KR20100035439A

KR20100035439A - Cmos image sensor and method for fabricating of the same

Info

Publication number: KR20100035439A
Application number: KR1020080094829A
Authority: KR
Inventors: 석장현
Original assignee: 주식회사 동부하이텍
Priority date: 2008-09-26
Filing date: 2008-09-26
Publication date: 2010-04-05

Abstract

PURPOSE: A CMOS(Complementary Metal-Oxide Semiconductor) image sensor and a manufacturing method thereof are provided to multiply light collecting efficiency by reducing the distance between a micro lens and a photo diode by removing a planar layer. CONSTITUTION: A plurality of photo diodes(41) are formed on a semiconductor substrate(40). An interlayer dielectric layer(42) is formed on a semiconductor substrate front board including a photo diode. A protective film(43) is formed on an interlayer dielectric layer in order to protect a color filter layer(44) and a device. The plurality of color filter layers is formed to have a constant gap on the protective film. A gap protecting spacer is formed in the gap between color filter layers. The micro lens is formed in order to the color filter layer to the photo diode.

Description

CMOS image sensor and method for fabricating the same

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image sensor and a method for manufacturing the same, and more particularly, to a CMOS image sensor and a method for manufacturing the same, which can improve light sensitivity of a photodiode by removing the planarization layer.

In general, an image sensor is a semiconductor device that converts an optical image into an electrical signal, and is generally a charge coupled device (CCD) and CMOS metal (Complementary Metal Oxide Silicon) image. It is divided into Image Sensor.

A charge coupled device (CCD) has a plurality of photo diodes (PDs) for converting a signal of light into an electrical signal in a matrix form, and is arranged between each of the vertical photo diodes arranged in a matrix form. A plurality of vertical charge coupled devices (VCCDs) formed to transfer charges generated in each photodiode in a vertical direction, and horizontally transfer charges transferred by each vertical charge transfer region (VCCD). A horizontal charge coupled device (HCCD) and a sense amplifier (Sense Amplifier) for outputting an electrical signal by sensing the charge transmitted in the horizontal direction.

However, such a CCD has a disadvantage in that the manufacturing method is complicated because the driving method is complicated, the power consumption is large, and the multi-step photo process is required.

In addition, the charge coupling device has a disadvantage in that it is difficult to integrate a control circuit, a signal processing circuit, an analog-to-digital conversion circuit (A / D converter), and the like into a charge coupling device chip, which makes it difficult to miniaturize a product.

Recently, CMOS image sensors have attracted attention as next-generation image sensors to overcome the disadvantages of charge-coupled devices.

The CMOS image sensor uses CMOS technology, which uses a control circuit, a signal processing circuit, and the like as peripheral circuits, to form MOS transistors corresponding to the number of unit pixels on a semiconductor substrate, thereby forming the MOS transistors of each unit pixel. The device adopts a switching method that sequentially detects output.

That is, the CMOS image sensor implements an image by sequentially detecting an electrical signal of each unit pixel by a switching method by forming a photodiode and a MOS transistor in the unit pixel.

The CMOS image sensor has advantages, such as a low power consumption, a simple manufacturing process according to a few photoprocess steps, by using CMOS manufacturing technology.

Hereinafter, a manufacturing method of the CMOS image sensor according to the prior art will be described with reference to the accompanying drawings.

1A to 1C are cross-sectional views illustrating a method of manufacturing a CMOS image sensor according to the prior art.

As shown in FIG. 1A, an interlayer insulating layer 32 is formed on an entire surface of a semiconductor substrate on which at least one photodiode 31 is formed to generate charges according to the amount of incident light.

Next, a planarized protective film 33 is formed on the interlayer insulating layer 32 to protect the device from moisture and scratches. In addition, a coating and patterning process is performed on the protective layer 33 by using a salty resist to form color filter layers 34 for filtering light for each wavelength band.

Then, the planarization planarization layer 35 is formed on the color filter layer 34 in order to adjust the focal length and secure the flatness for forming the lens layer.

