JP5250395B2 - Inspection device - Google Patents

Description

  The present invention relates to an inspection apparatus. For example, the present invention relates to a method for inspecting foreign matter or scratches (hereinafter referred to as defects) of a semiconductor wafer in a semiconductor device manufacturing process, an apparatus for inspecting defects, and a method for inspecting a semiconductor device using them.

  A conventional inspection apparatus is provided with a light intensity measurement mechanism only for measuring the light intensity of laser light, as disclosed in Japanese Patent Application Laid-Open No. 2007-279021. In a conventional semiconductor surface inspection apparatus, the light intensity measurement mechanism has been confirmed and adjusted.

JP 2007-279021 A

  In the conventional technique, the device state is monitored by a camera such as a sensor during adjustment, but correction is not performed by a plurality of imaging devices (for example, cameras), and the brightness of illumination light is detected by the sensor at the device adjustment stage. The sheath position was observed and adjustments were made to optimize the device state. Further, adjustment is performed using the sensor in order to restore the apparatus state using the sensor when the sensitivity is lowered or the parts are replaced. These sensors are not used for monitoring the state of the irradiation optical system but are used for restoring the state at the time of adjustment.

  In such a conventional technique, no consideration has been given to the point that the adjustment varies from the optimum state over time. An object of the present invention is to easily and stably operate an inspection apparatus.

  A feature of the present invention resides in that a plurality of imaging devices are mounted.

  Another feature of the present invention is that it includes a processing unit that calculates an adjustment amount for adjusting light from the irradiation optical system based on imaging results of the plurality of imaging devices.

  Another feature of the present invention resides in having an adjustment mechanism that adjusts the light based on the adjustment amount.

  According to the present invention, a stable apparatus state can be realized.

  FIG. 1 shows the configuration of the inspection apparatus. The inspection apparatus places a sample (including a substrate such as a wafer) and moves a scanning system 1111 in the scanning direction, an irradiation optical system 1112 that irradiates the substrate with light 101, and light 102 (scattered light, A detection optical system 1113 for detecting reflected light, an inspection processing system 1114 for inspecting a sample from the detection result, and an input / output system 1115 for displaying and inputting various information.

  More specifically, the transport system 1111 includes a placement unit 1116 for placing the sample and a moving unit 1117 for moving the placement unit. The irradiation optical system 1112 includes a light source 1 that generates light and an optical element 1118 that guides the light to a sample. The detection optical system 1113 includes a photodetector 1119 that detects light from the sample, but may include an optical element that guides light from the sample to the photodetector. The inspection processing system 1114 includes a defect processing unit 1120 that inspects defects of the sample from the detection result of the photodetector. The input / output system 1115 includes a display unit 1121 for displaying inspection results and defect information, and an input unit 1122 for inputting inspection conditions and the like.

  Hereinafter, examples will be described with reference to the drawings.

  FIG. 2 shows the configuration of a surface inspection apparatus for inspecting the surface of a semiconductor wafer according to an embodiment of the present invention.

  An inspection table 19 on which the sample 8 is placed (placed) is included as the mounting portion 1116 of the transport system 1111, and an XYZθ stage 9 is included as the scanning portion 1117. Note that the transport system 1111 may include a motor such as a spindle and a stage, and rotate and go straight. The irradiation optical system 1112 includes the light source 1, includes a light amount adjustment mechanism 2, an optical axis adjustment mechanism 3, and a zoom mechanism 5 as adjustment mechanisms, and includes mirrors 6 a, 6 b, 6 c, 6 d, and lenses 7 a, 7 b as optical elements 1118. Including. The detection optical system 1113 includes a detector 10 such as a photomultiplier tube as a photodetector 1119, and further includes an amplifier 11 and an A / D converter 12. The inspection processing system 1114 includes a defect determination mechanism 13 and a detected defect classification mechanism 14 as a defect processing unit 1120. The input / output system 1115 includes a display unit 111.

