JP5133305B2 - Substrate cleaning apparatus and cleaning method - Google Patents

Description

  The present invention relates to a method for cleaning a substrate used for manufacturing a semiconductor device or the like, and more particularly, to a cleaning apparatus for cleaning a photomask substrate, a photomask blank, a photomask, or a manufacturing intermediate thereof used in lithography, and the same. Related to the cleaning method.

  Photomasks used in a wide range of applications, including the manufacture of semiconductor integrated circuits such as IC, LSI or VLSI, basically contain a metal or a metal compound on a light-transmitting substrate (photomask substrate). It is obtained by processing the light shielding film of the photomask blank on which the light shielding film is formed by a thin film into a predetermined light shielding film pattern by using an electron beam photolithography method or the like.

  In the lithography method used in the process for producing precision electronic materials such as LSIs, for example, a photomask on which a diagram of an electronic circuit is drawn is used as an original drawing, and the pattern is formed on the photosensitive material by light irradiation. In recent years, along with market demands such as higher integration of semiconductor integrated circuits, pattern miniaturization has rapidly progressed, and higher precision of masks used for exposure has been required, and there has been a demand for defects in photomask blanks. It has become expensive.

For this reason, it is required that the quartz, CaF _{2 and} other substrates for manufacturing the photomask blank and the photomask blank be cleaned very precisely. Therefore, in addition to cleaning with a surfactant, multi-stage cleaning with hydrogen water or ozone water is usually performed, and rinsing with ultrapure water is performed at each stage as necessary (for example, Patent Documents). 1 and 2 etc.).

  On the other hand, even when the above-described multi-stage cleaning is performed, the substrate obtained is not unconditionally clean. For example, when the management of the cleaning liquid and the drying method are not appropriate, In some cases, particle contamination (contamination by minute foreign matter) may occur during drying (see, for example, Patent Documents 3 and 4). Furthermore, there is a problem of mist generated from the cleaning liquid as a cause of contamination during cleaning. As disclosed in Patent Document 5, the reattachment of the mist generated in the cleaning apparatus to the substrate due to the use of cleaning water also causes contamination.

JP 2001-96241 A JP 2002-151453 A JP 2009-21448 A Japanese Patent Laid-Open No. 2004-19993 JP 2005-252137 A

  Such contamination is observed as particle contamination when the substrate obtained by cleaning is inspected using, for example, laser light. In order to perform exposure of a finer pattern, a cleaner substrate for photomask manufacturing is required. If particle contamination such as that described above occurs on a transparent substrate or a film-forming intermediate film, lamination is performed. If it is on a mask blank, it may cause abnormal behavior during etching, peeling of the resist film, or abnormal shape of the resist pattern. There is a possibility to give.

  Therefore, in the cleaning process of the photomask substrate, the photomask blank intermediate, and the photomask blank, careful attention is paid so as not to cause the above-mentioned particle contamination, but cleaning is performed immediately before the application of the resist film for mask processing. Then, it is necessary to prevent contamination very highly.

  The present invention has been made in view of the above problems, and when a substrate used for manufacturing a semiconductor device or the like, in particular, a photomask substrate, a photomask blank, a photomask, or a manufacturing intermediate thereof is washed, It is an object of the present invention to provide a substrate cleaning apparatus and a cleaning method capable of extremely reducing the generation of foreign matters.

  In order to solve the above-described problems, the present invention provides at least an ultrapure water jet nozzle for jetting ultrapure water when cleaning a substrate with ultrapure water, and jets ultrapure water from the ultrapure water jet nozzle. And a substrate cleaning chamber for cleaning the substrate, and at least waiting for the ultrapure water ejection nozzle during standby before and after cleaning the substrate with ultrapure water. The substrate cleaning chamber has an ultrapure water ejection nozzle standby chamber partitioned by a partition, and the standby chamber is a mist from the drainage mechanism and the ultrapure water ejection nozzle standby chamber to the substrate cleaning chamber. Provided is a substrate cleaning apparatus comprising a diffusion preventing mechanism.

  By using such an apparatus, the operation of removing bubbles generated in the ultrapure water line is performed by discharging ultrapure water from the ultrapure water ejection nozzle during standby before and after cleaning the substrate with ultrapure water. In addition, it is possible to prevent mist derived from the discharged ultrapure water from diffusing into the substrate cleaning chamber and generating mist-derived particles on the surface of the substrate to be cleaned.

