KR20090053312A - Method for forming a color filter and method for manufacturing an image sensor using for the same - Google Patents

Abstract

In the color filter forming method and the image sensor manufacturing method using the same, in order to form the color filter, a preliminary color filter layer in which a plurality of metal oxide films and a plurality of silicon oxide films interposed between the metal oxide films are stacked is formed on a substrate. do. The preliminary color filter layer is heat-treated to form a color filter layer such that a difference in refractive index between the metal oxide layers and the silicon oxide layers is increased. By increasing the refractive index between the metal oxide film and the silicon oxide film through the heat treatment, it is possible to manufacture a color filter having high transmittance and improved color mixing and sensitivity.

Description

Method for forming a color filter and method for manufacturing an image sensor using for the same}

The present invention relates to a color filter forming method and an image sensor manufacturing method using the same. More specifically, the present invention relates to a color filter forming method comprising an inorganic material and a method of manufacturing an image sensor using the same.

Recently, the digital revolution is progressing rapidly, and one of the representative products is the digital camera. Key factors that determine the quality of digital cameras are optical lenses and image sensors. The light from the lens is converted into an electrical signal by the image sensor to achieve good image quality.

A typical image sensor is composed of a pixel array, i.e., a plurality of pixels arranged in a matrix, each pixel having a photodiode that generates signal charges by incident photons and a signal charge generated by the photodiodes. An element for transferring and outputting. According to the transfer and output method of the signal charge, the image sensor is largely divided into two types: a charge coupled device (CCD) type image sensor and a complementary metal oxide semiconductor (CMOS) type image sensor.

The image sensor collects light over photodiodes disposed in each pixel through a color filter, converts them photoelectrically, converts them into image information, and divides them into fine pixels. Therefore, as a result of the photoelectric transformation, as the voltage value (sensitivity) generated from each pixel becomes uniform, it is possible to reproduce a more realistic image by the image information. Here, the color filter has a shape in which filter patterns for transmitting light having wavelengths of red, green, and blue, respectively, are arranged in an array form.

However, in order to have uniform sensitivity and high light efficiency for each pixel, it is preferable that the light transmittance is very high in the filter patterns for selectively transmitting the light having the wavelengths of red, green, and blue. In addition, each of the red, green, and blue filter patterns preferably transmits only light within a wavelength range of red, green, and blue in the light incident on each filter.

Each of the color filters is formed of an organic material such as a photoresist material. However, when using the respective filter patterns formed of the organic material, it is not easy to transmit only light in the wavelength range of red, green, and blue. That is, the wavelength range to be transmitted in each of the filter patterns and the light in the wavelength range adjacent to each other are transmitted through each other, thereby causing crosstalk in the color filter.

In addition, the transmittance of light in each of the filter patterns is not high, and when sufficient light is not incident from the outside, the amount of light reaching the photodiode is reduced, making it difficult to reproduce a desired image.

In order to reduce the problems, recently, a method of forming the filter patterns using inorganic materials has been studied and published. An example of a filter pattern formed using the inorganic material is disclosed in Korean Patent No. 680386. In the case of the color filter having the inorganic filter patterns, the light transmittance is high and there is little wavelength portion that is repeatedly transmitted in each color filter, thereby reducing the occurrence of mixed color. However, since the wavelength range transmitted in each of the filter patterns is too narrow, a wavelength range that cannot be transmitted is generated so that problems such as low sensitivity remain.

Therefore, in order to obtain an image having a high resolution, a color filter that not only has high light transmittance but also improves sensitivity is required.

An object of the present invention is to provide a method of forming an inorganic color filter having high transmittance, reduced color mixing and improved sensitivity.

Another object of the present invention is to provide a method of manufacturing an image sensor including the inorganic color filter.

In the method of manufacturing a color filter according to an embodiment of the present invention for achieving the above object, a preliminary color filter layer in which a plurality of metal oxide films and a plurality of silicon oxide films interposed between the metal oxide films are stacked on a substrate. To form. Next, the preliminary color filter layer is heat-treated to form a color filter layer such that a difference in refractive index between the metal oxide layers and the silicon oxide layers is increased.

According to an embodiment of the present invention, the metal oxide films include titanium oxide.

According to an embodiment of the present invention, after the preliminary color filter layer is formed, patterning the preliminary color filter layer is further performed.

