JPH11145099A - Substrate treatment equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a substrate treatment equipment which enables uniform treatment even when consumption of treatment liquid is reduced. SOLUTION: In a closed chamber 10, a treatment bath 20 is arranged, in which treatment liquid is stored. A substrate W is held by a rotating stand 30 so as to be dipped in the treatment liquid in the treatment bath 20. The substrate W is rotated in the treatment liquid by a motor 32, and substrate cleaning treatment is performed. During the cleaning treatment, a liquid film exists always on the surface of the substrate W, so that nonuniform treatment due to an insufficient liquid film is not generated even when the supply amount of chemical liquid and pure water is reduced. Hence the supply amount of chemical liquid and pure water can be reduced as compared with the conventional case, and the consumption of chemical liquid and pure water can be reduced, so that cost reduction in the substrate treating process is enabled.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention uses a processing liquid for a thin substrate (hereinafter simply referred to as "substrate") such as a semiconductor substrate, a liquid crystal glass substrate, a glass substrate for a photomask, and a substrate for an optical disk. The present invention relates to a substrate processing apparatus that performs a predetermined process while performing a predetermined process.

[0002]

2. Description of the Related Art Generally, in a process of manufacturing a substrate, a chemical cleaning treatment using an acid or alkali chemical and a pure water cleaning treatment using pure water are performed. A processing apparatus that performs substrate processing using chemical liquid and pure water (these are collectively referred to as “processing liquids”) includes a single-wafer processing apparatus that processes substrates one by one and a processing apparatus that simultaneously processes a plurality of substrates. There is a batch type processing device.

FIG. 11 is a view for explaining a conventional single wafer type substrate cleaning apparatus. The peripheral end of the substrate W is held by a substrate holding member 107 erected on the spin base 105. In addition, the spin base 105 is
And is rotatable about a vertical axis.

When performing a chemical cleaning process on the substrate W, a chemical solution is discharged from the chemical solution front nozzle 102 and the chemical solution rear nozzle 104 onto the front and back surfaces of the substrate W, respectively, while rotating the substrate W. The spin base 105 has a shape in which a plurality of arms are radially arranged from the center thereof, and the chemical discharged from the chemical back nozzle 104 passes through the gap between the plurality of arms to the back surface of the substrate W. To reach.

When the substrate W is subjected to the pure water cleaning treatment, the pure water is discharged from the pure water front nozzle 101 and the pure water rear nozzle 103 onto the front surface and the rear surface of the substrate W while rotating the substrate W. .

[0006] When the chemical cleaning process and the pure water cleaning process are completed, the substrate W is transported to a substrate drying apparatus, and a drying process (spin drying) by high-speed rotation is performed.

[0007]

However, in the above-mentioned conventional substrate cleaning apparatus, it is necessary to supply a chemical solution or pure water on the substrate in a film form. Has been insufficient, and the processing has become non-uniform.

Therefore, it is necessary to discharge a sufficient amount of a chemical solution and pure water to form a liquid film, and the consumption of the chemical solution and pure water has been significantly increased.

In addition, during the cleaning process using a chemical solution and pure water, the substrate W is rotated at a high speed, so that the droplets shaken off by centrifugal force from the substrate W or the spin base 105 are
The powder scatters on the cup 108 disposed around the spin base 105, is rebounded by the cup 108, and adheres to the substrate W again. The droplets once shaken off from the substrate W or the spin base 105 contain particles and various contaminants, and when the droplets adhere to the substrate W again,
The substrate W will be contaminated. In the manufacturing process of the substrate, it is important to maintain the cleanliness of the substrate.
Contamination may cause a reduction in the yield of devices manufactured from the substrate W.

A conventional substrate cleaning apparatus is usually arranged in a clean room, and the atmosphere of the clean room is directly introduced into the apparatus. Therefore, the substrate W is exposed to the atmosphere of the clean room between the chemical solution cleaning step and the pure water cleaning step. Further, when the substrate W is transferred from the substrate cleaning device to the substrate drying device, the substrate W is exposed to the atmosphere of the clean room.

In general, the atmosphere in a clean room is adjusted for temperature and humidity and particles are removed by a filter, but still contains some particles, various gases, oxygen and water vapor. When the substrate W is exposed to such a clean room atmosphere, contamination may be caused by adhesion of particles or adsorption of gas, or a so-called watermark may be generated by unnecessary oxidation, which may cause a reduction in device yield. Becomes

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its first object to provide a substrate processing apparatus capable of performing uniform processing even when the consumption of the processing liquid is reduced.

It is a second object of the present invention to provide a substrate processing apparatus capable of preventing contamination of a substrate during or after processing a substrate with a processing solution.

[0014]

According to a first aspect of the present invention, there is provided a substrate processing apparatus for performing a predetermined process on a substrate while using a processing solution, wherein (a) A processing tank that stores the liquid, (b) a processing liquid supply unit that supplies the processing liquid to the processing tank, (c) a processing liquid discharge unit that discharges the processing liquid from the processing tank, (d) the processing liquid A substrate holding unit that is disposed in the processing tank and holds the substrate in the processing liquid stored in the processing tank; and (e) in a state where the substrate is held in the processing liquid by the substrate holding unit. Rotation driving means for rotating the substrate holding means.

According to a second aspect of the present invention, there is provided the substrate processing apparatus according to the first aspect of the present invention, further comprising (f) a closed chamber for housing the processing tank.

According to a third aspect of the present invention, in the substrate processing apparatus according to the second aspect of the present invention, there is provided (g) an organic solvent vapor supply means for supplying an organic solvent vapor for drying the processing liquid into the closed chamber. , Is further provided.

According to a fourth aspect of the present invention, there is provided the substrate processing apparatus according to the second aspect of the present invention, further comprising: (h) inert gas supply means for supplying an inert gas into the closed chamber.

According to a fifth aspect of the present invention, in the substrate processing apparatus according to any one of the first to fourth aspects of the present invention, (i) the processing liquid discharged by the processing liquid discharging means is provided with the processing liquid. And a circulation path for returning to the supply means and supplying the treatment tank with the supply tank again.

According to a sixth aspect of the present invention, in the substrate processing apparatus according to any one of the first to fifth aspects of the present invention, the rotation driving means is disposed above the processing tank.

