Kammrath & Weiss, Inc. is a United States Corporation, registered in New York
State and owned and operated by Jerome D. Schick. Originally, it was established to do
business in the United States on behalf of the German Company of the same name. In 2009
the German Company, Kammrath & Weiss, GMBH, decided to terminate its contract with
the USA company, form its own company, and conduct business in the United States through
that company. The company still specializes
in highly technical and sophisticated peripheral equipment for Scanning Electron
Microscopes, Focused Ion Beam Instruments, and other similar laboratory equipment.
The interested reader may investigate the Kammrath & Weiss, GMBH website, and he may
survey this and other companies for offerings of equipment that might interest him and
solve a technology problem he is pursuing. Although this organizational change was smooth and
amicable, the reader is encouraged to contact this present author, Jerome D. Schick, and
discuss the possibilities of equipment service as well as equipment purchase and applications
in the newly organized environment.
SEMICONDUCTOR INTERNATIONAL described the importance of the introduction of a probing capability into a Scanning Electron
Microscope and a Focused Ion Beam instrument. This, of course, has to do with the device
dimensions and the chip density. The size and density of integrated circuits make the probing
of individual devices on chips nearly impossible without better viewing of the circuit and
finer probe tips with more precise control.
There is a prober system which can be installed in a Focused Ion Beam
Instrument. The purpose of this device is to enable probing with four electrical needle
probes on an integrated circuit in situ inside the FIB.
For a discussion of some outstanding work performed at an Intel
Laboratory, CLICK HERE.
This is a .pdf file, so you will need Acrobat Reader to read the file. It
may take a while to download. Edwin Quijana, Paul Concepcion, and Terence Lacuesta show
the slides they used for this fine presentation.
The reader should appreciate the details regarding this work when he considers the size
of the individual contacts on the chip and the necessity of contacting four such contacts
by the four probes. The probed device is then exercised with a Semiconductor Device Tester to
obtain the characteristics for the single transistor. A discussion is also covered
in which a failed device is probed and analyzed to determine the cause for failure. Although a detailed discussion is
not available with these slides, the reader can follow the work by viewing the slides.
The term active probing typically refers to the measurement where an active chip is operating
and a measurement of some voltage node in the operating chip is measured. Usually the measurement
on an internal node using a mechanical probe tip touching the node will load the circuit
such that it will be measureably slower or even not function. Active probing utilizes a
probe tip with of high series resistance and low input capacitance, sometimes called tip
capacitance, such that the Device Under Test (DUT) continues to operate normally even when
probed. A probe used for passive probing may have 1 megohm/>10 pf input capacitance. Active
probing requires 1 megohm/<1 pf input capacitance. The input sensitivity also requires
noise-free amplification such that a FET amplifier very near the probe tip is essential
for adequate signal detection. Thus the active probing system requires an active
probe tip, a suitable probe arm for holding the tip/FET combination, and a power supply
appropriate for driving the amplifier system. The bandwidth of the probing system should
be DC to 300 MHz.
Although Kammrath & Weiss has yet to install its first Active Probing System using its
Prober System for SEMs and FIBs, the leakage current and capacitance measured with the signal cabling
already installed on probing systems is adequate for active probing. Triax signal cables
are typically supplied with the four-probe system allowing for the desireable driven shield
guard between the signal lead and the grounded shield. Triax cables are essential for low level
probing measurements using the typical Semiconductor Parameter Analyzer instrumentation for
device characterization inside an electron and/or ion beam system.
Authors from ANALOG DEVICES, Quality Systems, M.B. Ferrara and G.G. Owen described their
work in which
they performed Active Electron Beam Probing Techniques with an Existing Failure Analysis Process.
These authors did not utilize a probing system inside their SEM, but contacted
the DUT with socket pins and silver painted contacts. The present author, Jerome D. Schick,
has demonstrated the same techniques using probing systems. These probing results are
discussed earlier in this site and elsewhere. At this writing, he has not yet demonstrated
an Active Probing Measurement using the Kammrath & Weiss Probing System, but is confident
of being able to do so. The necessary socket to hold the functioning integrated circuit chip
mounted top-side-up on its module has not been selected or designed. The reader should remember
that all connections must be made to the chip inside the SEM or FIB in order for the chip to
operate. Then the operating chip may be probed with one or more active probe tips.
In November of 2003 a first-of-a-kind prober module that can be operated in a FEI
9800 Focused Ion Beam and also in a LEO 1550 Scanning Electron Microscope was installed. The operation for
this particular customer is to operate the prober in the FIB, with full X-, Y-, and Z- motions
of four independent probe tips, all motions with less than 0.1 micron tip placement accuracy.
The prober module may then be removed from the FIB and inserted in the SEM for the same full
probing capability. When desired, a sample rotation capability for the SEM may be used to
rotate the specimen under the probes. The probing mechanism for the FIB must be of materials
that will withstand the harsh, and often chemically reactive, environment in the FIB vacuum
chamber. This is not the case in the SEM chamber, but in order for the prober module to be
used in BOTH instruments, the more severe case determines the construction of the module.
In the last few years, although the interest in probing integrated circuits in an electron beam or
ion beam instrument has not decreased, the funding for such activities is diminishing. The
German Kammrath & Weiss, GmbH company has altered its direction to exclude most efforts in the
probing business. Although several advances in techniques were being considered, their marketing
emphasizes other metallurgical techniques and accessories.
Hopefully the difficult times will begin to improve to allow a return to their broader interests.