JPS6382325A - Light receiving element - Google Patents

Abstract

PURPOSE:To simplify and miniaturize a constitution, by a method wherein a color filter layer composed of a polyimide resin containing org. pigment is provided so as to contact with a light receiving surface and an infrared ray blocking layer composed of an org. material is provided so as to contact with said filter layer. CONSTITUTION:A light receiving element 10 is used as the white balance sensor of a color video camera so as to be capable of measuring the intensities of R(red light), G(green light) and B(blue light). Light receiving parts 2 are formed to the surface of an Si-substrate 1 by a usual process and red, green and blue filters 3, 4, 5 are respectively provided to the surfaces of the light receiving parts 2 so as to cover said light receiving surfaces and the vicinities thereof and org. infrared ray absorbing films 6 are applied to the surfaces of said filters 3-5. The light receiving element 10 having the color filters 3-5 and the infrared ray absorbing film 6 provided to the light receiving surfaces thereof is held to a chip carrier 60 by die-bonding. A bonding pad part composed of an Al-film is formed to the edge part of the light receiving 10 and connected to the conductive part of the chip carrier 60 through a bonding wire 50.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a light receiving element having a color filter.

(Conventional technology) Conventionally, gelatin, casein, polyvinyl alcohol (P
A dyeing substrate made of an organic substance such as VA) is dyed with a dye 8! A membrane color filter is used. In addition, as an organic film color filter with improved heat resistance and light resistance,
Color filters made of polyimide resin containing pigments have been proposed.

Compared to color filters formed by other vapor deposition or electrodeposition methods, these organic film color filters can be patterned using photolithography, making it possible to make them finer and easier to align them with the light receiving area. It has the advantage of being However, organic films transmit almost all infrared wavelength light, so in most cases it is necessary to add an infrared absorption filter to obtain the desired spectral 3 degree characteristics.

This will be explained using an example of a white balance sensor for a color video camera. FIG. 10 shows the spectral sensitivity characteristics of a desired white balance sensor, which has sensitivity over the entire visible light range and is not sensitive to ultraviolet light or infrared light. In order to obtain this spectral three-degree characteristic, an organic film color filter having spectral transmittance characteristics as shown in FIGS. 12(a), (b), and (e) is used. The color filters 5.4.3 for detecting blue light, green light, and red light are each formed on a glass substrate as shown in FIG. Either the relative positional relationship is adjusted (bonding method), or as shown in FIG. As can be seen from Figure 12 (a), (b), and (c), the organic film color filter has a blocking property against ultraviolet light and is opaque, but the blue filter (the same figure)
a)), the green filter ((b) in the same figure), and the red filter ((C) in the same figure) all have transmission characteristics for infrared light. Incidentally, the spectral transmittance characteristics of the light receiving section 2 itself of the silicon light receiving element 10 are as shown in FIG. 13, and are sensitive to infrared light as well. Therefore, in order to cut the infrared light incident on each of the color filters and further change the characteristics of the red filter to those shown in FIG. 10, the infrared absorption characteristics of the spectral sensitivity shown in FIG. The filter IR is placed in front of the color filter. A specific example of the configuration in which the light receiving element 10 is packaged as a final product is shown in FIGS. 15 and 16. FIG. 15 shows the case where the chip carrier 60 is used, and FIG. 16 shows the case where the lead frame 30 is used, but in either case, it is necessary to externally attach an infrared absorption filter IR.

(Problems to be Solved by the Invention) As mentioned above, in the case of a light receiving element using an organic film color filter, the optical system is complicated because it is necessary to separately arrange an infrared absorption filter IR in the optical system. This poses a problem in that it hinders miniaturization and increases costs.

The present invention has been made in view of these points,
The purpose is to add an on-chip type organic film filter with infrared absorption characteristics to the light receiving surface.
To provide a light receiving element that does not require an external infrared absorption filter.

(Means for Solving the Problems) In the light receiving element according to the present invention, a color filter layer made of a polyimide resin containing an organic pigment is provided in contact with the light receiving surface, and an organic pigment is provided in contact with the color filter layer. It is provided with an infrared blocking layer made of a material.

(Function) In the light-receiving element according to the present invention, a colored polyimide filter is provided in contact with the light-receiving portion, and an infrared blocking layer made of an organic material is further provided in contact with the colored polyimide filter. Therefore, the infrared light component of the incident light is blocked by the infrared blocking layer, and desired spectral detection characteristics can be obtained, and there is no need to attach an external infrared blocking filter separately from the light receiving element.

