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Chromium Reflector for Planar Metal Sputterers

IP.com Disclosure Number: IPCOM000034520D
Original Publication Date: 1989-Mar-01
Included in the Prior Art Database: 2005-Jan-27
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Chaloux, PN: AUTHOR [+3]

Abstract

In order to produce planar sputtered AlCu films capable of filling high aspect ratio holes, experiments have shown that a high wafer temperature (480 - 580oC) is necessary. In the absence of backside heating, maintaining and controlling the required high process temperature of the wafer is a critical control parameter. Planarized sputtered aluminum films allow filling of high aspect ratio vertical walled vias. These planar aluminum films require uniformly high temperatures (480 - 580oC) temperatures to reach the energy state at which planarization is possible. This is difficult to achieve in most sputtering systems because of heat control problems.

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Chromium Reflector for Planar Metal Sputterers

In order to produce planar sputtered AlCu films capable of filling high aspect ratio holes, experiments have shown that a high wafer temperature (480 - 580oC) is necessary. In the absence of backside heating, maintaining and controlling the required high process temperature of the wafer is a critical control parameter. Planarized sputtered aluminum films allow filling of high aspect ratio vertical walled vias. These planar aluminum films require uniformly high temperatures (480 - 580oC) temperatures to reach the energy state at which planarization is possible. This is difficult to achieve in most sputtering systems because of heat control problems. In these systems, the initial temperature needed to achieve planarization can be generated with a heater or etch station prior to metal deposition, but the heat loss during transport erodes the process window. The heat loss is primarily radiant. Aluminum foil reflectors reduce heat loss, but they are inadequate because they outgas, are difficult to handle, are easily bent (which changes their reflectivity), and, if used incorrectly, can short out the system. Use of a chromium-coated wafer (or similar temporary structure) behind the product wafer provides a heat resistant mirror to reflect radiated heat back to the wafer. Frontside heat loss is controlled by the deposited aluminum which acts as a mirror also, thus trapping most of the heat in the wafer. These structures wil...