JPS63135848A - Defect inspection instrument - Google Patents

Abstract

PURPOSE:To remove a defect other than those to be diagnosed automatically, by subtracting a defect distribution map prior to a diagnosis process of an object to be inspected from that after the end thereof. CONSTITUTION:A wafer 1 as object to be inspected is placed on a foreign matter inspection stage 4 and irradiated with laser 12 to detect scattered bean due to a foreign matter with a photo sensor 16. The resulting detection signal is processed with a CPU 23 through a foreign matter detection controller 17, a foreign matter distribution map prior to the diagnosis process is stored into a defect distribution map memory section 25 and, then, the wafer 1 is sent to the diagnosis process for a specified processing. Likewise, a foreign matter is detected from the wafer 1 via the diagnosis process and a foreign matter distribution map after the end of the diagnosis process is stored 25. Then, a computing section 26 subtracts a defect distribution map prior to the diagnosis process from that thereafter. This enables the selection of a defect along generated in the wafer 1 during the process, thereby automatically determining a distribution map of a foreign matter attached in the process.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a defect inspection technique, and in particular, to an automatic defect inspection device for foreign matter attached as a defect on the surface of an object to be inspected. , which is effective for use in inspecting foreign matter attached to the surface of wafers, etc.

(Prior art) In the manufacturing process of semiconductor devices, if a wafer has defects such as foreign matter adhering to it, the manufacturing yield, product quality, and reliability will deteriorate. Diagnosis is important whether online or offline.

Therefore, as a defect inspection device that performs wafer defect inspection non-destructively, the wafer as an object to be inspected is irradiated with light and the reflected light from the wafer is measured with a photo sensor, and based on the measurement results, it is determined whether the defect is normal or not. Various optical inspection apparatuses have been proposed that are configured to determine defect distribution by determining defective parts.

Examples of optical inspection techniques that describe optical inspection techniques include "Electronic Materials November 1984 Special Edition" published by Kogyo Research Association Co., Ltd., November 20, 1984, P213-P219.

Furthermore, in addition to detecting the distribution of foreign particles attached to the wafer, the size and composition of the foreign particles can be measured using a scanning electron R microscope or an X-ray microscope.
A foreign substance inspection device that uses a line microanalyzer for analysis has also been proposed (for example, Japanese Patent Application Laid-Open No. 60-2188
(See Publication No. 45).

[Point u while the invention is trying to solve the problem]

When inspecting wafers for defects using such defect inspection equipment, defects that existed on the wafer before the wafer went through the process to be diagnosed (or evaluated) are defects that are not subject to diagnosis. The inventor of the present invention has revealed that there is a problem in that it is difficult to manually remove this, although it is necessary to remove it.

An object of the present invention is to provide a defect inspection device that can automatically remove defects that are not subject to diagnosis.

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

[Means for solving problems]

A summary of typical inventions disclosed in this cabinet is as follows.

That is, a defect detection means for detecting defects in the object to be inspected, a storage section for storing a distribution map of defects in the object to be inspected based on the detection by the defect detection means, and a plurality of defect distribution maps based on the data stored in the storage section. The system is equipped with an arithmetic unit that verifies the information.

[Effect]

According to the above-mentioned means, the storage section inspects and stores the defect distribution before the inspected object undergoes the process to be diagnosed, and stores the defect distribution after the inspected object passes through the process to be diagnosed. It can be inspected and memorized. Then, by subtracting the defect distribution map of the inspected object before the process from the defect distribution map of the inspected object after the process, the arithmetic unit can select only the defects that occurred in the inspected object during the process.

Therefore, by analyzing the defect, it is possible to accurately diagnose the cause of the defect in the process.

Furthermore, the storage unit can store defect distribution maps for all inspected objects that have undergone the process to be diagnosed. Then, by integrating the defect distribution maps for all the objects to be inspected that have gone through the process to be diagnosed, the calculation section can highlight the tendency of defects occurring in the objects to be inspected during that process. Therefore, by analyzing this tendency, it is possible to accurately diagnose the cause of defects in the process.

[Embodiment 1] FIG. 1 is a scale diagram showing a 14-object inspection device which is an embodiment of the present invention, and FIG. 2 is an explanatory diagram for explaining its operation.

