Nanotechnology: A Maker’s Course complete course is currently being offered by Duke University, North Carolina State University & The University of North Carolina at Chapel Hill through Coursera platform.
Week 1 - Main: Introduction and Essential Technologies for Nano
Q1. Nano-measurement tools typically involve bombarding a sample with particles such as:
- ball bearings
- electrons
- photons
- ions
- bacteria
- dust
- vacuum
Q2. What are challenges of nanoscale measurement compared to traditional measurement? (Select all that apply.)
- Can’t find a nanoruler at hardware stores
- The equipment is not readily available
- Humans can’t see at that scale with their naked eye
- Not every material can be characterized at the nanoscale
Q3. Which of the following are not typically conductive? Select all that apply
- Silver
- Polymers
- Gold
- Dielectrics/Ceramics
- Metals
- Biologicals
Q4. Particles in the open air do not cause defects in thin film deposition.
- True
- False
Q5. Which of the following are methods used to deposit thin films? (Select all that apply)
- Nano-imprint Lithography
- Screenprinting
- Chemical Vapor Deposition
- Vacuum Evaporation
- Painting
- Photolithography
- E-Beam Lithography
- Sputter Deposition
- Etching
Q6. When gowning before entering the cleanroom, you:
- start at the top (head) and work down to the bottom (feet)
- start at the bottom (feet) and work up to the top (head)
Q7. Typical molecules found in air include _____ (check all that apply)
- carbon dioxide
- silicon dioxide
- nitrogen
- oxygen
- silver
Q8. Match the vacuum pump categories to their general function:
a. Positive Displacement Pumps _____
b. Momentum Transfer Pumps _____
c. Entrapment Pumps _____
1. trap air molecules inside the pump, effectively removing the molecules from the chamber
2. bounce or deflect air molecules out of the chamber
3. push air out of the chamber
- a-3, b-1, c-2
- a-1, b-2, c-3
- a-2, b-1, c-3
- a-2, b-3, c-1
- a-3, b-2, c-1
- a-1, b-3, c-2
Q9. Which of the following are found in the electromagnetic spectrum? (Select all that apply)
- Time wave
- Seismic wave
- Beta ray
- Radio
- Alpha ray
- Microwaves
Q10. What is the best resolution of a microscope with a numerical aperture of 0.5 using energy with a wavelength of 2.8 nm?
- 3.36 nm
- 5.6 nm
- 3.36 pm
- 5.6 microns
Q11. As the velocity of an electron increases the wavelength of the electron will ________.
- stay the same
- decrease
- increase
Q12. What can occur when an electron beam interacts with a sample? (Select all that apply)
- Electrons in the beam will gain mass as they hit the sample.
- Electrons in the beam will multiply as they hit the sample.
- The beam will create a vacuum.
- Electrons in the beam will knock electrons out of the sample.
- The beam will pass through the sample.
Q13. As the velocity of an electron changes from 1.6 x 108
m/s to 2.8 x 108
m/s the wavelength of the electron will ________.
stay the same
decrease
increase
Week 2 - Main : Nano Measurement and Characterization Tools: Scanning Electron Microscopy and Energy-Dispersive X-ray Spectroscopy
Q1. What is an advantage of using an environmental scanning electron microscope?
- Samples can be coated with less expensive metals to prevent charging.
- The resolution is typically higher than traditional SEM.
- Wet samples can be imaged in their natural state without being dried.
- Images can be collected much more rapidly.
Q2. If you are interested in collecting SEM images that highlight surface features of your sample, which detector would be more appropriate?
- Backscatter
- Secondary electron
Q3. Which of the following uses electrons to generate images?
- Light microscope
- Electron microscope
Q4. In SEM, which of the following materials is often used to coat nonconductive samples?
- Polymer
- Glass
- Carbon
- Acetone
Q5. In SEM, after loading the sample and pumping the chamber to a low pressure, what is the first thing that should be done before collecting an image?
- Move the sample out of the chamber.
- Tighten the set screws on the sample stage.
- Focus the electron beam on the sample.
- Coat the sample with a conductive layer.
Q6. Which of the following information can be obtained through Energy Dispersive X-Ray Spectroscopy? (Select all that apply)
- Mass
- Weight
- Elemental Composition
- Feature Size
- Chemical Composition
Q7. What makes each element have a unique fingerprint in Energy Dispersive Spectroscopy (EDS)?
- Atomic number of elements in the sample
- Electron energy states in the element
- Mass of the atoms in the sample
- Amount of atoms in the sample
Q8. If an insulating sample is coated with a very small layer of gold to produce better images, gold will not be detected in the Energy Dispersive X-Ray Microscopy (EDS) experiment.
