CN105428377A - CMOS image sensor - Google Patents

Abstract

The invention relates to a CMOS image sensor, comprising a substrate layer, a microlens layer and a light filter layer located above the substrate layer; the microlens layer includes several condenser lenses distributed in an array; the light filter layer includes a plurality of transmission gratings distributed in an array; The substrate layer includes several photodiode groups distributed in an array. The photodiode groups include red photodiodes, green photodiodes and blue photodiodes arranged in sequence; The photodiode corresponds to the red light emitting area of the transmission grating, the green photodiode corresponds to the green light emitting area of the transmission grating, and the blue photodiode corresponds to the blue light emitting area of the transmission grating. The invention replaces the color filter with a transmission grating, has a wide wavelength range, no light filtering loss, increases the light intensity entering the photodiode, improves the resolution and color reproduction of the CMOS image sensor, and expands its environmental use range and application field.

Description

A CMOS image sensor

technical field

The invention relates to the technical field of semiconductors, in particular to a CMOS image sensor.

Background technique

Existing CMOS image sensors acquire and distinguish colors through color filters on the photosensitive element. There are two main types of color filters: Bayer array and stripe array. However, due to the narrow wavelength range of the color filter, it is easy to cause poor resolution of the CMOS image sensor; and because the color filter has a certain thickness and only allows part of the wavelength of light to pass through, the light intensity entering the detector is reduced, which is easy to cause CMOS image sensors have poor color reproduction.

Contents of the invention

The object of the present invention is to provide a CMOS image sensor to solve the above-mentioned problems in the prior art.

The technical scheme that the present invention solves the problems of the technologies described above is as follows:

A CMOS image sensor, comprising a substrate layer and a microlens layer and a light filter layer positioned above the substrate layer;

The microlens layer includes several condenser lenses distributed in an array;

The light filtering layer includes several transmission gratings distributed in an array;

The substrate layer includes several photodiode groups arranged in an array, and the photodiode groups include red photodiodes, green photodiodes and blue photodiodes arranged in sequence; The photodiode group is arranged, and the red photodiode of the photodiode group corresponds to the red light emission area of the transmission grating, and the green photodiode of the photodiode group corresponds to the green light emission area of the transmission grating, The blue photodiodes of the photodiode group correspond to the blue light emitting regions of the transmission grating.

The beneficial effects of the present invention are: using the dispersion principle of the transmission grating, using the three primary colors of red, green and blue photodiodes to respectively receive the red, green and blue light from the decomposition of the transmission grating; replacing the existing color filter with the transmission grating The chip has a wide wavelength range, and there is no light filtering loss, which increases the light intensity entering the photodiode; improves the resolution and color reproduction of the CMOS image sensor, and expands its environmental use range and application field.

On the basis of the above technical solutions, the present invention can also be improved as follows.

Further, the apertures of the photodiodes are all less than 2um.

The beneficial effect of adopting the above further solution is to improve the resolution of the CMOS image sensor and effectively reduce the size of the CMOS image sensor.

Further, the microlens layer is located between the light filter layer and the substrate layer, and one condenser lens is arranged above each photodiode, and the diameter of the condenser lens is 2um.

The beneficial effect of adopting the above further solution is that the condensing lens efficiently couples the red, green, and blue light decomposed by the transmission grating into the corresponding red, green, and blue photodiodes, increasing the light intensity entering the photodiodes.

Further, the microlens layer further includes a light-transmitting film material, and the light-transmitting film material is coated on the upper surface of the condenser lens to obtain a flat upper surface of the microlens layer.

The beneficial effect of adopting the above further solution is that it is convenient to prepare a transmission grating on the microlens layer.

Further, the substrate layer also includes a metal grid, the metal grid is arranged between two adjacent photodiodes, and the upper and lower surfaces of the metal grid are respectively connected to the upper and lower surfaces of the substrate layer. at the same level.

The beneficial effect of adopting the above further solution is to improve the sensitivity and anti-interference performance of the CMOS image sensor.

Further, the light filter layer is located between the microlens layer and the substrate layer, and a row of the condensing lenses is arranged above the incident surface of each transmission grating, and the diameter of the condensing lenses is 6um.

The beneficial effect of adopting the above further solution is that the condensing lens efficiently couples white light into the transmission grating, increasing the light intensity entering the photodiode.

Further, the substrate layer also includes a metal grid, the metal grid is arranged between two adjacent photodiode groups, and the upper and lower surfaces of the metal grid are respectively connected to the upper and lower surfaces of the substrate layer. surfaces are at the same level.

The beneficial effect of adopting the above further solution is to improve the sensitivity and anti-interference performance of the CMOS image sensor.

Description of drawings

1 is a schematic diagram of a first embodiment of a CMOS image sensor of the present invention;

FIG. 2 is a schematic diagram of a second embodiment of a CMOS image sensor of the present invention.

In the accompanying drawings, the list of parts represented by each label is as follows:

1, substrate layer, 11, photodiode group, 111, red photodiode, 112, green photodiode, 113, blue photodiode, 12, metal grid, 2, microlens layer, 21, condenser lens, 3, Light filtering layer, 31. Transmission grating.

detailed description

The principles and features of the present invention are described below in conjunction with the accompanying drawings, and the examples given are only used to explain the present invention, and are not intended to limit the scope of the present invention.

