JPH06232140A - Safety operating method of hydrogen annealing furnace - Google Patents

Abstract

PURPOSE:To avoid the mixture of hydrogen and oxygen in a dangerous ratio by a method wherein no-existence of oxygen exceeding specific amount in a sealing vessel is confirmed before starting annealing step likewise no existence of hydrogen exceeding specific amount in the sealing vessel is confirmed after finishing the annealing step. CONSTITUTION:Before starting annealing step, a valve 6 is opened to feed nitrogen to a quartz tube 2 wherein a processed element is carried. Next, when the air pressure reaches a specific value, gas is started to be exhausted by a vacuum valve 17 also starting the measurement of oxygen concentration by an oxygen detecting sensor 16. Next, when the measured oxygen concentration reaches the value not exceeding a specific non-dangerous value, the valve 6 is closed simultaneously opening another valve 8 to start feeding hydrogen. When the previously set up hydrogen annealing step finishing requirements are met, the hydrogen feeding step is stopped to start hydrogen exhaust by a vacuum pump 13. Finally, when the air pressure in the quartz tube 2 reaches another specific value, the valve 6 is opened to start feeding nitrogen and when the hydrogen concentration measured by a hydrogen detecting sensor 15 reaches the value not exceeding a specific non-dangerous value, the processed element is to be taken out of the hydrogen annealing furnace 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydrogen anneal furnace, and more particularly to a safe operation method for a hydrogen anneal furnace in which hydrogen and oxygen in the air do not undergo a sudden chemical reaction.

[0002]

2. Description of the Related Art Hydrogen is annealed to a semiconductor wafer in the process of manufacturing a semiconductor. Conventionally, in order to perform such hydrogen annealing, a hydrogen detection sensor is installed in the room where the hydrogen annealing furnace is placed so that the leaked hydrogen and oxygen in the air do not chemically react with each other to cause an accident. Equip,
The notification is made when the hydrogen detection amount by the hydrogen detection sensor reaches a predetermined value. That is, when the mixing ratio of hydrogen to oxygen is 4% to 98%, hydrogen and oxygen are rapidly combined, so that an alarm is provided when the amount of hydrogen detected by the hydrogen detection sensor reaches about 1%.

[0003]

By the way, with the above-mentioned alarm means, there is a time delay from the start of the leak of hydrogen until the alarm is issued, and depending on the cause of the leak, after the alarm is issued. There was a risk that taking corrective action might not be in time, and it was an incomplete safety measure. It is an object of the present invention to provide a safe operation method of a hydrogen anneal furnace which solves the above problems (problems).

[0004]

In order to solve the above-mentioned problems, in a safe operation method of a hydrogen anneal furnace according to the present invention, an inert gas is introduced into a closed container into which a material to be treated is carried in before annealing. The gas containing oxygen was discharged from the sealed container, and hydrogen was supplied after confirming that oxygen was not present in the sealed container in a predetermined amount or more. Further, after the annealing, hydrogen in the closed container was discharged and then an inert gas was supplied, and after confirming that hydrogen was not present in the closed container in a predetermined amount or more, the material to be processed was carried out.

[0005]

According to the present invention, as described above, an inert gas such as nitrogen is supplied to a closed container for carrying a material to be processed such as a semiconductor wafer so that oxygen is not present in a predetermined amount or more in the closed container. After confirmation, hydrogen is supplied to carry out a hydrogen anneal, and after the anneal, the hydrogen in the closed container is discharged, then the above-mentioned inert gas is supplied, and a predetermined amount or more of hydrogen is present in the closed container. I decided to carry out the material to be processed after confirming that it was not done.
Hydrogen and oxygen do not mix in dangerous proportions.

