JPH053236A - Fine particle detector - Google Patents

Abstract

PURPOSE:To detect fine particles and recesses on the surface of a semiconductor substrate with the high accuracy. CONSTITUTION:A light source 101 which emits a light along a direction approximately in parallel with the surface of a test specimen 11. The light L1 emitted by the light source 101 is scattered by fine particles 17 existing on the test specimen 11. A detecting means 14 and 15 collects and detects the scattered lights L3-L5 to detect the fine particles 17.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for detecting particles adhering to the surface of an object, and more particularly to an apparatus for detecting particles on the surface of a semiconductor substrate.

[0002]

2. Description of the Related Art Detection of fine particles adhering to a semiconductor substrate is generally performed by irradiating a laser beam and collecting scattered light. FIG. 3 shows the configuration of a conventional particle detection device. With the vacuum chuck 12, the semiconductor substrate 1
1 is held horizontally. Laser light L11 is emitted from the laser light source 100 onto the surface of the semiconductor substrate 11 at a constant incident angle. An integrating sphere 21 having a mirror surface inside is installed on the semiconductor substrate 11. The integrating sphere 21 has a hole 23 for allowing the laser light L11 to pass from the outside, and the laser light L11 on the semiconductor substrate 11.
And a scattered light inlet 22 for taking in the scattered lights L13 to L15, and a hole 24 for letting out the reflected light L12 specularly reflected by the laser light L11 irradiated to the semiconductor substrate 11 to the outside. .

When the fine particles 17 are present on the surface of the semiconductor substrate 11, the irradiated laser beam L11 is scattered. The scattered laser lights L13 to L15 enter through the scattered light intake port 22 of the integrating sphere 21 installed on the semiconductor substrate 11 and reflect upward inside while heading upward. And the integrating sphere 21
The photodetector 15 provided on the upper part of the
~ L15 is detected. The vacuum chuck 12 is the motor 1
It is possible to rotate in the direction of arrow A by means of 3 and further to slide in the direction of arrow B or C by means of a sliding mechanism (not shown). As a result, the entire surface of the semiconductor substrate 11 can be irradiated with the laser light L11, and the distribution and total number of the fine particles 17 on the semiconductor substrate 11 can be measured.

The semiconductor substrate 1 of the laser light L11
The reflected light L12 specularly reflected by 1 is not scattered by the fine particles 17. Therefore, when such reflected light L12 is detected by the photodetector 15, the fine particles 1
The detection of 7 will be disturbed. Therefore, the reflected light L1
2 goes out of the integrating sphere 21 through the hole 24 and the photodetector 15
So that it is not detected by.

[0005]

However, the conventional particle detecting device has the following problems. Recent research has revealed that, as shown in FIG. 4, a minute recess 31 having a diameter of about 0.1 μm exists on the surface of the semiconductor substrate 11. When such a depression 31 is present, the laser light L11 is scattered on the semiconductor substrate 11. Therefore, the photodetector 15 erroneously detects the depression 31 as the fine particle 17. As described above, the conventional particle detection device has a problem that the particles 17 cannot be detected separately from the depressions 31, and the measurement accuracy is low.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a particle detection device capable of detecting particles with high accuracy.

[0007]

A particle detection apparatus of the present invention is a light source that irradiates light on a surface of a subject almost in parallel, and particles of the light emitted from the light source that are scattered on the subject. It is characterized in that it is provided with a means for collecting and detecting the light and detecting the fine particles. Alternatively, the particle detection device of the present invention includes a first light source that irradiates the surface of the subject with light substantially in parallel, a second light source that irradiates the surface of the subject with light at a predetermined incident angle, and a first light source. Of the light emitted from the light source, the light scattered by the fine particles is collected and detected to detect the fine particles, and among the light emitted from the second light source, the fine particles present on the subject and the surface of the subject It is characterized in that it is provided with a detection means for detecting the fine particles and the cavities by collecting and detecting the light scattered by the cavities present in the.

