AFM Probe Tip Solutions

StressedMetal™ Probes imaged by scanning electron microscopy (SEM). The MoCr beams on quartz substrate have different tip heights which allow for scanning of samples of varying heights.

StressedMetal™ probe tips improve the capabilities of scanning probe microscopes such as the atomic force microscope (AFM). These microscopes, which measure the topography of sample surfaces with nanometer precision and resolution, are used widely for a variety of applications in industrial and scientific research, including such areas as microelectronics and nanotechnology.

The low tip height of existing probes - typically one to 15 um - precludes the measurement of surfaces with deep trenches or high hills. Instead of straight cantilevers used in conventional probes, the StressedMetal probes use bent cantilevers. Their tips, with heights of up to more than 300 um, can be used to measure super-high topography samples that could not have previously been non-destructively measured.

Features

Unlike conventional cantilevers, which are fixed to the ends of the probe chips, the StressedMetal cantilevers are fixed under the probe chips. This results in much smaller probe dimensions and an integration density up to 300 percent higher than that of existing probe technologies - making the StressedMetal probes very cost-effective to produce. They are also more robust and easier to handle than existing probes

PARC's StressedMetal probes are based on bent cantilevers and have super-high tips which allow measurement of high-topography samples. The laser shines through a transparent substrate.

• Tip heights from tens to hundreds of micrometers
• Non-destructive measurements of high-topography samples
• Varying tip heights for different applications
• Density on wafer up to 300 percent higher compared to existing probe technologies
• Can be cost-effectively manufactured using surface micro-machining techniques

Applications

• non-destructive measurements on high-topography substrates for applications such as MEMS, DRIE and packaging
• depth-gauge AFM: PARC's StressedMetal probes can access narrow and deep structures and measure the depth quickly by two probe touch-downs
• electrical measurements: StressedMetal probes can measure currents and voltages and are therefore interesting candidates for electrical AFM techniques.
• liquid imaging: transparent substrate above the probe readily enables measurements of biological samples in liquids.

The StressedMetal probes are especially suited for super-high topography samples, but they can also be used for common measurements. Unlike conventional silicon probes, they can also be used for electrical measurements. They enable new applications such as nano-depth gauges and are of advantage for cantilever arrays.

Sample Images

Images below were taken with Digital Instruments Dimension 3100 AFM.

	Contact-mode scan of 200 nm deep silicon calibration sample.
	Non-contact mode scan of pentacene thin film sample.

	Non-contact mode scan strontium titanate (SrTiO3) sample surface.
	Roughness measurement on bottom of 80 µm deep Si trench made by RIE, image taken in non-contact mode.