According to an embodiment of the present invention, the lowermost layer and the uppermost layer of the ebi color filter layer are formed of a metal oxide film.

According to an embodiment of the present invention, the metal oxide films have different thicknesses in each layer.

According to one embodiment of the invention, the heat treatment is performed for 1 to 30 minutes at a temperature of 400 to 600 ℃.

According to one embodiment of the invention, the heat treatment is performed under one atmosphere selected from the group consisting of N ₂ , O ₂ , N ₂ O, NH ₃ and O ₃ .

According to an embodiment of the present invention, ultraviolet rays are irradiated during the heat treatment process.

According to an embodiment of the present invention, after the color filter layer is formed, the color filter layer is patterned.

In the manufacturing method of the image device according to an embodiment of the present invention for achieving the above object, a photodiode is formed on a substrate. An interlayer insulating film structure is formed to cover the photodiode. On the interlayer insulating film structure, a preliminary color filter structure is formed by sequentially stacking a metal oxide film and a silicon oxide film. The preliminary color filter structure is heat-treated to form a first color filter such that a difference in refractive index between the metal oxide layers and the silicon oxide layers is increased. Next, a micro lens is formed on the first color filter.

According to an embodiment of the present invention, the metal oxide films include titanium oxide.

According to an embodiment of the present invention, the metal oxide films each have a thickness of 300 to 2000 kPa.

According to an embodiment of the present invention, the metal oxide films and the silicon oxide films have different thicknesses for each layer.

According to an embodiment of the present invention, the preliminary color filter structure is patterned to form a preliminary color filter.

According to an embodiment of the present invention, the preliminary color filter is selectively formed in the filter region transmitting the green wavelength region.

According to an embodiment of the present invention, the method may further include patterning the first color filter such that the first color filter is selectively formed in the filter region transmitting the green wavelength region.

According to one embodiment of the present invention, after the first color filter is formed, the second and third color filter patterns made of organic materials and transmitting red and blue wavelength regions are formed on the interlayer insulating film structure, respectively. You can perform more steps.

In the method of manufacturing an image device according to another embodiment of the present invention for achieving the above object, a photodiode is formed on a substrate. An interlayer insulating film structure is formed to cover the photodiode. Preliminary first to third colors sequentially depositing a metal oxide film and a silicon oxide film on the first to third regions on the interlayer insulating film structure, and having different thicknesses of the silicon oxide film for each region to transmit light having different wavelengths. Form a filter. The preliminary first to third color filters are heat-treated to form a first to third color filter such that a difference in refractive index between the metal oxide layers and the silicon oxide layers is increased. Next, micro lenses are formed on the first to third color filters.

As described, the difference in refractive index between the metal oxide films and the silicon oxide films included in the color filter is increased. Thereby, the color filter according to the present invention has high light transmittance and improved sensitivity.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

With respect to the embodiments of the present invention disclosed in the text, specific structural to functional descriptions are merely illustrated for the purpose of describing embodiments of the present invention, embodiments of the present invention may be implemented in various forms and It should not be construed as limited to the embodiments described in.

As the inventive concept allows for various changes and numerous embodiments, particular embodiments will be illustrated in the drawings and described in detail in the text. However, this is not intended to limit the present invention to the specific disclosed form, it should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention.

Example 1

1 and 2 are cross-sectional views for explaining a color filter forming method according to Embodiment 1 of the present invention.

Referring to FIG. 1, the preliminary color filter structure 116 is formed by repeatedly depositing the titanium oxide layers 102, 106, 110, and 114 and the silicon oxide layers 104, 108, and 112 on the substrate 100. In this case, the lowermost layer and the uppermost layer of the preliminary color filter structure 116 may be formed of titanium oxide layers 102 and 114 having a high refractive index. This reduces reflection of light incident from the outside into the color filter, and allows light transmitted through the color filter to reach the photodiode (not shown) facing the color filter, thereby capturing high quality images. To make it work.

The titanium oxide films 102, 106, 110, and 114 are dielectric thin films having a high refractive index of about 2.5, and the silicon oxide films 104, 108, and 112 are selected as dielectric thin films having a low refractive index of about 1.5. As described above, the preliminary color filter structure 116 has a structure in which a dielectric thin film having a high refractive index and a dielectric thin film having a low refractive index are laminated with each other, and the thin film included in the preliminary color filter structure 116 satisfies this. It may also be replaced by a thin film (for example, a laminated structure of a silicon nitride film and a silicon oxide film).

