SUBSTRATE PROCESSING METHOD AND SUBSTRATE PROCESSING APPARATUS

Abstract

To improve a utilization ratio of a phosphoric acid aqueous solution.SOLUTION: A substrate processing method comprises a preparation step, an etching treatment step, and an increasing step. The preparation step adds a deposition inhibitor into a phosphoric acid aqueous solution to prepare a phosphate treatment solution. The etching treatment step immerses a substrate having a silicone oxide film and a silicon nitride film into a treatment tank to perform an etching treatment of the substrate. The increasing step, in the case where the number of substrates to which a re-etching treatment is conducted reaches a first threshold value or a silicon concentration in the phosphate treatment solution reaches a second threshold value, additionally injects the deposition inhibitor into the phosphate treatment solution in the treatment tank to increase the concentration of the deposition inhibitor in the phosphate treatment solution. The etching treatment step immerses a new substrate into the treatment tank in which the phosphate treatment solution increased in concentration of the deposition inhibitor is accumulated, after the step of increasing the concentration of the deposition inhibitor is performed, to conduct an etching treatment to the new substrate.SELECTED DRAWING: Figure 5

Description

[Technical field]

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

[0002] Conventionally, there is known a technique for etching a substrate by immersing the substrate in an aqueous phosphoric acid solution containing a precipitation inhibitor that inhibits the precipitation of silicon oxide (SiO2) (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-67810 A Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides a technique capable of improving the efficiency of use of an aqueous phosphoric acid solution. [Means for solving the problem]

[0005] A substrate processing method according to an embodiment of the present disclosure includes a preparation step, an etching step, and a step of increasing the concentration of a precipitation inhibitor. In the preparation step, a phosphate treatment liquid is prepared by adding a precipitation inhibitor that inhibits the precipitation of silicon oxide to an aqueous phosphoric acid solution. In the etching step, a substrate having a silicon oxide film and a silicon nitride film is immersed in a treatment tank in which the phosphate treatment liquid is stored to perform an etching treatment on the substrate. In the increasing the concentration of the precipitation inhibitor, when the number of substrates etched with the phosphate treatment liquid reaches a first threshold value, or when the silicon concentration in the phosphate treatment liquid reaches a second threshold value, the precipitation inhibitor is added to the phosphate treatment liquid in the treatment tank to increase the concentration of the precipitation inhibitor in the phosphate treatment liquid. In addition, in the etching step, after the step of increasing the concentration of the precipitation inhibitor, a new substrate is immersed in the treatment tank in which the phosphate treatment liquid in which the concentration of the precipitation inhibitor has been increased is stored to perform an etching treatment on the new substrate. Effect of the Invention

[0006] According to the present disclosure, the efficiency of use of an aqueous phosphoric acid solution can be improved. [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 an explanatory diagram of the mechanism by which the precipitation inhibitor inhibits the precipitation of silicon oxide. [Figure 4] FIG. 4 is an explanatory diagram of the mechanism of the selectivity adjustment by the precipitation inhibitor. [Diagram 5] FIG. 5 is a flowchart showing a series of substrate processing procedures executed by the substrate processing system according to the embodiment. [Figure 6] FIG. 6 is a diagram illustrating an example of the first threshold information. [Figure 7]FIG. 7 is a flow chart showing a series of substrate processing procedures executed by a substrate processing system according to a modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, with reference to the attached drawings, an embodiment of the substrate processing apparatus 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] A technique is known in which a substrate having a pattern in which silicon oxide films (SiO2) and silicon nitride films (SiN) are alternately stacked is immersed in an aqueous solution of phosphoric acid (H3PO4) to selectively etch the silicon nitride film out of the silicon oxide film and the silicon nitride film.

[0010] When a substrate is immersed in an aqueous solution of phosphoric acid, silicon dissolves from the substrate, increasing the silicon concentration in the aqueous solution of phosphoric acid. If the silicon concentration in the aqueous solution of phosphoric acid increases, silicon oxide (SiO2) may precipitate on the silicon oxide film of the substrate. Therefore, a technique is known in which a substrate is etched using an aqueous solution of phosphoric acid to which a precipitation inhibitor (hereinafter also referred to as a "precipitation inhibitor") that inhibits the precipitation of silicon oxide is added.

[0011] Conventionally, phosphoric acid aqueous solution containing a precipitation inhibitor was discarded after each etching process. However, there are hopes for a technology that can improve the usage efficiency of phosphoric acid aqueous solution, for example from the viewpoint of reducing running costs.

[0012] Here, the selectivity between the silicon oxide film and the silicon nitride film changes depending on the silicon concentration in the phosphoric acid aqueous solution. The "selectivity" in the phosphoric acid aqueous solution process is the ratio of the etching rate of the silicon nitride film to the etching rate of the silicon oxide film. As described above, the silicon concentration in the phosphoric acid aqueous solution changes by performing the etching process. Therefore, if the phosphoric acid aqueous solution is reused in multiple etching processes, there is a risk that the selectivity will vary for each etching process. Thus, it is difficult to stably perform the etching process by simply reusing the phosphoric acid aqueous solution.

[0013] It is known that the selectivity of silicon nitride film to silicon oxide film increases as the silicon concentration in the phosphoric acid aqueous solution increases. In other words, the etching rate of silicon oxide film decreases as the silicon concentration in the phosphoric acid aqueous solution increases. In response to this, the inventors of the present application have found, as a result of intensive research, that the etching rate of silicon oxide film at the same silicon concentration increases by increasing the amount of precipitation inhibitor added. In other words, they have found that the selectivity of silicon nitride film to silicon oxide film can be adjusted by increasing the amount of precipitation inhibitor added.

[0014] Based on this result, the substrate processing method according to the present disclosure uses an aqueous phosphoric acid solution containing a precipitation inhibitor (hereinafter, also referred to as a "phosphoric acid processing solution") for multiple etching processes while adding additional amounts of the precipitation inhibitor as needed. This makes it possible to efficiently use the phosphoric acid processing solution (aqueous phosphoric acid solution) while suppressing the variation in the selectivity between the silicon oxide film and the silicon nitride film.

