Semiconductor device forming method

A semiconductor device and method of manufacture comprise placing an etch stop layer of a material such as aluminum oxide over a conductive element, placing a dielectric layer over the etch stop layer, and placing a hard mask of a material such as titanium nitride over the dielectric layer. Openings are formed to the etch stop layer, the hard mask material is selectively removed, and the openingsare then the material of the etch stop layer is then selectively removed to extend the openings through the etch stop layer. 半导体装置与其形成方法包括将蚀刻停止层置于导电单元上，且蚀刻停止层的材料可为氧化铝。将介电层置于蚀刻停止层上，并将硬遮罩置于介电层上。硬遮罩层的材料可为氮化钛。形成开口至蚀刻停止层，选择性地移除硬遮罩材料，接着选择性地移除蚀刻停止层的材料，使开口延伸穿过蚀刻停止层。