Subsequently, as shown in FIG. 1B, a polymer material is adhered to the planarization layer 35 using a material layer for microlenses. After applying the photoresist on the polymer material, the photoresist is patterned by an exposure and development process to define the microlens region. Thereafter, the photoresist film is selectively patterned with a polymer material, which is a material layer for the microlenses, to form a microlens pattern 36a having a size substantially the same as that of the color filter layer 34 while being corresponding to the photodiode 31.

Next, as shown in FIG. 1C, the microlens pattern 36a is heat-treated by a reflow process to form a microlens 36 having a constant curvature.

In the conventional CMOS image sensor, a flattening layer is formed on the color filter layer in order to increase the uniformity of the microlens and to adjust the focal length and to secure the flatness for forming the lens layer.

However, the planarization layer of the conventional CMOS image sensor has a problem of acting as a major factor for reducing the light sensitivity characteristics of the CMOS image sensor instead of improving the uniformity of the microlens.

Accordingly, an object of the present invention is to provide a CMOS image sensor and a method of manufacturing the same that can improve the optical sensitivity of the photodiode by removing the planarization layer.

The CMOS image sensor according to the present invention includes a plurality of photodiodes formed on a semiconductor substrate, an interlayer insulating layer formed on an entire surface of the semiconductor substrate including the photodiode, a protective film formed to protect an element on the interlayer insulating layer; And a plurality of color filter layers formed on the passivation layer to have a predetermined gap with each other at regular intervals corresponding to the photodiode, a gap preventing spacer formed in a gap between the respective color filter layers, and the photodiode on the color filter layer. It characterized in that it comprises a microlens formed to correspond to.

A method of manufacturing a CMOS image sensor according to the present invention includes forming an interlayer insulating layer on a front surface of a semiconductor substrate on which photodiodes are formed, forming a protective film on the interlayer insulating layer, and forming the photodiode on the protective film. Forming a plurality of color filter layers to have a predetermined gap with each other at regular intervals corresponding to the plurality of color filters, forming a nitride film on the entire surface of the plurality of color filter layers, and performing an etch back process on the resultant product including the nitride film. Forming a gap preventing spacer in a gap between each color filter layer, forming a microlens pattern defining a microlens area on the front surface of the color filter layer including the gap preventing spacer, and reflowing the microlens pattern Heat-treating the process to form the microlenses .

As described above, the CMOS image sensor and the method of manufacturing the same according to the present invention can reduce the distance between the microlens and the photodiode by removing the planarization layer, thereby increasing the light collection efficiency, and preventing the gap between the color filters. Therefore, the color reproducibility of the image sensor and the decrease in the color contrast ratio can be effectively suppressed.

Hereinafter, a CMOS image sensor and a method of manufacturing the same according to the present invention will be described in detail with reference to the accompanying drawings.

2 is a cross-sectional view showing a CMOS image sensor according to the present invention.

As shown in FIG. 2, the CMOS image sensor according to the present invention includes a semiconductor substrate 40 on which photodiodes 41 are formed, an interlayer insulating layer 42 formed on an entire surface of the semiconductor substrate, and an interlayer insulating layer 42. A protective film 43 formed on the protective film 43 to protect the device, and a red (R), green (G) and blue (B) color filter layer 44 formed to filter light on the protective film 43, and red and green. And a microlens 46 formed to correspond to the photodiode 41 on the color filter layer 44 including the gap preventing spacer 45 formed between the blue color filter layer 44 and the gap preventing spacer 45.

At least one photodiode 41 is formed to generate electric charges according to the amount of incident light.

The interlayer insulating layer 42 may be formed in a multilayer, or may include a light shielding layer (not shown) for preventing light from being incident on portions other than the photodiode 41.

The protective film 43 is formed on the interlayer insulating layer 32 to protect the device from moisture and scratches.

The color filter layer 44 is formed on the passivation layer 43 to filter light for each wavelength band of red (R), green (G), and blue (B).

The gap preventing spacer 45 may reduce the distance between the microlens 46 and the photodiode 41 by preventing the gap between the color filter layers 44 and removing the planarization layer.

The microlens 46 is hemispherical and has a constant curvature and is formed to correspond to the photodiode 41.

Hereinafter, a method of manufacturing the CMOS image sensor according to the present invention will be described in detail.

