Piotr Szyszka

Lateral MEMS-Type Field Emission Electron Source

This paper describes a microelectromechanical-system-type field emission electron source fabricated as a planar silicon structure bonded with a glass substrate. It consists of a carbon nanotube cathode, beam formation electrodes, and silicon glass vacuum housing, all made in a uniform technological process. The current-voltage characteristics obtained inside a reference vacuum chamber for the two-, three-, and four-electrode configurations have been presented. The possibility of generation of a focused electron beam as well as gas ionization has been investigated. In addition, the lateral electron source has been integrated on the chip with a miniature ion-sorption vacuum pump and hermetically sealed. The use of the micropump significantly improved the stability of field emission current.

MEMS ion-sorption high vacuum pump

In the article a miniature MEMS-type ion-sorption vacuum pump has been presented. The influence of electric and magnetic field, as well as horizontal and vertical dimensions of the micropump and type of material used for electrodes on the pump properties has been investigated. It has been found that the micropump works efficiently as long as the magnetic field is higher than 0.3 T, and pumping cell is larger than 1x1x1 mm3. The pump allows generating vacuum at the level of 10-7-10-9 hPa in 100 mm3 volume.

MEMS ion source for mass spectrometer integrated on a chip

The paper describes silicon-glass MEMS electron impact ion source developed for miniature mass spectrometer (MS) integrated on a chip. The device consists of the field emission electron source with an electrophoretically deposited carbon nanotube cathode and ion beam formation electrodes. Ion source structure has been fabricated using MEMS technology. A complete manufacturing process of the test structures has been successfully elaborated and implemented.

Technology and parameters of thin membrane-anode for MEMS transmission electron microscope

A concept of a miniaturized microelectromechanical system based transmission electron microscope is presented. This device consists of two parts: part 1—electron optics column with a high vacuum micropump and part 2—sample chamber with a detector. These two parts are separated with a common electrode, called the anode. The anode consists of a very thin membrane (membrane-anode) that encloses the electron optics microsystem. It is used to let the electron beam pass to the sample and it must endure the pressure difference between its both parts. In this paper, the authors describe the fabrication process of the membrane-anode. It is made of Si3N4 layer deposited on an oxidized silicon substrate and is fabricated in five steps: photolithography, plasma etching, wet anisotropic etching, oxide stripping, and removing the Si3N4 and SiO2 layers. The membranes were characterized, and their preliminary performance parameters are presented, i.e., the endurance and the electron transmission.

Miniature mass spectrometer integrated on a chip

Mass spectrometry is one of the most powerful techniques that allows qualitative and quantitative characterization of chemical compounds. However, bulky high vacuum system required for analysis process limits application to professional laboratories. These restrictions can be overcome by replacing them with miniature high vacuum MEMS (Micro-Electro-Mechanical System). Our group, as the first in the world, has developed solutions that allow to propose the concept of fully miniaturized MEMS mass spectrometer. Multilayer silicon-glass elements: sample injection system, ion source, ion beam optics, mass separator, detector, and high vacuum micropump are integrated on a single, vacuum-sealed chip.

Influence of a magnetic field on trajectories of electrons in MEMS transmission electron microscope

In this paper we demonstrate how the magnetic field influences the trajectory of an electron beam in a miniature transmission electron microscope integrated with an ion-sorption micropump utilizing strong permanent magnets. Simulations of the electron trajectories (COMSOL software) and experimental results (spots on ITO screen) are compared. It is discussed how to eliminate the negative effect of the magnetic field but also how to change its distribution to improve properties of the field emission electron source.

Lateral MEMS-type field-emission electron source

The paper describes a MEMS-type field emission electron source fabricated as a planar silicon structure bonded to a glass substrate. The source consists of a carbon nanotube cathode, beam formation electrodes and vacuum housing; all made in uniform technological process. Complete fabrication process of the test structures has been successfully elaborated and implemented. Emission properties obtained for the 2-, 3- and 4-electrode configurations have been reported. Possibility of generation of a focused electron beam, as well as gas ionization have been investigated.