JP2008311358A - Ultrasonic cleaning device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultrasonic cleaning device capable of monitoring the delivering condition of a cleaning liquid including the operating condition of an ultrasonic oscillator and a delivery pressure of the cleaning liquid while efficiently using ultrasound emitted from the ultrasonic oscillator for vibrating the cleaning liquid. <P>SOLUTION: The ultrasonic cleaning device is provided with a rotary table that loads a substrate to be cleaned and rotates together with the substrate, a cleaning nozzle that has the ultrasonic oscillator and performs cleaning processing on the substrate by delivering the cleaning liquid to which the ultrasound is applied, a humidity sensor that measures the humidity in the vicinity of the cleaning nozzle, and a monitoring section that monitors the humidity measured by a humidity sensor. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an ultrasonic cleaning device, and more particularly, to an ultrasonic cleaning device that discharges a cleaning liquid to which ultrasonic waves are applied to a substrate to remove fine foreign substances adhering to the surface of the substrate.

  As a prior art related to the present invention, an ultrasonic oscillator for applying ultrasonic waves and a sound pressure sensor are incorporated in a cleaning nozzle for discharging a cleaning liquid, and ultrasonic waves emitted from the ultrasonic oscillator are electrically converted by a sound pressure sensor. 2. Description of the Related Art An ultrasonic cleaning device configured to be able to monitor whether or not an ultrasonic oscillator is operating normally by measuring automatically is known (for example, see Patent Document 1).

JP 2001-162239 A

Various semiconductor devices typified by IC and LSI are manufactured by repeating various processes such as thin film formation, impurity introduction, photoresist formation, and etching on a silicon wafer.
Semiconductor devices are manufactured in a very clean space called a clean room that is maintained at a certain temperature and humidity. However, some contamination is always introduced in each process, and fine foreign matter (metal or organic matter) is introduced. ) Adheres to the silicon wafer being fabricated.
For this reason, the cleaning process performed between processes is an indispensable process for manufacturing a semiconductor device with a high yield (good product rate).

In such a cleaning process, wet cleaning, in which the silicon wafer obtained in the previous process is cleaned with a cleaning solution such as a chemical solution or pure water, has become the mainstream.
There are two types of wet cleaning: a dipping method in which a silicon wafer is immersed in a cleaning tank, and a spray method in which a cleaning liquid is sprayed from a cleaning nozzle at a predetermined discharge pressure and flow rate. Applying a sound wave is performed.

A spray-type cleaning apparatus that uses ultrasonic waves incorporates an ultrasonic oscillator for applying ultrasonic waves to the cleaning liquid inside the cleaning nozzle.
When ultrasonic waves are applied to the cleaning liquid, the so-called cavitation phenomenon reduces the pressure of the cleaning liquid to reach the saturated vapor pressure, and a part of the cleaning liquid evaporates and the generation and bursting of the cavity bubbles are repeated. The fine foreign matter adhering to the surface of the silicon wafer is efficiently removed by the shock wave generated when the rupture occurs.

For this reason, it can be said that the method of cleaning by applying ultrasonic waves to the cleaning liquid is very excellent from the viewpoint of the removal efficiency of foreign matter. However, this depends on the action of ultrasonic waves, and if the ultrasonic oscillator breaks down, the removal efficiency of foreign matters will be extremely deteriorated.
If the ultrasonic oscillator breaks down and the cleaning process continues without the operator noticing it, the silicon wafer that has not been sufficiently cleaned will be carried to the next process, resulting in a significant increase in product yield. It will make it worse.
In other words, in the manufacture of current semiconductor devices, it is extremely important to ensure that the cleaning process is carried out in order to maintain the product yield. To that end, it is essential to check the operation of the ultrasonic oscillator on a regular basis. .

To confirm the operation of the ultrasonic oscillator, interrupt the cleaning process, install a sound pressure sensor directly under the cleaning nozzle, discharge the cleaning liquid from the discharge port of the cleaning nozzle to the sound pressure sensor, and generate a voltage value from the sound pressure sensor. It is done by confirming.
If the ultrasonic oscillator is operating normally, a predetermined voltage value is confirmed by pressurizing the sound pressure sensor with ultrasonic waves propagating in the cleaning liquid, and the ultrasonic oscillator is operating normally. It can be judged.

