Method for making a microelectronic interposer

Abstract

A microelectronic interposer is made by providing a sacrificial layer over the surface of a planar body. Apertures are formed passing through the body and the sacrificial layer. A layer of an electrically conductive structural material is deposited in each of the apertures and over the sacrificial layer, proximate to each aperture to thereby form contacts. The sacrificial layer is removed leaving the contacts with outwardly flaring peripheral portions spaced vertically above the surface of the planar body.

Description

CROSS REFERENCE TO RELATED APPLICATIONS [0001] The present application is a divisional application of U.S. patent application Ser. No. 10 / 658,941, filed Sep. 10, 2003, which is a divisional application of U.S. patent application Ser. No. 10 / 200,941, filed Jul. 23, 2002, which is a divisional application of U.S. patent application Ser. No. 09 / 779,117, filed Feb. 8, 2001, which is a divisional application of U.S. patent application Ser. No. 08 / 989,305, filed Dec. 12, 1997, now U.S. Pat. No. 6,247,228, which claims the benefit of Provisional Patent Application No. 60 / 032,884, filed Dec. 13, 1996, which applications are hereby incorporated by reference in their entirety herein.BACKGROUND OF THE INVENTION [0002] The present invention relates to the field of electrical circuitry, and more particularly relates to layered circuit structures such as multilayer circuit boards, to components and methods utilized in fabrication of such structures and to methods of making the same. [0003] Electr...

AI Technical Summary

Benefits of technology

[0020] One aspect of the present invention provides an interposer for making connections to electrical contact pads on a surface of a microelectronic element, such as a circuit panel, a semiconductor chip or other element having a contact bearing surface. The contacts define holes therein. The interposer includes a body having a first major surface, such that the body has horizontal directions parallel to the first major surface and vertical directions perpendicular to the first major surface. The interposer further has a plurality of conductors in the body, such as via conductors extending in or through the body. The interposer further has a plurality of contacts on or above the first major surface. Each of the contacts is permanently joined to one of the conductors, and extends radially outwardly from the conductor. Thus, each contact extends in a plurality of horizontal directions away from the conductor. Each contact has a periphery remote from the conductor and a central portion attached to the conductor. The contacts are adapted to deform so that the periphery of the contact will contract radially inwardly toward the central portion of the contact in response to urging the periphery of the contact against one of the contact pads on the surface of the microelectronic element, and inserting the central portion of the contact into the hole defined by the contact pad. As the microelectronic element is juxtaposed with the first surface of the interposer and forced toward the body, the contacts will wipe the contact pads of the microelectronic element. The wiping action removes oxides and other contaminants from the mating surfaces to provide an effective, low resistance electrical connection between the pads and the contacts and, in preferred embodiments, to facilitate bonding of the contacts and the pads.

[0028] In another embodiment of the invention, an interposer for making connections to electrical contact pads on a surface of a microelectronic element is provided. The interposer includes an interposer body have a first surface and a plurality of contacts on the body. Each of the contacts includes a central portion and a plurality of tabs extending radially outward from the central portion. Each of the tabs extends over the first surface, and is adapted to deform radially inward toward the central portion of the contact, in response to a force on the tab directed downward toward the body. The tabs may have asperities on top surfaces facing upward away from the body. The asperities engage and wipe a contact pad engaged with the contact, breaking through any oxidation that may be present on the contact pad in order to form a more reliable electrical contact.

[0035] The method may also include the step of bonding the contacts to the contact pads. The bonding step may include momentarily heating the stacked panels and interposers to activate electrically conductive bonding material that interfaces between the contacts and the vias. The bonding material may be carried on the contact pads. The momentary heating step may cause a softening of the body of the interposer, thereby facilitating vertical movement of the peripheral portions of the contacts during the compressing step.

Problems solved by technology

It is difficult to drill holes with a high ratio of depth to diameter.

Thus, the holes used in assemblies fabricated according to these prior methods must be relatively large and hence consume substantial amounts of space in the assembly.

Moreover, the electrical interconnections formed by depositing conductive materials in such drilled holes tend to be weak.

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