In this embodiment, this foreign matter inspection device is configured to analyze the distribution of foreign matter as a defect that has adhered to a wafer 1 as an object to be inspected during the process to be diagnosed, and the composition of the foreign matter, and is configured to analyze the composition of the foreign matter. It is equipped with an examination room 2 configured to be able to form a. One knee in examination room 2 (hereinafter referred to as the right side).

) is equipped with a preliminary chamber 3 so that wafers l can be taken in and out of the inspection chamber 2, and inside the inspection chamber 2 there is a foreign matter distribution inspection stage 4 for inspecting the distribution of foreign matter, and a foreign matter distribution inspection stage 4 for inspecting the distribution of foreign matter. Foreign matter analysis stages 5 are arranged on the right and on the left, respectively. A holder 6 for holding the wafer 1 is installed in the inspection chamber 2 and supported by a movable table 7. The moving table 7 is configured to be able to move the holder 6 in the X and Y directions, and the moving coordinates in the X and Y directions are input to the controller 11 by the encoder 8. The moving table 7 is a motor lO
The motor IO is configured to be moved between the distribution inspection stage 4 and the foreign matter analysis stage 5 by a feed screw device 9 driven by a controller 11.

A laser oscillator 12 is installed on the foreign material distribution stage 4 in the examination room 2.
This oscillator 12 emits a laser 1 as an inspection light to realize non-destructive inspection via a scanning mirror 13.
4 to scan and irradiate the wafer 1. Further, a photosensor 16 is installed in the foreign matter distribution stage 4 so as to face the laser irradiation point, and this photosensor 16 is configured to be able to detect the scattered light 15 of the laser 14 irradiated to the foreign matter on the wafer l. has been done. and,
The scanning mirror 13 is configured to be controlled by a foreign object inspection controller 17, and the photosensor 16 is configured to input its detection results to the controller 17.

On the foreign matter analysis stage 5 of the inspection room 2, an electron gun 18 of a scanning electron microscope (hereinafter referred to as SEX) is installed so that it can immediately shoot an electron beam at the foreign matter on the wafer l on the analysis stage 5. The electron gun 18 is configured to be side-controlled by an SEM controller 19. ? A secondary electron detector 20 is installed in one part of the tt child gun 18 so as to be able to detect secondary electrons emitted from a foreign object by irradiation with an electron beam, and this detector 20 sends the detection results to an SEM controller 19. It is configured so that it can be input to. Furthermore, an X-ray detector 21 is installed on the foreign matter analysis stage 5 to detect X-rays emitted from foreign matter by electron beam irradiation, and the detection results are input to an X-ray microanalyzer 22. It is configured as follows.

This foreign matter inspection device is equipped with a central processing unit (hereinafter referred to as CPtJ) 23 consisting of a computer etc.
The holder controller 11 and foreign object detection controller 17 are connected to the CPU 23. Also, C
Connected to the PU 23 are a console 24 for setting desired parameters, a memory 25 as a defect distribution map storage unit, and a calculation unit 26.
5 and the calculation unit 26 include a printer, a display device,
An output device 27 such as an external memory is connected. The memory 25 is configured to be able to store the positions of foreign objects on the wafer 1 sent from the foreign object detection controller 17 through the CPU 23 as a distribution map. Further, the calculation unit 26 is controlled by the CPU 23 so that it can collate the defect distribution map sent from the memory 24 through the CPU 23 and execute a desired calculation such as subtraction.

Next, the effect will be explained.

First, a wafer l that has not yet undergone a process to be diagnosed is transferred onto a holder 6 that has been moved from the preliminary chamber 3 to the foreign object detection stage 4 in the inspection N2.

Next, the laser 14 from the laser oscillation 012 hits the mirror 1.
The wafer 1 is moved in the X and Y directions by the moving stage 7 while being scanned by the wafer 3, so that the entire surface of the wafer 1 is irradiated regularly. At this time, if there is a foreign object on the wafer, the laser beam 14 irradiated onto the foreign object is scattered, so that scattered light 15 is detected by the photosensor 16. When a foreign object is detected, a detection signal is input from the photosensor 16 to the controller 17, and the output of the encoder 8 is latched into the memory 25. Based on this foreign matter position, the CPU 23 virtually creates a foreign matter distribution map 31 before passing through the process as shown in FIG. 2, and stores this in the memory 25.

