JP3444574B2 - Substrate cleaning nozzle - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a substrate cleaning nozzle attached to a substrate cleaning apparatus and a substrate cleaning method.

[0002]

2. Description of the Related Art FIG. 10 is a cross-sectional view of a conventional substrate cleaning nozzle viewed from the side. The cleaning liquid injected from the cleaning liquid inlet 52 in the nozzle 53 is ejected onto the semiconductor substrate from the ejection port 54 by applying ultrasonic waves oscillated downward from the vibrator 51 having a single frequency. The ultrasonic waves resonate with the particles adhering to the substrate, so that the particles can be effectively removed.

[0003]

The particle size and material of the particles that can be removed depend on the frequency of the applied ultrasonic waves.
As an example thereof, FIG. 11 shows the relationship between the particle size of particles and the removal rate when the oxide film on the semiconductor silicon substrate is used as particles and the frequency f = 1.5 MHz. In FIG. 11, the horizontal axis represents particle diameter (μm) and the vertical axis represents particle removal rate (%). As shown in FIG. 11, the particle size is 0.
Particles having particle sizes of 4 and 0.8 (μm) are efficiently removed, but particles having other particle sizes have a low removal rate. That is, the particle size of the particles that can be efficiently removed is limited by the constant frequency. In order to cause the particles to resonate and be efficiently removed, it is necessary to satisfy the correlation that the particle size of the particles is 1 / (2n) times the wavelength of the applied ultrasonic wave (n is an integer). Further, when n becomes too large, the removal effect gradually decreases.

Therefore, there is a limit to the particle size of particles that can be efficiently removed with one type of frequency, and there is a problem that there are particle sizes that are difficult to remove by resonance with ultrasonic waves.

The present invention has been made in view of the above circumstances, and an object thereof is to effectively remove particles having various particle sizes such as silicon oxide adhering to a semiconductor silicon substrate.

[0006]

To achieve the above object, the present invention provides a cleaning solution inlet for injecting a cleaning solution for cleaning a substrate and ultrasonic waves having different frequencies,
It is characterized by comprising two vibrators for applying the ultrasonic wave to the cleaning liquid, and a cleaning liquid ejection port for ejecting the cleaning liquid to which the ultrasonic wave is applied onto the substrate.

Further, it is preferable that the two different resonance frequencies have a wavelength of one frequency other than an even multiple of the wavelength of the other frequency. Further, the ultrasonic wave emitted from the vibrator may be provided with a reflection plate for reflecting a portion having the highest intensity so as to irradiate the portion on the substrate.

Further, instead of the reflecting plate, a means for reflecting and transmitting may be provided. Further, as a substrate cleaning method using the substrate cleaning nozzle, a step of applying ultrasonic waves having two or more different frequencies to the cleaning liquid, and the cleaning liquid is jetted onto the substrate to remove adhering particles. And a process. Therefore, in particular, the substrate is a semiconductor silicon substrate, and the particles are silicon oxide.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A substrate cleaning nozzle and a substrate cleaning method according to embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view of a substrate cleaning nozzle according to a first embodiment of the present invention seen from a lateral side, and FIG. 2 is a cross-sectional view of a substrate cleaning nozzle according to a first embodiment of the present invention seen from a side surface. Is.

The substrate cleaning nozzle 8 is a combination of a cylindrical portion and a conical portion, and ultrasonic waves generated from cylindrical vibrators 2 and 3 having different resonance frequencies connected to an oscillator (not shown) are used as a cleaning liquid. Apply to the cleaning liquid injected from the inlet 1,
This cleaning liquid is ejected from the ejection port 7 onto the substrate 11 to clean the substrate.

FIG. 3 is an explanatory view showing the structure of a substrate support base 9 on which the substrate 11 is mounted, which is used when the substrate 11 is cleaned using the substrate cleaning nozzle 8 according to the first embodiment of the present invention. Is. Six support pins 10 are attached to the substrate support base 9. When the substrate 11 is placed, the semi-cylindrical support pins 10 rotate to press the substrate 11, and then the support rod portion of the substrate support base 9 is moved. The substrate support 9 rotates around the center.

FIG. 4 is a movement process diagram of the substrate cleaning nozzle 8 according to the first embodiment of the present invention. In the case of the linear rocking mechanism, 21 moves back and forth on a straight line from the center of rotation to the circumferential direction of rotation, and in the case of the rocking arm mechanism 22, the point 23
It moves back and forth on the circumference of a circle centered around.

By moving the substrate cleaning nozzle 8 in this manner, the substrate 11 can be thoroughly cleaned. Further, in the nozzle, cylindrical vibrators 2 and 3 having different frequencies, which are connected to an oscillator (not shown), are installed apart from each other so that they are not affected by each other.
Generally, the intensity of the ultrasonic wave oscillated from the oscillator is the highest from the center of the oscillator, so that the irradiation direction of each ultrasonic wave emitted from the centers of the oscillators 2 and 3 is the highest. The angle of the reflection plate 6 is determined and set so that the intersection on the extension line of is on the substrate 11.

