This document discusses various electron microscopy techniques used to analyze materials at the nanoscale, including transmission electron microscopy (TEM), scanning electron microscopy (SEM), and scanning transmission electron microscopy (STEM). TEM works by transmitting electrons through a thin sample, allowing analysis of sample structure and crystallography. SEM scans the sample surface with a focused electron beam to produce high-resolution images based on emitted secondary electrons and backscattered electrons. STEM combines TEM and SEM to enable both imaging and elemental analysis using energy-dispersive X-ray spectroscopy (EDS) or electron energy loss spectroscopy (EELS).

1. 1
TFE4180 Semiconductor Manufacturing Technology, TEM and SEM
SEM and TEM
Chapter 7.2 : Semiconductor Science by Tudor E. Jenkins
Saroj Kumar Patra,
Department of Electronics and Telecommunication,
Norwegian University of Science and Technology ( NTNU )

2. 2
Contents
 Why use electrons?
• De-Broglie Hypothesis
• Electromagnetic lenses and Numerical Aperture
 Transmission Electron Microscopy (TEM)
• Structure
• Use Mode
• Practical complications
 Scanning Electron Microscopy (SEM)
• Structure
• Use Mode
 Scanning Transmission Electron Microscopy (STEM)
 Energy Dispersive X-ray Spectroscopy (EDS)
 Electron Energy Loss Spectroscopy (EELS)
TFE4180 Semiconductor Manufacturing Technology, TEM and SEM

3. 3
Contents
 Why use electrons?
• De-Broglie Hypothesis
• Electromagnetic lenses and Numerical Aperture
 Transmission Electron Microscopy (TEM)
• Structure
• Use Mode
• Practical complications
 Scanning Electron Microscopy (SEM)
• Structure
• Use Mode
 Scanning Transmission Electron Microscopy (STEM)
 Energy Dispersive X-ray Spectroscopy (EDS)
 Electron Energy Loss Spectroscopy (EELS)
TFE4180 Semiconductor Manufacturing Technology, TEM and SEM

4. 4
Why use electrons?
TFE4180 Semiconductor Manufacturing Technology, TEM and SEM
• Resolution of the microscope depends
on wavelength .
• Optical microscopy is limited by
wavelength to visible light.
• Maximum resolution of optical
microscopes ~ 200nm.

5. 5
Why use electrons?
TFE4180 Semiconductor Manufacturing Technology, TEM and SEM
• Material-wave : Wave particle
duality.
• Short wavelength

6. 6
Why use electrons?
TFE4180 Semiconductor Manufacturing Technology, TEM and SEM
For V= 100 keV:
Non-relativistic consideration:

7. 7
Electromagnetic Lenses
TFE4180 Semiconductor Manufacturing Technology, TEM and SEM
• Lenses focus poorly even at
moderate angels.
• This causes NAEM ~ 0.01
• This is far worse than optical
microscopy where NAOP ~ 1.0

8. 8
Contents
 Why use electrons?
• De-Broglie Hypothesis
• Electromagnetic lenses and Numerical Aperture
 Transmission Electron Microscopy (TEM)
• Structure
• Use Mode
• Practical complications
 Scanning Electron Microscopy (SEM)
• Structure
• Use Mode
 Scanning Transmission Electron Microscopy (STEM)
 Energy Dispersive X-ray Spectroscopy (EDS)
 Electron Energy Loss Spectroscopy (EELS)
TFE4180 Semiconductor Manufacturing Technology, TEM and SEM

9. 9
Transmission Electron Microscopy
(TEM)
TFE4180 Semiconductor Manufacturing Technology, TEM and SEM
• Send electrons through a thin (~100 nm) sample.
• Get information about the sample based on what
has happened to the electrons when they come out
the other side of the sample.

10. 10
TEM column
with components
TFE4180 Semiconductor Manufacturing Technology, TEM and SEM

11. 11
TEM
Schematic
Diagram
TFE4180 Semiconductor Manufacturing Technology, TEM and SEM

Energy-loss
spectrometer
Aperture
Sample stage
Detector
CCD video camera
Fluorescent screen
CRT
Condenser lens
Anode
Lenses
Electron gun
X-ray detector
Objective
aperture
Displayed
sample image
Liquid N2
Dewar
Figure 7.36

12. 12
Bright Field (BF)
TFE4180 Semiconductor Manufacturing Technology, TEM and SEM
• Separating out the electrons that are
scattered. i.e., those who have gone
straight through the sample.
• Dark and Bright fields for areas with
high and low degree of electron
absorption respectively (Mass-thickness
contrast).
• Dark and Bright fields for areas with
high and low degree of electron
absorption respectively (Diffraction
contrast).

13. 13
Bright Field (BF)
TFE4180 Semiconductor Manufacturing Technology, TEM and SEM
• Separating out the electrons that are
scattered. i.e., those who have gone
straight through the sample.
• Dark and Bright fields for areas with
high and low degree of electron
absorption respectively (Mass-thickness
contrast).
• Dark and Bright fields for areas with
high and low degree of electron
absorption respectively (Diffraction
contrast).

