JP5257126B2 - Particle detector - Google Patents

Description

  The present invention relates to a particle detection apparatus that detects particles such as dust contained in exhaust gas from a semiconductor processing apparatus or the like.

Particles such as dust generated in the semiconductor processing process and floating in the processing chamber cause the performance of the product to deteriorate. Therefore, the semiconductor processing apparatus is provided with a particle detection apparatus that detects particles floating in the processing chamber in real time.
The particle detector is disposed in, for example, an exhaust duct from a processing chamber. When light from a light source (for example, laser light) is irradiated into the exhaust duct, scattered light is emitted when particles pass through the exhaust duct. To emit. Among those obtained by converting the scattered light into an electric signal, those reaching a certain voltage or higher are detected as particles.

  In the conventional particle detector, since a part of the area inside the exhaust duct is irradiated with laser light, only particles passing through the area can be detected. On the other hand, Patent Document 1 describes a particle detection device that determines the distribution, size, number, and the like of particles in a processing chamber by scanning and irradiating laser light inside the processing chamber. .

JP 2003-7681 A

When laser light is scanned and irradiated as in Patent Document 1, particles can be detected in a wide area in the processing chamber, but particles that appear simultaneously in different areas cannot be detected.
The problem to be solved by the present invention is to provide a particle detector capable of acquiring accurate information on the distribution of particles floating in the processing chamber of a semiconductor processing apparatus.

In order to solve the above-mentioned problems, a particle detection device according to the present invention is a particle detection device installed in an exhaust pipe of the processing chamber in order to detect particles floating in the processing chamber of a semiconductor processing device. ,
a) a light irradiation means for irradiating the entire measurement target region in the exhaust pipe with light simultaneously;
b) a plurality of detection elements arranged in a line, and a scattered light detector for detecting scattered light generated when light is irradiated onto the measurement target region;
c) a signal processing unit that outputs information on a distribution state of particles passing through the exhaust pipe by processing a detection signal of the scattered light detector for each detection element;
d) It is characterized by comprising display means for displaying information relating to the distribution status of the particles output by the signal processing unit.

  In addition, the particle detection apparatus of the present invention further includes a storage unit that stores information on the distribution status of particles output from the signal processing unit, and information that processes information on the distribution status of the particles stored in the storage unit. A processing unit is provided.

  In the particle detection device of the present invention, the entire measurement target region in the exhaust pipe is irradiated with light at the same time, and the scattered light generated thereby is detected by a scattered light detector composed of a plurality of detection elements. The processing unit processes the detection signal of the scattered light detector for each detection element and outputs information on the particle distribution state to the display unit. Based on the information, the display unit displays information on the particle distribution state. For this reason, it is possible to accurately grasp the particle distribution in the measurement target region in the exhaust pipe.

BRIEF DESCRIPTION OF THE DRAWINGS Schematic which shows the whole structure of the particle | grain detection apparatus concerning one Example of this invention. The figure which shows the measurement object area | region in an exhaust pipe. The figure which shows an example of the monitor screen during data recording. The figure which shows an example of the bit pattern displayed on the generation | occurrence | production condition display part. The figure which shows an example of the histogram switched and displayed on the occurrence condition display part. The figure which shows the example of a display of the content of the measurement file of a particle.

An embodiment of a particle detection apparatus according to the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram showing the overall configuration of the particle detection apparatus 1. The particle detection device 1 includes a semiconductor laser diode 10, a scattered light detector 12, a data recording device 14, and the like.
The semiconductor laser diode 10 irradiates the exhaust pipe 18 with laser light through a light guide 20 provided in the exhaust pipe 18 of the processing chamber of the semiconductor processing apparatus. The scattered light detector 12 is formed of, for example, a 32-channel photomultiplier tube (PMT), and detects scattered light generated when particles passing through the exhaust pipe 18 are irradiated with laser light.