- True
- False
Week 3 - Main : Nano Measurement and Characterization Tools: Transmission Electron Microscopy
Q1. What is the major difference between SEM and TEM?
- Only TEM produces images of the sample
- Insulating samples can only be imaged in SEMs
- TEM uses smaller electrons than SEMs
- The electrons must pass through the sample in TEM
Q2. What are challenges of TEM? (Select all that apply)
- Aberrations related to lenses limit spatial resolution
- Requires ultrathin samples
- Sample image is a projection from 3D to 2D
- Environment around the microscope must be precisely controlled
Q3. In TEM, small changes in the environment, like vibrations from someone talking or a slight increase in temperature can affect imaging dramatically.
- True
- False
Q4. Using TEM, a researcher is able to image individual atoms.
- True
- False
Q5. What does a plasma cleaner do to a TEM sample?
- Washes the sample with detergent
- Coats the sample with a thin, clean layer of material
- Coats the sample with a conductive layer
- Removes debris and other particulates
Q6. Plunge freezing is a sample preparation method used for Cryo-TEM in which the sample is slowly cooled down.
- True. The sample should be frozen gradually.
- False. The sample should be cooled very rapidly.
Q7. Which is not a type of ice that can form at atmospheric pressure?
- vitreous
- hexagonal
- cubic
- octagonal
Q8. When performing biological sample prep for the TEM, which is not required safety equipment?
- lab coat
- safety glasses
- gloves
- ear plugs
Q9. The inside of the TEM is always under vacuum?
- True
- False
Week 4 - Main : Nano Measurement and Characterization Tools: X-ray and Optical Characterization
Q1. What happens when x-rays hit a very dense part of the sample?
- They are stopped or absorbed by it
- They are reflected backward
- They pass through it
Q2. In order to stabilize a sample for scanning it may be necessary to wrap it up before placing it on the stage. What would be the best material to package a sample in before running the MicroCT?
- Fill in container with cement to hold specimen firmly
- Light plastic bottle filled with cotton
- Dense plastic tube filled with tinfoil
- Stabilize with metal wire
Q3. Which of the following can be done with the final z-stack of images produced by the MicroCT?
- It can be used to create 3D models that can be 3D printed.
- It can be measured directly using free software like ImageJ
- It can be animated to show off the internal or external structure of the specimen
- All of the above
Q4. Using XPS you can obtain information about the chemistry of your sample’s ______.
- a. bulk
- b. surface
- c. both a and b
- d. none of the above
Q5. Electrons in a neutral/uncharged atom typically have _____ binding energies than electrons in an atom with a 4+ oxidation state.
- lower
- higher
Q6. Why are tweezers used during XPS sample preparation? (Select the best answer)
- To enable better sample conductivity
- To prevent sample contamination
- To protect the user as the sample is heated
- To help thin the sample prior to analysis
Q7. On the x-axis of an XPS plot is binding energy. What does this axis represent?
- The amount of energy required to remove electrons from an atom
- The amount of energy necessary to break bonds in a molecule
- The amount of energy needed to bind two atoms together
- The X-ray energy produced by the X-ray gun
Q8. What can XPS tell us about a sample? (Select all that apply)
- The oxidation state of elements on the surface
- The surface topography
- The elements present in the bulk
- The percentage of specific elements on the surface
Q9. The way light scatters or reflects depends on the size of an object.
- True
- False
Q10. Why might taking a scattering spectrum of nanoparticles take longer than taking a spectra of a bulk material?
- Nanoparticles scatter more light that is unfocused and cannot be collected
- Nanoparticles are small and scatter less light
- Bulk materials scatter light more quickly
- Bulk materials scatter light at higher energy
Q11. As the nanoparticle size changes, the peaks in the scattering spectra shift to different wavelengths.
- True
- False
Week 5 - Main : Nanofabrication: Vacuum Pumps and Thin Film Vacuum Deposition
Q1. The turbo-molecular pump, or simply turbopump, is an example of what type of pump:
- a high vacuum pump
- a low vacuum pump
- a rough pump
Q2. Why do the cooling fins in a cryopump have a large surface area?
- Larger surface area provides more room for trapping air molecules, which improves pumping.
- Large surface area reduces the noise of the pump.
- Large surface area reduces vibrations.
Q3. A cryopump will eventually become saturated with air molecules and pumping efficiency will degrade.
- True. A saturated cryopump must undergo a process called regeneration to remove trapped air molecules and regain its original pumping efficiency.
- False. A cryopump can pump indefinitely and will never become saturated with air molecules.
Q4. Why is a vacuum chamber typically kept under vacuum when not in use?
- It saves electricity
- It keeps the chamber cleaner than leaving it filled with air
- It is quieter
Q5. Why do we often use a tungsten boat to hold gold during thermal evaporation?