[0008]

The fine particles are detected by irradiating the surface of the subject with light from the light source substantially in parallel and collecting and detecting the light scattered by the fine particles by the detecting means. In this case, even if there are dents on the surface of the subject, the light radiated substantially parallel to the surface of the subject is not scattered, so only fine particles are detected.

Alternatively, the surface of the subject is irradiated with light from the first light source substantially in parallel, and the particles are scattered and detected by the particles. Further, the surface of the subject is irradiated with light from the second light source at a predetermined incident angle, and the light scattered by the fine particles and the depressions is collected and detected. This makes it possible to detect only the fine particles and the fine particles and the depressions.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows the configuration of a particle detection device according to the first embodiment. The conventional particulate matter detection apparatus shown in FIG. 3 includes a light source 100 that irradiates a laser beam on a semiconductor substrate 11 with a constant incident angle. On the other hand, the present embodiment is characterized in that the semiconductor substrate 11 is provided with the light source 101 for irradiating the laser light L1 substantially in parallel. Along with this, the integrating sphere 14 is not provided with a hole through which the laser light passes, other than the scattered light inlet 16 for taking in the scattered light. The same components as those of other conventional devices are designated by the same reference numerals and the description thereof will be omitted.

Laser light L1 emitted from the light source 101
Are scattered substantially at the point where the fine particles 17 exist in parallel with the semiconductor substrate 11, and the scattered lights L3 to L5 are scattered by the integrating sphere 14.
It is collected inside. In the region where the fine particles 17 are not present, the laser light L1 goes straight on the semiconductor substrate 11 (laser light L2) and is not focused on the integrating sphere 14. Therefore, only the lights L3 to L5 scattered by the fine particles 17 can be condensed, and the measurement accuracy is prevented from being lowered.

In the present embodiment, the laser light L1 is irradiated substantially parallel to the semiconductor substrate 11, so that the semiconductor substrate 1
It is scattered only by the fine particles 17 on 1 and not by the depressions. As a result, only the fine particles 17 can be detected, and extremely high measurement accuracy can be obtained.

The result of detecting fine particles using the detection apparatus according to the first embodiment will be described. In the light source 101,
An argon laser capable of irradiating the laser beam L1 having a wavelength of 488 nm was used. Further, the scattered light intake 16 provided in the integrating sphere 21 is preferably as small as possible so that the plurality of fine particles 17 are not simultaneously detected. Therefore,
The size of the holes was 100 μm in diameter. The semiconductor substrate 11 has a commercially available diameter of 5 inches and a crystal orientation of <100.
25 pieces of p-type silicon substrates of <> were used. The number of fine particles adhering to the surface of such a semiconductor substrate was measured using the apparatus of this example. As a result, a measurement result was obtained in which 215 fine particles having a diameter of 0.1 μm or more were attached to each semiconductor substrate on average. In addition, when the number of fine particles on the same semiconductor substrate was measured by a conventional device, it was 3 on average.
A result of 50 pieces was obtained.

The difference (135) between the value measured by the apparatus of this embodiment and the value measured by the conventional apparatus may be due not only to the number of depressions but also to the error of the measuring apparatus. To be Therefore, the fine particles were intentionally attached to the semiconductor substrate used for the measurement, and the number of fine particles was measured again using the apparatus according to this example and the conventional apparatus. As a result, in the device according to this embodiment, an average of 625 per semiconductor substrate is obtained.
While the number was 5,000, when the conventional apparatus was used, the number was 755 on average. The difference between the measured values at this time is 130. Since the differences in the measured values are almost the same, it was found that this value is the number of depressions existing on the surface of the semiconductor substrate. Therefore, it was confirmed that the particle detection device according to the present example can ignore the influence of the depression as an error on the measurement value, and can measure only the number of particles with high accuracy. Being able to accurately measure the number of fine particles makes it possible to clarify the behavior of the fine particles during the semiconductor manufacturing process, resulting in an improvement in yield.

