JP2006237228A - Substrate processing equipment and its method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a converted concentration as an absolute value and to reduce the manhour required for adjustment by setting references. <P>SOLUTION: Processing liquid is stored in a processing tank 1, a reference voltage is stored in a storage section 26 under that state, processing liquid stored in the processing tank 1 is heated to processing temperature, a processing voltage is detected under that state, and then actual specific gravity of the processing liquid is determined based on them at a concentration calculating section 27. The concentration calculating section 27 expresses the actual specific gravity in terms of specific gravity to obtain a converted actual specific gravity and then determine a converted concentration based on the specific gravity-concentration characteristics. Since the actual specific gravity represents a ratio to the reference voltage of the equipment, the converted concentration expressed in terms of temperature also becomes an absolute value. When the converted concentration is obtained for each equipment, it can be utilized for comparing the equipments and an absolute value understandable for the user can be obtained. Furthermore, a common reference can be obtained for respective equipments and manhour required for adjusting each equipment can be reduced. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a substrate processing apparatus and a method for processing a substrate (hereinafter simply referred to as “substrate”) such as a semiconductor wafer, a glass substrate for a liquid crystal display device, and a glass substrate for a photomask with a processing liquid.

  Conventionally, it is necessary to use a phosphoric acid concentration meter in order to check the concentration when a processing solution containing phosphoric acid is heated to a high temperature (for example, 160 ° C.) and the substrate is processed with the processing solution. The problem is that it is expensive, and in order to measure with a densitometer, it is necessary to cool the processing liquid to the measurement temperature (for example, 25 ° C.) determined by the specification, and real-time measurement cannot be performed. is there.

As an apparatus that solves the above-described problem, there is an apparatus that includes a nitrogen gas supply unit, a regulator, a supply pipe, and a pressure detection unit for concentration measurement (see, for example, Patent Document 1). This apparatus supplies nitrogen gas at a constant flow rate from the nitrogen gas supply unit with the detection end of the supply pipe arranged at a predetermined depth in the treatment tank, and detects the pressure at this time by the pressure detection unit. Output as a corresponding output signal (voltage). The pressure detected in this way is a pressure at a predetermined depth in the treatment tank, and there is a correlation between this pressure and the specific gravity of the treatment liquid. And the process of calculating | requiring the density | concentration of a process liquid based on the detected specific gravity, and controlling a density | concentration is performed.
Japanese Patent Laid-Open No. 11-219931 (paragraph numbers “0040” to “0050”, FIG. 2)

However, the conventional example having such a configuration has the following problems.
In the conventional apparatus, the detected pressure fluctuates even if the detection end position of the supply pipe fluctuates slightly. Therefore, the pressure changes each time the height of the supply pipe is adjusted, and there is a difference between the devices even if the devices have the same structure. do not have. Therefore, the pressure cannot be used for comparison with other devices having the same structure, and the detected pressure, that is, the meaning of the voltage is difficult to understand for the user. Furthermore, when adjusting the processing conditions of the apparatus, it is necessary to make an independent adjustment for each apparatus, resulting in a problem that man-hours increase.

  The present invention has been made in view of such circumstances, and by setting a reference, it is possible to obtain a converted concentration as an absolute value, and a substrate processing apparatus capable of reducing adjustment man-hours and its It aims to provide a method.

In order to achieve such an object, the present invention has the following configuration.
That is, the invention according to claim 1 is a substrate processing apparatus that performs processing on a substrate with a processing liquid obtained by mixing a chemical solution and a diluent, and heats the processing liquid that stores the processing liquid. A heating means, a supply pipe having a detection end at a predetermined depth in the processing tank, for supplying a gas at a constant flow rate, and a pressure detection means for detecting the pressure in the supply pipe and outputting a voltage corresponding to the pressure. And storage means for storing the voltage from the pressure detection means as a reference voltage in a state where the reference liquid at the reference temperature is stored in the processing tank, and the processing liquid stored in the processing tank by the heating means at the processing temperature. In this state, the voltage from the pressure detection means is used as a processing voltage, the actual specific gravity calculating means for obtaining the actual specific gravity of the processing liquid based on the processing voltage and the reference voltage of the storage means, and the actual specific gravity is used as the processing liquid. Specific gravity-concentration characteristics of Conversion means for obtaining a converted actual specific gravity by converting to a specific gravity at the measurement temperature at the time, and a calculation means for obtaining an converted concentration of the treatment liquid based on the converted actual specific gravity and the specific gravity-concentration characteristic. It is what.

