The act of applying a thin film to a surface is thin-film deposition – any technique for depositing a thin film of material onto a substrate or onto previously deposited layers. "Thin" is a relative term, but most deposition techniques control layer thickness within a few tens of nanometres. Molecular beam epitaxy, the Langmuir–Blodgett method, atomic layer deposition and molecular layer deposition allow a single layer of atoms or molecules to be deposited at a time.
It is useful in the manufacture of optics (for reflective, anti-reflective coatings or self-cleaning glass, for instance), electronics (layers of insulators, semiconductors, and conductors form integrated circuits), packaging (i.e., aluminium-coated PET film), and in contemporary art (see the work of Larry Bell). Similar processes are sometimes used where thickness is not important: for instance, the purification of copper by electroplating, and the deposition of silicon and enriched uranium by a CVD-like process after gas-phase processing.
Deposition techniques fall into two broad categories, depending on whether the process is primarily chemical or physical.
Chemical Vapor Deposition (1 pcs)
Chemical vapor deposition (CVD) is a vacuum deposition method used to produce high quality, and high-performance, solid materials. The process is often used in the semiconductor industry to produce thin films.
In typical CVD, the wafer (substrate) is exposed to one or more volatile precursors, which react and/or decompose on the substrate surface to produce the desired deposit. Frequently, volatile by-products are also produced, which are removed by gas flow through the reaction chamber.
Microfabrication processes widely use CVD to deposit materials in various forms, including: monocrystalline, polycrystalline, amorphous, and epitaxial. These materials include: silicon (dioxide, carbide, nitride, oxynitride), carbon (fiber, nanofibers, nanotubes, diamond and graphene), fluorocarbons, filaments, tungsten, titanium nitride and various high-k dielectrics.
Pulsed laser deposition (1 pcs)
Pulsed Laser Deposition (PLD) is a thin film deposition technique used to create thin films of various materials. In PLD, a high-energy pulsed laser beam is focused onto a target material in a vacuum chamber. The laser pulse ablates or vaporizes the target material, creating a plume of particles that then condense onto a substrate, forming a thin film with the same composition as the target. This method allows for precise control over film thickness and the deposition of complex materials, including oxides and compounds.
Sputtering (1 pcs)
Sputtering is a thin film deposition method used in materials science and semiconductor manufacturing. It involves bombarding a target material (often a solid metal or compound) with high-energy ions, typically through a low-pressure gas discharge or plasma. This energetic bombardment dislodges atoms from the target's surface, which then deposit onto a substrate, forming a thin film with precise control over thickness and composition.