JP2007096011A - Sample inspection method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sample inspection method which detects sample information when charged particle beam and laser beam are cast on a sample via a conductive probe in contact with the sample. <P>SOLUTION: A prescribed range on a sample 5 is scanned as a scanning region with charged particle beam 11, and the same time the scanning region is scanned at the same time with laser beam 12. A signal from the sample 5 in scanning of both the beams 11, 12 is detected via a conductive probe 8 in contact with the sample 5, and a computer 17 forms an inspection image, based on the detection signal thereby. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a sample inspection method using a charged particle beam and a laser beam.

  2. Description of the Related Art An inspection method for identifying a defective portion such as disconnection has been developed for a sample to be inspected (hereinafter referred to as “sample”) made of a semiconductor having an LSI circuit or the like formed on the surface.

  Among such inspection methods, a method has been studied in which a sample is irradiated with a charged particle beam such as an electron beam and a laser beam, and the sample is inspected in this state.

  For example, in Patent Document 1, an electron beam is irradiated from the wiring layer formation side of a sample, an electric field is generated in the diffusion layer through the wiring layer, and a laser in the infrared wavelength region is scanned or irradiated from the substrate side of the sample. In addition, there is shown a method in which a change in laser reflection intensity or phase is measured and detected by interference with incident light, and a breakage point of the sample is detected according to the measurement result.

  Patent Document 2 discloses that a scanning surface of an electron beam on a sample is scanned with a laser using an apparatus capable of irradiating the sample with an electron beam and a laser.

  In these inspection methods, sample information is acquired by acquiring sample information via a laser beam optical detection system or by detecting secondary electrons generated by irradiation with an electron beam.

JP 2000-311929 A JP-A-9-129169

  As described above, the sample is irradiated with a charged particle beam such as an electron beam and a laser beam, and the sample information at this time is acquired through a laser beam optical detection system or acquired by detecting secondary electrons. A sample inspection method is disclosed.

  However, no examination has been made on a sample inspection method in which sample information when a sample is irradiated with a charged particle beam and a laser beam is directly detected via a conductive probe in contact with the sample.

  The present invention has been made in view of the above points, and detects sample information when a sample is irradiated with a charged particle beam and a laser beam through a conductive probe brought into contact with the sample. An object is to provide a sample inspection method that can be used.

  The first sample inspection method according to the present invention scans with a charged particle beam using a predetermined range on the sample as a scanning region, and simultaneously scans the scanning region with a laser beam via both conductive probes brought into contact with the sample. A signal from the sample at the time of beam scanning is detected, and an inspection image is formed based on the detected signal.

  In the second sample inspection method of the present invention, a predetermined range on the sample is scanned with a charged particle beam as a scanning region, and at the same time, a predetermined spot in the scanning region is spot-irradiated with a laser beam and the conductive material is brought into contact with the sample. A signal from a sample at the time of scanning of a charged particle beam and irradiation of a laser beam is detected through a probe, and an inspection image is formed based on the detection signal thereby.

  In the third sample inspection method according to the present invention, a predetermined range on the sample is scanned with a laser beam, and at the same time, a predetermined portion in the scan region is spot-irradiated with a charged particle beam and the conductive material is brought into contact with the sample. A signal from the sample at the time of laser beam scanning and charged particle beam irradiation is detected through the probe, and an inspection image is formed based on the detected signal.

  In the present invention, a signal from the sample at the time of scanning or irradiating the charged particle beam and laser beam on the sample is detected through a conductive probe brought into contact with the sample, and an inspection image is based on the detection signal obtained thereby. Form.

  Therefore, sample information at the time of scanning or irradiation of both beams can be directly detected via the conductive probe brought into contact with the sample, and further detailed sample information at the time of scanning or irradiation can be acquired. In addition, the position of the sample information can be specified.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram showing an inspection apparatus used for carrying out the present invention.

  In the figure, an electron beam (charged particle beam) 11 is emitted from an electron gun 1 toward a sample 5. The electron beam 11 emitted from the electron gun 1 is irradiated in a state of being focused on the sample 5 by the focusing lens 2 and the objective lens 4.

