KR102469675B1 - Substrate liquid processing apparatus - Google Patents

Abstract

The boiling state of the treatment liquid in the treatment tank is more accurately controlled. The substrate liquid processing apparatus stores a processing liquid in a boiling state and immerses a substrate 8 in the stored processing liquid to perform processing of the substrate 34A, and a chemical component contained in the processing liquid. A concentration sensor 55B for detecting the concentration, and adjusting the concentration of the chemical component contained in the treatment solution to a set concentration by adding a chemical component to the treatment solution or adding a dilution solution based on the concentration detected by the concentration sensor. Concentration adjustment units 7, 40, 41, a head pressure sensor 86B for detecting the head pressure of the treatment liquid in the treatment tank, and a concentration for correcting the set concentration given to the concentration adjustment unit based on the detection values of the head pressure sensors A set value correction calculation unit 7 is provided.

Description

Substrate liquid processing device {SUBSTRATE LIQUID PROCESSING APPARATUS}

The present invention relates to a substrate liquid processing apparatus that performs liquid processing on a substrate such as a semiconductor wafer by immersing the substrate in a processing liquid stored in a processing tank.

BACKGROUND OF THE INVENTION In manufacturing semiconductor devices, in order to wet-etch a silicon nitride film formed on a surface of a substrate such as a semiconductor wafer, immersing a plurality of substrates in a heated aqueous solution of phosphoric acid stored in a treatment tank is performed. In order to efficiently and appropriately perform this wet etching treatment, it is necessary to maintain the phosphoric acid aqueous solution in an appropriate boiling state.

Patent Document 1 uses a configuration of a bubble level gauge, grasps the boiling state of an aqueous phosphoric acid solution based on the detected head pressure (back pressure), and controls the output of the heater or the injected amount of pure water based on the determined boiling state. that is listed. However, even in this control method, the boiling state cannot be controlled sufficiently and stably.

Japanese Patent No. 3,939,630

An object of the present invention is to provide a substrate liquid processing apparatus capable of more accurately controlling the boiling state of a processing liquid in a processing tank.

According to one embodiment of the present invention, a processing tank in which processing of the substrate is performed by storing a processing liquid in a boiling state and immersing a substrate in the stored processing liquid, and a concentration of a chemical component contained in the processing liquid and adjusting the concentration of the chemical component contained in the treatment solution to a set concentration by adding the chemical component to the treatment solution or adding a dilution solution based on the concentration detected by the concentration sensor. A head pressure sensor for detecting the head pressure of the treatment liquid in the treatment tank; and a concentration set value correction calculator for correcting the set concentration given to the concentration adjuster based on the detection value of the head pressure sensor. A substrate liquid processing apparatus is provided.

According to the above embodiment, it is possible to more accurately control the boiling state of the treatment liquid in the treatment tank in order to correct the set concentration given to the concentration adjustment unit according to the identified boiling level.

1 is a schematic plan view showing the entire configuration of a substrate liquid processing system.
2 is a system diagram showing the configuration of an etching device applied to a substrate liquid processing system.
Fig. 3 is a graph showing an example of changes over time in set values and actual values of the boiling level and set values (corrected set values) and actual values of the concentration when the etching apparatus was operated on a test basis.
4 is a schematic diagram showing a modified embodiment in which a temperature sensor is provided at an outlet of a heater provided in a circulation line.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described with reference to accompanying drawings. First, the entire substrate liquid processing system 1A in which the substrate liquid processing device (etching processing device) 1 according to one embodiment of the present invention is incorporated will be described.

As shown in FIG. 1, the substrate liquid processing system 1A includes a carrier carry-in/out unit 2, a lot forming unit 3, a lot arranging unit 4, a lot transfer unit 5, and a lot processing unit. (6) and a control unit (7).

The carrier carry-in/out unit 2 carries in and out of the carriers 9 that have accommodated a plurality of (for example, 25) substrates (silicon wafers) 8 arranged vertically in a horizontal position.

In the carrier carry-in/out unit 2, a carrier stage 10 for disposing a plurality of carriers 9, a carrier transport mechanism 11 for transporting the carriers 9, and a carrier 9 for temporarily storing Carrier stocks 12 and 13 and a carrier placing table 14 for placing the carrier 9 are provided. The carrier stock 12 temporarily stores the substrate 8 to be a product before being processed in the lot processing unit 6. The carrier stock 13 temporarily stores the substrate 8 to be a product after being processed in the lot processing unit 6.

The carrier carry-in/out unit 2 conveys the carrier 9 carried into the carrier stage 10 from the outside to the carrier stock 12 or the carrier mounting table 14 using the carrier conveyance mechanism 11 . Further, the carrier carry-in/out unit 2 conveys the carrier 9 placed on the carrier placing table 14 to the carrier stock 13 or the carrier stage 10 using the carrier conveyance mechanism 11 . The carrier 9 conveyed on the carrier stage 10 is carried out.

The lot forming unit 3 combines the substrates 8 accommodated in one or a plurality of carriers 9 to form a lot comprising a plurality of substrates 8 (for example, 50 sheets) to be processed simultaneously. In addition, when forming a lot, the lot may be formed so that the surfaces on which the pattern is formed on the surface of the substrate 8 face each other, and the surfaces on which the pattern is formed on the surface of the substrate 8 are all directed in one direction. You may form a lot so that

The lot formation section 3 is provided with a substrate conveying mechanism 15 for conveying a plurality of substrates 8 . Also, the substrate conveying mechanism 15 can change the posture of the substrate 8 from a horizontal attitude to a vertical attitude and from a vertical attitude to a horizontal attitude during conveyance of the substrate 8 .

