JPH04121702A - Formation of color filter - Google Patents

Abstract

PURPOSE:To form color filters to a uniform film thickness over the entire surface with a smaller number of stages by spraying the liquid drops of color filter materials onto a substrate or element, thereby forming the fine color filters. CONSTITUTION:The nozzle 41 of a discharge head 40 is registered to face the picture element on the substrate 1 formed with a solid-state image pickup device consisting of elements 2 to 8. The red filter drop 51a is discharged from this nozzle and is brought into collision against the aperture of a light shielding film 8 to form the red filter film 51b for one picture element. The discharge head 40 is thereafter moved by 3 picture elements and the next liquid drop 51a is discharged to form the filter film 51b. The filter films 51b of the 1st color are formed on the picture elements of the substrate 1 by repeating such operation. The films are heat treated to stabilize. The green filter films 52b are similarly formed on the adjacent picture elements by another head 40 packed with the green filter soln. 52 to form the blue filter films 53b in succession to the above operation. The stages are simplified in such a manner and the original color filters of the uniform three colors R, G, B are obtd.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention is applicable to color filters of light receiving devices such as solid-state imaging devices or auto white balance sensors, and light emitting devices such as LCD color televisions and TPT-LCD (Thin Film Transistor Liquid Crystal) displays. The present invention relates to a method of forming a color filter for an apparatus.

[Prior Art] Conventionally, methods for manufacturing color filters include dyeing methods, printing methods, electrodeposition coating methods, interference film deposition methods, dye vapor deposition methods, pigment film photolithography methods, and the like.

Among these methods, dyeing methods have been mainly used for color filters for solid-state imaging devices such as CCD image sensors.

Here, this staining method will be taken up as a representative example of the prior art and will be explained in detail below.

FIG. 6 is a schematic cross-sectional view of a CCD image sensor having a conventional color filter for a solid-state imaging device, particularly an on-chip color filter. In FIG. 6, 1 is a substrate made of silicon or the like, 2 is a photodiode formed on this substrate 1, 3 is a gate electrode for reading charges generated by light incident on this photodiode 2 to a CCD section, which will be described later. Reference numeral 4 denotes a Veri-Rad channel of the CCD section, and 5 denotes a gate electrode disposed on the Veri-Rad channel 4, which together with the Veri-Rad channel 4 constitutes the CCD section. Reference numeral 6 denotes an isolation oxide film, and a permeable light-shielding film 8 is formed above the gate electrode 3, Verirad channel 4, gate electrode 5, and isolation oxide film 6 with an insulating oxide film 7 interposed therebetween. Furthermore, an on-chip color filter film 10 is laminated on top of the on-chip color filter film 10, which is composed of a base film 11 made of a transparent resin material, an intermediate film 12, a protective film 13, and a colored pattern for color separation. has been done. This coloring pattern includes primary colors and complementary colors, but in this example, the cyan filter 21a and the yellow filter 22
Complementary color filters consisting of a combination of a are used.

In the conventional solid-state imaging device with the above structure, ^
The furnace light-shielding film 8 is open only above the photodiode 2, which is the light-receiving region, and prevents light from entering other than the light-receiving region, such as the Verirad channel 4 and the electrode 5, into the CCD section, thereby preventing the generation of unnecessary charges. is prevented. Also, the light incident on the opening of the light film 8 is separated into colors depending on the presence or absence of an unfilter 21a, a yellow filter 22a, or a green filter (not shown) formed by stacking these, and then enters the photodiode 2. , generates signal charges according to the intensity of incident light.

Here, a description will be given of a method for manufacturing a conventional solid-state imaging device using the on-chip color filter film 10 as described above.

