JPS61162737A - Checking method of performance for foreign matter inspection device - Google Patents

Abstract

PURPOSE:To check the performance of a foreign matter inspection device, by using a reference object to be inspected with the attached position of reference particles known exactly. CONSTITUTION:One sample 2 of objects to be inspected is extracted and the surface thereof is cleaned up. Then, a checkerboard-like scale 3 and numerals 4 indicating coordinates are drawn on the surface thereof by coating or printing. Then, reference particles 6... each with the size of 2mum are attached to desired parts dispersed over the entire surface of the sample two to three per part with a pipet or the like, for example, as shown by the shades in the drawing observing the surface of the sample 2 having the scale 3 and coordinate numerals 4 drawn thereon with a microscope. Then, the positions of the reference particles 6... are read out accurately to be recorded. To check the performance of a foreign matte inspector, a reference object 1 to be inspected is set on a stage thereof to detect the presence and the position of foreign matters on the surface of the object and the results of the detection are compared with the known data.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention is particularly applicable to detecting whether or not foreign matter is attached to the surface of an object to be inspected, such as a reticle or mask used to print a circuit pattern on a semiconductor wafer. A method for checking the performance of a foreign object inspection device used for inspections, etc., more specifically, a method for irradiating a laser beam onto the surface of an object to be inspected placed on a stage, and measuring the reflection and scattering state of the irradiated laser beam. The present invention relates to a method for checking the performance of a foreign matter inspection device configured to detect the presence or absence of foreign matter on the surface of an object to be inspected and its position.

[Background of the invention]

First, a conventional foreign matter inspection device of this type will be described using a reticle surface foreign matter inspection device as an example.

That is, as shown in FIG.
While moving linearly to the direction, and scanning in a reciprocating straight line within a predetermined range in the y direction perpendicular to the x direction,
The inspection surface of the reticle a was irradiated with a laser beam C from diagonally above at an appropriate angle θ (for example, 15 degrees) in the X direction, and the reflected and scattered state of the irradiated laser beam C was set on the upper side of the stage b. optical detector d,
By detecting d, it is possible to inspect whether there is a foreign substance on the surface of the reticle a and to detect its adhesion position.The inspection performance is approximately 2 μm.
Since it is required to be able to detect even the smallest foreign matter, when conducting actual inspections, it is necessary to adjust the laser beam irradiation system, for example! It is necessary to check the inspection performance in advance to see if the desired inspection performance cannot be achieved due to defects or the like.

Therefore, conventionally, the reticle a as the object to be inspected is
Extract one of these as a sample, attach 2 μm standard particles to several appropriate locations on the surface of the sample using a pipette, etc., and draw markings surrounding the attached locations with a marker to check the performance. A sample to which the standard particles have been attached is set in a foreign matter inspection device, and the presence or absence of foreign matter on its surface is detected as well as its position. A foreign matter distribution map is created on a CRT screen etc. from the detection results, and the foreign matter distribution map is created on a CRT screen etc. based on the detection results. By comparing the map with the marking state of the sample, it is determined whether the foreign object inspection device is correctly detecting foreign objects. The method of checking the performance of a foreign substance inspection device by means of this method was used brilliantly.

However, the above conventional method has the following drawbacks.

That is, during the performance check, the foreign matter detected by the foreign matter inspection device from the surface of the sample may include not only the standard particles but also other foreign matter attached to the sample. Since the location where the foreign matter was deposited was not known, the foreign matter was detected by the foreign matter inspection device.

It is unclear whether it is the standard particle itself or some other foreign substance attached to the vicinity of the standard particle, and therefore it is difficult to be sure that all the standard particles attached to the sample surface are being detected correctly. It was impossible to make a definitive judgment.

[Purpose of the invention]

The present invention has been made in view of the conventional situation, and its purpose is to accurately determine the correspondence between the nine actual positions of standard particles attached to the surface of a sample and the positions detected by a foreign object inspection device. By doing this, it is possible to determine whether all standard particles attached to the sample surface are correctly detected, even if foreign substances other than standard particles are attached to the sample surface. Furthermore, it is an object of the present invention to provide a method that can reliably and easily check the performance of a foreign substance inspection device.