According to a seventh aspect of the present invention, in the substrate processing apparatus according to any one of the first to sixth aspects, the surface of the substrate facing the main surface of the substrate held by the substrate holding means is provided. A discharge port for discharging the processing liquid supplied from the processing liquid supply means to the main surface.

According to an eighth aspect of the present invention, in the substrate processing apparatus according to any one of the first to fifth aspects, the rotation driving means is disposed below the processing tank to supply the processing liquid. The means includes a supply impeller fixed to a rotating shaft of the rotary drive means, and the processing liquid is supplied to the processing tank by rotation of the supply impeller.

According to a ninth aspect of the present invention, in the substrate processing apparatus according to any one of the first to fifth aspects, the rotation driving means is disposed below the processing tank to discharge the processing liquid. The means includes a discharge impeller fixed to a rotating shaft of the rotary drive means, and the processing liquid stored in the processing tank is discharged by rotation of the discharge impeller.

According to a tenth aspect of the present invention, in the substrate processing apparatus according to any one of the first to fifth aspects, the processing liquid supply means is fixedly provided above the processing tank. A supply impeller is included, and the processing liquid is supplied to the processing tank via the supply impeller.

According to an eleventh aspect of the present invention, in the substrate processing apparatus according to any one of the first to tenth aspects, an ultrasonic vibrator for applying ultrasonic vibration to the processing liquid in the processing tank. Is attached to the processing tank.

[0025]

Embodiments of the present invention will be described below in detail with reference to the drawings.

<1. First Embodiment> FIG. 1 is a configuration diagram showing an example of a substrate processing apparatus according to the present invention. The substrate processing apparatus has a function of performing a cleaning process on a substrate W with a chemical solution and pure water, and further performing a drying process after the cleaning process.

In the substrate processing apparatus of the first embodiment shown in FIG. 1, a processing tank 20 is provided inside a closed chamber 10 and a substrate W is stored inside the processing tank 20 storing a processing liquid.
Is configured to be able to perform the cleaning process. The substrate processing apparatus includes a processing liquid supply mechanism for supplying the processing liquid to the processing tank 20, a processing liquid discharging mechanism for discharging the processing liquid from the processing tank 20, and a rotation for rotating the substrate W while holding the substrate W in the processing liquid. Various mechanisms such as a driving mechanism and a gas supply mechanism for supplying IPA vapor (isopropyl alcohol vapor) and an inert gas into the closed chamber 10 are provided.

A gate valve 11 is provided on a side wall of the closed chamber 10 in which the processing tank 20 is installed. When loading / unloading a substrate W into / from the substrate processing apparatus, the gate valve 11 is opened, and a substrate transfer robot (not shown) loads / unloads the substrate from / to the side wall opening of the closed chamber 10. On the other hand, when the substrate is being cleaned and dried in the substrate processing apparatus, the gate valve 11 is closed,
The inside of the closed chamber 10 is a closed space.

Since the substrate processing is performed in the closed chamber 10 which is closed to the clean room, the clean room atmosphere is not introduced into the closed chamber 10 and the processing is performed by the particles and the gas contained in the atmosphere. Of the substrate W is not contaminated.

The processing tank 20 of the first embodiment is configured so that the processing liquid can be supplied from above and the processing liquid can be discharged from below. Here, the processing liquid is a general term for the chemical liquid and pure water as described above, and the chemical liquid used in the substrate processing apparatus according to the present invention includes hydrofluoric acid, a mixed solution of ammonia hydrogen peroxide and the like.

The processing liquid supply mechanism for supplying the processing liquid to the processing tank 20 includes a pure water valve 49, a chemical liquid valve 45, an IPA valve 44, a mixing section 43, a regulator 42, and a supply valve 4.
0, a fixed type supply impeller 41 and a supply pipe. When supplying pure water to the treatment tank 20, the supply valve 40 and a pure water valve 49 connected to a pure water supply source (not shown) are opened, and the chemical liquid valve 45 and IP
The A valve 44 is closed. The pure water is supplied to the processing tank 20 via the pure water valve 49, the mixing section 43, the regulator 42, the supply valve 40, and the fixed supply impeller 41.

The processing tank 20 has a liquid level meter 47 for detecting the level of the processing liquid stored in the processing tank 20.
Is installed, and the liquid level measuring device 47 is electrically connected to the level controller 48. The level controller 48 instructs the regulator 46 so that the liquid level of the processing liquid detected by the liquid level measuring device 47 is higher than the substrate W held on the turntable 30 and does not overflow from the processing tank 20. To communicate. The regulator 46 controls the flow rate of nitrogen gas sent to the regulator 42 based on a command from the level controller 48. The regulator 42 can adjust the supply amount of pure water or the supply amount of the chemical solution according to the flow rate of the sent nitrogen gas. That is,
The level controller 48 controls the supply amount of pure water according to the liquid level in the processing tank 20, and the liquid level is higher than the substrate W held on the turntable 30 and does not overflow from the processing tank 20. Adjust it. In addition, the level controller 48 may be electrically connected to a drain valve 50 described later, and the level of liquid in the processing tank 20 may be adjusted by controlling the amount of pure water discharged from the processing tank 20. .

When pure water is supplied to the processing tank 20, I
Open PA valve 44 and mix IPA in pure water in mixing section 43
May be mixed and supplied to the processing tank 20.
This technique will be described later.

When supplying a chemical solution to the treatment tank 20, the supply valve 40 and a chemical solution valve 45 connected to a chemical solution supply source (not shown) are opened, and a pure water valve 49 and an IPA
The valve 44 is closed. The chemical is supplied to the processing tank 20 via the chemical valve 45, the mixing section 43, the regulator 42, the supply valve 40, and the fixed supply impeller 41.
Also at this time, the level controller 48 adjusts the level of the chemical solution in the processing tank 20 to the substrate W
The height is adjusted to be higher than the height and not to overflow from the processing tank 20.

In the substrate processing apparatus according to the present invention, since both the cleaning process using the chemical solution and the cleaning process using the pure water are performed in the closed chamber 10, the substrate W is disposed between the chemical solution cleaning process and the pure water cleaning process. Is not exposed to the atmosphere of the clean room, and the substrate W is not likely to be contaminated by particles or gas contained in the atmosphere.

The pure water or the chemical solution supplied to the treatment tank 20 is supplied via the fixed supply impeller 41. The fixed supply impeller 41 is a fixed member having a plurality of spiral blades, and has a function of supplying the processing liquid to the processing tank 20 while turning the processing liquid passing through the member. The form and the like of the fixed supply impeller 41 will be described together with a movable impeller 35 described later.

