Structures using chemo-mechanical polishing and chemically-selective endpoint detection

摘要

One embodiment of the present invention provides a process that uses selective etching to form a structure on a silicon substrate. The process starts by receiving the silicon substrate with a first layer composed of a first material, which includes voids created by a first etching operation. The process then forms a second layer composed of a second material over the first layer, so that the second layer fills in portions of voids in the first layer created by the first etching operation. Next, the process performs a chemo-mechanical polishing operation on the second layer down to the first layer so that only remaining portions of the second layer, within the voids created by the first etching operation, remain. The system then forms a third layer composed of a third material over the first layer and the remaining portions of the second layer, and performs a second etching operation using a selective etchant to remove the remaining portions of the second layer, thereby creating voids between the first layer and the third layer.