JPH02115752A - Foreign matter checking device - Google Patents

Abstract

PURPOSE:To detect foreign matters and to shorten the analysis time by detecting the existence of foreign matters by scattering of reflected light from the surface of a sample and detecting the fluorescence from foreign matters, which absorb exciting light, to analyze the composition of foreign matters. CONSTITUTION:A wafer 2 is placed on a sample stage 4, and first and second beam splitters 10a and 10b are removed from between an objective lens 9 and a foreign matter detecting part 11 by a switching driving part 12. In this state, the reflected light from the wafer 2 due to the laser light from a light emitting part 8 is made incident on the detecting part 11 through the lens 9 and is converted to an electric signal. When this signal is larger than a prescribed threshold, a foreign matter signal discriminating circuit 13 discriminates abnormality and foreign matter data is transmitted to a CPU 7 and is stored in a means 7a as a foreign matter distribution map. At the time of analysis of the composition of foreign matters, beam splitters 10a and 10b are inserted between the lens 9 and the detecting part 11 by the driving part 12. The CPU 7 outputs a command to a sample stage control part 6 based on the position of the designated foreign matter and the foreign matter distribution map stored in the means 7a, and analysis is performed.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an inspection technique for inspecting and analyzing foreign matter on the surface of a sample, for example, inspection of foreign matter on the surface of a semiconductor wafer (hereinafter referred to as wafer). , concerning techniques that are effective when applied to analysis.

[Conventional technology]

Regarding inspection techniques for foreign substances on the wafer surface in any manufacturing process of semiconductor devices, for example, Japanese Patent Application Laid-Open No. 55-941
There is a description in Publication No. 45.

The above-mentioned publication describes a technology that improves the reliability of foreign particle measurement by reducing the reflected light from normal integrated circuit backbones, which becomes noise compared to the reflected light from foreign particles deposited on the wafer surface. .

Incidentally, conventionally, a foreign object inspection for detecting the presence of foreign objects and a fluorescence analysis for analyzing the detected foreign objects have been performed in separate examination rooms.

Therefore, in order to perform fluorescence analysis after inspecting the wafer surface for foreign substances, the following procedure has been used.

In other words, after detecting the presence of foreign matter on the wafer surface through a foreign matter inspection and outputting the position and number of foreign matter as a foreign matter distribution map, the wafer is taken out of the inspection chamber of the foreign matter inspection equipment, and the sample is placed in the inspection chamber of the fluorescence analyzer. Place it on the table. Then, after a so-called field of view is performed to find a predetermined foreign substance on the surface of the mounted wafer based on the foreign substance distribution map, the wafer is irradiated with excitation light and the foreign substance is analyzed based on the fluorescence generated from the foreign substance.

[Problem to be solved by the invention]

By the way, in recent years, in semiconductor devices, elements,
However, as the miniaturization progresses, the defect rate of semiconductor devices due to foreign matter is increasing.

Furthermore, due to the accelerated pace of product development, there is not enough time to investigate the cause of the foreign matter and take measures to completely remove it.
It's becoming.

Therefore, in order to improve the yield and reliability of semiconductor devices, it is necessary to analyze foreign substances generated during the wafer processing process.
An important issue is how to quickly and reliably determine the cause of the problem.

However, the present inventors have discovered that the following problem exists in the conventional technique in which a foreign substance detection test and an analysis test thereof are performed in separate test rooms.

In other words, since the wafer is moved from the inspection chamber of the foreign object inspection device to the inspection chamber of the fluorescence analyzer, there is a possibility that other foreign objects may enter the wafer surface or the detected foreign objects may be moved. Therefore, it becomes difficult to analyze the foreign matter and determine its cause, and it also takes a lot of time.

The present invention has been made in view of the above-mentioned problems, and its purpose is to provide a technique that can shorten the time required from a foreign matter detection test to its analysis test.

Another object of the present invention is to provide a technique that can improve the reliability of analyzing foreign matter and determining its cause.

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

[Means to solve the problem]

A brief overview of typical inventions disclosed in this application is as follows.

That is, the invention according to claim 1 includes: a light emitting section that irradiates light onto the surface of a sample placed on a sample stage; and a foreign matter detection section that detects the presence of foreign matter by scattering the reflected light reflected from the surface of the sample. an excitation light emitting unit that irradiates the surface of the sample with excitation light to identify foreign matter; and a first inspection system that detects fluorescence emitted from the foreign matter that has absorbed the excitation light, and determines the composition of the foreign matter. This foreign matter inspection device includes a second inspection system consisting of a fluorescence detection section for analysis.

