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Method for Implementing Redundant Vias in Unidirectional Designs

IP.com Disclosure Number: IPCOM000247615D
Publication Date: 2016-Sep-20
Document File: 4 page(s) / 74K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method of forming redundant vias for Self-Aligned Doubled Patterning (SADP)-generated metal layers in semiconductor circuits along with a novel metal/via structure. This solution can opportunistically and efficiently insert redundant vias and tracks in unidirectional designs.

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Page 01 of 4

Title

Method for Implementing Redundant Vias in Unidirectional Designs

Abstract

Disclosed is a method of forming redundant vias for Self-Aligned Doubled Patterning (SADP)-generated metal layers in semiconductor circuits along with a novel metal/via structure. This solution can opportunistically and efficiently insert redundant vias and tracks in unidirectional designs.

Problem

Unidirectional designs cannot have redundant vias or viabars, as the design requires two-dimensional (2D) metal constructs to provide landing pads and space to accommodate the redundant via or viabar. This is specifically important for Back End of Line (BEOL) processes using Self-Aligned Doubled Patterning (SADP), where lateral sizing up not usually possible (resulting in long range coloring conflicts).

Solution/Novel Contribution

The novel contribution is a method of forming redundant vias for SADP-generated metal layers in semiconductor circuits along with a novel metal/via structure.

The novel method comprises:


• Finding available empty tracks to form a redundant connection

• Picking available tracks by taking into account yield and performance criteria
• Generating redundant tracks in design, including metal and via shapes

• Providing feedback with connectivity information to the design database

The novel structure comprises:


• Metal shapes created by SADP

• Redundant tracks formed by the method above, comprising parallel metal tracks
connected by redundant vias

• Redundant tracks may be formed in a metal layer above or below the respective via and can have a multitude of parallel structures and connected vias

The algorithm looks for empty tracks post place and route (P&R) and connects two lines with a parallel running line, thus providing redundancy. The redundancy can also be achieved by utilizing an empty metal track in a layer above or below. This solves the fundamental problems of unidirectional designs. Without via redundancy, yield will be severely defect limited.


Page 02 of 4

Figure 1: Novel method

Method/Process

Existing methods involve widening of lines an inserting mandrel transitions. The method introduced here scans the Graphics Database System (GDS) for empty tracks and matches those to possible redundancy path...