  At this time, the electron beam 11 is deflected by the two scanning coils 3a and 3b, whereby the electron beam 11 scans a predetermined range on the sample 5 as a scanning region. A scanning signal is supplied from the scanning circuit 14 to the scanning coils 3a and 3b. Based on this, the scanning coils 3a and 3b are driven and the electron beam 11 is deflected.

  From the scanning area of the sample 5 scanned with the electron beam 11, detected electrons (not shown) such as secondary electrons are generated. The detected electrons are detected by the electron detector 9.

  The electron detector 9 outputs a detection signal in response to detection of detected electrons. This detection signal is amplified by the amplifier 15, A / D converted, and then sent to the computer 17. The computer 17 is supplied with a scanning signal from the scanning circuit 14.

  The computer 17 includes an image display unit 17a. The computer 17 can form a scanned image based on the detection signal and the scanning signal, and can display the scanned image on the image display unit 17a.

  Here, the sample 5 is placed on the stage 6. A manipulator 7 is disposed on the stage 6, and the manipulator 7 is provided with a plurality (two in the present embodiment) of conductive probes (hereinafter referred to as “probes”) 8.

  The electron gun 1, the focusing lens 2, the scanning coils 3 a and 3 b, and the objective lens 4 described above are disposed in the electron optical barrel 18. Further, the sample 5, the stage 6, the manipulator 7, and the electron detector 9 are arranged in a sample chamber 19 located on the downstream side of the electron optical column 18.

  A laser microscope 13 is provided below the sample chamber 19. The laser microscope 13 is for irradiating the sample 7 with the laser beam 12 from below. The optical axis of the laser beam 12 from the laser microscope 13 coincides with the optical axis of the electron beam 11.

  Here, an opening (not shown) is formed in the bottom surface 19 a of the sample chamber 19 at a portion facing the lower surface of the sample 7, and the opening is formed by the quartz glass plate 10 disposed on the outer surface of the sample chamber 19. It is blocked. In the stage 6, an opening 6 a formed smaller than the outer shape of the sample 7 is provided in a portion corresponding to the lower surface of the sample 7.

  As a result, the laser beam 12 emitted from the laser microscope 13 irradiates the sample 7 through the quartz glass plate 10, the opening formed in the bottom surface 19 a of the sample chamber 19, and the opening 6 a formed in the stage 6. . Here, when scanning the sample 5 with the laser beam 12, a scanning signal is supplied from the scanning circuit 14 to the laser microscope 13.

  As a result, the sample 5 is scanned or irradiated with the electron beam 11 from one side (upper side) with the upper surface (on the sample) of the sample 5 as a boundary, and the laser beam 12 is scanned or irradiated from the other side (lower side). be able to.

  Reflected light (not shown) generated from the sample 7 irradiated with the laser beam 12 is detected by the laser microscope 13. The detection signal thereby is sent to the computer 17, and a scanning image based on the detection signal and the scanning signal is formed.

  The tip of the probe 8 provided with the manipulator 7 is brought into contact with an arbitrary position on the sample 5. Thereby, sample information such as current flowing through the sample 5 can be directly detected.

  A detection signal such as a current value detected via the probe 7 is amplified by the amplifier 15 and A / D converted, and then sent to the computer 17. The computer 17 can form an inspection image based on the detection signal and the scanning signal, and can display the inspection image by the image display unit 17a.

  The above is the configuration of the inspection apparatus for carrying out the present invention. The sample inspection method according to the present invention will be described below.

  A predetermined range on the sample 5 is scanned with the electron beam 11 as a scanning region, and at the same time, the scanning region is scanned with the laser beam 12. At this time, the tip of the probe 8 is in contact with a predetermined position on the sample 5.

  And the signal from the sample 5 at the time of the scanning of the electron beam 11 and the laser beam 12 is detected through the probe 8 as sample information. The signal (detection signal) detected at this time corresponds to an absorption current flowing through the sample 5 by scanning the electron beam 11.

