JPH045503A - Inclination correcting method - Google Patents

Abstract

PURPOSE:To accurately measure and observe the fine shape of the surface of a sample at the same time by rotating the scanning direction of a probe or the fitting direction of the sample and matching the scanning direction of the probe with a direction where the sample surface does not slant. CONSTITUTION:When scanning signals X and Y are generated by an X-axial scanning signal generator 1 and a Y-axial scanning signal generator 2 respectively, the probe 16 is put in scanning motion on the surface of the sample 17 according to those scanning signals. In such a state, while the in-surface scanning of the probe 16 along the surface of the sample 17 is carried out, an angle signal theta generated by a reference voltage generator 4 is varied successively to observe the surface shape of the sample by the simultaneous observation for obtaining an observation image at the same time with the measurement while changing the direction of the in-surface scanning of the probe 16 along the surface of the surface of the sample 17.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for correcting the inclination of a sample surface in a measuring device that measures the sample surface shape by scanning a probe over the sample surface.

[Summary of the invention]

By rotating the scanning direction of the probe or the mounting direction of the sample,
Corrects the tilt of the sample surface by matching the scanning direction of the probe with the direction without tilt that always exists on the sample surface.
This is intended to improve the accuracy and efficiency of shape measurement in a measuring device that measures the shape of a sample surface by scanning a probe over the sample surface.

[Conventional technology]

For example, by using the tunnel effect to keep the distance between the sample surface and the probe constant, the probe is scanned in the in-plane direction along the sample surface, and from the height information of the probe at this time, the sample surface is STM (scanning tunneling microscope) to obtain three-dimensional microscopic shapes
In order to correct the inclination of the measurement image due to the inclination of the sample surface, a bypass filter is installed in the part that takes in the height information of the probe, while eliminating the gradual increase and decrease of the captured information caused by the inclination of the sample. Attempts have been made to include a method of capturing only information caused by minute irregularities on the surface of a sample, and a method of performing tilt correction by data processing the captured information afterwards.

[Problem to be solved by the invention]

However, in the method using a bypass filter,
There is a risk that information about the gradual fine shapes on the sample surface will disappear, and furthermore, at the starting point of each scanning line, which is the turning point of the probe's scan, the gradual increase or decrease of information acquired due to the tilt of the sample surface may suddenly occur. This will change in the opposite direction, and this influence cannot be eliminated by a bypass filter, which will instead disturb the measurement image, making it difficult to obtain an accurate microscopic shape of the sample surface.

Furthermore, in a method in which data processing is performed later, a large amount of time is spent on the processing, which not only results in very low efficiency, but also makes it impossible to perform simultaneous observation to obtain observation images at the same time as measurement.

[Means to solve the problem]

The above problem naturally occurs because the sample surface is tilted with respect to the scanning direction of the probe.

Therefore, the above-mentioned problem can be solved by eliminating the inclination of the sample surface with respect to the scanning direction of the probe by some means. However, providing a sample tilt correction table to correct the tilt of the sample surface not only complicates the function of the measuring device, but also requires a great deal of effort and time to accurately correct the tilt. This is actually extremely difficult.

Therefore, even if a certain surface exists in an inclined state with respect to the horizontal plane, there is always a straight line parallel to the horizontal plane on that surface, and when scanning the xy plane with STM etc., one screen Focusing on the fact that when scanning for minutes, scanning is repeated many times in the X-axis direction, but only once in the Y-axis direction, the scanning direction of the probe or the attachment of the sample is By rotating the direction, the X-axis scanning direction of the probe coincides with the non-tilted direction that always exists on the sample surface, and furthermore, the X-axis scanning direction of the probe coincides with the non-tilted direction that always exists on the sample surface. This method measures the fine shape of the sample surface by incorporating an extremely weak bypass filter that can eliminate increases and decreases in probe height information due to the tilt of the sample surface in the Y-axis scanning direction, which occurs only once. .

