JP2014228496A - Surface defect inspection device and surface defect inspection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve measurement sensitivity to forward scattered light and backward scattered light from an inspection object.SOLUTION: A surface defect inspection device includes: a forward scattered light detection unit 20b including a detection lens 21b for receiving forward scattered light, a total reflection mirror 22b for reflecting forward scattered light passing the detection lens 21b, and a photoelectric transducer 23b for detecting the forward scattered light; and a backward scattered light detection unit 20a including a detection lens 21a for receiving backward scattered light, a total reflection mirror 22a for reflecting backward scattered light passing the detection lens 21a, and a photoelectric transducer 23a for detecting the backward scattered light. The photoelectric transducer 23b detects forward scattered light which passes a direct light transmission part for direct transmission of light, of the detection lens 21b and is separated laterally by the total reflection mirror 22b, and the photoelectric transducer 23a detects backward scattered light which passes a direct light transmission part of the detection lens 21a and is separated laterally by the total reflection mirror 22a.

Description

  The present invention relates to a surface defect inspection apparatus and method, and more particularly to a technique effective for surface inspection that detects foreign matter, scratches, defects, dirt, and the like present on the surface of an inspection object such as a semiconductor wafer.

  In a semiconductor device manufacturing process, a circuit pattern is formed on a semiconductor bare wafer through a number of process steps. Possible causes of a decrease in the yield in this process are defects due to crystals of the semiconductor bare wafer and foreign matters due to the apparatus.

  Therefore, a surface defect inspection device that detects the surface of the semiconductor bare wafer inspects these defects and foreign matters with high sensitivity and high throughput, and outputs classification information such as whether the detected ones are defects or manages them. There is a need.

  This type of surface defect inspection apparatus irradiates the wafer surface with inspection light such as laser light, and detects reflected light or scattered light generated on the wafer surface, thereby removing defects and foreign matter existing on the wafer surface. What is detected is widely known.

  Also, depending on the size and shape of the defect or foreign matter to be detected, the material, the type of film to be deposited on the bare wafer, its film thickness, and the wavelength of the inspection light, the defect and foreign matter that are generated when the inspection light is irradiated The intensity distribution of light scattering is also different.

  As a technique for inspecting the above-described defects and foreign matters, for example, a detector that can adjust the light reception angle of scattered light generated on the wafer surface by irradiating the wafer surface with inspection light capable of adjusting polarization, or a plurality of detections There is a device (see Patent Document 1 and Patent Document 2) in which a container is arranged.

  In addition, as a technique for inspecting defects and foreign matter, for example, there is a technique of measuring specularly reflected light from a non-inspected object at a light receiving angle equal to the incident angle of inspection light (Patent Document 3 and Patent Document). 4).

JP-A-7-146245 JP 2006-47308 A JP 2008-170343 A JP 2001-013080 A

  By the way, in the surface defect inspection apparatus, the surface of the wafer is irradiated with inspection light such as laser light, and scattered light from a defect on a non-inspection object and a foreign substance, that is, any of forward scattering, back scattering, and side scattering. The configuration and arrangement of a light receiver that can efficiently receive light scattered in the direction of the light is important and greatly affects the detection capability.

  In the measurement of the forward scattered light, when the light receiving angle is arranged in the regular reflection direction at an angle equal to the incident angle of the inspection light, the regular reflected light enters the forward scattered light receiver. The above-described defect having a low scattering intensity compared to the regular reflection light intensity and the forward scattered light from the foreign matter are difficult to distinguish on the light receiver and become noise components, thereby reducing the defect detection sensitivity.

  Further, as in Patent Document 3, even the regular reflection light includes the scattered light intensity information from the inspection object, which is a factor of reducing the defect detection sensitivity of the inspection object by the regular reflection light.

  Therefore, for example, in forward scattered light measurement, the detector is arranged by shifting it vertically and horizontally in consideration of the aperture (NA) of the light receiving lens so that regular reflection light does not enter. Yes.

  When measuring specularly reflected light separately from the forward scattered light, the measurement time is divided and measured in order so as not to affect each other. In backscattered light measurement, placing the detector in exactly the same direction as the inspection light such as laser light makes it difficult for the return light from the detection lens to enter the laser body and adversely affect laser oscillation. Similarly, it is possible to cope with such an arrangement that the aperture (NA) of the light receiving lens is shifted and arranged in the vertical and horizontal directions.

  However, there is a problem in that the light receiving efficiency of the light receiver is lowered and the defect detection sensitivity of the inspection object is lowered by disposing the detectors in the vertical and horizontal directions.

  The objective of this invention is providing the technique which can improve the measurement sensitivity with respect to the front scattered light from a to-be-inspected object, and back scattered light.

  The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

  Of the inventions disclosed in the present application, the outline of typical ones will be briefly described as follows.

  That is, the outline of a typical one is applied to a surface defect inspection apparatus and a surface defect inspection method, and has the following characteristics.

  The surface defect inspection apparatus includes an illumination unit, a forward scattered light detection unit, a back scattered light detection unit, a processing device, and a stage. The illumination unit irradiates the inspection object with inspection light. The forward scattered light detection unit detects forward scattered light from the inspection object.

  The backscattered light detection unit detects backscattered light from the inspection object. The processing device processes the results detected by the forward scattered light detection unit and the back scattered light detection unit. The stage supports the object to be inspected.

