JP2011064514A - Scanning probe microscope and surface inspection method - Google Patents

Abstract

Provided are a scanning probe microscope and a surface inspection method capable of forming marking marks on a sample surface without complicating an apparatus configuration.
A marking material having a melting point lower than that of the probe 31 is coated on at least a part of the probe 31 except for a tip portion 33 adjacent to a sample 60, and the marking material 32 is heated to peel off from the probe. Using the scanning probe microscope 100 provided with the marking mark forming means 40 to be attached to the sample surface 60 and forming the marking mark 62 on the sample surface, the tip 33 of the probe 31 is moved close to the sample surface 60 and scanned. When the location 61 is detected, the marking material 32 is heated and peeled off from the probe, and is adhered to the vicinity of the abnormal location to form a marking mark 62 and surface inspection is performed.
[Selection] Figure 2

Description

  The present invention relates to a scanning probe microscope and a surface inspection method using the same.

  A scanning probe microscope typified by a scanning atomic force microscope (AFM) uses an interaction between a sample surface and a probe to detect a fine structure or structure on the sample surface. Device. For this reason, in a scanning probe microscope, a cantilever having a probe attached to the tip of a cantilever is used as a scanning probe.

  When the sample surface is scanned with the probe, an attractive force or a repulsive force based on an atomic force is generated between the sample surface and the probe. At this time, when the cantilever is irradiated with laser light and the position of the reflected light from the cantilever is detected by the photodetector, the position of the reflected light changes according to the amount of strain. If the sample stage is finely moved in the Z-axis direction so that the strain amount is constant, that is, the gap between the sample surface and the probe is constant, the fine movement signal or the detected strain amount at that time is the sample surface. The high-resolution image at the atomic image level can be obtained at the maximum. Furthermore, by utilizing the force acting between the sample and the probe, the distribution of nanoscale magnetic force, surface potential, viscoelastic force, friction force and the like can be measured simultaneously with the shape image. And, by analyzing the abnormal part discovered during the surface inspection of the sample with the scanning probe microscope with another analyzer such as a transmission microscope (TEM), it can be linked to the cause of the abnormality. is there.

  For this reason, an attempt is made to make it easy to specify the measurement position when performing further analysis with other analyzers by attaching marking marks in the vicinity of the abnormal part discovered by surface inspection with a scanning probe microscope Has been made.

  For example, in Patent Document 1 below, surface inspection is performed using a multi-probe scanning probe microscope apparatus provided with an indentation forming probe for forming an indentation on the surface of a sample and a measurement probe for measuring the surface of the sample. It is disclosed that an indentation is formed in the vicinity of a measurement location of a sample with an indentation forming probe.

JP 2002-139414 A

  However, in the scanning probe microscope disclosed in the above-mentioned Patent Document 1, it is necessary to provide an indentation forming probe driving mechanism and a position control mechanism for the indentation forming probe as incidental equipment, so that the apparatus mechanism becomes more complicated, There was a problem that the apparatus cost increased. Furthermore, when the sample surface is a hard material such as Si or metal, the indentation may not be formed on the sample surface even when the indentation forming probe is pressed, which is not versatile.

  Accordingly, an object of the present invention is to provide a scanning probe microscope and a surface inspection method capable of forming marking marks on the surface of a sample without complicating the apparatus configuration.

  In achieving the above object, the scanning probe microscope according to the present invention has a probe at the tip of a cantilever, and scans the tip of the probe close to the sample surface to perform surface inspection of the sample. In the scanning probe microscope to be performed, the probe is coated with a marking material having a melting point lower than that of the probe on at least a part of the probe except for a tip close to the sample, and the marking material is heated to detect the probe. A marking mark forming means is provided for peeling from the needle and adhering to the sample surface to form a marking mark on the sample surface.

  The scanning probe microscope of the present invention preferably includes a mechanism for heating the probe as the marking mark forming means. And as a means to heat, it is preferable to provide the mechanism which irradiates a laser to the said probe, or the mechanism which applies a voltage to the said probe.

  The scanning probe microscope of the present invention preferably includes a mechanism for determining the marking mark forming position by moving the sample stage in the xyz direction as the marking mark forming means.

