JPH11264756A - Level detector and level detecting method, and substrate processing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To miniaturize a detector and to continuously detect an optional level with a high precision by extending an optical fiber in a liquid, and detecting the light that reaches the tip part of the optical fiber while successively reflected by the inner wall, and is reflected by the tip part and returned while successively reflected. SOLUTION: A level detecting sensor 80 comprises a sensor body 83 having a light emitting part 81 and a light receiving part 32, and an optical fiber 84 extended from the sensor body 83 to a liquid, the optical fiber 84 having a reflecting surface 84 formed on the tip. The light emitted from the light emitting part 81 toward the inner wall of the optical fiber 84 reaches the tip part while successively reflected by the inner wall, reflected by the reflecting surface 85, and returned to the sensor body 83 while successively reflected by the inner wall, and detected by the light receiving part 82. The refractive index of the inner wall of the optical fiber 84 is varied between the part exposed to a liquid and a part exposed to air, and according to this, the intensity of the reflected light is changed. Thus, the intensity of the reflected light changed following the change of liquid level is detected by the light receiving part 82, whereby an optional liquid level can be continuously analogously detected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid level detector and a liquid level detection method for detecting a liquid level in a tank or the like, and a substrate processing apparatus using the liquid level detector.

[0002]

2. Description of the Related Art In a coating / developing processing system for a photolithography step in a semiconductor device manufacturing process, a semiconductor wafer (hereinafter, referred to as "wafer") is subjected to a cleaning treatment and a hydrophobic treatment, and then cooled by a cooling unit. Then, a resist solution is applied to the wafer by a resist application unit. Thereafter, the wafer is subjected to a pre-baking process in a heat treatment unit, cooled in a cooling unit, and then conveyed to an exposure apparatus via an interface unit, where a predetermined pattern is exposed. After exposure, the wafer is transported again into the system via the interface unit, subjected to post-exposure bake processing in the heating processing unit, and then subjected to development processing in the development processing unit for the wafer cooled in the cooling unit to form a predetermined circuit pattern on the wafer. I do.

[0003] In the various processing units described above, various tanks storing liquids such as a resist solution, a developing solution, and a drainage solution are used, and the liquid level in such a tank is detected by a liquid level detecting sensor. doing. As such a liquid level detection sensor, for example, a sensor using a floating sensor and a sensor using an optical sensor and an optical fiber are known.

When the liquid level in the tank is detected by a floating sensor, the float is floated on the liquid in the tank, and the inclination angle of the float, which changes according to the liquid level, is mechanically detected. Detect the liquid level in the inside.

When the liquid level is detected by a liquid level detecting sensor using an optical sensor and an optical fiber, an optical fiber extending from a sensor main body having a light emitting portion and a light receiving portion is arranged vertically in the liquid to emit light. The light emitted from the section is guided to the tip of the optical fiber. The refractive index of light differs between when the tip of the optical fiber comes into contact with air and when it comes into contact with liquid.If the liquid level is high and the tip of the optical fiber is immersed in the liquid, the light flows from the tip of the optical fiber into the liquid. When the liquid level is lowered and the tip of the optical fiber comes out into the air, the light is reflected at the tip of the optical fiber. Therefore,
The liquid level can be detected by detecting the reflected light at the light receiving section. Such an optical sensor and a liquid level detection sensor using an optical fiber have advantages that they are small, can accurately detect the liquid level, and have heat resistance.

[0006]

However, in the above-described liquid level detection sensor of the floating sensor, the liquid level is mechanically detected by a change in the tilt angle of the float. In the case where the liquid level is scratched, there is a problem that the liquid level cannot be accurately detected. Also,
Since the float needs to float on the liquid surface, it needs a relatively large volume, and tends to hinder work in the tank.

The liquid level detecting sensor using an optical sensor and an optical fiber has the above-mentioned advantages, but is configured to detect reflected light only when the liquid level reaches a predetermined level. Therefore, as in the case of detecting whether or not the liquid level has reached a predetermined level, one optical sensor can detect only one liquid level. Therefore, there is a problem that it is not possible to meet the recent demand for detecting a plurality of liquid levels with one optical sensor.