  [Operation / Effect] According to the first aspect of the present invention, prior to the treatment, the reference liquid at the reference temperature is stored in the treatment tank, and the voltage output from the pressure detection means in this state is stored as the reference voltage. To remember. Next, the processing liquid stored in the processing tank is heated by the heating means, and the voltage in this state is used as the processing voltage, and the actual specific gravity calculating means obtains the actual specific gravity of the processing liquid based on the processing voltage and the reference voltage. Since the actual specific gravity represents a ratio to the reference voltage in this device, it has an absolute meaning and can be used for comparison between devices if the reference voltage is measured in each device. The conversion means converts the actual specific gravity into the specific gravity at the measurement temperature to obtain the converted actual specific gravity. The converted actual specific gravity is a converted value obtained by converting the actual specific gravity into the measurement temperature of the treatment liquid when the specific gravity-concentration characteristic is measured. The computing means obtains the converted concentration when it is assumed that the processing liquid has been cooled to the measurement temperature based on the converted actual specific gravity and the specific gravity-concentration characteristics. Accordingly, since the actual specific gravity represents the ratio of the device to the reference voltage, the converted concentration obtained by converting the temperature based on this is also an absolute value. As a result, if the converted concentration is obtained by each device, it can be used for comparison between devices and can be made absolute for the user to easily understand. In addition, since a common reference can be obtained for each device, the number of adjustment steps for each device can be reduced.

  Incidentally, the specific gravity-concentration characteristic of the processing liquid generally collects data at a certain measurement temperature, and does not necessarily have data on the processing temperature of the processing liquid. Therefore, it is necessary to convert the actual specific gravity of the treatment liquid at the treatment temperature into the specific gravity at the measurement temperature.

  The reference liquid is, for example, pure water or distilled water, and the reference temperature is, for example, 25 ° C. or 25-30 ° C. Examples of the treatment liquid include a solution obtained by diluting phosphoric acid with pure water, a solution obtained by diluting hydrofluoric acid with pure water, and the like.

  Further, in the present invention, with respect to the actual specific gravity obtained by the actual specific gravity calculating means, the actual specific gravity of the treatment liquid at the treatment temperature and the measurement obtained by measuring with a hydrometer in the state where the treatment liquid is at the measurement temperature. It is preferable to obtain the converted actual specific gravity at the processing temperature by multiplying a coefficient set in advance according to the ratio with the specific gravity (claims 2 and 5). The ratio between the actual specific gravity obtained by measuring the specific gravity of the treatment liquid at the treatment temperature and the measurement specific gravity obtained by the hydrometer at this time is almost constant, while the treatment liquid is contained in a sealed container and cooled to the measurement temperature. This has been found by various experiments by the inventors. Therefore, if the actual specific gravity is obtained, the converted actual specific gravity can be obtained by multiplying by a preset coefficient.

  Moreover, in this invention, it is preferable that the said processing temperature is the range of 140-170 degreeC (Claim 3). In this temperature range, the ratio of the specific gravity (actual specific gravity) of the treatment liquid at the treatment temperature and the specific gravity (measurement specific gravity) when the treatment liquid is brought to the measurement temperature is a substantially constant value. Conversion is possible with a coefficient.

  If it is outside the above temperature range, a coefficient within the range may be obtained in advance, and a coefficient corresponding to the temperature of the treatment liquid may be used.