  The forward scattered light detection unit includes a first detection lens, a first total reflection mirror, and a first photoelectric conversion element. The first detection lens receives forward scattered light from a defect caused by inspection light irradiated on the inspection object from the illumination unit. The first total reflection mirror reflects the forward scattered light that has passed through the first detection lens. The first photoelectric conversion element detects forward scattered light.

  The backscattered light detection unit includes a second detection lens, a second total reflection mirror, and a second photoelectric conversion element. The second detection lens receives backscattered light from a defect caused by inspection light irradiated on the inspection object from the illumination unit. The second total reflection mirror reflects the backscattered light that has passed through the second detection lens.

  The second photoelectric conversion element detects backscattered light. Each of the first detection lens, the second detection lens, the first total reflection mirror, and the second total reflection mirror includes a direct light transmission unit that directly transmits light.

  The first photoelectric conversion element detects the forward scattered light that has passed through the direct light transmitting portion of the first detection lens and is laterally separated by the first total reflection mirror, and the second photoelectric conversion element. The element detects the backscattered light that has passed through the direct light transmitting portion of the second detection lens and is laterally separated by the second total reflection mirror.

  The surface defect inspection method is an inspection method by a surface defect inspection apparatus having a first detection lens, a first total reflection mirror, a second detection lens, and a second total reflection mirror. The first detection lens receives forward scattered light from a defect caused by inspection light irradiated on the inspection object from the illumination unit. The first total reflection mirror reflects the forward scattered light that has passed through the first detection lens.

  The second detection lens receives backscattered light from a defect caused by inspection light applied to the inspection object. The second total reflection mirror reflects the backscattered light that has passed through the second detection lens. In addition, the first detection lens, the second detection lens, the first total reflection mirror, and the second total reflection mirror each have a direct light transmission portion that directly transmits light.

  This surface defect inspection method includes the following steps.

  This is a step of detecting the forward scattered light separated to the side by the first total reflection mirror by the first photoelectric conversion element. In this step, the specular reflection light detection unit detects specular reflection light that passes through the direct light transmission unit of each of the first detection lens and the first total reflection mirror.

  Among the inventions disclosed in the present application, effects obtained by typical ones will be briefly described as follows.

  (1) The detection sensitivity in the inspection object can be improved.

  (2) According to the above (1), it is possible to realize a highly efficient surface defect inspection with a high defect capture rate.

It is explanatory drawing which shows an example of schematic structure of the surface defect inspection apparatus by one embodiment of this invention. It is explanatory drawing which showed an example of intensity distribution of the forward scattered light from a defect. It is explanatory drawing which shows an example of a structure of the optical system which measures the forward scattered light and regular reflection light shown in FIG. 2 simultaneously. It is explanatory drawing which shows an example of intensity distribution of the backscattered light from a defect. It is explanatory drawing which shows the structural example of the optical system which measures the backscattered light shown in FIG. It is explanatory drawing which shows an example of the detection lens provided with the hole. It is explanatory drawing which shows an example of the scanning of the inspection light in the surface defect inspection apparatus of FIG. It is explanatory drawing which shows an example of the determination method of the presence or absence of a defect. It is explanatory drawing which shows an example of the signal strength of regular reflection light. It is a flowchart which shows an example of the inspection process by the surface defect inspection apparatus of FIG. It is a flowchart which shows an example of the process in the defect classification output of the to-be-inspected object by the surface defect inspection apparatus of FIG. It is explanatory drawing which shows an example of the operation screen displayed on the test result display apparatus of FIG. It is explanatory drawing which shows an example of the input screen displayed on the test result display apparatus of FIG.

  In the following embodiments, when it is necessary for the sake of convenience, the description will be divided into a plurality of sections or embodiments. However, unless otherwise specified, they are not irrelevant to each other. There are some or all of the modifications, details, supplementary explanations, and the like.

  Further, in the following embodiments, when referring to the number of elements (including the number, numerical value, quantity, range, etc.), especially when clearly indicated and when clearly limited to a specific number in principle, etc. Except, it is not limited to the specific number, and may be more or less than the specific number.

  Further, in the following embodiments, the constituent elements (including element steps and the like) are not necessarily indispensable unless otherwise specified and apparently essential in principle. Needless to say.

  Similarly, in the following embodiments, when referring to the shape, positional relationship, etc. of components, etc., the shape of the component is substantially the case unless it is clearly specified and the case where it is clearly not apparent in principle. And the like are included. The same applies to the above numerical values and ranges.

  In all the drawings for explaining the embodiments, the same members are denoted by the same reference symbols in principle, and the repeated explanation thereof is omitted. In order to make the drawings easy to understand, even a plan view may be hatched.

<Summary of invention>
The first outline of the present invention is a surface defect inspection apparatus. The surface defect inspection apparatus includes an illumination unit (illumination units 10a and 10b), a forward scattered light detection unit (forward scattered light detection unit 20b), a backscattered light detection unit (backscattered light detection unit 20a), and a processing device (processing device). 50), and a stage (XZθ stage 40).

  The illumination unit irradiates the inspection object (semiconductor wafer 1) with inspection light. The forward scattered light detection unit detects forward scattered light from the inspection object. The backscattered light detection unit detects backscattered light from the inspection object. The processing device processes the results detected by the forward scattered light detection unit and the back scattered light detection unit. The stage supports the object to be inspected.

  The forward scattered light detection unit includes a first detection lens (detection lens 21b), a first total reflection mirror (total reflection mirror 22b), and a first photoelectric conversion element (photoelectric conversion element 23b).

  The first detection lens receives forward scattered light from a defect caused by inspection light irradiated on the inspection object from the illumination unit. The first total reflection mirror reflects the forward scattered light that has passed through the first detection lens. The first photoelectric conversion element detects forward scattered light.

