JP2012086108A - Method and device of ultrasonic cleaning - Google Patents

Abstract

An ultrasonic cleaning apparatus and method for reducing damage to an object to be cleaned by a cleaning liquid by irradiating ultrasonic waves on the entire surface of the object to be cleaned and reducing a cleaning time.
[Solution]
Adjust the size of the vibration member to which the ultrasonic vibrator is bonded to the size of the object to be cleaned, provide at least two cleaning liquid supply ports, and let the cleaning liquid flow from the cleaning liquid supply nozzle through the cleaning liquid supply port to the surface of the object to be cleaned. Applying an oscillation output from the oscillator to the ultrasonic vibrator while flowing the cleaning liquid with a nearly uniform thickness across the entire surface of the object to be cleaned by providing a small gap in parallel, the ultrasonic wave is applied to the surface of the object to be cleaned. Irradiates and propagates ultrasonic waves to the entire surface of the object to be cleaned covered by the cleaning liquid.
[Selection] Figure 1

Description

  The present invention relates to an ultrasonic cleaning method and apparatus for removing foreign matter attached to a substrate-like material such as various masks, glass substrates, and metal plates using an ultrasonic vibrator. In particular, the present invention relates to a photomask cleaning method.

  As a method for cleaning a substrate such as a semiconductor wafer, a photomask, or a liquid crystal substrate, for example, the substrate is immersed in a tank (cleaning tank) containing a cleaning liquid, and ultrasonic waves are applied from an ultrasonic vibrator provided at the bottom of the tank. There is a method of performing ultrasonic cleaning. When a voltage is applied to the ultrasonic transducer, an ultrasonic wave having a specific frequency is generated. By applying this ultrasonic vibration to the cleaning liquid in the cleaning tank, the substrate in the cleaning liquid can be cleaned.

Further, there is a method in which an ultrasonic vibrator is attached to the nozzle, and cleaning is performed by applying ultrasonic vibration to the cleaning liquid supplied into the nozzle and then spraying the cleaning liquid toward the substrate (object to be cleaned). Furthermore, the rod-shaped vibrating member is cut obliquely to form an ultrasonic irradiation surface, and an ultrasonic transducer is attached to the end opposite to the cutting surface, and the irradiation surface is attached to the object to be cleaned with a small interval. An ultrasonic device that cleans an object to be cleaned by allowing a cleaning liquid to flow from a side portion is disclosed (see Patent Document 1).

  For example, as a conventional ultrasonic cleaning apparatus, as shown in FIG. 3A, one end of the vibration member 11 is cut obliquely to form an ultrasonic irradiation surface 5, and the other end of the conventional vibration member 11 is The enormous portion 11 a is configured, and the conventional ultrasonic transducer 12 is attached to the enormous portion 11 a, and the vibrator case 13 is packed on the enormous portion 11 a of the conventional vibrating member 11 so as to cover the ultrasonic transducer 12. 14 is fixed with a screw (not shown), the cable 15 passes through the end of the transducer case 13, and the cord 15a of the cable 15 is connected to the conventional ultrasonic transducer 12, as shown in FIG. As described above, the cleaning liquid is supplied into the cleaning liquid supply nozzle 4, the cleaning liquid is supplied onto the rotating object 7 to be cleaned, and the ultrasonic wave from the ultrasonic vibrator 12 is propagated to the cleaning liquid 7 to be cleaned 7. To irradiate and wash Cleaning apparatus has been proposed a.

JP 2006-326486 A

However, since the effective cleaning range of the ultrasonic vibrator is narrow in the conventional cleaning device using the ultrasonic vibrator, the ultrasonic vibrator is swung from the center of rotation of the object to be cleaned toward the outer periphery. At the same time, a cleaning method has been adopted in which an object to be cleaned is rotated at a high speed and spirally directed from the center of rotation toward the outer periphery.
For this reason, there is a problem that the cleaning liquid is also exposed to a portion that is not irradiated with ultrasonic waves, so that, for example, an object to be cleaned such as a photomask is likely to undergo dimensional variation and film damage.
An object of the present invention is to provide an ultrasonic cleaning apparatus and method for reducing damage to an object to be cleaned by a cleaning liquid by irradiating the entire surface of the object to be cleaned with ultrasonic waves and shortening the cleaning time.

