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SADP scheme with Self-aligned cuts and self-aligned vias

IP.com Disclosure Number: IPCOM000246024D
Publication Date: 2016-Apr-26
Document File: 10 page(s) / 1M

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a flow that enables both self-aligned cuts for self-aligned double patterning (SADP) at 40nm pitch or less and self-aligned vias

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Title

SADP scheme with Self-aligned cuts and self-aligned vias

Abstract

Disclosed is a flow that enables both self-aligned cuts for self-aligned double patterning (SADP) at 40nm pitch or less and self-aligned vias.

Problem

A method is needed to enable self-aligned double patterning (SADP) at 40nm pitch or less, with self-aligned cuts and self-aligned vias, with vias also self-aligned to cuts.

Solution/Novel Contribution

The novel contribution is a flow that enables both self-aligned cuts for SADP at line pitch <40nm and self-aligned vias. The core novelty is illustrated in steps 5 to 10 (Fig. 1). The concept of capping the lines and self-aligning the vias is covered by prior art.

The scheme is developed for opposite polarity. The goal is not a pattern in Titanium Nitride (TiN) Hard Mask to etch trenches, but is for a block TiN to pattern bottom amorphous silicon (a-Si) lines (post cut).

Figure 1: Summary

Method/Process

The following figures illustrate the steps for implementing the solution.

Figure 2: Lower interconnect metal (M0) process

Unidirectional Back End of Line (BEoL) illustrated (same works for BiDirectional)


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Figure 3: M1 stack build-up


• Top Amorphous silicon (a-Si) is Mandrel layer pre-cut

• Titanium Nitride (TiN) is first an etch stop, then a Hard Mask
• Silicon oxynitride (SiON) acts as an etch stop

• Bottom a-Si is Mandrel layer post-cut


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Figure 4: M1 Mandrel etch for SADP

Figure 5: Cut 1 patterning: Mandrel cut

• This cut is performed while pitch is 80nm, so optical lithography is capable (regarding overlay) to fully land on the correct mandrel without risking to inadvertently clip an adjac...