Electron beam lithography uses a focused beam of electrons to directly write nanoscale patterns onto a resist-coated surface. It allows for very high resolution patterning down to a few nanometers in size. The process involves coating a surface with an electron-sensitive resist, using a focused electron beam to expose patterns in the resist according to design data, and then developing the resist to selectively remove the exposed or unexposed areas. Key advantages of electron beam lithography include its lack of diffraction limit on resolution and ability to create specialized device structures. However, it also has disadvantages like long write times and high system costs.

1. Topic:-
ELECTRON BEAM
LITHOGRAPHY
Prepared by :-
ANJALI VANPARIYA
SAGAR PANELIYA
VISHWA BHAVSAR
Subject:-
Nanostructured Material for Energy Devices

2. Lithography
 Lithography is also often referred to as photoengraving, and is the process of
transferring a pattern into a reactive polymer film, termed as resist,
Nanostructures Fabricated by Physical Techniques which will subsequently
be used to replicate that pattern into an underlying thin film or substrate.
 Many techniques of lithography have been developed in the last half a century
with various lens systems and exposure radiation sources including photons,
X-rays, electrons, ions and neutral atoms.

3. Why Electron beam lithography
High speed for complex patterns
Point by point exposure
Not Diffraction - limited
E-beam

4. Electron beam lithography
A finely focused beam of electrons can be deflected accurately
and precisely over a surface.
When the surface is coated with a radiation sensitive
polymeric material, the electron beam can be used to write
patterns of very high resolution.
Electron beams can be focused to a few nanometers in
diameter and rapidly deflected either electromagnetically or
electrostatically.
Resolution of electron beam lithography is, however, limited by
forward scattering of the electrons in the resist layer and back
scattering from the underlying substrate.

5. Steps involved in the EBL process

6.  Exposure of the resist by the forward and backscattered electrons depends on
the beam energy, film thickness and substrate atomic number
When an electron beam enters a polymer film or any solid material, it loses
energy via elastic and inelastic collisions known collectively as electron
scattering.
Elastic collisions result only in a change of direction of the electrons, whereas
inelastic collisions lead to energy loss. These scattering processes lead to a
broadening of the beam
Beam energy increases, the energy loss per unit path length and scattering
cross-sections decreases
 Proper exposure requires that the electron range in the polymer film be
greater than the film thickness in order to ensure exposure of the resist at the
interface.

7. Electron beam systems can be conveniently considered in two broad
categories:
1. Scanning beam systems have four typical subsystems:
(i) electron source (gun)
(ii) electron column (beam forming system),
(iii) mechanical stage and
(iv) control computer which is used to control the various
machine subsystems and transfer pattern data to the beam
deflection systems.
2. focused electron beams which expose the wafer in serial
fashion, and those projecting an entire pattern simultaneously
onto a wafer.

8. Electron sources applicable to electron beam lithography are the same as
those used in conventional electron microscopes. These sources can be
divided into 2 groups:
1. Thermionic emission: Thermionic guns rely on the emission of
electrons from a material that is heated above a critical temperature
beyond which electrons are emitted from the surface.
 These sources are prepared from materials such as tungsten,
thoriated
tungsten, or lanthanum hexaboride.
2.Field emission: sources use a highelectric field surrounding a very
sharp point of tungsten.

9. Advantages:
 The Resolution is not limited by diffraction
 Can write smaller features
 Used to develop specialized device
 No need of physical mask
 Lower deflection densities
 Larger depth of focus due to continuous focussing
Disadvantages:
 Inefficient process for industrial processing
 Long time to pattern entire wafer
 High system cost
 System complexity due to requirement of vacuum

10. Application
1. Fabrication of masks
2. opto-electronic devices