Synthesis of SiC microstructures in Si technology by high dose carbon implantation: Etch-stop properties

The use of high dose carbon ion implantation in Si for the production of membranes and microstructures is investigated. Si wafers were implanted with carbon doses of 1017 and 5 × 1017 cm-2, at an energy of 300 keV and a temperature of 500°C. The structural analysis of these samples revealed the formation of a highly stable buried layer of crystalline β-SiC precipitates aligned with the Si matrix. The etch-stop properties of this layer have been investigated using tetramethyl-ammonium hydroxide as etchant solution. Secondary ion mass spectrometry measurements performed on the etched samples have allowed an estimate of the minimum dose needed for obtaining an etch-stop layer to a value in the range 2 to 3 × 1017 ions/cm2. This behavior has been explained assuming the existence of a percolation process in a SiC/Si binary system. Finally, very thin crystalline membranes and self-standing structures with average surface roughness in the range 6 to 7 nm have been obtained.