JP2002328729A - Signal processor for thermocouple, signal processing method for thermocouple and heat treating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To execute accurate temperature detection at the time of doubling thermocouples in a heat treating unit for performing heat treatment to a semiconductor substrate. SOLUTION: The larger one of the electromotive forces of one doubled thermocouple and the other thermocouple is selected as a temperature detection value. One connecting terminal of each thermocouple is constituted so that a voltage for pull-up can be switched so as to be supplied or grounded by a switch, and normally connected to a ground side. When the difference or rate of the both electromotive forces is monitored, and the value is made large, that is, when one thermocouple is about to be disconnected, and the electromotive force is made low, it is judged that one thermocouple is disconnected, and the switch related with the other thermocouple is switched to the pull-up side. Afterwards, when one thermocouple is disconnected, control is executed to the safe side (so that it can be recognized that the temperature detection value is high).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a thermocouple signal processing device, a thermocouple signal processing method, and a heat treatment device.

[0002]

2. Description of the Related Art Thermocouples are used as temperature detecting means in various fields. For example, thermocouples are incorporated in a temperature control system in a heat treatment apparatus in a semiconductor manufacturing process. When a thermocouple is used in the heat treatment apparatus, if the thermocouple is disconnected, the temperature cannot be detected and predetermined processing cannot be performed. Further, there is a possibility that an overheat state may be caused. Therefore, the thermocouple is usually duplicated.

FIG. 11 is a diagram showing a conventional example of this type of thermocouple signal processing device, which is duplexed by thermocouples 1A and 1B. Both ends of one thermocouple 1A are connected to one connection terminal 11a and the other connection terminal 11b, respectively.
The other connection terminal 11b is grounded via a resistor r4. The connection terminals 11a and 11b are connected to both input terminals of the operational amplifier 12A via resistors r1 and r2, respectively, and a capacitor 13 forming a low-frequency filter together with the resistors r1 and r2 is connected between the input terminals. A similar circuit is combined with the other thermocouple 1B, and the operational amplifier is denoted by 12B, but other corresponding parts are denoted by the same reference numerals.

The output terminals of the operational amplifiers 12A and 12B are:
It is connected to a control unit 16 via a multiplexer 14 and an A / D converter 15. The control unit 16 selects and takes in the signal of a predetermined thermocouple of the duplicated thermocouples 1A and 1B, for example, the signal of the thermocouple 1A by the multiplexer 14, and detects the detected value by a temperature controller (not shown). To control the temperature.

Further, in order to detect a disconnection of the thermocouple 1A (1B), a pull-up voltage is supplied from the voltage source VC via the resistor r3 to the one connection terminal 11a. Since the resistance of the thermocouple 1A (1B) is, for example, about 10Ω, which is smaller than the impedance of the voltage source VC, the voltage generated by the electromotive force of the thermocouple 1A (1B) is substantially applied to the operational amplifier 12A (12B). Will be entered. However, for example, when the thermocouple 1A is disconnected, the capacitor 13 is charged by the pull-up voltage of the voltage source VC, and the operational amplifier 12
When the voltage between the two input terminals of A rises, and the output voltage of the operational amplifier 12A rises and exceeds a preset threshold, the control unit 16 determines that there is a disconnection and, for example, an alarm And the multiplexer 1
4 switches the thermocouple to be used from 1A to 1B.

[0006]

Since the voltage generated by the electromotive force tends to decrease when the thermocouple is deteriorated, even if one of the thermocouples 1A (1B) selected in advance is deteriorated, the deteriorated thermocouple is used. Since the temperature is controlled by reading the electromotive force voltage of 1A (1B), the accuracy of the detected temperature is reduced, and high-precision temperature control cannot be performed. As a result, for example, in the case of a batch furnace for heat-treating a semiconductor wafer, a predetermined film thickness cannot be obtained, or in-plane uniformity on a wafer or inter-wafer uniformity between wafers deteriorates. Further, when the selected thermocouple 1A (1B) is about to be disconnected, the electromotive force voltage is greatly reduced. Therefore, the control unit 16 recognizes that the temperature has decreased before the disconnection. There is a possibility that the heater power is increased and the temperature rises excessively. Further, when the thermocouple 1A (1B) is disconnected, the operational amplifier 12A (1B) is pulled up by the pull-up voltage.
Since the output voltage of 2B) rises, accurate temperature control cannot be performed until the output voltage exceeds the threshold and the thermocouple is switched. For example, when an extremely thin oxide film is formed. In this case, there is a concern that the inaccuracy of the temperature control is largely reflected on the film thickness, which affects the yield.

Further, when the output voltage exceeds the threshold, the voltage source VC is disconnected from the thermocouple 1A (1B) by a switch (not shown), but the capacitor 13 is charged by the pull-up voltage applied until then. Therefore, a voltage is generated at both ends of the capacitor 13 due to the dielectric absorption action of the capacitor 13. For this reason, it takes a long time until the capacitor 13 discharges after replacing the thermocouple 1A (1B) on the disconnection side, and it is necessary to allow the time until the correct temperature can be detected.

