JPH05310323A - Unmanned carrying device for clean room - Google Patents

Abstract

PURPOSE:To provide an unmanned carrying device which is capable of suppressing generation of the naturally oxidated film on the surface of a semi- conductor wafer or the like even when the carriage of the semiconductor wafers is forced to be stopped for a long time by the cause of the device or by the cause of any other loading or carrying device while the semiconductor wafer or the like being loaded. CONSTITUTION:In an unmanned carrying device which loads goods to be carried from an equipment on the ground side and travels to the destination, the carried goods are stored in a container 40 and carried, and the container is connected to an inert gas storing part (gaseous nitrogen cylinder) 50 in order to execute substitution of the inside atmosphere through a gas-supplying passage 53.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an unmanned conveying device used for conveying semiconductor wafers and electronic material substrates.

[0002]

2. Description of the Related Art Semiconductor ICs and the like are manufactured in a clean room in which air is constantly cleaned. However, when the degree of integration of semiconductor integrated circuits increases, the semiconductor ICs are naturally formed on the surfaces of semiconductor wafers and electronic material substrates. The oxide film becomes a problem,
In order to improve the yield, it is necessary to suppress the growth of this natural oxide film.

4 and 5 are described in a paper published in "VLSI LSI Ultra Clean Technology Symposium (November 19, 1990)". FIG. 4 shows a natural oxide film of a silicon semiconductor wafer. FIG. 6 is a diagram showing the relationship between the formation of (formed by oxygen and water in the air) and time, and FIG. 5 is a diagram showing the relationship between resistivity and time. As is clear from FIG. 4, when the silicon semiconductor wafer is exposed to the atmosphere, the growth of the oxide film becomes remarkable after 100 to 200 minutes, and the resistivity is about 1 hour after that, as shown in FIG. It rises sharply.

[0004]

In the above clean room, an automated guided vehicle equipped with a transfer robot is used to transfer a semiconductor wafer from one process to the next process. Is usually a short time of about several minutes, and it takes about one hour or more to form the above-mentioned problematic natural oxide film.
As the above natural oxide film does not need to be regarded as a problem, conventionally,
Transport between processes was carried out while exposed to the atmosphere.

Although it is not necessary to consider the formation of the natural oxide film as a problem when the transfer system using the unmanned transfer vehicle is operating normally, the semiconductor manufacturing apparatus, which is the transfer destination, may fail or transfer. If the automated guided vehicle does not operate according to the schedule due to system failure, equipment / device stoppage due to power outage, or failure of the transport route, the semiconductor wafer will be left on the automated guided vehicle for a long time. During this time, there was a problem that the above-mentioned natural oxide film was rapidly grown.

The present invention has been made in order to solve this problem, and the transportation of the semiconductor wafer while the semiconductor wafer or the like is mounted is interrupted for a long period of time due to its own cause or the cause of the transfer / transport destination or the like. It is an object of the present invention to provide an unmanned conveyance device capable of suppressing the formation of the above-mentioned natural oxide film even when forced to do so.

[0007]

In order to achieve the above-mentioned object, the present invention is an unmanned conveying device which carries a conveyed object from ground equipment and travels to a destination by itself. An unmanned transfer device for a clean room, characterized in that the container is connected to an inert gas reservoir through a gas supply passage so that the inside atmosphere can be replaced.

According to a second aspect of the present invention, the container is configured to be transferred to and from the above-ground equipment while containing the transported object.

According to a third aspect of the present invention, there is provided a means for measuring the transfer time, and when the transfer time exceeds the set value, the internal atmosphere of the container is replaced with the inert gas.

According to a fourth aspect of the present invention, after the supply gas passage is opened, when the oxygen concentration or the inert gas concentration in the container reaches a specified value, the supply gas passage is closed.

According to a fifth aspect of the present invention, the supply gas passage has one solenoid valve, and when the solenoid valve replaces the gas in the internal atmosphere, after the gas replacement is completed, the valve opening allows the minute flow rate to be delivered. The structure was narrowed down.

According to the present invention, the feed gas passage has a minute flow rate sending electromagnetic valve which is a main valve and a sub valve, and after the gas replacement is completed, the main valve is closed and the sub valve is used to reduce the minute flow rate. It is configured to supply.

[0013]

In the present invention, when the semiconductor wafer or the like is stored in the container, the air in the container is replaced with the inert gas, and the semiconductor wafer or the like is placed in the inert gas atmosphere and transported.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

In FIGS. 1 and 2, 1 is a wafer cassette containing a semiconductor wafer 2, and 10 and 20 are semiconductor manufacturing apparatuses. The semiconductor manufacturing apparatuses 10 and 20 are arranged in a clean room with a certain space therebetween. Reference numeral 30 denotes an unmanned transport vehicle, in which a transfer robot 31 is mounted near one end of a top plate 30B of a bogie frame 30A, and a transport box 40 is mounted and fixed to another part on the top plate 30B. .. 32
Is a drive wheel, and 33 is a caster.