The present invention has been made in view of such circumstances, and a liquid level detector capable of accurately detecting a plurality of liquid levels and being miniaturized, and such a liquid level detector. An object of the present invention is to provide a substrate processing apparatus using the same. It is another object of the present invention to provide a liquid level detection method capable of detecting a plurality of liquid levels with high accuracy.

[0009]

According to a first aspect of the present invention, light is emitted from a light emitting portion to an optical fiber extending into a liquid stored in a container, and is reflected at a tip portion of the optical fiber. In a liquid level detector that detects reflected light by a light receiving unit and detects a liquid level in a container, light is emitted from the light emitting unit toward the inner wall of the optical fiber, and the tip of the optical fiber is sequentially reflected by the inner wall of the optical fiber. A liquid level detector, wherein the reflected light is reflected by an inner wall of the optical fiber after returning to the optical fiber, and the reflected light is detected by the light receiving unit.

According to a second aspect of the present invention, there is provided a liquid level detector for detecting a liquid level of a liquid stored in a container, wherein the light emitting unit emits light, and the light emitting unit extends into the liquid stored in the container. Then, the light emitted from the light emitting unit is sequentially reflected on the inner wall to reach the distal end, and the reflected light reflected on the distal end is returned while being sequentially reflected on the inner wall, and the optical fiber is returned while being reflected on the inner wall of the optical fiber. And a light-receiving unit for detecting reflected light.

According to a third aspect of the present invention, in the liquid level detector according to the first or second aspect, based on the relationship between the liquid level detected in advance and the intensity of the reflected light, the level of the reflected light is calculated from the detected intensity of the reflected light. The liquid level detector further comprises a calculating means for calculating the following formula.

According to a fourth aspect of the present invention, in the liquid level detector according to any one of the first to third aspects, the optical fiber has a reflecting surface for reflecting light at a tip end thereof. A liquid level detector is provided.

According to a fifth aspect of the present invention, light is emitted from a light emitting portion to an optical fiber extending into a liquid stored in a container, and light reflected at a tip portion of the optical fiber is detected by a light receiving portion, and the liquid in the container is detected. In the liquid level detection method for detecting a surface level, light is emitted from the light emitting section toward the inner wall of the optical fiber, and reaches the tip of the optical fiber while being sequentially reflected on the inner wall of the optical fiber. A liquid level detection method is provided, wherein the reflected light is detected by the light receiving portion while being sequentially reflected by an inner wall.

According to a sixth aspect, in the liquid level detecting method according to the fifth aspect, the liquid level is obtained from the detected intensity of the reflected light based on a relationship between the liquid level and the intensity of the reflected light obtained in advance. A liquid level detection method is provided.

According to a seventh aspect of the present invention, there is provided a processing section for performing a predetermined process on a substrate using a processing liquid stored in a processing liquid container, and a processing liquid disposed in the processing liquid container and stored in the processing liquid container. A liquid level detector for detecting the liquid level of
The liquid level detector is a light emitting unit that emits light, and is extended into the processing liquid stored in the processing liquid container, and causes the light emitted from the light emitting unit to reach the distal end while being sequentially reflected by the inner wall. A substrate processing apparatus comprising: an optical fiber for returning the reflected light reflected on the tip portion while sequentially reflecting the reflected light on the inner wall; and a light receiving unit for detecting the reflected light returned while reflecting on the inner wall of the optical fiber. .

According to an eighth aspect of the present invention, there is provided a processing section for performing a predetermined process on a substrate with a liquid and storing the drainage in a drainage container, and disposed in the drainage container. A liquid level detector for detecting the liquid level of the stored drainage, the liquid level detector is a light emitting unit that emits light, and extends into the drainage stored in the container, An optical fiber that causes the light emitted from the light emitting section to reach the tip while being sequentially reflected by the inner wall, and that reflects the reflected light that is reflected by the tip sequentially while being reflected by the inner wall, and a reflection that returns while being reflected by the inner wall of the optical fiber. A substrate processing apparatus comprising: a light receiving unit that detects light.

According to a ninth aspect of the present invention, in the substrate processing apparatus of the seventh or eighth aspect, the liquid level detector detects the reflected light detected based on a relationship between a predetermined liquid level and the intensity of the reflected light. A substrate processing apparatus further comprising a calculating means for calculating a liquid level from the intensity of the substrate.