  The surface inspection method of the present invention is a surface inspection method using the scanning probe microscope, wherein the tip of the probe is scanned close to the sample surface, and the marking material is heated when an abnormal location is detected. The marking mark is formed by peeling off from the probe and adhering to the vicinity of the abnormal portion.

In the scanning probe microscope according to the present invention, a marking material having a melting point lower than that of the probe is coated on at least a part of the probe except the tip close to the sample, and the marking material is heated to adhere to the sample surface. And marking mark forming means for forming marking marks.
According to the scanning probe microscope of the present invention, when an abnormal location or the like is detected while inspecting the sample surface using the cantilever provided with the probe, the sample stage is moved in the xyz direction, The marking material can be heated and peeled off from the probe in the vicinity of the abnormal location and attached to the sample surface to form marking marks, so surface inspection and marking mark formation can be handled with a single cantilever. It is not necessary to separately provide the device mechanism in the vicinity of the sample observation mechanism, so that the device configuration can be simplified and the size can be further reduced. In addition, the marking marks are formed by attaching the marking material to the sample surface, so there is no need to cause damage such as scratches on the sample surface, and a marking mark with a stable shape is always formed regardless of the hardness or material of the sample. it can.
Then, according to the surface inspection method of the present invention, in the scanning probe microscope, after the sample surface is scanned by the cantilever, if an abnormal part is detected on the sample surface, a marking mark can be formed in the scanning probe microscope apparatus. It is possible to form a marking mark which becomes a position clue when the place is further analyzed by another analyzer with high positional accuracy of the spatial resolution order of the scanning probe microscope.

It is a schematic block diagram of the scanning probe microscope of this invention. It is an enlarged view of the cantilever used for the scanning probe microscope. It is a state figure which forms a marking mark on the surface of a test sample. It is an example which formed the marking trace on the surface of the sample.

  The scanning probe microscope of the present invention will be described with reference to FIGS.

  As shown in FIG. 1, a scanning probe microscope 100 according to the present invention includes a sample scanning mechanism 10 for placing and scanning an inspection sample 60, and a base end side of a cantilever 30 to fix the cantilever into a cantilever shape. The cantilever fixing portion 20 to be supported, the cantilever 30, the voltage applying device 40, and the laser oscillation device 50 including the photodetector 52 that irradiates the upper surface of the cantilever 30 and detects the reflected light are mainly configured. Yes.

  Referring also to FIG. 2, the tip 31 of the cantilever 30 is provided with a probe 31 coated with a marking material 32. The cantilever 30 is electrically connected to the voltage application device 40.

  The probe 31 is not particularly limited as long as it has excellent wear resistance, durability, and rigidity. For example, SiN, Si, diamond, etc. are mentioned. Further, the length L2 of the probe 31 is not particularly limited. For example, 10-15 micrometers is preferable.

  The marking material 32 is not particularly limited as long as it has a lower melting point than the probe. Examples of such marking materials include low melting point metals such as Au and Cu, and resin materials such as acrylic resins. The marking material can be appropriately selected according to the type of the test sample 60, and it is preferable to select a material made of a material different from the surface composition of the test sample 60. When the marking material 32 heats the heating by applying a voltage to the cantilever 30 as in this embodiment, if the material of the cantilever is non-conductive, a conductive material is used as the marking material 32. Is preferred.

  The film thickness of the marking material 32 is preferably 1000 nm or less, more preferably 50 to 1000 nm, and particularly preferably 50 to 150 nm. When the film thickness exceeds 1000 nm, the marking material 32 may come into contact with the sample surface when inspecting the sample surface, which may hinder the inspection.

  The marking material 32 is coated on at least a portion of the marking member 32 excluding the tip 33 close to the sample. In order not to reduce the spatial resolution, it is essential that the length L1 of the tip portion 33 of the probe exposed without being coated with the marking material 32 is larger than the radius of curvature of the tip portion 33. When the length L1 of the tip 33 is equal to or less than the radius of curvature of the probe 33, the marking material 32 may come into contact with the sample surface when inspecting the sample surface, which may hinder the inspection. Further, if the length L1 of the tip 33 exceeds 50% of the length L2 of the probe 31, the marking material 32 is reduced, so that a sufficient marking mark may not be formed on the sample surface. Is preferably 50% of the length L2 of the probe 31.