FIGS. 7(a) to 7(f) are schematic cross-sectional views illustrating the process of forming a color filter film in a conventional manufacturing method. FIG. 7(a) shows the state before the color filter film 10 is formed, in which the photodiode 2, Verirad channel 4, gate electrodes 3, 5, etc. are formed by a well-known silicon semiconductor process. ing. In the process of forming the color filter film 10, first, as shown in FIG. 7(b), a transparent material such as acrylic resin is applied onto the substrate 1 as shown in FIG. 7(a) by, for example, a spin coating method. Then, a base film 11 is formed. At this time, if the base film 11 itself is photosensitive to ultraviolet rays, unnecessary base film 11 is removed on top of the bonding pad and dicing line (both not shown) by photolithography. . Next, as shown in Figure 7(c), ammonium dichromate salt is applied to a natural molecular material such as water-soluble gelatin or casein, or a synthetic polymer material such as PVA (polyvinyl alcohol), which is the base material for the colored pattern. Applying a material that has been given negative photosensitivity by adding, for example,
A first color filter film 21 is formed. This filter membrane 2
1 is exposed to ultraviolet light using a mask 31, and then subjected to a development process, as shown in FIG. 7(d).
The filter film 21 is left only on the portion exposed to light, that is, only on the photodiode 2. Subsequently, this is dyed with cyan dye to form a cyan filter 21a as shown in FIG. 7(e).

After that, the intermediate film 12 and the second color yellow filter 2 are removed.
2a is formed by repeating the same steps as shown in FIGS. 7(b) to 7(e), and finally the protective film 13 is formed on the base film 11.
It is formed by the same method as the intermediate film 12. At this time, unnecessary films on the bonding pads and dicing lines (both not shown) can be removed by photolithography if the film itself has photosensitivity, or by photolithography if it does not have photosensitivity. Further, a resist film is formed on top of these films, and this is used as a mask to remove the resist film by etching with oxygen plasma or the like.Finally, the resist film is removed to obtain the color filter 1110 shown in FIG. 7(f). Ta.

The above example describes a method for forming a color filter on a plurality of solid-state image sensor chips formed on a substrate 1.6 Usually, the substrate is about LoCm (4 inches) to about 20 cm (8 inches). In most cases, a spin coating method is used to form a thin film of each material of the above-mentioned filter on the substrate 1.

However, in the spin coating method, the substrate size is about 25em (1
In the case of large items (exceeding 0 inch), apply F! with a uniform thickness on the order of microns. It is difficult to form a film over the entire surface, and this tendency becomes more pronounced as the size of the substrate increases, and it is more difficult to obtain a uniform film when the substrate is rectangular than circular.

For this reason, when forming color filters on large rectangular substrates such as liquid crystal color displays, roll coating was sometimes used, but this method also has better controllability of the film thickness than spin coating. However, it had the disadvantage that it was difficult to obtain a uniform film thickness.

[Problems to be Solved by the Invention] In the conventional method of forming color filters using the dyeing method, the above-mentioned steps such as coating, B light, development, and dyeing must be repeated many times depending on the number of colors. There were also problems in that the process was complicated and the cost was high.

In addition to the above-mentioned problems when using a large substrate such as a liquid crystal color display, as the substrate size increases, it becomes necessary to form a thin film of color filter material evenly over the entire surface of the substrate with a uniform thickness. There was a problem that it became difficult.

This invention was made to solve these problems, and it is possible to form a color filter with a small number of steps.
It is an object of the present invention to provide a method for forming a color filter that can reduce manufacturing costs and form a uniform film thickness over the entire surface regardless of the size and shape of the substrate.

[Means for Solving the Problems] A method for forming a color filter according to the present invention is to spray droplets of a color filter material onto a substrate or an element to form a fine color filter.

Further, in the method for forming a color filter according to the present invention, a bank is formed in advance on a substrate or an element using a material with a philophilic material opposite to that of the color filter material, and droplets of the color filter material are individually placed in the bank. It is used to form color filters.

Furthermore, the method for forming a color filter according to the present invention includes:
After a color filter is formed by spraying droplets of a color filter material onto a substrate or an element, droplets of a protective film material are sprayed on top of the color filter to form a protective film.

[Operation] In this invention, droplet-shaped color filter material is individually sprayed directly onto the substrate or element at the position where the color filter is to be formed, and the color filter material droplets collide with the substrate. deforms and forms a color filter film.

Further, in the present invention, droplets of the color filter material are sprayed by a bank having a philicity opposite to that of the color filter material, which is formed around the area on the substrate or element where the color filter film is to be formed. This prevents the color filter material from overflowing to adjacent pixels when a collision occurs.

Further, in the present invention, droplets of the protective film material are further sprayed onto the crotch of the color filter formed as described above, and these droplets collide and deform to form a protective film.

