Feature Size Dependent Etching

Reactive Ion Etching (RIE), Fig. 9 RIE lag etched depth depends on feature size... 

The features on the photomask are transferred to the photoresist, and their size depends on the resolution of the photomask. The features are revealed after immersion in the developer solution. The photoresist can be used as a masking layer for further etching steps, in which material is removed, or in deposition steps, in which material is added. 

As design features are continually reduced to produce higher-density interconnects, tighter control of every step in the conductor formation process is required to achieve high yield. The maximum possible yield with an etching or plating process depends on the conductor dimensions such as the conductor pitch in terms of line and space, the conductor thickness, and the size and shape of the capture pads around plated through-holes (PTH) and vias. 

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