Pitcher-shaped active area for field effect transistor and method of forming same
First Claim
1. A method of forming a pitcher-shaped active area structure for a field effect transistor (FET), the method comprising the steps of:
- forming divots into top portions of side walls of at least two shallow trench insulator (STI) structures formed into a substrate, wherein the STI structures comprise insulation and isolate a FET and define an active area structure, wherein the divots define recesses below a top surface of the substrate and below a top surface of the insulation, and wherein the recesses have boundaries formed by the top portions of the side walls and by exterior surfaces of the insulation; and
migrating substrate material into at least portions of the divots, thereby forming a widened top portion of the active area structure with a larger width than a bottom portion of the active area structure.
5 Assignments
0 Petitions
Accused Products
Abstract
An improved pitcher-shaped active area for a field effect transistor that, for a given gate length, achieves an increase in transistor on-current, a decrease in transistor serial resistance, and a decrease in contact resistance. The pitcher-shaped active area structure includes at least two shallow trench insulator (STI) structures formed into a substrate that defines an active area structure, which includes a widened top portion with a larger width than a bottom portion. An improved fabrication method for forming the improved pitcher-shaped active area is also described that implements a step to form STI structure divots followed by a step to migrate substrate material into at least portions of the divots, thereby forming a widened top portion of the active area structure. The fabrication method of present invention forms the pitcher-shaped active area without the use of lithography, and therefore, is not limited by the smallest ground rules of lithography tooling.
54 Citations
12 Claims
-
1. A method of forming a pitcher-shaped active area structure for a field effect transistor (FET), the method comprising the steps of:
-
forming divots into top portions of side walls of at least two shallow trench insulator (STI) structures formed into a substrate, wherein the STI structures comprise insulation and isolate a FET and define an active area structure, wherein the divots define recesses below a top surface of the substrate and below a top surface of the insulation, and wherein the recesses have boundaries formed by the top portions of the side walls and by exterior surfaces of the insulation; and
migrating substrate material into at least portions of the divots, thereby forming a widened top portion of the active area structure with a larger width than a bottom portion of the active area structure. - View Dependent Claims (2, 3, 4)
-
-
5. A method of forming a pitcher-shaped active area structure for a field effect transistor (FET), the method comprising:
-
implementing an etch to remove a pad oxide layer formed on a substrate and portions of an STI oxide fill and STI liner oxide that form top portions of sidewalls of at least two shallow trench insulator (STI) structures that isolate a FET and define an active area structure, thereby forming divots in the top portions of the sidewalls of the at least two STI structures, wherein the etch is selected from the group consisting of a wet etch and a plasma etch, wherein the STI structures comprise insulation, wherein the divots define recesses below a top surface of the substrate and below a top surface of the insulation, and wherein the recesses have boundaries formed by the top portions of the side walls and by exterior surfaces of the insulation; and
implementing a hydrogen annealing technique to migrate substrate material into at least portions of the divots, thereby forming a widened top portion of the active area structure with a larger width than a bottom portion of the active area structure. - View Dependent Claims (6, 7, 8, 9, 10, 11, 12)
-
Specification