A tenth aspect of the present invention is the substrate processing apparatus according to any one of the seventh to ninth aspects, wherein the optical fiber has a reflection surface for reflecting light at a tip end thereof. A processing device is provided.

According to the first invention, the second invention and the fifth invention, light is emitted from the light emitting portion toward the inner wall of the optical fiber, and reaches the tip of the optical fiber while being sequentially reflected by the inner wall of the optical fiber. After the light is reflected by the optical fiber, the reflected light is sequentially reflected by the inner wall of the optical fiber and returned, and the reflected light is detected by the light receiving unit. Generally, the optical fiber has a different refractive index of the inner wall between when it comes into contact with air and when it comes into contact with liquid, so that, for example, as the liquid level gradually drops, the optical fiber immersed in the liquid When the part touches the liquid surface and then touches the air, the refractive index changes on the inner wall of the optical fiber, and the reflected light reflected on the inner wall of the optical fiber corresponding to the change in the refractive index. Changes in intensity. Therefore, when the liquid level changes, the intensity of the reflected light changes accordingly. By detecting the intensity of the reflected light, it is possible to continuously detect any liquid level with high accuracy. it can. As a result, a plurality of liquid levels can be accurately detected, and the liquid level can be continuously monitored. Further, the liquid level detector according to the first or second aspect of the present invention uses an optical fiber, so that the size can be reduced.

Further, since there is a certain relation between the liquid level and the intensity of the reflected light, according to the third, sixth and ninth inventions, by obtaining this relation in advance, The liquid level can be calculated from the intensity of the reflected light.

According to the fourth and tenth aspects of the present invention, the light emitted from the light emitting section and reflected by the inner wall and reaching the tip can be reflected by the reflecting surface provided at the tip of the optical fiber.

According to the seventh aspect, since the liquid level detector is provided in the processing liquid container of the substrate processing apparatus, an arbitrary liquid level of the processing liquid container is continuously and accurately detected. be able to. Therefore, it is possible to accurately detect a plurality of liquid levels of the processing liquid container, and it is also possible to continuously monitor the liquid levels of the processing liquid container.

According to the eighth aspect of the present invention, since the above liquid level detector is provided in the drainage container of the substrate processing apparatus, an arbitrary liquid level of the drainage container is continuously and accurately detected. be able to. Therefore, it is possible to accurately detect a plurality of liquid levels of the drainage container, and to continuously monitor the liquid levels of the drainage container.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIGS. 1 to 3 are diagrams showing the overall configuration of a coating / developing system for a semiconductor wafer (hereinafter, referred to as “wafer”) to which an embodiment of the present invention is applied. FIG. 3 shows the front, and FIG. 3 shows the back.

As shown in FIG. 1, the coating / developing system 1 loads a plurality of wafers W as substrates to be processed in a wafer cassette CR, for example, into the system in units of 25 wafers W, or unloads wafers from the system. A cassette station 10 for loading and unloading wafers W into and out of the wafer cassette CR, and various single-wafer processing units for performing predetermined processing on the wafers W one by one in a coating and developing process. An interface unit 12 for transferring a wafer W between a processing station 11 arranged in multiple stages at a predetermined position and an exposure apparatus (not shown) provided adjacent to the processing station 11 is integrally connected. It has a configuration.

In the cassette station 10, FIG.
As shown in FIG.
At a position 0a, a plurality of wafer cassettes CR, for example, up to four wafer cassettes CR are placed in a line in the X direction with their respective wafer entrances facing the processing station 11 side. A wafer carrier 21 that can move in the wafer arrangement direction (Z direction: vertical direction) of the wafers stored in the cassette selectively accesses each wafer cassette CR.

Further, the wafer transfer body 21 is rotatable in the θ direction, and as will be described later, an alignment unit (ALIM) belonging to the multi-stage unit section of the third processing unit group G ₃ on the processing station 11 side. And an extension unit (EXT).

As shown in FIG. 1, the processing station 11 is provided with a vertical transfer type main wafer transfer mechanism 22 equipped with a wafer transfer device, and all the processing units are surrounded by one or more sets. Are arranged in multiple stages.