The wafer 1 on which the foreign matter distribution map 31 before undergoing the process has been created in this way is taken out from the inspection room 1 via the preliminary room 3, sent to the process to be diagnosed, and subjected to predetermined processing. .

After that, the wafer 1 that has undergone the process to be diagnosed is placed in the preliminary room 3.
From there, it is transferred onto the holder 6 of the foreign object detection stage 4 in the examination room 2.

Subsequently, a foreign object is detected on the wafer 1 by the same operation as described above, and a foreign object distribution map 32 after the process is virtually created as shown in FIG. 2 (crow) based on the position of the foreign object. and stored in the memory 25.

When the inspection of the entire surface of the wafer 1 is completed, the holder 6 holding the wafer 1 is moved by the moving table 7 to a position directly below the SEM sub-gun 18 on the analysis stage 5.

Since the position coordinates of the detected foreign object are stored in the memory 25, the moving table 7 moves the holder 6 based on the data, and sequentially brings the foreign object at the position to be observed to face the irradiation point of the electron gun 18.

When the foreign object is irradiated with an electron beam, secondary electrons ejected from the foreign object are detected by a secondary electron detector 20, and emitted X-rays are detected by an X-ray detector 21. This detection result is based on the 32M controller 19 and
The data is input to the line microanalyzer 22, sent to external memory and peripheral equipment, and used for size analysis, composition analysis, etc. of foreign objects.

By the way, the foreign matter that was attached to the wafer 1 before going through the process to be diagnosed is not a foreign matter that was attached by the process to be diagnosed, so it may be removed from the diagnosis. Since analysis and compositional analysis require time and cost, analysis work on unimportant foreign substances obstructs truly necessary foreign substance analysis work.

Therefore, before going through the process to be diagnosed, the wafer 1
F! which was attached to It is desirable to omit analysis work on objects.

Therefore, in this embodiment, the CPU 23 causes the arithmetic unit 26 to perform the subtraction shown in FIG. 33 virtually, and its distribution diagram 33
By operating the movable stage 7 based on the above, only the foreign matter that has adhered during the process to be diagnosed is guided to the irradiation point of the electron gun 18, and an analysis test is performed. That is, the calculation unit 26 calculates m2
Foreign matter distribution diagram 3 after passing through the process shown in Figure (Hata)
By subtracting the distribution diagram 31 of foreign matter before passing through the process shown in BL from 2, the distribution diagram 33 of foreign matter deposited in the process shown in TC of the same figure can be calculated.

In this way, in this example, 5I! Since only the objects are sequentially opposed to the electronic IA 1B and subjected to the analysis work, the efficiency of the analysis work is improved.

According to the embodiment described above, the following effects can be obtained.

(By providing a memory that stores a distribution map of foreign particles on the wafer based on the detection of the 11X particle removal means and a calculation unit that collates multiple foreign particle distribution maps based on the data in the memory, the distribution of foreign particles after passing through the process can be By drawing a foreign matter distribution map before passing through the process from the diagram, the distribution map of foreign matter adhering in the process can be automatically obtained, so the tendency of foreign matter adhesion in the process can be accurately and quickly known, and the process Diagnosis or evaluation can be made more accurately and quickly.

(2) By obtaining a distribution map of foreign matter that has adhered during the process, it is possible to exclude from the distribution map the foreign matter that has adhered before passing through the process, which should be relatively diagnosed. When implementing this, it is possible to increase inspection efficiency and improve the accuracy of diagnosis or evaluation of the process.

[Embodiment 2] FIG. 3 is an explanatory diagram corresponding to FIG. 2 showing another embodiment of the present invention.

