Substrate processing device, substrate processing method and storage medium

Abstract

The present invention provides a substrate processing device, a substrate processing method and a storage medium. The substrate processing device of an embodiment includes a substrate processing tank and a control unit. The substrate processing tank performs etching treatment by immersing the substrate in a phosphoric acid treatment solution. The control unit controls a temperature regulating unit for regulating the temperature of the phosphoric acid treatment solution as the etching treatment progresses to reduce the temperature of the phosphoric acid treatment solution. The present invention can suppress the precipitation of silicon oxide.

Description

Technical Field

[0001] Embodiments of the present invention relate to a substrate processing apparatus, a substrate processing method, and a storage medium. Background Art

[0002] A technology has long been known in which, in a substrate processing device, a silicon nitride film (SiN) and a silicon oxide film (SiO2) formed on a substrate are selectively etched by immersing the substrate in a phosphoric acid treatment solution (see Patent Document 1).

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2013-232593 Summary of the invention

[0006] Technical problem to be solved by the invention

[0007] However, when a silicon nitride film in a substrate having a plurality of silicon nitride films and silicon oxide films stacked thereon is selectively etched, as the etching proceeds, the path for the components of the etched silicon nitride film to be discharged out of the substrate becomes longer. Therefore, the silicon concentration in the phosphoric acid treatment solution in the gap formed between the silicon oxide films becomes higher, and there is a possibility that silicon oxide will precipitate on the silicon oxide film.

[0008] An object of one aspect of the embodiment is to provide a substrate processing apparatus, a substrate processing method, and a storage medium that suppress the precipitation of silicon oxide.

[0009] Technical means for solving technical problems

[0010] A substrate processing device according to one embodiment includes a substrate processing tank and a control unit. The substrate processing tank performs etching treatment by immersing the substrate in a phosphoric acid treatment solution. The control unit controls a temperature regulating unit for regulating the temperature of the phosphoric acid treatment solution to reduce the temperature of the phosphoric acid treatment solution as the etching treatment progresses.

[0011] Effects of the Invention

[0012] According to one aspect of the embodiment, precipitation of silicon oxide can be suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic plan view of a substrate processing apparatus.

[0014] Figure 2 It is a schematic block diagram showing the structure of a processing tank for etching according to an embodiment.

[0015] Figure 3A It is a schematic diagram showing a cross section of a substrate before etching.

[0016] Figure 3B It is a schematic diagram showing the state of the substrate after the etching process.

[0017] Figure 3C It is a schematic diagram showing the state of the substrate after further etching treatment.

[0018] Figure 3D This is a schematic diagram showing the state of the substrate after the etching process is completed.

[0019] Figure 4 This is a flow chart for explaining temperature control of etching process.

[0020] Figure 5A This is a graph showing the silicon concentration in the substrate when the temperature of the etching solution is high.

[0021] Figure 5B This is a graph showing the silicon concentration in the substrate when the temperature of the etching solution is low.

[0022] Figure 6 This is a flow chart for explaining the phosphoric acid concentration control in the etching process.

[0023] Figure 7 is a flow chart illustrating silicon concentration control in an etching process.

[0024] Figure 8 This is a graph showing the relationship between the temperature of the etching solution and the silicon saturation level.

[0025] Fig. 9 This is a graph summarizing the temperature, phosphoric acid concentration, and silicon concentration of the etching solution relative to the processing time.

[0026] Fig.10 This is a summary diagram showing the relationship between the temperature, phosphoric acid concentration, and silicon concentration of the etching solution and the processing time in the substrate processing apparatus of the modified example.

[0027] Description of Reference Numerals

[0028] 1. Substrate processing device

[0029] 6 Batch Processing Department

[0030] 8 Substrate

[0031] 23 Etching treatment device

[0032] 27 Etching treatment tank

[0033] 40 Phosphoric acid aqueous solution supply unit

[0034] 41 Phosphoric acid aqueous solution discharge part

[0035] 41A discharge line

[0036] 41B Fifth flow regulator (temperature regulator, phosphoric acid concentration regulator, silicon concentration regulator)

[0037] 42C Second flow regulator (temperature regulator, phosphoric acid concentration regulator, silicon concentration regulator)

[0038] 44 Inner tank (substrate processing tank)

[0039] 45 outer groove

[0040] 46 Temperature regulating tank

[0041] 52 first heater (temperature adjustment unit)

[0042] 62 Second heater (temperature adjustment unit)

[0043] 70 Supply lines

[0044] 72 Fourth flow regulator (temperature regulator, phosphoric acid concentration regulator, silicon concentration regulator)

[0045] 80 Temperature Sensor

[0046] 81 Phosphoric acid concentration sensor

[0047] 82 Silicon Concentration Sensor

[0048] 100 Control Department. DETAILED DESCRIPTION

[0049] Hereinafter, embodiments of the substrate processing apparatus, substrate processing method, and storage medium disclosed in the present invention will be described in detail with reference to the accompanying drawings. In addition, the present invention is not limited to the embodiments shown below.

[0050] Figure 1 As shown, the substrate processing apparatus 1 of the embodiment includes a carrier carrying in and out section 2 , a batch forming section 3 , a batch placing section 4 , a batch transport section 5 , a batch processing section 6 , and a control section 100 . Figure 1 1 is a schematic plan view of the substrate processing apparatus 1. Here, the description is made with the direction perpendicular to the horizontal direction being the up-down direction.

[0051] The carrier carrying-in and carrying-out section 2 carries in and carries out a carrier 9 storing a plurality (eg, 25) of substrates (silicon wafers) 8 arranged vertically in a horizontal posture.

