JPH0555332A - Foreign matter inspecting device - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To provide a foreign matter inspection apparatus capable of improving the detection sensitivity of foreign matter adhering to a wafer and performing the foreign matter inspection under optimum conditions suitable for the wafer. A foreign matter inspection device for a wafer on which a circuit pattern is formed, a laser 2 for irradiating the wafer 1 with a laser beam, and a sensor 3 for detecting reflected light reflected from the wafer 1 by the laser beam irradiation, A drive unit 4 that changes the installation angle of the laser 2 and moves the laser 2 in the XY axis directions.
And a data processing unit 5 for processing the detection data of the sensor 3. Then, after the laser 2 is automatically set to the optimum installation angle θ by the drive unit 4, the laser light emitted from the laser 2 to the wafer 1 is detected by the sensor 3 as the reflected light from the foreign matter 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a foreign matter inspection device,
In particular, the present invention relates to a technique effectively applied to a foreign matter inspection apparatus capable of inspecting a foreign matter on a patterned semiconductor wafer (hereinafter, simply referred to as a wafer) on which a circuit pattern is formed.

[0002]

2. Description of the Related Art Conventionally, as an inspection apparatus for detecting foreign matter on a wafer, for example, a laser for irradiating the wafer with laser light and a sensor for detecting reflected light reflected from the wafer by the irradiation of the laser light are used. There is an inspection device that is equipped with a sensor and can detect foreign matter attached to a wafer. In addition, there are some lasers equipped with a plurality of lasers set at a certain angle so that they can be used for wafers with different circuit patterns. These lasers are switched according to the height of the circuit pattern, Optimal inspection is possible.

As a technique similar to this, for example, “Journal of Semiconductor World” published by Press Journal Co., Ltd., May 20, 1988.
1988.6 ”P125-P129.

[0004]

However, in the above-mentioned prior art, although the angles of the lasers are different, the angles are fixed, which causes a problem in versatility. For example, there is a problem in that it cannot be applied to a wafer on which a circuit pattern with a high level difference that cannot detect foreign matter is formed by using any laser.

On the other hand, on the sensor side, there is a problem that the pattern edge cannot be detected even if the detection sensitivity of the sensor is maximized, or conversely, the sensitivity can be increased when the threshold voltage is the minimum. ..

Further, the detection sensitivity when detecting foreign matter on the wafer is regulated by the height of the step of the circuit pattern and the incident angle of the laser. Therefore, the optimum detection is achieved by optimally adjusting the incident angle of the laser. It is possible to obtain sensitivity.

That is, when detecting a foreign substance on the wafer from the relative relationship between the laser and the sensor, the reflection due to the circuit pattern is separated from the reflection due to the foreign substance, and if the reflected light from the pattern is large, the sensitivity of the sensor is reduced. Therefore, there is a problem in that the detection sensitivity of foreign matter is also reduced at the same time.

Therefore, an object of the present invention is to improve the detection sensitivity of foreign matter adhering to an object to be inspected, to enable detection of a wafer on which a circuit pattern with a high step is formed, and to detect a wafer with a low pattern step. It is an object of the present invention to provide a foreign matter inspection device that can improve sensitivity and perform inspection with higher accuracy.

Another object of the present invention is to provide a foreign matter inspection apparatus capable of performing a foreign matter inspection under optimum conditions suitable for an object to be inspected.

The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

[0011]

Among the inventions disclosed in the present application, a brief description will be given to the outline of typical ones.
It is as follows.

That is, the foreign matter inspection apparatus of the present invention comprises an illuminating means for illuminating the object to be inspected with illumination light, and a detecting means for detecting reflected light reflected from the object to be inspected by the illumination light irradiation. A foreign matter inspection device for detecting foreign matter adhered to an object to be inspected, comprising a drive mechanism which is connected to an illumination means so that an installation angle of the illumination means can be varied within a predetermined angle range.

