KR20070010619A - Wafer inspection equipment - Google Patents

Abstract

A wafer inspection apparatus for detecting a defect of a wafer has a first precision and a first inspection unit for detecting a defect of a wafer and a second inspection unit for detecting a defect of the wafer with a second precision higher than the first precision. It is provided. A stage supports the wafer while detecting defects in the first inspection unit and the second inspection unit. The driving unit has a second reference position of the second inspection unit wherein the wafer is positioned at a first reference position of the first inspection unit when the primary detection is performed, and the wafer is substantially equal to the first reference position when the secondary detection is performed. The stage is horizontally moved to be located at.

Description

Apparatus for inspecting a wafer}

1 is a block diagram for explaining a wafer inspection apparatus according to an embodiment of the present invention.

FIG. 2 is a configuration diagram for describing the first inspection unit of FIG. 1.

3 is a configuration diagram for describing the second inspection unit of FIG. 2.

Explanation of symbols on the main parts of the drawings

100: first inspection unit 200: second inspection unit

300: stage 400: drive unit

W: Wafer

The present invention relates to a wafer inspection apparatus for detecting a defect of a wafer, and more particularly, to a wafer inspection apparatus for detecting a defect of a bare wafer on which a pattern is not formed.

In general, a semiconductor device includes a Fab process for forming an electrical circuit including electrical elements on a silicon wafer used as a semiconductor wafer, and an EDS (electrical) for inspecting electrical characteristics of the semiconductor devices formed in the fab process. die sorting) and a package assembly process for encapsulating and individualizing the semiconductor devices with an epoxy resin.

The fab process includes a deposition process for forming a film on a wafer, a chemical mechanical polishing process for planarizing the film, a photolithography process for forming a photoresist pattern on the film, and the photoresist pattern using the photoresist pattern. An etching process for forming the film into a pattern having electrical characteristics, an ion implantation process for implanting specific ions into a predetermined region of the wafer, a cleaning process for removing impurities on the wafer, and a process for forming the film or pattern Inspection process for inspecting the surface;

The inspection process also includes inspection of a wafer without a pattern formed on the wafer, that is, a bare wafer.

In general, as the design rules decrease and the degree of integration of memory semiconductor devices increases, there is an urgent need for improvement in detection sensitivity in particle monitoring. As the size of particles that may have a fatal effect on the electrical characteristics of the device is reduced along with the decrease in cell size, an apparatus for detecting particles having a size of 30 nm or less has been developed and used.

However, according to the prior art, defects in the bare wafer are detected using an optical device. The optical device simply determines whether there is a defect. Therefore, it is not possible to confirm in what process the defect is caused by what cause. In addition, only defects with a large size are detected, and small defects are not detected. And it is difficult to check whether the detected defect is a real defect or noise.

Meanwhile, the wafer defect detected by the optical device may be reviewed by an electron scanning microscope (SEM) device using electrons. The stages of the optical device and the SEM device do not match. The defects detected by the optical device may not be found by the SEM device.

An object of the present invention for solving the above problems is to provide a wafer inspection apparatus with improved defect detection capability of the wafer.

According to a preferred embodiment of the present invention for achieving the object of the present invention, the wafer inspection apparatus includes a first inspection unit for detecting the defect of the wafer first and a second inspection for detecting the defect of the wafer secondary With a unit. A stage supports the wafer while detecting defects in the first inspection unit and the second inspection unit. The driving unit has a second reference position of the second inspection unit wherein the wafer is positioned at the first reference position of the first inspection unit when the primary detection is performed, and the wafer is substantially equal to the first reference position when the secondary detection is performed. The stage is horizontally moved to be located at.

The stage supports the wafer to have the same wafer coordinates while detecting defects in the first inspection unit and the second inspection unit. The driving unit horizontally moves the stage such that the wafer is positioned under the first inspection unit during the first detection, and the wafer is positioned under the second inspection unit during the second detection.

The first inspection unit has a first precision, detects a defect using light, and the second inspection unit has a second precision higher than the first precision, and detects a defect using an electron beam.

