JPH067108B2 - Foreign substance inspection device performance check method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention particularly relates to whether or not foreign matter is attached to the surface of an object to be inspected such as a reticle or a mask used for printing a circuit pattern on a semiconductor wafer. The method of checking the performance of the foreign material inspection device used when performing the inspection, etc., more specifically, irradiates the surface of the inspection object placed on the stage with a laser beam and determines the reflection and scattering state of the irradiation laser beam. The present invention relates to a performance check method of a foreign substance inspection apparatus configured to detect the presence or absence of a foreign substance on the surface of the inspection object and the position thereof by detecting.

[Background of the Invention]

First, a conventional foreign matter inspection apparatus of this type will be described by taking a reticle surface foreign matter inspection apparatus as an example.

That is, as shown in FIG. 3, the stage b on which the reticle a as an inspection object is placed is moved in one direction (x direction).
While linearly moving to and reciprocating linearly scanning within a predetermined range in the y direction orthogonal to the x direction,
The inspection surface of the reticle a was irradiated with the laser beam c from an obliquely upper angle θ (for example, 15 degrees) in the x direction, and the reflection / scattering state of the irradiation laser beam c was set to the upper side of the stage b. Optical detector d,
By detecting the foreign matter on the surface of the reticle a and detecting the adhered position, the detection performance is about 2 μm.
It is required to be able to detect even extremely minute foreign matter, so when performing an actual inspection, the desired inspection performance cannot be achieved due to, for example, an adjustment error in the laser beam irradiation system. It is necessary to check the inspection performance beforehand whether or not it is not.

Therefore, conventionally, the reticle a as the inspection target is used.
Extract one of the samples as a sample, attach 2 μm standard particles to a suitable number of points on the surface of the sample with a pipette, etc., and draw a marking around the attached point with a marker to check the performance. The sample to which the standard particles are attached is set in the foreign matter inspection device to detect presence or absence of foreign matter and its position on the surface, and a foreign matter distribution map is created on a CRT screen or the like from the detection result, and the foreign matter distribution is calculated. The performance check method of the foreign matter inspection device is adopted by comparing the map and the marking state of the sample to determine whether or not the foreign matter inspection device normally detects the foreign matter.

However, the above conventional method has the following drawbacks.

That is, at the time of 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 the foreign matter adhering to the other standard particles. Since the positions where the particles are attached are generally known, it is unknown whether the particles detected by the particle inspection device are the standard particles themselves or other particles adhering to the standard particles. Therefore, it was not possible to make a reliable judgment as to whether or not all the standard particles attached to the surface of the sample were correctly detected.

[Object of the Invention]

The present invention has been made in view of such conventional circumstances, and its purpose is to accurately determine the correspondence between the actual position of the standard particles attached to the surface of the sample and the detection position by the foreign substance inspection device. By doing so, even if foreign matter other than the standard particles is attached to the surface of the sample, determination of whether or not all the standard particles attached to the surface of the sample are correctly detected, Consequently, it is another object of the present invention to provide a method capable of surely and easily checking the performance of the foreign matter inspection device.

[Outline of Invention]

In order to achieve the above object, a performance checking method for a foreign matter inspection apparatus according to the present invention irradiates a surface of an inspection object placed on a stage with a laser beam and detects a reflection / scattering state of the irradiation laser beam. A method for checking the performance of a foreign substance inspection device configured to detect the presence or absence of a foreign substance on the surface of the inspection target and its position by using a checkerboard on the surface of one sample of the inspection target. Draw a scale, draw a numerical value indicating the vertical and horizontal coordinates of the scale on the outside of the board, and draw a diagonal line that divides the scale on the scale.
The standard particles are attached only to the scales on which the diagonal lines are drawn while observing the surface of the sample on which the scales and coordinate values are drawn with a microscope, and by confirming the attachment position, the standard particles The reference inspection object for which the data regarding the adhesion position of the above is known is manufactured, and the reference inspection object is set in the foreign matter inspection device for which the performance is to be checked, and the presence or absence and the position of minute foreign matter on the surface are detected. By adopting means for comparing the detection result with the known data, it is determined whether or not the foreign matter inspection device normally detects the foreign matter on the surface of the inspection object. Is characterized by.