[0006]

EXAMPLE An example of a safe operation method for a hydrogen annealing furnace according to the present invention will be described in detail with reference to the drawings. FIG. 1 shows a schematic configuration example of a hydrogen annealing furnace to which the present invention is applied and its control device. In FIG. 1, reference numeral 1 is an example of a hydrogen annealing furnace, and in this embodiment, an example of a vertical structure in which a material to be treated is carried in from the lower side of a closed container is shown. 2 is a quartz tube which is a closed container (hereinafter referred to as quartz tube), 3
Is a heating heater for anneal provided outside the quartz tube 2, and 4 is a boat into which a material to be treated such as a semiconductor wafer is loaded and which is inserted from below. . In FIG. 1, an elevating mechanism for elevating and lowering the boat 4, a transfer mechanism for loading a processed material on the boat 4 in a lowered state of the boat 4 and lowering the processed material from the boat. Illustrations of the above are omitted. An inert gas supply means and a hydrogen supply means are connected to the quartz tube 2, respectively. That is, a pipe 5 of nitrogen gas which is an inert gas (hereinafter, an inert gas is referred to as nitrogen) passes through a first valve 6, and a pipe 7 of hydrogen gas passes through a second valve 8, respectively. The pipe 9 is connected to the pipe 9, and the pipe 9 is opened at a position above the inner space of the quartz tube 2. The first valve 6 is composed of a flow control device 6a and an air-operated on / off valve 6b, and the second valve 8 is composed of a flow control device 8a and an air-operated on / off valve 8b. An air pipe 10 connected to the outside air is provided in the pipe 9 and a third valve 11 is provided.
Are bound via. The third valve 11 includes a flow rate control device 11a and an air operated on / off valve 11b.
It is composed by.

A first exhaust pipe 12 is connected to the quartz tube 2 for exhaust, and the first exhaust pipe 12 passes through a first exhaust function (referred to as a vacuum pump) 13 to a first exhaust pipe 13. It is connected to two exhaust pipes 14. Second exhaust pipe 1
Reference numeral 4 is coupled to an exhaust treatment device (not shown) which is composed of an exhaust mixing function, an exhaust pump, and the like. The vacuum pump 13 includes an air-operated on / off valve 13a (referred to as a first vacuum valve), a mechanical booster 13b,
It is composed of a dry pump 13c. In addition, a second pipe is provided between the first exhaust pipe 12 and the second exhaust pipe 14.
A second vacuum valve 17 is provided as an evacuation function of. Each of the valves described above, 6, 8, 11, 13a, 17
The maximum flow rate is set according to the application conditions and needs. A hydrogen detecting function 15 as a hydrogen detecting means is connected to the first exhaust pipe 12, and an oxygen detecting sensor 16 as an oxygen detecting means is connected to the second exhaust pipe 14, respectively. The hydrogen detection function 15 is composed of an air-operated on / off valve 15a and a hydrogen detection sensor 15b. The lower mechanism of the quartz tube 2 described above has a bow.
An O-ring 18 is provided so that the lower portion 4a of the grate 4 is in close contact.

A controller 19 for controlling the hydrogen annealing furnace system is connected to a controller (hereinafter referred to as a sequencer) 20 for executing and controlling safe operation according to the present invention so as to transmit a command signal. . The control unit 19 also lifts and lowers the boat 4 (not shown), loads the material to be treated on the boat 4 in the lowered state of the boat 4, and removes the treated material from the boat. It also executes the control of the transfer mechanism to unload.
The sequencer 20 has a first operating function 21 for operating and controlling the first valve 6, a second operating function 22 for operating and controlling the second valve 8, and a third operating function for controlling the third valve 11. 3, an operation function 23 for operating the heater 3, a heater operation function 24 for operating and controlling the heater 3, an exhaust control function 25 for operating and controlling the vacuum pump 13, and an exhaust operation function 26 for operating and controlling the second vacuum valve 17. Each is connected to transmit an operation control signal. The sequencer 20 also includes a first measurement circuit 27 that converts the hydrogen detection signal from the hydrogen detection function 15 described above into a predetermined electric signal, and an oxygen detection sensor 16
Second, which converts the oxygen detection signal by the device into a predetermined electric signal
Are connected to the measuring circuits 28, respectively. Further, a pressure measuring device 29 as a pressure measuring means for measuring a leak state from the closed quartz tube 2 is connected to the quartz tube 2. The pressure measuring device 29 is composed of an air-operated on / off valve 29a and a baratron sensor 29b, operates the pressure measuring device 29, and passes through a third measuring circuit 30 which converts the detection signal into a predetermined electric signal. It is connected to the sequencer 20 for input.

