Abstract A method for fabricating radiation resistant MOS devices in which the metal sodium is removed after the oxide is grown by utilizing negative ion implantation. Low energy negative ions penetrate the SiO2 oxide layer depositing their negative charge on the surface of the layer and transferring enough energy to the oxide itself to release the bound sodium in the form of positive ions. The sodium ions drift to the oxide surface due the negative charges thereon. A thin uppermost portion of the SiO2 oxide layer contains both the implanted negative ion charges and the sodium ions. This uppermost layer is etched away using hydrofluoric acid. Removal of the sodium metal from the oxide layer significantly reduces the sensitivity of the MOS device to radiation.
A METHOD FOR ENABLING A METAL-OXIDE SEMICONDUCTOR DEVICE TO WITHSTAND THE EFFECTS OF A HIGH RADIATION ENVIRONMENT COMPRISING THE STEPS OF: A. INCREASING THE THICKNESS OF THE OXIDE LAYER, B. DIRECTING A BEAM OF NEGATIVE IONS INTO THE OXIDE LAYER, C. IMPLATING SAID BEAM OF NEGATIVE IONS ONLY IN THE UPPERMOST 1,000 ANGSTROMS OF SAID OXIDE LAYER AND THEN D. ALLOWING THE SODIUM ATOMS IN THE OXIDE LAYER TO ACCUMULATE ON THE SURFACE OF SAID LAYER AS SODIUM ATOMS AND IONS, AND E. REMOVING SAID SODIUM ATOMS AND IONS.
Claim 2
Independent Claim
89 words
A METHOD FOR ENABLING A METAL-OXIDE SEMICONDUCTOR DEVICE TO WITHSTAND THE EFFECTS OF A HIGH RADIATION ENVIRONMENT COMPRISING THE STEPS OF: A. INCREASING THE THICKNESS OF THE OXIDE LAYER, B. DIRECTING A BEAM OF NEGATIVE IONS INTO THE OXIDE LAYER, C. IMPLATING SAID BEAM OF NEGATIVE IONS ONLY IN THE UPPERMOST 1,000 ANGSTROMS OF SAID OXIDE LAYER AND THEN D. ALLOWING THE SODIUM ATOMS IN THE OXIDE LAYER TO ACCUMULATE ON THE SURFACE OF SAID LAYER AS SODIUM ATOMS AND IONS, AND E. REMOVING SAID SODIUM ATOMS AND IONS.
Claim 3
Dependent Claim
24 words
The invention according to claim 1 wherein said sodium atoms and ions are removed by etching away the uppermost portion of said oxide layer.
Claim 4
Dependent Claim
18 words
The invention according to claim 2 wherein said etching is performed by a diluted buffered hydrofluoric acid solution.
Claim 5
Dependent Claim
18 words
The invention according to claim 1 wherein said oxide layer is increased by at least 1,000 additional Angstroms.