  The backscattered light detection unit includes a second detection lens (detection lens 21a), a second total reflection mirror (total reflection mirror 22a), and a second photoelectric conversion element (photoelectric conversion element 23a).

  The second detection lens receives backscattered light from a defect caused by inspection light irradiated on the inspection object from the illumination unit. The second total reflection mirror reflects the backscattered light that has passed through the second detection lens. The second photoelectric conversion element detects backscattered light.

  In addition, the first detection lens, the second detection lens, the first total reflection mirror, and the second total reflection mirror each have a direct light transmission portion that directly transmits light.

  Then, the first photoelectric conversion element detects the forward scattered light that has passed through the direct light transmitting portion of the first detection lens and is laterally separated by the first total reflection mirror. The second photoelectric conversion element detects the backscattered light that has passed through the direct light transmission portion of the second detection lens and has been laterally separated by the second total reflection mirror.

  The second outline of the present invention is a surface defect inspection method. This surface defect inspection method includes a first detection lens (detection lens 21b), a first total reflection mirror (total reflection mirror 22b), a second detection lens (detection lens 21a), and a second total reflection mirror (total This is a surface defect inspection method using a surface defect inspection apparatus having a reflection mirror 22a).

  The first detection lens receives forward scattered light from a defect caused by inspection light irradiated on the inspection object from the illumination unit. The first total reflection mirror reflects the forward scattered light that has passed through the first detection lens. The second detection lens receives backscattered light from a defect caused by inspection light applied to the inspection object. The second total reflection mirror reflects the backscattered light that has passed through the second detection lens. In addition, the first detection lens, the second detection lens, the first total reflection mirror, and the second total reflection mirror each have a direct light transmission portion that directly transmits light.

  The surface defect inspection method by this surface defect inspection apparatus includes the following steps.

  This is a step of detecting the forward scattered light separated to the side by the first total reflection mirror by the first photoelectric conversion element. In this step, the specular reflection light detection unit detects specular reflection light that passes through the direct light transmission unit of each of the first detection lens and the first total reflection mirror.

  Hereinafter, the embodiment will be described in detail based on the above-described outline.

<Configuration example of surface defect inspection system>
FIG. 1 is an explanatory diagram showing an example of a schematic configuration of a surface defect inspection apparatus according to an embodiment of the present invention.

  As shown in FIG. 1, the surface defect inspection apparatus includes illumination units 10a and 10b, a back scattered light detection unit 20a, a forward scattered light detection unit 20b, a regular reflection light detection unit 30, an XZΘ stage 40, and a processing device 50. doing.

  Here, the configuration of the forward scattered light detection unit 20b, the regular reflection light detection unit 30, and the illumination unit 10b in FIG. 1 will be described with reference to FIGS.

  2A and 2B are explanatory views showing an example of the intensity distribution of the forward scattered light from the defect. FIG. 2A is a side view and FIG. 2B is a plan view.

  A schematic diagram of so-called forward scattering is shown in which the scattered light from the defect 2 caused by the inspection light 3b irradiated on the semiconductor wafer 1 that is the inspection object has a scattering intensity distribution 4b in the regular reflection direction of the inspection light 3b, for example. .

  In order to efficiently receive the above-described forward scattered light, it is necessary to arrange a detection lens in the regular reflection direction of the inspection light 3b. However, the specularly reflected light from the semiconductor wafer 1 is also reflected in the same light receiving angle direction as the incident angle of the inspection light 3b.

<Configuration example of forward scattered light detector>
FIG. 3 is an explanatory diagram showing an example of the configuration of an optical system that simultaneously measures the forward scattered light and the regular reflection light 7 shown in FIG.

  The forward scattered light detection unit 20b is an optical system that receives forward scattered light indicated by an optical path ABC in the drawing. The forward scattered light detection unit 20b includes a detection lens 21b, a total reflection mirror 22b, and a photoelectric conversion element 23b.

  The detection lens 21b receives scattered light from the defect 2 due to the inspection light 3b irradiated from the illumination unit 10b to the semiconductor wafer 1 that is the inspection object. The total reflection mirror 22b is a mirror that reflects almost all light. The photoelectric conversion element 23b photoelectrically converts the received scattered light. Here, for example, a photomultiplier or the like is used as the photoelectric conversion element.

  Here, the detection lens 21b and the total reflection mirror 22b have a configuration in which a gap is formed in the central portion, in other words, in a direction perpendicular to the inspection light incident plane. The gap serves as a direct light transmitting portion that transmits light directly.

  As described above, there is a feature in that the regular reflection light 7 passes through the direct light transmission portion of the detection lens 21b and the total reflection mirror 22b. Further, the forward scattered light detection unit 20 b has a structure that can change the light receiving angle 6 b without being affected by the regular reflection light 7.

  As described above, by adopting a structure in which the regular reflection light 7 passes through the detection lens 21b and the direct light transmission portion in the total reflection mirror 22b, it is possible to efficiently receive only the forward scattered light, that is, the detection sensitivity. Improvements can be made.

  Subsequently, the specular reflection light detection unit 30 is an optical system that receives the specular reflection light 7 indicated by an optical path ABD in the drawing. The regular reflection light detection unit 30 includes a detection lens 31, a transmittance adjustment unit 32, and a photoelectric conversion element 33. The detection lens 31 receives specularly reflected light from the inspection light 3b irradiated to the semiconductor wafer 1 that is the inspection object from the illumination unit 10b.