  According to a fourth aspect of the present invention, in the substrate processing method for processing a substrate with a processing liquid obtained by mixing a chemical solution and a diluting solution, a reference liquid at a reference temperature is stored in a processing tank prior to the processing. The processing obtained from the pressure detection means with the reference voltage obtained from the pressure detection means according to the pressure at a predetermined depth in the treatment tank and the treatment liquid stored in the treatment tank at the treatment temperature. The process of obtaining the actual specific gravity of the treatment liquid based on the voltage, the process of obtaining the converted actual specific gravity by converting the actual specific gravity into the specific gravity at the measurement temperature when the specific gravity-concentration characteristic of the treatment liquid is measured, and the conversion And a process of obtaining a converted concentration of the processing liquid based on the actual specific gravity and the specific gravity-concentration characteristic, and adjusting the processing liquid based on the converted concentration.

  [Operation / Effect] According to the invention described in claim 4, prior to processing, the reference voltage output from the pressure detecting means in a state where the reference liquid at the reference temperature is stored in the processing tank, and the processing liquid is processed at the processing temperature. The actual specific gravity of the processing liquid is obtained based on the voltage output from the pressure detection means in the state heated to the processing voltage. Since the actual specific gravity represents the ratio of the device to the reference voltage, it has an absolute meaning and can be used for comparison between devices if the reference voltage is measured between devices. This actual specific gravity is converted into the specific gravity at the measurement temperature to obtain the converted actual specific gravity. Based on the converted actual specific gravity and the specific gravity-concentration characteristics, the converted concentration when the processing liquid is assumed to be cooled to the measurement temperature is obtained. The treatment liquid is adjusted based on the converted concentration. Accordingly, since the actual specific gravity represents the ratio of the device to the reference voltage, the converted concentration obtained by converting the temperature based on this is also an absolute value. As a result, if the converted concentration is obtained for each device, it can be used for comparison between devices and can be an absolute value that is easy for the user to understand. In addition, since a common reference can be obtained for each device, the number of adjustment steps for each device can be reduced.

  According to the substrate processing apparatus of the present invention, the actual specific gravity calculating means obtains the actual specific gravity of the processing liquid based on the processing voltage and the reference voltage, and the actual specific gravity is converted into the specific gravity at the measurement temperature to obtain the converted actual specific gravity. Ask. The converted actual specific gravity is a value obtained by converting the actual specific gravity to the measured temperature of the treatment liquid when the specific gravity-concentration characteristic is measured, and the calculation means is based on the converted actual specific gravity and the specific gravity-concentration characteristic. Calculate the equivalent concentration when the liquid is assumed to be cooled to the measurement temperature. Accordingly, since the actual specific gravity represents the ratio of the device to the reference voltage, the converted concentration obtained by converting the temperature based on this is also an absolute value. As a result, if the converted concentration is obtained by each device, it can be used for comparison between devices and can be an absolute value that is easy for the user to understand. In addition, since a common standard can be obtained for each device, the number of adjustment steps for each device can be reduced.

An embodiment of the present invention will be described below with reference to the drawings.
FIG. 1 is a block diagram showing a schematic configuration of a substrate processing apparatus according to an embodiment of the present invention. Here, a processing solution obtained by mixing phosphoric acid (H ₃ PO ₄ ) as a chemical solution and pure water as a diluting solution is heated, and a substrate (for example, a semiconductor wafer) is immersed in the processing solution for etching. The processing apparatus will be described as an example.

  The substrate processing apparatus includes a processing tank 1 for storing a processing liquid. Around the processing tank 1, a recovery tank 2 for recovering the processing liquid overflowing from the processing tank 1 is provided. The treatment liquid collected in the collection tank 2 is returned to the treatment tank 1 through the circulation system 3. The circulation system 3 is configured by interposing a pump 4 for feeding a liquid, an in-line heater 6 and a filter 7 in a pipe 4 that communicates and connects a recovery tank 2 and an ejection pipe 1 a provided at the bottom of the processing tank 1. Has been. The in-line heater 6 is for heating the processing liquid returned to the processing tank 1 in the circulation system 3. The filter 7 is provided to remove particles from the processing liquid returned to the processing tank 1. A tank heater 8 for heating the processing liquid in each tank is provided around the outer periphery of the processing tank 1 and the recovery tank 2. The in-line heater 6 and the tank heater 8 correspond to the heating means in the present invention.

