Active solid-state devices (e.g. – transistors – solid-state diode – Non-single crystal – or recrystallized – semiconductor... – Amorphous semiconductor material
Reexamination Certificate
2005-03-15
2005-03-15
Quach, T. N. (Department: 2814)
Active solid-state devices (e.g., transistors, solid-state diode
Non-single crystal, or recrystallized, semiconductor...
Amorphous semiconductor material
C257S288000, C257S347000, C257S392000
Reexamination Certificate
active
06867430
ABSTRACT:
Provided is a substrate identification circuit that generates a numeric value, whose duplication is difficult and which is proper to a substrate, at low cost and a semiconductor device having such a substrate identification circuit. A substrate identification circuit304is produced by utilizing variations in characteristics among TFTs formed on a substrate having an insulating surface. The substrate identification circuit304includes a plurality of proper bit generating circuits, each of which is constructed from a plurality of TFTs and outputs a one-bit random number based on variations in characteristics among the plurality of TFTs. The substrate identification circuit generates a numeric value proper to the substrate using the one-bit random number. The substrate identification circuit may include a circuit that makes a judgment by comparing the numeric value proper to the substrate with an identification number inputted from the outside.
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Kato Kiyoshi
Yamazaki Shunpei
Costellia Jeffrey L.
Nixon & Peabody LLP
Quach T. N.
Semiconductor Energy Laboratory Co,. Ltd.
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