JP3753215B2 - Scanning probe microscope - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an atomic force microscope used for observing a fine structure of a sample surface.
[0002]
[Prior art]
FIG. 9 is an explanatory view of an atomic force microscope which is one of conventional scanning probe microscopes. In the figure, 20 is an XYZ translator, 21 is a sample stage, 22 is a sample, 2 is a cantilever, 5 is a deflection detector of the cantilever, and 6 is a computer and a controller.
[0003]
In this conventional atomic force microscope, a sample is placed on a sample stage on an XYZ translator, the sample is brought into contact with a sharpened probe fixed to the tip of a cantilever, and the sample is scanned in the XY plane. At this time, the deflection of the cantilever is monitored by a deflection detector of 5, and the controller performs feedback control so that the deflection becomes constant, and the position of the sample in the Z direction is adjusted by the translator. The fine structure of the sample surface can be observed by mapping the adjustment amount at each position on the sample surface on the screen by a computer.
[0004]
[Problems to be solved by the invention]
One of the important features of the scanning probe microscope is measurement time. That is, it is the time taken to obtain one image. Compared to other similar microscopes, such as scanning electron microscopes and scanning laser microscopes, scanning is performed by mechanically scanning the probe or sample while keeping the distance between the probe and the sample and the force acting between the probe and the sample constant. A scanning probe microscope has a slow scanning speed and takes a long time to measure.
[0005]
One way to shorten the measurement time is to simply increase the scanning speed. However, in this case, in addition to the problem of the control system and mechanical followability, the probe moves on the surface of the sample at a high speed, and there are problems such as wear of the probe and damage to the sample. Can not.
Therefore, an object of the present invention is to provide a scanning probe microscope that can shorten the measurement time without changing the scanning speed or exceeding the limit of the scanning speed.
[0006]
[Means for Solving the Problems]
The scanning probe microscope according to the present invention has a plurality of cantilevers each having a probe at the tip, and independently detects the deflection of the plurality of cantilevers and moves the plurality of cantilevers up and down independently toward the sample. It was set as the structure which has a means. Thereby, compared with the case where measurement is performed with a single probe, the scanning range of each probe can be reduced, so that the measurement time can be shortened without changing the scanning frequency. Further, the deflection of each cantilever is controlled to be constant when the probe scans the sample surface. As a result, the force acting between each probe and the sample can be controlled, and damage to the probe and the sample can be suppressed.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[Embodiment 1]
In FIG. 1, 1 is a probe, 2 is a cantilever, 3 is a cantilever support, 4 is a piezoelectric actuator, 5 is a deflection detection means of the cantilever, and 6 is a computer and a controller. The one probe and the five deflection detection means have a one-to-one configuration, and can detect the displacement of a plurality of probes independently. Based on the output of the deflection detection means of 5, the computer and controller of 6 scan the surface of the sample while moving the support of 3 up and down by 4 piezoelectric actuators so as to keep the deflection of each cantilever constant. To do. With such a configuration, the area scanned by one probe can be reduced, and as a result, the measurement time can be shortened without changing the scanning speed.
[0008]
[Embodiment 2]
In FIG. 2, 1 is a probe, 2 is a cantilever, 3 is a cantilever support, 4 is a piezoelectric actuator, 7 is a piezoelectric resistor, and 6 is a computer and a controller. The piezoresistor mounted on the cantilever changes its resistance value according to the amount of deflection when the probe is subjected to force and the cantilever bends. The computer 6 and the controller 6 can independently detect the deflection of a plurality of cantilevers by measuring the resistance values of the piezoelectric resistors on the respective cantilevers. The computer 6 and the controller scan the sample surface while moving the support 3 up and down by the 4 piezoelectric actuators so as to keep the deflection of each cantilever constant. With such a configuration, the area scanned by one probe can be reduced, and as a result, the measurement time can be shortened without changing the scanning speed.
