JP3158466B2 - Method for manufacturing solid-state imaging device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a solid-state imaging device in which a condenser lens is formed on a substrate.

[0002]

2. Description of the Related Art In some solid-state imaging devices, a color filter is provided on each pixel on a chip. This type of solid-state imaging device is capable of imaging while maintaining color reproducibility.

[0003] Such a solid-state imaging device generally has a flattening layer, a staining layer, and a microlens forming layer on each light receiving portion formed on a substrate. The microlens forming layer is
Each pixel is finely processed on the order of μm on a size basis. A method for manufacturing a solid-state imaging device for forming such a microlens forming layer is disclosed in JP-A-64-106.
No. 66 is disclosed. The solid-state imaging device having the microlens forming layer formed thereon is generally mounted on a ceramic package through a dicing process, and further sealed from the microlens forming layer to the protective glass surface in a hollow state. As a specific example of the size of the microlens of the microlens forming layer of the conventional solid-state imaging device, the radius of curvature is 2.0 μm to 6.0 μm, the lens opening width is 5.0 μm to 10.0 μm, and the lens height is Say 5.
0 to 10.0 μm, and the opening width of the light receiving portion is 1.5 μm to
The refractive index of the lens material forming the microlens forming layer has a value of about 1.6 with respect to 1.0 of air. With these optical configurations, the amount of light condensed by each pixel is increased as compared with the case where no microlens is formed, and the sensitivity is improved about twice.

In addition to a structure in which an element chip is mounted in a ceramic package and a protective glass is mounted on the surface, there is another type in which the element chip is integrally formed of a transparent resin protective package material. In the case where this transparent resin protective package material is used, the refractive index of the transparent resin is about 1.5. Therefore, if the microlens forming layer having the refractive index of about 1.6 is used as it is, the light refraction effect of the microlens is reduced. Will weaken.

[0005]

In order to integrally mold a transparent resin package material with an element chip, it has been studied to use a non-photosensitive transparent material having a high refractive index as a lens base material.
For example, as such a lens base material, there is a polyimide resin.

However, when such a non-photosensitive transparent material having a high refractive index is used as a lens base material, a microlens structure and a bonding pad opening window only by a resist etch-back method conventionally used for the non-photosensitivity are used. It has become difficult to form the same at the same time, and it has been necessary to develop a process unique to a non-photosensitive transparent material having a high refractive index.

In view of the above technical problems, the present invention provides a method for manufacturing a solid-state imaging device using a non-photosensitive transparent material having a high refractive index, such as a polyimide resin layer, as a lens base material. An object of the present invention is to provide a method for manufacturing a solid-state imaging device in which an opening on a pad surface is efficiently formed.

[0008]

In order to achieve the above-mentioned object, the present invention is directed to a substrate on which an electrode pad portion and a light receiving portion are formed, the entire surface of the substrate having the electrode pad portion and the light receiving portion formed thereon. Forming a condensing lens forming layer made of a non-photosensitive transparent material , forming a first photoresist on the entire surface of the substrate, and removing the first photoresist on the electrode pad portion. Forming a second photoresist on the entire surface of the substrate, selectively removing the second photoresist corresponding to the light receiving portion, and removing the second photoresist on the light receiving portion. Heating and first
Forming a second condenser lens prototype by etching back the first condenser lens prototype to the first photoresist, and forming the second condenser lens prototype by etchback. Transferring the original form of the condensing lens of No. 2 to the condensing lens forming layer to form a condensing lens, removing all the layers on the electrode pad portion and exposing the electrode pad portion, and An apparatus is manufactured.

Further, the present invention provides a condensing lens forming layer made of a non-photosensitive transparent material on the entire surface of the substrate on which the electrode pad portion and the light receiving portion are formed, on which the electrode pad portion and the light receiving portion are formed. Forming, forming a first photoresist on the entire surface of the substrate, selectively removing the first photoresist on the electrode pad portion, and collecting light on the electrode pad portion Removing the formation layer;
Removing the remaining first photoresist, forming a second photoresist over the entire surface of the substrate,
Selectively removing the second photoresist corresponding to the light receiving portion, and heating the second photoresist on the light receiving portion to form a condensing lens prototype;
Transferring the original form of the condenser lens to the condenser lens forming layer by etch-back to form a condenser lens, removing the remaining layer on the electrode pad section, and exposing the electrode pad section to form a solid An imaging device is manufactured.

