CN212230431U

CN212230431U - Front-illuminated image sensor

Info

Publication number: CN212230431U
Application number: CN201922434691.7U
Authority: CN
Inventors: 徐涛; 李�杰; 付文; 郑展
Original assignee: Geke Microelectronics Shanghai Co Ltd
Current assignee: Geke Microelectronics Shanghai Co Ltd; Galaxycore Shanghai Ltd Corp
Priority date: 2019-12-30
Filing date: 2019-12-30
Publication date: 2020-12-25
Anticipated expiration: 2029-12-30

Abstract

The utility model discloses a front-illuminated image sensor, a top metal layer and a plurality of groove areas between the top metal layers; the embedded color filter film layer is positioned in the groove area of the top metal layer of the pixel unit; an embedded color filter film layer is formed in a groove area between top metal layers in a pixel unit area, so that optical crosstalk between different pixel units of the front-illuminated image sensor is reduced, and the performance of the image sensor is improved.

Description

Front-illuminated image sensor

Technical Field

The utility model relates to an image sensor field especially relates to a front-illuminated image sensor.

Background

An image sensor is a sensor that can sense optical image information and convert it into an electrical output signal, and is an important component that constitutes a digital camera. Depending on the Device, the Device can be classified into two categories, namely, a CCD (Charge Coupled Device) and a CMOS (Complementary Metal-oxide semiconductor).

The CMOS image sensor has the advantages of simple process, easy integration with other devices, small volume, light weight, low power consumption, low cost and the like. Therefore, as the technology is developed, CMOS image sensors are increasingly used in various electronic products instead of CCD image sensors. At present, CMOS image sensors are widely used in still digital cameras, camera phones, digital video cameras, medical imaging devices (e.g., gastroscopes), vehicle imaging devices, and the like. CMOS image sensor products can be classified into FSI (front Side Illumination) and BSI (Back Side Illumination).

The front-illuminated image sensor needs to be optimized in terms of performance problems such as the length of an optical path, crosstalk of adjacent pixel units and the like, and is a problem to be solved urgently in the industry.

SUMMERY OF THE UTILITY MODEL

The utility model aims to solve the technical problem of how to optimize the device structure of the front-illuminated image sensor and improve the performance of the front-illuminated image sensor; for this purpose,

the utility model also provides a front-illuminated image sensor, it includes:

a plurality of groove regions between the top metal layer and the top metal layer;

and the embedded color filter film layer is positioned in the groove area of the top metal layer of the pixel unit.

Preferably, the thickness of the top metal layer is: 2000 angstroms to 6000 angstroms.

Preferably, the top surface of the top metal layer is sequentially provided with: part of the metal interconnection dielectric layer and the hard mask layer.

Preferably, the surface of the top metal layer is provided with: a hard mask layer.

Preferably, the thickness of the hard mask layer is: 100 angstroms to 1000 angstroms.

Preferably, the hard mask layer is: SiN, SiON, SiC, SiNC, SiONC.

The utility model discloses, realize forming embedded colored light filtering film layer through the technology mode, can:

1) optical crosstalk is reduced by using a groove region between top metal layers in a pixel unit region;

2) the embedded color filter film layer structure of the front-illuminated image sensor can be realized by using the groove region between the top metal layers in the pixel unit region;

3) through the use of the groove region between the top metal layers in the pixel unit region, the color filter film layer is embedded in the groove region, so that the optical response abnormity at the step of the pixel region and the logic region is avoided;

4) the groove area between the top metal layers of the pixel unit area is formed when the top metal layers are etched, and extra manufacturing cost is not required to be increased.

Drawings

Fig. 1 is a side sectional view of a front-illuminated image sensor according to the present invention after a specific step of defining a pixel array area;

fig. 2 is a top view of the front-illuminated image sensor after a specific step of the pixel array area according to the present invention;

fig. 3 to 6 are schematic structural views of steps in a method of forming a first embodiment of a front-illuminated image sensor according to the present invention;

fig. 7 to 11 are schematic structural views of steps in a forming method of a second embodiment of a front-illuminated image sensor according to the present invention.

Detailed Description

In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. The present invention can be implemented in many different ways than those herein described and one skilled in the art can do so without departing from the spirit and scope of the present invention, which is not limited to the specific implementations disclosed below.

In a front-illuminated CMOS image sensor product, BEOL (Back end of Line) manufacturing processes have at least two layers of metal wirings, that is, a plurality of layers of metal wirings and dielectric layers, and usually, a logic region is a three-layer metal wiring, and a pixel unit region is a two-layer metal wiring. For the photosensitive area, the distance from the chip surface to the photosensitive surface is large, so that incident light rays can be absorbed by the photosensitive area only after passing through a long path (optical path), the light rays are greatly attenuated, the light Ray sensitivity is reduced, the CRA (Chief Ray Angle, the included Angle between the main light Ray and the normal direction of an imaging surface) of the chip cannot be too large, the application range is limited, and the performance of the image sensor is greatly influenced.

