JPS60106167A - Manufacturing method of color image sensor - Google Patents

Abstract

PURPOSE:To prevent the generation of forming irregularity of the filter base metal and the generation of dyeing irregularity accompanied with the forming irregularity of the filter base metal in the manufacturing method of a color image sensor by a method wherein a color filter array wherein the upper face thereof is flat, a colorless, transparent coated film is formed on at least the photodiode array part, and the filter base metal is adheringly dyed on the coated film, is formed on the whole surface of the color image sensor. CONSTITUTION:Plural P type regions 2 are formed in the surface part of an N type silicon substrate 1, and at the same time, aluminum wirings 3 are formed on the silicon substrate 1, and a negative-type resist film 7 is formed over the whole area of the photodiode array with the roughened surface, the part of a bonding pad 4 and the part of a scribing line 5. An exposure is performed on the bonding pad 4 and the scribing line 5 like shown by an arrow L through a mask 9 having a chrome film pattern 8, a developing process is performed thereon, and apertures are provided on the bonding pad 4 and the scribing line 5. A positive-type resist 10 is applied from the upper sides over the apertures in such a way as to bury the apertures, an exposure is performed like shown by the arrow L through the mask 9, and a negative-type resist 7 is adhered by performing a developing. As a result, flattening of the whole surface of the color image sensor is attained.

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to a method for manufacturing a color image sensor (solid-state imaging device) in which a color filter array is directly formed on a photodiode array, and particularly relates to a method for manufacturing a color image sensor (solid-state image sensor) in which a color filter array is directly formed on a photodiode array. The present invention relates to a method for flattening the surface of a wafer to be attached.

[Prior art]

When fabricating a so-called direct-mount color image sensor by forming a mosaic or striped color filter array directly on a photodiode array, the pattern accuracy of the filter array is important.

In order to accurately control alignment accuracy, filter film thickness, etc., flattening the surface of the wafer on which the filter array is to be formed is an important issue.

One possible way to solve this problem is to planarize it with an optically transparent inorganic material, but the properties of the deposited film, the complexity of the deposition process, the heat resistance and mechanical strength of the filter material, etc. Due to this limitation, flattening is performed using colorless and transparent organic materials. As this organic material, either a colorless and transparent positive photoresist material or a negative photoresist material is used.

By the way, although positive resist (hereinafter generally referred to as "resist") has the advantage that hole-opening work for bonding butts, scribe lines, etc. required for direct-mount color image sensors can be done in the final process,
There are very few positive resists that satisfy the performance as a color filter constituent material, and those that meet these conditions have extremely low sensitivity and pose a serious problem in practice. Also,
High-sensitivity filters have the drawbacks of poor mechanical strength and heat resistance of the film, and poor adhesion to the filter base material formed thereon.

On the other hand, when using a negative resist, exposure and
Even after repeated development, the process is highly sensitive, so the working time is short and a significant drop in throughput can be avoided, but some holes in the pumping thread and the scribe line are made before forming the filter. Therefore, there is a serious drawback that coating of the filter base material causes significant uneven coating. This coating unevenness becomes uneven dyeing when the base material is dyed to form a color filter, and eventually appears as color unevenness on a television image that reproduces the image pickup signal.

[Summary of the invention]

This invention was made in view of the above points, and a negative resist film is formed on the part where the color filter array is to be formed above the photodiode array forming part of the wafer to flatten the surface and bonding butts are formed. The openings formed in the negative resist film in the area and scribe line area are filled with a positive photoresist film, and
A color image sensor having a good filter array by flattening the entire upper surface and then applying a filter base material thereon to eliminate uneven coating, thereby preventing the occurrence of uneven dyeing when dyeing the base material. The present invention provides a method for manufacturing.

[Embodiments of the invention]

FIGS. 1A to 1D are cross-sectional views showing the main stages of an embodiment of the present invention. N-type silicon substrate (1)
A plurality of p shadow regions (2) are formed on the surface of the silicon substrate (1), and aluminum wiring (3) is formed on the silicon substrate (1) to form a photodiode array having an uneven surface and a bonding butt (4). and the scrypline (
5) A negative resist film (7) is formed over the entire area, and a mask (9) with a chrome film pattern (8) is formed on the bonding butt (4) and the scribe line (5). The bonding bat (4
) and an opening is formed above the scribe line (5) (FIG. 1B). Next, a positive resist Q1 is applied from above so as to fill the above-mentioned openings, and exposed as shown by the arrow through the same mask as that used in the step of FIG. 1C), by developing, a positive resist (11) is deposited on the bonding bat (4) and the scribe line (5), and a negative resist (7) is deposited on the other parts, making the surface flat. is achieved.

When the filter base material was coated on the flat surface obtained in this way, there was almost no unevenness in the coating, and even if it was dyed after the required buttering, there was no unevenness in dyeing and it was excellent. A filter array was obtained. Although the positive resist on the bonding butt (4) and the scribe line (5) must be removed, this can be easily removed by developing the resist in the next step.