According to the present invention, the performance of the foreign substance inspection device is checked by using the reference inspection object whose standard particle adhesion position is accurately known. Even if foreign matter other than particles is attached, by comparing the known position of the standard particle with the measured position of the detected foreign matter, it is possible to ensure whether or not all standard particles are correctly detected. The determination can be made easily, and the performance of the foreign substance inspection device can be checked much more accurately than the conventional method. Moreover, the surface of the standard inspection object is designed to draw a numerical value indicating a grid-shaped scale and coordinates, so that the standard particles are attached to a desired position on the surface while observing with a microscope, or, When accurately reading the position, the work can be easily performed and the position reading accuracy can be made high.

Furthermore, a diagonal line that divides the whole grid-like graduation into quarters is drawn, and the standard particles are attached only to the graduations on which this diagonal is drawn, so the performance check becomes accurate and easy. Further, even if the data on the attachment position of the standard particles is not known, the performance can be checked to some extent. The diagonal lines show the relationship between the vertical and horizontal coordinates of the grid scale (for example, if the grid is entirely square, the vertical and horizontal coordinates are equal). ,
Standard particles are attached only to the scale with diagonal lines,
Since standard particles are not attached to other scales,
The performance can be checked to some extent by comparing the vertical coordinate and the horizontal coordinate when a foreign substance is detected.

[Embodiment of the Invention] A concrete embodiment of a performance checking method for a foreign matter 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 for carrying out the method of the present invention,
That is, a plan view of the reference inspection object 1 configured by attaching standard particles to known positions in advance is shown.

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

That is, first, one sample 2 to be inspected (in this example, a reticle made of a transparent glass thin plate whose front and back surfaces are polished to a highly flat surface) is extracted, and both front and back surfaces thereof are washed with ultrapure water or ultrasonic waves. In a clean state with as little foreign matter as possible.

Next, on the surface of the sample 2, a grid-like scale 3 as shown in the drawing and a numerical value 4 indicating coordinates are drawn by means such as coating or printing. When drawing the checkerboard scale 3, the lines at small intervals (5 mm intervals in this example) are thinned (20 μm in this example) and large intervals (25 mm in this example).
The line for each (mm interval) is thickened (40 μm in this example). In addition, diagonal lines 5 and 5 that divide the whole of the board-shaped scale 3
Also draw a thin line (20 μm in this example).

Next, sample 2 with the scale 3 and coordinate value 4 drawn.
While observing the surface of the sample with a microscope, as shown by, for example, the hatched area in the figure, the desired portion dispersed over the entire surface of the sample is
Plural standard particles of 6μm
3 pieces) each.

And after all, looking at the surface of sample 2 with a microscope,
The positions of all the adhered standard particles 6 (... may be part if too many) are referred to the grid-shaped scale 3 and the coordinate value 4 itself as illustrated in FIG. 2, and Read and record as accurately as possible while also using the sense of interpolation division. The regular change in the thickness of the line and the presence of the diagonal line described above greatly help in performing the reading operation easily and accurately.

By the way, if a transparent protective film (in this case, a pellicle film) (not shown) is attached to the surface of the sample 2 before or after the reading operation of the positions of the standard particles 6 ... There is an advantage that the object 1 can be repeatedly used many times, and an advantage that an ordinary pellicle film-attached reticle can be inspected more practically.

Next, by using the jig manufactured as described above, that is, the standard inspection object 1 to which the standard particles 6 ...
A method of checking the performance of the foreign matter inspection device will be described.

Although not shown, the foreign matter inspection apparatus irradiates the surface of the inspection object placed on the stage with a laser beam, and detects the reflection / scattering state of the irradiation laser beam to perform the inspection. It is configured to detect the presence or absence of foreign matter on the surface of the object and its position.

First, the reference inspection object 1 is set on the stage of the foreign substance inspection device whose performance is to be checked, and the presence or absence and the position of the foreign substance on the surface are detected, and then the detection result and the known data are detected. If it is detected that there is a foreign matter at least at all the positions corresponding to the known positions of the previously attached standard particles 6, ..., The foreign matter inspection apparatus normally detects the foreign matter. If the presence of foreign matter is not detected at some or all positions of the standard particles 6 that must be detected, the foreign matter inspection device It is determined that there is a problem with the inspection performance of (1), the cause thereof is investigated, and then good measures such as adjustment of the laser beam irradiation system are taken.