The lot forming section 3 conveys the substrates 8 from the carriers 9 placed on the carrier placing table 14 to the lot placing section 4 using the substrate conveying mechanism 15, thereby forming a substrate lot. (8) is placed in the lot arranging unit (4). In addition, the lot formation unit 3 conveys the lot placed in the lot placing unit 4 to the carrier 9 placed on the carrier placing table 14 by means of the substrate conveying mechanism 15 . In addition, the substrate transport mechanism 15 is a substrate support unit for supporting a plurality of substrates 8, and supports the substrates 8 before processing (before they are transported by the lot transport unit 5). It has two types: a substrate support part and a processed substrate support part which supports the substrate 8 after processing (after being conveyed by the lot conveyance unit 5). This prevents particles or the like adhering to the substrate 8 or the like before processing from adhering to the substrate 8 or the like after processing.

The lot arranging unit 4 temporarily places (stands by) the lot transported between the lot forming unit 3 and the lot processing unit 6 by the lot conveying unit 5 on the lot placing table 16 .

In this lot placement unit 4, a carrying-in side lot placement table 17 for arranging the lot before processing (before being conveyed by the lot transfer unit 5) and after processing (by the lot transfer unit 5) There is provided a carry-out side lot placement table 18 for placing the lot (after being conveyed). On the carrying-in side lot placing table 17 and the carrying-out side lot placing table 18, a plurality of substrates 8 for one lot are arranged in a vertical position in a vertical position.

In the lot arranging unit 4, the lot formed in the lot forming unit 3 is placed on the loading-side lot arranging table 17, and the lot is carried into the lot processing unit 6 via the lot conveying unit 5 . Further, in the lot arranging unit 4, the lot carried out from the lot processing unit 6 via the lot conveying unit 5 is placed on the carrying-out side lot locating table 18, and the lot is placed in the lot forming unit 3 is returned

The lot transfer unit 5 transports lots between the lot arranging unit 4 and the lot processing unit 6 and between the inside of the lot processing unit 6 .

The lot conveying unit 5 is provided with a lot conveying mechanism 19 that conveys the lot.

The lot conveying mechanism 19 is a movable body that moves along the rails 20 while holding the rails 20 arranged along the lot arranging unit 4 and the lot processing unit 6 and a plurality of substrates 8 It consists of (21). The movable body 21 is provided with a substrate holder 22 capable of moving forward and backward, holding a plurality of substrates 8 arranged in a vertical position forward and backward.

The lot transfer unit 5 receives the lot placed on the load-side lot placing table 17 by the substrate holder 22 of the lot transfer mechanism 19 and delivers the lot to the lot processing unit 6 . In addition, the lot transfer unit 5 receives the lot processed by the lot processing unit 6 to the substrate holder 22 of the lot transfer mechanism 19, and transfers the lot to the lot placement table 18 on the discharge side. do. In addition, the lot transport unit 5 transports the lot inside the lot processing unit 6 using the lot transport mechanism 19 .

The lot processing unit 6 performs processing such as etching, cleaning, and drying as one lot of a plurality of substrates 8 arranged in a vertical position back and forth.

In this lot processing unit 6, a drying processing device 23 for drying the substrate 8, a substrate holding body cleaning processing device 24 for cleaning the substrate holding body 22, and the substrate 8 ), and two etching processing devices (substrate liquid processing device) 1 according to the present invention, which perform etching processing of the substrate 8, are arranged in a row.

The dry processing apparatus 23 has a treatment tank 27 and a substrate elevating mechanism 28 provided in the treatment tank 27 so as to be able to move up and down. A processing gas for drying (such as IPA (isopropyl alcohol)) is supplied to the processing tank 27 . In the substrate elevating mechanism 28, a plurality of substrates 8 for one lot are held in a vertical position in a vertical position. The dry processing apparatus 23 receives the lot from the substrate holding body 22 of the lot conveyance mechanism 19 by the substrate lifting mechanism 28, and lifts the lot with the substrate lifting mechanism 28, so that the treatment tank ( The substrate 8 is dried with the process gas for drying supplied to 27). Further, the drying processing device 23 transfers the lot from the substrate elevating mechanism 28 to the substrate holding body 22 of the lot conveying mechanism 19 .

The substrate holding body cleaning treatment device 24 has a treatment tank 29, and is capable of supplying a treatment liquid for cleaning and a drying gas to the treatment tank 29. After supplying the processing liquid for cleaning to 22, cleaning processing of the substrate holding body 22 is performed by supplying dry gas.

The cleaning treatment device 25 has a treatment tank 30 for cleaning and a treatment tank 31 for rinsing, and substrate elevating mechanisms 32 and 33 are provided in each treatment tank 30 and 31 to be able to move up and down. are doing A treatment liquid (SC-1 or the like) for washing is stored in the treatment tank 30 for washing. In the rinsing treatment tank 31, a rinsing treatment liquid (pure water, etc.) is stored.

An etching processing apparatus 1 has a processing tank 34 for etching and a processing tank 35 for rinsing, and substrate elevating mechanisms 36 and 37 are provided in each processing tank 34 and 35 so as to be able to move up and down. have. In the processing tank 34 for etching, a processing liquid for etching (aqueous phosphoric acid solution) is stored. In the rinsing treatment tank 35, a rinsing treatment liquid (pure water or the like) is stored.