  The mist diffusion preventing mechanism can be an exhaust mechanism that exhausts the mist generated in the ultra pure water ejection nozzle standby chamber to the outside of the standby chamber. In this case, the mechanism for exhausting the mist is the ultra pure water. It can be set as the apparatus which attracts | sucks the gas in the ejection nozzle standby chamber.

  In this way, if the generated mist is exhausted from the ultrapure water ejection nozzle standby chamber before diffusing into the substrate cleaning chamber, substrate contamination by the mist in the substrate cleaning chamber can be prevented, and the mist is exhausted. If a device for sucking the gas in the ultrapure water ejection nozzle standby chamber is used as the mechanism, the mist can be easily and reliably exhausted.

The mist diffusion preventing mechanism may be a mechanism that closes the opening of the ultrapure water ejection nozzle standby chamber.
Specifically, in this mechanism, for example, when the ultrapure water ejection nozzle is outside the standby chamber, the opening of the standby chamber is closed with a shutter, and when the nozzle is in the standby chamber, the nozzle is in close contact with the opening of the standby chamber. And is achieved by sealing the opening.

The present invention also provides a substrate for a photomask, a photomask blank, a photomask, or a production intermediate therebetween while preventing mist diffusion from the standby chamber to the substrate cleaning chamber using the substrate cleaning apparatus. Provided is a method for cleaning a substrate, characterized in that the body is cleaned.
As described above, the cleaning method of the present invention can be preferably used particularly when cleaning a photomask substrate, a photomask blank, a photomask, or a production intermediate thereof.

  The step of cleaning the substrate includes at least (A) a step of discharging ultrapure water from the ultrapure water jet nozzle into the ultrapure water jet nozzle standby chamber, and (B) the ultrapure water jet nozzle It is preferable to include a step of moving the ultrapure water ejection nozzle standby chamber to the substrate cleaning chamber, and (C) a step of cleaning the substrate by ejecting ultrapure water from the ultrapure water ejection nozzle.

  After the ultrapure water is discharged in the ultrapure water ejection nozzle standby chamber as described above, the ultrapure water ejection nozzle is moved to the cleaning chamber, and cleaning of the substrate to be cleaned is started. Is prevented, and the possibility that the substrate to be cleaned is contaminated with mist can be greatly reduced.

  As described above, according to the cleaning device of the present invention, ultrapure water is discharged from the ultrapure water ejection nozzle during standby in the ultrapure water ejection nozzle standby chamber, thereby providing ultrapure water in the ultrapure water line. The generation of bubbles caused by the stop of water supply can be suppressed, or the generated bubbles can be discharged, and the mist generated at the time of discharge diffuses from the standby chamber to the cleaning chamber to bring the mist to the substrate cleaning chamber. Can be prevented. According to the substrate cleaning method using the apparatus of the present invention, by reducing the amount of mist in the cleaning chamber, it is possible to greatly suppress the chance that the substrate to be cleaned is subjected to particle contamination caused by mist adhesion. The cleaning yield of the photomask substrate, photomask blank, photomask, or production intermediates thereof can be greatly improved.

It is the schematic which showed an example of the washing | cleaning apparatus of the board | substrate of this invention. It is the schematic which showed an example of the mist spreading | diffusion prevention mechanism in the washing | cleaning apparatus of the board | substrate of this invention.

  As described above, at present, cleaning of photomask substrates, photomask blanks, photomasks, or photomask blanks and photomask manufacturing intermediates that are currently used for lithography processing of products having extremely fine pattern shapes such as semiconductors, etc. It is desirable that foreign matter contamination due to extremely fine particles is also eliminated, and various proposals have been made including improvement of the cleaning liquid and improvement of the drying method as mentioned in the prior art. However, although any method can find a certain effect, the problem of fine foreign matters has still occurred suddenly.

  In order to solve the problem of contamination due to fine foreign matters that occur suddenly, the present inventors assumed various causes of the occurrence and added an operation to eliminate the cause, thereby changing the state of occurrence of contamination. The cause of the problem and the solution method have been examined by the method of whether or not the problem has already occurred. As described above, as described above, fine bubbles are generated in the filter housing during the cleaning operation while the supply of the cleaning liquid is stopped. Generated and mixed in the cleaning liquid (Patent Document 3), mist generated during cleaning in the space where cleaning is performed (a fine droplet, and does not drop by gravity like a normal water droplet) (Patent document 5) etc. have been clarified. However, when trying to keep the number of particle contamination smaller than 0.2 μm of the next generation low, it is necessary to further improve the cleaning device in order to suppress the sudden increase in the number of particles generated.

