JP2000321207A - Method for calibrating reactive sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily maintain a detection level with improved reproducibility by adjusting the sensing level of emission intensity with a calibration gas and eliminating the scattering of sensing accuracy. SOLUTION: While the pressure of a reaction chamber 4 is reduced by exhaust 13 and plasma is generated, a valve 16 is opened and a calibration gas 12 is supplied from a gas introducing pipe 10 to the plasma. Then, emission intensity by the calibration gas 12 is measured by a sensing part 1, and the measurement value of the emission strength is compared with the measurement value of the sensing level by a control part 3. In this case, when the emission sensing intensity is weaker than a specific value, an application voltage to a photomultiplier is increased by a high-voltage power supply 17. Otherwise, the application voltage is decreased. The measurement is repeated and calibration is completed when the comparison result reaches a specific value or a specific range, thus easily calibrating the sensing level difference of emission intensity due to the operation time of a device and the difference in each device with improved reproducibility.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for calibrating a reaction detector in an apparatus for performing processing using plasma.

[0002]

2. Description of the Related Art A reaction detector of an apparatus for performing processing using plasma takes out light emitted by the plasma in a reaction chamber through a window provided in the reaction chamber, introduces the light emission into a detection section, and detects the light introduced into the detection section. The state of the reaction is detected by measuring the intensity. Further, the detection section is composed of a band-pass filter for transmitting light of a specific wavelength and a photomultiplier, and the detection level is calibrated by changing a voltage applied to the photomultiplier.

[0003] Since the inside of the reaction chamber is contaminated with reaction products, the intensity of light that can be extracted from the emission window for the light emission gradually decreases as the apparatus operates. The reduction in the transmitted light intensity to some extent due to the contamination can be dealt with by calibrating by adjusting the voltage applied to the photomultiplier tube. Also,
If the decrease in the transmitted light intensity exceeds a certain limit, the inside of the reaction chamber is cleaned.

[0004] In an apparatus having a plurality of reaction chambers, it is necessary to calibrate the difference between the apparatuses for each reaction chamber and each reaction detector by adjusting the voltage applied to the photomultiplier tube. Conventionally, the calibration of the reaction detector is performed by actually performing a reaction process using a sample for adjustment,
The adjustment amount of the voltage applied to the photomultiplier was determined from the data of the detected light emission intensity.

[0005]

In an apparatus having a plurality of reaction chambers as described above, conventionally, it has been necessary to prepare a plurality of adjustment samples for each reaction chamber. In addition, the variation of the adjustment sample is inevitable, which leads to the variation of the calibration of the detection level, and the accuracy control is also difficult.

Further, since the calibration of the detection level is set based on the measurement data, the setting result cannot be confirmed in real time. Therefore, variation of the adjustment sample,
It was difficult to make fine adjustments such as variations due to differences between the reaction chambers and reaction detectors, and thus it was difficult to maintain the detection level and eliminate the differences.

SUMMARY OF THE INVENTION An object of the present invention is to provide a reaction detector in which a detector detects gas and plasma generated by a reaction process in a plasma processing apparatus and detects a reaction state based on the intensity of the detected light emission. It is an object of the present invention to provide a method for calibrating a reaction detector that can easily maintain a detection level with good reproducibility.

[0008]

In order to achieve the above object, in the present invention, a gas inlet for calibrating a detection level is provided in a reaction chamber, and a voltage applied to a photomultiplier tube of a detection unit is adjusted by a control unit. Thus, a means is provided for adjusting the voltage applied to the photomultiplier while measuring the emission intensity of the calibration gas and the plasma.

[0009]

FIG. 1 shows an embodiment of the present invention, and FIG.
2 shows a flow of the calibration method of the present invention.

The detecting section 1 shown in FIG. 1 comprises a photomultiplier tube (not shown) and a band-pass filter (not shown) for limiting a wavelength to be detected. An optical fiber 18 is provided near the reaction chamber window 14 so that light emission in the reaction chamber 4 can be detected.
Is installed at one end, and the other end is installed at the detection unit 1 to emit light to the detection unit 1. The determination unit 2 converts the detection result from the detection unit 1 into an analog or digital output and outputs emission intensity data to the control unit 3.

