JPH0592618U - Scanning probe microscope - Google Patents

Abstract

(57) [Abstract] [Purpose] To realize a probe scanning microscope that can perform planar image measurement and spectroscopic measurement simultaneously. [Structure] A probe, a displacement detection circuit for detecting displacement of the probe, an output of the displacement detection circuit, and a servo reference voltage V
_A servo circuit that applies a servo so that the physical quantity such as the atomic force acting between the probe and the sample using _SVO becomes constant.
A scanning actuator for scanning the sample in the x, y, and z directions, a scanning device for the scanning actuator, a circuit for generating or modulating a bias voltage V _B applied to the sample, the probe, and the sample. In a probe scanning microscope including a measuring circuit including a circuit for detecting a tunnel current I _T generated between and performing signal processing such as differentiation, and a memory circuit for storing the processed measurement result, the measurement is performed. Modulation of bias voltage V _B applied to the sample for the circuit /
The present invention is characterized in that a spectroscopic measurement range command circuit that outputs a bias voltage modulation command _MODL that commands non-modulation is provided.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a probe scanning microscope used for observing an ultrafine structure, and more particularly to an apparatus which enables spectroscopic measurement in an arbitrary range in an observation area.

[0002]

[Prior Art]

 A scanning probe microscope, for example, brings a metallic probe close to the sample to the extent that a tunnel current flows, and applies a voltage between them so that the tunnel current flowing at that time becomes constant. The shape of the sample surface is detected from the change in the control signal when the probe is scanned while controlling the distance between them.Spectroscopic measurement is performed using such a probe scanning microscope. The scanning system is maintained at each measurement point, the drive voltage of the actuator that controls the distance between the probe and the sample is also maintained, and those controls are temporarily suspended. Spectroscopy is performed by changing the voltage applied to and measuring the change in current at that time.

FIG. 4 is a block diagram showing an example of a conventional probe scanning microscope. In FIG. 3, 1 is a probe, 2 is a sample, 3 is a displacement detection circuit for detecting the displacement of the probe 1, 4 is the output of the displacement detection circuit 3 and the servo reference voltage V _SVO. The servo circuit that applies a servo so that the interatomic force acting between the sample 2 and the sample 2 becomes constant, 5, 6 and 7 are actuators for scanning the sample 2 in the x, y and z directions, and 8 is x. , A scanning device of the scanning actuators 5 and 6 in the y direction, and 9 is a bias voltage generating circuit for generating or modulating the bias voltage V _B applied to the sample 2 and the tunnel current generated between the probe 1 and the sample 2. It detects the I _T differential is measuring circuit and the like data memory for storing the tunnel current detection and signal processing circuit and the processed measurement results for performing signal processing such as.

In such a configuration, when the probe 1 is brought close to the sample 2, the probe 1 is bent by the atomic force. This displacement is detected by the displacement detection circuit 3 and servo is applied by the servo circuit 4 so that the interatomic force becomes constant, and the sample 2 is moved up and down by the z actuator 7. On the other hand, a tunnel current I _T flows between the probe 1 and the sample 2. With the bias voltage V _B applied to the sample 2 kept constant and the servo applied, the sample 2 is scanned on the X axis and the Y axis using the scanning device 8 and the x actuator 5 and the y actuator 6, and the tunnel current is By measuring I _T , a plane image is obtained. When the X-axis and the Y-axis are fixed, the bias voltage V _B is modulated, and the tunnel current I _T is measured, spectroscopic measurement can be performed.

[0005]

[Problems to be solved by the device]

 However, the probe scanning microscope shown in the above-mentioned prior art has the following problems. (1) Since the actuator used for scanning has a drift, it is impossible to accurately move the probe to an arbitrary position and perform spectroscopic measurement after the measurement of the planar image is completed. (2) The method of simultaneously performing the spectroscopic measurement during scanning can only measure a narrow range because the amount of data becomes huge.

The present invention has been made in view of the above-mentioned problems of the prior art, and excludes the influence of the drift of the actuator by providing a function of designating the range in which the photometric measurement is performed. The object of the present invention is to provide a probe scanning microscope capable of simultaneously performing plane image measurement and spectroscopic measurement.

[0007]

[Means for Solving the Problems]

The configuration of the present invention for solving the above-mentioned problems is a probe, a displacement detection circuit for detecting the displacement of the probe, the output of the displacement detection circuit and a servo reference voltage V _SVO , and the probe and the sample. A servo circuit for applying a servo so that a physical quantity such as an interatomic force acting therebetween becomes constant; a scanning actuator for scanning the sample in the x, y, and z directions; and a scanning device for the scanning actuator. A circuit for generating or modulating a bias voltage V _B applied to the sample, a circuit for detecting a tunnel current I _T generated between the probe and the sample, and performing signal processing such as differentiation, and a processed measurement result. A probe scanning microscope equipped with a measuring circuit comprising a memory circuit for storing, a bias voltage modulating finger for instructing the measuring circuit to modulate / non-modulate the bias voltage V _B applied to the sample. It is characterized in that a spectroscopic measurement range command circuit that outputs the command M _ODL is provided.

[0008]

[Action]

 According to the present invention, the probe scanning microscope is provided with the function of performing spectroscopic measurement in an arbitrary range within the scanning range, and measurement can be performed without being influenced by the drift of the actuator or the capacity of the data storage memory.

