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US 11,114,352 B2Granted
Process monitor circuitry with measurement capability
AssigneeBirad—Research & Development Company Ltd.
InventorsJoseph Shor, Liron Lisha
Life of this patent
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Abstract
A process monitor circuitry is described that can measure the electron mobility (μ), oxide capacitance (Cox) and threshold voltage (Vth) of an integrated circuit.
Claims20
A circuit comprising:
- a process monitor circuit comprising a current source, at least one composite circuit element and an analog-to-digital converter (ADC), wherein current from said current source is dropped across said at least one composite circuit element generating a voltage which is measured as a measurement by said ADC, and said measurement yields information about at least one process dependent parameter,
- wherein the current source comprises a switched capacitor current source that comprises a flying capacitor Cfl coupled to non-overlapping switches, which receive anti-phase frequency inputs from clocks Φ1 and Φ2, and said flying capacitor is switched between voltages Vfb and Vss, such that its current is:
- I=CflyVfbf
- where f represents frequency;
- and said flying capacitor comprises an MOS device and said switched capacitor current is mirrored or driven across said composite device.
2 more elements
A circuit comprising:
- a process monitor circuit comprising a current source, at least one composite circuit element and an analog-to-digital converter (ADC), wherein current from said current source is dropped across said at least one composite circuit element generating a voltage which is measured as a measurement by said ADC, and said measurement yields information about at least one process dependent parameter, wherein said composite circuit element comprises at least one MOS device and said at least one process dependent parameter is measured for either PMOS or NMOS transistors which are available in the process monitor circuit, and
- wherein said at least one MOS device comprises a stack of similar type MOS devices all having same gate connections, wherein there is a transistor whose drain is connected to all gates of the transistors in the stack, this drain being called a stack drain and this transistor being called a stack drain transistor, and said stack drain is coupled to said ADC so that said least one process dependent parameter comprises a threshold voltage or a product of electron mobility and oxide capacitance, wherein said stack comprises a series-connected transistor stack in which said similar type MOS devices are coupled drain to source.
Dependencies are inferred from the claim text.