  The light guide 20 extends in a direction orthogonal to the direction (indicated by an arrow A in FIG. 1) through which the particles P pass through the exhaust pipe 18. Accordingly, the laser light from the semiconductor laser diode 10 crosses the exhaust pipe 18 in a direction orthogonal to the particle passing direction A. Thereby, all the particles can be detected even when a plurality of particles pass through different parts of the measurement target region at the same time.

  The scattered light detector 12 processes the analog voltage corresponding to the scattered light, which changes as the particles P pass through the exhaust pipe 18 irradiated with the laser light, for each channel by the control board 24, and sends it to the data recording device 14. Output. The signal control unit 36 and the analysis control unit 34 in the control board 24 convert the analog voltage for each channel into a digital signal having the analog voltage as a threshold value and output the digital signal to the counter circuit unit 26. The counter circuit unit 26 monitors the ON / OFF state of the input digital signal. In the storage unit 28, various parameters obtained by processing preset parameters and analog voltage of the scattered light detector 12 are stored in a file. The display unit 30 displays information on the particle distribution status detected by the scattered light detector 12 in real time, and also displays information on the particle distribution status corresponding to the file read from the storage unit 28.

  The data recording device 14 is a personal computer, for example, and a monitoring / control application 22 is running on the computer. The control board 24 is a hardware component for analyzing and processing the signal of the scattered light detector 12, and information processed by the control board 24 is totaled by the data recording device 14, and processing such as storage and display is performed. I do. For example, when using Microsoft Windows (registered trademark) as the OS of the data recording device 14, the data recording board control unit 32, the storage unit 28, and the display unit 30 serve as means for processing data received from the control board 24. Data types and methods can be implemented in the form of a packaged dynamic link library (DLL).

The monitoring / control application 22 has the following functions, for example.
(1) The number of particles detected by the scattered light detector 12 is counted.
(2) Monitor the occurrence of particles along the time axis.
(3) Save the measurement result to a file, or read and display the saved file.
(4) A file (automatic measurement command file) in which parameters necessary for measurement are stored is taken, and automatic measurement is performed according to the file contents.
(5) Convert the measurement result into an editable file format.
That is, in this embodiment, the control board 24 and the monitoring / control application 22 function as an information processing unit .

なお、ａはパーティクル半径、λは入射光の波長、ｎはパーティクルの屈折率、θは入射光の進行方向と散乱光の観測方向のなす角度、rはパーティクルから検出器までの距離を示す。
式（１）より、散乱光強度はパーティクル半径ａの６乗に比例し、光の波長λの４乗に反比例することがわかる。従って、散乱光強度からパーティクルの数や半径を求めることができる。また、入射光の波長が大きくなると散乱光強度が減少することから、短波長の光を照射することが有効である。 Here, the detection signal (analog voltage) of the scattered light detector 12 will be described. Scattered light intensity I _scatt generated when incident light I ₀ is applied to the particles is expressed by the following equation.

Here, a is the particle radius, λ is the wavelength of the incident light, n is the refractive index of the particle, θ is the angle between the traveling direction of the incident light and the observation direction of the scattered light, and r is the distance from the particle to the detector.
From equation (1), it can be seen that the scattered light intensity is proportional to the sixth power of the particle radius a and inversely proportional to the fourth power of the wavelength λ of the light. Accordingly, the number and radius of particles can be obtained from the scattered light intensity. Further, since the intensity of scattered light decreases as the wavelength of incident light increases, it is effective to irradiate light having a short wavelength.

Next, the operation of the particle detection device 1 of the present embodiment will be described.
When the monitoring / control application software is activated, an initial screen (not shown) is displayed on the display screen of the display unit 30. First, the user sets parameters (sampling frequency, threshold voltage, measurement time, etc.) necessary for measurement on this initial screen.

  Data recording starts when the user presses the measurement start button after setting each parameter. FIG. 3 shows a monitor screen during data recording. A parameter necessary for measurement is displayed on the right half of the monitor screen, and a generation status display unit 100 for displaying the generation status of particles on the left half is displayed.

