Glow-discharge etching

Figure C2.18.3. Relationship between ion-assisted etching and directionality in plasma etching, (a) Demonstration of the synergy between ion bombardment and reactive species during ion-assisted etching, (b) Ions incident on an etched feature. This situation prevails in glow discharges when the feature dimensions are much less than the plasma sheath thickness. Reproduced from [35]...

B. Chapman, Glow Discharge Processes—Sputtering and Plasma Etching. Wiley, New York, 1980. 

Kinetics of Polymer Etching in an Oxygen Glow Discharge... 

A wide spectrum of heterogeneous processes can occur at solid surfaces exposed to a glow discharge (5,25,27). The primary processes of interest in plasma etching (and in plasma deposition) are summarized in Table II i20). These interactions result from the bombardment of surfaces by particles. Although vacuum UV photons and soft x-rays present in the plasma are sufficiently energetic to break chemical bonds, electron and particularly ion bombardment has been found to be the most effective method of promoting surface reactions (25). 

After removal of the native aluminum oxide layer, molecular chlorine (CI2) can etch pure, clean aluminum without a plasma (84,52), Indeed, CI2 may be the primary etchant species for aluminum in a glow discharge, perhaps due to a higher concentration of CI2 than chlorine atoms in the discharge (74). 

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