场发射源

The YPS Schottky type field emission (FE) sources can be used in many brands of focused electron beam systems including SEM, TEM, Auger and CD-SEM systems. These high quality FE sources are an excellent and cost effective drop-in alternative for FEI and Denka style FE sources. The YPS FE source is a thermal field emitter (TFE) cathode featuring a layer of zirconium oxide on a <100> oriented single crystal tungsten wire with a very sharp tip. The tip is mounted on a hairpin filament that is used to maintain the tip at a temperature of around 1800K.


The tip just penetrates the aperture hole in a cylindrical suppressor electrode mounted around the assembly. Electrons are emitted from the tip due to both thermal excitation and an electrical field at the tip due the potential difference between it and an extractor electrode. The YPS Schottky tip radius is typically 0.3um to ensure high brightness of the source.
Currently there are three types of FE sources available: the YPS-174, the YPS-184 and the YPS-M20 Mini Module. This product is aimed to customers who are comfortable with changing field emission sources and know how to change, load and align the TFE cathodes in a clean environment. It is also an excellent product for developers building custom designed electron beam columns using TFE sources. The operating vacuum for TFE sources is typically better than 1x10-9 mbar. This is higher than the operating vacuum for tungsten or LaB6 sources, but less stringent than for cold field emission sources.


YPS-174 Standard Schottky FE Module
The YPS-174 is the most common standard Schottky field emitter module which is equivalent in dimensions to both FEI and Denka standard Schottky field emission cathodes. The suppressor aperture has a diameter of 400µm. The emitter protrudes 250µm from the suppressor electrode. The YPS-174 is compatible with thermal field emissison sources used on systems from Amray, Hitachi, JEOL, ZEISS/LEO, FEI (pre 2002), PHI and Riber.
YPS-184 Schottky FE Module
The YPS-184 Schottky Module is a drop-in alternative for the FEI SSEM unit. The suppressor aperture has a diameter of 500µm and the emitter protrudes 250µm from the suppressor electrode. The YPS-184 module is also compatible with Tescan FESEMs.
YPS-M20 Mini Module TFE Source
The YPS-M20 Mini module TFE source is a complete pre-aligned assembly with a smaller style suppressor, ceramic insulator and extractor. The YPS-M20 Mini Module is a high grade alternative FE source for the Applied Materials/OPAL CD-SEMs.