Abstract
Wafers with different epitaxial layer thicknesses of 12, 18, 20, 25, 30 and 40 μm and high resistivities ranging from 0.03 to 8.0 kΩ⋅cm have been investigated in this study. To verify their properties, surface resistivity measurement, scanning electron microscopy inspection and spreading resistance profiling have been performed. The results indicate that wafers with a 25-μm epitaxial thickness are well-suited to our requirements for use as a starting material for ALPIDE chip production in the ALICE ITS upgrade project.