[0015] <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.

[0016] As shown in FIG. 1, a substrate processing system 1 according to the embodiment includes a carrier loading / unloading section 2, a lot formation section 3, a lot placement section 4, a lot transport section 5, a lot processing section 6, and a control section .

[0017] 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.

[0018] The carrier stage 20 places a plurality of carriers 9 transferred from outside. The carrier 9 is a container that accommodates a plurality of (e.g., 25) wafers W arranged vertically in a horizontal position. The carrier transfer mechanism 21 transfers the carriers 9 between the carrier stage 20, carrier stocks 22 and 23, and a carrier placement table 24.

[0019] A plurality of unprocessed wafers W are transferred from the carrier 9 placed on the carrier mounting table 24 to the lot processing section 6 by a substrate transfer mechanism 30 described later. A plurality of processed wafers W are transferred from the lot processing section 6 to the carrier 9 placed on the carrier mounting table 24 by the substrate transfer mechanism 30.

[0020] The lot formation section 3 has a substrate transport mechanism 30 and forms lots. A lot is made up of a plurality of (e.g., 50) wafers W that are simultaneously processed by combining wafers W accommodated in one or a plurality of carriers 9. The plurality of wafers W that form one lot are arranged at regular intervals with their plate surfaces facing each other.

[0021] The substrate transfer mechanism 30 transfers a plurality of wafers W between the carrier 9 placed on the carrier placement table 24 and the lot placement part 4.

[0022] 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.

[0023] 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.

[0024] Rails 51 are disposed 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 disposed on mobile body 52, and holds a plurality of wafers W lined up in front of and behind each other in an upright position.

[0025] The lot processing section 6 collectively performs processes such as etching, cleaning, and drying on one lot of 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.

[0026] The etching processing device 60 performs an etching process on one lot of multiple wafers W in a batch. The cleaning processing device 70 performs a cleaning process on one lot of multiple wafers W in a batch. The cleaning processing device 80 performs a cleaning process on the substrate holder 53. The drying processing device 90 performs a drying process on one lot of multiple wafers W in a batch. The numbers of the etching processing devices 60, cleaning processing devices 70, cleaning processing devices 80, and drying processing devices 90 are not limited to the example in FIG. 1.

[0027] 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 .

[0028] The processing tank 61 is capable of accommodating one lot of wafers W arranged in an upright position, and stores a chemical liquid for the etching process, specifically, the above-mentioned phosphoric acid processing liquid. The processing tank 61 will be described in detail later.

[0029] A processing liquid (deionized water, etc.) for rinsing processing is stored in the processing bath 62. The substrate lifting mechanisms 63, 64 hold a plurality of wafers W forming a lot in an upright position lined up one behind the other.

[0030] In the etching processing device 60, the lot transported by the lot transport section 5 is held by the substrate lifting mechanism 63 and immersed in the phosphoric acid processing solution in the processing bath 61 to perform the etching processing. The etching processing is performed for about 1 hour to 3 hours, for example.

[0031] 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.

[0032] 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).

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] The control unit 7 controls the operation of each unit (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 unit 7 controls the operation of each unit of the substrate processing system 1 based on signals from switches, various sensors, and the like.

[0040] The control unit 7 includes a microcomputer and various circuits having a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), an input / output port, etc. The control unit 7 controls the operation of the substrate processing system 1 by reading and executing a program stored in a storage unit (not shown).

[0041] The control unit 7 has a computer-readable storage medium 8. The storage medium 8 stores the above-mentioned programs for controlling various processes executed in the substrate processing system 1. The programs may be stored in the computer-readable storage medium 8 or may be installed in the storage medium 8 of the control unit 7 from another storage medium.

[0042] Examples of the computer-readable storage medium 8 include a hard disk (HD), a flexible disk (FD), a compact disk (CD), a magnet optical disk (MO), and a memory card.

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

[0044] The etching apparatus 60 includes a phosphating solution supply unit 100 and a substrate processing unit 110. The phosphating solution supply unit 100 prepares a phosphating solution L and supplies it to the substrate processing unit 110.

[0045] The phosphating solution supply unit 100 includes an aqueous phosphoric acid solution supply unit 101, a precipitation inhibitor supply unit 103, a mixing mechanism 104, a phosphating solution supply path 105, and a flow rate regulator .

[0046] The aqueous phosphoric acid solution supply unit 101 supplies an aqueous phosphoric acid solution to the mixing mechanism 104. The aqueous phosphoric acid solution supply unit 101 includes an aqueous phosphoric acid solution supply source 101a, an aqueous phosphoric acid solution supply path 101b, and a flow rate regulator 101c.

[0047] The aqueous phosphoric acid solution supply source 101a is, for example, a tank that stores an aqueous phosphoric acid solution. The aqueous phosphoric acid solution supply path 101b connects the aqueous phosphoric acid solution supply source 101a and the mixing mechanism 104 and supplies the aqueous phosphoric acid solution from the aqueous phosphoric acid solution supply source 101a to the mixing mechanism 104.

[0048] The flow rate regulator 101c is disposed in the phosphoric acid aqueous solution supply path 101b, and regulates the flow rate of the phosphoric acid aqueous solution supplied to the mixing mechanism 104. The flow rate regulator 101c includes an on-off valve, a flow rate control valve, a flow meter, and the like.

[0049] The precipitation inhibitor supplying unit 103 supplies the precipitation inhibitor to the mixing mechanism 104. The precipitation inhibitor supplying unit 103 includes a precipitation inhibitor supply source 103a, a precipitation inhibitor supply path 103b, and a flow rate regulator 103c.

[0050] The deposition inhibitor supply source 103a is, for example, a tank that stores the deposition inhibitor. The deposition inhibitor supply path 103b connects the deposition inhibitor supply source 103a and the mixing mechanism 104 and supplies the deposition inhibitor from the deposition inhibitor supply source 103a to the mixing mechanism 104.

