Browse Prior Art Database

Making a One Device Memory Cell

IP.com Disclosure Number: IPCOM000085616D
Original Publication Date: 1976-May-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 2 page(s) / 30K

Publishing Venue

IBM

Related People

Vogl, NG: AUTHOR

Abstract

A one-device memory cell is made in a semiconductor substrate without the necessity of ion implantation through a dielectric sandwich, which implantation tends to introduce defects in dielectric materials.

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Making a One Device Memory Cell

A one-device memory cell is made in a semiconductor substrate without the necessity of ion implantation through a dielectric sandwich, which implantation tends to introduce defects in dielectric materials.

To make the storage cell illustrated in cross section in the figure, a semiconductor substrate 10 has grown a 380 angstrom layer of silicon dioxide 12 with a 200 angstrom layer of silicon nitride 14 deposited thereon. Parallel and spaced apart isolation strips, such as recessed oxide strips, not shown, are provided at the surface of substrate 10.

A 5,000 angstrom N-doped polysilicon layer is deposited over silicon nitride layer 14 and etched to form strips 16 and 18, orthogonal to the recessed oxide strips, which serve as the word line and field shield, respectively. Strips 16 and 18 are oxidized to form 1,000 angstrom insulation layers 20 and 22.

In order to form a source region 24 in substrate 12 for the one-device cell, a 500 angstrom pyrolytic oxide layer, not shown, is deposited and an appropriate mask is used to etch 500 angstroms of the pyrolytic oxide, 200 angstroms of silicon nitride and 380 angstroms of silicon dioxide between strips 16 and 18. An N/+/ diffusion is then introduced through the etched opening into region 24 and about a 500 angstrom silicon dioxide layer 26 is grown over region 24.

Another 5,000 angstrom N-doped polysilicon layer is deposited and appropriately etched to form storage plate 28 over silicon d...