The titanium oxide layers 102, 106, 110, and 114 of each layer may have different thicknesses or may have the same thickness. The titanium oxide films 102, 106, 110 and 114 of each layer preferably have a thickness in the range of 300 to 2000 microseconds.

In addition, the silicon oxide layers 104, 108, and 112 of each layer may have different thicknesses or may have the same thickness. The silicon oxide films 104, 108 and 112 of each layer preferably have a thickness in the range of 400 to 2000 microseconds.

The titanium oxide films 102, 106, 110, and 114 and the silicon oxide films 104, 108, and 112 may have a thickness corresponding to a multiple of λ / 4. At this time, the set center wavelength may be selected within a range of about 490 to 570 nm, and more preferably, 550 nm. As such, the titanium oxide films 102, 106, 110, and 114 and the silicon oxide films 104, 108, and 112 have a thickness corresponding to a multiple of lambda / 4 so that the finished color filter can transmit light having a green wavelength. Can be.

Alternatively, by adjusting the deposition thickness of the silicon oxide film 108 positioned at the central portion of the preliminary color filter structure 116, a color filter for transmitting light having a red or blue wavelength may be formed.

As shown, the preliminary color filter structure 116 of the present embodiment may include a first titanium oxide film 102, a first silicon oxide film 104, a second titanium oxide film 106, a second silicon oxide film 108, and a second silicon oxide film 108. The third titanium oxide film 110, the third silicon oxide film 112, and the fourth titanium oxide film 114 are stacked. However, the preliminary color filter structure 116 may be formed of any structure in which the first through n-th titanium oxide films and the first through n-th silicon oxide films are repeatedly stacked.

In addition, in the present embodiment, the titanium oxide films 102, 106, 110, and 114 are separated from the silicon oxide film (ie, the second silicon oxide film) located at the center of the preliminary color filter structure 116. The thicknesses of the oxide films 104, 108, and 112 are made thicker.

The titanium oxide films 102, 106, 110, and 114 may be formed by atomic layer deposition or physical vapor deposition. Among the physical vapor deposition methods, sputtering or ion beam deposition may be used.

In addition, the silicon oxide films 104, 108, and 112 may be formed by atomic layer deposition, chemical vapor deposition, spin coating, or physical vapor deposition. More specifically, the silicon oxide films 104, 108, and 112 may include PE-TEOS, HDP oxide films, and fluidized oxide films.

Referring to FIG. 2, the preliminary color filter structure 116 is heat treated to form the color filter 120.

When the preliminary color filter structure 116 is heat-treated, the heat-treated titanium oxide layers 102a, 106a, 110a, and 114a have an increased refractive index. This is because the titanium oxide films 102a, 106a, 110a, and 114a become phase change by the heat treatment. Specifically, in the deposited state of the titanium oxide film, it has an amorphous or amorphous and anatase mixed phase. However, when the deposited titanium oxide film is heat treated, crystallization is performed to generate a rutile phase, whereby the heat treated titanium oxide films 102a, 106a, 110a, and 114a have a mixed rutile and anatase phase. . The titanium oxide film having the rutile phase is higher in density and has a higher refractive index than the titanium oxide film having an amorphous or anatase phase. Therefore, the refractive indexes of the heat treated titanium oxide films 102a, 106a, 110a, and 114a also increase.

In contrast, the heat-treated silicon oxide films 104a, 108a, 112a have a lower refractive index than the silicon oxide film in a deposited state.

Although a large number of hydrogens are bonded to the silicon oxide film in the deposited state, hydrogen is removed by heat treatment, so that only Si-O bonds remain mainly in the heat-treated silicon oxide films 104a, 108a, and 112a, and the film quality becomes dense. However, the refractive index of the case where hydrogen is not included in the silicon oxide film is lower than that when hydrogen is included in the silicon oxide film. Therefore, the heat-treated silicon oxide films 104a, 108a, 112a are considered to have a lower refractive index than the silicon oxide films 104, 108, 112 in the deposited state.

As described above, when the heat treatment process is performed, the difference in refractive index between the titanium oxide films 102a, 106a, 110a and 114a and the silicon oxide films 104a, 108a and 112a is greatly increased. As such, when the refractive index difference is increased, light of a specific wavelength may be transmitted with a very high transmittance. In addition, the inclination of both sides becomes more steep in the transmission spectrum, thereby reducing the occurrence of mixed color.

