Planarizing insulating region used in production of ULSI switches comprises forming connecting surface oxide layer, first nitride layer, and oxide sacrificial layer

摘要

Planarizing an insulating region comprises forming a connecting surface oxide layer (14), a first nitride layer (18), an oxide sacrificial layer and a second nitride layer on a substrate (10); forming a trench through the layers and in the substrate; depositing an oxide layer which fills the trench and extends over the second nitride layer; chemical-mechanical polishing the oxide layer and the second nitride layer so that the second nitride layer has a thickness of 50-200 Angstrom ; removing the second nitride layer and the oxide sacrificial layer; and chemical-mechanical polishing the oxide layer and the first nitride layer so that the upper surface of the oxide layer aligns within 10% of the upper surface of the first nitride layer. Preferred Features: The connecting surface oxide layer is 40-80 Angstrom thick. The first nitride layer is 600-1000 Angstrom thick. The oxide sacrificial layer is 100-200 Angstrom thick. The second nitride layer is 200-1500 Angstrom thick. The trench is 2500-3000 Angstrom deep in the substrate. The oxide layer is produced using HDPCVD.