The present invention is an improvement of the apparatus and the cleaning method for solving the above problems.
As disclosed in Patent Document 3, the ultrapure water used for cleaning uses a filter for removing fine foreign matters so as not to cause particle defects, but according to the study by the present inventors. When the supply to the cleaning liquid jet nozzle of the ultrapure water used for cleaning is temporarily stopped, bubbles are generated while waiting for the supply of ultrapure water, and fine bubbles generated in the ultrapure water are generated. It has been found that there is a particle problem that is thought to be caused by the adhesion of to the substrate surface.
The generation of the bubbles is not completely suppressed even when the bubble removing device is introduced into the ultrapure water production apparatus. As in Patent Document 3, the bubble removing device is placed at the most downstream portion of the ultrapure water line. Even if it is provided, bubbles may be generated while waiting for the supply of ultra pure water between the bubble eliminating device and the ultra pure water ejection nozzle.

  In order to prevent the occurrence of particle contamination due to such newly generated bubbles, the solution is to temporarily discharge the ultrapure water staying between the ultrapure water ejection nozzles from the bubble removing device before washing. Is the simplest method, but when a large amount of ultrapure water is discharged in the substrate cleaning chamber where the substrate is actually cleaned, the cleaning chamber is contaminated by splashes and a large amount of generated mist, and particle contamination is caused by this. It turns out that it occurs.

  Therefore, in order to prevent the generation of particles due to the bubbles, the ultrapure water once retained before the ultrapure water is used is discharged from the ultrapure water ejection nozzle in the cleaning device separately from the substrate cleaning chamber. An ultrapure water jet nozzle standby chamber that is partitioned and has a drainage mechanism is provided for the process, and after ultrapure water is discharged there, the ultrapure water jet nozzle is moved to the substrate cleaning chamber so that the substrate can be cleaned. The ultrapure water ejection nozzle was made movable, and the process of discharging ultrapure water was performed in a place separate from the cleaning chamber.

  However, since the effect of preventing particles was unexpectedly low even when the above-described apparatus was used, the present inventors further investigated the cause of the problem, and found that there was a problem in the following points. In the cleaning chamber of the substrate to be cleaned, the cleaning chamber is sized so as not to generate turbulent flow in the cleaning chamber in order to prevent the mist of cleaning liquid generated during cleaning from staying and reattaching to the substrate. Although suction for exhausting the gas inside is applied, mist generated in the ultrapure water ejection nozzle standby chamber by this suction may be diffused into the cleaning chamber. Even when the cleaning chamber is not sucked, if the substrate is rotated in the cleaning machine, a swirling airflow is formed in the cleaning chamber, and mist generated around the cleaning chamber is May spread in the form of being pulled in. That is, it was found that mist generated by the discharge of ultrapure water in the waiting room also causes contamination, and it was found that there is a need for advanced mist management over the entire cleaning apparatus.

  Accordingly, the present inventors have provided a partition wall between the substrate cleaning chamber that actually cleans the substrate and the place where the ultrapure water ejection nozzle is waiting during standby before and after cleaning the substrate, thereby providing an ultrapure water nozzle standby chamber. Furthermore, by providing a mechanism for preventing the mist from spreading in the waiting room, it is conceived that the problem of mist contamination can be solved and the number of particle-contaminated products detected by inspection can be greatly reduced. It came to make this invention.

  That is, the cleaning apparatus of the present invention includes at least an ultrapure water jet nozzle for jetting ultrapure water when cleaning a substrate with ultrapure water, and jets ultrapure water from the ultrapure water jet nozzle. A cleaning apparatus for cleaning a substrate having a substrate cleaning chamber for cleaning the substrate, and at least for waiting the ultrapure water ejection nozzle during standby before and after cleaning the substrate with ultrapure water The substrate cleaning chamber has an ultrapure water jet nozzle standby chamber partitioned by a partition wall, and the standby chamber prevents drainage mechanism and mist diffusion from the ultrapure water jet nozzle standby chamber to the substrate cleaning chamber. A mechanism is provided.