Next, the safe driving method according to the present invention in the embodiment constituted by the above-mentioned circuit functions will be described. The flow chart of FIG. 2 showing the function of the sequencer 20 and the time chart of FIG.
It will be described in detail with reference to FIG. When the operation of the hydrogen annealing furnace is started (time t ₀ shown in FIG. 3) (step 0 shown in FIG. 2), the command signal from the controller 19 causes the boat 4 to operate.
The material to be processed is loaded by a loading mechanism such as a robot (not shown) (time t ₀ to t ₁ shown in FIG. 3) (step 1 shown in FIG. 2). Further, the second vacuum valve 17 is made to function by the operation control signal from the sequencer 20, and the air in the quartz tube 2 is discharged by the exhaust treatment device (not shown) connected to the second exhaust pipe 14. , The first valve 6 is made to function, and nitrogen is supplied into the quartz tube 2 at the set flow rate of the flow rate control device 6a (step 2 shown in FIG. 2). By the elevating mechanism not shown the door 4 quartz Ju - - board loaded with the material to be treated is increased in Bed 2 (to no time t ₁ shown in FIG. 3 t _2). Therefore, the quartz tube 2 is completely sealed by the O-ring 18 and the lower portion 4a of the boat 4 (step 3 shown in FIG. 2). When the quartz tube 2 is closed, the supply of nitrogen to the quartz tube 2 is stopped and the gas in the quartz tube 2 is discharged by the vacuum pump 13. Therefore, quartz Ju - air pressure in Bed 2 drops (to no time t ₂ shown in FIG. 3 t ₃₎ (step 4 shown in FIG. 2).

The leak state of the quartz tube 2 is detected by the measurement signal of the pressure measuring device 29 (time t ₃ to t ₄ shown in FIG. 3) (judgment 1 shown in FIG. 2), and if there is an abnormality, an alarm is issued. and, if there is no abnormality quartz Ju - resumes nitrogen supply to Bed 2 (time t ₄ when FIG. 3) (step 5 shown in FIG. 2). When nitrogen is supplied into the quartz tube 2 and the atmospheric pressure reaches a predetermined value (time t ₅ shown in FIG. 3) (judgment 2 shown in FIG. 2), the second vacuum valve 17 is made to function and the quartz tube is activated. The gas discharge from the inside of the quartz tube 2 is started (step 6 shown in FIG. 2), and the measurement of the oxygen concentration inside the quartz tube 2 by the oxygen detection sensor 16 is started. Therefore, oxygen is replaced with nitrogen in the quartz tube at a predetermined pressure. When the measured oxygen concentration falls below a non-hazardous predetermined value (time t ₆ shown in FIG. 3)
(Judgment 3 shown in FIG. 2), the first valve 6 is closed to stop the supply of nitrogen, and the second valve 8 functions to cause the quartz tube 2 to supply hydrogen at the flow rate set by the flow control device 8a. Starting supply, the nitrogen in the quartz tube is replaced with hydrogen (step 7 shown in FIG. 2), and the heater 3 is made to function to raise the temperature in the quartz tube 2. That is, hydrogen annealing is started (step 8 shown in FIG. 2). During the anneal, the supply of hydrogen and the evacuation by the second vacuum valve 17 are continuously executed in parallel (time t ₆ to t ₇ shown in FIG. 3). The amount of oxygen is measured by the oxygen detection sensor 16 in the second exhaust pipe 14, and the exhaust of hydrogen is started.
Due to the function of an exhaust treatment device (not shown) to which the exhaust pipe 14 is connected, there is no possibility that the discharged hydrogen will chemically react with oxygen in the outside air. When the preset hydrogen annealing completion condition is reached (time t ₇ shown in FIG. 3) (decision 4 shown in FIG. 2), the supply of hydrogen and the function of the heater 3 are stopped, and the vacuum pump 13 is made to function. Then, the exhaust of hydrogen from the quartz tube 2 is started (step 9 shown in FIG. 2). When the atmospheric pressure in the quartz tube 2 measured by the pressure measuring device 29 reaches a preset pressure value (time t ₈ shown in FIG. 3) (determination 5 shown in FIG. 2), the first valve 6 is made to function. Then, the supply of nitrogen to the quartz tube 2 is started, and the second vacuum valve 17 is operated in place of the vacuum pump 13 to discharge the gas in the quartz tube 2 (step 1 shown in FIG. 2).
0). Therefore, replacement of hydrogen and nitrogen in the quartz tube is started. Further, the hydrogen detection function 15 is made to function from a predetermined timing set in advance to start the hydrogen concentration measurement in the quartz tube 2 (time t ₉ shown in FIG. 3). Quartz tu
When the hydrogen concentration in the valve 2 becomes equal to or less than a predetermined value without danger (time t ₁₀ shown in FIG. 3) (judgment 6 shown in FIG. 2), hydrogen annealing is performed.
Ball loaded with workpiece completing Le - lowering the lifting mechanism (not shown) the door 4 (to the time t ₁₀ not shown in FIG. 3 t ₁₁₎ (step 11 shown in FIG. 2). Quartz tube 2
Is released from the outside air, but since the hydrogen concentration in the quartz tube 2 is less than a predetermined value without danger, there is no danger of causing a rapid chemical reaction with oxygen in the outside air. The processed material to be processed is unloaded from the boat 4 (time t shown in FIG. 3).
₁₁ to t ₁₂ ) (step 12 shown in FIG. 2). Thereafter, the above sequence is repeated by returning to step 1 until the all hydrogen annealing work is completed (decision 7 and step 13 shown in FIG. 2). When the all hydrogen annealing work is completed as described above, or if necessary, the third valve 11 and the second vacuum valve 17 connected to the outside air are made to function to eliminate nitrogen in the quartz tube 2. ..

