Thermal Evaporation for thin film deposition

In PVD, the two terms describe the same process. Thermal evaporation is the standard name. Thermal vapour deposition and vacuum thermal evaporation are alternative names for heating a source material in vacuum until it vaporises and condenses on a substrate. They should not be confused with chemical vapour deposition (CVD), which relies on chemical reactions.

Both are PVD techniques in which a source material vaporises in vacuum and condenses on a substrate. The difference is the heat source. Thermal evaporation heats the source resistively, by passing current through a boat or filament. Electron beam evaporation uses a focused electron beam, which reaches higher temperatures and suits materials with higher melting points.

Resistive thermal evaporation is typically used for metals with relatively low melting points, such as aluminium, gold, silver and copper, and for some compounds. Materials with higher melting points, such as refractory metals, generally require electron beam evaporation. The suitable range depends on the source configuration and system.

Thermally evaporated material travels predominantly in straight lines, so relatively little is deposited on the sidewalls of a patterned resist layer. After deposition, the resist is removed and the unwanted material lifts off with it, leaving the desired metal pattern. This defines fine features without a separate etching step.