JP3942869B2 - Scanning probe microscope - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a scanning probe microscope that includes a means for heating a sample, a means for cooling the sample, and a sample moving means for moving the sample, and measures the surface irregularity shape of the sample or the surface physical properties of the sample.
[0002]
[Prior art]
In a scanning probe microscope having a means for heating a sample, a means for cooling the sample, and a sample moving means for moving the sample, heating is performed when the sample is heated in order to measure the surface irregularity shape of the sample or the surface physical properties of the sample. A dedicated sample stage was measured using a sample stage dedicated to cooling when the sample was cooled.
[0003]
[Problems to be solved by the invention]
In conventional scanning probe microscopes, when heating and cooling a sample, the measurement is performed by exchanging the sample table dedicated to heating and the sample table dedicated to cooling depending on the purpose, so there is no need for trouble in mounting and replacement. There was a drawback of this. In addition, there is a drawback that the sample temperature cannot be measured continuously from the cooling temperature (minus temperature) to the heating temperature (plus temperature). In addition, since the sample stage is exchanged according to the temperature, there is a drawback that the temperature change at the same measurement point on the sample surface cannot be measured. Also, when measuring in a vacuum environment, especially when the sample surface is likely to oxidize or absorb moisture in the air when it comes into contact with the air, the vacuum environment must be changed in the middle to replace the sample stage depending on the temperature. There was a drawback that it was necessary to return to the atmosphere, and the temperature change of the physical properties of the sample surface in a vacuum environment could not be measured.
[0004]
[Means for Solving the Problems]
In order to solve the above problems, in the present invention, in a scanning probe microscope having a means for heating a sample, a means for cooling the sample, and a sample moving means for moving the sample, the means for heating the sample is cooled. The means was composed of the same sample stage and used as a sample stage for heating and cooling.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
In the scanning probe microscope having a means for heating a sample and a means for cooling the sample and a sample moving means for moving the sample as shown in the figure, the means for heating the sample and the means for cooling are the same. By configuring the sample stage as a sample stage that is also used for heating and cooling, it is possible to eliminate the trouble of mounting and exchanging the sample stage dedicated to heating and the sample stage dedicated to cooling when heating or cooling the sample. In addition, since it is not necessary to replace the sample stage according to the measurement temperature, it is possible to measure the temperature change at the same measurement point on the sample surface. In addition to having a vacuum vessel, the surface of the sample surface or the temperature of the physical properties of the sample surface is maintained in a vacuum environment without oxidizing or absorbing moisture in the air when the sample surface comes into contact with air. It was possible to measure changes.
[0006]
【Example】
As an embodiment, a scanning probe microscope using a cantilever having a minute probe at the tip will be described with reference to the drawings. FIG. 1 is a schematic diagram of the method of the present invention in measurement with a scanning probe microscope. The tip of the cantilever 1 has a probe 2 and contacts the sample 3 with the probe 2. The sample 3 is placed on a sample stage 4 that is also used for heating and cooling. The sample table 4 also used as a heating / cooling has a heater 11 incorporated therein, a heat insulating means 12 is formed in the lower part, and is placed on the sample moving means 5. A piezoelectric element or the like is used for the operation of the sample moving means 5, and there is a risk that the piezoelectric element loses its polarization (polling) due to heating and becomes inoperable. In the present invention, the amount of heat conduction from the heater 11 to the sample moving means 5 is reduced by passing through the heat insulating means 12, and malfunction of the sample moving means 5 due to heat is prevented. The heat insulating means 12 is made of ceramic having poor heat conduction. One of the examples is that the material of the heat insulating means 12 is mica among the materials having particularly poor heat conduction.
[0007]
The sample moving means 5 can operate in the vertical direction and in the planar direction. By operating in the vertical direction, the tip of the needle can be pressed against the sample surface to give repeated vibrations. In the operation in the planar direction, the probe 2 and the sample 3 can be relatively moved.