The present invention has been made under such circumstances, and an object of the present invention is to provide a signal processing apparatus which uses a duplicated thermocouple and processes a signal corresponding to the electromotive force voltage, to obtain an accurate temperature. It is to provide a technique capable of performing measurement. It is still another object of the present invention to provide a technique capable of performing a favorable process on an object to be processed in a heat treatment apparatus that performs temperature control using a thermocouple.

[0009]

SUMMARY OF THE INVENTION A signal processing device for a thermocouple according to the present invention is a device for processing a signal corresponding to an electromotive force voltage of a thermocouple duplicated by a first thermocouple and a second thermocouple. A first circuit including one connection terminal and the other connection terminal to which both ends of the first thermocouple are respectively connected, and a capacitor connected between the connection terminals; and the second thermocouple. A second circuit including one connection terminal and the other connection terminal, both ends of which are connected to each other, and a capacitor connected between these connection terminals, and a voltage across the capacitor of the first circuit and the second circuit. And an amplifying unit for amplifying the first signal.
From the amplifying unit corresponding to the electromotive force voltage of the thermocouple
Means for comparing the output signal of the second thermocouple with the second output signal from the amplifying unit corresponding to the electromotive force voltage of the second thermocouple, and selecting a higher output signal as a temperature detection value. Features. According to the present invention, a configuration is provided that includes means for determining whether or not any of the first thermocouple and the second thermocouple is disconnected based on the first output signal and the second output signal. Can be. Further, both connection terminals of the first thermocouple and both connection terminals of the second thermocouple are grounded, for example, via respective resistors. Another invention is an apparatus for processing a signal corresponding to an electromotive force voltage of a thermocouple duplexed by a first thermocouple and a second thermocouple, wherein both ends of the first thermocouple are connected respectively. A first circuit including one connection terminal and the other connection terminal, and a capacitor connected between the connection terminals; one connection terminal and the other connection terminal to which both ends of the second thermocouple are respectively connected; And a second circuit including a capacitor connected between the connection terminals, and an amplifying unit for amplifying a voltage between both ends of the capacitors of the first circuit and the second circuit. In the processing device, the first thermocouple and the second thermocouple are provided respectively corresponding to the first thermocouple and the one connection terminal side, for detecting a disconnection higher than the electromotive force voltage of the thermocouple in a use temperature band. Voltage or ground voltage And a supply voltage supplied to the one connection terminal side from each of the voltage supply units relating to the first thermocouple and the second thermocouple as a ground voltage. A first output signal of the amplifying unit corresponding to the electromotive force voltage of the pair and a second output signal of the amplifying unit corresponding to the electromotive force voltage of the second thermocouple, which is higher than the first output signal; Means for selecting as a temperature detection value, and determines whether any of the first thermocouple and the second thermocouple is disconnected based on the first output signal and the second output signal, When it is determined that one of the thermocouples is disconnected, the supply voltage supplied to the one connection terminal side from the voltage supply unit related to the uncoupled thermocouple is set as the disconnection detection voltage. And a control means.

Each means in the present invention can be configured to include a predetermined program, a storage unit for storing the program, a CPU for executing the program, and the like. In the present invention, whether or not one of the first thermocouple and the second thermocouple is disconnected is determined based on, for example, a difference or a ratio between the first output signal and the second output signal. Will be When it is determined that one of the thermocouples is disconnected, the supply voltage supplied from the voltage supply unit for the disconnected thermocouple to the one connection terminal side is kept at the ground voltage. Is preferred. The voltage supply unit may include a voltage source for the disconnection detection voltage, a ground, and a switch that switches and connects the one connection terminal side between the voltage source and the ground, Alternatively, it may be constituted by a digital / analog converter.

When a thermocouple is deteriorated, it becomes lower than an original electromotive voltage corresponding to a temperature. Therefore, selecting a higher voltage has an effect that the thermocouple is less affected by the deterioration. When it is determined that one of the thermocouples is disconnected, the other thermocouple is left pulled down, and the uncoupled thermocouple is switched to the pull-up state, so that the remaining thermocouples are disconnected. Even if the wire is broken, it looks as if the temperature has become high, so that it is possible to prevent the temperature from becoming too high in the temperature control. In this case, after one thermocouple is disconnected, the output signal of the amplifying unit corresponding to the electromotive voltage of the other thermocouple is monitored, and when the output signal exceeds a preset value, the thermocouple is activated. By providing a means for determining that a disconnection has occurred, the other disconnection can also be detected.

Further, before the supply voltage supplied to one of the connection terminals of the first thermocouple and the second thermocouple is set to the ground voltage, the supply voltage is set to the disconnection detection voltage. It is preferable to confirm that neither the first thermocouple nor the second thermocouple is disconnected from the beginning based on the first output signal and the second output signal.