  According to such a cleaning apparatus of the present invention, in the ultrapure water ejection nozzle standby chamber, ultrapure water is discharged from the ultrapure water ejection nozzle during standby, thereby supplying ultrapure water into the ultrapure water line. It is possible to suppress the generation of bubbles caused by stopping or to discharge the generated bubbles, and to prevent the mist generated at the time of discharge from diffusing from the standby chamber to the cleaning chamber and bringing the mist to the substrate cleaning chamber. it can.

Hereinafter, the substrate cleaning apparatus of the present invention will be described in more detail with reference to the drawings, but the present invention is not limited thereto.
FIG. 1 is a schematic view showing an example of a substrate cleaning apparatus of the present invention.
The substrate cleaning apparatus 12 of the present invention ejects ultrapure water from the ultrapure water ejection nozzle 1 for ejecting ultrapure water when cleaning the substrate with ultrapure water, and the ultrapure water ejection nozzle 1. A substrate cleaning chamber 3 for cleaning the substrate and an ultrapure water ejection nozzle standby chamber 2 for waiting the ultrapure water ejection nozzle 1 during standby before and after cleaning the substrate with ultrapure water are provided.

  The substrate cleaning chamber 3 and the ultrapure water ejection nozzle standby chamber 2 are partitioned by a partition wall 11, and the ultrapure water ejection nozzle standby chamber 2 includes a standby chamber drain line 5 as a drainage mechanism, and a substrate cleaning chamber 3. As a mist diffusion preventing mechanism, a standby chamber gas exhaust line 4 is provided. The partition wall 11 and the standby chamber gas exhaust line 4 can effectively prevent the mist discharged from the nozzle 1 from the standby chamber 2 from being diffused into the cleaning chamber.

  A spinner 6 is installed in the substrate cleaning chamber 3 so that the substrate 7 to be cleaned can be sucked, fixed, and rotated. The substrate cleaning chamber 3 also has a substrate cleaning chamber mist exhaust line 9 to prevent substrate contamination caused by re-adhering mist generated in the cleaning chamber, and a cleaning liquid for discharging ultrapure water used for cleaning. A drain line 8 is provided.

The ultrapure water ejection nozzle standby chamber 2 is also provided with a standby chamber drain line 5 for discharging ultrapure water, and the ultrapure water discharged from the nozzle 1 in the standby chamber 2 is drained therefrom. The standby chamber drain line 5 is composed of a drain port (not shown) and a drain pipe, and may be sucked by a pump.
In order to acquire data for designing an appropriate exhaust amount of the apparatus, the amount of mist generated when ultrapure water is discharged from the ultrapure water ejection nozzle, the suction nozzle 10 for measuring mist particles is used as a standby for the ultrapure water ejection nozzle. This can be done by installing in the opening of the chamber 2 and measuring.

  Among the mist diffusion prevention mechanism from the ultrapure water ejection nozzle standby chamber to the substrate cleaning chamber, a simple method for remodeling is to exhaust the mist generated in the ultrapure water ejection nozzle standby chamber as described above. It is conceivable to provide a mechanism that performs this. Furthermore, in order to exhaust the mist in the ultrapure water ejection nozzle standby chamber of the above cleaning device, an exhaust suction device (pump) is connected to the ultrapure water ejection nozzle standby chamber as the mechanism that can be implemented most simply and reliably. In addition, there can be mentioned a mechanism that creates an air current that can exhaust the mist well in the ultrapure water ejection nozzle standby chamber.

Then, the present inventors installed an exhaust suction device in the ultra pure water ejection nozzle standby chamber, and created an air flow that exhausted the mist without diffusing from the opening. After the operation of discharging ultrapure water in the waiting room, the substrate was cleaned. As a result, the number of particle contamination of the cleaned substrate was greatly reduced. The air flow for exhausting the mist provided in the ultrapure water ejection nozzle standby chamber in this apparatus is opposite to the mist diffusion direction causing the problem at the opening of the nozzle standby chamber, that is, from the nozzle standby chamber opening. It is considered that the design should be such that the linear velocity is larger than the velocity at which the mist diffuses in the interior direction of the waiting room. Further, excessive suction is not preferable because it may cause turbulent flow. Therefore, the magnitude of this suction basically depends on the opening area of the opening of the ultrapure water ejection nozzle standby chamber of the apparatus, and is considered to be influenced by the shape. When a columnar ultrapure water ejection nozzle standby chamber is provided as a simple shape, from the data obtained by the present inventors, suction of 25 to 80 L / min is performed with respect to a space having a cross-sectional area of about 4 cm ^2. Is more preferable, and 30 to 50 L / min is more preferable. Therefore, it is considered that the preferred flow rate is preferably a flow rate of 6250 to 20000 cm / min without causing turbulent flow.

