Active solid-state devices (e.g. – transistors – solid-state diode – Field effect device – Having insulated electrode
Reexamination Certificate
2006-03-14
2006-03-14
Cao, Phat X. (Department: 2814)
Active solid-state devices (e.g., transistors, solid-state diode
Field effect device
Having insulated electrode
C257S391000
Reexamination Certificate
active
07012310
ABSTRACT:
A array of multi-bit Read Only Memory (ROM) cells is in a semiconductor substrate of a first conductivity type with a first concentration. Each ROM cell has a first and second regions of a second conductivity type spaced apart from one another in the substrate. A channel is between the first and second regions. The channel has three portions, a first portion, a second portion and a third portion. A gate is spaced apart and is insulated from at least the second portion of the channel. Each ROM cell has one of a plurality of N possible states, where N is greater than 2. The state of each ROM cell is determined by the existence or absence of extensions or halos that are formed in the first portion of the channel and adjacent to the first region and/or in the third portion of the channel adjacent to the second region. These extensions and halos are formed at the same time that extensions or halos are formed in MOS transistors in other parts of the integrated circuit device, thereby reducing cost. The array of ROM cells are arranged in a plurality of rows and columns, with ROM cells in the same row having their gates connected together. ROM cells in the same column have the first regions connected in a common first column, and second regions connected in common second column. Finally, ROM cells in adjacent columns to one side share a common first column, and cells in adjacent columns to another side share a common second column.
REFERENCES:
patent: 3914855 (1975-10-01), Cheney et al.
patent: 4282646 (1981-08-01), Fortino et al.
patent: 4322823 (1982-03-01), Pricer et al.
patent: 5796149 (1998-08-01), Sugaya et al.
patent: 6861714 (2005-03-01), Lee et al.
Chen Bomy
Lee Dana
Cao Phat X.
DLA Piper Rudnick Gray Cary US LLP
Silcon Storage Technology, Inc.
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