[Example] An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1(a) is a schematic cross-sectional view showing a discharge head for spraying droplets of color filter material, which is used when forming a color filter according to the present invention, and FIG. FIG. 3 is a partially enlarged cross-sectional view of part A in FIG. In FIG. 1, the symbols 1 to 8 are the same as those explained in the conventional example, so their explanation will be omitted here.

Note that although the substrate 1, such as a silicon wafer, will be described as an example of a target on which a color filter film is formed, it should be noted that elements such as a solid-state image sensor chip can also be formed in the same manner.

Reference numeral 40 denotes a discharge head disposed opposite to the substrate 1 or the element, and is moved two-dimensionally along the surface of the substrate 1 by a moving mechanism (not shown), and the discharging head 40 is disposed opposite to the substrate 1 or the element.
distance is adjusted. A solid-state imaging device consisting of elements 2 to 8 has already been formed on the substrate 1. Reference numeral 41 designates a nozzle of the ejection head 40, from which droplets of color filter material are ejected. Here, an example of red filter solution 51 is taken as a color filter material.
This red filter solution 51 is stored in an ink reservoir 44 above the ejection head 40. This ink reservoir 44
is connected to an ink chamber 42, and the inside of the ink chamber 42 is filled with a red filter solution 51. Note that the ink chamber 42 is also connected to the nozzle 41 described above.

An electrostrictive element 43 is arranged at the back of the ink chamber 42 , and a case 45 surrounds the ink chamber 42 and the electrostrictive element 43 . The electrostrictive element 43 is deformed by applying a predetermined voltage in a pulsed manner to the drawn out terminals 43a and 43b, and the volume of the ink chamber 42 is temporarily reduced. As a result, the pressure inside the ink chamber 42 increases, and minute droplets 51 of the red filter solution 51 are released from the nozzle 41.
a is discharged. Discharged red filter droplet 51a
is the desired position on substrate 1, here photodiode 2
It collides with the upper position and is deformed to form the red filter film 51b.

The red filter film 51b for one pixel is formed in the above steps, but after this, the ejection head 40 moves by a predetermined amount and ejects the red filter droplet 51a onto the next pixel.

Next, an example will be described in which a primary color R (:B (red, green, blue)) color filter is formed on the substrate 1 by the method described above.

FIGS. 2(a) to 2(cl) are schematic cross-sectional views for explaining an embodiment in which a color filter film is formed on a substrate 1 on which a solid-state imaging device is formed. FIG. 2(a) shows a substrate 1 or an element on which a solid-state imaging device consisting of elements 2 to 8 is formed, as described in the section of the prior art. Above the photodiode 2, the light shielding film 8 is opened.
This portion serves as a light incident area, that is, a pixel.

As shown in FIG. 2(b), the nozzle 41 of the ejection head 40 is aligned to face this pixel, and a pulsed voltage is applied between the terminals 43a and 43b as described above. The filter droplets 51a are discharged, and the furnace light-shielding film 8 collides with the opening and is deformed, forming a red filter film 51b for one pixel. After this, the ejection head 40 moves three pixels in the direction of the arrow as shown in the figure, and here the next red filter droplet 51a is ejected again, and one or more operations are performed as necessary to form the red filter film 51b. When repeated, the first color red filter film 51b is formed on the pixels of the substrate 1. Thereafter, by performing appropriate heat treatment as necessary, the solvent component of the red filter membrane 51b is volatilized, and the red filter membrane 51b is stabilized.

Subsequently, as shown in FIG. 2(c), the green filter film 52b is replaced by the red filter film 51b in the same manner as described above using another ejection head 40 filled with the green filter solution 52, which is the second color filter solution. are sequentially formed on pixels adjacent to .

Thereafter, after performing heat treatment as necessary, the above-mentioned process is repeated using another ejection head filled with the blue filter solution to form the blue filter film 53b shown in FIG. 2(d). primary color filters are formed.

In the explanation of the above embodiments, materials for color filters were not specifically mentioned, but similar to those explained in the conventional technology, hydrophilic materials such as gelatin or other water-soluble materials mixed with dyes, and pigment particles made of polymers may be used. Any hydrophobic material that is dispersed in a material and made into a solution with an organic solvent can be used.