The cleaning processing device 25 and the etching processing device 1 have the same configuration. Describing the etching processing apparatus (substrate liquid processing apparatus) 1, a plurality of substrates 8 for one lot are held in a vertical position in a vertical position in the substrate elevating mechanism 36. In the etching processing apparatus 1, the lot is received by the substrate lifting mechanism 36 from the substrate holding body 22 of the lot conveying mechanism 19, and the lot is moved by the substrate lifting mechanism 36, thereby processing the lot The substrate 8 is etched by being immersed in the processing liquid for etching in the bath 34 . After that, the etching processing apparatus 1 transfers the lot from the substrate elevating mechanism 36 to the substrate holding body 22 of the lot conveying mechanism 19 . In addition, the lot is received from the substrate holding body 22 of the lot conveyance mechanism 19 by the substrate lifting mechanism 37, and the lot is lifted by the substrate lifting mechanism 37, so that the lot is used for rinsing in the treatment tank 35. The substrate 8 is rinsed by being immersed in the treatment liquid. After that, the lot is transferred from the substrate elevating mechanism 37 to the substrate holding body 22 of the lot conveying mechanism 19 .

The control unit 7 includes each unit of the substrate liquid processing system 1A (carrier loading and unloading unit 2, lot forming unit 3, lot arranging unit 4, lot transfer unit 5, lot processing unit 6) , to control the operation of the etching processing apparatus 1.

This controller 7 is made of, for example, a computer, and has a computer-readable storage medium 38. The storage medium 38 stores programs for controlling various processes executed in the substrate liquid processing apparatus 1 . The controller 7 controls the operation of the substrate liquid processing device 1 by reading out and executing a program stored in the storage medium 38 . In addition, the program was stored in the storage medium 38 readable by a computer, and may be installed in the storage medium 38 of the control unit 7 from another storage medium.

Examples of the computer-readable storage medium 38 include a hard disk (HD), a flexible disk (FD), a compact disk (CD), a magnet optical disk (MO), and a memory card.

As described above, in the treatment tank 34 of the etching apparatus 1, the substrate 8 is subjected to liquid treatment (etching treatment) using an aqueous solution (phosphoric acid aqueous solution) of a chemical agent (phosphoric acid) having a predetermined concentration as a treatment liquid (etching liquid). )do.

Next, a configuration related to the etching processing device (substrate liquid processing device) 1, particularly the processing tank 34 for etching thereof, will be described with reference to FIG. 2 .

The etching processing apparatus 1 has the above-described processing tank 34 storing an aqueous phosphoric acid solution having a predetermined concentration as a processing liquid. The treatment tank 34 has an inner tank 34A with an open top and an outer tank 34B provided around the inner tank 34A and with an open top. The phosphoric acid aqueous solution overflowed from the inner tank 34A flows into the outer tank 34B. As shown in FIG. 2, the outer side jaw 34B surrounds the upper part of the inner side jaw 34A. The outer jaw 34B may be configured to accommodate the inner jaw 34A therein. In order to keep the phosphoric acid aqueous solution warm and to prevent splashing of the phosphoric acid aqueous solution, an openable and closable cover 70 covering at least the upper opening of the inner tank 34A is attached to the treatment tank 34.

One end of the circulation line 50 is connected to the bottom of the outer tank 34B. The other end of the circulation line 50 is connected to a processing liquid supply nozzle 49 installed in the inner tank 34A. In the circulation line 50, a pump 51, a heater 52, and a filter 53 are interposed sequentially from the upstream side.

By driving the pump 51, a circulating flow of the aqueous phosphoric acid solution is sent from the outer tank 34B through the circulation line 50 and the treatment liquid supply nozzle 49 into the inner tank 34A and flows out to the outer tank 34B again. is formed A gas nozzle (not shown) may be provided below the processing liquid supply nozzle 49 in the inner tank 34A, and bubbling of an inert gas such as nitrogen gas may be performed to stabilize the boiling state of the phosphoric acid aqueous solution. .

The liquid processing unit 39 is formed by the processing tank 34, the circulation line 50, and the devices 51, 52, 53, etc. in the circulation line 50. In addition, a circulation system is constituted by the treatment tank 34 and the circulation line 50 .

The etching processing apparatus 1 includes an aqueous phosphoric acid solution supply unit 40 that supplies an aqueous phosphoric acid solution to the liquid processing unit 39, a pure water supply unit 41 that supplies pure water to the liquid processing unit 39, and a liquid processing unit 39 It has a silicon supply unit 42 for supplying the silicon solution and a phosphoric acid solution discharge unit 43 for discharging the phosphoric acid aqueous solution from the liquid processing unit 39.

The phosphoric acid aqueous solution supply section 40 is located in the circulation system composed of the treatment tank 34 and the circulation line 50, that is, in the liquid treatment section 39, preferably at a concentration determined in the outer tank 34B as shown in the figure. of phosphoric acid solution is supplied. The aqueous phosphoric acid solution supply unit 40 includes an aqueous phosphoric acid solution supply source 40A composed of a tank for storing the aqueous phosphoric acid solution, an aqueous phosphoric acid solution supply line 40B connecting the aqueous phosphoric acid solution supply source 40A and the outer tank 34B, and an aqueous phosphoric acid solution. It has flow meter 40C, flow control valve 40D, and on-off valve 40E interposed sequentially from the upstream side to supply line 40B. The phosphoric acid aqueous solution supply unit 40 may supply the phosphoric acid aqueous solution to the outer tank 34B at a controlled flow rate through the flow meter 40C and the flow control valve 40D.

