KR20100067882A - An image sensor and method for manufacturing the same - Google Patents

Abstract

PURPOSE: An image sensor and a method for manufacturing the same are provided to shit an optical route to perform an accurate focus of a photo-diode. CONSTITUTION: A semiconductor substrate has a photo diode. An interlayer insulating layer(150) is formed on the substrate and has a metal line(140). A protection layer(160) is formed on the inter-layer insulating film and has a lens shaping section. The color filter layer(180) is formed within the lens shaping sections. The first optic(190) is formed within the lens shaping section and is formed on the color filter layer. The second lens(200) is formed within the lens shaping section and is formed on the first optic.

Description

An image sensor and method for manufacturing the same

This embodiment discloses an image sensor and a method of manufacturing the same.

An image sensor is a semiconductor device that converts an optical image into an electrical signal, and is largely a charge coupled device (CCD) and a CMOS (Complementary Metal Oxide Silicon) image sensor. Sensor) (CIS).

A charge coupled device (CCD) is a device in which charge carriers are stored and transported in a capacitor while individual metal-oxygen-silicon (MOS) capacitors are located in close proximity to each other.

Complementay MOS image sensors use CMOS technology that uses control and signal processing circuits as peripheral circuits to create MOS transistors as many pixels as those, which in turn An element employing a switching method for detecting an output of a pixel.

Recently, as the number of pixels of the CMOS image sensor increases to a mega level, pixels are formed in a relatively small size. The reduction in pixel size limits the size of the microlenses formed on the pixels, which also limits the focal length of the pixels and the microlenses.

1 is a diagram illustrating a schematic configuration of a CMOS image sensor, FIG. 2 is a diagram illustrating a state in which light is focused in a sensitivity region, and FIG. 3 is a diagram in which light is not focused in a sensitivity region. It is a figure for showing.

As shown in FIG. 1, light entering the edge of the image sensor is not incident alongside the optical axis, but is off-axis.

Therefore, the light incident on the sensor array located parallel to the optical axis is normally focused exactly at the sensitive area of the center of the sensor array, as shown in FIG.

On the other hand, the light incident to the edge of the sensor array, as shown in Figure 3, the phenomenon occurs that the shift without focusing the sensitivity region of the sensor array occurs.

Therefore, when the focus of the light is not accurately focused as shown in FIG. 3, in order to shift the focus of the incident light to the center of the sensitivity region, the microlens array should be centered within the minimum unit of 1 chip when manufacturing the mask for the microlens. As you move away from, you must create a mask with a specific shift value.

As a result, when the focal length of the primary lens is changed and the chip size is changed, it is inconvenient to newly manufacture the mask of the microlens.

The present embodiment aims to propose an image sensor capable of shifting an optical path so that accurate focusing of light can be achieved by a photodiode which is a sensitivity region of an image sensor, and a manufacturing method thereof.

The image sensor according to the present embodiment includes a semiconductor substrate on which a photodiode is formed; An interlayer insulating layer formed on the substrate and having metal lines formed thereon; A protective film formed on the interlayer insulating film and having a lens forming part formed thereon; And a color filter layer formed in the lens forming part. A first lens formed in the lens forming unit and formed on the color filter layer; And a second lens formed in the lens forming unit and formed on the first lens.

In addition, a method of manufacturing an image sensor according to an embodiment may include forming an interlayer insulating film on a substrate on which a photodiode is formed, and forming metal wires on the interlayer insulating film; Forming a protective film on the interlayer insulating film; Etching the passivation layer to form a lens forming portion in the passivation layer; Forming a color filter layer and a first lens in the lens forming unit; And forming a second lens on the first lens.

By the image sensor and its manufacturing method of the embodiment as proposed, focusing of light to be incident to the photodiode can be made more accurately, and focusing spot shift of the microlens positioned at the edge of the image sensor In order to compensate for this, by forming two micro lenses having different refractive indices, there is an advantage that the photodiode can be focused.

Hereinafter, with reference to the accompanying drawings for the present embodiment will be described in detail. However, the scope of the idea of the present invention may be determined from the matters disclosed by the present embodiment, and the idea of the invention of the present embodiment may be performed by adding, deleting, or modifying components to the proposed embodiment. It will be said to include variations.

In the following description, the word 'comprising' does not exclude the presence of other elements or steps than those listed. In addition, in the accompanying drawings, the thickness thereof is enlarged in order to clearly express various layers and regions. In addition, the same reference numerals are used for similar parts throughout the specification. When a part of a layer, film, region, plate, etc. is said to be "on" another part, this includes not only being another part "on top" but also having another part in the middle.

