JPH10214812A - Method and apparatus for cleaning wafer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable simultaneous cleaning of both sides of a wafer by jetting a first cleaning liquid, to which ultrasonic vibration is applied, toward one side of the wafer and simultaneously jetting a second cleaning liquid toward the other side. SOLUTION: A first cleaning liquid L1 jetted from an ultrasonic nozzle body 25 collides with one side of a semiconductor wafer 22 and the one side is cleaned by the first cleaning liquid L1 . Because the ultrasonic vibration from the ultrasonic nozzle body 25 is incident on the one side of the semiconductor wafer 22 at an angle θi smaller than the critical angle, part of the ultrasonic vibration is transmitted through the semiconductor wafer 22 and acts on the other side thereof so that the ultrasonic vibration is applied to a second cleaning liquid L2 jetted onto the other side, and the other side, on which a circuit pattern P of the semiconductor wafer 22 is formed, is also cleaned by the second cleaning liquid L2 to which the ultrasonic vibration is applied. Thus, both sides of the semiconductor wafer 22 can be cleaned simultaneously.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for cleaning a substrate for cleaning one side of a substrate on which a circuit pattern such as a semiconductor wafer is formed and the other side on which a circuit pattern is not formed. The present invention relates to a cleaning device.

[0002]

2. Description of the Related Art In the process of manufacturing a semiconductor device, there are a film forming process and a photo process for forming a circuit pattern on one surface of a semiconductor wafer as a substrate. In these processes, photolithography and cleaning are repeatedly performed on the semiconductor wafer. In the photolithography process, even if a small amount of dust adheres to the semiconductor wafer, it becomes a defect in a circuit pattern. Therefore, the cleaning process before the photolithography process is important.

On the semiconductor wafer, it is inevitable that more dust adheres to the other surface where the circuit pattern is not formed than to the one surface where the circuit pattern is formed.
In other words, when a circuit pattern is formed on one surface of a semiconductor wafer, the other surface is vacuum-adsorbed to a table, and when the semiconductor wafer is transferred, the other surface is transferred while being held by a robot. . Therefore, the semiconductor wafer has more dust on one surface than the other surface and adheres strongly.

If dust adheres to the other surface of the semiconductor wafer, the dust is transferred to one surface of another semiconductor wafer, and it becomes impossible to precisely form a circuit pattern on the semiconductor wafer. There is that. Therefore, it is necessary to sufficiently clean not only one surface of the semiconductor wafer on which the circuit pattern is formed but also the other surface on which the circuit pattern is not formed.

[0005] When cleaning the semiconductor wafer, a cleaning liquid to which ultrasonic vibrations are applied is sprayed onto the surface of the semiconductor wafer for cleaning. When cleaning both surfaces of the semiconductor wafer, first, a cleaning liquid to which ultrasonic vibration is applied is sprayed on one surface on which the circuit pattern is formed, and then the semiconductor wafer is turned over to form a circuit pattern. Cleaning is performed by spraying a cleaning liquid, which is also applied with ultrasonic vibration, to the other surface that is not provided.

However, if both surfaces of the semiconductor wafer are cleaned in this way, it takes time to clean both surfaces because one surface and the other surface must be sequentially cleaned. Not only have
If the semiconductor wafer is turned over by, for example, a robot in order to clean one surface and the other surface, dust may adhere at that time.

Further, when a cleaning liquid to which ultrasonic vibration is applied is directly sprayed on one surface of the semiconductor wafer on which the circuit pattern is formed, the adhered dust is surely removed, but the ultrasonic wave is removed. Vibration may damage the circuit pattern.

In order to prevent the circuit pattern from being damaged, it is sufficient to weaken the ultrasonic vibration applied to the cleaning liquid when cleaning one surface on which the circuit pattern is formed. . However, the degree of dirt on the other surface on which no circuit pattern is formed is greater than that on one surface as described above. Therefore, in order to clean the other surface with a high degree of cleanliness, the circuit pattern needs to be cleaned. Ultrasonic vibration applied to the cleaning liquid must be stronger than when one of the formed surfaces is cleaned.

In other words, in order to surely clean one surface and the other surface of the semiconductor wafer with the cleaning liquid to which ultrasonic vibrations are applied, respectively, when cleaning the one surface and the other surface, the cleaning liquid is used. Since the intensity of the applied ultrasonic vibration must be controlled, the operation may be complicated. In addition, the cleaning is performed without controlling the intensity of the ultrasonic vibration, so that reliable cleaning may not be performed or the circuit pattern may be damaged.

[0010]

As described above, when cleaning both surfaces of a semiconductor wafer, if one surface and the other surface are sequentially cleaned, a long cleaning time is required, and the productivity is reduced. Or a circuit pattern formed on one surface of the semiconductor wafer may be damaged by the ultrasonic vibration applied to the cleaning liquid.

