HVMOS reliability evaluation using bulk resistances as indices
First Claim
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1. A method comprising:
- determining a bulk resistance of a high-voltage PMOS (HVPMOS) device, wherein the determining the bulk resistance comprises;
measuring a plurality of source-to-bulk voltages of the HVPMOS device using a tester;
measuring a plurality of source currents of the HVPMOS device corresponding to the plurality of source-to-bulk voltages;
calculating a plurality of candidate bulk resistances from the plurality of source-to-bulk voltages and the plurality of source currents; and
selecting the bulk resistance from the plurality of candidate bulk resistances, with the bulk resistance being calculated from a source-to-bulk voltage in a pre-determined range, with the source-to-bulk voltage being one of the plurality of source-to-bulk voltages;
determining a reference bulk resistance comprising;
forming a plurality of reference sample HVPMOS devices;
determining bulk resistances of the plurality of reference sample HVPMOS devices; and
measuring current gains β
of the reference sample HVPMOS devices, wherein the reference bulk resistance is determined as a bulk resistance of one of the reference sample HVPMOS devices having a current gain β
equal to 1; and
comparing the bulk resistance with the reference bulk resistance, wherein the HVPMOS device with the bulk resistance greater than the reference bulk resistance is determined as not reliable, and the HVPMOS device with the bulk resistance smaller than the reference bulk resistance is determined as reliable.
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Abstract
A method of determining the reliability of a high-voltage PMOS (HVPMOS) device includes determining a bulk resistance of the HVPMOS device, and evaluating the reliability of the HVPMOS device based on the bulk resistance.
86 Citations
13 Claims
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1. A method comprising:
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determining a bulk resistance of a high-voltage PMOS (HVPMOS) device, wherein the determining the bulk resistance comprises; measuring a plurality of source-to-bulk voltages of the HVPMOS device using a tester; measuring a plurality of source currents of the HVPMOS device corresponding to the plurality of source-to-bulk voltages; calculating a plurality of candidate bulk resistances from the plurality of source-to-bulk voltages and the plurality of source currents; and selecting the bulk resistance from the plurality of candidate bulk resistances, with the bulk resistance being calculated from a source-to-bulk voltage in a pre-determined range, with the source-to-bulk voltage being one of the plurality of source-to-bulk voltages; determining a reference bulk resistance comprising; forming a plurality of reference sample HVPMOS devices; determining bulk resistances of the plurality of reference sample HVPMOS devices; and measuring current gains β
of the reference sample HVPMOS devices, wherein the reference bulk resistance is determined as a bulk resistance of one of the reference sample HVPMOS devices having a current gain β
equal to 1; andcomparing the bulk resistance with the reference bulk resistance, wherein the HVPMOS device with the bulk resistance greater than the reference bulk resistance is determined as not reliable, and the HVPMOS device with the bulk resistance smaller than the reference bulk resistance is determined as reliable. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method comprising:
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forming a plurality of sample high-voltage PMOS (HVPMOS) devices, wherein active-region-to-guard-ring spacings of the plurality of sample HVPMOS devices are different from each other, and the active-region-to-guard-ring spacings range from smaller than 2 μ
m to about 50 μ
m;finding among the plurality of sample HVPMOS devices a reference HVPMOS device by looking for the reference HVPMOS device having a current gain equal to about 1; determining a reference bulk resistance of the reference HVPMOS device, wherein a parasitic lateral bipolar junction transistor (BJT) of the reference HVPMOS device has a current gain equal to about 1, and wherein the lateral BJT comprises a source, a drain, and a well region of the reference HVPMOS device as an emitter, a collector, and a base, respectively, wherein the determining the reference bulk resistance comprises; forming a plurality of reference sample HVPMOS devices; determining bulk resistances of the plurality of reference sample HVPMOS devices; and measuring current gains β
of the plurality of reference sample HVPMOS devices, wherein the measuring the current gains β
comprises measuring source currents Is and bulk currents of the reference sample HVPMOS devices using a tester, wherein the reference bulk resistance is determined as a bulk resistance of one of the reference sample HVPMOS devices having a current gain β
equal to 1;finding bulk resistances of a plurality of HVPMOS devices on a chip; and comparing the bulk resistances with the reference bulk resistance, wherein; portions of the plurality of HVPMOS devices with bulk resistances greater than the reference bulk resistance are determined as not reliable; and portions of the plurality of HVPMOS devices with bulk resistances smaller than the reference bulk resistance are determined as reliable. - View Dependent Claims (8)
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9. A method comprising:
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forming a plurality of sample high-voltage PMOS (HVPMOS) devices having different active-region-to-guard-ring spacings; measuring source currents and bulk currents of the plurality of sample HVPMOS devices using testers; calculating a plurality of current gains from the source currents and bulk currents, wherein each of the plurality of current gains belongs to one of the plurality of sample HVPMOS devices; selecting from the plurality of current gains a reference current gain substantially equal to 1, wherein the reference current gain belongs to a reference HVPMOS device among the plurality of sample HVPMOS devices; and calculating a bulk resistance of the reference HVPMOS device, and selecting the bulk resistance of the reference HVPMOS device as a reference bulk resistance. - View Dependent Claims (10, 11, 12, 13)
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Specification