JPH06120193A - Liquid detection device and semiconductor manufacturing device using same - Google Patents

Abstract

PURPOSE:To provide a liquid detection device having no detection error and no contamination of a liquid. CONSTITUTION:A light-conducting member 2 of a nearly V-shaped pillar is mounted on the outer wall surface of a liquid tank 1 to house liquid 5 by face- contacting its bent part while connecting optical fibers (light source) 3 to the end face of the incident part 2a of this light-conducting member 2 and connecting an optical sensor 4 to the end face of the reflection part 2d. This light-conducting member 2 is to be of the same material with the liquid tank 1 and the contact face with the end face of an incident part 2a and the outer wall face of the liquid tank 1 is to be of a mirror finish. Further, a center angle theta to be composed of an incident part 2a and a reflection part 2b of the light-conducting member 2 is to be such an angle where the light 6 from the optical fibers (light source) 3 performs total reflection on the inner wall face of the liquid tank 1 for being photodetected by a photo-sensor 4 only when no liquid exists in the contact part of the light-guiding member 2 and the liquid tank 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid detection apparatus and a semiconductor manufacturing apparatus using the same, and more particularly to a technique effectively applied to the detection of a liquid such as a semiconductor processing liquid used in a semiconductor manufacturing process. Is.

[0002]

2. Description of the Related Art In semiconductor manufacturing equipment, for example,
The semiconductor processing liquid such as isopropyl alcohol (hereinafter referred to as liquid) used for drying semiconductor wafers is constantly supplied to a specified amount in the liquid tank. When the liquid decreases, it is detected and the required amount of liquid is detected. A liquid detection device is provided for automatically replenishing the liquid.

Here, in the conventional liquid detecting apparatus, as shown in FIG. 6, a communication pipe 18 communicating vertically with the liquid tank 11 is connected to the outside of the liquid tank 11 made of quartz. The optical fiber (light source) 13 irradiates the light 16 from the side surface, and the light sensor 14 on the opposite side receives the light 16.

That is, in FIG. 7 which is a sectional view taken along the line VII-VII of FIG. 6, when there is no liquid 15 in the liquid detecting device portion in the communicating pipe 18, as shown in FIG. The light 16 is diffused, but in the presence of the liquid 15, FIG.
As shown in (b), the light 16 is refracted and converged in the communication tube 18. Therefore, compared to the case without liquid 15,
The amount of light received by the optical sensor increases when the liquid 15 is present.

Therefore, the presence or absence of this liquid 15 is detected by the optical sensor 1.
4 is detected as a difference in the amount of received light, and this detection signal is transmitted to the liquid supply device to supply a prescribed amount of liquid 15 into the liquid tank 11.

[0006]

However, the present inventor has clarified that the conventional liquid detecting device has the following problems.

First, the difference in the amount of light received by the optical sensor, which is detected depending on the presence or absence of liquid, is extremely small, and it is difficult to adjust the detection sensitivity, resulting in erroneous detection. There was a situation where the liquid was not supplied.

Further, due to the surface tension, there is a difference between the liquid surface in the liquid tank and the liquid surface in the communicating pipe, and accurate detection cannot be performed.

Furthermore, since the connecting pipe is connected to the outside of the liquid tank, the surrounding pipe collides with the connecting pipe and the connecting pipe is damaged, and the liquid tank itself becomes unusable. Dust was generated or oil and fat were attached.

On the other hand, a liquid detecting device using a float, for example, which directly detects the liquid level in the liquid tank without providing a communication pipe, is also conceivable. Since a part of the liquid comes into contact with the liquid, dust is generated at this contact portion and the liquid is also contaminated.

Therefore, an object of the present invention is to provide a liquid detection device having no detection error.

Another object of the present invention is to provide a liquid detecting device in which the liquid is not contaminated.

Still another object of the present invention is to provide a semiconductor manufacturing apparatus using this liquid detecting device.

The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

[0015]

The typical ones of the inventions disclosed in the present application will be outlined below.

