Monolithic integration of enhancement-mode and depletion-mode galium nitride high electron mobility transistors
AssigneeNational Research Council of Canada
InventorsElias Al Alam, Alireza Loghmany
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Abstract
A device and method of fabricating a device having depletion-mode and enhancement-mode high-electron-mobility transistors (HEMTs) on a single wafer are disclosed. The method of fabrication involves providing semiconductor layers capable of sustaining a two-dimensional electron sheet to enable electrical current to flow through the HEMT, forming a series of trenches and fins in the semiconductor layers over an active area of the semiconductor layers on which a gate contact terminal is to be set down, the fins of respective HEMTs having different widths resulting in different voltage thresholds for the respective depletion-mode HEMTs.
Claims15
A method of fabricating a wafer containing a plurality of high-electron-mobility transistors (HEMTs), the method comprising:
- providing semiconductor layers capable of sustaining a two-dimensional electron sheet to enable electrical current to flow through the HEMTs,
- wherein the semiconductor layers comprise a first layer of aluminum gallium nitride (AlGaN) and a second layer of gallium nitride (GaN),
- whereby the concentration of Al and thickness of AlGaN give rise to a characteristic threshold voltage;
- for a first one of said HEMTs:
- forming a series of first trenches and first fins in the semiconductor layers over a first active area of the semiconductor layers on which a first gate contact terminal of the first one of said HEMTs is to be set down,
- wherein the width of the first fins is chosen to shift the characteristic threshold voltage to a new threshold voltage;
- setting down the first gate contact terminal across the first fins;
- and
- setting down a first source contact terminal and a first drain contact terminal on either side of the first gate contact terminal outside of the first active area;
- and
- for a further one of said HEMTs:
- forming a series of further trenches and further fins in the semiconductor layers over a further active area of the semiconductor layers on which a further gate contact terminal of the HEMT is to be set down,
- wherein the width of the further fins is less than the width of the first fins to shift the characteristic threshold voltage below the new threshold voltage of the first one of said HEMTs;
- setting down a further gate contact terminal across the further series of fins;
- and
- setting down a further source contact terminal and a further drain contact terminal on either side of the further gate contact terminal outside of the further active area,
- wherein the width of each of the first fins is selected to increase the characteristic threshold voltage such that the first one of said HEMTs operates as a depletion mode HEMT, and
- wherein the width of the further fins is selected to decrease the characteristic threshold voltage to a voltage such that the further one of said HEMTs operates as an enhancement mode HEMT.
A device incorporating monolithic integration of E-mode and D-mode AlGaN/GaN high-electron-mobility transistors (HEMTs),
- comprising:
- semiconductor layers comprising a first layer of aluminum gallium nitride (AlGaN) and a second layer of gallium nitride (GaN),
- said layers being capable of sustaining a two-dimensional electron sheet to enable electrical current to flow,
- the semiconductor layers comprising a plurality of active areas on which gate contact terminals are to be set down,
- the active areas comprising a series of trenches and fins, the fins having different widths over each active area;
- a plurality of drain contact terminals adjacent respective ones of the active areas;
- a plurality of source contact terminals adjacent respective ones of the active areas;
- and
- a plurality of gate contact terminals set down across the fins of respective ones of the active areas,
- such that the device comprises a plurality of AlGaN/GaN high-electron-mobility transistors (HEMTs) having different threshold voltages, and
- wherein for a first one of said HEMTs the width of each of the fins is selected to increase the characteristic threshold voltage such that the first one of said HEMTs operates as a depletion mode HEMT, and
- wherein for a further one of said HEMTs the width of the fins is selected to decrease the characteristic threshold voltage to a voltage such that the further one of said HEMTs operates as an enhancement mode HEMT.
Dependencies are inferred from the claim text.