JP4606007B2 - Manufacturing method of optical device - Google Patents

Description

The present invention relates to a manufacturing how an optical device, particularly relates to the production how an optical device having a predetermined optical characteristic.

  For example, in a mobile terminal device typified by a mobile phone, the brightness of a backlight of a liquid crystal display screen is changed according to the surrounding brightness, thereby improving visibility and saving battery power. For this reason, the mobile terminal device incorporates a light detection device that detects ambient brightness.

  The light detection device has a structure in which a semiconductor chip on which a light receiving element is formed is mounted on a circuit board on which wirings and electrodes are formed, and the semiconductor chip is sealed with a transparent sealing resin such as an epoxy resin. (For example, refer to Patent Document 1).

  At this time, in order not to react with light such as infrared rays that cannot be seen by human eyes, an optical filter that cuts light having a wavelength longer than infrared rays and 600 nm or more is usually disposed in the light receiving portion of the semiconductor chip.

  For example, a dielectric multilayer filter is used as the optical filter. The dielectric multilayer filter has a laminated structure in which the film thicknesses of the dielectric films having different refractive indexes are sequentially changed, and is formed in the light receiving portion when the semiconductor chip is manufactured. At this time, the optical filter is configured to change its optical characteristics by changing the film thickness of the dielectric film.

  In an optical apparatus equipped with such an optical filter, a semiconductor chip on which an optical filter is formed in advance is mounted on a circuit board, and then the semiconductor chip and the circuit board are connected by wire bonding, and the semiconductor chip is made of a transparent resin. Seal.

  At this time, in order to improve the adhesiveness of the sealing resin, usually, the resin sealing surfaces of the semiconductor chip and the circuit board are plasma cleaned before the resin sealing. When the resin-sealed surfaces of the semiconductor chip and the circuit board are plasma-cleaned, the resin-sealed surfaces of the semiconductor chip and the circuit board are struck by the plasma gas, and molecules on the surface layer are blown off for cleaning. By performing the plasma cleaning, the resin sealing surface is cleaned and the adhesion with the sealing resin is improved.

JP-A-9-129780

  FIG. 7 is a sectional view of a semiconductor chip before and after the conventional plasma cleaning. FIG. 7A shows the state of the semiconductor chip before plasma cleaning, and FIG. 7B shows the state of the semiconductor chip after plasma cleaning.

  As shown in FIG. 7A, the optical filter 101 is formed on the semiconductor chip 100. The optical filter 101 is composed of a dielectric multilayer filter, and is configured by alternately stacking two types of dielectric films 111-1 to 111-n and 112-1 to 112-n having different refractive indexes. Yes. At this time, the dielectric multilayer filter can obtain desired optical characteristics by setting the film thicknesses of the dielectric films 111-1 to 111-n and 1121-1 to 112-n. For example, when light having a wavelength of 600 nm or more, that is, infrared light is cut by the optical filter 101, the dielectric films 111-1 to 111-n are made of titanium oxide TiO3, and the dielectric films 112-1 to 112-n are made of silicon oxide. When composed of SiO2, the thickness of the outermost dielectric film 112-n is normally set to about 0.3 to 0.4 [mu] m.

  On the other hand, when sufficiently cleaned by plasma cleaning, about 1 μm of the outermost layer of the optical filter 101 is deleted. Therefore, when plasma cleaning is performed on the semiconductor chip 100 shown in FIG. 7A, the dielectric films 111-n and 112-n above the optical filter 101 are removed, and the dielectric film 112-m below is displayed. Will be put out. When the dielectric films 111-n and 112-n on the upper side of the optical filter 101 are shaved, the light transmission characteristics of the filter change and the desired optical characteristics are obtained although the influence on the optical characteristics is less than that of the optical filter 101. It can no longer be obtained.

  FIG. 8 is a diagram showing optical characteristics before and after the conventional plasma cleaning. In FIG. 8, the solid line indicates the optical characteristics before plasma cleaning, and the broken line indicates the optical characteristics after plasma cleaning.