The pure water supply unit 41 supplies pure water to replenish evaporated water by heating the phosphoric acid aqueous solution. This pure water supply unit 41 includes a pure water supply source 41A that supplies pure water at a predetermined temperature, and this pure water supply source 41A is connected to the outer tank 34B via a flow controller 41B.

The flow regulator 41B can be constituted by an on-off valve, a flow control valve, a flow meter, or the like.

The silicon supply unit 42 has a silicon supply source 42A consisting of a tank for storing a silicon solution, for example, a liquid in which colloidal silicon is dispersed, and a flow regulator 42B. The flow regulator 42B can be constituted by an on-off valve, a flow control valve, a flow meter, or the like.

The phosphoric acid aqueous solution discharge unit 43 is provided to discharge the phosphoric acid aqueous solution in the circulation system composed of the treatment tank 34 and the circulation line 50, that is, in the liquid treatment unit 39. The phosphoric acid aqueous solution discharge unit 43 includes a discharge line 43A branched from the circulation line 50, a flow meter 43B sequentially provided from the upstream side of the discharge line 43A, a flow control valve 43C, and an on-off valve ( 43D) and a cooling tank 43E. The phosphoric acid aqueous solution discharge unit 43 may discharge the phosphoric acid aqueous solution at a controlled flow rate through the flow meter 43B and the flow control valve 43C.

The cooling tank 43E temporarily stores and cools the phosphoric acid aqueous solution that has flowed through the discharge line 43A. The phosphoric acid aqueous solution (refer to 43F) distilled from the cooling tank 43E may be disposed of in a factory wastewater system (not shown), and silicon contained in the phosphoric acid aqueous solution is removed by a regeneration device (not shown), and then , It may be reused by sending it to the phosphoric acid aqueous solution supply source 40A.

In the illustrated example, the discharge line 43A is connected to the circulation line 50 (the position of the filter drain in the drawing), but is not limited to this, and is not limited to this, and is another part in the circulation system, for example, the bottom part of the inner tank 34A. may be connected to

The discharge line 43A is provided with a silicon concentration meter 43G for measuring the silicon concentration in the phosphoric acid aqueous solution. In addition, a branch line 55A branched from the circulation line 50 and connected to the outer tank 34B (this branch line 55A can also be regarded as a part of the circulation system) measures the phosphoric acid concentration in the aqueous phosphoric acid solution. A phosphate concentration meter 55B is interposed. The outer tank 34B is provided with a level gauge 44 that detects the liquid level in the outer tank 34B.

In the inner tank 34A, a temperature sensor 60 for detecting the temperature of the aqueous phosphoric acid solution in the inner tank 34A is provided. The temperature sensor 60 may be formed in a place other than the inside of the inner tank 34A in the circulation system, for example, in the vicinity of the exit of the heater 52 of the circulation line 50.

A bubble level gauge 80 is attached to the inner tank 34A. The bubble level gauge 80 has a bubble tube 81 inserted into the phosphoric acid aqueous solution in the inner tank 34A, and a purge set 82 that supplies a purge gas (here, nitrogen gas) to the bubble tube 81. have. The bubble tube 81 is made of a material that is resistant to aqueous phosphoric acid, such as quartz.

The purge set 82 includes a pressure reducing valve, a throttle, a rotameter (all not shown), and the like. The purge set 82 performs control so that the purge gas supplied from the pressurized gas supply source 83 (for example, a dynamometer in a factory) is discharged at a constant flow rate from the tip of the bubble tube 81 inserted into the phosphoric acid aqueous solution. .

A detection line 85 is connected to the gas line 84 connecting the bubble tube 81 and the purge set 82, and this detection line 85 is divided into two branch detection lines, that is, a first branch detection line ( 85A) and the second branch detection line 85B. A first detector 86A and a second detector 86B are connected to the first and second branch detection lines 85A and 85B, respectively. The first and second detectors 86A and 86B measure the back pressure of the purge gas corresponding to the head pressure applied to the tip of the bubble tube 81 (the head pressure of the aqueous phosphoric acid solution in the inner tank 34A).

Since purge gas always flows through the gas line 84, it is not necessary to make the gas line 84, the detection line 85, the first branch detection line 85A and the second branch detection line 85B made of quartz. , can be made of a suitable corrosion-resistant resin, for example PTFE, PFA and the like.

The same pressure is applied to the first detector 86A and the second detector 86B. However, the detection ranges of the first detector 86A and the second detector 86B are different from each other.

The first detector 86A determines, from the hydrostatic pressure applied to the tip of the bubble pipe 81 when the liquid level of the aqueous phosphoric acid solution in the inner tank 34A is at the lowest level (the inner tank 34A is empty), the highest level (inner tank 34A). It is set so that the pressure in the range up to the head pressure applied to the tip of the bubble tube 81 can be detected when the phosphoric acid aqueous solution overflows from the tank 34A to the outer tank 34B). That is, the first detector 86A is provided to measure the liquid level of the phosphoric acid aqueous solution in the inner tank 34A.

