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Method of defining 2D structures in BEOL using self-aligned multiple patterning

IP.com Disclosure Number: IPCOM000236124D
Publication Date: 2014-Apr-07
Document File: 2 page(s) / 34K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method of defining 2D structures in Back End of Line (BEOL) using both cut/block masks.

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Title

Method of defining 2D structures in BEOL using self-aligned multiple patterning

Abstract

Disclosed is a method of defining 2D structures in Back End of Line (BEOL) using both cut/block masks.

Problem

Optical lithography (ArF immersion) can be used when defining Back End of Line (BEOL) layers, such as Mx below 40nm pitch. Self-aligned multiple patterning, such as self-aligned quadruple patterning (SAQP), is used to print beyond the resolution limit. SAQP is the preferred method to define metal lines because other multiple patterning is challenged by the overlay to meet minimum insulator specification.Some jog is desirable when defining the Mx layer; without it, route-ability is dramatically reduced. However, defining jogs within the SAQP process is highly challenging.

Conventionally, only one mask (for BEOL, block mask) is used.

Figure 1: Example SAQP process flow using 30 nm final pitch

Solution/Novel Contribution

The solution is a method of defining BEOL using both cut/block masks. In order to achieve a 2D metal structure, the novel method uses two additional masks (e.g., bright/dark tones, cut/block masks). The 2D structures are defined by cutting unwanted spacers and blocking open regions to define the line- end (or dielectric).

Method/Process

The following figures illustrate the process flow.


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Figure 1: Steps 1-3. Two additional masks (cut +block) are used to define the 2D structure.

Figure 2: Steps 4-6