JPH03211768A - Manufacture of solid-state image sensor - Google Patents

Abstract

PURPOSE:To prevent ths decrease in yield ratio due to nonuniform imaging and form pad windows accurately by forming a water-soluble resin film on A first resist film, and then coating it with a protective film that is insoluble in the developer for a second resist film, before the second resist film is formed. CONSTITUTION:A water-soluble resin film 9 is applied on a protective film 6, and a first resist film 10 for protecting the water-soluble resin is applied on the film 6. A second resist film 11 to be used to form pad windows is applied on the resist film 10. Since the two resist films are separated by the water-soluble resin film 9, they will not be mixed, thus preventing formation of an insoluble interface. The first resist film 10 between the resin film 9 and the second resist film 11 is insoluble in the developer for the second resist film 11. When the second resist film 11 is patterned, therefore, the resin film 9 is protected from the developer so that it may not be dissolved sideways.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for manufacturing a solid-state image sensor having a bonding pad portion near a photoelectric conversion portion.

[Prior Art] FIG. 2 shows a cross-sectional structure of an example of a color solid-state image sensor having a bonding pad portion near a photoelectric conversion portion.

In the figure, 1 is a solid-state image sensor substrate, and 2 is a light receiving section 2 that generates and accumulates charges upon receiving incident light that becomes image information.
3 is a photoelectric conversion section consisting of a transfer section 2b for transferring charges generated and accumulated in the light receiving section 2a, and 3 is a bonding pad section formed on the solid-state image sensor substrate 1 near the photoelectric conversion section 2. It is an aluminum electrode.

4 is a flattening film formed to suppress the unevenness of the surface of the photoelectric conversion fill 2 to a certain value or less. 6 is a color filter of three primary colors formed on this flattening film 4 corresponding to the light receiving part 2& of the photoelectric conversion part 2, 5r is a first dyeing layer (red layer), and 5g is a second dyeing layer ( green layer), 5b
6 is a third dyeing layer (blue layer), and 6 is a protective film formed on the color filter 5. A pad window 7 is provided for bonding to the aluminum electrode 3.

FIG. 3 shows a cross-sectional structure of an example of a color solid-state image sensor having a bonding pad portion near a photoelectric conversion portion. In FIG. 3, parts corresponding to those in FIG. 2 are designated by the same reference numerals.

In the example shown in FIG. 3, each light receiving section 2a of the photoelectric conversion section 2 is
A microlens 8 is formed correspondingly.

Since the incident light is focused on each light receiving section 2a by the microlens 8, the sensitivity can be improved.

The color solid-state tS image element shown in FIG. 2 is manufactured by the following steps.

First, aluminum electrodes 3 as bonding pad portions are deposited in a predetermined pattern on the solid-state image sensor substrate 1 on which the photoelectric conversion portion 2 is formed (as shown in FIG. 4A).

Next, a flattening film 4 is applied onto the photoelectric conversion section 2 and the aluminum electrode 3 on the solid TM image element substrate l, and is cured by a process such as heating (as shown in FIG. 2B).

This flattening III 4 is made of, for example, acrylic resin, urethane resin, polyimide resin, epoxy resin, alkyd resin, phenolic resin, silicone resin, glass resin,
It is made of synthetic resin such as urea resin and polyester resin.

Next, a first dye layer 5rltM which constitutes the color filter 5 is formed on the flattened layer 11m14 (as shown in FIG. 3C). This first dye N5r is formed by applying a dyeing photosensitive solution consisting of, for example, ceratin, casein, gryu polyvinyl alcohol, etc. and dichromate, performing selective exposure and development to form a pattern, and applying this pattern to the red substrate. It is formed by immersing it in a dyeing solution. After pattern dyeing, the dye is fixed and the dyed layer is cured using an aqueous tannic acid solution, an aqueous antimonylpotassium tartrate solution, a formaldehyde aqueous solution, etc. to avoid color mixing in the dyed layer thereafter.

Next, the same process as the formation of the first dyed layer 5 is carried out.
By repeating the process while changing the type of n, a second dyed layer 5g and a third dyed layer 5b are formed on the flattened layer 114. As a result, a color filter 5 of three primary colors is formed (as shown in the figure).

Next, a protection Im6 is formed on the color filter 5 (as shown in FIG. E). The material of this protective film 6 is, for example, the same as that of the flattened film 4, and is cured by heating or the like in the same manner as the flattened film 4.

