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Method for a lifted compliant die-package interconnect

IP.com Disclosure Number: IPCOM000010066D
Publication Date: 2002-Oct-16
Document File: 3 page(s) / 35K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a structure for a lifted compliant die-package interconnect along with a method for creating it. Benefits include improved reliability and improved ease of manufacturing over other proposed compliant interconnects.

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Method for a lifted compliant die-package interconnect

Disclosed is a structure for a lifted compliant die-package interconnect along with a method for creating it. Benefits include improved reliability and improved ease of manufacturing over other proposed compliant interconnects.

Background

        � � � � � Coefficient for thermal expansion (CTE) mismatch between the die and the package substrate induces large stresses in on-die structures. With the introduction of low dielectric constant (k) and ultra-low k interlayer dielectric (ILD) materials, these forces are large enough to cause fracture and delamination unless an architectural or process change is made. This problem does not conventionally exist because low k and ultra-low k materials are not in production. Proposed solutions include:

1.        � � Low CTE substrates

2.        � � Changing the assembly process

3.        � � Other varieties of compliant interconnects

        � � � � � These possible solutions are not ideal due to the following reasons respectively:

1.        � � Moves the CTE mismatch to the package/motherboard interface

2.        � � May not be possible or sufficient
3.        � � Can be relatively complicated and expensive to manufacture

General description

        � � � � � The disclosed method is a thin film die-package interconnect that stands off the surface of the die, making it highly compliant (see Figure 1).

        � � � � � The disclosed method solves the CTE mismatch-induced stress problem without adding cost. The fabrication process of the proposed compliant interconnect is much simpler than other types of compliant interconnects.

        � � � � � The key elements of the method include:

•        � � � � 3-D lifted interconnect through lithographic processes

•        � � � � Use of a polymer reflow step to induce dome shape

• ...