JPH06118011A - Inspection device and method - Google Patents

Abstract

PURPOSE:To inspect a transparent film after built up for dust and judge whether the dust is on a sample substrate or in the transparent film from the result. CONSTITUTION:A laser beam 2 emitted from a light source 1 is incident on a sample substrate 4 placed on a moving table 3 at an incident angle of 45 deg.. The laser beam 2 incident on the sample substrate 4 is reflected from the sample substrate 4. The reflected beam 7 is measured by a detector 6. The detector 6 is moved around a position A as a fulcrum (center) on the sample substrate 4, where the laser beam 2 is irradiating along, its periphery apart by the diameter of the laser beam 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inspection device and an inspection method.

[0002]

2. Description of the Related Art In recent years, semiconductor devices having a fine line width have been manufactured with the high integration of semiconductor integrated circuits. One of the most important things to note when manufacturing a semiconductor device is the problem of dust or particles. Normally, in a semiconductor device having a submicron line width, the cleanliness during the manufacturing process must satisfy the severe environmental condition of class 1 or less. Although the clean room has a structure that meets such requirements, the generation of dust and particles by humans poses a problem at the semiconductor element manufacturing site.

If dust or particles adhere to the silicon substrate forming the semiconductor element, the semiconductor element formed there becomes defective. Therefore, the dust and particles of the silicon substrate are measured in advance.

FIG. 7 shows a schematic view of a conventional dust inspection device. The laser light 2 emitted from the light source 1 is applied to the sample substrate 4 mounted on the moving table 3. When dust or particles are present on the surface of the sample substrate 4, the laser light 2 is scattered by the dust. This scattered light 5 is measured by the detector 6. The intensity of the scattered light 5 detected by the detector 6 is
It is lower than the intensity detected from the dust-free area. Therefore, if the intensity of the scattered light 5 is monitored over the entire sample substrate 4, it is possible to know where on the sample substrate 4 the dust and particles are located.

[0005]

However, in the above-mentioned conventional configuration, although it is possible to know where on the sample substrate 4 the dust and particles on the surface of the sample substrate 4 are located, an oxide film is formed on the sample substrate 4. When a transparent film such as a nitride film or a nitride film is formed, it is possible to separate from the obtained signal whether the dust is the dust on the surface of the sample substrate 4, the dust in the transparent film, or the dust on the transparent film. No, you can only know that all the dust is present.

This is very inefficient in manufacturing a semiconductor device. That is, if it is attempted to distinguish between the dust on the surface of the sample substrate 4, the dust in the transparent film, and the dust on the transparent film by using the conventional dust inspection device, the dust inspection is performed before depositing the transparent film, and After forming the transparent film, dust inspection is performed again. After that, the inspection results of both are compared to determine in which manufacturing process the dust is generated.

If it is judged from this judgment that the amount of dust on the surface of the sample substrate 4 is large, the sample substrate 4 is washed more carefully. If it is determined that the dust is on the transparent film in the transparent film, cleaning of the film forming device for the transparent film,
Cleaning of gas and gas pipes will be performed. As described above, in the determination by the dust inspection, it is necessary to change the manufacturing process, the manufacturing apparatus, or the like, and therefore an accurate inspection must be performed. However, in the conventional configuration, even if such an inspection is repeated a plurality of times, it is not possible to know the dust generated in the process until the transparent film is deposited after the sample substrate 4 is inspected, and an erroneous judgment is made. Will be done.

It is an object of the present invention to provide an inspection device and an inspection method capable of inspecting dust after depositing a transparent film and judging from the result whether the dust is on the sample substrate or in the transparent film. It is in.

[0009]

In order to solve the above problems, an inspection apparatus of the present invention comprises a sample substrate, a moving table for moving the sample substrate, and a light source for irradiating the sample substrate with laser light. The laser light is provided with a reflected light reflected by the sample substrate and a detector for detecting the reflected light, and the detector is installed on an extension of the optical path of the reflected light reflected by the sample substrate surface, Move the detector left and right.

Further, in order to solve the above-mentioned problems, the inspection method of the present invention moves the sample substrate placed on the moving table so that the detector extends the optical path of the reflected light reflected by the surface of the sample substrate. , A step of irradiating the sample substrate with laser light, a step of detecting reflected light that is the laser light reflected by the sample substrate with a detector, and the detector is moved to the left and right of the optical path. The source of dust of the sample substrate is determined from the signal obtained by the detector.

[0011]

According to the above structure, the dust on the sample substrate and the dust in the transparent film can be distinguished by moving the detector left and right.

