplies the precipitation inhibitor to the tank 220. The precipitation inhibitor supplying unit 210 includes a precipitation inhibitor supply source 211, a precipitation inhibitor supply path 212, and a flow rate regulator 213.

[0051] The deposition inhibitor supply source 211 is, for example, a tank that stores the deposition inhibitor. The deposition inhibitor supply path 212 connects the deposition inhibitor supply source 211 and the tank 220, and supplies the deposition inhibitor from the deposition inhibitor supply source 211 to the tank 220.

[0052] The flow rate regulator 213 is provided in the precipitation inhibitor supply path 212, and regulates the flow rate of the precipitation inhibitor supplied to the tank 220. The flow rate regulator 213 includes an on-off valve, a flow control valve, a flow meter, and the like.

[0053] The precipitation inhibitor according to the embodiment may contain a component that inhibits the precipitation of silicon oxide. For example, the precipitation inhibitor may contain a component that stabilizes silicon ions dissolved in the phosphoric acid aqueous solution in a dissolved state to inhibit the precipitation of silicon oxide. The precipitation inhibitor may also contain a component that inhibits the precipitation of silicon oxide by other known methods.

[0054] The deposition inhibitor according to the embodiment may be, for example, an aqueous solution of hexafluorosilicic acid (H2SiF6) containing a fluorine component. In addition, in order to stabilize the hexafluorosilicic acid in the aqueous solution, an additive such as ammonia may be included.

[0055] As the precipitation inhibitor according to the embodiment, for example, ammonium hexafluorosilicate (NH4)2SiF6, sodium hexafluorosilicate (Na2SiF6), or the like can be used.

[0056] Furthermore, the precipitation inhibitor according to the embodiment may be a compound containing an element that is a cation with an ionic radius of 0.2 Å to 0.9 Å. Here, the "ionic radius" refers to the radius of an ion empirically determined from the sum of the radii of an anion and a cation obtained from the lattice constant of a crystal lattice.

[0057] The precipitation inhibitor according to the embodiment may contain, for example, an oxide of any of the elements aluminum, potassium, lithium, sodium, magnesium, calcium, zirconium, tungsten, titanium, molybdenum, hafnium, nickel, and chromium.

[0058] Furthermore, the precipitation inhibitor according to the embodiment may contain at least one of a nitride, a chloride, a bromide, a hydroxide, and a nitrate of any of the above elements, instead of or in addition to an oxide of any of the above elements.

[0059] The precipitation inhibitor according to the embodiment may include, for example, at least one of Al(OH)3, AlCl3, AlBr3, Al(NO3)3, Al2(SO4)3, AlPO4, and Al2O3.

[0060] The precipitation inhibitor according to the embodiment may include at least one of KCl, KBr, KOH, and KNO3. Furthermore, the precipitation inhibitor according to the embodiment may include at least one of LiCl, NaCl, MgCl2, CaCl2, and ZrCl4.

[0061] The precipitation inhibitor according to the embodiment contains a water-soluble organic solvent, such as ethanol, methanol, acetone, 1-propyl alcohol, 2-propyl alcohol, 1-butanol, or 2-butanol.

[0062] The tank 220 stores the phosphoric acid aqueous solution supplied from the phosphoric acid aqueous solution supply unit 200 and the precipitation inhibitor supplied from the precipitation inhibitor supply unit 210. The tank 220 also stores a mixed liquid M produced by mixing the phosphoric acid aqueous solution and the precipitation inhibitor.

[0063] The circulation path 230 is a circulation line that exits from the tank 220 and returns to the tank 220. The circulation path 230 has an inlet provided at the bottom of the tank 220 and an outlet provided at the top of the tank 220, and forms a circulation flow that flows from the inlet to the outlet. In the embodiment, the outlet is disposed above the liquid level of the mixed liquid M stored in the tank 220.

[0064] In the circulation path 230, a pump 231, a filter 232, a heater 233, a branching portion 234, a branching portion 235, and a valve 236 are provided in this order from the upstream side with respect to the tank 220. The pump 231 is an example of a third pump, and the heater 233 is an example of a second heater.

[0065] The pump 231 creates a circulation flow of the mixed liquid M out of the tank 220 , through the circulation path 230 , and back to the tank 220 .

[0066] The filter 232 removes contaminants such as particles contained in the mixed liquid M circulating in the circulation path 230. Note that the circulation path 230 is provided with a bypass flow path 237 that bypasses the filter 232, and the bypass flow path 237 is provided with a valve 238.

[0067] The control unit 8 (see FIG. 4) can form either a circulation flow that bypasses the filter 232 or a circulation flow that flows through the filter 232 by opening and closing the valve 238.

[0068] The heater 233 heats the mixed liquid M circulating in the circulation path 230. In the embodiment, by heating the mixed liquid M with the heater 233, the mixed liquid M stored in the tank 220 is heated.

[0069] A first liquid delivery path 101 branches off from branching portion 234, which delivers the mixed liquid M to the inner tank 111 (see Figure 3) of the treatment tank 61 (see Figure 3), and a second liquid delivery path 102 branches off from branching portion 235, which delivers the mixed liquid M to the outer tank 112 (see Figure 3) of the treatment tank 61.

[0070] A flow rate regulator 103 is provided in the first liquid transfer path 101. The flow rate regulator 103 regulates the flow rate of the mixed liquid M supplied to the inner tank 111 of the processing tank 61. The flow rate regulator 103 includes an on-off valve, a flow rate control valve, a flow meter, and the like.

[0071] In the second liquid transport path 102, a valve 250, a thermometer 251, a branching portion 252, a constant pressure valve 104, a throttle valve 105, a branching portion 106, and a valve 107 are provided in this order from the upstream side.

[0072] The thermometer 251 measures the temperature of the mixed liquid M flowing through the second liquid transfer path 102. A return path 253 that returns the mixed liquid M to the tank 220 branches off from the branching part 252. The return path 253 has a back pressure valve 254. The back pressure valve 254 adjusts the pressure on the upstream side of the back pressure valve 254 in the return path 253 (for example, the branching part 252).

[0073] The constant pressure valve 104 adjusts the pressure on the second liquid transfer path downstream of the constant pressure valve 104. The throttle valve 105 adjusts the flow rate of the mixed liquid M flowing through the second liquid transfer path .

[0074] A return path 108 that returns the mixed liquid M to the tank 220 branches off from the branching portion 106. Thus, in the embodiment, the return path 253 and the return path 108 branch off from the second liquid transport path 102, and return the mixed liquid M flowing through the second liquid transport path 102 to the tank 220. The return path 108 has a valve 109.

[0075] The control unit 8 alternately opens and closes the valve 107 and the valve 109. In this way, the control unit 8 can switch between sending the mixed liquid M to the outer tank 112 or the tank 220.

[0076] The valve 236 is controlled to be in a closed state when the mixed liquid M is supplied to the substrate processing unit 110 using the first liquid transfer path 101 or the second liquid transfer path 102.

[0077] In the phosphoric acid supply unit 100 described above, the control unit 8 mixes the phosphoric acid aqueous solution and the precipitation inhibitor in a predetermined ratio in the tank 220 to generate the mixed solution M. Furthermore, the control unit 8 operates the pump 231 to circulate the mixed solution M being generated within the circulation path 230. This can improve the mixability of the phosphoric acid aqueous solution and the precipitation inhibitor.