[0009]
[Embodiment 3]
In FIG. 3, 1 is a probe, 2 is a cantilever, 3 is a cantilever support, 4 is a piezoelectric actuator, 8 is a piezoelectric body, and 6 is a computer and a controller. The piezoelectric body mounted on the cantilever changes its electromotive force according to the amount of deflection when the probe is subjected to force and the cantilever bends. The computer 6 and the controller 6 can independently detect the deflection of the plurality of cantilevers by measuring the electromotive force of the piezoelectric body on each cantilever. The computer 6 and the controller scan the sample surface while moving the support 3 up and down by the 4 piezoelectric actuators so as to keep the deflection of each cantilever constant. With such a configuration, the area scanned by one probe can be reduced, and as a result, the measurement time can be shortened without changing the scanning speed.
[0010]
[Embodiment 4]
In FIG. 4, 1 is a probe, 2 is a cantilever, 3 is a cantilever support, 4 is a piezoelectric actuator, 9 is an optical interferometer, and 6 is a computer and a controller. The opening for irradiating light to the back surface of the cantilever of the optical interferometer moves up and down integrally with the cantilever support. The computer 6 and the controller 6 can independently detect the deflection of a plurality of cantilevers by monitoring the output of each optical interferometer. The computer 6 and the controller scan the sample surface while moving the support 3 up and down by the 4 piezoelectric actuators so as to keep the cantilever deflection constant. With such a configuration, the area scanned by one probe can be reduced, and as a result, the measurement time can be shortened without changing the scanning frequency.
[0011]
[Embodiment 5]
In FIG. 5, reference numerals 10 and 11 respectively denote a position sensitive detector (PSD) and a light source of an optical lever detection system. 2 is a cantilever, 4 is a piezoelectric actuator, and 12 is a linear light spot. The PSD of 10 detects the deflection of the cantilever from the position of the light spot on the light receiving surface. By using a linear light source as shown in 12 instead of a point light source, an optical lever detection system can be configured with a single light source for a plurality of cantilevers, and the deflection of each of the plurality of cantilevers can be detected. it can. The computer 6 and the controller scan the sample surface while moving the support 3 up and down by the 4 piezoelectric actuators so as to keep the cantilever deflection constant. With such a configuration, the area scanned by one probe can be reduced, and as a result, the measurement time can be shortened without changing the scanning frequency.
[0012]
[Embodiment 6]
In FIG. 6, 10 and 11 are the PSD and light source of the optical lever detection system, respectively. 2 is a cantilever, 4 is a piezoelectric actuator, and 13 is a light spot. 14 is a modulation signal generator, 15 is a lock-in amplifier, and 6 is a computer and a controller. The light irradiated to each cantilever is modulated with a different frequency, and a signal modulated at the same frequency as the light irradiated to each cantilever by 15 lock-in amplifiers is detected from the PSD output. With such a configuration, an optical lever detection system capable of detecting displacement of a plurality of probes with one PSD can be configured, and deflection of each of a plurality of cantilevers can be detected. The computer 6 and the controller scan the sample surface while moving the support 3 up and down by the 4 piezoelectric actuators so as to keep the cantilever deflection constant. With such a configuration, the area scanned by one probe can be reduced, and as a result, the measurement time can be shortened without changing the scanning frequency.
[0013]
[Embodiment 7]
In FIG. 7, reference numerals 10 and 16 denote light sources having a PSD for the optical lever detection system and means for scanning the light spot. 2 is a cantilever, 4 is a piezoelectric actuator, and 13 is a light spot. 17 is a signal generator for scanning the light spot, 18 is a means for detecting the deflection of each cantilever from the output of 10 PSDs, and 6 is a computer and a controller. In this case, the output of 10 PSDs is pulsed and the magnitude of each pulse represents the deflection of the respective cantilever. With such a configuration, an optical lever detection system capable of detecting displacement of a plurality of probes with one PSD can be configured, and deflection of each of a plurality of cantilevers can be detected. The computer 6 and the controller scan the sample surface while moving the support 3 up and down by the 4 piezoelectric actuators so as to keep the cantilever deflection constant. With such a configuration, the area scanned by one probe can be reduced, and as a result, the measurement time can be shortened without changing the scanning frequency.
