JP4435580B2 - Pressurized water jetting apparatus and substrate cleaning apparatus using the same - Google Patents

Description

  The present invention relates to a pressurized water injection device for injecting a jet water flow of cleaning water onto the surface of a semiconductor substrate, a glass substrate for liquid crystal display, and the like, and a substrate cleaning device using the same, and particularly has a function of suppressing the generation of static electricity during cleaning. It is related with the apparatus provided.

  Conventionally, as a surface cleaning method for semiconductor substrates, glass substrates for liquid crystal displays, etc., a high-pressure water jet cleaning method is known in which a high-pressure jet water flow of ultrapure water is sprayed onto the substrate surface and cleaned by its impact force. . In this high-pressure water jet cleaning method, ultrapure water having a high specific resistance is used, so that static electricity is generated when a high-speed jet water flow contacts the atmosphere or the substrate surface. When the generated static electricity is accumulated on the substrate surface, problems such as fouling of fine dirt particles, fusing of a wiring pattern formed on the substrate surface, and electrostatic breakdown of the gate oxide film of the MOS device occur.

Conventional techniques for suppressing the generation of such static electricity include a method of reducing specific resistance by dissolving CO ₂ gas in ultrapure water (see, for example, Patent Document 1), and ionized gas generated by corona discharge. A method (for example, refer to Patent Documents 2 and 3) of neutralizing generated static electricity by conveying with an air current is known.
However, a method of dissolving the CO ₂ gas over many load running costs, dissolved CO ₂ gas may adversely affect the object to be cleaned by the pure water acidified. In addition, in the method of neutralizing the ionized gas generated by corona discharge, in addition to problems such as the attenuation of ions during the transfer, the adhesion of dust generated by the wear of the corona discharge electrode to the substrate surface, There is a problem that it is difficult to neutralize locally generated static electricity immediately after the occurrence.
JP 7-45569 A JP-A-55-162379 JP-A-11-97402

  The present invention has been made from such a background, and the subject thereof is a pressurized water jetting device having a function of suppressing generation of static electricity when performing substrate cleaning using a high-speed jet water flow, and a substrate cleaning device using the same. It is to provide.

In order to achieve the above object, the invention according to claim 1 is a pressurized water injection device that receives a supply of pressurized water and injects a high-speed jet water stream forward from the nozzle tip, wherein the nozzle is made of metal and grounded. while, characterized in that the front is marked pressurized high DC voltage between the ground an annular electrode surrounding the nozzle tip while located in front of the nozzle tip.
According to such a pressurized water jetting device, by selecting the polarity of the DC high voltage indicia pressure to the annular electrode can be charged any polarity charge to a jet water stream ejected from the nozzle tip.
Further, since the electrode surface approaches the object to be cleaned, an electric charge having a polarity opposite to the polarity of the annular electrode is easily induced on the surface of the water flow near the surface of the object to be cleaned. Therefore, there is an effect that generation of static electricity having the same polarity as that of the annular electrode is more effectively suppressed.

The invention described in Claim 2 is the pressurized water ejecting apparatus according to claim 1, the polarity of the static electricity generated the polarity of the DC high voltage indicia pressure to the annular electrode, the water side by injection of the water jet It is characterized by having the same polarity as.
With such a configuration, since the jet water flow ejected from the nozzle tip is ejected with a charge of the opposite polarity to the generated static electricity, the static electricity generated on the water flow side due to contact with the atmosphere is moderate. This is effective to reduce the generation of static electricity.

The invention according to claim 3 is characterized in that, in the pressurized water jetting apparatus according to claim 1 or 2 , the surface of the annular electrode is covered with an insulating resin so that the electrode surface is not exposed to the atmosphere. To do.
With such a configuration, the jet water stream ejected from the nozzle tip, it is possible to charge the opposite polarity of the charge and polarity of the DC high voltage marked addition to the annular electrode. Moreover, since the surface of the annular electrode is not exposed to the atmosphere, there is no concern that metal ions will dissolve in the cleaning water.

