Operation method of a scanning acoustic microscope and a scanning acoustic microscope

Abstract

The present invention relates to a method of operating a scanning acoustic microscope, which is particularly an ultrasonic scanning microscope, and in particular, a transducer unit (10) having one or more transducer elements (1, 2, 3, 4, 12, 14), each comprising a transducer (20) and a lens (21, 22), scans a sample in the X-Y plane, the transducer unit (10) is moved in the X direction for a linear scan of the sample, after the linear scan of the sample by the transducer unit (10), the transducer unit (10) is displaced in the Y direction by a displacement increment (U, W), the magnitude of the displacement increment (U, W) in the Y direction of the transducer unit (10) is varied for the scan of the sample, and in particular, after the displacement of the transducer unit (10) in the Y direction, at least one further linear scan of the sample is performed in the Y direction by the transducer unit (10).

Description

Technical Field

[0001] The present invention relates to an operating method of a scanning acoustic microscope, particularly an ultrasonic scanning microscope, and a scanning acoustic microscope, particularly an ultrasonic scanning microscope.

Background Art

[0002] An ultrasonic microscope, also called a scanning acoustic microscope (SAM), is used to scan a sample with ultrasonic waves in a scanning manner and process the reflected sound waves to generate an image of the structure of the sample.

[0003] An ultrasonic microscope includes an ultrasonic head, also called a transducer head. Thus, the ultrasonic head includes an acoustic lens and an acoustic transducer (transducer) connected thereto.

[0004] When performing an inspection using an acoustic microscope, water is used as a coupling medium between the acoustic transducer and the sample to be inspected in order to allow sound waves to propagate well from the transducer to the sample. For this purpose, a coupling medium having characteristics suitable for sound wave conduction is required.

[0005] In an ultrasonic microscope operating in a frequency band of 1 MHz to 5 GHz, it is common to immerse the sample in a water bath and place it on a sample holder, and the inspection of the sample is performed by the immersion method using the ultrasonic microscope. In other methods, a water flow formed between the acoustic transducer and the sample is used to ensure good acoustic coupling to the sample.

[0006] An ultrasonic microscope that scans a sample with ultrasonic waves and processes the transmitted or reflected sound waves to generate an image is known from the prior art. This imaging is non-destructive, and thereby information regarding the internal structure of the sample can be obtained. The image obtained by the scanning method enables analysis or monitoring of materials, electronic components, etc.

[0007] Furthermore, in an acoustic microscope, a multi-channel transducer in which a very large number of individual elements having a fixed focal length are arranged adjacent to each other is used. As a result, the pixel size in the Y direction, that is, the direction perpendicular to the scanning direction in the X direction, corresponds to the distance between the individual transducer elements. When such a multi-channel transducer is used, a large number of parallel straight scanning lines corresponding to the number of transducer elements are recorded simultaneously. In the case of the transducer elements of the multi-channel transducer, the distance between the individual elements is constant and cannot be changed, the height of the line of the linear scan is fixed, and the pixel size in the Y direction (that is, perpendicular to the scanning direction in the X direction) always corresponds to the width of the individual transducer elements and is constant. Since the dimension of the individual elements in the Y direction, that is, the direction perpendicular to the scanning direction in the X direction, is small, the aperture of the lens of the transducer element in this direction becomes very small, and thereby the resolution in the Y direction becomes small.

[0008] One object of the present invention is to enhance the applicability in a scanning acoustic microscope or an acoustic microscope for inspecting a sample such as a wafer. Another object of the present invention is to inspect a large number of samples or a large-area sample by an acoustic microscope, particularly an ultrasonic scanning microscope, in an efficient and simple manner with a particularly high data throughput.

Summary of the Invention

[0009] This object is achieved by a method of operating a scanning acoustic microscope, particularly an ultrasonic scanning microscope, which has a transducer unit having one or more transducer elements each having one transducer and one lens, respectively, by which a sample is scanned in the X-Y plane, the transducer unit is moved in the X direction for a linear scan of the sample, after the linear scan of the sample by the transducer unit, the transducer unit is displaced in the Y direction by a displacement increment, and for the scan of the sample, the magnitude of the displacement increment of the transducer unit in the Y direction is changed, and in particular, after the displacement of the transducer unit in the Y direction, at least one further linear scan of the sample is performed by the transducer unit in the Y direction.

