JP2015035491A - Optical semiconductor device and process of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem in which adhesive strength between a window material and a lead frame substrate formed by resin molding is not sufficient under a high humidity environment on an optical semiconductor device of a hollow structure using phosphate glass for a window material having an infrared cut filter function.SOLUTION: An oxide film is deposited on a surface of phosphate glass for improving humidity resistance reliability. On the surface on which the oxide film is deposited, a portion that is to be bonded with a lead frame substrate formed by resin molding is roughened to increase a bonding surface area. By using such phosphate glass, the optical semiconductor device of high reliability is obtained.

Description

  The present invention relates to an optical semiconductor device having a hollow structure using phosphate glass as a window material and a method for manufacturing the same.

  In recent years, devices equipped with optical sensors are increasing. Optical sensors are mounted not only on small portable devices such as mobile phones and smart phones, but also on so-called household appliances such as flat-screen televisions, refrigerators, air conditioners, and lighting fixtures from an ecological perspective. Specifically, these are proximity sensors that detect the approach of the human body, illuminance sensors that detect the brightness of the outside world and estimate the absence of a householder, and also detect the brightness of the outside world and adjust the amount of light emitted from the backlight and illumination. Such as an illuminance sensor.

  The reason for this is that flat panel TVs, indoor home appliances, and indoor / outdoor lighting devices are subject to development issues with energy savings in addition to increasing performance year by year. It became so. The electronic parts used in these portable terminals, flat-screen TVs, indoor home appliances, and indoor / outdoor lighting devices have always been required to be smaller, thinner, power-saving, and lower in cost with the pursuit of multifunctionality and portability. . As a result, many resin mold packages have been adopted. The background is the sharing of parts and materials. An optical sensor, which is one of the mounted electronic components responsible for low power consumption, is no exception, and, like other electronic components, many are small, thin, and low cost by a resin mold package.

  FIG. 12 is an example in which an optical semiconductor package in which an optical semiconductor element 3 is mounted on a resin-molded lead frame substrate 2 is disclosed (for example, see Patent Document 1). The optical semiconductor element 3 is mounted on the hollow structure and sealed with glass 19 that transmits light.

  There is an example in which a silicon photodiode is used as the optical semiconductor element 3 as an application of the illuminance sensor. The silicon photodiode has light receiving sensitivity up to the infrared region. An example in which an infrared cut filter is mounted in order to match the wavelength range of this sensitivity with human visibility (see, for example, Patent Document 2).

  In addition, an example in which a glass lid is hermetically sealed with an epoxy resin adhesive in a resin package containing a solid-state imaging device as an optical semiconductor is disclosed (for example, page 7 of Patent Document 3 and FIG. 1).

  As the infrared cut filter, phosphate glass doped with copper ions or interference filter glass having a multilayer film formed on the surface is generally used. Phosphate glass is inferior in moisture resistance to interference filter glass, but has the characteristic that the spectral characteristics do not change even if the incident light angle changes. Interference filter glass has better moisture resistance than phosphate glass, but has a feature that when the incident light angle changes, the optical path length of the interference film through which the incident light passes changes, so that the spectral characteristics change.

Japanese Patent Laying-Open No. 2005-191498 (FIG. 2) JP 2011-060788 A (page 5 and FIG. 1) JP-A-10-326845 (page 7 and FIG. 1)

  When using an optical semiconductor device having a hollow structure as a window material, phosphate resistance has been a problem. In the hollow structure, the bonding portion between the mold portion of the lead frame substrate and the window material can be taken only by the frame portion around the window material, and the bonding area is small. Further, the window material combined with the solid-state imaging device is smoothed by precisely polishing or polishing the surface in order to avoid distortion of the image to be captured. Since the adhesion area is small and the surface is smooth, the adhesive strength is insufficient and the window material tends to peel off after passing through a high temperature and humidity environment.