According to a fourth aspect of the present invention, in the pressurized water injection device according to any one of the first to third aspects, a high voltage generation circuit that generates a DC high voltage applied to the annular electrode is provided in the pressurized water injection device. It is characterized by being built near the annular electrode.
With such a configuration, there is no need to feed a DC high voltage of several kV to several tens of kV from a place away from the cable, and the safety is improved.

The invention according to claim 5 is a substrate cleaning apparatus for cleaning the substrate surface by spraying a jet water flow of cleaning water onto the surface of the substrate, and the jet water flow injection apparatus according to any one of claims 1 to 4 The pressurized water jetting apparatus according to claim 1 is used.
According to the substrate cleaning apparatus having such a configuration, the substrate can be cleaned in a state in which the generation of static electricity due to the jet of the high-speed jet water flow is suppressed.

According to a sixth aspect of the present invention, in the substrate cleaning apparatus according to the fifth aspect of the present invention, pure water in which CO2 gas is dissolved is used as the cleaning water.
If such pure water is used, the specific resistance of the washing water is reduced and the conductivity is increased, so that an effect of further suppressing the generation of static electricity is obtained.

Hereinafter, an example of a preferred embodiment of the present invention will be described with reference to the drawings. In addition, in each figure, the same code | symbol is attached | subjected to the same or equivalent part.
(First embodiment)
FIG. 1 is a longitudinal sectional view for explaining a first embodiment of a pressurized water jetting apparatus according to the present invention. This pressurized water jetting device 1 is a device whose main purpose is to jet cleaning water as a high-speed jet water flow onto the surface of a semiconductor substrate, a glass substrate for a liquid crystal display, etc., and to perform surface cleaning by the impact force generated at that time. This device can also be called a high-speed washing water spray gun.

  The pressurized water injection device 1 has a substantially cylindrical shape as a whole. The trunk portion 2 is formed in a cylindrical shape with an insulating resin. A cylindrical nozzle 3 is inserted and fixed in the hollow hole inside the cylinder from the rear end side. The nozzle 3 includes a cylindrical nozzle body 4 and a nozzle head 5 attached to the tip of the nozzle body 4. In the shaft core portion of the nozzle body 4, a hollow hole serving as the cleaning water flow path 6 is provided so as to penetrate between the front and rear end faces.

  A pressure washing water pipe 7 is attached to the rear end portion of the nozzle body 4 in communication with the washing water flow path 6 by a connection joint 8. Wash water pressurized by a pressure pump (not shown) is supplied to the wash water flow path 6 through the pressure wash water pipe 7 and the joint 8. The vicinity of the front end of the cleaning water channel 6 is tapered toward the front end, and the cleaning water increases in the flow rate to the channel 9 in the nozzle head 5 attached to the front end of the nozzle body 4. Supplied. An outlet orifice 10 is formed at the front end of the flow path 9 in the nozzle head 5, and the washing water is jetted forward from the outlet orifice 10 as a high-speed jet water flow. The nozzle body 4 and the nozzle head 5 are both made of metal and are electrically grounded.

  An annular electrode 11 is attached to the front end surface of the body portion 2 so as to surround the nozzle head 5 with the front surface opened. On the back side of the annular electrode 11, a high voltage generation circuit 12 molded in a substantially cylindrical shape is accommodated in a hole formed from the rear end surface of the nozzle body 4. The annular electrode 11 is fixed to the metal electrode 13 protruding from the front end of the molded high voltage generation circuit 12 by welding or the like. A connector 14 is attached to the rear end side of the high voltage generation circuit 12 and a power supply cable 15 is connected thereto.

  The high voltage is generated by the high frequency power supply circuit 16 and the high voltage generation circuit 12 shown in FIG. The high frequency power supply circuit 16 is installed at a location away from the pressurized water injection device 1. The high frequency power supply circuit 16 receives power from a commercial power supply, generates a high frequency voltage of several hundred Hz to several kHz in an internal high frequency generation circuit 17, and boosts and insulates the generated voltage with an output high frequency transformer 18 Output.