Similarly, by moving the detector to the left and right, the dust existing on the sample substrate and the dust in the transparent film can be distinguished, and the source of the dust can be known from the result, which is suitable. Dust measures can be taken.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a block diagram showing the inspection apparatus of the present invention. A helium-neon laser is used as the light source 1. The laser light 2 emitted from the light source 1 is a spot light having a diameter of 2 mm. The laser light 2 is incident on the sample substrate 4 placed on the moving table 3 at an incident angle of 45 degrees. Moving table 3
Moves the sample substrate 4 left and right during measurement. Further, it is possible to move the paper surface in the front and back directions. The sample substrate 4 has an oxide film formed on a silicon substrate.

The laser light 2 incident on the sample substrate 4 is reflected by the sample substrate 4. The reflected reflected light 7 is measured by the detector 6 having a photodiode. Normally, when dust or the like is present on the sample substrate 4, the laser light 2 incident on the dust is scattered. Therefore, the amount of light detected by the detector 6 is smaller than that in the case where there is no dust. That is, the presence or absence of dust can be determined by scanning the sample substrate 4 with the laser light 2 and measuring the amount of light with the detector 6. The inspection apparatus of this embodiment also has the same function.

The detector 6 is installed at a position where the laser light 2 can detect the reflected light 7 reflected by the sample substrate 4 without dust. Further, the detector 6 has a diameter of the laser beam 2 of 2 mm.
Only, the position A irradiated with the laser beam 2 on the sample substrate 4 is moved as a fulcrum (center) on the circumference thereof. This movement moves in the direction of arrow B shown on the paper surface in this embodiment. However, the moving direction is not limited to the direction of the arrow B, but may be the front and back directions of the paper, and furthermore, one point on the circumference of a circle having a radius of 1 mm centered on the center of the detection surface of the detector 6. It suffices that the detector 6 moves on a straight line passing through the center of the detector.

Next, a case where an inspection is performed using the inspection device having the above-mentioned configuration will be described. FIG. 2 is an enlarged sectional view of the sample substrate 4. The sample substrate 4 has a silicon substrate 8 on which an oxide film 9 is formed. The laser light 2 is incident on the oxide film 9. At this time, since the air and the oxide film 9 have different refractive indexes, the laser light 2 travels straight through the oxide film 9 with a predetermined refraction angle. The laser light 2 that has traveled straight ahead travels by the thickness of the oxide film 9 and collides with the underlying silicon substrate 8. Here, the laser light 2 is reflected, and the reflected light 7 is detected by the detector 6 through a process reverse to the incident.

In the present embodiment, when dust is present in the oxide film 8, it is for measuring whether the dust is on the oxide film 8. For this reason, the sample substrate 4 is formed of the silicon substrate 8 and the oxide film 9, but the base substrate may be any substrate made of a material that reflects light. Needless to say, a permeable film made of a material that transmits the is.

The position where the detector 6 is installed can be obtained from the incident angle of the laser beam 2 incident on the oxide film 8, the thickness of the oxide film 9, and the refractive index of the oxide film 9. However, in practice, it is preferable to scan the sample substrate 4 as a reference made of the same material and find the position where the light amount is the largest from the reflected light reflected from the sample substrate 4.

A case where dust is present on the surface of the silicon substrate 8 will be described with reference to FIG. In the figure, since the laser beam 2 has a diameter of 2 mm, it is schematically represented as a band-shaped straight line.

On the silicon substrate 8, there is dust 10 that reflects or scatters light on the surface. Detector 6
Is initially installed at a predetermined position between the light source 1 and the detector 6 obtained by the reference measurement.
That is, it is installed at a position where the light at the center of the spot of the laser light 2 is incident. The laser light 2 at this position passes through the optical path indicated by the dotted line B in the figure. Next, the detector 6 is moved in the direction of the arrow. Here, the directions of the arrows are indicated by + and − symbols in the drawings.

FIG. 4 shows a signal waveform detected when the detector 6 is moved in the arrow direction. The vertical axis of the figure is the light intensity. "0" at the center of the horizontal axis is the position where the detector 6 detects the light of the dotted line B. As shown in FIG. 4, since the laser light 2 which hits the dust 10 is scattered, its intensity decreases.
In this case, even if the laser light 2 is sequentially scanned, the decrease in the light intensity due to the dust 10 is observed only when the laser light 2 is directly applied to the dust 10.

Next, a case where the dust 10 exists in the oxide film 9 will be described with reference to FIG. The laser beam 2 is displayed as in FIG. When this state is compared with when the dust 10 is present on the surface of the silicon substrate 8, when the dust 10 is present in the oxide film 9, the presence or absence of the dust 10 indicates that the position of the laser beam 2 is the solid line and the broken line in the figure. The difference is that it is detected at two positions indicated by. These two positions are detected by the light with which the center of the laser beam 2 irradiates points C and D in the figure. Scanning with laser light 2 illuminates point D,
At that time, if the detector 6 moves by the diameter of the laser beam 2,
The signal waveform obtained by the detector 6 is the silicon substrate 8
The signal waveform is exactly the same as when the dust 10 is present on the surface.