In the wafer inspection apparatus according to the present invention configured as described above, since the first inspection unit and the second inspection unit use the same coordinates, the defect detected by the first inspection unit may be redetected and analyzed through the second inspection unit. . Therefore, the defect detection capability of the wafer can be improved.

Hereinafter, a wafer inspection apparatus according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram for explaining a wafer inspection apparatus according to an embodiment of the present invention.

Referring to FIG. 1, the wafer inspection apparatus 1000 includes a first inspection unit 100, a second inspection unit 200, a stage 300, and a driving unit 400.

The first inspection unit 100 detects a defect of the wafer W using optical. The first inspection unit 100 has a first precision.

FIG. 2 is a configuration diagram for describing the first inspection unit of FIG. 1.

2, the light source 110, the imaging unit 120, the conversion unit 130, the image acquisition unit 140, the comparator 150, and the display unit 160 may be configured.

The light source unit 110 irradiates light onto the wafer W in order to detect a defect present in the wafer W. A lamp or a light emitting diode may be used as the light source unit 110. The light source unit 110 illuminates the surface of the wafer (W).

The light source unit 110 using the lamp may form a lamp which is a source of light, a reflector for reflecting the light and transferring the light onto the wafer W, and the light generated by the lamp and the light reflected by the reflector as parallel light. It may include a collimator lens (collimator lens) and the like.

The light source unit 110 is disposed above the wafer (W). The light source unit 110 may be disposed vertically from the upper surface of the wafer W or inclined at a predetermined angle. The light source unit 110 is preferably disposed to be inclined at an angle of about 85 to 90 degrees from the upper surface of the wafer (W).

A path switching member may be further disposed between the light source unit 110 and the front surface of the wafer W to switch the path of light. The path switching member may adjust an incident angle of light with respect to the entire surface of the wafer (W).

The imaging unit 120 captures an image of a portion of the wafer W to which light from the light source unit 110 is irradiated. A charge coupled device (CCD) sensor may be used as the imaging unit 120.

The imaging unit 120 is disposed at a suitable position for detecting the reflected light. According to an embodiment of the present invention, the imaging unit 120 is disposed to have an angle of about 85 to 90 degrees from the front surface of the wafer W, and the incident direction of light incident on the front surface of the wafer W is adjusted. It is placed within about 5 degrees on the basis. That is, the light source unit 130 and the imaging unit 120 are adjacent to each other, and are disposed to be substantially perpendicular to the upper surface of the wafer (W).

The converter 130 is connected to the imaging unit 120 and converts an electrical signal, which is an analog signal output in parallel from the imaging unit 120, into a digital signal. The converter 130 is an analog / digital converter (A / D converter) is used.

The image acquisition unit 140 is connected to the converter 130 and processes the digital signal containing the image information to obtain an image of the wafer (W).

The comparison unit 150 detects a defect by comparing the image with a preset reference image.

The display unit 160 displays the defect detected by the comparator 150. The defect is displayed on a wafer map. Therefore, the position of the said defect can be confirmed easily.

The second inspection unit 200 detects a defect of the wafer W using electrons. The second inspection unit 200 has a second precision that is more precise than the first precision. The second inspection unit 200 again inspects the defect detected by the first inspection unit 100 with a second precision.

3 is a configuration diagram for describing the second inspection unit of FIG. 2.

Referring to FIG. 3, the second inspection unit 200 includes an electron beam source 202, a stage 230, a driver 240, a detector 250, an image acquirer 260, a comparator 270, and a display unit. 280.

The electron beam source 202 includes an electron gun 210 for generating electrons, and a column for forming the electrons into an electron beam 204 and irradiating the electron beam 204 to the surface of a wafer W such as a silicon wafer. 220).

The electron gun 210 includes a filament 212 for generating electrons and an extraction electrode 212 for extracting the electrons. The column 220 includes an axial adjustment coil 224, a magnetic lens 224, an aperture 222, a scanning coil 223, and the like.