As shown in FIG. 3, the main wafer transfer mechanism 22 is provided with a wafer transfer device 46 inside a tubular support 49 so as to be able to move up and down in the vertical direction (Z direction). The cylindrical support 49 is connected to a rotation shaft of a motor (not shown), and is rotated integrally with the wafer transfer device 46 about the rotation shaft by the rotation driving force of the motor, whereby the wafer transfer is performed. The device 46 is rotatable in the θ direction.

The wafer transfer device 46 includes a plurality of holding members 48 movable in the front-rear direction of the transfer base 47, and the transfer of the wafer W between the processing units is realized by these holding members 48. .

In this example, as shown in FIG.
One processing unit group G ₁ , G ₂ , G ₃ , G ₄ , G ₅ can be arranged, and the multi-stage units of the first and second processing unit groups G ₁ , G ₂ are arranged in front of the system (FIG. 1). , The multi-stage unit of the _third processing unit group G ₃ is arranged adjacent to the cassette station 10, and the multi-stage unit of the fourth processing unit group G ₄ is arranged adjacent to the interface unit 12. The multi-stage units of the _fifth processing unit group G5 can be arranged on the back side.

As shown in FIG. 2, in the first processing unit group G ₁ , two spinner type processing units, for example, a resist coating unit (FIG. 2) for performing a predetermined processing by placing the wafer W on a spin chuck in the cup CP. COT) and the development processing unit (DEV) are stacked in two stages from the bottom. Second processing even unit group G _2, two spinner-type processing units, for example, a resist coating unit (CO
T) and the development processing unit (DEV) are 2
It is piled up on the steps. These resist coating units (C
OT) is preferably disposed at the lower stage in this way, since the drainage of the resist solution is troublesome both mechanically and for maintenance. However, it is of course possible to appropriately arrange the upper stage as needed.

As shown in FIG. 3, in the third processing unit group G ₃ , an oven-type processing unit for performing a predetermined process by mounting the wafer W on the mounting table SP, for example, a cooling unit (COL) for performing a cooling process , An adhesion unit (AD) for performing a so-called hydrophobizing process for improving the fixability of a resist, an alignment unit (ALIM) for positioning, and an extension unit (EX)
T), a pre-baking unit (PREBAKE) for performing a heating process before the exposure process and a post-baking unit (POBAKE) for performing a heating process after the exposure process are stacked in, for example, eight stages from the bottom.

In the fourth processing unit group G ₄ , an oven type processing unit, for example, a cooling unit (CO
L), extension cooling unit (EXT
COL), an extension unit (EXT), a cooling unit (COL), a pre-baking unit (PREBAKE), and a post-baking unit (POBAKE) are stacked in order from the bottom, for example, in eight stages.

As described above, the cooling unit (COL) and the extension cooling unit (EXTCOL) having a low processing temperature are arranged in the lower stage, and the baking unit (PREBAKE), the post-baking unit (POBAKE) and the adhesion having a high processing temperature are arranged. By arranging the units (AD) in the upper stage, thermal mutual interference between the units can be reduced. Of course, a random multi-stage arrangement may be used.

As shown in FIG. 1, the interface section 12 has the same dimensions as the processing station 11 in the depth direction (X direction), but is set smaller in the width direction. A portable pickup cassette CR and a stationary buffer cassette BR are provided in front of the interface section 12.
On the other hand, a peripheral exposing device 23 is arranged on the back side, and a wafer carrier 24 is provided on the central part. The wafer carrier 24 moves in the X and Z directions to move the cassettes CR and BR and the peripheral exposure device 2.
3 is accessed. The wafer transfer body 24 is configured to be rotatable also in the θ direction, and includes an extension unit (EXT) belonging to a multi-stage unit of the fourth processing unit group G4 on the processing station 11 side, and further, The wafer delivery table (not shown) on the adjacent exposure apparatus side can also be accessed.

In the coating / developing processing system 1,
As shown in FIG. 1, a multi-stage unit of a _fifth processing unit group G5 shown by a broken line can be arranged on the back side of the main wafer transfer mechanism 22 as described above.
The multi-stage unit of the processing unit group G _5, the guide rail 2
When viewed from the main wafer transfer mechanism 22 along the line 5, it can be shifted to the side. Therefore, this fifth
Even when provided as shown multistage unit of the processing unit group G ₅ of, by sliding along the guide rail 25, the space portion can be secured, maintenance work from behind the main wafer transfer mechanism 22 Can be easily performed.