That is, in the liquid detecting apparatus of the present invention, a substantially V-shaped columnar light guide member having an incident portion and a reflection portion is provided on the outer wall surface of the liquid tank in which the liquid is accommodated, and its refraction portion is provided. Mounted in surface contact, an optical fiber (light source) is connected to the end face of the light guide member, and an optical sensor is connected to the end face of the light guide member. The light guide member is made of the same material as the liquid tank. The central angle formed by the incident part and the reflection part of the member is an optical fiber (light source) when there is no liquid at the contact part between the light guide member and the liquid tank.
When the light from the optical fiber (light source) is present at the contact area between the light guide member and the liquid tank, the light from the optical fiber (light source) The angle is such that the liquid is refracted at the boundary surface between the tank and the liquid and goes straight in the liquid.

Further, in the liquid detecting device of the present invention,
The light guide member is held by a holding member, and the holding member allows the light guide member to be vertically displaced along the outer wall surface of the liquid tank.

Further, in the liquid detecting device of the present invention, the incident part and the reflection part of the light guide member are separately held by the holding member, and the holding member holds the incidence part and the reflection part of the light guide member. Can be vertically displaced along the outer wall surface of the liquid tank.

Further, in the liquid detecting device of the present invention, the position and angle of the optical fiber (light source) connected to the end face of the incident portion of the light guide member can be adjusted.

The semiconductor manufacturing apparatus of the present invention is a semiconductor manufacturing apparatus having a liquid tank for containing a liquid, and the liquid detecting device of any one of the above is mounted on the outer wall surface of the liquid tank.

[0021]

According to the liquid detecting device having the above-described structure, the light emitted from the optical fiber (light source) emits light from the inner wall surface of the liquid tank when there is no liquid at the contact portion between the light guide member and the liquid tank. The light is totally reflected by the light guide member, enters the reflection part of the light guide member, and is received by the optical sensor.
This optical sensor sends a detection signal to the liquid supply device,
Liquid is supplied from the liquid supply device into the liquid tank.

On the other hand, when liquid is present at the position of the contact surface between the light guide member and the liquid tank, light is refracted at the boundary surface between the liquid tank and the liquid and travels straight through the liquid. Since the light is not received by, the liquid is not supplied into the liquid tank.

Further, according to the liquid detection device in which the light guide member is vertically displaceable by the holding member, when the set amount of the liquid in the liquid tank is changed, the light guide member is moved by the holding member. This is possible by displacing and changing the detection position.

According to the liquid detecting device in which the incident portion and the reflecting portion of the light guide member are separate bodies and each of which can be vertically displaced by the holding member, the reflection angle of the light entering the reflecting portion is somehow. When an error from the theoretical value is caused by the cause, the error can be absorbed by displacing the incident portion or the reflecting portion by the holding member, and the light can be stably guided to the optical sensor.

According to the liquid detecting device in which the position and the angle of the optical fiber (light source) are adjustable, the position and the angle of the optical fiber (light source) are changed when the liquid is changed to another liquid having a different refractive index. The light can be guided to the optical sensor by adjusting.

[0026]

[Embodiment 1] FIG. 1 and FIG. 2 are cross-sectional views of an essential part showing an embodiment of a liquid detecting apparatus of the present invention.

First, the structure of the liquid detecting apparatus of the present invention will be described with reference to FIG.

The liquid detector of the present invention comprises a liquid tank 1 made of, for example, transparent quartz, a light guide member 2 provided on the outer wall surface of the liquid tank 1, and optical fibers connected to the light guide member 2, respectively. It comprises a (light source) 3 and an optical sensor 4.

That is, on the outer wall surface of the liquid tank 1 containing the liquid 5 made of, for example, isopropyl alcohol, approximately V
A light guide member 2 made of a V-shaped columnar body is provided with its refraction portion in surface contact with the outer wall surface of the liquid tank. Part 2b
It is said that.

The light guide member 2 is made of the same material as that of the liquid tank 1, so that the light guide member 2 and the liquid tank 1 have the same refractive index.

An optical fiber (light source) 3 is connected to the end face of the incident portion 2a of the light guide member 2, and the light 6 emitted from the optical fiber (light source) 3 is prevented from being diffusely reflected, so that the incident portion 2a of the incident portion 2a is prevented. The end surface and the contact surface between the light guide member 2 and the liquid tank 1 are mirror-finished.