A specific configuration of the present invention for solving the above problems will be described below.
(Claim 1)
A surface-shaped ultrasonic transducer;
A surface-shaped vibrating member bonded to one side of the ultrasonic transducer;
A plurality of holes provided so as to penetrate both the ultrasonic transducer and the vibration member;
An ultrasonic cleaning apparatus comprising: a plurality of nozzles that pass through the plurality of holes and that discharge a cleaning liquid from one surface of the vibration member.
(Claim 2)
The ultrasonic cleaning method according to claim 1, wherein the vibrating member is quartz.
(Claim 3)
The ultrasonic cleaning method according to claim 1, wherein the vibration member is diamond.
(Claim 4)
The ultrasonic cleaning method according to claim 1, wherein the vibrating member is alumina.
(Claim 5)
The ultrasonic cleaning method according to claim 1, wherein the vibration member is titanium.
(Claim 6)
The ultrasonic cleaning method according to claim 1, wherein the vibration member is silicon nitride.
(Claim 7)
Using the ultrasonic cleaning device according to any one of claims 1 to 6,
The object to be cleaned is supported so as to be opposed to the surface of the vibrating member that is not in contact with the ultrasonic transducer with a minute gap,
While discharging the cleaning liquid from the plurality of nozzles, the ultrasonic vibrator is vibrated,
A cleaning method for cleaning an object to be cleaned.
(Claim 8)
The cleaning method according to claim 7, wherein the vibration member is 50% to 120% with respect to an area of the object to be cleaned.

  According to the ultrasonic cleaning apparatus of the present invention, by designing the size of the vibration member of the ultrasonic generator to match the size of the object to be cleaned, the moving distance of the object to be cleaned can be reduced, and the ultrasonic wave By supplying the cleaning liquid from the cleaning liquid supply port provided in the generation unit, it is possible to increase the replacement efficiency of the cleaning liquid, and it is possible to perform cleaning in a shorter time than conventional cleaning.

It is a block diagram of the ultrasonic cleaning apparatus of the Example of this invention. It is sectional drawing of the ultrasonic wave generation part of FIG. (A) of the conventional ultrasonic cleaning apparatus is a side view, (b) is a block diagram. It is a block diagram of the photomask for evaluation.

Hereinafter, an example of the specific configuration of the ultrasonic cleaning apparatus of the present invention will be described in detail.
The embodiments described below are specific configuration examples of the present invention and do not limit the present invention unless otherwise specified.
FIG. 1 is a schematic configuration diagram showing an ultrasonic cleaning apparatus 6 of the present invention.
As shown in the figure, the ultrasonic transducer 2 and the vibrating member 1 have a surface shape and are bonded to each other. A plurality of cleaning liquid supply nozzles 4 are provided in a plurality of holes 3 (hereinafter also referred to as cleaning liquid supply ports 3) provided so as to penetrate both the ultrasonic vibrator and the vibration member.
When cleaning is performed, the object to be cleaned 7 is supported so as to face the surface of the vibrating member 1 that is not in contact with the ultrasonic transducer 2 with a minute gap. At this time, the ultrasonic vibrator 2 is oscillated while the cleaning liquid is ejected from the plurality of nozzles 4 to vibrate the vibration member 1 to clean the object 7 to be cleaned.

According to the ultrasonic cleaning apparatus 6 of the present invention configured as described above, the effective cleaning range of the ultrasonic vibrator 2 is expanded, so that the moving distance of the cleaning object 7 is reduced and a plurality of cleaning liquids are supplied. By supplying the cleaning liquid from the cleaning liquid supply nozzle 4 provided in the mouth 3, it is possible to increase the replacement efficiency of the cleaning liquid and shorten the cleaning time, thereby reducing damage to the object 7 to be cleaned by the cleaning liquid.
In order to perform efficient cleaning, the vibration member is desirably 80% to 120% with respect to the area of the object to be cleaned.

Here, quartz, diamond, alumina, titanium, silicon nitride, stainless steel, or the like can be used as the vibrating member of the present invention, but is not limited thereto.
Various known ultrasonic vibrators can be used, and quartz is particularly preferable.
The output and frequency of the ultrasonic vibration are set so that the cleaning is efficiently performed according to the size of the photomask and the type of foreign matter. For example, it can be performed by applying ultrasonic waves under conditions of a frequency of 950 K to 2 MHz, an output of 1 to 30 W, and a time: 30 seconds to 10 minutes.