  The light 101 emitted from the light source 1 is a light amount adjusting mechanism 2 that can adjust the brightness of an attenuator or the like composed of a λ / 2 wavelength plate and a polarizing beam splitter (PBS), and an optical axis that adjusts the optical axis. The sample 8 is irradiated through the adjusting mechanism 3 and the zoom mechanism 5 such as a beam expander. The optical axis adjustment mechanism 3 is provided with a CCD camera 4a (first imaging device) which is an example of an imaging device. The light emitted from the zoom mechanism 5 is switched to the vertical optical path or the oblique optical path by the vertical oblique irradiation switching mirror 6a. The vertically branched light passes through the half mirror 6d, is condensed by the condenser lens 7a, and is irradiated onto the sample 8. The light irradiated on the sample 8 is reflected, passes through the condenser lens 7a, is branched by the half mirror 6d, and reaches the CCD camera 4b (second imaging device).

  When the vertical oblique irradiation switching mirror 6a is out of the optical path, the beam travels along the oblique optical path, is reflected by the mirrors 6b and 6c, and is irradiated onto the sample surface by the condenser lens 7b. The light reflected from the sample 8 passes through the condenser lens 7a and is picked up by the CCD camera 4b as in the vertical irradiation. The images captured by the CCD cameras 4a and 4b are taken into the image analysis unit and the feedback control unit 15 (processing unit), perform image analysis, and information on the beam deviation from the correctly adjusted state (for example, the optical axis) , A shift amount indicating a horizontal shift, a tilt amount indicating a shift of the optical axis tilt, a shape shift amount, and a brightness shift amount) are calculated, and the light amount adjusting mechanism 2, the optical axis adjusting mechanism 3, and the zoom mechanism are calculated. 5 Command the adjustment amount to each.

  More specifically, in the light amount adjustment mechanism 2, for example, a λ / 2 wavelength plate rotates based on the adjustment amount. In the optical axis adjustment mechanism 3, at least one of a tilt mechanism 103 and a shift mechanism 104, which will be described later, operates based on the adjustment amount.

  In this way, the adjustment amount is calculated based on the imaging results of the CCD cameras 4a and 4b, and the light amount adjustment mechanism 2, the optical axis adjustment mechanism 3, and the zoom mechanism 5 each adjust the deviation of the light 101 based on the adjustment amount. Therefore, a stable device state can be realized.

  FIG. 3 shows details of the optical axis adjustment mechanism 3. The mirrors 17 and 18 are respectively provided with a tilt (rotation) mechanism 103 that rotates the mirrors 17 and 18 and a shift mechanism 104 that moves the mirrors 17 and 18. A motor can be used as the tilt mechanism, and a stage that moves in one direction can be used as the shift mechanism. The fixed reflection mirror 16 disposed in the optical path behind the mirrors 17 and 18 splits the light 101 in two directions. The light that has passed through the fixed reflecting mirror 16 is observed by the CCD camera 4a. The light whose direction is changed by the fixed reflection mirror 16 is irradiated to the sample 8 via the mirrors 6a and 6b.

  FIG. 4 shows a CCD camera image attached to the optical axis adjustment mechanism 3.

  In the CCD camera 4a of the optical axis adjustment mechanism, the shift amount indicating the horizontal shift of the optical axis and the tilt amount indicating the shift of the optical axis tilt can be confirmed. In the CCD camera 4b, the tilt amount of the beam can be confirmed. When the beam is shifted in the tilt direction, the beam is adjusted by the tilt of the optical axis adjusting mechanism 3. In the CCD camera 4a, the shift amount and the tilt amount can be observed. However, since the tilt amount is adjusted by the CCD camera 4b, only the shift amount can be confirmed with no tilt deviation.

  The tilt amount confirmation image 112 and the shift amount confirmation image 113 will be described in detail.

  The tilt amount confirmation image 112 is tilted with a tilt amount in one direction (first tilt amount) as one axis 114 and a tilt amount (second tilt amount) perpendicular to the first tilt amount as one axis 115. Display quantity.

