JP4935682B2 - Photomask for manufacturing color filters - Google Patents

Description

  The present invention relates to a photomask for manufacturing a color filter, and more particularly to a photomask for manufacturing a color filter used for a solid-state imaging device.

  In recent years, digital cameras and video cameras that capture still images and moving images have become widespread in various fields. These cameras use solid-state image sensors such as CCDs and CMOSs. However, with the advancement of semiconductor technology, the pixels of the solid-state image sensors have been further miniaturized, and the cameras themselves have been downsized. In such a solid-state imaging device, a color filter and a microlens for increasing the amount of light incident on the light receiving unit and improving the sensitivity are provided corresponding to the light receiving unit of each pixel. FIG. 12 is a view showing the arrangement of each color filter constituting the color filter of such a solid-state imaging device, and FIG. 13 is a cross-sectional view showing the color filter and the microlens taken along the line II of FIG. 14 is a cross-sectional view showing the color filter and the microlens taken along line II-II in FIG. As shown in the figure, the color filter 51 is formed on the planarization layer 52, and is formed by arranging rectangular red filters 51R, green filters 51G, and blue filters 51B. A microlens 55 is disposed on the color filter 51 via a planarizing layer 53. The rectangular red filter 51R, green filter 51G, and blue filter 51B constituting the color filter 51 are adjacent to each other, but the corners are rounded, and therefore there are voids V. . In such a void portion V, no filter of any color exists or only partially exists, so that light rays incident on this portion are not appropriately separated, and the void portion V There is a problem that the light is refracted at the interface and becomes stray light, resulting in crosstalk and the like. Further, the surface of the flattening layer 53 on the gap V is also uneven, which causes a problem such as deformation of the microlens formed on the flattening layer 53.

In order to prevent the occurrence of such voids, a color filter is formed so as not to cause voids by adjusting the dimensions of the corresponding mask pattern light shielding portions of the positive color resist and performing overexposure, It has been proposed to fill a corner with one of the color filters in contact with each corner (Patent Document 1).
JP 2006-269775 A

However, in the above-described method, it is necessary to control the ultraviolet irradiation energy for appropriate overexposure, and it is necessary to have an illuminance distribution in the ultraviolet irradiation in order to make the edge portion of the color filter into a tapered shape. There was a problem that process management was complicated.
Further, in the above-described method, the corner portion is filled with a filter of any one color by using a mask provided with a fine light-shielding pattern at the corner portion as a mask used for exposure of the positive color resist. However, the degree of reduction in contrast at the time of exposure at the corners differs between the green filter present in a checkered pattern and the other two color filters. For this reason, the use of a mask having a minute light-shielding pattern at the corners may not prevent the generation of voids, and conversely, the corners are raised and formed on the color filter. There is also a problem that irregularities are generated on the surface of the flattening layer, causing deformation of the microlens and the like.
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a photomask for manufacturing a color filter without generating a gap between filters of each color.

In order to achieve such an object, according to the present invention, in a photomask in which a rectangular pattern is disposed with corners close to each other, the corners are exposed from both patterns. The reduction in contrast is made by paying attention to the fact that the reduction in contrast at the corners of the rectangular pattern in which no adjacent pattern exists is smaller than that at the time of exposure.
That is, the present invention is a color filter used for a solid-state image sensor, and includes a color filter having three or more colors, and at least one color filter is manufactured in a non-isolated manner with corners in contact with each other. A photomask for a filter that is arranged in a non-isolated manner, and in the case of forming a filter using a negative photosensitive material, a rectangular light transmitting portion with a corner cut out When a filter is formed using a positive photosensitive material, a rectangular light-shielding portion pattern with a corner portion cut out is provided, and a corner portion is formed from an intersection of the rectangular sides extended. in the case of the maximum distance the notch size of up notch, the notch size photomask Ru dimensions der below the resolution limit of an exposure apparatus with a mask exposure condition, for the filter to be isolated arrayed photo A disk, in the case of forming a filter using negative photosensitive material, have a rectangular pattern of the light transmitting portion having a sub-pattern in the corners, forming a filter using positive photosensitive material In the case where the sub-pattern dimension has a rectangular light-shielding part pattern having a sub-pattern at the corner and the maximum length of the sub-pattern protruding outward from the corner is defined as the sub-pattern dimension, the sub-pattern dimension is the mask exposure. a photomask Ru dimensions der below the resolution limit of an exposure apparatus of the condition, and the configuration is a combination of a plurality of photomasks consisting of.