  The output high frequency voltage is supplied to the primary side of the step-up transformer 19 in the high voltage generation circuit 12 by the cable 15. The high frequency voltage boosted by the step-up transformer 19 is supplied to the voltage doubler rectifier circuit 20 connected to the secondary side. The voltage doubler rectifier circuit 20 is, for example, a Cockcroft-Walton type voltage doubler rectifier circuit, which rectifies the supplied high frequency voltage and simultaneously boosts it to generate a DC high voltage of several kV to several tens of kV. The generated DC high voltage is applied between the ground and the annular electrode 11 through the high resistance R. The step-up transformer 19, the voltage doubler rectifier circuit 20, and the high resistance R constituting the voltage doubler rectifier circuit 20 are integrally molded to ensure insulation.

  The polarity of the DC voltage applied to the annular electrode 11 can be made positive or negative by changing the direction of the diode in the voltage doubler rectifier circuit 20. Actually, a pressurized water injection device to which a positive high voltage is applied to the annular electrode 11 and a pressurized water injection device to which a negative high voltage is applied are prepared, and are selectively used depending on the application.

  Next, the operation of the pressurized water injection device 1 configured as described above will be described. Usually, ultrapure water is used as the washing water. The ultrapure water is pressurized by a pressure pump (not shown), passes through the pressurized washing water pipe 7 and the washing water flow path 6 in the nozzle 3, and becomes a high-speed jet water flow 40 from the outlet orifice 10 at the front end of the nozzle head 5. It is sprayed toward the object 22 to be cleaned placed in front.

  When this ultrapure water is jetted as a high-speed jet water stream 40, static electricity is generated in the ultrapure water. This static electricity is caused by contact between the ultra-pure water with high specific resistance and the atmosphere, contact between the ultra-pure water and the object to be cleaned such as a semiconductor wafer, spray electrification called the Leonard effect when the water flow breaks up and becomes splash, It may be caused by contact between pure water and the nozzle. The polarity of the generated static electricity differs depending on the type of the object to be cleaned, its conductivity, and other factors. In the case of semiconductor wafers, there are many reports that positive charges are charged.

As described in “Background Art”, the generated static electricity causes problems such as fusing of a wiring pattern and electrostatic breakdown of a gate oxide film of a MOS device in the case of a semiconductor wafer, for example. Therefore, a means for suppressing the generation of static electricity itself or neutralizing the generated static electricity is required.
In the pressurized water jetting apparatus 1 of the present embodiment, in order to suppress the generation of static electricity, a DC high voltage is applied to the annular electrode 11 attached so as to surround the periphery of the nozzle head 5. The polarity of the DC high voltage to be applied is the same as the polarity of static electricity generated on the water flow side when the electrode 11 is washed with only the jet water flow 40 without applying a voltage.

Here, the description will be made on the assumption that static electricity generated when washing is performed only with the jet water flow 40 without applying a voltage to the annular electrode 11 is positive. The polarity of the generated static electricity and the amount of charge can be examined using a Faraday gauge.
In this case, a positive DC high voltage is applied to the annular electrode 11 as shown in FIG. The nozzle head 5 is made of metal and grounded as described above. Therefore, when a positive DC high voltage is applied to the annular electrode 11, a strong electric field from the annular electrode 11 toward the nozzle head 5 is generated. This powerful electric field the surface of the nozzle head 5, the polarity sign pressurized with high DC voltage to the electrode 11 negative charges of opposite polarity is induced by electrostatic induction.

  When ultrapure water is jetted from the nozzle head 5 as a jet water stream 40 in such a state, the jetted ultrapure water generates a negative charge from the nozzle head 5 and jumps out in a state where the surface is negatively charged. . The negative charge charged on the surface of the ultrapure water is a positive charge generated on the ultrapure water side due to contact between the jet water stream 40 and the atmosphere, contact between the jet water stream 40 and the surface of the object 22 to be cleaned, or the like. It works to suppress the generation of static electricity. Furthermore, a part of the ultrapure water ejected by being charged negatively becomes droplets in a state of being negatively charged. An electrostatic force directed to the electrode 11 acts on the droplets, and part of the droplet reaches the electrode 11 to pass a current between the electrode 11 and the ground. However, most of them drift around the jet water flow and lower the conductivity in the vicinity thereof, so that the conductivity of the atmosphere is increased and the generation of static electricity is suppressed.