[0013] The present invention also holds in a method invention, which comprises a method of processing a signal corresponding to an electromotive force voltage of a thermocouple duplicated by a first thermocouple and a second thermocouple. A step of amplifying an electromotive force voltage of the first thermocouple by an amplifying unit having a capacitor connected between input terminals, and connecting an electromotive force voltage of the second thermocouple to a capacitor between input terminals. Amplifying by the amplified amplifying unit, the first output signal from the amplifying unit corresponding to the electromotive force voltage of the first thermocouple, and the amplifying unit corresponding to the electromotive force voltage of the second thermocouple And selecting the higher output signal as the detected temperature value by comparing the second output signal with the second output signal from the second output signal.

Another method is a method of processing a signal corresponding to an electromotive force of a thermocouple duplicated by a first thermocouple and a second thermocouple, and both ends of the first thermocouple are respectively provided. A first circuit including one connection terminal and the other connection terminal to be connected, and a capacitor connected between the connection terminals; one connection terminal to which both ends of the second thermocouple are respectively connected; A thermocouple comprising: a second circuit including a connection terminal and a capacitor connected between the connection terminals; and an amplifying unit for amplifying a voltage between both ends of the capacitor of the first circuit and the second circuit. In the signal processing method using the signal processing device of (1), the supply voltage supplied to one of the connection terminals of the first thermocouple and the second thermocouple is set as a ground voltage, and the first thermocouple is connected to the first thermocouple. The amplifying unit corresponding to the pair of electromotive force voltages Comparing the first output signal with the second output signal from the amplifying unit corresponding to the electromotive voltage of the second thermocouple, and selecting a higher output signal as a temperature detection value. Determining whether one of the first thermocouple and the second thermocouple is disconnected based on the first output signal and the second output signal; and disconnecting one of the thermocouples. When it is determined that the thermocouple is not disconnected, the supply voltage supplied to the one connection terminal of the thermocouple that is not disconnected is set to a voltage for disconnection detection higher than the electromotive voltage of the thermocouple in the operating temperature band. And controlling the
It is characterized by including. Furthermore, in the heat treatment apparatus of the present invention, the object to be processed is placed in the processing container, the object is heated by the heating means to perform predetermined processing, and the temperature is detected by the thermocouple, and the detection result is obtained. A heat treatment apparatus for controlling the power supply to the heating means based on the above is provided with the above-mentioned signal processing device.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the thermocouple signal processing apparatus of the present invention is applied to a heat treatment apparatus, for example, a vertical heat treatment apparatus will be described below. First, the vertical heat treatment apparatus will be briefly described with reference to FIG. 1, and then the signal processing apparatus will be described with reference to FIG. Reference numeral 2 in FIG. 1 denotes a double-walled reaction tube composed of an inner tube 2a and an outer tube 2b made of, for example, quartz. A metal cylindrical manifold 21 is provided below the reaction tube 2. Have been.
The upper end of the inner pipe 2 a is opened, and is supported on the inner side of the manifold 21. The upper end of the outer tube 2b is closed, and the lower end is airtightly joined to the upper end of the manifold 21. In this example, a processing container is constituted by the inner tube 2a, the outer tube 2b, and the manifold 21.

In the reaction tube 2, a large number of, for example, 126 wafers W to be processed are placed in a horizontal state in a wafer boat 22 as a holder in the reaction tube 2 at intervals in the horizontal state. Is placed. The wafer boat 22 is held on a lid 23 via a heat insulating cylinder 24 as a heat insulating unit. The lid 23 serves as a boat elevator 2 for carrying the wafer boat 22 into and out of the reaction tube 2.
5 and has a role of closing the lower end opening of the manifold 21, that is, the lower end opening of the processing vessel formed by the reaction tube 2 and the manifold 21 when in the upper limit position.

Around the reaction tube 2 is provided a heater 26 made of, for example, a resistance heater so as to surround the reaction tube 2. In this example, the heat treatment atmosphere in the reaction tube 2 is divided into a plurality of, for example, four, and the heaters 26 are divided into four stages (26-1 to 264) corresponding to the respective divided regions to control the temperature zone. (Temperature control of divided areas) is performed. Although not shown in FIG. 1, a heat insulating layer is provided around the heater 26 to constitute a heating furnace. A gas supply pipe 27 is provided around the manifold 21, and an exhaust pipe 28 is connected so that air can be exhausted from a space between the inner pipe 2a and the outer pipe 2b.

Each heater 26 (26-1 to 26-4)
A temperature controller 20 is provided corresponding to
A thermocouple 3 is provided between the reaction tube 2 and each heater 26 (26-1 to 26-4), and the temperature controller 20 is not shown based on the detected temperature value of each thermocouple 3. The amount of heat generated by the heaters 26 (26-1 to 26-4) is adjusted via a power supply unit, thereby controlling the temperature of each divided region in the reaction tube 2.