SUMMARY OF THE INVENTION It is an object of the present invention to remove one surface and the other surface of a substrate without damaging a circuit pattern formed on one surface and reliably removing dirt from the other surface. An object of the present invention is to provide a method and an apparatus for cleaning a substrate which can be cleaned simultaneously.

[0012]

According to a first aspect of the present invention, there is provided a cleaning method for cleaning one side and the other side of a substrate having a circuit pattern formed on one side. Is sprayed toward the other surface of the substrate, and simultaneously, the second cleaning solution is sprayed onto the one surface.

According to a second aspect of the present invention, in the first aspect, the ultrasonic vibration applied to the first cleaning liquid is incident on the substrate at an angle smaller than the critical angle. According to a third aspect of the present invention, there is provided a cleaning apparatus for cleaning the one surface and the other surface of a substrate on which a circuit pattern is formed on one surface, wherein the rotary driving body for holding and rotating the substrate. And first cleaning liquid supply means for injecting a first cleaning liquid to which ultrasonic vibration has been applied toward the other surface of the substrate held by the rotary drive, and the first cleaning liquid supply unit held by the rotary drive. And a second cleaning liquid supply means for injecting a second cleaning liquid toward one surface of the substrate.

According to a fourth aspect of the present invention, in the third aspect of the present invention, the ultrasonic vibration applied to the first cleaning liquid is incident on the substrate at an angle smaller than the critical angle. According to a fifth aspect of the present invention, there is provided a cleaning apparatus for cleaning the one surface and the other surface of a substrate having a circuit pattern formed on one surface, wherein the transport means transports the substrate along a predetermined direction. And first cleaning liquid supply means for spraying a first cleaning liquid to which ultrasonic vibration is applied toward the other surface of the substrate conveyed by the conveyance means, and the substrate conveyed by the conveyance means Second towards one side of
And a second cleaning liquid supply means for injecting the cleaning liquid.

According to a sixth aspect of the present invention, in the fifth aspect of the present invention, the ultrasonic vibration applied to the first cleaning liquid is incident on the substrate at an angle smaller than the critical angle. The invention according to claim 7 is characterized in that the cleaning liquid to which ultrasonic vibration is applied is jetted from the nozzle hole of the ultrasonic nozzle body toward the substrate,
In the cleaning apparatus for cleaning the substrate, the ultrasonic nozzle body is inclined at an angle at which the ultrasonic vibration applied to the cleaning liquid passes through the substrate, and the sound wave reflected by the substrate does not enter the nozzle hole. It is characterized by being arranged.

In a cleaning apparatus for cleaning a substrate by spraying a cleaning liquid to which ultrasonic vibrations have been applied from an ultrasonic nozzle body toward the substrate and cleaning the substrate, an ultrasonic wave is applied to the thickness of the substrate. The wavelength of the vibration is set to a value that does not cause a critical angle in the ultrasonic wave incident on the substrate.

According to the first aspect of the present invention, the first cleaning liquid to which the ultrasonic vibration has been applied is sprayed onto the other surface of the substrate, so that ultrasonic vibration of a predetermined intensity acts on the other surface. And a portion of the ultrasonic vibration is attenuated and transmitted from the other surface to the one surface. The attenuated ultrasonic vibration acts on the second cleaning liquid sprayed on one surface, so that one surface is cleaned by the second cleaning liquid to which ultrasonic vibration weaker than the other surface is applied.

According to the third aspect of the present invention, the one surface and the other surface are simultaneously formed while rotating the substrate, and the one surface on which the circuit pattern is formed is higher than the other surface on which the circuit pattern is not formed. Also, it is cleaned with a cleaning liquid to which weak ultrasonic vibration is applied.

According to the fifth aspect of the present invention, while the substrate is being conveyed in a predetermined direction, one surface and the other surface are simultaneously formed, and one surface on which the circuit pattern is formed is the other surface on which the circuit pattern is not formed. The surface is cleaned with a cleaning liquid to which weaker ultrasonic vibration is applied.

According to the second, fourth and sixth aspects of the present invention, a part of the ultrasonic vibration incident on the other surface of the substrate can be surely transmitted to one surface. Ultrasonic vibration can be applied to the second cleaning liquid sprayed on the surface.

According to the seventh aspect of the present invention, the ultrasonic vibration applied to the cleaning liquid is transmitted through the substrate, so that both surfaces of the substrate can be cleaned at the same time, and the ultrasonic vibration reflected by the substrate is generated by the ultrasonic vibration. By not entering the nozzle hole of the nozzle body, it is possible to prevent the ultrasonic vibration reflected from the substrate from canceling the sound wave applied to the cleaning liquid, thereby reducing the cleaning effect and preventing the ultrasonic nozzle body from being damaged. According to the eighth aspect of the present invention, since the critical angle does not occur in the incident angle of the ultrasonic wave incident on the substrate, the arrangement state of the ultrasonic nozzle body is not restricted.

