JPS6367528A - Photodetector molded with opalescent resin - Google Patents

Abstract

PURPOSE:To improve the heat resistance of a color filter layer by providing a color filter layer made of polyimide resin contg. an org. pigment so as to be brought into contact with a photodetecting surface and molding the entire part with opalescent resin. CONSTITUTION:The photodetector 10 is molded in the opalescent resin 20. The color filter made of polyimide resin is mounted on the photodetecting surface of the photodetector 10. The photodetector 10 is die-bonded by a conductive adhesive agent layer 40 onto a tab part 31 positioned in the central part of a lead frame body 30. One end of a bonding wire 50 is connected to each inner lead end 32 of the lead frame body 30. The other end of the wire 50 is connected to the bonding pad of the photodetector 10. The outer lead 33 of the lead frame body 30 is electrically connected to an inner lead end 32 to serve as an external drawing out lead wire of the photodetector 10.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a light-receiving element molded with a milky-white resin, which is formed by sealing a light-receiving element with a color filter directly attached to the light-receiving surface with a milky-white resin. .

(Prior Art) Conventionally, resin molding has been widely used as a packaging method for semiconductor elements. Packaging using a resin molding method has the advantage of being inexpensive, having good moisture resistance, and being highly reliable.

The working temperature conditions in the resin molding method are 150 to 180℃.
℃, and if the object to be sealed is only a silicon semiconductor chip, almost no thermal problem will occur. Furthermore, if the silicon semiconductor chip is a light-receiving element, molding resin is used to capture light. A transparent material was chosen.

On the other hand, as a light-receiving element having a color filter, an organic film color filter made by dyeing a dyed substrate such as gelatin, casein, or polyvinyl alcohol with a dye and directly attached to the chip surface of a semiconductor light-receiving element has been proposed. FIG. 17 is a diagram showing a schematic configuration of this conventional example. As shown in the figure, an on-chip type filter FL is attached to the chip surface of the light receiving element 10. The filter PL includes three types of color filters that transmit red light, green light, and blue light, respectively, and each color filter is arranged on the surface of the three light receiving parts of the light receiving element 10 to adjust the color distribution of the light to be measured. can be measured. An infrared cut filter IR for cutting light components in the infrared region is arranged in front of the light receiving element 10, and in many cases, the color distribution of the incident light to be measured is uneven. Therefore, a diffuser plate DF is placed in front of the infrared cut filter JR to diffuse the measured light.
The color distribution of the measured light on the surface of the light receiving element is made uniform. A light receiving element having such an on-chip type organic film color filter has the advantage that it has a simpler structure and can be constructed at a lower cost than a structure in which color filters are aligned and bonded one by one onto a chip. .

(Problems to be Solved by the Invention) If a light-receiving element having an on-chip type organic film color filter as described above could be molded with a milky white resin, it would be inexpensive, highly reliable, and would not require a diffuser plate. It is thought that it is possible to provide an element that does not however,
Conventional organic film color filters have poor heat resistance, making it impossible to use a resin molding method that requires the above working temperature conditions. In other words, on-chip type organic membrane color filters are formed by dyeing dyeing substrates such as gelatin, casein, or polyvinyl alcohol with dyes, but these materials generally have poor heat resistance (140 ℃ (the limit is near), the quality deteriorates at a temperature lower than the above-mentioned working temperature conditions, and the characteristics as a color filter change.Furthermore, in the conventional example of molding the light receiving element with a transparent resin,
Since transparent resin does not have the effect of diffusing light, if the color distribution of the measured light is uneven as described above, it is necessary to separately install a diffusing plate, leading to an increase in cost.

The present invention has been made in view of these points, and its purpose is to create a light-receiving element having an on-chip type color filter by using a highly heat-resistant color filter made of polyimide resin. To provide an inexpensive and highly reliable light receiving element molded with a milky white resin.

