A chemical mechanical polish (CMP) planarizing method for forming a planarized organo-functional siloxane polymer dielectric layer within a microelectronics fabrication. There is first provided a substrate employed within a microelectronics fabrication. There is then formed over the substrate an organo-functional siloxane polymer dielectric layer. The organo-functional siloxane polymer dielectric layer is then partially treated with an oxygen containing plasma to form from the organo-functional siloxane polymer dielectric layer an oxygen containing plasma treated organo-functional siloxane polymer dielectric upper layer and an organo-functional siloxane polymer dielectric lower residue layer. Finally, the oxygen containing plasma treated organo-functional siloxane polymer dielectric upper layer is planarized through a chemical mechanical polish (CMP) planarizing method to form a planarized oxygen containing plasma treated organo-functional siloxane polymer dielectric upper layer.