Nanofabrication and Semiconductor Devices Quiz

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.

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.