JPH06258235A - Surface inspection device - Google Patents

Abstract

PURPOSE:To provide a surface inspection device by which highly precise detection can be performed. CONSTITUTION:A light beam scans a face 7 to be inspected such as a reticule. Two photoelectric detectors 11a, 11b are arrange spatially in symmetrical positions with respect to a scanning area 6 of the light beam, and detected signals from these two photoelectric detectors 11a, 11b are added together by an adding circuit 13 to generate a sum signal. A foreign matter or a defect is determined on the basis of this sum signal, so that inspection can be carried out with uniform sensitivity without depending on the position in the scanning area 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the technical field of optically inspecting minute objects, defects and the like existing on an inspection surface.

[0002]

2. Description of the Related Art An example of a conventional surface inspection apparatus is shown in FIG. In the figure, the laser light from the light source unit 101 is guided to a scanning optical system including a polygon mirror 102 and an fθ lens system 103. Then, the scanning laser light from the scanning optical system is applied as spot light onto the inspection surface 107 such as a reticle. The spot light one-dimensionally optically scans the scanning region 106 from the position 104 to the position 105. At the same time, the entire surface of the inspection surface 107 is two-dimensionally scanned by moving the inspection surface 107 by the stage 108 in the direction perpendicular to the optical scanning direction.

When a foreign matter or defect exists in the scanning spot, this causes scattered light to be almost isotropic. In order to detect this scattered light, the condensing optical system 110 and the photoelectric detector 111 are arranged laterally as shown in the drawing, and the scanning area 1
The image of 06 is formed on the detection surface of the photoelectric detector 111 as a region 113, which satisfies the so-called Scheimpflug relationship. The filter system 109 is for removing scattered light from other than foreign matters and defects such as a circuit pattern on the inspection surface 107.

As a result, the scattered light is not detected by the photoelectric detector 111 when no foreign matter is present in the scanning spot, and the scattered light is detected by the photoelectric detector 111 only when the foreign matter is present. Then, the photoelectric detector 111
The scattered light signal detected at is guided to the signal processing system 112 to be inspected for foreign matters and defects.

[0005]

However, the above-mentioned conventional apparatus has the following problems. (1) Since the effective F number of the condensing optical system 110 is different between the position 104 and the position 105, the amount of detected light is different. (2) Since the detection angles of scattered light are different between the position 104 and the position 105, the amount of detected light is different.

As described above, since the detection sensitivity differs depending on the scanning spot position in the scanning area 106, it becomes difficult to discriminate the particle size of the foreign matter and the foreign matter and the defect cannot be detected with a high SN ratio.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a system such as a surface inspection apparatus and an exposure apparatus using the same, which can detect with higher accuracy than the conventional one. .

[0008]

A preferred embodiment of a surface inspection apparatus of the present invention for solving the above problems is a scanning means for scanning an inspection surface with a light beam, and a space for the scanning area of the light beam. It has at least two photoelectric detectors arranged at symmetrical positions, and means for generating a sum signal of detection signals from the two photoelectric detectors.

[0009]

【Example】

<Embodiment 1> FIG. 1 is a block diagram of a surface inspection apparatus according to a first embodiment of the present invention. In the figure, 1 is a light source unit including a laser light source and a collimator optical system. 2 is a polygon mirror,
Reference numeral 3 denotes an fθ lens system, which together form a scanning optical system. 6 is an area scanned by the scanning optical system, 4,
Reference numeral 5 is both end positions of the scanning spot, 7 is an inspection surface such as a reticle, and 8 is a stage. Further, 9a and 9b are filter systems, 10a and 10b are condenser optical systems, 11a and 11b are photoelectric detectors, and 13 is a signal obtained by electrically adding signals from the two photoelectric detectors 11a and 11b. An adder circuit 14 is a signal processing system for processing the signal from the adder circuit 13 to determine a foreign matter.

The structure in which the laser light emitted from the light source unit 1 scans the inspection surface 7 two-dimensionally is the same as that of the conventional example shown in FIG. The feature of this embodiment is that the two scanning directions of the scanning region 6 on the inspection surface 7, that is, the lateral direction of approximately 90 degrees with respect to the incident light direction, and the two symmetrical positions when viewed from the center of the scanning region 6 are provided. That is, the photoelectric detectors 11a and 11b are arranged. Here, the scanning area 6 is moved to the photoelectric detector 11a by the condensing optical system 10a.
The Scheimpflug relationship is satisfied so that the image is formed as 12a on the detection surface. Similarly, the condensing optical system 10b
Also satisfies the Scheimpflug relationship, and the scanning region 6 is formed as an image 12b on the detection surface of the photoelectric detector 11b.

Further, the filter systems 9a and 9b placed in front of each condensing optical system include a polarizing plate and an aperture, and remove scattered light caused by foreign matters or defects such as a circuit pattern on the inspection surface 7 as much as possible. I am trying to do it.

