JPH06242015A - Microparticle detection system - Google Patents

Abstract

PURPOSE:To provide a microparticle detection system for detecting a microparticle in a short time. CONSTITUTION:The microparticle detection system comprises a scattering light detecting optical system 4 for irradiating the surface 10 of an object 9 with a plurality of laser beams and detecting the light Ls scattered from a microparticle adhered to the surface 10, a scan mechanism section 2 for relatively displacing the object 9 and the optical system 4 and scanning the surface 10 by means of the laser beam, and a data processing section 3 for processing data detected by the optical system 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a particle detection device for optically detecting particles adhering to an object to be inspected such as a semiconductor wafer.

[0002]

2. Description of the Related Art Generally, in manufacturing semiconductors, optical disks, etc., ultrafine particles (foreign particles) of several μm or less and scratches adversely affect the quality. Therefore, a technique for detecting particles and scratches in advance has been developed. This kind of technology
Japanese Patent Publication No. 1-20483, Japanese Patent Publication No. 3-34576, Japanese Patent Publication No. 3-34577 and the like. In these techniques, the surface of an object to be inspected such as a substrate or a disk is scanned with laser light, and scattered light from particles is observed.

[0003]

By the way, in the conventional detection technique as described above, the spot diameter of the laser light is limited to about several μm. However, the diameter of the particles is
The spot size of light is extremely small (for example, the particle size is
In the case of 0.1 μm or less), the scattered light becomes extremely weak, and the signal component of the scattered light and the noise component of the detector or the light source cannot be distinguished. Further, in order to increase the detection sensitivity, it is possible to further concentrate the laser light and narrow the spot diameter. However, it is difficult to apply this technique to actual inspection because the time required to scan the entire surface of the object to be inspected with the laser light increases significantly. An object of the present invention is to provide a particle detection device capable of detecting extremely small particles in a short time.

[0004]

In order to achieve the above object, the present invention irradiates a plurality of detection lights onto an inspection surface of an object to be inspected and receives scattered light from fine particles adhering to the inspection surface. The scattered light detection optical system for detecting the scattered light, the scanning mechanism unit for relatively displacing the inspected object and the scattered light detection optical system to scan the detection surface with the detected light, and the detection data of the scattered light detection optical system are processed. And a data processing unit for performing the same. By doing so, the present invention is to enable detection of extremely small particles in a short time.

[0005]

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

FIG. 1 shows an embodiment of the present invention. Reference numeral 1 in the drawing is a particle detection device (hereinafter referred to as a detection device). The detection device 1 has a scanning mechanism section 2, a data processing section 3, and a scattered light detection optical system (hereinafter referred to as a detection optical system) 4.

Of these, the scanning mechanism section 2 is a linear motion stage.
A rotary stage 6, a rotary stage 6, a linear encoder 7 and a rotary encoder 8 are provided. The linear motion stage 5 supports the rotary stage 6 and is linearly displaced in one direction as shown by an arrow A. Further, the amount of movement of the linear motion stage 5 is detected by the linear encoder 7.

Further, the rotary stage 6 is vertically provided on the linear motion stage 5, and a disk-shaped object 9 to be inspected is horizontally mounted on the rotary stage 6. The surface (inspection surface) 10 of the inspected object 9 is processed into a flat surface with high accuracy.
The rotating stage 6 rotates the object 9 to be inspected concentrically as indicated by an arrow B. Then, the rotation amount of the inspected object 9 is detected by the rotary encoder 5.

The linear stage 5 and the rotary stage 6 are used here.
Various general drive sources and guide mechanisms can be used, and thus description thereof will be omitted. Also, as the linear encoder 7 and the rotary encoder 8, various general ones can be used, and therefore their description will be omitted.

The data processing unit 3 includes a pulse detection circuit 11,
A computer 12 and an output unit 13 are provided. The pulse detection circuit 11 receives the detection data of the linear encoder 7 and the rotary encoder 8. The output of the pulse detection circuit 11 is sent to the computer 12, and the computer 12 outputs a predetermined data based on the output of the pulse detection circuit 11.
Data processing. The processing result of the computer 12 is output to the output unit 13. A general display, printer, or the like can be used as the output unit 13.

The detection optical system 4 is arranged above the object 9 to be inspected. The detection optical system 4 is the semiconductor laser array 1
4 and a microlens array 15. Both arrays 14 and 15 are processed into a square flat plate shape.
Both arrays 14 and 15 face each other in parallel at a predetermined interval. Further, the microlens array 15 is used for the inspection object 9
However, they are parallel to and oppose the surface 10 at regular intervals.

As shown in FIGS. 2 and 3, the semiconductor laser array 14 has a plurality of semiconductor lasers 16 serving as light sources.
And a photodiode 17 as the scattered light detecting means. That is, the surface of the substrate 18 of the semiconductor laser array 14 is finely divided into a matrix, and the semiconductor lasers 16 ... Are formed in the center of each division 19. Each semiconductor laser 16 ...
Laser light 20 as detection light perpendicular to the surface of 8 ...
Is emitted.

