JPH04363633A - Spectrometry apparatus - Google Patents

Abstract

PURPOSE:To obtain an apparatus which allows fast time wise measurement of changes of a plurality of spectrum peals at a high accuracy and compact by building up a light intensity detecting section with a fiber array and a plurality of photomultipliers. CONSTITUTION:Light of spectrum peaks with three measuring wavelengths separated in three directions with a fiber array 10 is converted into electrical signals with the optimum sensitivity with photomultipliers 11a-11c by applying the optimum high voltage and amplified with amplifiers 12a-12c and A/D converters 13a-13c to be converted into digital signals. The digital signals are analyzed with a data processor (CPU) 14. With such an arrangement, even when light intensities of three spectrum peaks differ greatly, the high voltage to be applied to the respective photomultipliers are set to the optimum values to adjust the sensitivity thereby enabling measurement of hourly changes of the spectrum peaks at a high sensitivity and at a high speed. The use of a fiber array having a bundling of fine fibers also achieves a compact designing.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] This invention utilizes a diffraction grating spectrometer, such as a particle measuring device that can identify components used in dust management in semiconductor processes, and an end point detection monitor used in dry etching in semiconductor processes. This paper relates to improving the performance of spectroscopic measurement equipment.

0002

2. Description of the Related Art FIG. 5 is a block diagram showing a first conventional particle measuring device that can identify components, as disclosed in, for example, Japanese Patent Application Laid-Open No. 2-190744. It consists of a photomultiplier tube and a photomultiplier tube. 1 is a space to be measured, 2 is a capillary tube for carrying the gas SG collected from the space 1 containing fine particles,
3 is a microwave power supply, 4 is a microwave cavity, 5
is a reaction tube for discharging the gas containing fine particles carried by the capillary tube 2, and includes an inlet 5a for carrier gas CG such as He or Ar, and an exhaust port for discharging the collected gas and carrier gas after discharge. 5c is attached. 5b is a detection window, 6 is an evacuation means, 7 is a spectrometer for separating light emitted by discharging a gas containing fine particles, and 8 is a photomultiplier tube for converting the light separated by the spectrometer 7 into an electric signal. , 9 is a signal processing section that amplifies the electrical signal obtained by the photomultiplier tube 8, performs A/D conversion, and analyzes the data. 9a is a preamplifier, 9b is an A/D converter, 9
c is an arithmetic processing circuit.

Next, the operation of the conventional example will be explained. The gas containing fine particles collected from the measurement space 1 through the capillary tube 2 is mixed with a carrier gas of He or Ar, and is discharged in the reaction tube 5 by microwaves supplied from the microwave power source 3, generating plasma. It is formed. At this time, the particles introduced together with the sampling gas are plasma dissociated and gasified. Therefore, in this reaction tube, plasma emission occurs due to the sampling gas, the carrier gas, and the gasified particles. After this plasma emission is separated into spectra by a spectrometer 7, it is converted into an electric signal by a photomultiplier tube 8, and from the emission spectrum obtained by a signal processing unit 9, spectrum peaks caused by the sampled gas and carrier gas are excluded, and the gas By selecting only the spectral peaks caused by the microparticles, the components (elements) of the microparticles can be identified. Note that the emission spectrum caused by the fine particles becomes pulse-like when viewed on the time axis because the fine particles go through a process in which they are gasified, diffused into the carrier gas and sampling gas, and further exhausted.

[0004] Conventional particulate measuring devices and their component spectroscopic measuring devices are configured as described above, so that they measure temporal changes in spectral peaks based on one component (element) and count the number of pulses. By doing this, the number of fine particles can be measured, but if the fine particles do not contain a component (element) having a spectral peak that matches the measurement wavelength, the fine particles cannot be detected. In order to minimize the number of missed particles, it is necessary to simultaneously measure temporal changes in multiple spectral peaks in parallel. One way to do this is to mechanically scan the diffraction grating of a spectrometer, but it is difficult to measure rapid time changes for multiple spectral peaks. Another method is to install a photo array sensor in the output slit of a spectrometer to measure a wide wavelength range simultaneously, but the plasma emission spectrum includes many spectral peaks other than those of the particles, that is, the spectral peaks of the sampling gas and carrier gas. With photo array sensors, it is not possible to adjust the sensitivity for each spectral peak, so the measurement sensitivity of elements caused by particulates is determined by the intensity of the spectral peak of the sampled gas or carrier gas, making high-sensitivity measurement difficult. be. Also,
Since the time response speed of a photoarray sensor is slower than that of a photomultiplier tube, it is not possible to increase the counting rate of particles.

Further, FIG. 6 shows, for example, a second conventional example of spectroscopic measurement for measuring the luminescence phenomenon described in the Handbook of Applied Spectroscopy (edited by Hiroshi Yoshinaga, Asakura Shoten, 3rd edition, March 1, 1984, p. 633). It is a block diagram of a device. A plurality of photomultiplier tubes 8a are provided in the output slit portions 31a, 31b, 31c of the spectrometer 7.
, 8b, and 8c are arranged side by side. 33 is a light emitting means, and 34 is an arithmetic processing means. Therefore, the sensitivity can be adjusted for each spectral peak, and the time response is fast, but
It is necessary to arrange a large number of photomultiplier tubes 8a, 8b, 8c at a predetermined angle from the diffraction grating 32, and therefore it is difficult to reduce the size of the spectrometer 7. That is, it is difficult to obtain a compact spectroscopic measurement device.