[0010] A particularly advantageous aspect of this method is that during the inspection of the sample by the scanning method, the increment of the displacement of the transducer unit in the Y direction during the execution of the scanning method is changed, so that a specific region of the sample can be scanned at a higher (pixel) resolution and other less - focused regions of the sample can be scanned at a lower (pixel) resolution, respectively, in order to inspect them. Thereby, the inspection time for the entire sample can be shortened.

[0011] A further advantage of this method is that the scanning method enables the use of a transducer unit with a plurality of transducer elements, the lateral dimension of the transducer element being larger than the pixel size, and in the method according to the invention, the limitation of the free selection of the pixel size and the loss of resolution and detection sensitivity are avoided. In particular, the deviation of each transducer element from its reference position is calibrated and input into a calibration table, for example. In a transducer unit having transducer elements with the same focal length, the scanned surface of the sample is divided and the sample is scanned line - by - line by each of the individual transducer elements.

[0012] An acoustic microscope, in particular an ultrasonic scanning microscope, for implementing this method comprises a positioning system, at least one transducer unit, in particular a plurality of transducer elements, a pulse generator unit for the transducer unit, preferably a number of pulse generators corresponding to the transducer elements, a receiving unit, in particular one receiving device for each transducer element, and further comprises a data processing system and a module for digitizing the received analog ultrasonic signals.

[0013] In the method according to the invention, in the case of a transducer unit comprising a plurality of transducer elements, the lateral distance between the individual transducer elements is preferably taken into account on the basis of a (prior) calibration so that the surface to be examined and scanned of the sample is scanned in an optimal manner. Thereby, when performing a continuous line, i.e., a linear scan (X direction), with a pre-set and configurable number of image points per line, the distance from line to line in the Y direction can be freely selected. Preferably, the linear scan is performed with the same small displacement increment in the Y direction until the maximum distance between transducer elements of the same characteristic is reached, and then the transducer unit is moved with a large displacement increment in the Y direction by this distance, whereby a high-resolution image of the surface of the object to be inspected is generated with an increased analysis speed.

[0014] As a further development of this method, a plurality of linear scans (X direction) of the sample are performed by the transducer unit, and the transducer unit is displaced in the Y direction, preferably by a constant, small displacement increment, after each linear scan of the sample. After a plurality of linear scans of a predetermined number n (n≥2, 3, …) of samples, the transducer unit is displaced in the Y direction by a large displacement increment that is larger than the small displacement increment, preferably a constant one, and / or after a linear scan of the sample, the transducer unit is displaced in the Y direction by a large displacement increment, preferably a constant one. And after the displacement of the transducer unit by the large displacement increment, a plurality of linear scans of the sample of a plurality n (n≥2, 3, …) are performed by the transducer unit. After each linear scan of the plurality n (n≥2, 3, …) of samples, the transducer unit is displaced in the Y direction by a small displacement increment that is smaller than the large displacement increment, preferably a constant one, respectively.

[0015] Thus, a high-resolution image of the surface of the object to be inspected of the sample is obtained. For example, the pixel size or the distance of the linear scan (Y direction) is smaller than the distance between the individual transducer elements (Y direction) of a preferably linear transducer element array. In particular, the ratio of the pixel size or the distance of the linear scan to the distance between the individual transducer elements (Y direction) is less than 1:10, in particular less than 1:100, and further, in particular less than 1:1000.

[0016] Furthermore, a method in which the transducer unit is moved along a meandering path in the X-Y plane with respect to the sample is preferred. For this purpose, a corresponding positioning system is provided for moving the transducer unit with respect to the sample to be inspected.

[0017] Furthermore, according to an exemplary embodiment, in this method, a.) Scanning a sample using a scanning acoustic microscope having a plurality of transducer elements each comprising one transducer and one lens, in particular a transducer unit for an ultrasonic scanning microscope, with at least two transducer elements having different focal lengths, or b.) The sample is scanned using a transducer unit having a plurality of transducer elements each comprising one transducer and one, preferably, acoustic lens, in particular, the transducer elements have the same focal length and / or the transducer elements are arranged adjacent to each other linearly or rhomboidally in the Y direction.

