JP2002122552A - Defect inspection device and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a defect inspection device and method capable of easily searching for defects when reviewing the defects detected from the plane to be inspected of a body to be inspected such as a semiconductor wafer by an observing device such as a scanning microscope. SOLUTION: The defect inspection device comprises an optical system 12 for guiding luminous flux emergent from a light source 11 to the surface of the semiconductor wafer W, an image pickup device 18 for picking an optical image by reflected light from the surface of the semiconductor wafer W, a computer as a defect extracting means for extracting defects present in the surface of the semiconductor wafer W from the picked-up optical image, and a laser unit 31 as a marking means for marking the extracted defects in the surface of the semiconductor wafer W.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a defect inspection apparatus and a defect inspection method for inspecting a defect existing on a surface to be inspected, such as a surface of a semiconductor wafer.

[0002]

2. Description of the Related Art In a semiconductor device manufacturing process, a defect inspection technique for detecting a defect generated in a semiconductor wafer is described in US Pat.
This is a very important technology to identify the cause of the defect, adopt an appropriate solution, and improve the yield. For this reason, conventionally, in a semiconductor device manufacturing process, a semiconductor wafer is extracted during a semiconductor device manufacturing process, and, for example,
2. Description of the Related Art An optical defect inspection apparatus detects a defect such as a particle from an optical image on the surface of a semiconductor wafer. In addition, review the detected defects, analyze the source of the defects using an observation device such as a scanning electron microscope or an optical microscope, identify the source of the defects by analysis, and feed this back to the manufacturing process to improve the yield. That is being done.

[0003]

By the way, when a defect of a semiconductor wafer is detected by a defect inspection apparatus, positional information of the defect is stored. When reviewing the detected defect, the position information is sent to an observation device such as a scanning electron microscope or an optical microscope, and a stage for holding the semiconductor wafer provided in the observation device is driven based on the position information. Find out the defects to observe. However, when the defects existing in the semiconductor wafer are extremely small,
The field of view of the observation device may be shifted with respect to the defect to be observed within the range of the positioning accuracy of the stage. If the defect on the semiconductor wafer does not fall within the field of view of the observation device, it is very difficult and time-consuming to find the defect to be observed. Therefore, it takes a long time to analyze the defects, and it takes a long time to feed back information on the source of the defects to the manufacturing process. As a result, the yield may be reduced.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and is intended to detect a defect detected from an inspection surface of an inspection object such as a semiconductor wafer when reviewing the defect using an observation device such as a scanning microscope. It is an object of the present invention to provide a defect inspection apparatus and a defect inspection method that can easily search for a detected defect.

[0005]

SUMMARY OF THE INVENTION A defect inspection apparatus according to the present invention is a defect inspection apparatus for inspecting a defect existing on a surface to be inspected of an object to be inspected, wherein a light beam emitted from a light source is applied to the surface to be inspected. An optical system that guides, an imaging unit that captures an optical image by light reflected from the inspection surface, and a defect extraction unit that extracts a defect present on the inspection surface from the captured optical image.
Marking means for marking the extracted defect on the surface to be inspected.

[0006] The marking means performs marking of a predetermined shape on the defect.

The marking means has laser irradiation means for irradiating the defect on the surface to be inspected with laser light through the optical system to perform marking.

The optical system includes: an optical lens for condensing light from the light source; and a laser irradiation unit that irradiates the surface to be inspected with laser light through the optical system.
A marking lens for condensing a laser beam used in place of the optical lens.

A defect analysis means for analyzing information on the defect from the extracted optical image of the defect, and a marking for changing a marking condition by the marking means in accordance with the analysis information obtained from the defect analysis means. Control means.

The defect analysis means detects at least the area of the defect from the optical image of the defect, and the marking control means changes the area of the marking according to the detected area of the defect.

The marking means includes: a laser irradiating means for irradiating a defect on the surface to be inspected with laser light through the optical system for marking; and an opening area through which the laser light irradiated from the laser irradiating means passes. A variable aperture, wherein the marking control means changes the aperture area of the aperture according to the area of the detected defect.