[Summary of the invention]

In order to achieve the above object, a method for checking the performance of a foreign substance inspection device according to the present invention is to draw a checkerboard-like scale and numerical values indicating coordinates on the surface of one sample of the object to be inspected, and draw the scale and coordinate numerical values. By attaching standard particles to the surface of a sample with a microscope and confirming the adhesion position, a reference test object with known data regarding the adhesion position of the standard particles is prepared. The reference object to be inspected is set in a foreign object inspection device that is going to perform a performance check, and the foreign object is detected by detecting the presence and location of foreign objects on its surface, and comparing the detection results with the known data. A feature of this method is that it employs a method of determining whether or not the inspection device is correctly detecting foreign matter on the surface of the object to be inspected.

According to the present invention, the performance of the foreign matter inspection device is checked using a reference inspection object on which the adhesion position of the standard particles is known accurately, so even if the surface of the reference inspection object is Even if foreign matter other than particles is attached, it is ensured that all standard particles are loaded correctly by comparing the known position of the standard particle with the measured position of the detected foreign matter. Moreover, it can be easily determined, and as a result, the performance of the foreign object inspection device can be checked much more accurately than conventional methods. Moreover, since a checkerboard-shaped scale and numerical values indicating coordinates are drawn on the surface of the standard inspection object, standard particles can be attached to desired positions on the surface while viewing with the 1a microscope, Further, when accurately measuring the position H4, the work can be easily carried out, and the accuracy of reading the position can be made high.

[Embodiments of the invention]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A specific embodiment of a method for checking the performance of a foreign substance inspection apparatus according to the present invention will be described below with reference to the drawings (FIGS. 1 and 2).

FIG. 1 shows a jig used when carrying out the method of the present invention;
That is, it shows a plan view of a reference inspection object 1 configured by attaching standard particles to pre-known positions.

This reference inspection object 1 is manufactured by the following procedure.

That is, first, one sample 2 of the object to be inspected (in this example, a reticle made of a thin transparent glass plate whose front and back surfaces are polished to a highly flat surface) is extracted.

Both the front and back surfaces are cleaned with ultrapure water or ultrasonic waves to keep them as clean as possible from foreign matter.

Next, on the surface of the sample 2, a checkerboard-shaped scale 3 and numerical values 4 indicating the coordinates as shown are drawn by means such as coating or printing. , make the lines thinner (20 μm in this example) at small intervals (5 m intervals in this example), and make the lines thinner (20 μm in this example) at large intervals (20 μm in this example).
Make the lines thicker at every 5I11m interval (40μ in this example).
m), and a diagonal line 5°5 that divides the entire grid 3 into quarters is also drawn with a thin line (20 μm in this example).

Next, sample 2 with scale 3 and coordinate value 4 drawn.
While looking at the surface of the sample with a microscope, apply 2 to desired areas distributed over the entire surface of the sample, for example, as shown by diagonal lines in the figure.
A plurality of μm standard particles 6 (2~
Attach 3 pieces) at a time.

Then, while looking at the surface of sample 2 with a microscope,
As illustrated in FIG. 2, the positions of all the attached standard particles 6 (or only some of them if there are too many) are determined by referring to the grid-shaped scale 3 and the coordinate values 4 themselves, and While also using a sense of interpolation and division, read and record as accurately as possible. Note that the regular changes in line thickness and the presence of diagonal lines as described above greatly help in easily and accurately carrying out this reading operation.

By the way, if a transparent protective film (in this case, a pellicle film) (not shown) is applied to the surface of the sample 2 before or after reading the position of the standard particle 6, the standard inspection can be performed. There is an advantage that the object 1 can be used repeatedly, and there is also an advantage that inspection can be carried out more in line with the actual situation than with a normal reticle with a pellicle film.

Next, using the jig manufactured as described above, that is, the reference inspection object 1 on which the standard particles 6 are applied and the data regarding the adhesion positions are known,
A method for checking the performance of a foreign matter inspection device will be explained.

