YPS Schottky TFE sources

YPS Schottky Thermal Field Emission Sources

high quality replacement Schottky TFE emitters for Electron Beam Columns

YPS-174 Schottky emitters   |   YPS-184 Schottky emitters   |   FEI SFEG exchange modules

Introduction 

YPS Schottky TFE source consists of a single crystal (100) tungsten wire with a very sharp tip including a zirconium reservoir around the the tungsten tip wire

The YPS Schottky TFE source consists of a single crystal (100) tungsten wire with a very sharp tip including a zirconium reservoir around the the tungsten tip wire

The YPS Schottky type thermal field emission sources are an excellent choice to replace used TFE sources in electron beam systems, including FESEM, SFEG-SEM, FETEM, EPMA, Auger and CD-SEM systems. The YPS sources are drop-in replacements for existing FEI and Denka style sources also known as 184 and 174 type suppressors. The YPS Schottky TFE source consists of a single crystal (100) tungsten wire with a very sharp tip including a zirconium reservoir around the the tungsten tip wire. The tip is mounted on a hairpin filament which is used to mainatain the tip ate a temperature of around 1800K. This assembly is mounted in a cylindrical suppressor electrode with an aperture through which the sharp tip protudes. Electrons are emitted from the tip due to both thermal excitation and the electrical field at the tip. The YPS Schottky TFE source tip typically has a radius of 0.3µm and protrudes around 250µm to ensure high brigthness of the source. 

More info in: Frequeuntly Asked Questions (FAQ) about Thermal Field Emission (TFE)sources

 

 

YPS Schottky TFE sources

YPS supplies standard designs, refurbishes legacy designs and designs and supplies custom TFE sources. These products are aimed to customers who are comfortable with changing field emission sources and know how to change, load and align the TFE sources in a clean environment. Operating vacuum for Schottky TFE sources is typically better than 1x10-9mbar. This is higher than the operating vacuum for tungsten or Lab6 sources, but less stringent than for cold field emission sources. The YPS Schottky thermal field emission sources exhibit excellent stability over a wide range of acceleration voltages  and long operating times. Electron Source Performance Table

 

 

YPS-174 Standard Schottky TFE emitter module 

The YPS-174 Schottky TFE module is a drop-in replacement for the most common standard Schottky thermal field emitter module

The YPS-174 Schottky TFE module is a drop-in replacement for the most common standard Schottky thermal field emitter module.

The YPS-174 Schottky TFE module is a drop-in replacement for the most common standard Schottky thermal field emitter module. It is equivalent in dimensions with both Denka and FEI standard Schottky field emission cathodes. The supprossor aperture has a diameter of 400µm. The emitter typically protrudes 250µm from the suppressor electrode. The YPS-174 is compatible with thermal field emission sources used on E-beam systems from AmRay, Hitachi,  JEOL, Zeiss, LEO, Philips, PHI and Riber.Dimensions of the YPS-174 TFE module

 

YPS-184 Schottky TFE emitter module

The YPS-184 Schottky TFE emitter module is a drop-in replacement alternative for the FEI Schottky TFE emitter module.

The YPS-184 Schottky TFE emitter module
is a drop-in replacement alternative for the
FEI Schottky TFE emitter module.

 
 
YPS exchange Schottky TFE module assemblies for FEI FEG and Sirion SFEG 

YPS exchange Schottky TFE module assemblies for FEI FEG and Sirion SFEG

The YPS FEI FEG and SFEG Schottky TFE module is
a complete exchange module assembly replacement
for the FEI TFE module.

The YPS FEI FEG and SFEG Schottky TFE module is a complete exchange module assembly replacement for the FEI TFE module used in the FEI  XL-30, Sirion, Inspect and Nova NanoSEM systems. The FEG  or SFEG emitter module is supplied within the gun assembly and is factory pre-aligned.  It is avialable for the FEI systems units the FEG TFE module assembly and for the SFEG Sirion module assembly. This is available as a complete gun module exchange only. The complete TFE gun assembly will be shipped under inert  nitrogen gas with a protective container mounted on the gun assembly flange. The type of TFE source can be identifed through the silver label on the gun assembly flange.

 

 

YPS TFE Emitter module selection table

Instrument

Product #

YPS TFE Emitter Module

 

 

 

yps 174 source with suppressor YPS 184 source with suppressor

 

AmRay

AU-14-AM4702

YPS-174-A

 

 

CamScan

AU-14-CS4801

 

YPS-184-C *Exchange only

 

FEI/Philips 174

AU-14-FP4703

YPS-174-F *Exchange only

 

 

FEI **

AU-14-FE4803

 

YPS-184-F *Exchange only

 

FEI FEG  gun assembly

AU-14-FX4920

 

 

FEG gun assembly exchange only

FEI SFEG Sirion gun assembly

AU-14-FX4930

 

 

SFEG gun assembly exchange only

Hitachi TFE SEM ***

AU-14-HI4704

YPS-174-H

 

 

Hitachi TFE CD-SEM

AU-14-HC4705

YPS-174-HC

 

 

ISI / ABT / Topcon

AU-14-IT4706

YPS-174-IT

 

 

JEOL **

AU-14-JL4708

YPS-174-J

 

 

LEO (Gemini)

AU-14-ZE4710

YPS-174-Z

 

 

PHI

AU-14-PH4711

YPS-174-P

 

 

Riber

AU-14-RI4712

YPS-174-R

 

 

Tescan

AU-14-TE4809

 

YPS-184-T

 

Zeiss (Gemini)

AU-14-ZE4710

YPS-174-Z

 

 

Custom Emitters

Please contact us for more information

*For exchange only, the original suppressor parts are re-furbished, cleaned and furnished with a new TFE tip

** The 184 type TFE emitter module can also be found on other electron beam systems. Contact us for replacement.

*** YPS-174 Schottky TFE emitter modules for Hitachi FESEMS, Hitachi CD-SEMs and JEOL FESEMs are only compatible with Hitachi and JEOL FESEMs which use a thermal field emitter. Cold field emitters are not compatible with the YPS-174 or YPS-184 modules.


