Study of physisorption phenomena of chemical species on 300 mm Si wafers during controlled mini-environment transfers between microelectronic equipments

In this work we investigate the behavior of the Si wafers top surface chemistry during transfers or storage between steps in the microelectronic production flow. The study uses a unique 300 mm characterization platform that allows vacuum transfers between separate equipments thanks to the use of specific carriers, thus leading to the concept of quasi insitu characterisations. In order to maximize surface sensitivity, pARXPS (parallel Angle Resolved XPS) analyses is widely used to investigate the Si top surface by considering systematically the grazing photoemission angle. In addition, thanks to a rigorous experimental protocol, the unwanted contribution coming from the setup chain itself is subtracted, and the exact C and O amount of physisorbed species coming from the carrier only is extracted. The results shows that using this simple carrier design, industrially compatible and without embedded pumping, a low level of physisorbed species is possible thanks to the preoutgassing step performed before each transfer. More, this low level can be improved significantly by partially filling the carrier with a low gas pressure (a few Torrs) and the physical phenomenoms explaining this behavior are discussed. Then an innovative improvement, based on using a low pressure of pure H2 is proposed and demonstrated for optimizing furthermore the performances. Beyond Si surfaces, the applications of such an optimized design will be of key interest for preserving the chemical surface integrity of highly more air sensitive materials than Si during transfer between separate equipments. [Display omitted] •Unique 300 mm setup with quasi insitu capability: vacuum carrier for wafers transfer.•Simple carrier design, industrially compatible without additional pumping.•Surface species quantified thanks to pARXPS and rigourous experimental protocol.•A low N2 pressure in carrier greatly improves the performances. Even more using H2.