As a third conventional example, a spectroscopic measurement device is used as a component of a monitor for detecting the end point of dry etching in a semiconductor process (for example, PLASMA SPECTRUM commercially available from SOFIE).
ANALYSERSD20), a type of spectrometer that mechanically scans a diffraction grating is used here, and there is no problem when using this device with a method that detects the end point of etching using only a single spectral peak. With highly accurate methods that detect end points by processing time change data of spectral peaks, it is difficult to measure multiple spectral peaks at high speed after performing optimal sensitivity adjustment for each spectral peak. It is.

[0007]

[Problems to be Solved by the Invention] As described above, in the first conventional example, it is difficult to measure rapid time changes for multiple spectral peaks, and in the second conventional example, it is difficult to measure rapid temporal changes for multiple spectral peaks. It is possible to measure high-speed temporal changes with high sensitivity, but the equipment becomes large and the third
In the conventional example, since the sensitivity cannot be adjusted for each spectral peak, the sensitivity is determined by the maximum peak intensity of the sampling gas or carrier gas, making it difficult to perform high-sensitivity measurements.

The present invention has been made to solve the above-mentioned problems, and it is a device for measuring particles that can identify components, a monitor for detecting the end point of dry etching, etc., and is capable of detecting the time change of a necessary spectral peak in the spectrum of a luminescent phenomenon. The present invention aims to provide a compact spectrometer that can measure time changes of multiple spectral peaks at high speed by adjusting the optimal sensitivity for each peak. purpose.

[0009]

[Means for Solving the Problems] A spectroscopic measuring device according to the present invention is a diffraction grating type spectroscopic measuring device for measuring the temporal change in the intensity of a necessary peak in the spectrum of a temporally changing luminescent phenomenon. The intensity detection section is composed of a fiber array and two or more photomultiplier tubes.

0010

[Operation] In this invention, the light intensity detection section is constructed with a fiber array and two or more photomultiplier tubes corresponding to the number of spectral peaks, so the time changes of multiple spectral peaks are optimized for each peak. It is possible to perform high-speed measurements with appropriate sensitivity adjustment, and the device is compact and can be installed in small spaces. In addition, this light intensity detection section is
Using a light source with a spectrometer that can generate light with the same wavelength as the spectral peak to be measured or shifted by a predetermined wavelength, the light from this light source is introduced into the spectrometer equipped with the above fiber array, and the light from the fiber array is It can be manufactured by selecting only the shining fibers from among the multiple optical fibers on the output side and connecting the bundled fiber bundles to a photomultiplier tube as many times as there are spectral peaks to be measured. The device can be easily manufactured.

[0011]

【Example】

Embodiment 1 Hereinafter, an embodiment of the present invention will be described based on the drawings. Figure 1
1 is a configuration diagram when a spectroscopic measuring device according to an embodiment of the present invention is applied to a particle measuring device that can identify components. 10
is a fiber array and is attached to the output slit portion of the spectrometer 7. Here, a device that can measure three spectral peaks simultaneously is shown. A more detailed structure of the fiber array 10 is shown in the schematic explanatory diagram of FIG. fiber array 10
has a structure in which a large number of optical fibers are bundled as shown in the figure, and the light with three spectral peaks separated by the spectrometer 7 is attached to the mounting surface of the output slit part of the spectrometer 7 (the incident surface of the separated light). ) 7a, and the light at each spectral peak (wavelengths λ1, λ2, λ3) passes through each fiber bundle 10a, 10b, 10c and connects to a photomultiplier tube 30a. , 30b, 30c. Now, returning to FIG. 1, the light at the spectral peaks of the three measurement wavelengths separated into three directions by the fiber array 10 is transmitted from each photomultiplier tube 11a, 11b, 11.
The optimum high voltage is applied at c, and the signal is converted into an electrical signal with optimum sensitivity, and the amplifiers 12a, 12b, 12c and A
Amplification and conversion to digital signals are performed by /D converters 13a, 13b, and 13c. These digital signals are analyzed by a data processing device 14. With the above configuration, even if the light intensities of the three spectral peaks are significantly different, high sensitivity can be achieved by setting the high voltage applied to each photomultiplier tube to the optimal value and adjusting the sensitivity. In addition, it is possible to measure temporal changes in spectral peaks at high speed. Furthermore, by using a fiber array made up of extremely thin optical fibers, a compact spectroscopic measurement device can be realized.

Now, the spectrometer that can measure three spectral peaks has been shown above, but in order to increase the number of measurement peaks, it is necessary to use a fiber bundle of a fiber array, a photomultiplier tube, an amplifier, and an A/D converter. All you have to do is increase the number of additional pieces.

Furthermore, even if the spectral peaks to be measured are very close to each other, each peak can be separated with a resolution comparable to the diameter of an optical fiber. This is also effective in making the spectrometer more compact.

