Semiconductor processing methods of forming a contact opening to a semiconductor substrate

摘要

A semiconductor processing method of forming a contact opening to a substrate includes forming at least one conductive line over the substrate adjacent a substrate contact area to which electrical connection is to be made. A first oxide layer is formed over the substrate to cover at least part of the contact area. A second oxide layer is formed over the first oxide layer and is formed from a different oxide than the first oxide layer. A first etch is conducted over the contact area and through the second oxide layer to a degree sufficient to leave at least a portion of the first oxide layer over the contact area. A second etch is conducted to a degree sufficient to remove substantially all of the first oxide layer left behind and to remove a desired amount of the second oxide layer laterally outwardly of the contact area. According to one preferred aspect of the invention, the first oxide layer is formed from decomposition of tetraethyloxysilane (TEOS) and the second oxide layer comprises borophosphosilicate glass (BPSG). According to another preferred aspect of the invention, the second etch is an isotropic etch using an aqueous solution comprising fluorine having less than or equal to about 10% by weight of an etch rate changing surfactant which etches the second oxide layer at a slower rate than the first oxide layer.