JPH0515219B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a foreign matter inspection device for detecting foreign matter on the surface of a semiconductor wafer or the like.

More specifically, the present invention relates to a foreign matter inspection device that detects foreign matter on the surface of a semiconductor wafer and outputs a map of the detected foreign matter on a display screen or printed paper.

[Conventional technology]

Conventionally, in a foreign matter inspection apparatus for inspecting foreign matter on the surface of a semiconductor wafer, a foreign matter map is displayed on a display screen or printed out, in which detected foreign matter is plotted by superimposing the contour pattern of the semiconductor wafer.

[Problem to be solved]

The surface of a semiconductor wafer is divided into a plurality of chip areas, and the area where foreign matter management is truly necessary is the area (effective area) excluding the peripheral area of each chip area.

In other words, foreign matter that exists around the periphery of a semiconductor wafer or chip area is not important; what is truly important is to understand the distribution, amount, size, etc. of foreign matter within the effective area of each chip area. to know whether each chip area is available or not.

However, although it is possible to understand the distribution of foreign particles on the entire semiconductor wafer surface from the foreign particle map obtained by conventional foreign particle inspection equipment,
It is not possible to easily determine whether each chip area is usable or not.

[Purpose of the invention]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a foreign matter inspection apparatus that solves such problems and outputs a foreign matter map that allows easy determination of the availability of each chip area on the surface of a semiconductor wafer.

[Means for solving problems]

The present invention provides a foreign matter inspection device that detects foreign matter on a surface to be inspected and outputs a map of the detected foreign matter on a display screen or printed paper, and outputs a pattern indicating divisions within the surface to be inspected on the display screen or printed paper. means for extracting only the foreign matter within the effective area of the section from among the detected foreign matter as valid foreign matter; and means for outputting the pattern of the effective foreign matter on a display screen or printed paper superimposed on the pattern of the section. By providing this, the above-mentioned problems can be solved.

[Effect]

Because of this configuration, for example, if the surface of a semiconductor wafer is the surface to be inspected and the division is a chip area, only the foreign object pattern within the effective area of each chip area is created as a foreign object map that overlaps the pattern of the chip area. is obtained.

According to such a foreign matter map, it is possible to grasp the distribution of foreign matter that causes a real problem in each chip region on a semiconductor wafer, corresponding to each chip region. Therefore,
It can be easily determined whether each chip area is available or not.

〔Example〕

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic diagram of a foreign matter inspection apparatus for semiconductor wafers according to the present invention.

In this figure, numeral 10 is an observation section for optically observing the surface of a semiconductor wafer. To explain this observation unit 10, 12 is a semiconductor wafer 1
This is a moving stage mechanism for moving 4.
16 and 18 are S-polarized laser oscillators for obliquely irradiating the surface of the semiconductor wafer 14 with S-polarized laser beams.

The semiconductor wafer 1 is moved by the moving stage mechanism 12.
4 in the X and Y directions, the surface of the semiconductor wafer 14 is XY scanned by the S-polarized laser beam. Moving stage mechanism 1
2 has a built-in position encoder for detecting the scanning position, and the position information is output to the outside.

20 is an objective lens, 22 is an S polarization cut filter, and 24 is a photomultiplier. Scattered light from the semiconductor wafer surface in a substantially vertical direction enters an S-polarization cut filter 22 via an objective lens 20, and only its P-polarization component is extracted and enters a photomultiplier 24, where it is converted into an electrical signal. Ru.

When a foreign object is present at the scanning point, the surface of the foreign object has minute irregularities, so the P-polarized light component of the scattered light increases; however, when there is no foreign object, the P-polarized light component of the scattered light is sufficiently small. Incidentally, the scattered light in the vertical direction also increases at the edge portions of the pattern, but since the edge portions are smooth when viewed microscopically, the P-polarized light component of the scattered light is sufficiently small.

As a result, the presence or absence of foreign matter can be determined from the output signal level of the photomultiplier 24 by distinguishing it from the pattern on the surface of the semiconductor wafer.

Furthermore, since the output signal level of the photomultiplier 24 is proportional to the average level of the P light component of the scattered light within its field of view, the output signal level of the photomultiplier 24 is
The size of the foreign object can also be determined from the output level 4.