(Example) FIG. 1 is a diagram showing a cross-sectional structure of a light receiving element 10 according to an example of the present invention. This light receiving element 10 is used as a white balance sensor of a color video camera, and is used for R (red light), G (green light), and B (blue light).
The light intensity can be measured. A light receiving section 2 is formed on the surface of the silicon substrate 1 using a normal semiconductor manufacturing process, and a red filter 3, a green filter 4, and a blue filter 5 are provided on the surface of each light receiving section 2, respectively. It is provided so as to cover the top and its vicinity. An organic infrared resistant film 6 is applied to the surface of each of the filters 3 to 5. A wiring section made of aluminum film 7 is exposed at the edge of silicon substrate 1 .

FIG. 2 is a sectional view of a structure in which the above-described light receiving element 10 is mounted on a chip carrier 60 for surface mounting.

A light receiving element 10 having color filters 3 to 5 and an infrared absorbing film 6 on its light receiving surface is held by being firmly bonded to a chip carrier 60. A bonding pad portion made of an aluminum film is formed at the edge of the light receiving element 10 (see FIG. 1), and this bonding pad portion is connected to a conductive portion of the chip carrier 60 (not shown) via a bonding wire 50. ). Note that the inside of the chip carrier 60 is filled with transparent resin 20.

FIG. 3 is a sectional view of a structure in which the above-mentioned light receiving element 10 is mounted on a lead frame 30. The light receiving element 10 is bonded onto a tab portion 31 located at the center of the lead frame body 3o using a conductive adhesive pII40. Inner lead end 32 of lead frame main tree 30
One end of the bonding wire 50 is connected to. The other end of the bonding wire 50 is connected to the light receiving element 10
is connected to the pounding pad. The outer lead 33 of the main body 30 of the lead frame 11 is electrically connected to the inner lead end 32, and the light receiving element 10
This serves as an external lead wire.

Note that the light receiving element 10 is entirely molded in a transparent resin 20.

FIG. 4 is a diagram showing the manufacturing process of the above-mentioned light receiving element 10. Moreover, FIG. 5 to FIG. 7 are explanatory diagrams of each process. Hereinafter, the manufacturing process of the light receiving element 10 will be explained with reference to these figures. Incidentally, although each process in FIGS. 5 and 6 is performed on a wafer basis, each drawing shows only one chip. Further, in FIGS. 5 and 6, wiring is omitted.

(i) Color paste application, semi-curing process (fifth
(See Figure (a)) First, a heat-resistant color paste 8 for a color filter is applied to the surface of the silicon substrate 1 on which the light receiving section is formed.

At this stage, the silicon substrate 1 is being processed not in units of individual chips but in units of wafers. Heat-resistant color paste 1-8 consists of a solvent, an organic pigment insoluble in the solvent, and a polyimide precursor. When coating, the silicon substrate 1 on which the light receiving part has been formed is heated with N2 at 200°C.
After drying in the gas for 10 minutes, the first color paste 8f! : Drop a small amount onto the silicon substrate 1, and use a spinner (for example, Mikasa IIJIH-DS type) to
5 seconds at Q rpm, then 3000 rpm+
A coating film is formed at a rotation speed of * for 30 seconds. This coated film is semi-cured for 30 minutes in air at 140° C. using a ventilation dryer. As the first color paste 8, any color among red, green, and blue may be used.

FIG. 8 is a diagram showing how color base I-8 is applied using a spinner. A color paste 8 is obtained by mixing an organic pigment with a mixture of a solvent and a polymer, and this color paste 8 is poured onto the surface of a silicon substrate 1 from, for example, a beaker (see Fig. 8 (a)). The color paste 8 poured onto the surface of the silicon substrate 1 is uniformly dispersed over the surface of the silicon substrate 1 by centrifugal force (see Fig. 8).
b)). FIG. 9 is a diagram showing the relationship between the rotation speed of the spinner and the coating film thickness. As is clear from this figure, by increasing the number of rotations of the spinner, the thickness of the coating film can be reduced. In FIG. 9, each line indicates the characteristics when applying color paste (red ○ mark, green Δ mark, blue mark).

Examples of the components of the heat-resistant color paste 1 used in the color paste application process are as follows.

Color paste ■) General formula % Formula % However, R1: aromatic hydrocarbon ring or heterocycle R2: polymer 10 represented by hydrogen or a hydrocarbon group having 1 to 10 carbon atoms
0g, for organic pigments, red face "1", color index No. 739
05 pigment Rec1209, same No. 46500
A quinacridone pigment such as Pigment Violet 19; or as a green pigment, Color Index No. 7416
Phthalocyanine green pigments such as Pigment Green 36 with No. 0 and Pigment Green 7 with No. 74260; or, as a blue pigment, Pigment Green 7 with Color Index No. 7416;
0 pigment BIue15 3, same No. 74160
A heat-resistant color paste for a color filter, comprising a phthalocyanine blue pigment such as Pigment Blue 15-4 mixed in a proportion of 10 to 300 g.

