JPH04165640A - Temperature measurement - Google Patents

Abstract

PURPOSE:To accurately and easily measure temperatures at a plurality of points by inputting a plurality of detecting signals and at least two reference signals to signal switching means and making the temperature measurements on the basis of the plurality of detecting signals by correcting a temperature measurement circuit on the basis of the reference signals. CONSTITUTION:Reference signals C01 and C02 are successively sent to a temperature measurement circuit 20 while the signals are switched to each other by means of multiplexers 13 similarly to detecting signals C1-C18. When the voltage values obtained by measuring the signals C01 and C02 are deviated from set voltage values A and B and become A' and B' due to the variation of the turning-on or turning-off resistance of the multiplexers 13, temperature drift in the amplification degree of a detecting signal amplifier 23, etc., outputting voltage values by means of the setting signals C1-C18 are outputted after the output voltage values are corrected on the basis of the difference between the set and measured voltage values A and A' and the difference between the set and measured voltage values B and B'. Therefore, when temperature measurements are successively performed at a plurality of points by using the signal switching means, the temperature at each point can accurately and easily be measured.

Description

[Detailed description of the invention] [Purpose of the invention] (Industrial application field) The present invention relates to a temperature measuring method.

(Prior Art) Generally, in the film forming process and thermal diffusion process in the manufacturing process of semiconductor devices, a heat treatment apparatus is used, for example, which is configured by arranging a heater around a reaction tube that houses a semiconductor wafer, which is an object to be processed. ing.

In such heat treatment equipment, signals from multiple temperature detectors placed outside and inside the reaction tube are sequentially sent to a measurement circuit, the temperature at the location of each temperature detector is measured, and the temperature is calculated based on this measured temperature. The electric power applied to the heater is controlled, thereby controlling the temperature inside the reaction tube to a predetermined temperature.

By the way, when arranging multiple temperature detectors, such as thermocouples, as described above, it is possible to measure the temperature of each by sequentially switching multiple detection signals and sending them to the measurement circuit using, for example, a multiplexer. It is being said.

(Problem to be Solved by the Invention) However, when performing temperature measurements at multiple locations, switching the detection signal using a multiplexer as described above may cause problems such as temperature changes in the on-resistance and off-resistance of the multiplexer, There was a problem that measurement errors were easily caused by thermal electromotive force generated from dissimilar metal parts and drift of the amplifier when amplifying the detection signal. For example, in temperature measurement using a thermocouple, the detection signal is approximately 10-odd μV/
Since it is extremely small at around ℃, even a small thermoelectromotive force can cause an extremely large measurement error.

The present invention has been made to address the problems of the prior art, and an object of the present invention is to provide a temperature measurement method that allows temperature measurements at multiple locations to be performed accurately and easily.

[Structure of the Invention] (Means for Solving the Problems) The temperature measuring method of the present invention sequentially sends detection signals from a plurality of temperature detectors to a temperature measurement circuit by a signal switching means, and performs individual detection. When measuring the temperature at each location where the plurality of temperature detectors are installed based on the signals, inputting the plurality of detection signals and at least two reference signals to the signal switching means, and measuring the temperature based on these reference signals. The present invention is characterized in that temperature measurements are performed based on the plurality of detection signals while correcting the temperature measurement circuit.

(Function) In the temperature measurement method of the present invention, at least two reference signals are input to the signal switching means together with detection signals from a plurality of temperature detectors, and the reference signals are measured in the same manner as the detection signals. , errors introduced by the signal path, such as multiplexers and amplifiers, can be measured.

By correcting the outputs of individual detections (j4) based on the outputs from at least two reference signals, it is possible to perform accurate temperature measurements. Temperature measurements can be carried out by inputting the reference signal together with the detection signal to the signal switching means.

(Example) Hereinafter, an example in which the method of the present invention is applied to temperature measurement of a heat treatment apparatus will be described with reference to the drawings.

FIG. 1 is a diagram showing a schematic configuration of a heat treatment apparatus to which the temperature measurement method of the present invention is applied.
A heating heater 3 is arranged, and a large number of semiconductor wafers 5 housed in, for example, a wafer holder 4 are accommodated in the reaction tube 2 and subjected to desired heat treatment.