  Further, the tilt amount confirmation image 112 includes a line (first line) 116 parallel to the first tilt amount axis and a line (second line) parallel to the second tilt amount axis. Line) 117 is used to display the screen in four parts. The vicinity of the intersection 118 between the first line 116 and the second line 117 is not shifted.

  By displaying the image with the beam position adjusted near the intersection 118 in this way, the operator can easily know that the beam tilt amount has been adjusted correctly.

  The same can be said for the shift amount confirmation image 113. The shift amount confirmation image 113 is shifted with a shift amount in one direction (first shift amount) as one axis 119 and a shift amount (second tilt amount) perpendicular to the first shift amount as one axis 120. Display quantity.

  Further, the shift amount confirmation image 113 includes a line (first line) 121 parallel to the first shift amount axis and a line (second line) parallel to the second shift amount axis. Line) 122 is used to display the screen in four parts. The vicinity of the intersection 123 between the first line 121 and the second line 122 is not displaced. By displaying the image with the beam position adjusted in the vicinity of the intersection 123 in this manner, the operator can easily know that the beam shift amount has been correctly adjusted, and also constantly monitor the beam state. be able to.

  The tilt amount confirmation image 112 and the shift amount confirmation image 113 can also be confirmed on the display unit 111 such as a liquid crystal display or a CRT display.

  FIG. 5 shows a flowchart of irradiation optical system adjustment which is an embodiment of the present invention. The beam position and brightness are calculated from the image of the CCD camera 4b, and the tilt amount is confirmed (211). The brightness is adjusted by the light amount adjusting mechanism 2 (212), and the beam position is adjusted by the tilt motor of the optical axis adjusting mechanism 3 (213). Next, the shift amount of the CCD camera 4a is confirmed by the shift mechanism of the optical axis adjustment mechanism 3 (214) and adjusted (215). Further, in the CCD camera 4b and the display unit 111, the brightness and shape of the beam can be confirmed by adjusting the magnification of the camera.

  Then, the beam position is confirmed by the CCD cameras 4a and 4b (216). If there is a deviation in the beam position, the process returns to (211), and the tilt amount and the shift amount are adjusted again.

  If there is no deviation in the beam position in (216), the shape of the beam is confirmed by the CCD camera 4b (217). If there is no deviation in the beam shape, the adjustment is completed (220).

  If there is a deviation in the beam shape in (217), check the position of the Z stage, etc., and check whether the focus is out of focus (218). If the focus is off, move the Z stage, etc. The focus is adjusted (221).

  If there is no defocus, the zoom mechanism 5 adjusts the beam shape (219).

  From this result, the brightness is adjusted by the light quantity adjustment mechanism, the beam shape is adjusted by the zoom mechanism, and the irradiation optical system can be easily managed in the optimum state at all times.

  In this way, a stable apparatus state can be realized by automatically adjusting the beam tilt amount and shift amount. Furthermore, in the past, it took a lot of time to adjust the irradiation optical system, but in this embodiment, the beam state can be adjusted more quickly than in the past.

  In the present embodiment, it is also possible to adjust only the tilt amount. In the case of adjusting only the tilt amount, the adjustment may be completed in the procedure (213) in FIG. In this method, the state of the beam can be adjusted more rapidly than in the case of adjusting the tilt amount and the shift amount.

  Further, a semiconductor manufacturing factory has a plurality of manufacturing lines, and an inspection device such as a surface inspection device as in this embodiment is arranged in each manufacturing line to monitor the dust generation state of the manufacturing line. In the case of an apparatus equipped with an irradiation optical system, the stability of the state of the irradiation optical system and the stability of the detection system are indispensable in order to obtain stable sensitivity. Since the difference in the state of the irradiation optical system leads to a machine difference between apparatuses, even if one of them is specialized, the apparatus performance is affected. By applying the present embodiment to each of the inspection devices arranged on the plurality of production lines, the machine difference between the devices can be reduced.