The photodiodes 17 ... Are thin films, and the surface thereof is the light receiving surface 21. Photodiode 1
7 are formed for each of the sections 19 ... The photodiodes 17 have a perfect circular ring shape, and a pinhole (emission hole) 22 is opened in the center. The semiconductor lasers 16 ... Are exposed from the center of the pinholes 22 ..., and the laser light 20 ... Is emitted while passing through the pinholes 22.

Here, the arrangement of the photodiode 17 and the semiconductor laser 14 has a correlation. That is, the positional relationship between the two is set so that the laser light 20 that propagates while spreading is not blocked by the inner peripheral edge of the photodiode 17.

In the microlens array 15, as shown in FIGS. 4 and 5, a large number of rod lenses (hereinafter referred to as lenses) 24 ... . Each lens 24 has a cylindrical shape, and the length of the lens 24 and the thickness of the microlens array main body 23 are the same. further,
The lens 24 is of a refractive index changing type, and the refractive index changes greatly from the axial center to the outside.

The lenses 24 are arranged in a matrix at an equal pitch, and the arrangement pitch of the lenses 24 is set to be the same as the arrangement pitch of the semiconductor lasers 16.
Further, the lenses 24 ... One-to-one correspond to the semiconductor lasers 16 ... And are located on the same optical axis as the semiconductor lasers 16. And each one semiconductor laser 16,
A unit optical system 25 is composed of the photodiode 17 and the lens 24. The detection principle of the unit optical system is shown in FIG.

The laser light 20 emitted from the semiconductor laser 16 spreads in a conical shape, passes through the pinhole 22, and reaches the corresponding lens 24. The beam diameter when the laser light 20 passes through the pinhole 19 is the pinhole 22.
The diameter is the same as or slightly smaller. The diameter of the end surface of the lens 24 is larger than the diameter of the laser light 20 that has reached.

The laser light 20 that has passed through the lenses 24 is focused and focused on the surface 10 of the object 9 to be inspected. Surface 1
0 In light L _O that specular reflection reaches the lens 24 at the same opening angle θ as the previous reflection, semiconductor laser passes through the lens 24 - Back to The 16.

However, when the fine particles 26 adhere to the surface 10, the light reflected by the fine particles 26 is scattered in all azimuth angles. Therefore, scattered light L _S that enters the lens 24 is generated from the outside of the regular reflection light L _O as indicated by the diagonal lines in the figure, and this scattered light L _S is emitted from the outside of the regular reflection light L _O to the semiconductor laser. 1
Go to 6. When the regular reflection light L _O passes through the pinhole 22 of the photodiode 17, the beam diameter of the regular reflection light L _O is approximately the same as the diameter of the pinhole 22, so the scattered light L _S is The light does not pass through the pinhole 22 and is incident on the light receiving surface 21 of the photodiode 17. Then, the scattered light L _S is detected by the photodiode 17.

In this embodiment, the semiconductor laser array 14 is connected to the pulse detection circuit 11 as shown in FIG. 1, and the output of each photodiode 17 ... Is sent to the pulse detection circuit 11. Further, since the scanning mechanism 2 rotates the object 9 to be inspected, the laser light 20 ... Is scanned on the surface 10 of the object to be inspected, and the laser light 20 ... Is irradiated. Further, when the entire surface cannot be scanned only by rotating the inspection object 9, the inspection object 9 is linearly moved by the linear movement stage 5, and the laser beam 20 ... To be done.

Linear encoder 7 and rotary encoder
The datum 8 detects the amount of displacement of the linear motion stage 5 and the rotational stage 6, and the detected data is sent to the pulse detection circuit 11. The pulse detection circuit 11 converts the output of the semiconductor laser array 14 and the outputs of both encoders 7 and 8 into a signal for computer input and sends the signal to the computer 12. Computer 12
Maps the output data of the photodiode 17 ... To the memory. Then, when strong scattered light of a predetermined value or more is detected, it is determined that the fine particles are present at the position where the scattered light is obtained.

The detection device 1 as described above is provided with the detection optical system 4, and a plurality of laser lights 20 ... Are irradiated from the detection optical system 4 to a plurality of positions on the surface 10 of the object 9 to be inspected. It Further, the scanning mechanism section 2 displaces the inspected object 9 so that the laser light 20 scans the entire surface 10. Then, the data processing unit 3 determines the presence or absence of fine particles based on the detection data of the detection optical system 4. Therefore,
Laser light scanning can be performed in a short time, and the time required for detecting fine particles can be shortened.