- Tungsten is more electrically conductive than gold
- Tungsten has a lower melting temperature than gold
- Tungsten is denser than gold
- Tungsten has a higher melting temperature than gold
Q6. It is necessary to rough pump a vacuum chamber before pumping with a high vacuum pump.
- True
- False
Q7. E-Beam evaporation heats the source material using:
- Fire
- a high voltage electron beam
- a laser
Q8. In sputter deposition, the function of the plasma is to:
- cool the target
- produce light to improve visibility in the vacuum chamber
- generate energetic atoms that remove target material
- heat the target
Q9. During sputter deposition, increasing or decreasing sputter power too quickly can cause the target material to crack.
- True
- False
Week 6 - Main : Nanofabrication: Vapor Deposition
Q1. Atomic Layer Deposition (ALD) and Chemical Vapor Deposition (CVD) are both thin film deposition techniques
- True
- False
Q2. Which of the following are properties that can be added to a substrate with a thin film?
- Electrical Properties
- Barrier Properties
- Physical Properties
- All of the above
Q3. Which of the following statements are true about the differences between Atomic Layer Deposition & Chemical Vapor Deposition.? (Check all that apply)
- CVD does not require a substrate.
- CVD processes can grow thicker films at faster rates.
- ALD can be done at lower temperatures than CVD.
- ALD films are more conformal.
- ALD takes less time than CVD.
- ALD does not involve chemical interactions.
Q4. What types of substrates can be treated with Atomic Layer Deposition?
- Glass Slides
- Silicon Wafers
- Biological Samples
- Polymers
- All of the above
Q5. What types of substrates can be treated with Chemical Layer Deposition?
- Glass Slides
- Silicon Wafers
- Biological Samples
- Polymers
- All of the above
Q6. Which of the following are properties that can be added to a substrate with a thin film?
- Electrical Properties
- Barrier Properties
- Physical Properties
- All of the above
Q7. In Chemical Vapor Deposition, like any vacuum deposition process, why are the chambers kept under vacuum even when not in use? (Please select the best answer)
- To keep contaminants from accumulating inside the chamber
- To save energy
- To prevent unauthorized use of equipment
- To comply with federal law
Q8. Solid, liquid and gas are three states of matter. PECVD utilizes a fourth state of matter called:
- vapor
- plasma
- steam
Q9. The plasma in the PECVD chamber is formed using:
- a laser
- RF (radio frequency) electrical power
- a heated wire filament
Q10. In a PECVD system, the necessary activation energy that drives the chemical processes comes from the plasma. In non-plasma CVD processes, the activation energy is provided by:
- ultrasonic agitation
- high pressure
- high temperature / heat
Week 7 - Main : Nanofabrication: Patterning and Self-Assembly
Q1. When performing photolithography, the photoresist is intended to be a permanent or a temporary layer?
- Temporary
- Permanent
Q2. Why is there special colored lighting in the photolithography room?
- To save electricity
- To protect the light-sensitive photoresist
- It improves your vision
Q3. During photolithography, the process of illuminating the wafer with UV light is termed:
- spin coating
- exposure
- development
- baking
Q4. In photolithography, the development step comes before or after exposure?
- Before
- After
Q5. When discussing EBL, the term “EBL resist” is best described as:
- a light sensitive polymer
- a pressure sensitive polymer
- an electron sensitive polymer
Q6. When performing photolithography, we use chemical resists that are sensitive to light. When performing electron beam lithography, we use chemical resists that are sensitive to what?
- Temperature
- Electrons
- Pressure
Q7. Why must the EBL chamber be under vacuum?
- Because air would interfere with the electron beam
- Because air would degrade the polymer film on the wafer
- To reduce the noise generated by the EBL instrument
Q8. Electron beam lithography can pattern features so small that they cannot be adequately imaged using an optical microscope
- True
- False
Q9. Ion beams can be used for all of the following, except:
- Ion Implantation (Doping)
- Welding
- Patterning – Sputtering, Etching, & Milling
- Imaging
Q10. To generate a beam of positively charged Gallium ions, a ______ charged electrical field is needed to accelerate positively-charged Gallium ions. (Select one)
- positively
- neutrally
- negatively
Q11. In hot embossing, why is it important to wear gloves when handling the master mold? (Select one)
- The mold is too hot to touch when loading into the embosser
- Fingerprints and particles from hands can transfer from the mold to the substrate
- The mold is made of hazardous material
Q12. In hot embossing, a master mold is used to imprint a pattern onto a softer substrate material. The master mold is typically much more expensive than the materials it is used to emboss on.
- True
- False
Q13. There are four main steps in typical hot embossing processes. Select choice where the steps are listed in correct order.