In the process in this vertical heat treatment apparatus, after the wafer W to be processed is mounted on the wafer boat 22 and loaded into the processing vessel, the inside of the reaction tube 2 is heated to a predetermined temperature. The pressure is reduced to a predetermined pressure by the exhaust pipe 28, and the processing gas is supplied from the lower side of the processing vessel through the gas supply pipe 27, for example, is decomposed into thin film components and deposited on the wafer W, and the remaining gas is supplied to the inner pipe. 11a
From the ceiling part, the space between the inner pipe 2a and the outer pipe 2b descends, and is exhausted through the exhaust pipe 28.

In the vertical heat treatment apparatus, a thermocouple may be provided in the inner tube 2a in addition to the thermocouple 3 to perform temperature control based on thermocouples inside and outside the reaction tube 2. A signal processing device for processing a signal of the thermocouple 3 provided between the reaction tube 2 and each heater 26 (26-1 to 26-4) will be described with reference to FIG. The signal processing device shown in FIG. 2 is incorporated in the temperature controller 20, and in FIG. 1, each heater 26 (26-1 to 26-4)
Although one thermocouple 3 is shown for each, in practice, each thermocouple 3 is duplicated in the same divided region (zone). Therefore, one and the other of the duplicated thermocouples 3 are connected to a first thermocouple 3 (3A) and a second thermocouple 3 respectively.
The description will be given below with reference to (3B).

In FIG. 2, both ends of the first thermocouple 3A are connected to signal lines 33 and 34 via one connection terminal 31 and the other connection terminal 32, respectively. The signal lines 33 and 34 are connected to the operational amplifier 4A. Connected to input terminal. Signal lines 33, 34
, Resistors R1 and R2 are interposed, respectively, and a capacitor C1 is connected between each side of the resistors R1 and R2, and a low-frequency filter is formed by the resistors R1, R2 and the capacitor C1. The signal line 33 is connected to a switch 5A via a resistor R3 at a preceding stage of the resistor R1. The switch 5A is connected to one end of the resistor R3 and a contact 51 on the side of a voltage source VC having a power supply voltage of + 2V, for example.
And a function of switching and connecting to one of the contacts 52 on the side of the power supply.

The voltage source VC is for supplying a pull-up voltage for disconnection detection to one connection terminal 31 applied to the first thermocouple 3A, that is, the capacitor C1, and therefore has a large power supply voltage of the voltage source VC. In other words, it is necessary to set the electromotive force voltage of the thermocouple exceeding the assumed temperature of the use band or a voltage higher than the maximum voltage of the electromotive force that can be generated by the thermocouple. In this example, the switch 5A, the voltage source VC
And the earth correspond to the voltage supply unit described in the claims. Note that the signal line 34 is connected to the ground before the resistor R2 via the resistor R4.

The output terminal of the operational amplifier 4A is connected to a multiplexer 6 and an analog / digital (A / D) converter 6.
1 is connected to the control unit 7.

The second thermocouple 3B has the same circuit configuration as that of the first thermocouple 3A, and the same parts are denoted by the same reference numerals. Regarding the operational amplifier and the switch, respectively, C1,
4B and 5B codes are assigned. Further, the connection terminals 31 and 32 of the first thermocouple 3A and the capacitor C1
And the resistors R1 to R4 correspond to the first resistor described in the claims.
Of the second thermocouple 3B, the connection terminals 31 and 32, the capacitor C2, and the resistors R1 to R3.
4 corresponds to the second circuit 30B described in the claims. Furthermore, the operational amplifiers 4A and 4B constitute an amplifying unit described in the claims in this example.

The control unit 7 includes a CPU 71, a ROM 72 storing programs and the like, and an R
The AM 73 and the like are connected by a bus 70, take in the temperature detection values of the thermocouples 3A and 3B, perform predetermined processing (this processing will be described in detail later), and based on the processing result. It has a function of outputting a contact switching signal to the switches 5A and 5B.

Next, the operation of the above embodiment will be described. FIG. 3 is a flowchart showing the operation of the signal processing device described above. In the first stage, the switches 5A and 5A are switched by the switching signal from the control unit 7 as shown in step S1.
B is switched to the pull-down side, that is, the contact 52 side. On the other hand, the electromotive force voltages (voltages generated by the electromotive force) of the thermocouples 3A and 3B are amplified by the operational amplifiers 4A and 4B, respectively, and the multiplexer 6 alternates the output terminals of the operational amplifiers 4A and 4B by the control signal from the control unit 7. The first output signal from the operational amplifier 4A and the second output signal from the operational amplifier 4B are alternately taken into the control unit 7 via the A / D (analog / digital) converter 61. In this manner, each voltage, that is, the voltage value EA corresponding to the electromotive voltage of the thermocouple 3A and the voltage value EB corresponding to the electromotive voltage of the thermocouple 3B are read into the control unit 7 and read, for example, RA
It is stored in M73 (step S2).