[0018] Furthermore, a further development of this method is that the transducer unit comprises a plurality of transducer elements arranged in the Y direction, preferably one behind the other and / or linearly, and by each transducer element, a plurality of linear scans m (m≥2, 3, 4, …) are performed in the X direction, and the distances of the plurality of linear scans m (m≥2, 3, 4, …) by each transducer element are equally spaced in the Y direction. After the execution of the plurality of linear scans m (m≥2, 3, 4, …) by the transducer unit, the transducer unit is displaced in the Y direction by a displacement increment corresponding to the product of the distance of the equally spaced linear scans having the number m (m≥2, 3, 4, …) of linear scans and the number of transducer elements of the transducer unit in the Y direction.

[0019] Advantageously, in this method, the achieved image resolution does not depend on the distance and arrangement of the individual transducer elements, for example an array. Furthermore, the individual transducer elements can be freely adjusted or optimized with respect to the resolution and their signal strength.

[0020] The image resolution achieved or to be achieved by this method does not depend on the distance and arrangement of the individual transducer elements of the transducer unit or transducer array. In particular, the individual transducer elements can be configured with respect to their resolution and their focal length as required.

[0021] By using transducer elements with different focal lengths in the transducer unit, the surface or plane of the sample to be inspected in one or more depth planes, which is determined or to be determined by the corresponding focal lengths of the individual transducer elements of the transducer unit or transducer array, is scanned by the method of one embodiment. Further, according to other aspects, during the creation of the image, possible deviations are corrected such that the lateral deviation of each individual transducer element is calibrated, the scanning area is enlarged by a corresponding amount, and a seamless, matching image is generated.

[0022] In a further exemplary embodiment, in the method, a transducer unit preferably having a plurality of transducer elements has a length in the Y direction. After a plurality of linear scans in the X direction by the transducer unit, the transducer unit is displaced in the Y direction by a displacement increment corresponding to the length of the transducer unit, and the distance of each of the plurality of linear scans performed before displacing the transducer unit in the Y direction by a displacement increment corresponding to the length of the transducer unit corresponds to a natural fraction of the length of the transducer unit (length of the transducer unit / t, t ≧ 2, 3, 4,...).

[0023] Furthermore, in another development method, the transducer unit preferably comprises a plurality of transducer elements arranged in the Y direction adjacent to and / or linearly with respect to each other. Each transducer element has a width in the Y direction of one, preferably constant. A plurality of linear scans p (p≥2, 3, 4, …) are performed in the X direction. The distance between the plurality of linear scans p (p≥2, 3, 4, …) corresponds to a fraction of the width of the transducer element (width of the transducer element / p, p≥2, 3, 4, …). After the execution of p (p≥2, 3, 4, …) linear scans, the transducer unit is displaced in the Y direction by a displacement increment corresponding to a multiple of the width of the transducer element.

[0024] In one configuration of this method, in particular, a large displacement increment in the Y direction of the transducer unit is preferably corrected by an error tolerance correction value after the execution of a plurality of linear scans by the transducer unit. In particular, the error tolerance correction value is formed such that the distance in the Y direction from the last linear scan before the displacement of the transducer unit due to the large displacement increment to the first linear scan after the displacement of the transducer unit due to the large displacement increment matches the distance of the plurality of linear scans before and / or after the displacement in the Y direction of the transducer unit due to the large displacement increment. Or, in particular, the error tolerance correction value is formed such that the distance between all linear scans by the transducer unit is constant.

[0025] In particular, the transducer unit comprises a plurality of transducer elements, and the transducer elements operate in parallel. Preferably, the pulse generator for each transducer element and / or the receiving device for each transducer element operate in parallel. Alternatively, in one configuration, pulse operation is performed with a time offset of the total attenuation time of the transducer signal, minimizing crosstalk between individual transducer elements and / or the signals of the transducer elements caused by sound waves do not interfere with adjacent transducer elements.

[0026] In connection with the present invention, for the execution of the method, it is possible for the transducer unit to comprise a plurality of transducer elements in a compact design where the transducer elements are separated from each other or are monolithic blocks for the transducer elements.

[0027] Furthermore, in this method, in one configuration, the distance between the transducer unit and the sample surface is controlled by the transducer element. Alternatively, the distance control between the transducer unit and the sample can be realized by weight values of various transducer elements, for example, by using corresponding algorithms.

[0028] Regarding the performance of this method, a scanning acoustic microscope, each having one transducer and one preferably acoustic lens, and in particular a transducer unit for an ultrasonic scanning microscope, in which at least two transducer elements have different focal lengths, is provided.

