JPH0464245A - Electron microscope with optical microscope and appearance inspection device using it - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Industrial Field of Application] This invention relates to an electron microscope with an optical microscope and an appearance inspection device using this electron microscope, and is particularly applicable to the appearance inspection in the manufacturing process of semiconductor integrated circuit devices. The present invention relates to a technique that is effective when applied to an electron microscope with an optical microscope and an appearance inspection device using the same, which enables macroscopic positioning using a microscope and microscopic inspection using an electron microscope.

[Prior Art] Conventionally, in the manufacturing process of semiconductor integrated circuit devices,
As integrated circuit patterns become ever finer, electron microscopes, which enable higher resolution and finer observation, are being used in place of optical microscopes to evaluate manufacturing processes.

For example, Kyoritsu Shuppan Co., Ltd., published May 25, 1985, "Basics and Applications of Scanning Electron Microscope", especially Pi~F2
6 S E M (Scanning Electro
nMlscope: As described in the section on the principle and configuration of scanning electron microscope, the surface of a sample is scanned with an electron beam, and based on the intensity of the signal generated from the surface of the sample and the scanning position of the electron beam. There is a scanning electron microscope that displays a highly magnified image on a screen such as a cathode ray tube that is synchronized with the scanning of an electron beam, making it possible to observe a sample in detail.

It is used, for example, in the manufacturing process of semiconductor integrated circuit devices, and performs dimension measurements of integrated circuit patterns formed on semiconductor integrated circuits and visual inspections such as the presence or absence of defects.

[Problems to be Solved by the Invention] However, in the prior art as described above, although it is possible to perform microscopic observation by enlarging the area scanned by the electron beam at a high magnification, the area scanned by the electron beam In other words, no consideration is given to the range of positioning of the inspection portion of the sample, and problems arise in terms of macroscopic positioning of the sample.

For example, alignment is performed using a narrow field of view using high magnification, making it impossible to determine the entire image of the sample, which requires a large amount of time to align the inspection area, and at the same time, it is extremely difficult to detect the position of the inspection area. be.

Further, when measuring the dimensions of an integrated circuit pattern, it is necessary to input the coordinate data of the inspection point on the sample in advance, and this case also poses a problem in terms of time.

Therefore, conventional electron microscopes have the disadvantage that they cannot quickly perform a series of operations from alignment of the inspection location to detailed inspection.

Therefore, an object of the present invention is to enable macroscopic alignment using an optical microscope and microscopic inspection using an electron microscope, and to quickly perform a series of operations from alignment of inspection points to detailed inspection. An object of the present invention is to provide an optical microscope/electron microscope capable of performing the above-mentioned functions, and an appearance inspection device using the same.

The foregoing 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 the Problems] Among the inventions disclosed in this application, a brief overview of typical inventions is as follows.

That is, the electron microscope with optical microscope of the present invention includes: an electron optical system that focuses an electron beam emitted from an electron gun and irradiates the surface of a sample while scanning it two-dimensionally; and a sample stage on which the sample is placed. An electron microscope that is equipped with a detector that detects signals from the surface of a sample, and in which an electron optical system, a sample stage, and a detector are housed in a vacuum container that is maintained in a vacuum state. , a built-in optical microscope equipped with an optical system that irradiates the sample with light rays emitted from a light source.

In this case, the sample stage on which the sample is placed is aligned using an optical microscope, and the sample is inspected using an electron microscope by changing only the inclination of the sample stage.

Further, the appearance inspection apparatus of the present invention is equipped with an electron microscope with an optical microscope, the sample is a semiconductor substrate in the manufacturing process of a semiconductor integrated circuit device, and the integrated circuit pattern formed on the semiconductor substrate is inspected. .

[Function] According to the above-mentioned electron microscope with optical microscope, an optical microscope equipped with an optical system that irradiates the sample with light rays emitted from a light source is built in the same vacuum container as the electron microscope, so that the optical microscope is It is possible to perform macroscopic alignment of a predetermined inspection location on a sample using a microscope, and further microscopically inspect this aligned predetermined inspection location using an electron microscope. This makes it possible to quickly perform a series of operations from positioning the inspection location of the sample to detailed inspection.

