JP2003031540A - Ultrasonic cleaning unit, ultrasonic cleaning apparatus and method, and manufacturing methods of semiconductor device and liquid crystal display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ultrasonic vibration unit that can perform pure ultrasonic cleaning without giving damages to the object to be cleaned, an ultrasonic cleaning apparatus, and an ultrasonic cleaning method. SOLUTION: There should be an ultrasonic diaphragm 26, where an ultrasonic vibrator 25 is bonded and fixed, an ultrasonic transmission plate 28 that is arranged opposite to the ultrasonic diaphragm 26, a liquid supply means for supplying liquid to space being held between the ultrasonic diaphragm 26 and ultrasonic transmission plate 28, and a liquid discharge means for discharging the liquid from the space.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to cleaning a semiconductor substrate such as a silicon wafer or a compound semiconductor wafer forming a semiconductor device or a glass substrate forming a liquid crystal display device by ultrasonic treatment. The present invention relates to a suitable ultrasonic vibration unit, ultrasonic cleaning device, ultrasonic cleaning method, semiconductor device manufacturing method to which these cleaning techniques are applied, and liquid crystal display device manufacturing method.

[0002]

2. Description of the Related Art In the manufacturing process of semiconductor substrates and glass substrates for liquid crystal display devices, it is necessary to wash and remove submicron-order particles and the like adhering to semiconductor substrates and glass substrates before and after various microfabrications. is there. Therefore, there is little damage to the object to be cleaned at 500 kHz.
An ultrasonic cleaning method of irradiating and cleaning with a cleaning liquid to which ultrasonic waves with a high frequency of up to 1.5 MHz are applied is used. In order to improve the cleaning efficiency in ultrasonic cleaning, raising the ultrasonic energy on the surface of the object to be cleaned leads to improved efficiency.
As described in JP-A-283183, the ultrasonic energy from the ultrasonic oscillation source is converged to increase the ultrasonic energy on the surface of the object to be cleaned. However, there is a limit to the increase in the output of the ultrasonic wave oscillation source, and the diaphragm has a limit to the life and reliability of the ultrasonic oscillator and also the adhesive agent for adhering these. Therefore, in order to increase the latter ultrasonic energy, a method of converging the ultrasonic output to increase its apparent output is adopted.

[0003]

As described above, conventionally, the ultrasonic energy was focused to give the ultrasonic energy to the surface of the object to be cleaned, but in recent years, the ultrasonic energy is formed on the substrate. With the progress of miniaturization of patterns such as wiring, damage has been caused even by high-frequency ultrasonic waves, which were conventionally considered to be less damaged. As a result of a detailed investigation of the principle of this damage occurrence, the applicant converged the ultrasonic wave oscillated from the ultrasonic oscillator at a certain point, and at that point energy was generated enough to damage the wiring or affect the crystal. I found out that In other words, the cause was the convergence / synthesis of ultrasonic vibrations for increasing ultrasonic energy, which has been conventionally performed. The present invention has been made in view of the above circumstances, and an ultrasonic vibration unit, an ultrasonic cleaning device, an ultrasonic cleaning method, and a semiconductor device capable of performing a clean ultrasonic cleaning without damaging an object to be cleaned. And a method for manufacturing a liquid crystal display device.

[0004]

An ultrasonic cleaning unit according to the present invention comprises an ultrasonic vibrator, a diffusing means for diffusing the ultrasonic vibration oscillated by the ultrasonic vibrator, and a cooling for cooling the diffusing means. And means. In the present invention, the diffusing means has an ultrasonic vibrating plate to which an ultrasonic transducer is fixed, and an ultrasonic transmitting plate arranged to face the ultrasonic vibrating plate, and the cooling means is an ultrasonic vibrating plate. A liquid supply means for supplying a liquid to the space sandwiched between the plate and the ultrasonic transmission plate,
Liquid discharge means for discharging liquid from the space. Further, the ultrasonic transmission plate is allowed to have a function of diffusing the ultrasonic vibration propagated from the ultrasonic vibration plate through the liquid filling the space. Further, the ultrasonic wave transmission plate allows the ultrasonic wave vibration plate disposed opposite to the ultrasonic wave transmission plate to have a convex shape. Further, the cooling means allows the ultrasonic transducer to be annularly arranged around the transducer. Further, the ultrasonic transmission plate is allowed to have a curved convex shape on the side opposite to the ultrasonic vibration plates arranged to face each other. Further, the ultrasonic transmission plates allow the ultrasonic vibration plates to be arranged at a predetermined angle with respect to the ultrasonic vibration plates arranged to face each other.

Further, the ultrasonic cleaning apparatus of the present invention has a holding means for holding the object to be cleaned, and an ultrasonic cleaning unit provided so as to be movable relative to the surface to be cleaned of the object to be cleaned. In the ultrasonic cleaning device, the ultrasonic cleaning unit diffuses ultrasonic vibrations from an ultrasonic vibrator whose one surface has an ultrasonic vibrator fixed and the other surface which faces the object to be cleaned. It is characterized in that it has a diffusing means and a cooling means for cooling the diffusing means, and has a cleaning liquid supply means for supplying a cleaning liquid to the surface to be cleaned. In the present invention,
The diffusing means includes an ultrasonic transmission plate whose one surface is arranged to face the object to be cleaned, and an ultrasonic transmission plate whose one surface is arranged to face the other surface of the ultrasonic transmission plate. The cooling means has an ultrasonic vibrating plate to which the vibrator is fixed, and the cooling means discharges the liquid from the space, and the liquid supplying means that supplies the liquid to the space sandwiched between the ultrasonic transmitting plate and the ultrasonic vibrating plate. And liquid discharge means for Further, the ultrasonic transmission plate allows the ultrasonic vibration propagated from the ultrasonic vibration plate through the liquid filling the space to be diffused and propagated to the object to be cleaned. Further, the ultrasonic transmission plate allows the one surface to have a convex shape. Also,
The cooling means is allowed to be annularly arranged around the ultrasonic transducer.