[0078] In the embodiment, after the production process of the mixed liquid M is completed, the mixed liquid M circulating through the circulation path 230 is heated to a given temperature (for example, about 170° C.) by the heater 233. This makes it possible to efficiently heat the mixed liquid M.

[0079] During the heating process, the control unit 8 controls the valve 238 to be open so that the circulating flow of the mixed liquid M bypasses the filter 232. Then, when the heating process is completed, the control unit 8 controls the valve 238 to be closed so that the circulating flow of the mixed liquid M passes through the filter 232. This removes contaminants such as particles contained in the mixed liquid M.

[0080] In this manner, in the embodiment, the circulating flow of the circulation path 230 is controlled so as to bypass the filter 232 during the mixing process and the heating process. This makes it possible to reduce the pressure loss occurring in the filter 232 in the circulation path 230, and therefore makes it possible to efficiently circulate the mixed liquid M stored in the tank 220.

[0081] Since there is no need to filter the mixed liquid M with the filter 232 until the heating process is completed, there is no problem even if the mixed liquid M is circulated via the bypass flow path 237.

[0082] Next, the downstream substrate processing unit 110 will be described in detail with reference to Fig. 3. In the substrate processing unit 110, an etching solution L is generated from a mixed solution M supplied from a phosphoric acid supply unit 100 and a silicic acid solution supplied from a silicic acid solution supply unit 140.

[0083] Furthermore, the substrate processing unit 110 etches the wafer W by immersing the wafer W in the generated etching liquid L. The etching liquid L is an example of a processing liquid.

[0084] In the embodiment, for example, of a silicon nitride film and a silicon oxide film stacked on the wafer W, the silicon nitride film can be selectively etched.

[0085] The substrate processing unit 110 includes a processing tank 61, a substrate lifting mechanism 63, a circulation path 120, a DIW supply unit 130, a silicic acid solution supply unit 140, a bubbling gas supply unit 150, and an exhaust unit 160. The circulation path 120 is an example of a first circulation path, and the DIW supply unit 130 is an example of a pure water supply unit.

[0086] The processing tank 61 includes an inner tank 111, an outer tank 112, and a liquid level sensor 113. The liquid level sensor 113 is an example of a liquid amount sensor.

[0087] The inner tank 111 is a tank for immersing the wafer W in the etching liquid L, and contains the immersion etching liquid L. The inner tank 111 has an opening 111a at the top, and the etching liquid E is stored up to the vicinity of the opening 111a.

[0088] In the inner tank 111, a plurality of wafers W are immersed in the etching solution L using the substrate lifting mechanism 63, thereby performing an etching process on the wafers W. The substrate lifting mechanism 63 is configured to be capable of rising and lowering, and holds the plurality of wafers W aligned in front of and behind each other in a vertical posture.

[0089] The outer tank 112 is disposed outside the inner tank 111 so as to surround the inner tank 111, and receives the etching solution L flowing out from the opening 111a of the inner tank 111. As shown in FIG. 2, the liquid level in the outer tank 112 is maintained lower than the liquid level in the inner tank 111.

[0090] The liquid level sensor 113 measures the liquid level of the etching liquid L stored in the outer tank 112. The control unit 8 (see FIG. 4) can measure the amount of the etching liquid L stored in the processing tank 61 (hereinafter also referred to as the "storage amount of the etching liquid L") based on the height of the outer tank 112 measured by the liquid level sensor 113.

[0091] This is because the inside of the inner tank 111 and the circulation path 120 are filled with etching liquid L, and therefore the amount of liquid is always constant. Therefore, by measuring the amount of liquid in the outer tank 112 based on the measurement value of the liquid level sensor 113, the amount of liquid in the entire processing tank 61 can be obtained.

[0092] The outer bath 112 and the inner bath 111 are connected by a circulation path 120. One end of the circulation path 120 is connected to the bottom of the outer bath 112, and the other end of the circulation path 120 is connected to a processing liquid supply nozzle 126 located in the inner bath 111.

[0093] In the circulation path 120, a pump 121, a heater 122, a branching portion 123, a filter 124, and a concentration sensor 125 are positioned in this order from the upstream side, that is, the outer tank 112 side. The pump 121 is an example of a first pump, and the heater 122 is an example of a first heater.

[0094] The pump 121 forms a circulating flow of the etching liquid L that is sent from the outer tank 112 to the inner tank 111 via the circulation path 120. The etching liquid L overflows from an opening 111a of the inner tank 111 and flows back into the outer tank 112.

[0095] In this manner, in the etching processing apparatus 60, a circulating flow of the etching liquid L is formed in the substrate processing unit 110. In other words, such a circulating flow is formed in the outer bath 112, the circulation path 120, and the inner bath 111.

[0096] The heater 122 adjusts the temperature of the etching solution L circulating through the circulation path 120. The filter 124 filters the etching solution L circulating through the circulation path 120. The concentration sensor 125 detects the phosphoric acid concentration in the etching solution L circulating through the circulation path 120. A signal generated by the concentration sensor 125 is transmitted to the control unit 8.

[0097] The DIW supply unit 130 includes a DIW supply source 131, a DIW supply path 132, and a flow rate regulator 133. The DIW supply unit 130 supplies DIW (DeIonized Water) to the outer tank 112 in order to adjust the concentration of the etching solution L stored in the processing tank 61.

[0098] The DIW supply source 131 is, for example, a tank that stores DIW. The DIW supply line 132 connects the DIW supply source 131 and the outer bath 112, and supplies DIW at a given temperature from the DIW supply source 131 to the outer bath 112.

[0099] The flow rate regulator 133 is disposed in the DIW supply path 132 and regulates the amount of DIW supplied to the outer bath 112. The flow rate regulator 133 has an on-off valve, a flow control valve, a flow meter, etc. The amount of DIW supplied is adjusted by the flow rate regulator 133, whereby the temperature, phosphoric acid concentration, silicic acid concentration, and precipitation inhibitor concentration of the etching solution L in the etching processing device 60 are adjusted.

[0100] The silicic acid solution supply unit 140 supplies a solution containing a silicic acid compound (hereinafter also referred to as a “silicic acid solution”) to the inner tank 111. The silicic acid solution supply unit 140 includes a silicic acid solution source 141, a silicic acid solution supply path 142, and a flow rate regulator 143.

[0101] The silicic acid solution supply source 141 is, for example, a tank for storing a silicic acid solution. The silicic acid solution supply path 142 connects the silicic acid solution supply source 141 and the inner tank 111 of the treatment tank 61, and supplies the silicic acid solution from the silicic acid solution supply source 141 to the inner tank 111 of the treatment tank 61.

[0102] The flow rate regulator 143 is disposed in the silicic acid solution supply path 142, and regulates the flow rate of the silicic acid solution supplied to the inner tank 111 of the treatment tank 61. The flow rate regulator 143 includes an on-off valve, a flow control valve, a flow meter, etc. The silicic acid solution according to the embodiment is, for example, a solution in which colloidal silicon is dispersed.

[0103] The bubbling gas supply unit 150 discharges bubbles of an inert gas (for example, nitrogen gas) into the etching solution L stored in the inner tank 111. The bubbling gas supply unit 150 includes an inert gas supply source 151, an inert gas supply path 152, a flow rate regulator 153, and a gas nozzle 154.

[0104] The inert gas supply source 151 is, for example, a cylinder that stores an inert gas. The inert gas supply path 152 connects the inert gas supply source 151 and the gas nozzle 154, and supplies an inert gas (for example, nitrogen gas) from the inert gas supply source 151 to the gas nozzle 154.