[0052] The carrier carrying in and out section 2 is provided with: a carrier table 10 for carrying a plurality of carriers 9 ; a carrier transport mechanism 11 for transporting the carriers 9 ; carrier stacks 12 and 13 for temporarily storing the carriers 9 ; and a carrier placement table 14 for placing the carriers 9 .

[0053] The carrier carrying-in / out unit 2 carries the carrier 9 carried into the carrier table 10 from the outside to the carrier stack 12 or the carrier placement table 14 using the carrier transport mechanism 11. That is, the carrier carrying-in / out unit 2 carries the carrier 9 containing the plurality of substrates 8 before being processed by the batch processing unit 6 to the carrier stack 12 or the carrier placement table 14.

[0054] The carrier stack 12 temporarily stores the carriers 9 for storing a plurality of substrates 8 before being processed by the batch processing unit 6 .

[0055] The plurality of substrates 8 are transported to the carrier stage 14 and taken out from the carrier 9 that accommodates the plurality of substrates 8 before being processed by the processing unit 6 , by a substrate transport mechanism 15 described later.

[0056] In addition, a plurality of substrates 8 processed by the batch processing unit 6 are carried from the substrate transport mechanism 15 to the carrier 9 placed on the carrier mounting table 14 and containing no substrates 8 .

[0057] The carrier loading and unloading unit 2 transports the carrier 9 placed on the carrier mounting table 14 and containing a plurality of substrates 8 processed by the batch processing unit 6 to the carrier stack 13 or the mounting table 10 using the carrier transport mechanism 11 .

[0058] The carrier stack 13 temporarily stores a plurality of substrates 8 processed by the batch processing unit 6. The carrier 9 transported to the mounting table 10 is transported to the outside.

[0059] The batch forming unit 3 is provided with a substrate conveying mechanism 15 for conveying a plurality of (e.g., 25) substrates 8. In the batch forming unit 3, the substrate conveying mechanism 15 conveys a plurality of (e.g., 25) substrates 8 twice to form a batch consisting of a plurality of (e.g., 50) substrates 8.

[0060] The batch forming section 3 uses the substrate conveying mechanism 15 to convey the plurality of substrates 8 from the carrier 9 mounted on the carrier mounting table 14 to the substrate batch mounting section 4 , and mounts the plurality of substrates 8 on the batch mounting section 4 to form a batch.

[0061] The plurality of substrates 8 forming a batch are processed simultaneously by the batch processing unit 6. When forming a batch, the batch can be formed in a manner that the surfaces of the plurality of substrates 8 with patterns are opposite to each other, or the batch can be formed in a manner that the surfaces of the plurality of substrates 8 with patterns are all facing one direction.

[0062] Furthermore, the batch forming section 3 uses the substrate transport mechanism 15 to transport a plurality of substrates 8 from the batch processed by the batch processing section 6 and placed on the batch placing section 4 to the carrier 9 .

[0063] The substrate transport mechanism 15 is a substrate support for supporting the plurality of substrates 8, and includes two types: a pre-processing substrate support (not shown) for supporting the plurality of substrates 8 before processing and a post-processing substrate support (not shown) for supporting the plurality of substrates 8 after processing. Thus, it is possible to prevent particles attached to the plurality of substrates 8 before processing from being transferred to the plurality of substrates 8 after processing.

[0064] The substrate transport mechanism 15 can change the posture of the plurality of substrates 8 from a horizontal posture to a vertical posture and from a vertical posture to a horizontal posture during the transport of the plurality of substrates 8 .

[0065] The batch placement section 4 temporarily places (stands by) the batch transported between the batch forming section 3 and the batch processing section 6 by the batch transport section 5 on the batch placement table 16 .

[0066] The batch placement section 4 is provided with an inlet-side batch placement table 17 and an outlet-side batch placement table 18 .

[0067] The batches before processing are placed on the inbound batch placement table 17 , and the batches after processing are placed on the outbound batch placement table 18 .

[0068] On the carry-in-side batch placement stage 17 and the carry-out-side batch placement stage 18 , a plurality of substrates 8 for one batch are placed in a vertical orientation in a row.

[0069] The batch transport unit 5 transports the batch between the batch placement unit 4 and the batch processing unit 6 or within the batch processing unit 6 .

[0070] The batch transport unit 5 is provided with a batch transport mechanism 19 for transporting a batch. The batch transport mechanism 19 includes a guide rail 20 disposed along the batch placement unit 4 and the batch processing unit 6, and a moving body 21 that moves along the guide rail 20 while holding the batch.

[0071] The movable body 21 is provided with a substrate holding body 22 for holding a batch consisting of a plurality of substrates 8 arranged in a front-to-back manner in a vertical posture.

[0072] The batch transport section 5 receives the batch placed on the carry-in-side batch placement table 17 via the substrate holding body 22 of the batch transport mechanism 19 , and delivers the received batch to the batch processing section 6 .

[0073] Then, the batch transport section 5 receives the batch processed by the batch processing section 6 via the substrate holding body 22 of the batch transport mechanism 19 , and delivers the received batch to the outgoing batch placement table 18 .

[0074] Furthermore, the batch transport unit 5 uses a batch transport mechanism 19 to transport batches inside the batch processing unit 6 .

[0075] The batch processing section 6 performs processing such as etching, cleaning, and drying on a batch consisting of a plurality of substrates 8 arranged in a vertical posture in a front-to-back manner.