  As described above, in the pressurized water injection device 1 of the present embodiment, a DC high voltage having the same polarity as the static electricity generated in the jet water flow 40 of ultrapure water is applied to the annular electrode 11 attached so as to surround the periphery of the nozzle head 5. Then, a charge having the opposite polarity to the surface of the nozzle head 5, that is, a charge having a polarity opposite to the polarity of the generated static electricity is induced. Thereby, since the jet water stream 40 is jetted in a state of being charged with a charge having a polarity opposite to that of static electricity, the generated static electricity is neutralized, and the generation of static electricity is suppressed.

(Second Embodiment)
FIG. 3 is a longitudinal sectional view for explaining a second embodiment of the pressurized water jetting apparatus according to the present invention. The difference between the pressurized water injection device 1a of the present embodiment and the pressurized water injection device 1 of the first embodiment is that the annular electrode 11 attached so as to surround the periphery of the nozzle head 5 is positioned in front of the nozzle head 5. In other words, the front surface of the annular electrode 11 is attached so as to be closer to the object to be cleaned.

  In this way, a charge having a polarity opposite to the polarity of the annular electrode 11 is easily induced on the surface of the water flow near the surface of the object to be cleaned. Therefore, there is an effect that the generation of static electricity having the same polarity as that of the annular electrode 11 is more effectively suppressed.

(Third embodiment)
FIG. 4 is a longitudinal sectional view for explaining a third embodiment of the pressurized water jetting apparatus according to the present invention. The pressurized water injection device 1b of the present embodiment is different from the pressurized water injection devices 1 and 1a of the first and second embodiments in that the front surface of the annular electrode 11 is covered with an insulating resin 21, and the surface of the electrode 11 is in the atmosphere. The point is not to expose.

  The electric lines of force due to the electric field pass through the insulating resin 21 that is a dielectric and exit to the outside. Therefore, even if the surface of the electrode 11 is covered with the insulating resin 21, the electric lines of force emerging from the surface of the electrode 11 reach the surface of the nozzle head 5 or the surface of the jet water flow 40 of ultrapure water. A charge having the opposite polarity to the voltage applied to the electrode 11 is induced there by electrostatic induction. Therefore, the same effect as the case of the pressurized water injection device 1 of the first embodiment can be obtained by the pressurized water injection device 1b of the present embodiment.

(Fourth embodiment)
FIG. 5 is a diagram showing an embodiment of the substrate cleaning apparatus 23 using the pressurized water jetting apparatus described in the first to third embodiments. The object to be cleaned 22 is attached by vacuum suction onto a table 24 having a horizontal surface. The table 24 is horizontally rotated by a rotation motor 25 attached to the lower part. The pressurized water injection device 1 is attached downward to the cover 26 portion above the article 22 to be cleaned. The high frequency power supply circuit 16 is installed outside the cover 26, and the generated high frequency voltage is supplied to the pressurized water jetting apparatus 1 by a cable.

The pressure pump 27 is also installed outside the cover 26. The pressurizing pump 27 pressurizes the supplied ultrapure water and supplies it to the pressurized water injection device 1. As a result, ultrapure water is jetted from the nozzle head 5 at the tip of the pressurized water jetting device 1 toward the article to be cleaned 22 as a high-speed jet water stream 40. The surface of the article to be cleaned 22 is cleaned by the impact force of the jet water stream 40 that has been jetted.
At this time, a DC high voltage having the same polarity as the generated static electricity is applied to the annular electrode 11 attached around the nozzle head 5 of the pressurized water jetting apparatus 1. As a result, a charge having the opposite polarity is induced on the surface of the nozzle head 5. Since the jet water stream 40 is jetted in a state of being charged with the induced electric charge having the opposite polarity, the generated static electricity is neutralized and the generation of static electricity is suppressed.