[0051] The flow rate regulator 103c is disposed in the deposition inhibitor supply path 103b, and regulates the flow rate of the deposition inhibitor supplied to the mixing mechanism 104. The flow rate regulator 103c includes an on-off valve, a flow control valve, a flow meter, and the like.

[0052] 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.

[0053] The deposition inhibitor according to the embodiment may be, for example, an aqueous solution of hexafluorosilicic acid (H2SiF6) containing a fluorine component. The deposition inhibitor may also contain an additive such as ammonia to stabilize the hexafluorosilicic acid in the aqueous solution.

[0054] As the precipitation inhibitor according to the embodiment, for example, ammonium hexafluorosilicate (NH4)2SiF6, sodium hexafluorosilicate (Na2SiF6), or the like can be used.

[0055] 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.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] Moreover, the precipitation inhibitor supplying unit 103 according to the embodiment also supplies the precipitation inhibitor to the treatment tank 61. Specifically, the precipitation inhibitor supplying unit 103 further includes a treatment tank supply path 103d and a switching valve 103e.

[0061] The treatment tank supply path 103d is a flow path branched off from the precipitation inhibitor supply path 103b. A discharge portion 103f corresponding to the tip of the treatment tank supply path 103d is located above the inner tank 111 of the treatment tank 61. Specifically, the discharge portion 103f is located at a position higher than the liquid level of the phosphoric acid treatment solution L stored in the inner tank 111. The switching valve 103e is provided at the branch point of the precipitation inhibitor supply path 103b and the treatment tank supply path 103d, and switches the outflow destination of the precipitation inhibitor between the mixing mechanism 104 and the treatment tank 61.

[0062] In this manner, the precipitation inhibitor supply unit 103 can supply the precipitation inhibitor stored in the precipitation inhibitor supply source 103a to the inner tank 111 via the treatment tank supply path 103d.

[0063] The mixing mechanism 104 mixes the phosphoric acid aqueous solution and the precipitation inhibitor to generate the phosphoric acid treatment solution L. That is, the phosphoric acid treatment solution L according to the embodiment contains at least the phosphoric acid aqueous solution and the precipitation inhibitor. As will be described later, the phosphoric acid treatment solution L may further contain a silicon solution.

[0064] As an example, the mixing mechanism 104 includes a tank and a circulation path. The circulation path is provided with a pump, a filter, a heater, and the like. The mixing mechanism 104 can mix the liquids stored in the tank by circulating the liquids stored in the tank using the circulation path. The mixing mechanism 104 can also heat the liquids to a desired temperature using a heater provided in the circulation path.

[0065] The precipitation inhibitor according to the embodiment contains an alcohol as a solvent. The alcohol contained as the solvent is, for example, any one of methanol, ethanol, propyl alcohol, and isopropyl alcohol. Thus, the phosphoric acid treatment solution L according to the embodiment contains an aqueous phosphoric acid solution and the above-mentioned alcohol.

[0066] The phosphoric acid treatment solution supply passage 105 connects the mixing mechanism 104 to the outer tank 112 of the treatment tank 61 , and supplies the phosphoric acid treatment solution L from the mixing mechanism 104 to the outer tank 112 .

[0067] The flow rate regulator 106 is disposed in the phosphoric acid treatment solution supply passage 105, and regulates the flow rate of the phosphoric acid treatment solution L supplied to the outer bath 112. The flow rate regulator 106 includes an on-off valve, a flow rate control valve, a flow meter, and the like.

[0068] The substrate processing unit 110 immerses the wafer W in the phosphoric acid processing solution L supplied from the phosphoric acid processing solution supply unit 100, and performs an etching process on the wafer W. The wafer W is an example of a substrate. In the embodiment, for example, of a silicon nitride film and a silicon oxide film formed on the wafer W, the silicon nitride film can be selectively etched.

[0069] 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 silicon solution supply unit 135, a gas supply unit 140, and a processing liquid discharge unit 150. The processing tank 61 includes an inner tank 111, an outer tank 112, and a lid 113.

[0070] The inner tank 111 is a tank for immersing the wafer W in the phosphoric acid treatment liquid L, and contains the phosphoric acid treatment liquid L for immersion. The inner tank 111 has an opening 111a at the top, and the phosphoric acid treatment liquid L is stored up to the vicinity of the opening 111a of the inner tank 111.

[0071] In the inner tank 111, a plurality of wafers W are immersed in the phosphoric acid treatment solution L using the substrate lifting mechanism 63, and etching is performed 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.

[0072] The outer tank 112 is disposed outside the inner tank 111 so as to surround the inner tank 111, and receives the phosphoric acid treatment 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.

[0073] Further, the outer bath 112 has a temperature sensor (not shown). The temperature sensor detects the temperature of the phosphoric acid treatment solution L. A signal generated by the temperature sensor of the outer bath 112 is transmitted to the control unit 7 described above.

[0074] The inner tank 111, the outer tank 112, and the lid 113 are made of a material having high heat resistance and chemical resistance, such as quartz. This allows the control unit 7 to etch the wafer W with the phosphoric acid treatment solution L maintained at a high temperature (e.g., 150° C. or higher), thereby enabling the wafer W to be etched efficiently.

[0075] 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 125 located in the inner bath 111.

[0076] In the circulation path 120, a pump 121, a heater 122, a filter 123, and a silicon concentration meter 124 are positioned in this order from the outer bath 112 side.

[0077] The pump 121 forms a circulating flow of the phosphoric acid processing solution L that is sent from the outer bath 112 through the circulation path 120 to the inner bath 111. The phosphoric acid processing solution L overflows from the opening 111a of the inner bath 111 and flows back into the outer bath 112. In this manner, a circulating flow of the phosphoric acid processing solution L is formed in the substrate processing unit 110. That is, the circulating flow is formed in the outer bath 112, the circulation path 120, and the inner bath 111.

