Substrate processing apparatus

Information

  • Patent Grant
  • 6805769
  • Patent Number
    6,805,769
  • Date Filed
    Wednesday, October 10, 2001
    22 years ago
  • Date Issued
    Tuesday, October 19, 2004
    19 years ago
Abstract
Reaction products produced under dry etching attach to a substrate undergoing dry etching. It is necessary to remove the reaction products for the next step. Therefore, in the case of the background art, the processing of supplying a remover for reaction products, an intermediate rinse for washing away the remover, and deionized water to a substrate in order is performed.The above processing is conventionally performed under an atmospheric atmosphere. Therefore, a thin film may be changed in quality due to atmospheric components.Therefore, a substrate processing apparatus of the present invention uses means for blowing nitrogen gas on a substrate and supplies a remover to the substrate while blowing nitrogen. Thereby, it is possible to prevent a thin film from being changed in quality due to atmospheric components.
Description




BACKGROUND OF THE INVENTION




1. Field of the Invention




The present invention relates to a substrate processing apparatus for removing organic matter on a substrate.




Moreover, the present invention relates to a substrate processing apparatus for removing a various reaction products due to a resist.




Furthermore, the present invention relates to a substrate processing apparatus for removing a reaction product produced on a substrate through a dry-etching step of dry-etching a thin film present on the surface of the substrate by using a resist film as a mask from the substrate.




2. Description of the Background Art




A semiconductor-device fabrication process includes a step in which a metallic thin film made of aluminum or copper formed on a substrate such as a semiconductor wafer is etched by using a resist film as a mask and used for the wiring of a semiconductor device.




For example, as shown in

FIG. 16A

, a device


102


is formed on a substrate


101


and a metallic film


103


is formed on the device


102


and the substrate


101


. The metallic film


103


is made of, for example, aluminum.




Then, a resist film


104


is formed on the metallic film


103


. The resist film


104


is obtained by coating a resist to the upper face of the metallic film


103


and drying the resist, exposing a wiring pattern to the dried resist by an exposure system, supplying a developer to the exposed resist, and dissolving and removing unnecessary portions. Thereby, only a necessary portion of the metallic film


103


is masked by the resist film


104


and left in the next etching step without being etched.




Then, by applying dry etching such as RIE (reactive ion etching) to the metallic film


103


masked by the resist film


104


, portions not masked by the resist film


104


in the metallic film


103


are removed through etching and a portion left without being etched becomes a metallic wiring


106


.




Thus, by executing dry etching, a reaction product


105


resulting from the resist film


104


or the like is deposited at a side of the metallic wiring


106


as shown in FIG.


16


B.




The reaction product


105


is not usually removed in the following resist removing step but it remains on the substrate


101


as shown in

FIG. 16C

even after removing the resist film


104


.




If the substrate


101


is sent to the next step without removing the reaction product


105


, reaction affects the processing quality from the next step downward. Therefore, it is necessary to remove the product


105


before it is sent to the next step.




Hence, a conventional substrate processing apparatus has remover supplying means for supplying a remover for a reaction product to a substrate, intermediate-rinse supplying means for supplying an intermediate rinse such as an organic solvent having a function for washing away a remover to the substrate, and deionized-water supplying means for supplying deionized water to the substrate and washing the substrate with deionized water.




In the case of the substrate processing apparatus of conventional type, the environment around a substrate when processing the substrate is not controlled. Therefore, because a thin film continuously contacts the atmosphere, it is changed in quality due to an atmospheric component and the quality of the substrate may be deteriorated.




SUMMARY OF THE INVENTION




The present invention is directed to a substrate processing apparatus for removing an organic matter from a substrate by a remover for the organic matter.




According to the present invention, the substrate processing apparatus for removing an organic matter from a substrate by a remover for the organic matter, comprises a holding-and-rotating section for holding and rotating a substrate, a remover supplying section for supplying a remover for removing an organic matter to the substrate held by the holing-and-rotating section, and a gas supplying section for supplying an inert gas to the substrate held by the holding-and-rotation section.




Because a gas supplying section for supplying an inert gas to a substrate is included, it is possible to reduce the contact between the substrate and the atmosphere. Therefore, it is possible to prevent a thin film on a substrate from being changed in quality.




Preferably, according to a first aspect of the present invention, the remover supplying section has a remover supplying tube for discharging a remover to a substrate, and the gas supplying section has a gas supplying tube for blowing an inert gas on a substrate.




Preferably, according to a second aspect of the present invention, the gas supplying section is provided with a gas nozzle having a slit-like gas-blowing port for blowing an inert gas along the surface of the substrate held by the holding-and-rotating section and the gas nozzle is set to a side of the substrate held by the holding-and-rotating section.




The present invention is also directed to a substrate processing method for removing an organic matter from a substrate by a remover for the organic matter.




Therefore, it is an object of the present invention to prevent a thin film on a substrate from being changed in quality due to an atmospheric component when performing the processing for removing an organic matter from the substrate.




These and other objects, features, aspects, and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.











BRIEF DESCRIPTION OF THE DRAWINGS





FIG. 1

is a side view of a substrate processing apparatus of a first preferred embodiment of the present invention;





FIG. 2

is a top view of the substrate processing apparatus of the first preferred embodiment of the present invention;





FIG. 3

is a perspective view of a double-tube nozzle;





FIG. 4

is a piping diagram of the substrate processing apparatus of the first preferred embodiment of the present invention;





FIG. 5

is an illustration showing an electrical configuration of the substrate processing apparatus of the first preferred embodiment of the present invention;





FIG. 6

is a flowchart of a substrate processing method of the first preferred embodiment of the present invention;





FIG. 7

is a detailed diagram of a flow of the substrate processing method of the first preferred embodiment of the present invention;





FIG. 8

is a side view of a substrate processing apparatus of a second preferred embodiment of the present invention;





FIG. 9

is a top view of the substrate processing apparatus of the second preferred embodiment of the present invention;





FIG. 10

is a piping diagram of the substrate processing apparatus of the second preferred embodiment of the present invention;





FIG. 11

is an illustration showing an electrical configuration of the substrate processing apparatus of the second preferred embodiment of the present invention;





FIG. 12

is a flowchart of a substrate processing method of the second preferred embodiment of the present invention;





FIG. 13

is a detailed diagram of a flow of the substrate processing method of the second preferred embodiment of the present invention;





FIG. 14

is a perspective view of a substrate processing apparatus of a third preferred embodiment of the present invention;





FIG. 15

is a top view of the substrate processing apparatus of the third preferred embodiment of the present invention;





FIGS. 16A

,


16


B and


16


C are illustrations for explaining the background art.











