JP2000268768A - Converged ion beam device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable sure evaluation and analyzation of a same fault by providing means of getting an image of an scanning electronic microscope at an observation point from an external device and of displaying the image on a screen. SOLUTION: A defect position in a wafer is detected by a defect detector and it is stored as a data file. Then, the wafer is moved to a scanning electronic microscope(SEM) for observation/element analysys of an SEM image. A specified defect 50 is selected from defect information and SEM observation is carried out. The observed SEM image is stored as image information. Thereafter, the wafer is moved to a focusing ion beam device and the stage is moved to the same position as that of the SEM observed defect. After the movement of the stage, a scanning ion microscope image is obtaied and displayed on a screen. An SIM image 101 and the SEM image 102 are displayed on an FIB control screen 100. Accordingly, the shape of defect 50 can be confirmed by either one of the images to thereby attain the object.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a focused ion beam apparatus for analyzing a defective portion formed on a semiconductor wafer with high accuracy or separating a specimen including the defective portion from the wafer with high accuracy.

[0002]

2. Description of the Related Art In recent years, in order to realize higher functionality and lower cost of semiconductor elements, a larger wafer area and a finer device structure have been made.

[0003] Regarding the enlargement of the area of a wafer, the current mainstream is shifting from 8 inches to 12 inches. As a result, the number of chips per wafer has greatly increased, and the price of one wafer has become extremely high. Further, for the purpose of improving the yield, the process includes a device for process monitoring. For example, a defect inspection device inspects a defect on a wafer at high speed, and stores a position and a size in a data file. By analyzing this data, the cleanliness of the process can be managed.

As an apparatus for analyzing not only the number and size of defects but also their shapes and constituent elements, a scanning electron microscope (Sc
There is an anning elwctron microscope (hereinafter abbreviated as SEM), which moves the stage to the address of the defect detected by the defect inspection device, and observes the SEM image of the defect (shape observation) and the characteristic X-ray emitted from the sample by electron beam irradiation. And perform elemental analysis. By clarifying the nature of defects, it has become possible to accurately determine the cause of a defect.

[0005] However, in many cases, defects are not only those exposed on the surface, but also include defect parts even inside the device. As a means for observing the defects, a focused ion beam (hereinafter abbreviated as FIB) is used. A processing observation method using the technique was devised. In this method, a rectangular area including a cross section to be viewed is subjected to FIB processing, and then the cross section formed by tilting the stage is observed. As a result, the cross-sectional structure can be easily evaluated.

[0006] Further, regarding the observation of the cross section, there is an apparatus in which the FIB column and the SEM column are combined, the cross section is formed by the FIB, and the cross section is observed by the SEM. In this case, elemental analysis becomes possible by detecting characteristic X-rays emitted from the cross section.

As described above, it has become relatively easy to analyze the shape and composition of defects. However, in recent years, the structure of devices has been further miniaturized, and cross-sectional image observation using FIB and
In some cases, the resolution of images observed by SEM was insufficient and the defect could not be evaluated properly.

Further, in the X-ray analysis using the SEM, the elemental analysis of a minute portion cannot be performed due to the spread of the electron beam in the sample, and it is becoming difficult to obtain appropriate information on the composition of the defect.

[0009] An ultra-high resolution observation image and elemental analysis of a minute area are obtained by a transmission electron microscope (Transmission Electron Microscop).
e: hereinafter abbreviated as TEM). When a TEM sample piece is separated from a wafer, a technique has been developed in which only the vicinity of a defective portion is separated from the wafer without breaking the wafer. This is described in JP-A-5-52721.

[0010]

As a flow of the defect analysis method, for example, a wafer is inserted into a defect inspection apparatus to obtain information on the size and number of defects and the defect position. Next, the wafer is inserted into the visual inspection SEM, a desired defect is selected from the previously obtained defect information, and the stage is moved to an address corresponding to the desired defect to perform a defect shape and elemental analysis.