  In addition, as cleaning liquids that can be used in the cleaning method and apparatus of the present invention, pure water, ammonia perwater, sulfuric acid / hydrogen peroxide, hydrochloric acid / hydrogen peroxide, sulfuric acid, aqueous ammonia, hydrogen peroxide, tetramethylammonium hydroxide, ozone gas Dissolved water, hydrogen gas-dissolved water, nitrogen gas-dissolved water, carbon dioxide-dissolved water, helium gas-dissolved water, and argon gas-dissolved water can be used.

Examples of the present invention will be specifically described below, but this is only an example, and the present invention is not limited to these examples.
First, using the ultrasonic cleaning apparatus 6 of the present invention as shown in FIG. 1, MoSi is formed on the photomask substrate 20 (area 232 cm 2) shown in FIG. 4 by the ultrasonic cleaning method using the ultrasonic cleaning apparatus according to the present invention. The evaluation photomask 22 on which the (molybdenum silicon) pattern 21 was formed was cleaned.
At this time, the area of the vibration member and the ultrasonic vibrator was 250 cm 2, and eight holes were formed on both surfaces of the vibration member and the ultrasonic vibrator as the cleaning liquid supply port 3. The gap between the photomask substrate 20 and the ultrasonic irradiation surface 5 was 1 mm, the ultrasonic oscillation frequency was 2 MHz, and the oscillation output was 4 W. In addition, when the cleaning liquid (ammonia overwater) was supplied from the cleaning liquid supply nozzle 4 at 1.0 L / min, the cleaning was completed in 30 seconds.

(Comparative example)
Moreover, when the conventional ultrasonic cleaning apparatus 16 shown in FIG. 3B was used to clean the same evaluation photomask 22 as in Example 1 using the conventional ultrasonic cleaning method, the cleaning was completed in 2 minutes. .
At this time, the photomask substrate 7 and the vibrating member 11 were in contact with each other, the ultrasonic oscillation frequency was 2 MHz, and the oscillation output was 4 W. Further, a cleaning liquid (ammonia overwater) was supplied from the cleaning liquid supply nozzle 4 at a rate of 1.0 L / min.

  As described above, in the ultrasonic cleaning method using the ultrasonic cleaning apparatus 6 of the present invention, the cleaning time is shortened from 2 minutes to 30 seconds as compared with the ultrasonic cleaning method using the conventional ultrasonic cleaning apparatus 16, and the substrate Damage reduced.

DESCRIPTION OF SYMBOLS 1 ... Vibration member 2 ... Ultrasonic vibrator 3 ... Cleaning liquid supply port 4 ... Cleaning liquid supply nozzle 5 ... Ultrasonic irradiation surface 6 ... Ultrasonic cleaning apparatus 7 of this invention ... -Object to be cleaned (photomask substrate)
DESCRIPTION OF SYMBOLS 11 ... Conventional vibration member 11a ... Enormous part 12 ... Conventional ultrasonic vibrator 13 ... Vibrator case 14 ... Packing 15 ... Cable 15a ... Cord a
16 ... Conventional ultrasonic cleaning device 20 ... Photomask substrate 21 ... MoSi pattern 22 ... Photomask for evaluation

Claims (8)

A surface-shaped ultrasonic transducer;
A surface-shaped vibrating member bonded to one side of the ultrasonic transducer;
A plurality of holes provided so as to penetrate both the ultrasonic transducer and the vibration member;
An ultrasonic cleaning apparatus comprising: a plurality of nozzles that pass through the plurality of holes and that discharge a cleaning liquid from one surface of the vibration member.   The ultrasonic cleaning method according to claim 1, wherein the vibrating member is quartz.   The ultrasonic cleaning method according to claim 1, wherein the vibration member is diamond.   The ultrasonic cleaning method according to claim 1, wherein the vibrating member is alumina.   The ultrasonic cleaning method according to claim 1, wherein the vibration member is titanium.   The ultrasonic cleaning method according to claim 1, wherein the vibration member is silicon nitride. Using the ultrasonic cleaning device according to any one of claims 1 to 6,
The object to be cleaned is supported so as to be opposed to the surface of the vibrating member that is not in contact with the ultrasonic transducer with a minute gap,
While discharging the cleaning liquid from the plurality of nozzles, the ultrasonic vibrator is vibrated,
A cleaning method for cleaning an object to be cleaned.   The cleaning method according to claim 7, wherein the vibration member is 50% to 120% with respect to an area of the object to be cleaned.