  An openable / closable cover 9 is provided on the upper portion of the processing tank 1. The plurality of substrates W are held in an upright posture at equal intervals on a vertically movable holding arm 10. When the holding arm 10 is outside the tank, the cover 9 is closed. When the substrate W group is held by the holding arm 10 and put into the processing tank 1, the cover 9 is opened. The cover 9 is closed again while the substrate W group is put into the processing tank 1 and is subjected to the etching process.

  The collection tank 2 is provided with a phosphoric acid supply unit 11 for supplying phosphoric acid. The phosphoric acid supply unit 11 includes a nozzle 12 disposed in the upper part of the recovery tank 2, a pipe 13 that connects the nozzle 12 to a phosphoric acid supply source, and a flow rate adjustment valve 14 that is interposed in the pipe 13. . The processing tank 1 is provided with a pure water replenishment unit 15 for replenishing pure water. The pure water replenishing unit 15 includes a nozzle 16 disposed in the vicinity of the edge of the processing tank 1, a pipe 17 that connects the nozzle 16 to a pure water supply source, and a flow rate adjustment valve 18 that is interposed in the pipe 17. I have.

  A temperature sensor 19 for detecting the temperature of the processing liquid is provided in the processing tank 1. The detection signal of the temperature sensor 19 is given to the temperature control unit 20. The temperature control unit 20 performs PID (proportional / integral / differential) control of the in-line heater 6 based on this detection signal, and ON / OFF control of the tank heater 8.

  Further, the treatment tank 1 is provided with a concentration detection device 21 for detecting the concentration of the treatment liquid. This concentration detection device 21 pays attention to the fact that there is a correlation between the concentration of phosphoric acid in the treatment liquid and the specific gravity of the phosphoric acid solution, and substantially detects the specific gravity of the treatment liquid containing phosphoric acid to thereby remove phosphoric acid. The concentration of the processing liquid contained is detected. Further, since the specific gravity of the treatment liquid containing phosphoric acid has a correlation with the pressure at a predetermined depth in the treatment tank 1, the concentration detection device 21 has a detection end at a predetermined depth in the treatment tank 1. The concentration of the phosphoric acid solution is detected by detecting the pressure of the treatment liquid applied to the detection end. Hereinafter, a specific configuration of the concentration detection device 21 will be described.

  The concentration detection device 21 includes a supply pipe 22, a regulator 23, a pressure detection unit 24, a storage unit 26, a concentration calculation unit 27, a display unit 28, and a concentration control unit 29. The supply pipe 22 is formed of a fluororesin or the like that is resistant to the processing liquid, and a detection end that is a lower end portion thereof is provided at a predetermined depth in the processing tank 1. The regulator 23 supplies nitrogen gas from a nitrogen gas supply source to the supply pipe 22 at a constant flow rate. Then, in a steady state, the discharge pressure of nitrogen gas can be regarded as substantially equal to the liquid pressure at a predetermined depth from the liquid surface of the processing tank 1. The pressure detection unit 24 includes a pressure sensor that measures the nitrogen gas pressure in the supply pipe 22. For example, a voltage of 0 to 2.5 [V] is output from the pressure detection unit 24. This voltage can be regarded as a liquid pressure at a predetermined depth from the liquid surface of the treatment tank 1.

  The pressure detector 24 corresponds to the pressure detector in the present invention.