In this case, when changing the installation angle of the illuminating means, an arbitrary position of the object to be inspected is designated, and the installation angle of the illuminating means is set based on the detection intensity of the designated position. It is a thing.

Further, the inspected object is a patterned semiconductor wafer having a circuit pattern formed thereon, and the illuminating means is a laser.

[0015]

According to the foreign matter inspection apparatus described above, the drive mechanism is connected to the illuminating means, so that the incident angle of the irradiation light of the illuminating means can be set to an arbitrary angle. As a result, the reflected light from the inspection object can be minimized, and the detection sensitivity of foreign matter adhering to the inspection object can be increased.

Further, the installation angle of the illumination means is set on the basis of the detection intensity at an arbitrary position of the inspection object,
The incident angle of the illumination light can be set to the optimum detection condition of the inspection object. As a result, the illuminating means is automatically adjusted to an angle at which reflected light does not affect foreign matter inspection, and is also suitable for foreign matter inspection of inspected objects that differ depending on product type and process, such as circuit patterns with high steps and wafers with low pattern steps. Applicable.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic block diagram showing a foreign matter inspection apparatus according to an embodiment of the present invention.

First, the structure of the foreign matter inspection apparatus of this embodiment will be described with reference to FIG.

The foreign matter inspection apparatus of this embodiment is, for example, a foreign matter inspection apparatus for a wafer on which a circuit pattern is formed, and a laser (illumination means) 2 for irradiating a wafer (inspection object) 1 with laser light. A sensor (detection means) 3 for detecting the reflected light reflected from the wafer 1 by the irradiation of the laser light, and a drive unit (drive mechanism) 4 for varying the installation angle of the laser 2 and moving the laser 2 in the XY axis directions. , And a data processing unit 5 that processes the detection data of the sensor 3.

Then, the installation angle θ of the laser 2 is automatically set with high precision within a range of, for example, 0 ° to 90 ° by the driving unit 4 which is composed of, for example, a pulse motor and an encoder, and the laser 2 irradiates the wafer 1. The laser light thus generated is converted into an electric quantity corresponding to the quantity of the reflected light by a sensor 3 having a built-in photo-maru, for example, and is further outputted through a data processing section 5 in a format such as MAP or a foreign matter distribution table. ing.

Next, the operation of this embodiment will be described.

First, the wafer 1 to be inspected is placed, and a laser beam is emitted from the laser 2 by designating an arbitrary position on the wafer 1, for example, a position of a circuit pattern. Then, the reflected light is detected by the sensor 3, and the laser 2 is automatically set to the installation angle θ of the optimum detection condition according to the detection intensity.

For example, the incident angle of the laser 2 is automatically changed so as to detect a point where the detection intensity is below (or above) a certain level. In this case, the level of reflected light intensity is below (or above) a certain level. ), The installation angle θ of the laser 2 is fixed.

Next, after fixing the installation angle θ of the laser 2, the laser light is irradiated to a predetermined portion of the wafer 1 while maintaining this angle, and the light reflected by the circuit pattern and the light reflected by the foreign matter 6 are separated from each other. 3 to detect. Then, the laser beam 2 is moved in the XY axis directions by the driving unit 4, and the inspection is sequentially repeated while displacing the irradiation position of the laser light,
The inspection of the foreign matter 6 is performed on the entire surface of the wafer 1.

Further, after the inspection of one wafer 1 is completed, another wafer is set and the foreign matter inspection is similarly performed on all the wafers. In this case, with respect to wafers having different circuit patterns or wafers having different lots / processes, the laser 2 is set again to the optimum installation angle θ and then the inspection is performed.

When outputting the inspection result of the wafer 1 to the outside, the detection data of the sensor 3 is processed through the data processing unit 5 and is printed out by, for example, a printer or the like so that the MAP of the foreign matter 6 or the distribution table is displayed. It can be output in the form.