The supplied processing liquid is stored in the processing tank 20. Since the rotating shaft 31 of the motor 32 passes through the bottom of the processing tank 20, the processing tank 20 and the rotating shaft 31
The seal member 62 prevents the processing liquid from leaking from the space between them. FIG. 2 is a view showing a sealed portion of the processing tank 20. The seal member 62 is a member having a V-shaped cross section, thereby preventing the processing liquid stored in the processing tank 20 from leaking.

However, the rotating shaft 31 may perform not only a rotating operation but also an up and down operation, and it is difficult to completely prevent the rotation by the seal member 62. Therefore, the seal member 6 is provided via the flow control valve 61 and the seal water valve 60.
2, pure water as sealing water is supplied below the sealing member 6.
By filling the space between 2 and the sealing member 63 with pure water,
Prevention of leakage of the processing liquid from the processing tank 20 is completed.

Returning to FIG. 1, pure water supplied as seal water may leak from the seal member 63. Pure water leaking from the seal member 63 is collected by the vat 33 and drained out of the apparatus.

On the other hand, when discharging the processing liquid stored in the processing tank 20, the processing liquid is discharged outside the apparatus by opening the drain valve 50. Here, in the substrate processing apparatus of the first embodiment, the processing liquid is discharged by opening the drain valve 50 and rotating the movable impeller 35. FIG. 3 is a perspective view illustrating an example of the form of the movable impeller 35. As shown, four spiral blades 35a are attached to the outer periphery of the rotating shaft 31. When the rotating shaft 31 rotates clockwise, the spiral blade 35 is rotated.
a, the processing liquid is pushed downward, and the drain valve 50
Is discharged through.

That is, the rotation of the rotary shaft 31 is originally for transmitting the rotation of the motor 32 to the substrate W. In this embodiment, the movable impeller 35 is used and the rotation of the rotary shaft 31 is utilized. The processing liquid will be discharged. Therefore, a discharge system such as a dedicated pump for discharging the processing liquid is not required, and the substrate processing apparatus can be reduced in size and cost. In FIG. 3, four spiral blades 35a are provided, but the number of spiral blades 35a is not limited thereto, and one or more spiral blades 35a may be mounted.

By the way, the above-mentioned fixed supply impeller 4
The embodiment 1 is also the same as that shown in FIG. However, in the case of the fixed supply impeller 41, the spiral blade 35a
Are not attached to the rotating shaft 31 but are attached to a fixed shaft. Therefore, even when the processing liquid is supplied, the fixed supply impeller 41 does not rotate, and the processing liquid turns along the spiral blade 35a. By supplying the processing liquid to the processing tank 20 while rotating, the relative speed between the substrate W and the supplied processing liquid is increased, and the cleaning effect of the substrate W is enhanced.

Next, the rotation drive mechanism of the substrate W will be described. The substrate W is held by the turntable 30 so as to be immersed in the processing liquid stored in the processing bath 20. Since the substrate W is held by the plurality of pin-shaped substrate holding members 30a erected on the turntable 30 so as to grip the peripheral end of the substrate W, the substrate W There is a certain interval between them. Therefore, the processing liquid can contact both surfaces of the substrate W.

The rotating table 30 has a rotating shaft 3
1, the rotating shaft 31 is connected to a motor 32. The rotation of the motor 32 is transmitted to the turntable 30 via the rotation shaft 31, and the substrate W held on the turntable 30 rotates about the vertical direction as an axis. In other words, the substrate W is rotated while the substrate W is held in the processing liquid by the turntable 30, so that the substrate W is cleaned by the processing liquid.

On the other hand, the motor 32 is connected to the lifting / lowering means 34 by a locking member 36, so that the motor 32 can be raised / lowered by driving the lifting / lowering means 34. At this time,
Motor 32, rotating shaft 31, rotating table 30, movable impeller 3
5 and the substrate W are moved up and down integrally. The substrate W is raised and lowered not during the cleaning process using the processing liquid, but during the loading / unloading of the substrate W and during the drying process described later.

Next, a gas supply mechanism for supplying IPA vapor or an inert gas to the closed chamber 10 will be described. Gas can be supplied to the closed chamber 10 by opening the gas supply valve 70. Gases that can be supplied in the substrate processing apparatus according to the present invention are IPA vapor and nitrogen as an inert gas.

When supplying IPA vapor to the closed chamber 10, flow control valves 74, I connected by piping to an IPA vapor generator provided inside or outside the apparatus are provided.
This is performed via a PA valve 73 and a gas supply valve 70. That is, by opening the IPA valve 73 and the gas supply valve 70, the IPA
Steam can be supplied. Note that nitrogen gas is used as a carrier gas for the IPA vapor.

When nitrogen gas, which is an inert gas, is supplied to the closed chamber 10, a flow rate adjusting valve 72, a nitrogen gas valve 71,
This is performed via a gas supply valve 70. That is, the nitrogen gas can be supplied into the closed chamber 10 by opening the nitrogen gas valve 71 and the gas supply valve 70.

The supply of the IPA vapor into the closed chamber 10 is for drying the substrate W. In the substrate processing apparatus according to the present invention, after the cleaning processing with pure water, the drying processing can be performed in the same apparatus without transporting the substrate W to another drying apparatus. That is, after or immediately before the end of the pure water cleaning process, the IPA vapor is supplied into the closed chamber 10 while the substrate W is immersed in the pure water. Then, after the inside of the closed chamber 10 is replaced with the IPA vapor atmosphere, the elevating means 34 is driven to move the substrate W into the processing tank 2.
Withdraw from pure water stored in 0.

In this case, since the lifting is performed in the IPA vapor atmosphere, the moisture adhering to the substrate W is quickly dried, and the generation of the gas-liquid interface on the substrate W can be suppressed. it can. In general, since the gas-liquid interface is in an active state, silicon of the substrate W is easily oxidized at the gas-liquid interface. However, by suppressing the generation of the gas-liquid interface, unnecessary oxidation does not occur. The generation of marks can be suppressed.

Since the cleaning process and the subsequent drying process are performed in one closed chamber 10, the substrate W is not exposed to the clean room atmosphere between the cleaning process and the drying process. There is no possibility that the substrate W after the cleaning treatment with the treatment liquid is contaminated by particles or gas contained in the atmosphere.