Further, the method according to the present invention includes a step of forming a flattening layer on the surface of the substrate on which the electrode pad portion and the light receiving portion are formed, and further includes dyeing a pixel region on which the light receiving portion is formed. A step of forming a layer may be included.

[0011]

The method of the present invention comprises a first photoresist and a second photoresist.
Are formed, and the two photoresists are selectively exposed to produce a difference in film thickness between the light receiving area and the electrode pad area. Utilizing this difference in film thickness,
At the same time that the condensing lens is formed on the light receiving portion, the condensing lens forming layer and the flattening layer on the electrode pad surface are removed, and the electrode pad portion is exposed to facilitate wire bonding.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described with reference to the drawings.

First, the structure of an example of a solid-state imaging device to be manufactured will be briefly described with reference to FIGS.

As shown in FIG.
An electrode 12 covered with a light-shielding film is formed on a silicon substrate 11, and a region where the light-shielding film is opened between the electrodes 12 is a light receiving unit 13. A plurality of light receiving sections 13 are formed on the silicon substrate 11, and when the solid-state imaging device is an area sensor, the light receiving sections 13 are arranged in a matrix. The surface of the substrate on which the light receiving portion 13 and the electrodes 12 are formed is covered with a flattening layer 14, and a staining layer 15 is formed on the flattening layer 14. The flattening layer 14 is a layer for flattening unevenness due to the electrode 12. The staining layer 15 is a layer for decomposing light having different wavelengths and selectively transmitting the light, and is formed so as to cover the region of the light receiving unit 13. A microlens forming layer 16 for condensing light is formed on the staining layer 15. In this embodiment, particularly, the microlens forming layer 16 is made of a polyimide resin. Each of the microlenses 16a, which is a condenser lens, is formed corresponding to the region of the light receiving section 13 on the substrate. A transparent resin package 17 is formed on the microlens forming layer 16. The transparent resin package 17 directly seals the substrate 11.

FIG. 2 shows a cross section of such a solid-state imaging device. Element chip 1 fixed to lead frame 19a
8 is sealed in the transparent resin package 17.
Since the package is transparent, incident light is incident on the light receiving portion 13 formed on the surface of the element chip 18 via the package. The microlens forming layer 16 and the dyeing layer 15 are formed on the surface 18s of the element chip 18 as described above, and the gold wire 20 is also bonded to an electrode pad portion of the surface 18s as described later. This gold wire 2
The other end of the pin 0 is connected to a pin 19 b protruding outside the transparent resin package 17. First Embodiment Next, a method for manufacturing a solid-state imaging device according to a first embodiment will be described.
The steps will be specifically described with reference to FIGS.

First, as shown in FIG.
On the insulating film 22, a transfer electrode 23 formed by covering an aluminum light-shielding film (not shown) via an interlayer insulating film is formed, and an electrode pad portion 24 is also formed on the insulating film 22. . The electrode pad portion 24 is a region to which a wire is to be bonded later, and is formed in a peripheral region of the chip. On the surface of the silicon substrate 21 sandwiched between the transfer electrodes 23, a light receiving section 25 composed of a photodiode is formed. The light receiving sections 25 are arranged in a two-dimensional matrix if they are area sensors.

A flattening layer 26 is formed on the surface of the substrate on which the transfer electrodes 23 and the like are formed. This planarization layer 26
This is for flattening unevenness due to the transfer electrode 23 and the like, and is made of a non-photosensitive transparent material having a refractive index of about 1.4.
This flattening layer 26 is applied on a substrate and thermally cured. The conditions for the heat curing are 230 ° C. for about 2 minutes, and the film thickness is about 2.0 to 6.0 μm. A dye layer 27 is formed on the flattening layer 26. The dyed layer 27 is a layer having several layers of magenta, cyan, yellow, and the like. The dyed layer 27 is formed by dyeing a protein-based material such as casein with each pigment. The thickness of the dyed layer 27 is about 0.9 to 1.5 μm. The dyed layer 27 is exposed and developed with g-line or i-line during the dyeing process.
This dyed layer 27 is formed only on the pixel region where the light receiving section 25 is formed, and is not formed on the electrode pad section 24.