4 is a view showing the configuration of the image sensor according to the present embodiment, Figure 5 is a view showing the movement of the optical path by the second micro lens in the image sensor according to the present embodiment.

First, referring to FIG. 4, an interlayer insulating layer 150 is formed on a substrate having a sensitivity region for receiving and converting light into an electrical signal, such as a photodiode, and a plurality of metal wires are formed on the interlayer insulating layer 150. Are formed.

That is, the metal interlayer 140, which may be the final metal wiring layer, and the metal pad 145 for electrical connection with other external devices may be formed in the interlayer insulating layer 150.

In addition, the passivation layer 160 is formed on the interlayer insulating layer 150 to have a predetermined thickness. In particular, the passivation layer 160 has a lens forming part having a predetermined recessed shape according to the present embodiment. The color filter layer 180, the planarization layer 181, the first lens 190, and the second lens 200 are seated in the lens forming part.

That is, a lens that serves to receive light includes a first lens 190 and a second lens 200, and the second lens 200 has a refractive index different from that of the first lens 190. Can be formed. In this case, the light incident toward the edge portion of the first lens 190 is refracted by the second lens 200 and then passes through the first lens 190 to the photodiode, which is a light receiving unit. .

Although a few first lenses 190 are shown in the drawing, in practice, the number of first lenses 190 formed under the second lens 200 may be hundreds of thousands to millions. That is, after forming the first lenses corresponding to each photodiode, the second lens 200 is formed to cover the respective first lenses.

The protective layer 160 may include a lens forming part for accommodating the first lens and the second lens therein, and the lens forming part may have a depth ranging from about 1.2 μm to 1.6 μm. The width of the forming part may be formed differently depending on the size of the device to be manufactured, but may have a length in the range of 2400 μm to 3000 μm.

That is, the second lens 200 having a different refractive index is formed on the upper side of the micro lenses (first lens) formed as the image sensor.

And, as shown in FIG. 5, the second lens 200 is sensitive to light incident to the edge portion of the chip (only a few are shown for the microlenses constituting the chip in FIG. 5). In order to be able to be incident on the photodiode, which is an area, it is provided to have a predetermined curvature as a shape such as a concave lens.

The pad protection layer 170 for protecting the metal may be formed to a predetermined thickness on the uppermost metal line 140 and the metal pad 145.

That is, the passivation layer 160 is formed on the interlayer insulating layer 150 having the uppermost metal line, and the first lens 190 and the second lens 200 are formed in the lens forming portion inside the passivation layer. In addition, a pad protection layer 170 having a predetermined thickness may be further formed on the protection layer 160.

In addition, a metal hole 162 may be formed in the passivation layer 160 corresponding to the upper side of the metal pad 145 to later expose the upper surface of the metal pad 145.

5 illustrates a first lens 190 as a micro lens for collecting light and a second lens formed on the first lens 190 to improve light reception efficiency of light incident on an edge of a chip. 200 is shown.

As described above, the second lens 200 may be formed with a different refractive index than the first lens 190, and in this case, light incident on the edge of the chip due to a difference in refractive index between the first lens and the second lens. The light receiving capability of the photodiode, which is a light receiving unit, can be further improved.

The second lens 200 is provided in a concave shape with a predetermined curvature and is formed on the plurality of lenses 190 constituting the chip.

Next, a method of manufacturing the image sensor according to the present embodiment will be described.

6 to 8 are views for explaining the manufacturing method of the image sensor according to the present embodiment.

First, referring to FIG. 6, a pre-metal dielectric 130 may be formed on the semiconductor substrate 100 on which the photodiode 120 and the periphery are formed as the sensitivity region. For example, the pre-metallic insulating film 130 may be a TEOS film or a BPSG film.

In addition, a metal wiring layer is formed on the metal wiring insulating layer 130. The metal wiring layer is composed of metal wires formed through the interlayer insulating film 150 and the interlayer insulating film 150.

Here, the metal wirings will be described with reference to the case of the uppermost layer, in which case the metal wirings M2 140 and the metal pads 145 are formed in the interlayer insulating film 150. Although not specifically illustrated, the metallization layer may be formed of a plurality of layers to connect the power supply line, the signal line, the photodiode of the unit pixel, and the peripheral circuit.

In addition, the metal wires 140 may be intentionally configured so as not to block light incident to each photodiode 120.