An optical sensor 4 is connected to the end surface of the reflecting portion 2b of the light guide member 2. The optical sensor 4 is electrically connected to a liquid supply device (not shown), and the optical sensor 4 emits light 6a.
When light is received, a detection signal is sent from the optical sensor 4 to this liquid supply device, so that a required amount of liquid 5 is stored in the liquid tank 1.
Are being supplied.

Here, in the present embodiment in which the liquid tank 1 is transparent quartz and the liquid 5 is isopropyl alcohol, the substantially V-shaped light guide member 2 constituted by the incident portion 2a and the reflecting portion 2b is used. The central angle θ is 86.4 ° to 135.2 °.

In other words, the light guide member 2 is substantially V expanded at the same angle of 43.2 ° to 67.6 ° with respect to the normal line of the contact surface between the light guide member 2 and the liquid tank 1. An optical fiber (light source) 3 is formed on the end face of the incident portion 2a of the light guide member 2 having a substantially V shape.
However, the optical sensors 4 are respectively connected to the end faces of the reflecting portion 2b.

Next, the operation of the liquid detecting device in this embodiment will be described.

As shown in FIG. 1, when there is no liquid 5 at the position of the contact surface between the light guide member 2 and the liquid tank 1 in the liquid tank 1, the light 6 emitted from the optical fiber (light source) 3 is emitted. Enters from the end face of the entrance portion 2a of the light guide member 2 and travels straight to the liquid tank 1 made of the same material as the light guide member 2 and therefore having the same refractive index as the light guide member 2.

Then, the light is totally reflected on the inner wall surface of the liquid tank 1 and enters the reflecting portion 2b of the light guide member 2, reaches the end face of the reflecting portion 2b, and is received by the optical sensor 4 connected thereto. .

On the other hand, as shown in FIG. 2, when the liquid 5 is present at the position of the contact surface between the light guide member 2 and the liquid tank 1, the light 6 emitted from the optical fiber (light source) 3 is the liquid. Tank 1 and liquid 5
Since the light is refracted at the boundary surface of and goes straight in the liquid 5, it is not received by the optical sensor 4.

This will be described in detail as follows.

That is, the light 6 is refracted at a constant angle when incident on media having different refractive indexes, and this angle is sin θ1.
/ Sin θ2 = n2 / n1 (θ1 = incident angle, θ2 = refractive angle, n1 = refractive index of medium 1, n2 = refractive index of medium 2).

Here, as described above, in the liquid detecting device of this embodiment, the liquid tank 1 and the light guide member 2 are made of transparent quartz, and the liquid 5 is isopropyl alcohol. The transparent quartz and isopropyl alcohol are used. Has a refractive index of 1.46 and 1.35, respectively, and the refractive index of air is 1.00.

Further, the light guide member 2 is spread at an arbitrary angle between 43.2 ° and 67.6 ° with respect to the normal line of the contact surface between the light guide member 2 and the liquid tank 1 and is approximately V. Since it is shaped like a letter, this angle is the optical fiber (light source) with respect to the outer wall surface of the liquid tank
The incident angle of the light 6 emitted from 3 becomes.

Therefore, as shown in FIG. 1, when the medium 1 is transparent quartz and the medium 2 is air, the incident angle θ 1 is 5
At 0 °, since n1 = 1.46 and n2 = 1.00, sin50 ° / sinθ2 = 1.00 / 1.46, and the refraction angle θ2 is about 130 °.

That is, in the case of FIG. 1, the light 6 is totally reflected by the inner wall surface of the liquid tank 1, that is, the boundary surface between the liquid tank 1 and the air, and reaches the end surface of the reflecting portion 2b of the light guide member 2. However, the optical sensor 4 connected here receives the light 6.

On the other hand, as shown in FIG. 2, when the medium 1 is transparent quartz and the medium 2 is isopropyl alcohol, n1 = 1.46, n2 = when the incident angle θ1 is 50 °.
Since it is 1.35, sin 50 ° / sin θ2 = 1.35 / 1.
46, and the refraction angle θ2 is about 56 °.

Therefore, in the case of FIG. 2, the light 6 is refracted at the boundary surface between the liquid tank 1 and the liquid 5, travels straight in the liquid 5, and does not reach the optical sensor 4.

As described above, in the case of FIG. 1, the light 6 emitted from the optical fiber 3 (light source) is received by the optical sensor 4. When the light sensor 6 receives the light 6, the optical sensor 4 sends a detection signal to a liquid supply device (not shown), and the liquid 5 is supplied from the liquid supply device into the liquid tank 1.

