JP2014178215A - Inspection equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inspection equipment capable of inspecting a defect including a projection defect such as for example a foreign body and a dent defect such as for example a damage, the dent defect not always being allowed to be detected at high sensitivity with the patent literature 1 that performs optical detection with a detection light angle adjusted so as to detect the projection defect at high sensitivity.SOLUTION: An inspection equipment comprises an illumination optical system to obliquely supply P-polarized light to a sample, and a detection optical system to detect light from the sample. The detection optical system has an optical system to detect a projection defect at high sensitivity and an optical system to detect a dent defect.

Description

  The present invention relates to an inspection apparatus that detects a defect (for example, a scratch or a foreign object) on a sample.

  In the semiconductor manufacturing process, defects such as scratches and foreign matter on the wafer affect the product yield. Therefore, it is important to detect defects and feed back the defects to the semiconductor manufacturing process. A so-called inspection device is used for inspecting this defect. The following documents are listed as conventional techniques of the inspection apparatus.

JP 2011-209088 A

  Defects include protrusion defects exemplified by foreign substances and dent defects exemplified by scratches. In Patent Document 1, so-called detection detection is performed, but the present invention has found that when the detection angle is adjusted so as to detect the protrusion defect with high sensitivity, the dent defect cannot always be detected with high sensitivity. The prior art does not give sufficient consideration to this point.

  The present invention includes an illumination optical system that supplies P-polarized light obliquely to a sample, a detection optical system that detects light from the sample, and a processing unit, and the detection optical system is formed from the sample. A condensing lens that condenses the light, a rotatable wave plate for passing the light that has passed through the condensing lens, a polarization beam splitter for branching the light that has passed through the wave plate, and the polarization A first detector for detecting light transmitted through the beam splitter; and a second detector for detecting light reflected by the polarizing beam splitter; and the processing unit includes: If the first signal is detected and the first defect is detected, the first defect is determined as a projection defect, and the second signal from the second detector is detected. When the defect is determined and the second defect is detected, the second defect is recessed. The one characterized in that it is determined that the defect.

  According to the present invention, not only can a protrusion defect exemplified by a foreign substance be detected with high sensitivity, but also a dent defect exemplified by a flaw can be detected.

FIG. 6 is a diagram illustrating Example 1; The figure explaining the detail of the detection optical system. 3 is a flowchart for explaining the first embodiment. The figure explaining the histogram of S / N. FIG. 6 illustrates a display method according to the first embodiment. FIG. 6 is a diagram illustrating a second embodiment.

  Hereinafter, it demonstrates using drawing.

  FIG. 1 is a diagram illustrating an inspection apparatus according to this embodiment. The illumination light 100 is incident on a mirror 104 that can be taken in and out in the direction of an arrow 110, and is configured to switch between substantially vertical illumination and oblique illumination. When illuminating oblique illumination, the mirror 104 is retracted from the optical path, and the illumination light 100 is reflected by the mirrors 105 and 106 and supplied to the wafer 103. When substantially vertical illumination is supplied to the wafer 103, the mirror 104 is disposed in the optical path, and the illumination light is supplied onto the wafer 103 as substantial vertical illumination light.

  The wafer 103 is adsorbed by a rotatable chuck 102, and the chuck 102 is moved in one axis direction by the stage 101.

  Scattered light from the wafer 103 is photoelectrically converted by the detection optical systems 107 and 108, and the photoelectrically converted signal is compared with a threshold value in the processing unit 109, and if it is equal to or greater than the threshold value, it is determined as a defect.

  The detection optical system 108 is arranged with a predetermined elevation angle θ with respect to the wafer 103. The elevation angle θ can be an arbitrary angle, but scattered light from a minute foreign matter is scattered at a relatively low elevation angle, so it may be desirable that the elevation angle θ is an acute angle. The detection optical system 107 is arranged with a higher elevation angle than the detection optical system 108.

  FIG. 2 is a diagram for explaining the details of the detection optical system 108 (the same applies to 107). The detection optical system 108 includes an objective lens 201 that collects scattered light from the wafer 103, a wave plate 202, a polarization beam splitter 203, a lens 204 disposed on the transmission side of the polarization beam splitter 203, and a detector such as a photomultiplier. 205, which constitutes a so-called analyzing optical system. A lens 206 and a detector 207 are arranged on the reflection side of the polarization beam splitter 203. The transmission side of the polarization beam splitter 203 constitutes a channel for detecting foreign matter with high sensitivity, and the reflection side of the polarization beam splitter 203 constitutes a channel for detecting flaws with high sensitivity.

  Next, the flowchart of the present embodiment will be described with reference to FIG. First, a standard wafer in which predetermined standard particles (for example, polystyrene latex spheres) are coated on a mirror surface wafer is mounted on the chuck 102 (step 301).

  Next, P-polarized oblique illumination is applied to the wafer 103 (step 302). Note that the polarization may depend on the type of film on the wafer 103.

  Next, the standard wafer is inspected (step 303).

  Next, the operator or the processing unit 109 monitors the S / N histogram of the signal obtained by the detector 205. Here, a signal S / N histogram will be described with reference to FIG. As shown in FIG. 4A, when the horizontal axis is time and the vertical axis is intensity, noise is expressed by a noise component 4200, and a signal from a standard particle can be expressed by a substantial pulse component 4100. The S / N histogram shown in FIG. 4B is a graph in which the horizontal axis represents brightness and the vertical axis represents frequency.