Next, a polyimide solvent is applied to the entire surface of the silicon substrate 21. This polyimide-based solvent contains a non-photosensitive polyimide precursor. The application condition is 3-4g
, The initial rotation of the spinner is performed at 500 to 900 rpm for 5 seconds, and then the main rotation is performed at 2000 to 3000 rpm for about 15 seconds.
After this spin coating, prebaking is performed. The pre-bake condition is performed using a hot plate or a bake furnace at 80 to 130 degrees Celsius in a nitrogen atmosphere for about 5 to 20 minutes. In this prebaking, volatilization of a solvent such as xylene is promoted, and the polyimide precursor is semi-cured. This prebaking is a low-temperature treatment, and does not adversely affect the lower dyed layer 27. The film thickness of the polyimide precursor is reduced by about 10% after prebaking, and is set to about 4.0 to 8.0 μm.

After prebaking, the polyimide precursor is subjected to a heat curing treatment. The heating curing condition is a baking furnace in a nitrogen atmosphere at 150 to 170 degrees Celsius for 1 to 3 hours.
By this heat curing treatment, an imidization reaction of the precursor is started, and the polyimide resin thin film 28 is formed on the entire surface as shown in FIG. The polyimide resin thin film 28 has a solid content of 15 to 24% and a viscosity of 13.7 to 5.6 when the precursor is applied.
By setting the thickness to about poise, the thickness becomes about 4.0 to 8.0 μm after pre-baking and heating and curing.

After the formation of the polyimide resin thin film 28, FIG.
As shown in (1), a negative resist layer 29 is formed on the entire surface of the polyimide resin thin film. This negative resist layer 29 is applied to the entire surface of the wafer by a spin coater at 2000 to 3000 rpm for 10 to 30 seconds. After the application, 160 degrees Celsius by hot plate
Pre-bake at about 3 minutes. After the pre-bake, the negative resist layer 29 is selectively exposed using a photomask. The exposure of the negative resist layer 29 is selective exposure such that the resist layer 29b on the electrode pad portion 24 is not irradiated with light, and the resist layer 29a in a region other than on the electrode pad portion 24 transmits light. Expose. Of the negative resist layer 29, the exposed resist layer 29
a becomes a polymer and becomes insoluble in the developer, and the resist layer 29b not irradiated with light is soluble in the developer.

After selectively exposing the region other than the electrode pad portion 24 as described above, using a required developing solution, as shown in FIG. The resist layer 29b is removed. By selectively removing the resist layer 29b, an opening 30 is formed in the remaining resist layer 29a. At the bottom of the opening 30, the surface of the polyimide resin thin film 28 is exposed.
After the resist layer 29b is selectively removed only in the region corresponding to the electrode pad portion 24, the resist layer 29 is post-baked. The post bake is performed using a hot plate at about 160 degrees Celsius for 2 minutes. The resist layer 29a remaining after the post-baking has a thickness of, for example, 3.0 μm to 8.0 μm.

Next, as shown in FIG. 7, a second resist layer 31 is formed on the entire surface including the opening 30. This second
The resist layer 31 is made of a positive type resist, and its coating is formed using a spin coater, for example, at a main rotation of 3000.
It is performed under the condition of 30 seconds at rpm. After the application, prebaking of the second resist layer 31 is performed. The pre-bake is performed using a hot plate at 100 degrees Celsius for about 80 seconds. The thickness of the second resist layer 31 is, for example, 1.0 to 3.0 μm.

The pre-baked second resist layer 3
1 is selectively exposed and developed by g-line or i-line. At the time of the selective exposure, a region irradiated with light is a region on the electrode pad portion 24 or a region between individual microlenses. The region selectively irradiated with this light is removed by wet development. The wet development is 2.38 ~
Using 6.0% alkaline developer, 2 degrees Celsius
The immersion is performed at 5 degrees for about 20 seconds to 4 minutes. In FIG. 7, in the second resist layer 31, a region indicated by oblique lines is a region to be selectively exposed. As a result of the wet development, in the region where the microlens is formed, the second resist layer 31a divided only into the portion corresponding to the light receiving portion 25
Remain. In the opening 30, the second resist layer 31 once filled in the opening 30 is removed by development. Therefore, the surface of the polyimide resin thin film 28 faces the bottom of the opening 30.

