Nanofabrication and Semiconductor Devices Quiz
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Nanofabrication

The process of creating structures at the nanometer scale.

Top-down Nanofabrication

A top-down approach to nanofabrication involves starting with a larger material and gradually reducing it down to the nanoscale.

Bottom-up Nanofabrication

A bottom-up approach to nanofabrication involves assembling structures from individual atoms or molecules.

Moore's Law

A prediction by Gordon Moore that the number of transistors on a microchip would double every two years.

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Photolithography

A pattern transfer technique that uses light to create a pattern on a photosensitive material called photoresist.

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Deposition

A process in which a material is deposited onto a substrate, often in thin layers.

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Plasma Deposition

A deposition technique that uses a plasma to create a thin film on a substrate.

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Sputtering

A deposition technique that uses a high-energy beam of ions or neutrals to remove material from a target and deposit it onto a substrate.

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Pulsed Laser Deposition (PLD)

A deposition technique that uses a focused laser beam to ablate material from a target and deposit it onto a substrate.

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Chemical Vapour Deposition (CVD)

A deposition technique that uses chemical reactions to create a thin film on a substrate.

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Atomic Layer Deposition (ALD)

A deposition technique that creates a thin film one atomic layer at a time.

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Etching

The process of removing unwanted material from a substrate.

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Wet Etching

A type of etching that uses a liquid chemical to remove material.

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Dry Etching

A type of etching that uses a plasma to remove material.

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Etch Rate

The rate at which a material is removed during etching.

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Etch Selectivity

The ability of an etch to remove one material preferentially over another.

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Etch Uniformity

The ability of an etch to produce a uniform pattern across a substrate.

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Physical-Chemical Etching

A type of etching that uses both physical and chemical processes to remove material.

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Sidewall Passivation

A layer that is deposited on the sidewalls of a feature during etching to prevent the material from being etched away.

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Scanning Probe Microscopy (SPM)

A technique that uses a sharp tip to scan a surface and create a topographical map of the surface.

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Scanning Tunneling Microscopy (STM)

A type of SPM that uses a sharp metallic tip to scan a surface and measure the tunneling current between the tip and the surface.

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Decay Constant (κ)

A measure of the decay rate of an electron wavefunction as it tunnels through a barrier.

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Scanning Tunneling Spectroscopy (STS)

A technique that uses a sharp tip to scan a surface and measure the tunneling current between the tip and the surface over a range of bias voltages.

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Atomic Force Microscopy (AFM)

A type of SPM that uses a sharp tip to scan a surface and measure the force between the tip and the surface.

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Mechanical Pump

A device that uses mechanical means to remove gas molecules from a vacuum chamber.

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Non-Mechanical Pump

A device that uses chemical or physical means to trap gas molecules inside a vacuum chamber.

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Rotary Vane Pump

A type of mechanical pump that uses a rotating vane to compress gas and pump it out of a vacuum chamber.

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Roots Pump

A type of mechanical pump that uses two rotating lobes to compress gas and pump it out of a vacuum chamber.

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Turbomolecular Pump

A type of mechanical pump that uses a rotating blade to impart momentum to gas molecules, forcing them out of a vacuum chamber.

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Diffusion Pump

A type of mechanical pump that uses a stream of high-velocity vapor molecules to impart momentum to gas molecules, forcing them out of a vacuum chamber.

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Sorption Pump

A type of non-mechanical pump that uses a porous material to adsorb gas molecules from a vacuum chamber.

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Getter-ion Pump

A type of non-mechanical pump that uses a getter material to chemically react with and trap gas molecules from a vacuum chamber.

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Cryopump

A type of non-mechanical pump that uses a cold surface to adsorb gas molecules from a vacuum chamber.

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Pressure Measurement

The measurement of pressure in a vacuum chamber.

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Capacitance Manometer

A type of absolute pressure gauge that uses a diaphragm to measure pressure.

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Pirani Gauge

A type of pressure gauge that measures the thermal conductivity of a gas.

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Ionization Gauge

A type of pressure gauge that measures the ionization current produced by a gas discharge.

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Study Notes

Nanofabrication Part I

  • Nanofabrication is a process used to create structures at the nanoscale
  • The course covers the different techniques of nanofabrication.
  • Intel's 22nm 3D Ivy Bridge processor used new Tri-Gate "3D" transistors, which are less power hungry.

SEM Cross Section Silicon Device

  • SEM is an acronym for Scanning Electron Microscope.
  • The image shows a cross-section of a silicon device.
  • The image's magnification, voltage, and current measurement details are given.

