scan modes of ultrasonic microscopy / Execution of non-destructive analyses

Scanning modes - also known as imaging modes - can perform non-destructive analyses of the internal structure of components under the acoustic microscope. In particular, these imaging modes help to explain the individual layers and structures of components for delamination and crack detection. To get detailed insights, different imaging or scanning modes are used.

The A-scan provides local time of flight from the sample—a time-dependent ultrasonic wave reflected by the component. This information digitizes the selected sample range by means of a previously selected data gate. This data gate for the quantitative time-distance measurement (echo time) is used to set electronic time windows in the depth. Appropriately selected ranges are then incorporated into the C-scan. A digital oscilloscope on the screen represents the incoming echo. If more than one time window is placed (X- or G-scans), multiple images are displayed on the monitor.

A-Scan

A-scan signal with selected gate (red box)
In principle, the B-scan involves stringing together A-scans. They produce a depth-resolved cross-section image of the component in the X direction. The gate is set for the entire time range, but can be configured by the user. With the help of the SAMnalysis software, additional options for the B-scan analysis are provided.

B-scan

Sectional image of an IC sample
In this case, the gate is set at a specific depth and width (controlled in WINSAM). Scanning the component in the X and Y directions generates a stratified image of the component, whose width corresponds to that of the set data gate. In the event of delaminated surfaces, this area can be marked red immediately (display of phase inversion).

C-scan

Planar mapping of an IC sample
Delaminated areas are red
In the X-scan, more than 100 C-scan images of varying depth ranges can be generated simultaneously and displayed in real time during one scanning operation.

X-scan

Various types of depth information of an
IC sample
The Z-scan mode acquires three-dimensional data records (tomographic information) and enables off-line reconstructions of B-, C-, D-, P-, X-, A-, and 3D-scans as well as runtime measurements of the images with user-selectable gates. These can then be processed by the SAMnalysis and WINSAM software.

Z-scan

Example showing an image reconstruction from a Z
-scan of an IC sample
A transducer positioned above the sample emits an ultrasound signal, which is detected by a second transducer below the sample. This scanning mode provides the user with information about the structure of the sample. In this process, both transducers analyze the sample simultaneously.

Through-scan

Transmission image of an IC sample