After the second resist layer 31 is selectively exposed and developed as described above, the original lens 32 is formed by performing a heating reflow as shown in FIG. This reflow is performed using a hot plate at about 150 degrees Celsius for about 2 minutes. By this reflow treatment, the height of the end of the divided second resist layer 31a is reduced, and the lens prototype 32 having a curvature in which the central portion of each pixel projects using the surface tension of the resist layer is formed on the resist layer. 29.

After forming the lens prototype 32 on the negative resist layer 29, as shown in FIG.
Is transferred to the negative resist layer 29. This transfer is performed by etch-back by dry etching.
The etching rate of the resist layer 31, the resist layer 29, and the polyimide resin thin film 28 is constant, and the conversion of the gap width at the time of transfer is 0.1 to 0.2 μm. The etching used for this transfer is performed using, for example, an O ₂ gas or a mixed gas of CF ₄ and O ₂ .

Here, as an example of specific dimensions, the flattening layer 26 has a thickness of 2.0 μm, the dyed layer 27 has a thickness of 1.5 μm, and the polyimide resin thin film 28 has a thickness of 4 μm.
The thickness of the negative resist layer 29 is set to 3.0 μm, the thickness of the positive second resist layer 31 serving as the lens prototype 32 to 1.56 μm, and the like. Then, as shown in FIG. 9, when the negative resist layer 29 is etched to a thickness of about 2.0 μm, the remaining film thickness of the resist layer 29 becomes 1.0 μm.
At this point, the polyimide resin thin film 28 under the resist layer 29 is etched on the electrode pad portion 24 by about 2.0 μm from the bottom of the opening 30.

By such dry etching, a second lens prototype 33 reflecting the shape of the lens prototype 32 is formed in the negative resist layer 29 over the light receiving section 25, and at the same time, the aperture 30 is reflected. Finally, an opening 34 for exposing the electrode pad portion 24 is formed in the polyimide resin thin film 28.

After the second prototype lens 33 is formed on the negative resist layer 29, dry etching is further performed as shown in FIG. By this dry etching, the microlens 35 is formed on the polyimide resin thin film 28 reflecting the shape of the second lens prototype 33.
Then, at the same time as the formation of the microlens 35 made of the polyimide resin thin film 28, the opening 36 formed in the planarization layer 26 reflecting the opening 34 reaches the substrate surface. When the opening 36 reaches the surface of the substrate, the electrode pad portion 24 is exposed.

In this dry etching, the ratio of the etching rate of the resist layer 29 of the second lens prototype 33 to the polyimide resin thin film 28 is set to 1, and the ratio of the etching rate of the flattening layer 26 to the polyimide resin thin film 28 is set to 2 As described above, when the respective film thicknesses are set as described above, the electrode pad portions 24 are surely exposed by the openings 36.

The process shown in FIGS. 9 and 10 can be a continuous process by adjusting the film thickness and controlling the etching rate. For example, each film thickness is
Is 4.0 μm, the dyed layer 27 is 1.5 μm, the polyimide resin thin film 28 is 7.0 μm, the negative resist layer 29 is 8.0 μm, and the positive second resist layer 31 is 1.56 μm.
Set to μm. An opening corresponding to the film thickness is formed in the resist layer 29 by a plurality of selective exposures or the like. And
Only the flattening layer 26 is etched at a rate twice or more the etching rate selectivity at the time of dry etching as compared with the other layers. Etching is performed under the condition that the resist layer 31 is etched at a substantially constant speed. Then
10.0 μm from the surface of the second resist layer 31 continuously
By performing the etching to a certain degree, the microlens 35 made of the polyimide resin thin film 28 is surely formed, and at the same time, the electrode pad portion 24 is exposed through the opening 36.
In addition, as an etching gas, O ₂ gas or CF ₄ /
O ₂ gas or the like can be used.