  However, it is necessary to interrupt the cleaning process and install a sound pressure sensor below the cleaning nozzle every time the confirmation operation is performed. Reduce the availability of

As a solution to such a problem, a cleaning apparatus has been proposed in which a sound pressure sensor is built in a cleaning nozzle so that the operating state of an ultrasonic oscillator can be constantly monitored.
However, in the method in which the sound pressure sensor is built in the cleaning nozzle, since a part of the ultrasonic wave emitted from the ultrasonic oscillator is always absorbed by the sound pressure sensor, the absorbed amount is lost, and the ultrasonic wave is emitted from the ultrasonic oscillator. The ultrasonic waves that are generated cannot be used efficiently for the vibration of the cleaning liquid.
Even if the operating state of the ultrasonic oscillator is constantly monitored, it cannot be monitored whether or not the cleaning liquid is discharged at a predetermined discharge pressure.
In other words, in order for the cleaning process to be carried out properly, both the operating status of the ultrasonic oscillator and the discharge pressure of the cleaning liquid must be normal, and it is sufficient to monitor the operating status of the ultrasonic oscillator. I can't say that.

  The present invention has been made in consideration of the above-described circumstances, and the operation state of the ultrasonic oscillator and the discharge of the cleaning liquid while efficiently using the ultrasonic wave emitted from the ultrasonic oscillator for the excitation of the cleaning liquid. It is an object of the present invention to provide an ultrasonic cleaning apparatus that can monitor the discharge state of a cleaning liquid including pressure.

  The present invention includes a rotating table mounted with a substrate to be cleaned, a rotating table, a cleaning nozzle having an ultrasonic oscillator for discharging a cleaning liquid to which ultrasonic waves are applied, and cleaning the substrate, An ultrasonic cleaning apparatus including a humidity sensor that measures humidity and a monitoring unit that monitors humidity measured by the humidity sensor is provided.

  According to the ultrasonic cleaning apparatus of the present invention, the humidity in the vicinity of the cleaning nozzle is measured by the humidity sensor, and the measured humidity is monitored by the monitoring unit. Therefore, the ultrasonic wave emitted from the ultrasonic oscillator is used for exciting the cleaning liquid. It is possible to monitor the discharge state of the cleaning liquid including the operating state of the ultrasonic oscillator and the discharge pressure of the cleaning liquid while efficiently using it.

  In other words, when the ultrasonic oscillator operates normally and ultrasonic waves are applied to the cleaning liquid, the so-called cavitation phenomenon causes the pressure in the cleaning liquid to drop to the saturated vapor pressure, and a part of the cleaning liquid evaporates. Then, the generation and rupture of the cavity bubbles are repeated, and the water smoke rises from the discharged cleaning liquid. The fine mist that forms water smoke has a very small particle size and is easy to evaporate in the air. Therefore, when the ultrasonic oscillator operates normally and the cleaning liquid is discharged at the specified discharge pressure, the cleaning nozzle The nearby humidity is a constant high value.

  Therefore, by measuring and monitoring the humidity in the vicinity of the cleaning nozzle, it is possible to monitor the operating state of the ultrasonic oscillator and the discharge state of the cleaning liquid, including the discharge pressure of the cleaning liquid, and the operating state of the ultrasonic oscillator. Therefore, it is not necessary to incorporate a sound pressure sensor in the cleaning nozzle, so that the ultrasonic waves emitted from the ultrasonic oscillator can be efficiently used for exciting the cleaning liquid.

  An ultrasonic cleaning apparatus according to the present invention includes a rotary table mounted with a substrate to be cleaned and rotated, a cleaning nozzle having an ultrasonic oscillator and discharging a cleaning liquid to which ultrasonic waves are applied, and cleaning the substrate. A humidity sensor that measures the humidity in the vicinity of the cleaning nozzle and a monitoring unit that monitors the humidity measured by the humidity sensor are provided.

  In the ultrasonic cleaning apparatus according to the present invention, the rotary table means a table that rotates with a substrate to be cleaned, and the configuration thereof is not particularly limited as long as this object is achieved.