Furthermore, the ultrasonic wave transmission plate allows one surface to be disposed with a predetermined angle of inclination with respect to the surface to be cleaned. In the ultrasonic cleaning method of the present invention, an ultrasonic transducer is fixed to one surface of the surface of the object to be cleaned held by the holding means and the other surface is arranged to face the object to be cleaned. The ultrasonic cleaning unit having a diffusing means for diffusing the ultrasonic vibration from the ultrasonic transducer and a cooling means for cooling the diffusing means is relatively moved to one surface of the diffusing means and the surface to be cleaned. And a predetermined distance, and a step of supplying the cleaning liquid to the surface to be cleaned and filling the space between the surface to be cleaned and one surface of the diffusing means with the cleaning liquid, driving the ultrasonic vibrator, and diffusing. Ultrasonic wave that has propagated through the means is diffused and propagated to the surface to be cleaned to clean the surface to be cleaned. In addition, the ultrasonic transducer,
Allowing to drive the object to be cleaned so that it does not resonate,
Preferably, it is driven while repeating ON-OFF at predetermined intervals, or is driven so as to continuously oscillate a plurality of types of ultrasonic waves having different phases or amplitudes, or the wavelength is an integral multiple or It is allowed to drive a plurality of types of ultrasonic waves different from an integral number of wavelengths so as to continuously oscillate.

Further, the object to be cleaned is allowed to be a semiconductor substrate on which a pattern including a structure having a convex shape with a width of 0.2 μm or less is formed. Further, the object to be cleaned is a semiconductor substrate in which the metal wiring is exposed. Furthermore,
The object to be cleaned is a glass substrate for a liquid crystal display device in which Si or metal wiring is exposed. A method of manufacturing a semiconductor device according to the present invention comprises a step of forming a gate insulating film on a semiconductor substrate, a step of forming a gate conductor on the gate insulating film, a step of forming a gate cap on the gate conductor, and a gate cap. And a step of etching the gate conductor up to the gate insulating film according to the mask pattern, and a step of cleaning the surface by using the ultrasonic cleaning method. A method of manufacturing a liquid crystal device according to the present invention is a method of manufacturing a Si substrate on a glass substrate for a liquid crystal display device.
A step of sequentially forming an N film, a Si02 film, and an a-Si film,
a step of annealing the a-Si film with a laser to make it poly, a step of etching the polyized Si film to form poly-Si islands to serve as gates, and a surface of the surface using the ultrasonic cleaning method. And a step of washing.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of an ultrasonic cleaning unit and an ultrasonic cleaning apparatus using the same according to the present invention will be described below with reference to the drawings. 1 is a sectional view of a single-wafer spin cleaning type ultrasonic cleaning apparatus of the present invention, FIG. 2 is a partial perspective view of the ultrasonic cleaning unit, FIG. 3 is a sectional view of the ultrasonic cleaning unit, and FIG. 4 is an object to be cleaned. And FIG. 5 is a vertical sectional view showing the relationship between the ultrasonic cleaning unit and the ultrasonic cleaning unit. The ultrasonic cleaning device 10 supplies a cleaning liquid 13 to the object 11 to be cleaned, and a spin processing device 12 that holds an object 11 to be cleaned such as a semiconductor substrate such as a silicon wafer or a glass substrate for a liquid crystal display device. The ultrasonic cleaning unit 14 is configured to apply ultrasonic waves to the cleaning liquid 13 to clean the surface 11a to be cleaned of the object to be cleaned 11. In the figure, reference numeral 15 denotes a cylindrical cup body having a bottom, and a discharge port 16 for discharging the cleaning liquid 13 after the cleaning process is provided at the bottom of the cup body 15. In addition, above the cup body 15, the cleaning liquid 13 scattered from the body to be cleaned 11 is prevented from being reflected by the inner wall of the cup body 15 and splashing back to the body to be cleaned 11, and the cleaning liquid 13 is discharged from the outlet 1.
It is inclined toward the center side to guide it to the 6 side. A rotary shaft 18 connected to the shaft of the motor 17 penetrates through the lower portion of the cup body 15 at a substantially central position, and is rotatably supported by a bearing 19 provided on the cup body 15. A rotary stage 20 whose center of rotation is fixed to the rotary shaft 18 is fixed to the upper part of the rotary shaft 18. On the outer peripheral side of the rotary stage 20, a plurality of support pins 21 are annularly provided at equal intervals, and the support pins 21 support and fix the article to be cleaned 11. The rotary stage 20 and the plurality of support pins 21 constitute a holding means.