(Means for Solving the Problems) In order to solve the above-mentioned problems, in the light-receiving element molded with a milky white resin according to the present invention, a color filter layer made of polyimide resin containing an organic pigment is provided. It is provided so as to be in contact with the light-receiving surface, and is entirely molded with a milky white resin.

(Function) In the light-receiving element molded with a milky white resin according to the present invention, a color filter layer made of polyimide resin containing an organic pigment is used as the color filter layer provided in contact with the light-receiving surface. Compared to dyeing properties such as gelatin, casein, and polyvinyl alcohol used in conventional organic film color filters, polyimide resin has higher heat resistance. It also has high heat resistance, and therefore has improved heat resistance as a color filter layer, and can sufficiently withstand temperature conditions of about 300°C. Therefore, it can easily withstand temperatures of 150 to 180° C., which are the working temperature conditions for normal resin molds, and a milky white resin mold can be produced. Furthermore, since the milky white resin has the effect of diffusing light, installation of a diffusion plate becomes unnecessary.

(Example) Preferred embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view of a light-receiving element molded with a milky white resin according to an embodiment of the present invention, FIG. 2 is a sectional view of a mold used for manufacturing the same, and FIG. 3 is a lead used for manufacturing the same. It is a figure which shows an example of a frame.

As shown in FIG. 1, the light receiving element 10 has a milky white resin 2
It is molded into 0. A color filter made of polyimide resin is attached to the light receiving surface of the light receiving element 10, as will be described later. The light receiving element 10 is bonded onto a tab portion 31 located at the center of the lead frame body 30 using a conductive adhesive layer 40 . Inner lead end 32 of lead frame main body 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 lead frame main body 30 is electrically connected to the inner lead end 32 and serves as an external lead wire of the light receiving element 10.

For molding the light receiving element 10 into the milky white resin 20, for example, a mold 60 as shown in FIG. 2 is used. The mold 60 has a cavity 63 between an upper mold 61 and a lower mold 62. In this cavity 63, a light receiving element 1 is placed.
0 together with the lead frame main body 30 and injecting milky white resin, a mold package having an external shape corresponding to the internal shape of the cavity 63 is formed. It goes without saying that the light-receiving element 10 is die-bonded and wire-bonded to the lead frame body 30 before being molded, and the upper mold 61 is separated from the lower mold 62 after the milky white resin has hardened. after that,
The molded product is taken out from the mold 60 by moving the ejector pin 64 upward.

After the above molded product is formed, the frame frame 34 and tie bars 35 in the lead frame main body 30 shown in FIG. 3 are no longer needed and are therefore removed. Further, the dam burr 21 where the injected milky white resin 20 protrudes from the cavity 63 between the outer leads 33 and the flash burr 22 which wraps around the upper and lower surfaces of the outer lead 33 are unnecessary and are therefore removed. Furthermore, outer lead 33
the first I12I so as to form a DIR package.
It is curved as shown in .

FIG. 4 is a diagram illustrating a cross-sectional structure of the light receiving element 10 molded with a milky white resin. This light receiving element is used as a white balance sensor for color video cameras, and emits R (red light).

The light intensity of G (green light) and B (blue light) 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 is provided on the surface of each light receiving section 2.
, a green filter 4 and a blue filter 5 are provided so as to cover the light receiving surface and its vicinity. A top coat film 6 is applied to the surface of each filter 3 to 5,
The surface is flattened. At the edge of the silicon substrate l,
A wiring portion made of aluminum film 7 is exposed.

FIG. 5 is a diagram showing the manufacturing process for creating a color filter. Moreover, FIGS. 6 to 8 are explanatory diagrams of each process. Hereinafter, the manufacturing process of a light receiving element having a color filter will be explained with reference to these figures. still,
Each process in FIGS. 6 and 7 is performed on a single wafer, but the drawings show only one chip.

Further, in FIGS. 6 and 7, wiring is omitted.