Further, the signal detected at the point where the light source 1 has moved by the distance between the point C and the point D can obtain a similar signal waveform. Thus, if the dust 10 is present on the surface of the silicon substrate 8, even if the light source 1 and the detector 6 are moved, the signal obtained by the dust 10 is unique.

However, at this time, if there is another dust in the optical path of the laser beam 2 incident on the point C, a similar signal waveform will be obtained.

However, as described below, according to this embodiment, it is possible to reliably determine whether the dust 10 is present on the surface of the silicon substrate 8 or the dust 10 present in the oxide film 9.

FIG. 6 shows a signal waveform obtained by the laser light 2 incident on the points C and D. The detection method is the same as that for obtaining the signal shown in FIG.

FIG. 6A shows a signal waveform by the laser beam 2 with which the point D is irradiated. The laser light 2 enters the oxide film 9 and is scattered by the dust 10 inside. The laser light 2 that is not applied to the dust 10 is reflected by the surface of the silicon substrate 8 and enters the detector 6. Of the laser light 2 scattered by the dust 10, the intensity of the light incident on the detector 6 is E. When the incident laser light 2 irradiates the dust 10, the scattered light is scattered in the same plane as the detector 6.

On the other hand, FIG. 6 (b) shows a signal waveform by the laser beam 2 applied to the point C. With respect to the laser light 2 applied to the point C, the light once reflected on the surface of the silicon substrate 8 hits the dust 10. The reflected light that hits the dust 10 is scattered. However, in this case, the reflected light is irradiated to the lower part of the dust 10 and scattered. Therefore, scattered light hardly occurs in the direction of the detector 6, is scattered toward the silicon substrate 8 side, and the light intensity detected by the detector 6 is F. The light intensity F is smaller than the light intensity E shown in FIG. 6A for the above reason. Therefore, if there is another dust in the optical path of the laser beam 2 incident on the point C, the light intensity of the signal waveform will be E, and if the dust 10 is one detected at the point D, the signal will be The light intensity of the waveform is F. In this way, the dust 10 in the oxide film 9 can be accurately determined.

As described above, the inspection apparatus of this embodiment can know whether the dust is on the surface of the silicon substrate or in the oxide film. This is because when a film deposition apparatus such as a CVD apparatus or a sputtering apparatus for depositing an oxide film on a silicon substrate is used, dust on the sample substrate is present on the silicon substrate before the deposition of the film. It was possible to determine whether it had been formed or was formed during the growth of the film.

Therefore, it is possible to know the source of dust that adversely affects the manufacturing of the semiconductor integrated circuit, and it is possible to take appropriate measures against dust in an early stage.

[0032]

According to the present invention, whether dust or particles existed on the substrate surface before the transparent film was deposited,
Since it is possible to know whether or not it is the dust accumulated during the film formation, it is possible to know the dust generation source in the manufacture of the semiconductor integrated circuit as a dust monitor, and it is possible to take an appropriate dust countermeasure at an early stage.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an inspection apparatus that is an embodiment of the present invention.

FIG. 2 is an enlarged view of a sample substrate of the present invention.

FIG. 3 is a schematic diagram when inspecting dust using the inspection device of the present invention.

FIG. 4 is a signal waveform diagram when inspecting dust using the inspection device of the present invention.

FIG. 5 is a schematic diagram when inspecting dust using the inspection apparatus of the present invention.

FIG. 6 is a signal waveform diagram when inspecting dust using the inspection device of the present invention.

FIG. 7 is a block diagram of a conventional inspection device.

[Explanation of symbols]

 1 Light Source 2 Laser Light 3 Moving Table 4 Sample Substrate 6 Detector 7 Reflected Light

Claims (4)

[Claims] 1. A sample substrate, a moving table for moving the sample substrate, a light source for irradiating the sample substrate with laser light, and reflected light obtained by reflecting the laser light on the sample substrate.
An inspection comprising a detector for detecting the reflected light, wherein the detector is installed on an extension of an optical path of the reflected light reflected on the surface of the sample substrate, and the detector is moved to the left and right of the optical path. apparatus. 2. The inspection apparatus according to claim 1, wherein the sample substrate has a lower layer that is a reflective substrate that reflects light and an upper layer that is a transmissive film that transmits light. 3. A step of moving a sample substrate placed on a moving table so that a detector is installed on an extension of an optical path of reflected light reflected on the surface of the sample substrate, and irradiating the sample substrate with laser light. A step, a step of detecting a reflected light that is the laser light reflected by the sample substrate with a detector, a step of moving the detector to the left and right of the optical path, the signal obtained by the detector from the An inspection method characterized by determining the source of dust on a sample substrate. 4. The sample substrate has a lower layer that is a reflective substrate that reflects light, and an upper layer that is a transmissive film that transmits light.
4. The inspection method according to claim 3, wherein it is determined from the signal obtained by the detector whether dust is present on the surface of the reflective substrate or in the transparent film.