Each YPS Schottky TFE emitter module includes an extensive and unique data sheet with

  • Emitter radius value in µm
  • Emitter performance @ 1800K
  • Temperature versus current graph
  • Distance of tip protrudes from the suppressor in µm
  • SEM image from the TFE emitter tip

Example of YPS Schottky TFE emitter module data sheet


 

Addition information

 YPS-174 TFE source dimensions
YPS-174 TFE source dimensions YPS-184 TFE source dimensions

 

Electron Source Performance Table

The electron source performance table is provided to give additional information into the performance and requirements for different type of electron emitters. Tungsten cathodes are still used in many SEMs. Improved results can be obtained with LaB6 cathodes. The highest resolution, highest brightness and best low kV performance can be achieved with either Schottky or cold Field Emission Sources.

Emitter Type

Thermionic

Thermionic

Schottky TFE

Cold FE

Tip image comparison

Thermionic Wolframe Cathode

Thermionic LaB6 Cathode

chottky TFE ZrO/W (100) Cathode

Cold Fe W (310) cathode

Cathode Material

W

LaB6

ZrO/W (100)

W (310)

Operating Temp (K)

2700

1800

1800

300

Cathode Radius (nm)

60,000

10,000

<1000

<100

Effective Source Radius (µm)

25

10

0.015

0.0025

Emission Current Density (A/cm2)

3

30

5300

17,000

Total Emission Current (µA)

200

80

200

5

Brightness (A/cm2.sr.kV)

1x104

1x105

1x107

2x107

Maximum Probe Current (nA)

1000

1000

10

0.2

Energy Spread @ Cathode (ev)

0.59

0.4

0.31

0.26

Energy Spread @ Source Exit (eV)

1.5 – 2.5

1.3 – 2.5

0.35 – 0.7

0.3 – 0.7

Beam Noise (%)

1

1

1

5 – 10

Emission Current Drift (%/h)

0.1

0.2

<0.5

5

Operating Vacuum (hPa/mbar)

<10-5

<10-6

<10-8

<10-10

Typical Cathode Life (h)

100

>1000

>5000

>2000

Cathode Regeneration (h)

None

None

None

6-12

Sensitivity to External Influences

Minimal

Low

Low

High

Stability

Standard

High

Very high

Low

X-ray analysis

EDS / WDS

EDS / WDS

EDS / WDS

EDS

 

Frequeuntly Asked Questions (FAQ) about Thermal Field Emission (TFE)sources

Q. Are TFE sources less reliable than thermionic sources (e.g. Tungsten or LaB6)?
A. No – TFE sources can be very reliable, working over many months continuously. All YPS tips are guaranteed for one year of normal operation

Q. What are the advantages of Schottky thermal field emission compared to cold field emitters e.g. W(310) or W(111)?
A. The major advantages are better beam current stability, higher beam currents, less stringent vacuum requirements and the fact that there is no need for periodic emitter flashing to restore the emission curent.

Q. What are the vacuum requirements for operation of a Schottky thermal field emission source?
A. Normally, 10-9mbar or better at the source region.

Q. What brightness can be achieved with Schottky TFE sources compared to thermionic sources?
A. Schottky TFE emitters have a brightness of about 10xE8 Acm-2sr-1 against 10xE5 Acm-2sr-1 for thermionic sources.

Q. Do Schottky emitters need replacing very frequently?
A. Not really. The lifetime of a Schottky emitter is determined by the life of the Zr reservoir in the tip structure. This is normally about 8000 hours.

Q. Are there special steps to be taken in turning on a Schottky source?
A. Check the vacuum level be 10-9mbar at the emitter. Care is needed to avoid thermal shock to the emitter and to avoid electrical breakdown transients as the extraction voltage is applied. Further, the operating temperature should not exceed 1850K; see data sheet for current/temperature graph.

Q. How do I operate the YPS Schottky TFE emitter?
A. In the same way as other TFE sources. The YPS source is supplied with a Schottky emitter data sheet, unique to each emitter.

Q. How stable is the beam current of a Schottky field emitter compared to a cold field emitter?
A. Beam current stability for the thermal Schottky is <0.5%/h compared to 5-30% drift and random jumps for a cold field emitter.

Q. Can any thermionic source be replaced by a Schottky TFE source?
A. Yes, this is the YPS C>More column upgrade. There will be the need for additional differential pumping at the emitter region and a dedicated HT power supply unit for the TFE source. Contact us for details.

Q. Can a cold field emitter be replaced by a YPS Schottky TFE source?
A. Not as a drop-in replacement. Only when the complete electron gun and HT power supply are replaced. Contact us for details.

 

Ordering Information for

  1. YPS Schottky TFE emitter modules with type 174 suppressor for Amray, Philips, Hitachi, ISI/ABT/Topcon, LEO, PHI, Riber, Tescan and Zeiss columns.
  2. YPS exchange module assembly for FEI FEG and SFEG Sirion gun assemblies used on XL-30, Sirion, Inspect and Nova NanoSEM systems.

15 Item(s)

15 Item(s)