The drying process is not limited to lifting in an IPA vapor atmosphere, and the substrate W may be lifted from pure water containing IPA. That is,
When supplying pure water to the processing tank 20, the IPA valve 44 may be opened, and the mixing unit 43 may mix IPA into the pure water and supply the mixed water to the processing tank 20. Even in this case, when the substrate W is pulled up, the moisture adhering to the substrate W is quickly dried, and the generation of the gas-liquid interface on the substrate W can be suppressed. Can be suppressed.

On the other hand, the reason why nitrogen gas as an inert gas is supplied into the closed chamber 10 is to replace the atmosphere around the processing solution during the cleaning process with a nitrogen gas atmosphere. This can prevent oxygen and carbon dioxide from dissolving in the processing liquid from the atmosphere around the processing liquid, and can perform a cleaner cleaning process. In addition, it is possible to prevent the processing liquid from deteriorating and to increase the reliability and stability of the processing. The inert gas is not limited to nitrogen gas, and may be a gas having low reactivity with the processing liquid, for example, an argon gas.

The ultrasonic vibrator 2 is disposed on the outer surface of the side wall of the processing tank 20.
5 is attached. The ultrasonic vibrator 25 is connected to the processing tank 20.
Ultrasonic vibration can be applied to the processing liquid stored in the inside. During the cleaning process using the processing solution, the ultrasonic vibrator 2
By applying the ultrasonic vibration from 5, a higher-performance cleaning process can be performed.

As described above, the first embodiment of the present invention has been described. According to the substrate processing apparatus of the first embodiment, the substrate W is immersed in the processing liquid stored in the processing tank 20 to perform the rotary cleaning process. During the cleaning process, there is always a liquid film on the surface of the substrate W, and even if the supply amount of the chemical solution or pure water is reduced, the processing becomes uneven due to insufficient liquid film. It will not be.

Therefore, the supply amounts of the chemical solution and pure water can be reduced as compared with the conventional case, the consumption amounts of the chemical solution and pure water can be reduced, and the cost in the substrate processing step can be reduced.

Further, unlike the conventional single-wafer substrate cleaning apparatus, there is no concern that the processing liquid is shaken off by the centrifugal force due to the rotation of the substrate W, and the droplets are rebounded by the cup and adhere to the substrate W again. As a result, there is no possibility that particles or the like will adhere to the substrate W and contaminate the substrate W.

<2. Second Embodiment> FIG. 5 is a configuration diagram showing a substrate processing apparatus according to a second embodiment. This substrate processing apparatus also has a function of performing a cleaning process on the substrate W with a chemical solution and pure water, and further performing a drying process after the cleaning process.

The substrate processing apparatus of the second embodiment is different from the substrate processing apparatus of the first embodiment in that the processing liquid is supplied from above the processing tank 20 and discharged from below in the substrate processing apparatus of the first embodiment. On the other hand, in the substrate processing apparatus of the second embodiment, the processing liquid is supplied from below the processing tank 20 and discharged from above.

The processing liquid supply mechanism for supplying the processing liquid to the processing tank 20 includes a pure water valve 49, a chemical liquid valve 45, an IPA valve 44, a mixing section 43, a regulator 42, and a supply valve 4.
0, a movable impeller 35 and a supply pipe. When supplying pure water to the treatment tank 20, the supply valve 40 and a pure water valve 49 connected to a pure water supply source (not shown) are opened, and the chemical solution valve 45 and the IPA valve 44 are closed. Pure water is supplied to the pure water valve 49 and the mixing section 4
3, is supplied to the processing tank 20 via the regulator 42, the supply valve 40, and the movable impeller 35.

The processing tank 20 has a liquid level measuring device 47 for detecting the level of the processing liquid stored in the processing tank 20.
Is installed, and the liquid level measuring device 47 is electrically connected to the level controller 48. Then, similarly to the first embodiment, the level controller 48 controls the pure water supply amount according to the liquid level in the processing tank 20, and the liquid level is higher than the substrate W held on the turntable 30. And treatment tank 20
Adjust the height so that it does not overflow.

When pure water is supplied to the processing tank 20, I
Open PA valve 44 and mix IPA in pure water in mixing section 43
May be mixed and supplied to the processing tank 20,
This is the same as in the first embodiment.

On the other hand, when supplying a chemical solution to the processing tank 20, the supply valve 40 and the chemical solution valve 45 connected to a chemical solution supply source (not shown) are opened, and the pure water valve 49 and the IPA valve 44 are closed. Chemical solution is chemical solution valve 4
5, is supplied to the processing tank 20 via the mixing section 43, the regulator 42, the supply valve 40, and the movable impeller 35. Also at this time, the liquid level in the processing tank 20 is adjusted by the level controller 48 to be higher than the substrate W held on the turntable 30 and not to overflow from the processing tank 20.

As described above, in the second embodiment,
The processing liquid is supplied to the processing tank 20 via the movable impeller 35. The movable impeller 35 of the second embodiment has a different form from the first embodiment. FIG. 4 shows the movable impeller 3
It is a perspective view which shows the other example of 5 form. As is clear from comparison with FIG. 3, the movable impeller 35 of the second embodiment
The direction of the spiral of the four spiral blades 35a is the first
It is opposite to the movable impeller 35 of the embodiment. Therefore, when the rotating shaft 31 rotates clockwise, the processing liquid is sent upward from below by the spiral blade 35a.

As in the first embodiment, the rotation shaft 31 is rotated to transmit the rotation of the motor 32 to the substrate W. In the second embodiment, a movable impeller 35 is used.
The processing liquid is supplied to the processing tank 20 using the rotation of the rotating shaft 31. Therefore, a dedicated pump or the like for supplying the processing liquid is not required, and the substrate processing apparatus can be reduced in size and cost.

Further, by supplying the processing liquid using the movable impeller 35, the processing tank 20 is rotated while the processing liquid is swirled.
And the relative speed between the substrate W and the supplied processing liquid is increased, and the cleaning effect of the substrate W is enhanced. Although four spiral blades 35a are provided in FIG. 4 as well, the invention is not limited to this, and one or more spiral blades 35a may be attached.