3A to 3D are views illustrating a method of manufacturing the CMOS image sensor according to the present invention.

First, as shown in FIG. 3A, an interlayer insulating layer 42 is formed on the entire surface of the semiconductor substrate 40 on which at least one photodiode 41 is formed to generate charges according to the amount of incident light.

Here, the interlayer insulating layer 42 may be formed in multiple layers, and after the formation of one interlayer insulating layer 42, the light blocking layer 47 for preventing light from entering the portion other than the photodiode 41 is formed. After forming, the interlayer insulating layer 42 may be formed again.

Next, a planarized protective film 43 is formed on the interlayer insulating layer 42 to protect the device from moisture and scratches. The color filter layer 44 filters light by wavelength bands of red (R), green (G), and blue (B) by performing a coating and patterning process using a salty resist (not shown) on the protective layer 43. ) To form a constant gap with each other.

3B, the nitride film 45 is deposited on the entire surface of the semiconductor substrate 40 including the color filter layer 44. Here, the nitride film 45 is preferably formed of SiN, Si 3 N 4, SiON, or the like.

Subsequently, as illustrated in FIG. 3C, the nitride layer 45 is etched through an etch-back to etch to have a zero gap with the color filter layer 44. The gap prevention spacer 45a is formed in between.

Due to this structure, it is possible to suppress the variation in thickness of each filter that may occur at the contact surface of the filter due to the overlap of the blue (B), green (G) and red (R) when forming the existing color filter, To reduce the distance between the microlenses and the photodiode by removing the planarization layer that has been previously formed to planarize, the light collection efficiency can be increased.

Then, as shown in FIG. 3D, the polymer material is formed by adhering the material layer for microlenses onto the color filter layer 44. After the photoresist is coated on the polymer material, the photoresist is patterned by an exposure and development process to define a microlens region. Subsequently, the photoresist film is selectively patterned with a polymer material, which is a material layer for the microlenses, to form a microlens pattern having a size substantially the same as that of the color filter layer 44 while corresponding to the photodiode 41. Then, the microlens pattern is heat-treated by a reflow process to form a microlens 46 having a constant curvature.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the technical spirit of the present invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification but should be defined by the claims.

1A to 1C are cross-sectional views illustrating a method of manufacturing a CMOS image sensor according to the related art.

3A to 3D illustrate a method of manufacturing a CMOS image sensor according to the present invention.

Explanation of symbols on the main parts of the drawings

40: semiconductor substrate 41: photodiode

42: interlayer insulating layer 43: protective film

44: color filter layer 45: nitride film

45a: gap prevention spacer 46: microlens

Claims

A plurality of photodiodes formed on the semiconductor substrate,

An interlayer insulating layer formed on an entire surface of the semiconductor substrate including the photodiode;

A protective film formed on the interlayer insulating layer to protect the device;

A plurality of color filter layers formed on the passivation layer to have a predetermined gap with each other at regular intervals corresponding to the photodiode;

A gap prevention spacer formed in a gap between the respective color filter layers;

And a microlens formed on the color filter layer so as to correspond to the photodiode.

The method of claim 1,

And the interlayer insulating layer includes a light blocking layer for preventing light from being incident.

The method of claim 1,

The gap prevention spacer is formed of SiN, Si3N4 and SiON CMOS sensor.

Forming an interlayer insulating layer on an entire surface of the semiconductor substrate on which the photodiodes are formed;

Forming a protective film on the interlayer insulating layer;

Forming a plurality of color filter layers on the passivation layer to have a predetermined gap with each other at regular intervals corresponding to the photodiode;

Forming a nitride film over the entire color filter layer;

Performing an etch back process on the resultant product including the nitride film to form a gap prevention spacer in a gap between the respective color filter layers;

Forming a microlens pattern defining a microlens region on the front surface of the color filter layer including the gap preventing spacer;

And heat treating the microlens pattern by a reflow process to form a microlens.

The method of claim 4, wherein

The gap preventing spacer is formed of SiN, Si3N4 and SiON method of manufacturing a CMOS image sensor.

The method of claim 4, wherein

The microlens pattern is

And corresponding to the photodiode and having the same size as the color filter layer.