[0076] The batch processing section 6 is provided with two etching processing devices 23 for etching the batch, a cleaning processing device 24 for cleaning the batch, a substrate holder cleaning processing device 25 for cleaning the substrate holder 22, and a drying processing device 26 for drying the batch. In addition, the number of etching processing devices 23 is not limited to two, and may be one, or may be three or more.

[0077] The etching processing device 23 includes a processing tank 27 for etching, a processing tank 28 for rinsing, and substrate lifting mechanisms 29 and 30.

[0078] The etching tank 27 stores an etching solution (hereinafter referred to as “etching solution”). The rinsing tank 28 stores a rinsing solution (pure water, etc.). The etching tank 27 will be described in detail later.

[0079] The substrate lifting mechanisms 29 and 30 hold a plurality of substrates 8 forming a batch in a vertical orientation arranged front to back.

[0080] The etching device 23 receives a batch from the substrate holding body 22 of the batch conveying mechanism 19 via the substrate lifting mechanism 29, and lowers the received batch via the substrate lifting mechanism 29, thereby immersing the batch in the etching solution in the processing tank 27 to perform etching. The etching process is performed for about 1 to 2 hours, for example.

[0081] Thereafter, the etching processing apparatus 23 raises the substrate lifting mechanism 29 to take out the batch from the processing tank 27 , and transfers the batch from the substrate lifting mechanism 29 to the substrate holding body 22 of the batch transport mechanism 19 .

[0082] Then, the substrate lifting mechanism 30 receives the batch from the substrate holding body 22 of the batch transport mechanism 19, and the received batch is lowered by the substrate lifting mechanism 30, so that the batch is immersed in the processing liquid for rinsing in the processing tank 28 to perform rinsing treatment.

[0083] Thereafter, the etching processing apparatus 23 raises the substrate lifting mechanism 30 to take out the batch from the processing tank 28 , and transfers the batch from the substrate lifting mechanism 30 to the substrate holding body 22 of the batch transport mechanism 19 .

[0084] The cleaning processing device 24 includes a processing tank 31 for cleaning, a processing tank 32 for rinsing, and substrate lifting mechanisms 33 and 34 .

[0085] The cleaning tank 31 stores a cleaning solution (SC-1, etc.). The rinse tank 32 stores a rinse solution (pure water, etc.). The substrate lifting mechanisms 33 and 34 hold a plurality of substrates 8 for one batch in a vertical orientation.

[0086] The drying processing device 26 includes a processing tank 35 and a substrate lifting mechanism 36 that is lifted and lowered relative to the processing tank 35 .

[0087] A drying process gas (IPA (isopropyl alcohol) or the like) is supplied to the process tank 35. The substrate lifting mechanism 36 holds a plurality of substrates 8 for one batch in a vertical orientation in a front-to-back arrangement.

[0088] The drying processing device 26 receives a batch from the substrate holding body 22 of the batch conveying mechanism 19 via the substrate lifting mechanism 36, lowers the received batch via the substrate lifting mechanism 36 to be transported into the processing tank 35, and performs drying processing on the batch using the drying processing gas supplied to the processing tank 35. Then, the drying processing device 26 raises the batch via the substrate lifting mechanism 36, and transfers the dried batch from the substrate lifting mechanism 36 to the substrate holding body 22 of the batch conveying mechanism 19.

[0089] The substrate holder cleaning processing device 25 has a processing tank 37, which can supply a processing liquid and a dry gas for cleaning to the processing tank 37. After supplying the processing liquid for cleaning to the substrate holder 22 of the batch transport mechanism 19, the substrate holder 22 is cleaned by supplying a dry gas.

[0090] Next, refer to Figure 2 , describing the processing tank 27 for etching. Figure 2 It is a schematic block diagram showing the structure of the etching processing tank 27 according to the embodiment.

[0091] In the etching treatment tank 27, an etching solution is used to selectively etch only the silicon nitride film (SiN) 8A formed on the substrate 8 (see Figure 3A ) and silicon oxide film (SiO2) 8B (refer to Figure 3A ) in the silicon nitride film 8A.

[0092] In the etching process of the nitride film, a solution in which a silicon (Si) compound is added to a phosphoric acid (H3PO4) aqueous solution to adjust the silicon concentration is generally used as an etching solution. As a method for adjusting the silicon concentration, there are a method of immersing a simulated substrate in an existing phosphoric acid aqueous solution to dissolve the silicon (seasoning), or a method of dissolving a silicon-containing compound such as colloidal silica in a phosphoric acid aqueous solution. In addition, there is also a method of adding an aqueous solution of a silicon-containing compound to a phosphoric acid aqueous solution to adjust the silicon concentration.

[0093] The etching treatment tank 27 includes a phosphoric acid aqueous solution supply unit 40 , a phosphoric acid aqueous solution discharge unit 41 , a pure water supply unit 42 , a silicon supply unit 43 , an inner tank 44 , an outer tank 45 , and a temperature adjustment tank 46 .

[0094] The phosphoric acid aqueous solution supply unit 40 includes a phosphoric acid aqueous solution supply source 40A, a phosphoric acid aqueous solution supply line 40B, and a first flow regulator 40C.

[0095] The phosphoric acid aqueous solution supply source 40A is a tank storing phosphoric acid aqueous solution. The phosphoric acid aqueous solution supply line 40B connects the phosphoric acid aqueous solution supply source 40A and the temperature adjustment tank 46 to supply the phosphoric acid aqueous solution from the phosphoric acid aqueous solution supply source 40A to the temperature adjustment tank 46 .

