Browse Prior Art Database

COPPER PLATING ON SURFACE OF POWER DEVICES

IP.com Disclosure Number: IPCOM000008049D
Original Publication Date: 1997-Mar-01
Included in the Prior Art Database: 2002-May-15
Document File: 1 page(s) / 73K

Publishing Venue

Motorola

Related People

Diann M. Dow: AUTHOR [+3]

Abstract

Smaller integrated power devices are desired. The two main problems with integrated power devices are transient heat dissipation and on resis- tance. This invention provides a solution for both problems.

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@ MOTOROLA Technical Developments

COPPER PLATING ON SURFACE OF POWER DEVICES

by Diann M. Dow, Stephen W. Dow and Hak-Yam Tsoi

PROBLEM

  Smaller integrated power devices are desired. The two main problems with integrated power devices are transient heat dissipation and on resis- tance. This invention provides a solution for both problems.

PRIOR ART

  A capping metal of relatively thin, (3um), alu- minum has been used to lower drain to source on resistance (Rdson). Other proposed methods have focused on removing heat from the backside of the power device.

INVENTION

  The idea is to plate thick copper on the surface of a power device. Plated copper thicknesses of 15um to 25um is proposed for initial evaluations. The copper will be connected to the underlying metal of the power device through the use of a TiW and copper intermetallic structure. Passivation may or may not be used on the surface of the copper. The copper and TiW barrier metal will provide pro- tection for the underlying active area.

  Using thick copper over the active device will also enable the ability to wirebond over the active device. Since copper is proposed as the plating material, copper wirehonds can be reliably used.

  The thick plated copper will serve as a heat sink for the power device. It will also greatly reduce the on resistance of the device.

  Wirebonding over the active area will also improve power dissipation and on resistance. Die size will be reduced since additional bond pads will not be necessary for the source connections of the device and the device size can also be made s...