As another aspect of the present invention, the sub-pattern is configured to be disposed apart from the rectangular pattern.
As another aspect of the present invention, the photomask having a rectangular pattern with a corner cut out is a photomask for forming a green filter, and the photomask having a rectangular pattern having a sub-pattern at the corner. The mask was configured to be a photomask for forming a red filter and a blue filter.

  In the present invention, in the photomask having a rectangular pattern with the corners notched, the notches provided at the corners moderately suppress the exposure amount from both adjacent patterns. Can form a non-isolated filter that touches sharply, and in a photomask having a rectangular pattern with a sub-pattern at the corner, the sub-pattern suppresses a decrease in contrast during exposure at the corner. Therefore, it is possible to form an isolated filter having sharp corners without being rounded, thereby producing a color filter without producing a gap between the filters of each color. The

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram showing an example of a color filter manufactured using the photomask of the present invention. The color filter 1 shown in FIG. 1 is an array of rectangular red filters 1R, green filters 1G, and blue filters 1B. The green filter 1G is a non-isolated filter in which corners are in contact and arranged in a checkered pattern. Further, the red filter 1R and the blue filter 1B are isolated filters arranged in a portion where the green filter 1G is not formed. And this color filter 1 does not have a space | gap part between the filters of each color.
Next, the photomask of the present invention will be described by taking a photomask for forming the color filter 1 as an example.

  FIG. 2 is a partial plan view showing a photomask for the green filter 1G arranged in a non-isolated manner, and FIG. 3 is a diagram showing one pattern of the photomask shown in FIG. 2 and 3, the photomask 11G is provided with a rectangular pattern 12G in a checkered pattern, and each rectangular pattern 12G has a cutout portion 13 at four corners 12a. In addition, the pattern which the photomask in this invention has is a light transmissive part, when using a negative photosensitive material for formation of the red filter 1R, the green filter 1G, and the blue filter 1B. In the case of using the light shielding portion. The same applies to the following description.

  In the photomask in which rectangular patterns are arranged in a non-isolated manner in contact with corners, the present inventor shows that the reduction in contrast at the exposure in the corners is the case in the photomask in which rectangular patterns are arranged in isolation. Focused on the difference. That is, in a photomask in which rectangular patterns are arranged in a non-isolated manner in contact with corners, the corners are exposed from both patterns, and therefore there is no proximity pattern in the reduction in contrast at the corner exposure. This is less than the decrease in contrast during exposure at the corners of the rectangular pattern. For this reason, it is formed by exposure and development using a photomask (a photomask in which rectangular patterns are arranged in a non-isolated manner in contact with the corners) without the corner notch 13 as described above. When a negative photosensitive material is used, the filter is thickly connected at the corners. When a positive photosensitive material is used, the corners are separated from each other. Even in this case, a sharp rectangular filter cannot be formed. However, by using the photomask 11G of the present invention, the notch 13 provided in the corner 12a acts to moderately suppress the exposure amount of the corner 12a exposed from both adjacent patterns. Thereby, the non-isolated green filter 1G in which the corners are in sharp contact can be formed.

Here, the notch 13 included in each pattern 12G has a notch dimension L that is the maximum distance L in the X-axis direction and the Y-axis direction from the intersection P extending the side of the rectangle to the notch of the corner 12a. Sometimes, the notch dimension L is set to a dimension not more than the resolution limit of the exposure apparatus under the mask exposure conditions. When the cutout dimension L is larger than the resolution limit, the shape of the cutout portion 13 is directly reflected in the filter shape, and a sharp rectangular green filter cannot be obtained. Further, the lower limit of the notch dimension L can be about 40 nm, for example, when exposure by an i-line stepper is used.
In the above example, the cutout portion 13 has a shape in which the corner portion 12a is cut out linearly. However, the present invention is not limited to this, and for example, a cutout having a shape as shown in FIG. 4 and FIG. It may be part 13.