In each of the photoelectric detectors 11a and 11b,
Although the detection sensitivities are different between the scanning positions 4 and 5 as described above, the two photoelectric detectors 11a and 11b are arranged at symmetrical positions with respect to the scanning region 6 as in the present embodiment, and the adding circuit 13 is provided. Thus, the detection sensitivity is corrected by adding the scattered light signals to obtain the sum, and it is possible to obtain substantially uniform detection sensitivity at an arbitrary position of the scanning region 6.

FIG. 2 is an explanatory diagram of this detection sensitivity correction. In the figure, 201 is an axis representing the scanning position x on the inspection surface 7, 202 is an axis representing the detection sensitivity I of the photoelectric detector, 204 is a point corresponding to the scanning position 4, and 205 is a point corresponding to the scanning position 5. And 211a is the photoelectric detector 11a.
Is an approximate curve of the detection sensitivity of the photoelectric detector 11b, and 212 is an approximate curve of the combined detection sensitivity obtained by taking the signal sum of the two photoelectric detectors.

Detecting sensitivity approximate curve 21 of photoelectric detector 11a
1a will be described. When viewed from the condensing optical system 10a, the effective F number when collecting scattered light from the scanning position 4 and the effective F number when collecting scattered light from the scanning position 5 are the effective F number at the scanning position 4. The number is larger.
In other words, the light amount detected at the scanning position 4 is smaller. Therefore, assuming that the scattered light of the same intensity is generated from the scanning spot, the point 205 has a higher apparent detection sensitivity than the point 204, and thus a detection sensitivity curve such as 211a is approximately obtained. . For the photoelectric detector 11b, a detection sensitivity curve such as 211b can be approximately obtained for the reason opposite to the above description.

Here, the photoelectric detector 11a and the photoelectric detector 1
If the scattered light signals detected by 1b are added by the adder circuit 13 to generate a sum signal, the detection sensitivities are complemented with each other, and approximately uniform values are obtained from point 204 to point 205. The detection sensitivity curve 212 can be obtained. That is, it is possible to inspect foreign matters and defects at an arbitrary position in the scanning region 6 with substantially uniform sensitivity.

By processing the sum signal thus obtained by the signal processing system 14, it is possible to correct the fluctuation of the sensitivity of the detector due to the position of the scanning spot and to inspect foreign matters and defects with a high SN ratio. Becomes

In this embodiment, two photoelectric detectors 11 are used.
Although a and 11b are arranged in the scanning direction of the scanning region 6, that is, in the lateral direction of 90 degrees, the angle is not limited to 90 degrees.
Further, the two photoelectric detectors may be arranged at positions symmetrical with respect to the center point of the scanning area 6. Further, the number of photoelectric detectors is not limited to two, and for example, four photoelectric detectors may be symmetrically arranged.

<Embodiment 2> FIG. 3 is a block diagram of the essential parts of a second embodiment of the present invention. In the figure, 301a, 30
Reference numeral 1b is a photodetector (bundle fiber) in which optical fibers are bundled and cut surfaces are aligned, and 302 is a bundle fiber 301.
A coupler for combining a and 301b into one, and 303 is a photoelectric detector.

As in the first embodiment, the condensing optical systems 10a and 10b satisfying the Scheimpflug relationship are used.
The scanning region 6 is imaged on each cross section of the bundle fibers 301a and 301b. And bundle fiber 3
The scattered light from the scanning region 6 guided by 01a and 301b is collected by the coupler 302. That is, what is electrically added in the previous embodiment is optically added by the cups 302 in this embodiment. The scattered light collected by the cups 302 is guided to the photoelectric detector 303 and detects the sum signal of the scattered light. This sum signal is processed by the signal processing system 14.

According to the above-mentioned first and second embodiments, the following effects can be obtained. (1) The problem that the detection sensitivity differs depending on the scanning position can be solved, and the foreign substance inspection can be performed with substantially uniform sensitivity within the scanning region. (2) Since uniform detection sensitivity can be obtained, it is possible to perform foreign matter or defect inspection such as particle size discrimination of foreign matter with a high SN ratio.

<Embodiment 3> FIG. 4 is a diagram showing an embodiment of a manufacturing system for manufacturing a semiconductor device by printing a circuit pattern of an original plate such as a reticle or a photomask on a silicon wafer. The system roughly includes an exposure device, an original storage device, an original inspection device, and a controller, which are arranged in a clean room.

Reference numeral 901 denotes a far-ultraviolet light source such as an excimer laser, 902 denotes an illumination system unit, and the exposure position E.I. P. It has the function of illuminating the original set in the above at the same time (batch) from above with a predetermined NA (numerical aperture). Numeral 909 designates a circuit pattern formed on the original plate as a silicon wafer 9
10 is an ultra-high resolution lens system (or mirror system) for transferring onto the wafer 10, and the wafer is moved to the moving stage 9 during printing.
The exposure is repeated while shifting each shot according to the step feed of 11. Reference numeral 900 denotes an alignment optical system for aligning the original and the wafer prior to the exposure operation, and has at least one original observation microscope system. An exposure apparatus is configured by the above members.