At a position facing the surface 11a to be cleaned of the object to be cleaned 11, at least an arrow A (a direction in which the object to be cleaned 11 is moved toward and away from) and a direction B (the surface 11 to be cleaned of the object to be cleaned 11).
An arm 22 is provided so as to be movable in a direction (parallel to a), and the ultrasonic cleaning unit 1 is provided at the tip thereof.
4 is attached. The ultrasonic cleaning unit 14
A nozzle body 23 for supplying the cleaning liquid 13 to the surface 11a to be cleaned of the object 11 to be cleaned and an ultrasonic wave applying means 2 for applying ultrasonic waves to the cleaning liquid 13 supplied on the surface 11a to be cleaned.
4 and. Although only one nozzle body 23 is shown in FIG. 1, it is preferable to provide a plurality of nozzle bodies 23 as shown in FIG. Specifically, when the object to be cleaned 11 rotates in the direction of arrow C, the cleaning liquid 13 is supplied to the upstream side of the object to be cleaned 11 facing the ultrasonic wave applying means 24 from now on. On the left side of the object 11, three nozzle bodies 23a, 23 are provided on the lower side of the ultrasonic wave applying means 24 in the figure.
b and 23c are provided, and on the right side of the object to be cleaned 11, three nozzle bodies 23 are similarly provided on the upper side of the ultrasonic wave applying means 24 in the figure.
d, 23e, and 23f are provided. With such a configuration, ultrasonic waves can be efficiently applied to the applied cleaning liquid 13, and the cleaning effect can be improved.

In this embodiment, since the object to be cleaned 11 is rotated, the nozzle body 23 is arranged as described above. However, the object to be cleaned 11 is conveyed in a straight direction such as a belt conveyor. In this case, the ultrasonic wave applying means 24 may be provided on the upstream side with respect to the conveyance direction of the article to be cleaned 11. The installation position of the nozzle body 23 is not limited to this embodiment, and may be provided at any position as long as a sufficient amount can be supplied to the surface of the object to be cleaned 11. Further, in the present embodiment, the nozzle body 23 is provided as a separate body from the ultrasonic wave applying means 24, but it may be provided integrally with the ultrasonic wave applying means 24, and the cleaning liquid 13 is transmitted by the ultrasonic wave described later. The configuration may be such that it is supplied to the object to be cleaned 11 along the surface of the plate 28. In addition, each of the nozzle bodies 23a to 2
Regarding the amount of the cleaning liquid 13 discharged from 3f, it is preferable that the discharge amount be different. Specifically, since the cleaning target 11 is rotating in the direction of arrow C, the cleaning target 11
The cleaning liquid 13 supplied to the center of the liquid flows in the outer peripheral direction by the centrifugal force. Therefore, the surface to be cleaned 1 of the object to be cleaned 11
In order to supply the cleaning liquid 13 to the surface 1a substantially uniformly, the nozzle body 23c located on the center side of the object to be cleaned 11,
The amount of the cleaning liquid 13 discharged from 23d is maximized, and the discharge amount is reduced in the order of the nozzle bodies 23b and 23e and the nozzle bodies 23a and 23f.

In the present embodiment, since the object to be cleaned 11 is rotated, the amount of cleaning liquid discharged from the nozzle bodies 23a to 23f is made different as described above, but the object to be cleaned 11 goes straight. In the case of being conveyed in one direction, the discharge amounts do not have to be different. The ultrasonic wave applying means 24 is, for example, as shown in detail in FIGS. 2 and 3, a lead titanate-based ultrasonic wave oscillator 25 and an ultrasonic wave oscillator 2.
5, an ultrasonic vibration plate 26 that transmits the vibration of the ultrasonic vibrator 25, and an ultrasonic wave transmission that forms a space 27 with the ultrasonic vibrator 25, which is provided at a position facing the ultrasonic vibration plate 26. It has an ultrasonic wave diffusing means composed of a plate 28. The ultrasonic oscillator 25 may be a piezoelectric element or a piezo element. The ultrasonic oscillator 25 has an oscillation frequency of 1 to 8 MHz and generates heat by vibrating. At this time, if the ultrasonic vibration plate 26 is in an unloaded state, the ultrasonic vibrator 25 may self-destruct due to its own vibration and heat generation. Furthermore, the heat generated causes the adhesive (for example, an epoxy-based thermosetting adhesive) that bonds the ultrasonic transducer 25 and the ultrasonic diaphragm 26 to a temperature higher than the heat-resistant temperature. As a result, a loss occurs in the transmission of ultrasonic vibration.

Therefore, in order to apply a load to the ultrasonic vibrating plate 26, the ultrasonic transmitting plate 28 and the ultrasonic transducer 2
As a cooling means for cooling the adhesive agent that bonds the ultrasonic wave plate 26 and the ultrasonic vibration plate 26, a cooling water supply port (liquid supply means) 29 for supplying cooling water (liquid) such as water into the space 27. , And a plurality of cooling water discharge ports (liquid discharge means) 30 for discharging the cooling water (liquid). Further, when performing ultrasonic cleaning, it has been confirmed that the cleaning effect is improved when the temperature of the cleaning liquid is high. However, when the ultrasonic vibration plate 26 to which the ultrasonic vibrator 25 is bonded is directly contacted with the high temperature cleaning liquid. However, since the durability of the adhesive that adheres these becomes extremely short, the cleaning liquid cannot be heated to a high temperature. However, since the ultrasonic wave is applied to the cleaning liquid in contact with the ultrasonic wave transmission plate 28 via the cooling water as described above, it is not necessary to consider the heat damage to the adhesive, and therefore the high temperature cleaning liquid is used. You can also In the figure, the cooling water supply port 29 and the cooling water discharge port 3
Although a plurality of 0s are provided, the number may be appropriately selected depending on the size of the ultrasonic cleaning unit 24. The cooling water supply port 29 and the cooling water discharge port 30 are connected to a cooling water supply source and a cooling water discharge means (not shown) through the inside of the arm 22.

