MECHANISMS OF METALLIC IMPURITY DEPOSITION ON SILICON SUBSTRATES DIPPED IN CLEANING SOLUTION

A theoretical and experimental study of metallic deposition on silicon substrates was carried out in the cleaning solutions most widely used in microelectronics. This study highlights three preponderant deposit ion mechanisms: (i) physisorption due to van der Waals interactions be tween the substrate and metallic impurities, (ii) chemisorption which results from electrons commonly shared between the substrate and metal lic impurities, and (iii) metal displacement due to a transfer of elec trons between the substrate and metallic impurities. In addition, the solution ionic strength and the polarity of the impurities and of the silicon surface are shown to be relevant parameters which govern the t ransfer of impurities from the heart of the solution to the substrate.