Incidentally, the form of the fixed supply impeller 41 of the first embodiment may be the same as that shown in FIG. In the case of the fixed supply impeller 41, the helical blade 35a is not attached to the rotating shaft 31 but is attached to the fixed shaft in the same manner. However, when the fixed supply impeller 41 of the form shown in FIG. 4 is used,
The turning direction of the processing liquid is opposite to that in the case where the fixed supply impeller 41 having the form shown in FIG. 3 is used. Whether the embodiment shown in FIG. 3 or the embodiment shown in FIG. 4 is applied to the fixed supply impeller 41 is desirably determined according to the rotation direction of the substrate W.

If the rotation direction of the motor 32 is set to the counterclockwise direction, the movable impeller 35 of the form shown in FIG. 4 is used in the first embodiment, and the movable impeller 35 of the form shown in FIG. 3 is used in the second embodiment. It is also possible to use the impeller 35.

In the second embodiment, since the processing liquid is supplied from below the processing tank 20, excess processing liquid is supplied from the processing tank 2.
It overflows from above 0. The processing liquid overflowing from the processing tank 20 is collected by the outer tank 21 and discharged via the drain valve 50.

Further, in the second embodiment, the ultrasonic vibrator 25 is provided at a position different from that of the first embodiment. By applying ultrasonic vibration, a higher-performance cleaning process can be performed. Of course, the ultrasonic transducer 25 may be provided at the same position as in the first embodiment, in other words, the ultrasonic transducer 2
Reference numeral 5 may be set at a position where ultrasonic vibration can be applied to the processing liquid stored in the processing tank 20.

The remaining structure of the substrate processing apparatus according to the second embodiment is the same as that of the first embodiment, and a description thereof will be omitted.

According to the substrate processing apparatus of the second embodiment described above, the substrate W is contained in the processing liquid stored in the processing tank 20.
Is immersed in the rotary cleaning process, so that a liquid film always exists on the surface of the substrate W during the cleaning process, and even if the supply amount of the chemical solution or pure water is reduced, the liquid film becomes insufficient. The processing does not become uneven due to this.

Accordingly, the supply amounts of the chemical solution and pure water can be reduced as compared with the conventional case, the consumption of the chemical solution and pure water can be reduced, and the cost in the substrate processing step can be reduced.

Further, unlike the conventional single-wafer-type substrate cleaning apparatus, there is no concern that the processing liquid is shaken off by the centrifugal force due to the rotation of the substrate W, and the droplets are rebounded by the cup and adhere to the substrate W again. As a result, there is no possibility that particles or the like will adhere to the substrate W and contaminate the substrate W.

<3. Third Embodiment> FIG. 6 is a configuration diagram showing a substrate processing apparatus according to a third embodiment. This substrate processing apparatus also has a function of performing a cleaning process on the substrate W with a chemical solution and pure water, and further performing a drying process after the cleaning process.

The substrate processing apparatus of the third embodiment differs from the substrate processing apparatus of the first embodiment in that the processing liquid discharged through the drain valve 50 is circulated.

That is, the substrate processing apparatus of the third embodiment has a circulation mechanism including a circulation pump 51, a filter 52, and a circulation pipe. The circulation pump 51 sends the processing liquid discharged through the drain valve 50 again to the processing liquid supply mechanism. Further, the filter 52 is connected to the drain valve 50.
And has a function of removing particles and the like mixed in the processing liquid discharged through the processing liquid.

The processing liquid supply mechanism of the third embodiment includes a pure water valve 49, a chemical liquid valve 45, an IPA valve 44, a mixing section 43, a regulator 42, a supply valve 40, a fixed supply impeller 41, and a circulation pump. It comprises a valve 53 and a drain valve 54. When supplying the processing liquid newly, the circulation valve 53 and the drain valve 54 are closed, and the processing liquid is supplied in the same manner as in the first embodiment.

On the other hand, when circulating the processing liquid, the circulation valve 53 is opened, and the processing liquid supplied from the circulating mechanism is passed through the mixing section 43, the regulator 42, the supply valve 40, and the fixed supply impeller 41. To the treatment tank 20. At this time, new pure water or chemical liquid may be mixed with the processing liquid supplied from the circulation mechanism by opening the pure water valve 49 or the chemical liquid valve 45 as appropriate. The circulating treatment liquid can be discharged from the drain valve 54 in accordance with the amount of pure water or chemical liquid to be newly mixed.

In this manner, in addition to the same effects as those of the substrate processing apparatus of the first embodiment, a small amount of pure water or a chemical solution is mixed with the processing liquid discharged through the drain valve 50, and the processing is performed again. Since it is sufficient to supply the solution to the tank 20, it is possible to significantly reduce the consumption of the chemical solution and pure water.

In the third embodiment, the pure water valve 49, the chemical solution valve 45, the IPA valve 44, the mixing section 4
3. The circulation valve 53 and the drain valve 54 do not necessarily have to be individual members, but may be integrated valves.

The remaining configuration of the substrate processing apparatus according to the third embodiment is the same as that of the first embodiment, and a description thereof will be omitted.

<4. Fourth Embodiment> FIG. 7 is a configuration diagram showing a substrate processing apparatus according to a fourth embodiment. This substrate processing apparatus also has a function of performing a cleaning process on the substrate W with a chemical solution and pure water, and further performing a drying process after the cleaning process.

The substrate processing apparatus of the fourth embodiment differs from the substrate processing apparatus of the second embodiment in that the processing liquid discharged through the drain valve 50 is circulated.

That is, the substrate processing apparatus of the fourth embodiment has a circulation mechanism including a circulation pump 51, a filter 52, and a circulation pipe. The circulation pump 51 sends the processing liquid discharged through the drain valve 50 again to the processing liquid supply mechanism. Further, the filter 52 is connected to the drain valve 50.
And has a function of removing particles and the like mixed in the processing liquid discharged through the processing liquid.

The treatment liquid supply mechanism of the fourth embodiment includes a circulation valve 53 in addition to a pure water valve 49, a chemical liquid valve 45, an IPA valve 44, a mixing section 43, a regulator 42, a supply valve 40, and a movable impeller 35. And drain valve 54
It is constituted by. When a new processing liquid is supplied, the circulation valve 53 and the drain valve 54 are closed, and the processing liquid is supplied in the same manner as in the second embodiment.

