KR101015527B1 - CMOS Image sensor and Method for fabricating of the same - Google Patents

Abstract

The present invention relates to a method for manufacturing a CMOS image sensor that can increase the light collecting efficiency of the photodiode,

The CMOS image sensor according to the present invention comprises a plurality of photodiodes formed on a semiconductor substrate, an interlayer insulating layer formed on the front surface of the semiconductor substrate including the plurality of photodiodes, and formed to protect devices on the interlayer insulating layer. A passivation layer, red, green, and blue color filter layers formed on the passivation layer at regular intervals corresponding to the plurality of photodiodes, a planarization layer formed on an entire surface of the red, green, and blue color filter layers; The semiconductor substrate includes a formed microlens, and the semiconductor substrate has a step of increasing thickness in an order corresponding to regions of the color filter layers of red, green, and blue.

Semiconductor Substrate, Photodiode, Color Filter Layer

Description

CMOS Image sensor and Method for Fabrication of the same

The present invention relates to a CMOS image sensor, and more particularly to a method for manufacturing a CMOS image sensor that can increase the light collecting efficiency of the photodiode.

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.

1 is a process cross-sectional view showing a CMOS image sensor according to the prior art.

As shown in FIG. 1, the CMOS image sensor according to the related art includes at least one semiconductor substrate 10 having at least one photodiode 12 formed thereon and generating a charge according to an amount of incident light, and a plurality of metal wirings ( An interlayer insulating layer 14 formed on the entire surface of the semiconductor substrate 10, a planarization protective film 16 formed on the interlayer insulating layer 14 to protect the device from moisture and scratches, and a protective film. The color filter layer 18 which filters light for each wavelength band formed by applying a coating salt and a patterning process using a salty resist on the 16 and the focal length control and the lens layer are formed on the color filter layer 18. The planarization layer 20 formed to be flattened to secure flatness and the material layer for microlenses formed on the planarization layer 20 are heat-treated by a reflow process to have a constant curvature. And formed microlenses 22.

However, the conventional CMOS image sensor focuses the light collected from the microlenses through the color filter and the interlayer insulating film to the photodiode of the light receiving unit, although the focal lengths of the red, green, and blue color filters are different due to the difference in refractive index of the light. Since the distance between the microlens and the photodiode is constant, the shorter the wavelength, the lower the light collection efficiency.

Accordingly, an object of the present invention is to provide a method for manufacturing a CMOS image sensor that can increase the light collecting efficiency of the photodiode.

According to the present invention, a method of manufacturing a CMOS image sensor may be performed by selectively etching a semiconductor substrate in order of increasing thickness of the semiconductor substrate in order of corresponding color filter layer regions of red, green, and blue, and the red, green, and blue colors. Forming photodiodes in each of the semiconductor substrates corresponding to the color filter layer region of the substrate; forming an interlayer dielectric layer on the entire surface of the semiconductor substrate including the photodiodes; and forming a protective film on the interlayer dielectric layer. Forming a color filter layer on the passivation layer at regular intervals corresponding to the photodiodes, respectively, and forming a planarization layer on the red, green, and blue color filter layers. And forming a microlens on the entire surface of the planarization layer. Shall be.

The CMOS image sensor according to the present invention comprises a plurality of photodiodes formed on a semiconductor substrate, an interlayer insulating layer formed on the front surface of the semiconductor substrate including the plurality of photodiodes, and formed to protect devices on the interlayer insulating layer. A passivation layer, red, green, and blue color filter layers formed on the passivation layer at regular intervals corresponding to the plurality of photodiodes, a planarization layer formed on an entire surface of the red, green, and blue color filter layers; The semiconductor substrate includes a formed microlens, and the semiconductor substrate has a step of increasing thickness in an order corresponding to regions of the color filter layers of red, green, and blue.

As described above, the CMOS image sensor according to the present invention can appropriately control the distance between the microlens and the photodiode by forming the inclined photodiode, thereby increasing the light collection efficiency of the photodiode to improve color reproduction and The fall of color contrast ratio can be suppressed effectively.

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 of a CMOS image sensor according to the present invention.

As shown in FIG. 2, the CMOS image sensor according to the present invention includes an interlayer insulating layer 52 formed on the entire surface of the semiconductor substrate 50 on which the photodiode 48 is formed, and a protective film formed on the interlayer insulating layer 52. 54, a blue, green and red color filter layer 56 formed on the passivation layer 54, a planarization layer 58 formed on the color filter layers 56, and a microlens formed on the entire surface of the planarization layer 58. 60, the semiconductor substrate 50 is characterized by having a different thickness for each region of the red (R), blue (B) and green (G) color filter 56 layer.