Next, the developing unit (DEV) according to the present embodiment will be described. 4 and 5 are a schematic sectional view and a schematic plan view showing the entire configuration of the developing unit (DEV).

An annular cup CP is disposed at the center of the developing unit (DEV), and a spin chuck 52 is disposed inside the cup CP. The spin chuck 52 is rotationally driven by a drive motor 54 in a state where the wafer W is fixedly held by vacuum suction. The drive motor 54 is disposed at an opening of the unit bottom plate 50 so as to be able to move up and down, and is connected to a lift drive means 60 and a lift guide means 62 such as an air cylinder via a cap-like flange member 58 made of, for example, aluminum. . A cylindrical cooling jacket 64 made of, for example, SUS is attached to a side surface of the drive motor 54, and a flange member 58 is attached so as to cover an upper half of the cooling jacket 64.

When the developing solution is applied, the lower end of the flange member 58 is in close contact with the unit bottom plate 50 near the outer periphery of the opening of the unit bottom plate 50, thereby sealing the inside of the unit.
When the wafer W is transferred between the spin chuck 52 and the main wafer transfer mechanism 22, the lifting drive means 60 lifts the drive motor 54 or the spin chuck 52 to move the lower end of the flange member 58 to the unit bottom plate 5.
It floats from zero.

A developer supply nozzle 66 for supplying a developer to the surface of the wafer W is connected to a developer supply unit (not shown) via a developer supply pipe 68. The developer supply nozzle 66 is detachably attached to the tip of the nozzle scan arm 70 via a nozzle holder 76. The scan arm 70 is attached to the upper end of a vertical support member 74 that can move horizontally on a guide rail 72 laid in one direction (Y direction) on the unit bottom plate 50, and a Y direction drive mechanism (not shown) Thereby, it moves in the Y direction integrally with the vertical support member 74.

The developer supply nozzle 66 extends linearly in the radial direction of the wafer W, as shown in FIG.
The developer is sprayed in a belt shape. Thus, when the developing solution is applied, the developing solution is applied to the entire surface of the wafer W by, for example, one rotation of the wafer W while the developing solution is sprayed from the developing solution supply nozzle 66 in a band shape. The developer supply nozzle 66 may be a plurality of nozzles arranged in parallel, or may be a slit nozzle. The developer supply nozzle 66 is not limited to these, and may be another type. Further, a rinse nozzle 78 for discharging the cleaning liquid is provided, and the rinse nozzle 78 is attached to the tip of a nozzle scan arm 79 provided movably on the guide rail 72 in the Y direction. Thus, after the completion of the developing process with the developing solution, the cleaning solution is moved onto the wafer W and the cleaning solution is discharged onto the wafer W.

Next, the operation of the development processing in the development processing unit (DEV) will be described. The wafer W having a predetermined pattern exposed and subjected to post-exposure bake processing and cooling processing is transferred to a position directly above the cup CP by the main wafer transfer mechanism 22 and is vacuum-sucked to the spin chuck 52 raised by the lifting drive unit 60. . Next, the developer supply nozzle 66 moves above the wafer W,
The developing solution is applied to the entire surface of the wafer W to a thickness of, for example, 1 mm by rotating the wafer W, for example, once while the developing solution is sprayed from the developing solution supply nozzle 66 in a strip shape. Thereafter, the wafer W is rotated at a relatively low speed by the spin chuck 52, the developing solution is stirred, and the developing process is performed. When the development process is completed, the developer supply nozzle 6
6 and the stirring member 106 are moved to the retreat position.

Next, the wafer W is rotated by the spin chuck 52, and the developer is shaken off and discarded. Thereafter, the rinse nozzle 78 is moved above the wafer W, and the cleaning liquid is discharged from the rinse nozzle 78 to wash away the developer remaining on the wafer W. Next, the spin chuck 52 is rotated at a high speed, the developing solution and the cleaning solution remaining on the wafer W are blown off, and the wafer W is dried. Thus, a series of development processing ends.

Next, a liquid level detecting sensor according to an embodiment of the present invention will be described with reference to FIGS. FIG.
FIG. 7 is a cross-sectional view of a liquid level detection sensor according to the embodiment of the present invention, FIG. 7 is a cross-sectional view of a developer supply tank equipped with the liquid level detection sensor shown in FIG. 6, and FIG. FIG.
3 is a cross-sectional view of two drainage tanks each equipped with a liquid level detection sensor shown in FIG.