〔The invention's effect〕

As is clear from the above detailed description, according to the performance check method of the foreign matter inspection apparatus according to the present invention, the reference inspection object in which the attachment position of the standard particles is accurately known is manufactured in advance, and the reference Since the performance of the foreign matter inspection device is checked using the inspection object, even if foreign matter other than the standard particles is attached to the surface of the reference inspection object, the known value of the standard particle is known. By comparing the position with the measurement position of the detected foreign matter, it is determined whether all the standard particles adhered to the surface of the reference inspection object are correctly detected, and thus the performance of the foreign matter inspection device is checked. Can be reliably and easily determined, and therefore, the performance check of the microscopic foreign matter inspection device can be performed significantly more accurately than the conventional method.
Further, since the surface of the standard inspection object is drawn with a numerical value indicating a grid-like scale and coordinates, the standard particles are attached to desired positions on the surface while observing with a microscope, or When accurately reading the position, the work can be easily performed and the position reading accuracy can be made high.

Furthermore, a diagonal line that divides the whole grid-like graduation into quarters is drawn, and the standard particles are attached only to the graduations on which this diagonal is drawn, so the performance check becomes accurate and easy. Further, even if the data on the attachment position of the standard particles is not known, the performance can be checked to some extent. The diagonal lines show the relationship between the vertical and horizontal coordinates of the grid scale (for example, if the grid is entirely square, the vertical and horizontal coordinates are equal). ,
Standard particles are attached only to the scale with diagonal lines,
Since standard particles are not attached to other scales,
The performance can be checked to some extent by comparing the vertical coordinate and the horizontal coordinate when a foreign substance is detected.

[Brief description of drawings]

1 and 2 show a concrete example of a performance checking method for a foreign substance inspecting apparatus according to the method of the present invention, and FIG. 1 is an overall plan view of a jig used for carrying out the method of the present invention, and FIG. 2 is a plan view showing an enlarged main part for explaining a position reading procedure. Further, FIG. 3 is a perspective view of an essential part for explaining the background art. 1 ... Reference inspection object, 2 ... Sample, 3 ... Board-shaped scale, 4 ... Numerical value indicating coordinates, 5 ... Diagonal line, 6 ... Standard particle.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Minoru Taniguchi 2 Higashi-cho, Kichijoin-miya, Minami-ku, Kyoto-shi, Kyoto Prefecture Horiba Seisakusho Co., Ltd. (72) Inventor, Kazuhide Mukaihara 2 Higashi-cho, Kichijoin-miya, Minami-ku, Kyoto, Kyoto (56) References JP 62-11134 (JP, A) JP 62-206433 (JP, A) JP 59-98532 (JP, A) JP 58-97047 (JP, A) Japanese Patent Publication 4-50976 (JP, B2)

Claims (1)

[Claims] 1. A surface of an object to be inspected placed on a stage is irradiated with a laser beam, and a reflected / scattered state of the irradiation laser beam is detected to detect the presence or absence of foreign matter on the surface of the object to be inspected. A method for checking the performance of a foreign substance inspection device configured to detect a position, wherein a checkerboard scale is drawn on the surface of one sample of the inspection object, and the outside of the entire checkerboard scale Draw a numerical value showing the vertical and horizontal coordinates of the scale on the scale, draw a diagonal line to divide the whole scale on the scale, and observe the surface of the sample on which the scale and coordinate values are drawn with a microscope. While the standard particles are adhered only to the graduations on which the diagonal lines are drawn, and by confirming the adhered position, a reference inspection object for which data regarding the adhered position of the standard particles is known is manufactured. In advance, by setting the reference inspection object in the foreign substance inspection device that is going to perform performance check, detecting the presence or absence and the position of minute foreign substances on the surface, and comparing the detection result with the known data. A method for checking the performance of a foreign substance inspection device, comprising: determining whether or not the foreign substance inspection device normally detects a foreign substance on the surface of an inspection object.