Therefore, according to the foreign matter inspection apparatus of the present embodiment, the incident angle of the laser beam from the laser 2 can be adjusted by connecting the laser 2 to the drive unit 4 capable of varying the installation angle θ. The reflected light from the can be minimized, and the detection sensitivity of the foreign matter 6 can be increased.

When the step or shape of the circuit pattern varies depending on the type and process, the angle of the reflected light does not affect the inspection of the foreign matter 6 in advance, so that the foreign matter inspection of the wafer 1 can be performed under optimum conditions. You can do it below.

Although the invention made by the present inventor has been specifically described based on the embodiments, the present invention is not limited to the embodiments and various modifications can be made without departing from the scope of the invention. Needless to say.

For example, in the foreign matter inspection apparatus of the present embodiment, the case where the installation angle of the laser 2 is changed by the drive unit 4 has been described, but the present invention is not limited to the above embodiment, and the laser 2 is used, for example. Is also fixed and the incident angle of the laser beam with respect to the wafer 1 can be changed by using a mirror or the like.

Further, the drive unit 4 may be provided with an indicator or the like for displaying the installation angle of the laser 2 so that the installation angle of the laser 2 in the previous inspection can be reflected when the optimum condition angle for the next foreign matter inspection is set. It is possible.

In the above description, the invention mainly made by the present inventor is applied to the foreign matter inspection apparatus used for the wafer 1 on which the circuit pattern is formed, which is the field of use of the invention. However, the invention is not limited to this. However, the present invention is also widely applicable to foreign matter inspection devices for other inspected objects such as inspected objects having a single layer or a multilayer film without a circuit pattern.

[0033]

The effects obtained by the typical ones of the inventions disclosed in the present application will be briefly described as follows.
It is as follows.

That is, by connecting to the illuminating means a drive mechanism in which the installation angle of the illuminating means can be varied within a predetermined angle range, and by setting the incident angle of the irradiation light by the illuminating means by this drive mechanism. Since the reflected light from the object to be inspected can be minimized, it is possible to improve the detection sensitivity of foreign matter.

Further, when the installation angle of the illumination means is changed, an arbitrary position of the object to be inspected is designated, the installation angle of the illumination means is set based on the detection intensity of the designated position, and the incident angle of the illumination light is set. Is set to the optimum detection condition for the inspected object, the lighting unit can be automatically adjusted to an angle at which the reflected light does not affect the foreign object inspection. Applicable.

As a result, it is possible to obtain a foreign matter inspection apparatus capable of performing highly accurate foreign matter inspection on a wafer having a circuit pattern with a high step and a wafer with a low pattern step, especially on a wafer on which a circuit pattern is formed.

[Brief description of drawings]

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

[Explanation of symbols]

 1 wafer (inspection object) 2 laser (illumination means) 3 sensor (detection means) 4 drive unit (drive mechanism) 5 data processing unit 6 foreign matter

Claims (3)

[Claims] 1. An illuminating means for irradiating an object to be inspected with illuminating light, and a detecting means for detecting reflected light reflected from the object to be inspected by the irradiation of the illuminating light, and attached to the object to be inspected. In the foreign matter inspection device for detecting foreign matter, a drive mechanism is connected to the illuminating means so that the installation angle of the illuminating means can be varied within a predetermined angle range, and the incident angle of the irradiation light by the illuminating means is connected by the drive mechanism. Is set to an arbitrary angle, a foreign matter inspection apparatus. 2. When varying the installation angle of the illumination means, an arbitrary position of the inspection object is designated, and the installation angle of the illumination means is set based on the detection intensity of the designated position,
The foreign matter inspection apparatus according to claim 1, wherein an incident angle of the illumination light is set to an optimum detection condition of the inspection object. 3. The foreign matter inspection apparatus according to claim 1, wherein the inspection object is a patterned semiconductor wafer on which a circuit pattern is formed, and the illumination means is a laser.