Planar passivated PN-junctions - produced by using silicon dioxide blocks as diffusion mask

摘要

Planar passivated pn-junctions are produced by diffusion of impurities in a masked semi-conductor in the following stages: 1) the p-type Si substrate is coated with Si3N4 2). Windows are produced in the latter by photolacquer techniques. 3) SiO2 layers are produced by heating in moist O2. 4) The Si3N4 layer is etched away selectively. 5) Impurities are diffused into the area between the SiO2 blocks to produce an n-type Si layer. This avoids the disadvantage of the mesa technique of exposing the pn-junction after etching so that it is not passivated where exposed to atmosphere. The junction produced is perfectly plain, without any curvature at the fringe.