[0008]
The sample stage 4 also serving as a heating / cooling is connected by a relay cooling means 13 and a heat conducting means 14. The relay cooling means 13 is cooled with liquid nitrogen or the like. The relay cooling means 13 has a space inside and may store liquid nitrogen or the like. What is necessary is just a liquid refrigerant other than liquid nitrogen, such as liquid helium and liquid argon. Further, a gaseous refrigerant instead of a liquid may be stored or circulated in the internal space. Moreover, even if it cools with a refrigerator, the head part cooled by the refrigerator is good also as the relay cooling means 13 itself. For example, a copper foil or the like is used as the heat conducting means 14. A flexible foil is used so as not to restrict the operation of the sample moving means 5. Silver foil, gold foil, or general metal foil may be used instead of copper foil.
[0009]
When it is desired to cool the sample, the relay table 13 is cooled by cooling the relay cooling means 13 through the heat conduction means 14, and the sample 3 is also cooled. Subsequently, if the sample 3 is to be heated, the heater 11 heats the sample stage 4 which is also used for heating and cooling, and the sample is also heated. Moreover, desired temperature control is possible by controlling the current to the heater 11 while cooling at an intermediate temperature. Measurement can be performed continuously without changing the sample stage in the range from cooling to heating.
[0010]
Another embodiment of the present invention is illustrated in FIG. A radiation means 22 is disposed above the cantilever 1 and the sample 3 instead of incorporating a heater inside the sample stage 4 which is also used for heating and cooling. The cantilever 1 incorporates another displacement detection means 21 (for example, a strain resistance sensor) in itself, and the displacement amount of the probe 2 is measured. The sample is heated by the radiation means 22 with radiant heat. At the time of cooling, the sample is cooled by the relay cooling means 13 and the heat conducting means 14 as described above. Both temperatures are used in the middle of cooling and heating.
[0011]
Another embodiment of the present invention is shown in FIG. The case of obtaining viscoelastic properties among the sample surface properties will be described. The tip of the cantilever 1 has a probe 2 that is in contact with the sample 3. The sample 3 is placed on a sample stage 4 that is also used for heating and cooling. The sample moving means 5 can operate in the vertical direction and in the planar direction. By operating in the vertical direction, the probe 2 can be pressed against the surface of the sample 3 to give repeated vibrations. In the operation in the planar direction, the probe 2 and the sample 3 can be relatively moved.
[0012]
The vibration to the sample 3 is given as a modulation input 6 by a vertical movement built in the sample moving means 5. The cantilever 1 is irradiated with a laser 7, and the reflected light reaches the displacement detecting means 8. The displacement of the cantilever 1 is obtained as an output signal 9 depending on the arrival position of the displacement detection means 8.
[0013]
A sine wave is generally used for the modulation input 6, and the waveform of the output signal has a characteristic that is delayed with respect to the input waveform. The magnitude of the time delay is a value representative of the viscoelastic characteristics of the sample 3. If the amplitude (input amplitude) of the modulation input 6 is A0, the amplitude (output amplitude) of the output signal is A1. If the sample 3 is soft, the output amplitude A1 is smaller than the input amplitude A0. Even with the magnitude of the output amplitude A1, the viscoelastic characteristics of the sample 3 can be measured. In addition, instead of the sample moving means 5, another vibration means 10 installed on the cantilever 1 side may be used as the modulation input 6.
[0014]
As described above, the sample is brought to a desired temperature by the heater 11, the relay cooling means 13, and the heat conducting means 14. Modulation input 6 is added and the output waveform relative to the input waveform is measured. Next, the sample 3 is set to another desired temperature, and the measurement of the output waveform with respect to the input waveform is repeated. An example of temperature-dependent measurement is shown in FIG. For example, if attention is paid to the amplitude of the output waveform, as shown in FIG. 4A, a change in amplitude accompanying a change in the temperature of the sample is obtained as a graph. As the sample temperature increases, the viscoelastic characteristics such that the amplitude decreases, that is, the sample 3 becomes softer are measured. For example, if attention is paid to the time delay of the output waveform with respect to the input waveform, a change in the time delay accompanying the temperature change of the sample can be obtained as a graph as shown in FIG. As the sample temperature increases, the time delay increases, that is, the sample 3 becomes softer. When the sample temperature exceeds a certain temperature, the components inside the sample react and become harder, and the time delay exceeds the peak and decreases. Such viscoelastic properties are measured.