The second detector 86B operates when the liquid level of the aqueous phosphoric acid solution in the inner tank 34A is at its highest level (that is, when overflow occurs from the inner tank 34A to the outer tank 34B), the phosphoric acid aqueous solution Range from the head pressure applied to the tip of the bubble pipe 81 when the boiling level is maximum to the head pressure applied to the tip of the bubble pipe 81 when the phosphoric acid aqueous solution is not boiling at all (detection target range) It is set to detect pressure.

When the boiling level (boiling state) changes, the amount of bubbles in the phosphoric acid aqueous solution changes, so the head pressure applied to the tip of the bubble tube 81 also changes. That is, when the boiling level increases, the head pressure decreases, and when the boiling level decreases, the head pressure increases. The boiling level can be quantified by observing the size and number of bubbles in the phosphoric acid aqueous solution and the surface state of the phosphoric acid aqueous solution ('flat', 'largely wavy', etc.) visually or by image analysis (e.g., to 5 stages of boiling level 1 to 5). By experimentation, the relationship between the head pressure (HP) and the boiling level (BL) can be grasped, and this relationship can be expressed in the form of a function (BL = f(HP)). Although there is some variation, the head pressure HP monotonically decreases as the boiling level BL increases.

The above function is stored in the storage medium 38 of the control unit 7, for example. This makes it possible to grasp the boiling level (boiling state) of the aqueous phosphoric acid solution in the inner tank 34A based on the head pressure detected by the second detector 86B. That is, the bubble level gauge 80 acts as a boiling level sensor.

Preferably, the second detector 86B is performed by an electric circuit that processes the sensor output of the second detector 86B (e.g., has a high-pass filter function and an amplification function) or by software. As a result, it becomes insensitive to the pressure outside the detection target range described above, and on the other hand, the pressure detection resolution within the detection target range is improved. As a result, the second detector 86B substantially loses the capability of detecting the level of the aqueous phosphoric acid solution in the inner tank 34A, but instead it becomes possible to detect the boiling state with higher precision.

Specifically, for example, when the aqueous phosphoric acid solution is not boiling at all, the output voltage of the pressure sensor (not shown) in the second detector 86B (changes corresponding to the change in head pressure) is 5 V, and the aqueous phosphoric acid solution is 5 V. Assume that the output voltage of the second detector 86B when the boiling level of is at the highest level is 4V. In this case, the detection circuit provided in the second detector 86B is configured so that a value obtained by subtracting 4 V from the output voltage of the pressure sensor (actually, an appropriate margin is set) multiplied by a predetermined gain (integer) is output.

In the substrate liquid processing apparatus 1, each unit (carrier carry-in/out unit 2, lot formation unit 3, lot arranging unit 4) is operated by the control unit 7 according to the process recipe stored in the storage medium 38. , The substrate 8 is processed by controlling the operations of the lot transfer unit 5, the lot processing unit 6, and the etching processing apparatus 1. Operating parts (opening/closing valves, flow control valves, pumps, heaters, etc.) of the etching processing apparatus 1 operate based on operation command signals transmitted from the control unit 7 . In addition, a signal indicating a detection result from the sensors 43G, 55B, 86A, 86B, etc. is sent to the control unit 7, and the control unit 7 uses the detection result to control the moving parts.

Next, the operation of the etching processing apparatus 1 will be described. First, the phosphoric acid aqueous solution supply unit 40 supplies the phosphoric acid aqueous solution to the outer tank 34B of the liquid processing unit 39 . When a predetermined time elapses after the start of supply of the phosphoric acid aqueous solution, the pump 51 of the circulation line 50 operates, and a circulation flow circulating in the aforementioned circulation system is formed.

In addition, the heater 52 of the circulation line 50 is operated to heat the aqueous phosphoric acid solution so that the aqueous phosphoric acid solution in the inner tank 34A reaches a predetermined temperature (for example, 160°C). At the latest, until the start of heating by the heater 52, the cover 70 is closed, and at least the upper opening of the inner tank 34A is covered with the cover 70. An aqueous phosphoric acid solution at 160°C becomes boiling.

An aqueous phosphoric acid solution present in the circulation system (including the inner tank 34A, the outer tank 34B and the circulation line 50) before one lot of substrates 8 is put into the phosphoric acid aqueous solution in the inner tank 34A Adjustment of the concentration of silicon in (which affects the etching selectivity of the silicon nitride film to the silicon oxide film) is performed. The silicon concentration can be adjusted by immersing the dummy substrate in an aqueous solution of phosphoric acid in the inner tank 34A, or by supplying a silicon solution from the silicon supply unit 42 to the outer tank 34B. In order to confirm that the silicon concentration in the phosphoric acid aqueous solution present in the circulation system is within a predetermined range, the phosphoric acid aqueous solution may be flowed through the discharge line 43A, and the silicon concentration may be measured with the silicon concentration meter 43G.

After the silicon concentration adjustment is completed, the lid 70 is opened, and a plurality of sheets, that is, one lot (also called a processing lot or batch) held in the substrate lifting mechanism 36 are discharged into the phosphoric acid aqueous solution in the inner tank 34A. A plurality, for example, 50 substrates 8 to be formed are immersed. Immediately thereafter, lid 70 is closed. A wet etching treatment (liquid treatment) is performed on the substrate 8 by immersing the substrate 8 in an aqueous phosphoric acid solution for a predetermined period of time.

While the substrate 8 is subjected to the wet etching process, the control unit 7 performs the following control.