Further, the invention according to claim 2 provides the first inspection system and the second inspection system.
This foreign matter inspection apparatus is provided with a switching means that shares an optical path with the inspection system and selectively switches the optical path according to detection and analysis of the foreign matter.

[Effect]

According to the means described in claim 1 above, after detecting a foreign substance, it is possible to perform fluorescence analysis of the detected foreign substance without taking out a sample from the examination chamber.

Therefore, it is possible to quickly perform a foreign object detection test and its analysis test, and when moving to each test, for example, the intrusion of foreign objects is prevented, which improves the reliability of foreign object analysis and determination of its cause. can be done.

Moreover, according to the means described in claim 2, since the optical path is shared, the foreign matter inspection apparatus can be made compact.

〔Example〕

FIG. 1 is an explanatory diagram showing the main parts of a foreign matter inspection device that is an embodiment of the present invention.

The foreign matter inspection apparatus 1 of this embodiment shown in FIG. 1 is used for inspection to detect foreign matter present on the surface of a wafer 2 (sample) and analyze its composition in any manufacturing process of semiconductor devices.

At the top of the base 3, a sample stand 4 consisting of an X sample stand 4a and a Y sample stand 4b is installed. This X sample stage 4a and Y
The sample stage 4b is mechanically connected to a drive unit 5 such as a motor installed on its side so that it can be driven in directions orthogonal to each other, and the drive unit 5 is connected to the sample stage control unit 6. It is electrically connected to the central processing unit 7 via.

The central processing unit 7 controls the entire foreign matter inspection apparatus 1, and is composed of a storage section 7a, a control section (not shown), a calculation section, and the like.

The above-mentioned wafer 2 is removably placed on the upper part of the above-mentioned X sample stage 4a, and a first
A light emitting section 8.8 forming the inspection system is set.

The light emitting unit 8 is configured to be able to emit laser light, for example, and is set to be able to irradiate the wafer 2 with the laser light.

Immediately above the wafer 2, an objective lens 9, a first beam splitter 10a1 and a second beam splitter 10b1 which are switching means, and a foreign matter detection section 11 constituting a first inspection system are arranged along the optical axis of the objective lens 9. The settings are set in order from the bottom.

In this embodiment, the optical path is shared between the foreign matter detection test and the foreign matter analysis test. That is, during a foreign matter detection inspection, the first beam splitter 10a2 and the second
The beam splitter 10b is set to be removed from the opening between the objective lens 9 and the foreign object detection section 11 by a switching drive section 12 such as a motor. When analyzing foreign matter, the first beam splitter 10a1 and the second beam splitter 10b are inserted between the objective lens 9 and the foreign matter detection section 11 to switch the optical path. There is.

The switching unit 12 is electrically connected to the central processing unit 7, and its driving is controlled.

Note that switching of the optical path by the first beam splitter 10a and the second beam splitter 10b can also be done manually.

The foreign object detection section 11 is composed of, for example, a photomultiplier tube, and is electrically connected to the central processing unit 7 via a foreign object signal determination circuit 13.

An excitation light emitting section 14 constituting a second inspection system is set on the side of the first beam splitter lOa.

The excitation light emitting unit 14 includes, for example, an excitation light source 14a made of a mercury lamp that emits ultraviolet rays, a condenser lens 14b that condenses the excitation light emitted from the excitation light source 14a, and an excitation light that has passed through the condenser lens 14b. Of these, the filter 14C includes an excitation light selection filter 14C that selectively passes only the excitation light beam irradiated onto the wafer 2.

Further, on the side of the second beam splitter 10b, there is an excitation light absorption filter 15 that absorbs the excitation light reflected from the wafer 2 by irradiation with the excitation light and selectively passes only the fluorescence generated from the foreign matter. It is set.

A beam splitter 16 is set on the side of the excitation light absorption filter 15 so that the fluorescence that has passed through the excitation light absorption filter 15 is incident on the fluorescence detection section 17 .

The fluorescence detection section 17 includes a color detection section 17a that detects and amplifies incident fluorescence, and a color information analysis section 1117b that measures the wavelength of the detected fluorescence. It is electrically connected to the central processing unit 7.

Further, an eyepiece lens 1 is provided on the side of the beam splitter 16.
8 is set, so that foreign objects detected by the foreign object detection test can be visually observed.

In order to detect foreign matter on the surface of Uni-No 2 using the foreign matter inspection device 1 of this embodiment and analyze its composition, for example, the following procedure is performed.