  If S / N is equal to or greater than the specified value (if the difference ΔB between the histogram of S and the histogram of N is equal to or greater than the specified value), the adjustment is completed (step 305).

  If S / N is less than the specified value, the wave plate 202 is rotated (step 306).

  After the adjustment is completed, the standard wafer is unloaded from the chuck 102, the inspection wafer to be inspected is loaded onto the chuck 102 (307), and inspection by oblique P-polarized light is performed (step 308).

  In the present embodiment, the first detection optical system that detects the projection defect with high sensitivity does not substantially detect the scattered light from the dent defect, and the scattered light from the dent defect is detected first. It can also be expressed as being based on the idea that it will enter the second detection optical system other than the optical system.

  When inspecting the inspection wafer, the processing unit 109 performs defect determination on the signal from the detector 205, and assigns a code that is a protrusion defect exemplified by a foreign object to the signal determined to be defective. To do. Further, the processing unit 109 performs defect determination on the signal from the detector 207, and assigns a code that is a dent defect exemplified by a scratch to the signal determined to be a defect.

  Accordingly, the protrusion defect exemplified by the foreign matter is detected with high sensitivity by the detector 205, and the dent defect exemplified by the scratch other than the foreign matter is also detected by the detector 207.

  Next, an inspection result display method will be described with reference to FIG. FIG. 5 is a diagram for explaining the inspection result obtained by the detection optical system 108. There are several methods for displaying the inspection result. First, as shown in FIG. 5A, the foreign matter 404 and the scratch 405 are displayed on the substantially same wafer map 401 in the substantially same coordinate system.

  The other is a method of separately displaying a wafer map 402 for displaying flaws and a wafer map 403 for displaying foreign objects, as shown in FIG. In FIG. 5B, the coordinate systems of the wafer map 402 and the wafer map 403 are substantially the same, but the maps are different.

  As a display method, the color may be changed depending on the scratches and the foreign matter, the symbols may be changed, and the display may be made easier for the operator to recognize.

  According to the present embodiment, not only the protrusion defect exemplified by the foreign substance but also the dent defect exemplified by the scratch can be detected with high sensitivity.

  Next, Example 2 will be described. In the following, differences from the first embodiment will be mainly described. The present embodiment uses the point that the protrusion defect and the dent defect can be individually detected in the first embodiment, and obtains at least one of the change over time of the protrusion defect and the change over time of the dent defect, and is applied to the sample. This is to judge the abnormality of the processing process.

  FIG. 6 is a diagram for explaining the present embodiment. A wafer map 501 represents a wafer map for a flaw at time t1, and a wafer map 502 represents a wafer map for a foreign substance at time t1.

  A wafer map 503 represents a wafer map for a flaw at time t2, and a wafer map 504 represents a wafer map for a foreign substance at time t2.

  A wafer map 505 represents a wafer map for a flaw at time t3, and a wafer map 506 represents a wafer map for a foreign substance at time t3.

  At time t2, it can be understood that only flaws are increasing, and at time t3, it can be understood that only foreign substances are increasing, and it is possible to judge the abnormality of the processing process applied to the sample more quickly and in detail. It becomes possible.

  In addition, if the processing unit observes at least one time-dependent change in the position and number of foreign substances and at least one time-dependent change in the position and number of flaws, the abnormality of the processing process is substantially automatically monitored. You can also

  As mentioned above, although the Example of this invention was described, this invention is not limited to an Example. For example, the structure shown in FIG. 2 may be applied to the detection optical system 107.

DESCRIPTION OF SYMBOLS 100 ... Illumination light 101 ... Stage 102 ... Chuck 103 ... Wafer 104 ... Mirror 105 ... Mirror 106 ... Mirror 107 ... Detection optical system 108 ... Detection optical system 109 ... processing section

Claims (6)

An illumination optical system for supplying P-polarized light obliquely to the sample;
A detection optical system for detecting light from the sample;
A processing unit,
The detection optical system collects light from the sample, a rotatable wave plate for passing light that has passed through the condenser lens, and a light that passes through the wave plate. A polarizing beam splitter, a first detector for detecting light transmitted through the polarizing beam splitter, and a second detector for detecting light reflected by the polarizing beam splitter,
The processing unit performs defect determination on the first signal from the first detector. When the first defect is detected, the processing unit determines that the first defect is a protrusion defect, and An inspection apparatus that performs defect determination on the second signal from the detector, and determines that the second defect is a dent defect when the second defect is detected. The inspection apparatus according to claim 1,
An inspection apparatus in which the detection optical system is arranged with a predetermined elevation angle with respect to the sample, and the elevation angle is an acute angle. The inspection apparatus according to claim 2,
The processing unit is an inspection apparatus that integrates the protrusion defect and the dent defect into substantially the same coordinate system. The inspection apparatus according to claim 3, wherein
The processing unit is an inspection apparatus that obtains at least one of a change over time of the protrusion defect and a change over time of the dent defect. The inspection apparatus according to claim 1,
The processing unit is an inspection apparatus that integrates the protrusion defect and the dent defect into substantially the same coordinate system. The inspection apparatus according to claim 1,
The processing unit is an inspection apparatus that obtains at least one of a change over time of the protrusion defect and a change over time of the dent defect.