14. 14
Dark Field (DF)
TFE4180 Semiconductor Manufacturing Technology, TEM and SEM
• Separating out the electrons that have
been scattered in a particular direction.
• Light fields for areas in which electrons
have been scattered in the direction
chosen (Diffraction contrast).
• Greater chance of spreading to areas
with high mass and thickness ( Mass-
thickness contrast).

15. 15
Dark Field (DF)
TFE4180 Semiconductor Manufacturing Technology, TEM and SEM
• Separating out the electrons that have
been scattered in a particular direction.
• Light fields for areas in which electrons
have been scattered in the direction
chosen (Diffraction contrast).
• Greater chance of spreading to areas
with high mass and thickness ( Mass-
thickness contrast).

16. 16
HRTEM ( Lattice Images )
TFE4180 Semiconductor Manufacturing Technology, TEM and SEM
• Why ? : To take the “image” of the crystal planes in the
material.
• How ? : Setting out both the non-diffracted beam and
one of the diffracted rays with lens aperture and let
them interfere in the image plane.
Lets go back a little…..

17. 17
HRTEM ( Lattice Images )
TFE4180 Semiconductor Manufacturing Technology, TEM and SEM
Test
EM Lens
Diffraction plane
Objective aperture
Image plane
Selected area
aperture
More lenses
Screen / Camera

18. 18
HRTEM ( Lattice Images )
TFE4180 Semiconductor Manufacturing Technology, TEM and SEM
Test
EM Lens
Diffraction plane
Objective aperture
Image plane
Selected area
aperture
More lenses
Screen / Camera
Objective aperture
( in Diffraction plane)

19. 19
HRTEM ( Lattice Images )
TFE4180 Semiconductor Manufacturing Technology, TEM and SEM
Test
EM Lens
Diffraction plane
Objective aperture
Image plane
Selected area
aperture
More lenses
Screen / Camera
Objective aperture
( in Diffraction plane)

20. 20
HRTEM ( Lattice Images )
TFE4180 Semiconductor Manufacturing Technology, TEM and SEM
Test
EM Lens
Diffraction plane
Objective aperture
Image plane
Selected area
aperture
More lenses
Screen / Camera
Objective aperture
( in Diffraction plane)

21. 21
HRTEM ( Lattice Images )
TFE4180 Semiconductor Manufacturing Technology, TEM and SEM
Test
EM Lens
Diffraction plane
Objective aperture
Image plane
Selected area
aperture
More lenses
Screen / Camera
Two images of the sample are
brought together
Interference
Phase contrast image of the crystal plane

22. 22
HRTEM ( Lattice Images )
TFE4180 Semiconductor Manufacturing Technology, TEM and SEM
Two images of the sample are
brought together
Interference
Phase contrast image of the crystal plane

23. 23
Electron Diffraction
TFE4180 Semiconductor Manufacturing Technology, TEM and SEM
• Why ? : To study the crystal structure of the material.
• How ? : Adjusting last lens to diffraction plane (instead
of image plane) which is focused on the screen /
camera

24. 24
Electron Diffraction
TFE4180 Semiconductor Manufacturing Technology, TEM and SEM

25. 25
Electron Diffraction
TFE4180 Semiconductor Manufacturing Technology, TEM and SEM
Test
EM Lens
Diffraction plane
Objective aperture
Image plane
Selected area
aperture
More lenses
Screen / Camera

26. 26
Electron Diffraction
TFE4180 Semiconductor Manufacturing Technology, TEM and SEM
Test
EM Lens
Diffraction plane
Objective aperture
Image plane
Selected area
aperture
More lenses
Screen / Camera
Selected Area Aperture
( in Image plane)

27. 27
Electron Diffraction
TFE4180 Semiconductor Manufacturing Technology, TEM and SEM
Test
EM Lens
Diffraction plane
Objective aperture
Image plane
Selected area
aperture
More lenses
Screen / Camera
Much information about the
material

28. 28
TEM Practical Complications
TFE4180 Semiconductor Manufacturing Technology, TEM and SEM
• Must have thin samples (e.g., ~ 100 nm)
 Difficult
 Time consuming
 Can change the sample
• Damage to the sample
• Narrow view

29. 29
Contents
 Why use electrons?
• De-Broglie Hypothesis
• Electromagnetic lenses and Numerical Aperture
 Transmission Electron Microscopy (TEM)
• Structure
• Use Mode
• Practical complications
 Scanning Electron Microscopy (SEM)
• Structure
• Use Mode
 Scanning Transmission Electron Microscopy (STEM)
 Energy Dispersive X-ray Spectroscopy (EDS)
 Electron Energy Loss Spectroscopy (EELS)
TFE4180 Semiconductor Manufacturing Technology, TEM and SEM

30. 30
Scanning Electron Microscope
(SEM)
TFE4180 Semiconductor Manufacturing Technology, TEM and SEM

31. 31
Why use SEM?
TFE4180 Semiconductor Manufacturing Technology, TEM and SEM
• Visual : High Resolution Image of the sample
( but TEM has even better resolution)
• Versatile : Not too picky on the samples.
 Bad idea with live test
 Samples can be inserted very quickly.
 With modern sample holders, more than one sample can be
loaded at the same time.