Intel unveils 22nm 3D Ivy Bridge processor

  • Intel unveiled a new generation microprocessor technology in 2011 called Ivy Bridge.
  • The new processor utilized a 22nm manufacturing process.
  • The processor used Tri-Gate "3D" transistors, which were denser than the previous 32nm system and consumed less power.
  • A comparison image shows the traditional planar chip design and the new Tri- Gate design.

Moore's Law

  • Intel co-founder Gordon Moore predicted in 1965 that the number of transistors on a chip would double approximately every two years.
  • This observation, now known as Moore's Law, has driven significant technological advancements.
  • Moore's Law, enabled by Intel, the world largest silicon supplier, has fueled the worldwide technology revolution.

Evolution of Transistor

  • The implementation of high-k and metal materials marks a significant change in transistor technology.
  • The Intel announcement followed an announcement of similar breakthrough by IBM.
  • There are diagrams showing silicon and high-k based transistors.

Lithography

  • Photolithography is the process of making patterns on materials
  • Transferring patterns from a template (often called a "mask" in some designs)
  • Common photoresist approach involves using a photoresist (PR) that is exposed and developed, then the patterns are "printed" on the substrate using the PR layer as a mask.
  • PR can be removed (stripped) after the process.

Pattern Transfer

  • Integrated circuits (ICs) and micro-fabricated MEMS (microelectromechanical systems) devices are formed by defining patterns in several layers.
  • The process involves photographic transfer of the desired pattern to a photosensitive film, followed by chemical or physical processes.
  • Removal or addition of material is employed in this process (for creating the pattern).
  • The process includes photo, chemical, and physical processes.

Main Steps in Lithography

  • The steps to create patterns include applying photoresist, exposing, and etching away material.
  • The techniques are widely used in almost all microelectronic and MEMS processes.

Photoresist

  • Photoresist is a liquid film that can be spread onto a substrate.
  • Typically consists of a resin, sensitizer, and photoactive compound dissolved in a solvent.
  • Exposed areas dissolve in a solvent for subsequent development.

Top-Down Processing Techniques

  • Subtractive etching/etch-back: photoresist is applied, followed by etching unwanted materials.
  • Lift-off: patterned layers are deposited on top of photoresist, then unwanted material is lifted off when the resist is removed.

Subtractive and Additive Creation of Nanostructures

  • Subtractive etching is a dominant technique in microtechnology, transferring to nanotechnology with reduced thickness.
  • Nanofabrication requires high precision positioning of masks and the substrate with high resolution.
  • The amount of material and the rate of reaction is drastically reduced compared to microfabrication.

Nanostructure Generation by Lift-Off Processes

  • Lift-off is a method to fabricate small structures with high precision, independent of the properties of the patterned layer.
  • The quality of the photomask and the ability to deposit material into the openings of the photomask determine the edge quality of the final product.

Novel Lithographic Processes

  • E-beam lithography
  • Ion-beam lithography
  • X-ray lithography

Energy of Light Source

  • UV, Deep UV, and X-Ray light sources are used, with different energies and wavelengths.

Electron Beam Lithography

  • This technique involves directly writing patterns on wafers.
  • Diffraction limits the resolution in optical lithography.
  • Low throughput and high cost limit its use primarily to photomask production.

Implantation

  • Essential for modern IC manufacturing.
  • Doping or modifying semiconductor wafers involving steering ions into a substrate.
  • Ions can be accelerated or decelerated using electric fields.
  • Commonly used implanted species include arsenic, phosphorus, boron, boron difluoride, indium, antimony, germanium, silicon, nitrogen, hydrogen, and helium.

Molecular Beam Epitaxy (MBE)

  • MBE is a technique for depositing atomically perfect layers through evaporation at low rates in ultra-high vacuum.
  • It involves controlled crystal growth with a crystallographic relationship between the film and the substrate.
  • Homoepitaxy involves the same material for film and substrate, while heteroepitaxy utilizes different materials.

Surface interactions during MBE growth

  • Similar surface processes like adsorption, desorption, migration, and incorporation into film occur during MBE.
  • MBE can be used as a doping method with the advantage of preserving the lattice.
  • The method is expensive, and the concentration is limited.

Assessment topics and date

  • The assessment will be a test covering Plasma Physics, Surface Physics and SPM, and Nanofabrication.

Nanofabrication Part II

  • This part expands on the topics initially presented.

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Test your knowledge on nanofabrication techniques and semiconductor technology. This quiz covers topics including Intel's 22nm 3D Ivy Bridge processor and scanning electron microscopy of silicon devices. Challenge yourself with questions about industry developments and theoretical predictions like Moore's Law.

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