[0078] The heater 122 adjusts the temperature of the phosphoric acid treatment solution L circulating through the circulation path 120. The filter 123 filters the phosphoric acid treatment solution L circulating through the circulation path 120. The silicon concentration meter 124 detects the silicon concentration of the phosphoric acid treatment solution L circulating through the circulation path 120. A signal generated by the silicon concentration meter 124 is transmitted to the control unit 7.

[0079] The DIW supply unit 130 includes a DIW supply source 130a, a DIW supply path 130b, and a flow rate regulator 130c. The DIW supply unit 130 supplies DIW (DeIonized Water) to the outer tank 112 in order to adjust the concentration of the phosphoric acid treatment solution L stored in the treatment tank 61.

[0080] The DIW supply path 130b connects the DIW supply source 130a and the outer bath 112, and supplies DIW at a predetermined temperature from the DIW supply source 130a to the outer bath 112.

[0081] The flow rate regulator 130c is disposed in the DIW supply path 130b and regulates the amount of DIW supplied to the outer bath 112. The flow rate regulator 130c 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 130c, whereby the temperature, phosphoric acid concentration, silicon concentration, and precipitation inhibitor concentration of the phosphating solution L in the etching processing device 60 are adjusted.

[0082] The silicon solution supply unit 135 supplies a silicon solution to the processing tank 61. The silicon solution supply unit 135 includes a silicon solution supply source 135a, a silicon solution supply path 135b, and a flow rate regulator 135c.

[0083] The silicon solution supply source 135a is, for example, a tank that stores a silicon solution. The silicon solution supply path 135b connects the silicon solution supply source 135a to the inner tank 111 and supplies the silicon solution from the silicon solution supply source 135a to the inner tank 111.

[0084] The flow rate regulator 135c is disposed in the silicon solution supply path 135b and regulates the flow rate of the silicon solution supplied to the inner tank 111. The flow rate regulator 135c includes an on-off valve, a flow rate control valve, a flow meter, etc. The silicon solution according to the embodiment is, for example, a solution in which colloidal silicon is dispersed.

[0085] The gas supply unit 140 discharges bubbles of an inert gas (for example, nitrogen gas) into the phosphoric acid treatment solution L stored in the inner tank 111. The gas supply unit 140 includes an inert gas supply source 140a, an inert gas supply path 140b, a flow rate regulator 140c, and a gas nozzle 140d.

[0086] The inert gas supply path 140b connects the inert gas supply source 140a and the gas nozzle 140d, and supplies an inert gas (for example, nitrogen gas) from the inert gas supply source 140a to the gas nozzle 140d.

[0087] The flow rate regulator 140c is disposed in the inert gas supply path 140b and regulates the amount of inert gas supplied to the gas nozzle 140d. The flow rate regulator 140c includes an on-off valve, a flow rate control valve, a flow meter, and the like.

[0088] The gas nozzle 140d is located, for example, in the inner bath 111 below the wafer W and the processing liquid supply nozzle 125. The gas nozzle 140d ejects bubbles of an inert gas into the phosphoric acid processing liquid L stored in the inner bath 111.

[0089] The etching processing apparatus 60 according to the embodiment can supply a fast flow of the phosphoric acid processing solution L to the gaps between the multiple wafers W arranged side by side in the inner tank 111 by discharging bubbles of inert gas from the gas nozzle 140d. Therefore, according to the embodiment, the multiple wafers W can be etched efficiently and uniformly.

[0090] The processing solution discharge unit 150 discharges the phosphoric acid processing solution L to the drain DR, for example, when replacing the used phosphoric acid processing solution L with a new solution. The processing solution discharge unit 150 has a discharge path 150a, a flow rate regulator 150b, and a cooling tank 150c.

[0091] The discharge path 150a is connected to the circulation path 120. The flow rate regulator 150b is disposed on the discharge path 150a and regulates the amount of the discharged phosphoric acid treatment solution L. The flow rate regulator 150b includes an on-off valve, a flow rate control valve, a flow meter, and the like.

[0092] The cooling tank 150c temporarily stores and cools the phosphoric acid treatment liquid L that has flowed through the discharge path 150a. In the cooling tank 150c, the discharge rate of the phosphoric acid treatment liquid L is adjusted by the flow rate adjuster 150b.

[0093] Here, as described above, the precipitation inhibitor supply unit 103 according to the embodiment supplies the precipitation inhibitor to the inner tank 111. The precipitation inhibitor supplied to the inner tank 111 overflows from the inner tank 111 and moves to the outer tank 112, and returns from the outer tank 112 to the inner tank 111 through the circulation path 120. This cycle allows the substrate processing system 1 to mix the additionally added precipitation inhibitor with the phosphoric acid treatment solution L. In addition, in the inner tank 111, a liquid flow of the phosphoric acid treatment solution L is formed by the gas discharged from the gas supply unit 140. By utilizing this liquid flow, the additionally added precipitation inhibitor and the phosphoric acid treatment solution L can be mixed more quickly.

[0094] Further, the deposition inhibitor supply unit 103 supplies the deposition inhibitor by dripping onto the liquid surface of the phosphoric acid treatment solution L in the inner tank 111 from the discharge portion 103f of the treatment tank supply path 103d.

[0095] The alcohol contained as a solvent in the precipitation inhibitor has a lower boiling point than phosphoric acid. Therefore, if the precipitation inhibitor is simply supplied to the high-temperature phosphoric acid treatment solution L, the alcohol in the precipitation inhibitor may boil in the high-temperature phosphoric acid treatment solution L, causing a large amount of bubbles to be generated in the phosphoric acid treatment solution L. In addition, if the phosphoric acid treatment solution L containing a large amount of bubbles overflows from the treatment tank 61, the amount of liquid in the treatment tank 61 may be significantly reduced, making it difficult to stably perform the etching process.

[0096] In response to this, by supplying the precipitation inhibitor to the phosphoric acid treatment solution L in small amounts by dropwise addition, bumping of the precipitation inhibitor can be suppressed.