The carrying box 40 has a lid 42 attached to the box body 41 by a hinge 43, and has an on-board sensor 43 inside. The lid 42 is opened and closed by an opening / closing mechanism (not shown), for example, an electric cylinder. A gas injection port 44 and an exhaust port 45 are formed on the bottom wall of the transfer box 40.

An inert gas cylinder (a nitrogen gas cylinder in this example) is provided in the bogie frame 30A of the automatic guided vehicle 30.
50 is provided, and the port of the nitrogen gas cylinder 50 and the gas injection port 44 of the transfer box 40 are connected by a pipe 52 in which a pressure reducing valve 51 and a gas supply valve 53 are interposed. From the exhaust port 45 of the transfer box 40, an exhaust pipe 55 having an exhaust valve 54 penetrates the top plate 30B and extends into the bogie frame 30A. Reference numeral 60 denotes a controller, which inputs detection signals from sensors described later and transmits / receives required timing signals to / from a main controller (not shown) that controls the automatic guided vehicle 30 and the transfer robot 31. In addition to outputting an opening / closing signal for the gas supply valve 53 and the exhaust valve 54, a signal for opening / closing the lid 42 of the transfer box 40 is output.

Next, the operation of this device will be described.

Now, assume that the wafer cassette 1 on the semiconductor manufacturing apparatus 20 is conveyed to the semiconductor manufacturing apparatus 10. When the automated guided vehicle 30 stops at a predetermined position in front of the semiconductor manufacturing apparatus 20, or when it reaches a position before this predetermined position, (1) it is synchronized with the timing signal output from the main controller to the controller 60. Then, the electric cylinder of the transfer box 40 extends to open the lid 42. When the lid 42 is opened to a predetermined position, a lid opening detection sensor (limit switch) not shown operates. When the vehicle stops at a predetermined position in front of the semiconductor manufacturing apparatus 20, the arm / wrist of the transfer robot 31 starts a transfer operation according to a predetermined program, on condition that the limit switch for lid opening detection generates a detection signal. ..

(2) When the wafer cassette 1 is stored in the transfer box 40 from the semiconductor manufacturing apparatus 20 by the transfer operation of the transfer robot 31, the load sensor 43 outputs and the transfer box 40 is electrically driven. The cylinder contracts and the lid 41 is closed. When the lid 42 is closed, a lid closing detection sensor (limit switch) not shown operates.

(3) When the lid 42 is completely closed, that is, when the lid closing detection limit switch outputs, the controller 6
A timer (not shown) in 0 starts timing, the exhaust valve 54 opens, the supply gas valve 53 subsequently opens, and nitrogen gas is ejected from the nitrogen gas cylinder 50 into the transfer box 40. The air in the transfer box 40 is pushed out by this nitrogen gas and exhausted from the exhaust port 45 into the bogie frame 30A, and the inside of the transfer box 40 is replaced with nitrogen gas. The time Tk required for this gas replacement is set by the timer, and when the timer times out, the exhaust valve 54 is closed, and subsequently the gas supply valve 53 is closed.

(4) When the exhaust valve 54 and the gas supply valve 53 are closed, the automated guided vehicle 30 executes a traveling program toward the semiconductor manufacturing apparatus 10 and starts traveling toward the semiconductor manufacturing apparatus 10.

(5) The automated guided vehicle 30 is the semiconductor manufacturing apparatus 1
When the vehicle stops at a predetermined position before 0 or reaches a certain position before the predetermined position, the electric cylinder of the transfer box 40 is synchronized with the timing signal output from the main controller to the controller 60. When the unmanned transport vehicle 30 stops at a predetermined position in front of the semiconductor manufacturing apparatus 10 by extending the lid 42 to open the lid 42, the arm / wrist portion of the transfer robot 31 starts the transfer operation according to a predetermined program, and the transfer box. The wafer cassette 1 in 40 is the semiconductor manufacturing apparatus 10
Transferred to.

In this embodiment, the wafer cassette 1 accommodating the semiconductor wafer 2 is housed in the carrier box 40, and the atmosphere in the carrier box 40 is changed from a predetermined position to a predetermined position in a nitrogen gas atmosphere which is an inert gas. For example, even if the unmanned guided vehicle 30 is forced to stop for a long time (a time sufficient for the natural oxide film to grow) during the transportation for some reason, the semiconductor It is possible to suppress the growth of the natural oxide film on the surface of the wafer 2.

