AbstractThis paper reports on recent improvements in organic spin‐on glass (SOG) planarization technology combined with etch‐back process. A general rule has been established for SOG planarization mechanism that is suitable for every kind of wiring pattern distribution. This general rule, the volume constant rule, shows that the SOG volume in a certain projection length along the horizontal direction is constant and independent of the wiring width. Based on this rule, it is found that the SOG planarization process margin can be increased significantly by decreasing the plasma SiO2(= P‐SiO2) layer thickness underneath the SOG layer.The characteristics of this newly developed organic SOG material have been investigated. This new organic SOG material developed by Hitachi Chemical Company, Ltd. (HSG‐2209S‐R7) has heat reflow capability that causes the movement of SOG on the wires to the space during the second baking; this results in improvements in local planarization and decrease in the SOG thickness on the wires.A six‐level metallization test structure for a logic LSI has been successfully created using the optimized process