The occurrence status display unit 100 can switch and display a bit pattern indicating a detection position of a particle and a histogram. The display state of the occurrence status display unit 100 is switched by pressing a “display switching” button.
FIG. 4 shows an enlarged view of the bit pattern displayed on the occurrence status display unit 100. The bit pattern is a 32-bit digital I / O output value obtained by digitizing an analog voltage detected by a 32-channel photomultiplier tube with reference to a preset threshold value, and a logical sum (OR) thereof is a black circle (●). And white circles (◯). A black circle indicates a location (channel) where a particle is detected, and a white circle indicates a location where no particle is detected.
The display interval of the bit pattern displayed on the occurrence status display unit 100 is set to 100 times the sampling interval, for example. That is, for a sampling interval of 100 μs (sampling frequency: 10 kHz), the display interval is set to 10 ms. The display interval can be changed. Thus, in the present embodiment, recording data is stored in the main memory, but are stored in a file in a batch after completion of the measurement, the bit pattern (histogram) displayed on the generated status display portion 100 of the main memory data Is referred to according to the progress of measurement.

  FIG. 5 is an enlarged view of a histogram displayed on the occurrence status display unit 100 when the “display switching” button is pressed. The vertical axis in FIG. 5 indicates the number of detected particles, and the horizontal axis indicates the bit number of 32-bit digital I / O. This histogram is displayed in a different color for each preset unit time (hatched with different line types in FIG. 5). This histogram shows which photomultiplier tube has detected many particles and at what timing many particles have been detected.

  Data recording ends when the specified measurement time has elapsed or when the measurement end button is pressed in the middle. At this time, if it is set to save data, the data recording result is saved in a file after the measurement is completed.

In the particle detection device 1, when data recording is completed, the bit pattern and histogram shown in FIGS. 4 and 5, and data relating to particle generation conditions such as particle diameter are stored in the storage unit 28 as a particle measurement file. In each file, header information is recorded, and data obtained by detection is sequentially stored under the header information. The parameter data set before data recording is also stored in the storage unit 28. The file stored in the storage unit 28 can be appropriately read out and displayed on the display unit 30.
FIG. 6 shows a display example of the contents of the particle measurement file. Here, the contents of the measurement file are displayed as a set value list. When “extraction time” is set on this file display screen and the extraction button is pressed, detailed information of the measurement file is extracted as a file in a general-purpose software format such as Microsoft Excel (registered trademark).

The present invention is not limited to the above-described embodiments, and for example, the following modifications are possible.
The traveling direction of the laser beam only needs to intersect the particle passing direction.
The scattered light detector is not limited to 32 channels. Further, the photomultiplier tubes of the scattered light detector may be arranged side by side in a direction that crosses the light obliquely, in addition to being along the light. In short, it is only necessary that the photomultiplier tube is arranged so that it is possible to detect the passage of particles over a wide range of the measurement target region.

DESCRIPTION OF SYMBOLS 1 ... Particle detector 10 ... Semiconductor laser diode 12 ... Scattered light detector 14 ... Data recording device 18 ... Exhaust pipe 24 ... Control board 28 ... Storage part 30 ... Display part

Claims (2)

In the particle detector installed in the exhaust pipe of the processing chamber to detect particles floating in the processing chamber of the semiconductor processing apparatus,
a) a light irradiation means for irradiating the entire measurement target region in the exhaust pipe with light simultaneously;
b) a plurality of detection elements arranged in a line, and a scattered light detector for detecting scattered light generated when light is irradiated onto the measurement target region;
c) a signal processing unit that outputs information on a distribution state of particles passing through the exhaust pipe by processing a detection signal of the scattered light detector for each detection element;
d) display means for displaying information related to the distribution state of the particles output by the signal processing unit.   2. A storage unit that stores information on a distribution state of particles output from the signal processing unit, and an information processing unit that processes information on the distribution state of the particles stored in the storage unit. The particle detection apparatus described.

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