The semiconductor substrate 50 is characterized in that the thickness increases in the order of the red (R), green (G), and blue (B) color filter layer 56 region.

The microlens 60 is characterized in that the distance between the photodiode 48 is shortened in order of red (R), green (G), and blue (B) color filter layer 56 region.

3A to 3C are cross-sectional views illustrating a method of manufacturing the CMOS image sensor according to the present invention.

First, as shown in FIG. 3A, the semiconductor substrate 50 is selectively etched to have a different thickness for each of the regions of the red (R), green (G), and blue (B) color filter layers 56. In this case, the semiconductor substrate 50 may be etched so that the thickness becomes thick in order of the red (R), green (G), and blue (B) color filter layers 56.

Thereafter, as shown in FIG. 3B, the photodiode 48 generates charges according to the amount of light incident on the red (R), green (G), and blue (B) color filter layers 56 in the semiconductor substrate 50. ), And the interlayer insulating layer 52 is formed on the entire surface of the semiconductor substrate 50 including the photodiode 48.

Here, the interlayer insulating layer 52 may be formed in multiple layers, and after forming one interlayer insulating layer 52, a light shielding layer (not shown) for preventing light from being incident on portions other than the photodiode 48. After forming the interlayer insulating layer 52 may be formed again.

A planarized protective film 54 is then formed on the interlayer insulating layer 52 to protect the device from moisture and scratches. In addition, a coating process and a patterning process are performed on the protective layer 54 using a salt resist to form the red (R), green (G), and blue (B) color filter layers 56.

Then, as shown in FIG. 3C, the planarized planarization layer 58 is formed on the color filter layer 56 for adjusting the focal length and securing the flatness for forming the lens layer. The microlens region is defined by attaching a polymer material to the planarization layer 58 using a microlens material layer, applying a photoresist film on the polymer material, and then etching the photoresist film by an exposure and development process. Thereafter, the photoresist film is selectively etched to form a microlens material layer that corresponds to the photodiode 48 to form a microlens pattern having a size substantially the same as that of the color filter layer 56. Thereafter, the microlens pattern is heat-treated by a reflow process to form a microlens 60 having a constant curvature.

Accordingly, in the CMOS image sensor according to the present invention, as shown in FIG. 3C, the distance between the microlens 60 and the photodiode 48 is shortened in the order of red, green, and blue color filter layer regions 56. The light condensing efficiency of the photodiode 48 for each area can be increased to effectively suppress color reproducibility and a decrease in color contrast ratio.

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.

1 is a process cross-sectional view showing a CMOS image sensor according to the prior art.

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

3A to 3C are cross-sectional views illustrating a method of manufacturing the CMOS image sensor according to the present invention.

Claims (10)

Selectively etching the semiconductor substrate to have a step thickness in which the thickness of the semiconductor substrate becomes thick in an order corresponding to the color filter layer regions of red, green, and blue, respectively; Forming photodiodes in each of the semiconductor substrates corresponding to the color filter layer regions of the red, green, and blue colors; Forming an interlayer insulating layer on an entire surface of the semiconductor substrate including the photodiodes; Forming a protective film on the interlayer insulating layer; Forming color filter layers of red, green, and blue on the passivation layer at regular intervals corresponding to the photodiodes; Forming a planarization layer on the red, green, and blue color filter layers; And forming a microlens on the entire surface of the planarization layer. delete delete delete The method of claim 1, The distance between the micro lens and the photodiodes is And the red, green and blue color filter layers are shortened in order. A plurality of photodiodes formed on the semiconductor substrate, An interlayer insulating layer formed on an entire surface of the semiconductor substrate including the plurality of photodiodes; A protective film formed on the interlayer insulating layer to protect the device; A red, green, and blue color filter layer formed on the passivation layer at regular intervals corresponding to the plurality of photodiodes; A planarization layer formed over the red, green and blue color filter layers; It includes a micro lens formed on the planarization layer, The semiconductor substrate has a CMOS image sensor, characterized in that it has a step thickness becomes thick in the order corresponding to the color filter layer region of the red, green and blue. delete delete delete The method of claim 6, The distance between the micro lens and the photodiode is And the red, green, and blue color filter layers are shortened in order.

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