DESCRIPTION OF THE PREFERRED EMBODIMENTS




In the case of the following preferred embodiments, a substrate denotes a semiconductor substrate, more particularly a silicon substrate. Moreover, the substrate has a thin film. The thin film is a metallic film or an insulating film. A metal constituting the metallic film includes copper, aluminum, titanium, and tungsten. The insulating film uses a silicon oxide film or silicon nitride film. In this case, the thin film includes not only a film whose height is smaller than the bottom length but also a film whose height in the cross section is larger than the bottom length. Therefore, a wiring on the substrate is also included in the thin film.




A polymer which is a reaction product resulting from a resist or thin film is produced on a substrate passing through a step of dry-etching the thin film by using a resist film as a mask.




The substrate processing used for the following preferred embodiments denotes a polymer removal processing for removing a polymer from the substrate with the polymer produced on it.




Moreover, the remover used for the following preferred embodiments is a polymer remover. The polymer remover is a liquid for selectively removing only a polymer, which includes a liquid containing an organic alkali liquid, a liquid containing an inorganic acid, and a liquid containing ammnonium-fluoride-based substance. Among these liquids, DMF (dimethylformamide), DMSO (dimethylsulfoxide), or hydroxylamine is used as the liquid containing organic alkali liquid. Moreover, hydrofluoric acid or phosphoric acid is used as the liquid containing inorganic acid.




Moreover, examples of the polymer remover are liquids containing 1-methyl-2-pyrrolidone, tetrahydrothiophene1.1-dioxide, isopropanolamine, monoethanolamine, 2-(2aminoethoxy)ethanol, catechol, N-methylpyrrolidone, aromatic diol, perphene, and phenol, and, more specifically, a mixed solution of 1-methyl-2-pyrrolidone, tetrahydrothiophene1.1-dioxide, and isopropanolamine, a mixed solution of dimethyl sulfoxide and monoethanolamine, a mixed solution of 2-(2aminoethoxy)ethanol, hydroxyamine, and catechol, a mixed solution of 2-(2aminoethoxy)ethanol and N-methylpyrrolidone, a mixed solution of monoethanolamine, water, and aromatic diol, and a mixed solution of perphene and phenol.




Moreover, the intermediate rinse used for the following preferred embodiments is a liquid for washing away a remover from a substrate, which can use an organic solvent. The organic solvent can use isopropyl alcohol (IPA). Moreover, the intermediate rinse can use ozone water obtained by dissolving ozone in deionized water or hydrogen water obtained by dissolving hydrogen in deionized water.




Furthermore, in the following preferred embodiments, remover, intermediate rinse, and deionized water are generally referred to as treatment liquid.




<1. First Preferred Embodiment of Substrate Processing Apparatus>




A first preferred embodiment of a substrate processing apparatus of the present invention is described below.





FIGS. 1 and 2

show a substrate processing apparatus


1


.

FIG. 1

is an I—I sectional view of FIG.


2


and hatching is locally omitted for convenience's sake.




The substrate processing apparatus


1


has an almost U-shaped cross section as shown in FIG.


1


. In the top view in

FIG. 2

, the apparatus


1


comprises an almost-annular cup


3


having an opening at the center, a holding-and-rotating section


5


vertically set through the opening at the center of the cup


3


to hold and rotate a substrate W as shown in

FIG. 1

, a remover supplying section


7


for supplying a remover to the substrate W held by the holding-and-rotating section


5


, and a deionized-water supplying section


9


for supplying deionized water to the substrate W held by the holding-and-rotating section


5


.




The cup


3


has a plurality of discharge ports


4


at its bottom. Moreover, extra liquid supplied to the substrate W reaches the discharge ports


4


after passing through the inner wall of the cup


3


and is discharged to the outside of the apparatus from the discharge ports


4


. Moreover, a plurality of exhaust ports


6


are opened on the cup


3


. The exhaust ports


6


are openings formed toward the substrate W at a height almost equal to the horizontal height of the surface of the substrate W and connected to exhaust means constituted by a not-illustrated exhaust pump to exhaust a gas nearby the substrate W to the outside of the cup


3


.




The holding-and-rotating section


5


has a driving shaft vertically set and moreover has a spin motor


13


fixed to a not-illustrated machine casing, a spin shaft


14


fixed to the driving shaft of the spin motor


13


, and a vacuum chuck


15


set to the top of the spin shaft


14


to serve as a substrate holding member.




The vacuum chuck


15


has a suction face for sucking a substrate on its upper face and has a not-illustrated suction hole on the suction face. Moreover, by aspirating air through the suction hole, the chuck


15


almost horizontally holds the substrate W.




The holding-and-rotating section


5


holds the substrate W mounted on the vacuum chuck


15


and drives the spin motor


13


to rotate the substrate W about a shaft


71


.




The remover supplying section


7


has a driving shaft vertically set and has a first motor


17


fixed to a not-illustrated machine casing, a first rotation shaft


19


fixed to the driving shaft of the first motor


17


, a first arm


21


connected to the top of the first rotation shaft


19


, and a remover nozzle body


23


set to the front end of the first arm


21


.




The remover nozzle body


23


is fixed to the first arm


21


while axial directions of an inner tube


42


and an outer tube


38


to be described later are vertically set.




Moreover, when the first arm


21


reciprocally rotates about a shaft


73


as shown by an arrow


79


, the remover nozzle body


23


is fixed to the first arm


21


so that a remover


81


discharged from the remover nozzle body


23


moves on an circular arc


85


in FIG.


2


. In this case, the circular arc


85


shows a circular arc passing through the rotation center C of the substrate W and intersecting at two points on the circumference of a turning circle


95


which is drawn by a locus of the edge of the rotated substrate W.




The deionized-water supplying section


9


handles not a remover but only deionized water as a treatment liquid and has a structure almost same as that of the remover supplying section


7


.




The deionized-water supplying section


9


has a second motor


31


having a driving shaft vertically fixed to a not-illustrated machine casing, a second rotation shaft


33


fixed to the driving shaft of the second motor


31


, a second arm


35


connected to the top of the second rotation shaft


33


, and a deionized-water nozzle body


37


set to the front end of the second arm


35


.