When information on a cross section of a defect is required, the wafer is inserted into the FIB apparatus, and a cross section of the defect is observed. If more detailed information (defect TEM image or local elemental analysis information) is needed, the sample including the defect is separated from the wafer by the FIB sampling function, and thin-wall processing is performed by the FIB to convert the sample into a TEM. Insert and observe.

In the above, when sampling a defective portion from a wafer by the FIB, the sample stage is moved by using the in-wafer address information of the defect obtained by the defect inspection apparatus, and the desired defect is moved to the optical axis of the FIB. Sampling. At this time, a problem is the accuracy of the address. Generally, the absolute accuracy of address information of a defect inspection apparatus is several tens μm.

Therefore, whether the defect sampled by the FIB device is a desired defect detected by the defect inspection device. In addition, it may be difficult to confirm whether or not the defect has been subjected to shape analysis or elemental analysis by SEM. This is particularly problematic when the defects are adjacent within the address accuracy described above.

An object of the present invention is to provide a visual inspection apparatus, SEM,
An object of the present invention is to provide an environment in which the same defect can be reliably evaluated and analyzed by FIB.

[0015]

A means for displaying an SEM image is provided in a FIB apparatus, and a scanning ion microscope (ScanningIo) is provided.
The n Microscope (hereinafter abbreviated as SIM) image and the SEM image can be compared on the same screen, so that it can be confirmed that both evaluate the same defect site. The visual inspection SEM is provided with software that sequentially learns with the observation of a defect and sequentially improves the matching accuracy between the sent defect position information and the actual stage address. Therefore, S
The address accuracy of the defect observed by the EM is higher than the address accuracy detected by the defect inspection device.

Therefore, by using a sample stage having the same specifications in the SEM and the FIB, and controlling the stage position based on information (software corrected) from the SEM instead of information from the defect inspection apparatus using the sample address of the FIB, Mutual accuracy of defect positions between devices is further improved.

[0017]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of a first embodiment of the present invention.

FIB device 1, SEM 2, visual inspection device 1
1 are connected via a network 10 and can transfer data mutually. The defect inspection apparatus 11 has a defect position information detecting means 12, which can detect information such as a position and a size of a defect in a wafer and can make it a data file.

The SEM 13 has a defect position information acquiring means 14
This has a function of transferring and storing defect information from the defect inspection apparatus 11. Defect position stage moving means 15
Has a function of moving the stage to the position of a specific defect based on the obtained defect position information. The SEM image acquiring means has a function of acquiring an SEM image of a defect and storing the acquired SEM image as image data. FIB 1 has external SEM information acquisition means 2,
It has a function of transferring the image data stored by the SEM to the FIB device. The external SEM image display means displays the transferred S
It has a function of displaying EM image information on the screen of the FIB device. The defect position information acquiring means 4 has a function of transferring and storing defect information. The defect position stage moving means has a function of moving the stage to a position of a specific defect based on the obtained defect position information.

The sampling means 6 has a function of separating the area containing the defect from the wafer. The separated specimen is thin-walled (TE) using the FIB device or an external FIB device.
M sample processing), and the processed sample can be analyzed by TEM. FIG. 2 shows a procedure for analyzing a specific defect in a wafer.

First, a wafer defect inspection 40 is performed. A defect inspection device detects a defect position, a size, and the like in the wafer, and stores them as a data file.

Next, SEM image observation / elemental analysis 41 is performed. The wafer is moved to the SEM, a specific defect is extracted from the defect information obtained by the defect inspection apparatus, the stage is moved to the defect position, and SEM observation is performed. Observed SEM
The image is stored as image information.

When elemental analysis is required, an electron beam is intensively applied to a defect site, and characteristic X-rays emitted from the defect are detected to perform elemental analysis.

Next, the wafer is moved to the FIB apparatus,
The stage is moved to the same position as the defect observed in M. After the movement, a SIM image is acquired and displayed on the screen. Also, an SEM image of the defect is displayed on the same screen. This is the external S
This is made possible by the EM image information acquisition means 2 and the external SEM image display means 3.

