Surface analyzer

Abstract

A technique for allowing users to efficiently specify a region of interest (ROI) on a sample for a certain physical quantity (e.g. phase) other than the altitude is provided. A range-indicating image showing a range that can be observed on a sample is displayed on a navigation window in a sample observation display screen. An ROI-indicating frame for specifying a magnified observation range is superposed on the range-indicating image. A list of thumbnails of previously taken magnified images for the same sample is displayed on an image history display window. When an observer selects any image from this list, the thumbnail of the selected image is mapped onto the range-indicating image. With reference to this image, the observer can change the position, size and/or angle of the ROI-indicating frame by a mouse operation. In response to this operation, a magnified image of the sample within the new ROI is acquired.

Claims

1. A surface analyzer for microscopy, comprising: a sample stage for placing the sample; a detection unit for obtaining information of one or more different kinds of physical quantities from the sample on the sample stage; a controller for receiving the information of one or more different kinds of physical quantities from the detection unit; a cylindrical scanner on which the sample stage is mounted, wherein the scanner has a plurality of elements for moving the sample; a cantilever having a probe at its tip disposed over the sample; and a display processor for microscopy configured to display, based on the information of one or more different kinds of physical quantities from the controller, a two-dimensional range-indicating image indicating an entire range capable of being scanned with the probe, and configured to create a distribution image of the one or more different kinds of physical quantities obtained for a range of any size located at any position within the two-dimensional range-indicating image, and configured to superpose the distribution image on a corresponding position on the range-indicating image, said the one or more physical quantities being phase, electric current, viscoelasticity, magnetic force, surface potential and/or electrostatic force on the sample surface.

2. The surface analyzer according to claim 1, further comprising: wherein the detection unit is provided to detect the displacement of the cantilever, the displacement detection unit has a laser source, a lens, a beam splitter, a mirror, and a photodetector, and a laser beam emitted from the laser source and converged by the lens is reflected by the beam splitter, and cast onto the tip of the cantilever and reflected; and then the reflected light is received by the mirror and redirected to the photodetector.

3. The surface analyzer according to claim 1, wherein the range specifier displays a rectangular frame on the range-indicating image and allows users to translate, resize, and rotate the rectangular frame to specify a range to be analyzed.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The file of this patent contains at least one drawing executed in color. Copies of this patent with color drawings will be provided by the Office upon request and payment of the necessary fee.

(2) FIG. 1 is a configuration diagram showing the main components of a scanning probe microscope (SPM) as one embodiment of the present invention.

(3) FIGS. 2A and 2B are photographic images showing one example of an altitude image and a phase image taken with an SPM.

(4) FIG. 3 is a flowchart showing one example of the steps of operations and processes in a sample observation characteristic of the SPM of the present embodiment.

(5) FIG. 4 is a diagram illustrating the relationship between a range that can be observed on a sample and an actually observed range.

(6) FIG. 5 is a schematic diagram showing one example of a display screen used in the sample observation process characteristic of the SPM of the present embodiment.

(7) FIG. 6 is an enlarged view of the navigation window shown in FIG. 5.

(8) FIGS. 7A-7C are diagrams illustrating various operations that can be performed on an RO-setting frame displayed in the navigation window shown in FIG. 6.

BEST MODE FOR CARRYING OUT THE INVENTION

(9) A scanning probe microscope (SPM) as one embodiment of the surface analyzer according to the present invention is hereinafter described with reference to the attached drawings. FIG. 1 is a configuration diagram showing the main components of the SPM in accordance with the present embodiment.

(10) A sample 1 to be observed is placed on a sample stage 2 mounted on the upper end of a substantially cylindrical scanner 3. The scanner 3 has a plurality of piezoelectric elements and is capable of moving the sample 1 in the X and Y directions as well as finely adjusting its position in the Z direction in accordance with voltages applied from a scanner driver 7. A cantilever 4 having a probe at its tip is located above the sample 1. The cantilever 4 is driven to oscillate by an exciter including a piezoelectric element (not shown). Located above the cantilever 4 is a displacement detection unit 10 for detecting the displacement of the cantilever 4 in the Z direction. The displacement detection unit 10 includes a laser source 11, lens 12, beam splitter 13, mirror 14, photodetector 15 and other elements. In this displacement detection unit 10, a laser beam emitted from the laser source 11 and converged by the lens 12 is reflected by the beam splitter 13, to be cast onto the tip of the cantilever 4 and thereby reflected. The reflected light is received by the mirror 14 and redirected to the photodetector 15, which has a light-receiving plane divided into a plurality of sections arrayed in the displacement direction of the cantilever 4 (i.e. the Z direction).