[temperature control]

The control part 7 feedback-controls the output of the heater 52 so that the temperature of the phosphoric acid aqueous solution in 34 A of inner tanks detected by the temperature sensor 60 may become a set temperature. In this feedback control, the set temperature is the set value (SV), the temperature detected by the temperature sensor 60 is the measured value (PV), and the output of the heater 52 is the manipulated variable (MV). The temperature control unit is constituted by the control unit 7 and the heater 52 .

In the present embodiment, the set temperature of the phosphoric acid aqueous solution is maintained at a predetermined value in the process recipe without being changed according to a change in the phosphoric acid concentration or a change in the set concentration of the phosphoric acid concentration.

[Density control]

The control unit 7, if necessary, the pure water supply unit 41 so that the concentration of phosphoric acid (medicinal solution component) in the phosphoric acid aqueous solution (treatment liquid) in the circulation system, which is detected by the phosphoric acid concentration meter 55B (concentration sensor), becomes a set concentration. The supply amount of pure water (diluted liquid) from the above to the circulation system (outer tank 34B in the illustration) or the supply amount of phosphoric acid from the aqueous phosphoric acid solution supply unit 40 to the circulation system (outer tank 34B in the illustration) is feedback-controlled. In this feedback control, the set concentration is the set value (SV), the concentration detected by the phosphoric acid concentration meter 55B is the measured value (PV), and pure water from the pure water supply unit 41 to the circulation system (outer tank 34B in the illustrated example) ( The supply amount of dilution liquid) or the supply amount of phosphoric acid from the aqueous phosphoric acid solution supply unit 40 to the circulation system (outside tank 34B in the illustrated example) is the manipulated variable MV. The concentration adjustment unit is constituted by the control unit 7, the pure water supply unit 41, and the phosphoric acid aqueous solution supply unit 40. The set concentration is corrected by the boiling level control described later, although a value predetermined in the process recipe is used as an initial value.

In this embodiment, an aqueous phosphoric acid solution is used as the treatment liquid, and since the aqueous phosphoric acid solution is constantly boiling during the treatment of the substrate 8, the pure water content in the aqueous phosphoric acid solution always tends to decrease, and the phosphoric acid concentration always tends to increase. there is For this reason, only pure water is supplied into the circulatory system for concentration control.

[Boiling Level Control]

An initial value is set in the process recipe for the set concentration of phosphoric acid (chemical component) in the phosphoric acid aqueous solution (treatment liquid). At the start of control, the above-described concentration control is performed based on the initial value of the set concentration.

When the boiling level of the phosphoric acid aqueous solution in the inner tank 34A ascertained based on the head pressure detected by the second detector 86B deviates from the optimum level (e.g. boiling level 4), the control unit 7 , or if it seems to deviate, correct the set density. For example, when the boiling level is lower than the optimum level (for example, at least one of a state in which there are few bubbles in the phosphoric acid aqueous solution and a state in which there are small bubbles), or if it is likely to decrease, the set concentration is lowered. On the other hand, when the boiling level becomes higher than the optimum level (for example, a state in which the surface in the phosphoric acid aqueous solution is vigorously wavy) or is likely to become high, the set concentration is raised.

Since it is undesirable for the boiling level to deviate from the optimum level, at the time point when a change in head pressure predictable that the boiling level is likely to deviate from the optimum level is confirmed, control for correcting the set concentration so as to offset the change in head pressure is performed. It is desirable to do

For example, the median value of the output voltage of the sensor of the second detector 86B at the optimum boiling level (e.g. boiling level 4) is 4V, and the output voltage of the sensor of the second detector 86B is 4V±0.2 It is assumed that the optimum boiling level can be achieved at the time of V. At this time, for example, when the output voltage of the sensor of the second detector 86B increases from 4 V to 4.1 V, even if the optimum boiling level is maintained regardless of this change, the set concentration is changed by a small amount to output It is preferable to perform control for correcting the set concentration so as to prevent the voltage from approaching 4.2V any further. As an example, the initial value of the concentration setting value is about 88%, and the concentration setting value can be corrected with a 0.02 wt% pitch.

In order to prevent hunting of boiling levels, the control unit 7 preferably performs control with hysteresis (dead zone of control) in control. In addition, since the degree of influence of the concentration change width on the boiling level is different between the case where the boiling level is higher than the optimum level and the case where the boiling level is lower than the optimum level, it is preferable to correct the change width to each optimum value. The optimum value of the change width is determined by the chemical solution temperature, concentration, and boiling state used in the process recipe, and becomes a unique value set for each process recipe.

In this embodiment, only the set concentration is corrected according to the detected boiling level, and the set temperature is not corrected. The actual temperature of the phosphoric acid aqueous solution can be controlled with high precision by the above temperature control, for example within a range of about +/- 0.1 to 0.2°C of the set temperature.

Fig. 3 shows the boiling level set value (line A) and actual value (line B), and the concentration set value (corrected set value) (line C) when the etching apparatus was test-operated based on the control method described above. ) and an example of the change over time of the actual value (line D). The vertical axis on the left is the output voltage of the sensor of the second detector 86B, and the median value of the output voltage when the optimum boiling state is realized (this becomes the target value) is 4V. The vertical axis on the right is the phosphoric acid concentration in the phosphoric acid aqueous solution. The horizontal axis is the elapsed time (unit seconds). The target value (set concentration) of the phosphoric acid concentration is corrected with a pitch of 0.02 wt%. As shown in FIG. 3, it turns out that the stable boiling state was obtained between 500 second and 5500 second. In addition, although not shown in FIG. 3, the temperature of the phosphoric acid aqueous solution was maintained within a range of about 160°C ± 0.1 to 0.2°C from 500 seconds to 5500 seconds.