  A detection signal by the detection is sent to the computer 17 via the amplifier 16. The computer 17 forms an inspection image based on the detection signal and the scanning signal from the scanning circuit 14, and displays the inspection image on the image display unit 17a.

  Here, the scanning of the electron beam 11 and the scanning of the laser beam 12 are synchronized as shown in FIG. As a result, during scanning of both beams 11 and 12, both beams 11 and 12 simultaneously irradiate the same position (same location) in the scanning region on the sample 5.

  By doing in this way, the part irradiated with the electron beam 11 on the sample 5 can always be locally heated by the laser beam 12, and the sample information at this time is directly detected via the probe 8. be able to.

  At this time, by setting the wavelength of the laser beam 12 to 1200 nm or more, the sample 7 is affected only by heating by the laser beam 12. In addition, by setting the wavelength of the laser beam 12 to less than 1200 nm, it is possible to generate an OBIC current at a portion irradiated with the laser beam 12 on the sample 5 and detect the OBIC current including the OBIC current.

  Here, when it is desired to detect sample information by irradiation of the electron beam 11 immediately after the laser beam 12 is irradiated at the same location on the sample 5, as shown in FIG. 3, the scanning timing of the electron beam 11 and the laser are detected. The scanning timing of the beam 12 may be shifted to scan the beams 11 and 12.

  In this case, the timing at which the electron beam 11 arrives (scans with the electron beam 11) by scanning the electron beam 11 at the same location where the beams 11 and 12 reach within the scanning region on the sample 5; There will be a time difference from the timing when the laser beam 12 arrives (irradiates with the laser beam 12) by the scanning of the laser beam 12.

  In each of the above examples, the computer 17 forms a composite image by superimposing the scan image formed based on the detection signal obtained by detecting the detected electrons on the inspection image, and the composite image is displayed on the image display unit 17a. May be displayed.

  A predetermined range on the sample 5 is scanned with the electron beam 11 as a scanning region, and at the same time, a predetermined portion (PN junction portion of the semiconductor element) in the scanning region is spot-irradiated with the laser beam 12. This spot irradiation means that the beam is irradiated in a fixed position. At this time, the tip of the probe 8 is in contact with a predetermined position on the sample 5.

  A signal from the sample 5 at the time of scanning with the electron beam 11 and irradiation with the laser beam 12 is detected through the probe 8 as sample information. The signal (detection signal) detected at this time corresponds to an absorption current generated in the sample 5 by scanning with the electron beam 11 and an excitation current generated in the PN junction of the semiconductor element of the sample 5 by irradiation with the laser beam 12.

  A detection signal by the detection is sent to the computer 17 via the amplifier 16. The computer 17 forms an inspection image based on the detection signal and the scanning signal of the electron beam 11, and displays the inspection image on the image display unit 17a.

  As a result, sample information including the excitation current generated when the laser beam 12 is spot-irradiated on the PN junction of the semiconductor element in the sample 5 and the absorption current generated by scanning the electron beam 11 on the sample 5 is transmitted via the probe 8. Can be detected directly.

  A predetermined range on the sample 5 is scanned with the laser beam 12 as a scanning region, and at the same time, a predetermined portion (wiring portion) in the scanning region is spot-irradiated with the electron beam 11. At this time, the tip of the probe 8 is in contact with a predetermined position on the sample 5.

  Then, a signal from the sample 5 at the time of scanning with the laser beam 12 and irradiation with the electron beam 11 is detected through the probe 8 as sample information. The signal (detection signal) detected at this time corresponds to a current flowing through the wiring portion using the electron beam 11 as a current source.

  A signal by the detection is sent to the computer 17 via the amplifier 16. The computer 17 forms an inspection image based on the detection signal and the scanning signal of the laser beam 12, and displays the inspection image on the image display unit 17a.

  Thereby, the sample information including the current flowing through the wiring portion can be directly detected via the probe 8. And it can be test | inspected whether this wiring part has a disconnection and abnormal resistance.

  The inspection apparatus (see FIG. 1) is an example in which a laser microscope is provided below the sample chamber, but a laser microscope may be provided above the sample chamber.