Further, the cleaning nozzle means a nozzle that includes an ultrasonic oscillator and discharges a cleaning liquid to which ultrasonic waves are applied toward the substrate, and its configuration is not particularly limited as long as this purpose is achieved. Absent.
Here, as the ultrasonic oscillator, for example, a piezoelectric ceramic that is distorted by application of a voltage and oscillates an ultrasonic wave is preferably used.
In addition, as the cleaning liquid, those generally used in the semiconductor device manufacturing process can be used, and are not particularly limited. For example, pure water, ammonium hydroxide (NH ₄ OH) / peroxide Hydrogen (H ₂ O ₂ ) -containing water, hydrogen chloride (HCl) / hydrogen peroxide-containing water, a mixed solution of sulfuric acid (H ₂ SO ₄ ) and hydrogen peroxide, hydrogen fluoride (HF) / hydrogen peroxide-containing water, Examples thereof include water containing hydrogen fluoride and water containing hydrogen fluoride / ammonium fluoride (NH ₄ F).

Further, the humidity sensor means one that electrically measures the humidity in the vicinity of the cleaning nozzle, and the configuration thereof is not particularly limited as long as this object is achieved.
As the humidity sensor, for example, a capacitive or resistive electric humidity sensor is exemplified, and among others, a capacitance change type humidity sensor having a configuration in which a polymer film as a moisture sensitive body is sandwiched between a pair of electrodes. From the viewpoint of the wide measurement range (0 to 100% RH) and the speed of response speed, it is preferably used.

The monitoring unit means a microcomputer that monitors humidity measured electrically by a humidity sensor, and the configuration thereof is not particularly limited as long as this object is achieved.
Examples of the monitoring unit include a CPU that performs arithmetic processing, a ROM that stores a control program for the CPU, a RAM that provides a work area for the CPU, a driver circuit that drives various driving units under the control of the CPU, and a humidity sensor. A microcomputer configured with I / O ports for inputting / outputting signals to / from various sensors can be used.

In the ultrasonic cleaning apparatus according to the present invention, the monitoring unit may stop the discharge of the cleaning nozzle when the measured humidity does not fall within a predetermined range.
As described above, when the ultrasonic oscillator operates normally and the cleaning liquid is discharged at a predetermined discharge pressure, the humidity near the cleaning nozzle has a constant high value.
Therefore, when the humidity measured during the cleaning process does not fall within the predetermined range, it can be determined that some abnormality has occurred in one or both of the operating state of the ultrasonic oscillator and the discharge pressure of the cleaning liquid, and the cleaning nozzle It is possible to prevent an insufficient cleaning process from being continued by stopping the discharge.

In the ultrasonic cleaning apparatus according to the present invention, the monitoring unit may obtain a temporal change rate of the humidity and stop the discharge of the cleaning nozzle when the change rate exceeds a predetermined threshold.
As described above, if the operating state of the ultrasonic oscillator and the discharge pressure of the cleaning liquid are both normal, the humidity in the vicinity of the cleaning nozzle remains at a constant high value. When the threshold value is exceeded, it can be judged that some abnormality has occurred in either or both of the ultrasonic oscillator operation status and the cleaning liquid discharge pressure, and insufficient cleaning processing continues by stopping the discharge of the cleaning nozzle. Can be prevented.

The ultrasonic cleaning apparatus according to the present invention further includes an arm for moving the cleaning nozzle along the substrate surface on the substrate, and the monitoring unit is configured to position the cleaning nozzle within a predetermined range from the axis of the rotary table. It is preferable to monitor the measured humidity.
This is because, in the above configuration, the cleaning nozzle moves along the surface of the rotating substrate, but in a region exceeding a predetermined range from the axis of the rotary table, the discharged cleaning liquid is subjected to centrifugal force generated by rotation. It moves toward the outside of the substrate, and as it approaches the outside of the substrate, the contact area with the air increases and it tends to evaporate, and the humidity tends to increase regardless of the operating state of the ultrasonic oscillator Because.
For this reason, the humidity measured in the region exceeding the predetermined range from the axis of the rotary table has a low causal relationship with the operating status of the ultrasonic oscillator, and the cleaning liquid including the operating status of the ultrasonic oscillator In order to accurately monitor the discharge state, it is preferable to monitor based on the humidity measured when the cleaning nozzle is located within a predetermined range from the axis of the rotary table.