Next, a resist film 11 for pad window opening is coated on the first resist film 6, and patterning is performed by photolithography (as shown in FIG. F).

Next, tri-etching is performed in a plasma atmosphere consisting of fluoride carbon ICF- and #1 element 02 to remove the flattening film 4 and protective film 6 on the aluminum electrode 3 to form a butt window 7 (G in the same figure). (illustrated).

Finally, 11111 parts of the resist film 11 for the butt window opening are removed (as shown in Fig. 1).

Furthermore, the color solid-state image sensing device shown in the example shown in FIG. 3 requires 11 steps as described below.

The color filter 5 is manufactured in the same manner as in the manufacturing process of the example shown in FIG.
After a protective film 6 is formed on the protective film 6, a microlens lens 1118' is coated on the protective film 11B, and patterning is performed by dry etching in a plasma atmosphere consisting of fluorocarbon CF a and oxygen 02. (Illustrated in Figure 4!), lens) 11B' is, for example, a negative-type photosensitive 1! for ultraviolet or far ultraviolet light. tj& is applied by a spin code method or the like.

Next, the resist film 8' is thermally deformed by heat treatment to form a spherical microlens 8 (as shown in J in the same figure), and the microlens 8 is exposed by irradiation with ultraviolet rays or far ultraviolet rays. harden the lenses 8.

Next, a resist film It1i:m for forming a pad window is formed on the microlens 8, and patterning is performed by photolithography (as shown in FIG. 6K).

Next, dry etching is performed in a plasma atmosphere consisting of fluorocarbon CFa and oxygen 02 to remove the flattening film 4 and protective film 6 on the aluminum electrode 3, thereby forming a pad window 7 (as shown in the same figure). .

Finally, the resist film 11 for forming the pad window is peeled off (as shown in FIG. 2M).

[Problems to be Solved by the Invention] As described above, in the process of forming the butt window 7, the two-layer resist film (protective film 6 or microlens 8 (microlens resistor) 118') and the butt window opening are not used. When using the resist film 11), since all resist films generally use organic solvents, some of the solvents mix at the interface of the resist film, and then the resist film 11 is peeled off between the pad windows. However, an interfacial layer that is insoluble in the stripping solution is formed.

Since this interface layer is formed non-uniformly and reduces transmittance, imaging unevenness due to non-uniform transmittance increases and yield decreases.

Although not mentioned above, it is also considered that the step of forming the butt window 7 by applying the resist film 11 for opening the butt window is performed after the flattening film 4 is formed. In this case as well, an interface layer is formed at the interface of the resist film, and this W surface layer obstructs the formation of a color filter in the next step, and also causes unevenness in imaging due to non-uniform transmittance.

Here, it has been proposed that a water-soluble resin film be interposed between two resist films to prevent the formation of a compatible or insoluble W surface layer between the resist films (Japanese Patent Laid-Open No. 1983-1982-1).
175725).

However, the upper lens) Ill (the lens with a butt window opening)
After patterning in II), when the exposed water-soluble resin film portion is removed with water or a solution containing water, dissolution progresses in the site direction, making it difficult to form a highly accurate resist pattern, and also due to pattern lift-off. Peeling of the upper resist film causes dust.

Therefore, in the present invention, it is possible to prevent the formation of an insoluble interface layer that would cause unevenness between the resist films, and to form a pattern of the resist film between the butt windows with high precision.

[f! Means for Solving the Problem] The present invention is a method for manufacturing a solid-state #IA image element having a bonding pad portion near a photoelectric conversion portion, and the method includes a method for manufacturing a solid-state #IA image element having a bonding pad portion near a photoelectric conversion portion. 1st
A second resist film for forming a bat window opening is formed on the resist film and patterned. When forming a pad window leading to the bonding pad portion, a water-soluble resin film and a second resist film are formed on the first resist film. After forming a protective resist film of a water-soluble resin film insoluble in the IR image solution of the resist film in this order, a second film is formed.
This method is characterized by forming a resist film of.

[Function] In the above method, since the water-soluble resin 1119 is interposed between the first resist film and the second resist film 11 for the butt opening, the two resist films are not mixed. , the formation of an insoluble interfacial layer is prevented.

