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Energy Materials

Electron Cyclotrone Resonance

Electron Cyclotron Resonance. Foto : https://snf.stanford.edu

To study on energy materials, it is necessary to learn a system tools so-called ECR (Electron Cyclotrone Resonance). The system is used as a plasma sources for any kind of material processing applications. The main components of ECR include the microwave generator which generates the frequency of 2.45 GHz, an electromagnetic generator to provide the magnetic field and other supporting associated gases. There are a lot of applications of ECR, such as ethcing, deposition or coating of materials.

What are the advantages of this ECR compared to the other plasma system ?

  1. ECR Operates at low neutral gas pressure (0.2 – 10 mtorr). For Diode and RIE (Reactive Ion Etcher) : 50 – 1000 mtorr. Low pressure reduces ion collisionality in the substrate sheats. It is necessary for anisotropic etching of a smaller and increasingly high aspect ratio features in the modern IC.
  2. ECR operates in the relatively high density range ni = 1011 – 1012 cm-3. For RIE ni = 1010 cm-3. Higher ion density means higher ion-flux-driven processing rate. High ion flux is advantages for non-passivating chemistries
  3. ECR has low plasma potential (15 – 30 eV) without substrate biasing. Low plasma potential can reduce physical damage to the substrate from high energy ion bombardment, as well as reducing unwanted sputtering of materials from remainder of the tool surface.
  4. ECR has an independent control of ion energy and ion flux. Ion energy is controlled by RF or DC biasing of substrate holder. While control of ion and neutral flux is achieved by varying microwave power and neutral gas pressure.
  5. ECR Source are wave-driven which has the unique feature of plasma formation remote from any physical surface.
    1. Inductively couple sources : Power deposited within a skin depth 0.5 cm/(ne x 10-12 cm-3)1/2.
    2. Capasitively couple sources : Power deposited within a skin depth 0.01 cm/(ne x 10-12 cm-3)1/2.

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