Anodic Etch for Junction Delineation
Original Publication Date: 1980-Apr-01
Included in the Prior Art Database: 2005-Feb-13
An anodic etch method is described which brings out exceptionally sharp electrochemical junctions, that may be physically very close to electrical junctions at the corresponding voltages. It is believed that the method works by making the anodically biased n-layer silicon of the device insoluble in fluoride electrolyte, while allowing electrochemical (including galvano-chemical) dissolution of the differently doped areas. It has been found that the electrochemical junction between n-epi and other p-type areas are consistently delineated to the required sharpness. According to the method, the bevelled section of a device wafer with Pt-Si in contact windows or covered with a continuous platinum film is anodically biased by making an electrical contact with the p-substrate and platinum film, if used.