  The transmittance adjusting unit 32 includes, for example, an ND (Neutral Density) filter and adjusts the amount of light received. The photoelectric conversion element 33 photoelectrically converts the received scattered light. Here, for example, a photomultiplier or the like is used as the photoelectric conversion element in the same manner as the photoelectric conversion element 23b. Further, the regular reflection light detection unit 30 has a structure that automatically adjusts the light reception angle 6b to be the same as the incident angle 5b of the inspection light 3b.

  The illumination unit 10b includes an irradiation lens 11b and a laser device 12b that generates inspection light such as laser light having a predetermined wavelength. The illumination unit 10b irradiates the surface of the semiconductor wafer 1 that is an inspection object with the inspection light 3b. Further, for example, a wavelength plate may be inserted into the irradiation light, and a mechanism for changing the polarization of the inspection light 3b may be provided.

  Then, the structure of the backscattered light detection part 20a and the illumination part 10a is demonstrated using FIG. 4 and FIG.

  FIG. 4 is an explanatory view showing an example of an intensity distribution of backscattered light from a defect, FIG. 4 (a) is a side view, and FIG. 4 (b) is a plan view.

  A schematic diagram of so-called back scattering is shown in which the scattered light from the defect 2 by the inspection light 3a irradiated on the semiconductor wafer as the inspection object has a scattering intensity distribution 4a in the same direction as the incident direction of the inspection light 3a, for example. Yes. In order to receive this backscattered light efficiently, it is necessary to arrange a detection lens in the irradiation direction of the inspection light 3a.

<Configuration example of backscattered light detector>
FIG. 5 shows the configuration of an optical system for measuring the backscattered light shown in FIG.

  The backscattered light detection unit 20a is an optical system that receives backscattered light 7a indicated by an optical path AEF in the drawing. The backscattered light detection unit 20a includes a detection lens 21a, a total reflection mirror 22a, and a photoelectric conversion element 23a. The detection lens 21a that receives light receives the backscattered light 7a from the defect 2 caused by the inspection light 3a irradiated on the semiconductor wafer that is the inspection object from the illumination unit 10a.

  The total reflection mirror 22a is a mirror that reflects almost all light. The photoelectric conversion element 23a photoelectrically converts the received backscattered light 7a. Here, for example, a photomultiplier is used as the photoelectric conversion element 23a.

  Here, the detection lens 21a and the total reflection mirror 22a are excised in the central portion, in other words, in a direction perpendicular to the inspection light incident plane, and the excised portion becomes a direct light transmitting portion that transmits light directly. . A characteristic is that the inspection light 3a passes through the direct light transmitting portion at the center. Further, the backscattered light detection unit 20a has a structure that can change the light receiving angle 6a.

  Also in this case, in the detection of the backscattered light, the inspection light 3a passes through the detection lens 21a and the direct light transmitting portion at the center of the total reflection mirror 22a, so that the inspection light is defective from directly behind the detection lens 21a. Can be irradiated. As a result, the backscattered light can be received efficiently, that is, the detection sensitivity can be improved.

  Here, the inspection light is passed through the detection lens 21b, the total reflection mirror 22b, the detection lens 21a, and the direct light transmission portion which is a region obtained by cutting out the central region of the total reflection mirror 22a. However, the detection lens 21b, the total reflection mirror 22b, the detection lens 21a, and the total reflection mirror 22a may be configured to pass inspection light.

  When the detection lens 21b and the detection lens 21a are divided into two, in order to maintain the lens performance and the like, precise alignment of the two divided lenses is necessary, and the number of work steps is increased. It gets bigger. Further, when the lens alignment accuracy is poor, there is a risk of performance degradation. The same applies to the total reflection mirror 22b and the total reflection mirror 22a.

  Therefore, for example, instead of dividing the detection lens 21b, the total reflection mirror 22b, the detection lens 21a, and the total reflection mirror 22a into two, a hole such as an elliptical or rectangular slit is provided in the center. You may make it pass inspection light.

<Example of detection lens>
FIG. 6 is an explanatory diagram showing an example of the detection lens 21a provided with a hole.

  Although FIG. 6 shows an example of the detection lens 21a, the detection lens 21b, the total reflection mirror 22b, and the total reflection mirror 22a have the same configuration.

  As shown in FIG. 6, a rectangular hole 25 is formed at the center of the detection lens 21a. By providing the hole 25, the detection lens 21a is not divided and is fixed by the peripheral portion of the detection lens 21a, and the lens shape is maintained.

  With this configuration, the detection lens 21b, the total reflection mirror 22b, the detection lens 21a, and the total reflection mirror 22a are fixed without being divided, so that operations such as alignment can be made unnecessary.

<Example of scanning with surface defect inspection equipment>
FIG. 7 is an explanatory view showing an example of scanning of inspection light in the surface defect inspection apparatus of FIG.

  In FIG. 7, the semiconductor wafer 1 adsorbed and supported on the XZθ stage 40 is moved in the θ direction while moving straight in the X direction which is the radial direction of the semiconductor wafer 1 shown in FIG. The entire surface of the wafer 1 is scanned in a spiral shape 9.

  Returning to FIG. 1, the XZθ stage 40 outputs coordinate position information using, for example, a laser scale for detecting the coordinate position in the X direction and a rotary encoder for detecting the coordinate position in the θ direction.

  The processing device 50 includes a coordinate management device 41, amplifiers 51a, 51b, 51c, A / D converters 52a, 52b, 52c, a defect determination device 53, an inspection result storage device 54, an inspection result display device 55, an input device 57, and A threshold setting circuit 58 is provided.