On the other hand, in the case of FIG. 2, the light 6 emitted from the optical fiber 3 (light source) travels straight through the liquid 5 and is not received by the optical sensor 4. Therefore, the optical sensor 4 that does not receive the light 6 does not send a detection signal to the liquid supply device (not shown), and the liquid 5 is not supplied into the liquid tank 1.

Although the incident angle .theta.1 has been described as 50.degree. Here, the above sin.theta.1 / sin.theta.2 = n2 /
From the relational expression of n1, this incident angle θ1 is 43.2 ° to 67.6.
The same effect can be obtained by setting an arbitrary angle between °.

[0050]

[Embodiment 2] FIG. 3 is a cross-sectional view of essential parts showing another embodiment of the liquid detecting apparatus of the present invention.

The liquid detecting apparatus of this embodiment is configured so that the light guide member 2 is held by the holding member 7a and is vertically displaceable along the outer wall surface of the liquid tank 1.

According to the liquid detecting apparatus of this embodiment, the light guide member 2 is vertically displaceable. Therefore, when changing the set amount of the liquid 5 in the liquid tank 1, the holding member 7a is used. This can be easily performed by displacing the light guide member 2 and changing the detection position of the liquid 5.

[0053]

[Embodiment 3] FIG. 4 is a sectional view showing the principal part of a liquid detecting apparatus according to still another embodiment of the present invention.

In the liquid detecting device of this embodiment, the light entrance member 2a and the light reflecting member 2b of the light guide member 2 are separated into separate members, which are held by respective holding members 7b.
Thus, each of them can be vertically displaced along the outer wall surface of the liquid tank 1.

According to the liquid detecting apparatus of this embodiment, when the reflection angle of the light 6 entering the reflecting portion 2b differs from the theoretical value due to some cause, the holding member 7b causes the incident portion 2a or the incident portion 2a to move. This error can be absorbed by displacing the reflection portion 2b, and the light 6 can be stably transmitted to the optical sensor 4.
Can be guided.

[0056]

[Embodiment 4] FIG. 5 is a sectional view showing the principal part of a liquid detecting apparatus according to still another embodiment of the present invention.

In the liquid detecting device of this embodiment, the diameter of the light guide member 2 having a columnar shape is increased so that the position and the angle of the optical fiber (light source) 3 connected to the end face of the incident portion 2a of the light guide member 2 are changed. It can be adjusted.

According to the liquid detecting apparatus of this embodiment, the liquid 5
Is changed to another liquid 5 having a different refractive index, the position and angle of the optical fiber (light source) 3 can be adjusted without replacing the light guide member 2 with another light guide member 2 having a different central angle. , Light 6 can be guided to the light sensor 4.

Although the invention made by the present inventor has been specifically described based on the embodiments, the present invention is not limited to the embodiments and various modifications can be made without departing from the scope of the invention. Needless to say.

For example, in this embodiment, the liquid tank and the light guide member are made of transparent quartz, but they may be other than quartz, and may be semitransparent as long as they can transmit light. is there.

Furthermore, in this embodiment, isopropyl alcohol used for drying semiconductor wafers has been described as an example of the liquid in the liquid tank, but this liquid may be, for example, an etching liquid for semiconductor wafers.

The refractive index varies depending on the material of the liquid tank and the light guide member and the type of liquid. Therefore,
It is needless to say that the incident angle of the light on the outer wall surface of the liquid tank must be calculated from the refractive index of this material so that the light is totally reflected only when the light enters the air from the liquid tank.

[0063]

The effects obtained by the typical ones of the inventions disclosed in the present application will be briefly described as follows.

(1) That is, when there is no liquid at the contact area between the light guide member and the liquid tank, the light emitted from the light source is received by the optical sensor, and when there is liquid, it is not received. As described above, the presence / absence of liquid is detected by the presence / absence of light reception by the optical sensor, not by the difference in the amount of light received by the optical sensor, so that the liquid can be detected reliably and the detection sensitivity of the optical sensor need not be adjusted. Become. Therefore, when the amount of liquid in the liquid tank is insufficient, the optical sensor always detects this,
Liquid will be supplied.