From the above knowledge, in the above configuration further comprising an arm for moving the cleaning nozzle, when the substrate is substantially disk-shaped, the substrate is mounted on the rotary table so that the center thereof coincides with the axis of the rotary table. The arm may reciprocate the cleaning nozzle between the center and the outer edge of the substrate, and the monitoring unit may measure the humidity measured when the cleaning nozzle is positioned at the center of the substrate.
According to such a configuration, it is possible to accurately monitor the discharge state of the cleaning liquid including the operation state of the ultrasonic oscillator without being affected by the centrifugal force due to the rotation of the substrate.

  In the ultrasonic cleaning apparatus according to the present invention, the humidity sensor may be attached to the cleaning nozzle.

  Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings. 1 is an explanatory view of an ultrasonic cleaning apparatus according to the embodiment, FIG. 2 is an enlarged view of a main part of FIG. 1, FIG. 3 is an explanatory view showing a configuration of a cleaning nozzle of the ultrasonic cleaning apparatus shown in FIG. Is a graph showing the relationship between the distance along the substrate surface between the center of the substrate and the humidity sensor and the amount of change in humidity, and FIG. 5 is a graph showing the relationship between the vertical distance between the substrate surface and the humidity sensor and the humidity. FIG. 6 is a block diagram showing a configuration of a monitoring unit according to the present embodiment, and FIG. 7 is a flowchart showing a control flow performed by the monitoring unit in the present embodiment.

  As shown in FIG. 1, an ultrasonic cleaning apparatus 1 according to the embodiment includes a rotary table 3 that rotates with a substrate (disk-shaped silicon wafer) 2 to be cleaned, and an ultrasonic oscillator 4 (FIG. 3). A cleaning nozzle 6 for discharging the cleaning liquid 5 to which ultrasonic waves are applied and cleaning the substrate 2, a humidity sensor 7 for measuring the humidity in the vicinity of the cleaning nozzle 6, and the humidity sensor 7. And a monitoring unit 8 (see FIG. 6) for monitoring the humidity.

Hereinafter, the configuration and operation of the ultrasonic cleaning apparatus 1 according to the embodiment will be described in more detail.
As shown in FIG. 1, the ultrasonic cleaning apparatus 1 includes a turntable 3 that rotates while holding a substrate 2 to be cleaned.
The turntable 3 has a function of chucking the substrate 2, and a driving force is transmitted from the rotation drive unit 9 via the rotation shaft 10. The substrate 2 to be cleaned is mounted on the turntable 3 so that the center thereof coincides with the axis of the turntable 3.
The turntable 3 rotates at a rotation speed of 500 rpm or more with the substrate 2 being chucked. This is because at a rotational speed of less than 500 rpm, it is difficult to sufficiently blow off the cleaning liquid 5 discharged onto the surface of the substrate 2 by centrifugal force, and there is a possibility that the cleaning liquid 5 is insufficiently shaken off.

On the other hand, as shown in FIG. 3, the cleaning nozzle 6 is formed with an introduction port 6a through which the cleaning liquid 5 is introduced and a discharge port 6b through which the cleaning liquid 5 is discharged, and ultrasonic waves are introduced into the cleaning liquid 5 introduced from the introduction port 6a. Is embedded in the upper part.
Further, as shown in FIG. 1, the cleaning nozzle 6 is attached to the tip of an arm 12 driven by an arm drive motor 11 via a mount 13 and moves so as to draw an arc along the surface of the substrate 2. . The mount 13 interposed between the cleaning nozzle 6 and the arm 12 can be moved up and down by a mount lifting motor 14.
The cleaning nozzle 6 discharges the cleaning liquid 5 to which ultrasonic waves are applied at a predetermined discharge pressure while reciprocating between the center and the outer edge of the substrate 2 rotated by the arm 12.