  The coordinate management device 41 outputs the coordinate information to the defect determination device 53 based on the position information input from the XZθ stage 40, that is, the position information of the semiconductor wafer 1.

  The amplifiers 51a, 51b, 51c amplify and output analog signals input from the backscattered light detection unit 20a, the forward scattered light detection unit 20b, and the specular reflection light detection unit 30, respectively. The A / D converters 52a, 52b, and 52c convert the analog signals amplified by the amplifiers 51a, 51b, and 51c into digital signals, respectively, and output the digital signals. Further, for example, the A / D converters 52a, 52b, and 52c may be provided with a digital filtering function for the purpose of noise removal.

  The defect determination device 53 includes determination circuits 53a, 53b, and 53c. These determination circuits 53a, 53b, and 53c receive the threshold value setting circuit 58 from the signals detected by the backscattered light detection unit 20a, the forward scattered light detection unit 20b, and the regular reflection light detection unit 30. Each value is compared with each other to determine the presence or absence of a defect.

  The inspection result storage device 54 stores the inspection result input from the defect determination device 53 and the coordinate information on the semiconductor wafer 1 output from the coordinate management device 41 in association with each other. The inspection results input from the defect determination device 53 are the presence / absence of a defect in the semiconductor wafer 1, the detection signal intensity, and the defect classification type.

<Defect detection principle>
Here, the principle of defect detection will be described with reference to FIGS.

  FIG. 8 is an explanatory diagram illustrating an example of a method for determining the presence / absence of a defect. FIG. 8 shows the relationship between the signal intensity of the defect output from the backscattered light detector 20a or the forward scattered light detector 20b and the threshold value.

  FIG. 8A shows an example of a detection signal when, for example, scattered light from a defect and specular reflection light 7 are simultaneously received by the forward scattered light detection unit 20b, and the defect signal is buried in a noise signal. Indicates an impossible state.

  On the other hand, in the method in which the forward scattered light and the specular reflected light 7 are separately detected by the surface defect inspection apparatus of FIG. 1, the noise signal is reduced as shown in FIG. By setting the threshold value, it is possible to detect defects with high accuracy.

  FIG. 9 is an explanatory diagram showing an example of the signal intensity of the regular reflection light. FIG. 9 shows the signal intensity for one rotation of the stage θ of the regular reflection light 7 output from the regular reflection light detection unit 30.

  Since the light intensity from the regular reflection light 7 is very strong, it is necessary to adjust the amount of light received by the photomultiplier by the transmittance adjusting unit 32, for example. The sensitivity may be lowered by lowering the photomultiplier voltage.

  If the adjustment is not appropriate, as shown in the upper part of FIG. 9, the signal becomes saturated and accurate information cannot be obtained. When the adjustment is appropriate, a waveform signal is obtained as shown in the lower part of FIG.

  Returning to FIG. 1, the input device 57 is an input unit for inputting, for example, a threshold value related to an inspection condition and a non-inspection area range from the periphery of the semiconductor wafer 1, such as an edge cut. The input device 57 also performs input of an inspection condition setting unit 101 in FIG.

  The inspection result display device 55 displays the inspection result information input from the inspection result storage device 54. For example, inspection maps 103a to 107a and signal intensity histograms 103b to 107b shown in the radar chart type classification threshold setting screen 90 of FIG. 12 described later and the inspection result display unit 102 of FIG. 13 are displayed.

<Example of inspection processing>
FIG. 10 is a flowchart showing an example of inspection processing by the surface defect inspection apparatus of FIG.

  First, the semiconductor wafer 1 is loaded into the inspection apparatus. Then, an inspection file related to the first detection system and the second detection system is generated (step S101).

  Here, in FIG. 10, the detector A is the forward scattered light detection unit 20b, and the detector B is the forward scattered light detection unit 20b. The detector C is a backscattered light detection unit 20a that detects side scattered light by turning off the illumination unit 10b, and the detector D is a backscattered light detection unit 20a. The detector E is a forward scattered light detection unit 20b that detects side scattered light by turning off the illumination unit 10a. The first detection system indicates detectors A, B, and C, and the second detection system indicates detectors D and E.

  Further, the contents of the inspection file include wafer inspection light illumination angle, laser power, and inspection information related to the detectors A to E. Here, the inspection information includes a detection angle, a photomultiplier voltage, a threshold value, a setting of an ND filter that is the transmittance adjusting unit 32, and the like.

  At this time, it may be possible to select which one of the backscattered light detection unit 20a, the forward scattered light detection unit 20b, and the regular reflection light detection unit 30 is used. Note that, for example, by utilizing simulation, the optimal incident angles 5a and 5b of the inspection light beams 3a and 3b and the light receiving angles 6a and 6b are determined from the scattering intensity distribution due to the material of the inspection object, the film thickness, the size of the defect, and the like. There is also a way to find a combination.

  For example, when the backscattered light detection unit 20a is selected, the backscattered light detection and the side scattered light detection can be performed by turning off the illumination unit 10b used for the forward scattered light detection unit 20b. be able to. Therefore, in this case, for example, the backscattered light detection unit 20a functions as the detector C.

  On the contrary, when the forward scattered light detection unit 20b is selected, by turning off the illumination unit 10a used for the back scattered light detection unit 20a, forward scattered light detection and side scattered light detection are performed. Is possible. Therefore, for example, the forward scattered light detection unit 20b functions as the detector E. The setting is performed by an inspection condition setting unit 101 in FIG.