Next, a micro lens 35 made of the polyimide resin thin film 28 is formed, and the electrode pad portion 24 is formed.
At the upper opening, the wafer is divided into chips, bonded to a lead frame, and then wire-bonded. The wire 37 is connected to a lead frame pin 38,
The electrode pad 24 at the bottom of the opening 36 is electrically connected.

Subsequently, as shown in FIG. 11, each chip is sealed with a transparent resin 39 together with the lead frame. When the resin is sealed with the transparent resin 39, for example, the microlens 35 is formed even when the resin is sealed under the condition of injecting at 150 degrees Celsius for 5 minutes and curing at 100 to 120 degrees for 8 hours. Polyimide resin thin film 2
8 has a high thermal decomposition temperature, so that the microlens 35 itself does not deform.

Further, since the polyimide resin thin film 28 on which the microlenses 35 are formed has a relatively high refractive index of 1.7 to 1.9, the light collection rate can be increased. More than twice the sensitivity can be obtained.

In this embodiment, the structure of the solid-state imaging device to be manufactured is sealed with the transparent resin 39. However, the present invention is not limited to this. It is also possible to apply Second Embodiment Next, a method of manufacturing a solid-state imaging device according to a second embodiment will be specifically described according to the steps with reference to FIGS.

As in the first embodiment, the silicon substrate 41
An insulating film 42 is formed thereon. A transfer electrode 43 is formed on the insulating film 42 by coating an aluminum light-shielding film (not shown) via an interlayer insulating film, and an electrode pad portion 44 is formed of an aluminum material layer. Is also formed. The electrode pad portion 44 is a region where a wire is to be bonded later, and is formed in a peripheral region of the chip. On the surface of the silicon substrate 41 sandwiched between the transfer electrodes 43, a light receiving section 45 composed of a photodiode is formed. The light receiving sections 45 are arranged in a two-dimensional matrix if they are area sensors.

On the surface of the substrate, a flattening layer 46 for flattening unevenness due to the transfer electrode 43 and the like is formed. The flattening layer 46 is made of a non-photosensitive transparent material having a refractive index of about 1.4, applied on a substrate, and thermally cured. The conditions for the heat curing are 230 ° C. for about 2 minutes, and the film thickness is about 2.0 to 6.0 μm. A dye layer 47 is formed on the flattening layer 46. The dyed layer 47 is a layer having several layers of magenta, cyan, yellow and the like, and the dyed layer 47 is formed by dyeing a protein-based material such as casein with each pigment. The thickness of the dyed layer 47 is about 0.9 to 1.5 μm. The dyed layer 47 is exposed to g-rays or i-rays during the dyeing process and developed.
This dyed layer 47 is formed only on the pixel region where the light receiving section 45 is formed, and is not formed on the electrode pad section 44.

Next, as shown in FIG. 12, a polyimide-based solvent is applied on the entire surface of the silicon substrate 41. This polyimide-based solvent contains a non-photosensitive polyimide precursor. The coating condition is 3-4 g, and the spinner initial rotation is 500-9.
00 rpm for 5 seconds, followed by main rotation 2000 to 3000 r
pm for about 15 seconds. After this spin coating, prebaking is performed. The pre-bake condition is such that a hot plate or a bake furnace is used, and the temperature is set to 80 to 1 degree Celsius depending on the nitrogen atmosphere.
This is performed at 30 degrees for about 5 to 20 minutes. In this pre-baking, volatilization of a solvent such as xylene is promoted, and the polyimide precursor layer 48 is semi-cured. This pre-bake is a low-temperature treatment, and does not adversely affect the lower dyed layer 47. The film thickness of the polyimide precursor layer 48 is reduced by about 10% after the pre-baking, and is set to about 4.0 to 8.0 μm.

The prebaked polyimide precursor layer 4
8, a positive resist layer 49 is applied to the entire surface. The application of the positive resist layer 49 is performed, for example, using a spin coater at a main rotation speed of 2000 rpm for 30 seconds. After this application, prebaking is performed on a hot plate at 100 degrees Celsius for 1 to 2 minutes.