In addition, when the heat treatment is performed, the stress characteristics of the titanium oxide films 102a, 106a, 110a and 114a and the silicon oxide films 104a, 108a and 112a are changed.

Specifically, in the state where the titanium oxide film is deposited by ion beam deposition, the titanium oxide film has a compressive stress, whereas after the heat treatment, the titanium oxide film has a compressive stress. In contrast, the silicon oxide film has the same compressive stress in the state in which the silicon oxide film is deposited by ion beam deposition and after the heat treatment. However, after performing the heat treatment, the numerical value of the compressive stress of the silicon oxide film is slightly reduced. Therefore, the titanium oxide films 102a, 106a, 110a and 114a and the silicon oxide films 104a, 108a and 112a on which the heat treatment is performed have different stress characteristics.

As such, the stress is relaxed as a whole when thin films having compressive and tensile stress are repeatedly stacked. Therefore, even if the total thickness of the color filter becomes very thick because the number of stacked layers of the titanium oxide films 102a, 106a, 110a and 114a and the silicon oxide films 104a, 108a and 112a is increased, the thin film due to stress is damaged or the characteristics thereof are poor. Can be reduced.

On the other hand, as the heat treatment temperature is higher, the difference in refractive index between the titanium oxide films 102a, 106a, 110a and 114a and the silicon oxide films 104a, 108a and 112a increases. However, when the heat treatment temperature is increased, damage may be applied to the structure formed below. Therefore, the heat treatment process is preferably carried out at a temperature of 400 to 800 ℃. In particular, when the metal wiring is formed in the lower portion, it is preferable to heat-treat at a temperature of 400 to 600 ° C. so that the metal wiring does not melt or be damaged.

In addition, when the heat treatment process is performed for 30 minutes or more, a thermal budget may be generated. When the heat treatment process is performed for 1 minute or less, sufficient heat treatment may not be performed to change the refractive index of the thin film. Therefore, the heat treatment process may be performed for 1 to 30 minutes. On the other hand, when the heat treatment temperature is low, the heat treatment time may be increased, and when the heat treatment temperature is high, the heat treatment time may be reduced.

When performing the heat treatment process, the atmosphere gas may be introduced. The atmosphere gas includes oxygen (O ₂ ), ozone (O ₃ ), nitrogen (N ₂ ), N ₂ O, HN ₃ gas, or the like.

In addition, UV radiation may be performed when the heat treatment process is performed. In particular, when the ultraviolet rays are irradiated when the heat treatment process is performed while the oxygen or ozone gas is introduced, oxygen or ozone is separated into O atoms by ultraviolet rays, thereby providing oxygen to the silicon oxide film. Therefore, the hydrogen contained in the silicon oxide film is released and the oxygen bond is made, the refractive index is lowered. In addition, the oxygen oxide may be replenished in the titanium oxide film, thereby increasing the refractive index.

The color filter formed by performing the above process is not only formed of an inorganic material, but also has a very large difference in refractive index between the stacked thin films, thereby reducing problems such as color mixing while having a very high transmittance for transmitting light having a specific wavelength.

Example 2

3 to 8 are cross-sectional views illustrating a method of manufacturing an image sensor according to a second exemplary embodiment of the present invention.

Referring to FIG. 3, first, a substrate 200 for manufacturing an image sensor is prepared. Examples of the substrate include a silicon substrate, a silicon on insulator (SOI) substrate, a gallium arsenide substrate, a silicon germanium substrate, a ceramic substrate, a quartz substrate, or a glass substrate for a display.

A field oxide film (not shown) is formed on the substrate 200 to define an active region. Receiving elements such as photodiode 202 are formed on the surface of the active region, and transistors (not shown) which are switching elements of the photodiode 202 are formed.

The lower insulating layer 204 is formed to cover the substrate 100 on which the photodiodes are formed. The lower insulating layer 204 may be formed of a transparent material. Silicon oxide or the like may be used as the transparent material that may be used for the lower insulating layer 204. A contact plug 206 is formed in the lower insulating layer 204 to be connected to the source / drain regions of the transistor.

