Method of prefilling of keyhole at the top metal level with photoresist to prevent passivation damage even for a severe top metal rule

摘要

This is a method of planarizing a surface of a photoresist layer formed above a layer formed over a gap in a blanket silicon nitride layer which in turn is formed above a keyhole in metallization with SOG layers therebetween on the surface of a semiconductor device. The following steps are performed. Form a blanket, first photoresist layer above the blanket silicon nitride with a damaged surface caused by the gap. Then strip the first photoresist layer leaving a residual portion of the first photoresist layer in the gap. Next, form a blanket, second photoresist layer above the blanket layer. The gap has a neck with a width from about 200 Å to about 500 Å and the gap has a deep, pocket-like cross-section with a width from about 500 Å to about 1,200 Å below the narrow neck. Partial stripping of the first photoresist layer, which follows, is performed by an etching process including wet and dry processing.