(2) In addition, since the liquid can be detected without contacting the liquid, a part of the liquid detecting device and the liquid come into contact with each other, and dust or oil is attached to the contact portion. The liquid will not be contaminated.

(3) Further, since it is not a method of providing a communication pipe outside the liquid tank and detecting the liquid in the communication pipe,
The detection error does not occur due to the surface tension of the communication pipe.

(4) Since it is not necessary to provide a communication pipe outside the liquid tank, a peripheral object hits the communication pipe and damages it, making the liquid tank itself unusable or dust on the connection. There is no possibility that the liquid will be contaminated due to the occurrence of.

(5) According to the liquid detecting device in which the light guide member is vertically displaceable by the holding member, by changing the detection position by displacing the light guide member by the holding member,
It is possible to change the set amount of the liquid in the liquid tank, which facilitates the change of the liquid amount.

(6) According to the liquid detecting device in which the entrance portion and the reflection portion of the light guide member are vertically displaceable by the holding members, the reflection angle of the light entering the reflection portion is equal to the theoretical value. When the error occurs, the error can be absorbed by displacing the incident portion or the reflecting portion, so that the light can be stably guided to the optical sensor.

(7) According to the liquid detecting device in which the position and angle of the light source can be adjusted, the position and angle of the light source can be adjusted when the liquid is changed to another liquid having a different refractive index. Since light can be guided to the optical sensor, it is convenient when different liquids are stored in the liquid tank.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of essential parts showing a case where there is no liquid at a position of a contact surface between a light guide member and a liquid tank in a liquid tank in a liquid detection device according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of essential parts showing a case where liquid is present at the position of the contact surface between the light guide member and the liquid tank in the liquid tank in the liquid detection apparatus according to the first embodiment of the present invention.

FIG. 3 is a cross-sectional view of essential parts showing a liquid detection device according to a second embodiment of the invention.

FIG. 4 is a cross-sectional view of essential parts showing a liquid detection device according to a third embodiment of the invention.

FIG. 5 is a cross-sectional view of essential parts showing a liquid detection device according to a fourth embodiment of the present invention.

FIG. 6 is a cross-sectional view of essential parts showing a conventional liquid detection device.

7 is a sectional view taken along line VII-VII of the liquid detection device of FIG.

[Explanation of symbols]

 1 Liquid Tank 2 Light Guide Member 2a Incident Part 2b Reflecting Part 3 Optical Fiber (Light Source) 4 Optical Sensor 5 Liquid 6 Light 7a Holding Member 7b Holding Member 11 Liquid Tank 13 Optical Fiber (Light Source) 14 Optical Sensor 15 Liquid 16 Light 18 Communication Tube θ center angle

Claims (5)

[Claims] 1. A substantially V-shaped columnar light guide member having an incident portion and a reflection portion, which is attached to an outer wall surface of a liquid tank in which a liquid is contained so as to be in surface contact with a refraction portion, A light source connected to an end surface of the light guide member at an incident portion, and an optical sensor connected to an end surface of the reflection portion, the light guide member made of the same material as the liquid tank, and an incident portion of the light guide member. The central angle formed by the reflecting portion is such that when the liquid does not exist at the contact portion between the light guide member and the liquid tank, the light from the light source is totally reflected on the inner wall surface of the liquid tank. When the light is received by the optical sensor and the liquid is present in the contact portion between the light guide member and the liquid tank, the light from the light source is refracted at the interface between the liquid tank and the liquid, and the liquid A liquid detection device, characterized in that the liquid detection device has an angle so as to go straight inside. 2. The light guide member is held by a holding member, and the holding member allows the light guide member to be vertically displaced along an outer wall surface of the liquid tank. 1. The liquid detection device according to 1. 3. An incident part and a reflection part of the light guide member are separately held by a holding member, and the holding part holds the incidence part and the reflection part of the light guide member in the liquid tank, respectively. The liquid detection device according to claim 1, wherein the liquid detection device is vertically displaceable along the outer wall surface. 4. The liquid detection device according to claim 1, wherein the position and angle of the light source connected to the end surface of the light guide member on the incident part are adjustable. 5. A semiconductor manufacturing apparatus, wherein the liquid detection device according to any one of claims 1 to 4 is mounted on an outer wall surface of the liquid tank.