The development processing unit (DEV) shown in FIG.
, A developer supply nozzle 66 for supplying a developer to the surface of the wafer W is provided via a developer supply pipe 68.
A drain passage 65 which is connected to a developer supply tank 91 as shown in FIG. 7 and is provided below the annular cup CP for discharging the drainage is provided with a drainage tank 92 as shown in FIG. It is connected to the.

Liquid level detection sensor 80 according to the present embodiment
As shown in FIG. 6, a light emitting unit 8 for emitting light is provided.
1 and a sensor main body 83 having a light receiving portion 82 for receiving and detecting light. This sensor body 8
An optical fiber 84 extends from 3, and a reflection surface 85 is provided at the tip. The optical fiber 84 has a heat resistance of, for example, −40 ° C. to + 200 ° C.

In the liquid level detection sensor 80, the light emitting section 8
From 1, light is emitted toward the inner wall of the optical fiber 84, is sequentially reflected by the inner wall of the optical fiber 84, and reaches the reflecting surface 85 at the tip of the optical fiber 84. The light reflected by the reflecting surface 85 is sequentially reflected and returned by the inner wall of the optical fiber 84, and is detected by the light receiving unit 82.

In general, the refractive index of the inner wall of the optical fiber 84 differs between when it comes into contact with air and when it comes into contact with liquid. Therefore, for example, the case where the liquid level is sequentially lowered will be described. As the liquid level is sequentially lowered, the portion of the optical fiber 84 immersed in the liquid touches the liquid surface, and then, when the optical fiber 84 touches the air, the optical fiber 84 On the inner wall of the portion 84, the refractive index changes, and the optical fiber 8 corresponds to the change in the refractive index.
The intensity of the light reflected on the inner wall of the portion 4 changes.

As described above, when the liquid level changes, the intensity of the reflected light changes accordingly. Therefore, the intensity of the reflected light is detected by the light receiving section 82 so that an arbitrary liquid level can be continuously set. And can be detected in an analog manner.

In this case, since there is a certain relationship between the liquid level and the intensity of the reflected light, this relationship is calibrated in advance, and the result is stored in the memory 86. Based on the intensity of the reflected light detected by the light receiving unit 82 based on the calibration result, the CPU
The liquid level can be calculated by the calculation unit 87.

At this time, since the change in the reflected light intensity is detected as a analog value corresponding to the change in the liquid level, the detection signal is A / D-converted, divided into levels, and calculated by the calculation unit 87. Is done. Then, the liquid level signal from the arithmetic unit 87 is input to the unit controllers of the various processing units.

As shown in FIG. 7, the developer supply tank 90
Is connected to a developer supply nozzle 68 connected to a developer supply nozzle 66. The developer supply tube 68 has a pump 88 on the way and is inserted into a developer supply tank 90. Have been. As a result, the pump 88 is driven, and the developer in the developer supply tank 90 is supplied to the developer supply nozzle 66 via the developer supply pipe 68. Further, the developer is supplied to the developer supply tank 90.
An introduction pipe 89 for introducing the inside is provided.

The above-described liquid level detection sensor 80 is mounted on the developer supply tank 91. Therefore, for example, when the developer is supplied through the developer supply pipe 68 and the amount of the developer remaining in the developer supply tank 90 decreases, the liquid level detection sensor 80 detects the lower liquid level (L). ) Is detected. When the inside of the developer supply tank 91 becomes almost full with the developer introduced by the introduction pipe 87, the liquid level detection sensor 80 detects a higher liquid level (H). Thus, in the present embodiment,
One liquid level detection sensor can detect the liquid level at a plurality of locations.

In the present embodiment, the liquid level detecting sensor 80 can detect an arbitrary liquid level because the light intensity to be detected changes according to the liquid level, and furthermore, detects continuously. Therefore, not only the predetermined liquid level (L, H) but also the liquid level can be constantly monitored. These detected liquid level signals are sent to the unit controller of the development processing unit (DEV), and based on this signal, the developer supply tank 9 is controlled.
The supply of the developer to 0 is controlled.

