Abstract: A method and apparatus 10 for detecting the height of non-flat and transparent substrates using one or more reflectors 30 patterned on the surface of the substrate 40 and adjusting the position of the substrate in its holder based on measurement of the height of the reflectors in comparison to a calibration marker 60 on the holder and using appropriate spacers 50 with appropriate thickness to adjust the placement of the substrate at various locations to place the greatest portion of the substrate in an optimal focal range of the lithography system.

Abstract: A method of fabricating a T-gate HEMT with a club extension comprising the steps of: providing a substrate; providing a bi-layer resist on the substrate; exposing an area of the bi-layer resist to electron beam lithography where the area corresponds to a T-gate opening; exposing an area of the bi-layer resist to electron beam lithography where the area corresponds to the shape of the club extension wherein the area corresponding to the club extension is approximately 1 micron to an ohmic source side of a T-gate and approximately 0.5 microns forward from a front of the T-gate; developing out the bi-layer resist in the exposed area that corresponds to the T-gate opening; developing out the bi-layer resist in the exposed area that corresponds to the club extension; and forming the T-gate and club extension through a metallization process.

Abstract: A method of fabricating a T-gate HEMT with a club extension comprising the steps of: providing a substrate; providing a bi-layer resist on the substrate; exposing an area of the bi-layer resist to electron beam lithography where the area corresponds to a T-gate opening; exposing an area of the bi-layer resist to electron beam lithography where the area corresponds to the shape of the club extension wherein the area corresponding to the club extension is approximately 1 micron to an ohmic source side of a T-gate and approximately 0.5 microns forward from a front of the T-gate; developing out the bi-layer resist in the exposed area that corresponds to the T-gate opening; developing out the bi-layer resist in the exposed area that corresponds to the club extension; and forming the T-gate and club extension through a metallization process.

Abstract: A method and apparatus 10 for detecting the height of non-flat and transparent substrates using one or more reflectors 30 patterned on the surface of the substrate 40 and adjusting the position of the substrate in its holder based on measurement of the height of the reflectors in comparison to a calibration marker 60 on the holder and using appropriate spacers 50 with appropriate thickness to adjust the placement of the substrate at various locations to place the greatest portion of the substrate in an optimal focal range of the lithography system.