  Further, the mechanism for exhausting the mist from the standby chamber without diffusing from the opening of the standby chamber is not limited to the above. It is possible to exhaust the mist from the exhaust line together with the air flow by flowing it.

  On the other hand, as a mechanism different from the method of creating an air flow in the ultra pure water ejection nozzle standby chamber as described above, when the ultra pure water ejection nozzle is outside the standby chamber, the opening of the standby chamber is closed with a shutter, and the nozzle However, when waiting in the ultrapure water ejection nozzle standby chamber, a mechanism for closing the opening can be used so that mist cannot move between the standby chamber and the substrate cleaning chamber. For example, as shown in FIG. 2, when the ultrapure water ejection nozzle is in the standby chamber, the tip member of the nozzle is located at the opening of the standby chamber. Inserted into close contact, and the opening of the standby chamber is blocked by the ultrapure water ejection nozzle, the ultrapure water ejection nozzle standby chamber and the cleaning chamber are shut off, and the nozzle moves from the opening. In this case, there is a method of closing the opening by operating the shutter 14 with the closing device 13 for preventing mist diffusion.

Among these mechanisms, in terms of the simplicity of the mechanism of the device itself and the point of maintenance, a mechanism that prevents the mist from being diffused by exhausting the mist generated in the standby chamber to the outside of the standby chamber by the air flow created using the suction device. However, it is an easier solution and a more preferable method.
However, both the exhaust mechanism and the closing mechanism may be provided to prevent the mist from spreading more reliably.

  Further, the present invention provides a photomask substrate, a photomask blank, a photomask, or a production thereof, while preventing the mist from spreading from the standby chamber to the substrate cleaning chamber using the cleaning apparatus of the present invention. Provided is a method for cleaning a substrate, characterized by cleaning an intermediate.

  In this case, the step of cleaning the substrate includes at least (A) a step of discharging ultrapure water from the ultrapure water jet nozzle into the ultrapure water jet nozzle standby chamber, and (B) the ultrapure water jet nozzle. It is preferable to include a step of moving the ultrapure water ejection nozzle standby chamber to the substrate cleaning chamber, and (C) a step of cleaning the substrate by ejecting ultrapure water from the ultrapure water ejection nozzle.

  The substrate cleaning method of the present invention will be described using the above-described cleaning apparatus provided with the mist exhaust mechanism, but the present invention is not limited to these. The reason why such a device is used and the operation of the device are basically the same in other mechanisms for preventing mist diffusion.

  Specifically, the substrate 7 to be cleaned can be a photomask substrate, a photomask blank, a photomask, or a production intermediate thereof, and the cleaning with ultrapure water is a cleaning agent. It is the final cleaning after the cleaning using etc., the drying is performed after the cleaning with the ultra-pure water, and the cleaning process of each product or intermediate can be completed.

The ultrapure water to be used is produced by a known ultrapure water production apparatus, and usually includes ion exchange and foreign matter removal as well as bubble removal. The ultrapure water produced by this ultrapure water production apparatus is supplied to the substrate cleaning apparatus of the present invention through the ultrapure water line. Generally, the ultrapure water production apparatus is set in the vicinity of the substrate cleaning apparatus. There is nothing. Although the cause is not clear, even with ultrapure water from which bubbles have been removed, bubbles are generated in the line due to pressure fluctuations due to changes over time or the diameter of the supply line, etc. When pure water is stopped and a residence time is created, bubbles are likely to be generated in the line. For this reason, if a deaeration device is separately provided in the vicinity of the cleaning device as in Patent Document 3, the problem due to bubbles generated due to the above-described causes is reduced. In addition, by providing a deaeration device near the cleaning device, if it is desired to remove bubbles more completely, it occurred downstream of the separate deaeration device at the start of supplying ultrapure water for cleaning. The bubbles need only be removed, and the amount of ultrapure water containing bubbles to be exhausted when the supply of ultrapure water is started can be reduced.
However, even with such a method, there is a limit to removing all the bubbles, and particles caused by bubbles are actually generated.

