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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) / 78K

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

• ...