[0097] <Selectivity adjustment mechanism using precipitation inhibitors> As described above, the inventors of the present application have found that it is possible to adjust the selectivity of a silicon nitride film to a silicon oxide film. The mechanism will be described with reference to Figs. 3 and 4. Fig. 3 is an explanatory diagram of the mechanism of silicon oxide precipitation inhibition by a precipitation inhibitor. Fig. 4 is an explanatory diagram of the mechanism of selection ratio adjustment by a precipitation inhibitor.

[0098] During the etching process, the following reactions occur in the processing bath 61: SiO2+2H2O⇔Si(OH)4 The deposition of silicon oxide occurs when Si(OH)4 in the phosphoric acid treatment solution L comes into contact with the silicon oxide film.

[0099] 3, component S (silane coupling agent) contained in the precipitation inhibitor bonds with the silicon oxide film on the wafer W. As a result, the surface of the silicon oxide film is coated with component S, making it difficult for Si(OH)4 in the phosphoric acid treatment solution L to come into contact with the silicon oxide film. As a result, the precipitation of silicon oxide is suppressed.

[0100] In FIG. 3, it is assumed that the concentration of the precipitation inhibitor in the phosphoric acid treatment solution L is C1. On the other hand, FIG. 4 shows a state in which the concentration of the precipitation inhibitor in the phosphoric acid treatment solution L is increased from C1 to C2. As shown in FIG. 4, when the concentration of the precipitation inhibitor is increased, the component S of the precipitation inhibitor is bonded not only to the silicon oxide film on the wafer W but also to Si(OH)4 in the phosphoric acid treatment solution L. As a result, the active Si(OH)4 is reduced, and the reaction proceeding to the right in the above reaction formula, that is, the reaction SiO2+2H2O→Si(OH)4, becomes more likely to proceed. In other words, the etching rate of the silicon oxide film increases. Therefore, by controlling the concentration of the precipitation inhibitor, it is possible to adjust the selectivity of the silicon nitride film to the silicon oxide film.

[0101] <Specific Operation of Substrate Processing System 1> Next, a specific operation of the substrate processing system 1 will be described with reference to Fig. 5. Fig. 5 is a flow chart showing a series of substrate processing procedures executed by the substrate processing system 1 according to the embodiment. Each processing procedure shown in Fig. 5 is executed under the control of the control unit 7. Fig. 5 mainly shows the processing procedures in the etching processing device 60, and omits processing in other devices, such as the cleaning processing device 70.

[0102] 5, a preparation process is first performed (step S101) in the substrate processing system 1. The preparation process is a process in which the phosphating process liquid L is prepared using the phosphating process liquid supply unit 100 and the prepared phosphating process liquid L is sent to the processing tank 61.

[0103] Specifically, first, the phosphoric acid aqueous solution supply unit 101 is operated to supply the phosphoric acid aqueous solution from the phosphoric acid aqueous solution supply source 101a to the tank of the mixing mechanism 104. Next, while circulating the phosphoric acid aqueous solution using the circulation path of the mixing mechanism 104, the phosphoric acid aqueous solution is heated to a desired temperature using a heater provided in the circulation path. This causes the phosphoric acid aqueous solution to be concentrated.

[0104] In parallel with the concentration of the phosphoric acid aqueous solution, the precipitation inhibitor supply unit 103 is operated to supply a constant amount of the precipitation inhibitor from the precipitation inhibitor supply source 103a to the tank of the mixing mechanism 104. The precipitation inhibitor supplied to the tank of the mixing mechanism 104 is mixed with the phosphoric acid aqueous solution by circulating through the circulation path together with the phosphoric acid aqueous solution. As a result, the phosphoric acid treatment solution L is produced in the tank of the mixing mechanism 104.

[0105] Next, the on-off valve of the flow rate regulator 106 is opened to supply the phosphating solution L stored in the tank to the treatment tank 61. The phosphating solution L supplied to the treatment tank 61 is adjusted to a desired temperature by the heater 122 while circulating through the circulation path 120. Thereafter, the silicon solution supply unit 135 is operated to supply silicon solution from the silicon solution supply source 135a to the treatment tank 61. Also, the gas supply unit 140 is operated to supply an inert gas into the inside of the inner tank 111. As a result, a liquid flow of the phosphating solution L is formed by the inert gas.

[0106] Next, in the substrate processing system 1, an etching process is performed (step S102). Specifically, first, a lot formed of a plurality of (e.g., 50) wafers W is held by the substrate lifting mechanism 63, and then the substrate lifting mechanism 63 is lowered to place the wafers W inside the inner bath 111. As a result, the plurality of wafers W are immersed in the phosphoric acid processing solution L in the processing bath 61. Thereafter, the state in which the plurality of wafers W are immersed in the phosphoric acid processing solution L in the processing bath 61 is maintained for a predetermined time (e.g., about 1 hour to 3 hours). Thereafter, the substrate lifting mechanism 63 is raised to lift the plurality of wafers W from the inner bath 111.

[0107] The plurality of wafers W pulled up from the inner bath 111 are transferred to the processing bath 62 by the lot transfer unit 5. Then, the etching processing device 60 holds the transferred lot by the substrate lifting mechanism 64 and performs a rinsing process by immersing the lot in the rinsing liquid in the processing bath 62. The lot that has been rinsed in the processing bath 62 is transferred by the lot transfer unit 5 to the processing bath 71 of the cleaning processing device 70.

[0108] Next, the control unit 7 counts up the number of processed sheets (step S103) and also counts up the total number of processed sheets (step S104).

[0109] Here, the number of processed wafers refers to the number of wafers W etched in step S102 before the precipitation inhibitor is additionally added in step S108, which will be described later. Specifically, if the etching process in step S102 is the first etching process after the preparation process in step S101 (hereinafter also referred to as the "initial etching process"), the number of processed wafers corresponds to the number of wafers from the initial etching process until the precipitation inhibitor is additionally added. Also, if the etching process in step S102 is the second or subsequent etching process, the number of processed wafers corresponds to the number of wafers from the addition of the precipitation inhibitor in step S108 until the next additional addition of the precipitation inhibitor in step S108.