[0105] The flow rate regulator 153 is disposed in the inert gas supply path 152, and regulates the amount of inert gas supplied to the gas nozzle 154. The flow rate regulator 153 includes an on-off valve, a flow rate control valve, a flow meter, and the like.

[0106] The gas nozzle 154 is located, for example, below the wafer W and the processing liquid supply nozzle 126 in the inner tank 111. The gas nozzle 154 discharges bubbles of an inert gas into the etching liquid L stored in the inner tank 111.

[0107] The etching processing apparatus 60 according to the embodiment can supply a fast flow of the etching solution L to the gaps between the multiple wafers W aligned in the inner tank 111 by discharging bubbles of the inert gas from the gas nozzle 154. Therefore, according to the embodiment, the multiple wafers W can be etched efficiently and uniformly.

[0108] The discharge unit 160 discharges the etching liquid L to the drain DR when, for example, replacing all or a part of the etching liquid L used in the etching process. The discharge unit 160 has a discharge path 161, a valve 162, a flow meter 163, a constant pressure valve 164, a throttle valve 165, and a cooling tank 166.

[0109] The discharge path 161 is connected to a branching point 123 of the circulation path 120. On the discharge path 161, a valve 162, a flow meter 163, a constant pressure valve 164, a throttle valve 165, and a cooling tank 166 are provided in this order from the upstream side with respect to the branching point 123.

[0110] The flow meter 163 measures the flow rate of the etching liquid L flowing through the discharge path 161. The constant pressure valve 164 adjusts the pressure downstream of the constant pressure valve 164 in the discharge path 161. The throttle valve 165 adjusts the flow rate of the etching liquid L flowing through the discharge path 161. The cooling tank 166 temporarily stores and cools the etching liquid L that has flowed through the discharge path 161.

[0111] In the substrate processing according to the embodiment, first, the control unit 8 supplies the mixed liquid M (see FIG. 2) to the inner bath 111 using the first liquid supply path 101, and also supplies the silicic acid solution to the inner bath 111 using the silicic acid solution supply unit 140.

[0112] Furthermore, the control unit 8 causes the mixed liquid M and the silicic acid solution to overflow from the inner tank 111 to the outer tank 112 , and also operates the pump 121 to form a circulating flow in the circulation path 120 .

[0113] This produces a given amount of etching solution L having given phosphoric acid concentrations, silicic acid concentrations, and precipitation inhibitor concentrations. That is, in the embodiment, the etching solution L having a desired silicic acid concentration can be prepared at the start of the etching process of the wafer W.

[0114] Therefore, according to the embodiment, from the start of the etching process on the wafer W, the etching selectivity of the silicon nitride film to the silicon oxide film can be improved.

[0115] In the embodiment, the control unit 8 supplies both the mixed liquid M and the silicic acid solution to the inner tank 111 of the treatment tank 61. As a result, in the embodiment, the mixed liquid M and the silicic acid solution can be mixed while overflowing from the inner tank 111 to the outer tank 112, thereby improving the mixability of the mixed liquid M and the silicon solution.

[0116] Next, in the substrate processing according to the embodiment, the control unit 8 immerses the wafer W in the inner tank 111 of the processing tank 61 in which a given amount of etching solution L is stored, and performs an etching process on the wafer W. Meanwhile, in the etching process, since the silicic acid compound is dissolved from the wafer W into the etching solution L, the concentration of silicic acid in the etching solution L increases if left as is.

[0117] Therefore, in the embodiment, during the etching process, the control unit 8 supplies the mixed liquid M not containing silicic acid to the outer tank 112 via the second liquid supply path 102 of the phosphoric acid supply unit 100, and discharges the etching liquid L containing silicic acid from the treatment tank 61 by the discharge unit 160.

[0118] This makes it possible to maintain the silicic acid concentration in the etching solution L at a given value in the etching process of the wafer W. Therefore, according to the embodiment, the etching process of the wafer W can be stably performed.

[0119] Furthermore, in the etching process according to the embodiment, the etching solution L is heated to a high temperature (for example, about 170°C), and the water in the etching solution L evaporates, so that if left as is, the phosphoric acid concentration in the etching solution L will increase.

[0120] Therefore, in the embodiment, during the etching process, the control unit 8 operates the DIW supply unit 130 to appropriately replenish the etching solution L with DIW. This makes it possible to maintain the phosphoric acid concentration in the etching solution L at a given value during the etching process of the wafer W. Therefore, according to the embodiment, the etching process of the wafer W can be stably performed.

[0121] <Embodiment> Next, details of the substrate processing according to the embodiment will be described with reference to Fig. 4 to Fig. 8. Fig. 4 is a block diagram showing the configuration of a control device 7 according to the embodiment. As shown in Fig. 3, the control device 7 includes a control unit 8 and a storage unit 9.

[0122] In addition to the functional units shown in FIG. 4, the control device 7 may also have various functional units that known computers have, such as various input devices and audio output devices.

[0123] The control unit 8 is realized by, for example, a CPU, a micro processing unit (MPU), a graphics processing unit (GPU), or the like executing a program stored in the storage unit 9 using the RAM as a working area.

[0124] The control unit 8 may be realized by an integrated circuit such as an application specific integrated circuit (ASIC) or a field programmable gate array (FPGA).

[0125] The storage unit 9 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. The storage unit 9 stores information used in the processing by the control unit 8.

[0126] The control unit 8 has a liquid volume measurement unit 8a, a concentration measurement unit 8b, a discharge amount maintenance unit 8c, and a supply amount control unit 8d, and realizes or executes the functions and actions of the control processing described below. Note that the internal configuration of the control unit 8 is not limited to the configuration shown in Fig. 4, and may be other configurations as long as they perform the control processing described below.

[0127] The liquid amount measuring unit 8a measures the amount of the etching liquid L (see FIG. 3) stored in the processing tank 61 (see FIG. 3). Specifically, the liquid amount measuring unit 8a measures the amount of the etching liquid L stored in the outer tank 112 (see FIG. 3) based on the measurement value of the liquid level sensor 113 (see FIG. 3), thereby obtaining the amount of the etching liquid L stored in the entire processing tank 61.

[0128] The concentration measuring unit 8b measures the phosphoric acid concentration in the etching solution L stored in the treatment tank 61. Specifically, the concentration measuring unit 8b measures the phosphoric acid concentration in the etching solution L based on the measurement value of the concentration sensor 125 (see FIG. 3).

[0129] The discharge amount maintaining unit 8c maintains at a given value the amount of the etching solution L discharged per unit time from the processing tank 61. Fig. 5 is a timing chart showing an example of changes in the discharge amount, the storage amount, and the supply amount in the substrate processing according to the embodiment.

[0130] For example, as shown in FIG. 5, in a concentration maintenance process for maintaining the phosphoric acid concentration and the silicic acid concentration during the etching process of a wafer W, the discharge amount maintenance unit 8c maintains the discharge amount of the etching solution L (see FIG. 3) per hour at a given discharge amount D1 from time T0 when the concentration maintenance process is started.

[0131] In this discharge amount maintenance process, the discharge amount maintenance unit 8c performs coarse adjustment of the flow rate using the throttle valve 165 (see FIG. 3), and performs fine adjustment of the flow rate using the flow meter 163 (see FIG. 3) and the constant pressure valve 164 (see FIG. 3).