(i) Color paste application, semi-curing process (6th
(See Figure (a)) First, heat-resistant color paste 8 for color filters is applied to the surface of silicon substrate 1 on which light-receiving elements are formed. At this stage, the silicon substrate 1 is being processed not in units of individual chips but in units of wafers. The heat-resistant color paste 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 element is formed is heated with N at 200°C.
After drying in two gases for 10 minutes, a small amount of the first color color paste 8 was dropped onto the silicon substrate 1, and then dried at 500 r using a spinner (for example, IH-DS type manufactured by Mikasa).
A coating film is formed under the conditions of 5 seconds at a rotational speed of pm, and further 30 seconds at a rotational speed of 3000rpI11.

This coated film is semi-cured for 30 minutes in air at 140° C. using a ventilation dryer. 1st color color paste 8
Any color among red, green, and blue may be used as the color.

FIG. 9 is a diagram showing how the color paste 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 Figure 9(a)).The silicon substrate 1 is placed in a spinner. 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. 9(b)).
), and FIG. 10 is a diagram showing the relationship between the rotation speed of the spinner and the coating film thickness. As is clear from this figure, the thickness of the coating M can be reduced by increasing the rotation speed of the spinner. In addition, in Fig. 10, each line indicates the characteristics when applying color paste (red O mark, green Δ
mark, blue mark).

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

-1 paste (I 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
011, for organic pigment, as a red pigment, color index No. 7390
Quinacridone pigments such as No. 5 Pigment Red 209 and No. 46500 Pigment Viole L19; or as a green pigment, Color Index No. 7416
Phthalocyanine green pigments such as No. 0 Pigment Green 36, Pigment No. 74260, Pigment Green 7; or as a blue pigment, Color Index No. No. 017416
0 Pigment Blue15-3, 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.

(Heat Color 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 a color filter, which is made by mixing the same red pigment, green pigment, or blue pigment as used in 1) at a ratio of 10 to 3008.

General formula, R8: 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 a color filter, which is made by mixing 10 to 300 g of the same red pigment, green pigment, or blue pigment as used in I).

The color paste applied to the silicon substrate 1 is as follows:
Any color paste from (I) to (III) above may be used.Before applying the color paste, in order to flatten the unevenness of the light receiving surface, a transparent polyimide layer is applied to the light receiving surface. You may also apply it.

(ii) Resist coating and pre-beta process (Fig. 6(b)
)#photo) 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 the photoresist 9 is coated.
A positive resist, ``Microposit Photoresist 1400-31'' (trade name) manufactured by Sibley Co., Ltd., was used.

The application of the photoresist 9 is also carried out using a spinner, which is applied at a rotation speed of 500 rpm for 5 seconds and then at a rotation speed of 200 rpm.
A coating film is formed at a rotation speed of Qrpm 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. 6(e)g) Next, after adjusting the exposure position on the silicon substrate 1 using a mask aligner, exposure of 70 mJ was performed, only on and near the light receiving surface. Exposure to ultraviolet light is performed through a photomask 11 so that the photoresist remains.

(iv) Resist development and etching process (Fig. 6(d)
)) Next, the photoresist 9 on the silicon substrate 1 that has been exposed is
Develop. As a developer, Microposit "MF-312 Developer" (trade name) manufactured by Sibley is used.
and water at a 1:1 ratio, and the liquid temperature was 22°C.
After that, the excess color paste layer is etched. After the etching, the silicon substrate 1 is rinsed with water and dried by blowing N2 gas.

(Ma) Resist peeling, rinsing, and curing process (Figure 6 (
(See e)) Next, in order to peel off the photoresist 9 remaining on the color paste layer, the silicon substrate 1 is immersed and stirred in ethyl acetate, taken out after 5 minutes, and rinsed with isopropyl alcohol. Dry by blowing N2 gas, then dry in N2 gas at 300℃ in a ventilation dryer for 30 minutes.
Let it cure for a minute.