  Subsequently, the inspection is started (step S102), the inspection result is displayed (step S103), and it is determined whether there is any abnormality in the inspection map (step S104). If there is an abnormality in the process of step S104, the process returns to the process of step S101, and the threshold value, laser power, photomultiplier voltage, and the like are changed.

  Then, in the process of step S104, the processes of steps S101 to S104 are repeated until there is no map abnormality. When the map is no longer abnormal, the semiconductor wafer 1 is unloaded, and the process ends.

<Example of defect classification processing>
FIG. 11 is a flowchart showing an example of processing in defect classification output of an inspection object by the surface defect inspection apparatus of FIG.

  With reference to FIG. 11, a process for outputting the defect classification of the inspection object on the premise that the inspection conditions of the back scattered light, the forward scattered light, and the side scattered light are completed as described above will be described.

  First, each setting is performed by an inspection condition setting unit 101 in FIG. Subsequently, inspection is performed on the first detection system of FIG. 10, that is, the forward scattered light by the detector A, the specularly reflected light by the detector B, and the side scattered light by the detector C. The scattered luminance information and the like are stored in the inspection result storage device 54 (step S201).

  Then, the second detection system in FIG. 10, that is, the back scattered light by the detector D and the side scattered light by the detector E are inspected (step S202), and the detected coordinates and the scattered luminance information of each scattered light are obtained. The result is stored in the inspection result storage device 54.

  Subsequently, the inspection result display device 55 merges the information obtained from the processing of step S201 and the processing of step S202 (step S203), and the inspection coordinates, the scattered luminance information of each scattered light, and the like are inspected. To remember.

  A SEM (Scanning Electron Microscope) review is performed based on the detected coordinate information obtained in the process of step S203 (step S204). The SEM review performs review and classification of various defects.

  The defect shape and type are classified by SEM review. Is added to the detected coordinate information, and the detected coordinates, the scattered luminance information of each scattered light, and the category number. And the threshold value is determined on the radar chart type classification threshold value setting screen shown in FIG. 12, which will be described later, and stored as a threshold value in the threshold value setting circuit 58 (step S205).

  Then, classification processing is performed based on the classification threshold value (step S206) and displayed on the inspection map (step S207). In addition, the category No. after classification processing. May be output in association with the detected coordinate data.

<Example of operation screen>
FIG. 12 is an explanatory diagram illustrating an example of an operation screen displayed on the inspection result display device of FIG. FIG. 12A shows an example of a radar chart type classification threshold setting screen, and FIG. 12B shows an example of a category determination table.

  The radar chart type classification threshold setting screen 90 is displayed as a GUI (Graphical User Interface) as shown in FIG. The radar chart type classification threshold value setting screen 90 is used when setting the classification threshold value in the process of step S205 of FIG. 11 described above.

  The scattering intensity of the forward scattered light is item 93, the scattering intensity of the backward scattered light is item 95, the scattered intensity of the side scattered light detected simultaneously with the forward scattered light is item 94, and the side scattered light detected simultaneously with the backward scattered light. The scattered intensity is taken as an item 96 and arranged so that the scattered light from the object to be detected can be visually recognized. For example, the measured scattered intensity is plotted as shown by a broken line 98.

  Item 93 is the scattering intensity of the forward scattered light by detector A, for example, and item 94 is the scattering intensity of the side scattered light detected simultaneously with the forward scattered light by detector C, for example. Item 95 is, for example, the scattering intensity of the backscattered light by the detector D, and item 96 is the scattering intensity of the side scattered light detected simultaneously with the backscattered light by the detector E, for example.

  At this time, a category such as a scratch luminance distribution or a foreign substance luminance distribution can be changed by selecting a category number from the “Read” button 91 of “Class”, and a solid line 97 in FIG. The threshold indicated by can be set.

  When the category classification table button 99 is pressed, a category determination table 900 is displayed as shown in FIG. The number of classifications is, for example, 16 because a threshold value is set for each of the four detectors A, C, D, and E to determine presence / absence of detection.

  As described above, since the side scattered light can be detected, a category classification function is provided based on the tendency of each scattered light intensity of the defect. Therefore, it is possible to detect defects that are difficult to detect or have missed, increase the capture rate, and add classification information, thereby contributing to improvement in yield in the semiconductor manufacturing process.

  As shown in FIG. 12B, in the category determination table 900, a table 901 displays the 16 combinations described above. The (Class No.) allocation status is displayed. The category determination table 900 is stored by inputting a file name to the classification threshold setting storage 92.

  In FIG. 12A, it can be visually confirmed that the scattering intensity of the forward scattered light exceeds the threshold value indicated by the solid line 97 in the inspection result of each scattering intensity indicated by the broken line 98. Thus, since all the inspection results can be displayed simultaneously, it is possible to perform a highly efficient surface defect inspection with a high defect capture rate.

<Example of input screen>
FIG. 13 is an explanatory diagram showing an example of an input screen displayed on the inspection result display device of FIG.

  The operation screen 100 is displayed as a GUI. The operation screen 100 includes an inspection condition setting unit 101, an inspection result display unit 102, and a defect classification condition setting unit 108, as illustrated. The inspection condition setting unit 101 inputs and sets items necessary for generating the above-described inspection file. The inspection file is information set in the process of step S101 in FIG.

  The inspection result display unit 102 includes an inspection map 103a and a signal intensity histogram 103b, an inspection map 104a and a signal intensity histogram 104b, an inspection map 105a and a signal intensity histogram 105b, an inspection map 106a and a signal intensity histogram 106b, and an inspection map 107a and a signal. Intensity histograms 107b are respectively displayed.

