Plasma-Enhanced Atomic Layer Deposition (PE-ALD) is an advanced variant of the ALD process that replaces thermal energy with highly reactive plasma species (radicals, ions, and electrons) to drive surface reactions. While thermal ALD relies on heating the substrate—often to temperatures between 200°C and 400°C—PE-ALD can achieve high-quality, dense films at much lower temperatures, sometimes even at room temperature.

In a standard thermal cycle, the second precursor (e.g., water or ammonia) requires thermal energy to react with the first precursor on the surface. In PE-ALD, a plasma discharge (typically O2, N2, or H2 plasma) generates reactive radicals that provide the necessary chemical energy.

The diagram of the working mechanism of the plasma-enhanced ALD process is shown below:

References:

Hyungjun Kim, et al., Characteristics and applications of plasma enhanced-atomic layer deposition, Thin Solid Films, 2011, 519, 6639-6644

D. R. Boris, et al., The role of plasma in plasma-enhanced atomic layer deposition of crystalline films, J. Vac. Sci. Technol. A, 2020, 38, 040801.