[0132] The discharge amount maintaining unit 8c maintains the flow rate of the etching liquid L in the flow meter 163 at the discharge amount D1 by feedback-controlling the pressure of the etching liquid L in the flow meter 163 with the constant pressure valve 164. This allows a more accurate amount of etching liquid L to be discharged, so that the discharge amount maintaining process can be performed stably and accurately.

[0133] Returning to the explanation of Fig. 4, the supply amount control unit 8d controls the supply amounts of the mixed liquid M and DIW supplied to the processing tank 61 so that the amount of the etching liquid L stored in the processing tank 61 and the phosphoric acid concentration are maintained at given values, respectively.

[0134] For example, as shown in Fig. 5, the supply amount control unit 8d controls the supply amount of the mixed liquid M (see Fig. 2) and DIW so that the storage amount in the treatment tank 61 (see Fig. 3) is maintained at a given storage amount Vth. In the example of Fig. 5, at time T0 when the concentration maintenance process is started, the storage amount in the treatment tank 61 is a storage amount V1 that is larger than the storage amount Vth, so that the supply amount control unit 8d controls the supply amount of the mixed liquid M and DIW to a smaller supply amount S1.

[0135] Then, when the storage amount in the treatment tank 61 gradually decreases, the supply amount control unit 8d gradually increases the supply amount of the mixed liquid M and the DIW. Furthermore, when the storage amount in the treatment tank 61 reaches the storage amount Vth, the supply amount of the mixed liquid M and the DIW is controlled so as to maintain the storage amount Vth.

[0136] This allows the supply amount control unit 8d to maintain the amount of the etching liquid L stored in the processing tank 61 at the storage amount Vth. The supply amount control unit 8d can control the supply amounts of the mixed liquid M and DIW by controlling the constant pressure valve 104 (see FIG. 3) and the flow rate regulator 133 (see FIG. 3).

[0137] In addition, although not shown in FIG. 5, the supply amount control unit 8d can maintain the phosphoric acid concentration in the etching solution L in the treatment tank 61 at a given value by appropriately controlling the ratio of the mixed liquid M and DIW supplied to the treatment tank 61.

[0138] As described above, in the substrate processing according to the embodiment, in the concentration maintenance process, the discharge amount of the etching liquid L is fixed and controlled to a given value (discharge amount D1), and the supply amounts of the mixed liquid M and DIW are variably controlled. The effect of such control will be described below.

[0139] 6 is a diagram showing an example of the balance between the supply amount and the discharge amount of each liquid in the concentration maintenance process in a reference example. In this reference example (example of FIG. 6), in the concentration maintenance process, contrary to the embodiment, the discharge amount of the etching liquid L (see FIG. 3) is variably controlled, and the supply amount of the mixed liquid M (see FIG. 2) is fixedly controlled.

[0140] 6(a) shows a case where a mixed solution M having the same phosphoric acid concentration of 90(%) as that of the treatment tank 61 is supplied from a phosphoric acid supply unit 100 (see FIG. 2) to a treatment tank 61 (see FIG. 3) in which an etching solution L having a phosphoric acid concentration of 90(%) is stored. Note that, since the amount of the precipitation inhibitor in the mixed solution M is small, the precipitation inhibitor is not taken into consideration in the description of FIGS. 6 and 8 for ease of understanding.

[0141] In the example of FIG. 6(a), when 1.0 (L) of mixed solution M is supplied from the phosphoric acid supply unit 100 at a constant supply rate, the mixed solution M contains 0.9 (L) of phosphoric acid and 0.1 (L) of DIW.

[0142] At this time, in order to maintain the phosphoric acid concentration in the treatment tank 61, it is necessary to discharge 0.9 (L) of phosphoric acid from the discharge part 160 (see FIG. 3). Therefore, in this case, a total of 1.0 (L) of etching solution L with a phosphoric acid concentration of 90 (%) containing 0.1 (L) of DIW is discharged from the discharge part 160.

[0143] Furthermore, since the etching solution L in the treatment tank 61 is at a high temperature, a large amount (for example, 0.3 (L)) of DIW evaporates from the treatment tank 61. Therefore, in order to maintain the storage amount and phosphoric acid concentration in the treatment tank 61, 0.3 (L) of DIW is supplied from the DIW supply unit 130 (see FIG. 3).

[0144] In this manner, by appropriately controlling the discharge amount from the discharge unit 160 and the supply amount from the DIW supply unit 130, the amount of the etching liquid L stored in the treatment tank 61 and the phosphoric acid concentration are maintained in the example of FIG. 6(a).

[0145] The example of (b) in FIG. 6 shows a case where a mixed liquid M having a phosphoric acid concentration of 85(%), which is lower than that in the example of (a) in FIG. 6, is supplied from the phosphoric acid supply unit 100 to a processing tank 61 storing an etching solution L having a phosphoric acid concentration of 90(%).

[0146] This is because the phosphoric acid supply unit 100 shown in FIG. 2 heats the mixed liquid M using the heater 233, and water evaporates from the mixed liquid M stored in the tank 220, which may cause the phosphoric acid concentration in the mixed liquid M to vary.

[0147] In the example of FIG. 6(b), when 1.0 (L) of mixed solution M is supplied from the phosphoric acid supply unit 100 at a constant supply rate, the mixed solution M contains 0.85 (L) of phosphoric acid and 0.15 (L) of DIW.

[0148] At this time, in order to maintain the phosphoric acid concentration in the treatment tank 61, it is necessary to discharge 0.85 (L) of phosphoric acid from the discharge part 160. Therefore, in this case, a total of about 0.95 (L) of etching solution L with a phosphoric acid concentration of 90 (%) containing about 0.1 (L) of DIW is discharged from the discharge part 160.

[0149] Furthermore, 0.3 (L) of DIW evaporates from the treatment tank 61. Therefore, in order to maintain the storage volume and phosphoric acid concentration in the treatment tank 61, 0.25 (L) of DIW is supplied from the DIW supply unit 130. This is because the mixed solution M supplied from the phosphoric acid supply unit 100 contains 0.15 (L) of DIW, which is more than in the example of FIG. 6(a).

[0150] In this manner, by appropriately controlling the discharge amount from the discharge unit 160 and the supply amount from the DIW supply unit 130, the amount of the etching liquid L stored in the treatment tank 61 and the phosphoric acid concentration are maintained even in the example of FIG. 6(b).

[0151] On the other hand, in the example of Fig. 6(b) in which the phosphoric acid concentration of the mixed liquid M supplied to the treatment tank 61 is lower than that in the example of Fig. 6(a), the amount of the etching liquid L discharged from the discharge part 160 is reduced. That is, in the example of Fig. 6(b), the discharge performance of the etching liquid L is deteriorated compared to the example of Fig. 6(a).

[0152] As a result, in the example of FIG. 6(b), the performance of discharging the silicic acid compound dissolved from the wafer W into the etching solution L by the etching process decreases, so that the concentration of silicic acid in the etching solution L gradually increases.

[0153] Fig. 7 is a diagram showing an example of the transition of the silicic acid concentration in the etching solution L (see Fig. 3) in the reference example. As shown in Fig. 7, when the phosphoric acid concentration in the mixed liquid M (see Fig. 2) supplied is 90(%), which is the same as that of the etching solution L stored in the treatment tank 61 (see Fig. 3), the silicic acid concentration is maintained constant even after the etching time has elapsed.

[0154] On the other hand, when the phosphoric acid concentration in the supplied mixed liquid M is 85(%), which is lower than that of the etching liquid L stored in the processing tank 61, it is found that the silicic acid concentration gradually increases as the etching time passes. As a result, in the reference example, it is difficult to stably perform the etching process of the wafer W.