Specific example 1゜As a negative resist, an acrylic copolymer solution (concentration 10% by weight) containing 0.2% diazonium salt (based on the solid content of the resist)' (with a step difference of 1.0 to 1.4 μm in the i-photodiode array section) A negative resist film (7) with a thickness of 2.5 μm was formed by applying a drop onto a 4-inch (101 mm) silicon wafer and rotating it at a predetermined number of rotations, and this film was exposed to ultraviolet light with a light output of 500 W. 5 by device
Exposure for seconds and development to form a bonding bat (thickness 2 with holes on the 4th and scribe lines (5)).
A planarization film of μm was formed. Next, a positive-type film (JIS) (10) was applied to a thickness of 3 μm over the entire surface including the inside of the opening, exposed for 10 seconds using the same exposure device, and developed. In this way, the bonding bat (4) and the scrubber Ipline (
5) After filling the upper openings and flattening the surface, apply the filter base material in a 1 μm float on the wafer, perform the required patterning, and then dye it with cyan (blue-green) to obtain a cyan filter. However, no uneven dyeing due to uneven coating was observed.

Of course, when the filter base material was formed directly on the negative resist film (7) without filling the openings with a positive resist, uneven dyeing occurred due to the uneven coating.

Specific example 2゜The step difference in the photodiode array part is about 2 μm, and a polystyrene chloride resist (concentration 15%) is used as a negative resist.
), using a deep ultraviolet exposure device as the exposure device, the thickness of the flattened negative resist film was 2.5 μm1, the thickness of the positive resist film on it was 0.7 μm1, the exposure time was about 20 seconds, and the thickness of the filter base material was The thickness was set to 0.5 μm, and the outside of the fish body was the same as in Example 1, and cyan fill without uneven dyeing was also obtained in this case.

The negative resist used in this invention must have the performance as a general resist, be colorless and transparent after exposure and development, and have good adhesion to the filter base material and wafer surface. It needs to be stable to the solvent in which the base material is dissolved.

Therefore, as a negative resist, even if the resist is colored by the sensitizer itself or the addition of a sensitizer before exposure, it can be used as long as it becomes colorless and transparent by exposure and development.

As can be seen from the above description, the positive resist does not necessarily have to be colorless and transparent, but only needs to have the performance of a normal photoresist. This positive resist does not need to be applied thickly at all, but needs to be adjusted to have a low viscosity so that it flows into and fills the recesses of the bonding pad and dicing line.

In the above embodiment, the resist is a so-called photoresist (
(using ultraviolet or far ultraviolet light as a light source),
X-ray or electron beam resists or even ion beam resists can be used as well.

〔Effect of the invention〕

As explained above, in the present invention, the upper surface is flat over the entire surface including the photodiode array part, bonding butt, and scribe line part, and a colorless and transparent film is formed on at least the photodiode array part, and a filter base material is formed on the film. Since the color filter array is formed by depositing and dyeing, it is possible to prevent uneven formation of the filter base material and the resulting uneven dyeing, and it is possible to manufacture a color image sensor having a good color filter array.

[Brief explanation of the drawing]

FIGS. 1A-1D are cross-sectional views showing the main stages of an embodiment of the present invention. In the figure, (1) is the n-type silicon substrate, (2) is the p-shade region that makes up the photodiode, (3) is the aluminum wiring that makes up the surface unevenness, (4) is the bonding bat, and (5) is the scribe line. , (7) is a negative resist film, (10 is a positive resist film. 0 The same reference numerals in the figures indicate the same or corresponding parts O. Attorney Masuo Oiwa, Commissioner of the Japan Patent Office. 1. Indication of the case. 58-215322 No. 2 Invention (7) Name Color image sensor manufacturing method 3,
Person making the amendment 5, Figure 1 D of the drawing to be amended 6. Contents of the amendment The first diagram of the drawing is corrected as shown in the attached drawing. 7. One or more drawings showing the first drawing after the revised list of attached documents

Claims (2)

[Claims] (1) When forming a color filter array on the diode array part of an image sensor having a photodiode array part having small irregularities on its surface, and a bonding butt and a scribe line part, the diode array part and the After forming a colorless and transparent film on the entire surface including the bonding pad and the scribe line part and having a flat top surface at least on the diode array part, a filter base material is applied on top of this film and it is colored by dyeing it. A method of manufacturing a color image sensor, comprising forming a filter array. (2) A negative resist film with a flat top surface is formed on the photodiode array area and its surroundings, and a positive resist film whose top surface matches the top surface of the negative resist film is formed on the bonding pad and scribe line area. 2. The method of manufacturing a color image sensor according to claim 1, wherein a coating having a flat upper surface is formed over the entire surface of the photodiode array portion, the bonding bat, and the suffix pipeline portion.