  In this case, a window portion made of quartz glass is provided on a part of the side surface of the electron optical column arranged on the sample chamber. Here, the periphery of the window portion is airtight. Furthermore, a reflecting mirror located at the same height as the window is disposed inside the electron optical column. This reflecting mirror has an opening through which an electron beam passes.

  Then, a laser beam is scanned or irradiated onto the sample through the window and the reflecting mirror by a laser microscope disposed outside the window of the electron optical column. At this time, the optical axis of the laser beam coincides with the optical axis of the electron beam in the electron optical column. Reflected light generated from the sample by scanning or irradiation with the laser beam reaches the laser microscope through the reflecting mirror and the window and is detected.

  In this example, the sample is scanned or irradiated with the electron beam and the laser beam from the same side (above) with respect to the upper surface of the sample.

  In each of the above embodiments, an electron beam is used as the charged particle beam. However, an ion beam may be used instead of the electron beam.

  As described above, in the present invention, the signal from the sample during scanning or irradiation of the charged particle beam and laser beam on the sample is detected through the conductive probe brought into contact with the sample, and the detection signal by this is detected. Based on this, an inspection image is formed.

  Therefore, sample information at the time of scanning or irradiation of both beams can be directly detected via the conductive probe brought into contact with the sample, and further detailed sample information at the time of scanning or irradiation can be acquired. At the same time, the position of the sample information can be specified.

It is a schematic block diagram which shows the test | inspection apparatus used in order to implement this invention. It is a figure which shows the state which synchronized the scanning of the electron beam and the laser beam. It is a figure which shows the state which shifted the scanning timing of the electron beam, and the scanning timing of the laser beam.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Electron gun, 2 ... Focusing lens, 3a, 3b ... Scanning coil, 4 ... Objective lens, 5 ... Sample, 6 ... Stage, 7 ... Manipulator, 8 ... Probe (conductive probe), 9 ... Electron detector, 10 ... quartz glass plate, 11 ... electron beam (charged particle beam), 12 ... laser beam, 13 ... laser microscope, 14 ... scanning circuit, 15 ... amplifier, 16 ... amplifier, 17 ... computer

Claims (8)

  The scanning area is scanned with a charged particle beam using a predetermined area on the specimen as a scanning area. At the same time, the scanning area is scanned with a laser beam, and a signal from the specimen during scanning of both beams is detected via a conductive probe in contact with the specimen. And a sample inspection method for forming an inspection image based on the detection signal thereby.   The detection electron generated from the sample is detected based on the scanning of the charged particle beam, and the synthesized image is formed by superimposing the scanning image formed based on the detection signal thereby on the inspection image. Item 1. The sample inspection method according to Item 1.   3. The sample according to claim 1, wherein the scanning of the charged particle beam and the scanning of the laser beam are synchronized so that the same portion is simultaneously irradiated with both beams in the scanning region on the sample. Inspection method.   For the same location in the scanning region on the sample, there is a time difference between the timing when the charged particle beam is irradiated by scanning the charged particle beam and the timing when the laser beam is irradiated by scanning the laser beam. The sample inspection method according to claim 1, wherein the sample inspection method is provided.   Scanning with a charged particle beam using a predetermined region on the sample as a scanning region, and simultaneously scanning the charged particle beam and laser beam through a conductive probe that is irradiated with a laser beam at a predetermined location in the scanning region and contacting the sample. A sample inspection method for detecting a signal from a sample at the time of irradiation and forming an inspection image based on the detected signal.   A predetermined area on the sample is scanned with a laser beam, and at the same time, a predetermined portion in the scanning area is spot-irradiated with a charged particle beam, and the laser beam is scanned and the charged particle beam is passed through a conductive probe in contact with the sample. A sample inspection method for detecting a signal from a sample at the time of irradiation and forming an inspection image based on the detected signal.   The sample inspection method according to claim 1, wherein the detection signal detected through the conductive probe is a value of a current flowing through the sample. 8. The sample inspection method according to claim 1, wherein the charged particle beam is scanned or irradiated from one side with the sample as a boundary, and the laser beam is scanned or irradiated from the other side.

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