[0022]

Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 show a first embodiment of the present invention, and FIG. 1 shows a spin processing device as a cleaning device. This spin processing device has a cup body 1. This cup body 1 has a lower cup 1a and an upper cup 1b.
The upper cup 1b is vertically slidable with respect to the lower cup 1a. The peripheral wall of the upper cup 1b is inclined radially inward.

At the bottom of the lower cup 1a, one end of a plurality of exhaust pipes 2 is connected to the periphery, and an insertion hole 4 whose periphery is surrounded by a flange 3 is formed at the center.
The support shaft 5 is inserted through the insertion hole 4. Support shaft 5
The upper part protrudes into the cup body 1 and the lower end part is fixed to a base plate 6 disposed below the cup body 1.

A rotary chuck 11 as a rotary driving body is rotatably supported on the support shaft 5. This rotary chuck 11 is a rotary disk 1 having a through hole 12a formed in the center.
2 The lower surface of the turntable 12 has the through holes 12a.
Correspondingly, a cylindrical drive shaft 13 is vertically provided. The drive shaft 13 is fitted around the support shaft 5, and the upper and lower portions are rotatably supported by bearings 14.

A driven pulley 1 is provided at the lower end of the drive shaft 13.
5 is provided, and the base plate 6 is provided with a motor 16. The drive shaft is attached to the rotating shaft 16a of the motor 16.
A rib 17 is fitted. A belt 18 is stretched between the driving pulley 17 and the driven pulley 15. Therefore, if the motor 16 operates, the drive shaft 1
3, that is, the rotary chuck 11 is driven to rotate.

On the upper surface of the rotary disk 12 of the rotary chuck 11, four chuck shafts 19 are provided upright at intervals of 90 degrees in the circumferential direction. A support pin 19 is provided at the upper end of each chuck shaft 19.
a, and a support pin 19 is provided radially outside of the support pin 19a.
and an engagement pin 19b that is taller than a.

On the four chuck shafts 19, a semiconductor wafer 22 as a substrate to be cleaned has the lower surface of the peripheral portion supported by the support pins 19a, and the peripheral portion is formed by the engaging pins 19a.
b. This semiconductor wafer 22
Rotates integrally with the rotary chuck 11.

The semiconductor wafer 22 has a circuit pattern P formed on one surface, with one surface on which the circuit pattern P is formed facing downward and the other surface on which the circuit pattern P is not formed facing downward. The upper side is held by the chuck shaft 19.

An ultrasonic nozzle 25 is disposed above the semiconductor wafer 22 held by the rotary chuck 11 so as to be driven in a radial direction of the semiconductor wafer 22 by a driving mechanism (not shown). The ultrasonic nozzle body 25 is provided with a vibration plate (both not shown) having an ultrasonic vibrator attached therein, and the ultrasonic nozzle body 25 is provided with a second liquid such as a chemical solution or pure water supplied into the ultrasonic nozzle body 25. Ultrasonic vibration is applied to the first cleaning liquid L1.

The first cleaning liquid L 1 to which the ultrasonic vibration has been applied by the ultrasonic nose body 25 is applied to the other of the upper surface side of the semiconductor wafer 22 held on the chuck shaft 19 where the circuit pattern P is not formed. Injected toward the surface.

As shown in FIG. 2, the ultrasonic nozzle 2
5, the incident angle .theta.i at which the ultrasonic vibration applied to the first cleaning liquid L1 injected from the ultrasonic nozzle body 25 is incident on the other surface of the semiconductor wafer 22, The angle is set smaller than the angle of total reflection (critical angle θc) on the plate surface of the wafer 22.

As a result, at least a part of the ultrasonic vibration wave incident on the other surface of the semiconductor wafer 22 is transmitted through the semiconductor wafer 22 and the rest is reflected at the reflection angle θr.

The critical angle θc can be obtained by the following equation. sin θc = C1 / C2 (1) where C1 is the sound velocity in the medium on the upper surface side of the semiconductor wafer 22, that is, the sound velocity in the first cleaning liquid L1, and C2 is the sound velocity in the semiconductor wafer 22. C1 = 1500m / sec,
Since C2 = 9000 m / sec, the critical angle θ
When c is calculated, sin θc = 1500 ÷ 9000 = 0.166, so each critical θc is 9.6 degrees.