26 is a level comparison circuit for making such a determination. This level comparison circuit 26 compares the level of the output signal of the photomultiplier 24 with a plurality of threshold values corresponding to the size of the foreign object, and outputs foreign object data corresponding to the size.

Reference numeral 28 denotes a drive control circuit that controls the drive motor of the moving stage 12 and the like.

30 is a processing control section. This processing control section 30
1 has a configuration in which a microprocessor 32, a memory 34, and an interface circuit 38 are interconnected by a bus 46.

The foreign substance data output from the level comparison circuit 26 is input to the processing control section 30 through the interface circuit 38.

A control command to the drive control circuit 28 is output from the processing control section 30 via the interface circuit 38. Also, this interface circuit 3
Position information is input from the moving stage mechanism 12 via 8.

48 is a keyboard, and this keyboard 48
Information can be input to the processing control unit 30 via the interface circuit 38 from the interface circuit 38 .

50 is a display unit for displaying foreign matter maps and the like. 52 is its controller, which is connected to the bus 46. This controller 52 has a built-in image memory 54 for storing display data on a display screen in the form of a bitmap. This image memory 54 is accessible by the microprocessor 32, and the controller 52 converts the data stored in the image memory 54 into a video signal and sends it to the display unit 50 for display on its display screen.

FIG. 2 is a schematic flowchart showing the flow of processing by the processing control section 30. Hereinafter, the operation of this foreign matter inspection device will be explained with reference to this flowchart.

When a specific key on the keyboard 48 is pressed while the semiconductor wafer 14 is positioned and fixed on the moving stage mechanism 12, the microprocessor 32 of the processing control section 30 performs processing and control operations as shown in FIG. Start execution of the program (stored in memory 34).

Note that size information and chip arrangement definition information of the semiconductor wafer 14 to be inspected are input in advance from the keyboard 48 to the processing control unit 30, and from the input information, scan end coordinates, outline coordinates of each chip area,
The contour coordinates of the effective area of each chip area are calculated and stored in the coordinate table 34b on the memory 34.

First, initialization is performed such as clearing the foreign object table 34a on the memory 34 and clearing the image memory 52 (step 100).

In step 102, the moving stage mechanism 1
A control command is sent to the drive control circuit 28 to move the scanner 2 to the scanning start position.

When positioning to this scanning start position is completed,
At step 104, a scan start command is sent to drive control circuit 28. As a result, the moving stage mechanism 12 moves in the X direction and the Y direction, and XY scanning of the semiconductor wafer surface by the S-polarized laser beam begins.

After the start of scanning, the determination data by the level comparison circuit 26 and the scanning position information sent from the moving stage mechanism 12 are sampled at regular intervals and held in the internal register of the microprocessor 32 (step 106).

The microprocessor 32 determines whether the sampled determination data is a code indicating a foreign object of any size (step 108).

If it is a foreign object code, in step 110, the sampled scan position information (coordinates of the scan position) is compared with the outline coordinates of the effective area of each chip area stored in the coordinate table 34b, and the scan position is determined. It is checked whether the chip is within the valid area of any chip area.

If it is within the valid area, in step 112, the judgment data (code indicating the foreign object size) and
The scanning position information is paired and stored in the foreign object table 34a.
, and the process returns to step 106.

If it is determined in step 108 that the code is not a foreign object, or if it is determined in step 110 that the code is not a valid chip area, the process proceeds to step 114. In this step, the scan position information is compared with the scan end coordinates stored in the coordinate table 34b, and it is determined whether the scan has ended. If not finished, step 1
The process returns to step 06, but if the process is finished, the process proceeds to step 116. In this way, among the detected foreign substances, only those within the effective area of the chip area are extracted, and their information is written into the foreign substance table 34a. In other words, foreign matter detected outside the effective area of the chip area, that is, foreign matter detected at the periphery of the chip area and the periphery of the semiconductor wafer, is masked.
It is not registered in the foreign matter table 34a.

At step 116, a scan stop command is sent to the drive control circuit 28, and the moving stage mechanism 12 is stopped.