Next, a first interlayer insulating film 210 is formed, and a first contact plug 212 is formed inside the first interlayer insulating film 210. Thereafter, a first conductive line 214 connected to the first contact plug 212 is formed. The first contact plug 212 and the first conductive line 214 may be made of a metal material. Specifically, the first contact plug 212 and the first conductive line 214 may be made of a material such as aluminum, copper, tungsten, and the like, and these may be used alone. In addition, a process of forming a barrier metal film (not shown) to surround the surface of the metal material may be further involved.

Next, the process of forming the interlayer insulating film, the contact plug and the conductive line is repeatedly performed to form the interlayer insulating film structure having the multi-layered wiring. In the present embodiment, only the first interlayer insulating film and one layer of wiring are included, but the number of the wirings can be increased according to the design of the image device.

Thereafter, a second interlayer insulating layer 216 for planarization is formed on the first interlayer insulating layer 210.

Referring to FIG. 4, the preliminary color filter structure 234 is formed by repeatedly depositing the titanium oxide layers 220, 224, 228, and 232 and the silicon oxide layers 222, 226, and 230 on the second interlayer insulating layer 216. do. Specific methods for forming the preliminary color filter structure 234 are the same as those described with reference to FIG. 1.

In this case, the wavelength of the transmitted light varies according to the thicknesses of the silicon oxide layers 222, 226, and 230 included in the preliminary color filter structure 234. The preliminary color filter structure 234 of the present embodiment should be designed to transmit light of a green wavelength, that is, a wavelength within a range of about 490 to 570 nm. To this end, the thickness of the silicon oxide film 226 positioned at the center of the preliminary color filter structure 234 should be λ / 4.

Referring to FIG. 5, a mask pattern (not shown) is formed on the preliminary color filter structure 234. The mask pattern should be formed to selectively cover a portion through which light in the green wavelength region is transmitted. The mask pattern includes a photoresist pattern formed through a photo process.

The first preliminary color filter 234a is formed by etching the preliminary color filter structure 234 using the mask pattern as an etching mask.

Referring to FIG. 6, a first color filter pattern 234b is formed by heat treating the first preliminary color filter 234a. The first color filter pattern 234b selectively transmits light in the green wavelength region. The heat treatment process may be performed in the same manner as described in FIG. In addition, as described above, an atmospheric gas may be introduced during the heat treatment step, or ultraviolet rays may be irradiated. The first color filter pattern 234a formed by performing the heat treatment process has a high transmittance and hardly any color mixture.

Referring to FIG. 7, a first photoresist film (not shown) including a blue pigment is formed on the second interlayer insulating layer 216 on which the first color filter pattern 234b is formed. Thereafter, the first photoresist film is exposed and developed to selectively leave only the first photoresist film in a portion where light in the blue wavelength region is transmitted. Through the above process, the second color filter pattern 238 for selectively transmitting the light in the blue wavelength region is formed.

Next, a second photoresist film including a red pigment is formed on the second interlayer insulating film 216 on which the first and second color filter patterns 234b and 238 are formed. Thereafter, the second photoresist film is exposed and developed to selectively leave only the second photoresist film in a portion where light in the red wavelength region is transmitted. Through the above process, the third color filter pattern 240 for selectively transmitting the light in the red wavelength region is formed.

 In the present embodiment, the second color filter pattern 238 is first formed and the third color filter pattern 240 is formed, but the order of forming the second and third color filter patterns 238 and 240 are mutually different. You can change it.

By performing the above process, a color filter having an array structure of green, blue and red color filters is completed. As described above, the first color filter pattern 234b for transmitting light having a green wavelength is formed of an inorganic material, and the second and third color filter patterns 238 and 240 for transmitting light having a blue and red wavelengths. ) Is formed of organic matter.

The first color filter pattern 234b formed of the inorganic material has a higher light transmittance and a narrower wavelength range of the transmitted light than the second and third color filter patterns 238 and 240 formed of the organic material. In addition, the slope of the transmission spectrum for each wavelength is very urgent. Therefore, imaging efficiency becomes very high about the light of green wavelength. In particular, since two green color filters are disposed per one blue and red color filter in the unit array structure of the color filters, the number of the first color filter patterns 234b that transmits light having a green wavelength is determined by the second color filter. And relatively more than the third color filter patterns 238, 240. Therefore, the improvement of the characteristic of the first color filter pattern 234b has more influence on the improvement of the characteristic of the image sensor.