As shown in FIG. 1, the cleaning nozzle 6 is connected to an oscillation power source 15, and the ultrasonic oscillator 4 (see FIG. 3) oscillates ultrasonic waves according to the frequency of the oscillation power source 15.
The cleaning nozzle 6 is connected to a cleaning liquid tank 18 via a pump 16 and an electromagnetic valve 17, and the cleaning liquid 5 is supplied to the inlet 6 a of the cleaning nozzle 6 at a predetermined pressure.

The discharge port 6b of the cleaning nozzle 6 has a diameter of about ^{2 to 10} mm, and discharges the cleaning liquid 5 at a flow rate of 0.1 L / min or more at a discharge pressure of about 1 to ² kg / cm ² .
The cleaning effect is reduced under the above discharge pressure. On the other hand, if the discharge pressure exceeds the above-described discharge pressure, damage to the substrate 2 increases, which may cause a defect. Therefore, managing the discharge pressure of the cleaning liquid 5 within the appropriate range is important for appropriately performing the cleaning process.
In this embodiment, since the diameter of the discharge port 6b of the cleaning nozzle 6 is constant, the flow rate of the cleaning liquid 5 is proportional to the discharge pressure.
In the present embodiment, pure water having a specific resistance value of 1 MΩ · cm ² or more is used as the cleaning liquid 5. The use of pure water that does not satisfy this specific resistance value may cause substrate contamination by the cleaning liquid 5, and is therefore preferably not used.

To the cleaning liquid 5 introduced from the introduction port 6a of the cleaning nozzle 6, ultrasonic waves having a sound pressure of about 350 to 450 mV in terms of voltage converted by a sound pressure sensor are applied from the ultrasonic oscillator 4 built in the upper part. .
When an ultrasonic wave having a voltage converted value of about 350 to 450 mV is applied to the cleaning liquid 5, the pressure in the liquid of the cleaning liquid 5 decreases and reaches a saturated vapor pressure due to a so-called cavitation phenomenon, and a part of the cleaning liquid 5 evaporates. Then, the generation and rupture of the cavity bubbles are repeated, and the foreign matter attached to the surface of the substrate 2 is efficiently removed (stripped) by the shock wave generated when the cavity bubbles are ruptured.

When the sound pressure of the ultrasonic wave applied to the cleaning liquid 5 is less than about 350 mV in terms of voltage, the generation of hollow bubbles is poor and the cleaning effect is reduced. On the other hand, when the sound pressure of the ultrasonic wave applied to the cleaning liquid 5 exceeds about 450 mV in terms of voltage, the damage given to the substrate 2 increases, which may cause defects.
For this reason, the intensity of the ultrasonic wave applied from the ultrasonic oscillator 4 to the cleaning liquid 5, that is, the sound pressure, is set to 350 to 450 mV in terms of a voltage converted value by the sound pressure sensor.

As described above, when ultrasonic waves are applied from the ultrasonic oscillator 4 and generation and rupture of the cavity bubbles are repeated in the cleaning liquid 5 due to the cavitation phenomenon, the water smoke 5a rises from the discharged cleaning liquid 5. The mist that forms the water smoke 5a has a very small particle size and is therefore easily evaporated, and the humidity in the vicinity of the cleaning nozzle 6 has a constant high value due to the water smoke 5a.
Therefore, in the present embodiment, the humidity sensor 7 is mounted outside the cleaning nozzle 6, and the humidity near the cleaning nozzle 6 is measured by the humidity sensor 7.
If the ultrasonic oscillator 4 (see FIG. 3) operates normally and the water smoke 5a due to the cavitation phenomenon rises from the cleaning liquid 5, a constant high value is measured by the humidity sensor 7, but the ultrasonic oscillator 4 If it does not operate normally, the cavitation phenomenon does not occur and the water smoke 5a does not rise, so that a high value is not measured.

Of course, the measured humidity value also varies depending on the discharge pressure of the cleaning liquid 5.
As described above, in the present embodiment, the flow rate of the cleaning liquid 5 is proportional to the discharge pressure. Therefore, if the discharge pressure decreases, the flow rate of the cleaning liquid 5 also decreases, and even if the ultrasonic oscillator 7 is operating normally, Since the amount of generation is reduced, the measured humidity value is lowered.
On the other hand, if the discharge pressure is increased, the flow rate of the cleaning liquid 5 is increased, and the amount of generated void bubbles is increased, so that the measured humidity value is increased.