Moreover, since the resist film 1° on the water-soluble resin film 9, which is insoluble in the developer containing 1 μl of the second resist, is interposed between the water-soluble resin M9 and the second resist film 11 used for bat window opening.
I! ! In the patterning gap of the resist film 11 of No. 2, a water-soluble resin [1 film 9 is protected from the developer, and this water-soluble resin
9 site direction is prevented.

[Example] Hereinafter, an example of a method for manufacturing a solid-state image sensor according to the present invention will be described. This example is an example of manufacturing a color solid-state image sensor as shown in FIG. 2.

First, as shown in FIG. 1 A-E (same as FIG. 4 A-E), an aluminum electrode 3 is formed on a solid-state tS image element substrate 1 on which a photoelectric conversion section 2 is formed, as in the conventional case. Planarization If! on the photoelectric conversion section 2 and aluminum electrode 3. [Form 4,
A color filter 5 is formed on this flattened t[4, and a protective film 6 is roughly formed on this color filter 5.

Next, a water-soluble resin fl[9 is applied on the ring 1tIIe,
Furthermore, a water-soluble resin film protection resist film 10 is applied on this water-soluble resin film 9. Then, a pad opening resist film 11 is applied onto this water-soluble resin film protective resist film 10, and patterning is performed by photolithography (as shown in FIG. 1F).

The water-soluble resin film 9 is for separating the protection 11116 and the resist film 11 for pad window opening and preventing the formation of an interface layer between the two resist films, and is made of polyvinyl alcohol, methyl cellulose, etc. It is formed.

The water-soluble resin II protective resist film 10 is required to be a synthetic resin that is insoluble in the resin IJIII developer for bat window opening. For example, acrylic resin, urethane resin,
It is made of polyimide resin, epoxy resin, alkyd resin, phenol resin, silicone resin, glass resin, urea resin, polyester resin, etc.

This water-soluble resin film protective resist film 1O needs to be thick enough to block the developer of the resist film 11 for opening the bat window, but it should be less than the thickness of the water-soluble disease N film 9. is desirable. The reason for this is to facilitate the peeling off of the water-soluble resin film 9 and the resist film 10 of the water-soluble resin film 1 when forming a butt window by etching the bonding pad portion, which will be described later. That is, since the water-soluble resin film protective resist film 10 is peeled off by lift-off when the water-soluble resin film 9 is peeled off, if the water-soluble [1 film protective resist film 10 is too thick, lift-off will be difficult to occur.

Next, dry etching is performed in a plasma atmosphere consisting of fluorocarbon CF 4 and oxygen 02 to remove the flattening film 4, the holding film 6, the water-soluble resin 1119, and the water-soluble WIII film protective resist film 10 on the aluminum electrode 3. This is removed to form a bad window 7 (as shown in FIG. 7G).

Finally, the resist film 11 used for opening the pad window is peeled off, and the water-soluble resin film 9 and the water-soluble resin film protective resist film 10 are peeled off using a hot water spin etching device (
At this time, the water-soluble resin II 9 is eluted by the hot water, and the resist film 10 is lifted off and peeled off.

In this method, since the water-soluble resin film 9 is interposed between the protective film 6 and the resist M11 for opening the butt, the two resist films are not mixed, and an insoluble interfacial layer is formed. This makes it possible to prevent the formation of the interface layer, thereby avoiding a decrease in yield due to imaging unevenness caused by the interface layer.

In addition, water-soluble resin film 9 and pad window opening lens) 111
11, a water-soluble resin film protective resist film 10 which is insoluble in the developer of the resist film 1 for pad window opening is interposed, so that the pad window opening can be carried out using the developer when patterning the resist film 11 for pad window opening. The water-soluble resin film 9 is further protected, the water-soluble resin film 9 can be prevented from dissolving in the site direction, and the pattern for forming the pad window 7 can be formed with high precision.

Next, the solid-state image sensor according to the present invention! Another example of the ll method will be explained. In this example, a color solid-state image sensor as shown in FIG. 13 is manufactured.

First, as shown in FIGS. 1A to 1J (FIGS. 4A to 1), aluminum electrodes 3 are formed on the solid-state image sensor substrate l on which the photoelectric conversion IIB 2 is formed in the same way as before. A flattening film 4 is formed on the photoelectric conversion part 2 and the aluminum electrode 3, a color filter 5 is formed on this flattening film 4, a protection layer 1lI6 is formed on this color filter 5, and this protective film is roughly formed. A microlens 8 is formed on 6.