[0029] When using the transducer unit in a scanning acoustic microscope, preferably a plurality of linear scans are performed simultaneously in a single scanning method, and due to the different focal lengths of the transducer elements of the transducer unit, scans are performed simultaneously in different planes of the sample. Therefore, during the scanning operation, different scanning regions of the sample to be inspected are obtained in different planes of the sample.

[0030] Excluding the transducer for generating the acoustic signal and the acoustic lens for focusing, each transducer element further includes a pulse generator, a transmit / receive switch, a receiver for receiving the acoustic signal reflected or transmitted in the sample, and an A / D converter for converting the received acoustic signal into digital values to create a display (gray scale) image. The ultrasonic signal reflected or transmitted in the sample is measured and converted to generate an image. Furthermore, the propagation time or phase shift of the signal is acquired as additional image information. In the scanning method, the sample is scanned pixel by pixel and line by line. Thereby, the transducer unit or the transducer element is moved relative to the sample to be inspected.

[0031] For this purpose, in a preferred further development of the transducer unit, preferably exclusively, two transducer elements having different focal lengths with respect to the X-Y plane are arranged linearly adjacent to each other in the Y direction, or arranged one behind the other in the X direction, or preferably exclusively, two transducer elements having different focal lengths with respect to the X-Y plane are arranged offset from each other in the X direction and the Y direction, in particular obliquely.

[0032] Furthermore, in another configuration of the transducer unit, the transducer unit comprises a plurality of transducer elements each having a first focal length with respect to the X-Y plane and a plurality of transducer elements each having a second focal length different from the first focal length. An array of transducer elements having the first focal length and arranged linearly adjacent to each other in the Y direction, in particular, and an array of transducer elements having the second focal length and arranged linearly adjacent to each other in the Y direction are arranged one behind the other in the X direction, or an array of transducer elements having the first focal length and arranged linearly adjacent to each other in the Y direction, in particular, and an array of transducer elements having the second focal length and arranged linearly adjacent to each other in the Y direction are arranged offset from each other in the X direction and the Y direction, in particular obliquely, or transducer elements having the first focal length and transducer elements having the second focal length are arranged in an alternating order, one behind the other in the Y direction, in particular linearly.

[0033] According to another advantageous development, the transducer unit comprises, in particular, two or more transducer elements each having a first focal length and two or more transducer elements each having a second focal length. By using a plurality of arrays of transducer elements for an acoustic microscope, in particular two or more transducer elements having the first focal length and two or more transducer elements having the second focal length, in parallel or simultaneously, different focal lengths of the transducer elements enable a plurality of exposures or images to be obtained simultaneously in different planes during the inspection process of the sample, thus increasing the applicability of the acoustic microscope. Furthermore, due to the array, a plurality of transducer elements with one focal length scan the sample over a wider width or a wider scanning area in the Y direction, thus shortening the inspection time in the scanning method.

[0034] Furthermore, this object is solved by a scanning acoustic microscope, in particular an ultrasonic scanning microscope, which is formed with a transducer unit as described above, or the scanning acoustic microscope is configured to carry out the above-described method according to any one of claims 1 to 11, in particular for operating an acoustic microscope. For the sake of avoiding repetition, express reference is made to the above description.

[0035] Incidentally, in connection with the present invention, a method of operating a scanning acoustic microscope, in particular an ultrasonic scanning microscope, is provided as the subject of an independent invention, in which method a sample is scanned in the X-Y plane by means of the above-described transducer unit, in particular one or more transducer elements each having one transducer and one lens, the transducer unit is moved in the X direction to perform a linear scan of the sample, after the linear scan of the sample by the transducer unit, the transducer unit is displaced in the Y direction by a displacement increment, and in particular, after the displacement of the transducer unit in the Y direction, at least one further linear scan of the sample is performed in the Y direction by the transducer unit.

[0036] In this case, in the scanning method, the sample to be inspected is displaced in the Y direction by a constant displacement increment by the transducer unit after each linear scan in the X direction. Preferably, the transducer unit comprises a plurality of transducer elements, and the transducer elements are operated in parallel. In particular, according to another aspect, the transducer unit moves along a meandering path in the X-Y plane with respect to the sample.

[0037] Other features of the present invention will become apparent from the description of the embodiments according to the present invention, the claims and the attached drawings. The embodiments according to the present invention can satisfy individual features or combinations of a plurality of features.

[0038] In the context of the present invention, features specified as "in particular" or "preferably" should be understood as optional features. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Hereinafter, based on exemplary embodiments with reference to the drawings, the general inventive concept will be described without limiting it, and for all details regarding the invention not further described in the text, explicit reference is made to the drawings.

