PELCO® Dimpler™ for TEM Thinning of Specimens

Termination

Process termination can be determined using the built-in timer, or by the Z Position. When using Z Position termination, the timer counts to measure the total time elapsed until the Z Position is reached. This is useful for creating process recipes for various sample types. Four factors improve the overall stability during processing, and the termination accuracy:

1. Non-Contact Position Sensor

2. Tool Phase Sensor

3. No external measuring device

4. Magnetically coupled arm damping

 

Damping

Damping of the arm is accomplished by using position information from the Non-Contact Position Sensor, processing it and feeding it back to the arm motor, which controls the up/down force of the arm. The position sensor and the processing circuit is fast enough to actively dampen any vibration the arm may experience. Since the damping force is magnetically coupled to the arm there is no mechanical play in the system, allowing damping response on the sub-micrometer level. Damping is adjustable from zero damping to stiff damping.
Damping offers three significant attributes:

1. Vibrations that can crack thin specimens are greatly reduced.

2. Keeps tools round, negating excess impacts, providing more accurate Z position control.

3. Tool gently contacts the specimen when the arm is lowered.

Automated Controls

Automated features make the dimpling process more repeatable and easier to use. Tools are raised and lowered at the touch of a button; dimpling force, damping force, fine balance, and Z offset (termination point) all are set from the front panel.
Once dimpling has begun no monitoring is necessary. After the initial specimen thickness has been measured, the specimen is mounted and the user simply selects a dimple depth and begins dimpling. The precise Z position of the tool/surface interface is continuously displayed while dimpling with any tool. When the selected dimple depth is reached the PELCO^® Dimpler™ controls will automatically raise the arm then stop the tool rotation, specimen rotation, and clock timer.


Specimen Mounting

Different mounts are available depending on the size and type of sample. TEM specimens are generally mounted on optically smooth sapphire flats. The low thermal mass of the flat reduces mounting and dismounting times and the smooth surface allows the dimpled specimens to be easily removed. The hardness of sapphire limits damage if specimens are accidentally perforated due to operator error. The retainer ring which secures the sapphire flat also serves as a slurry reservoir. This platen set is used with the traditional Dimpler tools. For larger specmens for surface analysis or delayering a separate, shorter magnetic base and platen set is used with larger diameter tools. These were developed for delayering and deprocessing.

 


PELCO^® Video Alignment Microscope (VAM)
 

The PELCO^® Video Alignment Microscope is an essential accessory for the PELCO^® Dimpler™, particularly for deprocessing/delayering and site-specific polising applications. It allows easy targeting of an area of interest, and precise control of the position, size, and shape of the bottom of the dimple or thin area of the specimen. It is particularly useful for selective surface polishing and delayering applications, where the low point and planarity of the polished area must be controlled to reveal the feature of interest. The VAM consits of a microscope optical system with a TFT display, a post corresponding precisely to the base mount on the PELCO^® Dimpler™ that is aligned to the optic axis of the microcope, a reticle to allow precise targeting of a particular area using the adjustable base, and an X-Y stage for precision alignment to the area of interest.