Method of prefilling of keyhole at the top metal level with photoresist to prevent passivation damage even for a severe top metal rule
 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 .ANG. to about 500 .ANG. and the gap has a deep, pocket-like cross-section with a width from about 500 .ANG. to about 1,200 .ANG. below the narrow neck. Partial stripping of the first photoresist layer, which follows, is performed by an etching process including wet and dry processing. 
Taiwan Semiconductor Manufacturing Company
H H
H01L H01L
additional inventional
Yu-Hua Min-Hsiung Jenn Ming
Lee Chiang Huang