JPS6015939A - Inspecting device for foreign matter - Google Patents

Abstract

PURPOSE:To detect the number and distributiin of foreign matters in advance, and to position each foreign matter appropriately by integrally mounting an observing optical system to a foreign-matter detecting optical system while fitting a foreign-matter coordinate memory section to a foreign-matter detecting circuit and operating and controlling a sample driving system. CONSTITUTION:A stage 3 is moved slowly in the theta-direction and the X-direction, and the surface is relatively scanned spirally by a foreign-matter detecting optical system 9 in a wafer 1. Irregular reflection beams are projected to an objective 12 through a polarizing plate 11, and imaged on a photoelectric converter 18 by a lens 16 through a relay lens 13 and half-mirrors 14, 15. Consequently, the presence of the foreign matter can be detected in a foreigh-matter detecting circuit 24 by an output from the photoelectric converter 18. Polar coordinates for foreign matters can also be detected by coordinate signals, and the coordinates and number of foreign matters can be detected, and are drawn by a foreign-matter districution-figure drawing instrument 26. On the other hand, the coordinates and number of foreign matters are memorized simultaneously by a coordinate memory section 25. Memorized coordinates are pulled out one by one, and a sample driving system 2 is operated on the basis of the memorized coordinates.

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to an apparatus for inspecting minute foreign particles existing on the surface of an object, and more particularly to a foreign particle inspection apparatus for inspecting and reducing foreign particles on the surface of a semiconductor wafer. It is.

[Background technology]

When foreign matter adheres to the surface of a semiconductor wafer during the manufacturing process of a semiconductor device, the pattern at the place where the foreign matter is attached becomes defective, resulting in a decrease in the yield of semiconductor devices. For this reason, a device that detects the number of foreign particles on a wafer using, for example, an optical method can be considered. However, such a device only detects the number of foreign particles, and cannot easily reduce or prevent foreign particles by investigating the cause of foreign particles, which is the original purpose of foreign particle inspection. For this reason, the inventor thought that simply detecting the number of foreign objects is insufficient. We also considered simply applying a microscope to the foreign object inspection device and attaching a device that magnifies a foreign object and observes it with the naked eye.

However, since the observer himself or herself had to look with his/her naked eye to see where the foreign object was, the inspection took a very long time and also caused a high degree of fatigue for the observer.

[Purpose of the invention]

The purpose of the present invention is to enable a foreign matter inspection device that can easily and efficiently inspect the number and distribution of foreign matter, as well as the material and shape of foreign matter, thereby achieving examination of the cause of foreign matter generation and prevention of foreign matter generation. Our goal is to provide the following.

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

[Summary of the invention]

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

That is, an observation optical system is integrally provided with the foreign object inspection optical system in an inspection apparatus including a foreign object detection optical system, a sample drive system, a foreign object detection circuit, etc., and a foreign object coordinate storage section is provided in the foreign object detection circuit. By configuring the sample drive system to be operationally controlled by this storage unit, the number and distribution of foreign objects can be detected first, and then each foreign object can be properly positioned with respect to the observation optical system. This allows for highly efficient grasping.

〔Example〕

The figure is an overall configuration diagram of an embodiment of the present invention, in which a semiconductor wafer 1 as a sample to be inspected is placed on a stage 3 movable in the X direction and the θ direction by a sample drive system 2. The sample drive system 2 is composed of a θ-direction feed motor 4 that directly rotates the stage 3 in the horizontal direction, and an X-direction feed motor 6 that moves an X-table 5 on which the θ-direction feed motor 4 is mounted. Motors 4 and 6 each have an encoder 7.
．． 8 is attached.

A foreign object detection optical system 9 is fixedly disposed directly above the stage 3, and an observation optical system 10 is integrally provided with this. The foreign object detection optical system 9 includes a polarizing plate 11, an objective lens 12, a relay lens 13, and a half mirror 14.
A 5% lens 16 and an aperture 17 are arranged on the optical axis to detect polarized light reflected from the surface of the wafer 1 and form an image on a photoelectric converter 18 provided at the uppermost position, which is detected as an electrical signal. Note that 19 is a foreign object illumination system for generating parallel light beams that illuminates the surface of the wafer 1'.

On the other hand, the observation optical system 10 has an illumination lamp 20 and a lens 21 provided opposite to the half mirror 14, and a mirror 22' and an eyepiece 23 provided opposite to the half mirror 15. The surface can be observed with the naked eye at high magnification.

The photoelectric converter 18 is connected to a foreign matter detection circuit 24, and each motor 4.6 (each encoder 7, i) of the sample drive system 2 is also connected to the foreign matter detection circuit 24. This foreign matter detection circuit 24 has a coordinate storage section 25 inside, and is connected to a foreign matter distribution map creator 26 or the like to the outside.
Ru.