After the pre-bake, the positive resist layer 49 is selectively exposed using a required photomask using g-line or i-line. The region irradiated with light by this exposure is only the region on the electrode pad section 44, and the resist layer 49a in this region is polymerized and becomes soluble in the developing solution.

Next, a developer having an alkalinity of about 2.36% to 6.0% is used.
The wet development is performed under the condition of about 1 to 4 minutes. After this wet development, rinsing with pure water at 25 degrees Celsius for about 1 to 4 minutes is performed, and drying is performed at, for example, 3000 rpm for about 30 seconds using a spinner. By such wet development, FIG.
As shown in (1), first, the resist layer 49a in the selectively exposed portion is removed, and subsequently, a part of the polyimide precursor layer 48 is removed by the same developer to form an opening 51. The portion where the polyimide precursor layer 48 is removed is a region on the electrode pad portion 44 corresponding to the resist layer 49a. At the bottom of the opening 51, the surface of the flattening layer 46 is exposed. The portion has a diameter slightly wider than the bottom.

After the polyimide precursor layer 48 on the electrode pad portion 44 is partially removed by wet development, as shown in FIG. 14, the remaining positive type resist layer 49 on the polyimide precursor layer 48 is peeled off. I do. The peeling is performed with acetic acid n
Using a stripping solution in which butyl: isopropyl alcohol is mixed at a ratio of 1: 1 to 5 is immersed at 25 degrees Celsius for about 1 to 2 minutes. Thereafter, rinsing is performed while immersing the same in an n-butyl acetate solution at 25 degrees Celsius for about 1 to 2 minutes. After the rinsing step, 3000 r using a spinner
Dry for about 30 seconds at pm. By wet-peeling with such n-butyl acetate solution diluted with isopropyl alcohol, the polyimide precursor layer 48 and the planarizing layer 46 are removed.
Is not dissolved, and only the positive resist layer 49 is peeled off.

After the positive type resist layer 49 is peeled off, the polyimide precursor layer 48 is cured by heating. The heating and curing treatment is performed in a baking furnace at a temperature of 150 to 170 degrees Celsius for 1 to 3 hours in a nitrogen atmosphere. By this heat curing treatment, an imidization reaction is started in the polyimide precursor layer 48, and complete volatilization of the solvent occurs. As a result, the polyimide precursor layer 48 becomes a polyimide resin thin film 50. In this polyimide resin thin film 50,
When the precursor is applied, the solid content is reduced to, for example, 15 to 24.5.
By adjusting the viscosity to a percentage and setting the viscosity to, for example, 3.7 to 5.6 poise, a film thickness of about 4.0 to 6.0 μm can be obtained after prebaking and heating and curing.

Next, as shown in FIG. 15, a second resist layer 52 is formed on the entire surface including the opening 51. The second resist layer 52 is a positive type resist, and its coating is formed by, for example, main rotation 300 using a spin coater.
This is performed at 0 rpm for 30 seconds. Second after application
Of the resist layer 52 is performed. This pre-bake is performed at about 80 ° C. using a hot plate at 100 ° C.
It is performed on the condition of seconds. The thickness of the second resist layer 52 is, for example, 1.0 to 3.0 μm.

The pre-baked second resist layer 5
2 is selectively exposed and developed by g-line or i-line. At the time of this selective exposure, a region irradiated with light is a region on the electrode pad portion 44 or a region between individual microlenses. The region selectively irradiated with this light is removed by wet development. The wet development is 2.38 ~
Using 6.0% alkaline developer, 2 degrees Celsius
The immersion is performed at 5 degrees for about 20 seconds to 4 minutes. In FIG. 15, an area indicated by oblique lines in the second resist layer 52 is an area to be selectively exposed. As a result of the above wet development,
In a region where a micro lens is formed, the light receiving portion 45 is formed.
Resist layer 52 divided only into portions corresponding to
a remains. In the opening 51, the second resist layer 52 once filled in the opening 51 is removed by development. Therefore, the flattening layer 46 is formed at the bottom of the opening 51.
Faces.

