Field effect transistor having a gate dielectric with variable thickness
AssigneeMotorola, Inc.
InventorsCarlos A. Mazure, Marius K. Orlowski
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Abstract
A field effect transistor, FET, (11) having a gate dielectric of varying thickness (14, 24) to improve device performance. The FET (11) is made on a substrate (10) and has a control electrode, or gate (16), and two current electrodes, or source and drain regions (28), which are separated by a channel region. The gate (16) is separated from the channel region by a gate dielectric. The gate dielectric has a centrally located first region that is of a first thickness (14) and a second region which is adjacent a perimeter of the first region that is of a second thickness (24). The second thickness (24) is made greater than the first thickness (14).
Claims5
A process for forming a field effect transistor having a gate dielectric with variable thickness, comprising the steps of:
- providing a semiconductor substrate;
- forming a dielectric overlying the substrate and having a first thickness;
- forming a control electrode on the dielectric with a first predetermined width;
- forming a non-oxidizing film of material around the control electrode;
- increasing the first thickness of the dielectric to a second thickness adjacent a perimeter of the control electrode;
- removing the non-oxidizing film of material from the control electrode after the second thickness of the dielectric has been formed;
- extending the first predetermined width of the control electrode by laterally enlarging the control electrode to a second predetermined width after the second thickness of the dielectric is formed so that the dielectric which is below the control electrode has a thickness in a central portion beneath the control electrode which is less than an outer perimeter portion beneath the control electrode;
- and
- forming first and second current electrodes in the semiconductor substrate to form a channel region underlying the control electrode.
Dependencies are inferred from the claim text.