  The present invention can be applied to inspection of substrates other than wafers such as hard disks and liquid crystal substrates. Furthermore, the present invention can be applied to a wafer inspection apparatus that collects scattered light using an ellipsoidal sphere, and a wafer inspection apparatus with a pattern that inspects a defect of a wafer on which a pattern is formed, or an inspection of a defect of a hard disk. It can also be applied to a hard disk inspection device.

  The transport system may include an X stage, a Y stage, a Z stage, and a θ stage, and may be configured to scan in the XY direction, or the shape of the laser irradiated onto the substrate by the irradiation optical system May be linear, the detection optical system may be an imaging system using a mirror, a lens, etc., or may be equipped with a spatial filter that removes diffracted light from the pattern, The detector may be a time delay integration type sensor or a CCD sensor.

Configuration of inspection equipment. Configuration of surface inspection equipment. Details of the optical axis adjustment mechanism 3. Tilt amount confirmation image 112 and shift amount confirmation image 113. The flowchart of irradiation optical system adjustment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light source 2 Light quantity adjustment mechanism 3 Optical axis adjustment mechanism 4 CCD camera 5 Zoom mechanism 6 Mirror 7 Condensing lens 8 Sample 9 XYZ (theta) stage 10 Detector 11 Amplifier 12 A / D converter 13 Defect determination mechanism 14 Detection defect classification mechanism 15 Image Processing unit, feedback control unit

Claims (13)

A transport system for placing a sample and moving in the scanning direction;
An irradiation optical system for irradiating the sample with light for illumination;
A detection optical system for detecting light from the sample;
An inspection processing system for performing an inspection from a detection result from the detection system;
A first imaging device that images light for the illumination;
A second imaging device for imaging light from the sample;
A processing unit that calculates an adjustment amount for adjusting a shift of light for the illumination, using imaging results of the first imaging device and the second imaging device;
And an adjustment mechanism that adjusts light for the illumination based on the adjustment amount. The inspection apparatus according to claim 1, wherein the optical system for illumination includes a switching mechanism that switches between substantially vertical illumination and oblique illumination,
A half mirror and a condensing lens for condensing light from the sample are arranged in an optical path where the vertical illumination reaches the sample,
The inspection apparatus, wherein the second imaging device images light reflected by the half mirror. The inspection apparatus according to claim 1,
The first imaging device and the second imaging device are inspection devices that are CCD cameras. The inspection apparatus according to claim 1,
The light from the sample is
Collected by the lens,
An inspection apparatus branched by a mirror and imaged by the second imaging apparatus. The inspection apparatus according to claim 1,
The adjustment mechanism is an inspection apparatus having an optical axis adjustment mechanism. The inspection apparatus according to claim 5, wherein
The optical axis adjustment mechanism is
An inspection apparatus comprising a mirror that reflects light for illumination, a tilt mechanism, and a shift mechanism. The inspection apparatus according to claim 6.
The tilt mechanism is a motor;
An inspection apparatus in which the shift mechanism is a stage. The inspection apparatus according to claim 6, wherein
The optical axis adjustment mechanism is
A first mirror, a first tilt mechanism, and a first shift mechanism;
An inspection apparatus having a second mirror, a second tilt mechanism, and a second shift mechanism. The inspection apparatus according to claim 8, wherein
The optical axis adjustment mechanism is
In the optical path behind the first mirror and the second mirror,
An optical element that branches the light in a first direction and a second direction;
An inspection apparatus in which the first imaging device is arranged in the first direction. The inspection apparatus according to claim 1,
The adjustment mechanism is an inspection apparatus having a zoom mechanism and a light amount adjustment mechanism. The inspection apparatus according to claim 1,
Information on the light shift is as follows:
An inspection apparatus which is at least one of the light positional deviation amount, the shape deviation deviation amount, and the brightness deviation amount. The inspection apparatus according to claim 1,
Having a display,
The display unit is an inspection apparatus that displays a tilt amount confirmation image and a shift amount confirmation image. In the testing apparatus of claim 1 2,
The tilt amount confirmation image, and the shift amount confirmation image, the first line and the inspection device being quartered displayed by the second line.

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