In order to solve the above problems, the following means were used.
In an optical semiconductor device having a hollow structure, an oxide film thin film such as silicon dioxide (SiO ₂ ) or dialuminum trioxide (Al ₂ O ₃ ) is formed on the surface of a phosphate-based glass window material bonded to the upper surface of the optical semiconductor device. Filmed. In addition, the surface of the window frame portion of the phosphate glass that adheres the window material to the lead frame substrate using an adhesive was roughened to increase the surface area where the adhesive and the window material contact each other.

  Specifically, 1) An oxide film thin film is formed on the entire surface of the phosphate glass window material. 2) A photoresist is formed on the formed oxide film. 3) The pattern of the portion to be roughened in the photo process is exposed and developed, and the portion to be roughened is exposed. 4) The phosphate glass of the window material is etched weakly with an alkaline solution to roughen the surface. 5) Apply an adhesive to the lower resin case and attach the window material. 6) In the process of heating and curing the adhesive, a protective film can be formed on the surface of the phosphate glass, and the surface roughening treatment can be performed on the part to be bonded.

  In another step of roughening the surface, 1) an oxide film is formed on the entire surface of the phosphate glass window material. 2) Cover the formed oxide film with a metal mask from which a portion to be roughened is removed. 3) The same process can be performed in the step of performing the sand blasting process on the metal mask and roughening the surface of the part from which the metal mask is removed.

  With the above-described configuration, sufficient adhesive strength is obtained between the lead frame substrate and the window material even through a high temperature and high humidity environment, and the moisture resistance reliability of the optical semiconductor device having a hollow structure is improved. .

It is sectional drawing which shows typically the structure of the optical semiconductor device of the hollow structure of this invention. It is a figure which shows typically the manufacturing method of the optical semiconductor device of this invention. It is a figure which shows typically the manufacturing method of the optical semiconductor device of this invention. It is a figure which shows typically the manufacturing method of the optical semiconductor device of this invention. It is a figure which shows an example of the spectral sensitivity of a silicon semiconductor. It is a figure which shows human visibility (bright field). It is a figure which shows an example of the spectral transmittance of phosphate glass. It is a figure which shows typically the manufacturing method of the optical semiconductor device of this invention. It is a figure which shows typically an example of the metal plate for sandblasting. It is a figure which shows typically another example of the metal plate for sandblasting. It is a figure which shows typically an example of the phosphate glass after sandblasting. It is sectional drawing which shows typically the structure of the optical semiconductor device of a conventionally well-known hollow structure.

  The optical semiconductor device of the present invention includes a phosphate glass window material having an infrared cut filter function, a resin mold lead frame substrate in which a hollow portion is formed by a resin mold, and a mounting surface located under the hollow portion. It is comprised from the mounted optical semiconductor element. FIG. 1 schematically shows a cross-sectional configuration of an optical semiconductor device having a hollow structure having a hollow portion according to the present invention.

A thin film of silicon dioxide (SiO ₂ ) or dialuminum trioxide (Al ₂ O ₃ ) is formed on the surface of a phosphate glass window material having an infrared cut filter function in order to improve moisture resistance. The resin mold lead frame substrate on which the window material and the optical semiconductor element are mounted is bonded with an adhesive. The surface of the bonding portion on the window material side is roughened to improve the bonding reliability.
Hereinafter, specific examples of the semiconductor device having a hollow structure according to the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic view showing a cross section of the semiconductor device of this example. An optical semiconductor element 3 is wire-bond mounted with a gold wire 4 on a mounting surface located under the hollow portion, which is a part of a resin-molded lead frame substrate 2 having a hollow portion. A phosphate-based glass window material 1 having an infrared cut filter function is bonded to a lead frame substrate 2 that is resin-molded in a roughened portion 5 on the surface.