The deionized-water nozzle body


37


is fixed to the second arm


35


while axial directions of an inner tube


42


and an outer tube


38


to be described later are vertically set.




Moreover, when the second arm


35


reciprocally rotates about the shaft


75


as shown by an arrow


77


, the deionized-water nozzle body


37


is fixed to the second arm


35


so that deionized water discharged from the deionized-water nozzle body


37


moves on a circular arc


87


in FIG.


2


. In this case, the circular arc


87


shows a circular arc passing through the rotation center C of the substrate W and intersecting at two points on the circumference of the turning circle


95


which is drawn by a locus of the edge of the rotated substrate W.




<1-1. Double-tube Nozzle>




Then, a double-tube nozzle


16


is described below by referring to FIG.


3


. The double-tube nozzle


16


is constituted by a cylindrical inner tube


42


having a determined outside diameter and a cylindrical outer tube


38


having an inside diameter larger than the outside diameter of the inner tube


42


and has a structure in which the inner tube


42


is set in the outer tube


38


and the inner tube


42


is coaxial with the outer tube


38


. Moreover, the outer tube


38


can discharge fluid from the gap with the inner tube


42


.




<1-2. Remover Supplying System


89


and Deionized-water Supplying System


91


>




Then, the remover supplying system


89


to the remover supplying section


7


and the deionized-water supplying system


91


to the deionized-water supplying section


9


are described below by referring to FIG.


4


.




In this case, the above-described double-tube nozzle


16


is used as the remover nozzle body


23


, and the outer tube


38


is set to a first gas supplying tube


27


for blowing nitrogen and the inner tube


42


is set to a remover supplying tube


29


for discharging a remover.




Moreover, the double-tube nozzle


16


is also used as the deionized-water nozzle body


37


, and the outer tube


38


is set to a second gas supplying tube


41


for blowing nitrogen and the inner tube


42


is set to a deionized-water supplying tube


43


for discharging deionized water.




The remover supplying system


89


has a remover pump


47


for pumping out a remover from a remover source


45


outside of an apparatus, a temperature controller


51


for controlling the temperature of the remover pumped out by the pump


47


by heating or cooling the remover to a predetermined temperature, a filter


49


for filtering contaminants from the remover temperature-controlled by the temperature controller


51


, and a remover supplying valve


53


for opening or closing the channel of the filtered remover to the remover supplying section


7


.




According to the above configuration, the remover supplying system


89


supplies the remover which is temperature-controlled to a predetermined temperature by the temperature controller


51


and purified by the filter


49


to the remover supplying tube


29


of the remover supplying section


7


.




The deionized-water supplying system


91


has a deionized-water pump


57


for pumping out deionized water from a deionized-water source


55


outside of the apparatus, a temperature controller


61


for controlling the temperature of the deionized water pumped out by the pump


57


by heating or cooling the deionized water to a predetermined temperature, a filter


59


for filtering contaminants from the deionized water temperature-controlled by the temperature controller


61


, and a deionized-water supplying valve


63


for opening or closing the channel of the filtered deionized water to the deionized-water supplying section


9


.




According to the above configuration, the deionized-water supplying system


91


supplies the deionized-water which is temperature-controlled to a predetermined temperature by the temperature controller


61


and purified by the filter


59


to the deionized-water supplying tube


43


of the deionized-water supplying section


9


.




<1-3. Gas Supplying Section


92


>




Then, the gas supplying section


92


is described below by referring to FIG.


4


.




The gas supplying section


92


has a first nitrogen valve


32


inserted into a duct extended to the first gas supplying tube


27


serving as the outer tube of the remover nozzle body


23


from the nitrogen source


44


for supplying nitrogen and a second nitrogen valve


34


inserted into a duct extended to the second gas supplying tube


41


serving as the outer tube of the deionized-water nozzle body


37


from the nitrogen source


44


. According to the above configuration, it is possible to execute or stop blowing nitrogen from the first gas supplying tube


27


, more minutely from the gap between the first gas supplying tube


27


and the remover supplying tube


29


by opening or closing the first nitrogen valve


32


. Moreover, by opening or closing the second nitrogen valve


34


, it is possible to execute or stop blowing nitrogen from the second gas supplying tube


41


, more minutely from the gap between the second gas supplying tube


41


and the deionized-water supplying tube


43


.




Then, an electrical configuration of the substrate processing apparatus


1


is described below by referring to FIG.


5


.




Controlling means


69


connects with the spin motor


13


, first motor


17


, second motor


31


, remover pump


47


, deionized-water pump


57


, remover supplying valve


53


, deionized-water supplying valve


63


, temperature controllers


51


and


61


, first nitrogen valve


32


, and second nitrogen valve


34


. The controlling means


69


controls these connected units as described for the first preferred embodiment of a substrate processing method to be described later.




<2. First Preferred Embodiment of Substrate Processing Method>





FIG. 6

is an illustration showing the first preferred embodiment of a substrate processing method using the above substrate processing apparatus


1


. As shown in

FIG. 6

, the substrate processing method of this preferred embodiment comprises a remover supplying step s


1


, a remover shaking-off step s


2


, a deionized-water supplying step s


3


, and a deionized-water shaking-off step s


4


. These steps are described below by referring to FIG.


7


.




(1. Remover Supplying Step s


1


)




First, the controlling means


69


controls the temperature controllers


51


and


61


by the time t0 so that temperatures of a remover and deionized water respectively reach a predetermined value. Moreover, the first nitrogen valve


32


and second nitrogen valve


34


are kept close.




Furthermore, the controlling means


69


drives the spin motor


13


to rotate the substrate W by the time t0 and the substrate W rotates at a predetermined number of revolutions at the time t0. Moreover, the controlling means


69


starts exhausting from the exhaust port


6


by the time t0 and aspirates the atmosphere nearby the substrate W.




Then, at the time t0, the controlling means


69


rotates the first motor


17


to rotate the remover nozzle body


23


on the substrate W reciprocally.




Moreover, the controlling means


69


discharges a remover toward the remover nozzle body


23


by driving the remover pump


47


, opens the remover supplying valve


53


, and supplies the remover from the remover supplying section


7


to the substrate W. Thereby, the remover supplied from the remover supplying section


7


is supplied onto the substrate W so that the arrival point to the substrate W moves on a circular arc passing through the rotation center C of the substrate W on the horizontal plane including the surface of the substrate W as shown by the arrow


85


in FIG.