[0096] The first flow regulator 40C is provided in the phosphoric acid aqueous solution supply line 40B, and regulates the supply amount of the phosphoric acid aqueous solution to the temperature adjustment tank 46. The first flow regulator 40C is composed of an on-off valve, a flow control valve, a flow meter, and the like.

[0097] The pure water supply unit 42 includes a pure water supply source 42A, a pure water supply line 42B, and a second flow rate regulator 42C. The pure water supply unit 42 supplies pure water (DIW) to the outer tank 45 in order to replenish water evaporated by heating the etching liquid.

[0098] The pure water supply line 42B connects the pure water supply source 42A and the outer tank 45 , and supplies pure water at a predetermined temperature from the pure water supply source 42A to the outer tank 45 .

[0099] The second flow regulator 42C is provided in the pure water supply line 42B, and regulates the supply amount of pure water supplied to the outer tank 45. The second flow regulator 42C is composed of an on-off valve, a flow control valve, a flow meter, etc. By regulating the supply amount of pure water by the second flow regulator 42C, the temperature, phosphoric acid concentration, and silicon concentration of the etching solution are regulated. The second flow regulator 42C constitutes a temperature regulating unit, a phosphoric acid concentration regulating unit, and a silicon concentration regulating unit.

[0100] The silicon supply unit 43 includes a silicon supply source 43A, a silicon supply line 43B, and a third flow regulator 43C.

[0101] The silicon supply source 43A is a tank storing an aqueous solution of a silicon-containing compound. The silicon supply line 43B connects the silicon supply source 43A and the temperature adjustment tank 46 to supply the aqueous solution of a silicon-containing compound from the silicon supply source 43A to the temperature adjustment tank 46.

[0102] The third flow regulator 43C is provided in the silicon supply line 43B, and regulates the supply amount of the silicon-containing compound aqueous solution supplied to the temperature adjustment tank 46. The third flow regulator 43C is composed of an on-off valve, a flow control valve, a flow meter, and the like.

[0103] When the etching process is completed and a preliminary solution is generated to be supplied when the etching solution is replaced, the silicon-containing compound aqueous solution is supplied. In addition, the silicon supply unit 43 may supply the silicon-containing compound aqueous solution to the outer tank 45. In this case, when the silicon concentration in the etching solution decreases during the etching process, the silicon supply unit 43 can supply the silicon-containing compound aqueous solution to the outer tank 45.

[0104] The upper part of the inner tank 44 is open, and the etching liquid is supplied to the vicinity of the upper part. In the inner tank 44, a batch (a plurality of substrates 8) is immersed in the etching liquid by the substrate lifting mechanism 29, and the substrates 8 are etched. The inner tank 44 constitutes a substrate processing tank.

[0105] The outer tank 45 is provided around the upper part of the inner tank 44 and has an open upper part. The etching liquid overflowing from the inner tank 44 flows into the outer tank 45. In addition, the preliminary liquid is supplied from the temperature regulating tank 46 to the outer tank 45. In addition, the pure water supply unit 42 supplies pure water to the outer tank 45.

[0106] The outer tank 45 is provided with a temperature sensor 80 for detecting the temperature of the etching solution and a phosphoric acid concentration sensor 81 for detecting the phosphoric acid concentration of the etching solution. The signals generated by the sensors 80 and 81 are input to the control unit 100 (see Figure 1 ).

[0107] The outer tank 45 and the inner tank 44 are connected by a first circulation line 50. One end of the first circulation line 50 is connected to the outer tank 45, and the other end of the first circulation line 50 is connected to a processing liquid supply nozzle 49 provided in the inner tank 44.

[0108] The first circulation line 50 is provided with a first pump 51, a first heater 52, and a filter 53 in order from the outer tank 45 side. The etching liquid in the outer tank 45 is heated by the first heater 52 and flows into the inner tank 44 from the processing liquid supply nozzle 49. The first heater 52 adjusts the temperature of the etching liquid supplied to the inner tank 44. In addition, a silicon concentration sensor 82 for detecting the silicon concentration of the etching liquid is provided in the first circulation line 50. The signal generated by the silicon concentration sensor 82 is input to the control unit 100. The first heater 52 constitutes a temperature adjustment unit.

[0109] By driving the first pump 51, the etching liquid is sent from the outer tank 45 to the inner tank 44 via the first circulation line 50. In addition, the etching liquid overflows from the inner tank 44 and flows out again to the outer tank 45. In this way, a circulation path 55 of the etching liquid is formed. That is, the circulation path 55 is formed by the outer tank 45, the first circulation line 50, and the inner tank 44. In the circulation path 55, the outer tank 45 is set at a position on the upstream side of the first heater 52 with respect to the inner tank 44.

[0110] The phosphoric acid aqueous solution supplied by the phosphoric acid aqueous solution supply unit 40 is stored as a preliminary solution in the temperature control tank 46. In addition, the phosphoric acid aqueous solution supplied by the phosphoric acid aqueous solution supply unit 40 and the silicon-containing compound aqueous solution supplied by the silicon supply unit 43 are mixed and generated and stored in the temperature control tank 46.

[0111] For example, in the temperature control tank 46, when all the etching solutions in the inner tank 44 and the outer tank 45 are replaced, a preliminary solution composed of a mixture of an aqueous phosphoric acid solution and an aqueous silicon-containing compound solution is generated and stored. In addition, in the temperature control tank 46, when a part of the etching solution is replaced during the etching process, an aqueous phosphoric acid solution is stored as a preliminary solution.