That is, if the incident angle of the ultrasonic vibration wave incident on the semiconductor wafer 22 from the ultrasonic nozzle body 25 is less than 9.6 degrees, at least a part of the ultrasonic vibration wave incident on the semiconductor wafer 22 22 to reach the back side.

As shown in FIG. 2, if the incident wave λi of the ultrasonic vibration incident on the semiconductor wafer 22 is smaller than the critical angle θc, a part of the incident wave λi becomes a reflected wave λr and the other part is transmitted. Wave λt.

The critical angle θc varies depending on various conditions such as the type of the first cleaning liquid L1, and is not limited to 9.6 degrees. At the upper end of the support shaft 5, a head 5a having a diameter larger than that of the support shaft 5 and having a conical shape is provided.
The support shaft 5 is provided with a cleaning liquid supply passage 31 whose upper end is open to the head 5a and a gas supply passage 32 extending in the axial direction, and is open to the head 5a.

A second cleaning liquid L2 such as a chemical solution or pure water is jetted from the cleaning liquid supply path 31 toward one of the lower surfaces of the semiconductor wafer 22, on which the circuit pattern P is formed. An inert gas such as nitrogen is supplied from the gas supply path 32. Cleaning solution supply path 3
The second cleaning liquid L2 sprayed from 1 is applied to the semiconductor wafer 22.
Flows while covering the front surface of one of the surfaces.

Next, a case where the semiconductor wafer 22 is cleaned by the spin processing apparatus having the above configuration will be described.
When the semiconductor wafer 22 is held on the four chuck shafts 19, the motor 16 is operated to rotate the rotary chuck 11, and ultrasonic vibration is applied to the other upper surface of the semiconductor wafer 22. The applied first cleaning liquid L1 is ejected from the ultrasonic nozzle body 25, and the first surface on which the circuit pattern P on the lower surface side is formed is supplied from the cleaning liquid supply passage 31 to the second surface.
The cleaning liquid L2 is sprayed. Then, the ultrasonic nozzle body 25 is driven along the radial direction of the semiconductor wafer 22.

When the first cleaning liquid L1 ejected from the ultrasonic nozzle body 25 collides with the other surface of the semiconductor wafer 22, this other surface is cleaned by the first cleaning liquid L1. Since the ultrasonic vibration colliding with the cleaning liquid on the other surface of the semiconductor wafer 22 is hardly attenuated, the other surface of the semiconductor wafer 22 is cleaned with the first cleaning liquid L1 to which strong ultrasonic vibration is applied. become.

Since the other surface of the semiconductor wafer 22 is more contaminated than the one surface as described above, the semiconductor wafer 22 is cleaned with the first cleaning liquid L1 to which strong ultrasonic vibration is applied, so that precise cleaning is performed. In other words, cleaning is performed in which almost no fine particles remain.

The ultrasonic vibration from the ultrasonic nozzle body 25 is incident on the other surface of the semiconductor wafer 22 at an angle smaller than the critical angle θc. Therefore, a part of the ultrasonic vibration is transmitted through the semiconductor wafer 22 and acts on one surface, which is on the back surface side.
The ultrasonic vibration is applied to the cleaning liquid L2.

Accordingly, one surface of the semiconductor wafer 22 on which the circuit pattern P is formed is also cleaned with the second cleaning liquid L2 to which ultrasonic vibration has been applied. That is,
The other surface and the one surface of the semiconductor wafer 22 can be simultaneously cleaned with the first cleaning liquid L1 and the second cleaning liquid L2 to which ultrasonic vibration has been applied.

The ultrasonic vibration is attenuated by transmitting through the semiconductor wafer 22. Therefore, the ultrasonic vibration applied to the second cleaning liquid L2 is weaker than the ultrasonic vibration applied to the first cleaning liquid L1, so that one surface of the semiconductor wafer 22 to be cleaned by the second cleaning liquid L2 The formed circuit pattern P is not damaged by strong ultrasonic vibration.

That is, the first ultrasonic nozzle 25
Even if the ultrasonic vibration applied to the cleaning liquid L1 is strong enough to reliably remove the dirt on the other surface of the semiconductor wafer 22, it passes through the semiconductor wafer 22 and reaches one surface. Since it is attenuated, cleaning can be performed without damaging the circuit pattern P formed on one surface thereof.

In other words, when it is desired to clean one surface of the semiconductor wafer 22 on which the circuit pattern P is formed and the other surface on which the circuit pattern P is not formed with a cleaning liquid to which ultrasonic vibrations of different strengths are applied. Both surfaces can be cleaned at the same time and without controlling the intensity of the ultrasonic vibration according to the one surface and the other surface.