In the heat treatment apparatus, for example, 5
A 5-zone temperature control system that controls the power applied to the heater 3 for each of the divided regions A, B, C, D, and E, and controls the temperature inside the reaction tube 2 for each of these regions A and -E. A control method is adopted.

In order to implement the above five-zone temperature control method,
In the vicinity of the heater 3 outside the reaction tube 2, each area AS
Two temperature detectors such as thermocouples 6.7 are installed in each of B, C, D, and E. Furthermore, inside the reaction tube 2, temperature detectors such as thermocouples 8 are installed in each of the regions A, B, CSD, and E, respectively.

Each thermocouple 6.7.8 is connected via a compensation conductor 9 to a connector 10. At this time, among the thermocouples installed outside the reaction tube 2, the first thermocouple 6 is connected to the first connector 10a, and the second thermocouple 7 is connected to the second connector], Ob and and each thermocouple 8 installed inside the reaction tube 2 is a third connector],
Connected to OC. Each connector 10a, 10b, 1
Compensation temperature sensors 11 are installed at 0c to measure the temperature of these connectors themselves.

As shown in FIG. 2, the detection signals from each thermocouple 6, 7, 8 are sent together with the output signal from the compensating temperature sensor 11 to a signal switching means, such as an analog multiplexer made of semiconductor 2.

Note that the detection signal from the first connector 10a is sent to the first multiplexer 12a, the detection signal from the second connector 10b is sent to the second multiplexer 12b, and the detection signal is sent to the third connector 10.
The detection signal from e is sent to the third multiplexer 12c.

At least two reference signals C81 and CO2 are input to each of the multiplexers 12a, 12b, and 12c, respectively, along with detection signals from the thermocouples 6, 7, and 8, respectively.

As these reference signals C83 and CO2, for example, a voltage corresponding to the maximum temperature depending on the object to be measured, a zero voltage, etc. are used. In this example, the measurement temperature range is 0°C to 1399°C.
．． 9℃, and Cot has a temperature of about 141℃, which is higher than the maximum temperature measured.
A reference power supply 13 of +16.2a+V corresponding to 2°C was connected, and CO2 was connected to ground potential. Note that the number of reference signals is not limited to two, and whether more accurate measurement can be expected by increasing the number of reference signals, α1
Two reference signals are usually sufficient since this results in a reduction in the number of signal inputs to be determined.

Each multiplexer 12a, 12b, 12C is
The detection signals C2 to C18 from the thermocouples 6.7.8, reference signals C81, CO2, etc., which are connected to the temperature measurement circuit 20 and input to the multiplexer 12, are switched by the multiplexers 12a, 12b, and 12C. and are sequentially sent to the temperature measurement circuit 20 side.

The temperature measurement circuit 20 includes three multiplexers 12a.
, 12b, 12c, an amplifier 23 for amplifying the detection signal, an A/D converter 24, and an arithmetic equation for converting the detection signal, reference signal, etc. into temperature. Reference signal C81, C
ROM25 in which calculation formulas, etc. for correcting the output temperature value from the detection signal according to the output temperature value from O2 are stored in advance.
and RAM2 which temporarily stores the output values during these calculation processes.
6, and convert the detection signal, reference signal, etc. into temperature based on the calculation formula stored in the ROM 25, correct the output temperature value from the detection signal, output it as the measured temperature, and perform this correction. A CPU 27 that outputs a command signal for a power value to be applied to the heating heater 3 based on the later measured temperature.
and 5CR28, etc., which control the power applied to the heating heater 3 in accordance with this command signal.

Here, temperature correction of the detection signals C1 to crs from the thermocouples 6.7.8 using the reference signal C63 and CO2 will be explained.