2


. Moreover, at the time t0, the controlling means


69


opens the first nitrogen valve


32


.




According to the above described, the remover is supplied to the substrate W while nitrogen is blown onto the substrate W from the remover nozzle body


23


. Moreover, because the atmosphere nearby the substrate W is aspirated from the exhaust port


6


, the nitrogen blown from the remover nozzle body


23


moves along the surface of the substrate W and is aspirated into the exhaust port


6


. Thereby, because the surface of the substrate W is successively covered with nitrogen which is an inert gas, a thin film on the substrate W is prevented from being changed in quality.




Thus, the remover supplying step s


1


is executed. The controlling means


69


stops driving the first motor


17


at the time t1 after a predetermined time elapses from the time t0 while the remover nozzle body


23


escapes from the upper portion of the cup


3


. Moreover, the controlling means


69


closes both the remover supplying valve


53


and first nitrogen valve


32


and stops driving the remover pump


47


and supplying the remover from the remover nozzle body


23


.




(2. Remover Shaking-off Step s


2


)




Then, the control means


69


stops supplying the remover to the substrate W at the time t1 while it continuously rotates the spin motor


13


to keep the state of rotating the substrate W. Thereby, the remover-shaking-off step s


2


for shaking off the remover from the substrate W is executed.




In the remover shaking-off step s


2


, the substrate W is rotated at 500 rpm or more, preferably rotated at 1,000 to 4,000 rpm. Moreover, it is preferable to keep rotation for 1 sec or more, preferably for 2 to 5 sec.




Thus, because the substrate W continuously rotates while supply of the remover to the substrate W is stopped, the remover on the substrate W is shook off from the surface of the substrate W by a centrifugal force.




(3. Deionized-water Supplying Step s


3


)




Then, at the time t2, the controlling means


69


rotates the second motor


31


to rotate the deionized-water nozzle body


37


reciprocally.




Moreover, at the time t2, the controlling means


69


drives the deionized-water pump


57


and thereby discharges deionized water toward the deionized-water nozzle body


37


, opens the deionized-water supplying valve


63


, and supplies deionized water from the deionized-water supplying section


9


. Thereby, the deionized water supplied from the deionized-water nozzle body


37


is supplied onto the substrate W so that the arrival point to the substrate W moves on a circular arc passing through the rotation center C of the substrate W on a horizontal plane including the surface of the substrate W as shown by the arrow


87


in FIG.


2


. Moreover, at the time t2, the controlling means


69


opens the second nitrogen valve


34


.




According to the above described, deionized water is supplied to the substrate W while nitrogen is blown onto the substrate W from the deionized-water nozzle body


37


. Moreover, because the atmosphere nearby the substrate W is aspirated from the exhaust port


6


, the nitrogen blown out of the deionized-water nozzle body


37


moves along the surface of the substrate W and then it is aspirated into the exhaust port


6


. Thereby, because the surface of the substrate W is covered with nitrogen which is an inert gas, a thin film on the substrate W is prevented from being changed in quality. Thus, the deionized-water supplying step s


3


is executed.




At the time t3 after a predetermined time elapses, the controlling means


69


stops driving the second motor


31


while the deionized-water nozzle body


37


escapes from the upper portion of the cup


3


. Moreover, the controlling means


69


closes the deionized-water supplying valve


63


and second nitrogen valve


34


and stops driving the deionized-water pump


57


and supplying deionized water from the deionized-water nozzle body


37


. Furthermore, the controlling means


69


stops exhausting from the exhaust port


6


.




(4. Deionized-water Shaking-off Step s


4


)




At the time t3, the controlling means


69


stops supplying deionized water while it continuously rotates the spin motor


13


to keep the state of rotating the substrate W. Thus, the deionized-water shaking-off step s


4


is executed.




Because a remover and deionized water are supplied to the substrate W as described above, reaction products are removed.




According to the substrate processing method of this preferred embodiment, nitrogen is also continuously supplied to the substrate W while a remover is supplied to the substrate W in the remover supplying step s


1


. Therefore, it is possible to suppress the contact between a thin film and the atmosphere and prevent the thin film from being changed in quality. Moreover, in the deionized-water supplying step s


3


, nitrogen is also continuously supplied to the substrate W while deionized water is supplied to the substrate W. Therefore, it is possible to suppress the contact between a thin film and the atmosphere and prevent the thin film from being changed in quality.




According to the substrate processing method of this preferred embodiment, a remover on the substrate W is shook off in the remover shaking-off step s


2


and thereby, a small or no amount of the remover is left on the substrate W. Therefore, by supplying deionized water to the substrate W under the above state in the deionized-water supplying step s


3


, the quantity of the remover with which deionized water contacts slightly or completely decreases. Therefore, pH-shock hardly influences the substrate W or it does not occur. Therefore, an intermediate rinsing step is unnecessary and throughput is improved. Moreover, by omitting the intermediate rinsing step, it is possible to reduce cost and an organic solvent used for the intermediate rinsing step is unnecessary. Therefore, it is also possible to improve the safety of the apparatus.




PH-shock denotes that strong alkali is produced when a remover contacts deionized water. It is known that the produced strong alkali damages a metallic film.




Though the first preferred embodiment of the above substrate processing method reciprocates the remover nozzle body


23


and deionized-water nozzle body


37


relatively to the substrate W, the following way is also allowed.




That is, it is allowed to rotate the first motor


17


, set the remover nozzle body


23


(more minutely, the remover supplying tube


29


) immediately above the rotation center C of the substrate W by the time t0, and supply a remover to the rotation center C of the currently rotating substrate W and supply nitrogen from the first gas supplying tube


27


at the time t0. Then, it is allowed to supply the remover to the rotation center C of the currently rotating substrate W and supply nitrogen from the first gas supplying tube


27


while stopping the remover nozzle body


23


up to the time t1.




Furthermore, it is allowed to rotate the second motor


31


and set the deionized-water nozzle body


37


(more minutely, the deionized-water supplying tube


43


) immediately above the rotation center C of the substrate W by the time t2, and supply deionized water to the rotation center C of the currently rotating substrate W and supply nitrogen from the second gas supplying tube


41


at the time t2. Then, it is allowed to supply deionized water to the rotation center C of the currently rotating substrate W and supply nitrogen from the second gas supplying tube


41


while stopping the deionized-water nozzle body


37


up to the time t3.