On the other hand, when circulating the processing liquid, the circulation valve 53 is opened, and the processing liquid supplied from the circulating mechanism is processed through the mixing section 43, the regulator 42, the supply valve 40, and the movable impeller 35. Supply to tank 20. At this time, new pure water or chemical liquid may be mixed with the processing liquid supplied from the circulation mechanism by opening the pure water valve 49 or the chemical liquid valve 45 as appropriate. Also,
The circulating treatment liquid can be discharged from the drain valve 54 in accordance with the amount of pure water or chemical liquid to be newly mixed.

In this way, in addition to the same effects as the substrate processing apparatus of the second embodiment, a small amount of pure water or a chemical solution is mixed with the processing liquid discharged through the drain valve 50, and the processing is performed again. Since it is sufficient to supply the solution to the tank 20, it is possible to significantly reduce the consumption of the chemical solution and pure water.

In the fourth embodiment, the pure water valve 49, the chemical solution valve 45, the IPA valve 44, and the mixing unit 4
3. The circulation valve 53 and the drain valve 54 do not necessarily have to be individual members, but may be integrated valves.

The remaining structure of the substrate processing apparatus according to the fourth embodiment is the same as that of the second embodiment, and a description thereof will be omitted.

<5. Fifth Embodiment> FIG. 8 is a configuration diagram showing a substrate processing apparatus according to a fifth embodiment. This substrate processing apparatus also has a function of performing a cleaning process on the substrate W with a chemical solution and pure water, and further performing a drying process after the cleaning process.

The substrate processing apparatus according to the fifth embodiment is different from the substrate processing apparatus according to the first embodiment in that a motor 32 as a main part of a rotary drive mechanism is provided below the processing tank 20 in the substrate processing apparatus according to the first embodiment. On the other hand, in the substrate processing apparatus of the fifth embodiment, a hollow motor 82 is provided above the processing tank 20.

The processing liquid supply mechanism for supplying the processing liquid to the processing tank 20 includes a pure water valve 49, a chemical liquid valve 45, an IPA valve 44, a mixing unit 43, a regulator 42, and a supply valve 4.
0 and the supply pipe, and are the same as the first embodiment except for the fixed type supply impeller 41. However,
In the substrate processing apparatus of the fifth embodiment, the supply valve 4
0 to the hollow motor 82, the hollow rotary shaft 81 and the turntable 8
The processing liquid is supplied through the zero discharge port.

FIG. 9 is a sectional view showing a rotary drive mechanism of the substrate processing apparatus according to the fifth embodiment. The substrate W is placed in the processing tank 20.
And is held by a circular turntable 80 so as to be immersed in the processing liquid stored in the rotary table. The substrate W is provided with a plurality of pin-shaped substrate holding members 80a erected on the turntable 80.
Is held so as to grip the peripheral end portion of the substrate W, so that a certain interval is generated between the substrate W and the turntable 80. Here, the substrate holding member 80a is configured to be rotatable by driving the link member 85, and the substrate holding member 80a is rotated to urge the peripheral end portion of the substrate W to press the substrate W. Is held on the turntable 80 without falling.

The rotary table 80 has a hollow rotary shaft 81 suspended at the center of the upper surface side, and the hollow rotary shaft 81 is mounted on the hollow motor 8.
2 are connected. The rotation of the hollow motor 82 is transmitted to the turntable 80 via the hollow rotary shaft 81, and the substrate W held on the turntable 80 rotates about the vertical direction as an axis. In other words, the substrate W is rotated while the substrate W is held in the processing liquid by the turntable 80, whereby the substrate W is cleaned by the processing liquid.

As shown in FIG. 9, a hollow hole is provided through the center of each of the hollow motor 82 and the hollow rotary shaft 81. A discharge port 87 is provided at the center of the circular turntable 80. The holes of the hollow motor 82 and the hollow rotary shaft 81 and the discharge port 87 of the turntable 80 are made to coincide with each other, and these are configured as one path.

When supplying pure water to the processing tank 20, the supply valve 40 and a pure water valve 49 connected to a pure water supply source (not shown) are opened, and the chemical solution valve 45 and the IPA valve 44 are closed. Pure water is pure water valve 4
9, mixing section 43, regulator 42, supply valve 40,
It is supplied to the processing tank 20 via the hollow motor 82, the hollow rotary shaft 81 and the discharge port 87 of the turntable 80.

When supplying a chemical solution to the processing tank 20, the supply valve 40 and a chemical solution valve 45 connected to a chemical solution supply source (not shown) are opened, and the pure water valve 49 and the IPA valve 44 are closed. The chemical is supplied to the processing tank 20 through the chemical liquid valve 45, the mixing section 43, the regulator 42, the supply valve 40, the hollow motor 82, the hollow rotary shaft 81, and the discharge port 87 of the turntable 80.

Since the turntable 80 is a circular flat plate having a flat surface facing the main surface of the substrate W, the processing liquid discharged from the discharge port 87 flows along the gap between the substrate W and the turntable 80. Will flow. As a result, fresh processing liquid is directly supplied to the main surface of the substrate W, and the cleaning effect on the main surface is enhanced.

On the other hand, when discharging the processing liquid stored in the processing tank 20, the drain valve 50 is opened,
The liquid is discharged out of the apparatus by operating the drainage pump 59.

The lifting and lowering of the substrate W is performed by lifting means 34 fixed to the closed chamber 10. That is, the hollow motor 82 is connected to the lifting / lowering means 34 by the locking member 36, and the hollow motor 8 is driven by the lifting / lowering means 34.
2. The hollow rotary shaft 81, the turntable 80, and the substrate W are integrally moved up and down.

In the substrate processing apparatus according to the fifth embodiment,
Since the hollow motor 82 is provided above the processing tank 20,
The rotation shaft does not penetrate the bottom of the processing tank 20, and FIG.
A member for preventing the processing liquid from leaking from the processing tank 20, such as the sealing member 62, is not required, and the configuration of the apparatus can be simplified.

The remaining structure of the substrate processing apparatus according to the fifth embodiment is the same as that of the first embodiment, and a description thereof will be omitted.

According to the substrate processing apparatus of the fifth embodiment described above, the substrate W is contained in the processing liquid stored in the processing tank 20.
Is immersed in the rotary cleaning process, so that a liquid film always exists on the surface of the substrate W during the cleaning process, and even if the supply amount of the chemical solution or pure water is reduced, the liquid film becomes insufficient. The processing does not become uneven due to this.