In the next step 118, the microprocessor 32 transfers the contour pattern of the semiconductor wafer and the contour pattern of each chip area to the image memory 52 according to the coordinate information stored in the coordinate table 34b.
Generate above.

When this process is completed, plotting of the foreign matter is started. First, in step 120, the foreign object determination codes registered in the foreign object table 34a are read into the microprocessor 32 starting from the first registered foreign object, and a pattern corresponding to the determination code (foreign object size) is generated. , are held in internal registers of the microprocessor 32.

In the next step 122, the position information of the foreign object is read from the foreign object table 34a into the microprocessor 32, and the data in the area of the image memory 54 corresponding to the position of the foreign object is read into the microprocessor 34. Then, the logical sum data of the data and the foreign object pattern is stored in the image memory 54.
written to the same area.

When the same process is executed up to the last foreign object registered in the foreign object table 34a, step 12 is executed.
4, it is determined that the process is complete, and the process ends.

In this way, a foreign object map as shown in FIG. 3 is displayed on the screen of the display unit 50. In this figure, 60 is an outline pattern of a semiconductor wafer, 62 is an outline pattern of a chip area, and 64 is a foreign matter pattern.

According to such a foreign matter map, it is possible to grasp the distribution and size of foreign matter within the effective area corresponding to each chip area, and easily judge whether each chip area is usable or not.

Although one embodiment has been described above, the present invention is not limited thereto, and can be implemented with various modifications within the scope of the invention.

For example, in the embodiment described above, the foreign object map is displayed on the display screen, but it may be printed out.

Although the outline pattern of the semiconductor wafer is also displayed in the above embodiment, it is not necessarily necessary to display it.

In the embodiment described above, each time foreign object determination data is read, foreign objects within the chip effective area are extracted (other foreign objects are masked). However, after unconditionally registering detected foreign objects in the foreign object table, effective foreign object extraction processing can also be performed all at once.

In the above embodiment, the surface of the semiconductor wafer is
Although XY scanning was performed, helical scanning may also be performed.

Furthermore, in the above embodiments, it has been explained that there is no positional deviation of the semiconductor wafer in the What is necessary is to perform the correction process.

Further, the present invention can be similarly applied to an apparatus for inspecting foreign matter on the surface of an object to be inspected other than a semiconductor wafer.

〔Effect of the invention〕

As explained above, the present invention provides a foreign matter inspection device that detects foreign matter on a surface to be inspected and outputs a map of the detected foreign matter on a display screen or printed paper. means for outputting on a screen or printed paper; and means for extracting only foreign matter within the effective area of the section from among the detected foreign matter as valid foreign matter;
Since the device is equipped with a means for outputting the effective foreign material pattern on a display screen or printed paper overlapping with the pattern of the section, from the foreign material map, for example, the distribution of foreign materials within the effective area of each chip area of a semiconductor wafer can be determined. It is possible to realize a foreign matter inspection device that solves the problems of conventional devices, such as being able to easily determine whether each chip area can be used or not.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a foreign matter inspection apparatus according to the present invention, FIG. 2 is a schematic flowchart for explaining processing and control of a processing control section, and FIG. 3 is an explanatory diagram of a foreign matter map. DESCRIPTION OF SYMBOLS 10... Observation part, 14... Semiconductor wafer, 12... Moving stage mechanism, 16, 18... S polarization laser oscillator, 24... Photomultiplier, 26... Level comparison circuit, 30... Processing control part, 32... Microprocessor, 34 ...Memory, 34a...Foreign object map, 3
4b...Coordinate table, 50...Display unit, 52...Controller, 54...Image memory.

Claims (1)

[Scope of Claims] 1. In a foreign matter inspection device that detects foreign matter on a surface to be inspected and outputs a map of the detected foreign matter on a display screen or printed paper, a pattern indicating a division within the surface to be inspected is displayed on the display screen or printed out. means for outputting on paper, means for extracting only foreign objects within the effective area of a section from among the detected foreign objects as effective foreign objects, and outputting a pattern of the effective foreign object on a display screen or printed paper by overlapping it with the pattern of the section. A foreign matter inspection device characterized by having a means for causing 2. The foreign matter inspection apparatus according to claim 1, wherein the surface to be inspected is the surface of a wafer, and the division is a chip area.