  The inspection map 103a is an inspection map detected by the forward scattered light detection unit 20b, and the signal intensity histogram 103b indicates the distribution of signal intensity and frequency in the inspection map 103a.

  The inspection map 104a is an inspection map detected by the regular reflection light detection unit 30, and the signal intensity histogram 104b shows the distribution of signal intensity and frequency in the inspection map 104a.

  The inspection map 105a is an inspection map detected at the same time by the forward scattered light detection unit 20b, and the signal intensity histogram 105b shows the distribution of signal intensity and frequency in the inspection map 105a.

  The inspection map 106a is an inspection map detected by the backscattered light detection unit 20a, and the signal intensity histogram 106b indicates the distribution of signal intensity and frequency in the inspection map 106a.

  The inspection map 107a is an inspection map detected at the same time by the backscattered light detection unit 20a, and the signal intensity histogram 107b shows the distribution of signal intensity and frequency in the inspection map 107a.

  Enlarged buttons 110 are provided in the display frames of the inspection maps 103a, 104a, 105a, 106a, 107a, respectively, and the result list buttons are displayed in the display frames of the signal intensity histograms 103b, 104b, 105b, 106b, 107b. 111 are provided.

  The enlargement button 110 is a button for displaying each inspection map in an enlarged manner by pressing the enlargement button 110. When the result list button 111 is pressed, detection coordinates (X, Y) on the semiconductor wafer and signal intensity information are displayed. At this time, the category numbers classified as defects may be displayed in association with each other, and the inspection map may be displayed with the category numbers displayed in different colors.

  A defect classification condition setting unit 108 is displayed below the inspection result display unit 102. The defect classification condition setting unit 108 includes an inspection data reading 108a, an SEM classification data reading 108b, a teaching button 108c, a classification threshold setting screen button 108d, and a classification threshold file selection 108e.

  The inspection data reading 108a reads the inspection result stored in the inspection result storage device 54 of FIG. The SEM classification data reading 108b reads data classified by the SEM and added with a category number.

  The teaching button 108c associates inspection data with SEM classification data. The classification threshold setting screen button 108d displays the radar chart type classification threshold setting screen of FIG. The classification threshold file selection 108e sets a classification threshold used at the time of surface defect inspection.

  As described above, the detectors A and D, which are detection systems that detect forward and backscattered light from the semiconductor wafer that is the object to be inspected, the detector B that is a detection system that detects specularly reflected light, and the two detection systems. By having the detectors C and E capable of simultaneously detecting side scattered light by selection, the inspection result can be displayed simultaneously.

  Thereby, according to this Embodiment, the detection sensitivity in a surface defect inspection apparatus can be improved, and a highly efficient surface defect inspection can be implement | achieved.

  As mentioned above, the invention made by the present inventor has been specifically described based on the embodiment. However, the present invention is not limited to the embodiment, and various modifications can be made without departing from the scope of the invention. Needless to say.

  In addition, this invention is not limited to above-described embodiment, Various modifications are included. For example, the above-described embodiment has been described in detail for easy understanding of the present invention, and is not necessarily limited to one having all the configurations described.

  Further, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. . In addition, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

DESCRIPTION OF SYMBOLS 1 Semiconductor wafer 2 Defect 3a Inspection light 3b Inspection light 4a Scattering intensity distribution 4b Scattering intensity distribution 5a Incident angle 5b Incident angle 6a Light receiving angle 6b Light receiving angle 7 Regular reflection light 7a Back scattered light 9 Spiral shape 10a Illumination part 10b Illumination part 11b Irradiation Lens 12b Laser device 20a Backscattered light detection unit 20b Forward scattered light detection unit 21a Detection lens 21b Detection lens 22a Total reflection mirror 22b Total reflection mirror 23a Photoelectric conversion element 23b Photoelectric conversion element 30 Regular reflection light detection unit 31 Detection lens 32 Transmittance Adjustment unit 33 Photoelectric conversion element 40 XZθ stage 41 Coordinate management device 50 Processing device 51a Amplifier 51b Amplifier 51c Amplifier 52a A / D converter 52b A / D converter 52c A / D converter 53 Defect determination device 53a Determination circuit 53b Determination circuit 53c judgment circuit 54 inspection result storage device 55 Inspection Result Display Device 57 Input Device 58 Threshold Setting Circuit 90 Radar Chart Type Threshold Setting Screen 91 Button 92 Classification Threshold Setting Save 93 Item 94 Item 95 Item 96 Item 97 Solid Line 98 Dashed Line 99 Category Classification Table Button 100 operation screen 101 inspection condition setting unit 102 inspection result display unit 103a inspection map 103b signal intensity histogram 104a inspection map 104b signal intensity histogram 105a inspection map 105b signal intensity histogram 106a inspection map 106b signal intensity histogram 107a inspection map 107b signal intensity histogram 108 defect Classification condition setting unit 108a Inspection data reading 108b SEM classification data reading 108c Teaching button 108d Classification threshold setting screen button 108e Classification threshold file Selection 110 Expand button 111 Result list button 900 Category determination table 901 Table

Claims (16)

