Method and apparatus to measure threshold shifting of a MOSFET device and voltage difference between nodes
First Claim
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1. A circuit for measuring threshold-voltage (Vt) shifts of a MOSFET device, comprising:
- a Vt reference sensor;
a comparator for receiving inputs from said Vt reference sensor and a Vt target sensor, said comparator having an output coupled to a voltage measuring device, whereinsaid Vt reference sensor comprises a reference voltage generator connected to a reference voltage sensor; and
a digitally programmable current source (IDAC) connected to an input of said reference voltage sensor.
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Abstract
An on-chip circuit to quantitatively measure threshold voltage shifts of a MOSFET. The circuit includes a programmable Vt reference sensor; a programmable Vt monitoring sensor; and a comparator for receiving inputs from the reference and monitoring sensors providing an output flag signal. The shifting of the MOSFET device voltage threshold monitors process variations, geometry sensitivity, plasma damage, stress, and hot carriers and other device damages. The same circuit also measures voltage differences between any two nodes in an integrated circuit chip or wafer.
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Citations
14 Claims
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1. A circuit for measuring threshold-voltage (Vt) shifts of a MOSFET device, comprising:
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a Vt reference sensor; a comparator for receiving inputs from said Vt reference sensor and a Vt target sensor, said comparator having an output coupled to a voltage measuring device, wherein said Vt reference sensor comprises a reference voltage generator connected to a reference voltage sensor; and a digitally programmable current source (IDAC) connected to an input of said reference voltage sensor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. An on-chip circuit for measuring threshold voltage (Vt) shifts of a MOSFET device, comprising:
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a Vt reference sensor; a plurality of Vt target sensors, each of said plurality of Vt target sensors having a target voltage generator and a target voltage sensing unit, and having their respective output connected to a multiplexer; and a comparator for receiving inputs from said Vt reference sensor and an output of said multiplexer, said comparator having an output coupled to a voltage measuring device.
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12. A method of measuring threshold voltage (Vt) shifts of a MOSFET device, comprising steps of:
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sensing a Vt reference voltage; sensing a plurality of Vt target voltages using a plurality of Vt target sensors, each of which having a target voltage generator and a target voltage sensor, and having their respective output connected to a multiplexer; comparing said sensed Vt reference voltage against a voltage at an output of said multiplexer, said multiplexer having an output coupled to a voltage measuring device; measuring a reference voltage generated by a reference voltage generator upon sensing a reference voltage generated by a reference voltage sensor; and programming a current source (IDAC) connected to an input of said reference voltage sensor. - View Dependent Claims (13, 14)
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Specification