Skip to content

Atomic Layer Etching (ALE)

Atomic Layer Etching (ALE) alternates between two steps: a chemical modification that only affects the top atomic layers of the material, and an etching step that removes these modified areas. This allows for precise control, enabling the removal of individual atomic layers.

Precise control over the ion energy distribution (IED) in ALE can help:

  1. Reducing Damage: By controlling the energy of ions, potential harm to the substrate during the ALE process can be minimized. For example, in the etching of silicon nitride, a prolonged argon desorption process can lead to significant silicon damage due to the build-up of incident ions. This damage can be significantly reduced with careful control of ion energy.
  2. Maintaining Directionality: Precise control of IED is crucial for achieving directionality, which is necessary for most pattern transfers to preserve critical dimensions.
  3. Ensuring Self-Limitation: ALE is a self-limiting process that involves the removal of atoms from the surface. This can be triggered by various energy sources, such as chemistry, temperature, and kinetic energy from collisions. Precise control of ion energy is essential to maintain the self-limiting nature of the process.
  4. Enhancing Etching Outcomes: Precise control of ion energy can lead to a more accurate determination of sputter thresholds, which are valuable for designing new ALE chemistries. For instance, researchers have been able to achieve narrow energy distributions and use mono-energetic ions to etch silicon dioxide thin films by physical sputtering using tailored bias voltage waveforms in a commercial remote plasma reactor.

In conclusion, the precise control of IED is a key factor in optimizing the ALE process, reducing potential damage, maintaining directionality, and enhancing overall etching outcomes. It plays a vital role in achieving atomic-precision control in semiconductor manufacturing processes. EHT Semi’s pulse generators for wafer bias can help manufacturers improve their ALE process through precision waveform and IED control.