An unillustrated RF power source, for example, is connected to the ultrasonic oscillator 25 via a power line 25a, and the oscillation of the ultrasonic vibration is controlled by controlling and driving this. . The ultrasonic vibration plate 26 is made of flat plate quartz, single crystal sapphire, SiC, alumina, SU.
It is composed of an S or Ta plate or the like. The ultrasonic transmission plate 28 is formed in a convex shape on the opposite side of the ultrasonic vibration plate 26, and the material thereof is the same as that of the ultrasonic vibration plate 26, such as quartz, single crystal sapphire, SiC, alumina, SUS, or T.
It is composed of a plate and the like. The ultrasonic transmission plate 28
Since it directly contacts the cleaning liquid 13, it is conceivable that the components contained in the ultrasonic transmission plate 28 may elute and contaminate the object to be cleaned 11 depending on the type of cleaning liquid. Therefore, it is necessary to appropriately select the material depending on the type of the cleaning liquid 13 used. As shown in FIG. 4, the length of the ultrasonic wave applying means 24 is slightly longer than the diameter of the object to be cleaned 11 (a silicon wafer is shown in the drawing). With such a configuration, the object to be cleaned 11 is
The entire surface can be washed once by rotating 0 degree. However, this length can be appropriately changed depending on the size of the object to be cleaned 11, and for example, in the case of the object to be cleaned 11 having a circular shape as shown in FIG. , Can be configured to be slightly larger than the radius to cover from the center of rotation to the outer circumference,
Furthermore, it is possible to make it small so as to apply ultrasonic vibration in a spot manner. Further, the object to be cleaned 11 is a rectangular substrate (for example, a glass substrate for a liquid crystal display device),
In the case where this is conveyed in a straight line direction, if it is configured to be slightly longer than its length in the width direction, the object to be cleaned passes under the ultrasonic wave applying means 24 and the entire surface can be cleaned. , Efficient. Area 2 indicated by the broken line in the figure
Reference numeral 8a denotes a portion where an ultrasonic wave transmission plate 28, which will be described later, and the object to be cleaned 11 are communicated with each other by the cleaning liquid 13.

The principle of cleaning in the ultrasonic cleaning apparatus 10 will be described with reference to FIG. 5 as well. The gap between the surface 11a to be cleaned of the object 11 to be cleaned and the ultrasonic transmission plate 28 of the ultrasonic wave applying means 24 is determined. 0.5 mm or more, for example 1 m
When the cleaning liquid 13 is supplied to this gap to a distance of about m, as shown in FIG. 5, the cleaning liquid 13 comes into contact with the ultrasonic wave transmission plate 28 side in a convex shape due to surface tension. On the other hand, the vibration by the ultrasonic transducer 25 reaches the ultrasonic transmission plate 28 from the ultrasonic vibration plate 26 via the cooling water filling the space 27. The ultrasonic waves that have reached the ultrasonic wave transmission plate 28 are diffused radially by the curved convex shape of the ultrasonic wave transmission plate 28 and are applied to the cleaning liquid 13. That is,
The ultrasonic waves diffused by the ultrasonic transmission plate 28 are washed by the cleaning liquid 1.
3 or the surface 11a to be cleaned does not converge, and an energy convergence point higher than the ultrasonic energy oscillated per unit area does not occur. Therefore, it is possible to prevent the structure having a convex shape such as wiring formed on the surface to be cleaned 11a and the crystal structure of the member exposed on the surface of the object to be cleaned 11 from being damaged. Ultrasonic cleaning device 1 as described above
A cleaning method using 0 will be described below. First, with the arm 22 retracted from the rotary stage 20, the object to be cleaned (for example, a silicon wafer) 11 is transferred to the rotary stage 20 by a support pin 21 provided in an annular shape and supported and fixed. During this time, the ultrasonic wave applying means 24 is moved to a cleaning means (not shown) provided outside the cup body 15, and the cleaning liquid 1
It is possible to clean the surface of the ultrasonic transmission plate 28 that is in contact with 3. Next, the arm 22 is rotated and driven to horizontally move the ultrasonic cleaning unit 14 onto the object 11 to be cleaned, and further, the surface of the object 11 to be cleaned and the ultrasonic transmission plate 2 of the ultrasonic wave applying means 24.
It is lowered until the most convex portion of 8 becomes a predetermined gap.

