This work shows results of investigation concerning optimalisation of deposition and etching of carbon layers (NCD – Nano Crystalline Diamond and DLC – Diamond like Carbon). The layers were produced with capacitance coupled a.c. discharges with frequency (RF – radio frequency). During the experiment aiming to MISFET transistor (Metal – Insulator – Semiconductor Field Effect Transistor) with carbon layer, activities were taken to determine properties of plasma and the layers. The layers were etched in reactor and aluminium mask was used. The influence of plasma etching on the layer and mask has been determined.