In this case, inspection is performed by changing only the inclination of the sample stage after positioning the sample, which makes it possible to minimize the drive of the sample stage, thereby improving the accuracy of alignment and inspection. High positioning is possible.

Further, according to the above-mentioned appearance inspection apparatus, an electron microscope with an optical microscope that can perform macroscopic alignment of inspection points and microscopic inspection of the aligned inspection points is used for manufacturing semiconductor integrated circuit devices. By being used in the process, integrated circuit patterns formed on a semiconductor substrate can be easily inspected in a short time.

[Example 1] Fig. 1 is a schematic configuration diagram showing an appearance inspection apparatus using an electron microscope with an optical microscope, which is an embodiment of the present invention, and Fig. 2 shows a sample inspected by the appearance inspection apparatus of this embodiment. FIG.

First, the configuration of an appearance inspection apparatus using an electron microscope with an optical microscope according to this embodiment will be explained with reference to FIG.

The appearance inspection apparatus of this embodiment is an appearance inspection apparatus 2 used to inspect the appearance of an integrated circuit pattern on a semiconductor substrate (sample) 1, for example, in the manufacturing process of a semiconductor integrated circuit device, and is used to inspect predetermined inspection points on the semiconductor substrate 1. It consists of an electron microscope 3 that inspects the area, and an optical microscope 4 that aligns the inspection area.
is housed in a vacuum container 5 that is maintained in a vacuum state.

The electron microscope 3 includes an electron gun 6 that emits an electron beam, an electron optical system 7 that focuses the electron beam irradiated from the electron gun 6 and two-dimensionally scans the surface of a semiconductor substrate 10, and a semiconductor substrate 1.
It is composed of a sample stage 8 on which a specimen is placed, and a detector 9 that detects a signal from the surface of a semiconductor substrate 10, so that a portion of the semiconductor substrate 1 to be inspected can be microscopically inspected.

The electron optical system 7 includes a focusing lens 7a that controls the spot size of the electron beam that reaches the semiconductor substrate 1, and a deflection coil 7 that controls the incident position of the electron beam with respect to the semiconductor substrate 1.
b, and an objective lens 7C that controls the focal position of the electron beam with respect to the semiconductor substrate 1.

Furthermore, these electron optical systems 7 are connected to a signal control section via, for example, a current control section and a power supply section (not shown), and their respective operations are collectively controlled by this signal control section. A display section such as a cathode ray tube is connected to the signal control section, and a high-magnification enlarged image is displayed in synchronization with the scanning of the electron beam.

The sample stage 8 is connected to the optical axis control unit 10 via, for example, a drive motor (not shown), and its horizontal movement and inclination from the horizontal plane are controlled to be freely displaceable. Positioning and inspection are performed by moving and tilting the semiconductor substrate 1 placed on the sample stage 8, and at the same time, the semiconductor substrate 1 can be easily taken in and out.

The detector 9 detects the intensity of secondary electrons or reflected electrons from the semiconductor substrate 1 due to the irradiated electron beam, and converts it into an electrical signal.

The optical microscope 4 includes a light source 11 that emits a light beam, and this light source 1.
an optical system 12 that focuses and projects the light beam irradiated from 1;
The inspection position of the semiconductor substrate 1 placed on the sample stage 8 is macroscopically aligned.

The optical system 12 includes a focusing lens 12a that controls the spot size of the light beam reaching the semiconductor substrate 1, and an objective lens 12 that controls the focal position of the light beam with respect to the semiconductor substrate 1.
b, and an eyepiece lens 12c that magnifies and projects a real image of the semiconductor substrate 1.

The vacuum container 5 is connected to an exhaust system 13 such as an exhaust pump disposed below the sample stage 8, and the path of the electron beam is maintained in a high vacuum state.

Next, the operation of this embodiment will be explained.

First, the semiconductor substrate 1 as a sample is mounted on the sample stage 8 and housed inside the vacuum container 5 maintained in a vacuum state. Then, while controlling the horizontal movement and inclination of the sample stage 8 from the horizontal plane, the optical microscope 4 is used to inspect a predetermined inspection location of the semiconductor substrate 1, that is, a predetermined portion A shown in FIG. alignment to the integrated circuit pattern.