  In the cleaning method of the present invention, the ultrapure water ejection nozzle 1 has a mechanism that can move between the ultrapure water ejection nozzle standby chamber 2 and the substrate cleaning chamber 3, and the ultrapure water ejection nozzle standby chamber 2 The mechanism that does not diffuse the mist generated when the ultrapure water is discharged from the drainage mechanism and the ultrapure water ejection nozzle 1 into the substrate cleaning chamber 3, preferably exhausts the mist generated in the ultrapure water ejection nozzle standby chamber 2. The following cleaning operation is carried out using a substrate cleaning apparatus provided with a mist exhaust device.

  As described above, the substrate 7 to be cleaned is set in the cleaning apparatus, and cleaning with another chemical solution is performed in some cases, but during the setting of the substrate 7 to be cleaned or during cleaning with another chemical solution, The pure water ejection nozzle 1 stands by in the ultra pure water ejection nozzle standby chamber 2. At this time, the ultrapure water may be continuously discharged so that bubbles are not newly generated in the ultrapure water line during the standby time, or the ultrapure water may be temporarily stopped. When the ultrapure water discharge is once stopped, the ultrapure water ejection nozzle standby chamber 2 moves the ultrapure water ultrapure water ejection nozzle 1 from the standby position in the standby chamber 2 to the cleaning chamber 3. The ultrapure water is discharged, and bubbles generated in the line are removed from the ultrapure water line. At this time, ultrapure water is discharged from the drainage line 5 of the drainage mechanism in the standby chamber 2 and mist is generated by the operation of discharging the ultrapure water. A directional airflow is created, the mist is exhausted by the airflow, and a mechanism that does not diffuse into the cleaning chamber 3 operates. This air flow may be always generated during the operation of the apparatus, and is started simultaneously with the discharge of the ultrapure water. After the ultrapure water discharge in the ultrapure water ejection nozzle standby chamber 2 is stopped, all the mist is exhausted. You may stop after taking time.

Next, prior to cleaning the substrate 7 to be cleaned with ultrapure water, the ultrapure water ejection nozzle 1 is moved from the standby position to the substrate cleaning chamber 3. As described above, the ultrapure water is discharged from the ultrapure water ejection nozzle 1 before the movement. If the ultrapure water is ejected during the movement, the ultrapure water is injected into the partition wall 11 separating the standby chamber 2 and the cleaning chamber 3. Since the water hits and scatters, it is preferable to stop the ejection of ultrapure water.
In addition, since the movement of the nozzle 1 from the standby chamber 2 to the cleaning chamber 3 is performed in a short time, no bubbles are generated in the line even if the ejection of ultrapure water is stopped.

  Furthermore, after the ultrapure water ejection nozzle 1 moves onto the substrate 7 to be cleaned, ultrapure water is ejected from the nozzle 1 and the substrate 7 to be cleaned is cleaned. As described above, the control of the mist in the cleaning chamber 3 is also important. For example, a substrate 7 for cleaning the mist generated in the cleaning chamber 3 by providing a mechanism such as exhaust by a method such as Patent Document 5. It is preferred that re-adhesion to be prevented.

EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to this.
[Experimental Example 1]
As shown in FIG. 1, a spinner 6 capable of rotating by adsorbing and fixing a substrate is installed, and a spin cleaning and drying machine for cleaning the substrate by supplying a cleaning chemical and ultrapure water to the fixed substrate, The substrate cleaning chamber 3 where the actual cleaning is performed is partitioned by a partition wall, and an ultrapure water ejection nozzle standby chamber 2 having a drain port on the lower surface of the space is provided so that ultrapure water can be drained in the space. An exhaust device capable of sucking and exhausting the gas in the pure water ejection nozzle standby chamber was installed. Moreover, the ultrapure water ejection nozzle was adjusted so that it could move between the substrate to be cleaned and the ultrapure water ejection nozzle standby chamber according to a predetermined cleaning process. At this time, the ultra pure water ejection nozzle standby chamber is a rectangular column-shaped space having a sufficient height (13 cm) so that the discharged ultra pure water does not fall and scatter and contaminate the nozzle. The opening area was 4 cm ² .
In order to measure the amount of mist generated when the ultrapure water is discharged from the ultrapure water ejection nozzle standby chamber, an opening for the ultrapure water ejection nozzle standby chamber is used. Nozzle) is installed, 0.481L (0.017ft3) of gas is sucked per second, and particles in the sucked gas are measured with a particle counter (Transtech A2100C: or He-Ne laser measurement method). I was able to do it.

