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Cryo Panel Heat Absorber to Enhance Wafer Cooling During Ion Implantation

IP.com Disclosure Number: IPCOM000051765D
Original Publication Date: 1981-Mar-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 2 page(s) / 44K

Publishing Venue

IBM

Related People

Bayer, EH: AUTHOR [+3]

Abstract

The ion-implant arrangement described provides a cryo-cooled heatsink i close proximity to either the surface of a wafer or the wafer-back, keeping the temperature of the wafer within ""safe'' limits during ion bombardment. Since most of the heat transfer in vacuum is achieved by radiation, it is essential to provide a surface to which the heat can radiate, preferentially, and then remove the heat rapidly by cooling.

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Cryo Panel Heat Absorber to Enhance Wafer Cooling During Ion Implantation

The ion-implant arrangement described provides a cryo-cooled heatsink i close proximity to either the surface of a wafer or the wafer-back, keeping the temperature of the wafer within ""safe'' limits during ion bombardment. Since most of the heat transfer in vacuum is achieved by radiation, it is essential to provide a surface to which the heat can radiate, preferentially, and then remove the heat rapidly by cooling.

The arrangement utilizes a black body in close proximity (typically ~ 1 cm) to the wafers to be ion-implanted. The body contains cooling coils through which water, FREON* or liquid nitrogen, for example, may be circulated to remove the heat and keep the surface cool.

A representative application of the principle employed here is shown in the attached figure. Wafers to be ion-implanted are suspended on disc 1 within ion- implant chamber 2. Openings 3 are provided in disc 1 to accommodate wafers 5. In line with the backs of wafers 5 in openings 6 through which radiation can occur, a black surface 7 is provided close to the disc. This surface is cooled by pumping water, or the like, through cooling passages 9 provided under the surface.

Normally, when a silicon wafer is subjected to an ion beam of several hundred watts of power, the temperature of the wafer rises to several hundred degrees C within a few minutes, thereby causing the wafer to deform or warp, rendering it unsuitable...