(11) For example, in a DFM (Dynamic Force Mode) observation, the cantilever 4 is oscillated in the Z direction at a frequency f near its resonance point. In this state, when an attractive or repulsive force due to an interatomic force or other factor acts between the probe 5 and the surface of the sample 1, the oscillation amplitude of the cantilever 4 changes. A displacement of the cantilever 4 in the Z direction causes a change in the proportion of the amounts of light falling onto the plural sections of the light-receiving plane of the photodetector 15. A displacement calculator 6 calculates the amount of displacement of the cantilever 4 by processing the detection signals corresponding to the amounts of light, and sends the obtained value to the controller 21.

(12) The controller 21 calculates a voltage value for slightly changing the position of the scanner 3 in the Z direction via the scanner driver 7 so as to cancel the displacement of the cantilever 4, i.e. so as to maintain a constant distance between the probe 5 and the surface of the sample 1. The calculated voltage is sent to the scanner driver 7, whereby the position of the scanner 3 in the Z direction is finely adjusted. The controller 21 also calculates voltage values for the X and Y directions so as to move the sample 1 relative to the probe 5 in the X-Y plane according to a predetermined scan pattern, thereby finely adjusting the position of the scanner 3 in the X and Y directions via the scanner driver 7. A signal reflecting the amount of feedback in the Z direction (scanner voltage) is sent from the controller 21 to a data processor 22, which processes this signal at each point (X, Y) to calculate a data corresponding to the altitude or another physical quantity of the sample 1. Based on this data, a display processor 24 creates a two-dimensional image or the like and displays it on the screen of a display unit 26. The obtained data is stored in the data memory 23.

(13) The SPM in the present embodiment is capable of performing not only the measurement of the altitude (i.e. surface shape) of the sample 1 but also simultaneously the measurement of another physical quantity, such as the phase, electric current, magnetic force or surface potential. These additional data are also stored in the data memory 23. The controller 21, data processor 22, data memory 23, display processor 24 and other components are embodied by a personal computer 20. The previously described data-collecting operation, and an image-displaying process described later, can be carried out by running a dedicated controlling and processing software program installed in the computer 20 beforehand.

(14) An image-displaying process characteristic of a sample observation by the SPM of the present embodiment, and a measurement control based on an image displayed in that process, are hereinafter described.

(15) FIG. 3 is a flowchart showing one example of the operating and processing steps in a sample observation characteristic of the SPM of the present embodiment, FIG. 4 is a diagram illustrating the relationship between a range that can be observed on a sample and an actually observed range, FIG. 5 is a schematic diagram showing one example of a display screen used in the sample observation process characteristic of the SPM of the present embodiment, FIG. 6 is an enlarged view of the navigation window shown in FIG. 5, and FIGS. 7A-7C are diagrams illustrating various operations that can be performed on an ROI-indicating frame displayed in the navigation window shown in FIG. 6.

(16) The following description deals with the case where the SPM is used so as to perform a two-dimensional measurement of not only the altitude of the sample 1 but also the phase on the surface and create a magnified image showing the phase distribution. The “phase” is the phase shift (delay) between the voltage signal for oscillating the cantilever 4 and the actual oscillation signal. The phase reflects a difference in a certain physical property of the surface of the sample 1, such as the viscoelasticity or adsorption property. FIGS. 2A and 2B are photographic images showing one example of an altitude image and a phase image taken with an SPM for the same area on a sample.

(17) As shown in FIG. 5, a sample observation display screen 30 has a real-time image display window 31 for displaying a real-time image (magnified image), a image history display window 32 for displaying a list of miniature versions (thumbnails) of previously taken magnified images of the same sample 1 and stored in the data memory 23, and a navigation window 33 which shows the positional relationship between the entire observation range on the sample 1 and the previously taken magnified image and on which users can specify the next measurement range. As already stated, the present system simultaneously acquires the altitude image and the phase image of the sample 1. Accordingly, the altitude images and the phase images of the same area are listed in the image history display window 32. Naturally, the arrangement of the windows 31, 32 and 33 in the sample observation display screen 30 is not limited to this form.