Therefore, in this embodiment, based on the humidity measured by the humidity sensor 7, the operating state of the ultrasonic oscillator 4 and the discharge state of the cleaning liquid 5 including the discharge pressure of the cleaning liquid 4 can be monitored.
However, in order to accurately monitor the discharge state of the cleaning liquid 4 based on the humidity, it is preferable to monitor the discharge state based on the humidity measured at a position satisfying a predetermined condition.
In the present embodiment, the position satisfying the predetermined condition is a position where the axis of the rotary table 3, that is, a radius within 2 cm from the center of the substrate 2 and a height within 2 cm from the surface of the substrate 2. .

In order to derive such conditions, the following two experiments were conducted.
In the first experiment, the vertical distance H (see FIG. 2) between the surface of the substrate 2 and the humidity sensor 7 while rotating the substrate 2 at a constant rotation number, that is, a humidity sensor with respect to the surface of the substrate 2. While maintaining the height of 8 at 2 cm, the cleaning liquid 5 is discharged without operating the ultrasonic oscillator 4 (see FIG. 3), and the cleaning nozzle 5 is moved from the center of the substrate 2 to the outer edge over the surface of the substrate 2 over 60 seconds. The humidity variation was measured.

  As a result of the experiment, as shown in Table 1 and FIG. 3 below, the humidity relative to the initial value increases as the distance L (see FIG. 2) along the substrate surface between the center of the substrate 2 and the humidity sensor 7 increases. There was a tendency for the amount of change to increase, that is, a tendency to increase humidity. In this experiment, the initial value is a humidity value measured before the experiment is started and the cleaning nozzle 6 is positioned at the center of the substrate 2 and the cleaning liquid 5 is not discharged.

This is because the discharged cleaning liquid 5 moves so as to spread toward the outer periphery due to the centrifugal force caused by the rotation of the substrate 2, and the contact area with the air increases as the outer periphery approaches, so that the cleaning liquid 4 is easily evaporated. .
As shown in FIG. 3, it can be seen that when the distance from the center of the substrate 2 exceeds 3 cm, evaporation due to an increase in the contact area between the cleaning liquid 5 and air proceeds, and the amount of change in humidity with respect to the initial value increases.
Therefore, it can be said that a range within a radius of 2 cm from the center of the substrate 2 is suitable for measuring the humidity without being affected by the centrifugal force due to the rotation of the substrate 2.

In the second experiment, based on the previous experimental results, the distance L along the substrate surface between the center of the substrate 2 and the humidity sensor 7 is kept within 2 cm without being affected by the centrifugal force, and the ultrasonic wave The cleaning liquid 5 was discharged in a state where the oscillator 4 was operated, and the cleaning nozzle 6 was lifted vertically upward from the surface of the substrate 2 over 180 seconds to measure the change in humidity.
In this experiment, the initial value is a value measured before the experiment is started and the cleaning nozzle 6 is positioned at the center of the substrate 2 and the cleaning liquid 5 is not discharged.

  As a result of the experiment, as shown in Table 2 and FIG. 4 below, the amount of change in humidity with respect to the initial value as the vertical distance (height) H between the surface of the substrate 2 and the humidity sensor 7 increases. Tended to decrease, that is, a tendency to decrease humidity.

This is because the water smoke 5a rising from the cleaning liquid 5 due to the cavitation phenomenon when ultrasonic waves are applied evaporates in the vicinity of the surface of the substrate 2, and the evaporated water vapor is dispersed in the air as it moves vertically upward from the surface of the substrate 2. Because.
As shown in FIG. 4, it can be seen that when the height from the surface of the substrate 2 exceeds 3 cm, the amount of change in humidity with respect to the initial value becomes small.
Therefore, it can be said that a height within 2 cm from the surface of the substrate 2 is suitable for measuring an increase in humidity caused by the water smoke 5a generated by the cavitation phenomenon.

