Nozzle for injecting sublimable solid particles entrained in gas for cleaning a surface

Disclosed is a nozzle for injecting sublimable solid particles, which is capable of minimizing consumption of the carrier gas and also maximizing cleaning efficiency. The nozzle comprises a base block having a space in which carrier gas is supplied through a gas supplying pipe; a sub-block having a space in which cleaning medium decompressed by a regulator is supplied through a cleaning medium supplying pipe; a first venturi block having a venturi path for adiabatically expanding the carrier gas supplied from the space of the base block, and a cleaning medium injection path communicating the venturi path and the space of the sub-block and the carrier gas passed through the venturi path; and a second venturi block having a venturi path for adiabatically expanding the mixed gas of the carrier gas and the cleaning medium.

TECHNICAL FIELD

The present invention relates to a nozzle for injecting sublimable solid particles such as Co2snow, Ar snow, etc., to clean a surface of a wafer or FPD (Flat Panel Display) and the like.

BACKGROUND ART

In order to clean pollutants such as fine particles on a surface of a wafer, an LCD, a color filter or various glass substrates, there has been proposed various techniques. Particularly, in the semiconductor industry, high-pressure liquid is used independently or used in a state of being combined with brushes to remove the polluted fine particles from a surface of a semiconductor wafer. These processes achieved partial success in removing the pollutant. However, the brushes scratch the surface of the substrate, and also it may generate undesirable static electricity. And, the high-pressure liquid is apt to cut the soft surface of the substrate. Further, the high-pressure liquid has a drawback that it is not easy to withdraw the liquid from the brushes and high-pressure liquid cleaning system.

Meanwhile, it is well known that solid and gas phase carbon dioxide (CO2snow) can remove the polluted fine particles from the surface of the substrate without the above-mentioned drawback. One of the techniques is disclosed in U.S. Pat. No. 5,125,979.

In the above mentioned technique, there are provided a small expansion chamber and a large expansion chamber which are communicated with each other through a venturi interposed therebetween. At an outlet of the large expansion chamber is provided an accelerating chamber for accelerating an injecting speed of a cleaning medium. The cleaning medium is supplied from a cleaning medium supplying source to the small expansion chamber, and then adiabatically expanded while being supplied through the venturi to the large expansion chamber, thereby forming Co2snow having snow particles of about 46%. The Co2snow is accelerated by inert gas introduced to the accelerating chamber, and then injected through a nozzle to a desired position in which the cleaning process is performed.

That is, in the technique, the cleaning medium is transformed into the Co2snow, while passing through the venturi. Then, the particles of the Co2snow grow, while the Co2snow passes through the large expansion chamber. The cleaning medium injected through the nozzle cleans the pollutant on the surface of the substrate and then sublimed.

However, in the technique, since the cleaning medium of Co2is transformed into the Co2snow, while passing through one venturi, a solidification rate of the cleaning medium is low. Furthermore, since the cleaning process is typically performed at a high presser, there is a problem that a large quantity of cleaning medium is needed to remove the polluted fine particles under the same conditions.

To solve the problem, the applicant had proposed Korean Patent application No. 2000-8560 filed on Feb. 22, 2000, entitled “Nozzle for cleaning components of semiconductor fabricating equipment”.

As shown inFIGS. 1 to 3, the nozzle for cleaning components of a semiconductor fabricating equipment has first and second venturi blocks51and53, which are disposed in series, to provide a wider cleaning surface than a single nozzle, thereby maximizing the cleaning efficiency. A carrier gas supplying pipe61is connected to a base block55in which the first venturi block51is disposed. A cleaning medium supplying pipe59is connected to a sub-block57disposed at an upper side of the base block55.

The cleaning medium supplying pipe59is connected to a cleaning medium chamber13bin which high-pressure Co2is stored in liquid phase. The cleaning medium supplying pipe59is controlled by a regulator11to have a lower pressure of 100˜120 psi. Since the cleaning medium of Co2is reduced from the high pressure to the low pressure, the particles of snow state are formed in the cleaning medium. The cleaning medium controlled to have the above-mentioned pressure is supplied through the cleaning medium supplying pipe59and the sub-block57to a fan-shaped space51aformed in the base block55.