After arranging the object to be cleaned 11 and the ultrasonic wave applying means 24 in a predetermined relationship, the motor 17 is driven to rotate the object to be cleaned 11 in the direction of the arrow C, and the nozzle bodies 23a to 23a.
The cleaning liquid 13 is supplied to the cleaning surface 11a of the cleaning target 11 from 3f. A predetermined amount of cleaning liquid 1 on the surface to be cleaned 11a
3 is supplied, as shown in FIG.
8 and the surface 11a to be cleaned are filled with the cleaning liquid 13, and the surface 11a to be cleaned and the ultrasonic transmission plate 28 are connected by the cleaning liquid 13 in the region 28a. When the ultrasonic vibrator 25 is driven in this state, ultrasonic vibration is generated by the ultrasonic vibration plate 26, the cooling water filling the space 27, the ultrasonic transmission plate 28, and the cleaning liquid 13 through the surface to be cleaned of the object to be cleaned 11. Particles reaching the surface 11a and adhering to the surface 11a to be cleaned can be removed and cleaned. The cleaning liquid 13 after cleaning is scattered to the outer peripheral side by the centrifugal force due to the rotation of the object to be cleaned 11 and is discharged from the discharge port 16. Here, a method of driving the ultrasonic transducer 25 will be described. In recent years, the wiring formed on the surface of a substrate such as a silicon wafer is being miniaturized, and even ultrasonic waves in a band where damage has not been conventionally caused may be damaged.
Therefore, in the present embodiment, instead of continuously applying ultrasonic waves, ON-OFF is repeatedly emitted, or a plurality of types of ultrasonic waves having different phases, wavelengths, or amplitudes are used. The method of continuous irradiation is adopted. The details will be described below.

FIG. 6 is a diagram showing a waveform of an ultrasonic wave when the ultrasonic wave is applied while being repeatedly turned on and off. FIG. 6A shows a case where a carrier wave of 100 Hz is superposed on the ultrasonic wave for driving, FIG. 6B shows a case where it is superposed on a carrier wave of 200 Hz, and FIG. Indicate the case. In this way, ultrasonic waves are turned on-of
By repeating F, ultrasonic waves when turned on resonate the crystals that make up the wiring and the substrate, but when turned off after a predetermined time, the resonance subsides and resonance that damages the wiring and crystals is prevented. can do. In FIG. 7, instead of turning on and off the ultrasonic wave,
It is the figure which showed the waveform of the ultrasonic wave at the time of continuously irradiating several ultrasonic waves from which a phase, a wavelength, and an amplitude differ. Figure 7 (a)
Is a case where the phase is shifted 180 degrees during continuous irradiation,
The phase is shifted by 180 degrees for every 80 pulses. Figure 7
(B) is a case where the wavelength (pulse width) is changed during continuous irradiation, which is 1590 Hz / 80 pulses, 749 Hz / 4.
0 pulses are emitted alternately. However, at this time, if the wavelength to be changed is set to an integral multiple of the original wavelength or a wavelength of an integer, resonance will occur. Therefore, it is necessary to remove the wavelength. Further, FIG. 7C shows a case where the phase is kept unchanged during the irradiation of continuous irradiation and the amplitude (pulse output) is changed at regular intervals, and 30 W / 80 pulses and 5 W / 80 pulses are alternately irradiated. There is. Irradiation methods such as these are applied while switching the ultrasonic waves that cancel the resonance that occurs in the wiring or crystal, and damage is generated compared to the case where a constant ultrasonic wave is continuously applied. Can be reduced to 1/100. In the above description,
Although the case where two kinds of ultrasonic waves are applied while switching is explained respectively, it is also possible to apply three or more kinds of ultrasonic waves while switching, and a plurality of kinds of ultrasonic waves are overlapped to each other at a predetermined timing. A method of suppressing the resonance by switching the type of the ultrasonic wave every time is also possible.

Further, the ultrasonic transducer 25 and the ultrasonic diaphragm 2
6. The ultrasonic wave transmitting plate 28 and the adhesive agent that adheres the ultrasonic transducer 25 and the ultrasonic vibrating plate 26 deteriorate with time. Therefore, the sensor detects the ultrasonic state in the gap between the ultrasonic transmission plate 28 and the surface 11a to be cleaned, or the ultrasonic state in the space 27, and depending on the degree, an RF power source for driving the ultrasonic transducer 25. It can be used for feedback control to and to recognize when to replace each part. Next, a case where the ultrasonic cleaning method according to the present embodiment is applied to manufacture of an active area of a semiconductor device and a liquid crystal cell of a liquid crystal display device will be described. FIG. 8 is a diagram showing a process of forming an active area and a gate conductor in a process of manufacturing a semiconductor device. If the design rule is not so strict, damage to the wiring or the like will not be a serious problem, but it is known that the design rule becomes strict and damage to the wiring or the like is likely to occur at the 0.2 μm level. . First, a gate insulating film (gate oxide film) is formed on a semiconductor substrate made of, for example, a silicon wafer, and a gate conductor is formed on the gate insulating film. Then, for example, a SiN film forming a gate cap is formed on the gate conductor, and a resist film is formed on the SiN film. Next, the resist film is exposed and developed and patterned to form a mask, and then the SiN film is etched to form a gate cap (FIG. 8A). Next, after removing the resist used as the mask and cleaning the surface, the gate conductor is etched to the gate insulating film according to the mask pattern of the gate cap (FIG. 8B). Then, after cleaning the surface, spacers made of an oxide film are formed around the sidewalls of the gate (FIG. 8C) to complete, for example, the gate of the DRAM.