[Effect]

The method described above provides a means for rotating the scanning direction of the probe or the mounting direction of the sample without providing a complicated mechanism and performing a large amount of correction work, and having little influence on the height information of the probe to be captured. By using the simple means of incorporating a bypass filter without a burr, the tilt of the sample surface can be corrected very easily, allowing accurate measurement and simultaneous observation of the fine shape of the sample surface.

〔Example〕

This example describes a method for correcting the inclination of a sample surface in a 37M apparatus, in which a piezoelectric element is used to scan a probe in the in-plane direction, and a three-dimensional fine shape of the sample surface is obtained from the height information of the probe at this time. The explanation will be given below according to the drawings.

(First Embodiment) FIG. 1 shows an apparatus configuration applied to a first embodiment of the present invention.

X-axis scanning signal X generated from the X-axis scanning signal generator 1
is divided into two systems, one system is input to the CoS signal modulator 5, and the other system inverts the signal with the inverting amplifier 3 and then outputs the signal to the SI.
N signal is input to the modulator 6.

Y-axis scanning signal Y generated from Y-axis scanning signal generator 2
is divided into two systems and directly connected to CO8 signal modulator 7 and SU
N signal is input to the modulator 8. The reference voltage generator 4 generates a reference voltage θ corresponding to the angle at which the in-plane scanning direction of the probe 16 is to be rotated, and generates a reference voltage θ corresponding to the angle ordered from the reference voltage generator 4. is divided into four systems: a CO8 signal modulator 5.7, a SIN signal modulator 6,
8 reference voltages, respectively. The CO8 signal modulator 5.7 modulates the input signals X and Y with the CoS function of the reference voltage θ to obtain xcosθ and y, respectively.
A signal called cos θ is output.

Further, the SJN signal modulator 6.8 modulates the input signals -X and Y using the SIN function of the reference voltage θ, and outputs signals -XSINθ and YSINθ, respectively.

The signal XC○Sθ output from the CO8 signal modulator 5 is
The signal YSINθ output from the SIN signal modulator 8 is
The addition signal YSINθ+COSθ input to the adder 9 and output from the adder 9 is amplified at a desired amplification factor by the high voltage amplifier 11, and is applied to the X-axis electrode of the cylindrical piezoelectric element 13, which is an example of an in-plane scanning mechanism. 14, the cylindrical piezoelectric element 1
The probe 16 attached to the tip of the sample I7 is scanned in the X direction along the surface of the sample I7, which is arranged to face the probe 16.

The signal -XSINθ output from the SIN signal modulator 6 and the signal VCO3θ output from the CoS signal modulator 7 are input to the adder 10, and the addition signal ycosθ−XSINθ output from the adder 10 is input to the high voltage amplifier 12. The signal is amplified by a desired amplification factor and applied to the X-axis electrode 15 of the cylindrical piezoelectric element 13, and the probe 16 attached to the tip of the cylindrical piezoelectric element 13 is placed so as to face the probe 16. scan in the Y direction along the surface of the sample 17.

With the above configuration, the X-axis scanning signal
YSINθ+XCQSθ, ycosθ−XSI, respectively
It becomes possible to convert the probe 16 to YSINθ + XCO5θ in the X-axis direction and ycosθ in the Y-axis
Scanning is performed according to the signal -XSINθ,
This changes the in-plane scanning direction of the probe 16 to X according to the angle signal θ.
The in-plane scanning direction of the probe 16 can therefore be rotated to an arbitrary angle. In addition, this device has 37
As part of the M device configuration, the distance between the sample 17 and the probe 16 is controlled to be constant in a part not shown.
Further, the height information of the probe 16 is taken in as information on the surface shape of the sample I7 and is converted into an image.

Furthermore, a very weak bypass filter, that is, a filter that cuts only extremely low frequency signals, is built into the height information acquisition part of the probe 16, and all signals except for extremely long period tilt signals are passed through. It is now being visualized.