Meanwhile, the second and third color filter patterns 238 and 240 formed of the organic material have a lower light transmittance than the first color filter pattern 234b formed of the inorganic material. However, the light sensitivity is better because the wavelength range of the transmitted light is wider. Therefore, the wavelength range of the transmitted light is narrow, thereby reducing the problem of not transmitting the light within a specific range.

In addition, since the wavelength range of the light transmitted through the first color filter pattern 234b is narrow, the wavelength of the range overlapping with the wavelength range of the light transmitted through the second and third color filter patterns 238 and 240 is reduced. . As a result, mixed color defects caused by overlapping wavelength ranges of light transmitted through the color filter patterns 234b, 238, and 240 may be reduced.

Referring to FIG. 8, the planarization layer 242 is formed on the first to third color filter patterns 234b, 238, and 240. The planarization layer 242 is provided to reduce the step difference between the color filter patterns 234b, 238, and 240.

The microlens 244 is formed on the planarization layer 242 to face the color filter patterns 234b, 238, and 240. The micro lens 244 may be made of a photoresist material. Specifically, a photoresist film is coated on the planarization layer 242 and a lens pattern is formed through an exposure and development process. Thereafter, the lens pattern is heat-treated at a temperature of about 200 ° C. to reflow to form a micro lens 244 having a convex shape.

Example 3

9 and 10 are cross-sectional views illustrating a method of manufacturing an image sensor according to Embodiment 3 of the present invention.

The image sensor manufacturing method of the third embodiment differs from the image sensor manufacturing method of the second embodiment only in the order of processing. Therefore, overlapping parts will be omitted or briefly described.

First, a preliminary color filter structure as shown in FIG. 4 is formed by performing the same process as described with reference to FIGS. 3 and 4.

Thereafter, referring to FIG. 9, the color filter structure 234 ′ is formed by heat treating the preliminary color filter structure. The heat treatment process is performed through the same process as described with reference to FIG. By performing the heat treatment process, the difference in refractive index between the titanium oxide and the silicon oxide included in the preliminary color filter structure is further increased, and a problem that may be caused by stress may be reduced.

Referring to FIG. 10, the color filter structure 234 ′ is patterned to form a first color filter pattern 234c that transmits light having a green wavelength.

Thereafter, an image sensor as shown in FIG. 7 is completed by performing the same process as described with reference to FIG. 7.

Example 4

11 to 14 are cross-sectional views illustrating a method of manufacturing an image sensor according to a fourth embodiment of the present invention.

The image sensor manufacturing method of the fourth embodiment is the same as the image sensor manufacturing method of the second embodiment except for the method of forming the color filter. Therefore, overlapping parts will be omitted or briefly described.

First, the same process as described with reference to FIG. 3 is performed to form the photodiode 202, the interlayer insulating films 204, 210, and 216, and the wirings 206, 212, and 214.

Next, referring to FIG. 11, the titanium oxide films 250 and 254 and the silicon oxide films 252 and 256 are repeatedly deposited on the uppermost interlayer insulating film 216. For example, two layers of titanium oxide films 250 and 254 and two layers of silicon oxide films 252 and 256 interposed between the respective titanium oxide films 250 and 254 are formed.

Thereafter, a portion of the second silicon oxide film 256 positioned at the top of the blue, red, and green color filter areas is etched so that the thickness of the second silicon oxide film 256 is different for each color filter area. The process of etching a portion of the second silicon oxide film 256 may be performed through a photolithography process.

Specifically, a second silicon oxide film 256 having a first thickness is formed in the blue color filter area, and a second silicon oxide film 256 having a second thickness lower than the first thickness is formed in the red color filter area. Is formed. In addition, the second silicon oxide film is completely removed from the green color filter region.

12, a third titanium oxide film 258, a third silicon oxide film 260, and a fourth titanium oxide film 262 are sequentially formed on the second silicon oxide film 256 and the second titanium oxide film 254. By forming the preliminary filter structure 264. At this time, it is preferable that a titanium oxide film is formed on the uppermost surface of the preliminary filter structure 264.

In the present embodiment, to form the preliminary filter structure 264, a portion of the second silicon oxide layer 256 is removed through a photolithography process. However, alternatively, some of the second silicon oxide layer 256 may be removed in a lift off manner. As described above, a method of forming the preliminary filter structure 264 having a different thickness of the second silicon oxide film 256 is disclosed in Korean Patent No. 680386.

