JP2008232983A - SPM and SPM measurement method - Google Patents

Abstract

The present invention relates to an SPM and an SPM measuring method, and an object thereof is to provide an SPM and an SPM measuring method capable of performing flow rate control capable of preventing condensation and controlling atmospheric temperature. .
A sample chamber comprising a first cell 18 having a gas inlet and a second cell 17 communicating with the first cell 18 and having a cantilever 1 disposed therein is provided in the sample chamber. In the SPM provided with the gas discharge port, the temperature adjusting means 23 disposed in the first cell and the SPM measuring means for performing SPM measurement in the second cell 17 are provided. .
[Selection] Figure 1

Description

  The present invention relates to SPM and a method for measuring SPM. More specifically, when a constant dew point gas controlled to a high dew point or a low dew point is introduced into a sample chamber, the ambient temperature around the sample is controlled instead of the sample temperature. The present invention relates to an SPM and an SPM measurement method when performing SPM measurement in a heated atmosphere.

  The scanning probe microscope (SPM) generates a local stimulus from the probe to the sample when the probe is scanned relative to the sample in a state where the probe and the sample are brought close to each other. It is a microscope that observes the surface of a sample by measuring a local response from the sample surface. SPM includes a scanning tunneling microscope (STM) that detects the current flowing between the probe and the sample due to the difference in the measurement method of the physical quantity, and the interatomic force that detects various forces acting between the sample surface and the probe. Many types of microscopes that measure friction force, viscosity, elasticity, electric potential, etc. between samples have been put into practical use, including a force microscope (AFM) and a magnetic force microscope (MFM) that measures the magnetic distribution on the sample surface.

  FIG. 3 is a diagram showing a configuration example of a conventional apparatus, and an FM detection type NC-AFM (non-contact AFM) is used as an observation mode. The back surface of the cantilever 1 is irradiated with laser light from a laser diode (LD) 2, and the reflected light is detected by a photodetector (photodetector) 3. The vibration displacement of the cantilever 1 is detected by this optical lever system, and is electrically amplified by a preamplifier 4 incorporating a bandpass filter.

  The displacement signal of the cantilever 1 converted into an electric signal is assembled with a loop that is input to the excitation PZT via the amplifier 5 with an adjustment function. Although not shown, a phase shifter is also incorporated in this loop, and is set to positively oscillate at the natural frequency of the cantilever 1. The amplifier 5 is controlled by AGC (automatic gain control) or the like so that the vibration amplitude of the cantilever or the voltage amplitude input to the excitation PZT 6 is constant.

On the other hand, the oscillation waveform is branched halfway and input to an FM demodulator (demodulator) 7 constituted by a PLL, and a voltage corresponding to the oscillation frequency is output (f / V conversion). As the FM demodulator 7, for example, a PLL is generally used. The gradient of force F ′ acting between the tip and the sample and the natural frequency fo of the cantilever with spring constant k are:
fo∝√ (k−F ′)
And the change in fo (frequency shift) substantially corresponds to F ′.

  The Z motion of the PZT scanner 11 is controlled via the filter 9 and the Z piezo driver 10 so that the error amplifier 8 shifts the signal corresponding to the f / V converted frequency by a certain amount from the natural frequency. (Feedback 1). The frequency shift held constant is the reference voltage Ref. Set by V12. The signal (the output of the filter 9) controlling the Z motion at this time corresponds to the topography signal, and the PZT scanner 11 is scanned two-dimensionally by the scan signal (X, Yscan) 13. A Topo image can be obtained by using the Z motion of the image as a luminance signal.

  In such an SPM, when humidity control is performed, the SPM unit is disposed in the sealed container 14, and a dew point controlled gas from the constant dew point gas supply device 15 is introduced into the sealed container 14 to control the humidity. To do. In the case of the apparatus shown in FIG. 3, since the entire apparatus is exposed to a high humidity atmosphere, in order to avoid this, the upper sealed cell 17 and the lower sealed cell 18 are surrounded around the sample 16 and the cantilever 1 as shown in FIG. There is a method of controlling the humidity in the enclosure.

  The upper closed cell 17 and the lower closed cell 18 are connected by an elastic seal 19 because their distance changes when the cantilever 1 is brought close to the sample 16. The upper closed cell 17 is provided with a window 20 through which the cantilever 1 and the vibration PZT 6 transmit laser light, as in FIG. A humidity meter 21 is used to measure the humidity around the sample 16, and the dew point is converted.

  A conventional device of this type includes a cantilever having a minute probe at the tip, a displacement detecting means for detecting the displacement of the cantilever, and a sample moving means for moving the sample, and at least the cantilever and the sample And means for separating the vacuum chamber into a vacuum chamber first chamber in which the cantilever and the sample are installed and a vacuum chamber second chamber in which the sample moving device is disposed. An equipped device is known (for example, see Patent Document 1).

