Free-standing porous silicon membranes were fabricated by electrochemical anodisation of 6 inch diameter p + type wafers.
An n-type wafer is generally chosen as the starting material.
A p-type wafer is doped with POCl3.
First, a p-type layer was fabricated by diffusing into a lightly doped n-type wafer on polished surface.
The figure shows a schematic representation of the locally formed porous Si layer on the p-type wafer and SEM images of the porous Si surface.
The technology involves ion-implanted piezoresistors formation on the backside and a novel anisotropic etching on the front side of an n-type wafer.
The gold films were deposited onto two substrates: standard Si (100) n-type wafer (5-cm diameter) and glass (25 × 25 mm2, 0.1-mm thick, Marienfeld, Lauda-Königshofen, Germany).
A specimen with an oval trench, which was made of a p-type wafer, was designed for compressive stress concentration over 2 GPa applicable without any possibility of fracture.
To model the electrolyte/mask/silicon interface behavior, we considered a semiconductor/metal contact at the front side of a p-type wafer (1015 at./cm3) with a bias of -1 V applied on the conductor border at 30 μ m from the semiconductor surface.
Corresponding, the iVoc and recombination current density (Joe) could reach ∼745 mV and ∼9.5 fA/cm2 (Δn = 5 × 1015 cm−3) for the 1-Ω cm and 200-μm n-type wafer covered with high-quality oxide and n+-Si layers.
Silicon n-type wafers with <100> crystallinity are used to etch pores growing perpendicular to the wafer surface.