On the other hand, reference numeral 914 is an original storage device which stores a plurality of originals inside. Reference numeral 913 is an original inspection device, which includes the configuration of the previous embodiment. The original inspection device 913 detects that the selected original is pulled out from the original storage device 914 and the exposure position E.E. P. The foreign matter inspection on the original plate is carried out before being set to 1. The principle and operation of the foreign matter inspection are the same as those in the above-mentioned embodiment. Controller 91
Reference numeral 8 is for controlling the sequence of the entire system, and controls the operation commands of the original storage device 914 and the original inspection device 913, as well as the basic operations of the exposure apparatus, such as alignment, exposure, and step feed of the wafer. .

The manufacturing process of a semiconductor device using the system of this embodiment will be described below. First, the original storage device 914
The original to be used is taken out and set in the original inspection device 913. Next, the original inspection device 914 inspects the foreign matter on the original. As a result of the inspection, when it is confirmed that there is no foreign matter, this original plate is exposed at the exposure position E. P. Set to.
Next, the silicon wafer 910 which is the exposure target is set on the moving stage 911. Then, according to the step-and-repeat method, the original pattern is reduced and projected onto each region of the silicon wafer while shifting each shot according to the step feed of the moving stage 911, and the exposure is repeated. After the exposure on one silicon wafer is completed, the silicon wafer is accommodated and a new silicon wafer is supplied, and similarly, the exposure of the original pattern is repeated by the step & repeat method.

The exposed silicon wafer that has been exposed is subjected to processing such as development and etching by an apparatus provided separately from this system. Then, a semiconductor device is manufactured through an assembly process such as dicing, wire bonding, packaging and the like.

According to this embodiment, it is possible to manufacture a highly integrated semiconductor device having a very fine circuit pattern, which has been difficult to manufacture in the past.

<Embodiment 4> FIG. 5 is a diagram showing an embodiment of an original plate cleaning inspection system for manufacturing a semiconductor device. The system is roughly: original storage device, cleaning device,
It has a drying device, an inspection device, and a controller, which are arranged in a clean chamber.

Reference numeral 920 denotes an original storage device which stores a plurality of originals and supplies the originals to be cleaned. A cleaning device 921 cleans the original plate with pure water. 92
A drying device 2 dries the washed original plate. 9
Reference numeral 23 denotes an original inspection device, which includes the configuration of the previous embodiment, and inspects foreign materials on the original that has been washed using the method of the above-described embodiment. A controller 924 controls the sequence of the entire system.

The operation will be described below. First, the original plate to be cleaned is taken out from the original plate storage device 920 and supplied to the cleaning device 921. The original plate cleaned by the cleaning device 921 is sent to the drying device 922 to be dried. After the drying, it is sent to the inspection device 923, and the inspection device 923 inspects the foreign matter on the original plate by using the method of the previous embodiment. If no foreign matter is found as a result of the inspection, the original is returned to the original storage device 920. Also, if foreign matter is confirmed,
The original plate is returned to the cleaning device 921, a cleaning / drying operation is performed, and then an inspection is performed again, and this is repeated until the foreign matter is completely removed. Then, the completely cleaned original plate is returned to the original plate storage device 920.

Thereafter, the cleaned original plate is set in an exposure apparatus, and a circuit pattern of the original plate is printed on a silicon wafer to manufacture a semiconductor device. As a result, it is possible to manufacture a highly integrated semiconductor device having a very fine circuit pattern, which has been difficult to manufacture in the past.

[0031]

According to the present invention, it is possible to detect minute foreign matters, defects, etc., which were difficult to detect in the past, with a high S / N ratio. Further, by applying the present invention to semiconductor manufacturing, it is possible to manufacture a highly integrated semiconductor device, which has been difficult to manufacture in the past.

[Brief description of drawings]

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

FIG. 2 is a diagram showing a detection sensitivity curve.

FIG. 3 is a configuration diagram of a main part of a second embodiment.

FIG. 4 is a system configuration diagram of a semiconductor manufacturing system according to a third embodiment.

FIG. 5 is a system configuration diagram of an original plate cleaning inspection system according to a fourth embodiment.

FIG. 6 is a diagram showing a configuration of a conventional inspection device.

[Explanation of symbols]

 1 Light Source 2 Polygon Mirror 3 fθ Lens System 6 Scanning Area 7 Inspection Surface 8 Stage 9a, 9b Filter System 10a, 10b Condensing Optical System 11a, 11b Photoelectric Detector 13 Adder Circuit 14 Signal Processing System

Claims (1)

[Claims] 1. A scanning means for scanning a light beam on an inspection surface, at least two photoelectric detectors arranged spatially symmetrically with respect to a scanning region of the light beam, and two photoelectric detectors. And a means for generating a sum signal of detection signals from the surface inspection apparatus.