First, ultrapure water is ejected from the ultrapure water ejection nozzle without operating an exhaust device that can suck and exhaust the gas in the ultrapure water ejection nozzle standby chamber, and the number of particles in the ultrapure water ejection nozzle standby chamber is determined. As a result of measurement, the total number of particles having a diameter of 0.1 μm or more observed for 10 seconds was 432 (89.8 / L).
Next, when the number of particles in the ultrapure water ejection nozzle standby chamber was measured with 20 L of suction exhaust per minute by the gas exhaust device in the ultrapure water ejection nozzle standby chamber, it was observed for 10 seconds. The total number of particles having a diameter of 1 μm or more is 106 (22.0 / L), and when the suction exhaust amount is increased to 25L, the total number of particles is about several, and the suction exhaust amount is further increased to 30L. As a result of measurement, no particles were observed on the particle counter.
When the suction exhaust amount was gradually increased, turbulent flow occurred when the suction exhaust amount exceeded 80L.

From this result, it was confirmed that mist diffusion could be prevented without generating turbulent flow by performing suction at 25 to 80 L / min into a space having a cross-sectional area of 4 cm ² . Then, from the relationship of the linear velocity = flow rate / cross-sectional area, the result of obtaining the linear velocity about the ultra-pure water spray nozzle antechamber ^{6250 (25L / 4cm 2) ~20000} (80L / 4cm 2) cm / min linear It was confirmed that if evacuation that creates an airflow having a velocity was performed, diffusion of mist from the ultrapure water ejection nozzle standby chamber to the substrate cleaning chamber could be prevented without generating turbulent flow.

[Examples and Comparative Examples]
Fifty-three photomask substrates having a square of 152 mm on one side and having CrON film formed as the outermost surface material were prepared, and cleaning and drying operations were continuously performed using the cleaning apparatus of the present invention. At this time, the cleaning cycle includes (1) fixing the substrate to be cleaned to the cleaning apparatus, (2) supplying 1 L of ultrapure water on the substrate to be cleaned for 9 minutes using the ultrapure water nozzle, Performing flush cleaning, (3) Spin drying at 1000 rpm for 60 seconds, (4) After completion of the drying operation, the substrate to be cleaned is taken out and the next substrate to be cleaned is fixed.
Also, the ultrapure water jet nozzle of the cleaning device discharges 1 L of ultrapure water per minute for 1 minute at the ultrapure water jet nozzle standby position before starting the first cleaning, and then (1) once ultrapure water (2) The ultrapure water ejection nozzle is moved from the standby chamber to the substrate cleaning chamber. (3) The ultrapure water is ejected and ultrapure water is supplied onto the substrate to be cleaned. (4) After the cleaning time is over, the ejection of ultrapure water is stopped, and the ultrapure water ejection nozzle is moved to the standby position. (5) When the ultrapure water ejection nozzle is returned to the standby position, the ultrapure water is discharged again. In the following, steps (1) to (5) were repeated in conjunction with the replacement of the substrate to be cleaned. Further, during the standby time for replacing the substrate to be cleaned, the discharge of ultrapure water from the ultrapure water ejection nozzle did not stop.

53 photomask substrates were continuously cleaned using the cleaning cycle and the ultrapure water ejection nozzle operation cycle as described above. At this time, the ultrapure water ejection nozzle was used up to the 29th. Exhaust by the gas exhaust device in the standby chamber is not performed, and when the 29th photomask substrate is completely cleaned, exhaust of 30 L / min by the gas exhaust device in the ultra pure water ejection nozzle standby chamber is started. Then, the exhaustion was continued until the cleaning of the 53rd photomask substrate was completed. On the substrate cleaning chamber side, suction was performed at 405 L per minute in order to prevent particle contamination of the substrate due to mist re-adherence generated in the cleaning chamber in cleaning all the substrates.
Further, the number of particle defects of the substrate after cleaning was measured by using (device name GM1000A) and using polystyrene particles as a standard.