  Examples of the method for coating the marking material 32 include a method in which the marking material is coated on the probe 31 by vapor deposition, CVD, sputtering, or the like in a state where the tip portion 33 of the probe is masked.

  Next, the surface inspection method of the present invention using the scanning probe microscope will be described.

  First, the probe 31 of the cantilever 30 is brought close to or in contact with the surface of the inspection sample 60, the laser 51 is irradiated from the laser oscillation device 50 to the upper surface of the cantilever 30, and the reflected light is detected by the photodetector 52. In this state, when the probe 31 of the cantilever 30 is scanned over the surface of the inspection sample 60, the position of the reflected light of the laser 51 changes according to the movement of the cantilever 30, so that the position information is sequentially detected by the photodetector 52. At the same time as the shape image, nano-scale magnetic force, surface potential, viscoelastic force, and friction force distribution can be obtained.

  When the surface inspection is performed in this way and any abnormal portion is found on the surface of the inspection sample 60, the sample scanning mechanism 10 causes the sample stage to be moved to the xy-state while the probe 31 and the inspection sample 60 are in contact with each other. After moving in the z direction to determine the marking mark formation position, a voltage is applied to the cantilever 30 from the voltage application device 40. By applying a voltage to the cantilever 30, a discharge is generated between the probe 31 and the test sample 60, and the marking material 32 formed on the probe 31 is heated and peeled off as shown in FIG. It adheres to the surface of the inspection sample 60 and becomes a marking mark 62. The voltage application conditions differ depending on the material and film thickness of the marking material 32 and are not particularly limited, and can be adjusted as appropriate.

  There are no particular limitations on the method of forming the marking marks. For example, as shown to Fig.4 (a), the method of arrange | positioning three point marking marks 62 so that the abnormal part 61 of the test sample 60 may be pinched | interposed is mentioned. If three or more marking marks 62 are arranged around the abnormal portion 61, the measurement position can be easily specified when the abnormal portion 61 is further analyzed by another analyzer. Further, as shown in FIGS. 4B and 4C, four or more dot marking marks 62 are arranged so as to sandwich the abnormal portion 61 of the test sample 60, and further, the abnormal portion 61 and the dot marking mark 62 are arranged. By making the distance and the number of marking marks 62 non-identical on the top and bottom and on the left and right, the direction of the abnormal part 61 can be more easily recognized.

  As described above, according to the scanning probe microscope of the present invention, the surface inspection of the sample and the formation of the marking trace can be performed with one cantilever. Can be simplified and further downsizing can be achieved. In addition, the marking marks are formed by attaching the marking material to the sample surface, so there is no need to cause damage such as scratches on the sample surface, and a marking mark with a stable shape is always formed regardless of the hardness or material of the sample. it can.

  According to the surface inspection method of the present invention, after an abnormal part is detected on the sample surface after scanning the sample surface with a cantilever, a marking mark can be formed in the scanning probe microscope apparatus. Thus, a marking mark that becomes a position clue for further analysis can be formed with a high position accuracy of the spatial resolution order of a scanning probe microscope.

  In this embodiment, the voltage applying device 40 is used as the marking mark forming means. However, instead of the voltage applying device 40, a laser irradiation device is provided, and the coating layer 32 is heated by laser irradiation to melt the marking material 32. Alternatively, it may be peeled off and attached to the sample surface. However, the voltage application type using the voltage application device 40 is preferable because the marking can be performed in a shorter time.

  In the following examples, as the laser oscillation device 50, a semiconductor laser (wavelength 660 nm red) was used as a laser light source, and a laser spot diameter of 10 μm was used. Further, a Si wafer having a flat surface was used as the inspection sample 60.