A defect inspection method according to the present invention is a defect inspection method for inspecting a defect present on a surface to be inspected of an object to be inspected,
A defect existing on the inspected surface is extracted from the optical image of the inspected surface, marking is performed on the extracted defect on the inspected surface, and the inspected surface on which the defect is marked is observed by a predetermined observation device. It is characterized by the following.

Preferably, in the defect inspection method according to the present invention, marking is performed by irradiating a laser beam to a defect existing on the inspection surface.

More preferably, in the defect inspection method of the present invention, the size of the extracted defect is obtained, and the irradiation area of the laser beam to be applied to the defect on the inspection surface is determined according to the size of the defect. change.

In the present invention, a defect existing on the inspected surface is extracted from the optical image of the inspected surface, and the defect is directly marked. When observing the surface to be inspected on which the defect is marked in detail with an observation device, it is sufficient to find out the marking, and it is possible to easily fit in the visual field of the observation device. In particular, by making the marking a predetermined shape such as a circle, a rectangle, and a triangle, the search for a defect becomes easier.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram of a defect inspection apparatus according to one embodiment of the present invention. In FIG. 1, the defect inspection apparatus 1 includes a stage unit 2, a light source 11, an optical system 12, an imaging device 18, a laser unit 31, and a computer 21.

The stage section 2 has an XY stage 3 and a tilt stage 4 provided on the XY stage 3. The tilt stage 4 holds a semiconductor wafer W to be inspected, and can tilt the semiconductor wafer W at an arbitrary tilt angle with respect to the XY plane. The XY stage 3 can move the semiconductor wafer W in the X-axis direction and the Y-axis direction. The XY stage 3 and the tilt stage 4 are driven by a drive mechanism including, for example, a motor and a transmission mechanism (not shown).

The optical system 12 includes a light source 11, half mirrors 13 and 14, and an objective lens 15. Light source 1
Reference numeral 1 denotes, for example, a halogen lamp or an Xe lamp, and emits a light beam L for irradiating the inspection surface of the semiconductor wafer W.

The half mirror 13 reflects the light beam L emitted from the light source 11 toward the surface facing the light source 11, and bends the optical path of the light beam L in a direction toward the half mirror 14. Further, the half mirror 13 transmits a laser beam Ls that enters the surface on the side facing the laser unit 31 described later.

The half mirror 15 reflects the light beam L or the laser light Ls guided from the half mirror 13 and directs the light path of the light beam L or the laser light Ls toward the surface of the semiconductor wafer W held on the tilt stage 4. The half mirror 15 transmits the reflected light Lr of the light beam L applied to the semiconductor wafer W.

The objective lens 15 condenses the light beam L or the laser light Ls incident from the half mirror 14 side and guides it to the surface of the semiconductor wafer W.

The image pickup device 18 receives the reflected light Lr from the semiconductor wafer W through the objective lens 15 and the half mirror 14, and converts this into an electric signal to pick up an optical image of the semiconductor wafer W. The imaging device 18 includes, for example, a charge coupled device (CCD).
vice).

The laser unit 31 includes a laser oscillator 32
, A laser forming section 33 and an aperture 34. The laser oscillator 32 outputs a laser beam Ls. The laser shaping unit 16 outputs the laser light Ls output from the laser oscillator 32.
Is formed into a predetermined shape, for example, a circular shape.
The aperture 34 is provided with the laser light L formed by the laser forming unit 16.
s has an opening through which This opening has, for example, a circular shape. The aperture area of the stop 34 is variable. The aperture 34 is connected to the computer 21 as described later.
Is controlled by Laser light Ls that has passed through aperture 34
Is a light flux corresponding to the opening area of the stop 34.

The computer 21 receives a detection signal from the image pickup device 18 through an A / D converter 22. A detection signal containing an optical image of the surface of the semiconductor wafer W captured by the imaging device 18 is converted into a digital signal of a predetermined format by the A / D converter 22 and taken into the computer 21. The computer 21 is connected to the stage unit 2 and the laser unit 31. The computer 21 is connected with input devices such as a mouse 23 and a keyboard 24, and is also connected with a display device 25 made of, for example, a CRT.

FIG. 2 is a functional block diagram of the computer 21. 2, a computer 21 includes an image data input unit 41, a defect extraction unit 42, and a defect analysis unit 4.
3, a defect data storage unit 44, and an operation data input unit 45
, A marking control unit 46, an image display unit 47, and a stage control unit 48.