Effects Car Paste ■ General Formula However, R1: aromatic hydrocarbon ring or heterocycle R2: polymer 10 represented by hydrogen or a hydrocarbon group having 1 to 10 carbon atoms
For 0g of organic pigment, the color paste (
A heat-resistant color paste for color filters prepared by mixing 10 to 300 g of the same red pigment, green pigment, or blue pigment as used in I).

General formula, R1: aromatic hydrocarbon ring or heterocycle R2: polymer 10 represented by hydrogen or a hydrocarbon group having 1 to 10 carbon atoms
For 0g of organic pigment, the color paste (
A heat-resistant color paste for color filters made by mixing 10 to 300 g of the same red pigment, green pigment, or blue pigment as used in 1).

As the color paste 8 applied to the silicon substrate 1, any one of the above (1) to (I[[) may be used for the color base 1. Before applying the color paste, In order to flatten the unevenness, a transparent polyimide layer may be coated on the light-receiving surface.

(ii) Resist coating and prebake process (Fig. 5(b)
) 9) In this embodiment, the semi-cured silicon substrate 1 coated with the color paste 8 is taken out of the ventilation dryer, waits for it to cool down, and then coats the photoresist 9.
A positive resist "Microposit Photoresist 1400-31" (trade name) manufactured by Sibley was used.

The application of the photoresist is also carried out using a spinner, with a rotation speed of 500 rpII for 5 seconds and then 20 seconds.
A coating film is formed at a rotation speed of 0 Orpm for 30 seconds. Prebaking is performed for 30 minutes in nitrogen gas (N2 gas) at 90° C. using a ventilation dryer.

(iii) Exposure process (see Fig. 5(c)) Next, after adjusting the exposure position on the silicon substrate 1 using a mask aligner, exposure of 70 mJ is performed, and the photo is exposed only on the light receiving surface and its vicinity. Photomask 1 so that the registry remains
Exposure to ultraviolet light is performed through 1.

(iv) Resist development and etching process (Fig. 5(d)
) Low light) Next, the exposed photoresist on the silicon substrate 1 is developed. As the current eF (I, use a 1:1 mixture of Microposit 'MP-312 developer °'' (product name) manufactured by Sibley and water at a liquid temperature of 22
The resist is developed for 60 seconds at .degree. C., and then the excess color paste layer is etched.After the etching, the silicon substrate 1 is rinsed with water and dried by blowing N2 gas.

(v) Resist peeling, rinsing, and curing process (see Figure 5(e) 9) Next, in order to peel off the photoresist 9 remaining on the color paste layer, the silicon substrate 1 is placed in ethyl acetate. After 5 minutes, it was taken out, rinsed with isopropyl alcohol, dried by blowing N2 gas, and then dried in N2 gas at 300℃ in a ventilation dryer for 30 minutes.
Let it cure for a minute.

In the embodiment, an example is shown in which a positive resist is used as the photoresist, but a negative resist (for example, negative resist 'RU-I100N' (trade name) manufactured by Hitachi Chemical Co., Ltd.) may also be used.

(vi) Creation process of the second color color filter Next, the creation of the second color color filter begins.In the creation of the second color color filter, the color paste 8 is applied and until it is cured, The second color, which undergoes the same processes (i) to (v) as the first color, can be any of red, green, and blue, excluding the first color. . For example, if the first color is green, the second color may be red.

(vii) Creation process of the third color filter We begin the creation of the third color filter on the clothes, but in the creation of the third color filter, we apply Color Base I.8 until it cures. Repeat the same processes (i) to (V) as for the first color. The third color is red,
Among green and blue, this is the remaining color excluding the first and second colors. For example, if the first color is green and the second color is red, the third color is blue.

In this way, in the case of a light-receiving element with multiple light-receiving surfaces, by repeating the photophosphorography method as described above using color paste containing organic pigments of different colors,
Color filters of different colors can be attached to each light-receiving surface, and a spectral detection light-receiving element having spectral characteristics determined mainly by the type of organic pigment contained in each color filter can be formed.

(vii) Coating process of organic infrared absorption 1 sample (Fig. 6 (a)
>9) After completing the creation of the three color filters 3, 4 and 5 on the same silicon substrate 1, the organic infrared absorbing film 6 is finally formed. To form the organic infrared absorbing film 6, for example, a near infrared absorber Planetron (PA-
1001, PA-1003), thermosetting acrylic resin,
and solvent dimethyl; 1; lumamide PA-1001
:PA-1003; Acrylic resin dimethylformamide mixed in a ratio of 1,5:2:8:3 (double ratio) was applied and formed by applying near-infrared absorbing wax to a thickness of 3μ...
The infrared absorbing film 6 is formed by heating at .degree. C. for 20 minutes to harden it.

