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Browse Prior Art Database

Process for Nucleate Boiling Enhancement

IP.com Disclosure Number: IPCOM000084655D
Original Publication Date: 1975-Dec-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Chu, RC: AUTHOR [+2]

Abstract

A method is provided for enhancing the onset of nucleate boiling and for extending the nucleate boiling range of semiconductor chips in a liquid cooled package, by standard semiconductor processing applied to the back side of the wafer.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 92% of the total text.

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Process for Nucleate Boiling Enhancement

A method is provided for enhancing the onset of nucleate boiling and for extending the nucleate boiling range of semiconductor chips in a liquid cooled package, by standard semiconductor processing applied to the back side of the wafer.

The number of bubble sites on a chip is a random variable effected by surface material and finish. In some cases, the onset of boiling is delayed until some critical power density, leading to abnormally high-chip temperatures. Further, the upper limit of nucleate boiling is believed to be a function of the number of sites which are producing the vapor bubbles. Both of these effects are enhanced by artificially providing a number of doubly reentrant cavities on the back side of a chip. These bubble sites are formed during standard semiconductor processing by the following method steps:
1. Applying photoresist to the back side of a wafer after any

glassing operation;
2. Applying a nonaligned mask containing the required number

and spacing of efficient bubble sites; and
3. Etching through the glass and into the silicon, undercutting

the hole (as will occur naturally), and thus forming the

reentrant cavity desired for this purpose.

This method has the following advantages:
1. It uses standard semiconductor processing.
2. It leaves no debris.
3. There is no mask alignment necessary.
4. It may be applied after any of the various glassing

operations

in the standard semiconductor processing.
5. The...