(18) As shown in FIGS. 5 and 6, the navigation window 33 displays a range-indicating image 34 which illustrates a rectangular frame indicating the range that can be observed on the sample 1 at that point in time. A rectangular ROI-indicating frame 35 for allowing users to set a region of interest (ROI) for observation is superposed on the range-indicating image 34. The ROI-indicating frame 35 is a GUI (Graphical User Interface) component that can be manipulated with a mouse or similar pointing device included in the input unit 25. That is to say, as shown in FIGS. 7A and 7B, the ROI-indicating frame 35 can be resized by a drag-and-drop operation of the mouse on any one of the four corners of the frame (FIG. 7A) or translated by a drag-and-drop operation on the entire frame (FIG. 7B). Furthermore, as shown in FIG. 7C, when a rotational manipulation mode is selected, the ROI-indicating frame 35 can be rotated around the point located above the frame 35 by an arbitrary angle by moving the mouse pointer around the aforementioned point.

(19) The range-indicating image 34 in the navigation window 33 corresponds to the range that can be observed on the sample, which is denoted by numeral 40 in FIG. 4. That is to say, the observable range 40 is the entire range that can be scanned with the probe 5 driven by the scanner 3 in the X and Y directions. The smaller range 41 shown by the dotted line within the observable range 40 in FIG. 4 corresponds to the range to be actually scanned and observed with the probe 5 according to the range specification through the ROI-indicating frame 35 as will be described later.

(20) The steps of a sample observation characteristic of the SPM of the present embodiment are hereinafter described with reference to FIG. 3. Initially, an observer enters through the input unit 25 a command for initiating an observation of a altitude over the entire observable range 40 on the sample 1. Upon receiving this command, the controller 21 operates the scanner 3 via the scanner driver 7 so as to scan the entire observable range 40 with the probe 5. As a result, a two-dimensional distribution data on the altitude of the sample 1 is obtained for the entire observable range 40 in the data processor 22. Based on this data, the display processor 24 creates a two-dimensional altitude image and shows this image (which is a broad-area image showing the sample's altitude) on the real-time image display window 31 in the sample observation display screen 30 on the screen of the display unit 26 (Step S1). From this image, the observer can roughly grasp the altitude of the entire observable range 40 on the sample 1.

(21) With reference to the broad-area image showing the sample's altitude on the real-time image display window 31, the observer can perform the aforementioned mouse manipulations to arbitrarily change the position, size and/or angle (direction) of the ROI-indicating frame 35 on the range-indicating image 34 so as to set the region of interest on the sample 1 to be observed with a high magnification (Step S2). According to the setting of the ROI-indicating frame 35, the controller 21 operates the scanner 3 via the scanner driver 7 so that only a small range on the sample 1 corresponding to the ROI-indicating frame 35 will be scanned with the probe 5. As a result, a two-dimensional altitude distribution data and a two-dimensional phase distribution data for the aforementioned small range are obtained in the data processor 22. Based on these data, the display processor 24 creates a two-dimensional altitude image and shows this image (which is a broad-area image showing the sample's altitude) on the real-time image display window 31 in the sample observation display screen 30 on the screen of the display unit 26 (Step S3).

(22) At this point, the obtained data are not yet stored in the data memory 23 and the observer may appropriately change the position, size and/or angle of the ROI-indicating frame 35 on the range-indicating image 34. When such a change is made, the range actually scanned with the probe 5 correspondingly changes and the magnified image shown in the real-time image display window 31 is updated. After the ROI-indicating frame 35 is set, when the observer enters, through the input unit 25, a command for acquiring data, the data obtained at that point in time, i.e. the two-dimensional distribution data on the altitude and the two-dimensional distribution data on the phase for the small area corresponding to the ROI-indicating frame 35 at that point in time, are stored in the data memory 23 (Steps S4 and S5). Additionally, a positional data, which indicates, for example, the relative position within the observable range 40 on the sample 1, is also stored so as to identify the position at which the aforementioned two-dimensional data have been obtained.