[0015]
The above description has been given as an example of measuring viscoelastic properties as sample surface properties. The sample surface property measurement target may be a friction characteristic or an adsorption characteristic. It is possible to continuously track changes in physical properties depending on the temperature of the sample surface at the same measurement point by using a sample stage that is also used for heating and cooling.
[0016]
Next, FIG. 5 shows an embodiment for measuring and displaying the surface unevenness image and the physical property image in a certain region of the sample surface by using the movement of the sample moving means 5 in the plane direction. The surface unevenness image and the physical property image are measured by setting the sample temperature to a desired temperature. Repeat at the same temperature. As described above, the temperature change in the same region on the sample surface can be tracked.
[0017]
FIG. 6 shows another embodiment of the present invention. A cantilever 1 that owns the probe 2, a sample 3, a sample stage 4 that is also used for heating and cooling, and a sample moving means 5 are arranged in a vacuum vessel 61. A vacuum exhaust means 62 is connected to the vacuum vessel 61. In the upper part of the vacuum vessel 61, vacuum confidentiality is secured by a window 63 so that the position to be measured can be visually confirmed. The laser 7 is introduced into the vacuum container 61 through the window 63 and irradiated onto the cantilever 1. The reflected light of the irradiated laser 7 is returned to the atmosphere side through the window 63 and reaches the displacement detecting means 8. The sample 3 is placed on a sample table 4 that is also used for heating and cooling. The heating / cooling sample stage 4 incorporates a heater 11. The sample stage 4 also serving as a heating / cooling unit is installed on the sample moving unit 5 through the heat insulating unit 12. The sample moving means 5 can operate in the vertical direction, X-axis scanning (left-right direction on the paper surface), and Y-axis scanning (vertical direction on the paper surface). The sample stage 4 also serving as a heating / cooling is connected by a relay cooling means 13 and a heat conducting means 14. The relay cooling means 13 is cooled with liquid nitrogen or the like.
[0018]
For example, in a state where the probe 2 is in contact with the sample 3, the cantilever 1 and the sample 3 are vibrated as the modulation input 6 by the vertical operation built in the sample moving means 5. The amplitude of the displacement of the cantilever 1 corresponding to the vibration is obtained as an output signal 9 depending on the position where the reflected light of the laser 7 reaches the displacement detecting means 8. The procedure for measuring the viscoelastic characteristics of the sample by obtaining the relationship between the modulation input 6 and the output signal 9 is as described above.
[0019]
Further, a gas introduction 64 may be disposed in the vacuum vessel 61, and after evacuating the inside of the vacuum vessel 61, a desired gas may be introduced to return to atmospheric pressure, and a series of viscoelastic characteristics may be measured. The introduction of gas may be stopped in a negative pressure state before the atmospheric pressure is reached, and a series of viscoelastic characteristics may be measured. Also, a series of viscoelastic characteristics may be measured by adding moisture to the introduced gas. Alternatively, the measurement may be performed at 1 atm by continuously flowing gas or moisture-containing gas into the vacuum vessel 61 without evacuating.
[0020]
Further, the modulation input may be performed by another vibration means 10 on the cantilever 1 side instead of the function built in the sample moving means 5.
[0021]
Further, instead of the heater 11, the radiation means 22 may be arranged on the window 63 to serve as a heating means. Instead of the laser 7 and the displacement detection means 8, a cantilever incorporating a displacement detection means may be used.