[0112] The temperature regulating tank 46 is connected to a second circulation line 60 that circulates the reserve liquid in the temperature regulating tank 46. In addition, the temperature regulating tank 46 is connected to one end of a supply line 70. The other end of the supply line 70 is connected to the outer tank 45.

[0113] The second circulation line 60 is provided with a second pump 61 and a second heater 62. The second pump 61 is driven with the second heater 62 turned on to heat and circulate the preliminary liquid in the temperature adjustment tank 46. The second heater 62 adjusts the temperature of the preliminary liquid. The second heater 62 constitutes a temperature adjustment unit.

[0114] The supply line 70 is provided with a third pump 71 and a fourth flow regulator 72. The fourth flow regulator 72 regulates the supply amount of the preliminary liquid supplied to the outer tank 45. The fourth flow regulator 72 is composed of an on-off valve, a flow control valve, a flow meter, etc. By regulating the supply amount of the preliminary liquid using the fourth flow regulator 72, the temperature, phosphoric acid concentration, and silicon concentration of the etching solution can be adjusted. The fourth flow regulator 72 constitutes a temperature regulating unit, a phosphoric acid concentration regulating unit, and a silicon concentration regulating unit.

[0115] When all or part of the etching liquid is replaced, the preliminary liquid stored in the temperature adjustment tank 46 is supplied to the outer tank 45 via the supply line 70 .

[0116] When all or part of the etching liquid used in the etching process is replaced, the phosphoric acid aqueous solution discharge part 41 discharges the etching liquid. The phosphoric acid aqueous solution discharge part 41 includes a discharge line 41A, a fifth flow regulator 41B, and a cooling tank 41C.

[0117] The discharge line 41A is connected to the first circulation line 50. The fifth flow regulator 41B is provided in the discharge line 41A, and is used to adjust the discharge amount of the discharged etching liquid. The fifth flow regulator 41B is composed of an on-off valve, a flow control valve, a flow meter, etc. The cooling tank 41C temporarily stores the etching liquid that has flowed through the discharge line 41A and cools it. By adjusting the discharge amount (for example, supplying pure water) using the fifth flow regulator 41B, the temperature, phosphoric acid concentration, and silicon concentration of the etching liquid can be adjusted. The fifth flow regulator 41B constitutes a temperature adjustment unit, a phosphoric acid concentration adjustment unit, and a silicon concentration adjustment unit.

[0118] In addition, the actuator (not shown) operates according to the signal from the control unit 100, thereby changing the opening and closing of the opening and closing valves constituting the first flow regulator 40C to the fifth flow regulator 41B and the opening degree of the flow control valve. In other words, the opening and closing valves and the flow control valve constituting the first flow regulator 40C to the fifth flow regulator 41B are controlled by the control unit 100.

[0119] return Figure 1 The control unit 100 controls the operation of each unit (carrier carrying in and out unit 2, batch forming unit 3, batch loading unit 4, batch conveying unit 5, batch processing unit 6) of the substrate processing apparatus 1. The control unit 100 controls the operation of each unit of the substrate processing apparatus 1 based on a signal from a switch or the like.

[0120] The control unit 100 is constituted by, for example, a computer, and has a computer-readable storage medium 38. The storage medium 38 stores a program for controlling various processes executed in the substrate liquid processing apparatus 1.

[0121] The control unit 100 controls the operation of the substrate liquid processing apparatus 1 by reading and executing the program stored in the storage medium 38. The program is stored in the computer-readable storage medium 38 and can be installed in the storage medium 38 of the control unit 100 from other storage media.

[0122] Examples of the computer-readable storage medium 38 include a hard disk (HD), a floppy disk (FD), a compact disk (CD), a magneto-optical disk (MO), and a memory card.

[0123] Here, refer to Figure 3A to Figure 3D The etching process will be described. Figure 3A It is a schematic diagram showing a cross section of the substrate 8 before etching. Figure 3B It is a schematic diagram showing the state of the substrate 8 after the etching process. Figure 3C It is a schematic diagram showing the state of the substrate 8 after a single etching process. Figure 3D It is a schematic diagram showing the state of the substrate 8 after the etching process is completed.

[0124] like Figure 3A As shown, before etching, a plurality of silicon nitride films 8A and silicon oxide films 8B are alternately stacked on a substrate 8. In addition, etching liquid is impregnated into the substrate 8, and a plurality of grooves 8C are formed in the substrate 8 for etching the stacked silicon nitride films 8A.

[0125] The substrate 8 is immersed in the inner tank 44, and when the etching process is started, as shown in FIG. Figure 3B As shown, first, the silicon nitride film 8A near the groove 8C is etched. That is, in the etching process, the silicon nitride film 8A is etched sequentially starting from the silicon nitride film 8A near the groove 8C.

[0126] The components of silicon nitride film 8A dissolved into the etching solution by etching are discharged into groove 8C from gap 8D formed by etching of silicon nitride film 8A, and discharged from groove 8C to the outside of substrate 8. Etching is performed by replacing the etching solution in groove 8C and gap 8D with new etching solution.

[0127] Therefore, as the etching process progresses, e.g. Figure 3C As shown in FIG. 1 , the distance from the etched portion to the groove 8C becomes longer. That is, the distance for discharging the components of the silicon nitride film 8A dissolved into the etching solution to the outside of the substrate 8 becomes longer.

[0128] Therefore, when the etching rate of the silicon nitride film 8A is high, the silicon concentration contained in the etching solution in the groove 8C and the gap 8D becomes high. In particular, the silicon concentration of the etching solution becomes high in the gap 8D formed at the inner side of the groove 8C, that is, at a longer distance from the surface of the substrate 8.