Further, the detection optical system 4 is provided with a semiconductor laser array 14 and a microlens array 15, and the semiconductor laser array 14 has a large number of semiconductor lasers 1.
6 and a photo diode 17 are formed. The laser light 20 emitted from the semiconductor laser 16 ...
Is squeezed by the lens 22 and irradiates the surface 10 of the inspection object 9. Therefore, the spot diameter of the laser light 20 can be reduced. It should be noted that the present invention is not limited to the above-described embodiments, and can be variously modified without departing from the scope of the invention.

For example, in this embodiment, scattered light L _S
Although a thin film photodiode 17 ... Is used for receiving light, the present invention is not limited to this.
For example, as shown in FIGS. 7A and 7B, an optical fiber-
The bundle 31 may be arranged annularly. In this case, the photodetector is separate from the semiconductor laser array 14 and the scattered light is guided to the photodetector via the optical fiber bundle 31.

Although the semiconductor lasers 16 ... And the photodiodes 17 ... Are formed on the same substrate 18 in this embodiment, they may be formed on different substrates and combined, for example.

Further, in the present embodiment, the lenses 24 of the microlens array 15 are rod-shaped refractive index changing type, but curved type lenses 33 may be used as shown in FIG. 8, for example.

The laser light 20 emitted from the semiconductor laser 16 is directly incident on the microlens array 15. For example, the laser light 2 is made by using an optical fiber.
0 may be transmitted from the outside, and the laser light 20 may be emitted from the optical fiber toward the lenses 24. Furthermore, a light source other than the semiconductor lasers 16 may be used as long as the same diffused light as in this embodiment can be obtained.

Further, the array of the unit optical system 25 does not necessarily have to be a matrix, but the semiconductor laser array 1
4 or the optimum arrangement for the scanning mechanism unit 2 may be selected. For example, when the object 9 to be inspected has a disk shape and the object 9 to be inspected rotates as in this embodiment, the surface 10 can be obtained by arranging the unit optical systems 25 in a line at equal intervals.
It is possible to scan the whole of.

Further, as shown in FIG. 9, each section 19 of the semiconductor laser array 14 (and the microlens array 1)
If the lenses 24 of 5 are diagonally arranged while being shifted in a stepped manner, the scanning interval p of the laser light 20 can be narrowed. Such an arrangement is effective when, for example, each section 19 cannot be freely reduced. As other arrangements, an illegal pitch arrangement, a staggered arrangement, and the like can be considered.

Further, in this embodiment, the linear motion stage 5 and the rotary stage 6 are used for scanning the laser light 20 ..., However, various general moving mechanisms are adopted. It is possible to

[0031]

As described above, the present invention irradiates a plurality of detection lights onto the inspection surface of an object to be inspected and receives scattered light from fine particles adhering to the inspection surface to detect the scattered light. A scanning mechanism section for relatively displacing the object to be inspected and the scattered light detection optical system to scan the inspection surface with the detected light, and a data processing section for processing the detection data of the scattered light detection optical system. Equipped Therefore, the present invention has an effect that detection of extremely small particles can be performed in a short time.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing the operation of a scattered light detection optical system.

FIG. 3 is an enlarged view showing a part of a semiconductor laser array.

FIG. 4 is a perspective view showing a part of a microlens array.

FIG. 5 is an enlarged cross-sectional view showing a part of a microlens array.

FIG. 6 is an explanatory diagram showing a detection principle of a unit optical system.

FIG. 7A is a view showing a modified example of the scattered light detection means,
(B) is an enlarged view of a portion surrounded by a circle C in (a).

FIG. 8 is a diagram showing a modified example of a microlens array.

FIG. 9 is an explanatory view showing a modified example of the arrangement of each section formed in the semiconductor laser array.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Particle detection device, 2 ... Scanning mechanism part, 3 ... Data processing part, 4 ... Scattered light detection optical system, 9 ... Inspected object, 10 ... Inspected object surface (inspection surface), 14 ... Semiconductor laser -The array, 15 ... Microlens array, 16 ... Semiconductor laser (light source), 17 ... Photodiode (scattered light detecting means), 20 ... Laser light (detection light), 24 ... Rod lens (light collecting) Means), 26 ... fine particles, L _O ... regular reflection light, L _S ...
Scattered light.

Claims (2)

[Claims] 1. A scattered light detection optical system that irradiates a plurality of detection lights onto an inspection surface of an inspection object and receives and detects scattered light from fine particles adhering to the inspection surface, the inspection object, and the inspection object. Fine particles provided with a scanning mechanism section that relatively displaces the scattered light detection optical system to scan the detection surface onto the inspection surface, and a data processing section that processes the detection data of the scattered light detection optical system. Detection device. 2. The scattered light detecting optical system includes a plurality of integrated light sources, scattered light detecting means arranged for each of the light sources, and integrated and collects the detected light on the inspection surface. The particle detection device according to claim 1, further comprising a condensing unit that guides the scattered light to the scattered light detecting unit.