FIG. 3 shows an example in which the SIM image and the SEM image are simultaneously displayed on the control screen.

SEM image 102 on FIB control screen 100
And the SIM image 101 are displayed. The shape of the defect 50 can be confirmed in both images, and it can be confirmed that the same defect is analyzed.

In the FIB processing, a processing area 103 is formed on the SIM image.
Is set, and FIB is locally irradiated to this area. The control screen 100 has a defect information window 104 in which a defect number 105 and a defect position are displayed. This F
Observation of sample and setting of processing area using IB control screen /
Processing is performed, and sampling is performed by the sampling method described in JP-A-5-52721.

After sampling, thin wall processing (TEM sample processing 43) is performed in the FIB apparatus. The obtained sample piece is TE
M, and perform TEM image observation / elemental analysis 44.

By the above series of flows, a TEM observation of a specific defect in a wafer can be performed with high accuracy.

FIG. 4 is a block diagram of the second embodiment. The difference from the first embodiment is that the SEM 13 is provided with a defect position information correcting means 17 and the FIB 1 is provided with a means for acquiring the corrected defect position information.

The accuracy of the defect position information obtained by the defect inspection apparatus is generally low, and it may be difficult to determine which defect is adjacent when the defects are adjacent. For this reason, the SEM has a function of correcting defect position information, and a mechanism has been built in which learning is performed as a plurality of defects are observed, and the position accuracy is sequentially improved.

By using a stage having the same specifications for the SEM and the FIB and performing the FIB stage movement based on the defect position information corrected by the SEM, it was possible to locate the defect with higher precision.

[0034]

According to the present invention, a fine defect in a wafer can be surely analyzed by SEM / TEM.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a first embodiment of the present invention.

FIG. 2 is a flowchart showing a procedure according to the first embodiment of the present invention.

FIG. 3 is an FIB control screen used in the embodiment of the present invention.

FIG. 4 is a configuration diagram showing a second embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... FIB apparatus, 2 ... External SEM image information acquisition means, 3
... External SEM image display means, 4 ... Defect position information acquisition means, 5 ... Defect position stage moving means, 6 ... Ampling means, 7 ... Corrected defect position information acquisition means, 10 ... Network, 11 ... Defect inspection device, 12 ... Defect position information detection means, 13 ... SEM, 14 ... Defect position information acquisition means,
15: Defect position stage moving means, 16: SEM image acquisition means, 17: Defect position information correction means, 40: Defect inspection, 41: SEM image observation / elemental analysis, 42: Sampling, 43: TEM sample processing, 44: TEM Image observation / elemental analysis, 50: defect, 100: FIB control screen, 101:
SIM image, 102: SEM image, 103: processing area, 10
4 ... Defect information display window, 105 ... Defect number, 10
6: defect position X, 107: defect position Y

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01L 21/66 H01L 21/66 NF term (Reference) 4M106 AA01 BA02 BA03 BA20 CA38 CA39 CA41 CA42 CA43 CA45 CA46 CA50 CA51 DA15 DB05 DH08 DH24 DH60 DJ23 5C001 AA03 AA05 CC04 5C033 FF04 UU03 UU04 5C034 DD06 DD09

Claims (3)

[Claims] 1. A sample moving means for moving a wafer sample at least in X, Y and tilt directions, a focused ion beam processing and observing means for irradiating a focused ion beam on the sample for observation or processing, and an observation point in the sample. FIB including specific area
In a focused ion beam apparatus provided with means for separating (sampling) from the sample using processing, means for acquiring observation point address information in the sample from an external device, and a sample for driving a sample stage based on the address information transportation,
A focused ion beam apparatus comprising: means for acquiring a scanning electron microscope image of the observation point from an external device; and means for displaying the scanning electron microscope image on a screen. 2. The focused ion beam apparatus according to claim 1, wherein the SEM image and the scanning ion microscope image are displayed on the same screen. 3. The focused ion beam device according to claim 1, wherein the address information is information generated from a scanning electron microscope connected to the focused ion beam device.