  A method for manufacturing the optical semiconductor device will be described. FIG. 2 shows a process of obtaining the phosphate glass window material 1 from the phosphate glass block 6. As shown in FIGS. 2 (2) and (3), the phosphate glass block 6 is sliced into thin plates 8 slightly thicker than a desired plate thickness with a wire saw 7 and separated into individual pieces. As shown in FIGS. 2 (4) and 2 (5), both surfaces indicated by arrows of the phosphate glass processed into the thin plate 8 are polished and polished to be smooth. As shown in FIG. 2 (6), the surface of the phosphate-based glass having a smooth surface is coated with silicon dioxide or silicon dioxide for the purpose of improving weather resistance and reducing light loss due to light reflection on the filter glass surface. A thin film 9 of dialuminum trioxide is formed by sputtering or EB vapor deposition. Thus, a phosphate-based glass 10 with a surface protective film having a desired thickness is obtained.

  FIG. 3 is a schematic view showing a process of roughening a part of the surface of the phosphate glass. As shown in FIG. 3B, an etching resist 11 is applied to a phosphate glass 10 with a surface protective film having a thin film (not shown) formed on the surface. The etching resist 11 may be applied by applying a liquid resist using a roll coater or a spinner, or applying a dry film. As shown in FIG. 3 (3), the etching resist 11 is patterned to expose the surface that comes into contact with the adhesive later. As shown in FIG. 3 (4), after etching the silicon dioxide or dialuminum trioxide thin film on the glass surface, the surface of the phosphate glass is etched with an alkaline chemical to form the roughened portion 5. As shown in FIG. 3 (5), the etching resist is peeled off, and a phosphor having a single infrared cut filter function is attached to the optical semiconductor device after being cut into pieces by a cutting line 13 by means of dicing or scribe break An acid salt glass window material 1 is obtained.

  FIG. 4 shows a process for manufacturing a hollow structure optical semiconductor device. FIG. 4A shows a hollow package made of a resin-molded lead frame substrate 2. The inner wall that forms the periphery of the hollow portion is formed of resin together with the bottom surface that is the mounting surface, and the lead exposed in the hollow portion passes through the resin and is exposed outside the resin to become an external terminal.

  As shown in FIGS. 4 (2) and (3), the optical semiconductor element 3 is wire-bonded to the leads of the resin-molded lead frame substrate 2 with gold wires 4. Examples of optical semiconductor elements include CCD and CMOS imaging elements, silicon photodiode elements, and the like. Unlike human visibility, the spectral sensitivity of optical sensor elements using silicon semiconductors extends from the visible light region to the infrared region.

  FIG. 5 shows an example of the spectral sensitivity of the silicon optical semiconductor. FIG. 6 shows human bright-field visibility. FIG. 7 shows an example of the spectral transmittance of phosphate glass for correcting the spectral sensitivity of the silicon semiconductor to the visual sensitivity. From these graphs, the spectral sensitivity of an optical sensor element using a silicon semiconductor extends to the infrared region, and the spectral transmittance of phosphate glass has a shape very similar to that of human bright-field visibility. I understand that

  As shown in FIG. 4 (4), the roughened portion 5 of the phosphate glass window material 1 having the roughened portion 5 on the upper surface of the lead frame substrate 2 on which the optical semiconductor element 3 is mounted is bonded with an epoxy adhesive 15. Since bonding is performed, a thermosetting epoxy resin layer is formed between the roughened portion and the bonded portion of the lead frame substrate. Since the phosphate-based glass window material 1 does not transmit ultraviolet rays as shown in the spectral transmittance graph of FIG. 7, a thermosetting epoxy adhesive is used as the epoxy adhesive 15 instead of an ultraviolet curable epoxy adhesive. . Here, although a thermosetting epoxy adhesive is selected as the adhesive 15, an acrylic adhesive or a silicon adhesive may be used as long as a good adhesive force can be obtained. A hollow structure optical semiconductor device using a phosphate-based glass window material is obtained through the above steps.

