Abstract: The present invention remedies the problems associated with selective etching of material, and in particular tungsten, by locally removing the material (e.g. tungsten) from the alignment marks through wet etching without the need for any photo steps. Either before or after chemical mechanical polishing, the wafers are flatly aligned and a tungsten etching agent is introduced through an etchant dispensing apparatus onto the alignment marks. Since an alignment mark is normally a few hundred microns in size and there is a large unused silicon real estate around the alignment marks, the alignment constraints vis-a-vis etchant dispensing apparatus and wafer are not very critical and tungsten plugs in the live dice are easily protected from the wet etch. After the etch, the etching byproduct is removed by suction and the wafer is cleaned by being rinsed in distilled water.

Abstract: A semiconductor processing method of chemical mechanical polishing an aluminum containing metal layer on a semiconductor substrate includes, a) providing a chemical mechanical polishing slurry comprising H.sub.3 PO.sub.4 at from about 0.1% to about 20% by volume; H.sub.2 O.sub.2 at from about 1% to about 30% by volume, H.sub.2 O, and a solid abrasive material; and b) chemical mechanical polishing an aluminum containing metal layer on a semiconductor substrate with the slurry. Such process and slurry are also usable in chemical mechanical polishing of other layers, such as Ti, TiN and TiW materials. Such enables chemical mechanical polishing of a barrier metal/aluminum layer composite in a single polishing step, leading to increased controllability and resulting increased throughput. With respect to aluminum containing metal layers, the H.sub.2 O.sub.2 is understood to cause oxidation to aluminum oxide, which is subsequently removed by both chemical and mechanical action the result of the polish and slurry.