First, when the reference signals C81 and CO2 are switched by the multiplexer 12 and sent sequentially to the temperature measurement circuit 20 in the same way as the detection signals 01 to C18, a voltage based on these reference signals C8 to C82 is output. At this time, as shown in Fig. 3, if the output voltage value from these reference signals C81 and CO2 is the predetermined value ASB, the voltage C corresponding to the temperature from the detection signals 01 to C18 directly corresponds to the measured temperature. output as a voltage. In addition, the voltage values obtained by measuring the reference signals C81 and CO2 may be affected by, for example, fluctuations in the on-resistance and off-resistance of the multiplexer 12, thermoelectromotive force generated from dissimilar metal parts of the connector 10, or the amplification level of the detector amplifier 23. If the measured voltages A' and B' deviate from the set voltage values A and B due to temperature drift, etc., the difference between the set voltage A and the measured voltage value A' and the set voltage B
Detection signals C3 to C18 are generated based on the difference between and measured voltage value B'.
The output voltage value is subjected to a predetermined correction, for example, the voltage C' before correction is corrected to the voltage C and output.

The above temperature correction can be performed, for example, by proportional calculation based on the difference between the voltages A' and B' measured using the reference signals C83 and CO2 and the set voltages A and B. Such temperature correction may be performed by sequentially inputting the reference signal C3lsCO2 together with the detection signal CI'''-C10, or the temperature measurement circuit 20 may be configured to be calibrated every second, for example.

By temperature correction as described above, each thermocouple 6.7.8
Detection signals 01 to C18 are corrected for errors caused by temperature drift in the signal path, etc., and are output as accurate temperature values.

Note that temperature control inside the reaction tube 2 by the above-mentioned external temperature detectors (6, 7) and internal temperature detector (8) is performed using, for example, the output temperature value from the internal temperature detector (8) and the external temperature detector. This is done by calculating the average value of the output temperature values from (6, 7) according to a predetermined ratio, and controlling the electric power applied to the heating heater 3 according to this average value.

In this way, in the heat treatment apparatus 1 of the above embodiment, the detection signals CI- (along with +s, two) reference signals COI and CO2 from the plurality of thermocouples 6, 7, 8 are inputted to each multiplexer 12, and the Since the temperature measurement circuit 20 is calibrated based on the output temperature value from the reference signals Cot and CO2, the A
Errors that occur before digital conversion by the /D converter 24 are corrected, and accurate temperature measurements can be made, thereby making it possible to more accurately control the temperature of the reaction tube 2.

In addition, such accurate temperature measurement is possible using the detection signal C+ −
This can be done by a simple operation of inputting the two reference signals COI and Co2 together with CIs to each multiplexer] 2, which reduces the burden on the device.

In addition, in the above embodiment, an example was explained in which the temperature measurement method of the present invention is applied to temperature control of a heat treatment apparatus, but the present invention is not limited to this. It can be applied to various types of temperature measurements, such as sequentially sending data to a temperature measurement circuit.

[Effects of the Invention] As explained above, according to the temperature measurement method of the present invention,
When temperature measurements at multiple locations are sequentially performed using the signal switching means, each temperature measurement can be performed accurately and efficiently.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing a schematic configuration of a heat treatment equipment to which a temperature measurement method according to an embodiment of the present invention is applied, Fig. 2 is a diagram showing its temperature measurement circuit, and Fig. 3 is a diagram showing a temperature correction method according to the present invention. FIG. 1...Heat treatment device, 2...Reaction tube, 3...
Heating heater, 6.7.8...Thermocouple, 10.
... Connector, ]2 ... Multiplexer, 13
...Reference power supply, 20...Temperature measurement circuit. Applicant Tokyo Electron Sagami Co., Ltd. Agent Patent Attorney Sasa Suyama - (1 other person) TA1 mouth↓ Figure 2

Claims (1)

[Claims] Detection signals from a plurality of temperature detectors are sequentially sent to a temperature measurement circuit by a signal switching means, and when measuring the temperature at each location where the plurality of temperature detectors are installed based on the individual detection signals, the signal inputting the plurality of detection signals and at least two reference signals to a switching means;
A temperature measuring method characterized in that temperature measurements are performed based on each of the plurality of detection signals while correcting the temperature measurement circuit based on these reference signals.