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Confined Laser Heating and the Formation of Bird's Beak-Free Recessed Oxide Isolation

IP.com Disclosure Number: IPCOM000053105D
Original Publication Date: 1981-Aug-01
Included in the Prior Art Database: 2005-Feb-12
Document File: 2 page(s) / 47K

Publishing Venue

IBM

Related People

Chu, WK: AUTHOR [+3]

Abstract

In order to improve IC packing density and performance, methods of forming "bird's beak"-free recessed oxide isolation (ROI) have long been sought. A laser reflective masking pattern is herein used to confine laser heating to areas where ROI regions are formed. ROI formed by this method is free of or nearly free of the unwanted "bird's beak" structure. The method is as follows: 1. A thin layer 10 of thermal silicon dioxide is first grown on the silicon substrate 11. The layer 10 is then coated with a layer 12 of polyimide, other suitable organic or dielectric film of a desired thickness. A heat treatment may be carried out to increase the layer's thermal stability and surface smoothness. 2.

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Confined Laser Heating and the Formation of Bird's Beak-Free Recessed Oxide Isolation

In order to improve IC packing density and performance, methods of forming "bird's beak"-free recessed oxide isolation (ROI) have long been sought. A laser reflective masking pattern is herein used to confine laser heating to areas where ROI regions are formed. ROI formed by this method is free of or nearly free of the unwanted "bird's beak" structure. The method is as follows: 1. A thin layer 10 of thermal silicon dioxide is first grown on the silicon substrate 11. The layer 10 is then coated with a layer 12 of polyimide, other suitable organic or dielectric film of a desired thickness. A heat treatment may be carried out to increase the layer's thermal stability and surface smoothness. 2. A layer 14 of optically highly reflective metal, for example, aluminum, noble or near noble metal, is deposited forming a metal-polyimide-SiO(2) overlay structure on the silicon substrate, as shown in Fig. 1. 3. Using the lithographic method, desired device patterns are etched into the metal-polyimide-SiO overlay structure, exposing areas where ROIs are to be formed, as seen in Fig. 3. 4. The structure is then scanned or blanket illuminated by a laser beam in the presence of oxygen and/or steam. The laser beam heats up the exposed silicon areas to an extremely high temperature, resulting in rapid silicon dioxide growth in these areas. On the other hand, by virtue of the laser reflective natur...