In this case, the appearance inspection group W1 of the conventional electron microscope 3 only
There is no need for positioning due to the narrow field of view due to high magnification as in 2, and the positioning of the inspection area can be done macroscopically, making positioning extremely easy without spending a lot of time on positioning. becomes.

Next, after the alignment is completed, only the inclination is controlled while maintaining the horizontal position of the sample stage 8, and the integrated circuit pattern in section A of the semiconductor substrate 1 is enlarged to a high magnification using the electron microscope 3. Conduct specific inspections.

The above operations are repeated for all the integrated circuit patterns shown in FIG. 2 that are the inspection points, and a series of visual inspections from alignment to inspection of the semiconductor substrate 1 in the manufacturing process of the semiconductor integrated circuit device are carried out.

Therefore, according to the appearance inspection apparatus 2 of this embodiment, the electron beam emitted from the electron gun 6 is focused inside the same vacuum container 5 maintained in a vacuum state, and the surface of the semiconductor substrate 10 as a sample is inspected. An electron optical system 7 that irradiates while scanning dimensionally, a sample stage 8 on which a semiconductor substrate 1 is placed, and a semiconductor substrate 1
In addition to a conventional electron microscope 3 equipped with a detector 9 that detects signals from the 0 surface, an optical microscope 4 equipped with an optical system 12 that irradiates the semiconductor substrate 1 with light rays emitted from the light s11 is built-in. By doing so, by performing macroscopic alignment of a predetermined inspection location on the semiconductor substrate 1 using the optical microscope 4, and further changing only the inclination of the sample stage 8,
Since the aligned predetermined inspection area can be microscopically inspected using the electron microscope 3, a series of operations from alignment of the inspection location of the semiconductor substrate 1 to detailed inspection can be performed quickly.

Embodiment 2 FIG. 3 is a schematic diagram showing the appearance inspection apparatus using an electron microscope with an optical microscope, which is another embodiment of the present invention.

As shown in FIG. 3, the visual inspection apparatus of this embodiment, as in the first embodiment, performs the following steps in the manufacturing process of semiconductor integrated circuit devices:
Visual inspection equipment used for visual inspection of integrated circuit patterns on semiconductor substrate (sample) 1! 22, it consists of an electron microscope 3 that inspects a predetermined inspection location on a semiconductor substrate 1, and an optical microscope 4 that aligns the inspection location, and these electron microscope 3 and optical microscope 4 are maintained in a vacuum state. It is built in a vacuum container 5.

The difference from Embodiment 1 is that the movement of the sample stage 8 is controlled by the optical coordinates of the optical microscope 4 and the optical coordinates of the electron microscope 3, and the positioning and the same inspection point are performed by moving in the horizontal direction. There are different points to be examined.

That is, in the visual inspection apparatus 2 of Example 2, the coordinate control section 14 and the coordinate storage section 15 are connected to the sample stage 8,
Only the movement of the sample stage 8 in the horizontal direction is controlled to be freely displaceable.

Therefore, according to the appearance inspection apparatus 2 of this embodiment, after aligning a predetermined inspection location of the semiconductor substrate 1 with the optical microscope 4 and storing the optical coordinates of the alignment in the coordinate storage section 15, the sample stage 8 is moved onto the optical axis of the electron microscope 3. Then, based on the stored optical coordinates of alignment, a predetermined inspection location on the semiconductor substrate 1 can be magnified at high magnification using the electron microscope 3 to perform microscopic inspection.

As a result, as in Example 1, from the macroscopic positioning of a predetermined inspection location on the semiconductor substrate l using the optical microscope 4, to the predetermined inspection position that has been aligned only by moving the sample stage 8 in the horizontal direction. Predetermined electron microscope 3
Even micro-inspections can be carried out quickly.

As above, the invention made by the present inventor has been specifically explained based on Examples 1 and 2. However, the present invention is not limited to the above embodiments, and can be modified in various ways without departing from the gist thereof. Needless to say, it is.

For example, regarding the appearance inspection apparatus 2 of Example 2, a case has been described in which both the electron microscope 3 and the optical microscope 4 are housed in a vacuum container 5 that is maintained in a vacuum state.
The optical microscope 4 does not necessarily need to be kept in a vacuum state, and it is sufficient that only the part shown by the two-dot chain line in FIG. 2 on the side of the electron microscope 3 is in a vacuum state.