In the example, an example was shown in which a positive resist was used as the photoresist 9, but a negative resist (for example, a negative resist "RLJ-I100N" manufactured by Hitachi Chemical Co., Ltd.) was used.
(product name)) may be used.

(vi) In the process of creating the second color filter,
Now we will start creating the second color filter.In creating the second color filter, we repeat the same processes (i) to (v) as for the first color until we apply color paste 8 and cure it. , the second color may 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 The creation of the third color filter begins on the garment, but also in the creation of the third color color filter, color paste 8 is applied and the color paste 8 is applied until it is cured. Repeat the same processes (i) to (v) as for the first color, and the third color is the remaining one of red, green, and blue, excluding the first and second colors.
Becomes a color. 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 photolithography 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 step of the tube coat film (see FIG. 7(a)) After the three color filters 3, 4, and 5 have been formed on the same silicon substrate 1, a top coat M6 is finally formed. To form the top coat M6, for example, JSR polyimide “JIA-1-2” manufactured by Japan Synthetic Rubber Co., Ltd.
(trade name) to a thickness of 0.5 μm (') and baked. The baking conditions are 1 hour in an atmosphere of 150°C. In addition to this, the top coat film 6 may be formed using, for example, a surface flattening agent "JSS-17" (trade name) manufactured by Japan Synthetic Rubber Co., Ltd.

The purpose of applying this top coat film 6 is the above-mentioned (i) to (
On the surface of the colored polyimide color filter formed in step vii), so-called orange peel-like roughness occurs, which often leads to a decrease in light transmittance due to diffuse reflection on the surface. This is to flatten the surface to prevent diffuse reflection on the surface and improve light transmittance. As shown in FIGS. 12 to 14,
The light transmittance is increased by the top coating.
Improved by a few percent. Figures 12 to 14 are diagrams showing the spectral transmittance characteristics of blue, red, and green color filters created by the above-mentioned process, respectively, and the characteristics shown by solid lines are the same as those shown by broken lines when there is no top coating. The properties shown are those with a top coating.

In addition, Figure 11 shows the change in spectral transmittance characteristics when H3 is changed for a blue color filter without top coating. If so, ■
If is 3000 rpm, ■ is 4000 rpm
The spectral transmittance characteristics in the case of pm are shown respectively. Furthermore, Fig. 15 shows the blue color provided on the silicon chip.
It shows the characteristics of green and red color filters.

In order to obtain this characteristic, an infrared cut filter IR having the characteristics shown in FIG. 16 is externally attached.

ix) Process of applying resist (see FIG. 7(b)) Next, in order to expose the wiring made of the aluminum film 7 covered with the top coat film 6 and form a bonding pad part, a photoresist is applied. 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, and therefore, for example, FIG. 6 (,) can be slightly exaggerated as shown in FIG. 8. ing.

(x) Etching process of top coat film (Fig. 7(e)
(See) Next, the exposed silicon substrate 1 is developed and etched to remove the top coat film 6 on the aluminum JI 17 portion.
remove.

(xi) Resist stripping process (see FIG. 7 (cl)) Furthermore, the photoresist 1 covering the top coat film 6 is
The top coat film 6 in the portion corresponding to the bonding pad portion is removed by the steps (ix) to (xi) of zero or more, in which the top coat film 6 is peeled off using ethyl acetate or acetone.

In other words, the electrode made of aluminum film 7 is exposed.

The light-receiving element with the color filter manufactured by the above process has heat resistance that can withstand heat up to 300 degrees Celsius due to the use of polyimide resin and organic pigments as materials for the color filter. There is no need to worry about thermal conditions during wire bonding, wire bonding, or resin molding processes.

