KR20100021228A - Method for manufacturing image sensor of semiconductor device - Google Patents

Abstract

In the conventional image sensor manufacturing method, since the respective color filters are formed with different thicknesses, a flattening layer must be formed to compensate for the thickness difference before proceeding with the microlens process, so that light is applied to the photodiode. There is a problem in that the number of layers that must pass through to reach is increased, resulting in the loss of light. Accordingly, the present invention can improve the sensitivity of a complementary metal-oxide-silicon (CMOS) image sensor by reducing the number of layers that light must pass through the photodiode, and reduce the number of layers required for manufacturing a CMOS image sensor. In order to reduce the overall process period, an image sensor manufacturing method will be prepared.

Description

Method for manufacturing image sensor of semiconductor device {METHOD FOR MANUFACTURING IMAGE SENSOR OF SEMICONDUCTOR DEVICE}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technology for manufacturing an image sensor of a semiconductor device, and more particularly, to a method for manufacturing an image sensor of a semiconductor device suitable for improving the sensitivity of a CMOS (Complementary Metal-Oxide-Silicon) image sensor and reducing a process.

In general, an image sensor is a semiconductor device that converts an optical image into an electrical signal. In a dual charge coupled device (CCD), individual metal-oxide-silicon (MOS) capacitors are very different from each other. A device in which charge carriers are stored and transported in a capacitor while in close proximity. Furthermore, CMOS (Complementary MOS) image sensors use CMOS technology, which uses control circuits and signal processing circuits as peripheral circuits, to make MOS transistors as many as the number of pixels, and to sequentially output them using them. It is a device that adopts a switching method for detecting output.

In manufacturing such various image sensors, efforts are being made to increase the photo sensitivity of the image sensor, and one of them is a light condensing technology. For example, the CMOS image sensor is composed of a light sensing element portion that senses light and a CMOS logic circuit portion that processes the detected light into an electrical signal to make data. Efforts have been made to increase the area occupied (commonly called 'Fill Factor'), but there is a limit to such efforts under a limited area because the logic circuit part cannot be removed.

On the other hand, in the conventional CMOS image sensor manufacturing process to form a metal pad in the logic circuit area and to protect the device from the external moisture and scratches on the resultant to deposit a device protective film and etching it to perform an open process of the metal pad after optical The color filter array is formed in the sensing element region.

Hereinafter, a process of manufacturing a CMOS image sensor according to the prior art will be briefly described with reference to FIGS. 1A to 1G.

In the drawing, reference numeral A denotes a photosensitive device region, and B denotes a logic circuit region.

First, as shown in FIG. 1A, a field insulating film (not shown) and at least one photosensitive device (not shown) and a logic circuit (not shown) are provided between the field insulating films for electrical insulation between the unit pixels of the image sensor. The insulating film 10 is formed on the semiconductor substrate 1 on which the semiconductor substrate 1 is formed.

A metal material is deposited on the entire surface of the resultant and patterned to form a metal pad 102 on the insulating film 10 of the logic circuit region B of the substrate 1. In this case, an anti-reflection film 101 such as titanium nitride (TiN) may be deposited on and under the metal pad 102.

Then, device protection films 104 and 106 are deposited on the entire surface of the resultant metal pad 102 to protect the device from external moisture and scratches. In this case, the device passivation layer may have, for example, a structure in which a TEOS (Tetraethylorthosilicate) thin film 104 and an USG (Undoped Silicate Glass) film 106 are stacked.

Subsequently, as shown in FIG. 1B, the photosensitive device region A is masked and subjected to an etching process to open the device protective layers 106 and 104 and the anti-reflection film 101 by etching to expose a part of the surface of the metal pad 102. Area 108 is formed. At this time, the open area 108 is for exposing the surface of the metal pad 102 to be wire bonded during the packaging process.

Next, as shown in FIG. 1C, the first planarization layer 110 is thinly formed on the device protection layer 106 of the photosensitive device region A in order to overcome the step difference and improve adhesion. The purpose of this first planarization layer 110 is to facilitate the coating of subsequent color filters and to maximize the drive and response of the image sensor.