Next, a water-soluble resin film 9 is applied on the microlens 8,
Furthermore, a water-soluble resin film protection resist film 10 is applied on this water-soluble resin film 9. And the second water-soluble resin M l
A pad window opening resist film 11 is applied on the ji' protection resist film 10 and patterned by photolithography (as shown in FIG. 1K).

Next, tri-etching is performed in a plasma atmosphere consisting of fluorocarbon CF and oxygen 02 to remove the flattened M4, protective film 6, water-soluble resin I119 and water-soluble resin film protective resist film 10 on the aluminum electrode 3. to form a pad window 7 (as shown in the figure).

Finally, the pad window opening resist film 11 is peeled off and the water-soluble resin film 9 and the water-soluble resin film protective resist film 10 are removed using a warm water spin etching device (as shown in FIG. M). The water-soluble resin film protective lens) INI O is peeled off by elution of the water-soluble resin film 9 by hot water and lift-off.

In this method, since the water-soluble resin film 9 is interposed between the microlens 8 (resist film 8' for microlens) and the resist film 11 for pad opening,
The two resist films are not mixed together, and it is possible to prevent the generation of an insoluble interface layer, and it is possible to avoid a decrease in yield due to imaging unevenness caused by the interface layer.

In addition, the water-soluble resin film 9 and the resist film 11 for opening the batt window are
In between, the bat window opening is the development of the resist 11! Since the protective resist film 10 is interposed with an insoluble water-soluble resin film, the cyst film is not used for opening the bat window! During patterning of l, the water-soluble resin film 9 is protected from the developer, and dissolution of this water-soluble resin film 9 in the site direction can be prevented, and the pattern for forming the batt window 7 can be formed with high precision. .

In addition, in the above example, the first lurgist film has protection 1! IE
Although the example shown is a microlens 8, the process of forming the butt window 7 by applying a lens (for opening the butt window) III is also applicable to those in which the step of forming the butt window 7 is performed after the flattening film 4 is formed. can do. In this case, the first Lujist film is the flattening film 4, and the same effects can be obtained, and the interface layer does not interfere with the formation of the color filter.

Further, in the above example, a method for manufacturing a color solid-state image sensor having a color filter 5 is described, but it goes without saying that the present invention can be similarly applied to manufacturing a monochrome solid-state image sensor. . In short, it is a solid-state imaging device that has a bonding pad part near the photoelectric conversion part, and a second resist film for forming a bat window opening is formed and patterned on the first resist film. It can be well applied to those forming a communicating pad window.

[Effects of the Invention] As explained above, according to the present invention, since the water-soluble resin film is interposed between the first resist film and the second resist film used for the pad window opening, the two resists are separated. The films do not mix, the generation of an insoluble interface layer can be prevented, and a decrease in yield due to imaging unevenness caused by the interface layer can be avoided. In addition, since a water-soluble resin film protective resist film that is insoluble in the developer of the second resist film is interposed between the water-soluble resin film and the second resist film used for pad window opening, the second resist film The water-soluble resin film is protected from the developer during the patterning gap, and the water-soluble resin film can be prevented from dissolving in the side direction, and the pattern for forming the bat window can be formed with high precision.

[Brief explanation of drawings]

FIG. 1 is a manufacturing process diagram explaining the present invention in detail, FIGS. 2 and 3 are configuration diagrams of an example of a solid-state image sensor, and FIG. 4 is a manufacturing process diagram explaining a conventional example.・Solid TM developer substrate ・Photoelectric conversion section ・Aluminum electrode ・Planarization film ・Color filter ・Fit retention film ・Bat window ・Micro lens 9...Water-soluble resin film 1O...Water-soluble resin film protective resist film 11・・・Resist film for pad window opening

Claims (1)

[Claims] (1) In a method for manufacturing a solid-state image sensor having a bonding pad portion near a photoelectric conversion portion, a second resist film for opening a pad window is formed on the first resist film and patterned, and the bonding pad portion is When forming a communicating pad window, a water-soluble resin film and a water-soluble resin protective resist film insoluble in the developer of the second resist film are formed in this order on the first resist film, and then the second resist film is formed. A method for manufacturing a solid-state imaging device, characterized by forming a resist film.