Method for fabricating MNOS structures utilizing hydrogen ion implantation
First Claim
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1. An improved method for reducing the density of electronic trapping states and fixed insulator charge in the oxide layer of an MNOS structure of the type having a gate, said oxide layer including a gate region disposed below the gate, and a field region surrounding said gate region, said method comprising the steps of:
- implanting hydrogen ions in the MNOS structure such that the gate blocks the hydrogen implant from the gate region of the oxide layer, the field region of the oxide layer of the MNOS structure thereby being implanted with hydrogen ions; and
annealing the MNOS structure to cause said implanted hydrogen ions in the field region of the oxide layer to diffuse laterally into the gate region of the oxide layer and to chemically react at the Si--SiO2 interface to reduce the density of electronic trapping states and fixed oxide charge.
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Abstract
An improved method for reducing the density of electronic trapping states and fixed insulator charge in the thin oxide layer of an MNOS structure. The method includes the steps of implanting hydrogen ions in field region of the oxide layer and annealing the MNOS structure at 400° C. to cause the ions to diffuse laterally into the gate region of the oxide layer.
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9 Claims
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1. An improved method for reducing the density of electronic trapping states and fixed insulator charge in the oxide layer of an MNOS structure of the type having a gate, said oxide layer including a gate region disposed below the gate, and a field region surrounding said gate region, said method comprising the steps of:
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implanting hydrogen ions in the MNOS structure such that the gate blocks the hydrogen implant from the gate region of the oxide layer, the field region of the oxide layer of the MNOS structure thereby being implanted with hydrogen ions; and annealing the MNOS structure to cause said implanted hydrogen ions in the field region of the oxide layer to diffuse laterally into the gate region of the oxide layer and to chemically react at the Si--SiO2 interface to reduce the density of electronic trapping states and fixed oxide charge. - View Dependent Claims (2, 3, 4, 5)
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6. An improved method for reducing the density of electronic trapping states and fixed insulator charge in the oxide layer of an MNOS structure of the type with a continuous nitride layer disposed over the oxide layer, said nitride layer having a gate formed on its upper surface, and wherein said oxide layer includes a gate region disposed below the gate, and a field region surrounding said gate region, said method including the steps of:
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implanting the oxide layer with hydrogen ions such that the gate blocks the hydrogen implant from the gate region of the oxide layer; adjusting the energy of said ions to cause the peak of the implanted hydrogen ions to be positioned in the oxide layer; terminating said step of implanting when the fluence of hydrogen ions in the oxide layer is from about 1015 ions/cm2 to 1016 ions/cm2 ; heating the MNOS structure to about 400°
C. for about 1 to about 2 hours. - View Dependent Claims (7, 8)
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9. An improved method for reducing the density of electronic trapping states and fixed insulator charge in the oxide layer of an MNOS structure of the type having a gate, said oxide layer including a gate region disposed below the gate, and a field region surrounding said gate region, said method comprising the steps of:
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implanting hydrogen ions solely in the field region of the oxide layer of the MNOS structure, such that no hydrogen ions are implanted in the gate region; and annealing the MNOS structure to cause said implanted hydrogen ions in the field region of the oxide layer to diffuse laterally into the gate region of the oxide layer and to chemically react at the Si--SiO2 interface to reduce the density of electronic trapping states and fixed oxide charge.
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