Thus, because nitrogen radially moves along the surface of the substrate W from the rotation center C of the substrate W, the upper portion of the substrate W is uniformly covered with a nitrogen atmosphere. Therefore, it is possible to effectively suppress the quality change of a thin film.




Moreover, in the case of the first preferred embodiment of the above substrate processing method, supply of nitrogen from the first gas supplying tube


27


is performed simultaneously with supply of a remover from the remover supplying tube


29


. However, it is not necessary to perform the supplies at the same time.




That is, it is allowed to supply nitrogen from the first gas supplying tube


27


before supplying a remover from the remover supplying tube


29


. In this case, a remover is supplied after the surface of the substrate W is brought into a nitrogen atmosphere. Therefore, because the surface of the substrate W is brought into the nitrogen atmosphere before removal of reaction products is started from the surface of the substrate W, it is possible to effectively suppress the quality change of a thin film.




Moreover, it is allowed to start supplying a remover from the remover supplying tube


29


before supplying nitrogen from the first gas supplying tube


27


. In this case, the remover is supplied to the substrate W while the surface of the substrate W is put in an atmospheric atmosphere for a certain period. However, a certain type of a remover can quickly remove reaction products in an atmospheric atmosphere compared to the case of a nitrogen atmosphere.




When using the above type of the remover, it is preferable to previously calculate the removal start time up to the start of removal of reaction products from the surface of the substrate W through experiments or the like. Then, it is preferable to start supplying a remover from the remover supplying tube


29


at the time t0 and after the removal start time elapses, start supplying nitrogen from the first gas supplying tube


27


.




Thus, it is possible to quickly remove reaction products and suppress the quality change of a thin film.




Moreover, in the case of the first preferred embodiment of the above substrate processing apparatus, a remover is supplied from an inner tube and nitrogen from an outer tube by the remover nozzle body


23


of the substrate processing apparatus


1


. Therefore, when supplying a remover and nitrogen to the substrate W, a layer of the remover is smoothly formed immediately on the substrate W and a layer of the nitrogen is smoothly formed on the remover layer. Therefore, the remover on the substrate W is isolated from the atmosphere by the nitrogen layer and it is also possible to suppress the quality change of the remover due to an atmospheric atmosphere.




Though the remover nozzle body


23


of the above substrate processing apparatus


1


supplies the remover from the inner tube and nitrogen from the outer tube to the substrate W. However, it is also allowed to supply the nitrogen from the inner tube and the remover from the outer tube.




Moreover, in the case of the deionized-water nozzle body


37


, it is allowed to supply nitrogen from an inner tube and deionized water from an outer tube.




Furthermore, though the remover nozzle body


23


of the above substrate processing apparatus


1


uses a double-tube structure, it is also allowed to separately set a tube for discharging a remover and a tube for blowing nitrogen at the front end of the first arm


21


.




<3. Second Preferred Embodiment of Substrate Processing Apparatus>




Second preferred embodiment of a substrate processing apparatus of the present invention is described below by referring to

FIGS. 8 and 9

. Though

FIG. 8

is a sectional view taken along the line VIII—VIII in

FIG. 9

, hatching is locally omitted for convenience's sake.




A substrate processing apparatus


100


of the second preferred embodiment has a solvent supplying section


2


serving as an intermediate rinse supplying section in addition to the substrate processing apparatus


1


of the first preferred embodiment.




The substrate processing apparatus


100


of the second preferred embodiment has many portions common to those of the substrate processing apparatus


1


of the first preferred embodiment. Therefore, portions common to those of the substrate processing apparatus


1


are provided with the same reference numbers and their descriptions are omitted.




As shown in

FIG. 8

, the substrate processing apparatus


100


has a solvent supplying section


2


.




The solver supplying section


2


has a driving shaft vertically set and moreover has a third motor


18


fixed to a not-illustrated machine casing, a third rotation shaft


20


fixed to the driving shaft of the third motor


18


, a third arm


22


connected to the top of the third rotation shaft


20


, and a solvent nozzle body


24


set to the front end of the third arm


22


.




The above-described double-tube nozzle


16


is applied to the solvent nozzle body


24


, in which an inner tube


42


is set to a solvent supplying tube


30


and an outer tube


38


is set to a third gas supplying tube. Moreover, the solvent nozzle body


24


is fixed to the third arm


22


while vertically setting the axial directions of the inner tube


42


and outer tube


38


.




Furthermore, the solvent nozzle body


24


is fixed to the third arm


22


so that an organic solvent


82


discharged from the solvent nozzle body


24


moves on a circular arc


86


in

FIG. 9

when the third arm


22


reciprocally rotates about an axis


74


as shown by an arrow


78


. In this case, the circular arc


86


is a circular arc passing through the rotation center C of the substrate W and intersecting at two points on the circumference of a turning circle


95


which is drawn by a locus of the edge of the rotated substrate W.




<


3-1.


Solvent Supplying System


90


>





FIG. 10

shows a solvent supplying system


90


for supplying an organic solvent to a solvent supplying section


2


. The solvent supplying system


90


has a solvent pump


48


for pumping out an organic solvent from a solvent source


46


outside of the apparatus, a temperature controller


50


for controlling the temperature of the organic solvent to a predetermined temperature by heating or cooling the organic solvent pumped out by the solvent pump


48


, a filter


52


for filtering contaminants from the organic solvent temperature-controlled by the temperature controller


50


, and a solvent supplying valve


54


for opening or closing the channel of the filtered organic solvent to the solvent nozzle body


24


.




According to the above configuration, the solvent supplying system


90


supplies the organic solvent temperature-controlled to a predetermined temperature by the temperature controller


50


and purified by the filter


52


to the solvent nozzle body


24


.




Then, a gas supplying section


92


is described below by referring to FIG.


10


.




The gas supplying section


92


has a third nitrogen valve


36




a


inserted into a duct extended from the nitrogen source


44


to a third gas supplying tube


36


serving as the outer tube of the solvent nozzle body


24


in addition to the configuration of the substrate processing apparatus


1


of the first preferred embodiment. According to the above configuration, it is possible to execute or stop blowing nitrogen from the solvent nozzle body


24


by opening or closing the third nitrogen valve


36




a.






Then, an electrical configuration of the substrate processing apparatus


10


is described below by referring to FIG.


11


.




