KR100902597B1 - Method for Fabricating of CMOS Image Sensor - Google Patents

Abstract

The present invention relates to a method for preventing blue color filter (BCF) peeling and improving image characteristics, in particular, in a CMOS image sensor.

According to the present invention, there is provided a CMOS image sensor manufacturing method comprising: sequentially forming an insulating layer including a plurality of metal wirings and a passivation layer on a substrate including a photodiode, and a front surface of the passivation layer. Applying a resist for positive type Blue Color Filter on the surface, forming a blue color filter through a photo process, and negative on the entire passivation layer including the blue color filter. After applying a resist for the (negative) type Green Color Filter, and forming a green color filter through a photo process, a negative red color filter on the entire passivation layer including the blue and green color filter After applying the resist for the (Red Color Filter), forming a red color filter through a photo process and the flat on the blue, green and red color filter It comprises forming a hwacheung and microlenses.

Photolithography, Photolithography, Color Filters, CMOS Image Sensors

Description

MOS Image Sensor Manufacturing Method {Method for Fabricating of CMOS Image Sensor}

The present invention relates to a method of forming a color filter of a CMOS image sensor, in particular.

In general, an image sensor is a semiconductor device that converts an optical image into an electrical signal, and a charge coupled device (CCD) is located at a position where individual metal-oxide-silicon (MOS) capacitors are very close to each other. Charge carriers are stored and transported in capacitors, and CMOS image sensors use a CMOS technology that uses a control circuit and a signal processing circuit as peripheral circuits. It is a device that adopts a switching method that makes transistors and sequentially detects output using them.

The color filter array process applied to the image sensor is a technology for implementing a color image by arranging three color filters including blue, green, and red on a CMOS or CCD substrate. In this case, three photo processes, that is, a lithography process, are applied to form the three color filter array. Then, the resist for forming the color filter of the three colors is a negative resist.

However, as described above, the reason why the depth of each trench is different in the first to third trenches corresponding to the blue, green, and red pixels is that the penetration depth is different depending on the wavelength of light.

In general, the thickness of the color filter is required by the individual device characteristics. In order for the image sensor to have sufficient chromaticity, it is necessary to form a color filter of sufficient thickness. If the thickness of the color filter becomes thick, the exposure light may not reach the bottom of the resist sufficiently, and thus, the stable patterning process may not be performed.

Therefore, when the thickness of the color filter becomes thick and the exposure light does not sufficiently reach the bottom portion of the resist, there is a problem that pattern lifting occurs.

Disclosure of Invention An object of the present invention is to provide a method for manufacturing a CMOS image sensor which prevents a peeling phenomenon of a blue color filter (BCF) pattern generated when a color filter is formed. will be.

In addition, to provide a CMOS image sensor manufacturing method for improving the characteristics of the image sensor by widening the pattern area of the blue color filter.

One aspect of the CMOS image sensor manufacturing method according to an embodiment of the present invention for achieving the above object is an insulating layer, passivation provided with a plurality of metal wiring on a substrate having a photodiode (photo diode) Forming a passivation layer in sequence, applying a resist for a positive type blue color filter on the entire surface of the passivation layer, and then forming a blue color filter through a photographic process. Step, after applying a resist for the negative type (Green Color Filter) on the entire passivation layer including the blue color filter, and forming a green color filter through a photo process, the blue and green After applying a resist for a negative red color filter on the entire passivation layer including the color filter, the red color filter is formed through a photographic process. The method comprising and is formed by forming a planarization layer, and a microlens on the blue, green and red color filter.

More preferably, the insulating layer is either a USG (Undoped Silicate Glass) film or a FUSG (Fluorine doped Silicate Glass) film.

More preferably, the insulating layer has a metal wiring provided therein includes a metal wiring for driving the image sensor and a metal wiring for driving the logic circuit.

More preferably, the passivation layer is a silicon nitride film deposited by plasma-enhanced chemical vapor deposition (PECVD).

More preferably, after the passivation layer is formed, the method may further include performing an annealing process.

More preferably, the exposure for the photo process is done using an i-line of 365 nm wavelength.

More preferably, a reticle is used as the exposure mask for the photographic process.

As described above, the color filter forming method of the CMOS image sensor according to the present invention, by mixing the negative and positive resist in the photo process for forming a color filter, filling the blue color filter (Blue Color Filter (BCF)) There is an effect that can prevent (peeling) phenomenon.

In addition, as the TR treatment process, which has been additionally performed to prevent the peeling phenomenon of the blue color filter, is reduced, the semiconductor manufacturing process and the manufacturing cost can be reduced.

In addition, the light absorption rate of the BCF having a wide bottom portion is increased, thereby improving the sensitivity and image characteristics of the image sensor.

Hereinafter, with reference to the accompanying drawings illustrating the configuration and operation of the embodiment of the present invention, the configuration and operation of the present invention shown in the drawings and described by it will be described by at least one embodiment, By the technical spirit of the present invention described above and its core configuration and operation is not limited.

1A to 1B are graphs showing light absorption and light transmittance according to color. In the present invention, an i-line having a wavelength of 365 nm is used during resist exposure.

First, Figure 1 is a graph showing the light absorption of the resist according to the color, it can be seen that the i-line absorption in blue corresponding to 350nm is significantly high.

And, Figure 2 is a graph showing the light transmittance of the resist according to the color filter color, it can be seen that the i-line transmittance in red is remarkably high.

2A to 2C are photographs showing a result of performing a photolithography process of a resist according to a color filter color according to the related art.