Subsequently, as shown in FIG. 1D, a color filter array is formed on the first planarization layer 110 in the photosensitive device region A. FIG. At this time, the color filter array manufacturing process is applied to the photoresist dyed on the first planarization layer 110, exposed and developed to a part of the photosensitive device region (A) blue, green, red color filters 112a, 112b, 112c) is formed in the form of an array.

Then, in FIG. 1E, a photoresist (not shown) is applied to the entire surface of the photosensitive device region A on which the color filters 112a, 112b, and 112c are formed, and patterned by exposure and development to color filter 112a, 112b, After the thickening of the second planarization layer 114 in the form surrounding the 112c, the metal pad 102 of the first planarization layer 110 used to smooth the coating of the color filters 112a, 112b and 112c. O ₂ ashing is performed to remove the first planarization layer of the region. At this time, the purpose of coating the second planarization layer 114 is to protect the color filter and the micro lens.

1F, a photoresist (not shown) for forming a microlens is applied and patterned by exposure and development to form a microlens photoresist pattern 116.

Finally, in FIG. 1G, a heat treatment process is performed to reflow the microlens photoresist pattern 116 to form a hemispherical microlens 118 that concentrates light on the second planarization layer 114. Complete the manufacturing process of the CMOS image sensor.

However, in the conventional image sensor manufacturing method, as shown in FIG. 1D, each color filter, that is, blue, green, and red color filters are formed to have different thicknesses. In order to compensate for this problem, a planarization layer must be formed, which increases the number of layers through which light passes through the photodiode, resulting in a loss of light.

As a result, in the conventional process technology, the sensitivity of the CMOS image sensor is inevitably lowered.

Accordingly, the present invention is to provide a method of manufacturing an image sensor that can improve the sensitivity of the CMOS image sensor by reducing the number of layers to pass through the light reaches the photodiode.

In addition, the present invention is to provide an image sensor manufacturing method that can shorten the overall process period by reducing the number of layers required for the CMOS image sensor manufacturing.

According to a preferred embodiment of the present invention, a process of forming a metal pad in a logic circuit region of a semiconductor substrate, a process of depositing a device protective film on an entire surface of the resultant product on which the metal pad is formed, and etching the device protective film Forming an open area in which a part of the surface of the metal pad is exposed, forming a color filter in the photosensitive device region of the semiconductor substrate, and forming a color filter as a hemispherical micro lens by applying a reflow process. It provides a method for manufacturing an image sensor of a semiconductor device comprising a process.

According to the present invention, by reducing the number of layers that light must pass through to the photodiode, the image sensitivity of the CMOS image sensor can be improved and the process can be simplified.

SUMMARY OF THE INVENTION The technical gist of the present invention is to form a color filter in a photosensitive device region of a semiconductor substrate, and to apply a reflow process to the color filter itself to form respective hemispherical microlenses for light concentration, whereby light By reducing the number of layers to reach the diode to improve the image sensitivity of the CMOS image sensor and implement the process simplification, it will be easy to achieve the object of the present invention from this technical idea.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of the present invention.

2A to 2E are cross-sectional views illustrating a process of fabricating an image sensor of a semiconductor device according to a preferred embodiment of the present invention, wherein A represents a photosensitive device region and B represents a logic circuit region.

Hereinafter, a process of manufacturing an image sensor, for example, a CMOS image sensor, according to the present invention will be described in detail with reference to FIGS. 2A to 2E.

First, as shown in FIG. 2A, a field insulating film (not shown) and at least one light sensing element (not shown) and a logic circuit (not shown) are provided between the field insulating films for electrical insulation between unit pixels of the image sensor. The insulating film 20 is formed on the semiconductor substrate 2 on which the semiconductor substrate 2 is formed.

A metal material is deposited on the entire surface of the resultant and patterned to form a metal pad 202 on the insulating film 20 in the logic circuit region B of the substrate 2. In this case, an anti-reflection film 201 such as titanium nitride (TiN) may be deposited on and under the metal pad 202.

