Abstract The present invention relates to a processing apparatus for growing and annealing a silicon dioxide insulator layer to obtain a mobile positive ion free silicon dioxide insulator layer. A mobile positive ion free silicon dioxide insulator layer is required in order to make a stable insulated gate field effect transistor. The processing apparatus comprises a non-oxidizing, high-melting-point platinum metal film coated quartz furnace tube, potential means for placing a positive potential upon the platinum metal film coating of the platinum metal film coated quartz furnace tube to repel mobile ions therefrom, heater means for heating the interior of the quartz furnace tube, and gas means for passing oxygen gas through the platinum metal film coated quartz furnace tube. A silicon wafer may be oxidized in said processing apparatus to form a relatively mobile positive ion free silicon dioxide insulator layer of an insulated gate field effect transistor upon the silicon wafer. The silicon dioxide insulator layer is relatively uncontaminated by mobile positive ions which exist to the outside of the platinum metal film coated quartz furnace tube. A silicon wafer which previously has been coated by a silicon dioxide insulator layer may be processed to remove mobile ions within the silicon dioxide insulator layer. Mobile positive ions are repelled by the positive potential applied to the platinum metal film away from the outside of the quartz furnace tube, and mobile positive ions of the silicon dioxide insulator layer within the platinum metal film coated quartz tube are removed by the flowing oxygen gas due to the low vapor pressure of the mobile positive ions.
Apparatus for annealing and reducing the concentration of mobile positive ions in a silicon oxide insulator layer in a furnace tube to deplete the concentration of mobile positive ions, including positive sodium ions, comprising: a furnace tube having inner and outer wall surfaces; a thin non-oxidizing, high-melting-point film of material disposed on the inner wall surfaCe of the tube, the film of material being impervious to mobile positive ions and selected from the group consisting of platinum; rhodium; tantalum overcoated with silicon nitride; and titanium overcoated with silicon nitride; means for causing a gaseous material to flow through the furnace tube to anneal the silicon oxide insulator layer and to reduce the concentration of mobile positive ions therein; and heater means in close proximity to the furnace tube for raising the temperature within the interior of the furnace tube to an elevated temperature range sufficient to drive mobile positive ions out of the silicon dioxide insulator layer.
Claim 2
Dependent Claim
184 words
Apparatus for annealing a silicon oxide insulator layer to deplete the concentration of mobile positive ions, including mobile positive sodium ions, in the silicon oxide insulator layer, comprising: a furnace tube having inner and outer wall surfaces; a thin non-oxidizing, high-melting-point film of material disposed on the inner wall surface of the tube, the film of material being impervious to mobile positive ions and selected from the group consisting of platinum; rhodium; tantalum overcoated with silicon nitride; and titanium overcoated with silicon nitride; means for applying a positive potential to the film for further hindering mobile positive ions from entering the interior of the furnace tube from the wall of the tube; means connected to the furnace tube for causing a gaseous material to flow through the tube to anneal the silicon oxide insulator layer and to deplete the concentration of mobile positive ions therein; and heating means acting in conjunction with the furnace tube for raising the temperature within the interior of the furnace tube to an elevated temperature range sufficient to drive mobile positive ions out of the silicon dioxide insulator layer.
Claim 3
Dependent Claim
172 words
Apparatus for oxidizing silicon semiconductor material in a mobile-positive-ion-free environment to form a silicon dioxide insulator layer thereon which is substantially free of mobile positive ions, comprising: a furnace tube having inner and outer wall surfaces; a thin non-oxidizing, high-melting-point film of material disposed on the inner wall surface of the tube, the film being impervious to mobile positive ions and selected from the group consisting of platinum; rhodium; tantalum overcoated with silicon nitride; and titanium overcoated with silicon nitride; means for applying a positive potential to the film for further hindering mobile positive ions from entering the interior of the furnace tube; means for introducing a gaseous material into the furnace tube to oxidize the semiconductor material and to flush the interior of the furnace tube of mobile positive ions; and heater means in close proximity to the furnace tube for raising the temperature within the interior of the furnace tube to an elevated temperature range sufficient to increase the kinetic energy of any mobile positive ions in the furnace tube.