The concentration calculation unit 27 stores a voltage corresponding to the pressure from the pressure detection unit 24 in the storage unit 26 in advance as a reference voltage V _DIW described later, and based on the reference voltage V _DIW and the processing voltage V _{SOL during} processing. Obtain the actual specific gravity of the processing solution. Further, the actual specific gravity is multiplied by a “coefficient” to obtain a converted actual specific gravity. Then, referring to the calibration curve data representing the specific gravity-concentration characteristics stored in advance in the storage unit 26, the phosphoric acid concentration (converted concentration) of the processing liquid in the processing tank 1 is obtained based on the converted actual specific gravity. The display unit 28 sequentially displays the actual specific gravity, the converted actual specific gravity, the converted concentration, and the like under the control of the concentration calculating unit 27. Although the details will be described later, the converted actual specific gravity is a value obtained by converting the actual specific gravity to the measured temperature of the treatment liquid when the specific gravity-concentration characteristic is measured, and the converted concentration is collected by the specific gravity-concentration characteristic. It is the concentration conversion value of the processing temperature at the measured temperature when The specific gravity-concentration characteristic may be a mathematical expression representing the characteristic instead of the calibration curve data.

  The storage unit 26 corresponds to the storage unit in the present invention, and the concentration calculation unit 27 corresponds to the actual specific gravity calculation unit, the conversion unit, and the calculation unit in the present invention.

A specific concentration calculation method is described in detail in Japanese Patent Application Laid-Open No. 11-219931. The following is a brief description.
That is, the detection signal (voltage) from the pressure detection unit 24 and the fluid pressure have a predetermined functional relationship, and the fluid pressure is the distance (depth) from the fluid surface to the detection end of the supply pipe 22 and the processing liquid. It can also be expressed as a value obtained by adding atmospheric pressure to a value proportional to the product of the specific gravity of. Therefore, the liquid pressure at the detection end can be expressed by a function having the phosphoric acid concentration of the treatment liquid and the depth of the detection end as variables. For this reason, the concentration and depth have a certain relationship with the voltage output from the pressure detection unit 24. From this relationship, the phosphoric acid concentration of the treatment liquid can be obtained based on the voltage from the pressure detection unit 24 by obtaining the relationship between the concentration and the voltage in advance with respect to the predetermined depth.

  Concentration data (converted concentration, which will be described later) of the processing liquid obtained by the concentration detection device 21 is given from the concentration calculation unit 27 to the concentration control unit 29. The concentration control unit 29 operates the pure water flow rate adjustment valve 18 to adjust the replenishment amount of pure water so that the phosphoric acid detection concentration of the processing liquid is slightly higher than the boiling point concentration corresponding to the set temperature of the processing liquid. . Specifically, the concentration control unit 29 operates the flow rate adjustment valve 18 by PID (proportional / integral / derivative) control based on the detected phosphoric acid concentration of the processing liquid.

  The main controller 31 is provided to manage the entire substrate processing apparatus. Specifically, the main control unit 31 gives a command for the set temperature of the processing liquid to the temperature control unit 20, a command for the target concentration of the processing liquid to the concentration control unit 29, an operation command for the flow rate adjustment valve 14 of phosphoric acid, and the like. .

  The above-described “reference voltage” and “processing voltage” will be described with reference to FIGS. 2 is a diagram schematically showing measurement of the reference voltage, and FIG. 3 is a diagram schematically showing measurement of the processing voltage. 4 is a flowchart showing a procedure for measuring a reference voltage, and FIG. 5 is a flowchart showing a procedure for measuring at the time of processing. FIG. 6 is a diagram schematically showing a procedure for obtaining the converted concentration.

“Measurement of Reference Voltage”
Before actually processing the substrate W, the reference voltage is measured in advance as follows.
First, as shown in FIG. 2, a reference solution having a reference temperature is stored in the processing tank 1. The reference temperature is, for example, 25 ° C., and the reference liquid is, for example, pure water. Then, the pump 5 is controlled so that pure water circulates at the same flow rate as that at the time of processing described later (step S1). For example, distilled water may be employed as the reference liquid, and the reference temperature may be in the range of 25 to 30 ° C., for example.

Then, the concentration calculation unit 27 monitors that the voltage that is an output signal from the pressure detection unit 24 is stabilized (step S2), and the voltage at the time of stabilization is written and stored in the storage unit 26 as the reference voltage V _DIW ( Step S3).

