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Method for significantly enhancing the number of boiling nucleation sites in a two-phase microchannel cooling system fabricated in silicon

IP.com Disclosure Number: IPCOM000029751D
Publication Date: 2004-Jul-09
Document File: 8 page(s) / 102K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for significantly enhancing the number of boiling nucleation sites in a two-phase microchannel or cooling system fabricated in silicon. Benefits include improved functionality and improved performance.

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Method for significantly enhancing the number of boiling nucleation sites in a two-phase microchannel cooling system fabricated in silicon

Disclosed is a method for significantly enhancing the number of boiling nucleation sites in a two-phase microchannel or cooling system fabricated in silicon. Benefits include improved functionality and improved performance.

Background

      The performance of a two-phase microchannel liquid cooling (boiling) system must be improved. Two-phase cooling is a potential solution for removing the heat from a hot integrated circuit (IC) chip. This type of cooler relies on converting liquid to steam on the IC chip due to the heat generated by the IC chip. Increasing the number of nucleation sites results in very efficient boiling and an increase in the heat-transfer coefficient.

      The conventional microchannel heat exchanger uses parallel channels formed in silicon by deep reactive ion etching.

General description

      The disclosed method is the fabrication of a microchannel cooling system out of silicon with enhanced nucleation sites.

              The key elements of the method include:

•             Integrated circuit die

•             Microchannel cooler fabricated in silicon

•             Porous silicon

Advantages

The disclosed method provides advantages, including:

•             Improved functionality due to increased nucleation sites in the microchannel cooler

•             Improved performance due to decreased thermal resistance in the cooler because of increased nucleation

Detailed description

      The disclosed method significantly enhances the number of boiling nucleation sites in a two-phase microchannel cooling systems fabricated in silicon. The method can be described with an example of p-type silicon, although process flows for n-type silicon can also be defined.

 The example is for the case when the two-phase microchannel cooler is attached later to the backside of a die that already has an IC device fabricated on the front-side. However, the concept can be implemented directly on the back of a die with an IC device on the front-side.

This attachment may be on the die or the wafer.  The example defines the case when a patterned array of pores is used. Flows are possible with random pore locations.

      The disclosed method can be implemented using the following steps:

1.   A layer of nitride or oxide is deposited on a silicon wafer. The nitride or oxide may be deposited on one side of the wafer using chemical vapor deposition (CVD). Alternatively, the nitride or oxide may be deposited on both sides of the wafer using thermal or low pressure chemical vapor deposition (LPCVD, see Figure 1).

2.           A layer of resist material is spun on the wafer. If only one side of the wafer has a layer of nitride or oxide, this side receives the resist material. The resist is patterned with a hexagonal array of squares the size and spacing of which is a function of the resistivity of th...