Several deposition techniques are commonly used in nanotechnology, each with its own advantages and limitations. The main techniques include:
Physical Vapor Deposition (PVD) PVD involves the physical transfer of material from a source to the substrate. Common methods include:
- Evaporation: Material is heated to a high temperature until it vaporizes, then it condenses onto the substrate. - Sputtering: Ions are used to eject material from a target, which then deposits onto the substrate.
Chemical Vapor Deposition (CVD) In CVD, gaseous precursors react chemically on the substrate surface to form a solid material. Variations include:
- Thermal CVD: Uses heat to drive the chemical reaction. - Plasma-Enhanced CVD (PECVD): Uses plasma to enhance the reaction at lower temperatures.
Molecular Beam Epitaxy (MBE) MBE is a highly controlled technique where beams of atoms or molecules are directed at the substrate in a high-vacuum environment. This method is particularly useful for creating very high-quality crystalline films.
Atomic Layer Deposition (ALD) ALD is a type of CVD that allows for the deposition of materials one atomic layer at a time. This technique is extremely precise and is used to create ultra-thin films with excellent uniformity and conformality.