As described above, according to the substrate cleaning apparatus 23 of the present embodiment, it is possible to perform substrate cleaning with the jet water stream 40 in a state where static electricity generation is suppressed.
In the present embodiment mounted in the object to be cleaned 22, the rotary table 24 is used as a moving mechanism, placed in the object to be cleaned 22, various forms can be considered as a moving mechanism, the substrate cleaning apparatus of the present invention 23 the mounting of the moving mechanism is not limited to the mechanism shown in FIG.

Further, in the pressurized water injection devices 1, 1a, 1b described in the first to third embodiments and the substrate cleaning device 23 described in the fourth embodiment, it has been described that ultrapure water is used as the cleaning water. However, pure water in which CO ₂ gas is slightly dissolved in this ultra pure water may be used. If the CO ₂ gas is slightly dissolved, the specific resistance of pure water is lowered, so that generation of static electricity is more effectively suppressed. In this embodiment, since a method of suppressing the generation of static electricity by applying a DC high voltage is adopted, the amount of CO ₂ gas to be dissolved is more than that of the method of suppressing the generation of static electricity only by the dissolved CO ₂ gas. The amount may be small.

In addition, when using the pressurized water injection apparatus 1, 1 a, 1 b for cleaning a substrate, pure water having a high specific resistance is generally used as the cleaning water, and the cleaning water supplied in this case is 1 MPa to 50 MPa. It is particularly effective to compress and inject at a pressure in the range.
Further, the pressurized water injection device 1, 1a, 1b is a low-pressure shower (injection) device of 1 Mpa or less, an ultrasonic cleaning device to which ultrasonic waves are added, and two fluids for atomizing supply water with the force of gas (air, nitrogen). It is also effective when applied to a cleaning device.

It is a longitudinal cross-sectional view of the pressurized water injection apparatus which concerns on 1st Embodiment. It is explanatory drawing of an effect | action of a pressurized water injection apparatus. It is a longitudinal cross-sectional view of the pressurized water injection apparatus which concerns on 2nd Embodiment. It is a longitudinal cross-sectional view of the pressurized water injection apparatus which concerns on 3rd Embodiment. It is a block diagram of the board | substrate cleaning apparatus which concerns on this invention.

Explanation of symbols

  In the drawings, 1, 1a, 1b are pressurized water injection devices, 2 is a barrel, 3 is a nozzle, 4 is a nozzle barrel, 5 is a nozzle head, 6 is a washing water flow path, 10 is an outlet orifice, 11 is an electrode (annular electrode) ), 12 is a high voltage generating circuit, 21 is an insulating resin, 22 is an object to be cleaned, 23 is a substrate cleaning device, and 40 is a jet water flow.

Claims (6)

A pressurized water injection device that receives a supply of pressurized water and injects a high-speed jet water stream forward from the nozzle tip, wherein the nozzle is made of metal and grounded, and the front surface is positioned forward from the nozzle tip. pressurized water jet apparatus characterized by indicia pressurized high DC voltage between the ground an annular electrode surrounding the tip. The polarity of the DC high voltage indicia pressure to the annular electrodes, pressurized water ejecting apparatus according to claim 1, characterized in that the same polarity as the polarity of the static electricity generated in the water flow side by injection of the water jets. 3. The pressurized water jetting apparatus according to claim 1, wherein the surface of the annular electrode is covered with an insulating resin so that the electrode surface is not exposed to the atmosphere . 4. The pressurized water jetting device according to claim 1, wherein a high voltage generating circuit for generating a DC high voltage applied to the annular electrode is built in the vicinity of the annular electrode in the pressurized water jetting device. A substrate cleaning apparatus for cleaning a substrate surface by spraying a jet water flow of cleaning water onto the surface of the substrate, wherein the pressurized water injection apparatus according to any one of claims 1 to 4 is used as the jet water flow injection apparatus. A substrate cleaning apparatus. 6. The substrate cleaning apparatus according to claim 5, wherein pure water in which CO2 gas is dissolved is used as the cleaning water .

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