[0110] The total number of processed wafers refers to the number of wafers W etched in step S102 from the preparation process in step S101 to the waste liquid process in step S111, which will be described later. In other words, the total number of processed wafers refers to the total number of wafers processed from the initial etching process.

[0111] For example, when one lot is formed of 50 sheets, the control unit 7 counts up the number of processed sheets by 50 sheets in step S103, and counts up the total number of processed sheets by 50 sheets in step S104.

[0112] Next, the control unit 7 judges whether the total number of processed substrates is equal to or greater than the third threshold, in other words, whether the total number of processed substrates has reached the third threshold (step S105). In this process, if the total number of processed substrates has not reached the third threshold (step S105, No), the control unit 7 sets a first threshold according to the number of additional additions of the precipitation inhibitor (step S106). This point will be described with reference to FIG. 6. FIG. 6 is a diagram showing an example of first threshold information. The first threshold information is stored in a storage unit (not shown) of the substrate processing system 1.

[0113] As shown in FIG. 6, the first threshold information is information that associates the number of additional additions of the precipitation inhibitor with the first threshold. In the example shown in FIG. 6, the first threshold "50 sheets" is associated with the number of additional additions of the precipitation inhibitor "0 times", the first threshold "60 sheets" is associated with the number of additional additions of the precipitation inhibitor "1 time", and the first threshold "70 sheets" is associated with the number of additional additions of the precipitation inhibitor "2 times". In this case, when the number of additional additions of the precipitation inhibitor is "0 times", the control unit 7 sets the first threshold to "50 sheets". Similarly, when the number of additional additions of the precipitation inhibitor is "1 time", the control unit 7 sets the first threshold to "60 sheets", and when the number of additional additions of the precipitation inhibitor is "2 times", the control unit 7 sets the first threshold to "70 sheets".

[0114] In this manner, in the substrate processing system 1 according to the embodiment, the first threshold value is set higher as the number of times the precipitation inhibitor is added increases. The concentration of the precipitation inhibitor in the phosphoric acid processing solution L increases as the precipitation inhibitor is added. The characteristics of the phosphoric acid processing solution L change depending on the concentration of the precipitation inhibitor. Specifically, the phosphoric acid processing solution L exhibits a more gradual decrease in the etching rate of the silicon oxide film relative to the number of wafers W processed as the concentration of the precipitation inhibitor increases. In other words, the higher the concentration of the precipitation inhibitor in the phosphoric acid processing solution L, the higher the upper limit of the number of wafers W processed that can keep the selectivity within the allowable range increases. Therefore, by setting the first threshold value higher as the number of times the precipitation inhibitor is added increases, the selectivity of the silicon nitride film to the silicon oxide film can be appropriately managed even when the precipitation inhibitor is added.

[0115] Returning to Fig. 5, in step S107, the control unit 7 judges whether the number of processed sheets is equal to or greater than the first threshold, in other words, whether the number of processed sheets has reached the first threshold. In this process, if the number of processed sheets has not reached the first threshold (No in step S107), the control unit 7 returns the process to step S102.

[0116] On the other hand, when it is determined in step S107 that the number of processed sheets has reached the first threshold value (Yes in step S107), the control unit 7 additionally supplies a precipitation inhibitor to the processing tank 61 (step S108). Specifically, the control unit 7 operates the precipitation inhibitor supply unit 103 to supply the precipitation inhibitor from the precipitation inhibitor supply source 103a to the inner tank 111. As described above, the precipitation inhibitor is supplied by dripping from a position higher than the liquid level of the phosphoric acid treatment solution L stored in the inner tank 111 to the liquid level of the phosphoric acid treatment solution L. This makes it possible to additionally supply the precipitation inhibitor to the phosphoric acid treatment solution L while suppressing bumping of the precipitation inhibitor.

[0117] The amount of the precipitation inhibitor added in step S108 may be a fixed amount each time. The "fixed amount" may be the same as the amount of the precipitation inhibitor mixed into the phosphoric acid aqueous solution in the blending process in step S101.

[0118] Next, the control unit 7 counts up the number of times the deposition inhibitor is added (step S109). As a result, in the next determination process of step S107, a first threshold value higher than the first threshold value used this time will be used. In addition, the control unit 7 resets the count of the number of processed sheets (step S110). Thereafter, the control unit 7 returns the process to step S102.

[0119] In this manner, in the substrate processing system 1 according to the embodiment, the process of additionally supplying the precipitation inhibitor is performed between the end of one etching process and the start of the next etching process. This makes it possible to suppress the influence of the additional supply of the precipitation inhibitor (for example, a change in the selectivity) during the etching process, as compared with the case where the precipitation inhibitor is additionally supplied during the etching process. Therefore, each etching process can be stably performed.

[0120] On the other hand, when it is determined in step S105 that the total number of processed wafers has reached the third threshold value (step S105, Yes), the control unit 7 performs waste liquid treatment (step S111). Specifically, the control unit 7 operates the treatment liquid discharge unit 150 to discharge all of the phosphoric acid treatment liquid L from the treatment tank 61. Thereafter, the control unit 7 resets the counts of the number of processed wafers, the total number of processed wafers, and the number of times the precipitation inhibitor has been added, and ends the series of processes. Note that the third threshold value is a value greater than the first threshold value.

[0121] In this manner, the substrate processing system 1 according to the embodiment can reuse the phosphoric acid processing solution L prepared in step S101 for a plurality of etching processes by appropriately adding a precipitation inhibitor to the processing tank 61. Therefore, the substrate processing system 1 according to the embodiment can improve the efficiency of use of the aqueous phosphoric acid solution.