In addition, the passivation layer 160 is formed on the interlayer insulating layer 150. The passivation layer 160 is formed on the interlayer insulating layer 150 including the final metal line 140 and the metal pad 145 to protect the device from moisture, scratches, and the like.

The protective layer 160 may be an oxide layer such as USG or TEOS.

Next, referring to FIG. 7, the passivation layer 160 is partially etched to form a lens forming unit 161 and a metal hole in which a first lens which is a micro lens and a second lens formed on the first lens are formed. 162).

That is, in order to form the color filter layer and the micro lens inside the passivation layer 160, the process of etching the passivation layer 160 is performed on the region where the micro lens is to be formed, and the etching of the passivation layer 160 is performed. A portion of the interlayer insulating layer 150 may be exposed.

Although the depth B and the width A of the lens forming unit 161 formed in the passivation layer 160 are similar in size, the second lens according to the embodiment may be hundreds of thousands to millions of parts. Since it is provided in a size that can cover the microlens, the depth B of the lens forming portion 161 is formed in a range of 1.2 μm to 1.6 μm, and the horizontal width A of the lens forming portion 161 is 2400 μm. It may be formed to a size in the range from 3000㎛.

In the process of etching the passivation layer 160, a metal hole 162 exposing a portion of the upper surface of the metal pad 145 may be further formed.

After forming the lens forming unit 161 and the metal hole 162 by etching the passivation layer 160, a pad passivation layer 170 made of an insulating layer may be further formed on the passivation layer 160.

Next, referring to FIG. 8, a plurality of color filter layers 180 are formed in the lens forming unit 161 in the passivation layer 160, and the plurality of first lenses 190 are formed on the color filter layer 180. Form.

In addition, a second lens 200 having a different refractive index is formed on the first lens 190. Since a step is formed in the protective layer 160 due to the lens forming portion, a photoresist for forming the second lens 200 is formed. Spin coating results in a concave shape as shown by the depth and width of the step.

That is, as the depth of the lens forming portion formed by etching the passivation layer 160 increases, the curvature of the second lens 200 also increases.

As a result, an image sensor is manufactured according to the proposed embodiment, and the steps of forming the color filter layer, the planarization layer, and the microlens (first lens) in the lens forming portion of the protective film correspond to each photodiode region by a known method. It is formed to be.

1 shows a schematic configuration in a CMOS image sensor.

2 is a view for showing a state in which light is focused to the sensitivity region.

3 is a view for showing a state in which light is not focused in the sensitivity region.

4 is a diagram showing the configuration of an image sensor according to the present embodiment;

5 is a view showing the movement of the optical path by the second micro lens in the image sensor according to the present embodiment.

6 to 8 are views for explaining the manufacturing method of the image sensor according to the present embodiment.

Claims (11)

A semiconductor substrate on which a photodiode is formed; An interlayer insulating layer formed on the substrate and having metal lines formed thereon; A protective film formed on the interlayer insulating film and having a lens forming part formed thereon; And A color filter layer formed in the lens forming portion; A first lens formed in the lens forming unit and formed on the color filter layer; And And a second lens formed in the lens forming unit and formed on the first lens. The method of claim 1, And the second lens has a refractive index different from that of the first lens. The method of claim 1, The first lens is formed in plural to correspond to each of the plurality of photodiodes, And the second lens is formed on a plurality of first lenses. The method of claim 1, And the second lens has a concave shape having a predetermined curvature. The method of claim 1, And a metal hole formed in the passivation layer to open a metal pad formed in the interlayer insulating layer. The method of claim 1, The lens forming portion of the protective film has a depth of 1.2㎛ to 1.6㎛ range, The horizontal width of the lens forming portion is an image sensor, characterized in that consisting of a size in the range of 2400㎛ to 3000㎛. The method of claim 1, An image sensor, characterized in that the pad protective film of a predetermined thickness is further formed on the protective film. Forming an interlayer insulating film on the substrate on which the photodiode is formed, and forming metal wires on the interlayer insulating film; Forming a protective film on the interlayer insulating film; Etching the passivation layer to form a lens forming portion in the passivation layer; Forming a color filter layer and a first lens in the lens forming unit; And And forming a second lens on the first lens. The method of claim 8, The forming of the second lens may include forming the second lens in the lens forming part. The method of claim 8, The forming of the second lens may be performed by spin-coating a photoresist using a step of a protective film formed by the lens forming unit. The method of claim 8, The forming of the lens forming unit may include forming the lens forming unit by etching a passivation layer in a region corresponding to the photodiode.

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