The image data input section 41 receives an optical image of the semiconductor wafer W input from the imaging device 18 through the A / D converter 22 and holds the optical image.

The defect extraction unit 42 is provided with an image data input unit 41
An optical image of a defect such as a particle existing on the semiconductor wafer is extracted from the optical image of the semiconductor wafer W input from the computer. Specifically, when a defect is present on the semiconductor wafer and when there is no defect on the semiconductor wafer, the optical image is different, and the difference is detected by software processing to extract the defect. be able to.

The defect analyzer 43 analyzes information on the defect on the semiconductor wafer extracted by the defect extractor 42. Here, the defect information is, for example, various information for specifying the defect, such as coordinates at which the defect is located, the shape of the defect, and the size of the defect. The defect analysis unit 43 outputs the obtained analysis information to the defect data storage unit 44. The defect data storage unit 44 stores analysis information on defects.

The image display unit 47 displays on the display unit 25 the optical image of the defect extracted by the defect extraction unit 42 and various analysis information stored in the defect data storage unit 44.
The operator can observe the defect image displayed on the display device 25 and confirm various information.

The stage controller 48 controls the X of the stage 2
The drive control of the Y stage 3 and the tilt stage 4 is performed. The light beam L applied to the semiconductor wafer W is
, The entire image of the surface of the semiconductor wafer W cannot be obtained by a single imaging. Therefore, to obtain an image of the entire surface of the semiconductor wafer W, X
The Y stage 3 is driven to scan the semiconductor wafer W in the XY directions. In addition, if the image of the semiconductor wafer W is captured from the same direction, the locational characteristics of the defect may not be known in some cases. Therefore, in order to capture the image of the semiconductor wafer W while changing the imaging direction, the tilt stage 4 is inclined appropriately. The control operation of the stage control unit 48 is associated with the imaging operation of the imaging device 18.
A configuration controlled by a previously facilitated program can be adopted. Further, the stage control unit 48 acquires the position information of the semiconductor wafer W from a position detector provided in a motor that drives the XY stage 3 and the tilt stage 4. From this position information, the defect analyzer 43
The position coordinates of the defect can be specified.

The operation data input section 45 receives information from the mouse 23 and the keyboard 24. The data input to the operation data input unit 45 is used to control the computer 21. It is also used as control information for a marking control unit 46 described later.

The marking control section 46 controls the operation of the laser unit 31. Specifically, the marking control unit 46 controls output and stop of the laser light Ls from the laser unit 31 and control of the output intensity. The marking control unit 46 performs these controls according to the input data from the operation data input unit 45. Further, the marking control unit 46 obtains information on the size (area) of the defect from the defect analysis unit 43 and controls the opening area of the stop 34 according to this information.

Next, a defect inspection method according to the present invention using the defect inspection apparatus 1 having the above-described configuration will be described. First, the semiconductor wafer W is positioned at the reference position of the tilt stage 4. A light beam L is emitted from the light source 11 to the semiconductor wafer W. An optical image of the surface of the semiconductor wafer W irradiated with the light beam L is captured by the imaging device 18. After capturing an optical image of a part of the surface of the semiconductor wafer W, the semiconductor wafer W is driven while the stage unit 2 is driven by a predetermined operation.
An image of the entire surface of the semiconductor wafer W is captured while scanning the entire surface of the semiconductor wafer W (step S1).

The picked-up image data of the semiconductor wafer W is taken into an image data input section 41 of the computer 21, and a defect extracting section 42 extracts a defect existing on the semiconductor wafer W from the image data of the semiconductor wafer W. (Step S2).

Next, the defect analysis unit 43 analyzes various information such as position coordinates, shape, and size of the defect from the extracted defect image (step S3). Further, the obtained analysis information is stored in the defect analysis data storage unit 44.

When the extraction of the defect existing on the semiconductor wafer W and the analysis of the defect are completed, the defect inspection ends.

In this state, if there are defects on the semiconductor wafer W, the computer 21 displays a list of these defects on, for example, the screen of the display device 25 (step S4). The defect list includes an image of each defect and analysis information of these defects.

