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Metal Deposition Technique for Pinhole Analysis in Solid Dielectrics

IP.com Disclosure Number: IPCOM000087525D
Original Publication Date: 1977-Feb-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Lechaton, JS: AUTHOR [+3]

Abstract

This technique enables the accurate and rapid location of pinholes through a solid dielectric, such as SiO(2).

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Metal Deposition Technique for Pinhole Analysis in Solid Dielectrics

This technique enables the accurate and rapid location of pinholes through a solid dielectric, such as SiO(2).

A silicon wafer coated with SiO is placed in a solution of copper sulphate. An ohmic contact is made from the substrate to a source of controllable DC power. An anode of electrically suitable material is suspended near the dielectric surface in the solution and is connected to the positive output of the power supply. A controlled current is sent through the electrolyte for a given time, resulting in the electrolytic reduction of the solution in any small hole in the dielectric which goes through to the substrate.

The result is that a deposit of copper is made in the hole and can be made to emerge on the surface as a ball or bead, many times larger than the hole. The resultant ball of metal is conspicuous and easily identifiable under a microscope; if allowed to grow enough, it can be seen by the naked eye under various light conditions. This positively locates the site of any hole. The ball is easily removed by mechanical or chemical means and the site, now located, can be further tested or inspected.

The amount of the voltage, current and density of copper sulphate or other electrolyte is variable, and can be changed to suit the effect desired. A voltage of about 30V, through a solution of about 30 grams CuSO4 to a liter of water applied to an anode about 50 mils away from a test wafer...