Further, the angle of the ultrasonic nozzle body 25, that is, the incident angle θi at which the ultrasonic vibration is incident on the semiconductor wafer 22
Is changed so as not to be larger than the critical angle θc, the transmission amount of the ultrasonic vibration transmitted through the semiconductor wafer 22, that is, the intensity can be changed. Therefore, the degree of cleaning of one surface of the semiconductor wafer 22 on which the circuit pattern P is formed can be controlled by changing the angle of the ultrasonic nozzle body 25 without controlling the power applied to the ultrasonic vibrator.

FIG. 3 shows experimental results obtained by measuring the cleaning effect when the semiconductor wafer 22 is cleaned by various cleaning methods. The points A to C in the figure are the particle removal rates, and the bar graphs are the number of particles before and after cleaning.

A point A in the figure indicates that the cleaning liquid (rinse liquid) is supplied to the lower surface of the semiconductor wafer 22 while rotating the semiconductor wafer 22 while rotating the semiconductor wafer 22, and the cleaning liquid to which ultrasonic vibration is applied is sprayed from the upper surface. The removal rate of the particles before and after the cleaning was 26%.
This method is referred to as a first cleaning method.

At point B in the figure, the contaminated surface is turned upward while the semiconductor wafer 22 is rotated, and a cleaning liquid to which ultrasonic vibration is applied is sprayed from the upper surface, and a cleaning liquid (rinse liquid) is sprayed to the lower surface for cleaning. In this case, the removal rate of the particles before and after the cleaning was 83%. This method is referred to as a second cleaning method.

In the figure, the point C is a cleaning liquid (rinse liquid) with the contaminated surface facing downward while rotating the semiconductor wafer 22.
And the removal rate of the particles before and after cleaning when the cleaning liquid to which ultrasonic vibrations were applied was sprayed from the upper surface, and the value was 84%. This method is referred to as a third cleaning method.

The conditions for each experiment were as follows: the supply of the rinsing liquid was 1000 cc / min, the supply of the cleaning liquid was 200 cc / min, and the output of the ultrasonic oscillator driving the ultrasonic vibrator was 15 W. From the above experimental results, the same is true even when the cleaning liquid to which the ultrasonic vibration is applied is jetted from the surface opposite to the contaminated surface without directly jetting the cleaning liquid to which the ultrasonic vibration is applied to the contaminated surface. It was confirmed that a cleaning effect was obtained.

FIG. 4 shows a second embodiment of the present invention. This embodiment is a cleaning apparatus for cleaning a semiconductor wafer 22 while carrying a roller. That is, the cleaning apparatus of this embodiment includes the transfer path 35 that transfers the semiconductor wafer 22 in a predetermined direction. The transport path 35 is formed by a plurality of transport rollers 36 arranged at predetermined intervals. Each transfer roller 36 has a stepped portion 36a formed at both ends, and the semiconductor wafer 22 to be transferred is transferred by the transfer roller 36.
, And only the radial end of the semiconductor wafer 22 comes into contact with the stepped portion 36a.

The semiconductor wafer 22 is transported on the transport path 35 with one surface on which the circuit pattern P is formed facing downward. An ultrasonic nozzle body 25A is provided above the middle of the transport path 35, and a slit nozzle body 41 is provided below. The ultrasonic nozzle body 25A is formed to be elongated along the width direction of the transfer path 35, and a slit 42 having a length equal to or larger than the diameter of the semiconductor wafer 22 transferred on the transfer path 35 is provided at the lower end. .

The first cleaning liquid L 1 is supplied to the ultrasonic nozzle body 25 A, where the first cleaning liquid L 1 is applied thereto, and is jetted from the slit 42 toward the other surface, which is the upper surface of the semiconductor wafer 22, from the slit 42. You. The ultrasonic nozzle body 25A
Of the center axis O2 of the semiconductor wafer 22 with respect to the plate surface,
That is, the angle at which the ultrasonic vibration applied to the first cleaning liquid L1 is incident on the semiconductor wafer 22 is set to be smaller than the critical angle θc.

As a result, a part of the ultrasonic vibration incident on the other surface of the semiconductor wafer 22 is transmitted and the rest is reflected, as in the first embodiment. The slit nozzle body 41 is connected to the ultrasonic nozzle body 2
The slit 43 has a length substantially equal to that of 5A, and has a slit 43 for spraying the second cleaning liquid L2 toward the other surface on the lower surface of the semiconductor wafer 22 on which the circuit pattern P is formed. Is formed.

According to such a configuration, the transport path 3 is formed by the ultrasonic nozzle body 25A and the slit nozzle body 41, respectively.
When the first cleaning liquid L1 and the second cleaning liquid L2 are sprayed on the other surface and the one surface of the semiconductor wafer 22 to which the wafer 5 is conveyed, the semiconductor cleaning is performed by the first cleaning liquid L1 to which ultrasonic vibration is applied. The other surface of the wafer 22 is cleaned, and the ultrasonic vibration transmitted from the other surface to one surface is applied to the second cleaning solution L2 sprayed on the one surface, so that the second cleaning solution L2 Thus, one surface of the semiconductor wafer 22 is also cleaned.