[0129] Therefore, while the etching solution including the components of the silicon nitride film 8A dissolved by etching is discharged to the outside of the substrate 8, there is a possibility that silicon oxide is precipitated on the silicon oxide film.

[0130] Furthermore, when further etching is performed, as Figure 3D As shown, the gaps 8D on both sides are connected.

[0131] In the substrate processing apparatus 1 of the present embodiment, etching processing is performed by the method described below.

[0132] First, refer to Figure 4 The temperature control of the etching process will be described. Figure 4 This is a flow chart for explaining temperature control of etching process.

[0133] When the etching process starts, the temperature of the etching liquid reaches a preset initial temperature. The initial temperature is the temperature at which the etching liquid reaches a boiling state.

[0134] When the etching process starts, the control unit 100 detects the temperature of the etching solution using the temperature sensor 80 ( S10 ).

[0135] The control unit 100 sets the set temperature of the etching solution to a predetermined temperature according to the processing time of the etching process (S11). Specifically, the control unit 100 sets the predetermined temperature to a lower temperature as the processing time becomes longer. That is, the control unit 100 sets the predetermined temperature to a lower temperature as the etching process progresses.

[0136] During the etching process, the higher the temperature of the etching solution becomes, the higher the etching rate of the silicon nitride film 8A becomes. When the etching process is performed in a state where the etching rate of the silicon nitride film 8A is high, silicon oxide may be precipitated while the etching solution containing the components of the silicon nitride film 8A dissolved by etching is discharged to the outside of the substrate 8.

[0137] Therefore, the control unit 100 sets the predetermined temperature to a lower temperature as the etching process progresses.

[0138] The control unit 100 outputs a temperature control signal so that the detected temperature of the etching liquid becomes a predetermined temperature (S12). That is, the control unit 100 outputs a temperature control signal so that the temperature of the etching liquid decreases as the etching process progresses.

[0139] For example, the control unit 100 outputs a signal to reduce the amount of heating of the etching liquid by the first heater 52, and controls the temperature of the etching liquid by the first heater 52. In addition, the control unit 100 replaces a part of the etching liquid to control the temperature of the etching liquid. The control unit 100 discharges a part of the etching liquid and outputs a signal to supply the preliminary liquid from the temperature adjustment tank 46. In addition, the control unit 100 is used to output a signal to adjust the temperature of the preliminary liquid by the second heater 62 when a part of the etching liquid is discharged.

[0140] Here, refer to Figure 5A , Figure 5B , which illustrates the silicon concentration when the temperature of the etching solution is lowered. Figure 5A This is a graph showing the silicon concentration in the substrate 8 when the temperature of the etching solution is high. Figure 5B is a graph showing the silicon concentration in the substrate 8 when the temperature of the etching solution is low. Figure 5A and Figure 5B In the above examples, the conditions except the temperature of the etching solution are the same. Figure 5A and Figure 5B In the graph, the darker the color, the higher the silicon concentration.

[0141] In the substrate 8 undergoing etching, the silicon concentration increases as the groove 8C of the substrate 8 is deeper, that is, the distance from the surface of the substrate 8 is longer. Also, the silicon concentration in the gap 8D formed between the silicon oxide films 8B increases as the distance from the groove 8C is longer.

[0142] When the temperature of the etching solution is low, the silicon concentration becomes lower than when the temperature of the etching solution is high, the distance from the surface of the substrate 8 becomes longer, and the silicon concentration in the portion with a long distance from the groove 8C can be reduced.

[0143] As described above, by lowering the temperature of the etching solution as the etching process progresses, the etching rate of the silicon nitride film 8A can be reduced, and the silicon concentration in the etching solution in the gap 8D formed between the silicon oxide films 8B can be suppressed from increasing. Therefore, the precipitation of silicon oxide can be suppressed.

[0144] Next, refer to Figure 6 , illustrating the phosphoric acid concentration control for etching treatment. Figure 6 This is a flow chart for explaining the phosphoric acid concentration control in the etching process.

[0145] When the etching process is started, the phosphoric acid concentration of the etching solution becomes a preset initial phosphoric acid concentration.

[0146] When the etching process starts, the control unit 100 detects the phosphoric acid concentration of the etching solution using the phosphoric acid concentration sensor 81 ( S20 ).

[0147] The control unit 100 sets the phosphoric acid concentration of the etching solution to a predetermined phosphoric acid concentration (S21). Specifically, the control unit 100 sets the phosphoric acid concentration of the etching solution to the predetermined phosphoric acid concentration so that the etching solution is maintained in a boiling state. For example, when the temperature of the etching solution is lowered by the temperature control described above, the control unit 100 sets the predetermined phosphoric acid concentration to a lower concentration as the etching process progresses in order to maintain the etching solution in a boiling state.

[0148] It is also known that the selectivity of etching the silicon nitride film 8A to the silicon oxide film 8B increases by reducing the phosphoric acid concentration of the etching solution.

[0149] Therefore, the control unit 100 can increase the selectivity by setting the predetermined phosphoric acid concentration to a lower concentration as the etching process progresses.

[0150] The control unit 100 outputs a phosphoric acid concentration control signal so that the detected phosphoric acid concentration becomes the set predetermined phosphoric acid concentration (S22). For example, when the phosphoric acid concentration is reduced, the control unit 100 outputs a signal to discharge a portion of the etching solution. In addition, the control unit 100 outputs a signal to supply pure water and a preliminary solution.