The carrier gas supplying pipe61is connected to a carrier gas chamber13ato supply carrier gas such as N2to the base block55. The carrier gas is stored in the carrier gas chamber13aat a high pressure. As shown inFIG. 2, at an distal end of the carrier gas supplying pipe61, there is formed a slot61afor uniformly injecting the carrier gas into a plurality of venturi paths formed at the first venturi block51. At the sub-block57, there is formed a path57aperpendicular to the fan-shaped space51ato be communicated with the space51a. The cleaning medium supplying pipe59has a circular portion on which the cleaning medium is dashed, so that the cleaning medium is uniformly injected into the fan-shaped space51a.

Accordingly, the cleaning medium supplied through the cleaning medium supplying pipe59to the space51aof the base block55is mixed with the carrier gas injected from the carrier gas supplying pipe61in the space51aso as to firstly induce the solidification of the cleaning medium. The mixed gas is adiabatically expanded, while passing through the venturi paths formed in the first venturi block51, whereby a temperature and a pressure of the mixed gas are sharply reduced. Since the cleaning medium is adiabatically expanded in the first venturi block51, the solidification of the cleaning medium is further promoted. Further, the cleaning medium is adiabatically expanded again, while passing through the second venturi block53, and thus, the solidification of the cleaning medium is promoted once more. However, the conventional technique as described above has a structure that the cleaning medium supplying path is perpendicular to the carrier gas supplying path at a place where the cleaning medium and the carrier gas is mixed. Therefore, since the carrier gas having the higher pressure than the cleaning medium is flowed back to the cleaning medium supplying path, there is a problem that the cleaning medium supplying path is clogged. Furthermore, since the carrier gas is supplied at the high pressure, there is another problem that the consumption of the carrier gas is increased.

DISCLOSURE OF THE INVENTION

Therefore, an object of the present invention is to provide a nozzle for injecting sublimable solid particles, which is capable of preventing the clogging of the cleaning medium supplying path due to backflow of carrier gas, and also minimizing consumption of the carrier gas.

Another object of the present invention is to provide a nozzle for injecting sublimable solid particles, in which a desired staying space for carrier gas and cleaning medium is secured at a place that the carrier gas and the cleaning medium are mixed, thereby uniformly mixing the carrier gas and the cleaning medium, and which stabilizes growth of particles and flow of the carrier gas and the cleaning medium to maximize solidification of the cleaning medium, thereby improving cleaning efficiency.

The present invention provides nozzle for injecting sublimable solid particles entrained in gas for cleaning a surface, comprising a base block having a space in which carrier gas is supplied through a gas supplying pipe; a sub-block having a space in which cleaning medium decompressed by a regulator is supplied through a cleaning medium supplying pipe; a first venturi block having a venturi path for adiabatically expanding the carrier gas supplied from the space of the base block, and a cleaning medium injection path communicating the venturi path and the space of the sub-block to mix the cleaning medium of the sub-block and the carrier gas passed through the venturi path; and a second venturi block having a venturi path for adiabatically expanding the mixed gas of the carrier gas and the cleaning medium, wherein the venturi path of the first venturi block has an acute angle with respect to the cleaning medium injection path.

The nozzle of the present invention comprises an intermediate block having a path, which is disposed between the first and second venturi blocks, for promoting the mixture of the carrier gas and the cleaning medium in the mixed gas moving from the path of the first venturi block to the path of the second venturi block and thus inducing growth of snow particles.

Herein, the first and second venturi blocks respectively have a plurality of venturi paths disposed in parallel, and the sub-block has the same number of cleaning medium injection paths as the number of venturi paths.

Further, the venturi path of the first venturi block has an angle of 15 to 60° with respect to the cleaning medium injection path. Therefore, it is prevented that the carrier gas is flowed back to the cleaning medium injection path. More preferably, the injection hole in which the cleaning medium decompressed by the regulator is mixed with the carrier gas has a diameter of 0.1 to 0.3 mm. Therefore, since the pressure of the cleaning medium injected through the injection path is higher than that of the carrier gas, it is efficiently prevented that the carrier gas is flowed back.

the carrier gas supplying pipe has a slit at an end thereof so that the carrier gas is injected at a desired angle range when supplied to the space of the base block. The carrier gas injected through the slit has an angle of 116°.

further, the cleaning medium supplied to the first venturi path has a pressure of 10 to 50 psi, and the carrier gas supplied to the space of the base block has a pressure of 60 to 100 psi.

