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Recessed Oxide Isolation Process

IP.com Disclosure Number: IPCOM000088845D
Original Publication Date: 1977-Aug-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 2 page(s) / 73K

Publishing Venue

IBM

Related People

Beyer, KD: AUTHOR [+3]

Abstract

Recessed oxide isolation (ROI) is an established technology in today's semiconductor field. One problem with this technology is the so-called "bird's beak" effect. This effect leads to masking and diffusion problems which result in yield losses. A method for eliminating the "bird's beak" effect, thus improving yields and device performance and device packing density, is described.

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Recessed Oxide Isolation Process

Recessed oxide isolation (ROI) is an established technology in today's semiconductor field. One problem with this technology is the so-called "bird's beak" effect. This effect leads to masking and diffusion problems which result in yield losses. A method for eliminating the "bird's beak" effect, thus improving yields and device performance and device packing density, is described.

Fig. 1 shows a structure that results from standard processing through epitaxial layer 5 growth upon substrate 6. The subcollector 7 and isolation diffusions 8 are shown. An implant is utilized to produce a highly disordered silicon layer 9. A typical implant can be argon at 100 KeV energy with a dose of 1 x 10/16//cm/2/. Other ion species and implant conditions can be utilized depending on the specific structure being processed. A screen of silicon dioxide of about 500Angstroms in thickness can be utilized with the implant process if necessary.

If a screen silicon dioxide is used, it is removed prior to the Si(3)N(4) layer 10 and pyrolytic SiO(2) layer 11 deposition. Then layers 10, 11 are etched by conventional photolithography techniques to produce the Fig. 2 structure. The silicon dioxide layer 11 is then removed by conventional etching. An alternate process would be to implant through the Si(3)N(4)/SiO(2) layers 10, 11 to form the damage layer.

The regions which will ultimatly be the ROI regions are given a silicon etch, with the resultant structure...