Example 1
Masking 200 nm from the tip of the cantilever (product name “SI-DF20”, manufactured by SII Nanotechnology, material: SiN, length of the probe 31: 12.5 μm, tip radius: 10 nm) and applying acrylic resin A marking material 32 made of an acrylic resin having a thickness of 100 nm was coated on the probe 31 by vapor deposition.
Using this cantilever, the surface shape of the test sample 60 was scanned. The upper surface of the cantilever was irradiated with a laser 51, and the reflected light of the laser from the cantilever was captured by a photodetector 52 and converted into cantilever position information to obtain a shape image. At this time, the laser power was about 3 mW. As a result, in the scanning range of 10 μm × 10 μm, the average surface roughness (Ra) of the surface morphology was about 0.4 nm, and it was confirmed that the surface was extremely flat.
Next, a laser 51 having a laser power of about 100 mW is irradiated on the cantilever for 60 seconds to melt the marking material 32 of the probe 31, and the marking material is adhered to the surface of the inspection sample 60. 62 was formed. The marking portion 62 shown in FIG. 4B was formed by moving the abnormal portion 61 by ± 2 μm in the xy direction from the origin.
Then, when the surface shape was scanned again after the probe 31 was sufficiently cooled, it was confirmed that a convex marking mark 62 having a diameter of about 200 nm and a height of about 50 nm was formed. The marking marks 62 could be easily confirmed with an electron microscope (model number “FE-SEM S-4700”, manufactured by Hitachi, Ltd.).

(Example 2)
Mask gold from the tip of the cantilever (product name “SI-DF20”, manufactured by SII Nanotechnology, material: SiN, length of probe 31: 12.5 μm, tip radius: 10 nm) to detect gold The marking material 32 made of gold having a thickness of 100 nm was coated on the needle 31 by vapor deposition. For the measurement sample, conductive silver paste was applied from a single part of the sample surface to the sample stage of the main body.
Using the cantilever coated with the marking material 32, the surface shape of the test sample 60 was scanned in the same manner as in Example 1. In the scanning range of 10 μm × 10 μm, the average surface roughness (Ra) of the surface morphology was about 0.4 nm, and it was confirmed that the surface was extremely flat.
Next, a voltage of 2 V was applied to the conductive marking material 32 from the voltage applying device 40 for 1 second while the cantilever probe 31 and the surface of the inspection sample 60 were in contact with each other.
At this time, the probe 31 was heated by voltage application, the marking material was peeled off due to the difference in thermal expansion coefficient between the marking material 32 and the cantilever, and adhered to the sample surface, and the marking mark 62 was formed. With the abnormal portion 61 as the origin, the marking mark 62 shown in FIG. 4A is formed by moving by ± 2 μm in the x direction and +2 μm in the y direction.
When the surface shape was scanned again, it was confirmed that a convex marking mark 62 having a diameter of about 150 nm and a height of about 60 nm was formed. The marking marks 62 could be easily confirmed with an electron microscope (model number “FE-SEM S-4700”, manufactured by Hitachi, Ltd.).

DESCRIPTION OF SYMBOLS 10: Sample scanning mechanism 20: Cantilever fixing | fixed part 30: Cantilever 31: Probe 32: Marking material 33: Tip part 40: Voltage application apparatus 50: Laser oscillation apparatus 51: Laser beam 52: Photo detector 60: Inspection sample 61: Abnormal part 62: Marking mark 100: Scanning probe microscope

Claims (5)

A scanning probe microscope that has a probe at the tip of a cantilever and scans the tip of the probe close to the sample surface to inspect the surface of the sample,
The probe is coated with a marking material having a melting point lower than that of the probe on at least a part of the tip excluding the tip close to the sample,
A scanning probe microscope comprising marking mark forming means for heating and marking the marking material from a probe to adhere to the sample surface and forming a marking mark on the sample surface.   The scanning probe microscope according to claim 1, further comprising a mechanism for heating the probe as the marking mark forming unit.   The scanning probe microscope according to claim 2, further comprising a mechanism for irradiating the probe with a laser or a mechanism for applying a voltage as the heating means.   4. The scanning probe microscope according to claim 1, further comprising a mechanism for moving the sample stage in an xyz direction to determine a marking mark forming position as the marking mark forming unit. 5. A surface inspection method using the scanning probe microscope according to any one of claims 1 to 4,
The tip of the probe is scanned close to the sample surface, and when an abnormal location is detected, the marking material is heated and peeled off from the probe, and is attached to the vicinity of the abnormal location to form a marking mark. Surface inspection method.