The cleaning medium is Co2+or Ar+, and the carrier gas is N2gas or clean dry air.

BEST MODE FOR CARRYING OUT THE INVENTION

The present invention will now be described in further detail with reference to the drawings.

As shown inFIGS. 4 and 5, a nozzle according to the present invention includes a base block1, a sub-block2, a first venturi block3and a second venturi block4. A intermediate block5may be disposed between the first and second venturi blocks3and4. The intermediate block5has a mixing space for assuring mixture of cleaning medium and carrier gas and stabilizing flow of the cleaning medium and carrier gas.

The base block1is connected through a carrier gas supplying pipe12to a carrier gas chamber13ain which carrier gas such as N2gas or clean dryd air. The carrier gas supplied to the base block1typically has a pressure of 60 to 100 psi. The carrier gas supplying pipe12has a nozzle body7at an end thereof. As shown inFIG. 5, the nozzle body7is disposed at the base block1so as to inject the carrier gas into a space6formed in the base block1. The nozzle body-7is formed with a slit7afor injecting the carrier gas at an injecting angle a of about 116° into the space of the base block1. As shown inFIG. 6, the space6formed in the base block1is formed into a sector having an angle of 116°.

The sub-block2is positioned at an upper side of the base block1to be connected to the first venturi block3. The sub-block2is connected through a cleaning medium supplying pipe14to a Co2cleaning medium chamber13bin which cleaning medium for generating solidifying particles like Co2particles. When the cleaning medium is injected through a nozzle body9, which is disposed at an end of the cleaning medium supplying pipe14, to an injection space10, the cleaning medium is firstly decompressed to a pressure of about 10 to 50 psi by a regulator11or other valve means disposed at the cleaning medium supplying pipe14and then injected into the injection space10of the sub-block2in a liquid C02state.

Meanwhile, a cryogenic heat exchanger (not shown) is disposed between the cleaning medium chamber13band the regulator11. Therefore, the cleaning medium of Co2gas is transformed into liquid Co2due to temperature drop while passing through the cryogenic heat exchanger, and transformed again into liquid Co2having a lower pressure while passing through the regulator11, and then introduced into the sub-block2. Solidified particles like Co2particles is generated at a place where the cleaning medium is mixed with the carrier gas.

As shown inFIGS. 5 and 7, the injection space10of the sub-block2is formed into the sector, and disposed to be perpendicular to the nozzle body9. The nozzle body9is positioned at an upper side of the space10. The nozzle body9has an arc-shaped distribution surface9aat an end thereof so that the cleaning medium injected through a nozzle hole9bof the nozzle body9is injected into a lower portion of the injection space10. Therefore, the cleaning medium injected from the nozzle body9is dashed on the distribution surface9a, and thus injected at an angle of about 146° into the lower portion of the injection space10. In order to obtain such injection angle of the cleaning medium, the distribution surface9ahas an angle of about 75° with respect to the distribution surface9a.

As shown in drawing, the first venturi block3is connected to the base block1and the sub-block2. The first venturi block3has multiple, preferably, 10 or more venturi paths15disposed in parallel and multiple cleaning medium injection paths16for connecting each throttle portion of the venturi path15to the injection space10of the sub-block2, such that the cleaning medium injection paths16are adjacent to the throttle portion of the venturi paths15. The venturi paths15are connected with the space6formed in the base block1. The carrier gas supplied from the space6formed in the base block1is adiabatically expanded and a flow rate of the carrier gas is increased, while the carrier gas passes through a throttle portion of the venturi path15. Therefore, in the venturi path15, the cleaning medium supplied from the sub-block2through the cleaning medium injection path16to the venturi path15can be rapidly mixed with the carrier gas supplied from the base block1to the venturi path15.

Each of the cleaning medium injection paths16has an angle of 15° to 60°, preferably 45 ° with respect to each of the venturi paths15. The venturi paths15respectively have a diameter of about 2 mm at a place where the venturi paths15are contacted with the cleaning medium injection paths16. The throttle portion formed in the venturi path15has a diameter of about 0.3 to 1 mm. An inlet and an outlet of the venturi path15respectively have a diameter of 1 to 3 mm. However, it is preferable that the diameter of the outlet is smaller than that of the inlet. In addition, since the cleaning medium injection paths16respectively have the above-mentioned angle with respect to the venturi paths15and the pressure of the carrier gas is about 10 to 50 psi lower than that of the cleaning medium of liquid Co2 state, a clogging phenomenon of the pipe due to back pressure or solidified particles is prevented.