That is, the other surface and the one surface of the semiconductor wafer 22 can be cleaned at the same time, and one surface can be cleaned with the second cleaning liquid L2 to which ultrasonic vibrations weaker than the other surface are applied. Since the intensity of the ultrasonic vibration applied to the second cleaning liquid L2 is attenuated by passing through the semiconductor wafer 22, the intensity of the ultrasonic vibration is controlled to be different between the one surface and the other surface without controlling the intensity of the ultrasonic vibration. The cleaning can be performed with the cleaning liquid to which the ultrasonic vibration is applied.

FIG. 5 is an explanatory diagram of a third embodiment of the present invention. In this embodiment, the semiconductor wafer 22 was cleaned under the following conditions. The thickness of the semiconductor wafer 22 is 0.65 mm
The wavelength λ of the ultrasonic vibration applied to the first cleaning liquid L1 is
6.38 mm. That is, the wavelength λ can be obtained by λ = C / f (2) Where C is 9000 m / se in sound speed
and f is the frequency of the ultrasonic wave set to 1410 kHz by an ultrasonic oscillator (not shown), so that the wavelength λ is 6.38 mm.
Becomes

The distance L between the tip of the ultrasonic nozzle body 25 and the plate surface of the semiconductor wafer 22 is set to 20 mm, and pure water is supplied to the ultrasonic nozzle body 25 at a rate of 1 liter / min. Applied a power of 30 W (19.5 W / cm ² ). Further, the inner diameter d of the nozzle hole 25a of the ultrasonic nozzle body 25
Is 4 mm.

The inclination angle of the axis O1 of the ultrasonic nozzle body 25 with respect to the plate surface of the semiconductor wafer 22, that is, the incident angle θi of the ultrasonic vibration emitted from the ultrasonic nozzle body 25 with respect to the semiconductor wafer 22, is changed. Was measured.

FIG. 6 shows that the incident angle θi of the ultrasonic vibration is 0 degree to 4 degrees.
This is a result of measuring a sound pressure applied to the semiconductor wafer 22 and a sound pressure transmitted therethrough when the angle is changed in a range of 5 degrees. In the figure, the curve A indicates the irradiation sound pressure V for irradiating the semiconductor wafer 22, and the curve B indicates the transmission sound pressure V1. The irradiation sound pressure V becomes smaller than the emission sound pressure V0 from the ultrasonic nozzle body 25, and the value can be calculated from the incident angle θi of the emission sound pressure V0 by the following equation. It is a calculated value.

V = V 0 · cos θi (3) From the above, it can be seen that the theoretical sound pressure V substantially coincides with the irradiation sound pressure V 0 and decreases as the incident angle θ i increases. It can also be seen that the transmitted sound pressure V1 is lower than the irradiation sound pressure V0.

FIG. 7 is a graph showing the relationship between the incident angle θi and the reflectivity of ultrasonic vibration. The reflectivity is as high as about 36% when the incident angle θi is 0 °, but is about 26% when the incident angle θi is 5 ° or more. % Was almost constant.

FIG. 8 is a graph showing the relationship between the incident angle θi and the transmittance of the sound wave. The transmittance was almost constant at about 70% even when the incident angle θi was changed. If the semiconductor wafer 22 has a critical angle of ultrasonic vibration,
The incidence angle θi at which the reflectance increases sharply and the transmittance sharply decreases occurs, but the fact that such an incidence angle θi is not measured means that there is no critical angle in the numerical experiment based on FIG. it is conceivable that.

As a result of considering this point, the following conclusions could be obtained. That is, in this experiment, the thickness of the semiconductor wafer 22 is 0.65 mm, which is less than one-fourth of the ultrasonic wavelength λ of 6.38 mm. When the thickness of the semiconductor wafer 22 is equal to or less than の of the wavelength λ, the antinode portion having the highest vibration energy is not located inside the semiconductor wafer 22 in the thickness direction, but located outside. .

As a result, since the energy of the ultrasonic vibration is easily transmitted in the thickness direction of the semiconductor wafer 22, it is considered that there is no critical angle at which the ultrasonic vibration is totally reflected on the incident surface of the semiconductor wafer 22.

If there is no critical angle, the semiconductor wafer 2
At least a part of the sound wave incident on the semiconductor wafer 22 is always transmitted regardless of the incident angle, that is, the arrangement angle of the ultrasonic nozzle body 25, so that not only the other surface of the semiconductor wafer 22 but also one surface Can be cleaned by vibration. That is, it is considered that the critical angle can be prevented from being generated by setting the frequency of the ultrasonic vibration according to the thickness of the semiconductor wafer 22.