After selectively exposing and developing the second resist layer 52 in this way, as shown in FIG. 16, a heat reflow is performed to form a lens original 53. This reflow is performed using a hot plate at about 150 degrees Celsius for about 2 minutes. By this reflow treatment, the height of the end of the divided second resist layer 52a is reduced, and the lens prototype 53 having a curvature in which the central portion of each pixel projects using the surface tension of the resist layer is made of polyimide. It is formed on the resin thin film 50.

The lens prototype 53 is replaced with a polyimide resin thin film 5
After being formed on the substrate 0, the lens prototype 53 is transferred to a polyimide resin thin film 50 as shown in FIG. Then, when the lens prototype 53 is transferred to the polyimide resin thin film 50, the flattening layer 46 on the electrode pad portion 44 is also removed while reflecting the pattern of the opening portion 51, and the opening portion 54 is formed. You. The transfer of the lens prototype 53 to the polyimide resin thin film 50 results in the polyimide resin thin film 5
A plurality of microlenses 55 are formed at 0. This transfer is performed by etch back by dry etching. As an example of the etching rate, the lens prototype 5
The second resist layer 52 and the polyimide-based resin thin film 50 according to 3 can be made to have the same speed, and the flattening layer 46 can be etched at a rate twice or more as fast as the polyimide-based resin thin film 50. In addition, in the etching used for this transfer, the conversion difference of the gap width during the transfer is 0.1 to
The process is performed under a condition of 0.2 μm, for example, using an O ₂ gas or a mixed gas of CF ₄ and O ₂ . As an example of setting the film thickness for forming the opening 54 in the flattening layer 46 together with the transfer of the lens prototype 53, the flattening layer 46
Is about 2.0 μm to 6.0 μm, and the etch-back amount of the polyimide resin thin film 50 is 2.0 to 3.0 μm.
It may be set to about μm. By setting such a film thickness, the electrode pad portion 44 of the flattening layer 46 has a relation of a selectivity.
The upper opening 54 becomes a through hole, and wire bonding is performed.

Hereinafter, although not shown, the wafer is divided into chips, bonded to a lead frame, and then wire-bonded as in the first embodiment. The wires electrically connect the pins of the lead frame to the electrode pad portions 44 at the bottom of the openings 54. After this wire bonding, each chip is resin-sealed with a transparent resin together with the lead frame. At this time, the micro lens 55
The microlens 55 itself does not deform because the polyimide-based resin thin film 50 on which is formed has a high thermal decomposition temperature.

The polyimide resin thin film 50 on which the microlenses 55 are formed has a refractive index of 1.7 to 1.9.
Is relatively high, the light collection rate can be increased even when resin sealing is performed with a transparent resin, and for example, a sensitivity of twice or more can be obtained as a solid-state imaging device.

In the present embodiment, the package is not limited to the one sealed with a transparent resin, but may be, for example, a ceramic package.

[0049]

As described above, in the method of manufacturing a solid-state imaging device according to the present invention, the first photoresist on the condensing lens forming layer made of a non-photosensitive transparent material has the second lens forming an original lens. Before the photoresist is formed, a concave portion such as an opening is formed on the electrode pad portion. Therefore, during the transfer process of the lens original shape, an opening reflecting the concave portion is formed at the same time, and the electrode pad portion can be exposed. Therefore, even when a non-photosensitive transparent material is used for the light collecting lens forming layer, wire bonding can be easily performed to the electrode pad portion while maintaining the light collecting property of the micro lens sealed with the transparent resin.

In addition, by using a polyimide resin layer having high heat resistance as the light-collecting lens forming layer, deformation of the lens can be prevented even when resin sealing is performed.

[Brief description of the drawings]

FIG. 1 is a sectional view showing the vicinity of a light receiving section of a solid-state imaging device manufactured by a method of the present invention.

FIG. 2 is a sectional view showing a package in which a solid-state imaging device manufactured by the method of the present invention is resin-sealed using a transparent resin.

FIG. 3 is a process sectional view up to the step of forming a stained layer in the first embodiment of the method of the present invention.

FIG. 4 is a process sectional view up to the step of forming a polyimide resin thin film in the first embodiment of the method of the present invention.

FIG. 5 is a process sectional view up to a selective exposure process of a resist layer in the first embodiment of the method of the present invention.

FIG. 6 is a process sectional view up to a step of developing a resist layer that has been selectively exposed in the first embodiment of the method of the present invention.

