M4PP Microscopic Four-Point Probes

CAPRES M4PP Microscopic Four-Point Probes have an electrode pitch three orders of magnitude smaller than conventional four-point probes, and are fabricated using silicon micro-fabrication technology.

With the M4PP, a number of advantages compared with a conventional macroscopic 4-Point Probe is obtained: Accurate Rs-measurements on thinfilms Non-destructive probing No calibration needed Micro-scale resolution Measurements on product wafers

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Accurate Rs-measurements on thinfilms

As e.g. semiconductor devices becomes more and more integrated, device structures becomes smaller and smaller. The implanted regions (especially the Source-Drain Extension (SDE) region) therefore become thinner and thinner (in the nanometer-region – hence the designation Ultra Shallow Junctions). Measurement of the electrical sheet resistance (Rs) has for decades been a very important parameter in semiconductor characterization – but due to the size of macroscopic probes as well as the inevitable destructive penetration of the thin-film, they no longer provide accurate results.

	Fortunately, these crucial shortcomings are overcome by the M4PP, as this continues to provide the correct results as the layers become thinner. (See “Micro-scale Sheet Resistance Measurements On Ultra Shallow Junctions” by C.L. Petersen et al, Proceedings of RTP Conference, Kyoto October 2006).
	Four-point measurements as a function of electrode spacing on 11 nm, 50 nm and 70 nm deep profiles.

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Non-destructive probing

The M4PP contact force is 1,000,000 times smaller than that of a macroscopic 4-Point Probe. This ensures non-destructive probing of e.g. semiconductor-structures.

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No calibration needed

Due to the very well-defined manufacturing process, the probe pins are by design extremely accurately positioned with respect to each other. This ensures that no calibration of the individual probe is needed, and also results in an extremely low probe-to-probe variation (<0.1%).

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Micro-scale resolution

Picture of “The Little Mermaid” in 6-by-8 pixel resolution reveals little or no details.	Same picture, but this time in 600-by-800 pixel resolution. A multitude of detail is revealed. This “digital camera analogy” illustrates the difference in resolution obtained by a macroscopic and a microscopic 4-Point Probe, respectively.

By using an M4PP on e.g. laser-annealed structures, previously unseen variations in sheet resistance are revealed.

Comparison of macro and micro sheet resistance. A 25 µm-step line scan has been repeated with various four-point probe pitch. From ”A Comparative Study Of Size Dependent Four-point Probe Sheet Resistance Measurement On Laser Annealed Ultra Shallow Junctions”, D. H. Petersen et al, presented at INSIGHT 2007.

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Measurements on product wafers

With the M4PP, a wide range of new measurement options has become available. The plot at the left shows micro-scale sheet-resistance measurements performed inside a 120µm-by-150µm SIMS-pad.

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M4PP product range

CAPRES currently offers M4PPs with an electrode pitch of 5, 10, 15, 20, 25 and 30 µm.

	For the microRSP-M150, the probe chips are mounted on a ceramic carrier which fits into a high-precision 14-pin mating adaptor.
	For the next-generation microRSP-A300, an array of M4PP probe chips will be mounted in a cassette. The M4PP will be fully semiconductor-fabrication compatible: The probe coating material will be Ni, TiN, TiW or another suitable material.
	M4PP chip (10 micron electrode pitch) on ceramic carrier substrate.

The probes are designed for micro-scale electrical characterizations of materials, and are ideal for quality control in the semiconductor and thin-film industries. They can also be used for research, for example to image the electrical conductivity in single grains or domains in polycrystalline materials. For example, the probes are currently used to investigate micro-scale changes in electrical transport due to changes in surface reconstruction on clean silicon in UHV. This work is part of collaboration between MIC and the department of physics at the University of Tokyo, Japan.

CAPRES is also developing customized probes and probing techniques to solve customer specific measurement problems. We are able to make multi-point probes with electrode pitch down to 1.5 microns.

Custom Microscopic 12-Point Probe with 1.5 micron inner electrode pitch

Datasheets etc.

	The Microscopic Four-Point Probe
	Application Note - Handling of Microscopic Multi-Point Probes
	General M4PP Application Note

Send mail for more information.

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