Browse Prior Art Database

FET Gate Structure for Nonvolatile N Channel Read Mostly Memory Device

IP.com Disclosure Number: IPCOM000084418D
Original Publication Date: 1975-Nov-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 2 page(s) / 42K

Publishing Venue

IBM

Related People

Bhattacharyya, A: AUTHOR [+3]

Abstract

The present gate structures for read-mostly memory field-effect transistor (FET) devices exhibit certain deficiencies, such as excessive volatility, switching voltages close to insulator breakdown, and long erase pulse duration.

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FET Gate Structure for Nonvolatile N Channel Read Mostly Memory Device

The present gate structures for read-mostly memory field-effect transistor (FET) devices exhibit certain deficiencies, such as excessive volatility, switching voltages close to insulator breakdown, and long erase pulse duration.

The following structure describes a structure believed to eliminate the aforesaid disadvantages. In the drawings, a typical FET structure is shown having source and drain diffusions labeled S and D. However, the gate structure shows a thin silicon oxide passivation layer 1 overlaid by a thin oxy-nitride layer; the stoichiometry varying in accordance with a refractive index 1.55 to 1.65, where the atomic composition at index 1.55 comprises 15 atomic percent nitrogen, 48 atomic percent oxygen, and the remainder silicon. The composition at an index of 1.65 is approximately 30 atomic percent nitrogen, 32 atomic percent oxygen, and the remainder silicon. These layers are designated as 2.

The first such layer in the structure is covered with a bulk insulator 3 such as Al(2)O(3) or Si(3)N(4) which, in turn, has superimposed thereon any metal gate 4 such as aluminum or Al-Cu or Au. The contact metal 5 may be of the same metal material. The field insulator 7 consists of a thin layer of Al(2)O(3) and a thick layer of pyro SiO deposited over a tunnel oxide, not shown.

The structure shown in Fig. 2 is believed to reduce the charge injection into the insulation layer. This structur...