Vertical Edge Blocking Mask for BEOL Patterning Margin
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Solution Overview
Problem
As semiconductor devices continue to scale to smaller critical dimensions, edge placement error margins are decreasing, leading to increased risks of defects such as unwanted vias and shorts in the BEOL stack.
Innovation Solution
The implementation of a vertical edge blocking (VEB) mask layer, which is a conformal layer disposed along the sidewall and top surfaces of the grating, increases the edge placement error margin by effectively widening the lines of the grating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If gratings are used to provide increased overlay margins, then edge placement error margin is improved, but as critical dimensions scale, the widths of the gratings decrease and the margins continue to decrease
Solution Approach 1:
The patent introduces a vertical dimension by forming a conformal mask layer over the grating structure. This mask layer extends vertically from the grating surface, creating a three-dimensional blocking feature that increases the effective width of the grating in the lateral direction through its vertical profile, thereby providing increased edge placement error margin without requiring larger grating widths at the same critical dimension node
Solution Approach 2:
The conformal mask layer acts as an intermediary structure between the grating and the subsequent patterning layers. This intermediate vertical feature provides the necessary edge placement margin by creating a physical barrier that prevents printing defects from propagating, allowing the grating itself to maintain its scaled-down width while still providing adequate process margin
Data Source
AI summary
Embodiments disclosed herein include semiconductor devices and methods of forming such semiconductor devices. In an embodiment, a method of fabricating a semiconductor device comprises, forming a first grating of parallel first lines, forming a second grating of parallel second lines, wherein the second lines are substantially orthogonal to the first lines, and wherein the first lines and second lines define a plurality of first openings, disposing a conformal mask layer over the first lines and the second lines, wherein the conformal mask layer partially fills the first openings and defines a second opening within each of the first openings, disposing a hardmask over the conformal mask layer, wherein the hardmask fills the second openings, patterning third openings into the hardmask, wherein the third openings clear the hardmask from at least one of the second openings, and removing the mask layer proximate to cleared second openings to clear first openings.