Apparatus for evaluating piezoelectric film, and method for evaluating piezoelectric film

Abstract

There are provided an apparatus for evaluating a piezoelectric film, which contains: a detection unit containing a pair of probes, each probe containing a cantilever and a probe tip; and an evaluation unit, wherein the detection unit is configured to respectively place the probe tips on both surfaces of a sample comprising a piezoelectric film so as to detect a displacement magnitude of the pair of probes, and the evaluation unit is configured to evaluate either or both a deformation and a displacement of the piezoelectric film based upon the detected displacement magnitude of the pair of probes, and a method for evaluating a piezoelectric film by using the apparatus for evaluating a piezoelectric film.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graph showing an example of a butterfly curve for evaluating a piezoelectricity of an piezoelectric film.

FIG. 2A is a schematic diagram showing a device for evaluating a piezoelectric film using the conventional AFM.

FIG. 2B is a schematic diagram showing a device for evaluating a piezoelectric film using the conventional laser displacement meter.

FIG. 3 is a schematic diagram showing displacements of an piezoelectric film before and after applying a voltage by means of the conventional AFM.

FIG. 4 is a graph of piezoelectricity which is obtained by plotting the measurements taken from the device shown in FIG. 3.

FIG. 5 is a schematic diagram showing a device for evaluating a piezoelectric film in the conventional double-beam system.

FIG. 6A is a schematic diagram showing an embodiment of a piezoelectric film-evaluation by means of the apparatus for evaluating a piezoelectric film according to Example 1 of the present invention, and wherein (1) shows the evaluation before applying the voltage, (2) shows the evaluation after applying the voltage, and (3) shows the condition of the sample which is warped after the application of the voltage.

FIG. 6B is a graph showing the displacement of the pair of probes measured by the method for evaluating a piezoelectric film of the present invention by means of the apparatus of FIG. 6A, and the displacement of the piezoelectric film measured based upon the displacement of the pair of probes.

FIG. 7A is a schematic diagram showing an initial setting of the probes using a reference sample in Example 2 of the present invention.

FIG. 7B is an enlarged cross-sectional view of the X-X section in FIG. 7A.

FIG. 7C is a schematic diagram showing an example of the forming process of the reference sample.

FIG. 7D is a schematic diagram showing another example of the forming process of the reference sample.

FIG. 8A is a schematic diagram showing the determination of the displacement of the sample based on the displacement magnitude of the probes in Example 2 of the present invention.

FIG. 8B is a flow chart showing the detection step and evaluation step in Example 2 of the present invention.

FIG. 8C is a graph showing the measurement results of the piezoelectric film, and the relationship of Zf and Zb in Example 2 of the present invention.

FIG. 9 is a control diagram showing the evaluation procedure of the sample in Example 3 of the present invention.

FIG. 10 is a control diagram showing the evaluation procedure of the sample in Example 4 of the present invention.

Claims

1. An apparatus for evaluating a piezoelectric film, comprising: a detection unit comprising a pair of probes, each probe comprising a cantilever and a probe tip; anda evaluation unit,

2. The apparatus for evaluating a piezoelectric film according to claim 1, wherein the detection unit detects the displacement magnitude of the pair of probes based upon a change in one selected from: positions of the pair of probes in Z direction; deflections of the cantilevers; amplitudes of the vibrated cantilevers; phases of the vibrated cantilevers; and frequencies of the vibrated cantilevers.

3. The apparatus for evaluating a piezoelectric film according to claim 1, wherein the detection unit is configured to respectively scan the pair of probes relatively along the sample so as to detect the displacement magnitude.

4. The apparatus for evaluating a piezoelectric film according to claim 1, wherein the sample comprises a substrate, and the piezoelectric film formed on the substrate.

5. The apparatus for evaluating a piezoelectric film according to claim 1, wherein the detection unit is configured to perform initial setting so as to make X-Y coordinates of one of the probes meet with X-Y coordinates of the other probe.

6. The apparatus for evaluating a piezoelectric film according to claim 1, wherein the detection unit is configured to perform an initial setting so as to set initial positions of Z coordinates of the pair of proves.

7. The apparatus for evaluating a piezoelectric film according to claim 5, wherein the prove tips of the pair of probes are respectively placed on both surfaces of a reference sample for positioning so as to perform the initial setting.

8. The apparatus for evaluating a piezoelectric film according to claim 7, wherein the reference sample for positioning is a substrate having a reference marker for positioning.

9. The apparatus for evaluating a piezoelectric film according to claim 8, wherein the reference marker is a hole which goes through the substrate.

10. The apparatus for evaluating a piezoelectric film according to claim 8, wherein the reference marker is a conductive material filled in a hole which goes through the substrate.

11. A method for evaluating a piezoelectric film by means of an apparatus for evaluating a piezoelectric film, comprising: respectively placing a pair of probe tips, which are respectively contained in a pair of probes, on both surfaces of a sample comprising a piezoelectric film to detect a displacement magnitude of the pair of probes; andevaluating either or both a deformation and displacement of the piezoelectric film based upon the detected displacement magnitude of the pair of probes,

12. The method for evaluating a piezoelectric film according to claim 11, wherein the step of detecting is to detect the displacement magnitude of the pair of probes based upon a change in one selected from: positions of the pair of probes in Z direction; deflections of the cantilevers; amplitudes of the vibrated cantilevers, phases of the vibrated cantilevers, and frequencies of the vibrated cantilevers.

13. The method for evaluating a piezoelectric film according to claim 11, wherein the step of detecting further comprises scanning the pair of probes respectively along the sample so as to detect the displacement magnitude.

14. The method for evaluating a piezoelectric film according to claim 11, wherein the sample comprises a substrate, and the piezoelectric film formed on the substrate.

15. The method for evaluating a piezoelectric film according to claim 11, wherein the step of detecting further comprises performing an initial setting so as to make X-Y coordinates of one of the probes meet with X-Y coordinates of the other probe.

16. The method for evaluating a piezoelectric film according to claim 11, wherein the step of detecting further comprises performing an initial setting so as to determine initial positions of Z coordinates of the pair of proves.

17. The method for evaluating a piezoelectric film according to claim 15, wherein the initial setting is to respectively place the pair of probes on both surfaces of a reference sample for positioning.

18. The method for evaluating a piezoelectric film according to claim 17, wherein the reference sample for positioning is a substrate having a reference marker for positioning.

19. The method for evaluating a piezoelectric film according to claim 18, wherein the reference marker is a hole which goes through the substrate.

20. The method for evaluating a piezoelectric film according to claim 18, wherein the reference marker is a conductive material filled in a hole which goes through the substrate.