  As shown by a broken line in FIG. 8, the dielectric films 111-n and 112-n above the optical filter 101 are removed by plasma cleaning, the wavelength of the light passing therethrough becomes unstable, and the light state, for example, is included. Sensitivity differs depending on the wavelength, and there is a problem that accurate detection cannot be performed.

The present invention has been made in view of the above, and an object thereof is to provide a manufacturing how an optical device in which a predetermined optical property can be obtained.

The present invention is a method of manufacturing an optical device (1) having predetermined optical characteristics, and a filter (42) that realizes the predetermined optical characteristics on an optical element (41) mounted on a circuit board (11). ), A cleaning step of performing plasma cleaning on the circuit board (11) on which the optical element (41) on which the filter (42) is formed, and a circuit board (11) and the optical element after plasma cleaning. (41) has a wire bonding step of wire bonding after cleaning the circuit board optical element (41) is mounted (11), and a sealing step of sealing with a plug (14), said filter ( 42) has a multilayer structure, than the thickness to be set to film optical filter in order to obtain the desired optical properties, but the thickness to be removed to the thickness of the top layer in the cleaning step Thick set, the filter, after being sealed by the sealing step, wherein the set so as to realize the predetermined optical properties.

  In addition, the said reference code is a reference to the last, and a claim is not limited by this.

According to the present invention, a predetermined optical characteristic is realized by a filter and a sealing material, whereby the predetermined optical characteristic can be obtained when completed, and a desired optical characteristic can be obtained. Further, according to the present invention, after the plasma cleaning, the surface of the optical element pad and the circuit board bonding pad is cleaned by connecting the optical element and the bonding pad of the circuit board with the wire. And when the optical element is sealed with a sealing material made of a transparent resin, the surfaces of the optical element and the circuit board are cleaned. Since the substrate can be brought into close contact with the substrate, the reliability as an optical device can be improved.

  FIG. 1 shows a perspective view of one embodiment of the present invention.

  The optical device 1 according to the present embodiment mainly includes a circuit board 11, a semiconductor chip 12, wires 13, a sealing material 14, and a die attaching material 15.

  The circuit board 11 is made of, for example, a ceramic substrate, and a die pad 21, a bonding pad 22, a wiring 23, and a terminal portion 24 are formed on the surface of the circuit board 11 with a metal film. The die pad 21 is formed on the upper surface of the circuit board 11, and the semiconductor chip 12 is die attached by the die attaching material 15. After the semiconductor chip 12 is die-attached, plasma cleaning is performed, and the circuit and the circuit board 11 are connected by the wire 13.

  The wires 13 are stretched between the connection pads of the semiconductor chip 12 and the bonding pads 22 formed on the upper surface of the circuit board 11 to connect the semiconductor chip 12 and the circuit board 11. The bonding pad 22 is connected to the terminal portion 24 by the wiring 232.

  The terminal portion 24 is formed from the upper surface to the side surface of the circuit board 11, and is connected to the wiring 23 on the upper surface side of the circuit board 11. The terminal portion 24 is soldered to a land of the printed wiring board when the optical device 1 is mounted on a printed wiring board (not shown).

  Here, a method for manufacturing the semiconductor chip 12 mounted on the optical device 1 will be described.

  FIG. 2 is a diagram for explaining a method for manufacturing the semiconductor chip 12.

  First, as shown in FIG. 2A, a plurality of optical elements 41 are formed on a semiconductor substrate 31 by diffusing impurities or the like. For example, the optical element 41 constitutes a light receiving element such as a photodiode that passes a current corresponding to the amount of incident light.

  Next, as shown in FIGS. 2B to 2D, an optical filter 42 is formed on the optical element 41. The optical filter 42 is composed of, for example, a dielectric multilayer film filter, and dielectric films 43-1 to 43-n and dielectric films 44-1 to 44-n having different refractive indexes are, for example, vacuum deposited. Thus, the layers are alternately laminated at different thicknesses. The dielectric films 43-1 to 43-n are made of, for example, titanium oxide TiO3, and the dielectric films 44-1 to 44-n are made of, for example, silicon oxide SiO3. The dielectric films 43-1 to 43-n are not limited to titanium oxide TiO3, and the dielectric films 44-1 to 44-n are not limited to silicon oxide SiO3. The dielectric films 43-1 to 43-n and the dielectric films 44-1 to 44-n are materials that transmit light and have different refractive indexes, and can obtain necessary optical characteristics. It is not limited to this.