Next, in step S3, it is determined which of the voltage value EA and the voltage value EB is higher. If the voltage value EA is larger, the voltage value EA is selected as a temperature detection signal (step S4), and the voltage value EB is determined. If it is larger, the voltage value EB is selected as the temperature detection value (step S5).
The temperature controller 20 performs temperature control as described above based on the selected temperature detection signal. In step S6, it is determined whether or not the difference between the voltage value EA and the voltage value EB is equal to or greater than a set value. If the difference is smaller than the set value, the process returns to step S2 to read the voltage value EA and the voltage value EB. Will be done again.

FIG. 4 is an explanatory diagram schematically showing a temporal change of the electromotive force voltage of the thermocouples 3A and 3B. The solid line and the dotted line show the electromotive force voltage (voltage EA) of the thermocouples 3A and 3B, respectively.
And a voltage value EB). Until time t1, none of them has deteriorated and their electromotive force voltages are almost the same value over time. At this time, the control unit 7 selects the higher voltage value although the difference between the two is small. Whichever value is selected, it is substantially the same, and an accurate temperature detection value can be obtained.
Here, assuming that the first thermocouple 3A has deteriorated at time t1 and its electromotive voltage has become lower, the voltage value EB is higher than the voltage value EA.
The voltage value EB which is the electromotive voltage of B is selected, and the temperature is controlled based on the value.

Next, at step S6, the voltage value EA and the voltage value E
The case where the difference from B is equal to or greater than a predetermined set value will be described. In this case, it is determined in step S7 which of the voltage value EA and the voltage value EB is higher, and it is determined that the voltage value EA is higher. If so, the control unit 7 recognizes that the thermocouple 3B is disconnected (step S8), and if it determines that the voltage value EB is high, the control unit 7 recognizes that the thermocouple 3A is disconnected (step S9).

FIG. 5 is an explanatory view schematically showing the temporal change of each of the voltage value EA and the voltage value EB until the thermocouple 3B is disconnected, and thereafter, all deteriorate until the time t1. However, the voltage has almost the same value over time, and in this case, as described above, even if any value is selected, the voltage is substantially the same, and an accurate temperature detection value can be obtained. Here, assuming that the thermocouple 3B is about to be disconnected due to deterioration at time t1, the voltage value EB gradually decreases, and the voltage value EA is selected in step S4. Then, as described above, the difference between the voltage value EA and the voltage value EB is monitored in step S6, and if the difference becomes equal to or greater than the set difference value ΔE at time t2, the process proceeds to step S7 to determine which is higher. . Since the voltage value EA is higher in the example of FIG.
Determines that the thermocouple 3B is disconnected in step S8. It should be noted that the disconnection is determined, for example, by using the voltage value EA and
Out of the higher ones (in this example, EB
/ EA) may be checked, and a step corresponding to this processing enters step S6.

Subsequently, the thermocouple 3A (3
A switching signal is output from the control unit 7 so that the contact point of the switch 5A (5B) according to B) is switched to the pull-up side (51 side). In the example of FIG. 5, since the thermocouple 3B is disconnected, the switch 5A related to the thermocouple 3A is switched to the pull-up side (step S10), and for example, a voltage of +2 V is applied to the preceding stage of the resistor R1. In this case, thermocouple 3A
Is sufficiently smaller than the impedance of the voltage source VC, so that the operational amplifier 4A receives the substantial electromotive voltage of the thermocouple 3A. The reason for pulling up the previous stage of the resistor R1 is that if the thermocouple 3
If A is also disconnected, the voltage value EA decreases, and when viewed from the control unit 7, the temperature is lowered and the power of the heater 26 is controlled to be increased, which may cause an overheating state.

On the other hand, the thermocouple 3B (3
Regarding the contact of the switch 5B (5A) according to A), the output signal is not selected on either side of the switch 51B or 52B, so that the temperature control is not affected. However, when the thermocouple is replaced, the capacitor C2 (C1) is used. It is preferable to switch to the earth side (contact point 52 side) in order to suppress the dielectric absorption.

Thus, after time t2, the normal electromotive force voltage (voltage value EA) of the thermocouple A is read, and temperature control is performed using this as the detected temperature value (step S11). The selection of the voltage value EA is performed, for example, by reading both the voltage value EA and the voltage value EB by the control unit 7, but making only the voltage value EA valid. Then, it is determined whether or not this voltage value EA is higher than a predetermined set value E1 (step S1).
12) If it is smaller than the set value E1, the process returns to step S11.

Here, in FIG. 5, at time t3, the thermocouple 3
If A is disconnected, the voltage value EA gradually increases (specifically, the voltage value EA temporarily drops immediately before disconnection). If the voltage value EA exceeds a predetermined value at time t4, the thermocouple 3A is disconnected in step 13. An alarm is issued to notify that the operation has been performed, for example, the operation of the apparatus is stopped.
Examples of the alarm include an alarm sound, lighting of a lamp, and display on a screen. Before disconnection of both thermocouples 3A and 3B, one thermocouple 3A
An alarm may also be issued when it is determined that (3B) is disconnected. When the thermocouple 3A is disconnected first, the switch 5B related to the thermocouple 3B is switched to the pull-up side (Step S14), and thereafter, Step S15 is performed.
Similar processing is performed as shown in FIGS.