FIG. 6 is a partial plan view showing a photomask for the red filter 1R arranged in isolation, and FIG. 7 is a diagram showing one pattern of the photomask shown in FIG. 6 and 7, the photomask 11R includes a rectangular pattern 12R, and each rectangular pattern 12R has a rectangular subpattern 14 at four corners 12a.
By using the photomask 11R having the sub-pattern 14 at the corner 12a of the rectangular pattern 12R arranged in this way, the sub-pattern 14 suppresses a decrease in contrast during exposure at the corner. Therefore, it is possible to form an isolated red filter 1 </ b> R that is not round and has sharp corners.

  Here, the sub-pattern 14 included in each pattern 12R has the sub-pattern dimension L when the maximum length of the sub-pattern protruding outward from the corners in the X-axis direction and the Y-axis direction is the sub-pattern dimension L ′. Let 'be a dimension that is less than the resolution limit of the exposure apparatus under the mask exposure conditions. Further, when the maximum distance that the sub-pattern 14 protrudes outward from the corner 12a of the rectangular pattern 12R is defined as the protrusion distance d, the protrusion distance d is also a dimension that is less than the resolution limit of the exposure apparatus under the mask exposure conditions. To do. When the sub-pattern dimension L ′ and the projection distance d exceed the resolution limit, the exposure amount of the corner portion 12a becomes excessive, and the formed filter has a shape in which the corner portion protrudes, resulting in a sharp rectangular shape. The red filter cannot be obtained. Further, the lower limit of the sub-pattern dimension L ′ and the protrusion distance d can be set to about 40 nm when exposure using an i-line stepper is used, for example.

As shown in FIG. 8, the sub-pattern 14 may be provided apart from the pattern 12R. In this case, the distance d ′ between the pattern 12R and the sub-pattern 14 is preferably set to be equal to or less than the resolution limit of the exposure apparatus under the mask exposure conditions. If the distance d ′ is too large, the sub-pattern 14 is not preferable because the effect of suppressing the reduction in contrast at the time of exposure of the corner portion 12a by 14 cannot be obtained.
In the above example, the sub pattern 14 is rectangular, but the shape of the sub pattern 14 is not limited to this. For example, it may be a triangle as shown in FIG. 9A, and in this case as well, the sub-pattern 14 may be separated from the pattern 12R as shown in FIG. 9B. The protrusion distance d and the separation distance d ′ are preferably within the above-described ranges. Further, the sub-pattern 14 may be circular as shown in FIG. 10A, and in this case as well, the sub-pattern 14 may be separated from the pattern 12R as shown in FIG. 10B. The protrusion distance d and the separation distance d ′ are preferably within the above-described ranges.
Note that the photomask 11B for the blue filter 1B arranged in isolation can be configured in the same manner as the photomask 11R described above, and description thereof is omitted here.

Next, an example of forming the color filter 1 using the above-described photomasks 11G, 11R, and 11B of the present invention will be described with reference to FIG.
First, a photosensitive material for a green filter is applied, and exposure and development are performed using a photomask 11G to form a non-isolated green filter 1G (FIG. 11A). The green filter 1G is a sharp rectangle with corners in contact with each other. Therefore, the non-formation part (isolated) of the green filter 1G is also a sharp rectangle.
Next, a photosensitive material for a red filter is applied so as to cover the green filter 1G, and exposed and developed using a photomask 11R to form an isolated red filter 1R (FIG. 11B). . The red filter 1R is a rounded and rectangular shape with sharp corners, and therefore, the non-formed portion of the green filter 1G (the formed portion of the red filter 1R) is red without generating a gap. Filled with filter 1R.

Next, a photosensitive material for a blue filter is applied so as to cover the green filter 1G and the red filter 1R, and exposed and developed using a photomask 11B to form an isolated blue filter 1B (FIG. 11 ( C)). The blue filter 1B is a rectangle that is not round and has a sharp corner, and therefore, the non-formation part of the green filter 1G (formation part of the blue filter 1B) is blue without generating a gap. Filled with filter 1B.
As a result, a color filter 1 that is composed of a rectangular green filter 1G, a red filter 1R, and a blue filter 1B and that has no gaps between the filters of each color, particularly at the corners, is obtained.
The formation order of the red filter 1R and the blue filter 1B may be reversed.
The above-described embodiments are examples, and the present invention is not limited to these embodiments.

