SEM Magnification Calibration
MRS-3

Applications

• Electron microscopy - SEM, in both SE and BSE mode, SEM/FIB and TEM (with special version)
• Scanning Microscopies and Profilometry - STM, AFM, the pattern height is 100nm
• Optical Microscopy - transmitted, reflected, bright/dark field, differential contrast and confocal
• Chemical mapping - EDS, WDS, XRF, XPS, Auger and others. The pattern is fabricated using 100nm CrO₂ and Cr on quartz
• Particle Size Counting - series of circles, squares and rectangles for calibration confirmation

Pattern Design

The MRS-3 is fabricated using the high accuracy direct write electron beam manufacturing equipment. The pattern is anti-reflective chromium (30nm Cr₂O over 70nm CR) on quartz. Imaging in both secondary and back scattered mode is very high. The pattern is coated with a proprietary conductive material which allows for SEM imaging at any accelerating voltage.

Geometric design

The MRS-3 has groups of nested squares with pitches of 2µm, 50µm and 500µm.  The largest pattern has an overall dimension of 8mm square with lines and spaces of 250µm. This can be used to check magnifications between 10 - 100x, The 50µm pitch patterns are useful from 100 - 1000x magnifications. The 2µm pitch allows calibrations up to 50,000x.

Dimensions

The overall size is approx. 9mm x 9mm x 2.3mm thick. The MRS-3 can be provided in a aluminum retainer with a size of 25mm diameter and 3mm thickness to protect the standard.

Optional Protective Retainer 614-5 and Optional Pin Stub Mounting 614-62		Optical Microscope Adapter OM/R 614-6

This is the most popular retainer and is usable for SEM and transmitted light applications. A special version of the MRS-3 is available for TEM which has a 3mm diameter and a 500µm thickness.

Accuracy

Measurements by the NPL in the UK (counterpart of NIST) have demonstrated that the accuracy of the 500µm pitch pattern was ±0.25µm and ±0.1µm for the 50µm and 2µm patterns. It goes without saying that these reported results from NPL are highly conservative. Our customers have also sent MRS-3's to NIST. The NIST data shows better accuracy than NPL reports.

Certification report

The certification is done following ISO guidelines. Each MRS-3 has a unique serial number engraved on the standard. Certification includes the serial number, certification date, operator, instrumentation used, actual pattern measurements and measure of accuracy. The recertification due date is also given.

MRS-3 is more radiation resistant. (It handles about 10x the electron beam current density and provides higher scanning electron microscopy imaging contrast, even at 500eV. Patterns have been added to help calibrate particle size counting systems and determine the spatial resolution in video and surface chemical imaging systems. Highest accuracy equipment used.
Measurements in the X-Y Plane can be certified to NIST and NPL standards. Z plane measurements are traceable to a NIST standard only.

NIST = National Institute of Standards and Technology, USA

NPL = National Physical Laboratories, UK