Next, a second embodiment of the present invention will be described. The structure of the particle detecting device according to the second embodiment is as shown in FIG. In this embodiment, a light source 10 for irradiating a laser beam L1 almost in parallel with a semiconductor substrate 11 is used.
In addition to 1, the semiconductor substrate 11 is characterized by further including a light source 100 that emits the laser light L11 with a predetermined incident angle. Accordingly, the integrating sphere 21 has a light source 10
A hole 23 for passing the laser beam L11 from 0,
A hole 24 for letting out reflected light is formed.

First, the laser light L11 is emitted from only the light source 101.
And the light L3 to L5 scattered by the fine particles 17
Is collected and detected. As a result, the number of only the fine particles 17 is detected as in the case of the first embodiment.

Further, the laser light L1 is emitted only from the light source 100.
The light L13 to L15 scattered by the fine particles 17 and the depressions on the semiconductor substrate 11 is collected and detected. As a result, the total value of the number of fine particles 17 and the number of depressions is measured as in the conventional case. By subtracting the number of only the fine particles 17 from this value, the number of only the depressions can be obtained.

The fine particle detecting apparatus according to the second embodiment as described above was used to detect depressions existing on the surface of various commercially available semiconductor substrates. According to this, it became clear that the size, distribution, and density of the depressions were characterized by the manufacturing companies. It was also found that the formation of the depression largely depends on the conditions under which the silicon single crystal grows and the processing conditions. Therefore, by detecting the depressions using the apparatus according to the present embodiment, it becomes possible to evaluate the crystal quality of the semiconductor substrate, select a higher quality substrate, and improve the yield.

The above-mentioned embodiments are merely examples and do not limit the present invention. For example, although an argon laser is used as the light source in the embodiment, another light source may be used. Further, not limited to the integrating sphere, any condensing means may be used as long as it can condense the light scattered by the fine particles or the depressions.

[0020]

According to the particle detecting apparatus of the present invention, since the light from the light source irradiates the surface of the subject substantially in parallel, the particles are scattered only by the particles and not by the depressions, and only the particles are detected with high accuracy. It is possible.

Furthermore, when not only the first light source that irradiates the surface of the object to be inspected with light substantially in parallel but also the second light source that irradiates the light at a predetermined incident angle is provided, Since the irradiated light is scattered by the fine particles and the depressions, it is possible to detect the total number of the fine particles and the depressions, and it is possible to accurately detect the number of only the fine particles and the number of the depressions. is there.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing the structure of a particle detection device according to a first embodiment of the present invention.

FIG. 2 is a vertical sectional view showing the structure of a particle detection device according to a second embodiment of the present invention.

FIG. 3 is a vertical cross-sectional view showing the configuration of a conventional particle detection device.

FIG. 4 is a vertical cross-sectional view of a semiconductor substrate to be detected by the particle detection device according to the present invention.

[Explanation of symbols]

11 Semiconductor substrate 12 Vacuum chuck 13 motor 15 Photodetector 16,22 Scattered light intake 17 Fine particles 21 integrating sphere 23, 24 holes 100, 101 light source L1, L2, L11, L12 laser light L3, L4, L5, L13, L14, L15 scattered light

Claims (2)

[Claims] 1. A light source for irradiating light on a surface of a subject substantially in parallel, and of the light emitted from the light source, light scattered by fine particles on the subject is collected and detected. A fine particle detection device comprising: a detection unit that detects the fine particles. 2. A first light source for irradiating the surface of the subject with light substantially in parallel, a second light source for irradiating the surface of the subject with light at a predetermined incident angle, and the first light source. Among the light emitted, the light scattered by the fine particles is collected and detected to detect the fine particles, and among the light emitted from the second light source, the fine particles existing on the subject and the A fine particle detection device comprising: a detection unit that collects and detects light scattered by a dent existing on the surface of a subject to detect the fine particle and the dent.