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EP0447976A1 Expired / Lapsed EP ⏱️ 0.0 years remaining

Read-only semiconductor memory device

Assignee: Toshiba Corp
•
Filing: 1991-03-15
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Granted: —
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Expires: 2011-03-15
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Abstract

Abstract A source (13), a drain (14), and a channel (15) are formed in an element region of a semiconductor substrate (11). A gate electrode (16) is formed above the channel (15). An insulating oxide film (18) is deposited on the entire surface of the resultant structure. Contact holes (19) and (20) are formed to bring the source (13) and drain (14) of each memory cell transistor into contact with each other. A wiring layer of a first aluminum layer is formed on the insulating oxide film including inner portions of the contact holes (19) and (20). The wiring layer includes a wiring layer (21A) for connecting adjacent memory cell transistors and a wiring layer (21B) for short-circuiting the source (13) and drain (14) to operate a memory cell transistor in the same manner as a depletion type transistor does.

Inventors

  • 👤 Shinsuke C/O Intellectual Property Div. Takase
  • 👤 Yutaka C/O Intellectual Property Div. Tanaka
  • 👤 Hisashi C/O Intellectual Property Div. Hashimoto

Bibliographic Details

Application Number —
Jurisdiction EP
Data Source google_patents
Last Synchronized 2026-11-09 06:37
CPC Classifications
G; G11; G11C; G11C17/00; G11C17/08; G11C17/10; G11C17/12; G11C17/123; H; H10; H10B; H10B20/00

Claims Analysis

Total Claims: 6
Claim 1
Independent Claim 63 words
A read-only semiconductor memory device comprising: a memory cell group (30) including at least two series-connected memory cells each constituted of a MOS transistor (Q) having a source and a drain; and a first wiring layer (21B, 37A) for short-circuiting a source and a drain of a specific one of the memory cells of said memory cell group in accordance with program data.
Claim 2
Dependent Claim 30 words
The read-only semiconductor memory device according to claim 1, characterized in that said memory cells of said memory cell group are connected in series by a second wiring layer (21A).
Claim 3
Dependent Claim 25 words
The read-only semiconductor memory device according to claim 2, characterized in that said first and second wiring layers are formed of a metal wiring layer.
Claim 4
Dependent Claim 34 words
The read-only semiconductor memory device according to claim 1, characterized in that said memory cells are connected in series by forming sources and drains of two memory cells of a common diffusion layer (32).
Claim 5
Dependent Claim 28 words
The read-only semiconductor memory device according to claim 1, characterized in that each of said memory cells of said memory cell group includes an enhancement type MOS transistor.
Claim 6
Dependent Claim 93 words
A read-only semiconductor memory device characterized by further comprising: a semiconductor substrate (31) of a first conductivity type; a plurality of diffusion layers (32) of a second conductivity type, formed in said semiconductor substrate at predetermined intervals; a plurality of gate electrodes (34) each formed so as to extend over adjacent two diffusion layers; an insulating layer (35) formed on said plurality of gate electrodes; and a wiring layer (37A) formed of a metal wiring layer formed on said insulating layer, for connecting said adjacent two diffusion layers in accordance with program data.

References Cited (Backward Citations)

GB2102623A Cited

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