In addition to the above three feedback controls, the silicon concentration in the phosphoric acid aqueous solution may be controlled while the substrate 8 is subjected to the wet etching process. Since silicon is eluted from the substrates 8 during processing of one lot of the substrates 8, the concentration of silicon in the phosphoric acid aqueous solution present in the circulation system increases. During processing of one lot of substrates 8, in order to maintain or intentionally change the concentration of silicon in the aqueous phosphoric acid solution present in the circulation system, while discharging the aqueous phosphoric acid solution in the circulation system by the aqueous phosphoric acid discharge unit 43, , The phosphoric acid aqueous solution (new liquid) can be supplied by the phosphoric acid aqueous solution supply unit 40. You may supply the silicone solution from the silicone supply part 42. However, since it is difficult to feedback-control the silicon concentration in real time, it is preferable to control the silicon concentration by discharging and supplying the liquid at predetermined timings according to a process recipe.

When processing of the substrate 8 of one lot is completed as described above, the lid 70 is opened and the substrate 8 is carried out from the inner tank 34A. The unloaded substrate 8 is carried into the adjacent treatment tank 35, where a rinse treatment is performed.

Thereafter, the cover 70 is closed, and the temperature, phosphoric acid concentration, and silicon concentration of the aqueous phosphoric acid solution in the circulation system are adjusted, and then substrates 8 of another lot are processed in the same manner as above.

In the above embodiment, the control unit 7 is in charge of the control function of the concentration adjustment unit, the temperature adjustment unit, and the concentration set value correction calculation unit, but is not limited thereto, and among the concentration adjustment unit, the temperature adjustment unit, and the concentration setting value correction calculation unit. At least one control function may be realized by another computer.

According to the above embodiment, the boiling state (boiling level) of the phosphoric acid aqueous solution in the inner tank 34A is grasped based on the detected value of the second detector 86B, which is a hydrostatic pressure sensor, and the boiling state is maintained as a target state. Since the set concentration is corrected and the feedback control of the concentration is performed based on the corrected set concentration, it becomes easy to maintain the boiling level of the phosphoric acid aqueous solution in the inner tank 34A in an optimum state. In addition, by controlling the boiling level by concentration correction, it is possible to simultaneously manage concentrations that affect process performance.

Next, a method for evaluating the integrity of the boiling level sensor (bubble level gauge 80) will be described.

The temperature of the aqueous phosphoric acid solution, the concentration of the aqueous phosphoric acid solution, and the boiling level of the aqueous phosphoric acid solution have a close correlation. Therefore, when the detected value of the temperature sensor (for example, the temperature sensor 60) for detecting the temperature of the aqueous phosphoric acid solution is not stable at the set temperature (specifically, the temperature within the allowable range based on the set temperature), There may be something wrong with the boiling level sensor.

Further, if the concentration detected by the phosphoric acid concentration meter 55B is not stable at the set concentration (specifically, the concentration within the allowable range based on the set concentration), there is a possibility that there is an abnormality in the boiling level sensor.

In addition, when the supply amount of pure water from the pure water supply unit 41 is too large or too small, there is a possibility that there is an abnormality in the boiling level sensor. That is, if the treatment conditions, specifically, the temperature and boiling level of the phosphoric acid aqueous solution in the circulation system are appropriately controlled, the amount of water lost by evaporation by boiling per unit time is approximately constant, and therefore, the pure water supply unit 41 is discharged from the circulation system. The amount of pure water per unit time to be replenished will be within the set range (In addition, from the pure water supply unit 41, pure water may be continuously replenished to the circulation system or intermittently replenished to the circulation system). Therefore, when the supply amount of pure water per unit time from the pure water supply unit 41 deviates from the predetermined range, there is a possibility that there is an abnormality in the boiling level sensor.

The control unit 7 determines whether any one of the above-described abnormal detection value of the temperature sensor, abnormal detection value of the phosphate concentration meter 55B, or abnormal supply amount of pure water from the pure water supply unit 41 is recognized, or the abnormality is determined in advance. If this continues over a period of time, an alarm is generated to warn the operator of the substrate processing apparatus that there is a possibility that an abnormality may occur in the boiling level sensor (bubble level gauge 80), and the operator inspects the boiling level sensor. urge In addition, the control unit 7 can warn the operator that there is a suspicion that processing defects have occurred in the substrates 8 of the lot being processed at this time.

Further, as shown in FIG. 4 , a temperature sensor 60A is provided at the outlet of the heater 52, and based on the detected value of the temperature sensor 60A, the output of the heater 52 (to the heater 52) supply power) may be controlled. In this case, when the detected value of the temperature sensor 60A is not stable at the set temperature (specifically, the temperature within the allowable range based on the set temperature), it may be determined that there is a possibility that there is an abnormality in the boiling level sensor. .

In addition, the integrity of the boiling level sensor (bubble level gauge 80) is determined when the heater temperature is relatively stable, specifically, for example, when the substrate 8 is not being processed in the treatment tank 34. It is desirable to evaluate when

In the above embodiment, the treatment liquid was an aqueous phosphoric acid solution, but is not limited thereto. The processing liquid may be one whose concentration changes due to boiling, and the processing state of the substrate changes depending on the boiling state. Further, the substrate is not limited to a semiconductor wafer, and other types of substrates such as a glass substrate and a ceramic substrate may be used.