Similarly to the case of the control means


69


of the first preferred embodiment, control means


70


connects with a spin motor


13


, a first motor


17


, a second motor


31


, a remover pump


47


, a deionized-water pump


57


, a remover supplying valve


53


, a deionized-water supplying valve


63


, a temperature controller


51


, a temperature controller


61


, a first nitrogen valve


32


, and a second nitrogen valve


34


.




Furthermore, the control means


70


connects with a third motor


18


, a solvent pump


48


, a solvent supply valve


54


, a temperature controller


50


, a third nitrogen valve


36




a.






Moreover, the control means


70


controls these connected units as described for the second preferred embodiment of a substrate processing method to be described later.




<4. Second Preferred Embodiment of Substrate Processing Method>




Second preferred embodiment of a substrate processing method using the above substrate processing apparatus


100


is described below by referring to FIG.


12


.




The substrate processing method of this preferred embodiment comprises a remover supplying step s


31


, a remover shaking-off step s


32


, a solvent supplying step s


33


serving as an intermediate rinsing step, a deionized-water supplying step s


34


, and a deionized-water shaking-off step s


35


.




The substrate processing method of this preferred embodiment is constituted by substantially adding a solvent supplying step between the remover shaking-off step s


2


and the deionized-water supplying step s


3


of the substrate processing method of the first preferred embodiment comprising the remover supplying step s


1


, remover shaking-off step s


2


, deionized-water supplying step s


3


, and deionized-water shaking-off step s


4


.




Therefore, because the remover supplying step s


31


, remover shaking-off step s


32


, deionized-water supplying step s


34


, and deionized-water shaking-off step s


35


are the same as the remover supplying step s


1


, remover shaking-off step s


2


, deionized-water supplying step s


3


, and deionized-water shaking-off step s


4


of the substrate processing method of the first preferred embodiment, their descriptions are omitted.




Then, the solvent supplying step s


33


of this preferred embodiment is described below.




As shown in

FIG. 13

, the solvent supplying step s


33


is executed after the remover supplying step s


31


and remove shaking-off step s


32


. Because the substrate W continuously rotates while stopping the supply of a remover to the substrate W in the remover shaking-off step s


32


, the remover on the substrate W is shook off from the substrate W by a centrifugal force and thereby, the remover remaining on the substrate W is unlimitedly decreased. Moreover, the solvent supplying valve


54


and third nitrogen valve


36




a


are closed before the time t0 and the temperature controller


50


keeps an organic solvent at a predetermined temperature.




Then, at the time t2, the control means


70


rotates the third motor


18


and the solvent nozzle body


24


.




Moreover, at the time t2, the control means


70


drives the solvent pump


48


and thereby discharges an organic solvent toward the solvent nozzle body


24


, opens the solvent supplying valve


54


, and supplies the organic solvent from the solvent supplying section


2


.




Thereby, the organic solvent supplied from the solvent supplying section


2


(more minutely, the solvent nozzle body


24


) is supplied onto the substrate W so that the arrival point to the substrate W moves on a circular arc passing through the rotation center C of the substrate W on a horizontal plane including the surface of the substrate W as shown by an arrow


86


in FIG.


9


.




Moreover, the control means


70


opens the third nitrogen valve


36




a.


Thereby, a solvent is supplied to the substrate W while nitrogen is blown from the solvent nozzle body


24


. Moreover, because the atmosphere nearby the substrate W is aspirated from the exhaust port


6


, the nitrogen flown out of the solvent nozzle body


24


moves along the surface of the substrate W and then it is aspirated into the exhaust port


6


. Thereby, the surface of the substrate W is covered with nitrogen that is an inert gas and thereby the quality change of a thin film on the substrate W is suppressed.




Thus, in the solvent supplying step s


33


, a remover is completely washed away from the substrate W by supplying an organic solvent to the substrate W. Therefore, when deionized water is supplied to the substrate W in the subsequent deionized-water supplying step s


34


, no remover contacts deionized water and thereby, it is possible to prevent pH-shock from occurring. Therefore, it is possible to prevent a thin film on the substrate W from being damaged.




<5. Third Preferred Embodiment of Substrate Processing Apparatus>




Third preferred embodiment of a substrate processing apparatus of the present invention is described below by referring to

FIGS. 14 and 15

.

FIG. 15

is a top view of the preferred embodiment in FIG.


14


.




In the case of the substrate processing apparatus


1


of the first preferred embodiment and the substrate processing apparatus


100


of the second preferred embodiment, a gas supplying tube is also mounted on an arm on which a nozzle for discharging treatment liquid such as the first arm


21


, second arm


35


, or third arm


22


is mounted. In the case of the substrate processing apparatus


200


of the third preferred embodiment, however, a gas supplying tube is not mounted on such an arm but nitrogen-blowing means is set nearby a substrate W instead.




The substrate processing apparatus


200


is different from the substrate processing apparatus


100


of the second preferred embodiment in that a solvent nozzle body and a deionized-water nozzle body are mounted on one arm. However, because a holding-and-rotating section, a remover supplying system, a solvent supplying system, and a deionized-water supplying system substantially have the same configurations as those of the second preferred embodiment, their descriptions are omitted.




As shown in

FIG. 14

, the substrate processing apparatus


200


has a remover supplying section


207


for supplying a remover to the substrate W, a solvent and deionized-water supplying section


209


for supplying an organic solvent and deionized water to the substrate W, and gas blowing means


230


and gas aspirating means


206


. Moreover, though not illustrated, the substrate W is held by the holding-and-rotating section similarly to the case of the substrate processing apparatus


100


.




The remover supplying section


207


has a first motor


217


which is fixed to a not-illustrated machine casing and has a driving shaft vertically set, a first rotation shaft


219


fixed to the driving shaft of the first motor


217


, and a first arm


221


connected to the top of the first rotation shaft


219


.




A first fixed block


229


is set to the front end of the first arm


221


and a remover nozzle body


223


is set to the first fixed block


229


.




The remover nozzle body


223


is a tubular member vertically set, in which an opening oriented to the substrate W is formed on one end and a remover is supplied to the other end from a remover supplying system. Thereby, the remover nozzle body


223


discharges a remover to the substrate W.




In the case of this preferred embodiment, as shown by the arrow


285


in

FIG. 15

, the remover nozzle body


223


is moved so that the arrival point of a remover to the substrate W moves on a circular arc using the radius of a turning circle


95


drawn by rotation of the edge of the substrate W as a chord.