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SEM Structure
TFE4180 Semiconductor Manufacturing Technology, TEM and SEM

33. 33
Simple Schematic of SEM
TFE4180 Semiconductor Manufacturing Technology, TEM and SEM
X-scan signal
Specimen
Scanning
magnets
Stage
Detector
Y-scan signal
X-scan
Y-scan
Z-axis signal CRT
Condenser
lens
Anode
Electron extractor
Filament (electron
emitter)
Electron beam
Figure 7.20

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Electron Beam System
TFE4180 Semiconductor Manufacturing Technology, TEM and SEM

35. 35
Electron Beam System
TFE4180 Semiconductor Manufacturing Technology, TEM and SEM
WD:
• Important Parameters : Condenser aperture and working distance (WD)
• What about Resolution and Depth of Field !

36. 36
Electron Beam System
TFE4180 Semiconductor Manufacturing Technology, TEM and SEM
Aperture Size:

37. 37
Electron Beam System
TFE4180 Semiconductor Manufacturing Technology, TEM and SEM
Interaction volume
(Typically ~ 100 nm to 5μm

38. 38
Secondary Electrons
TFE4180 Semiconductor Manufacturing Technology, TEM and SEM
- Contrast : Topography
- Secondary – not the same electrons
that were injected.
- Coming from the second upper
layer of the interaction volume.

39. 39
SEM Image
TFE4180 Semiconductor Manufacturing Technology, TEM and SEM

40. 40
Back Scattered Electrons
TFE4180 Semiconductor Manufacturing Technology, TEM and SEM
Contrast : Element
Cause : Coulomb Force
∗
∗ ∗
Resolution : Lower than SE
(Due to large interaction volume)

41. 41
SEM Image using BSE
TFE4180 Semiconductor Manufacturing Technology, TEM and SEM

42. 42
Contents
 Why use electrons?
• De-Broglie Hypothesis
• Electromagnetic lenses and Numerical Aperture
 Transmission Electron Microscopy (TEM)
• Structure
• Use Mode
• Practical complications
 Scanning Electron Microscopy (SEM)
• Structure
• Use Mode
 Scanning Transmission Electron Microscopy (STEM)
 Energy Dispersive X-ray Spectroscopy (EDS)
 Electron Energy Loss Spectroscopy (EELS)
TFE4180 Semiconductor Manufacturing Technology, TEM and SEM

43. 43
Scanning Transmission Electron
Microscopy (STEM)
TFE4180 Semiconductor Manufacturing Technology, TEM and SEM
http://www.ipme.ru/e-journals/RAMS/no_1100/browning/Brow.pdf
• Combining the two techniques
:TEM and SEM.
• Provides opportunity for
element analysis
 EDS
 EELS
• Annular Dark Field Imaging
(not in syllabus)

44. 44
Contents
 Why use electrons?
• De-Broglie Hypothesis
• Electromagnetic lenses and Numerical Aperture
 Transmission Electron Microscopy (TEM)
• Structure
• Use Mode
• Practical complications
 Scanning Electron Microscopy (SEM)
• Structure
• Use Mode
 Scanning Transmission Electron Microscopy (STEM)
 Energy Dispersive X-ray Spectroscopy (EDS)
 Electron Energy Loss Spectroscopy (EELS)
TFE4180 Semiconductor Manufacturing Technology, TEM and SEM

45. 45
Energy Dispersive X-ray
Spectroscopy (EDS)
TFE4180 Semiconductor Manufacturing Technology, TEM and SEM
• X-rays emitted from atoms
that have been excited by
the electron radiation.
• The wavelengths of X-rays
are characteristic of atomic
number.
• It works best on heavier
elements.

46. 46
Energy Dispersive X-ray
Spectroscopy (EDS)
TFE4180 Semiconductor Manufacturing Technology, TEM and SEM
• X-rays emitted from atoms
that have been excited by
the electron radiation.
• The wavelengths of X-rays
are characteristic of atomic
number.
• It works best on heavier
elements.

47. 47
Contents
 Why use electrons?
• De-Broglie Hypothesis
• Electromagnetic lenses and Numerical Aperture
 Transmission Electron Microscopy (TEM)
• Structure
• Use Mode
• Practical complications
 Scanning Electron Microscopy (SEM)
• Structure
• Use Mode
 Scanning Transmission Electron Microscopy (STEM)
 Energy Dispersive X-ray Spectroscopy (EDS)
 Electron Energy Loss Spectroscopy (EELS)
TFE4180 Semiconductor Manufacturing Technology, TEM and SEM

48. 48
Electron Energy Loss Spectroscopy
(EELS)
TFE4180 Semiconductor Manufacturing Technology, TEM and SEM
Plot: Relative intensity against Energy loss.
NB most electrons lose no energy ( elastic
collision)
• Some electrons lose energy due to
inelastic shock.
• The shape of the curve to the right
is characteristic for each element.
• It works best for low mass.

49. 49
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TFE4180 Semiconductor Manufacturing Technology, TEM and SEM