According to the above-described embodiment, the following effects can be obtained. (1) As described above, when the thermocouple is deteriorated, it becomes lower than the original electromotive voltage corresponding to the temperature. It is hard to receive. For this reason, highly accurate temperature control can be performed, and processing with high in-plane uniformity can be performed when heat-treating a wafer. (2) The difference (or ratio) between the electromotive force voltages of both thermocouples is determined, and when the value exceeds the set difference value, it is determined that the thermocouple corresponding to the lower electromotive voltage is disconnected. So
Disconnection can be reliably detected. (3) Since the disconnection is detected with both thermocouples in the pull-down state, the dielectric absorption of the disconnected capacitor C1 (or C2) is suppressed. Therefore, when the thermocouple is replaced, the output signal relating to the new thermocouple quickly shows an accurate value. (4) After judging that one of the thermocouples is disconnected, the other thermocouple is pulled up (supplying a voltage for disconnection detection to one of the connection terminals 31). Even if the other thermocouple is disconnected, the voltage for disconnection detection is applied to the capacitor, so that the input voltage of the operational amplifier is increased and the output signal is increased.
On the side, it looks as if the temperature has risen, so that overheating can be prevented.

Here, the probability that both the thermocouples 3A and 3B are disconnected when the power is turned on is extremely low. However, if such a case is taken into consideration, the program used in the above-described signal processing apparatus is shown in FIG. 6 may be added to the flow of FIG. In the flow of FIG. 6, first, step S2
In step 1, both switches 5A and 5B are switched to the pull-up side, that is, to the contact 51 side. And step S22
Reads the voltage value EA and the voltage value EB, and
At 23, it is determined whether or not the voltage value EA is larger than the set value 1.
It is determined whether it is greater than (steps S24, S2
5). This set value 1 is the same value as the set value E ｀ shown in FIG. 5 described above, and if the thermocouple 3A (3B) is disconnected,
Since the pull-up voltage charges the capacitor C1 (C2) as described in steps S10 and S14 of FIG.
The voltage value EA (EB) exceeds the set value 1. If it is determined that both thermocouples 3A and 3B are disconnected (step S26), then, for example, an alarm is generated (not shown) and the flow ends there, and the thermocouple 3A
If only the wire is disconnected, the voltage value EB is selected, and then the process proceeds to step S15 in FIG. 3 (steps S27 and S2).
8) If only the thermocouple 3B is disconnected, the voltage value EA is selected, and then the process proceeds to step S11 in FIG.

On the other hand, each of the voltage values EA and EB has the set value 1
If the voltage value is smaller than the voltage value EA or EB, the larger value is selected (step S).
31, 32, 33). After that, the process may shift to the start in FIG. 3. At this point, if the switches 5A and 5B are immediately switched to the pull-down side, for example, if both of the thermocouples 3A and 3B are disconnected near normal temperature, this Disconnection cannot be detected. Referring to FIG. 7, the reason is as follows. FIG. 7 shows that the thermocouples 3A and 3B are near normal temperature until time t5, and then the voltage values EA and E when the temperature rises.
5B shows a change in B, in which the thermocouple 3B is disconnected near time t5. In this case, since the voltage value EA increases, the disconnection of the thermocouple 3B can be detected after step S6 in FIG. 3, but both of the thermocouples 3A and 3B are disconnected before the temperature has risen. And the voltage value E
The difference between A and EB does not open. Therefore, a set value 2 is set to give a margin to the voltage value EA (EB) when the thermocouple 3A (3B) is disconnected, and both the thermocouples 3A and 3B are set to the set value 2 in step S34. After confirming that it is larger than the threshold value, the process moves to the start in FIG. The set value 2 is the voltage value EA at the process temperature.
If it is larger than (EB), it does not shift to the start of FIG. 3, so that the voltage value EA (EB) at a value smaller than the process temperature, for example, about 100 ° C.

In the above, in the above embodiment, the first
After the electromotive force voltages of the thermocouple 3A and the second thermocouple 3B are amplified by operational amplifiers 4A and 4B, respectively, the output signals are sequentially taken into the control unit 7 by the multiplexer 6, as shown in FIG. A common operational amplifier 4 is used as an operational amplifier, and a multiplexer 60 is provided in a stage preceding the operational amplifier 4 so that the first thermocouple 3A and the second
Each electromotive force voltage of the thermocouple 3B may be sequentially input to the operational amplifier 4 by the multiplexer 60. In this case, the operational amplifier 4 corresponds to an amplifier.

In the above embodiment, the one connection terminal 31 is used as a voltage supply unit for supplying a disconnection detection voltage or a ground voltage higher than the electromotive voltage of the thermocouple in the operating temperature band. Although the switch 5A (5B) is used, as shown in FIG. 9, a D / A (digital / analog) converter 8 is used, and the output is controlled by a control signal from the control unit 7 to detect a disconnection voltage or a ground voltage ( 0
V).