An illumination unit that irradiates the inspection object with inspection light; and
A forward scattered light detection unit for detecting forward scattered light from the inspection object;
A backscattered light detection unit for detecting backscattered light from the inspection object;
A processing device for processing results detected by the forward scattered light detection unit and the back scattered light detection unit;
A stage for supporting the inspection object;
Have
The forward scattered light detection unit is
A first detection lens that receives forward scattered light from a defect caused by inspection light applied to the inspection object from the illumination unit;
A first total reflection mirror that reflects forward scattered light that has passed through the first detection lens;
A first photoelectric conversion element for detecting the forward scattered light;
Have
The backscattered light detection unit is
A second detection lens that receives backscattered light from a defect caused by inspection light applied to the inspection object from the illumination unit;
A second total reflection mirror that reflects backscattered light that has passed through the second detection lens;
A second photoelectric conversion element for detecting the backscattered light;
Have
The first detection lens, the second detection lens, the first total reflection mirror, and the second total reflection mirror each have a direct light transmission part that directly transmits light,
The first photoelectric conversion element detects forward scattered light that has passed through the direct light transmission portion of the first detection lens and is laterally separated by the first total reflection mirror,
The second photoelectric conversion element detects a backscattered light that passes through the direct light transmitting portion of the second detection lens and is laterally separated by the second total reflection mirror. apparatus. In the surface defect inspection apparatus according to claim 1,
The direct light transmission part of the first and second detection lenses is a hole formed in a central part of the lens,
The surface defect inspection apparatus, wherein the direct light transmission portion of the first and second total reflection mirrors is a hole formed in a central portion of the mirror. In the surface defect inspection apparatus according to claim 1,
The direct light transmission part of the first and second detection lenses is a space obtained by cutting a central part of the lens,
The direct light transmitting portion of the first and second total reflection mirrors is a surface defect inspection apparatus, which is a space obtained by cutting a central portion of the mirror. In the surface defect inspection apparatus according to claim 1,
Furthermore, it has a regular reflection light detection unit for detecting regular reflection light,
The said regular reflection light detection part is a surface defect inspection apparatus which detects the regular reflection light which passes through the said direct light transmission part which the said 1st detection lens and said 1st total reflection mirror each have. In the surface defect inspection apparatus according to claim 1,
In the second photoelectric conversion element, the inspection light irradiated from the illumination unit passes through the direct light transmission unit included in the second detection lens and the second total reflection mirror, respectively, and the inspection target A surface defect inspection device that detects backscattered light that is irradiated onto an object and reflected by the second total reflection mirror. In the surface defect inspection apparatus according to claim 1,
The backscattered light detection unit detects side scattered light from the inspection object when detecting the forward scattered light by the illumination unit and the forward scattered light detection unit,
The said front scattered light detection part is a surface defect inspection apparatus which detects the side scattered light from the said to-be-inspected object in the case of the detection of the said back scattered light by the said illumination part and the said back scattered light detection part. In the surface defect inspection apparatus according to claim 1,
The stage is a surface defect inspection apparatus which moves in a radial direction of the inspection object while rotating the inspection object supported when the inspection light is irradiated onto the inspection object. In the surface defect inspection apparatus according to claim 1,
The front scattered light detection unit is a surface defect inspection apparatus in which a light receiving angle for receiving the forward scattered light can be varied. In the surface defect inspection apparatus according to claim 4,
The surface reflection inspection apparatus, wherein the regular reflection light detection unit is movable so that an incident angle of the inspection light is equal to a light reception angle of the regular reflection light detection unit. In the surface defect inspection apparatus according to claim 1,
The said backscattered light detection part is a surface defect inspection apparatus which can change the light reception angle which light-receives the said backscattered light. In the surface defect inspection apparatus according to claim 1,
The said backscattered light detection part is a surface defect inspection apparatus which moves so that the incident angle of the said inspection light and the light reception angle of the said backscattered light detection part may become equal. A first detection lens that receives forward scattered light from a defect caused by inspection light irradiated on the object to be inspected from the illumination unit, and a first total reflection mirror that reflects forward scattered light that has passed through the first detection lens A second detection lens that receives backscattered light from a defect caused by inspection light irradiated on the inspection object, and a second total reflection mirror that reflects backscattered light that has passed through the second detection lens And each of the first detection lens, the second detection lens, the first total reflection mirror, and the second total reflection mirror has a direct light transmitting portion that directly transmits light. A surface defect inspection method using a defect inspection apparatus,
Detecting forward scattered light separated laterally by the first total reflection mirror by a first photoelectric conversion element;
Detecting specularly reflected light that passes through the direct light transmitting part of each of the first detection lens and the first total reflection mirror by a specularly reflected light detecting part;
A surface defect inspection method. The surface defect inspection method according to claim 12,
Further, the surface defect inspection method includes a step of detecting, by a second photoelectric conversion element, the backscattered light received by the second detection lens and laterally separated by the second total reflection mirror. The surface defect inspection method according to claim 13.
Further, the scattering of the inspection object is performed based on the light scattering intensity detected by the first and second photoelectric conversion elements and the classification threshold value for classifying the scattering tendency of the inspection object by the processing device. A surface defect inspection method comprising the step of classifying a trend. The surface defect inspection method according to claim 14,
Furthermore, in the said processing apparatus, the surface defect inspection method which has a step which outputs the classification threshold value setting graph which displays the classification result of the scattering tendency of the said to-be-inspected object, and the said classification threshold value. The surface defect inspection method according to claim 15,
The classification threshold setting graph includes the scattering intensity of the forward scattered light, the scattering intensity of the backward scattered light, the scattered intensity of the side scattered light detected when detecting the forward scattered light, and the backward scattered light. A surface defect inspection method that is a radar chart in which each item of the scattered intensity of side scattered light detected at the time of detection is taken as an axis and the origins are combined into one.

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