[0009]

【Example】

Hereinafter, the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of the probe scanning microscope of the present invention. In FIG. 1, the same elements as those in FIG. 4 are designated by the same reference numerals. In FIG. 1, 1 is a probe and 2 is a sample. When the probe 1 comes very close to the sample 2, the probe 1 is bent by an atomic force and a tunnel current I _T flows. Reference numeral 3 is a displacement detection circuit for detecting the displacement of the probe 1, and 4 is a z-actuator for comparing the output of the displacement detection circuit 3 and the servo reference voltage V _{SVO so} that the atomic force acting on the probe 1 becomes constant. This is a servo circuit that outputs a signal for moving up and down 7. The bias voltage V _B is output from the measurement circuit 9 to the sample 2 and is modulated or non-modulated by the spectroscopic measurement range command circuit 10. 8 is a scanning device for driving the x actuators 5 and y actuator 6, the output signal, X-axis X _SCAN, the Y axis is Y _SCAN. Reference numeral 9 is a measuring circuit that outputs a bias voltage V _B , detects and differentiates the tunnel current I _T , and stores the result in a memory. _{Reference numeral} 10 is an input of X _SCAN and Y _SCAN signals from the scanning device 8 and X _max , X _min , Y _max and Y _min signals from the _host controller, and X _min ≤X _SCAN ≤X _max and Y _min ≤Y _SCAN ≤ when Y _max, the spectral measurement range command circuits for outputting the bias voltage modulation command M _ODL the measuring circuit 9.

In such a configuration, a case will be described in which, in the measurement of 4 × 4 points shown in FIG. 2, spectroscopic measurement is performed only at the four central points (hatched portions). FIG. 3 is a diagram showing each output signal in FIG. 1 to 3, the scanning signals X _SCAN and Y _SCAN output from the scanning device 8 are, as shown in FIGS. 3 (a) and 3 (b), signals of 0 to 3 in a stepwise manner in accordance with the scanning order. Output to. Here, the spectroscopic measurement is performed only when (X _SCAN , Y _SCAN ) = (1,1), (1,2), (2,1), (2,2) shown in FIG. Therefore, the bias voltage modulation command M _ODL output from the spectroscopic measurement range command circuit 10 to the measurement circuit 9 is modulated only at these four points (“1” in FIG. 3C), and unmodulated at the other 12 points. (In FIG. 3C, the command value is "0"). The bias voltage V _B output from the measurement circuit 8 receives the bias voltage modulation command _MODL from the spectroscopic measurement range command circuit 10, modulates only four points as shown in FIG. It becomes a constant voltage at the point. As shown in FIG. 3E, the timing at which the tunnel current I _T is sampled and stored in the data memory is once per measurement at one point when the bias voltage V _B is not modulated. Sample about 100 times. In addition, in FIG. 3 (e), sampling is performed 10 times. By such an operation, the characteristics of the scanning signal (X _SCAN , Y _SCAN ) vs. the tunnel current I _T , and the characteristics of the bias voltage V _B vs. the tunnel current I _T (and the differential value of I _T etc.) are obtained at the same time, and the plane Image measurement and spectroscopic measurement can be performed simultaneously.

Note that the target to which the servo is applied is not limited to the interatomic force shown in the above embodiment, and it is possible to use a magnetic force generated between the probe and the sample. Further, the target to be modulated is not limited to the bias voltage V _B , but it is also possible to modulate the servo reference voltage V _SVO .

[0012]

[Effect of the device]

 As described above in detail with the embodiments, according to the present invention, there is an effect that the measurement can be performed without being influenced by the drift of the actuator and the capacity of the data storage memory, and the probe that can perform the planar image measurement and the spectroscopic measurement simultaneously. A scanning microscope can be realized.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of a probe scanning microscope of the present invention.

FIG. 2 is a diagram showing an example of a scan target on a sample surface.

FIG. 3 is a diagram showing each output signal in the apparatus of FIG.

FIG. 4 is a conventional example of a probe scanning microscope.

[Explanation of symbols]

1 probe 2 Sample 3 displacement detecting circuit 4 servo circuit 5 x actuator 6 y actuator 7 z actuator - motor 8 scanning device 9 measuring circuit 10 the spectral measurement range command circuit I _T tunneling current M _ODL bias voltage modulation command V _B bias voltage V _SVO servo reference voltage

Claims (1)

[Scope of utility model registration request] 1. A probe, a displacement detection circuit for detecting displacement of the probe, and an output of the displacement detection circuit and a servo reference voltage V _SVO are used to detect an atomic force acting between the probe and the sample. A servo circuit for applying a servo so that the physical quantity is constant, a scanning actuator for scanning the sample in the x, y, and z directions, a scanning device of the scanning actuator, and a bias voltage applied to the sample. A circuit for generating or modulating V _B and a tunnel current I _T generated between the probe and the sample
In a probe scanning microscope including a measurement circuit including a circuit for performing signal processing such as differentiation and signal processing such as differentiation and a memory circuit for storing the processed measurement result, and applying the measurement circuit to the sample. Bias voltage modulation command M for instructing modulation / non-modulation of bias voltage V _B
A probe scanning microscope characterized in that a spectroscopic measurement range command circuit for outputting _ODL is provided.