Cooling microfan arrangements and process

• US 5,326,430 A
• Filed: 12/07/1993
• Issued: 07/05/1994
• Est. Priority Date: 09/24/1992
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Sullivan, Timothy D., Ryan, James G., Cronin, John E., Previti-Kelly, Rosemary A.
• Primary Examiner(s): POWELL, WILLIAM A
• Application Number:
  US08/164,494
• Time in Patent Office: 210 Days
• Field of Search: 156/643, 156/644, 156/653, 156/655, 156/656, 156/657, 156/659.1, 156/662, 156/663, 156/668, 310/40 R, 310/40.5, 310/261, 310/262, 310/309, 437/228, 437/233, 437/238, 437/241, 437/245
• US Class Current: 438/584
• CPC Class Codes: F04D 25/08 the working fluid being air, e.g. for ventilation
• CPC Class Codes: H02N 1/004 in which a body is moved along a path due to interaction with an electric field travelling along the path

Abstract

A micro electrostatic cooling fan arrangement is provided which includes a heat source having a planar surface, a stator attached to the heat source, an axle attached to the heat source and spaced from the stator, a rotary element including a hub having an aperture therein and a fan blade, the axle passing through the aperture of the hub and the fan blade having a major surface thereof disposed at an angle with respect to the surface of the heat source and attached to the hub at one end, with the other end of the fan blade being adjacent to but spaced from the stator and a voltage source applied to the stator having sufficient voltage to charge the fan blade. Also, a process is provided for making a microfan which includes forming a strip of sacrificial material on a planar surface of a heat source, applying a spin on insulating layer over the heat source and the strip for producing a sloping surface extending from about the top of the strip toward the planar surface of the heat source, applying a layer of conductive material on the sloping surface and strip and defining from the layer of conductive material a fan blade on the sloping surface of the spin on insulating layer and a stator at one end of the fan blade.

Claims

1. A process for making a microfan comprising

forming a strip of sacrificial material on a planar surface of a heat source,

applying a spin on sacrificial material over the heat source and the strip to produce a sloping surface extending from about the top of the strip toward the planar surface of the heat source,

applying a layer of conductive material on the sloping surface and strip and

defining from the layer of conductive material a rotary blade on the sloping surface of the spin on sacrificial material and a stator at one end of the blade.

2. A process for making a microfan as set forth in claim 1 wherein forming the strip of sacrificial material includes forming a strip of insulating material.

3. A process for making a microfan as set forth in claim 1 wherein forming the strip of sacrificial material includes forming a strip of silicon dioxide and wherein applying the layer of conductive material includes applying a layer of polysilicon.

4. A process for making a microfan as set forth in claim 1 wherein applying the layer of conductive material includes applying a layer of metal.

5. A process for making a microfan comprising

forming a segment of a given insulating material on a planar surface of a semiconductor substrate having a source of heat therein,

forming a strip of insulating material on the planar surface of said semiconductor substrate,

forming a layer of insulating material over said semiconductor substrate and said strip of insulating material by using spin on techniques to provide a sloping surface on the layer of insulating material from the top of said strip toward the planar surface of said semiconductor substrate,

applying a layer of electrically conductive material on said layer of insulating material,

defining in said layer of electrically conductive material a rotary element including a fan blade on the sloping surface of said layer of insulating material and a hub having an aperture therein and a stator on said segment of the given insulating material,

forming an axle within the aperture of said hub, and

etching away said strip of insulating material and said layer of insulating material.

6. A process for making a microfan as set forth in claim 5 further including forming a bushing under the hub of said rotary element made of said given insulating material.

7. A process for making a fan arrangement on a semiconductor chip having a heating source therein comprising

forming a plurality of channels at a planar surface in said chip,

applying a thermally conductive layer on the planar surface of said chip and into said plurality of channels,

forming a plurality of insulating segments on said thermally conductive layer,

applying a planarizing sacrificial layer over said thermally conductive layer,

forming a plurality of sacrificial strips on said planarizing layer extending outwardly from a given point,

forming a plurality of bushings in a circular arrangement,

applying a spin on sacrificial layer on said planarizing layer and on said strips to provide sloping surfaces extending from about the top of each of said plurality of sacrificial strips toward the planar surface of said chip,

applying a first electrically conductive layer on said spin on sacrificial layer and on said plurality of insulating segments,

defining in said electrically conductive layer a rotary element including fan blades on the sloping surfaces of said spin on sacrificial layer and a hub having an aperture therein and a plurality of stators each disposed on a respective one of said plurality of insulating segments, said hub being disposed above but spaced from said plurality of bushings,

forming an opening defined by the aperture in said hub to said thermally conductive layer through the sacrificial material,

applying a conformal sacrificial layer over said electrically conductive layer and on the sidewalls of said opening,

applying a second electrically conductive layer over said conformal sacrificial layer and over said thermally conductive layer,

defining in said second electrically conductive layer an axle within the aperture in said hub, and

etching away said planarizing sacrificial layer, said plurality of sacrificial strips, said spun on sacrificial layer and said conformal sacrificial layer to free said rotating element from said axle.