Also, in the scanning probe microscope, the humidity around the sample can be accurately controlled from the high vacuum state to the saturated water vapor amount, and the high humidity is measured at the same place as the frictional force image measured in the low humidity state. An apparatus for measuring the hydrophilic / hydrophobic distribution on the sample surface by comparing the frictional force images measured for the state is known (see, for example, Patent Document 2).
Japanese Patent Laying-Open No. 2005-283188 (paragraphs 0022 to 0030, FIG. 1) Japanese Patent Laid-Open No. 10-19908 (paragraphs 0009 to 0016, FIG. 4)

  When the high dew point gas is introduced by the apparatus shown in FIG. 4 described above, there is a problem that dew condensation occurs inside the closed container or the closed cell, and a constant dew point cannot be maintained. In addition, when the low dew point gas is introduced, the atmospheric temperature cannot be controlled, so that there is a problem that the humidity cannot be increased. In addition, there is a problem that the influence of vibration due to gas flow appears in image observation.

  The present invention has been made in view of such a problem, and is capable of preventing condensation, controlling the ambient temperature, and controlling the flow rate so that the influence of gas flow does not appear in image observation. An object of the present invention is to provide an SPM dew point control method and apparatus that can be performed.

(1) The invention according to claim 1 comprises a sample chamber comprising a first cell having a gas inlet and a second cell communicating with the first cell and having a cantilever disposed therein, In the SPM measurement method using SPM in which a gas discharge port is provided in a sample chamber, temperature adjusting means is disposed in the first cell, and the gas introduced into the first cell from the gas introduction port is The temperature is adjusted to a predetermined temperature by the temperature adjusting means, and the temperature-controlled gas is supplied to the second cell so that the SPM can be measured in the predetermined temperature atmosphere in the second cell. It is characterized by that.
(2) The invention described in claim 2 is characterized in that the gas inlet and the gas outlet to the sample chamber are sealed at the time of SPM measurement.
(3) The invention described in claim 3 comprises a sample chamber comprising a first cell having a gas inlet and a second cell communicating with the first cell and having a cantilever disposed therein, In the SPM in which a gas discharge port is provided in the sample chamber, the temperature adjusting means disposed in the first cell and the SPM measuring means for performing SPM measurement in the second cell are provided. Features. (4) The invention described in claim 4 is characterized in that the gas inlet and the gas outlet to the sample chamber are sealed at the time of SPM measurement.
(5) The invention described in claim 5 is characterized in that a hot water bath maintained at a dew point temperature is provided in the sample chamber in order to perform high dew point control.
(6) The invention described in claim 6 is characterized in that the hot water bath is provided with vaporization excitation means.

(1) According to the first aspect of the present invention, condensation can be prevented, the ambient temperature can be controlled, and the flow rate can be controlled without the influence of the gas flow appearing in the image observation. .
(2) According to the invention described in claim 2, it is possible to prevent vibration due to gas flow in the sample chamber during SPM observation.
(3) According to the invention described in claim 3, the ambient temperature can be controlled by supplying the constant dew point gas whose temperature is adjusted from the gas supply means into the first cell. It is possible to perform flow rate control without the influence of the flow appearing in the image observation.
(4) According to the invention described in claim 4, it is possible to prevent vibration due to gas flow in the sample chamber during SPM observation.
(5) According to the invention described in claim 5, it is possible to correct a dew point change due to condensation in a constant dew point gas introduction line or the like.
(6) According to the invention described in claim 6, water can be efficiently vaporized to a saturated water vapor pressure.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of the main part of the present invention. The same components as those in FIG. 4 are denoted by the same reference numerals. Here, a configuration for realizing a high dew point atmosphere in SPM measurement will be described. A cantilever 1 and a laser transmitting window 20 to which a vibration PZT 6 is attached are attached to an upper closed cell (second cell) 17, and a heater 22 (heater 1) is a window for preventing condensation at the window 20. It is attached around the frame.

  The upper closed cell 17 is connected to communicate with a lower closed cell (first cell) 18 through an elastic seal 19. As a result, the airtightness around the sample 16 is maintained. A heat radiating cylinder 29 in which a heater 23 (heater 2) is embedded is provided in the lower sealed cell 18, and the heater is used to keep the temperature of the thermometer 21 for measuring the temperature and humidity in the cell at a set temperature. 2 is controlled, and the ambient temperature in the cell is controlled. That is, the temperature value measured by the thermometer 21 enters one input of the temperature controller 30. A temperature set value is given to the other end of the temperature controller 30. The temperature controller 30 controls the heater 2 so that the temperature measured by the thermometer 21 becomes equal to the temperature set value. Here, the upper closed cell 17 and the lower closed cell 18 constitute a sample chamber.

  A constant dew point gas from a high dew point gas generator (not shown) is introduced into the lower sealed cell 18 via a copper mesh wire 31 and a heat resistant tube 32. Then, the gas is discharged from the discharge port 28 of the upper closed cell 17. The atmospheric temperature in the cell is set to be higher than the dew point temperature of the introduced constant dew point gas. In order to vary the humidity in the cell while maintaining the dew point, the ambient temperature is changed and adjusted to a predetermined humidity.