The solvent and deionized-water supplying section


209


has a second motor


231


which is fixed to a not-illustrated machine casing and has a driving shaft vertically set, a second rotation shaft


233


fixed to the driving shaft of the second motor


231


, and a second arm


235


connected to the top of the second rotation shaft


233


.




A second fixed block


243


is set to the front end of the second arm


235


and a deionized-water nozzle body


237


and a solvent nozzle body


224


are set to the second fixed block


243


.




The deionized-water nozzle body


237


is a tubular member vertically set, in which an opening oriented to the substrate W is formed on one end and deionized water is supplied to the other end from a deionized-water supplying system. Thereby, the deionized-water nozzle body


237


discharges deionized water to the substrate W.




The solvent nozzle body


224


is a tubular member in which an opening oriented to the substrate W is formed on one end and an organic solvent is supplied to the other end from a solvent supplying system. Thereby, the solvent nozzle body


224


discharges an organic solvent to the substrate W. The front end of the solvent nozzle body


224


is bent in the direction in which the deionized-water nozzle body


237


is present. Minutely, the front end of the solvent nozzle body


224


is bent so that the arrival point of an organic solvent discharged from the solvent nozzle body


224


to the substrate W become equal to the arrival point of deionized water discharged from the deionized-water nozzle body


237


to the substrate W. According to the above configuration, an organic solvent and deionized water supplied from the solvent and deionized-water supplying section


209


arrive at the same position on the substrate W.




In the case of this preferred embodiment, the solvent nozzle body


224


and deionized-water nozzle body


237


are moved so that arrival points of deionized water and an organic solvent to the substrate W move on a circular arc using the radius of the turning circle


95


drawn by rotation of the edge of the substrate W as a chord as shown by the arrow


287


in FIG.


15


.




The gas blowing means


230


has a gas nozzle


227


on which a slot-like (slit-like) gas blowing port


228


extending in the extending direction of the surface of the substrate W or almost horizontal direction in this case is formed. The gas nozzle


227


is set so that the gas blowing port


228


becomes almost the same height and position as the substrate W nearby the substrate W. Moreover, nitrogen is supplied to the gas nozzle


227


and thereby, a nitrogen gas is blown toward the substrate W from the gas blowing port


228


.




The aspirating means


206


has an aspiration nozzle


208


. The aspiration nozzle


208


has a slot-like aspiration port


210


extending in the extending direction of the surface of the substrate W or almost horizontal direction in this case. Moreover, because the aspiration nozzle


208


is exhausted, the atmosphere nearby the substrate W is aspirated into the aspiration port


210


.




The above substrate processing apparatus


200


executes a remover supplying step of supplying a remover to the currently-rotating substrate W from the remover nozzle body


223


while rotating the substrate W and reciprocating the remove nozzle body


223


while blowing nitrogen from the gas blowing means


230


simultaneously with the supply of a remover and aspirating the atmosphere nearby the substrate W by the aspirating means


206


.




Thereby, the nitrogen supplied from the gas blowing means


230


flows on the surface of the substrate W and is aspirated into the aspirating means


206


and the surface of the substrate W is covered with a nitrogen atmosphere. Moreover, a remover is supplied to the substrate W while the surface of the substrate W is covered with the nitrogen atmosphere.




Therefore, it is possible to suppress the quality change of a thin film on the substrate W due to the atmosphere.




After the remover supplying step is completed, a solvent supplying step is executed in which supply of a remover is stopped to supply an organic solvent from the solvent nozzle


224


while continuing supply of nitrogen from the gas blowing means


230


, aspiration of atmosphere from the aspirating means


206


, and rotation of the substrate W.




After the solvent supplying step is completed, a deionized-water supplying step is executed in which supply of an organic solvent is stopped to supply deionized water from the deionized-water nozzle body


237


while continuing supply of nitrogen from the gas blowing means


230


, aspiration of atmosphere from the aspirating means


206


, and rotation of the substrate W.




After the deionized-water supplying step is completed, supply of deionized water is stopped while continuing supply of nitrogen from the gas blowing means


230


, aspiration of atmosphere from the aspirating means


206


, and rotation of the substrate W. Thereby, a deionized-water shaking-off step for the substrate W is executed under a nitrogen atmosphere.




As described above, in the case of the substrate processing apparatus


200


of this preferred embodiment, nitrogen is blown out of the gas blowing means


230


and atmosphere is aspirated from the aspirating means


206


in all the remover supplying step, solvent supplying step, deionized-water supplying step, and deionized-water shaking-off step and periods between these steps. Therefore, because all processings of the substrate W can be executed under a nitrogen atmosphere, it is possible to preferably suppress the quality change of a thin film on the substrate W.




<6. Summary>




Though the holding-and-rotating section of each of the above preferred embodiments horizontally holds and rotates a substrate, it is also allowed to use a holding-and-rotating section for holding and rotating a substrate by tilting the main surface of the substrate from a horizontal plane or making the main surface of the substrate parallel with the vertical direction.




Moreover, though the holding-and-rotating section of each of the above preferred embodiments holds only one substrate, it is also allowed to use a holding-and-rotating section for holding a plurality of substrates.




Furthermore, the substrate processing of each of the above preferred embodiments purposes a substrate on whose surface a polymer is produced after undergoing dry etching. The substrate processing is particularly effective when purposing a substrate after undergoing the above dry etching and moreover ashing.




Ashing is performed by setting a substrate having a resist film in oxygen plasma. When undergoing ashing, a firmer polymer is produced. Therefore, when removing a polymer from a substrate undergoing dry etching and ashing, it is possible to improve the throughput and reduce the cost in accordance with the present invention.




Moreover, the substrate processing apparatus of each of the above preferred embodiments shows a particularly remarkable effect when a thin film on the substrate W is a metallic film. That is, metallic films are easily oxidized by oxygen in the atmosphere. Particularly, a metallic portion exposed because reaction products are removed is easily oxidized. This oxide deteriorates the quality of a substrate. However, because the substrate processing apparatus of each of the above preferred embodiments has a gas supplying section for supplying nitrogen which is an inert gas to a substrate, it is possible to suppress occurrence of oxides. Among the above metallic films, a copper (Cu) film is particularly extremely deteriorated in quality by oxidation. When removing reaction products from a substrate having a copper film or a copper wiring, the substrate processing apparatus of each of the above preferred embodiments shows a remarkable effect.




Moreover, though nitrogen is used for each of the above preferred embodiments as an inert gas, it is also possible to use argon as an inert gas.