Next, an Example is shown and this invention is demonstrated further in detail.
[Example 1]
First, a wafer on which a CMOS image sensor having a pixel light receiving portion pitch of 2.0 μm and a pixel number of 2592 × 1944 was formed.
Next, after cleaning the wafer surface with a spin scraper, a photo-curing acrylic transparent resin material (CT-2020L manufactured by Fuji Microelectronics Materials Co., Ltd.) is spin-coated, and then pre-baking, UV exposure, post Baking was performed to form a planarization layer (thickness 0.3 μm).
Next, the following materials were prepared as negative photosensitive green materials (G materials), red materials (R materials), and blue materials (B materials).
Material for G: SG-4000L manufactured by Fuji Microelectronic Materials Co., Ltd.
Material for R: SR-4000L manufactured by Fuji Microelectronic Materials Co., Ltd.
Material for B: SB-4000L manufactured by Fuji Microelectronic Materials Co., Ltd.

Moreover, the arrangement pitch of each color filter of a color filter was 2.0 micrometers, and the photomask shown by FIG. 2 and FIG. 3 was prepared as a photomask for green filters. This photomask has a rectangular pattern (light transmission portion) with a side of 2.0 μm, and the notch dimension L of the notched portion of the right isosceles triangle shape at the corner of each pattern is 0.1 μm. . The exposure apparatus was NSR-2505i14E2 manufactured by Nikon Corporation, and the resolution limit under the set exposure conditions was 0.35 μm.
Moreover, the photomask shown by FIG. 6 and FIG. 7 was prepared as a photomask for red filters and blue filters. This photomask has a rectangular pattern (light transmission part) having a side of 2.0 μm and a rectangular sub pattern (light transmission part), the dimension L ′ of the sub pattern is 0.2 μm, and the protrusion distance d is The thickness was 0.23 μm.

Then, in the formation order of the green filter, red filter, and blue filter, the above materials are spin-coated, pre-baked, exposed with a 1/5 reduction type i-line stepper, developed, and post-baked, and then the green filter, red filter, A color filter (thickness 0.8 μm) composed of a blue filter was formed on the planarization layer. As a developing solution, a 50% diluted solution of CD-2000 manufactured by Fuji Microelectronic Materials Co., Ltd. was used.
About the color filter formed as mentioned above, the presence or absence of the space | gap part in an adjacent filter, especially the corner | angular part, and the presence or absence of the swelling part were observed using the atomic force microscope. As a result, it was confirmed that neither the void portion nor the raised portion was present, and the state was good.

[Example 2]
A photomask having a pattern shown in FIG. 5 is used as a photomask for a green filter, and a photomask having a pattern and a sub-pattern shown in FIG. 10A is used as a photomask for a red filter and a blue filter. A color filter was formed on the planarizing layer in the same manner as in Example 1 except that was used. The cutout dimension L of the notch in the green filter photomask is 0.15 μm, and the subpattern dimension L ′ in the red filter and blue filter photomask is 0.25 μm, and the protrusion distance d. Was 0.2 μm.
As a result of observing the formed color filter in the same manner as in Example 1, it was confirmed that neither the void portion nor the raised portion was present and that the color filter was in a good state.

[Example 3]
Other than using positive photosensitive green material (G material), red material (R material), blue material (B material), and using photomask pattern and sub-pattern as light shielding part As in Example 1, a photomask for a green filter, and a photomask for a red filter and a blue filter were prepared, and a color filter was formed on the planarizing layer in the same manner as in Example 1.
As a result of observing the formed color filter in the same manner as in Example 1, it was confirmed that neither the void portion nor the raised portion was present and that the color filter was in a good state.