  In addition, on the structure of the processing tank 1, if pure water is simply stored, pure water is discharged little by little, and the liquid level gradually decreases. Since the pressure at the detection end of the supply pipe 22 fluctuates when the liquid level fluctuates, it is preferable to circulate pure water through the circulation system 3 as described above. By doing so, the depth at which the detection end of the supply pipe 22 is positioned can be made constant while maintaining the liquid level constant, so that pressure detection can be performed under the same conditions for the reference liquid and the processing liquid. Therefore, it is possible to improve the accuracy of the actual specific gravity described later by aligning the detection conditions for both pressures.

"When processing"
First, as shown in FIG. 3, a treatment liquid having a treatment temperature is stored in the treatment tank 1. For example, the processing temperature is 160 ° C., and the processing liquid is a mixed liquid of phosphoric acid and pure water. Then, the pump 5 is controlled so that the treatment liquid circulates at the circulation flow rate during the treatment (step S10).

At this time, the voltage (process voltage V _SOL ) from the pressure detection unit 24 is measured (step S11), and an operation for dividing the process voltage V _SOL by the reference voltage V _DIW stored in the storage unit 26 is performed (step S12). ). This result (= V _SOL / V _DIW ) represents the actual specific gravity since the specific gravity of pure water is 1 [g / cm ³ ].

In addition, it can utilize as a reference _| standard in each apparatus and the processing tank 1 by calculating _| requiring the reference voltage _VDIW about the different processing tank 1 of a different apparatus or the same apparatus. That is, a reference voltage V _DIW = 0.845 [V] in the tank A, and was the reference voltage V _DIW = 0.830 [V] in the B tank. Furthermore, suppose that the specific gravity according to the density | concentration of the process liquid at the time of a process was 1.55 [g / cm < ³ >]. In such a case, in the tank A and the tank B, the voltage to be adjusted during processing is as follows.

Tank A 1.55 x 0.845 = 1.309 [V]
Tank B 1.55 × 0.830 = 1.286 [V]

  The actual specific gravity obtained as described above corresponds to the specific gravity when the processing liquid is at the processing temperature. In general, the specific gravity-concentration characteristic of the processing liquid has a predetermined measurement temperature (for example, 25 ° C.). Data is collected only under the conditions. Therefore, an accurate concentration cannot be obtained from the actual specific gravity of the processing temperature and the specific gravity-concentration characteristics.

The inventor measured the treatment voltage V _SOL at each temperature with the temperature of the treatment liquid being 150 ° C., 155 ° C., and 160 ° C. Then, each processing solution was put in a sealed container and cooled to a measurement temperature (for example, 25 ° C.), and the specific gravity (measurement specific gravity) at the measurement temperature was measured using a single specific gravity meter. Then, as shown in Table 1 below, it was found that there is a common ratio (k) of about 1.084 between the actual specific gravity (m1) and the measured specific gravity (m2) at each temperature. This ratio (k) is caused by thermal expansion. Therefore, the above ratio (k) is substantially established at 140 to 170 ° C. including the above temperature range.

  Therefore, in the above temperature range, the processing liquid at the processing temperature is made to have a specific gravity at the measurement temperature by multiplying the actual specific gravity (m1) obtained in step S12 as described above by the ratio k = 1.084. The converted actual specific gravity is calculated (step S13). When the converted actual specific gravity is obtained, the converted concentration is obtained from the specific gravity-concentration characteristics collected at the measurement temperature (25 ° C.) as shown in the graph of FIG. 6 (step S14). The density calculation unit 27 described above obtains the converted density by the above-described processes of steps S <b> 10 to S <b> 14 and outputs this to the display unit 28 and the density control unit 29.

  Next, operations during actual processing will be described with reference to FIG. FIG. 7 is a flowchart showing a procedure during processing.

Steps S20 and S21
First, the flow control valve 14 of phosphoric acid is opened, and phosphoric acid is supplied to the recovery tank 2. The phosphoric acid supplied to the recovery tank 2 is heated by the in-line heater 6 while being sent to the treatment tank 1 via the circulation system 3. The phosphoric acid introduced into the treatment tank 1 is also heated by the tank heater 8.

