Sputtering Wake Forest University（溅射维克森林大学）.pdfVIP

Sputtering Vacuum Evaporation Recap • Use high temperatures at high vacuum to evaporate (eject) atoms or molecules off a material surface. • Use ballistic flow to transport them to a substrate and deposit. • Film uniformity can be an issue. • Alloy evaporation is very complicated and in most cases, not possible. An Alternative Method • Instead of using heat to eject material from a source, we can Substrate bombard them with high speed particles. • The momentum transfer from the particles to the surface atoms can impart enough energy to allow the surface atoms to escape. Source • Once ejected, these atoms (or molecules) can travel to a substrate and deposit as a film. • There are several considerations here: – Creating, controlling and directing a high speed particle stream. – Interaction of these particles with the source surface and emission yields. – Deposition of the emitted atoms on the substrate and film quality. Some Terminology • Atomic particles can best be easily controlled by electromagnetic methods if they are charged. A weakly charged gas of particles that exhibit collective behavior is called a plasma. • The source material is called the target and the emitted atoms or molecules are said to be sputtered off. Sputtering • So in sputtering, the target material and the substrate is placed in a vacuum chamber. -V • A voltage is applied between them so that the target is the Target cathode and the substrate is (cathode) attached to the anode. Plasma • A plasma is created by