First, the wafer 2 is placed on the upper part of the sample stage 4, and the switching drive unit 12 drives the first beam splitter 10a1.
Then, the second beam splitter 10b is removed from between the objective lens 9 and the foreign object detection section 11.

Then, the surface of the wafer 2 is irradiated with Raded light having a predetermined beam diameter from the light emitting unit 8, and the sample stage 4 is moved so that the laser light scans the wafer 2 from one end to the other.

The light reflected from the wafer 2 by the laser beam irradiation enters the foreign object detection section 11 via the objective lens 9, where it is converted into an electrical signal.

At this time, the presence of foreign matter is detected by the light scattered by the foreign matter on the surface of the wafer 2 out of the reflected light.

Incidentally, the converted electrical signal components also include electrical signal components due to normal patterns such as wiring and insulating films formed on the surface of the wafer 2.

Therefore, in order to remove the electrical signal component due to such a normal pattern, a foreign object signal determination circuit 13 is provided. In the foreign object signal determination circuit 13, a predetermined threshold voltage is set, and anything below that value is regarded as an electrical signal component of a normal pattern, and is removed.

The electrical signal determined to be caused by a foreign object is transmitted to the central processing unit 7 as data such as the number, size, and position (coordinates) of the foreign object, and is stored in the storage unit 7 as a foreign object distribution map.
In this way, the entire surface of the wafer 2 is inspected for detecting foreign substances.

Next, in order to analyze the composition of the detected foreign matter, first, with the wafer 2 placed on the sample stage 4, the switching drive section 12 is driven according to a command from the central processing unit 7, and the first beam splitter 10a is , and the second beam splitter lQb are automatically inserted between the objective lens 9 and the foreign object detection unit 1i1B11.

Then, when the inspection operator specifies the coordinates of a predetermined foreign object, the central processing unit 7 determines the position of the specified foreign object,
A command is transmitted to the sample stage control section 6 based on the foreign matter distribution map stored in the storage section 7a. The sample stage control unit 6 automatically moves the sample stage 4 in accordance with this command so that the designated foreign object is located below the objective lens 9. As a result, the inspection operator can visually observe the designated foreign object through the eyepiece lens 18.

After the field of view of such foreign matter is determined, the excitation light source 14
Excitation light is emitted from a. The emitted excitation light is incident on the excitation light selection filter 14C via the focusing lens 14b. Of the excitation light incident on the excitation light selection filter 14c, only the excitation light of a predetermined wavelength passes through the first beam splitter 10a and the objective lens 9 in this order, and is irradiated onto the surface of the wafer 2. Then, among the foreign substances on the surface of the wafer 2, foreign substances made of, for example, organic substances emit a specific fluorescence depending on the foreign substances. The generated fluorescence, together with the reflected light of the excitation light, passes through the objective lens 9 and the second beam splitter 10b in this order and enters the excitation light absorption filter 15. Here, the excitation light is removed and only the fluorescence generated from the foreign matter is incident on the fluorescence detection section 17 via the beam splitter 16.

The fluorescence incident on the fluorescence detection section 17 is converted into an electrical signal by the color detection section 17a, and its wavelength is measured by the color information analysis section 17b. And the measured wavelength data is
The data is transmitted to the memory ITa of the central processing unit 7 and stored therein. Then, the inspection operator stores this wavelength data in advance in the storage unit 7.
Comparing the wavelength data of fluorescence generated by various substances stored in a, foreign matter is analyzed and its cause is determined.

As described above, according to this embodiment, the following effects can be obtained.

(1) After the foreign matter detection test, it is possible to proceed to the foreign matter analysis test with the wafer 2 placed on the sample stage 4. In other words, it is possible to perform an integrated process from detection of foreign matter to analysis of foreign matter.

(2) According to (1) above, the time required from the foreign matter detection test to the foreign matter analysis test can be significantly shortened. especially,
Since the position of the foreign object is stored in the storage unit 7a, when moving from a foreign object detection test to a foreign object analysis test, a predetermined foreign object designated by the inspection operator can be brought into view in a short time.

(3) Unlike the conventional technology, with (1) above, when moving from a foreign object detection test to a foreign object analysis test, it is possible to prevent other foreign objects from entering or the detected foreign object from moving. This improves the reliability of foreign matter analysis and determination of its cause.

(4) According to (1) to (3) above, it is possible to support early development of semiconductor devices.

(5) According to (1) to (3) above, foreign matter removal measures are performed quickly and with high reliability, so that the reliability of the semiconductor device is improved.