Referring to FIG. 13, the color filter 264a is formed by increasing the difference in refractive index between the titanium oxide film and the silicon oxide film by heat treating the preliminary filter structure 264. The color filter 264a has a different thickness of the second silicon oxide film 256a for each region, and thus the wavelength of the transmitted light is different. The heat treatment process may be performed in the same manner as described with reference to FIG.

Thereafter, the planarization layer 266 and the microlens 268 are formed as described with reference to FIG. 8 to complete the image sensor shown in FIG. 14.

Comparative Experiment 1

After depositing a titanium oxide film on the substrate and heat treatment, it is shown in Table 1 by measuring the refractive index, density and phase of the titanium oxide film for each heat treatment temperature.

 TABLE 1

Heat treatment condition Refractive Index 633nm Prize  Density (g / ㎠) PVD TiO ₂ 500Å 400 ° C O ₂ 30 minutes 2.44 Anataz 3.8 ALD TiO ₂ 170Å RTN 500 ℃ 2 minutes 2.62 Anataz 3.9 ALD TiO ₂ 500Å RTN 800 ℃ 2 minutes 2.68 Anataz, Rutile 4.1

First, when the titanium oxide film deposited by ion beam vapor deposition was heat-treated at a temperature of about 400 ° C. for 30 minutes, the refractive index of light having a wavelength of 633 nm was about 2.44.

In addition, the refractive index when the titanium oxide film deposited by the atomic layer deposition method was heat treated at a temperature of 800 ° C was higher than the refractive index when the titanium oxide film deposited by the atomic layer deposition method was heat treated at a temperature of 500 ° C. In addition, the heat treatment at a high temperature increases the density of the titanium oxide film and had a mixed phase of rutile and anatase.

By the above experiment, it was found that by increasing the heat treatment temperature of the preliminary color filter structure including the titanium oxide film, the difference in refractive index between the titanium oxide film and the silicon oxide film can be further increased. However, the heat treatment temperature should be determined in consideration of the fact that the films formed below may be damaged when the thin films are heat treated.

Comparative Experiment 2

Titanium oxide and silicon oxide films were deposited on the substrate by ion beam deposition, respectively, and the stresses were measured for the respective thin films. In addition, after the heat treatment of the deposited titanium oxide film and silicon oxide film, the stress was measured for each heat-treated thin film.

15 is a graph showing a state in which a titanium oxide film and a silicon oxide film are deposited, and a stress after heat treatment of the titanium oxide film and the silicon oxide film.

Referring to FIG. 15, the titanium oxide film in the deposited state had a compressive stress. However, the titanium oxide film in the heat treated state had stretch stress.

On the other hand, the silicon oxide film in the deposited state and the heat treated state had the same compressive stress. However, it can be seen that the compressive stress was somewhat reduced in the heat treated state.

As such, it can be seen that the heat treated titanium oxide film and the heat treated silicon oxide film have different stress characteristics. Therefore, it can be seen that the stress is reduced in the laminated structure of the titanium oxide film and the silicon oxide film.

Comparative Experiment 3

After the deposition of the HDP oxide film on the substrate, and after performing a heat treatment for each temperature on the deposited HDP oxide film, the refractive index was measured.

In addition, the refractive index was measured after the PE-TEOS film was deposited on the substrate and after the heat treatment was performed for each temperature on the deposited PE-TEOS film.

FIG. 16 is a graph showing refractive indexes according to heat treatment temperatures of HDP oxide films and PE-TEOS films.

In Fig. 16,? Is a refractive index according to the heat treatment temperature of the PE-TEOS film, and ▲ is a refractive index according to the heat treatment temperature of the HDP oxide film.

Referring to FIG. 16, it can be seen that the refractive indexes of the HDP oxide film and the PE-TEOS film are lowered as the heat treatment temperatures of the HDP oxide film and the PE-TEOS film are increased.

Comparative Experiment 4

The refractive index was measured after depositing a flowable oxide (FOX) on the substrate, and performing heat treatment at each temperature on the deposited flowable oxide.

17 is a graph showing the refractive index according to the heat treatment temperature of the flowable oxide film.

In Fig. 17,? Is the refractive index of light of 633 nm wavelength of the flowable oxide film in the deposited state. (Circle) is the refractive index of the light of 633 nm wavelength of the fluidized oxide film by the rapid nitriding heat treatment at about 450 degreeC. X is the refractive index of the light of 633 nm wavelength of the fluidized oxide film in the state of rapid nitriding heat treatment at about 500 degreeC. Is the refractive index of light of 633 nm wavelength of the fluidized oxide film in the state of rapid oxidation heat treatment at about 500 degreeC.

