Structure and Method for Fully-Aligned Via Cap Erosion Control
Publication Date: 2016-Nov-08
The IP.com Prior Art Database
Disclosed is a method to utilize a thin liner material with high Reactive Ion Etching (RIE) selectivity to preserve the Fully-Aligned Via (FAV) spacer, which is essential to good alignment of the vias and via size consistency.
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Structure and Method for Fully -
Cap erosion caused by ultra-low K (ULK) Reactive Ion Etching (RIE) selectivity is reducing effectiveness of the Fully-Aligned Via (FAV) process. Selectivity of cap materials due to conformal deposition requirements in the FAV scheme is the main limitation. Optimization of RIE selectivity is difficult to achieve while maintaining desired profiles.
Figure 1: Background/Problem Definition
The novel solution is to utilize a thin liner material with high RIE selectivity to preserve the FAV spacer, which is essential to good alignment of the vias and via size consistency. The approach uses Atomic Layer Deposition (ALD) metallic liner deposition to provide the needed selectivity to prevent cap erosion. The metallic liner is a sacrificial, wet removable layer in which the removal process has high selectivity to the rest of the stack. This wet removal of the liner has minimal impact on the final profile. Techniques to remove this liner are readily available.
The process splits the dielectric RIE into two sections, via etch and trench etch, with a liner deposition occurring between the two etches.
Figure 2: Liner deposition
The final structure in FAV region then has stronger chamfer control, via CD uniformity, and a larger via overlay tolerance.
-Aligned Via Cap Erosion Control
Aligned Via Cap Erosion Control
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The liner protection method explored by the chamferless via scheme (existing methods) can enable the fully aligned vi...