Browse Prior Art Database

Method and System for Mitigating Electromigration Effects by Creating Metal Topologies for Preferred Grain Boundary Formation

IP.com Disclosure Number: IPCOM000197734D
Publication Date: 2010-Jul-20
Document File: 5 page(s) / 53K

Publishing Venue

The IP.com Prior Art Database

Abstract

A method and system for reducing electromigration effects in a circuit is disclosed. The method includes minimizing grain boundary movement along the direction of a current flow. Further, the method facilitates in increasing the median time to failure of the metal line while maintaining voltage at slotted areas and reducing layout area of the circuit being constructed.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 52% of the total text.

Page 1 of 5

Method and System for Mitigating Electromigration Effects by Creating Metal Topologies for Preferred Grain Boundary Formation

Disclosed is a method and system for mitigating electromigration effects in a circuit.

Vacant elongated slots or holes in metal lines are typically created to reduce grain boundary movement. This facilitates in increasing the median time to failure of the metal lines due to electromigration. Depending on the maximum current (Imax) that an interconnect metal line is designed to carry, the metal interconnect metal line may be slotted (physical holes) or continuous without holes. Imax through a metal line is proportional to the width of the metal line. If the number of slots, the metal line has in its width increases, the physical width of the metal line has to be increased in order to maintain Imax. This significantly increases the layout size and area of the core layout as the metal interconnections have to be increased all throughout the layout for different nets and supply ground lines.

The method and system disclosed allows minimizing grain boundary movement along the direction of a current and reduces electromigration effects of a metal line by utilizing metallization structures. The metallization structure eliminates voiding due to current flow. A first length of metallization of a first width is used for carrying a rated current of a conductor. A second length of metallization of the first width is used for carrying the rated current of the conductor. A third length of metallization is used for connecting the first length of metallization to the second length of metallization. The third length of metallization has a physical width greater than the first width and is slotted to provide an electrical width equal to the first width. As a result, the third length of metallization provides a preferential stop for voids moving in the metallization.

As shown in Fig. 1, the wire width in non-slotted areas is increased to maintain desired Imax. This ensures that the wire area in non-slotted positions is also increased resulting in occupation of significant portion of the layout. Thus, the effective width of the metal interconnection (or wire) is maintained at the slotting positions by widening the width in either side of the slots along the longitudinal walls. In order to minimize the grain boundary movement between slots, elongated slots are used in the direction of current flow. In a scenario, holes may be utilized to replace some or all of the elongated slots. Further, the distance between the elongated slots/holes should be less than the length corresponding to the minimum "Backflow Potential" capacity for the metal interconnection l...