Insulator for integrated circuits and process

The present invention is concerned with the use of certain flowable oxide layers as back end insulators for semiconductor devices. The present invention provides an insulator that exhibits a unique combination of relatively low dielectric constant below 3.2 and excellent gap fill capability. The back end insulator of the present invention can be formed by curing a flowable oxide layer and by annealing in the presence of hydrogen and aluminum. An insulator for covering an interconnection wiring level in a surface thereof on a semiconductor substrate containing semiconductor devices formed by curing a flowable oxide layer and annealing. The annealing is carried out in the presence of hydrogen and aluminum to obtain a dielectric constant of the oxide layer to a value below 3.2.Also provided is electrical insulation between neighboring devices using the flowable oxide which is cured and annealed. In this case, the annealing can be carried out in hydrogen with or without the presence of aluminum.