Transistors with controllable threshold voltages, and various methods of making and operating same

• Main Authors: WRISTERS DERICK J, FUSELIER MARK B, WEI ANDY C
• Format: Patent
• Language: English
• Published: 07.10.2008
• Subjects: BASIC ELECTRIC ELEMENTS; ELECTRIC SOLID STATE DEVICES NOT OTHERWISE PROVIDED FOR; ELECTRICITY; SEMICONDUCTOR DEVICES

In one illustrative embodiment, the method comprises providing an SOI substrate comprised of an active layer, a buried insulation layer and a bulk substrate, the active layer being doped with a first type of dopant material, the bulk substrate having an inner well formed therein adjacent a surface of the bulk substrate and under the active layer, the inner well being doped with the first type of dopant material, forming a transistor above the SOI substrate in an area above the inner well and applying a voltage to the inner well to vary a threshold voltage of the transistor. In some embodiments, the method further comprises forming an NMOS transistor, wherein the active layer and the inner well are doped with a P-type dopant material. In other embodiments, the method further comprises forming a PMOS transistor, wherein the active layer and the inner well are doped with an N-type dopant material. In another illustrative embodiment, the method comprises providing a consumer product comprised of at least one integrated circuit product, the integrated circuit product being comprised of at least one transistor formed in an active layer of an SOI substrate, the SOI substrate further comprising an inner well formed adjacent a surface of a bulk substrate of the SOI substrate, the inner well being formed under the active layer, the active layer and the inner well being doped with a first type of dopant material, sensing an activity level of the integrated circuit product and applying a voltage of a magnitude and a polarity to the inner well of at least one transistor, the magnitude and polarity of the applied voltage being determined based upon the sensed activity level of the integrated circuit product.