The operator determines whether or not to mark each defect while looking at the defect list displayed on the screen of the display device 25 (step S5). For example, information as to whether or not to mark each defect may be displayed on the screen of the display device 25 in an interactive manner, and the information may be selected by operating the mouse 23 to determine the information. Specifically, for example, as shown in FIG.
The defect K is displayed on the screen D of the display device 25, and the defect K
, Selection buttons bt1 and bt2 are displayed. The selection button bt1 is a button for determining that marking is to be performed on the defect K, and the selection button b
t2 is a button for deciding not to mark the defect K. The operator observes the defect image K,
Also, the selection buttons bt1, b
It is determined whether any one of t2 is selected with the mouse 23 and marked.

After selecting the selection button bt1 for performing marking, the output intensity of the laser light Ls output from the laser unit 31 is determined (step S6). For example, the output intensity of the laser beam Ls can be configured to be selectable from three levels of high, medium, and low. The selection of the output intensity of the laser light Ls can also be performed by operating the mouse 23 on the screen of the display device 25. The reason for adjusting the output intensity of the laser light Ls is that if the energy of the laser light Ls is too high, the defect present on the semiconductor wafer W is, for example, in the case of an organic substance, the organic substance itself is oxidized and disappears or deforms It is possible to avoid this. That is, the state of the defect is determined on the screen of the display device 25, and when the displayed defect is determined to be an organic substance, the energy of the laser beam Ls is relatively reduced to prevent the defect from disappearing or deforming.

Next, marking by the laser unit 31 is started. At this time, the semiconductor wafer W is positioned by the stage unit 2 so that the defect to be marked is irradiated with the laser light Ls from the laser unit 31. Further, according to the size (area) of the defect included in the defect analysis information described above, the marking control unit 46
Adjusts the opening area of the stop 34 of the laser unit 31 (step S7). That is, when the defect is relatively large, the aperture of the stop 34 is adjusted to be large,
When the defect is small, the aperture area of the stop 34 is also adjusted to be small. Thereby, for example, the size of the cross section of the laser beam Ls having a circular cross section is substantially the same as the size of the defect.

The semiconductor wafer W is moved to an appropriate position,
After adjusting the opening area of the stop 34, the laser light Ls is irradiated toward the defect (step S8). This laser light Ls
The defect is marked, for example, as shown in FIG. The marking MK has substantially the same size as the defect K and is circular.

The marking process is completed by performing the above process for all the defects on the semiconductor wafer W. The process up to this point is a process of extracting defects on the semiconductor wafer W for the time being and marking these defects. Thereafter, the defect of the marked semiconductor wafer W is analyzed and analyzed using an observation device such as a scanning electron microscope or an optical microscope to identify the source of the defect, and this is fed back to the semiconductor device manufacturing process. When observing a marked defect using an observation device,
The defect must be displayed on the monitor of the observation device. At this time, when the defect is extremely small, it may be difficult to display a desired defect on a monitor only by the position information of the defect, but in the present embodiment, the defect is marked. Therefore, it is possible to easily search for a defect. In other words, markings made on defects are
The search is very easy because it is always circular and not abnormal. It is also possible to provide an observation device such as a scanning electron microscope or an optical microscope with a means for searching for a circular marking by an image processing technique. In the present embodiment, the shape of the marking by the laser light Ls is circular, but may be, for example, rectangular, triangular, or the like. By making the shape of the marking a specific shape, it becomes very easy to search for a defect in the observation device.

FIG. 5 is a configuration diagram showing an example of the configuration of the optical system of the defect inspection apparatus of the present invention. In FIG. 5, the same components as those in the above-described embodiment are denoted by the same reference numerals. The optical system 120 shown in FIG.
In addition to 5, an objective lens 16 for marking is provided. The objective lens 16 for marking is not used when extracting a defect existing on the semiconductor wafer W,
It is used only when a laser beam is emitted by the laser unit 31.

In the above-described embodiment, since the laser beam is irradiated using the objective lens 15, the objective lens 15 may be damaged by the laser beam. For this reason, by adding the objective lens 16 for marking used only when irradiating laser light to the optical system 120 and using the objective lens 16 at the time of marking, the life of the objective lens 15 is shortened. Can be prevented.