According to the above four-part configuration, if the foreign object illumination system 19 illuminates the surface of the workpiece 1 and the θ direction feed motor 4° and the X direction feed motor 6 are operated, the stage 3 is moved in the θ direction, As a result, the surface of the wafer 1 is scanned in a spiral manner relative to the foreign object detection optical system 9. The foreign object illumination system 19 illuminates the surface of the wafer 1 with parallel light at a required angle, so when a foreign object exists on the wafer surface, the foreign object generates diffusely reflected light, which is reflected by the polarizing plate 1.
1 and enters the objective lens 12, further passes through the relay lens 13 and half mirrors 14 and 15, and is imaged by the lens 16 onto the photoelectric converter 18. As a result, the presence of foreign matter is detected by the foreign matter detection circuit 24 by the output of the photoelectric converter 18.
can be detected in

At this time, the θ direction feed motor 4. The polar coordinates of foreign objects can also be detected by the coordinate signal from the X-direction feed motor 6, and thereby the coordinates and number of foreign objects on the wafer can be detected. The distribution of these foreign substances is plotted by a foreign substance distribution map creator 26.

On the other hand, the coordinates and number of foreign objects are simultaneously stored in the coordinate storage section 25. After the scanning of the entire surface of the wafer 1 is completed, the stored coordinates are extracted one by one from the storage unit 25 and the sample drive system 2 is operated based on the coordinates. 12. In other words, the position of the wafer 1 is set again so as to correspond to the optical axis of the viewing optical system 100. Therefore, if the illumination lamp 20 is turned on in this state, the lamp light will partially illuminate the wafer surface through the lens 21, the half mirror 14, the relay lens 13, the objective lens 12, and the polarizing plate 11, and the reflected light will go in the opposite direction. After being reflected by the half mirror 15 and the mirror 22, it is brought into a state where it can be observed with the naked eye through the eyepiece lens 23.

This allows the operator to observe the shape, material, etc. of the foreign object with the naked eye. After the observation of one foreign object is completed, the next stored coordinate is retrieved, and the sample drive system 2 is operated again to automatically position the wafer 1 so that the next foreign object corresponds to the optical system. This eliminates the need for the observer to move the wafer at all, and eliminates the need for the conventional work of searching for foreign objects.

〔effect〕

(1) While the observation optical system is provided integrally with the foreign object detection optical system, the foreign object detection circuit is also provided with a coordinate storage section, so it is possible to not only detect the number and distribution of foreign objects, but also store the stored coordinates of foreign objects. Based on this, foreign objects can be observed easily and quickly, and the shape and material of foreign objects can be inspected with high efficiency.

(2) Observation of foreign objects is performed based on the memorized coordinates of the detected foreign objects, eliminating the need to scan the entire surface of the wafer using an optical system and observing foreign objects quickly and without leaking. This not only improves efficiency but also increases the magnification of the observation optical system, making it easier to inspect the shape, material, etc.

(3) Not only the number and distribution of foreign objects but also the shape and material of the foreign objects can be inspected, so the cause of foreign object generation can be accurately investigated and measures can be taken to prevent the generation of foreign objects.

Although the invention made by the present inventor has been specifically described above based on examples, it goes without saying that the present invention is not limited to the above-mentioned examples, and can be modified in various ways without departing from the gist thereof. Nor. For example, the specific configurations of the foreign object detection optical system and the observation optical system may be other configurations, the sample drive system may be configured to move the stage in the X and Y directions, or the optical system may be configured to move the stage in the X and Y directions. may be moved relative to the sample.

[Application field]

The above explanation has mainly been about the application of the invention made by the present inventor to foreign matter detection on semiconductor wafers, which is the background field of application, but the invention is not limited thereto. Applicable to technology, etc.

[Brief explanation of the drawing]

The figure is an overall configuration diagram of a foreign object detection device according to the present invention. DESCRIPTION OF SYMBOLS 1... Sample (wafer), 2... Sample drive system, 3 stages, 4... θ direction feed motor, 6... X direction feed motor, 9... Foreign object detection optical system, 10... - Observation optical system, 18... Photoelectric converter, 19... Foreign object illumination system,
24... Foreign object detection circuit, 25... Coordinate storage unit. ′−゛, agent: patent attorney Akio Takahashi. ξ

Claims (1)

[Scope of Claims] 1. A foreign matter detection optical system that detects foreign matter present on the surface of a sample, a sample drive system that scans the sample by moving the sample relative to the foreign matter detection optical system, and the foreign matter detection system. a foreign object detection circuit that detects the number and distribution of foreign objects based on signals from an optical system and a sample pivoting system; the foreign object detection optical system is provided with an observation optical system; 1. A foreign substance inspection apparatus, characterized in that a coordinate storage section is provided, and the sample drive system can be operated and controlled by the coordinate storage section. 2. The coordinate storage unit stores the coordinates of the detected foreign object. 2. The foreign object inspection apparatus according to claim 1, wherein the foreign object is set in a corresponding position in the observation optical system by the sample g movement system based on this memory.