For example, if we consider the case where a low-viscosity color filter material is used, depending on the speed or size of the droplet discharged from the nozzle 41, when the droplet collides with the pixel of the substrate 1, the color filter solution may It may spread more than necessary and jump onto adjacent pixels. In order to prevent this, in another embodiment of the present invention, a bank made of a material having a philophilic property opposite to that of the color filter material is formed on the area between the pixels, so as to surround the pixel portion. , spraying droplets of color filter material onto the area inside the embankment.

Other embodiments of the present invention will be described above using the schematic cross-sectional views of FIGS. 3(a) to 3(d).

In FIG. 3(a), a bank or enclosure 50 made of a hydrophobic polymeric material is formed around the photodiode 2 on the light shielding film 8 shown in FIG. 2(a). Examples of such materials include synthetic resins such as PGM^ (polyglycidyl acrylate) and PMM^ (polymethyl methacrylate). The embankment 50 made of such a hydrophobic material is formed in advance using photolithography technology, screen printing technology, etc., and the ejection head is formed as shown in FIG. 3(b) in the same manner as described in FIG. Head filter droplets are discharged from 40 to form a red filter film 51b. Here, the red filter solution 51 is assumed to be a water-soluble material. Red filter film 51 for one pixel
After discharging and forming b, the discharging head 40 is moved by a predetermined pitch.
is moved to form a predetermined amount of red filter film 51b. Thereafter, heat treatment is performed as necessary to stabilize the red filter film 51b.

Next, as shown in FIG. 3(e), 2
A green filter film 52b is formed using the colored green filter solution 52. Thereafter, the same steps as described above are repeated, and primary color filters of red, green, and blue are formed within the bank 50, as shown in FIG. 3(d).

In the above description of the embodiment, an example of forming a primary color filter having a three-color configuration has been described; yellow cyan, magenta,
It goes without saying that the formation method of the present invention can also be applied to the formation of complementary color filters using colors such as green.

Further, in the above embodiment, an example was explained in which color filters are formed in the order of red, green, and blue, but the order of formation is not limited to this and may be arbitrary.

Next, regarding still another embodiment of the present invention, FIG. 4(, ),
(b) and the schematic cross-sectional views of FIGS. 5(a) and 5(b).

Figures 2(a)-(d) and 3(a)-(d) have already been shown.
) The color filter film formed by the method described above does not have any functional problems in itself, but depending on the material of the color filter film, the functional strength may be low (easily scratched, etc.), or it may deteriorate due to reaction with outside air. There are cases where it happens. Therefore, as a countermeasure when such weak materials are used, a protective film may be required on the color filter film.

4(a) and 5(a) structurally differ only in the presence or absence of the embankment 50, so both will be explained together below. After the three-color color filter films 51b, 52b, and 53b of red, green, and blue are formed, as shown in (a) of Ryogoku, transparent resin such as PGM^ or PH88 as described earlier is ejected from the ejection head 40 as shown in (a) of Ryogoku. Droplets 54m of a protective film solution 54 made of the material are sprayed. The protective film droplet 54a that collided with the color filter film is deformed and forms a protective film 54b on the color filter film.

By forming step-by-step protective films 54b on the color filter films of each color, color filters as shown in FIGS. 4(b) and 5(b) are formed.

In the above embodiments, a silicon wafer is used as the substrate, and a color filter is formed on a solid-state image pickup device formed on the silicon wafer. Needless to say, it can also be used to form a color filter for a liquid crystal display device such as an LCD display. may be fixed and the substrate may be moved.

In addition, an example was shown in which a protective film is formed pixel by pixel, but in this case, large droplets are ejected from the nozzle of the ejection head so as to cover multiple pixels at once, forming a protective film over a wide area. You can do it like this.

In addition, the substrate is not limited to silicon wafers,
The glass substrate 1 may be another substrate such as a five-English substrate.

[Effects of the Invention] As explained above in detail, the present invention forms a color filter by spraying droplets of each color of the constituent elements of the color filter onto the pixels. There is no need to form an intermediate film, so the process can be simplified and costs will not increase, and a uniform color filter can be formed without being limited by the size or shape of the substrate.

In addition, in this invention, a bank is formed with a material having an opposite affinity to that of the color filter material so as to surround the pixel, and droplets of the color filter are injected, so that the color filter material reaches the adjacent pixel. The effect is that a highly accurate color filter can be obtained without any protrusion.