(6) According to (5) above, the manufacturing yield of semiconductor devices is improved.

(7) Since the device for detecting foreign matter and the device for analyzing foreign matter, which were conventionally separated, are integrated, space can be saved. Furthermore, since the optical path is shared between the foreign matter detection test and the foreign matter analysis test, that is, the optical system is also shared, the foreign matter inspection apparatus 1 can be downsized.

As above, the invention made by the present inventor has been specifically explained based on Examples, but it should be noted that the present invention is not limited to the Examples and can be modified in various ways without departing from the gist thereof. Not even.

For example, the sample is not limited to a wafer, but may also be a mask that projects a predetermined pattern onto the wafer.

Furthermore, in the first embodiment, a case has been described in which the optical path is shared between the foreign matter detection test and the foreign matter analysis test, and the optical path is switched according to each test, but the present invention is not limited to this. For example, the optical paths may not be shared. In this case, add an objective lens above the wafer and
Of the two objective lenses, one is set to focus on the reflected light from the laser beam irradiation, and the other is set to focus on the fluorescence generated from the foreign object by the excitation light, and the light passing through the objective lens is set to focus on each detection unit. All you have to do is make it incident.

In the above explanation, the invention made by the present inventor is mainly applied to the field of application which is the background of the invention, which is the inspection of foreign substances on the surface of a wafer in the manufacturing process of semiconductor devices, but the invention is not limited to this and can be applied to various other applications. For example, it can be applied to foreign matter inspection in the manufacturing process of electronic devices that require microfabrication and are sensitive to foreign matter.

〔Effect of the invention〕

Among the inventions disclosed in this application, the effects obtained by typical inventions are briefly described below.

That is, the first inspection system includes a light emitting source that irradiates light onto the surface of a sample placed on a sample stage, and a foreign matter detection section that detects the presence of foreign matter by scattering the reflected light from the surface of the sample. and a second fluorescence detection section that includes an excitation light source that irradiates the surface of the sample with excitation light that identifies foreign matter, and a fluorescence detection section that detects fluorescence emitted from the foreign matter that has absorbed the excitation light and analyzes the composition of the foreign matter. By providing an inspection system, it is possible to analyze the detected foreign matter without removing the sample after detecting the foreign matter.

Therefore, the time required from foreign matter detection to foreign matter analysis can be significantly shortened.

Moreover, when moving from foreign object detection to foreign object analysis, for example, it prevents other foreign objects from entering or the detected foreign object from moving, which increases the reliability of foreign object analysis and cause determination. can be improved.

Further, the first inspection system and the second inspection system share an optical path, and a switching means for selectively switching the optical path according to the detection and analysis of the foreign substance is provided, so that the foreign substance inspection apparatus can be made small.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the main parts of a foreign matter inspection device that is an embodiment of the present invention. 1... Foreign matter inspection device, 2... Wafer (sample), 3...
...Base, 4...Sample stand, 4a...X sample stand, 4b
... Y sample stage, 5... Drive unit, 6... Sample stage control unit, 7... Central processing unit, 7a... Storage unit, 8...
- Light emitting part (first inspection system), 9...Objective lens, 10
a, 10b...beam splitter (switching means),
DESCRIPTION OF SYMBOLS 11... Foreign object detection part (1st inspection system), 12... Switching drive part, 13... Foreign object signal determination circuit, 14...
・Excitation light emitting unit (second inspection system), 14a...Excitation light source, 14b...Condensing lens, 14c...Excitation light selection filter, 15...Excitation light absorption filter, 16...
Beam splitter, 17... Fluorescence detection unit (second inspection system), 17a... Color detection unit, 17b... Color information analysis unit, 18... Eyepiece. Agent: Patent Attorney Katsuo Ogawa

Claims (1)

[Claims] 1. A light emitting section that irradiates light onto the surface of a sample placed on a sample stage, and a foreign matter detection section that detects the presence of foreign matter by scattering the reflected light from the surface of the sample. an excitation light emitting unit that irradiates the surface of the sample with excitation light that identifies foreign matter; and a fluorescence that detects fluorescence emitted from the foreign matter that has absorbed the excitation light and analyzes the composition of the foreign matter. A foreign matter inspection device comprising: a second inspection system comprising a detection section; 2. A claim characterized in that the first inspection system and the second inspection system share an optical path, and further include a switching means for selectively switching the optical path in accordance with the detection and analysis of the foreign object. Item 1. Foreign matter inspection device according to item 1.