On the other hand, when the angle of the ultrasonic nozzle body 25 is set to be almost perpendicular to the plate surface of the semiconductor wafer 22, the ultrasonic waves reflected on the plate surface of the semiconductor wafer 22 emit the ultrasonic waves reflected from the nozzle holes 25 a of the ultrasonic nozzle body 25. And the ultrasonic vibration applied to the first cleaning liquid L1 by the ultrasonic vibrator may be attenuated, or the ultrasonic vibrator may be damaged.

Therefore, it is desirable that the angle at which the ultrasonic nozzle body 25 is arranged is such that the ultrasonic vibration reflected by the semiconductor wafer 22 does not enter the nozzle hole 25a.
When the distance L between the tip of the ultrasonic nozzle body 25 and the plate surface of the semiconductor wafer 22 is 20 mm, and the inner diameter of the nozzle hole 25a is 4 mm, the arrangement angle is set to 5 degrees or more.
It was confirmed that the sound wave reflected by No. 2 did not enter the nozzle hole 25a. The upper limit of the arrangement angle is limited by the shape of the ultrasonic nozzle body 25.

If the inclination angle of the ultrasonic nozzle body 25 is increased, the incidence of reflected waves can be reliably prevented. However,
When the inclination angle of the ultrasonic nozzle body 25 is increased, the irradiation sound pressure V obtained from the above equation (3) is reduced, and the cleaning effect is reduced. Therefore, it is required that the arrangement angle of the ultrasonic nozzle body 25 be set to an angle that can prevent the reflected wave from being incident on the nozzle hole 25a without significantly reducing the cleaning effect.

The present invention is not limited to the above embodiments, but can be variously modified without departing from the gist of the invention. For example, in each of the above embodiments, one surface of the semiconductor wafer on which the circuit pattern is formed is on the lower side, and the other surface on which the circuit pattern is not formed is on the upper side. May be set to the upper side, in which case the ultrasonic nozzle body may be arranged on the lower side of the semiconductor wafer.

As a method for simultaneously cleaning both surfaces of the semiconductor wafer, a cleaning liquid having ultrasonic vibration applied to both surfaces may be jetted. In that case, the ultrasonic vibration applied to the cleaning liquid sprayed on one surface on which the circuit pattern is formed is made weaker than the ultrasonic vibration applied to the cleaning liquid sprayed on the other surface, Cleaning can be performed without damaging the circuit pattern. in this case,
By displacing the positions of the cleaning liquid jetted on one surface and the other surface of the semiconductor wafer, it is possible to prevent the ultrasonic vibrations applied to each other from interfering with each other.

[0073]

According to the first aspect of the present invention, the first cleaning liquid to which the ultrasonic vibration has been applied is sprayed on the other surface of the semiconductor wafer on which the circuit pattern is not formed, thereby providing the other surface. The surface can be cleaned by applying ultrasonic vibration of a predetermined intensity to the surface, and a part of the ultrasonic vibration is attenuated from the other surface to the one surface and transmitted.

Since the attenuated ultrasonic vibration acts on the second cleaning liquid jetted to one surface, a circuit pattern is formed by the second cleaning liquid to which the ultrasonic vibration weaker than the other surface is applied. One surface of the semiconductor wafer thus cleaned can be cleaned simultaneously with the other surface.

That is, not only can both surfaces of the semiconductor wafer be cleaned at the same time, but also ultrasonic vibrations of different intensities can be applied to one surface and the other surface without controlling and changing the intensity of the ultrasonic vibration. It can be washed with the applied washing liquid.

According to the third aspect of the present invention, the circuit pattern is formed on one surface and the other surface simultaneously while rotating the semiconductor wafer and without controlling the intensity of the ultrasonic vibration. Can be cleaned with a cleaning liquid to which weaker ultrasonic vibration is applied than the other surface on which no surface is formed.

According to the fifth aspect of the present invention, a circuit pattern is formed on one surface and the other surface simultaneously while transferring the semiconductor wafer in a predetermined direction, and without controlling the intensity of ultrasonic vibration. One of the surfaces thus formed can be cleaned with a cleaning liquid to which a weaker ultrasonic vibration has been applied than the other surface where no surface is formed.

According to the second, fourth and sixth aspects of the present invention, the ultrasonic vibration applied to the first cleaning liquid is incident on the other surface of the semiconductor wafer at an angle smaller than the critical angle. Thus, a part of the ultrasonic vibration incident on the other surface can be surely transmitted to one surface. As a result, since the ultrasonic vibration can be applied to the second cleaning liquid sprayed on one surface, the one surface can also be reliably cleaned.