[0155] Returning to the explanation of Fig. 6, the example of Fig. 6(c) shows a case where a mixed solution M having a phosphoric acid concentration of 95(%), which is higher than that in the example of Fig. 6(a), is supplied from the phosphoric acid supply unit 100 to a processing tank 61 storing an etching solution L having a phosphoric acid concentration of 90(%).

[0156] In the example of FIG. 6(c), when 1.0 (L) of mixed solution M is supplied from the phosphoric acid supply unit 100 at a constant supply rate, the mixed solution M contains 0.95 (L) of phosphoric acid and 0.05 (L) of DIW.

[0157] At this time, in order to maintain the phosphoric acid concentration in the treatment tank 61, it is necessary to discharge 0.95 (L) of phosphoric acid from the discharge part 160. Therefore, in this case, a total of about 1.05 (L) of etching solution L with a phosphoric acid concentration of 90 (%) containing about 0.1 (L) of DIW is discharged from the discharge part 160.

[0158] 6(a), 0.3 (L) of DIW evaporates from the treatment tank 61. Therefore, in order to maintain the storage volume and phosphoric acid concentration in the treatment tank 61, 0.35 (L) of DIW is supplied from the DIW supply unit 130. This is because the mixed solution M supplied from the phosphoric acid supply unit 100 contains 0.05 (L) of DIW, which is less than in the example of FIG. 6(a).

[0159] In this manner, by appropriately controlling the discharge amount from the discharge unit 160 and the supply amount from the DIW supply unit 130, the amount of etching liquid L stored in the treatment tank 61 and the phosphoric acid concentration are maintained even in the example of FIG. 6(c).

[0160] On the other hand, in the example of Fig. 6(c) in which the phosphoric acid concentration of the mixed liquid M supplied to the treatment tank 61 is higher than that in the example of Fig. 6(a), the amount of the etching liquid L discharged from the discharge part 160 is large. That is, in the example of Fig. 6(c), the discharge performance of the etching liquid L is excessive compared to the example of Fig. 6(a).

[0161] As a result, in the example of FIG. 6(c), the discharge performance of the silicic acid compound dissolved from the wafer W into the etching solution L during the etching process becomes excessive, so that the concentration of silicic acid in the etching solution L gradually decreases.

[0162] 7, when the phosphoric acid concentration in the supplied mixed liquid M is 95(%), which is higher than that of the etching liquid L stored in the processing tank 61, the silicic acid concentration gradually decreases as the etching time passes. As a result, in the reference example, it is difficult to stably perform the etching process of the wafer W.

[0163] 8 is a diagram showing an example of the balance between the supply amount and the discharge amount of each liquid in the concentration maintenance process according to the embodiment. As described above, in the embodiment, in the concentration maintenance process, the discharge amount of the etching liquid L (see FIG. 3) is fixedly controlled, and the supply amount of the mixed liquid M (see FIG. 2) is variably controlled.

[0164] The example of (a) in Figure 8 shows a case where a mixed liquid M having the same phosphoric acid concentration of 90(%) as that of the treatment tank 61 (see Figure 3) is supplied from the phosphoric acid supply unit 100 (see Figure 2) to a treatment tank 61 (see Figure 3) in which an etching solution L having a phosphoric acid concentration of 90(%) is stored.

[0165] In the example of (a) in Figure 8, when 1.0 (L) of etching solution L is discharged from the discharge part 160 (see Figure 3) at a constant discharge amount, the etching solution L contains 0.9 (L) of phosphoric acid and 0.1 (L) of DIW.

[0166] At this time, in order to maintain the phosphoric acid concentration in the treatment tank 61, it is necessary to supply 0.9 (L) of phosphoric acid from the phosphoric acid supply unit 100 (see FIG. 2). Therefore, in this case, a total of 1.0 (L) of mixed solution M with a phosphoric acid concentration of 90 (%) containing 0.1 (L) of DIW is supplied from the phosphoric acid supply unit 100.

[0167] Furthermore, since the etching solution L is at a high temperature, 0.3 (L) of DIW evaporates from the treatment tank 61. Therefore, in order to maintain the storage amount and phosphoric acid concentration in the treatment tank 61, 0.3 (L) of DIW is supplied from the DIW supply unit 130 (see FIG. 3).

[0168] In this manner, by appropriately controlling the supply amounts from the phosphoric acid supply unit 100 and the DIW supply unit 130, the amount of the etching liquid L stored in the processing tank 61 and the phosphoric acid concentration are maintained in the example of FIG. 8(a).

[0169] The example of (b) in Figure 8 shows a case where a mixed liquid M having a phosphoric acid concentration of 85(%), which is lower than the example of (a) in Figure 8, is supplied from the phosphoric acid supply unit 100 to a processing tank 61 storing an etching solution L having a phosphoric acid concentration of 90(%).

[0170] In the example of FIG. 8(b), when 1.0 (L) of etching solution L is discharged from the discharge part 160 at a constant discharge rate, the etching solution L contains 0.9 (L) of phosphoric acid and 0.1 (L) of DIW.

[0171] At this time, in order to maintain the phosphoric acid concentration in the treatment tank 61, it is necessary to supply 0.9 (L) of phosphoric acid from the phosphoric acid supply unit 100. Therefore, in this case, a total of about 1.05 (L) of mixed solution M containing about 0.15 (L) of DIW and having a phosphoric acid concentration of 85 (%) is supplied from the phosphoric acid supply unit 100.

[0172] 8(a), 0.3 (L) of DIW evaporates from the treatment tank 61. Therefore, in order to maintain the storage volume and phosphoric acid concentration in the treatment tank 61, 0.25 (L) of DIW is supplied from the DIW supply unit 130. This is because the mixed solution M supplied from the phosphoric acid supply unit 100 contains about 0.15 (L) of DIW, which is more than in the example of FIG. 8(a).

[0173] In this manner, by appropriately controlling the supply amounts from the phosphoric acid supply unit 100 and the DIW supply unit 130, the amount of the etching liquid L stored in the processing tank 61 and the phosphoric acid concentration are maintained even in the example of FIG. 8(b).

[0174] Furthermore, in the embodiment, even in the example of Fig. 8(b) in which the phosphoric acid concentration of the mixed liquid M supplied to the treatment tank 61 is lower than that in the example of Fig. 8(a), the discharge amount of the etching liquid L from the discharge part 160 is maintained at 1.0 (L). That is, in the example of Fig. 8(b), the discharge performance of the etching liquid L is maintained compared to the example of Fig. 8(a).

[0175] As a result, in the example of Figure 8 (b), the discharge performance of the silicic acid compound that dissolves from the wafer W into the etching solution L during the etching process is maintained, so that the silicic acid concentration in the etching solution L can be maintained at a given value.

[0176] The example of (c) in Figure 8 shows a case where a mixed liquid M having a phosphoric acid concentration of 95(%), which is higher than that in the example of (a) in Figure 8, is supplied from the phosphoric acid supply unit 100 to a processing tank 61 in which an etching solution L having a phosphoric acid concentration of 90(%) is stored.

[0177] In the example of FIG. 8(c), when 1.0 (L) of etching solution L is discharged from the discharge part 160 at a constant discharge rate, the etching solution L contains 0.9 (L) of phosphoric acid and 0.1 (L) of DIW.

