James Li

A testing apparatus for determining the etch bias associated with a semiconductor-processing step includes a substrate, a first cathode finger with a first width on the substrate, a second cathode finger with a second width on the substrate, and a cathode large area on the substrate wherein the cathode large area has a third width W" and a length L" that are both substantially larger than either of the first and second widths.

A thin InGaAs contact layer is provided for the collector of a heterojunction bipolar transistor (HBT) above an InP sub-collector. The contact layer provides a low resistance contact mechanism and a high thermal conductivity path for removing device heat though the sub-collector, and also serves as an etch stop to protect the sub-collector during device fabrication. A portion of the sub-collector lateral to the remainder of the HBT is rendered electrically insulative, preferably by an ion… Show more

A thin InGaAs contact layer is provided for the collector of a heterojunction bipolar transistor (HBT) above an InP sub-collector. The contact layer provides a low resistance contact mechanism and a high thermal conductivity path for removing device heat though the sub-collector, and also serves as an etch stop to protect the sub-collector during device fabrication. A portion of the sub-collector lateral to the remainder of the HBT is rendered electrically insulative, preferably by an ion implant, to provide electrical isolation for the device and improve its planarity by avoiding etching through the sub-collector. Show less

A thin InGaAs contact layer is provided for the collector of a heterojunction bipolar transistor (HBT) above an InP sub-collector. The contact layer provides a low resistance contact mechanism and a high thermal conductivity path for removing device heat though the sub-collector, and also serves as an etch stop to protect the sub-collector during device fabrication. A portion of the sub-collector lateral to the remainder of the HBT is rendered electrically insulative, preferably by an ion… Show more

A thin InGaAs contact layer is provided for the collector of a heterojunction bipolar transistor (HBT) above an InP sub-collector. The contact layer provides a low resistance contact mechanism and a high thermal conductivity path for removing device heat though the sub-collector, and also serves as an etch stop to protect the sub-collector during device fabrication. A portion of the sub-collector lateral to the remainder of the HBT is rendered electrically insulative, preferably by an ion implant, to provide electrical isolation for the device and improve its planarity by avoiding etching through the sub-collector. Show less

Test probe pads are located lateral to, and spaced from, the emitter, base or collector region of a bipolar transistor, preferably on separate pedestals, and connected to their respective transistor regions by air bridges. The probe pads, transistor contacts and air bridges are preferably formed as common metallizations. In the case of an HBT, a gap in the subcollector below the air bridges insulates the test transistor from capacitor loading by the probe pads. The test transistors can be used… Show more

Test probe pads are located lateral to, and spaced from, the emitter, base or collector region of a bipolar transistor, preferably on separate pedestals, and connected to their respective transistor regions by air bridges. The probe pads, transistor contacts and air bridges are preferably formed as common metallizations. In the case of an HBT, a gap in the subcollector below the air bridges insulates the test transistor from capacitor loading by the probe pads. The test transistors can be used to characterize both themselves and functional circuit transistors fabricated with the same process on the same wafer by testing at an intermediate stage of manufacture, thus allowing wafers to be discarded without completing the manufacture if their transistors do not meet specifications. Show less

A method of measuring a width of an undoped or lightly doped polysilicon line is disclosed. The width measuring method includes generating carriers in the polysilicon line with an energy source; measuring a capacitance between the polysilicon line and a substrate separated from the polysilicon line by a dielectric layer; and determining a line width of said polysilicon line from the measured capacitance. The capacitance measurement includes connecting first and second probes to the polysilicon… Show more

A method of measuring a width of an undoped or lightly doped polysilicon line is disclosed. The width measuring method includes generating carriers in the polysilicon line with an energy source; measuring a capacitance between the polysilicon line and a substrate separated from the polysilicon line by a dielectric layer; and determining a line width of said polysilicon line from the measured capacitance. The capacitance measurement includes connecting first and second probes to the polysilicon line; connecting a third probe to the substrate; connecting a first terminal of a capacitance meter to the first and second probes; connecting a second terminal of the capacitance meter to the third probe; and applying a direct current bias across the first and second probes. A capacitor may be connected between the first and second probes. Further steps include, connecting a fourth probe to a conductor that supports the substrate; and connecting the fourth probe to the third probe. Show less

A method of measuring a width of an undoped or lightly doped polysilicon line is disclosed. The width measuring method includes generating carriers in the polysilicon line with an energy source; measuring a capacitance between the polysilicon line and a substrate separated from the polysilicon line by a dielectric layer; and determining a line width of the polysilicon line from the measured capacitance. The capacitance measurement includes connecting first and second probes to the polysilicon… Show more

A method of measuring a width of an undoped or lightly doped polysilicon line is disclosed. The width measuring method includes generating carriers in the polysilicon line with an energy source; measuring a capacitance between the polysilicon line and a substrate separated from the polysilicon line by a dielectric layer; and determining a line width of the polysilicon line from the measured capacitance. The capacitance measurement includes connecting first and second probes to the polysilicon line; connecting a third probe to the substrate; connecting a first terminal of a capacitance meter to the first and second probes; connecting a second terminal of the capacitance meter to the third probe; and applying a direct current bias across the first and second probes. A capacitor may be connected between the first and second probes. Further steps include, connecting a fourth probe to a conductor that supports the substrate; and connecting the fourth probe to the third probe. Show less