Atoms in Flight
Magnetron sputtering ejects atoms from a target surface with energies of 5–30 eV — far above the 0.025 eV thermal energy at room temperature. These energetic atoms traverse the vacuum, potentially colliding with background argon gas, and condense on the substrate to form a thin film. The competition between ballistic and thermalized transport determines film microstructure, density, and properties.
Deposition Rate Physics
The deposition rate depends on the sputter yield (atoms ejected per ion), the ion flux (controlled by discharge power), and the geometric factor (inverse square of target-substrate distance). Increasing power increases the ion current proportionally, while the sputter yield is fixed by the ion energy and target material. This simulation calculates the rate from these fundamental parameters.
Pressure and Transport
Argon pressure controls the mean free path of sputtered atoms. At 0.5 Pa, the mean free path is a few centimeters — comparable to typical target-substrate distances. Below this pressure, atoms arrive ballistically with high energy, producing dense films. Above it, multiple collisions thermalize the atoms, reducing their energy and changing the film growth mode from dense to columnar.
Film Growth Visualization
The canvas shows sputtered atoms leaving the target, traversing the gas phase (with collisions shown at higher pressures), and building up a film on the substrate. The film thickness grows in real time, and the color intensity represents film density. Adjusting pressure and distance lets you visually explore the transition between ballistic and thermalized deposition regimes.