As described above, in the present embodiment, in order to accurately monitor the operating state of the ultrasonic oscillator 4 and the discharge state of the cleaning liquid 5 including the discharge pressure of the cleaning liquid 5 based on the humidity, the radius is within 2 cm from the center of the substrate 2. In addition, the discharge state of the cleaning liquid 5 is monitored based on the humidity measured at a height within 2 cm from the surface of the substrate 2.
The monitoring of the discharge state of the cleaning liquid 5 is to determine whether or not the ultrasonic oscillator 4 is operating normally and the cleaning liquid 5 is discharged at a predetermined discharge pressure. Then, this determination is performed by the monitoring unit 8.

  As shown in FIG. 6, the monitoring unit 8 includes a CPU 19 that performs arithmetic processing, a ROM 20 that stores a control program for the CPU 19, a RAM 21 that provides a work area to the CPU 19, a storage unit 22 that temporarily stores various information, and a CPU 19. The driver circuit 23 that drives various drive units under the control of the above and the I / O port 24 that inputs and outputs signals to and from various external sensors.

  Hereinafter, a control flow in which the monitoring unit 8 monitors the discharge state of the cleaning liquid 5 based on humidity will be described based on a flowchart shown in FIG. In addition, about each member quoted in the following description, please refer FIG.

  As shown in FIG. 7, when a cleaning process is requested, the monitoring unit 8 drives the arm drive motor 11 to position the cleaning nozzle 6 at the center of the substrate 2. At this time, the mount raising / lowering motor 14 is also driven, and the height of the cleaning nozzle 6 with respect to the surface of the substrate 2 is adjusted so that the distance H between the surface of the substrate 2 and the humidity sensor 7 is 2 cm. (Step 1).

When the cleaning nozzle 6 is positioned at the center of the substrate 2 in step 1, the monitoring unit 8 drives the rotation driving unit 9 to rotate the rotary table 3 at a predetermined number of rotations (step 2).
When the rotary table 3 is rotated at a predetermined rotational speed in step 2, the monitoring unit 8 causes the cleaning liquid 5 to be discharged toward the surface of the substrate 2 at a predetermined discharge pressure while operating the ultrasonic oscillator 4 of the cleaning nozzle 6. (Step 3).
When the cleaning liquid 5 is discharged from the cleaning nozzle 6 in step 3, the monitoring unit 8 causes the humidity sensor 7 to measure the humidity, and stores the measured humidity value in the storage unit 22 as humidity information (step 4).

When the humidity information is stored in the storage unit 22 in step 4, the monitoring unit 8 determines whether or not the stored humidity information value is within a predetermined range (step 5).
Here, the predetermined range means an allowable upper limit set in advance based on humidity measured during normal operation in which the ultrasonic oscillator 4 operates normally and the cleaning liquid 5 is discharged at a predetermined discharge pressure. Value and allowable lower limit.

If it is determined in step 5 that the humidity information value is within the predetermined range, the monitoring unit 8 determines that there is no abnormality in either the operating state of the ultrasonic oscillator 4 or the discharge pressure of the cleaning liquid 5. The cleaning nozzle 6 is reciprocated once along the surface of the substrate 2 at a predetermined speed between the center and the outer edge of the substrate 2 (step 6).
On the other hand, when determining that the value of the humidity information is not within the threshold range, the monitoring unit 8 determines that some abnormality has occurred in either or both of the operating state of the ultrasonic oscillator 4 and the discharge pressure of the cleaning liquid 4. Then, the cleaning process is stopped (step 10), and the series of flows is completed.

In step 6, the cleaning nozzle 6 is reciprocated once, and when the cleaning nozzle 6 returns to the center of the substrate 2, the monitoring unit 8 determines whether or not the cleaning processing of the substrate 2 is completed (step 7). If it is determined that it is not, the process returns to step 4 to cause the humidity sensor 7 to measure the humidity again.
On the other hand, if it is determined that the cleaning process has been completed, the operation of the ultrasonic oscillator 4 is stopped, the discharge of the cleaning liquid 5 is stopped (step 8), the rotation of the rotary table 3 is stopped (step 9), and a series of flows. Exit.