Figure 1a

Figure 1b

Figure 2a

Figure 2b

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0040] In the drawings, the same or similar types of members and / or components are given the same reference numbers, and corresponding re - descriptions are omitted respectively.

[0041] Figures 1a and 1b are respectively schematic perspective views of longitudinal sections of a transducer unit 10 for an acoustic microscope, particularly for an ultrasonic scanning microscope.

[0042] The transducer unit 10 in Fig. 1a includes transducer elements 1, 2, 3, 4 arranged linearly adjacent to each other in a direction perpendicular to the scanning direction of the transducer unit 10 in the Y direction, i.e., the X direction, and they all have the same focal length. The transducer elements 1, 2, 3, 4 have the same structure and each includes a transducer 20 and an acoustic lens 21 arranged on the transducer 20 for concentrating an ultrasonic signal on a sample to be inspected.

[0043] In the exemplary embodiment of Fig. 1b, the transducer unit 10 is configured by linearly arranging transducer elements 1, 12, 3, 14 in the Y direction alternately. The transducer elements 1, 3 each have a (first) focal length, the transducer elements 12, 14 have a (second) focal length, and the focal length of the transducer elements 1, 3 is different from the focal length of the transducer elements 12, 14. Here, the transducer elements 12, 14 have lenses 22, and their focal lengths are different from the focal length of the lens 21 for the transducer elements 1, 3.

[0044] Figs. 2a and 2b respectively show schematic perspective views of longitudinal sections of the transducer unit 10 for an acoustic microscope, particularly an ultrasonic scanning microscope.

[0045] The design of the other transducer unit 10 according to Figs. 2a and 2b is different from the configuration of the transducer unit 10 according to Figs. 1a and 1b in the arrangement of the transducer elements.

[0046] In the configuration of the transducer unit 10 according to Fig. 2a, compared with the transducer unit 10 in Fig. 1a, the transducer elements 1, 3 are shifted in the X direction with respect to the transducer elements 2, 4. The transducer elements 1, 2, 3, 4 each have the same focal length.

[0047] In the configuration of the transducer unit 10 according to Fig. 2b, compared with the transducer unit 10 in Fig. 1b, the transducer elements 1, 3 are shifted in the X direction with respect to the transducer elements 12, 14. The transducer elements 1, 3 each have the same focal length, which is different from the focal length of the transducer elements 12, 14.

[0048] FIG. 3 schematically shows a single first scanning region 100.1 of a transducer unit 10 having the configuration of FIG. 1a with transducer elements 1, 2, 3, 4 having the same focal length for a sample to be inspected. By the transducer elements 1, 2, 3, 4 at the position Y1 in the Y direction, the image lines "Y1 transducer element 1", "Y1 transducer element 2", "Y1 transducer element 3", "Y1 transducer element 4" are simultaneously obtained in the linear scanning of the sample corresponding to the reflected signals from the sample to the transducer elements 1, 2, 3, 4 in the scanning in the X direction, for example, as a display on a monitor.

[0049] Thereafter, at the end position, the transducer unit 10 is moved from the Y-direction position Y1 to the Y-direction position Y2 by a small displacement increment U in the Y direction (see FIG. 5), whereby, in the linear scanning of the sample, the image lines "Y2 transducer element 1", "Y2 transducer element 2", "Y2 transducer element 3", "Y2 transducer element 4" are obtained from the sample. Thereafter, the transducer unit 10 is moved from the Y-direction position Y2 to the Y-direction position Y3 by a small displacement increment U in the Y direction (see FIG. 5), and the image lines "Y3 transducer element 1", "Y3 transducer element 2", "Y3 transducer element 3", "Y3 transducer element 4" are sequentially obtained by the transducer elements 1, 2, 3, 4. Similarly, thereafter, the transducer unit 10 is further moved from the Y-direction position Y3 to the Y-direction position Y4 by a small displacement increment U in the Y direction (see FIG. 5), and the image lines "Y4 transducer element 1", "Y4 transducer element 2", "Y4 transducer element 3", "Y4 transducer element 4" are simultaneously acquired in the linear scanning in the X direction.

