KR20110139520A

KR20110139520A - Image sensor having multi-lens

Info

Publication number: KR20110139520A
Application number: KR1020100059649A
Authority: KR
Inventors: 정연우
Original assignee: 주식회사 하이닉스반도체
Priority date: 2010-06-23
Filing date: 2010-06-23
Publication date: 2011-12-29

Abstract

PURPOSE: An image sensor having a multi-lens is provided to improve the focusing characteristic of light by increasing the integration of light in a light receiving region. CONSTITUTION: In a image sensor having a multi-lens, light-receiving regions(105a,105b) are formed in a substrate(101). Multi-layereds(110,120,130,PG,M1,M2) are formed on the substrate. Multi-layered comprises a metal line and an inter-layer insulating film. A lower micro lens(140) is formed on the multi-layered. The lower micro lens condenses the light to the light-receiving region. A color filter layer(150) is formed on the lower micro lens. An upper micro lens(160) is formed on a color filter layer. A plurality of bead type mosaic eye lenses are arranged within the upper micro lens.

Description

Image sensor having multi-lens

The present invention relates to an image sensor, and more particularly to an image sensor having multiple lenses.

An image sensor is an apparatus for capturing an image by using a property of a semiconductor that reacts to light, and includes a plurality of pixels for capturing an image. Each part of the subject in nature has different brightness and wavelengths of light, so that each pixel of the image sensor that detects light may have a different electrical value. The image sensor makes this electrical value a signalable level. Such imagers include pixel arrays of tens of thousands to hundreds of thousands or more of unit pixels (hereinafter, simply referred to as pixels), devices for changing digital voltages of analog voltages sensed by a plurality of pixels, and a plurality of storage devices. .

In particular, a CMOS image sensor can be constructed using CMOS technology and typically includes a photodiode, which is a light receiving region, and a plurality of MOS transistors for each pixel. Such a CMOS image sensor stores image information of a subject as a photodiode and converts it into an electrical signal. In addition, the CMOS image sensor includes a color filter and microlens on each pixel region to receive light as an input, so the light transmittance has a great effect on the image sensor characteristics and is sensitive to process or structural changes.

In image sensors, including CMOS image sensors, it is important to integrate light from outside into a light receiving region, such as a photodiode. This is because the image is shaped by the light reaching the light receiving area. Decreased or uneven amount of light reaching the light receiving region causes deterioration of the characteristics of the image sensor and deterioration of the sensing function. Although the conventional image sensor uses a microlens, light received through the outer portion of the lens is refracted before reaching the light receiving area, and thus a light loss occurs. In particular, light outside the microlens may not be collected in the light receiving area.

Embodiments of the present invention provide an image sensor capable of increasing the integration of light into a light receiving area and improving focusing characteristics.

An image sensor according to an embodiment of the present invention includes a substrate on which a light receiving region is formed; A multi-layer structure formed on the substrate and having a metal line and an interlayer insulating film; A lower microlens formed on the multilayer structure to focus light into the light receiving region; A color filter layer formed on the lower microlens; An upper microlens formed on the color filter layer; And a plurality of bead type mosaic-eye lenses arranged in the upper microlens.

The image sensor may further include a translucent overcoating layer formed on the upper microlens, and a plurality of upper hemispherical mosaic eye lenses formed on the overcoating layer. The overcoat layer may be a conformal layer conformally formed along an upper surface of the upper microlens. The plurality of upper hemispherical mosaic eye lenses may be arranged along an upper surface of the conformal layer.

The image sensor may further include a plurality of lower hemispherical mosaic eye lenses formed between the upper microlens and the overcoating layer. The plurality of lower hemispherical mosaic eye lenses may be arranged along an upper surface of the upper micro lens.

According to an embodiment of the present invention, the degree of integration of light into a light receiving region such as a photodiode can be increased and the focusing characteristic of the light can be improved. This increases the texture and uniformity of light, improves the characteristics and sensing capabilities of the image sensor, and reduces light loss.