[0178] At this time, in order to maintain the phosphoric acid concentration in the treatment tank 61, it is necessary to supply 0.9 (L) of phosphoric acid from the phosphoric acid supply unit 100. Therefore, in this case, a total of about 0.95 (L) of mixed solution M with a phosphoric acid concentration of 95 (%) containing about 0.05 (L) of DIW is supplied from the phosphoric acid supply unit 100.

[0179] 8(a), 0.3 (L) of DIW evaporates from the treatment tank 61. Therefore, in order to maintain the storage volume and phosphoric acid concentration in the treatment tank 61, 0.35 (L) of DIW is supplied from the DIW supply unit 130. This is because the mixed solution M supplied from the phosphoric acid supply unit 100 contains about 0.05 (L) of DIW, which is less than in the example of FIG. 8(a).

[0180] In this manner, by appropriately controlling the supply amounts from the phosphoric acid supply unit 100 and the DIW supply unit 130, the amount of the etching liquid L stored in the processing tank 61 and the phosphoric acid concentration are maintained even in the example of FIG. 8(c).

[0181] Furthermore, in the embodiment, even in the example of Fig. 8(c) in which the phosphoric acid concentration of the mixed liquid M supplied to the treatment tank 61 is higher than that in the example of Fig. 8(a), the discharge amount of the etching liquid L from the discharge part 160 is maintained at 1.0 (L). That is, in the example of Fig. 8(c), the discharge performance of the etching liquid L is maintained compared to the example of Fig. 8(a).

[0182] As a result, in the example of (c) of Figure 8, the discharge performance of the silicic acid compound that dissolves from the wafer W into the etching solution L during the etching process is maintained, so that the silicic acid concentration in the etching solution L can be maintained at a given value.

[0183] In this manner, in the concentration maintenance process according to the embodiment, by controlling the discharge amount of the etching solution L to a fixed amount and controlling the supply amount of the mixed solution M to a variable amount, the silicic acid concentration in the etching solution L can be maintained even if the phosphoric acid concentration in the mixed solution M generated in the phosphoric acid supply section 100 varies.

[0184] Therefore, according to the embodiment, the etching process of the wafer W can be performed stably.

[0185] In addition, in the embodiment, even if the phosphoric acid concentration in the mixed liquid M generated in the phosphoric acid supply unit 100 varies, the silicic acid concentration in the etching liquid L can be maintained, so there is no need to provide the phosphoric acid supply unit 100 with a concentration sensor for measuring the phosphoric acid concentration of the mixed liquid M.

[0186] Therefore, according to the embodiment, the manufacturing cost of the etching processing apparatus 60 can be reduced.

[0187] In the embodiment, in the substrate processing unit 110, the amount of the etching liquid L stored in the processing tank 61 may be measured using a liquid level sensor 113 provided in the outer tank 112. This allows the amount of the etching liquid L stored in the processing tank 61 having the inner tank 111 and the outer tank 112 to be easily measured.

[0188] In the embodiment, the heater 122 is provided in the circulation path 120 in which a circulating flow is formed by the pump 121, so that the etching liquid L can be efficiently heated.

[0189] In the embodiment, the discharge part 160 may be connected to the downstream side (branch part 123) of the pump 121 of the circulation path 120. This allows the etching liquid L to be discharged from the discharge part 160 by the pump 121 used in the mixing process or heating process of the etching liquid L.

[0190] That is, in the embodiment, since it is not necessary to provide a separate pump for discharging the etching liquid L, the etching liquid L can be discharged at low cost.

[0191] In the embodiment, in the phosphoric acid supply unit 100, by providing the heater 233 in the circulation path 230 in which a circulation flow is formed by the pump 231, the mixed solution M can be efficiently heated.

[0192] In the embodiment, the first liquid transfer path 101 and the second liquid transfer path 102 may be connected to the circulation path 230 downstream of the pump 231 (branching portions 234, 235). This allows the mixed liquid M to be supplied from the phosphoric acid supplying portion 100 to the substrate processing portion 110 by the pump 231 used in the mixing process and heating process of the mixed liquid M.

[0193] That is, in the embodiment, since it is not necessary to provide a separate pump for the supply process of the mixed liquid M, the mixed liquid M can be supplied at low cost.

[0194] <Modification> Next, a modified example of the substrate processing system 1 according to the embodiment will be described with reference to Fig. 9. Fig. 9 is a schematic block diagram showing a configuration of an etching processing apparatus 60 according to the modified example of the embodiment, and corresponds to Fig. 3 of the embodiment. Note that Fig. 9 omits the illustration of the inert gas supply source 151 of the bubbling gas supply unit 150 shown in Fig. 3 and the like.

[0195] 9, in an etching processing apparatus 60 according to the modified example, the configuration of a discharge unit 160 is different from that of the embodiment. Specifically, a circulation path 170 separate from the circulation path 120 is provided in the processing tank 61, and the discharge unit 160 is connected to the circulation path 170. The circulation path 170 is an example of a second circulation path.

[0196] The circulation path 170 is a circulation line that exits from the outer tank 112 of the treatment tank 61 and returns to the outer tank 112. The circulation path 170 has an inlet provided at the bottom of the outer tank 112 and an outlet provided at the top of the outer tank 112, and forms a circulation flow that flows from the inlet to the outlet.

[0197] In the circulation path 170, a pump 171, a branching portion 172, and a back pressure valve 173 are provided in this order from the upstream side with respect to the outer tank 112. The pump 171 is an example of a second pump.

[0198] The pump 171 forms a circulating flow of the etching solution L that leaves the outer bath 112, passes through the circulation path 170, and returns to the outer bath 112. The back pressure valve 173 adjusts the pressure in the circulation path 170 on the upstream side of the back pressure valve 173 (for example, the branching portion 172).

[0199] The discharge section 160 in the modified example has a discharge path 161, a valve 162, a flow meter 163, a constant pressure valve 164, a throttle valve 165, a cooling tank 166, a valve 181, a return path 182, and a valve 183, and discharges the etching liquid L to a drain DR.

[0200] The discharge path 161 is connected to a branching portion 172 of the circulation path 170. In the discharge path 161, a valve 162, a flow meter 163, a constant pressure valve 164, a throttle valve 165, a branching portion 180, a valve 181, and a cooling tank 166 are provided in this order from the upstream side with respect to the branching portion 172.

[0201] The flow meter 163 measures the flow rate of the etching liquid L flowing through the discharge path 161. The constant pressure valve 164 adjusts the pressure on the downstream side of the constant pressure valve 164 in the discharge path 161. The throttle valve 165 adjusts the flow rate of the etching liquid L flowing through the discharge path 161.

[0202] The cooling tank 166 temporarily stores and cools the etching liquid L that has flowed through the discharge path 161. A return path 182 that returns the etching liquid L to the outer tank 112 branches off from the branching part 180. The return path 182 has a valve 183.

[0203] Similarly to the embodiment, the discharge unit 160 having the configuration described above controls the discharge amount of the etching liquid L to be fixed and controls the supply amount of the mixed liquid M to be variable in the concentration maintenance process.

[0204] As a result, even if the phosphoric acid concentration in the mixed liquid M generated in the phosphoric acid supply unit 100 varies, the silicic acid concentration in the etching liquid L can be maintained, so that the etching process of the wafer W can be performed stably.

[0205] In a modified example, the control unit 8 (see FIG. 4) may return the etching liquid L flowing through the discharge path 161 to the processing tank 61 through the return path 182 when it is not necessary to discharge the etching liquid L from the processing tank 61.