[0014]
[Embodiment 8]
In FIG. 8, 10 and 11 are the PSD and light source of the optical lever detection system, respectively. 2 is a cantilever, 4 is a piezoelectric actuator, and 12 is a linear light spot. Reference numeral 19 denotes modulation means, 14 denotes a modulation signal generator, 15 denotes a lock-in amplifier, and 6 denotes a computer and a controller. A means for modulating light at a constant frequency is arranged on each cantilever between a light source that irradiates a linear light spot and the cantilever, and each of the cantilevers is modulated by changing the frequency. The signal modulated by the modulation frequency of the light irradiated to each cantilever by 15 lock-in amplifiers is detected from the output of the PSD. With such a configuration, an optical lever detection system capable of detecting displacements of a plurality of probes with one PSD and one light source can be configured, and the deflection of each of the plurality of cantilevers can be detected. The computer 6 and the controller scan the sample surface while moving the support 3 up and down by the 4 piezoelectric actuators so as to keep the cantilever deflection constant. With such a configuration, the area scanned by one probe can be reduced, and as a result, the measurement time can be shortened without changing the scanning frequency.
[0015]
【The invention's effect】
According to the present invention, in the scanning probe microscope, by having a plurality of cantilevers having probes at the tips, the measurement time can be shortened without changing the scanning frequency, and the deflection of each cantilever is detected, Since the surface of the sample can be scanned while keeping the deflection constant, the force generated between each probe and the sample can be controlled, so that damage to the probe and the sample can be suppressed.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of a scanning probe microscope shown in Embodiment 1. FIG.
2 is an explanatory diagram of a scanning probe microscope shown in Embodiment 2. FIG.
3 is an explanatory diagram of a scanning probe microscope shown in Embodiment 3. FIG.
4 is an explanatory diagram of a scanning probe microscope shown in Embodiment 4. FIG.
5 is an explanatory diagram of a scanning probe microscope shown in Embodiment 5. FIG.
6 is an explanatory diagram of a scanning probe microscope shown in Embodiment 6. FIG.
7 is an explanatory diagram of a scanning probe microscope shown in Embodiment 7. FIG.
8 is an explanatory diagram of a scanning probe microscope shown in Embodiment 8. FIG.
FIG. 9 is an explanatory diagram of a conventional scanning probe microscope.
[Explanation of symbols]
1 Probe 2 Cantilever 3 Cantilever Support 4 Piezoelectric Actuator 5 Cantilever Deflection Detector 6 Computer and Controller 7 Piezoresistor 8 Piezoelectric 9 Optical Interferometer 10 Position Sensitive Detector (PSD)
Reference Signs List 11 light source 12 linear light spot 13 light spot 14 modulation signal generator 15 lock-in amplifier 16 light source 17 having means for scanning light spot signal generator 18 means for detecting deflection of cantilever 19 modulation means 20 XYZ translator 21 sample Stage 22 sample

Claims (4)

In a scanning probe microscope in which a minute probe scans the sample surface to observe the minute structure on the sample surface.
Means having a plurality of probes, each independently moving up and down relative to the sample;
Means for independently detecting the displacement of each probe;
A plurality of cantilevers having the probe at the tip and moving up and down according to the irregularities of the sample surface by a piezoelectric body;
A deflection detecting means for irradiating the plurality of cantilevers with light and using the optical lever method to individually detect the deflection of the plurality of cantilevers;
The optical lever method detects the deflection of a plurality of cantilevers with a single detector by applying a different frequency modulation to the light irradiated to the plurality of cantilevers and detecting each frequency with a detector. A scanning probe microscope characterized by the above. The scanning probe microscope according to claim 2, wherein the optical lever method irradiates a cantilever with a linear light spot.   A process of irradiating a plurality of cantilevers each having a probe at the tip with light modulated with different frequencies,
  A step of detecting the light reflected from the plurality of cantilevers for each frequency with a single detector;
A method for detecting deflection of a cantilever. The cantilever deflection detection method according to claim 3, wherein, in the step of irradiating the light, the cantilever is irradiated with a linear light spot.

Images