In the case of the above preferred embodiments, it is disclosed to remove a polymer produced under dry etching from a substrate passing through a dry etching step. However, the present invention is not restricted to the case of removing the polymer from the substrate on which the polymer is present under dry etching.




For example, though previously described, the present invention includes a case of removing a polymer produced under plasma ashing from a substrate. Therefore, a case is also included in which a polymer produced due to a resist is removed from a substrate not only under dry etching but also under various processings.




Moreover, the present invention is not restricted to a case of removing only a polymer produced due to a processing through dry etching and plasma ashing but it includes a case of removing various reaction products due to a resist from a substrate.




Furthermore, the present invention is not restricted to a case of removing reaction products due to a resist from a substrate but it also includes a case of removing a resist from a substrate.




For example, a case is also included in which a resist film whose lower-layer processing is completed and thereby which becomes unnecessary is removed from a substrate to which a resist is applied, patterns including a wiring pattern are exposed to the resist, the resist is developed, and the lower layer of the resist is processed (for example, a thin film serving as the lower layer is etched).




In this case, it is possible to remove a reaction product produced due to the quality change of the resist film if any simultaneously when removing the unnecessary resist film. Therefore, the throughput is improved and the cost can be reduced. For example, when dry-etching the thin film serving as a lower layer in the above lower-layer processing, reaction products are also produced. Therefore, it is also possible to remove the resist film used to mask the lower layer under dry etching and reaction products produced due to the quality change of the resist film.




Moreover, the present invention is not restricted to a case of removing not only a reaction product resulting from a resist or the resist itself from a substrate but also an organic matter not resulting from a resist such as a fine contaminant produced by a human body from a substrate.




While the invention has been shown and described in detail, the foregoing description is in all aspects illustrative and not restrictive. It is therefore understood that numerous other modifications and variations can be devised without departing from the scope of the invention.



Claims
  • 1. A substrate processing apparatus for removing an organic matter from a substrate by a remover for said organic matter, comprising:a holding-and-rotating section for holding and rotating a substrate; a remover supplying section for supplying a remover for removing an organic matter to the substrate held by said holding-and-rotating section; and a gas supplying section for supplying an inert gas to a surface of the substrate substantially concurrently with a supply of said remover to said substrate.
  • 2. The substrate processing apparatus according to claim 1, whereinsaid remover supplying section bas a remover supplying tube for discharging a remover to a substrate, and said gas supplying section has a gas supplying tube for blowing an inert gas on said substrate.
  • 3. The substrate processing apparatus according to claim 2, whereinsaid remover supplying tube is set in said gas supplying tube.
  • 4. The substrate processing apparatus according to claim 3, further comprising:an exhausting section set to a side of the substrate held by said holding-and-rotating section to exhaust a gas nearby said substrate.
  • 5. The substrate processing apparatus according to claim 4,wherein said organic matter attached to said substrate is a reaction product produced when a resist film formed on said substrate changes in quality.
  • 6. The substrate processing apparatus according to claim 5, whereinsaid reaction product is a polymer produced when a thin film present on the surface of said substrate is dry-etched by using said resist film as a mask.
  • 7. The substrate processing apparatus according to claim 1, whereinsaid gas supplying section is provided with a gas nozzle having a slit-like gas-blowing port for blowing an inert gas along the surface of the substrate held by said holding-and-rotating section and said gas nozzle is set to a side of the substrate held by said holding-and-rotating section.
  • 8. The substrate processing apparatus according to claim 7, further comprising:an aspirating section for aspirating a gas nearby the substrate held by said holding-and-rotating section, said aspirating section being located opposite said gas nozzle with said substrate sandwiched in between.
  • 9. The substrate processing apparatus according to claim 8, whereinsaid remover supplying section starts supplying a remover to a substrate and when a predetermined time elapses, said gas supplying section starts supplying an inert gas to said substrate.
  • 10. The substrate processing apparatus according to claim 9, whereinsaid organic matter attached to said substrate is a reaction product produced when a resist film formed on said substrate changes in quality.
  • 11. The substrate processing apparatus according to claim 10, whereinsaid reaction product is a polymer produced when a thin film present on the surface of said substrate is dry-etched by using said resist film as a mask.
  • 12. The substrate processing apparatus according to claim 1, further comprising:a controller for controlling said remover supplying section and said gas supplying section in such a manner that a supply period of said remover and a supply period of said inert gas to the substrate at least in part overlap.
  • 13. The substrate processing apparatus according to claim 12, whereinsaid controller controls said remover supplying section and said gas supplying section in such a manner that said remover supplying section starts supplying a remover to a substrate and, when a predetermined time elapses, said gas supplying section starts supplying an inert gas to said substrate.
  • 14. A substrate processing method for removing an organic matter from a substrate by a remover for said organic matter, comprising the steps of:holding and rotating a substrate; supplying a remover for removing an organic matter to said rotating substrate; and supplying an inert gas to a surface of the substrate substantially concurrently with said supplying of a remover.
  • 15. The substrate processing apparatus according to claim 14, whereinit is started to supply a remover to said substrate and when a predetermined time elapses, it is started to supply an inert gas to said substrate.
  • 16. The substrate processing apparatus according to claim 15, whereinsaid organic matter attached to said substrate is a reaction product produced when a resist film formed on said substrate changes in quality.
  • 17. The substrate processing apparatus according to claim 16, whereinsaid reaction product is a polymer produced when a thin film present on the surface of said substrate is dry-etched by using said resist film as a mask.
  • 18. The substrate processing apparatus according to claim 14, whereina supply period of said remover and a supply period of said inert gas to the substrate at least in part overlap.
Priority Claims (1)
Number Date Country Kind
P2000-313496 Oct 2000 JP
US Referenced Citations (7)
Number Name Date Kind
4968375 Sato et al. Nov 1990 A
5608943 Konishi et al. Mar 1997 A
5871584 Tateyama et al. Feb 1999 A
5952050 Doan Sep 1999 A
6247479 Taniyama et al. Jun 2001 B1
6453916 Tran et al. Sep 2002 B1
6669809 Hashimoto et al. Dec 2003 B2
Foreign Referenced Citations (5)
Number Date Country
63-190679 Aug 1988 JP
64-61917 Mar 1989 JP
4-206626 Jul 1992 JP
11-40557 Feb 1999 JP
2948055 Jul 1999 JP