[0050] In FIG. 4, the entire scanning area 100 of the transducer unit 10 of the acoustic microscope for the inspection of the sample is schematically shown. As shown with reference to FIG. 3, after the acquisition of the entire scanning area 100.1 by four linear scans in the X direction, the transducer unit 10 is displaced in the Y direction by a displacement increment W (see FIG. 5) that is larger than the displacement increment U (see FIG. 5) between the Y-direction positions Y1, Y2, Y3, Y4. In particular, the displacement increment W in the Y direction of the transducer unit 10 corresponds to a length resulting from the product of the equal distance U of the linear scan, the number m of linear scans (m = 4 in this embodiment), and the number of transducer elements in the Y direction of the transducer unit 10 (4 in this embodiment).

[0051] In other configurations, the Y-direction distances of the four linear scans at the positions Y1, Y2, Y3, Y4 correspond to a part of the widths of the transducer elements 1, 2, 3, 4. After the execution of the four linear scans in the X direction, the transducer unit is displaced in the Y direction by a displacement increment corresponding to a multiple of the width of the transducer element.

[0052] As explained with reference to FIG. 3, after the acquisition and complete display of the scanning area 100.1 and after the displacement in the Y direction by the large displacement increment W (see FIG. 5), the transducer unit 10 is moved from the Y-direction position Y4 to the Y-direction position Y5 for the acquisition of the subsequent scanning area 100.2. The transducer unit 10 is moved in a meandering manner from the Y-direction position Y5 to the other Y-direction positions Y6, Y7, Y8 in the scanning method for the acquisition of the scanning area 100.2 in order to generate the respective image lines of the four Y-direction positions Y5, Y6, Y7, Y8 by the transducer elements 1, 2, 3, 4 by linear scanning of the sample. These method steps between the individual Y-direction positions of the transducer unit 10 and between two consecutive scanning areas are repeated several times in a corresponding manner until the last scanning area 100.n for the Y-direction positions Yn, Yn+1, Yn+2, Yn+3 is scanned by the transducer elements 1, 2, 3, 4 and the corresponding image lines are generated.

[0053] In the context of the present invention, instead of the transducer unit 10 of FIG. 1a, a transducer unit 10 with a schematic configuration according to FIG. 1b or FIG. 2a or FIG. 2b or a plurality of transducer elements arranged in a predetermined array in the X direction and / or Y direction can be used, and / or another transducer unit with different focal lengths can be used for the acquisition of the entire scanning area 100. The transducer units 10 are each moved according to one, in particular meandering, scanning method having different displacement increments in the Y direction during the scanning method.

[0054] FIG. 5 shows in detail a schematic view of the scanning path of a transducer unit 10 (see FIG. 4) having four transducer elements 1, 2, 3, 4 across the cross-section of the sample surface of the sample. For the acquisition of the scanning areas 100.1, 100.2, the transducer unit 10 is moved in the Y direction by a (small) displacement increment U between a plurality of Y-direction positions Y1, Y2, Y3, Y4 or Y5, Y6, Y7, Y8 of the respective scanning areas 100.1, 100.2, and after the acquisition of the scanning areas 100.1, 100.2, it is moved by a displacement increment W larger than the displacement increment U.

[0055] The movement of the transducer unit 10 is performed in the form of a meander 30, whereby the sample is scanned while meandering. Thereby, the Y-direction increment of the meander 30 of the transducer unit 10 varies with the Y-direction displacement increments U, W for acquiring the entire scanning area 100.

[0056] In the exemplary embodiment of FIG. 6, a transducer unit 10 with two transducer elements 1, 12 and the entire scanning areas 101, 112 for the two transducer elements 1, 12 are schematically shown. The transducer elements 1, 12 have different focal lengths in this configuration.

[0057] As can be seen from FIG. 6, the transducer elements 1 and 12 are arranged in the transducer unit 10 with an offset in the X and Y directions. Thus, when scanning a sample, the entire scanning regions 101 of the transducer element 1 and 112 of the transducer element 12 are also formed corresponding to each other with an offset in the X and Y directions. Therefore, the images of the entire generated scanning regions 101 and 112 obtained by the transducer elements 1 and 12 are displayed with an offset. In one configuration, for the linear scanning by the transducer elements 1 and 12, the transducer unit 10 moves while meandering the sample, and the Y increment between two linear scans is constant.