Meanwhile, the carrier gas can be uniformly supplied to the venturi paths15formed in the first venturi block3according to a structure of the slit7aof the nozzle body7disposed in base block ion solution, and the cleaning medium can be uniformly supplied to the cleaning medium supplying path16according to a structure of the distribution surface9aand the space10of the nozzle body9. The cleaning medium is adiabatically expanded while passing through the venturi paths15of the first venturi block3, and the carrier gas has the increased flow rate after passing through the throttle portion, whereby a mixing rate of the carrier gas and the cleaning medium is increased. Preferably, the cleaning medium path16has a larger diameter of an upper portion thereof than that of a lower portion thereof, and the diameter of the lower portion is 0.1 to 0.3 mm. Therefore, the snow solidification of the cleaning medium is improved.

The intermediate block5is connected to the first venturi block3. The intermediate block5has a mixing space18and a path19communicated with a venturi path17of the second venturi block4. The mixing space18secures the sure mixing of the cleaning medium and the carrier gas and also stabilizes the flow of the cleaning medium and the carrier gas so as to induce the growth of the snow particles. In the mixing space18, a turbulent flow is stably transformed into a laminar flow, while the carrier gas and the cleaning medium are completely mixed and, at the same time, the snow particles are grown, thereby maintaining the uniform injection conditions. Preferably, each of the paths19has the same diameter as an inlet of the venturi path15.

The second venturi block4has the same number of venturi paths17as the number of venturi paths15of the first venturi block3and the number of the paths of the intermediate block5. The second venturi block4is connected to the intermediate block5so that the venturi paths17are exactly met with each other. As described above, since there are provided 10 or more venturi paths17of the second venturi block4through which the mixture of the cleaning medium and the carrier gas is injected into the outside, the nozzle of the present invention has an increased injection surface area.

The mixed gas of the cleaning medium and the carrier gas, of which the snow particles are grown, is adiabatically expanded again, while passing through the venturi paths17of the second venturi block4. Thus, a size of the sublimable solid particle can be maximized.

Meanwhile, in the embodiment of the present invention, as described above, the intermediate block5is disposed between the first venturi block3and the second venturi block4. Further, since the diameter of the cleaning medium path16through which the cleaning medium of the liquid Co2state is passed is reduced, the pressure of the cleaning medium, which is higher than the supplying pressure of the carrier gas, is applied to the cleaning medium path, thereby solving the problem of back pressure. Furthermore, since a proper amount of snow particles are formed, it is possible to inject the cleaning medium with the low pressure carrier gas.

As described above, the mixing places of the paths15,16,17and19formed in the first and second venturi block3and4and the intermediate block5respectively have a diameter of 2 mm. The throttle portion of each venturi path15and17has a diameter of 0.3 to 1 mm. The cleaning medium path16has a diameter of 0.1 to 0.3 mm. The inlet and outlet have a diameter of 1 to 3 mm.

According to the nozzle of the present invention, at the place in which the cleaning medium and the carrier gas are mixed, the cleaning medium supplying paths have an acute angle with respect to the venturi paths. The clogging of the cleaning medium supplying path due to the backflow of the carrier gas is prevented by pressure gradient according to a size of the cleaning medium path.

In addition, due to the first and second venturi blocks and the intermediate block, the flow and the solidified particles of the cleaning medium are stabilized and the solidification rate is maximized. Therefore, the consumption of the cleaning medium can be reduced, while a time of cleaning process can be remarkably reduced by the increasing in the injection surface area of the nozzle.

INDUSTRIAL APPLICABILITY

As described above, the cleaning medium is transformed into the liquid Co2by the first decompression using the regulator and other valve and the temperature drop using the cryogenic heat exchanger. The liquid Co2is phase-changed to form the sublimable solid particles like the Co2particles, while passing through the cleaning medium path16. Further, while the cleaning medium is passed through the nozzle of the present invention, an opportunity of the adiabatic expansion of the cleaning medium is maximized, and the flow rate of the cleaning medium is increased by the carrier gas. Meanwhile, in the embodiment, the Co2is used as the cleaning medium. However, it is obvious to those skilled in the art that other medium like Ar+can be used as the cleaning medium.