FIG. 3 shows another embodiment of the present invention, which is provided with a clock circuit 70, and the clock time T of the clock circuit 70 is compared with a set time To in the controller 60, and T> To.
2 is different from that of FIG. 2 in that the controller 60 outputs an open signal to the supply gas valve 53 and the exhaust valve 54. The set time To is set to a value within a safe period in which the growth of the natural oxide film is not observed, for example, within 10 minutes.

Next, the operation of this embodiment will be described.

Now, assume that the wafer cassette 1 on the semiconductor manufacturing apparatus 20 is conveyed to the semiconductor manufacturing apparatus 10. When the automated guided vehicle 30 stops at a predetermined position in front of the semiconductor manufacturing apparatus 20 or when it reaches a certain position before the predetermined position, (1) it is synchronized with the timing signal output from the main controller to the controller 60. Then, the electric cylinder of the transfer box 40 extends to open the lid 42. When the lid 42 is opened to a predetermined position, a lid opening detection limit switch (not shown) operates. When the automatic guided vehicle 30 stops at a predetermined position in front of the semiconductor manufacturing apparatus 20, the arm / wrist portion of the transfer robot 31 moves according to a predetermined program on condition that the lid opening detection limit switch generates a detection signal. Start loading operation.

(2) When the wafer cassette 1 is stored in the transfer box 40 by the transfer operation of the transfer robot 31, the load sensor 43 outputs and the timing circuit 70 starts timing. Further, the electric cylinder of the transfer box 40 contracts to close the lid 42. When the lid 42 is closed, the lid close detection limit switch operates.

(3) When the lid 42 is completely closed, the automated guided vehicle 30 executes the running program, and the semiconductor manufacturing apparatus 10
Start traveling toward.

(4) The automated guided vehicle 30 is the semiconductor manufacturing apparatus 1
When the vehicle stops at a predetermined position before 0 or reaches a certain position before the predetermined position, the electric cylinder of the transfer box 40 is synchronized with the timing signal output from the main controller to the controller 60. When the unmanned transport vehicle 30 stops at a predetermined position in front of the semiconductor manufacturing apparatus 10 by extending the lid 42 to open the lid 42, the arm / wrist portion of the transfer robot 31 starts the transfer operation according to a predetermined program, and the transfer box. The wafer cassette 1 in 40 is the semiconductor manufacturing apparatus 10
Transferred to.

(5) For some reason, the automated guided vehicle 30
When the unmanned guided vehicle 30 is forced to stop for a long time as described above during the above-mentioned transportation, and the set time To has elapsed during this stopping, the controller 60 causes the gas supply valve 53 A valve opening command signal is output to the exhaust valve 54, and the above-mentioned timer starts counting time. As a result, the supply gas valve 53 and the exhaust valve 54 are opened, and the nitrogen gas is ejected from the nitrogen gas cylinder 50 into the transfer box 40. The air in the transfer box 40 is pushed out by this nitrogen gas and exhausted from the exhaust port 45 into the bogie frame 30A.
The inside is replaced with nitrogen gas. When the timer times out, the exhaust valve 54 closes, and then the gas supply valve 53 closes.

In the present embodiment, the semiconductor wafer 2 is transferred while the inside of the transfer box 40 is kept in the atmospheric atmosphere during the safe period To in which the growth of the natural oxide film is not observed. Since the inside of the box 40 is replaced with nitrogen gas, there are the following advantages over the case of FIG.

When the distance between the semiconductor manufacturing apparatuses 10 and 20 is short and the required transportation time of the unmanned guided vehicle 30 during normal traveling is a short time, for example, a few minutes, the natural oxide film is formed in this short time. Since there is no fear of rapid growth,
In the case of the embodiment shown in FIG. 2, the nitrogen gas is wastefully consumed, and the nitrogen gas is exhausted to the atmosphere each time one carrying process is completed, so that the carrying process is repeated. However, in the present embodiment, the oxygen concentration in the narrow clean room may be reduced. Since nitrogen is replaced by nitrogen gas, it is possible to prevent wasteful consumption of nitrogen gas, and there is no fear of lowering the oxygen concentration in the clean room.

In the above embodiment, the transport box 40 is used.
After replacing the inside with nitrogen gas, the supply gas valve 53 and the exhaust valve 54 are closed to stop the supply of nitrogen gas to the transfer box 40. However, the supply gas valve 53 is not a simple open / close valve,
An electromagnetic control valve that can control the valve opening and an exhaust valve 5
After removing 3 and replacing the inside of the transfer box 40 with nitrogen gas, the valve opening is reduced and a small amount of nitrogen gas is continuously sent into the transfer box 40, and the gas injection port 44 of the transfer box 40 is
A nitrogen gas flow from the exhaust gas to the exhaust port 54 may be formed.

