Introduction: The optical nature of a charged particle beam 17
[58]. The sample consists of chromosomes of the fruit fly Drosophila
melanogaster. Four different chemical species are shown, giving
detailed spatially resolved chemical information about the chromosomes. These images were obtained using the SIMS tool at the
University of Chicago, which uses a focused primary ion beam consisting of gallium ions from a liquid metal ion source. This method
can be used to analyze an enormous variety of samples at the microscopic level.
Alternatively, an electron or ion beam can physically or chemically
alter the target material locally. The writing substrate is coated
with a thin film of organic material. Bombarding the film with a
focused electron or ion beam renders the film either more soluble
(positive-tone process) or less soluble (negative-tone process) in
the developer. The organic film is thus patterned, and forms a binary mask for subsequent process steps. Creating fine patterns on
a substrate is commonly referred to as lithography. An enormous
variety of useful devices can be fabricated with high areal density
and very small feature sizes.
Two patterns written by electron beam lithography are shown in
Figure 1.10. The top pattern shows the negative-tone resist which
is left behind after the development step. It is an electronic circuit
pattern with 30 nm features, courtesy of Vistec Lithography. The
bottom pattern shows pillars of silicon which are 0.5 µm in diameter and 1.5 µm high. They were written using a Vistec SB352 HR
electron beam system, courtesy of IMS CHIPS, Stuttgart, Germany.
A focused electron beam is the smallest, finest practical writing
pencil known. An arbitrary pattern can be created and stored
using standardized computer-aided design software, and subsequently transmitted to the electron beam writer for one or more
exposures. This flexibility, together with the high resolution, make
electron beam lithography the method of choice for creating patterns on the nanometer scale of dimensions in low volume.
[58]. The sample consists of chromosomes of the fruit fly Drosophila
melanogaster. Four different chemical species are shown, giving
detailed spatially resolved chemical information about the chromosomes. These images were obtained using the SIMS tool at the
University of Chicago, which uses a focused primary ion beam consisting of gallium ions from a liquid metal ion source. This method
can be used to analyze an enormous variety of samples at the microscopic level.
Alternatively, an electron or ion beam can physically or chemically
alter the target material locally. The writing substrate is coated
with a thin film of organic material. Bombarding the film with a
focused electron or ion beam renders the film either more soluble
(positive-tone process) or less soluble (negative-tone process) in
the developer. The organic film is thus patterned, and forms a binary mask for subsequent process steps. Creating fine patterns on
a substrate is commonly referred to as lithography. An enormous
variety of useful devices can be fabricated with high areal density
and very small feature sizes.
Two patterns written by electron beam lithography are shown in
Figure 1.10. The top pattern shows the negative-tone resist which
is left behind after the development step. It is an electronic circuit
pattern with 30 nm features, courtesy of Vistec Lithography. The
bottom pattern shows pillars of silicon which are 0.5 µm in diameter and 1.5 µm high. They were written using a Vistec SB352 HR
electron beam system, courtesy of IMS CHIPS, Stuttgart, Germany.
A focused electron beam is the smallest, finest practical writing
pencil known. An arbitrary pattern can be created and stored
using standardized computer-aided design software, and subsequently transmitted to the electron beam writer for one or more
exposures. This flexibility, together with the high resolution, make
electron beam lithography the method of choice for creating patterns on the nanometer scale of dimensions in low volume.