Trench sidewall contact schottky photodiode and related method of fabrication

A Schottky photodiode comprising:

• a semiconductor substrate having a front surface, a rear surface, and a first dopant concentration and configured to define a cathode of the Schottky photodiode;
• an epitaxial layer over the front surface of said semiconductor substrate having a second dopant concentration less than the first dopant concentration;
• a plurality of parallel spaced apart trenches in said epitaxial layer and having of a depth less than a depth of said epitaxial layer;
• a metal filler in said plurality of parallel spaced apart trenches to form a Schottky rectifying contact with said epitaxial layer;
• an anode current distributor metal layer on a surface of said epitaxial layer and in electrical contact with said metal filler of said plurality of parallel spaced apart trenches;
• a dielectric passivation layer on said anode current distributor metal layer;
• and
• a conductive layer over the rear surface of said semiconductor substrate and configured to provide an ohmic contact with the cathode.

A Schottky photodiode comprising:

• a semiconductor substrate having a front surface, a rear surface, and a first dopant concentration and configured to define a cathode of the Schottky photodiode;
• a first epitaxial buffer layer over the front surface of said semiconductor substrate;
• a second epitaxial layer over said first epitaxial buffer layer having a second dopant concentration less than the first dopant concentration;
• a plurality of parallel spaced apart trenches in said second epitaxial layer and having of a depth less than a depth of said second epitaxial layer;
• a metal filler in said plurality of parallel spaced apart trenches to form a Schottky rectifying contact with said second epitaxial layer;
• an anode current distributor metal layer on a surface of said second epitaxial layer and in electrical contact with said metal filler of said plurality of parallel spaced apart trenches;
• a dielectric passivation layer on said anode current distributor metal layer;
• and
• a conductive layer over the rear surface of said semiconductor substrate and configured to provide an ohmic contact with the cathode.

A method of making a Schottky photodiode on a semiconductor substrate having a first dopant concentration, the method comprising:

• growing a first epitaxial buffer layer with a second dopant concentration of same type of conductivity of the monocrystalline semiconductor substrate on a front side thereof;
• growing a second epitaxial layer with a third dopant concentration of same type of conductivity of the dopant of the monocrystalline semiconductor substrate over the first epitaxial buffer layer;
• depositing a metal hardmask layer;
• defining an array of spaced parallel openings through the metal hardmask layer by a first lithography step;
• anisotropically etching the doped semiconductor of the second epitaxial layer through the openings of the metal hardmask layer to form trenches and to remove residual metal of the metal hardmask;
• depositing a Schottky contact metal layer for filling the trenches and etching back the deposited metal to remove it from a front surface the Schottky photodiode;
• depositing a metal layer on the front surface in contact with the metal filler of the trenches;
• defining an anode current distributor from the deposited metal layer for connecting the contact metal filler of the trenches and forming a connectable anode terminal pad of the Schottky photodiode with a second lithography step and selective wet etching process;
• depositing a passivation layer over the front surface for coating the anode current distributor;
• removing the passivation layer in areas of separation among coated parallel stripes of the metal anode current distributor defined over the metal filled trenches by a third lithography step and dry etching process;
• and
• depositing a metallization layer over a rear surface of the semiconductor substrate to provide a connectable cathode terminal of the Schottky photodiode.

A method of making a Schottky photodiode comprising:

• forming a semiconductor substrate having a front surface, a rear surface, and a first dopant concentration and to define a cathode of the Schottky photodiode;
• forming an epitaxial layer over the front surface of the semiconductor substrate having a second dopant concentration less than the first dopant concentration;
• forming a plurality of parallel spaced apart trenches in the epitaxial layer and having of a depth less than a depth of the epitaxial layer;
• filling a metal in the plurality of parallel spaced apart trenches to form a Schottky rectifying contact with the epitaxial layer;
• forming an anode current distributor metal layer on a surface of the epitaxial layer and in electrical contact with the metal filler of the plurality of parallel spaced apart trenches;
• forming a dielectric passivation layer on the anode current distributor metal layer;
• and
• forming a conductive layer over the rear surface of the semiconductor substrate and configured to provide an ohmic contact with the cathode.