Further, according to the present invention, the switch 5A (5
B) or one D / A (digital / analog) converter 8 may be used, and one connection terminal 31 may be always grounded as shown in FIG. 10, in which case the thermocouple 3A
(3B) Even after disconnection of one thermocouple 3B
(3A) remains pulled down, but the rest is the same as in the above embodiment.

[0041]

As described above, according to the present invention, an accurate temperature measurement can be performed in a signal processing device that processes a signal corresponding to the voltage by using a duplicated thermocouple. Further, in a heat treatment apparatus that performs temperature control using a thermocouple, favorable processing can be performed on an object to be processed.

[Brief description of the drawings]

FIG. 1 is a vertical sectional side view showing a vertical heat treatment apparatus to which a thermocouple signal processing apparatus of the present invention is applied.

FIG. 2 is a circuit diagram showing an embodiment of a thermocouple signal processing device according to the present invention.

FIG. 3 is a flowchart showing the operation of the above embodiment.

FIG. 4 is an explanatory diagram illustrating an example of a change in voltage of a first thermocouple and a second thermocouple.

FIG. 5 is an explanatory diagram showing another example of a change in voltage of a first thermocouple and a second thermocouple.

FIG. 6 is a flowchart showing a modified example of the flowchart shown in FIG. 3;

FIG. 7 is an explanatory diagram showing still another example of a change in voltage of a first thermocouple and a second thermocouple.

FIG. 8 is a circuit diagram showing a modification of the embodiment of FIG. 2;

FIG. 9 is a circuit diagram showing another embodiment of the thermocouple signal processing device of the present invention.

FIG. 10 is a circuit diagram showing still another embodiment of the thermocouple signal processing device of the present invention.

FIG. 11 is a circuit diagram showing a conventional thermocouple signal processing device.

[Explanation of symbols]

 Reference Signs List 2 reaction tube 20 temperature controller 22 wafer boat W semiconductor wafer 26 heater 3 thermocouple 3A first thermocouple 3B second thermocouple 30A first circuit 30B second circuit 31 one connection terminal 32 the other connection terminal 4 , 4A, 4B Operational amplifier 5A, 5B Switch 6, 60 Multiplexer 61 A / D converter 7 Control unit 8 D / A converter

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01L 21/22 501 H01L 21/22 501N 511 511Q // G05B 9/03 G05B 9/03 F term (reference) 2F056 KL01 KL03 KL06 KL07 KL09 4K056 AA09 BA01 BB06 CA18 FA04 FA13 5H209 AA05 AA11 BB02 DD02 EE08 FF08 GG02 JJ01 JJ07 JJ09 SS01 SS04 SS07 TT01 5H323 AA05 BB17 CB02 FF03 GG02 NN

Claims (15)

