MOSFET test structure for capacitance-voltage measurements
AssigneeAdvanced Micro Devices, Inc.
InventorsKhaled Z. Ahmed, Nguyen D. Bui, Effiong Ibok, John R. Hauser
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Abstract
An apparatus and method used in extracting polysilicon gate doping from C−V analysis in strong inversion, especially for ultrathin gate oxides. For sub-20-angstrom oxide MOS devices, transistors with channel lengths less than about 10 μm are connected in parallel to avoid an extrinsic capacitance roll-off in strong inversion. The upper limit of the channel length is estimated using a transmission-line-model of the terminal capacitance, which accounts for the non-negligible gate tunneling current and finite channel resistance.
Claims12
A MOSFET test structure, consisting of:
- a first MOSFET having a channel length less than 10 micrometers;
- a second MOSFET having a channel length less than 10 micrometers,
- wherein the first and second MOSFETS are connected in parallel, and
- wherein capacitance/voltage characteristics are capable of being measured from the MOSFET test structure by using a transmission line model of the first and second MOSFETs that accounts for tunneling currents and channel size.
A MOSFET test structure method, comprising:
- modeling a first MOSFET having a channel length less than 10 micrometers by utilizing a transmission line model of the first MOSFET transistor that accounts for tunneling currents and channel size;
- modeling a second MOSFET having a channel length less than 10 micrometers by utilizing a transmission line model of the second MOSFET transistor that accounts for tunneling currents and channel size, and
- connecting the first and second MOSFETS in parallel,
- wherein at least one device parameter of a thin-oxide-MOSFET is capable of being extracted utilizing the MOSFET test structure.
A method for determining a doping amount for one or more polysilicon gates in a semiconductor device, comprising:
- providing a test circuit having two or more transistors coupled in parallel, wherein a channel length of each transistor is less than or equal to a threshold channel length, the threshold channel length being equal to or less than 10 micrometers,
- determining capacitance/voltage characteristics of said test circuit;
- and
- determining a doping amount of a polysilicon gate based on said capacitance/voltage characteristics,
- wherein said step of determining said threshold channel length comprises simulating a model circuit, and
- wherein said step of simulating said model circuit utilizes a transmission line model of a MOSFET transistor that accounts for tunneling currents and channel size.
Dependencies are inferred from the claim text.