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Ultra-Small Test Probe

IP.com Disclosure Number: IPCOM000046637D
Original Publication Date: 1983-Aug-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 2 page(s) / 51K

Publishing Venue

IBM

Related People

Bojarczuk, NA: AUTHOR [+2]

Abstract

A method of making ultra-small test probes of 1-micrometer diameter that will allow smaller fan-out test patterns, test pads and closer spacing of some devices or chips in certain designs is described. This allows for increased packing density of structures, shorten test lines to improve electrical testing, and allows for direct testing of chip sites. In order to make very fine (about 1-micrometer wide) probes, there is used the unique property of metal under electromigration to create huge stresses and form the probes by extrusion. To get the desired shape, first a narrow thin film of metal 10, e.g., aluminum,is deposited over a diffused contact 12 on a silicon wafer 14. The contact to the silicon is very highly doped to provide high conductivity.

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Ultra-Small Test Probe

A method of making ultra-small test probes of 1-micrometer diameter that will allow smaller fan-out test patterns, test pads and closer spacing of some devices or chips in certain designs is described. This allows for increased packing density of structures, shorten test lines to improve electrical testing, and allows for direct testing of chip sites. In order to make very fine (about 1-micrometer wide) probes, there is used the unique property of metal under electromigration to create huge stresses and form the probes by extrusion. To get the desired shape, first a narrow thin film of metal 10, e.g., aluminum,is deposited over a diffused contact 12 on a silicon wafer 14. The contact to the silicon is very highly doped to provide high conductivity. Also, the contact is as large as possible to increase the overall contact conductance. A passivating glass or SiO2 layer 16 is deposited over the structure. The passivating layer 16 is as thick as the probe to be made is long. After the passivating layer deposition, a hole 17 is made in the layer 16 directly over the diffused contact. A good way to make this hole is by laser drilling to complete the Fig. 1 structure. A high current of greater than 106 A/cm2, or about 100 ma., for a 1-micrometer thick, 5-micrometer wide film is passed through the metal. Very high compressive stresses of greater than about 1010 dynes/cm2 will develop in the metal film because: 1. the metal-to-silicon contact has th...