[Example 4]
A color filter was formed on the planarizing layer in the same manner as in Example 1 except that a photomask having the pattern and subpattern shown in FIG. 8 was used as the photomask for the red filter and the blue filter. The subpattern dimension L ′ in the red filter and blue filter photomasks was 0.2 μm, and the separation distance d ′ was 0.05 μm.
As a result of observing the formed color filter in the same manner as in Example 1, it was confirmed that neither the void portion nor the raised portion was present and that the color filter was in a good state.

[Comparative Example 1]
Flattening in the same manner as in Example 1 except that the photomask for the green filter is a photomask that does not have a notch and is in contact with corners and in which a rectangular pattern is non-isolated. A color filter was formed on the layer.
As a result of observing the formed color filter in the same manner as in Example 1, the corners of each green filter are thickly connected, and the corners of the red filter and the blue filter are overlapped with this part, and the raised part ( It was confirmed that the flatness was poor.

[Comparative Example 2]
In the photomask for the green filter, the cutout dimension L of the cutout portion of the right isosceles triangle shape is set to 0.4 μm that exceeds the resolution limit (0.35 μm) of the exposure apparatus, and is the same as in the first embodiment. Thus, a color filter was formed on the planarizing layer.
As a result of observing the formed color filter in the same manner as in Example 1, it was confirmed that voids were present at the corners.

  The present invention can be applied in various fields where a precise color filter having no gap portion between the filters of each color is required.

It is a figure which shows an example of the color filter produced using the photomask of this invention. It is a partial top view which shows one Embodiment of the photomask for filters arranged in a non-isolated manner. It is a figure which shows one pattern of the photomask shown by FIG. It is a figure which shows other embodiment of the photomask for filters arranged in a non-isolated manner. It is a figure which shows other embodiment of the photomask for filters arranged in a non-isolated manner. It is a fragmentary top view which shows one Embodiment of the photomask for filters arranged in isolation. It is a figure which shows one pattern of the photomask shown by FIG. It is a figure which shows other embodiment of the photomask for filters arranged in isolation. It is a figure which shows other embodiment of the photomask for filters arranged in isolation. It is a figure which shows other embodiment of the photomask for filters arranged in isolation. It is process drawing for demonstrating the example of formation of the color filter using the photomask of this invention. It is a figure which shows arrangement | positioning of each color filter which comprises the color filter of a solid-state image sensor. It is sectional drawing which shows the color filter and micro lens in the II line | wire of FIG. It is sectional drawing which shows the color filter and micro lens in the II-II line | wire of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Color filter 1G ... Green filter 1R ... Red filter 1B ... Blue filter 11G ... Photomask for green filter 11R ... Photomask for red filter 12G, 12R ... Pattern 13 ... Notch part 14 ... Sub pattern

Claims (3)

A color filter used in a solid-state imaging device, comprising a rectangular filter of three or more colors, wherein at least one color filter is a photomask for manufacturing a color filter arranged in a non-isolated manner in contact with corners ,
A photomask for a filter that is non-isolated and is formed using a negative photosensitive material and has a rectangular light-transmitting portion pattern with a corner cut out, and is positive. In the case of forming a filter using a type photosensitive material, it has a rectangular light-shielding part pattern with corners notched, and the maximum distance from the intersection of the rectangular sides extended to the corner notch when the notch dimensions, the photomask cutout dimensions Ru following dimensions der resolution limit of an exposure apparatus with a mask exposure condition,
A photomask for filters isolated arrayed, when using negative photosensitive material to form the filter have a rectangular light transmitting portion of the pattern having a sub-pattern in the corners, positive When forming a filter using a type photosensitive material, it has a rectangular light-shielding part pattern with a sub-pattern at the corner, and the maximum length of the sub-pattern protruding outward from the corner is defined as the sub-pattern dimension. when the photomask, characterized in that the sub-pattern dimension is a combination of a plurality of photomasks consisting of a photomask Ru following dimensions der resolution limit of an exposure apparatus with a mask exposure condition. The photomask according to claim 1 , wherein the sub-pattern is disposed apart from the rectangular pattern. The photomask having a rectangular pattern with a corner cut out is a photomask for forming a green filter, and the photomask having a rectangular pattern having a sub-pattern at a corner includes a red filter and a blue filter. the photomask according to claim 1 or claim 2 characterized in that it is a photomask for forming.

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