1 is a cross-sectional view showing main parts of a pixel of an image sensor according to an exemplary embodiment of the present invention.
2 is a cross-sectional view illustrating main parts of a pixel of an image sensor according to another exemplary embodiment of the present invention.
3 is a cross-sectional view illustrating a main part of a pixel of an image sensor according to another exemplary embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, the embodiments of the present invention may be modified into various other forms, and the scope of the present invention is not limited to the embodiments described below. Elements denoted by the same reference numerals in the drawings are identical elements.

1 is a cross-sectional view showing main portions of pixels of a CMOS image sensor according to an embodiment of the present invention. Referring to FIG. 1, the image sensor 100 includes a semiconductor substrate 101 on which photodiodes 105a and 105b, which are light receiving regions, and multilayer structures 110, 120, 130, PG, M1, and M2 formed thereon are formed. Include. A gate structure PG of a transistor such as, for example, a transfer transistor may be formed on the semiconductor substrate 101. The photodiode PD may be formed by forming a junction between a deep n-type region and a shallow p-type region in a portion of the semiconductor substrate 101 on one side of the gate structure PG. Although not shown, a high concentration of floating diffusion region may be formed in the semiconductor substrate 101 by ion implantation below the substrate surface.

The insulating film 110 is formed on the semiconductor substrate 101 on which the photodiode PD and the gate structure PG are formed, and the first metal line M1 is formed on the insulating film 110. An interlayer insulating layer 120 is formed on the first metal line M1, and a second metal line M2 is formed on the interlayer insulating layer 120. The metal lines M1 and M2 are conductors that connect power lines, signal lines, pixels, and logic circuits. The metal lines M1 and M2 may serve as shields to prevent light from entering the semiconductor region beyond the light receiving region. The insulating layers 110, 120, and 130 may be formed of a silicate insulating layer or a PECVD silicon oxide layer. In addition, an insulating film 130 is formed on the second metal line M2. The insulating layer 130 may serve to protect the layer structure below or to remove the step. Although FIG. 1 shows that the second metal line M2 is the final metal line, an additional metal line (and an additional insulating film structure) may be further provided thereon. The metal lines M1 and M2 and the insulating layers 110, 120, and 130 have a multi-layered structure on a semiconductor substrate on which a photodiode is formed.

The lower microlens 140 is formed on the insulating layer 130. The lower microlens 140 receives light from above and condenses the light to the photodiode PD, which is a light receiving area. The lower microlens 140 may be disposed to overlap the photodiode PD in a vertical direction. An intermediate insulating layer 145 is formed on the lower microlens 140. The intermediate insulating layer 145 may be formed to reduce the level difference caused by the lower microlens 140 or to planarize.

The color filter layer 150 is formed on the intermediate insulating film. The color filter layer 150 implements RGB color per unit pixel. An upper micro lens 160 is formed on the color filter layer 150. In addition, a bead-shaped or spherical mosaic-eye lens is formed in the upper microlens 160 on the color filter layer 150.

The image sensor 100 has a multi-lens structure including lower and upper microlenses 140 and 160 and a plurality of beaded mosaic eye lenses 170, and can greatly increase the intensity of light coming from the outside. It reduces the loss of light generated in the multilayer structure (110, 120, 130, M1, M2). In particular, the plurality of bead-shaped mosaic eye lenses 170 further focus the light collected by the upper microlens 160 to the lower microlens 140, and the lower microlens 140 additionally transmits light to the photodiode PD. ), That is, condensing into a light receiving area. As a result, the degree of integration of light from the outside into the light-receiving area can be greatly improved and the focusing characteristic can be improved. In addition, it is possible to reduce the loss of light passing through the microlens or through both ends of the microlens, and to further enhance the texture and uniformity of the light.

2 is a cross-sectional view illustrating main parts of a pixel of an image sensor according to another exemplary embodiment of the present invention. Referring to FIG. 2, the image sensor 200 may further include an overcoating layer 180 and a plurality of upper hemispherical mosaic eye lenses 190 in addition to the above-described structure of the image sensor. Other elements are the same as the above-described embodiment (see FIG. 1), and thus description thereof will be omitted.