According to the seventh aspect of the present invention, since the ultrasonic vibration applied to the cleaning liquid passes through the substrate, both surfaces of the substrate can be cleaned at the same time, and the ultrasonic vibration reflected by the substrate is transmitted by the ultrasonic wave. Since it does not enter the nozzle hole of the nozzle body,
It is possible to prevent the ultrasonic vibration reflected from the substrate from canceling the ultrasonic vibration applied to the cleaning liquid, thereby reducing the cleaning effect or damaging the ultrasonic nozzle body.

According to the eighth aspect of the invention, by setting the wavelength of the ultrasonic vibration according to the thickness of the substrate, it is possible to prevent the critical angle from being generated at the incident angle of the ultrasonic vibration incident on the substrate. Can be. Thereby, the arrangement angle of the ultrasonic nozzle body is not restricted, so that the degree of freedom of the arrangement of the ultrasonic nozzle body can be improved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing the overall configuration of a spin processing device according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of ultrasonic vibration incident from the other surface of the semiconductor wafer.

FIG. 3 is a graph showing the relationship between the cleaning method and the cleaning effect.

FIG. 4 is a schematic configuration diagram of an apparatus for cleaning a semiconductor wafer according to a second embodiment of the present invention.

FIG. 5 is an explanatory diagram of a relationship between a semiconductor wafer and an ultrasonic nozzle body according to a third embodiment of the present invention.

FIG. 6 is a graph showing the relationship between the angle of incidence of ultrasonic waves on a semiconductor wafer and the sound pressure.

FIG. 7 is a graph showing a relationship between an incident angle of ultrasonic vibration to a semiconductor wafer and a reflectance.

FIG. 8 is a graph showing the relationship between the incident angle of ultrasonic vibration and the transmittance of the semiconductor wafer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 ... Rotating chuck (rotation driving body) 22 ... Semiconductor wafer 25, 25A ... Ultrasonic nozzle body 31 ... Cleaning liquid supply path 41 ... Slit nozzle body L1 ... First cleaning liquid L2 ... Second cleaning liquid P ... Circuit pattern

Claims (8)

[Claims] In a cleaning method for cleaning a substrate having a circuit pattern formed on one surface, the first cleaning liquid to which ultrasonic vibration has been applied is applied to the substrate. And at the same time, the second surface
A cleaning method of a substrate, characterized by injecting a cleaning liquid. 2. The method according to claim 1, wherein the ultrasonic vibration applied to the first cleaning liquid is incident on the substrate at an angle smaller than a critical angle. 3. A cleaning apparatus for cleaning said one surface and the other surface of a substrate having a circuit pattern formed on one surface, comprising: a rotary driving member for holding and rotating said substrate; First cleaning liquid supply means for injecting a first cleaning liquid to which ultrasonic vibration is applied toward the other surface of the substrate held by the rotary driver; and the substrate held by the rotary driver. And a second cleaning liquid supply means for injecting a second cleaning liquid toward one surface of the substrate. 4. The apparatus for cleaning a substrate according to claim 3, wherein the ultrasonic vibration applied to the first cleaning liquid is incident on the substrate at an angle smaller than a critical angle. 5. A cleaning apparatus for cleaning one side and the other side of a substrate having a circuit pattern formed on one side thereof, comprising: a transport unit for transporting the substrate along a predetermined direction; First cleaning liquid supply means for spraying a first cleaning liquid to which ultrasonic vibration is applied toward the other surface of the substrate conveyed by the conveyance means, and one of the substrates conveyed by the conveyance means A second cleaning liquid supply means for injecting a second cleaning liquid toward the surface of the substrate. 6. The apparatus for cleaning a substrate according to claim 5, wherein the ultrasonic vibration applied to the first cleaning liquid is incident on the substrate at an angle smaller than a critical angle. 7. A cleaning apparatus for cleaning a substrate by spraying a cleaning liquid to which ultrasonic vibration is applied from a nozzle hole of an ultrasonic nozzle body toward a substrate, wherein the ultrasonic nozzle body is applied to the cleaning liquid. A substrate cleaning device, wherein the ultrasonic vibration transmitted through the substrate and the sound wave reflected by the substrate are inclined at an angle that does not enter the nozzle hole. 8. A cleaning apparatus for jetting a cleaning liquid to which ultrasonic vibration has been applied from an ultrasonic nozzle body toward a substrate, and cleaning the substrate, wherein a wavelength of the ultrasonic vibration is determined with respect to a thickness of the substrate. An apparatus for cleaning a substrate, wherein the ultrasonic vibration incident on the substrate is set to a value that does not cause a critical angle.