FIG. 7 is a process sectional view up to a selective exposure step of a second resist layer in the first embodiment of the method of the present invention.

FIG. 8 is a sectional view of a process up to the step of forming a lens original by using a second resist layer in the first embodiment of the method of the present invention.

FIG. 9 is a process cross-sectional view up to a transfer step of transferring an original lens shape to a resist layer in the first embodiment of the method of the present invention.

FIG. 10 is a process cross-sectional view up to the step of forming a microlens and the step of forming an opening on the electrode pad portion in the first embodiment of the method of the present invention.

FIG. 11 is a process cross-sectional view up to the transparent resin sealing step in the first embodiment of the method of the present invention.

FIG. 12 is a sectional view showing a process up to a selective exposure step of a resist layer in a second embodiment of the method of the present invention.

FIG. 13 is a process cross-sectional view up to a wet development process of a resist layer and a polyimide precursor layer in a second embodiment of the method of the present invention.

FIG. 14 is a process cross-sectional view up to the step of removing a resist layer in a second embodiment of the method of the present invention.

FIG. 15 is a process sectional view up to a selective exposure step of a second resist layer in a second embodiment of the method of the present invention.

FIG. 16 is a process cross-sectional view up to the step of forming an original lens in the second embodiment of the method of the present invention.

FIG. 17 is a process cross-sectional view up to an etching process for simultaneously transferring a lens shape to a polyimide-based resin thin film and opening a flattening layer on an electrode pad portion in a second embodiment of the present invention.

[Explanation of symbols]

21, 41 silicon substrate, 22, 42 insulating film,
23, 43 transfer electrode, 24, 44 electrode pad part,
25, 45 light receiving section, 26, 46 flattening layer, 2
7,47 staining layer, 28,50 polyimide resin thin film, 29 resist layer, 30,34,36,51,
54 opening, 31 second resist layer, 32,5
3 original lens shape, 33,55 micro lens, 5
2 Resist layer

Claims (6)

(57) [Claims] A step of forming a light-condensing lens-forming layer made of a non-photosensitive transparent material on the entire surface of the substrate on which the electrode pad portion and the light receiving portion are formed; Forming a first photoresist on the entire surface of the substrate; removing the first photoresist on the electrode pad portion; forming a second photoresist on the entire surface of the substrate; Selectively removing a second photoresist corresponding to the light receiving portion; heating the second photoresist on the light receiving portion to form a first condensing lens prototype; Transferring the first condensing lens prototype to the first photoresist by backing to form a second condensing lens prototype; and forming the second condensing lens prototype by etching back to form the condensing lens. In layers Thereby forming a copy condensing lens,
Removing all layers on the electrode pad portions to expose the electrode pad portions. 2. The method for manufacturing a solid-state imaging device according to claim 1, further comprising a step of forming a planarization layer on a surface of the substrate on which the electrode pad portion and the light receiving portion are formed. 3. The method for manufacturing a solid-state imaging device according to claim 1, further comprising a step of forming a staining layer on a pixel region where the light receiving section is formed. Forming a condensing lens forming layer made of a non-photosensitive transparent material on the entire surface of the substrate on which the electrode pad portion and the light receiving portion are formed; Forming a first photoresist on the entire surface of the substrate, selectively removing the first photoresist on the electrode pad portion, and removing a condensing lens forming layer on the electrode pad portion A step of removing the remaining first photoresist; a step of forming a second photoresist over the entire surface of the substrate; and selectively applying the second photoresist to the light receiving unit. Removing, heating the second photoresist on the light receiving unit to form a condensing lens original form, transferring the original condensing lens form to the condensing lens forming layer by etch-back, and condensing lens And forming, by removing the remaining layer on the electrode pad portions, the manufacturing method of the solid-state imaging device and a step of exposing the electrode pad portion. 5. The method for manufacturing a solid-state imaging device according to claim 4, further comprising a step of forming a flattening layer on a surface of the substrate on which the electrode pad portion and the light receiving portion are formed. 6. The method for manufacturing a solid-state imaging device according to claim 4, further comprising a step of forming a staining layer on a pixel region where said light receiving section is formed.