Steps S22, S23, S24
The temperature of phosphoric acid in the treatment tank 1 is detected by the temperature sensor 19 and given to the temperature control unit 20. The temperature control unit 20 performs temperature management within a range of ± 0.3 ° C. with respect to a set temperature of 160 ° C. Specifically, when the liquid temperature is less than 159.7 ° C., heating by the in-line heater 6 and the tank heater 8 is continued. When the liquid temperature exceeds 160.3 ° C., the heating by the in-line heater 6 and the tank heater 8 is stopped and the liquid temperature is lowered by natural cooling. When the liquid temperature falls within the range of 159.7 ° C. to 160.3 ° C., the process proceeds to the next step S25.

Step S25
The converted concentration of the processing liquid in the processing tank 1 is calculated by the concentration detection device 21 as in steps S10 to S14 described above.

Step S26
The converted concentration is sequentially detected by the concentration detecting device 21 as in step S25. The concentration control unit 29 replenishes the processing tank 1 with pure water by operating the flow rate adjusting valve 18 by PID control so that the detected converted concentration becomes a preset target concentration. This target concentration is preferably set to be slightly higher than the boiling point concentration corresponding to the set temperature of the treatment liquid. When the detected concentration of the processing liquid in the processing tank 1 exceeds the target concentration range, the replenishment of pure water is continued. On the other hand, when the detected concentration falls below the target concentration range, the replenishment of pure water is stopped. When the replenishment of pure water is stopped, the pure water in the processing liquid evaporates due to the heating of the processing liquid, and the concentration of the processing liquid naturally increases.

Steps S27, S28, S29
When the processing liquid in the processing tank 1 enters the target concentration range and is stabilized, the substrate W group held by the holding arm 10 is put into the processing tank 1 and the etching process of the substrate W group starts. Until the predetermined processing time elapses, the temperature control and concentration control in steps S21 to S26 are repeated. When the processing time elapses, the substrate W group is pulled up from the processing tank 1 and transferred to the next processing tank.

As described above, prior to the treatment, the reference solution at the reference temperature is stored in the treatment tank 1, and the voltage output from the pressure detection unit 24 in this state is stored in the storage unit 26 as the reference voltage V _DIW . Next, heat the process liquid stored in a treating tank 1 to the processing temperature, the voltage in this state as a treatment voltage V _SOL, concentration calculator 27 based on the the treatment voltage V _SOL and the reference voltage V _DIW processing The actual specific gravity (m1) of the liquid is determined. The actual specific gravity (m1) represents a ratio with respect to the reference voltage V _DIW in this device, and therefore has an absolute meaning. If the reference voltage is measured in each device, it can be used for comparison between devices. The concentration calculation unit 27 converts the actual specific gravity (m1) into a specific gravity at the measurement temperature to obtain a converted actual specific gravity. The converted actual specific gravity is a converted value obtained by converting the actual specific gravity into the measurement temperature of the treatment liquid when the specific gravity-concentration characteristic is measured. Based on the converted actual specific gravity and specific gravity-concentration characteristics, the concentration calculation unit 27 obtains a converted concentration when it is assumed that the processing liquid has been cooled to the measurement temperature. Therefore, since the actual specific gravity (m1) represents the ratio to the reference voltage V _DIW of the apparatus, the converted concentration obtained by temperature conversion based on this is also an absolute value. As a result, if the converted concentration is obtained by each device, it can be used for comparison between devices and can be made absolute for the user to easily understand. In addition, since a common reference can be obtained for each device, the number of adjustment steps for each device can be reduced.

  The present invention is not limited to the above-described embodiment, and can be modified as follows.

  (1) In the above embodiment, the treatment liquid containing phosphoric acid has been described as an example, but the present invention can be applied to other treatment liquids such as a sulfuric acid solution.

  (2) In the above apparatus, the phosphoric acid detection concentration of the treatment liquid is controlled to be slightly higher than the boiling point concentration corresponding to the set temperature of the treatment liquid, but the present invention is limited to such control. is not.