Here, in the 37M device, the scanning trajectories of the X-axis scanning signal generator 1 and the Y-axis scanning signal generator 2 are generally shown in FIG. 3, which shows an in-plane scanning trajectory and an example of its rotation. By generating the angle signal θ from the reference electro-acid generator 4, the probe scanning trajectory 21 before rotation changes to the probe scanning trajectory 21 after rotation. It will change like the trajectory 22.

Now, in such an apparatus configuration, when scanning signals X and Y are generated from the X-axis scanning signal generator 1 and the Y-axis scanning signal generator 2, respectively, the probe 16 moves to the sample 17 in response to these scanning signals. will be in-plane scanned along the surface of. At this time, if the surface of the sample 17 is inclined compared to a plane perpendicular to the probe 16, the height of the probe 16 changes depending on the surface shape of the sample 17 and its inclination. In this state, while actually in-plane scanning the probe 16 along the surface of the sample 17, by sequentially changing the angle signal θ generated from the reference voltage generator 4, the probe 16 is scanned along the surface of the sample 17. By observing the surface shape of the sample 17 through simultaneous observation while changing the direction of in-plane scanning and obtaining an observation image at the same time as the measurement, the angle signal θ generated from the reference voltage generator 4 is used to observe the surface shape of the probe 16. If the range of change in the direction of in-plane scanning along the surface of the sample 17 is within a maximum of 180 degrees, there always exists a point at which the observed image is no longer tilted in the lateral direction, that is, in the X-axis direction.

The direction in which the probe 16 is scanned by the scanning signal X from the X-axis scanning signal generator 1 at this time is the direction in which there is no inclination that always exists on the surface of the sample 17. From then on, it is only necessary to continue the measurement while keeping the angle signal θ from the reference voltage orderer 4 fixed.

As described above, the inclination of the sample 17 can be adjusted by the extremely easy method of rotating the in-plane scanning direction of the probe 16 so that the lateral inclination is eliminated while looking at the observed image at the start of measurement without requiring any special techniques. Corrections will be made.

(Second Embodiment) Figure 2 shows the configuration of the device applied to the second embodiment of the present invention, but since the method of tilt correction is almost the same as in the first embodiment, only the different parts will be explained. conduct.

In the first embodiment, scanning by the scanning signal In the second embodiment, the direction of the sample 17 on which the sample 17 is mounted is made to match the direction with no inclination that always exists on the surface of the sample 17. By rotating the rotary stage 18, the direction of scanning by the scanning signal .

〔Effect of the invention〕

As described above, by using the method of the present invention, it is possible to correct the tilt of the sample very easily, which makes it possible to accurately measure the minute shape of the sample surface in real time. Achieves higher precision and faster measurement.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of an apparatus applied to a first embodiment of the invention, and FIG. 2 is an explanatory diagram of an apparatus applied to a second embodiment of the invention. Further, FIG. 3 is a diagram showing an in-plane scanning locus and an example of its rotation. 1...X-axis scanning signal generator 2...Y-axis scanning signal generator 3...Inverting amplifier 4...Reference voltage (angle signal) generator 5.7...COS signal modulator 6. 8...SIN signal modulator 9.10...Adder 11, 12...High voltage amplifier 13...Cylindrical piezoelectric element 14...X-axis electrode 15...Y-axis electrode 16... Probe 17... Sample 1B... Sample rotation stage 19... In-plane scanning area 20 before rotation... In-plane scanning area 21 after rotation... Probe scanning locus 22 before rotation...・Probe scanning trajectory after rotation Applicant: Seiko Electronics Industries Co., Ltd. Patent attorney: Keinosuke Hayashi

Claims (1)

[Claims] A tilt correction method characterized by correcting the tilt of the sample surface by rotating the probe scanning direction or the sample mounting direction to match the probe scanning direction with a direction in which the sample surface is not tilted.