In the manufacturing process of the semiconductor device as described above, after the steps such as etching, it is necessary to clean the surface in order to form another layer in the subsequent steps. At that time, according to the present invention. The ultrasonic cleaning method is effective. This is because when the design rule becomes 0.2 μm level (0.7 μm level or less for metal wiring) and the aspect ratio (H / W in FIG. 8C) becomes 1 or more, the conventional ultrasonic wave is used. In the cleaning method, there is a high possibility that the wiring will collapse at the portion α in FIG. 8B or the portion β in FIG. 8C, resulting in a pattern defect, and in some cases, the yield rate is 50% or less. It is also possible that Here, by applying the ultrasonic cleaning method according to the present invention, damage to the wiring and the like can be reduced as much as possible, and the yield rate can approach 100%. Next, an application example in the step of forming a gate on a glass substrate which constitutes a liquid crystal cell in a liquid crystal display device of the poly-Si TFT system will be described. A liquid crystal display device has a larger processing area than a semiconductor device. In addition, it is desired to make the opening larger in order to improve the display capability. Therefore, it is necessary to increase the size of the pixel portion and reduce the size of the peripheral path portion such as the driver.

The basic process is to use SiN on a glass substrate.
After forming the film, the Si02 film, and further the a-Si film,
The surface of the Si film is washed. After that, the a-Si film is annealed by a laser to be poly, and a mask is formed.
The poly that becomes the gate by etching the poly-Si film
After forming the y-Si islands, the surface is washed. Then, after forming an insulating film and a metal film on the surface of the glass substrate including poly-Si islands, a resist is applied, exposed and developed to form a mask, and the metal film is etched to form a gate line. . In a manufacturing process of a liquid crystal display device, it is necessary to clean a large area in a short time as compared with a semiconductor device. Therefore, it is necessary to apply a large amount of power in ultrasonic cleaning. When the conventional ultrasonic cleaning method is applied, the number of damaged portions on the glass substrate is about 10 and is small in number. However, in the case of a liquid crystal display device, since there is no redundant circuit, one damaged portion is a fatal problem. Therefore, it has been experimentally confirmed that when the ultrasonic cleaning method of the present invention is applied, the number of damaged points is reduced to almost zero. As described above, when ultrasonic cleaning is performed using the ultrasonic cleaning apparatus according to the present embodiment, damage to the wiring or the like and a crystalline state of a substance forming the substrate or the like are compared to conventional ultrasonic cleaning methods. The damage given can be reduced as much as possible, and the yield in the manufacturing process of the semiconductor device or the liquid crystal display device can be significantly improved.

Next, a modification of the ultrasonic wave applying means in the above embodiment will be described. FIG. 9 shows a first modification of the ultrasonic wave applying means. The ultrasonic wave applying means 40 has a pair of supporting portions 41 a and 41 b, and these supporting portions 4
An ultrasonic vibrating plate 4 in which a part of the supporting portions 41a and 41b and an ultrasonic vibrator 42 are fixedly bonded between the portions 1a and 41b.
3, an ultrasonic transmission plate 4 having a plate-shaped member formed in a convex shape on one side
4, and a space 45 is formed by being surrounded by a pair of side plates (not shown). One support portion 41a is provided with a cooling water supply port 46a for introducing cooling water into the space 45 (a plurality of cooling water supply ports 46a may be provided in the longitudinal direction of the ultrasonic wave applying means 40). The portion 41b has a cooling water discharge port 46b (cooling water supply port 46b) for discharging the cooling water.
It is also possible to provide a plurality as in a). With the ultrasonic wave applying means 40 having such a structure, the manufacturing is facilitated, and the maintenance and the replacement of the members can be smoothly and easily performed by configuring each member separately. FIG. 10 shows a second modification of the ultrasonic wave applying means. The same components as those of the first modified example are designated by the same reference numerals and the description thereof will be omitted. The ultrasonic wave imparting means 50 has a pair of supporting portions 51a and 51b, and the ultrasonic transducer 42 is bonded and fixed between the supporting portions 51a and 51b and a part of the supporting portions 51a and 51b. A space 55 is formed by being surrounded by the ultrasonic vibration plate 43, the flat plate-shaped ultrasonic transmission plate 54, and a pair of side plates (not shown). In the present modification, the ultrasonic transmission plate 54 is formed in a flat plate shape, and the ultrasonic transmission plate 54 is connected to the ultrasonic vibration plate 4.
3 is different in that it is fixed with an angle to 3. By giving the angle in this way, the vibration generated from the ultrasonic transducer 42 is passed through the ultrasonic vibrating plate 43, the cooling water filled in the space 55, and the vibration transmitting plate 54 to be cleaned 11
When the ultrasonic vibration that has propagated to the ultrasonic wave is reflected by the non-cleaning body 11 and returns, its direction is changed by the ultrasonic wave transmission plate 54 and is reflected on the bonding portion with the ultrasonic wave oscillator 42 or the ultrasonic wave oscillator plate 43. Vibration can be prevented from damaging. It should be noted that the mounting angle of the ultrasonic transmission plate 54 may be tilted by about 2 to 20 degrees, preferably about 15 degrees, in view of the relationship between the transmission of the vibration from the ultrasonic vibration plate 43 and the reflected vibration.