Further, in the above embodiment, one gas supply valve 5 is used.
Nitrogen gas is supplied from No. 3, but in addition to this feed gas valve 53, a sub valve (electromagnetic valve) for sending a minute flow rate is provided, and after the gas replacement is completed, the feed gas valve 53 which is the main valve is closed, A minute flow rate may be supplied by the sub valve.

Further, in the embodiment shown in FIG.
After the replacement with nitrogen gas in 0 is completed, the automated guided vehicle 30
However, the nitrogen gas replacement may be performed while the automatic guided vehicle 30 is running.

In the above embodiment, the transport box 40 is used.
The air inside is pushed out by nitrogen gas to be replaced, but a vacuum pump may be provided so that the air in the transfer box 40 is pulled by the vacuum pump before the nitrogen gas is sent into the transfer box 40. it can.

The supply time of nitrogen gas is regulated by a timer (not shown) in the controller 60.
A concentration meter for measuring the oxygen concentration or the nitrogen concentration in 0 may be provided and the supply gas valve 53 and the exhaust valve 54 may be closed.

Further, the transport box 40 is a bogie frame 30A.
The top plate 30B may have a structure in which a part of the top plate 30B is used as a bottom and the top is covered therewith.

Although the transport box 40 in each of the above-described embodiments is fixed to the bogie frame 30A, the transport box 40 is not fixed to the bogie frame 30A, and the transport box 40 itself is exchanged with the semiconductor manufacturing apparatus 10, 20 side. In some cases.

In each of the above embodiments, the automatic guided vehicle 30
Although the transfer robot 31 mounted on and receives the transferred object from the ground side (semiconductor manufacturing apparatuses 10 and 20), the transfer robot may be provided on the ground side to transfer the transferred object.

[0042]

As described above, according to the present invention, a semiconductor wafer or the like is housed and carried in a container for carrying a product, which is connected to an inert gas cylinder through a valve so that the internal atmosphere can be replaced. Since it is possible to prevent the natural oxide film from growing during the transportation period, it is possible to improve the yield of semiconductor manufacturing as compared with the conventional method, and it is extremely effective for use in a highly integrated semiconductor manufacturing line. ..

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a usage state of an embodiment of the present invention.

FIG. 2 is a diagram showing a specific configuration of an automated guided vehicle in the above embodiment.

FIG. 3 is a diagram showing another embodiment of the present invention.

FIG. 4 is a diagram showing a relationship between growth of a natural oxide film of a silicon semiconductor wafer and time.

FIG. 5 is a diagram showing a relationship between resistivity and time due to formation of a natural oxide film of a silicon semiconductor wafer.

[Explanation of symbols] 1 wafer cassette 2 semiconductor wafers 10, 20 semiconductor manufacturing equipment 30 unmanned carrier 30A bogie frame 30B top plate 31 transfer robot 40 carrier box 42 lid 43 load sensor 44 gas inlet 45 exhaust port 50 nitrogen cylinder 53 gas supply valve 54 exhaust valve 60 controller 70 timing circuit

Claims (6)

[Claims] 1. An unmanned carrier device, which carries a carrier from a ground facility and travels to a destination by itself, stores the carrier in a container and transports the container, and the container is capable of replacing an internal atmosphere with a gas supply path. An unmanned transfer device for a clean room, characterized in that it is connected to an inert gas storage part via a. 2. The unmanned transfer device for a clean room according to claim 1, wherein the container is transferred to and from the above-ground equipment while containing the transferred object. 3. The method according to claim 1, further comprising a means for measuring the transfer time, wherein the internal atmosphere of the container is replaced with an inert gas when the transfer time exceeds a set value. Unmanned transfer device for clean rooms. 4. The clean room for a clean room according to claim 1, wherein when the oxygen concentration or the inert gas concentration in the container reaches a specified value after opening the gas supply passage, the gas supply passage is closed. Unmanned carrier device. 5. The supply gas passage has a solenoid valve, and the solenoid valve comprises:
5. The unmanned transfer apparatus for a clean room according to claim 1, wherein the valve opening is narrowed so that a minute flow rate can be delivered after the gas replacement is completed in the gas replacement of the internal atmosphere. 6. The supply gas passage has a minute flow rate delivery electromagnetic valve, which is a main valve and a sub valve, and after the gas replacement is completed, the main valve is closed and the sub valve supplies a minute flow rate. The unmanned transfer device for a clean room according to any one of claims 1 to 4.