Very small image sensor
AssigneeSTMicroelectronics (Crolles 2) SAS
InventorsFrancois Roy, Benoit Ramadout
Life of this patent
Estimating the term…
Abstract
An image sensor formed in a semiconductor stack of a lower region of a first conductivity type and of an upper region of a second conductivity type, including: a photodiode formed of a first portion of the stack; a read area formed of a second portion of the stack; a trench with insulated walls filled with a conductive material, the trench surrounding the photodiode and the read area and being interrupted, all along its height, on a portion facing the photodiode and the read area; and first connection mechanism associated with the conductive material of the trench and capable of being connected to a reference bias voltage.
Claims10
An image sensor formed in a semiconductor stack of a lower region of a first conductivity type and of an upper region of a second conductivity type, comprising:
- a photodiode formed of a first portion of said stack;
- a read area formed of a second portion of said stack;
- a trench with insulated walls filled with a conductive material, the trench surrounding the photodiode and the read area and being interrupted, all along its height, on a portion situated between the photodiode and the read area;
- first connection means associated with the conductive material of the trench and capable of being connected to a reference bias voltage;
- a column with insulated walls, filled with a conductive material formed in the interruption area of the trench;
- and
- second connection means associated with the conductive material of the column and capable of being connected to a reference bias voltage or to a transfer voltage.
A method for manufacturing an image sensor comprising the steps of:
- (a) forming, in a semiconductor substrate of a first conductivity type, a trench and a column, the trench surrounding at least a portion of the substrate and being interrupted, across a portion of its periphery and all along its height, the column being located in the trench interruption region;
- (b) forming, on the bottom and the walls of the trench and of the column, an insulating layer;
- (c) filling the space remaining in the trench and in the column with a conductive material;
- (d) forming, in the semiconductor substrate of the first conductivity type and on the entire surface thereof, a layer of a second conductivity type;
- (e) forming, in the enclosure delimited by the trench and the column, at the surface of the layer of the second conductivity type, a heavily-doped area of the first conductivity type;
- and
- (f) forming, opposite to the heavily-doped area of the first conductivity type with respect to the column, at the surface of the layer of the second conductivity type, a heavily-doped area of the second conductivity type.
Dependencies are inferred from the claim text.