It is a block diagram which shows schematic structure of the substrate processing apparatus which concerns on the Example of this invention. It is the figure which showed the measurement of the reference voltage typically. It is the figure which showed the measurement of the process voltage typically. It is a flowchart which shows the measurement procedure of a reference voltage. It is a flowchart which shows the measurement procedure of a process voltage. It is the figure which showed typically the procedure which calculates | requires conversion density | concentration. It is a flowchart which shows the procedure at the time of a process.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Processing tank 2 ... Collection tank 6 ... In-line heater (heating means)
8 ... Tank heater (heating means)
22 ... Supply pipe 24 ... Pressure detector (pressure detector)
26: Storage unit (storage means)
27 ... Concentration calculation unit (actual specific gravity calculation means, conversion means, calculation means)
29… Concentration control unit V _DIW … Reference voltage V _SOL … Processing voltage (m1)… Actual specific gravity (m2)… Measurement specific gravity (k)… Ratio

Claims (5)

In a substrate processing apparatus for processing a substrate with a processing liquid obtained by mixing a chemical and a diluent,
A treatment tank for storing the treatment liquid;
Heating means for heating the treatment liquid;
A supply pipe having a detection end at a predetermined depth in the processing tank and supplying a gas at a constant flow rate;
Pressure detecting means for detecting the pressure in the supply pipe and outputting a voltage corresponding to the pressure;
Storage means for storing a voltage from the pressure detection means as a reference voltage in a state in which a reference liquid at a reference temperature is stored in the processing tank;
In a state where the processing liquid stored in the processing tank by the heating means is at a processing temperature, the voltage from the pressure detecting means is used as a processing voltage, and the actual processing liquid is measured based on the processing voltage and the reference voltage of the storage means. An actual specific gravity calculating means for obtaining a specific gravity;
A conversion means for converting the actual specific gravity into a specific gravity at a measurement temperature when the specific gravity-concentration characteristic of the treatment liquid is measured to obtain a converted actual specific gravity;
A computing means for obtaining a converted concentration of the treatment liquid based on the converted actual specific gravity and specific gravity-concentration characteristics;
A substrate processing apparatus comprising: The substrate processing apparatus according to claim 1,
The conversion means measures the actual specific gravity obtained by the actual specific gravity calculation means by measuring the actual specific gravity of the treatment liquid at the treatment temperature and a hydrometer with the treatment liquid at the measurement temperature. A substrate processing apparatus characterized in that a converted actual specific gravity at a processing temperature is obtained by multiplying a coefficient set in advance according to a ratio to specific gravity. The substrate processing apparatus according to claim 1 or 2,
The substrate processing apparatus, wherein the processing temperature is in a range of 140 to 170 ° C. In a substrate processing method for processing a substrate with a processing liquid obtained by mixing a chemical and a diluent,
Prior to processing, the reference voltage at the reference temperature is stored in the processing tank, and the reference voltage obtained from the pressure detecting means according to the pressure at a predetermined depth in the processing tank and the processing liquid stored in the processing tank are processed. In the state of temperature, a process of obtaining the actual specific gravity of the processing liquid based on the processing voltage obtained from the pressure detection means,
The actual specific gravity is converted into the specific gravity at the measurement temperature when the specific gravity-concentration characteristic of the treatment liquid is measured, and the converted actual specific gravity is obtained.
A process of obtaining a converted concentration of the treatment liquid based on the converted actual specific gravity and specific gravity-concentration characteristics,
A substrate processing method comprising adjusting a processing solution based on the converted concentration. The substrate processing method according to claim 4,
The process of obtaining the converted actual specific gravity includes the actual specific gravity of the treatment liquid at the treatment temperature with respect to the actual specific gravity of the treatment liquid, and the measurement specific gravity obtained by measuring with a hydrometer in a state where the treatment liquid is at a reference temperature. A substrate processing method characterized in that a converted actual specific gravity at a processing temperature is obtained by multiplying a coefficient set in advance according to the ratio.

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