[0058] In still another configuration (not shown here), for example, instead of the transducer unit 10 shown in FIG. 6, the transducer unit 10 shown in FIG. 2b is used to acquire the entire scanning regions 101 and 112, and the transducer unit 10 is moved according to a scanning method having different displacement increments in the Y direction, each having a different displacement increment in the Y direction, particularly a meandering one. Also, by using a transducer unit having a plurality of transducer elements with different focal lengths, other configurations of the scanning method can also be realized, and when acquiring the entire scanning region, the transducer unit moves with different displacement increments in the Y direction according to a scanning method that particularly meanders.

[0059] All of the cited features, including those obtained only from the drawings, as well as the individual features disclosed in combination with other features, are considered to be essential to the present invention both individually and in combination. Embodiments according to the present invention can be realized by individual features or combinations of a plurality of features.

Explanation of Reference Numerals

[0060] 1, 2, 3, 4 Transducer elements 10 Transducer unit 12, 14 Transducer elements 20 Transducer 21, 22 Lenses 30 Meandering 100 Entire scanning region 101 Entire scanning region Scanning areas 100.1, 100.2,..., 100.n Entire scanning area 112 Increment of U displacement Increment of W displacement

Claims

1. A method of operating a scanning acoustic microscope such as an ultrasonic scanning microscope, wherein a transducer unit (10), in particular one or more transducer elements (1, 2, 3, 4, 12, 14) each having one transducer and one lens, scans a sample in the X-Y plane, the transducer unit (10) is moved in the X direction for a linear scan of the sample, after the linear scan of the sample by the transducer unit (10), the transducer unit (10) is displaced in the Y direction by a displacement increment, for the scan of the sample, the magnitude of the displacement increment in the Y direction of the transducer unit (10) is changed, in particular after the displacement of the transducer unit (10) in the Y direction, at least one other linear scan of the sample is performed in the Y direction by the transducer unit (10).

2. A plurality of linear scans of the sample are performed by the transducer unit (10), and after each linear scan of the sample, the transducer unit (10) is displaced in the Y direction by a preferably constant, small displacement increment (U), and after a plurality of linear scans of a predetermined number n (n ≥ 2, 3,...) of the sample, the transducer unit (10) is displaced in the Y direction by a large displacement increment (W) that is larger than the small displacement increment (U), preferably constant, and / or after each linear scan of the sample, the transducer unit (10) is displaced in the Y direction by a preferably constant, large displacement increment (W), and after the displacement of the transducer unit by the large displacement increment (W), a plurality of linear scans of the sample, n (n ≥ 2, 3,...), are performed by the transducer unit (10), and after each linear scan of the plurality of linear scans of the sample, n (n ≥ 2, 3,...), the transducer unit (10) is displaced in the Y direction by a small displacement increment (U) that is smaller than the large displacement increment (W), preferably constant. The method according to claim 1.

3. The method according to claim 1 or claim 2, wherein the transducer unit (10) is moved along a path that meanders in the X-Y plane with respect to the sample.

4. a.) the sample is scanned with a transducer unit (10) for a scanning acoustic microscope, in particular for an ultrasonic scanning microscope, having a plurality of transducer elements (1, 2, 3, 4, 12, 14) each with one transducer (20) and one lens (21, 22), at least two transducer elements (1, 2, 3, 4, 12, 14) with different focal lengths, or b.) The method according to any one of claims 1 to 3, in which the sample is scanned using a transducer unit (10) having a number of transducer elements (1, 2, 3, 4, 12, 14) each with one transducer (20) and one, preferably acoustic lens (21, 22), in particular in which the transducer elements (1, 2, 3, 4, 12, 14) have the same focal length and / or the transducer elements (1, 2, 3, 4, 12, 14) are arranged next to each other in a straight line or in a diamond shape in the Y direction.

5. 5. The method according to claim 1, wherein the converter unit (10) comprises a plurality of transducer elements (1, 2, 3, 4, 12, 14) arranged in the Y direction, preferably back-to-back and / or linearly, a plurality of m (m≧2, 3, 4, ...) linear scans are performed in the X direction by each of the transducer elements (1, 2, 3, 4, 12, 14), the distances of the plurality of m (m≧2, 3, 4, ...) linear scans by each of the transducer elements (1, 2, 3, 4, 12, 14) being equidistant in the Y direction, and after the performance of the plurality of m (m≧2, 3, 4, ...) linear scans by the converter unit (10), the converter unit (10) is displaced in the Y direction by a displacement increment corresponding to the product of the equidistant intervals of the plurality of m (m≧2, 3, 4, ...) linear scans and the number of the converter elements (1, 2, 3, 4, 12, 14) of the converter unit (10).