  In the control flow described above, each time the cleaning nozzle 6 is reciprocated once, the humidity is measured at the center of the substrate 2, and the operation of the ultrasonic oscillator 4 is determined by determining whether the measured humidity is within a predetermined range. The condition and the discharge state of the cleaning liquid 5 including the discharge pressure of the cleaning liquid 5 are monitored. The humidity change rate is obtained from the humidity measured at the same position with a time interval, and the change rate is compared with a predetermined threshold value. Thus, the discharge state of the cleaning liquid 4 may be monitored.

  In the present embodiment, pure water is used as the cleaning liquid. However, the present invention is not necessarily limited to pure water. Ammonium hydroxide / hydrogen peroxide-containing water, hydrogen chloride / hydrogen peroxide-containing water, sulfuric acid Various cleaning liquids such as a mixed solution of hydrogen and hydrogen peroxide, water containing hydrogen fluoride / hydrogen peroxide, water containing hydrogen fluoride, water containing hydrogen fluoride / ammonium fluoride can be used.

It is explanatory drawing of the ultrasonic cleaning apparatus which concerns on embodiment of this invention. It is a principal part enlarged view of FIG. It is explanatory drawing which shows the structure of the washing nozzle of the ultrasonic cleaning apparatus which concerns on embodiment of this invention. It is a graph which shows the relationship between the distance along the board | substrate surface between the center of a board | substrate, and a humidity sensor, and the variation | change_quantity of humidity. It is a graph which shows the relationship between the distance of the perpendicular direction between the surface of a board | substrate, and a humidity sensor, and the variation | change_quantity of humidity. It is a block diagram which shows the structure of the monitoring part of the ultrasonic cleaning apparatus which concerns on embodiment of this invention. It is a flowchart figure which shows the control flow which a monitoring part performs in embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Ultrasonic cleaning apparatus 2 ... Board | substrate 3 ... Rotary table 4 ... Ultrasonic oscillator 5 ... Cleaning liquid 5a ... Water smoke 6 ... Cleaning nozzle 6a ... Inlet 6b ... Discharge port 7 ... Humidity sensor 8 ... Monitoring unit 9 ... Rotation drive unit 10 ... Rotation shaft 11 ... Arm drive motor 12 ... Arm 13 ... Mount 14 ... Mount lift motor 15 ... Oscillating power supply 16 ... Pump 17 ... Electromagnetic valve 18 ... Cleaning fluid tank 19 ... CPU
20 ... ROM
21 ... RAM
22 ... Storage unit 23 ... Driver circuit 24 ... I / O port

Claims (6)

  A rotating table that mounts and rotates a substrate to be cleaned, a cleaning nozzle that has an ultrasonic oscillator and discharges a cleaning liquid to which ultrasonic waves are applied, and cleans the substrate, and measures the humidity near the cleaning nozzle An ultrasonic cleaning apparatus comprising a humidity sensor and a monitoring unit that monitors humidity measured by the humidity sensor.   The ultrasonic cleaning apparatus according to claim 1, wherein the monitoring unit stops the discharge of the cleaning nozzle when the measured humidity does not fall within a predetermined range.   The ultrasonic cleaning apparatus according to claim 1, wherein the monitoring unit obtains a temporal change rate of humidity and stops the discharge of the cleaning nozzle when the change rate exceeds a predetermined threshold.   An arm for moving the cleaning nozzle along the surface of the substrate on the substrate is further provided, and the monitoring unit monitors the humidity measured when the cleaning nozzle is located within a predetermined range from the axis of the rotary table. The ultrasonic cleaning apparatus as described in any one of -3.   When the substrate is substantially disk-shaped, the substrate is mounted on the rotary table so that its center coincides with the axis of the rotary table, and the arm reciprocates the cleaning nozzle between the center and the outer edge of the substrate, The ultrasonic cleaning apparatus according to claim 4, wherein the monitoring unit monitors the humidity measured when the cleaning nozzle is located at the center of the substrate.   The ultrasonic cleaning apparatus according to claim 1, wherein a humidity sensor is attached to the cleaning nozzle.

Images