Abstract A surface barrier diode, also known as a Schottky diode, is disclosed having a hypersensitive voltage variable capacitance. The surface barrier diode structure comprises a silicon wafer of n conductivity having an N-type epitaxial layer which is oxidized on its outer surface to form a silicon oxide layer overlaying the epitaxial n-region of the wafer. The silicon oxide coating is relatively thin, as of less than 5000 A., and is formed relatively quickly i.e., in less than 20 minutes at a temperature within the range of 1150* C. to 1250* C. in order to produce a hypersensitive n impurity accumulation layer immediately adjacent to and underlying the oxide coating. A hole is then opened through the silicon layer and a metal electrode, as of chromium, is deposited directly upon the hypersensitive n region to form the rectifying junction of the diode. The surface barrier diode (Schottky diode) exhibits a hypersensitive voltage variable capacitance effect where ''''hypersensitive voltage variable capacitance'''' means that the capacitance is approximately inversely proportional to the first power of the applied voltage as contrasted with normal voltage variable capacitance effects in PN junction devices wherein the capacitance is approximately inversely proportional to the onehalf or one-third power of the applied voltage.
In a surface barrier diode exhibiting a hypersensitive voltage variable capacitance effect comprising, a wafer of N-type silicon semiconductor material, a layer of metal deposited in surface barrier relation on one surface of said silicon wafer to form a rectifying junction with said silicon wafer, means forming a pair of electrodes formed on the diode for applying an electrical potential across the rectifying junction of the diode, THE IMPROVEMENT COMPRISING, a hypersensitive n region disposed in said silicon wafer immediately adjacent to and underlying said metal layer, said n region having a lower resistivity than said N-type silicon and having a thickness of less than 2 microns.
Claim 2
Dependent Claim
107 words
In a surface barrier diode exhibiting a hypersensitive voltage variable capacitance effect comprising, a wafer of N-type silicon semiconductor material, a layer of metal deposited in surface barrier relation on one surface of said silicon wafer to form a rectifying junction with said silicon wafer, means forming a pair of electrodes formed on the diode for applying an electrical potential across the rectifying junction of the diode, THE IMPROVEMENT COMPRISING, a hypersensitive n region disposed in said silicon wafer immediately adjacent to and underlying said metal layer, said n region having a lower resistivity than said N-type silicon and having a thickness of less than 2 microns.
Claim 3
Dependent Claim
34 words
The apparatus of claim 1 wherein said silicon wafer includes a second n region, an epitaxial n region overlaying said second n region, and said hypersensitive n region formed overlaying said epitaxial n region.
Claim 4
Dependent Claim
44 words
The apparatus of claim 2 wherein said silicon wafer includes a silicon oxide layer overlaying said hypersensitive n region, said silicon oxide layer having a hole therein, and said metal layer being deposited at the bottom of said hole in said silicon oxide layer.