Browse Prior Art Database

Method to Produce Sizes in Openings in Photo Images Smaller Than Lithographic Minimum Size

IP.com Disclosure Number: IPCOM000061580D
Original Publication Date: 1986-Aug-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 2 page(s) / 23K

Publishing Venue

IBM

Related People

Noble, WP: AUTHOR

Abstract

By means of the addition of a well-controlled thickness of material to sidewalls on a minimum lithographic size opening, well-controlled smaller openings are formed. An example of a useful application is described wherein recessed oxide (ROX) pad openings are formed which are, e.g., 0.4 micron smaller than the minimum achievable lithographic image size. The material, e.g., polycrystalline silicon (Poly-Si), is added to sidewalls of openings by first depositing the Poly-Si by a conformal deposition process, e.g., chemical vapor deposition (CVD), and then using an anisotropic etching process, e.g., reactive ion etching (RIE), to remove the CVD Poly-Si from regions coplanar to the substrate. Referring to the figure, conventional processing is used to create pad oxide (SiO2) 4 and pad nitride (Si3N4) 6 on a silicon substrate 2.

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Method to Produce Sizes in Openings in Photo Images Smaller Than Lithographic Minimum Size

By means of the addition of a well-controlled thickness of material to sidewalls on a minimum lithographic size opening, well-controlled smaller openings are formed. An example of a useful application is described wherein recessed oxide (ROX) pad openings are formed which are, e.g., 0.4 micron smaller than the minimum achievable lithographic image size. The material, e.g., polycrystalline silicon (Poly-Si), is added to sidewalls of openings by first depositing the Poly-Si by a conformal deposition process, e.g., chemical vapor deposition (CVD), and then using an anisotropic etching process, e.g., reactive ion etching (RIE), to remove the CVD Poly-Si from regions coplanar to the substrate. Referring to the figure, conventional processing is used to create pad oxide (SiO2) 4 and pad nitride (Si3N4) 6 on a silicon substrate 2. Next, a layer of Poly-Si 8 is deposited to a thickness t suitable to act as a mask in a boron field ion implantation process (t>0.3 micron), photo-patterned and etched to form holes of minimum lithographic size m. A layer 10 of Poly-Si is conformally deposited by CVD to a thickness of
0.2 micron (um). This layer 10 is then removed from all regions coplanar with the substrate 2 by RIE, leaving edge spacers of 0.2 um thickness on sidewalls of openings originally m wide, thus producing openings 0.4 micron smaller than minimum lithographic size m. The field...