[Claims] An apparatus for processing a signal corresponding to an electromotive force voltage of a thermocouple duplicated by a first thermocouple and a second thermocouple, wherein both ends of the first thermocouple are connected respectively. A first circuit including one connection terminal and the other connection terminal and a capacitor connected between the connection terminals, and one connection terminal and the other connection to which both ends of the second thermocouple are respectively connected. A second circuit including a terminal and a capacitor connected between the connection terminals; and an amplifying unit for amplifying a voltage between both ends of the capacitor of the first circuit and the second circuit. In the signal processing device, a first output signal from the amplifying unit corresponding to the electromotive force voltage of the first thermocouple and a second output signal from the amplifying unit corresponding to the electromotive force voltage of the second thermocouple Compare the output signal with the higher output signal Thermocouple signal processing apparatus characterized by comprising means for selecting as a detection value. 2. The apparatus according to claim 1, further comprising means for judging whether or not one of the first thermocouple and the second thermocouple is disconnected based on the first output signal and the second output signal. The signal processing device for a thermocouple according to claim 1. 3. A connection between both connection terminals of the first thermocouple and the second connection terminal.
3. The thermocouple signal processing device according to claim 1, wherein both connection terminals of the thermocouple are grounded via respective resistors. 4. An apparatus for processing a signal corresponding to an electromotive voltage of a thermocouple duplexed by a first thermocouple and a second thermocouple, wherein both ends of the first thermocouple are connected respectively. A first circuit including one connection terminal and the other connection terminal, and a capacitor connected between the connection terminals;
A second circuit including one connection terminal and the other connection terminal to which both ends of the thermocouple are respectively connected, and a capacitor connected between the connection terminals; and a capacitor of the first circuit and the second circuit. An amplification unit for amplifying the voltage between both ends of the
A thermocouple signal processing device comprising: a thermocouple signal processing device provided in correspondence with the first thermocouple and the second thermocouple, and having one of the connection terminals closer to an electromotive force voltage of the thermocouple in a use temperature band. And a voltage supply unit for selectively supplying a high disconnection detection voltage or a ground voltage, and a voltage supply unit for the first thermocouple and the second thermocouple, which is supplied to the one connection terminal side. The first supply signal corresponding to the electromotive force voltage of the first thermocouple and the amplifying unit corresponding to the electromotive force voltage of the second thermocouple, where the supplied voltage is a ground voltage. Means for comparing the second output signal with the second output signal to select a higher output signal as the detected temperature value; and a first output signal based on the first output signal and the second output signal.
It is determined whether any one of the thermocouple and the second thermocouple is disconnected, and when it is determined that one of the thermocouples is disconnected, the voltage supply unit for the non-disconnected thermocouple is determined. And means for controlling a supply voltage supplied to the one connection terminal side from the voltage to be used for the disconnection detection voltage, the signal processing device for a thermocouple. 5. When it is determined that one of the thermocouples is disconnected, the supply voltage supplied to the one connection terminal side from the voltage supply unit for the disconnected thermocouple is set to the ground voltage. 5. The thermocouple signal processing device according to claim 4, wherein the signal is controlled to remain as it is. 6. A determination as to whether any one of the first thermocouple and the second thermocouple is broken is made based on a difference or a ratio between the first output signal and the second output signal. The thermocouple signal processing device according to any one of claims 1 to 5, wherein: 7. A voltage supply unit comprising: a voltage source for the disconnection detection voltage; a ground; and a switch for switching and connecting the one connection terminal side between the voltage source and the ground. The signal processing device for a thermocouple according to any one of claims 4 to 6, wherein: 8. The thermocouple signal processing device according to claim 4, wherein the voltage supply unit is a digital / analog converter. 9. After one thermocouple is disconnected, an output signal of the amplifying unit corresponding to an electromotive voltage of the other thermocouple is monitored, and when the output signal exceeds a preset value, the output signal is monitored. 9. The signal processing device for a thermocouple according to claim 4, further comprising means for determining that the thermocouple has been disconnected. 10. Before the supply voltage supplied to one of the connection terminals of the first thermocouple and the second thermocouple is set to the ground voltage, the supply voltage is used as the disconnection detection voltage. After confirming that neither the first thermocouple nor the second thermocouple is disconnected based on the first output signal and the second output signal, the supply voltage is controlled to be the ground voltage. 5. The thermocouple signal processing device according to claim 4, further comprising means. 11. A method of processing a signal corresponding to an electromotive force voltage of a thermocouple duplicated by a first thermocouple and a second thermocouple, comprising the steps of: inputting an electromotive force voltage of the first thermocouple to an input terminal; Amplifying by an amplifying unit having a capacitor connected therebetween; amplifying an electromotive voltage of the second thermocouple by an amplifying unit having a capacitor connected between input terminals; and the first thermocouple. A first output signal from the amplifying unit corresponding to the electromotive voltage of the second thermocouple and a second output signal from the amplifying unit corresponding to the electromotive voltage of the second thermocouple, and the higher output Selecting a signal as the temperature detection value;
A signal processing method for a thermocouple, comprising: 12. A method for processing a signal corresponding to an electromotive voltage of a thermocouple duplexed by a first thermocouple and a second thermocouple, wherein both ends of the first thermocouple are connected respectively. A first circuit including one connection terminal and the other connection terminal, and a capacitor connected between these connection terminals;
A second circuit including one connection terminal and the other connection terminal to which both ends of the thermocouple are respectively connected, and a capacitor connected between the connection terminals; and a capacitor of the first circuit and the second circuit. An amplification unit for amplifying the voltage between both ends of the
In a signal processing method using a thermocouple signal processing device comprising: a supply voltage supplied to one of the connection terminals of the first thermocouple and the second thermocouple is set as a ground voltage,
A first output signal from the amplifying unit corresponding to the electromotive force voltage of the first thermocouple is compared with a second output signal from the amplifying unit corresponding to the electromotive force voltage of the second thermocouple. Selecting the higher output signal as the detected temperature value, and selecting the first output signal based on the first output signal and the second output signal.
Determining whether one of the thermocouple and the second thermocouple is disconnected; and determining that one of the thermocouples is disconnected; Controlling the supply voltage supplied to the connection terminal side of the thermocouple to a voltage for detecting disconnection higher than the electromotive voltage of the thermocouple in the operating temperature band. Processing method. 13. A determination as to whether any one of the first thermocouple and the second thermocouple is disconnected is performed based on a difference or a ratio between the first output signal and the second output signal. The signal processing method for a thermocouple according to claim 12, wherein the signal is processed. 14. Before the supply voltage supplied to one of the connection terminals of the first thermocouple and the second thermocouple is set to the ground voltage, the supply voltage is used as the disconnection detection voltage. 13. The thermoelectric device according to claim 12, wherein a step of confirming that neither the first thermocouple nor the second thermocouple is disconnected based on the first output signal and the second output signal is performed. Pair signal processing method. 15. An object to be processed is placed in a processing container, the object to be processed is heated by a heating means to perform a predetermined process, and a temperature is detected by a thermocouple, and heating is performed based on the detection result. A heat treatment apparatus for controlling electric power supplied to the means, comprising the thermocouple signal processing apparatus according to any one of claims 1 to 10.