  FIG. 8 is a schematic view showing another method for manufacturing the optical semiconductor device of the present invention. Here, an example will be described in which the sandblasting method is used instead of the etching method of the first embodiment as a means for forming the roughened portion.

  A phosphate-based glass 10 with a surface protective film having a desired thickness is prepared by the same process as in Example 1. As shown in FIG. 8B, a metal mask 16 is brought into close contact with the phosphate glass 10 with a surface protective film. The metal mask 16 has a gap 17. As shown in FIG. 8 (3), the roughened portion 5 is formed by sandblasting on the surface of the phosphate glass 10 in the space 17 of the metal mask.

  Here, in order to make the roughened portion 5 only in the frame region, a first metal mask in which a gap 17 as shown in FIG. 9 is arranged in isolation and a gap in the first metal mask as shown in FIG. The sand blasting is repeated a plurality of times by exchanging with a second metal mask having a void arrangement different from the arrangement. By processing in this manner, a roughened phosphate glass 18 in which the roughened portions 5 are arranged in a lattice shape without the gaps 17 as shown in FIG. 11 being isolated is obtained.

  As shown in FIGS. 8 (4), 8 (5), and 11, the phosphate glass window material 1 separated into pieces is obtained by separation at the cutting line 13. Thereafter, an optical semiconductor device having a hollow structure using phosphate glass as the window material is obtained in the same process as in the first embodiment. Thereafter, processing is performed in the same process as in Example 1 to obtain a hollow-structured optical semiconductor device using a phosphate glass window material.

  A hollow-structured semiconductor device using a window material with an infrared cut filter function made of phosphate glass can be provided with high reliability, so portable terminals designed for indoor and outdoor use and even in harsh environments It can contribute to the supply to various optical sensor device-equipped devices including lighting fixtures.

DESCRIPTION OF SYMBOLS 1 Phosphate glass window material 2 Lead frame board 3 Optical semiconductor element 4 Gold wire 5 Roughening part 6 Phosphate glass block 7 Wire saw 8 Glass thin plate 9 Silicon dioxide or dialuminum trioxide thin film 10 With surface protection film Phosphate glass 11 Etching resist 13 Cutting line 15 Adhesive 16 Metal plate 17 Void 18 Roughened phosphate glass 19 Glass

Claims (6)

A lead frame substrate resin-molded with a hollow portion;
A part of the lead frame substrate, and an optical semiconductor element mounted on a mounting surface located below the hollow portion;
A window material made of a glass substrate that covers the hollow portion, which is bonded to the lead frame substrate;
Have
The glass substrate is made of phosphate glass,
There is a roughened portion on the glass substrate surface of the bonded portion between the glass substrate and the resin-molded lead frame substrate,
An optical semiconductor device characterized in that a thin film of silicon dioxide or dialuminum trioxide is formed on the surface of the glass substrate other than the roughened portion.   2. The optical semiconductor device according to claim 1, wherein a layer of a thermosetting epoxy resin is provided at a bonding portion between the roughened portion and the lead frame substrate. Forming a silicon dioxide or dialuminum trioxide thin film on the surface of the phosphate glass substrate;
A step of roughening a part of the surface of the glass substrate;
Mounting an optical semiconductor element on a resin-molded lead frame substrate;
Adhering the glass substrate to the resin-molded lead frame substrate at the roughened roughened portion;
A method for manufacturing an optical semiconductor device, comprising:   The method of manufacturing an optical semiconductor device according to claim 3, wherein the roughening treatment is a step of etching with an alkaline solution after applying an etching resist.   4. The method of manufacturing an optical semiconductor device according to claim 3, wherein the roughening step is a step of sandblasting the glass substrate after masking the glass substrate with a mask.   6. The optical semiconductor device manufacturing method according to claim 5, wherein the roughening step is a step of exchanging two or more masks having different mask gap shapes and repeating the sandblasting process twice or more. Method.

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