  According to this embodiment, the constant dew point gas from the high dew point gas generator is supplied into the upper closed cell 17 via the lower closed cell 18 to control the ambient temperature in the cell. Therefore, it is possible to control the flow rate so that the influence of the gas flow does not appear in the image observation. Further, according to this embodiment, during the SPM measurement, inflow of gas introduced into the cell and discharge of gas from the discharge port 28 are completely closed in order to suppress the influence of vibration due to the flow of the constant dew point gas. Try to end up. By doing in this way, the influence of the vibration by the flow of constant dew point gas can be suppressed.

  In the above-described embodiment, the SPM atmosphere control using the high dew point gas has been described. However, the present invention is not limited to this, and the SPM atmosphere control using the low dew point gas can be similarly applied. it can. In this case, in the observation at around 0 ° C., the portion cooled by the refrigerant is connected to the heat radiating tube 29 by a heat conductor such as copper foil, and an atmosphere near 0 ° C. can be obtained by temperature control.

  FIG. 2 is a block diagram showing another embodiment of the main part of the present invention. The same components as those in FIG. 1 are denoted by the same reference numerals. In this embodiment, in order to completely eliminate the influence of the gas flow, when the valve 24 is closed and the inside of the cell is completely sealed, dew condensation occurs when the inner wall temperature is lower than the dew point, and a hot water bath is used to suppress a decrease in the dew point. 25, and the water temperature is kept at the dew point temperature by the heater 26. When the dew point is drastically reduced, the hot water bath 25 is vibrated by the liquid surface vibration PZT (vaporization excitation means) 27 to induce the generation of water vapor. In addition, the constant dew point gas entering through the valve 24 is discharged from the discharge port 28 provided with the valve 35. In this way, by allowing a constant constant dew point gas to flow into and out of the sample chamber, the sample chamber can be maintained at a constant constant dew point temperature.

  If comprised in this way, the dew point change by the dew condensation in a fixed dew point gas introduction line etc. can be correct | amended by providing the hot water bath 25 hold | maintained by the dew point temperature in the sample chamber. Moreover, by providing the vaporization excitation means 27 for the hot water bath 25, water can be efficiently vaporized to the saturated vapor pressure.

  In each of the above examples, the upper closed cell 17 is provided with the discharge port 28. However, the discharge port may be provided in one or both of the upper closed cell 17 and the lower closed cell 18, thereby A discharge port is provided in the sample chamber.

Thus, according to the present invention, the following effects can be obtained.
1) Since a radiator tube with a heater for controlling the ambient temperature is installed in an airtight cell and can be set to a temperature higher than the dew point temperature, condensation on the wall surface can be prevented and a decrease in the dew point temperature can be avoided. . Furthermore, by providing a heater in the laser transmission window, it is possible to prevent condensation that prevents transmission. This enables SPM observation in a high dew point atmosphere.
2) Since the ambient temperature can be set to around 0 ° C. by connecting a refrigerant or the like to the radiating cylinder, humidity control at the ambient temperature is possible.
3) By providing a valve at the gas inlet / outlet of the cell, the gas flow rate can be controlled, and the influence of vibration due to the gas flow in the SPM measurement can be reduced.

It is a block diagram which shows one Embodiment of the principal part of this invention. It is a block diagram which shows other embodiment of the principal part of this invention. It is a figure which shows the structural example of a conventional apparatus. It is a figure which shows the structural example of the principal part of a conventional apparatus.

Explanation of symbols

1 Cantilever 6 PZT for vibration
11 PZT scanner 16 Sample 17 Upper sealed cell 18 Lower sealed cell 19 Elastic seal 20 Window 21 Greenhouse meter 22 Heater 1
23 Heater 2
25 Copper mesh wire 26 Heat-resistant tube 28 Discharge port 29 Radiator tube 30 Temperature controller

Claims (6)

An SPM having a sample chamber comprising a first cell having a gas inlet and a second cell communicating with the first cell and having a cantilever disposed therein, the gas chamber having a gas outlet In the SPM measurement method using
A temperature adjusting means is disposed in the first cell;
The gas introduced into the first cell from the gas inlet is adjusted to a predetermined temperature by the temperature adjusting means,
The temperature-controlled gas is supplied to the second cell;
SPM measurement in a predetermined temperature atmosphere can be performed in the second cell.
An SPM measuring method characterized in that it is configured as described above.   2. The SPM measuring method according to claim 1, wherein the gas inlet and the gas outlet to the sample chamber are sealed during the SPM measurement. An SPM having a sample chamber comprising a first cell having a gas inlet and a second cell communicating with the first cell and having a cantilever disposed therein, the gas chamber having a gas outlet In
Temperature adjusting means disposed in the first cell;
SPM measuring means for performing SPM measurement in the second cell;
SPM characterized by having provided.   4. The SPM according to claim 3, wherein the gas inlet and the gas outlet to the sample chamber are sealed during SPM measurement.   The SPM according to claim 3, wherein a hot water bath maintained at a dew point temperature is provided in the sample chamber in order to perform high dew point control.   6. The SPM according to claim 5, wherein the hot water bath is provided with vaporization excitation means.

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