(23) Based on the data stored in the data memory 23 in the previously described manner, the display processor 24 creates thumbnails of the magnified images of the altitude and those of the phase on the sample surface and displays the thumbnails in the image history display window 32 in the sample observation display screen 30 (Step S6). That is to say, the image history display window 32 is used to display thumbnails of previously taken magnified images showing various kinds of physical quantities (e.g. the altitude and phase on the sample surface in the present case) of the same sample.

(24) On the image history display window 32, the observer selects any one or more images (thumbnails) and moves them onto the range-indicating image 34 by an operation using the input unit 25 (Step S7). In response to this operation, the display processor 24 retrieves, from the data memory 23, the positional data associated with the two-dimensional distribution data from which the selected images were created. Based on the retrieved positional data, the display processor 24 arranges the thumbnails on the range-indicating image 34 in such a manner that their positions relative to this image 34 correspond to their original positions on the observable range 40 (Step S8). This means that thumbnails of magnified images corresponding to small areas are mapped onto the range-indicating image 34. On the resultant image, the positional relationship between the previously taken magnified images and the observable range on the sample indicated by the frame of the range-indicating image 34 can be quickly and visually grasped, as shown in FIG. 5.

(25) While visually checking the range-indicating image 34 onto which previously taken images have been mapped, the observer may want to acquire a magnified image of another portion within the observable range 40 on the sample 1. In such a case, the observer can return to Step S2 and change the position and/or other properties of the ROI-indicating frame 35 on the range-indicating image 34 by a mouse operation to set a new region of interest. Subsequently, the newly set small area (region of interest) on the sample 1 is scanned with the probe 5 in the previously described manner to collect two-dimensional distribution data of the altitude and phase on that small area of the sample. After the scan is completed, thumbnails of the magnified images created from the new data are added to the image history display window 32.

(26) In the example of FIG. 5, only two thumbnails of phase images are superposed on the range-indicating image 34. It is possible to collect detailed two-dimensional distribution data on the sample's altitude and phase over the entire observable range 40 of the sample 1 by repeatedly collecting data while setting the ROI-indicating frame 35 for each of the unmapped regions. However, in many cases, what is required is to collect two-dimensional distribution data of the sample's altitude and phase for an area near a limited region on the sample 1. In such a case, the observation can be completed when the desired data have been collected.

(27) In the example of FIG. 5, the thumbnails selected from the image history display window 32 and displayed on the range-indicating image 34 show the same kind of physical quantity, i.e. the phase. However, it is possible to select thumbnails of magnified images showing different kinds of physical quantities and display them together on the range-indicating image 34. Furthermore, as already noted, the previously described processes and operations can be performed for not only the sample's altitude and phase but also any kind of physical quantity that can be observed or measured with the SPM.

(28) Although an SPM was taken as an example in the previous embodiment, it is obvious that the present invention can be generally applied to any surface analyzer capable of measuring a two-dimensional distribution of different kinds of physical quantities within a predetermined area on the surface of a sample. Examples of such surface analyzers include laser microscopes and electron probe micro analyzers.

(29) It should be noted that the previous embodiment is a mere example of the present invention, and any change, modification or addition appropriately made within the spirit of the present invention will evidently fall within the scope of claims of the present patent application.

EXPLANATION OF NUMERALS

(30) 1 . . . Sample 2 . . . Sample Stage 3 . . . Scanner 4 . . . Cantilever 5 . . . Probe 6 . . . Displacement Calculator 7 . . . Scanner Driver 10 . . . Displacement Detector 11 . . . Laser Source 12 . . . lens 13 . . . Beam Splitter 14 . . . Mirror 15 . . . Photodetector 20 . . . Personal Computer 21 . . . Controller 22 . . . Data Processor 23 . . . Data Memory 24 . . . Display Processor 25 . . . Input Unit 26 . . . Display Unit 30 . . . Sample Observation Display Screen 31 . . . Real-Time Image Display Window 32 . . . Image History Display Window 33 . . . Navigation Window 34 . . . Range-Indicating Image 35 . . . ROI-Setting Frame