The above description shows the structure for realizing the technical idea of the present invention and the safe operation method according to the basic method, and each measuring means corresponds to the conditions of the hydrogen annealing furnace. It is natural that the configuration, type and configuration of valves and pumps can be appropriately applied and modified.

[0012]

As described above, the safe operation method of the hydrogen anneal furnace of the present invention is such that the surface treatment of the material to be treated such as the semiconductor wafer is carried out by interposing an inert gas such as nitrogen. There is an excellent effect that the operation can be performed while ensuring safety as follows. Hydrogen can be supplied to the hydrogen annealing furnace after confirming that oxygen does not remain above the dangerous value. When the hydrogen is discharged from the hydrogen anneal furnace, oxygen does not exist in the discharge pipe above the dangerous value. When the processed material is discharged, hydrogen does not remain in the closed container. Hydrogen and oxygen are not mixed in dangerous proportions according to the above conditions. Since hydrogen and oxygen are not mixed in a dangerous ratio, there is no possibility of causing an explosion accident due to a rapid chemical reaction between hydrogen and oxygen.

[Brief description of drawings]

FIG. 1 is a block diagram showing an example of a hydrogen anneal furnace and a control device for the hydrogen anneal furnace to which a safe operation method for a hydrogen anneal furnace according to the present invention is applied.

FIG. 2 is a schematic flow chart in the case where the safe operation method of the hydrogen annealing furnace according to the present invention is applied to the hydrogen annealing furnace and the control device thereof in the configuration shown in FIG.

FIG. 3 is a schematic time chart diagram when the safe operation method of the hydrogen annealing furnace according to the present invention is applied to the hydrogen annealing furnace and the control device thereof in the configuration shown in FIG.

[Explanation of symbols]

 1: Hydrogen anneal furnace 2: Quartz tube (closed vessel) 3: Heater 4: Boat 5: Nitrogen gas (inert gas) piping 6, 8, 11: Valve 7: Hydrogen gas piping 12 , 14: Exhaust pipe 13: Vacuum pump 15: Hydrogen detection function (hydrogen detection means) 16: Oxygen detection sensor (oxygen detection means) 17: Vacuum valve 19: Control device 20: Sequencer

Claims (1)

[Claims] 1. A hermetically sealed container, a boat for carrying out and carrying in a material to be treated into the hermetically sealed container, a means for driving the boat, a hydrogen supply means, an exhaust means, and a means for heating the material to be treated. In the hydrogen anneal furnace, an inert gas supply means, a hydrogen detection means, and an oxygen detection means are provided, and the hydrogen anneal is performed by the following sequence. How to safely operate the furnace. Exhaust the gas in the closed container and supply the inert gas. The material to be treated is carried into a closed container, and the closed container is closed. Evacuate the gas in the closed container. Hydrogen is supplied after confirming that oxygen does not exist in the sealed container in a predetermined amount or more. Hydrogen annealing of the material to be processed is performed. The hydrogen in the closed container is discharged. Inert gas is supplied to the closed container. The material to be processed is carried out after confirming that hydrogen does not exist in the closed container in a predetermined amount or more.