[0151] As described above, the phosphoric acid concentration of the etching solution is reduced as the etching process progresses. This maintains the boiling state of the etching solution, causes the etching solution to flow, and can suppress uneven etching of the substrate 8. In addition, the selectivity can be increased.

[0152] Furthermore, it is not necessary to reduce the phosphoric acid concentration, and the phosphoric acid concentration may not be essential in the entire treatment step. Alternatively, the phosphoric acid concentration may be kept constant after the phosphoric acid concentration is reduced to a certain concentration.

[0153] Next, refer to Figure 7 The silicon concentration control in the etching process will be described. Figure 7 is a flow chart illustrating silicon concentration control in an etching process.

[0154] When the etching process starts, the silicon concentration of the etching solution becomes a preset initial silicon concentration. Generally, when the silicon concentration is high, the selectivity becomes large, so the initial silicon concentration is set to a concentration close to the saturation concentration.

[0155] When the etching process starts, the control unit 100 detects the silicon concentration of the etching solution using the silicon concentration sensor 82 ( S30 ).

[0156] The control unit 100 sets the silicon concentration of the etching solution to a predetermined silicon concentration (S31). Specifically, the control unit 100 sets the predetermined silicon concentration according to the temperature of the etching solution. Figure 8 As shown in FIG. 1 , the saturated amount of silicon in the etching solution decreases as the temperature of the etching solution decreases. That is, when the temperature of the etching solution decreases, silicon oxide is easily precipitated. Figure 8 This is a graph showing the relationship between the temperature of the etching solution and the silicon saturation level.

[0157] Therefore, the control unit 100 sets the predetermined silicon concentration to a concentration not higher than the saturation concentration corresponding to the silicon saturation amount as the temperature of the etching solution decreases by the above-mentioned temperature control, that is, as the etching process progresses.

[0158] The control unit 100 outputs a silicon concentration control signal so that the detected silicon concentration becomes the set silicon concentration (S32). During the etching process, as the etching process progresses, the silicon nitride film 8A is etched, and the silicon nitride film 8A is dissolved into the etching solution, so the silicon concentration of the etching solution becomes higher as a whole. Therefore, for example, in the case of reducing the silicon concentration, the control unit 100 outputs a signal to discharge a part of the etching solution. In addition, the control unit 100 outputs a signal to supply pure water and a preliminary solution.

[0159] As described above, by reducing the silicon concentration of the etching solution as the etching process progresses, the precipitation of silicon oxide can be suppressed.

[0160] In addition, when the silicon concentration of the etching solution is not at the saturation concentration, the silicon concentration may not be controlled until the silicon concentration reaches the saturation concentration. In this case, for example, when the detected silicon concentration reaches the saturation concentration corresponding to the temperature of the etching solution, the prescribed silicon concentration is set to a concentration below the saturation concentration. That is, it is not necessary to set the initial silicon concentration to a concentration close to the saturation concentration, and the initial silicon concentration may be zero, for example. By setting the initial silicon concentration to be lower, the time for the silicon concentration in the groove 8C to reach the saturation concentration can be extended, and the precipitation of silicon oxide can be suppressed. In addition, by increasing the silicon concentration until the silicon concentration reaches the saturation concentration, the selectivity can be increased.

[0161] As described above, by performing temperature control, phosphoric acid concentration control, and silicon concentration control, the temperature, phosphoric acid concentration, and silicon concentration of the etching solution are controlled. Fig. 9 The processing time is shown to be correspondingly lower. Fig. 9 This is a graph summarizing the temperature, phosphoric acid concentration, and silicon concentration of the etching solution relative to the processing time.

[0162] In the etching process, Fig. 9 As shown, at time t1 when the temperature control, phosphoric acid concentration control, and silicon concentration control are completed and etching is completed, the temperature of the etching solution becomes the processing end temperature, the phosphoric acid concentration becomes the processing end phosphoric acid concentration, and the silicon concentration becomes the processing end silicon concentration. Furthermore, in the etching process, after time t1, the substrate 8 is kept in the state of time t1 for a predetermined period to perform over etching. Thus, it is possible to suppress the occurrence of etching omissions of the silicon nitride film 8A on the substrate 8.

[0163] In addition, the temperature, phosphoric acid concentration and silicon concentration of the etching solution may be discontinuous but may change in steps. In addition, the time when the temperature of the etching solution reaches the processing end temperature, the time when the phosphoric acid concentration reaches the processing end phosphoric acid concentration, and the time when the silicon concentration reaches the processing end silicon concentration may be different.

[0164] The substrate processing apparatus 1 lowers the temperature of the etching solution as the etching process progresses. This can reduce the etching rate of the silicon nitride film 8A, and can suppress, for example, the situation where the silicon concentration in the etching solution locally increases in the gap 8D formed between the silicon oxide films 8B. Therefore, the precipitation of silicon oxide can be suppressed.

[0165] The substrate processing apparatus 1 reduces the phosphoric acid concentration of the etching solution as the etching process progresses, thereby maintaining the boiling state of the etching solution, suppressing uneven etching of the substrate 8, and increasing the selectivity.

[0166] The substrate processing apparatus 1 reduces the silicon concentration of the etching solution as the etching process proceeds, thereby being able to suppress the precipitation of silicon oxide.

[0167] In the substrate processing apparatus 1 of the modified example, the supply line 70 is connected to the inner tank 44 , so that the preliminary liquid can be supplied from the temperature adjustment tank 46 to the inner tank 44 .

