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A Structure and Method for bi-directionally self aligned vias (bSAV)

IP.com Disclosure Number: IPCOM000201787D
Publication Date: 2010-Nov-23
Document File: 3 page(s) / 117K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a system and methods for an integration and etch scheme that achieves a bi-directionally self-aligned Via scheme. The invention incorporates topographic alignment to the underlying trench level in conjunction with trench first metal hardmask (TFMHM) integration scheme for self alignment in the other direction.

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A Structure and Method for bi-directionally self aligned vias (bSAV)

For a self-aligned vias (SAV) process with a trench first metal hard mask integration scheme, vias (Vx) are self-aligned perpendicular to the trench (Mx+1) direction, but are not self-aligned along the trench (Mx+1) direction. This causes a potential Vx - Mx shorting problem. Currently, the process relies on heavy etch shrink to maintain the
Via CD control along the trench direction; however, once the overlay along trench direction is slightly beyond control, the risk of Vx-Mx shorting is high. Non Adjacent (or Diagonal only) Via placement is a design limitation that developers have had to impose. As the pitch of Mx reduces (56nm & 40 for 15S & 16S respectively), the demands on Lithographic Overlay tolerance and etch shrink further tighten.

Where Self-Aligned Vertical Interconnect Access (Via) Technology allows for self alignment in the direction perpendicular to the top trench, bi-directional self alignment to the intersection point as defined by two orthogonal trenches in consecutive levels is the ultimate requirement. The need for alignment in the direction parallel to the top trench (perpendicular to the bottom trench in a cross point array) becomes critical as trench pitches go into the deep sub 80nm regime in the 15S and 16S nodes.

The disclosed solution is an integration and etch scheme that achieves a bi-directionally Self-aligned Via scheme. The invention incorporates topographic alignment to the underlying trench level in conjunction with trench first metal hardmask (TFMHM) integration scheme for self alignment in the other direction.

In a typical embodiment, the solution is demonstrated with, but not limited to, M1V1M2 integration. (Figure) In this disclosure, metal M1 is protruded above M1 dielectrics. The height topography difference is large enough that it is still memorized post M2 dielectric and TiN hard mask deposition. When performing V1 etch in the via open programming language (OPL) etch step, vias lands first on the locations with M1 since it is with higher topography; by controlli...