The magnetic lens 224 is a cylindrical electromagnet in which a coil is wound, and forms a magnetic field to focus electrons. In general, the cross-sectional area of the electron beam generated by the electron gun 210 is about 10 to 50 µm, and the spot size of the electron beam irradiated on the wafer W is about 5 to 200 nm. The magnetic lens 224 includes a pair of focusing lenses 225 and one objective lens 226. The pair of focusing lenses 225 focus the electron beam generated from the electron gun 210, and adjust the intensity of the electron beam. The objective lens 226 adjusts the spot size and the focal length of the electron beam irradiated to the surface of the wafer (W).

An axial adjustment coil 224 is disposed between the extraction electrode 212 and the magnetic lens 224 to match the electron beam formed by the extraction electrode 212 to the central axis of the magnetic lens 224.

An aperture 222 and a scanning coil 223 are disposed between the pair of focusing lenses 225 and the objective lens 226, and the scanning coil 223 deflects the electron beam so that the electron beam scans the wafer W. Let's do it.

The detector 230 detects the secondary electrons 206 emitted from the wafer W by the irradiation of the electron beam 204, converts the current signals corresponding to the detected secondary electrons into voltage signals, and amplifies the voltage signals. Let's do it. In this case, a bias voltage for detecting the secondary electrons 206 is applied to the detector 230.

The image acquisition unit 240 is connected to the detection unit 230 and converts the amplified voltage signal into image information of the wafer (W). That is, the image acquisition unit 240 also functions as an analog digital converter (AD converter) for converting an analog voltage signal into digital image information. The image acquisition unit 240 processes the image information to obtain an image of the wafer (W).

The comparator 250 is connected to the image acquirer 240 and compares the acquired image with a preset reference image. In the comparison, defects are detected and classified using various parameters. The parameters include contrast, contrast, brightness, size, and the like, which may be used alone or in combination of two or more.

The display unit 260 is connected to the comparator 250, and displays a defect detected by the comparator 250 on the wafer map.

The stage 300 supports the wafer W during the wafer inspection of the first inspection unit 100 and the second inspection unit 200. The stage 300 is commonly used in the first inspection unit 100 and the second inspection unit 200. The wafer W supported by the stage 300 is a bare wafer W in which no pattern is formed.

The driving unit 400 drives the stage 300 to reciprocate between the first inspection unit 100 and the second inspection unit 200. In detail, the driving unit 400 is connected to the stage 300 and moves the stage 300 in a horizontal direction with respect to a plane including the wafer W supported by the stage 300. When a defect is detected in the wafer W as a result of the defect detection of the first inspection unit 100, the driving unit 400 moves the stage 300 to the second inspection unit 200 for more accurate defect detection. Move to).

In the case of detecting a defect of the wafer W in the first inspection unit 100, the driving unit 400 has the wafer W positioned at a first inspection reference position of the first inspection unit 100. The stage 300 is moved to make. In the case of detecting a defect of the wafer W in the second inspection unit 200, the driving unit 400 is located at the second inspection reference position of the second inspection unit 200. The stage 300 is moved to make. At this time, the first inspection reference position and the second inspection reference position are substantially the same position. Therefore, the defect position on the wafer W may be represented using the same coordinates in the first inspection unit 100 and the second inspection unit 200.

That is, since the stage 300 is commonly used in the first inspection unit 100 and the second inspection unit 200, a wafer used in detecting defects of the wafer W in the first inspection unit 100. Coordinates and wafer coordinates used for defect detection of the wafer W in the second inspection unit 200 are substantially the same. Therefore, the defect detected by the first inspection unit 100 can be easily confirmed by the second inspection unit 200. The defect detected by the first inspection unit 100 may be inspected more precisely by the second inspection unit 200. Therefore, it is possible to classify the defect, and to identify the generation time of the defect, the cause of the defect, and the like.

On the other hand, the driving unit 400 is X with respect to the plane including the wafer (W) supported on the stage 300 for defect detection in the first inspection unit 100 and the second inspection unit 200 The stage 300 is moved in the axial and Y-axis directions. Since the wafer W is moved in the X-axis and Y-axis directions by the driving unit 400, a light source or an electron beam scans the upper surface of the wafer W.