[0206] That is, when it is not necessary to discharge the etching liquid L from the processing tank 61, the control unit 8 changes the valve 181 to a closed state and the valve 183 to an open state, so as to circulate the etching liquid L using the circulation path 170, the discharge path 161, and the return path 182.

[0207] This makes it possible to uniformly maintain a state in which the etching liquid L is discharged from the discharge path 161 (i.e., a state in which discharge of the etching liquid L is necessary) and a state in which the etching liquid L is not discharged from the discharge path 161 (i.e., a state in which discharge of the etching liquid L is not necessary).

[0208] Therefore, according to the modified example, the etching liquid L can be discharged more accurately, and therefore the discharge amount maintenance process can be performed more accurately.

[0209] In a modified example, the inner diameter of the pipe forming the circulation path 170 may be smaller than the inner diameter of the pipe forming the circulation path 120, and the capacity of the pump 171 may be smaller than the capacity of the pump 121. For example, in a modified example, the circulation flow rate of the circulation path 170 generated by the pump 171 may be less than 10 (L / min).

[0210] This can reduce the pulsation of the pump 171, thereby reducing the variation in the amount of etching liquid L discharged per unit time caused by the pulsation. Therefore, according to the modified example, the etching process of the wafer W can be performed more stably.

[0211] In a modified example, the control unit 8 may throttle the back pressure valve 173 during the discharge process of the etching liquid L. This allows the control unit 8 to increase the pressure at the branching part 172 in the circulation path 170, thereby ensuring the pressure required to discharge the etching liquid L from the branching part 172 through the discharge path 161 to the drain DR.

[0212] The substrate processing apparatus (substrate processing system 1) according to the embodiment includes a processing tank 61, a liquid amount sensor (liquid level sensor 113), a concentration sensor 125, a phosphoric acid supply unit 100, a pure water supply unit (DIW supply unit 130), a discharge unit 160, and a control unit 8. The processing tank 61 processes a substrate (wafer W) by immersing it in a processing liquid (etching liquid L) containing a silicic acid compound and phosphoric acid. The liquid amount sensor (liquid level sensor 113) measures the amount of the processing liquid (etching liquid L) stored in the processing tank 61. The concentration sensor 125 measures the phosphoric acid concentration in the processing liquid (etching liquid L) stored in the processing tank 61. The phosphoric acid supply unit 100 supplies an aqueous phosphoric acid solution (mixed liquid M) containing phosphoric acid to the processing tank 61. The pure water supply unit (DIW supply unit 130) supplies pure water (DIW) to the processing tank 61. The discharge unit 160 discharges the processing liquid (etching liquid L) from the processing tank 61. The control unit 8 controls each unit. The control unit 8 also has a discharge amount maintaining unit 8c and a supply amount control unit 8d. The discharge amount maintaining unit 8c maintains the amount of processing liquid (etching liquid L) discharged per hour from the discharge unit 160 at a given value (discharge amount D1). The supply amount control unit 8d controls the supply amounts of the phosphoric acid aqueous solution and pure water supplied from the phosphoric acid supply unit 100 and the pure water supply unit to the processing tank 61, respectively, so that the storage amount of the processing liquid (etching liquid L) and the phosphoric acid concentration in the processing tank 61 are maintained at given values, respectively. This allows the etching process of the wafer W to be performed stably.

[0213] Moreover, in the substrate processing apparatus (substrate processing system 1) according to the embodiment, the processing tank 61 has an inner tank 111 and an outer tank 112. The inner tank 111 has an opening 111a at an upper portion, and stores a processing liquid (etching liquid L). The outer tank 112 is disposed outside the inner tank 111, and receives the processing liquid flowing out from the opening 111a. The liquid amount sensor is a liquid level sensor 113 provided in the outer tank 112. This makes it possible to easily measure the amount of the etching liquid L stored in the processing tank 61 having the inner tank 111 and the outer tank 112.

[0214] Moreover, in the substrate processing apparatus (substrate processing system 1) according to the embodiment, the processing tank 61 has a first circulation path (circulation path 120), a first pump (pump 121), and a first heater (heater 122). The first circulation path (circulation path 120) leaves the processing tank 61 and returns to the processing tank 61. The first pump (pump 121) and the first heater (heater 122) are provided in the first circulation path (circulation path 120). This allows the etching solution L to be efficiently heated.

[0215] Moreover, in the substrate processing apparatus (substrate processing system 1) according to the embodiment, the discharge unit 160 has a discharge path 161, a flow meter 163, and a constant pressure valve 164. The discharge unit 160 branches off from the downstream side of the first pump (pump 121) in the first circulation path (circulation path 120). The flow meter 163 and the constant pressure valve 164 are provided in the discharge path 161. Moreover, the discharge amount maintaining unit 8c controls the valve opening degree of the constant pressure valve 164 so that the measurement value of the flow meter 163 is maintained at a given value (discharge amount D1). This makes it possible to perform the discharge amount maintaining process stably and accurately.

[0216] In the substrate processing apparatus (substrate processing system 1) according to the embodiment, the discharge unit 160 has a second circulation path (circulation path 170), a second pump (pump 171), a discharge path 161, a flowmeter 163, and a constant pressure valve 164. The second circulation path (circulation path 170) leaves the processing tank 61 and returns to the processing tank 61. The second pump (pump 171) is provided in the second circulation path (circulation path 170). The discharge path 161 branches off from the downstream side of the second pump (pump 171) in the second circulation path (circulation path 170). The flowmeter 163 and the constant pressure valve 164 are provided in the discharge path 161. The discharge amount maintaining unit 8c controls the valve opening degree of the constant pressure valve 164 so that the measurement value of the flowmeter 163 is maintained at a given value (discharge amount D1). This allows the discharge amount maintaining process to be performed stably and accurately.

[0217] In the substrate processing apparatus (substrate processing system 1) according to the embodiment, the circulation flow rate in the second circulation path (circulation path 170) generated by the second pump (pump 171) is less than 10 (L / min). This makes it possible to perform the etching process of the wafer W more stably.

[0218] Moreover, in the substrate processing apparatus (substrate processing system 1) according to the embodiment, the discharge section 160 has a back pressure valve 173 provided in the second circulation path (circulation path 170) downstream of the branch point of the discharge path 161. This makes it possible to ensure a pressure required for discharging the etching liquid L from the branch point 172 through the discharge path 161 to the drain DR.

[0219] In addition, in the substrate processing apparatus (substrate processing system 1) according to the embodiment, the phosphoric acid supplying unit 100 includes a tank 220, a third circulation path (circulation path 230), a third pump (pump 231), and a second heater (heater 233). The tank 220 stores the phosphoric acid aqueous solution (mixed liquid M). The third circulation path (circulation path 230) leaves the tank 220 and returns to the tank 220. The third pump (pump 231) and the second heater (heater 233) are provided in the third circulation path (circulation path 230). In addition, the phosphoric acid supplying unit 100 circulates the phosphoric acid aqueous solution (mixed liquid M) in the third circulation path (circulation path 230) while heating the phosphoric acid aqueous solution (mixed liquid M) with the second heater (heater 233). This allows the mixed liquid M to be efficiently heated.

[0220] <Control process procedure> Next, a procedure of a control process according to the embodiment and the modified example will be described with reference to Fig. 10. Fig. 10 is a flow chart showing an example of a procedure of a control process executed by the substrate processing system 1 according to the embodiment.

[0221] In the control process according to the embodiment, first, the control unit 8 starts a concentration maintaining process for maintaining the concentration of the etching liquid L in the etching process of the wafer W performed in the processing tank 61 (step S101).