FIG. 11 shows a third modification of the ultrasonic wave applying means. The same components as those in the above-described modified examples are designated by the same reference numerals, and description thereof will be omitted. The difference from the above modification is that
The point is that the ultrasonic wave transmission plate 64 is bent at approximately the center position of the support portions 62a and 62b. With such a structure, as in the case of the second modified example, the effect of reducing the damage of reflected vibration is obtained, and the cleaning liquid 13 is provided between the surface 11a to be cleaned of the object 11 to be cleaned and the ultrasonic wave transmission plate 64. It is possible to widen the portion that is satisfied by, and it is possible to improve the cleaning efficiency as compared with the second modification. FIG. 12 is a fourth modification of the ultrasonic wave applying means. The same components as those in the above-described modified examples are designated by the same reference numerals, and description thereof will be omitted. The ultrasonic transmission plate of this modification is different from the ultrasonic transmission plate 44 of the first modification. Ultrasonic transmission plate 7 in this modification
4 is characterized in that the surface facing the ultrasonic vibration plate 43 is formed in a flat shape, and the surface facing the object to be cleaned 11 has a convex shape. With such a configuration, the ultrasonic vibrations emitted from the ultrasonic transmission plate 74 are diffused more uniformly,
It is possible to make the energy on the surface to be cleaned 11a uniform and reduce the difference in cleaning processing capacity.

FIG. 13 shows a fifth modification of the ultrasonic wave applying means. The same components as those in the above-described modified examples are designated by the same reference numerals, and description thereof will be omitted. The ultrasonic transmission plate of this modification is different from the ultrasonic transmission plate 54 of the second modification. The ultrasonic transmission plate 84 in the present modification has a lens shape in which the surface facing the ultrasonic vibration plate 43 is formed in a flat shape and the surface facing the object to be cleaned 11 is formed in a convex shape. The feature is that. With such a configuration, in addition to the effect of the second modification, the ultrasonic vibrations emitted from the ultrasonic transmission plate 84 are more evenly diffused, and the energy on the surface to be cleaned 11a is made uniform. Thus, the difference in cleaning processing capacity can be reduced. 14A and 14B show a sixth modification of the ultrasonic wave applying means configured to irradiate ultrasonic waves in a spot manner. FIG. 14A is a vertical sectional view, and FIG. 14B is a sectional view taken along line AA in FIG. Is. Ultrasonic wave applying means 9
0 has a ring-shaped support portion 91, and one surface (the lower surface in the drawing) has a convex shape (a spherical surface in this modification) inside and the other surface is formed on a flat surface. It also has ultrasonic diffusing means 93. The ultrasonic wave diffusing means 93 is made of any one of quartz, sapphire, SiC, alumina, stainless steel, and Ta. The ultrasonic transducer 9 is provided at a substantially central position on the other surface of the ultrasonic diffusing means 93.
2 are bonded and fixed, and a heat conductive sheet 96 made of, for example, a fluorine resin is provided on the outer periphery thereof.
On the heat conducting sheet 96, the cooling water conducting passage 94 is internally provided.
A ring-shaped cooling means 94 in which a is formed is provided, and a cooling water supply port 95a for supplying cooling water and a cooling water discharge port 95b for discharging the cooling water are provided in the cooling water passage 94a.
Is provided. With the ultrasonic wave applying means 90 having such a configuration, the ultrasonic wave diffusing means 93 can be cooled, and the ultrasonic vibrator 92 can be cooled together with the adhesive through the ultrasonic wave diffusing means 93, and further, the manufacturing This facilitates maintenance and replacement of members smoothly and easily.

In the above-described embodiment and modification, the linear form as shown in FIGS. 1 to 13 and FIG.
Although the spot irradiation can be performed as shown in (1), the combination of these is free and can be appropriately adopted as needed, and the same effect can be obtained.

[0024]

According to the present invention, it is possible to minimize the damage to the object to be cleaned and to clean the surface of the object to be cleaned precisely.

[Brief description of drawings]

FIG. 1 is a sectional view of a single-wafer spin cleaning type ultrasonic cleaning apparatus of the present invention.

FIG. 2 is a partial perspective view of an ultrasonic cleaning unit.

FIG. 3 is a sectional view of the ultrasonic cleaning unit.

FIG. 4 is a plan view showing the relationship between the object to be cleaned and the ultrasonic cleaning unit.

FIG. 5 is a vertical cross-sectional view showing the relationship between the object to be cleaned and the ultrasonic cleaning unit.

FIG. 6 is a diagram showing a waveform of an ultrasonic wave when the ultrasonic wave is repeatedly emitted while being turned on and off.

7A is a diagram showing a waveform of an ultrasonic wave when a phase is shifted by 180 degrees during irradiation of continuous irradiation, and FIG. 7B is a case where a wavelength (pulse width) is changed during irradiation of continuous irradiation. Showing the waveform of the ultrasonic wave, and FIG. 7C shows the waveform of the ultrasonic wave when the amplitude (pulse output) is changed during irradiation of continuous irradiation.

FIG. 8 is a process diagram showing a process of forming an active area and a gate conductor in a process of manufacturing a semiconductor device.

FIG. 9 is a diagram showing a first modification of the ultrasonic wave applying means.

FIG. 10 is a diagram showing a second modification of the ultrasonic wave applying means.

FIG. 11 is a diagram showing a third modification of the ultrasonic wave applying means.

FIG. 12 is a diagram showing a fourth modification of the ultrasonic wave applying means.

FIG. 13 is a diagram showing a fifth modification of the ultrasonic wave applying means.

