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Structure & Fabrication of Self Aligned Bucket Brigade SABB

IP.com Disclosure Number: IPCOM000077044D
Original Publication Date: 1972-Jun-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 40K

Publishing Venue

IBM

Related People

Agusta, B: AUTHOR [+2]

Abstract

In order to achieve high density, good reproducibility and high yield in bucket-brigade devices which comprise serially interconnected field-effect transistors (FET's) with parallel capacitors, a self-aligning structure is necessary.

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Structure & Fabrication of Self Aligned Bucket Brigade SABB

In order to achieve high density, good reproducibility and high yield in bucket-brigade devices which comprise serially interconnected field-effect transistors (FET's) with parallel capacitors, a self-aligning structure is necessary.

Fabrication of such a self-aligned bucket-brigade device on an N-type substrate 10 can be accomplished through the following steps: following the initial oxidation of the substrate 10, the oxide layer 11 is etched to form a long shift register channel 12 and an FET region 13. After this etching of the oxide layer 11, a thin oxide layer 14 is regrown in the bed of the channel 12 and in the FET region 13. Subsequently, a thin layer of conducting material, such as, platinum, is deposited over the entire surface of the substrate. This conductive layer is subsequently reduced, either by chemical etching, back-sputtering or other conventional methods, to a series of island; 15a, 15b, 15c and 15d in the channel region 12; and, an island 15e overlying a portion of the FET region 13 where the gate is to be subsequently formed. Once these conductive islands have been formed, the thin oxide layer 14 is subsequently etched away, using the metallic islands 15a through 15e as a protective mask, so as to provide a series of openings in the oxide layer 14.

Once these openings are made, a P-type diffusion is made into the body 10 to form, in the FET region 13, a source 17, a drain 18; and, i...