Multiband optoelectronic device for colorimetric applications and related manufacturing process

An array comprising a plurality of optoelectronic devices for detecting radiation, each optoelectronic device including:

• a cathode region formed in a semiconductor body, the cathode region being delimited by a front surface of the semiconductor body, and having a first conductivity type, said cathode region having a lower layer;
• an anode region having a second conductivity type, which extends in the cathode region starting from the front surface and forms a shallow junction with said cathode region;
• and
• a first buried region having the second conductivity type, which extends within the cathode region and forms a first buried junction with said lower layer;
• and wherein said cathode region further comprises a first buffer layer, which is arranged underneath the anode region and overlies, in direct contact, the lower layer, said first buffer layer having a doping level higher than a doping level of the lower layer.

A detection system comprising:

• an optoelectronic device for detecting radiation, the optoelectronic device including a semiconductor body including:
• a cathode region delimited by a front surface of the semiconductor body and having a first conductivity type, said cathode region having a lower layer;
• an anode region having a second conductivity type, which extends in the cathode region starting from the front surface and forms a shallow junction with said cathode region;
• and
• a first buried region having the second conductivity type, which extends within the cathode region and forms a first buried junction with said lower layer, wherein said cathode region further comprises a first buffer layer, which is arranged underneath the anode region and overlies, in direct contact, the lower layer, said first buffer layer having a doping level higher than a doping level of the lower layer;
• a power supply configured to bias by turns the shallow junction and the first buried junction;
• and
• an electronic circuitry configured to determine a first quantity and a second quantity indicating, respectively, a light intensity of a first spectral component of the radiation and a light intensity of a second spectral component of the radiation.

A process for manufacturing an optoelectronic device for detecting radiation, comprising:

• forming a cathode region in a semiconductor body, the cathode region being delimited by a front surface of the semiconductor body, having a first conductivity type, and including a lower layer;
• inside the cathode region, forming, starting from the front surface, an anode region having a second conductivity type, the anode region forming a shallow junction with the cathode region;
• and
• inside the cathode region, forming a first buried region having the second conductivity type, the first buried region forming a first buried junction with the lower layer;
• and wherein forming the cathode region further comprises forming, underneath the anode region, a first buffer layer that overlies, and directly contacts, the lower layer, said first buffer layer having a doping level higher than a doping level of the lower layer.

The manufacturing process according to claim, further comprising:

• forming a first trench that traverses the front surface, extends in the cathode region, and includes a top portion, which traverses the first buffer layer, and a bottom portion, which extends within the lower layer, wherein said first trench has a ring shape;
• forming first dielectric coating region on side walls of the top portion of the first trench, including forming an inner dielectric coating region and an outer dielectric coating region on the side walls of the first trench;
• inside the top portion of the first trench, forming a top portion of a first conductive region, the top portion being surrounded by the first dielectric coating region;
• and
• inside the bottom portion of the first trench, forming a bottom portion of the first conductive region, wherein forming the inner and outer coating regions includes:
• after forming the first trench, coating the side walls and the bottom of the first trench with at least one dielectric coating layer;
• forming, on the at least one dielectric coating layer, a first protective layer and a second protective layer, which are opposite to one another and leave exposed a portion of said at least one dielectric coating layer that coats the bottom portion of the first trench;
• selectively removing the exposed portion of said at least one dielectric coating layer and exposing an underlying portion of the bottom layer;
• and
• removing the first and second protective layers;
• wherein:
• forming the top portion and the bottom portion of a first conductive region comprise forming in the first trench a first polysilicon region with the second doping type, the first polysilicon region contacting the inner coating region, the outer coating region, and the lower layer;
• and
• forming the first buried region comprises carrying out a thermal treatment that causes dopant impurities present in the first polysilicon region to diffuse into the lower layer.