6. Preferably, the converter unit (10) comprising a plurality of converter elements (1, 2, 3, 4, 12, 14) has the length in the Y direction, and after a plurality of linear scans in the X direction by the converter unit (10), the converter unit (10) is displaced in the Y direction by a displacement increment corresponding to the length of the converter unit (10), and the distance of each of the plurality of linear scans performed before the displacement in the Y direction by a displacement increment corresponding to the length of the converter unit (10) is one natural number fraction of the length of the converter unit (10) (the length of the converter unit / t: t ≧ 2, 3, 4,...). The method according to any one of claims 1 to 5.

7. The converter unit (10) preferably comprises a plurality of converter elements (1, 2, 3, 4, 12, 14) arranged adjacent to each other and / or linearly in the Y direction, and the converter elements (1, 2, 3, 4, 12, 14) each have one, preferably a constant, width in the Y direction, and a plurality of p (p ≧ 2, 3, 4,...) linear scans are performed in the X direction. The distance between the plurality of p (p ≧ 2, 3, 4,...) linear scans corresponds to one fraction of the width of the converter element (1, 2, 3, 4, 12, 14) (the width of the converter element (1, 2, 3, 4, 12, 14) / p: p ≧ 2, 3, 4,...), and after the execution of the plurality of p (p ≧ 2, 3, 4,...) linear scans, the converter unit (10) is displaced in the Y direction by a displacement increment corresponding to a multiple of the width of the converter element (1, 2, 3, 4, 12, 14). The method according to any one of claims 1 to 5.

8. A particularly large displacement increment (W) in the Y direction of the transducer unit (10) is corrected by an error tolerance correction value after execution of a plurality of linear scans by the transducer unit (10). In particular, the error tolerance correction value is such that the distance in the Y direction from the last linear scan before displacement of the transducer unit (10) by a large displacement increment (W) to the first linear scan after displacement of the transducer unit (10) by a large displacement increment (W) is equal to the distance in the Y direction of a plurality of linear scans before and / or after displacement of the transducer unit (10) by a large displacement increment (W), or, in particular, the error tolerance correction value is formed such that the distances between all linear scans by the transducer unit (10) are constant. The method according to any one of claims 5 to 7.

9. The method according to any one of claims 1 to 8, wherein the transducer unit (10) comprises a plurality of transducer elements (1, 2, 3, 4, 12, 14) which operate in parallel.

10. In particular, in case a.), preferably exclusively, two transducer elements (1, 2, 3, 4, 12, 14) having different focal lengths with respect to the X-Y plane are arranged linearly adjacent to each other in the Y direction, or are arranged one behind the other in the X direction, or, preferably exclusively, two transducer elements (1, 2, 3, 4, 12, 14) having different focal lengths with respect to the X-Y plane are displaced relative to each other in the X direction and the Y direction, in particular arranged obliquely. The method according to any one of claims 4 to 9.

11. In particular, in case a.), the transducer unit (10) comprises a plurality of transducer elements (1, 2, 3, 4, 12, 14) each having a first focal length with respect to the X-Y plane and a plurality of transducer elements (1, 2, 3, 4, 12, 14) each having a second focal length different from the first focal length, an array of transducer elements (1, 2, 3, 4, 12, 14) having the first focal length and arranged adjacent to each other in the Y direction, in particular linearly, and an array of transducer elements (1, 2, 3, 4, 12, 14) having the second focal length and arranged adjacent to each other in the Y direction, in particular linearly, are arranged one behind the other in the X direction, Alternatively, an array of transducer elements (1, 2, 3, 4, 12, 14) having the first focal length and arranged adjacent to each other in the Y direction, particularly linearly, and an array of transducer elements (1, 2, 3, 4, 12, 14) having the second focal length and arranged adjacent to each other in the Y direction, particularly linearly, are arranged offset from each other in the X direction and the Y direction, particularly obliquely. Or, a method according to any one of claims 4 to 10, wherein the transducer elements (1, 2, 3, 4, 12, 14) having the first focal length and the transducer elements (1, 2, 3, 4, 12, 14) having the second focal length are arranged alternately in the Y direction, particularly linearly, one behind the other. [

12. ] A scanning acoustic microscope, particularly an ultrasonic scanning microscope, wherein the scanning acoustic microscope is configured to perform the method according to any one of claims 1 to 11.

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