Self‐Replication of Deeply Buried Doped Silicon Structures, which Remotely Control the Etching Process: A New Method for Forming a Silicon Pattern from the Bottom Up

Abstract A typical microstructuring process utilizes photolithographic masks to create arbitrary patterns on silicon substrates in a top‐down approach. Herein, a new, bottom‐up microstructuring method is reported, which enables the patterning of n‐doped silicon substrates to be performed without the need for application of etch‐masks or stencils during the etching process. Instead, the structuring process developed herein involves a simple alkaline etching performed under illumination and is remotely controlled by the p‐doped micro‐sized implants, buried beneath a homogeneous n‐doped layer at depths of 0.25 to 1 µm. The microstructuring is realized because the buried implants act upon illumination as micro‐sized photovoltaic cells, which generate a flux of electrons and increase the negative surface charge in areas above the implants. The locally increased surface charge causes a local protection of the native silicon oxide layer from alkaline etching, which ultimately leads to the microstructuring of the substrate. In this way, substrates having at their top a thick layer of homogeneously n‐doped silicon can be structured, reducing the need for costly, time‐consuming photolithography steps.