Furthermore, since the present invention forms a protective film on the color filter film, the strength and stability of the color filter can be improved.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view showing a discharge head used in forming a color filter according to the present invention, FIG. 2 is a schematic sectional view illustrating a method for forming a color filter according to an embodiment of the present invention, and FIG. FIG. 4 is a schematic sectional view illustrating a method of forming a color filter according to another embodiment of the present invention.
5 and 5 are schematic cross-sectional views illustrating a method of forming a color filter according to still another embodiment of the present invention, FIG. 6 is a cross-sectional view showing a CCD image sensor having a conventional color filter, and FIG. 7 is a conventional FIG. 3 is a schematic cross-sectional view illustrating a method for forming a color filter in order of steps. In the figure, 1 is a substrate, 2 is a photodiode, 50 is a bank, 51a is a red filter solution, 51b is a red filter film, 52b is a green filter film, 53b is a blue filter film, 54a is an M retention film droplet, and 54b is a It is a protective film. In addition, in the figures, the same reference numerals indicate the same or equivalent parts. Representative Person Zeng I Do Shokazu ((3) 5j Koshi-nodofirashi history) Figure 2 ((3) 7'r2 (b) 5T. Sodophila family l Figure 2 fc) Figure 42 (d ) Toe diagram ((3) 50:jL Oshi diagram (1)) Figure 3 (C) (d) Figure 4 ((3) 40 (b) Figure 5 to+ 5Ii 7r-5 mark (j))゛) Figure 7 (○) Figure 7T7 (C) Figure 7 Fd1 7V7 Figure (e) -70 (f) Procedural amendment 1゜ Indication of case Patent application No. 241267 of 1990 Address Tokyo 2-2-3 Marunouchi, Chiyoda-ku
Name (601) Mitsubishi Electric Corporation Representative Moriya Shiki 4゜Agent address 8th floor, International Building, 3-1-1 Marunouchi, Chiyoda-ku, Tokyo Subject of amendment (1) Column 6 for detailed explanation of the invention in the specification , Contents of amendment (1) ' A f in the following parts of the specification
The description of Z light film 8J is corrected to "light shielding film 8." Page 3, Line 12, Page 4, Line 3, Line 7, Page 12, Lines 17-18, Page 15, Lines 4-5 (2) [Unfiltered] on page 5, page 12 of the specification. Correct the description of J to ``Cyan Filter Co.'' (3) Add unnecessary J on page 5, line 9 of the specification, etc.
amend the description to "unnecessary above etc." (4) "Natural molecular material f'l J" on page 5, line 12 of the specification.
The description of ``natural polymer material'' has been corrected to ``natural polymer material.'' (5) The description of "thickness on the order of microns" on page 7, line 6 of the specification will be corrected to "thickness on the order of microns." (6) Insert "The shape of the π plate 1" before the description of "circular" on page 7, line 9 of the specification. (7) The statement "A-filtering light-shielding film 8 is an opening" on page 13, line 4 of Book 11jI of Meiji is corrected to "opening of light-shielding film 8." (8) “Move 3 pixels” on page 13, line 7 of the specification
amend the description to ``For example, move a distance of 3 pixels.''<9) The description of "head filter droplets" on page 15, lines 13 to 14 of the specification is corrected to "red filter droplets." (1(3) The description of "predetermined amount J" on page 15, line 18 of the specification is corrected to "predetermined number." (11) The description of "functional strength" on page 17, line 3 of the specification is corrected to " (12) The description of "Step Pi Step" on page 17, lines 17 to 18 of the specification is corrected to "Sequentially J."

Claims (3)

[Claims] (1) A method for forming a color filter, comprising the step of spraying droplets of a color filter material onto a substrate or element on which a color filter is to be formed. (2) On the substrate or element on which the color filter is to be formed, it is made of a material that surrounds each position where each component of the color filter is to be placed and has an affinity opposite to that of the color filter material. A method for forming a color filter, comprising the steps of forming a bank, and forming each component of the color filter by individually injecting droplets of the color filter material into the bank. . (3) Spraying droplets of color filter material onto the substrate or element on which the color filter is to be formed to form a color filter pattern, and then individually spraying droplets of protective film material onto the color filter pattern; A method for forming a color filter comprising the step of forming a protective film by spraying at the same time.