As a result, the ultrasonic waves applied to the cleaning liquid injected from the cleaning liquid inlet 1 can reach the substrate in a state in which the attenuation of the ultrasonic waves is suppressed to the minimum, and the particle removal rate can be improved.

The removal of particles in the present invention is carried out by a method of causing particles adhering to an object to be cleaned to resonate with ultrasonic waves and giving kinetic energy exceeding the adhesion energy to remove the particles. Resonance of particles has a relationship of D = λ / (2n) (n is an integer), where λ is the wavelength of the applied ultrasonic wave and D is the diameter of the resonating particle, and when n is too large, it is effective. Since the particle diameter gradually drops, the particle diameter that can be easily removed is limited. FIG. 8A shows a waveform diagram of the wavelength λ. In this figure, the horizontal axis represents time and the vertical axis represents amplitude. In this case, the particle diameter that can be easily removed is D = λ / 2, λ / 4, ...
Therefore, there is no wavelength for resonating particles between λ / 2 and 3λ / 4 or between λ / 4 and λ / 2, and the effect of removing particles having a particle diameter in the corresponding region is low. On the other hand, FIG. 8B shows a waveform diagram of the wavelength λ ′ = λ / 3. In this figure, the horizontal axis represents time and the vertical axis represents amplitude. The particle diameter that can be easily removed by the ultrasonic wave of wavelength λ '= λ / 3 is D' = λ / 3, λ / 6, λ / 9, ... , And it is difficult to remove λ by the ultrasonic wave of λ of (a). / 3, λ /
Particles having a particle size of 9 or the like can be resonated and removed. Therefore, it becomes possible to remove particles having various particle diameters by using ultrasonic waves of two kinds of wavelengths.

FIG. 5 shows the relationship between the particle size of particles and the removal rate when the two frequencies are used independently and in combination. The horizontal axis of FIG. 5 indicates the particle size (μ
m), the vertical axis is the removal rate (%). Looking at this, the graph a for the frequency f = 1.5 MHz and the frequency f =
In the graph b at 0.5 MHz, there is a large difference in the removal rate depending on the particle size of each particle, but in the graph c when two frequencies are used together, a high removal rate is maintained regardless of the particle size of the particles. be able to.

Next, a substrate cleaning nozzle and a substrate cleaning method according to a second embodiment of the present invention will be described with reference to FIG. FIG. 7 is a lateral cross-sectional view of a substrate cleaning nozzle according to a second embodiment of the present invention.

The substrate cleaning nozzle 40 is a combination of two cylindrical parts and one conical part. The ultrasonic waves oscillated from the oscillator 32 are reflected by the reflector / transmissive plate 36 and travel toward the ejection port 37. In addition, the ultrasonic waves oscillated from the oscillator 31 pass through the reflector / transmissive plate 36 and head toward the ejection port 37. The ultrasonic waves oscillated from the two vibrators 31 and 32 are used as the cleaning liquid inlet 3
5 is applied to the cleaning liquid injected from the nozzle 5, and the cleaning liquid is ejected from the ejection port 37 to clean the substrate.

At this time, the reflection plate / transmission plate 36 allows the flow of the cleaning liquid in consideration of the rebound and interference of the sound wave in the nozzle, the reflectance of the sound wave from the vibrator 32 and the transmittance of the sound wave from the vibrator 31. And the frequency direction are set to be the same. Further, the position of the cleaning liquid inlet 35 is determined in consideration of convection of the cleaning liquid so that both ultrasonic waves are easily applied, and bubbles generated by vibration do not collect in the nozzle.

In the apparatus used in FIGS. 1 and 7, the diameter of the cylindrical portion is 10 to 15 mm and the diameter of the ejection port is 3 to 4 mm. The reason why the diameter of the ejection port is made smaller than that of the cylindrical portion in this way is to consider the load on the substrate and the flow rate of the cleaning liquid. When the diameter of the ejection port is made larger in the direction parallel to the paper surface than the direction perpendicular to the paper surface in which FIGS. 1 and 7 are described, the intersections on the extension lines of the irradiation directions of the two ultrasonic waves are located on the substrate. When coming, the distance between the ejection port and the substrate can be maintained.

In the embodiment of the present invention, the relationship between the wavelength of the ultrasonic wave emitted from one transducer and the wavelength of the ultrasonic wave emitted from the other transducer is not limited to λ '= λ / 3. Any wavelength can be used as long as it is not an even multiple of one wavelength.