There are various types of organic near-infrared absorbers.
001, PA-1003, etc.), Cibanon Olive B Micro Powder, Cibanon Olive S manufactured by Ciba Geigy
There are Micro Powder, Micro Powder Hi-Conk, Chibanon Green F6G Micro Powder, etc. By using one or two of these near-infrared absorbers, one or two types of acrylic or methacrylic resin, phenol resin, modified phenol resin, getone resin, polyester resin, urethane type (two-type resin, etc.) can be used. Dissolved in the above resin,
By applying this, the infrared absorbing film 6 can be formed.

(ix) Resist coating and exposure process (see FIG. 6(b)) Next, the wiring made of the aluminum film 7 covered with the organic infrared absorbing film 6 is exposed to form a bonding pad part. Then, a photoresist 12 is applied and exposed to ultraviolet light through a photomask 13 so that only the photoresist 12 on the aluminum film 7 is removed. The wiring (ponding pad portion) made of the aluminum film 7 is formed on the edge of the silicon substrate 1. Therefore, for example, FIG. 5(a) can be slightly exaggerated as shown in FIG. 7. ing.

(x) Etching process of organic infrared absorbing film (Fig. 6(c)
) Next, the exposed silicon substrate 1 is developed, and the organic infrared absorbing film 6 in the aluminum film 7 portion is removed by etching. Note that the organic infrared absorbing film 6 may be left so as to sufficiently cover the three color filters 3, 4, and 5. That is, the area above the color filter and its surroundings may be left, and all other areas may be etched.

(xi) Resist stripping step (see FIG. 6(d)) Furthermore, the photoresist 12 covering the organic infrared absorbing film 6f is removed with ethyl acetate or acetone.
By the steps (ix) to (xi) of 0 or more, the organic infrared absorbing film 6 in the portion corresponding to the bonding pad portion is
is removed. That is, the electrode made of aluminum rPA7 is exposed.

(xii) Assembly process (see Figures 1 to 3) Next, a wafer test is performed to determine whether the chips are good or bad, and after gilling into individual chips, only the good chips are transferred to the chip carrier 60 (see Figure 2). ) is die-bonded to the lead frame 30 (see FIG. 3). Die bonding is performed using an adhesive layer 40 made of a conductive epoxy resin. After the die bonding is completed, it is cured at 100° C. for one hour, and then wire bonding is performed to connect the wires.

The substrate heating temperature during wire bonding is 100-150℃
It is ℃. When the wire bonding is completed, the entire light receiving element is molded with transparent resin 20.

The structure shown in Figure 2 uses silicone resin for botting. Further, in the structure shown in FIG. 3, transfer molding is performed, and a transparent resin 20 such as epoxy resin or acrylic resin is cast. The white balance sensor constructed in this manner has the spectral sensitivity characteristics shown in FIG.

In addition to the white balance sensor exemplified in the example, examples of the light receiving element include a 4A integrated circuit chip (IC chip) having a processing circuit and a light receiving element on a common chip, a brightness measurement sensor, and a two-dimensional image sensor. -(C
Possible devices include a solid-state image sensor (CD or MOS), a colorimetric sensor, etc.

(Effects of the Invention) As described above, in the light-receiving element of the present invention, the infrared absorption filter, the color separation filter, and the light-receiving element, which were provided independently in the conventional spectroscopic functional element, are integrated. Since the structure can be simplified, the structure can be made smaller, and the cost can be reduced accordingly.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a light receiving element according to an embodiment of the present invention, and FIG. 2 is a tR with the same light receiving element mounted on a chip carrier.
3 is a cross-sectional view showing the structure in which the above photodetector is mounted on a lead frame, FIG. 4 is a process diagram showing the manufacturing process of the above photodetector, and FIGS. 5 to 7 are An explanatory diagram for explaining each of the above manufacturing processes, FIG.
)(b) is an explanatory diagram showing the color paste coating process, FIG. 9 is a diagram showing the relationship between the rotation speed of the spinner and the coating film thickness, and FIG. 10 is a characteristic diagram showing the spectral characteristics of the light receiving element as above.
Figures 11(a) and 11(b) are block diagrams showing the schematic structure of a conventional light receiving element, Figures 12(a), (b), and (c) are diagrams showing the spectral transmittance characteristics of a color filter, and Figure 13 is a diagram showing the schematic configuration of a conventional light receiving element. FIG. 14 is a characteristic diagram showing the spectral detection sensitivity of a silicon semiconductor light receiving part, FIG. 14 is a diagram showing spectral transmittance characteristics of an infrared cut filter used in the light receiving element, and FIGS. 15 and 16 are cross-sectional views of different conventional examples. be. 3 to 5 are color filters, 6 is an organic infrared absorption film, 1
0 is a light receiving element.

Claims (1)

[Claims] (1) A light-receiving element comprising: a color filter layer made of a polyimide resin containing an organic pigment, provided in contact with a light-receiving surface; and an infrared ray blocking layer made of an organic material provided in contact with the color filter layer.