7: Density setting value correction calculation unit
7, 52: temperature control unit
7, 40, 41: concentration adjustment unit
34: treatment tank
34A: inner jaw
34B: outer jaw
50: circulation line
51: pump
52: heater
55B: concentration sensor (phosphate concentration meter)
60, 60A: Temperature sensor
86B: hydrostatic pressure sensor (second detector)

Claims (13)

A processing tank for storing a processing liquid in a boiling state and processing the substrate by immersing the substrate in the stored processing liquid;
a concentration sensor for detecting a concentration of a chemical component contained in the treatment liquid;
a concentration adjusting unit configured to adjust the concentration of the chemical component contained in the treatment solution to a set concentration by adding the chemical component to the treatment solution or adding a diluent based on the concentration detected by the concentration sensor;
a head pressure sensor for detecting a head pressure of the treatment liquid in the treatment tank;
a concentration set value correction calculator configured to correct a set concentration given to the concentration adjuster based on a detection value of the head pressure sensor;
The substrate liquid processing apparatus of claim 1 , wherein the head pressure sensor is set to detect a pressure within a narrower range than a detection range for measuring a level of the processing liquid in the processing tank. A processing tank for storing a processing liquid in a boiling state and processing the substrate by immersing the substrate in the stored processing liquid;
a concentration sensor for detecting a concentration of a chemical component contained in the treatment liquid;
a concentration adjusting unit configured to adjust the concentration of the chemical component contained in the treatment solution to a set concentration by adding the chemical component to the treatment solution or adding a diluent based on the concentration detected by the concentration sensor;
a head pressure sensor for detecting a head pressure of the treatment liquid in the treatment tank;
a concentration set value correction calculator for correcting the set concentration given to the concentration adjuster based on the detection value of the head pressure sensor;
and a control unit for generating an alarm warning of a possibility that an abnormality has occurred in the head pressure sensor when the concentration of the chemical component detected by the concentration sensor is not stable at the set concentration. A processing tank for storing a processing liquid in a boiling state and processing the substrate by immersing the substrate in the stored processing liquid;
a concentration sensor for detecting a concentration of a chemical component contained in the treatment liquid;
a concentration adjusting unit configured to adjust the concentration of the chemical component contained in the treatment solution to a set concentration by adding the chemical component to the treatment solution or adding a diluent based on the concentration detected by the concentration sensor;
a head pressure sensor for detecting a head pressure of the treatment liquid in the treatment tank;
a concentration set value correction calculation unit correcting the set concentration given to the concentration adjustment unit based on the detection value of the head pressure sensor;
When the amount of the diluent added to the treatment liquid from the concentration adjustment unit per unit time is not an amount corresponding to the treatment condition, a control unit for generating an alarm warning of the possibility that an abnormality is occurring in the head pressure sensor Substrate liquid processing device. According to any one of claims 1 to 3,
a temperature sensor for detecting the temperature of the treatment liquid;
and a temperature controller configured to adjust the temperature of the processing liquid to a set temperature by adjusting the output of the heater based on the temperature detected by the temperature sensor. According to claim 4,
a circulation line connected to the treatment tank;
a pump provided in the circulation line to form a flow of the treatment liquid coming out of the treatment tank, passing through the circulation line, and returning to the treatment tank;
The temperature sensor is provided at any place in the circulation system including the treatment tank and the circulation line,
The heater is provided in the circulation line substrate liquid processing apparatus. According to claim 5,
The concentration sensor is provided in the circulation line substrate liquid processing device. According to any one of claims 1 to 3,
The processing tank has an inner tank for storing the processing liquid and processing the substrate by immersing the substrate in the stored processing liquid, and an outer tank for accommodating the processing liquid overflowing from the inner tank. liquid handling device. According to claim 7,
The substrate liquid processing apparatus of claim 1 , wherein the concentration adjusting unit is configured to add the chemical component or a diluent to the processing liquid in the outer tank. A processing tank for storing a processing liquid in a boiling state and processing the substrate by immersing the substrate in the stored processing liquid;
a concentration sensor for detecting a concentration of a chemical component contained in the treatment liquid;
a concentration adjusting unit configured to adjust the concentration of the chemical component contained in the treatment solution to a set concentration by adding the chemical component to the treatment solution or adding a diluent based on the concentration detected by the concentration sensor;
a head pressure sensor for detecting a head pressure of the treatment liquid in the treatment tank;
a concentration set value correction calculation unit correcting the set concentration given to the concentration adjustment unit based on the detection value of the head pressure sensor;
a temperature sensor for detecting the temperature of the treatment liquid;
a temperature controller configured to adjust the temperature of the treatment liquid to a set temperature by adjusting the output of the heater based on the temperature detected by the temperature sensor;
Substrate liquid processing apparatus having a control unit generating an alarm to warn of the possibility that an abnormality has occurred in the head pressure sensor when the temperature of the processing liquid detected by the temperature sensor is not stable at the set temperature . According to claim 9,
a circulation line connected to the treatment tank;
a pump provided in the circulation line to form a flow of the treatment liquid coming out of the treatment tank, passing through the circulation line, and returning to the treatment tank;
The temperature sensor is provided at any place in the circulation system including the treatment tank and the circulation line,
The heater is provided in the circulation line substrate liquid processing apparatus. According to claim 10,
The temperature sensor is provided at an outlet of the heater of the circulation line. delete delete

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