[0022]
【The invention's effect】
The present invention is implemented in the form as described above, and has the following effects. In the scanning probe microscope having a means for heating the sample, a means for cooling the sample, and a sample moving means for moving the sample, the means for heating the sample and the means for cooling the sample are configured on the same sample stage. When heating or cooling, there is an effect of eliminating the trouble of attaching a sample stage dedicated to heating and a sample stage dedicated to cooling depending on the purpose. Further, there is an effect that the temperature change at the same measurement point on the sample surface can be continuously measured without exchanging the sample stage according to the temperature. In addition, by having a vacuum container, the sample surface can be kept in a vacuum environment without changing the temperature of the sample surface properties or physical properties without oxidizing or absorbing moisture in the air. There is also an effect that can be measured.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of the present invention showing the configuration of a sample stage for both heating and cooling in a scanning probe microscope.
FIG. 2 is a schematic view showing another embodiment of the present invention showing a configuration of a sample stage for heating and cooling in a scanning probe microscope.
FIG. 3 is a schematic view showing an example in which viscoelastic characteristics are measured as physical properties of a sample in the present invention using a scanning probe microscope.
FIG. 4A is a temperature-dependent measurement example of the present invention, and is a graph showing a change in amplitude accompanying a change in the temperature of a sample. FIG. 4B is a temperature-dependent measurement example of the present invention. The graph which shows the change of the time delay accompanying a change.
FIG. 5 is a schematic diagram showing an embodiment in the case of obtaining a measurement image with a scanning probe microscope.
FIG. 6 is a schematic diagram showing an example in the case of measuring in a vacuum environment with a scanning probe microscope.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Cantilever 2 Probe 3 Sample 4 Sample stand 5 also used for heating and cooling Sample moving means 6 Modulation input 7 Laser 8 Displacement detecting means 9 Output signal 10 Other vibration means 11 Heater 12 Heat insulating means 13 Relay cooling means 14 Heat conduction means A0 Input amplitude A1 Output amplitude 61 Vacuum vessel 62 Vacuum exhaust means 63 Window 64 Gas introduction

Claims (7)

The heating means for heating the sample stage and the cooling means for cooling the sample stage by cooling the sample stage are thermally connected to the same sample stage, and the sample stage moves the sample. Connected with the means,
The heating means is a heater built in the sample stage,
The cooling means is a scanning probe microscope composed of a relay cooling means having a cooling capability itself, and a heat conduction means for thermally connecting the relay cooling means and the sample stage,
Control means for controlling the heating means and the cooling means, the control means for controlling the sample temperature to be changed in a series from the cooling temperature to the heating temperature , the heating means and the cooling means Scanning probe microscope that can be controlled simultaneously . The heating means for heating the sample stage and the cooling means for cooling the sample stage by cooling the sample stage are thermally connected to the same sample stage, and the sample stage moves the sample. Connected with the means,
The heating means is a heater built in the sample stage,
The cooling means is a scanning probe microscope composed of a relay cooling means having a cooling capability itself, and a heat conduction means for thermally connecting the relay cooling means and the sample stage,
In order to make the environment for measuring the information of the sample at least a vacuum environment, a vacuum vessel and an exhaust means are provided,
Further comprising a control means for controlling the cooling means and said heating means, said control means is for controlling to vary the series in the range of the sample temperature from the cooling temperature to heating temperature, said heating means A scanning probe microscope capable of simultaneously controlling the cooling means .   The scanning probe microscope according to claim 2, further comprising means for bringing the inside of the vacuum vessel to an atmospheric pressure so that measurement can be performed in an atmospheric environment.   4. The scanning probe microscope according to claim 2, further comprising means for evacuating the inside of the vacuum vessel once and then replacing the gas into a gas atmosphere. 5.   The scanning probe microscope according to claim 4, wherein the means for replacing the gas into a gas atmosphere further includes a function of adding moisture to the gas when the gas is introduced.   6. The scanning probe microscope according to claim 1, wherein the scanning probe microscope is further provided with heat insulating means for thermally insulating the sample stage and the sample moving means. 7. microscope.   The scanning probe microscope according to claim 6, wherein the heat insulating means is made of mica.

Images