Please refer to fig. 1 and fig. 2; fig. 1 is a cross-sectional side view of a logic area and a pixel array area of a front-illuminated image sensor according to the present invention, wherein the left side of a dotted line is the logic area, and the right side of the dotted line is the pixel unit area; fig. 2 is a top view of the front-illuminated image sensor after a specific step of the pixel array area according to the present invention; in fig. 1, a top metal layer 200 of the front-illuminated image sensor is formed on an inter-metal dielectric layer 100, and it should be noted that the top metal layer 200 specially left in a pixel unit region is used for forming a groove to prepare for forming an embedded structure subsequently; in fig. 2, the top metal layer 200 is a grid structure.

Referring to fig. 3 to 6, fig. 3 to 6 are schematic structural diagrams of steps in a forming method of a front-illuminated image sensor according to a first embodiment of the present invention; in the steps subsequent to fig. 1, in fig. 3, the metal interconnection dielectric layer 300 is formed by laying, and the hard mask layer 400 is formed on the metal interconnection dielectric layer 300; in fig. 4, a hard mask layer 400 is formed on a metal interconnection dielectric layer 300, and then the hard mask layer 400 and the metal interconnection dielectric layer 300 in a pixel unit region are etched until the side portion of a top metal layer 200 is exposed, wherein a remaining part of the metal interconnection dielectric layer 310 and a remaining part of the hard mask layer 410 are sequentially formed on the top of the top metal layer; and in the process of etching the metal interconnection dielectric layer, etching the metal interconnection dielectric layer in the pixel unit region and reserving the metal interconnection dielectric layer in the peripheral circuit region. In fig. 5, an embedded color filter film layer 510 is formed in the groove region between the top metal layers in the pixel unit region; fig. 6 shows that a microlens 600 is formed on the upper portion of the color filter layer 510, and the embedded color filter layer is spaced by the top metal layer 200 in this embodiment, so as to reduce optical crosstalk, reduce optical crosstalk between different pixel units of the front-illuminated image sensor, and improve the performance of the image sensor.

Referring to fig. 7 to 11, fig. 7 to 11 are schematic structural diagrams of steps in a forming method of a front-illuminated image sensor according to a second embodiment of the present invention; in fig. 7, a metal interconnection dielectric layer 300 'is formed by laying, in fig. 8, the metal interconnection dielectric layer 300' in the pixel unit region is etched to expose the top and side portions 210 'of the top metal layer, in this embodiment, a portion of the inter-metal dielectric layer 100' is also etched to leave 110 ', in fig. 9, a hard mask layer 400' is formed by laying to cover the pixel unit region and the peripheral region of the image sensor; in fig. 10, an embedded color filter film 500 ' is formed in a region where a groove region between top metal layers of a pixel unit region covers a hard mask layer, and fig. 11 is a microlens 600 ' located on an upper portion of the color filter film 500 ', in this embodiment, the embedded color filter film is spaced by the top metal layers 210 ', a metal interconnection dielectric layer of the pixel unit region is etched first to expose a top portion and a side portion of the top metal layer, and then the hard mask layer is formed, and a hard mask layer 400 ' is provided between the groove region of the top metal layer and the embedded color filter film.

In the above embodiment, the thickness of the top metal layer is: 2000 angstroms to 6000 angstroms. The hard mask layer is any one or combination of more of SiN, SiON, SiC, SiNC and SiONC, and the thickness of the hard mask layer is as follows: 100 angstroms to 1000 angstroms.

The beneficial effects of utility model are as follows:

The present invention is described in detail by using schematic diagrams, and when the embodiments of the present invention are described in detail, the schematic diagrams are only examples for convenience of explanation, and the scope of protection of the present invention should not be limited herein.

It should be noted that the CMOS image sensor of the present invention can be used in a wide variety of general purpose or special purpose computing system environments or configurations. For example: personal computers, server computers, hand-held or portable devices, tablet-type devices, multiprocessor systems, microprocessor-based systems, set top boxes, programmable consumer electronics, network PCs, minicomputers, mainframe computers, distributed computing environments that include any of the above systems or devices, and the like.

Although the present invention has been disclosed in the preferred embodiments, it is not intended to limit the present invention, and any person skilled in the art can use the above-mentioned method and technical contents to make possible changes and modifications to the technical solution of the present invention without departing from the spirit and scope of the present invention, therefore, any simple modification, equivalent changes and modifications made to the above embodiments by the technical substance of the present invention all belong to the protection scope of the technical solution of the present invention.

Claims

1. A front-illuminated image sensor, comprising:

2. The front-illuminated image sensor of claim 1, the thickness of the top metal layer being: 2000 angstroms to 6000 angstroms.

3. The front-illuminated image sensor as in claim 1, the top surface of the top metal layer having disposed thereon, in order: part of the metal interconnection dielectric layer and the hard mask layer.

4. The front-illuminated image sensor as recited in claim 1, wherein a surface of the top metal layer is provided with: a hard mask layer.

5. The front-illuminated image sensor according to any one of claims 3 or 4, wherein the hard mask layer has a thickness of: 100 angstroms to 1000 angstroms.

6. The front-illuminated image sensor according to any one of claims 3 or 4, wherein the hard mask layer is: SiN, SiON, SiC, SiNC, SiONC.