[0122] (Modification) In the above-described embodiment, an example has been described in which the timing to additionally supply the precipitation inhibitor is determined based on the number of processed wafers W. However, the present invention is not limited to this, and the control unit 7 may determine the timing to additionally supply the precipitation inhibitor based on the silicon concentration in the phosphoric acid treatment solution L. An example of this case will be described with reference to Fig. 7. Fig. 7 is a flowchart showing a series of substrate processing procedures executed by the substrate processing system 1 according to the modified example.

[0123] 7, in the substrate processing system 1, a compounding process (step S201) is performed, and then an etching process (step S202) is performed. The compounding process in step S201 and the etching process in step S202 are similar to steps S101 and S102 shown in FIG. 5, and therefore will not be described here.

[0124] When the etching process is completed, the control unit 7 acquires the detection result of the silicon concentration meter 124 (step S203). Next, the control unit 7 determines whether the silicon concentration in the phosphoric acid treatment solution L is equal to or higher than the fourth threshold value, in other words, whether the silicon concentration in the phosphoric acid treatment solution L has reached the fourth threshold value (step S204). In this process, if the silicon concentration has not reached the fourth threshold value (step S204, No), the control unit 7 sets a second threshold value according to the number of times the precipitation inhibitor has been added (step S205).

[0125] In the modified example, second threshold information is stored in a storage unit (not shown) of the substrate processing system 1. The second threshold information is information that associates the number of additional additions of the precipitation inhibitor with the second threshold. In the second threshold information, the more the number of additional additions of the precipitation inhibitor, the higher the second threshold is associated with. That is, in the substrate processing system 1 according to the modified example, the more the number of additional additions of the precipitation inhibitor increases, the higher the second threshold is set.

[0126] As described above, the higher the concentration of the precipitation inhibitor in the phosphoric acid treatment solution L, the higher the upper limit of the number of wafers W that can be processed while keeping the selectivity within the allowable range. The silicon concentration in the phosphoric acid treatment solution L increases in proportion to the number of wafers W that can be processed. Therefore, by setting the second threshold higher as the number of times the precipitation inhibitor is additionally added increases, the selectivity of the silicon nitride film to the silicon oxide film can be appropriately controlled even when the precipitation inhibitor is additionally added.

[0127] In step S206, the control unit 7 determines whether the silicon concentration is equal to or greater than the second threshold, in other words, whether the silicon concentration has reached the second threshold. In this process, if the silicon concentration has not reached the second threshold (step S206, No), the control unit 7 returns the process to step S202.

[0128] On the other hand, when it is determined in step S206 that the silicon concentration has reached the second threshold value (Yes in step S206), the control unit 7 additionally adds a precipitation inhibitor to the treatment tank 61 (step S207).

[0129] Next, the control unit 7 counts up the number of times the deposition inhibitor has been additionally added (step S208). As a result, in the next determination process in step S206, a second threshold value higher than the second threshold value used this time will be used.

[0130] On the other hand, when it is determined in step S204 that the silicon concentration has reached the fourth threshold value (Yes in step S204), the control unit 7 performs waste liquid treatment (step S209) and ends a series of processes.

[0131] (Other variations) In the flow chart shown in FIG. 5, the "number of processed sheets" and the "total number of processed sheets" are counted, and the judgment process of step S107 is performed based on the count result of the "number of processed sheets". Without being limited to this, the judgment process of step S107 may be performed based on the count result of the "total number of processed sheets". In this case, the first threshold value may also be a value according to the total number of processed sheets. For example, in the example shown in FIG. 6, the number of additional additions of precipitation inhibitor "1 time" may correspond to 50 sheets + 60 sheets = "110 sheets", and the number of additional additions of precipitation inhibitor "1 time" may correspond to 50 sheets + 60 sheets + 70 sheets = "180 sheets".

[0132] As described above, the substrate processing method according to the embodiment includes a preparation step, an etching step, and a step of increasing the concentration of a precipitation inhibitor. In the preparation step, a phosphate treatment liquid is prepared by adding a precipitation inhibitor that inhibits the precipitation of silicon oxide to a phosphoric acid aqueous solution. In the etching step, a substrate having a silicon oxide film and a silicon nitride film is immersed in a treatment tank in which a phosphate treatment liquid is stored to etch the substrate. In the increasing the concentration of the precipitation inhibitor, when the number of substrates etched with the phosphoric acid treatment liquid reaches a first threshold value or when the silicon concentration in the phosphoric acid treatment liquid reaches a second threshold value, a precipitation inhibitor is added to the phosphoric acid treatment liquid in the treatment tank to increase the concentration of the precipitation inhibitor in the phosphoric acid treatment liquid. In the etching step, after the step of increasing the concentration of the precipitation inhibitor, a new substrate is immersed in a treatment tank in which a phosphoric acid treatment liquid in which the concentration of the precipitation inhibitor has been increased is stored to etch the new substrate.

[0133] Therefore, according to the substrate processing method of the embodiment, it is possible to improve the efficiency of use of the aqueous phosphoric acid solution.

[0134] The substrate processing method according to the embodiment may further include a step of discharging the phosphating solution from the processing tank when the number of substrates etched with the phosphating solution reaches a third threshold value higher than the first threshold value, or when the silicon concentration in the phosphating solution reaches a fourth threshold value higher than the second threshold value.

[0135] The step of increasing the concentration of the precipitation inhibitor may be carried out two or more times between the preparation step and the discharge step.

[0136] The step of increasing the concentration of the precipitation inhibitor may include a step of additionally adding the precipitation inhibitor and a step of circulating. The step of additionally adding the precipitation inhibitor is to additionally add the precipitation inhibitor to the phosphoric acid treatment liquid in the treatment tank. The step of circulating is to circulate the precipitation inhibitor together with the phosphoric acid treatment liquid using a circulation path provided in the treatment tank. This allows the additionally added precipitation inhibitor to be efficiently mixed with the phosphoric acid treatment liquid.