Further, since the liquid level detecting sensor 80 uses the optical fiber 84, it is small in size.
Since it has heat resistance, operability is extremely good for mounting in the developer supply tank 91 and the like.

Although only one developer supply tank 90 is provided in the example shown in FIG. 7, two developer supply tanks 90 are provided, and a three-way valve or the like is provided in the middle of the developer supply pipe 68. May be provided such that when the developer in one tank 90 becomes empty, the developer is supplied from the other tank 90.

Next, the drainage system will be described. As shown in FIG. 8, a three-way switching valve 88 is provided in the drain passage 65 for discharging the drainage. Two discharge pipes 91 are connected to the liquid tank 92. In the two drainage tanks 92, respectively,
A liquid level detection sensor 80 is mounted.

Therefore, the three-way valve 8 is
8 and one of the drainage tanks 92 via the discharge pipe 89.
When the drainage tank 92 is almost full, the liquid level detection sensor 80 detects a higher liquid level (H), and the signal of the higher liquid level (H) is: It is sent to the unit controller of the development processing unit (DEV). As a result, the tank switching alarm is issued, the three-way switching valve 88 is switched, and the drainage is
It is introduced into the other drainage tank 92. Further, when the liquid level reaches a higher liquid level (HH), the liquid level (HH) is detected, and an alarm or the like that the drainage tank 92 is substantially full is issued. May be configured.

Also in this case, the liquid level detecting sensor 8
The value 0 indicates that the liquid level can be arbitrarily and continuously detected, so that not only the predetermined liquid level (H, HH) but also the liquid level can be constantly monitored.

Note that the present invention is not limited to the above embodiment, and various modifications are possible. For example, in the above embodiment, the liquid level detector (sensor) is applied to the development processing unit, but is not limited thereto, and may be another substrate processing apparatus such as a coating processing unit. Further, in the above embodiment, the coating / developing processing system for a semiconductor wafer has been described. However, the present invention can be applied to a coating / developing processing system for a substrate to be processed other than the semiconductor wafer, for example, an LCD substrate. Furthermore, the liquid level detector of the present invention can be applied to devices other than the substrate processing apparatus.

[0062]

As described above, according to the first, second, and fifth aspects of the present invention, light is emitted from the light emitting portion toward the inner wall of the optical fiber, and the tip of the optical fiber is sequentially reflected by the inner wall of the optical fiber. And after being reflected at this tip, the reflected light is detected by the light receiving unit while being sequentially reflected by the inner wall of the optical fiber, so that the inner wall of the optical fiber when touching air and when touching liquid is detected. By utilizing the fact that the refractive index is different and detecting the intensity of the reflected light when the liquid level changes, an arbitrary liquid level can be continuously and accurately detected.
Therefore, a plurality of liquid levels can be detected with high accuracy, and the level of the molten metal can be continuously monitored. Further, the liquid level detector according to the first or second aspect of the present invention uses an optical fiber, so that the size can be reduced.

According to the third, sixth, and ninth inventions, the relationship between the liquid level and the intensity of the reflected light is determined in advance, so that the liquid level can be easily calculated from the intensity of the reflected light. be able to.

According to the seventh aspect, since the liquid level detector is provided in the processing liquid container of the substrate processing apparatus, an arbitrary liquid level in the processing liquid container can be continuously and accurately detected. can do. Therefore, it is possible to accurately detect a plurality of liquid levels in the processing liquid container, and to continuously monitor the liquid level in the processing liquid container.

According to the eighth aspect, since the liquid level detector is provided in the drainage container of the substrate processing apparatus, an arbitrary liquid level in the drainage container can be continuously and accurately detected. can do. Therefore, it is possible to accurately detect a plurality of liquid levels in the drainage container, and to continuously monitor the liquid level in the drainage container.

[Brief description of the drawings]

FIG. 1 is a plan view of the overall configuration of a semiconductor wafer coating and developing processing system according to an embodiment of the present invention.

FIG. 2 is a front view of the coating and developing system shown in FIG.

FIG. 3 is a rear view of the coating and developing system shown in FIG. 1;

FIG. 4 is a sectional view of the overall configuration of a developing unit mounted on the coating and developing system shown in FIG. 1;

FIG. 5 is a plan view of the developing unit shown in FIG. 4;

FIG. 6 is a sectional view of a liquid level detector (sensor) according to the embodiment of the present invention.