Embodiment 2 Next, another embodiment of the present invention will be described. FIG. 3 is a configuration diagram when a spectroscopic measuring device according to another embodiment of the present invention is applied to a dry etching end point detection monitor. When high frequency power is applied from the high frequency power source 15 to the parallel plate electrode 16 while the etching gas is supplied, the plasma 17
occurs and etches the wafer. By receiving the light emitted from this plasma by, for example, the fiber head 18 and introducing it into the spectrometer 7, in this example, time changes in three spectral peaks can be measured simultaneously. For example, when the end point of etching is reached, the peak of λ1 increases, and the peak of λ2 and λ
Assuming that the peak of 3 decreases, λ2 and λ3
If the value obtained by normalizing the peak intensity of λ1 with the peak intensity of λ1 is constantly monitored, and the etching end point is set when these two values decrease simultaneously, extremely reliable end point detection becomes possible. Note that by applying the spectrometer of the present invention, optimal sensitivity adjustment can be made for each of the spectral peaks to be monitored, so highly sensitive measurement is possible. If it is desired to increase the number of spectral peaks to be monitored, this can be easily achieved as in the case of the particle measuring device described above.

The spectroscopic measuring device of the present invention is effective not only in the embodiments described above, but also in measuring devices that measure temporal changes in the intensity of a necessary peak in the spectrum of a temporally changing luminescent phenomenon. It goes without saying that there is.

Next, a method for manufacturing the light intensity detection section, which is a main component of the spectrometer of the present invention, will be explained. The light intensity detection unit is composed of a fiber array and two or more photomultiplier tubes, but it is necessary to manufacture as many fiber bundles as the number of spectral peaks to be measured in the fiber array. A method for manufacturing this fiber array will be explained using FIG. 4. In FIG. 4, reference numeral 19 denotes a light source such as a xenon arc lamp or a tungsten lamp, which can generate light in a wide wavelength range. 20 is a spectroscope for spectroscopy of the light from the light source 19 to obtain light of the same wavelength as the spectral peak to be measured or a wavelength shifted by a predetermined value; 21 is a spectrometer for dispersing the spectroscopic light of the spectrometer of the present invention; This is a lens for introducing into the spectrometer 7 which is a component. When light with the same wavelength as the spectral peak to be measured or a wavelength shifted by a predetermined value is introduced into the spectrometer 7, only the optical fibers that emit light from their end faces among the optical fibers making up the fiber array are detected. The fibers are sorted and bundled together to form a fiber bundle. When visually determining whether or not light is emitted from the end face, the selection process is performed in a dark room for light with visible spectral peak wavelengths. In addition, for light with spectral peak wavelengths other than visible, light with a visible wavelength is used by shifting it by a predetermined value, and the setting of the diffraction grating of the spectrometer 7 is shifted by a predetermined value to select optical fibers. After doing this, set the diffraction grating of the spectrometer 7 back by the amount that was shifted earlier. Furthermore, this does not apply when optical fibers are sorted using a photodetector that is sensitive to a wide range of wavelengths instead of visually. A desired fiber array can be manufactured by performing the above operations as many times as there are spectral peaks to be measured. The optical fibers that have not been sorted may be bundled separately.

[0017] Since the fiber array is manufactured by the method described above, delicate alignment of optical parts is not required, and manufacturing can be performed with relatively simple operations. Furthermore, since it is only necessary to handle the optical fiber corresponding to the spectral peak wavelength to be measured, most of the other optical fibers are wasted in terms of material, but this is not so much in terms of the amount of work.

[0018]

As described above, according to the present invention, the light intensity detection section of the spectrometer is configured with a fiber array and a plurality of photomultiplier tubes, so that the time changes of a plurality of spectral peaks can be detected from each peak. It can perform high-speed measurements with optimal sensitivity adjustment, and the device is compact and can be installed in small spaces. Moreover, this spectrometer can be manufactured relatively easily.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram when a spectroscopic measuring device according to an embodiment of the present invention is applied to a particle measuring device that can identify components.

FIG. 2 is a schematic explanatory diagram showing the detailed structure of a fiber array according to the present invention.

FIG. 3 is a configuration diagram when a spectroscopic measurement device according to another embodiment of the present invention is applied to a dry etching end point detection monitor.

FIG. 4 is a configuration diagram for explaining a method for manufacturing a fiber array according to the present invention.

FIG. 5 is a configuration diagram showing a first conventional example of a particle measuring device capable of identifying components.

FIG. 6 is a configuration diagram of a second conventional spectroscopic measurement device for measuring a luminescence phenomenon.

[Explanation of symbols]

1 Space to be measured 7 Spectrometer 10 Fiber array 11a, 11b, 11c Photomultiplier tube 12a, 12
b, 12c Amplifier 14 Data processing device 18 Fiber head 19 Light source 20 Spectrometer

Claims (1)

[Claims] 1. A spectroscopic measurement device using a diffraction grating spectrometer, characterized in that a light intensity detection section is composed of a fiber array and a plurality of photomultiplier tubes.