As shown in Figures 1 and 2, a CMOS image sensor includes a substrate layer 1 and a microlens layer 2 and an optical filter layer 3 positioned above the substrate layer 1;

The microlens layer 2 includes several condenser lenses 21 distributed in an array;

The light filtering layer 3 includes several transmission gratings 31 distributed in an array;

The substrate layer 1 includes several photodiode groups 11 distributed in an array, and the photodiode group 11 includes red photodiodes 111, green photodiodes 112 and blue photodiodes 113 arranged in sequence; each of the transmission gratings 31 A row of the photodiode groups 11 is arranged below the exit surface, and the red photodiodes 111 of the photodiode groups 11 correspond to the red light emission area of the transmission grating 31, and the green photodiodes of the photodiode groups 11 112 corresponds to the green light emission area of the transmission grating 31 , and the blue photodiode 113 of the photodiode group 11 corresponds to the blue light emission area of the transmission grating 31 .

Preferably, the apertures of the photodiodes 111, 112, 113 are all less than 2um.

The first embodiment is shown in FIG. 1. Preferably, the microlens layer 2 is located between the light filter layer 3 and the substrate layer 1, and one of the light concentrators is arranged above each photodiode 111, 112, 113. The lens 21, the diameter of the condenser lens 21 is 2um.

Preferably, the microlens layer 2 further includes a light-transmitting film material 22 , and the light-transmitting film material 22 is coated with the upper surface of the condenser lens 21 to obtain a flat upper surface of the microlens layer 2 .

Preferably, the substrate layer 1 further includes a metal grid 12, the metal grid 12 is arranged between two adjacent photodiodes 111, 112, 113, and the upper and lower surfaces of the metal grid 12 are respectively connected to The upper and lower surfaces of the substrate layer 1 are at the same level.

The second embodiment is shown in FIG. 2 . Preferably, the light filter layer 3 is located between the microlens layer 2 and the substrate layer 1, and a column of the light-concentrating light is arranged above the incident surface of each transmission grating 31. The lens 21, the diameter of the condenser lens 21 is 6um.

Preferably, the substrate layer 1 further includes a metal grid 12, the metal grid 12 is arranged between two adjacent photodiode groups 11, and the upper and lower surfaces of the metal grid 12 are respectively connected to the substrate The upper and lower surfaces of the bottom layer 1 are on the same horizontal plane.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection of the present invention. within range.

Claims (7)

1. A CMOS image sensor, characterized in that, comprises a substrate layer (1) and a microlens layer (2) and a light filter layer (3) positioned above the substrate layer (1); The microlens layer (2) includes several condenser lenses (21) distributed in an array; The light filtering layer (3) includes several transmission gratings (31) distributed in an array; The substrate layer (1) includes several photodiode groups (11) distributed in an array, and the photodiode group (11) includes red photodiodes (111), green photodiodes (112) and blue photodiodes arranged in sequence (113); a column of photodiode groups (11) is arranged below the exit surface of each transmission grating (31), and the red photodiodes (111) of the photodiode groups (11) correspond to the The red light emission area of the transmission grating (31), the green photodiode (112) of the photodiode group (11) corresponds to the green light emission area of the transmission grating (31), and the photodiode group (11) The blue photodiode (113) corresponds to the blue light emission area of the transmission grating (31). 2. A CMOS image sensor according to claim 1, characterized in that the apertures of the photodiodes (111, 112, 113) are all smaller than 2um. 3. a kind of CMOS image sensor according to claim 2, is characterized in that, described microlens layer (2) is positioned between described light filtering layer (3) and substrate layer (1), and each photodiode ( 111, 112, 113) above are all provided with a said condenser lens (21), the aperture of said condenser lens (21) is 2um. 4. A kind of CMOS image sensor according to claim 3, is characterized in that, described microlens layer (2) also comprises light-transmitting film material (22), and described light-transmitting film material (22) is coated with described The upper surface of the condensing lens (21) obtains a smooth upper surface of the microlens layer (2). 5. A CMOS image sensor according to claim 3, characterized in that, the substrate layer (1) further comprises a metal grid (12), and the metal grid (12) is arranged between two adjacent photodiodes (111, 112, 113), and the upper and lower surfaces of the metal grid (12) are respectively at the same level as the upper and lower surfaces of the substrate layer (1). 6. a kind of CMOS image sensor according to claim 2, is characterized in that, described light filtering layer (3) is positioned between described microlens layer (2) and substrate layer (1), and each transmission grating ( 31) above the incident surface is provided with a row of the condenser lens (21), the diameter of the condenser lens (21) is 6um. 7. A CMOS image sensor according to claim 6, characterized in that, the substrate layer (1) further comprises a metal grid (12), and the metal grid (12) is arranged between two adjacent photodiodes between the groups (11), and the upper and lower surfaces of the metal grid (12) are respectively at the same level as the upper and lower surfaces of the substrate layer (1).