Referring to FIG. 17, it can be seen that the refractive index of the light at the time of heat treatment at about 500 ° C. is lower than that of the light at the deposition state and the heat treatment at about 450 ° C.

As described above, the manufacturing method of the color filter of the present invention can be used to form an image element. In addition, the present invention may be actively applied to forming various display elements such as a liquid crystal display and a display panel.

1 and 2 are cross-sectional views for explaining a color filter forming method according to Embodiment 1 of the present invention.

3 to 8 are cross-sectional views illustrating a method of manufacturing an image sensor according to a second exemplary embodiment of the present invention.

9 and 10 are cross-sectional views illustrating a method of manufacturing an image sensor according to Embodiment 3 of the present invention.

11 to 14 are cross-sectional views illustrating a method of manufacturing an image sensor according to a fourth embodiment of the present invention.

15 is a graph showing a state in which a titanium oxide film and a silicon oxide film are deposited, and a stress after heat treatment of the titanium oxide film and the silicon oxide film.

FIG. 16 is a graph showing refractive indexes according to heat treatment temperatures of HDP oxide films and PE-TEOS films.

17 is a graph showing the refractive index according to the heat treatment temperature of the flowable oxide film.

Claims (20)

Forming a preliminary color filter layer having a plurality of metal oxide films and a plurality of silicon oxide films interposed between the metal oxide films on a substrate; And And heat treating the preliminary color filter layer to form a color filter layer such that a difference in refractive index between the metal oxide films and the silicon oxide films is increased. The method of claim 1, wherein the metal oxide layers include titanium oxide. The method of claim 1, further comprising patterning the preliminary color filter layer after forming the preliminary color filter layer. The method of claim 1, wherein the bottom and top layers of the eb color filter layer are formed of a metal oxide film. The method of claim 1, wherein the metal oxide layers have different thicknesses in respective layers. The method of claim 1, wherein the silicon oxide layers have different thicknesses in respective layers. The method of claim 1, wherein the heat treatment is performed at a temperature of 400 to 600 ° C. for 1 to 30 minutes. The method of claim 1, wherein the heat treatment is performed under one atmosphere selected from the group consisting of N ₂ , O ₂ , N ₂ O, NH _3, and O ₃ . The method of forming a color filter for an image device according to claim 1, wherein ultraviolet rays are irradiated during the heat treatment step. The method of claim 1, further comprising patterning the color filter layer after the color filter layer is formed. Forming a photodiode on the substrate; Forming an interlayer insulating film structure covering the photodiode; Forming a preliminary color filter structure on the interlayer insulating film structure, the metal oxide film and the silicon oxide film sequentially stacked; Heat treating the preliminary color filter structure to form a first color filter such that a difference in refractive index between the metal oxide films and the silicon oxide films is increased; And And forming a microlens on the first color filter. The method of claim 11, wherein the metal oxide layers comprise titanium oxide. 12. The method of claim 11, wherein the metal oxide layers each have a thickness of about 300 to about 2000 microseconds. The method of claim 11, wherein each of the silicon oxide layers has a thickness of 400 to 2000 μs. The method of claim 11, wherein the metal oxide layers and the silicon oxide layers have different thicknesses for each layer. 12. The method of claim 11, further comprising patterning the preliminary color filter structure to form a preliminary color filter. The method of claim 16, wherein the preliminary color filter is selectively formed in a filter region that transmits a green wavelength region. 12. The method of claim 11, further comprising patterning the first color filter such that the first color filter is selectively formed in a filter region that transmits a green wavelength region. The method of claim 11, wherein after forming the first color filter, And forming second and third color filter patterns each of which transmits a red and blue wavelength region on the interlayer insulating film structure and are formed of an organic material. Forming a photodiode on the substrate; Forming an interlayer insulating film structure covering the photodiode; Preliminary first to third colors sequentially depositing a metal oxide film and a silicon oxide film on the first to third regions on the interlayer insulating film structure, and having different thicknesses of the silicon oxide film for each region to transmit light having different wavelengths. Forming a filter; Heat treating the preliminary first to third color filters to increase a difference in refractive index between the metal oxide films and the silicon oxide films to form first to third color filters; And And forming a microlens on the first to third color filters.

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