In the first embodiment, it is possible to use three vibrators that emit three kinds of frequencies. The effect in this case is shown in FIG. In FIG. 6, the vertical axis represents the particle size (μm) of particles, and the horizontal axis represents the removal rate (%). When the frequency is 1.5 MHz, it is graph a, when it is 0.9 MHz, it is graph d, and when it is 0.5 MHz, it is graph b. Therefore, a more stable removal effect can be obtained.

Further, a substrate cleaning nozzle and a substrate cleaning method according to a third embodiment of the present invention will be described with reference to FIG. FIG. 9 is an explanatory diagram of a substrate cleaning nozzle according to the third embodiment of the present invention.

The substrate cleaning nozzle 44 is an FPD (Flat).
Panel Display). In this case, the substrate 46 is not rotated, and the cleaning liquid to which ultrasonic waves are applied is jetted from the substrate cleaning nozzle 44 in a waterfall shape and moved so that the cleaning time per unit area of the substrate 46 becomes uniform. By using the vibrator having two different frequencies, a high removal effect can be obtained as in the case of the semiconductor substrate described above.

[0025]

According to the present invention, it is possible to efficiently remove particles having various particle sizes by using two or more frequencies.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a substrate cleaning nozzle according to a first embodiment of the present invention as viewed from the side.

FIG. 2 is a cross-sectional view of the substrate cleaning nozzle according to the first embodiment of the present invention as seen from a side surface.

FIG. 3 is an explanatory diagram of a substrate support base used in the present invention.

FIG. 4 is a movement process diagram of the substrate cleaning nozzle of the present invention.

FIG. 5 is a correlation diagram between the particle size of particles and the removal rate when the two frequencies are used individually and in combination.

FIG. 6 is a correlation diagram between the particle size of particles and the removal rate when used in combination with each of the three frequencies.

FIG. 7 is a cross-sectional view of a substrate cleaning nozzle according to a second embodiment of the present invention as seen from the side.

FIG. 8A is a waveform diagram of wavelength λ. (B) It is a waveform diagram of wavelength λ ′ = λ / 3.

FIG. 9 is an explanatory diagram of a substrate cleaning nozzle according to a third embodiment of the present invention.

FIG. 10 is a cross-sectional view of a conventional substrate cleaning nozzle viewed from the side.

FIG. 11 shows a conventional substrate cleaning nozzle with a frequency of 1.5 MHz.
It is a correlation diagram of a particle size of particles and a removal rate when used under the condition of z.

[Explanation of symbols]

1, 35.52 ... Cleaning liquid inlet, 2, 3, 31, 32, 4
1, 42, 51 ... Oscillator, 4, 5, 32, 33 ... Oscillator, 6 ... Reflector, 7, 37, 45, 54 ... Cleaning liquid jet, 8, 40, 44, 53 ... Substrate cleaning nozzle, 9 ... Substrate support, 10 ... Support pins, 11, 46 ... Substrate, 36, 4
3 ... Reflective plate and transparent plate

─────────────────────────────────────────────────── --Continued from the front page (56) References JP-A-8-224555 (JP, A) JP-A-8-281230 (JP, A) JP-A-49-102323 (JP, A) JP-B-36- 22806 (JP, B1) (58) Fields surveyed (Int.Cl. ⁷ , DB name) H01L 21/304 B08B 3/12

Claims (4)

(57) [Claims] 1. A cleaning liquid inlet for injecting a cleaning liquid for cleaning a substrate, two oscillators for emitting ultrasonic waves having different frequencies and applying the ultrasonic waves to the cleaning liquid, and an oscillator for emitting the ultrasonic waves . Of the above ultrasonic waves, the highest intensity
A substrate cleaning nozzle comprising: a reflecting plate for reflecting a threshold portion onto a substrate so as to irradiate the substrate; and a cleaning liquid ejection port for ejecting the cleaning liquid to which the ultrasonic wave is applied onto the substrate. . 2. The substrate cleaning nozzle according to claim 1, wherein the two ultrasonic waves have a wavelength of one ultrasonic wave that is an odd multiple of the wavelength of the other ultrasonic wave. 3. Injecting a cleaning liquid for cleaning a substrate
The cleaning liquid inlet and ultrasonic waves with different frequencies are emitted to the cleaning liquid.
Of the two oscillators that apply the ultrasonic wave and the ultrasonic wave that is emitted from the oscillator, the intensity is the highest.
Reflect and transmit as if irradiating the threshold on the substrate
Means and the cleaning liquid to which the ultrasonic wave is applied on the substrate.
And a cleaning liquid jetting port for jetting
Substrate cleaning nozzle. 4. The two ultrasonic waves are waves of one ultrasonic wave.
Characterized in that the length is an odd multiple of the wavelength of the other ultrasonic wave
The substrate cleaning nozzle according to claim 3.