Plasma-enhanced etching discharge

For the most part, plasma-enhanced etching and deposition are performed in four basic reactor types (Figure 7 2, 46). Each reactor has several basic components a vacuum chamber and pumping system to maintain reduced pressures, a power supply to create the discharge, and gas- or vaporhandling capabilities to meter and control the flow of reactants and products. 

Plasmas are used in three major microelectronics processes sputtering, plasma enhanced chemical vapor deposition (PECVD), and plasma etching. In each, the plasma is used as a source of ions and/or reactive neutrals and is sustained in a reactor so as to control the flux of neutrals and ions to a surface. The typical ranges of properties for a glow discharge used in microelectronic fabrication are as shown in Table I. 

There are many different methods for modifying polymer surfaces to improve their adhesion and wetting properties. They include chemical etching and oxidation, ion bombardment, plasma treatments, flame treatment, mechanical abrasion and corona-discharge treatments (1.2). Especially flame and corona treatments are widely used for the modification of polyolefin surfaces to enhance, for instance, their printabilify. Despite the widespread use of such processes in industry, the understanding of the fundamental processes which occur at the polymer surface is very limited. This is undoubtedly due to the shallow depth to which the polymer is modified, typically 5 nm or less. 

The structure dependency of the etching rate is enhanced in chemically reactive luminous gas, but the nature of dependence remains the same. Plasma-sensitive structures such as -O- in the backbone of a polymer- and oxygen-containing pendant group play a dominant role. It is important to note that LCVT, chemical etching of polymers by non-polymer-forming gas plasma, can be well described by the same discharge power parameter for LCVD, which is WjFM. 

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