After the cleaning of the 53 photomask substrates, the total number of defects newly observed for all 53 substrates was as follows.

Further, when the average number of particle defects in the cleaned substrate was compared, it was as follows.

  From the results shown in Tables 1 and 2, the ultrapure water jet nozzle is made to pass ultrapure water on the substrate to be cleaned between cleaning cycles by preventing the mist from spreading from the ultrapure water jet nozzle standby chamber to the substrate cleaning chamber. While waiting for the operation to supply, it was confirmed that even when ultrapure water was discharged from the ultrapure water jet nozzle to eliminate bubbles, it was possible to prevent the number of particle defects from increasing due to cleaning. .

  That is, according to the cleaning apparatus of the present invention, in the ultrapure water ejection nozzle standby chamber, ultrapure water is discharged from the ultrapure water ejection nozzle during standby, thereby stopping the supply of ultrapure water in the ultrapure water line. It is possible to suppress the generation of bubbles generated by the liquid or to discharge the generated bubbles and to prevent the mist generated at the time of discharge from diffusing from the standby chamber to the cleaning chamber and bringing the mist to the substrate cleaning chamber. In addition, according to the substrate cleaning method using the apparatus of the present invention, by reducing the amount of mist in the cleaning chamber, it is possible to greatly suppress the chance that the substrate to be cleaned is subjected to particle contamination caused by mist adhesion. It was proved that the cleaning yield of photomask substrates, photomask blanks, photomasks, or their production intermediates can be greatly improved. .

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has substantially the same configuration as the technical idea described in the claims of the present invention, and any device that exhibits the same function and effect is the present invention. It is included in the technical scope of the invention.

  DESCRIPTION OF SYMBOLS 1 ... Ultrapure water ejection nozzle, 2 ... Ultrapure water ejection nozzle standby chamber, 3 ... Substrate cleaning chamber, 4 ... Standby chamber exhaust line, 5 ... Standby chamber drain line, 6 ... Spinner, 7 ... Substrate to be cleaned, 8 ... Cleaning liquid drain line, 9 ... Cleaning chamber mist exhaust line, 10 ... Mist particle measurement suction nozzle, 11 ... Bulkhead, 12 ... Substrate cleaning device, 13 ... Mist diffusion prevention closing device (shutter device), 14 ... Shutter.

Claims (6)

  At least an ultrapure water jet nozzle for jetting ultrapure water when cleaning the substrate with ultrapure water, and a substrate cleaning chamber for jetting ultrapure water from the ultrapure water jet nozzle and cleaning the substrate. A cleaning apparatus for cleaning a substrate, wherein the partition cleaning chamber is a partition wall for waiting the ultrapure water ejection nozzle at least during standby before and after cleaning the substrate with ultrapure water. An ultrapure water ejection nozzle standby chamber partitioned by a drain chamber and a mechanism for preventing mist diffusion from the ultrapure water ejection nozzle standby chamber to the substrate cleaning chamber. A substrate cleaning apparatus.   2. The substrate cleaning apparatus according to claim 1, wherein the mist diffusion prevention mechanism is an exhaust mechanism that exhausts mist generated in the ultra pure water ejection nozzle standby chamber to the outside of the standby chamber.   The substrate cleaning apparatus according to claim 2, wherein the mechanism for exhausting the mist is a device for sucking a gas in the ultrapure water ejection nozzle standby chamber.   4. The substrate cleaning apparatus according to claim 1, wherein the mist diffusion preventing mechanism is a mechanism that closes an opening of the ultrapure water ejection nozzle standby chamber. 5.   A substrate for a photomask and a photomask blank while preventing mist from being diffused from the standby chamber to the substrate cleaning chamber by using the substrate cleaning apparatus according to any one of claims 1 to 4. A method for cleaning a substrate, comprising cleaning a photomask or a production intermediate thereof.   The step of cleaning the substrate includes at least (A) a step of discharging ultrapure water from the ultrapure water jet nozzle into the ultrapure water jet nozzle standby chamber, and (B) the ultrapure water jet nozzle being the ultrapure water. 6. The method according to claim 5, further comprising the step of moving the substrate from the water ejection nozzle standby chamber to the substrate cleaning chamber, and (C) cleaning the substrate by ejecting ultrapure water from the ultrapure water ejection nozzle. A method for cleaning a substrate as described.

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