The control unit 3 controls the processing for the reaction processing device based on the data of the luminescence intensity taken in, and adjusts the voltage applied to the photomultiplier tube by the high voltage power supply 17 for the reaction detector. Calibrate the detection level.

In the above-mentioned reaction process, the object 8 to be processed is placed on the mounting table 9 in the reaction chamber 4, and the pressure in the reaction chamber is kept reduced by the exhaust 13. Further, a high frequency generated by the high frequency power supply 5 is matched by a matching box 6 and applied to a coil 7 to generate plasma (not shown) in the reaction chamber.

In the reaction process, the valve 15 is opened and the gas passage inlet pipe 1 is opened.
The reaction is performed by an active gas generated by supplying the reaction gas 11 from 0 and passing the reaction gas 11 through the generated plasma. The gas generated by the reaction between the active gas and the object to be processed 8 emits light by plasma, the light emission intensity is measured by the detection unit 1, and the reaction processing is controlled by the control unit 3.

In the calibration of the reaction detector, the reaction chamber 4 is depressurized by the exhaust 13, the valve 16 is opened in a state where the plasma is generated, and the calibration gas 12 is supplied to the plasma from the gas passage inlet 10. The light emission intensity due to the calibration gas is measured by the detection unit 1, the measured value of the light emission intensity is compared with a predetermined value of the detection level by the control unit 3, and when they do not match, the voltage applied to the detection unit is adjusted by the high voltage power supply 17. The calibration is performed so as to reach the default value of the detection level.

FIG. 2 shows an example of the calibration method. That is, light emission due to the introduction of the calibration gas (19) is detected (20), and the light emission intensity is compared with a predetermined value (2).
1). If the emission detection intensity is lower than a predetermined value, (2
2) The applied voltage is increased according to the degree (23), and if the emission detection intensity is higher than a predetermined value (24), the applied voltage is reduced according to the degree (25). The measurement is repeated, and when the comparison result reaches a predetermined value (or within a predetermined range), the calibration is completed.

As the calibration gas, it is desirable to use a gas containing the same element as the gas generated by the actual processing reaction of the object to be processed, and to perform calibration at the emission wavelength of the element.

[0017]

According to the present invention, by using the calibration gas, it is possible to easily and reproducibly calibrate the difference in the detection level of the light emission intensity due to the operation time of the apparatus and the machine difference of each apparatus. As a result, the detection levels of a plurality of reaction detectors can be adjusted without any machine difference, the reproducibility of the process for each apparatus and each processing chamber can be stabilized, and the production yield in the manufacture of semiconductor devices can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a reaction detection system according to an embodiment of the present invention.

FIG. 2 is a flowchart showing a calibration procedure according to an embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Detection part, 2 ... Judgment part, 3 ... Control part, 4 ... Reaction chamber, 5
... RF power supply (high frequency power supply), 6 ... matching box,
7 Plasma generating coil, 8 Workpiece, 9 Workpiece mounting table, 10 Gas introduction pipe, 11 Reaction gas, 12 Calibration gas, 13 Evacuation, 14 Reaction chamber window, 15 Reaction gas Introduction valve, 16: Calibration gas introduction valve, 17: High voltage power supply, 18: Optical fiber.

 ──────────────────────────────────────────────────続 き Continued on front page F-term (reference) 2G043 AA01 CA01 CA02 DA05 EA08 GA06 GA09 GB11 GB21 HA05 JA03 LA02 NA01 NA05 NA06 NA11 2G059 AA01 BB01 DD12 EE06 JJ03 JJ17 KK02 MM01 MM05 MM09 MM10 MM12 4G075AA51

Claims (2)

[Claims] 1. A reaction chamber for performing a reaction process, a plasma is generated in the reaction chamber, a reaction process is performed on an object to be processed by the plasma and a supply gas, and light generated by the gas generated by the reaction process and the plasma is emitted. A method for calibrating a reaction detector, comprising: adjusting a detection level of light emission intensity using a calibration gas in a reaction detector that detects a reaction state based on the light emission intensity detected by a detection unit. 2. The method according to claim 1, wherein a calibration gas used for calibrating the reaction detector is a gas containing the same element as the gas generated by the reaction process, and the calibration is performed at the emission wavelength of the element. 2. The method for calibrating a reaction detector according to 1.