[0222] Next, the control unit 8 measures the amount of the etching liquid L stored in the treatment tank 61 (step S102). Then, the control unit 8 measures the phosphoric acid concentration in the etching liquid L stored in the treatment tank 61 (step S103).

[0223] Next, the control unit 8 maintains the discharge rate per hour of the etching solution L discharged from the treatment tank 61 at a given value (step S104). Then, the control unit 8 controls the supply rates of the mixed solution M and DIW supplied to the treatment tank 61 so that the amount of the etching solution L stored in the treatment tank 61 and the phosphoric acid concentration are maintained at given values ​​(step S105).

[0224] Next, the control unit 8 determines whether the etching process of the wafer W in the processing tank 61 has been completed (step S106). If the etching process of the wafer W in the processing tank 61 has been completed (step S106, Yes), the control unit 8 ends the series of control processes. On the other hand, if the etching process of the wafer W in the processing tank 61 has not been completed (step S106, No), the control unit 8 returns to the process of step S102.

[0225] The substrate processing method according to the embodiment includes a liquid amount measuring step (step S102), a concentration measuring step (step S103), a discharge amount maintaining step (step S104), and a supply amount controlling step (step S105). The liquid amount measuring step (step S102) measures the amount of processing liquid (etching liquid L) stored in a processing tank 61 in which a substrate (wafer W) is immersed in the processing liquid (etching liquid L) containing a silicic acid compound and phosphoric acid for processing. The concentration measuring step (step S103) measures the phosphoric acid concentration in the processing liquid (etching liquid L) stored in the processing tank 61. The discharge amount maintaining step (step S104) maintains the discharge amount per hour of the processing liquid (etching liquid L) discharged from the processing tank 61 at a given value. In the supply amount control step (step S105), the supply amounts of the phosphoric acid aqueous solution (mixed liquid M) and the deionized water (DIW) supplied to the processing tank 61 are controlled so that the amount of the processing liquid (etching liquid L) stored in the processing tank 61 and the phosphoric acid concentration are maintained at given values, respectively. This allows the etching process of the wafer W to be performed stably.

[0226] Although the embodiment of the present disclosure has been described above, the present disclosure is not limited to the above embodiment, and various modifications are possible without departing from the spirit of the present disclosure. For example, in the above embodiment, the device structure formed on the wafer W is a laminated silicon nitride film and a silicon oxide film, but the device structure formed on the wafer W is not limited to this example.

[0227] The disclosed embodiments should be considered to be illustrative and not restrictive in all respects. Indeed, the above-described embodiments may be embodied in various forms. Furthermore, the above-described embodiments may be omitted, substituted, or modified in various forms without departing from the scope and spirit of the appended claims. [Explanation of symbols]

[0228] 1. Substrate processing system (an example of a substrate processing apparatus) 7 Control Device 8. Control Unit 8a Liquid volume measuring section 8b Concentration measuring section 8c Emission Maintenance Department 8d Supply amount control section 61 Treatment tank 100 Phosphate supply unit 110 Substrate processing section 111 Inner tank 111a opening 112 Outer tank 113 Liquid level sensor (an example of a liquid level sensor) 120 Circulation Route (Example of the First Circulation Route) 121 Pump (example of the first pump) 122 Heater (an example of the first heater) 125 Concentration Sensor 130 DIW supply section (an example of a pure water supply section) 160 Discharge section 161 Exhaust channel 163 Flow meter 164 Constant Pressure Valve 170 Circulation Route (An example of the second circulation route) 171 Pump (Example of the second pump) 173 Backpressure valve 220 Tank 230 Circulation Route (an example of the 3rd Circulation Route) 231 Pump (Example of the third pump) 233 Heater (an example of a second heater) W wafer (example of substrate) L Etching solution (an example of a processing solution) M Mixture (Example of phosphoric acid aqueous solution)

Claims

1. a treatment tank for immersing a substrate in a treatment solution containing a silicic acid compound and phosphoric acid; a liquid level sensor that measures the amount of the processing liquid stored in the processing tank; a concentration sensor for measuring a phosphoric acid concentration in the treatment solution stored in the treatment tank; A phosphoric acid supply unit that supplies an aqueous phosphoric acid solution containing phosphoric acid to the treatment tank; a pure water supply unit for supplying pure water to the treatment tank; a discharge section for discharging the treatment liquid from the treatment tank; A control unit for controlling each unit; Equipped with The control unit is a discharge maintaining unit that maintains a discharge amount of the treatment liquid per unit time from the discharge unit at a given value; a supply amount control unit that controls the supply amounts of the aqueous phosphoric acid solution and the pure water supplied from the phosphoric acid supply unit and the pure water supply unit to the treatment tank, respectively, so that the storage amount of the treatment liquid and the phosphoric acid concentration in the treatment tank are maintained at given values, respectively; have Substrate processing equipment.

2. The treatment tank comprises: an inner tank having an opening at an upper portion and configured to store the treatment liquid; an outer tank disposed outside the inner tank and configured to receive the treatment liquid flowing out from the opening; having The liquid level sensor is a liquid level sensor provided in the outer tank. The substrate processing apparatus according to claim 1 .

3. The treatment tank comprises: a first circulation path that leaves the treatment tank and returns to the treatment tank; a first pump and a first heater provided in the first circulation path; have The substrate processing apparatus according to claim 1 .

4. The discharge section is a discharge passage branching off from the first circulation passage at a downstream side of the first pump; A flow meter and a constant pressure valve provided in the discharge passage; having The discharge amount maintaining unit controls the valve opening degree of the constant pressure valve so that the measurement value of the flow meter is maintained at a given value. The substrate processing apparatus according to claim 3 .

5. The discharge section is a second circulation path that exits the treatment tank and returns to the treatment tank; a second pump provided in the second circulation path; a discharge passage branching off from the second circulation passage at a downstream side of the second pump; A flow meter and a constant pressure valve provided in the discharge passage; having The discharge amount maintaining unit controls the valve opening degree of the constant pressure valve so that the measurement value of the flow meter is maintained at a given value. The substrate processing apparatus according to any one of claims 1 to 3.

6. The circulation flow rate of the second circulation path generated by the second pump is less than 10 (L / min). The substrate processing apparatus according to claim 5 .

7. The discharge section is a back pressure valve provided in the second circulation path downstream of a branch point of the discharge path; The substrate processing apparatus according to claim 5 or 6.

8. The phosphoric acid supply unit is A tank for storing the phosphoric acid aqueous solution; a third circuit leading from the tank and returning to the tank; a third pump and a second heater provided in the third circulation path; having The phosphoric acid aqueous solution is circulated through the third circulation path while being heated by the second heater. The substrate processing apparatus according to any one of claims 1 to 7.

9. a liquid amount measuring step of measuring the amount of a treatment liquid stored in a treatment tank in which a substrate is immersed in the treatment liquid containing a silicic acid compound and phosphoric acid; a concentration measuring step of measuring a phosphoric acid concentration in the treatment solution stored in the treatment tank; a discharge maintaining step of maintaining a discharge amount per unit time of the treatment liquid discharged from the treatment tank at a given value; a supply amount control step of controlling the supply amounts of the aqueous phosphoric acid solution and the pure water supplied to the treatment tank so that the storage amount of the treatment liquid and the phosphoric acid concentration in the treatment tank are maintained at given values, respectively; A substrate processing method comprising:

Images