Therefore, the supply amount of the chemical solution or pure water can be reduced as compared with the conventional case, the consumption amount of the chemical solution or pure water can be reduced, and the cost in the substrate processing step can be reduced.

Further, unlike the conventional single-wafer substrate cleaning apparatus, there is no concern that the processing liquid is shaken off by the centrifugal force due to the rotation of the substrate W, and the droplets are rebounded by the cup and adhere to the substrate W again. As a result, there is no possibility that particles or the like will adhere to the substrate W and contaminate the substrate W.

<6. Sixth Embodiment> FIG. 10 is a configuration diagram showing a substrate processing apparatus according to a sixth embodiment. This substrate processing apparatus also has a function of performing a cleaning process on the substrate W with a chemical solution and pure water, and further performing a drying process after the cleaning process.

The substrate processing apparatus of the sixth embodiment is different from the substrate processing apparatus of the fifth embodiment in that the processing liquid is supplied from above the processing tank 20 and discharged from below in the substrate processing apparatus of the fifth embodiment. On the other hand, in the substrate processing apparatus of the sixth embodiment, the processing liquid is supplied from below the processing tank 20 and discharged from above.

The processing liquid supply mechanism for supplying the processing liquid to the processing tank 20 includes a pure water valve 49, a chemical liquid valve 45, an IPA valve 44, a mixing section 43, a regulator 42, and a supply valve 4.
0, a supply pump 58 and a supply pipe. That is, the processing liquid supply mechanism of the sixth embodiment has a configuration similar to that of the processing liquid supply mechanism of the second embodiment (see FIG. 5). However, in the sixth embodiment, the processing liquid is supplied using the supply pump 58 because the movable impeller 35 is not provided.

When supplying pure water to the treatment tank 20, the supply valve 40 and the pure water valve 49 connected to a pure water supply source (not shown) are opened, and the chemical liquid valve 45 and the IPA are supplied.
The valve 44 is closed. The pure water is supplied to the processing tank 20 via the pure water valve 49, the mixing section 43, the regulator 42, the supply pump 58, and the supply valve 40.

On the other hand, when supplying a chemical solution to the processing tank 20, the supply valve 40 and the chemical solution valve 45 connected to a chemical solution supply source (not shown) are opened, and the pure water valve 49 and the IPA valve 44 are closed. Chemical solution is chemical solution valve 4
5, is supplied to the processing tank 20 via the mixing section 43, the regulator 42, the supply pump 58 and the supply valve 40.

In the sixth embodiment, as in the second embodiment, the processing liquid is supplied from below the processing tank 20.
Excess processing liquid overflows from above the processing tank 20. The processing liquid overflowing from the processing tank 20 is collected by the outer tank 21 and discharged via the drain valve 50.

The rotary drive mechanism of the sixth embodiment is the same as that of the fifth embodiment. However, in the sixth embodiment, since the processing liquid does not pass through the inside of the rotary drive mechanism, the hollow motor 82 and the hollow rotary shaft 81 do not necessarily need to be hollow. Further, it is not always necessary to provide the discharge port 87 for the turntable 80.

In the substrate processing apparatus of the sixth embodiment,
Since the hollow motor 82 is provided above the processing tank 20,
The rotation shaft does not penetrate the bottom of the processing tank 20, and FIG.
A member for preventing the processing liquid from leaking from the processing tank 20, such as the sealing member 62, is not required, and the configuration of the apparatus can be simplified.

The remaining structure of the substrate processing apparatus according to the fifth embodiment is the same as that of the first embodiment, and a description thereof will be omitted.

<7. Modifications> While the preferred embodiments of the present invention have been described above, the present invention is not limited to the above-described examples. For example, a circulation mechanism as in the third or fourth embodiment may be provided in the substrate processing apparatus of the fifth or sixth embodiment. If a circulation mechanism is provided, a small amount of pure water or a chemical solution may be mixed with the processing liquid discharged through the drain valve 50 and then supplied to the processing tank 20 again. It becomes possible to reduce to.

Further, a hollow motor is applied to the motor 32 of the substrate processing apparatus according to the second or fourth embodiment, a hollow rotary shaft is applied to the rotary shaft 31, and a discharge port is provided on the rotary base 30. You may. As in the fifth embodiment, fresh processing liquid is directly supplied to the main surface of the substrate W, and the cleaning effect on the main surface is enhanced.

[0118]

As described above, according to the first aspect of the present invention, a processing tank for storing a processing liquid, processing liquid supply means for supplying the processing liquid to the processing tank, and discharging the processing liquid from the processing tank. A processing liquid discharge unit, a substrate holding unit disposed in the processing bath, and holding the substrate in the processing liquid stored in the processing bath, and a substrate held in the processing liquid by the substrate holding unit. Liquid rotation means for rotating the holding means, the liquid film always exists on the surface of the substrate during processing, and even if the supply amount of the processing liquid is reduced, the liquid film is insufficient. The processing does not become uneven. As a result, the supply amount of the processing liquid can be reduced as compared with the conventional case, the consumption amount of the processing liquid can be reduced, and the cost in the substrate processing step can be reduced.

Further, there is no concern that the processing liquid is shaken off by the centrifugal force due to the rotation of the substrate, and the droplets scatter and adhere to the substrate again. As a result, there is no possibility that particles and the like will adhere to the substrate and contaminate the substrate.

According to the second aspect of the present invention, since the closed chamber accommodating the processing tank is provided, the atmosphere of the clean room is not introduced into the closed chamber.
There is no possibility that the substrate during or after substrate processing is contaminated by particles or gas contained in the atmosphere.

According to the third aspect of the present invention, since the closed chamber is provided with the organic solvent vapor supply means for supplying the vapor of the organic solvent for drying the processing liquid, the processing liquid adhering to the substrate is provided. Is quickly dried to suppress the generation of a gas-liquid interface, and accordingly, unnecessary oxidation does not occur. As a result, generation of a so-called watermark can be suppressed.

According to the fourth aspect of the present invention, since the inert gas supply means for supplying an inert gas into the closed chamber is provided, the atmosphere around the processing liquid is replaced with the inert gas atmosphere. As a result, it is possible to prevent oxygen and carbon dioxide from being dissolved in the processing liquid from the atmosphere around the processing liquid, and to perform a cleaner cleaning treatment. In addition, it is possible to prevent the processing liquid from deteriorating and to increase the reliability and stability of the processing.