Embodiment 2 is applicable to determining the tendency of foreign matter to adhere in a process to be diagnosed, and the foreign matter test value shown in FIG. 1 is used in this embodiment as well. In this case, the memory 25 sequentially stores distribution maps 33A, 33B, etc. of foreign matter attached to a plurality of wafers that have passed through the same process, and a predetermined number or more distribution maps 33A, 33B, etc. , 33B...
・ is stored in the memory 25, the calculation unit 26 calculates all the distribution maps 33A, 3, as shown in the Kaya 3 diagram.
3B is added to the same figure (cumulative distribution diagram 34 shown in C1).
automatically.

By observing the distribution tendency of foreign matter in this cumulative distribution diagram 34, the tendency of occurrence of foreign matter in the process can be diagnosed or evaluated. In this case, since the foreign material distribution is automatically accumulated, diagnosis and evaluation are performed accurately without any accumulation errors, and diagnosis and evaluation can be performed quickly and online.
Evaluation is also possible and productivity can be increased.

Although the invention made by the present inventor has been specifically explained above based on Examples, it goes without saying that the present invention is not limited to the Examples and can be modified in various ways without departing from the gist thereof. Nor.

For example, after inspecting the distribution of foreign particles on a wafer, the XfiI! The device may be configured to determine the distribution of foreign matter.

The defects whose distribution is to be determined are not limited to foreign objects, but may also be defective defects, protrusion defects, dimensional error defects, etc. in visual inspection.

The defect detection means is not limited to optical means configured to irradiate the wafer with a laser and detect the scattered light, but also to irradiate the wafer with an rtIf8 particle beam such as an electron beam. Means configured to detect subparticles or waves, etc. may be used.

In the above explanation, the invention made by the present inventor has mainly been explained in the case where it is applied to the foreign matter inspection technology of wafers, which is the background application field, but the present invention is not limited to this, and the present invention is not limited to this. 8. The present invention can be applied to all defect inspection equipment in which at least a plurality of objects to be inspected pass through the same process.

〔Effect of the invention〕

A brief explanation of the effects obtained by typical inventions disclosed in this application is as follows.

By providing a storage unit that stores a distribution diagram of defects in the inspected object based on the detection by the foreign object detection means, and a calculation unit that collates multiple defect distribution diagrams based on the data in the storage unit, it is possible to prevent defects from occurring in the process. Since it is possible to automatically know the tendency of the process to occur, diagnosis or evaluation of the process can be performed quickly and its accuracy can be increased.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing a foreign matter inspection device according to an embodiment of the present invention, FIG. 2 is an explanatory diagram for explaining its operation, and FIG. 3 is a schematic diagram showing another embodiment of the present invention. FIG. 1...Wafer (object to be inspected), 2...Inspection room, 3...
・Preliminary room, 4... Foreign matter detection stage, 5... Foreign matter analysis stage, 6... Holder, 7... Moving table, 8...
・Linear encoder, L--・Feed screw device, lO・・
・Motor, 11...Holder controller, 12...
Laser oscillator, 13... Scanning mirror, 14... Laser, 15... Scattered light, 16... Photo sensor, 17.
...Foreign object detection controller, 18...SEM electronic 1L
19...SEM controller, 20...Secondary electron detector, 21...X-ray detector, 22...X-ray microanalyzer, 23...CPU. 24... Console, 25... Memory (defect distribution map storage unit), 26... Arithmetic unit, 27... Output device,
31... Foreign matter distribution diagram before passing through the process, 32... Foreign matter distribution diagram after passing through the process, 33.33A, 33B...
・Distribution diagram of foreign matter attached during the process, 34...Distribution diagram of foreign matter. Figure 1 """"",,I'4-fz@9;QTKJ
¥S 2 Figure ((Ll (b) (a-> (b) (C) (C)

Claims (1)

[Claims] 1. Defect detection means for detecting defects in an object to be inspected;
It is characterized by comprising a storage unit that stores a distribution map of defects in the inspected object based on the detection by the defect detection means, and a calculation unit that collates a plurality of defect distribution maps based on the data stored in the storage unit. Defect inspection equipment. 2. The defect inspection apparatus according to claim 1, wherein the calculation section is configured to calculate a difference between the defect distribution maps. 3. The defect inspection apparatus according to claim 1, wherein the arithmetic unit is configured to perform integration of the defect distribution map.