Referring to FIG. 2, the light-transmitting overcoating layer 180 is formed on the upper microlens 160, and in particular, is formed as a conformal layer conformally formed along the upper surface of the upper microlens. . Therefore, the top surface of the overcoat layer 180 may have the same lens shape as the top surface of the upper microlens. A plurality of upper hemispherical mosaic eye lenses 190 are disposed along the upper surface of the overcoating layer 180. The plurality of upper hemispherical mosaic-eye lenses 190 collect light coming from above closer to the center of the upper microlens 160 to further reduce light loss when condensing to the photodiode PD. Also in this embodiment, as described above with reference to FIG. 1, the degree of integration of light into the light-receiving area is greatly improved by the lower and upper microlenses 140 and 160 and the plurality of beaded mosaic eye lenses 170. Its focusing characteristics are improved and the texture and uniformity of light can be improved.

3 is a cross-sectional view illustrating a main part of a pixel of an image sensor according to another exemplary embodiment of the present invention. Referring to FIG. 3, in addition to the structure of the image sensor 200 of FIG. 2, the image sensor 300 includes a plurality of lower hemispherical mosaic eye lenses 195 formed between the upper microlens 160 and the overcoating layer 180. It further includes.

Referring to FIG. 3, the lower hemispherical mosaic eye lens 195 is arranged along the upper surface of the upper microlens 160 between the upper microlens 160 and the overcoating layer 180. In the embodiment of FIG. 3, the dual hemispherical mosaic eye lens structure of the upper and lower hemispherical mosaic eye lenses 190 and 195 allows the light coming from above to be collected closer to the center of the upper microlens 160. Accordingly, it is possible to further reduce the loss of light when condensing to the photodiode PD. The lower hemispherical mosaic eye lens 195 may be added to the upper hemispherical mosaic eye lens 190 to further improve focusing characteristics of the entire lens structure. Also in this embodiment, as described above with reference to FIG. 1, the integration of light into the light receiving region is greatly improved by the lower and upper micro lenses 140 and 160 and the plurality of beaded mosaic eye lenses 170. Its focusing characteristics are improved and the texture and uniformity of light can be improved.

In the above embodiment, the CMOS image sensor has been described as an example, but the present invention is not limited thereto. The invention can also be applied to other image sensors using light receiving regions and microlenses.

It is intended that the invention not be limited by the foregoing embodiments and the accompanying drawings, but rather by the claims appended hereto. Accordingly, various forms of substitution, modification, and alteration may be made by those skilled in the art without departing from the technical spirit of the present invention described in the claims, which are also within the scope of the present invention. something to do.

100, 200, 300: image sensor 101: semiconductor substrate
105a, 105b: photodiode 110: insulating film
120, 130: interlayer insulating film 140: lower microlens
145: intermediate insulating film 150: color filter layer
160: upper microlens 170: beaded mosaic eye lens
180: overcoating layer 190: upper hemispherical mosaic eye lens
195: lower hemispherical mosaic eye lens PD: photodiode
PG: gate structure M1: first metal line
M2: second metal line

Claims

A substrate on which a light receiving region is formed;
A multi-layer structure formed on the substrate and having a metal line and an interlayer insulating film;
A lower microlens formed on the multilayer structure to focus light into the light receiving region;
A color filter layer formed on the lower microlens;
An upper microlens formed on the color filter layer; And
And a plurality of beaded mosaic-eye lenses arranged in the upper microlenses.

The method of claim 1,
And a translucent overcoating layer formed on the upper microlens, and a plurality of upper hemispherical mosaic eye lenses formed on the overcoating layer.

The method of claim 2,
And the overcoat layer is a conformal layer conformally formed along an upper surface of the upper microlens.

The method of claim 3,
And the plurality of upper hemispherical mosaic eye lenses are arranged along an upper surface of the conformal layer.

The method of claim 2,
The image sensor further comprises a plurality of lower hemispherical mosaic eye lenses formed between the upper microlens and the overcoating layer.

The method of claim 5,
And the plurality of lower hemispherical mosaic eye lenses are arranged along an upper surface of the upper micro lens.