14A is a diagram showing a sixth modification of the ultrasonic wave applying means, and FIG. 14B is a sectional view taken along the line AA of FIG. 14A.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Ultrasonic cleaning device, 11 ... Cleaning object, 12 ... Spin processing device, 13 ... Cleaning liquid, 14 ... Ultrasonic cleaning unit,
23, 23a to 23f ... Nozzle, 24 ... Ultrasonic wave imparting means, 25 ... Ultrasonic vibrator, 26 ... Ultrasonic vibrating plate, 27 ...
Space, 28 ... Ultrasonic transmission plate, 29 ... Cooling water supply port, 30
… Cooling water outlet

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G02F 1/13 101 G02F 1/13 101 1/1333 500 1/1333 500 F term (reference) 2H088 FA18 FA21 MA20 2H090 JB02 JB04 JC19 3B201 AA01 AB33 AB47 BB21 BB82 BB83 BB92 4G059 AA01 AB19 AC21 AC24

Claims (13)

[Claims] 1. An ultrasonic cleaning unit comprising: an ultrasonic vibrator, a diffusing means for diffusing the ultrasonic vibration oscillated by the ultrasonic vibrator, and a cooling means for cooling the diffusing means. 2. The diffusion means includes an ultrasonic vibration plate to which an ultrasonic vibrator is fixed, and an ultrasonic transmission plate arranged to face the ultrasonic vibration plate, and the cooling means includes: A liquid supply means for supplying a liquid to a space sandwiched between the ultrasonic vibration plate and the ultrasonic transmission plate, and a liquid discharge means for discharging the liquid from the space. 1. The ultrasonic cleaning unit according to 1. 3. The ultrasonic wave transmitting plate according to claim 2, wherein the ultrasonic wave transmitting plate has a function of diffusing the ultrasonic wave vibrations propagated from the ultrasonic wave vibrating plate through the liquid filling the space. Sonic cleaning unit. 4. An ultrasonic cleaning apparatus, comprising: a holding unit for holding an object to be cleaned; and an ultrasonic cleaning unit provided so as to be movable relative to a surface to be cleaned of the object to be cleaned, The ultrasonic cleaning unit includes a diffusing means for diffusing ultrasonic vibration from the ultrasonic vibrator, the ultrasonic vibrator being fixed to one surface and the other surface facing the object to be cleaned, and the diffusing means. An ultrasonic cleaning apparatus comprising: a cooling unit configured to cool the unit; and a cleaning liquid supply unit that supplies a cleaning liquid to the surface to be cleaned. 5. The diffusing means is arranged such that one surface thereof faces an object to be cleaned and the ultrasonic wave transmitting plate is arranged, and one surface of the diffusing means is arranged so as to face another surface of the ultrasonic wave transmitting plate. An ultrasonic vibrating plate having an ultrasonic transducer fixed to the other surface thereof, wherein the cooling means supplies a liquid to a space sandwiched between the ultrasonic transmitting plate and the ultrasonic vibrating plate. The ultrasonic cleaning apparatus according to claim 4, further comprising: means and a liquid discharge means for discharging the liquid from the space. 6. The ultrasonic transmission plate has a function of diffusing and propagating ultrasonic vibration propagated from the ultrasonic vibration plate through a liquid filling the space to the object to be cleaned. The ultrasonic cleaning device according to claim 5, wherein 7. The ultrasonic wave, wherein an ultrasonic transducer is fixed to one surface of the surface of the object to be cleaned held by the holding means and the other surface of the ultrasonic wave is arranged to face the object to be cleaned. An ultrasonic cleaning unit having a diffusing means for diffusing ultrasonic vibrations from the vibrator and a cooling means for cooling the diffusing means is moved relatively to one surface of the diffusing means and the surface to be cleaned. And a step of supplying a cleaning liquid to the surface to be cleaned and filling the space between the surface to be cleaned and one surface of the diffusing means with the cleaning liquid, the ultrasonic transducer A step of driving, diffusing the ultrasonic vibration propagating through the diffusing means, propagating to the surface to be cleaned, and cleaning the surface to be cleaned, the ultrasonic cleaning method. 8. The ultrasonic cleaning method according to claim 7, wherein the ultrasonic vibrator is driven so as not to resonate the object to be cleaned. 9. The ultrasonic transducer is turned on at predetermined intervals.
The ultrasonic cleaning method according to claim 7, wherein the ultrasonic cleaning method is performed while repeating -OFF. 10. The ultrasonic transducer is driven so as to continuously oscillate a plurality of types of ultrasonic waves having different phases or amplitudes.
The ultrasonic cleaning method according to any one of 1. 11. The ultrasonic transducer is driven so as to continuously oscillate a plurality of types of ultrasonic waves whose wavelengths are different from each other by an integral multiple or an integral number of wavelengths. The ultrasonic cleaning method according to any one of 1. 12. A step of forming a gate insulating film on a semiconductor substrate, a step of forming a gate conductor on the gate insulating film, a step of forming a gate cap on the gate conductor, and a mask of the gate cap. 12. A semiconductor comprising: a step of etching the gate conductor to the gate insulating film according to a pattern; and a step of cleaning the surface by using the ultrasonic cleaning method according to claim 7. Device manufacturing method. 13. Si on a glass substrate for a liquid crystal display device.
A step of sequentially forming an N film, a Si02 film, and an a-Si film; a step of annealing the a-Si film with a laser to make it poly, and a step of etching the poly Si film to form a gate p
A method for manufacturing a liquid crystal display device, comprising: a step of forming an oli-Si island; and a step of cleaning the surface by using the ultrasonic cleaning method according to claim 7. .