- Demolding, Heating, Embossing, Cooling
- Cooling, Heating, Demolding, Embossing
- Embossing, Heating, Demolding, Cooling
- Heating, Embossing, Cooling, Demolding
Q14. In hot embossing, why is it important to wear gloves when handling the master mold? (Select one)
- The mold is made of hazardous material
- Fingerprints and particles from hands can transfer from the mold to the substrate
- The mold is too hot to touch when loading into the embosser
Q15. Self-assembly can only be achieved through intra-molecular forces, such as ionic and covalent bonds.
- True
- False
Week 8 - Main : Nanofabrication: Etching
Q1. In general, etching ________ material ____ a substrate. (Select the best answer)
- removes, from
- deposits, on
- protects, in
- stamps, on
Q2. What is the etch rate?
- The rate at which material is removed
- The time it takes to complete the etching process
- The rate of reaction between two materials on the substrate
- The rate at which material is deposited onto the mask
Q3. When etch selectivity is high it means:
- the etch rates of all materials in the system are equal
- the etch rates of the mask and underlying substrate are high compared to the etch rate(s) of undesired material(s)
- the etch rates of all materials in the system are high
- the etch rates of the mask and underlying substrate are low compared to the etch rate(s) of undesired material(s)
Q4. In which of the following scenarios would the etch selectivity be low? (Select all that apply)
- The etch rates of the mask and underlying substrate are low compared to the etch rate(s) of undesired material(s)
- The etch rates of all materials in the system are high
- The etch rates of all materials in the system are equal
- The etch rates of the mask and underlying substrate are high compared to the etch rate(s) of undesired material(s)
- The etch rates of all materials in the system are low
Q5. During wet etching, etching is due to
- Ion beam patterning
- a chemical reaction between the reactant/etchant and materials in the system
- a chemical reaction between the mask material and the substrate
- physical removal of material
Q6. Which of the following describes the majority of wet etching processes?
- Isotropic and selective
- Anisotropic and non-selective
- Isotropic and non-selective
- Anisotropic and selective
Q7. Which of the following are advantages of the wet etching process? (Select all that apply)
- The reactions are typically anisotropic
- The process is simple
- The chemical consumption is low
- It is easy to batch process multiple substrates/wafers
- It is easy to finely control the etch process
- The reactions are selective
Q8. Which of the following are disadvantages of the wet etching process? (Select all that apply)
- The reactions are typically isotropic
- This question refers to the following learning objective: Learners will be able to discuss the advantages and disadvantages of using chemical wet etching for an etching process.
- One of the main disadvantages of wet etching is that the reactions in most cases are isotropic. This makes etching small geometries difficult. It also requires large amounts of chemicals which can be costly to purchase and dispose of. Further, fine process control is difficult. This can make reproducibility hard.
- The process is complex
- It is difficult to batch process multiple substrates/wafers
- The chemical consumption is high
- The reactions are not selective
- It is difficult to finely control the etch process
Q9. Which of the following personal protective equipment should be worn during a standard wet etching process? (Select all that apply)
- Self-contained breathing apparatus
- Face shield
- Chemical apron
- Helmet
- Chemically resistant gloves
- Ear plugs
- Steel-toed boots
Q10. To perform the wet etch, wafers are ____________. (Select the best answer)
- placed in a vacuum chamber with reactive gases
- placed in a spin-rinse dryer and rinsed with etchant
- submerged in a bath of chemical etchant
- sprayed with chemical etchant in a fume hood
Q11. After etching, why is it important to do characterization of the wafer?
- To continue etching in places that were not etched
- To build new structures on the substrate
- To confirm and evaluate the etching process
- To clean the wafe
Q12. What can cause the etching event in dry etching?
- Chemical process
- Physical process
- All of the above
Q13. To obtain anisotropic and highly selective conditions in dry etching, ________ (Select the best answer)
- the plasma etching is followed by thin film deposition.
- chemical and physical processes can be combined.
- the plasma etching is followed by wet etching.
- the wafers are submerged in liquid nitrogen.
Q14. Which of the following are advantages of the dry etching process? (Select all that apply)
- Process can be finely controlled
- Simple equipment
- Selective and anisotropic etches possible
- Easy to etch multiple wafers
- Chemical consumption is low
- Inexpensive
- Ability to make intricate features
Q15. Which of the following are disadvantages of the dry etching process? (Select all that apply)
- Process is difficult to control
- Chemical consumption is high
- Small geometries are difficult
- Batch processing difficult
- Requires complex equipment
- Isotropic reactions
- Expensive
Q16. Which of the following parameters can be controlled by the user through the etching software in the “recipe”? (Select all that apply)
- Reaction temperature
- Etching pattern
- Chamber volume
- Power
- Mask material
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