(xi) Assembly process (see Figures 1 to 3) Next,
After performing a wafer test, determining whether the chips are good or bad, and gluing each chip, only the non-defective chips are bonded to the lead frame body 30. The gouey bonding is performed using adhesive N40 made of conductive epoxy resin. After the gouey 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 ℃. After the wire bonding is completed, resin molding is performed using a transparent acrylic resin, epoxy resin, a mixture of silicone resin and titanium oxide, a mixture of barium sulfate, or the like using a transfer molding method. The molding temperature at this time is about 180°C at the highest,
Both organic pigments and polyimide resins can be sufficiently heat resistant.

Incidentally, before resin molding, a transparent polyimide layer or epoxy resin layer may be formed on the color filter by coating, whereby mold 4! l It is possible to prevent the internal stress of the fat part and the heat during molding from being directly transmitted to the color filter.

Furthermore, when resin molding is performed in the 5th assembly step, the molding resin can improve surface roughness of the color filter, so it is not necessarily necessary to provide a top coat film.

By the way, there are various methods for resin molding, including the transfer molding method used in the examples, as exemplified below, but it doesn't matter which method you choose.The work atmosphere is in the air. .

■Transfer molding This method is the most widely used method, in which powdered resin is melted and injected into a mold under the pressure of a plunger to seal a large number of molds at the same time. As the mold material, Fe-N
A combination of an i-alloy lead frame or a Cu lead frame and an epoxy resin or silicone resin is common.The working temperature is usually 150 to 170°C, and the polyimide color filter of the present invention can sufficiently withstand heat. It's temperature.

■Injection molding This method involves molding with an injection molding machine using P, P, S, @ resin or polyester resin.
The working temperature used for the -Ni lead frame is 150° C. or lower, which is a temperature at which the polyimide color filter of the present invention can be sufficiently heat resistant.

■Casting/botting This method is a method in which liquid resin is poured into a mold, and the working temperature used when molding diode leads or hybrid boards with silicone resin or epoxy resin is room temperature. The curing is performed at 180° C. or lower, which is a temperature at which the polyimide color filter of the present invention can sufficiently withstand heat.

In addition to the white balance sensor exemplified in the example, examples of the light receiving element molded with milky white resin include a single circuit chip (IC chip) having a processing circuit and a light receiving element on a common chip, and a sensor for measuring brightness. Possible options include color-enriching sensors, etc.

(Effects of the Invention) As described above, in the light-receiving element molded with a milky white resin according to the present invention, the color filter layer made of polyimide resin containing an organic pigment is used as the color filter layer provided in contact with the light-receiving surface. The heat resistance of the color filter layer is improved, and therefore it is possible to mold an on-chip spectroscopic function element with a milky white resin in which the color filter is directly attached to the light-receiving surface of the light-receiving element. This has the effect of reducing production costs, and since the entire chip can be covered with a milky white resin mold, it is resistant to moisture and has high reliability.Moreover, the milky white resin has the effect of diffusing light. This has the effect of eliminating the need for installing a diffusion plate.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a light-receiving element molded with a milky white resin according to an embodiment of the present invention, FIG. 2 is a cross-sectional view of a mold used for manufacturing the same, and FIG. 3 is a cross-sectional view of a lead frame used for manufacturing the same. A diagram showing an example, FIG. 4 is a cross-sectional view of a light receiving element having a color filter used in the above, FIG. 5 is a process diagram showing the manufacturing process of the same, and FIGS. 9(a) and 9(b) are explanatory diagrams showing the color paste coating process; FIG. 10 is a diagram showing the relationship between the rotation speed of the spinner and the coating film thickness;
Figures 15 to 15 are diagrams showing the spectral transmittance characteristics of the color filter, Figure 16 is a diagram showing the spectral transmittance characteristics of an infrared cut filter externally attached to the light receiving element, and Figure 17 is a schematic diagram of the conventional example. It is a diagram. 10 is a light receiving element, and 20 is a milky white resin.

Claims (1)

[Claims] (1) A light-receiving element molded with a milky-white resin, characterized in that a color filter layer made of polyimide resin containing an organic pigment is provided in contact with the light-receiving surface, and the entire body is molded with a milky-white resin.