[0045]

According to the present invention, when a defect detected from a surface to be inspected of an object to be inspected such as a semiconductor wafer is reviewed by an observation device such as a scanning microscope, the defect can be easily searched.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a defect inspection apparatus according to an embodiment of the present invention.

FIG. 2 is a functional block diagram in a computer.

FIG. 3 is a flowchart showing a procedure of a defect inspection method of the present invention.

FIG. 4A is a diagram illustrating an example of a defect image;
(B) is a figure which shows an example of the image of the state which marked the defect.

FIG. 5 is a configuration diagram showing another configuration example of the optical system of the defect inspection apparatus of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Defect inspection apparatus, 2 ... Stage part, 3 ... XY stage, 4 ... Tilt stage, 11 ... Light source, 12 ... Optical system,
DESCRIPTION OF SYMBOLS 21 ... Computer, 22 ... A / D converter, 23 ... Mouse, keyboard ... 24, 25 ... Display device, 31 ... Laser unit, 32 ... Laser oscillator, 33 ... Laser molding part, 34 ... Aperture, 41 ... Image data Input unit, 42: defect extraction unit, 43: defect analysis unit, 44: defect data storage unit,
45: operation data input unit, 46: marking control unit, 4
7 image display unit, 48 stage control unit, W semiconductor wafer.

Continued on the front page F-term (reference) 2F065 AA21 AA49 AA58 BB03 BB24 BB25 CC19 DD00 DD06 FF04 GG02 GG03 GG04 HH04 HH12 JJ03 JJ26 LL04 LL30 LL46 PP12 QQ03 SS02 SS07 SS13 UU04 UU09 2G051 AA01 AB01 DA07 BC ED09 4M106 AA01 BA05 CA38 CA43 DA05 DA20 DB04 DB08 DB12 DB13

Claims (11)

[Claims] 1. A defect inspection apparatus for inspecting a defect present on a surface to be inspected of an object to be inspected, comprising: an optical system for guiding a light beam emitted from a light source to the surface to be inspected; and a reflection from the surface to be inspected. Imaging means for capturing an optical image by light; defect extraction means for extracting a defect present on the inspection surface from the captured optical image; and marking means for marking the extracted defect on the inspection surface. Defect inspection equipment. 2. A defect inspection apparatus according to claim 1, wherein said marking means performs marking of a predetermined shape on said defect. 3. The defect inspection apparatus according to claim 1, wherein said marking means has laser irradiation means for irradiating a laser beam on the defect on the surface to be inspected through the optical system to perform marking. 4. The optical system according to claim 1, further comprising: an optical lens for condensing light from the light source; and an optical lens when the laser irradiation means irradiates the inspection target surface with laser light through the optical system. The defect inspection apparatus according to claim 3, further comprising a marking lens for condensing a laser beam to be used. 5. A defect analysis means for analyzing information relating to the defect from the extracted optical image of the defect, and changing a marking condition by the marking means in accordance with the analysis information obtained from the defect analysis means. The defect inspection apparatus according to claim 1, further comprising a marking control unit that performs the marking. 6. The defect analyzing means detects at least the size of the defect from the optical image of the defect, and the marking control means changes the area of the marking according to the detected size of the defect. The defect inspection apparatus according to claim 5, wherein 7. A laser irradiating means for irradiating a laser beam on a defect on the surface to be inspected through the optical system for marking, and an opening through which the laser light radiated from the laser irradiating means passes. The defect inspection apparatus according to claim 5, further comprising a stop having a variable area, wherein the marking control unit changes an opening area of the stop in accordance with a size of the detected defect. 8. A defect inspection method for inspecting a defect present on a surface to be inspected of an object to be inspected, comprising: extracting a defect present on the surface to be inspected from an optical image of the surface to be inspected; A defect inspection method, wherein a defect on a surface to be inspected is marked, and the surface on which the defect is marked is observed by a predetermined observation device. 9. The defect inspection method according to claim 8, wherein the defect is marked in a predetermined shape. 10. The defect inspection method according to claim 8, wherein the defect existing on the inspection surface is marked by irradiating a laser beam. 11. The defect inspection method according to claim 10, wherein a size of the extracted defect is obtained, and an irradiation area of a laser beam applied to the defect on the inspection surface is changed according to the size of the defect. .