[0168] In addition, in the substrate processing device 1 of the modified example, a SiO2 precipitation inhibitor may be supplied to suppress the precipitation of silicon oxide. As the SiO2 precipitation inhibitor, it is sufficient to stabilize the silicon ions dissolved in the phosphoric acid aqueous solution in a dissolved state and contain a component that suppresses the precipitation of silicon oxide. For example, a fluorine-containing hexafluorosilicic acid (H2SiF6) aqueous solution may be used. In addition, in order to stabilize the fluorosilicic acid in the aqueous solution, an additive such as ammonia may be contained.

[0169] For example, SiO2 precipitation inhibitors include ammonium hexafluorosilicate (NH4)2SiF6, sodium hexafluorosilicate (Na2SiF6), and the like.

[0170] In addition, the substrate processing apparatus 1 of the modified example may also reduce the temperature, phosphoric acid concentration, and silicon concentration of the etching solution according to the elapsed time of the etching process without using the temperature sensor 80, the phosphoric acid concentration sensor 81, and the silicon concentration sensor 82. For example, in the substrate processing apparatus 1 of the modified example, when the elapsed time of the etching process reaches a preset time, the temperature, phosphoric acid concentration, and silicon concentration of the etching solution are reduced. In addition, the time (elapsed time) to reduce the temperature, phosphoric acid concentration, and silicon concentration of the etching solution may be set respectively according to the temperature, phosphoric acid concentration, and silicon concentration of the etching solution.

[0171] In addition, if Fig.10 As shown, the substrate processing apparatus 1 of the modified example increases the temperature of the etching solution and increases the phosphoric acid concentration and the silicon concentration after the time t1 when the etching is finished, that is, during the over-etching. This is because the dissolution of the silicon nitride film 8A almost disappears during the over-etching. As a result, the time required for the over-etching can be shortened, and the etching processing time can be shortened. Fig.10 This is a graph summarizing the temperature, phosphoric acid concentration, and silicon concentration of the etching solution with respect to the processing time in the substrate processing apparatus 1 according to the modification.

[0172] Furthermore, the timing for increasing the temperature of the etching solution, the timing for increasing the phosphoric acid concentration, and the timing for increasing the silicon concentration may be different timings.

[0173] The above-mentioned substrate processing device 1 is a device for processing a plurality of substrates 8 simultaneously, but it may also be a single-wafer type device for cleaning the substrates 8 one by one.

[0174] Those skilled in the art can easily derive further effects and variations. Therefore, the broader aspects of the present invention are not limited to the specific details and representative embodiments shown and described above. Therefore, various changes can be made as long as they do not depart from the spirit or scope of the general concept of the invention defined by the scope of the attached claims and their equivalents.

Claims

1. A substrate processing device, characterized in that: include: A substrate processing tank for performing etching treatment by immersing a substrate having a silicon nitride film and a silicon oxide film formed thereon in a phosphoric acid treatment solution; and A control unit, when the etching process starts, the control unit makes the temperature of the phosphoric acid treatment solution an initial temperature, the initial temperature being the temperature at which the phosphoric acid treatment solution becomes a boiling state; as the etching process progresses, the control unit controls a temperature regulating unit for regulating the temperature of the phosphoric acid treatment solution to reduce the temperature of the phosphoric acid treatment solution so that the etching rate of the silicon nitride film becomes smaller; and controls a phosphoric acid concentration regulating unit for adjusting the phosphoric acid concentration in the phosphoric acid treatment solution to reduce the phosphoric acid concentration so that the phosphoric acid treatment solution is maintained in a boiling state and the selectivity of etching the silicon nitride film relative to the silicon oxide film becomes larger; at the end of the etching, the temperature of the phosphoric acid treatment solution is reduced to the process end temperature, and the phosphoric acid concentration of the phosphoric acid treatment solution is reduced to the process end phosphoric acid concentration; during the subsequent over-etching, the temperature regulating unit is controlled to increase the temperature of the phosphoric acid treatment solution, and the phosphoric acid concentration regulating unit is controlled to increase the phosphoric acid concentration.

2. The substrate processing device according to claim 1, characterized in that: The control unit controls a silicon concentration adjustment unit for adjusting a silicon concentration in the phosphoric acid treatment solution to reduce the silicon concentration as the etching process progresses.

3. The substrate processing device according to claim 2, characterized in that: The control unit controls the silicon concentration adjustment unit to increase the silicon concentration after reducing the silicon concentration of the phosphoric acid treatment solution to a treatment end silicon concentration.

4. A substrate processing method, characterized in that: include: a step of performing an etching treatment by immersing the substrate on which the silicon nitride film and the silicon oxide film are formed in a phosphoric acid treatment solution; and At the beginning of the etching process, the temperature of the phosphoric acid treatment solution is set to an initial temperature, which is a temperature at which the phosphoric acid treatment solution becomes a boiling state. As the etching process progresses, the temperature of the phosphoric acid treatment solution is lowered so that the etching rate of the silicon nitride film decreases, and the phosphoric acid concentration is lowered so that the phosphoric acid treatment solution is maintained in a boiling state and the selectivity of etching the silicon nitride film relative to the silicon oxide film becomes larger. At the end of the etching, the temperature of the phosphoric acid treatment solution is lowered to the treatment end temperature, and the phosphoric acid concentration of the phosphoric acid treatment solution is lowered to the treatment end phosphoric acid concentration. During the subsequent over-etching, the temperature of the phosphoric acid treatment solution is increased, and the phosphoric acid concentration is increased.

5. A storage medium, characterized in that: A program for causing a computer to execute the substrate processing method according to claim 4 is stored.

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