Then, device protection layers 204 and 206 are deposited on the entire surface of the resultant metal pad 202 to protect the device from external moisture and scratches. In this case, the device protection layer may have, for example, a structure in which a TEOS (Tetraethylorthosilicate) thin film 204 and an USG (Undoped Silicate Glass) film 206 are stacked.

Subsequently, as shown in FIG. 2B, the photosensitive device region A is masked and an etching process is performed to open the device protective layers 206 and 204 and the anti-reflection film 201 to expose portions of the surface of the metal pad 202. Area 208 is formed. In this case, the open area 208 is for exposing the surface of the metal pad 202 to be wire bonded during the packaging process.

Next, as shown in FIG. 2C, the first planarization layer 210 is thinly formed on the device protection film 206 of the photosensitive device region A in order to overcome the step difference and improve adhesion. The purpose of this first planarization layer 210 is to facilitate the coating of subsequent color filters and to maximize the driving and response of the image sensor.

Subsequently, as shown in FIG. 2D, a color filter array is formed on the first planarization layer 210 of the photosensitive device region A. Referring to FIG. In this case, the color filter array manufacturing process may be performed by applying, exposing and developing the dyed photoresist on the first planarization layer 210 to apply a blue, green, and red color filter 212a to a part of the photosensitive device region A. 212b and 212c) to form an array. As can be seen in FIG. 2, each of the color filters 212a, 212b, and 212c has a different thickness, for example, a green color filter 212b is formed thicker than the blue color filter 212a, and is red than the green color filter 212b. It can be seen that the color filter 212c is formed thicker.

Then, in FIG. 2E, each of the hemispherical microlenses 218a for light aggregation is applied by applying a reflow process to the color filters 212a, 212b, and 212c itself without the process of forming the planarization layer as in the related art. , 218b, 218c.

As can be seen in FIG. 2E, since the direct reflow process is applied to each of the color filters 212a, 212b, and 212c, each hemispherical microlens 218a, 218b, and 218c has its own blue, green, red color. It is characterized by being formed in different thicknesses in proportion to the thickness difference of the color filters (212a, 212b, 212c).

That is, FIG. 2E is the biggest feature of the present embodiment. After the color filters 212a, 212b, and 212c are formed, a reflow process is directly applied to each color filter, without using a planarization layer or an additional mask pattern. It was implemented to form a micro lens.

As a result, the present invention eliminates the need for a flattening layer, a photoresist pattern, and the like, thereby greatly reducing the number of layers, and greatly reducing the total number of layers through which light must pass, thereby minimizing light loss. Could be implemented.

Meanwhile, the embodiments of the present invention have been described in detail, but the present invention is not limited to these embodiments, and various modifications may be made by those skilled in the art within the spirit and scope of the present invention described in the claims below. to be.

1A to 1G are cross-sectional views illustrating a process of manufacturing an image sensor of a conventional semiconductor device;

2A to 2E are cross-sectional views illustrating a process of manufacturing an image sensor of a semiconductor device according to a preferred embodiment of the present invention.

Claims (4)

Forming a metal pad in a logic circuit region of the semiconductor substrate, Depositing a device protection film on the entire surface of the resultant metal pad formed thereon; Etching the device protection layer to form an open area in which a part of the surface of the metal pad is exposed; Forming a color filter in the photosensitive device region of the semiconductor substrate; Process of forming the color filter into a hemispherical micro lens by applying a reflow process Image sensor manufacturing method of a semiconductor device comprising a. The method of claim 1, Forming the color filter, Applying a dyed photoresist to the photosensitive device region of the semiconductor substrate; Exposing and developing the photoresist to form blue, green, and red color filters in an array form on a part of the photosensitive device region, respectively. Image sensor manufacturing method of a semiconductor device comprising a. The method of claim 2, Each of the blue, green, and red color filters is formed with a different thickness from each other. The method of claim 2, The hemispherical microlenses are formed with different thicknesses in proportion to the thickness differences of the respective blue and green red color filters.

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