[0137] The treatment tank may have an inner tank and an outer tank. The inner tank has an opening at the top and stores the phosphating solution. The outer tank is disposed outside the inner tank and receives the phosphating solution flowing out from the opening. The inner tank is provided with a gas discharge unit that discharges gas into the inner tank. The step of additionally adding the precipitation inhibitor includes supplying the precipitation inhibitor to the inner tank. In the inner tank, a liquid flow of the phosphating solution is formed by the gas discharged from the gas supply unit. By utilizing this liquid flow, the additionally added precipitation inhibitor and the phosphating solution can be mixed more quickly.

[0138] In the step of additionally adding the precipitation inhibitor, the precipitation inhibitor may be dropped onto the liquid level of the phosphoric acid treatment solution from a position higher than the liquid level of the phosphoric acid treatment solution in the inner tank, thereby making it possible to suppress bumping of the precipitation inhibitor.

[0139] The step of increasing the concentration of the precipitation inhibitor is carried out during the period from the end of one etching process to the start of the next etching process, thereby making it possible to stably carry out each etching process.

[0140] 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]

[0141] 1: Substrate processing system 7: Control section 8:Storage medium 60: Etching treatment device 61: Treatment tank 62: Treatment tank 63: Substrate lifting mechanism 64: Substrate lifting mechanism 100: Phosphating solution supply unit 101: Phosphoric acid aqueous solution supply unit 103: Deposition inhibitor supply unit 103e: Switching valve 103f:Discharge part 104: Mixing mechanism 105: Phosphating solution supply channel 106:Flow rate regulator 110: Substrate processing section 111: Inner tank 111a: Opening 112: Outer tank 113: Lid 120: Circulation path 121: Pump 122: Heater 123: Filter 124: Silicon concentration meter 135: Silicone solution supply unit 140: Gas supply section 150: Processing liquid discharge section L: Phosphate treatment

Claims

1. preparing a phosphoric acid treatment solution by adding a precipitation inhibitor that inhibits precipitation of silicon oxide to an aqueous phosphoric acid solution; a step of etching a substrate having a silicon oxide film and a silicon nitride film by immersing the substrate in a treatment tank containing the phosphoric acid treatment solution; a step of increasing a concentration of the precipitation inhibitor in the phosphoric acid treatment solution by additionally adding the precipitation inhibitor to the phosphoric acid treatment solution in the treatment tank when the number of the substrates etched with the phosphoric acid treatment solution reaches a first threshold value or when the silicon concentration in the phosphoric acid treatment solution reaches a second threshold value; Including, The etching step includes, after the step of increasing the concentration of the precipitation inhibitor, immersing a new substrate in the treatment tank storing the phosphoric acid treatment solution in which the concentration of the precipitation inhibitor has been increased, and etching the new substrate; The step of increasing the concentration of the precipitation inhibitor includes: adding the precipitation inhibitor to the phosphoric acid treatment solution in the treatment tank; circulating the precipitation inhibitor together with the phosphoric acid treatment solution through a circulation path provided in the treatment tank; Including, The treatment tank comprises: an inner tank having an opening at an upper portion and configured to store the phosphoric acid treatment solution; an outer tank disposed outside the inner tank and configured to receive the phosphoric acid treatment solution flowing out from the opening; having The inner tank is provided with a gas discharge part that discharges gas into the inner tank, The step of additionally adding a precipitation inhibitor comprises supplying the precipitation inhibitor to the inner tank.

2. a step of draining all of the phosphoric acid treatment solution from the treatment tank when the number of the substrates that have been etched reaches a third threshold value that is higher than the first threshold value, or when the silicon concentration in the phosphoric acid treatment solution reaches a fourth threshold value that is higher than the second threshold value. The method of claim 1 , comprising:

3. 3. The substrate processing method according to claim 2, wherein the step of increasing the concentration of the precipitation inhibitor is performed two or more times between the step of preparing the precipitation inhibitor and the step of discharging the precipitation inhibitor.

4. 4. The substrate processing method according to claim 1, wherein the step of additionally adding the precipitation inhibitor comprises dripping the precipitation inhibitor onto the liquid surface of the phosphoric acid treatment solution in the inner tank from a position higher than the liquid surface of the phosphoric acid treatment solution.

5. 5. The substrate processing method according to claim 1, wherein the step of increasing the concentration of the precipitation inhibitor is performed during a period from the end of one of the etching processes to the start of a next etching process.

6. A treatment tank; a compounding unit that compounds a phosphoric acid treatment solution by adding a precipitation inhibitor that inhibits the precipitation of silicon oxide to an aqueous phosphoric acid solution; an input section for inputting the deposition inhibitor into the treatment tank; a control unit that executes the steps of controlling the preparation unit to prepare the phosphoric acid treatment liquid, immersing a substrate having a silicon oxide film and a silicon nitride film in the treatment tank in which the phosphoric acid treatment liquid is stored to perform an etching treatment on the substrate, and controlling the precipitation inhibitor to additionally add the precipitation inhibitor to the phosphoric acid treatment liquid in the treatment tank to increase the concentration of the precipitation inhibitor in the phosphoric acid treatment liquid when the number of the substrates etched with the phosphoric acid treatment liquid reaches a first threshold value or when the silicon concentration in the phosphoric acid treatment liquid reaches a second threshold value; Equipped with The etching step includes, after the step of increasing the concentration of the precipitation inhibitor, immersing a new substrate in the treatment tank storing the phosphoric acid treatment solution in which the concentration of the precipitation inhibitor has been increased, and etching the new substrate; The step of increasing the concentration of the precipitation inhibitor includes: adding the precipitation inhibitor to the phosphoric acid treatment solution in the treatment tank; circulating the precipitation inhibitor together with the phosphoric acid treatment solution through a circulation path provided in the treatment tank; Including, The treatment tank comprises: an inner tank having an opening at an upper portion and configured to store the phosphoric acid treatment solution; an outer tank disposed outside the inner tank and configured to receive the phosphoric acid treatment solution flowing out from the opening; having The inner tank is provided with a gas discharge part that discharges gas into the inner tank, The step of additionally introducing a precipitation inhibitor includes supplying the precipitation inhibitor to the inner tank.

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