FIG. 7 is a sectional view of a processing liquid tank to which the liquid level detection sensor shown in FIG. 6 is attached.

8 is a cross-sectional view of two drainage tanks to which the liquid level detection sensors shown in FIG. 6 are respectively mounted.

[Explanation of symbols]

 65; drain passage 68; developer supply pipe 80; liquid level detector (sensor) 81; light emitting section 82; light receiving section 83; sensor main body 84; optical fiber 85; reflecting surface 86; 89; discharge pipe 91; developer supply tank (treatment liquid container) 92; drainage tank (drainage container)

Claims (10)

[Claims] 1. A light emitting unit emits light to an optical fiber extending into a liquid stored in a container, detects light reflected by a tip of the optical fiber by a light receiving unit, and detects a liquid level in the container. In the liquid level detector to be detected, light is emitted from the light emitting section toward the inner wall of the optical fiber, reaches the tip of the optical fiber while being sequentially reflected by the inner wall of the optical fiber, and after being reflected by the tip, is sequentially reflected by the inner wall of the optical fiber. A liquid level detector, wherein reflected light returned while being reflected is detected by the light receiving unit. 2. A liquid level detector for detecting a liquid level of a liquid stored in a container, wherein the light emitting unit emits light, and the light emitting unit extends in the liquid stored in the container. An optical fiber that causes the light emitted from the light emitting section to reach the distal end while being sequentially reflected by the inner wall, and returns the reflected light reflected by the distal end while being sequentially reflected by the inner wall; and a reflected light that returns while being reflected by the inner wall of the optical fiber. A liquid level detector, comprising: 3. The method according to claim 1, further comprising calculating means for calculating the liquid level from the detected intensity of the reflected light based on a relationship between the liquid level and the intensity of the reflected light obtained in advance. Or the liquid level detector according to claim 2. 4. The liquid level detector according to claim 1, wherein the optical fiber has a reflecting surface at a tip end thereof for reflecting light. 5. A light emitting unit emits light to an optical fiber extending into a liquid stored in a container, detects light reflected at a tip end of the optical fiber by a light receiving unit, and detects a liquid level in the container. In the liquid level detection method for detecting, the light is emitted from the light emitting section toward the inner wall of the optical fiber, and reaches the tip of the optical fiber while being sequentially reflected on the inner wall of the optical fiber. A liquid level detection method, wherein reflected light returned while being reflected is detected by the light receiving unit. 6. The liquid level detecting method according to claim 5, wherein the liquid level is obtained from the detected intensity of the reflected light based on the relationship between the liquid level and the intensity of the reflected light obtained in advance. . 7. A processing section for performing a predetermined process on a substrate using a processing liquid stored in a processing liquid container, and a liquid surface of the processing liquid disposed in the processing liquid container and stored in the processing liquid container. A liquid level detector for detecting a level, wherein the liquid level detector is provided with a light emitting unit that emits light, and is extended into the processing liquid stored in the processing liquid container, and is provided from the light emitting unit. An optical fiber that causes the emitted light to reach the distal end while being sequentially reflected by the inner wall and returns the reflected light reflected by the distal end while being sequentially reflected by the inner wall, and a light receiving device that detects the reflected light that is returned while being reflected by the inner wall of the optical fiber And a substrate processing apparatus. 8. A processing unit for performing predetermined processing on a substrate with a liquid and storing the drainage in a drainage container, and a drainage unit disposed in the drainage container and stored in the drainage container. A liquid level detector for detecting a liquid level of the liquid, wherein the liquid level detector is a light emitting unit that emits light; An optical fiber that causes the light emitted from the optical fiber to reach the distal end while being sequentially reflected by the inner wall and returns the reflected light reflected by the distal end while being sequentially reflected by the inner wall, and detects the reflected light that is returned while being reflected by the inner wall of the optical fiber A substrate processing apparatus, comprising: 9. The liquid level detector further includes a calculating means for calculating a liquid level from the detected intensity of the reflected light based on a relationship between the liquid level and the intensity of the reflected light obtained in advance. 9. The substrate processing apparatus according to claim 7, wherein: 10. The optical fiber according to claim 1, wherein
The substrate processing apparatus according to any one of claims 7 to 9, further comprising a reflecting surface that reflects light.