Although not shown, a second driving unit may be connected to the lower portion of the stage 300 to adjust the height of the stage 300 when the wafer defect is detected by the second inspection unit 200.

According to the above embodiment, it has been described that the display units 160 and 260 are provided in the first inspection unit 100 and the second inspection unit 200, respectively, but according to another embodiment of the present invention, the first inspection unit One display unit may be provided in common to the 100 and the second inspection unit 200.

According to the above embodiment, it has been described that the display units 160 and 260 are provided in the first inspection unit 100 and the second inspection unit 200, respectively, but according to another embodiment of the present invention, the first inspection unit One display unit may be provided in common to the 100 and the second inspection unit 200.

Hereinafter, the operation of the wafer inspection apparatus 1000 will be described.

First, the stage 300 is positioned below the first inspection unit 100 by the driving unit 400. Thereafter, the bare wafer W is loaded into the stage 300. The loaded bare wafer W is first inspected. The primary inspection is made with a first precision using the first inspection unit 100.

As a result of the inspection, when no defect exists in the bare wafer W, the bare wafer W is unloaded to proceed to the subsequent process. If a defect exists in the bare wafer W, the defect is detected.

More precise inspection of the defect is necessary to obtain more information about the defect and whether or not the defect detected in the first inspection unit 100 is actually present on the wafer (W). Therefore, the driving unit 400 moves the stage 300 supporting the bare wafer W to be located under the second inspection unit 200 for the inspection of the bare wafer W.

The bare wafer W positioned below the second inspection unit 200 is secondarily inspected. The secondary inspection is performed using the second inspection unit 200 to make the bare wafer W at a second precision that is more accurate than the first precision. Since the stage 300 is commonly used in the first inspection unit 100 and the second inspection unit 200, coordinates of defects existing on the bare wafer W may be used in the same manner. Therefore, the defect position detected as a result of the inspection in the first inspection unit 100 can be quickly and easily reconfirmed in the second inspection unit 200. Therefore, it is possible to quickly check whether the defect is a defect that actually exists. In addition, the defects can be inspected more precisely to classify the defects according to types. The cause of occurrence can be identified according to the type of the defect.

Unloading the bare wafer W after the inspection of the bare wafer W is completed, and the stage 300 is positioned under the first inspection unit 100 by driving the driving unit 400. .

Thereafter, the above process is repeated to inspect the wafer (W).

As described above, the wafer inspection apparatus according to the preferred embodiment of the present invention inspects the defect of the wafer in the first inspection unit and again inspects the defect of the wafer in the second inspection unit where the defect is detected. At this time, the stage supporting the wafer is moved and used in common in the first inspection unit and the second inspection unit. Therefore, the defect of the wafer detected by the said 1st inspection unit can be confirmed quickly and inspected by the said 2nd inspection unit. Therefore, the time required for the inspection of the wafer can be shortened.

In addition, through the inspection of the second inspection unit it is possible to classify the defects by type or size, and to determine the cause of the defects. Therefore, it can be fed back to the semiconductor manufacturing process to improve the yield of the semiconductor device.

While the foregoing has been described with reference to preferred embodiments of the present invention, those skilled in the art will be able to variously modify and change the present invention without departing from the spirit and scope of the invention as set forth in the claims below. I can understand that you can.

Claims (4)

A first inspection unit for primarily detecting a defect in the wafer; A second inspection unit for secondarily detecting a defect of the wafer; A stage for supporting the wafer while detecting defects in the first inspection unit and the second inspection unit; And The wafer is positioned at a first reference position of the first inspection unit during the first detection and the wafer is positioned at a second reference position of the second inspection unit substantially the same as the first reference position during the secondary detection. And a drive unit for horizontally moving the stage. The wafer inspection apparatus according to claim 1, wherein the first inspection unit has a first precision, and the second inspection unit has a second precision higher than the first precision. The wafer inspection apparatus according to claim 2, wherein the first inspection unit detects a defect by using light, and the second inspection unit detects a defect by using an electron beam. The wafer inspection apparatus according to claim 1, wherein the wafer is a bare wafer.

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