US 5,859,460 AGranted

Tri-state read-only memory device and method for fabricating the same

AssigneeUnited Microelectronics Corp.

InventorsKuan-Cheng Su, Chen-Hui Chung, Yi-Chung Sheng

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Abstract

A tri-state read-only memory device and its fabrication method are disclosed herein. After a plurality of word lines are formed and spaced apart in parallel through patterning by a shielding layer, insulating blocks are formed to fill the trenches among the word lines. Then removing the shielding layer, sidewalls, of the insulating blocks are revealed, and spacers are formed on the sidewalls thereof. The spacers above the first state regions are removed to form the conductive width of the channel regions in three forms. By merely applying one code-implantation, the ROM device are coded into on of three states at the same time. In addition, the disposition of the insulating blocks by liquid-phase deposition prevents the misalignment that often occurs with the conventional method.

Claims3

Dependent claims

A tri-state read only memory device for storing first, second and third states, comprising:

a semiconductor substrate;
a plurality of bit lines spaced in parallel formed in said substrate;
a plurality of word lines spaced in parallel formed over said substrate, having a dielectric layer disposed therebetween;
a plurality of channel regions disposed between each of two of said bit lines and said word lines for storing said first, second, and third states, respectively, whereby said channel regions for storing said first state are all operated in an OFF-state, said channel region for storing said second state are operated in said OFF-state in a central portion, and the channel regions for storing said third state are operated in an ON-state,
wherein said word lines above said channel regions for storing said second state are provided with sidewalls spacers at opposite sides thereof.

2 more elements

Dependencies are inferred from the claim text.

Facts

Application: 08/839,497Filed 14 Apr 1997 · division
Priority: 19 Sep 1995
Granted: 12 Jan 1999
Term ends: Not estimatedThe source records don’t support an estimate.

Classification6 codes

H10B 20/383
Doping programmed, e.g. mask ROM: channel doping programmed
G11C 11/56
Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor: using storage elements…
G11C 11/5692
Using storage elements with more than two stable states represented by steps, e.g. of voltage, current, phase, frequency: read-only digital stores…
H10B 20/00
Read-only memory [rom] devices