1. Digital thickness control to atomic level (no rate monitor needed, just set the number of atomic layers).
2. Perfect 3D conformality, 100% step coverage: uniform coatings on flat, inside porous and around particle samples.
3. Large area thickness uniformity.
4. Easy batch scalability (precursor sources are small and stacking of substrates is possible).
5. Pinhole free films, even over very large areas.
6. Excellent repeatability (wide process windows: ALD is not sensitive to temperature or precursor dose variations).
7. Low defect density.
8. Excellent adhesion due to chemical bonds at the first layer.
9. Digital control of sandwiches, heterostructures, nanolaminates, mixed oxides, graded index layers and doping.
10. Gentle deposition process for sensitive substrates, no plasma.
11. Low temperature deposition possible (RT-400C).
12. Atomically flat and smooth coating, copies shape of substrate perfectly.
13. Low stress because of molecular self assembly.
14. 100% film density guarantees ideal material properties (n, Ebd, k, etc).
15. Insensitive to dust (grows underneath dust!).
16. Oxides, nitrides, metals, semiconductors possible (Cambridge NanoTech provides standard recipes).
17. Amorphous or crystalline depending on substrate and temperature.
ALD is a self-limiting, sequential surface chemistry that deposits conformal thin-films of materials onto substrates of varying compositions. ALD is similar in chemistry to chemical vapor deposition (CVD), except that the ALD reaction breaks the CVD reaction into two half-reactions, keeping the precursor materials separate during the reaction. ALD film growth is self-limited and based on surface reactions, which makes achieving atomic scale deposition control possible. By keeping the precursors separate throughout the coating process, atomic layer control of film grown can be obtained as fine as ~ 0.1 angstroms per monolayer.
ALD has unique advantages over other thin film deposition techniques, as ALD grown films are conformal, pin-hole free, and chemically bonded to the substrate. With ALD it is possible to deposit coatings perfectly uniform in thickness inside deep trenches, porous media and around particles. The film thickness range is usually 1-500 nm. ALD can be used to deposit several types of thin films, including various ceramics, from conductors to insulators.
"Atomic Layer Deposition." Wikipedia, The Free Encyclopedia. 29 Nov 2007, 15:04 UTC. Wikimedia Foundation, Inc. 24 Jan 2008 <http://en.wikipedia.org/w/index.php?title=Atomic_Layer_Deposition&oldid=174606450>.