2A is a result of performing a photo process of the red color filter resist, FIG. 2B is a result of performing a photo process of the green color filter resist, and FIG. 2C is a result of performing a photo process of the blue color filter resist.

In the case of the red color filter resist, since the light absorption rate is low and the light transmittance is high, as a result of performing the photographic process, the lower end portion is wider than the upper end portion as shown in FIG. 2A. In addition, in the case of the blue color filter resist, since the light transmittance is low and the light absorption is high, light does not reach the lower end of the resist as a result of performing the photolithography process. Therefore, as shown in Figure 2c, the lower end of the resist is formed in a narrower form than the upper end. In addition, in the case of the resist for green color filters, as shown in FIG. Therefore, it can be seen that the resist is formed differently according to the wavelength of light.

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

First, as illustrated in FIG. 3A, an insulating layer 20 and a passivation layer (eg, a plurality of metal lines 21, 22, and 23) are provided on a substrate 10 having a photodiode 12. 30), the blue color filter resist 51 is applied on the passivation layer 40, and then exposed using the first reticle A1.

In this case, the insulating layer 20 may be any one of a USG (Undoped Silicate Glass) film or a FUSG (Fluorine doped Silicate Glass) film, and the insulating layer 20 has a metal wiring provided therein to drive the image sensor. Metal wiring, and metal wiring for driving a logic circuit.

The passivation layer 40 is a silicon nitride film deposited by a plasma-enhanced chemical vapor deposition (PECVD) method. After the deposition of the nitride film, an annealing process is performed to cure the nitride film.

In addition, the blue color filter resist 51 is a positive type and has a property opposite to that of a negative type resist that has been used.

When the positive type blue color filter resist 51 subjected to the exposure is developed, as shown in FIG. 3B, a portion that receives light during exposure is removed by a developer in a subsequent developing process to form a blue color filter 61. do.

Then, as shown in Figure 3c, after applying a resist (52) for the negative green color filter (Green Color Filter) on the passivation layer 40 including the blue color filter 61 The exposure is performed using the second reticle A2. Then, when the developing process is performed, as shown in FIG. 3D, the green color filter 62 is formed.

As shown in FIG. 3E, a resist 53 for a negative red color filter on the entire surface of the passivation layer 40 including the blue color filter 61 and the green color filter 62. ) Is applied and then exposed using a third reticle A3. Then, when the developing process is performed, as shown in FIG. 3F, a red color filter 63 is formed.

When the formation of the three color filters 61, 62 and 63 is completed in the same manner as described above, as shown in FIG. 3G, according to a known technique on the color filters 61, 62 and 63 of the three colors. , The planarization layer 60 and the microlens 70 are formed.

4a to 4b are photographs showing the results of performing a photographic process of the blue color filter resist according to the prior art and the present invention.

Figure 4a shows the result of performing a photo process on the blue color filter resist according to the prior art, 4b is the result of performing a photo process on the blue color filter resist according to the present invention.

Comparing FIGS. 4A and 4B, it can be seen that the lower end of the resist of FIG. 4B is much wider than the resist of FIG. 4A.

As described above, when the blue color filter is formed according to the present invention, as shown in 4b, the lower end portion of the blue color filter is wider to increase the light absorption rate of the blue color filter, thereby improving the sensitivity and image characteristics of the image sensor. There are advantages to it.

Although specific embodiments of the present invention have been described with reference to the drawings, this is intended to be easily understood by those of ordinary skill in the art and is not intended to limit the technical scope of the present invention. Therefore, the technical scope of the present invention is determined by the matters described in the claims, and the embodiments described with reference to the drawings may be modified or modified as much as possible within the technical spirit and scope of the present invention.

1A to 1B are graphs showing light absorption and light transmittance according to color;

Figure 2a to 2c is a photograph showing the results of performing a photo process of the resist according to the color filter color according to the prior art.

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

Figures 4a to 4b is a photograph showing the results of performing the photo process of the blue color filter resist according to the prior art and the present invention.

Claims (7)

Sequentially forming an insulating layer having a plurality of metal wirings and a passivation layer on a substrate having a plurality of photo diodes; Applying a resist for a positive type blue color filter on the entire surface of the passivation layer, and then forming a blue color filter in a region corresponding to the photodiode through a photo process; After applying a resist for a negative green color filter on the entire passivation layer including the blue color filter, the photodiode corresponds to the photodiode on the same layer as the blue color filter. Forming a green color filter in the region; After applying a resist for a negative red color filter on the entire passivation layer including the blue and green color filters, the photodiode and the photodiode correspond to the same layer as the blue and green color filters through a photo process. Forming a red color filter in the region; And Forming a planarization layer and a microlens on the blue, green, and red color filters. The method of claim 1, The insulating layer is a method of manufacturing a CMOS image sensor, characterized in that any one of the USG (Undoped Silicate Glass) film or FUSG (Fluorine doped Silicate Glass) film. The method of claim 1, The insulating layer is a metal wiring provided inside the CMOS image sensor manufacturing method characterized in that it comprises a metal wiring for driving the logic circuit and a metal wiring for driving the image sensor. The method of claim 1, The passivation layer is a CMOS image sensor, characterized in that the silicon nitride film deposited by a plasma-enhanced chemical vapor deposition (PECVD) method. The method of claim 1, And forming an passivation layer and then performing an annealing process. The method of claim 1, Exposure for the photographic process is a CMOS image sensor manufacturing method characterized in that using the i-line of 365nm wavelength. The method of claim 1, Method of manufacturing a CMOS image sensor, characterized in that to use a reticle (reticle) as the exposure mask for the photographic process.

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