According to the fifth aspect of the present invention, since there is provided a circulation path for returning the processing liquid discharged by the processing liquid discharging means to the processing liquid supply means and supplying the processing liquid again to the processing tank, Can be greatly reduced.

According to the sixth aspect of the present invention, since the rotary driving means is disposed above the processing tank, it is possible to prevent the processing liquid from leaking from a portion of the processing tank through which the rotary driving means penetrates. No member is required, and the configuration of the device can be simplified.

According to the seventh aspect of the present invention, since the discharge port for discharging the processing liquid supplied from the processing liquid supply means to the main surface of the substrate is provided in the substrate holding plate, fresh processing liquid can be directly supplied. Since it is supplied to the main surface of the substrate, the processing effect on the main surface is enhanced.

According to the eighth aspect of the present invention, since the processing liquid is supplied to the processing tank by the rotation of the supply impeller fixed to the rotating shaft of the rotation driving means, the processing liquid is supplied. This eliminates the need for a dedicated pump or the like, which can reduce the size of the apparatus and lead to cost reduction. Further, the processing liquid can be supplied to the processing tank while swirling, the relative speed between the substrate and the supplied processing liquid increases, and the processing effect of the substrate can be enhanced.

According to the ninth aspect of the present invention, since the processing liquid stored in the processing tank is discharged by the rotation of the discharge impeller fixedly mounted on the rotating shaft of the rotary driving means, the processing liquid is discharged. This eliminates the need for a dedicated pump or the like for discharging, so that the apparatus can be reduced in size and cost.

According to the tenth aspect of the present invention, since the processing liquid is supplied to the processing tank via the supply impeller fixedly provided, the processing liquid can be supplied to the processing tank while rotating. As a result, the relative speed between the substrate and the supplied processing liquid is increased, and the processing effect of the substrate can be enhanced.

According to the eleventh aspect of the present invention, since the ultrasonic vibrator for applying ultrasonic vibration to the processing liquid in the processing tank is attached to the processing tank, when the processing is a cleaning processing,
Higher-performance cleaning processing becomes possible.

[Brief description of the drawings]

FIG. 1 is a configuration diagram illustrating an example of a substrate processing apparatus according to the present invention.

FIG. 2 is a view showing a seal portion of a processing tank of the substrate processing apparatus of FIG.

FIG. 3 is a perspective view showing an example of a form of a movable impeller of the substrate processing apparatus of FIG.

FIG. 4 is a perspective view showing another example of the form of the movable impeller.

FIG. 5 is a configuration diagram illustrating a substrate processing apparatus according to a second embodiment.

FIG. 6 is a configuration diagram illustrating a substrate processing apparatus according to a third embodiment.

FIG. 7 is a configuration diagram illustrating a substrate processing apparatus according to a fourth embodiment.

FIG. 8 is a configuration diagram illustrating a substrate processing apparatus according to a fifth embodiment.

FIG. 9 is a cross-sectional view illustrating a rotation drive mechanism of a substrate processing apparatus according to a fifth embodiment.

FIG. 10 is a configuration diagram illustrating a substrate processing apparatus according to a sixth embodiment.

FIG. 11 is a view illustrating a conventional single-wafer substrate cleaning apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Closed chamber 20 Processing tank 30 Turntable 32 Motor 25 Ultrasonic vibrator 35 Movable impeller 40 Supply valve 41 Fixed supply impeller 50 Drainage valve 51 Circulation pump 53 Circulation valve 71 Nitrogen gas valve 73 IPA valve 82 Hollow motor 87 Discharge port W Substrate

Claims (11)

[Claims] 1. A substrate processing apparatus for performing a predetermined processing on a substrate while using a processing liquid, comprising: (a) a processing tank for storing the processing liquid; and (b) a processing tank for storing the processing liquid in the processing tank. (C) a processing liquid discharging means for discharging the processing liquid from the processing tank, (d) disposed in the processing tank, and within the processing liquid stored in the processing tank. Substrate holding means for holding the substrate, and (e) rotation driving means for rotating the substrate holding means in a state where the substrate is held in the processing liquid by the substrate holding means. Substrate processing apparatus. 2. The substrate processing apparatus according to claim 1, further comprising: (f) a closed chamber containing the processing tank. 3. The substrate processing apparatus according to claim 2, further comprising: (g) an organic solvent vapor supply means for supplying a vapor of an organic solvent for drying the processing liquid into the closed chamber. Substrate processing equipment. 4. The substrate processing apparatus according to claim 2, further comprising: (h) inert gas supply means for supplying an inert gas into the closed chamber. 5. The substrate processing apparatus according to claim 1, wherein: (i) the processing liquid discharged by the processing liquid discharging means is returned to the processing liquid supply means, and the processing liquid is returned to the processing liquid supply means. A substrate processing apparatus further comprising a circulation path for supplying the processing tank. 6. The substrate processing apparatus according to claim 1, wherein the rotation driving unit is disposed above the processing tank. 7. The substrate processing apparatus according to claim 1, wherein the substrate holding unit includes a substrate holding plate having a surface facing a main surface of the held substrate. The substrate processing apparatus, wherein the substrate holding plate has a discharge port for discharging the processing liquid supplied from the processing liquid supply unit to the main surface. 8. The substrate processing apparatus according to claim 1, wherein the rotation driving unit is disposed below the processing tank, and the processing liquid supply unit is provided in the rotation driving unit. A substrate processing apparatus, comprising: a supply impeller fixed to a rotating shaft, wherein the processing liquid is supplied to the processing tank by rotation of the supply impeller. 9. The substrate processing apparatus according to claim 1, wherein the rotation driving unit is disposed below the processing tank, and wherein the processing liquid discharging unit is provided with the rotation driving unit. A substrate processing apparatus, comprising: a discharge impeller fixedly mounted on a rotating shaft, wherein the processing liquid stored in the processing tank is discharged by rotation of the discharge impeller. 10. The substrate processing apparatus according to claim 1, wherein the processing liquid supply unit includes a supply impeller fixedly provided above the processing tank. A substrate processing apparatus, wherein the processing liquid is supplied to the processing tank via a supply impeller. 11. The substrate processing apparatus according to claim 1, wherein an ultrasonic vibrator for applying ultrasonic vibration to the processing liquid in the processing tank is provided in the processing tank. A substrate processing apparatus characterized by the above-mentioned.