Furthermore, the positional relationship and arrangement of the electron microscope 3 and the optical microscope 4 in the visual inspection apparatus 2 of Examples 1 and 2 are not limited to the structures shown in FIGS. 1 and 3.

In the above description, the invention made by the present inventor is mainly applied to the appearance inspection apparatus 2 for a semiconductor substrate 1 used in the manufacturing process of a semiconductor integrated circuit device, which is the field of application of the invention, but the present invention is not limited to this. The present invention can be widely applied to other visual inspection devices such as exposure masks, for example.

Further, the electron microscope with optical microscope is widely applicable to other fields such as medicine and biology, such as tissue and cell observation.

``Effects of the Invention'' Among the inventions disclosed in this application, the effects obtained by typical inventions are briefly explained below.

(1) An electron optical system that focuses the electron beam emitted from the electron gun and irradiates it while scanning the surface of the sample two-dimensionally, a sample stage on which the sample is placed, and an electron beam that collects signals from the surface of the sample. An electron microscope is equipped with a detector for detection, and is housed in a vacuum container in which an electron optical system, a sample stage, and a detector are kept in a vacuum state. By having a built-in optical microscope equipped with an optical system that irradiates the sample with the emitted light beam, the optical microscope can perform macroscopic alignment of a predetermined inspection point on the sample, and furthermore, the aligned predetermined inspection point can be can be microscopically inspected using an electron microscope, so a series of operations from positioning the inspection location of the sample to detailed inspection can be performed at six speeds.

(2) The sample stage on which the sample was placed was aligned using an optical microscope, and the sample was inspected using an electron microscope by changing only the inclination of the sample stage to align the sample. Since the drive of the sample stage can be kept to a minimum until later inspection, highly accurate positioning for alignment and inspection is possible.

(3) When an electron microscope with an optical microscope is used in the manufacturing process of semiconductor integrated circuit devices, it is possible to perform macroscopic alignment of inspection locations and microscopic inspection of the aligned inspection locations. Everything from alignment to inspection of an integrated circuit pattern formed on a semiconductor substrate can be easily performed in a short time.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing a visual inspection apparatus using an electron microscope with an optical microscope, which is Embodiment 1 of the present invention. FIG. 2 is a plan view showing a sample inspected by the visual inspection apparatus of this embodiment. FIG. 3 is a schematic configuration diagram showing an appearance inspection apparatus using an electron microscope with an optical microscope, which is a second embodiment of the present invention. 1... Semiconductor substrate (sample), 2... Appearance inspection device,
3... Electron microscope, 4... Optical microscope, 5... Vacuum container, 6... Electron gun, 7... Electron optical system, 7a.
... Focusing lens, 7b... Deflection coil, 7C... Objective lens, 8... Sample stage, 9... Detector, 1
0... Optical axis control unit, 11... Light source, 12... Optical system, 12a... Focusing lens, 12b... Objective lens, 12C... Eyepiece lens, 13... Exhaust system, 14
. . . Coordinate control unit, 15 . . . Coordinate storage unit. Diagram b: Electronic form diagram

Claims (1)

[Claims] 1. Focus the electron beam emitted from the electron gun to
an electron optical system that irradiates while scanning dimensionally; a sample stage on which the sample is placed; and a detector that detects a signal from the surface of the sample; An electron microscope is housed in a vacuum container maintained in a vacuum state, and an optical microscope equipped with an optical system for irradiating the sample with light rays emitted from a light source is built in the same vacuum container. Perform macroscopic alignment of a predetermined inspection location of the sample using an optical microscope,
The electron microscope with an optical microscope further comprises microscopically inspecting the aligned predetermined inspection location using the electron microscope. 2. Claim characterized in that the sample stage on which the sample is placed is aligned using the optical microscope, and the sample is inspected using the electron microscope by changing only the inclination of the sample stage. 1. The electron microscope with optical microscope described in 1. 3. An electron microscope with an optical microscope according to claim 1 or 2, wherein the sample is a semiconductor substrate in a manufacturing process of a semiconductor integrated circuit device, and an integrated circuit pattern formed on the semiconductor substrate is inspected. Appearance inspection equipment.