Photodiode with interfacial charge control and associated process
AssigneesSTMicroelectronics S.r.l., STMicroelectronics (Crolles 2) SAS
InventorsJorge Regolini, Michael Gros-Jean
Life of this patent
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Abstract
A photodiode includes a first doped layer and a second doped layer that share a common face. A deep isolation trench has a face contiguous with the first and second doped layers. A conducting layer is in contact with a free face of the second doped layer. A protective layer is provided at an interface with the first doped layer and second doped layer. This protective layer is capable of generating a layer of negative charge at the interface. The protective layer may further be positioned within the second doped layer to form an intermediate protective structure.
Claims18
A photodiode comprising:
- a first doped layer;
- a second doped layer having a common face with the first doped layer;
- at least one deep isolation trench having a face contiguous with the first doped layer and the second doped layer;
- a conducting layer in contact with a free face of the second doped layer;
- and
- a protective layer configured to generate a layer of negative charge at an interface between, on one side, the first and second doped layers and, on the other side, the deep isolation trench, said protective layer made from a protective material implanted with a material selected from the group consisting of F and ZrO2.
A photodiode, comprising:
- a first doped layer;
- a second doped layer having a common face with the first doped layer;
- at least one deep isolation trench having a face contiguous with the first doped layer and the second doped layer;
- a conducting layer in contact with a free face of the second doped layer;
- a protective layer configured to generate a layer of negative charge at an interface between, on one side, the first and second doped layers and, on the other side, the deep isolation trench;
- and
- an intermediate protective layer at least partly located in the second doped layer, said intermediate protective layer configured to generate a layer of negative charge at an interface with the second doped layer.
A process for producing a deep isolation trench for a photodiode made from a structure comprising a first doped layer and a second doped layer sharing a common face, and a conducting layer in contact with a free face of the second doped layer, comprising:
- etching at least one trench through the first doped layer and the second doped layer as far as the conducting layer;
- conformally depositing in the trench a protective layer of a material providing a layer of negative charge at an interface with first and second doped layers, said material providing a layer of negative charge selected from the group consisting of AlF3, SiN/SiC, Al2O3 and HfAlxOy/SiO2;
- and
- conformally depositing an insulator on the protective layer to fill the trench.
A photodiode, comprising:
- a first layer of a first conductivity type;
- a second layer of a second conductivity type located underneath the first layer;
- an isolation trench;
- and
- a protective layer located at an interface between the isolation trench and the first and second layers, the protective layer including doping species configured to provide a layer of negative charge at the interface, said doping species comprising an implantation material selected from the group consisting of F and ZrO2.
A photodiode comprising:
- a first layer of a first conductivity type;
- a second layer of a second conductivity type located underneath the first layer;
- an isolation trench;
- a protective layer located at an interface between the isolation trench and the first and second layers, the protective layer including doping species configured to provide a layer of negative charge at the interface;
- and
- an intermediate protective layer passing through the second layer, said intermediate protective layer configured to provide a layer of negative charge within the second layer.
A method, comprising:
- forming a first doped silicon layer of a first conductivity type;
- depositing an intermediate protective layer of a material providing a layer of negative charge at an interface with the first doped silicon layer;
- forming a second doped silicon layer of the same first conductivity type overlying the intermediate protective layer;
- forming a third doped silicon layer of a second conductivity type overlying the second doped silicon layer;
- etching a trench through the second and third doped silicon layers and into at least a portion of the first doped silicon layer;
- conformally depositing in the trench a protective layer of a material providing a layer of negative charge at an interface with first through third doped silicon layers;
- and
- depositing an insulator on the protective layer to fill the trench.
A method, comprising:
- forming a first doped silicon layer of a first conductivity type;
- forming a second doped silicon layer of a second conductivity type overlying the first doped silicon layer;
- etching a trench through the second doped silicon layer and into at least a portion of the first doped silicon layer;
- conformally depositing in the trench a protective layer of a material providing a layer of negative charge at an interface with first and second doped silicon layers, said material providing a layer of negative charge selected from the group consisting of AlF3, SiN/SiC, Al2O3, and HfAlxOy/SiO2;
- and
- depositing an insulator on the protective layer to fill the trench.
Dependencies are inferred from the claim text.