Although not shown in the figure, the foreign matter inspection device irradiates the surface of the inspection object placed on a stage with a laser beam and detects the reflection and scattering state of the irradiated laser beam. It is configured to detect the presence or absence of foreign matter on the surface of an object and its position.

First, the reference inspection object 1 is set on the stage of a foreign object inspection device whose performance is to be checked, and the presence or absence and position of foreign objects on its surface are detected, and then the detection results are combined with the known data. If the presence of foreign matter is detected at least at all positions corresponding to the known positions of the standard particles 6 attached in advance, then the foreign matter inspection device has successfully detected the foreign matter. If it is determined that there is a foreign substance and the presence of foreign substances is not detected at some or all of the positions of the standard particles 6 that must be detected, the foreign substance inspection device moves on to the actual foreign substance inspection work. It is determined that there is a problem with the inspection performance, the cause is investigated, and corrective measures are taken, such as adjusting the laser beam irradiation system.

〔Effect of the invention〕

As is clear from the detailed description above, according to the method for checking the performance of a foreign particle inspection device according to the present invention, a reference inspection object on which the adhesion position and position of standard particles are accurately known is manufactured in advance; Since the performance of the foreign matter inspection device is checked using the reference inspection object, even if foreign matter other than the standard particles is attached to the surface of the reference inspection object, the standard particle By comparing the known position and the measured position of the detected foreign object, it is possible to determine whether all the standard particles attached to the surface of the reference inspection object are correctly detected, and by extension, the performance of the foreign object inspection device. It is possible to reliably and easily determine whether the check can be performed reliably and easily, and therefore, the performance of the micro foreign object inspection apparatus can be checked much more accurately than with conventional methods. Furthermore, since a checkerboard-shaped scale and numerical values indicating the coordinates are drawn on the surface of the standard inspection object, it is possible to attach the standard particles to the desired position on the surface while viewing it with a microscope, and to When accurately reading a position, the work can be easily performed and the position reading accuracy can be increased.

[Brief explanation of the drawing]

Fig. 1 and the sub-figures show a specific example of the method for checking the performance of a foreign object inspection device according to the method of the present invention, and Fig. 1 is an overall plan view of a jig used when carrying out the method of the present invention; , FIG. 2 is a plan view showing an enlarged main part in order to explain the position reading procedure. Moreover, FIG. 3 is a perspective view of essential parts for explaining the background technology. 1... Standard inspection object, 2... Sample, 3...
Checkerboard-shaped scale, 4... Numerical values indicating coordinates, 5... Diagonal line, 6... Standard particle.

Claims (1)

[Claims] 1. By irradiating a laser beam onto the surface of an object to be inspected placed on a stage and detecting the state of reflection and scattering of the irradiated laser beam, foreign matter on the surface of the object to be inspected can be detected. A method of checking the performance of a foreign object inspection device configured to detect the presence and location of foreign objects, which involves drawing a checkerboard-shaped scale and numerical values indicating coordinates on the surface of one sample of the object to be inspected. By adhering standard particles to the surface of the sample with scales and coordinate values drawn on it using a microscope, and confirming the adhesion position,
A reference test object for which data regarding the adhesion position of standard particles is known is manufactured, and the reference test object is set in a foreign material inspection device for performance checking to determine the presence and location of minute foreign objects on its surface. let it be detected,
A foreign object inspection characterized in that it is determined whether or not the foreign object inspection device normally detects foreign objects on the surface of the object to be inspected by comparing the detection result with the known data. How to check equipment performance. 2. The method for checking the performance of a foreign substance inspection device according to claim 1, wherein when drawing the grid-like scale, the lines for each small interval are made thinner, and the lines for each large interval are made thicker. 3. The method for checking the performance of a foreign substance inspection device according to claim 1 or 2, wherein diagonal lines dividing the entire grid into quarters are also drawn on the grid-like scale. 4. A transparent protective film is coated on the surface of the reference test object before or after the step of reading the position of the standard particle during the production of the reference test object, or A method for checking the performance of a foreign matter inspection device according to any one of Item 3.