  At this time, in this embodiment, the dielectric film 44-n constituting the outermost surface layer of the optical filter 42 is formed to be thicker than the film thickness deleted by plasma cleaning. For example, the thickness is set to about 1 μm. Since the film thickness of the uppermost dielectric film is usually 0.3 to 0.4 μm, the dielectric film 44-n is set to 1.3 to 1.4 μm.

  The optical filter 42 has optical characteristics of selectively transmitting light having a desired wavelength by setting the film thickness of the dielectric films 43-1 to 43-n and the dielectric films 44-1 to 44-n. For example, an optical characteristic that cuts light having a wavelength longer than about 600 nm including infrared rays can be obtained.

  2D, the semiconductor substrate 31 is cut, and a plurality of semiconductor chips 12 on which the optical element 41 is mounted are cut out. In FIG. 2D, the formation of contacts for connecting the semiconductor chip 12 to the outside is omitted.

  FIG. 3 shows a cross-sectional configuration diagram of the semiconductor chip 12.

  At this time, the uppermost dielectric film 44-n constituting the optical filter 42 is formed to have a thickness of about 1.3 to 1.4 μm or more in the semiconductor chip 12. The overall film thickness of the optical filter 42 is about 4 μm.

  Next, a method for mounting the semiconductor chip 12 will be described.

  FIG. 4 is a diagram for explaining a mounting method of the semiconductor chip 12.

The semiconductor chip 12 is bonded onto the die pad 21 of the circuit board 11 by the die attaching material 15 as shown in FIG.
Next, the circuit board 11 on which the semiconductor chip 12 is mounted is inserted into a vacuum apparatus and plasma cleaned with argon Ar gas or the like as shown in FIG. 4B. By plasma cleaning, the outermost layer of the semiconductor chip 12, that is, the outermost dielectric film 44-n constituting the optical filter 42 is cut by about 1 μm.

  FIG. 5 is a diagram showing changes in the optical filter 42 due to plasma cleaning.

  By performing the plasma cleaning, the outermost dielectric film 44-n is removed by about 1 μm. Since the outermost dielectric film 44-n is formed to have a thickness of about 1.3 to 1.4 μm, the thickness is reduced to about 0.3 to 0.4 μm by removing 1 μm by plasma cleaning. Become. This corresponds to the film thickness set for the outermost dielectric film 44-n of the optical filter 42 in order to obtain desired optical characteristics. Thereby, the optical filter 42 can obtain a desired optical characteristic set in advance.

  FIG. 6 is a diagram showing the optical characteristics of the optical filter 42. In FIG. 6, the solid line indicates the optical characteristics before plasma cleaning, and the broken line indicates the optical characteristics after plasma cleaning.

  As shown in FIG. 6, there is no change in optical characteristics before and after plasma cleaning.

  After the plasma cleaning, the semiconductor chip 12 and the bonding pad 22 of the circuit board 11 are connected by the wire 13 as shown in FIG. At this time, since the surfaces of the pads of the semiconductor chip 12 and the bonding pads 22 of the circuit board 11 are cleaned by the plasma cleaning, the wires 13 can be reliably connected.

  After the wires 13 are connected, the semiconductor chip 12 is sealed with a sealing material 14 made of a transparent resin as shown in FIG. At this time, since the surfaces of the semiconductor chip 12 and the circuit board 11 are cleaned by plasma cleaning, they can be formed in close contact with the semiconductor chip and the circuit board 11 of the sealing material 14, and the optical device 1 is reliable. Can be improved.

  The sealing material 14 is set so as to have the same refractive index as that of the dielectric film 44-n constituting the outermost layer of the optical filter 42. Accordingly, refraction does not occur between the outermost dielectric film 44-n of the optical filter 42 and the transparent resin sealing material 14, and thus the optical characteristics of the optical filter 42 are not affected. In addition, the sealing material 14 is not limited to transparent resin, You may comprise with a glass material etc.

  In this embodiment, the thickness of the outermost dielectric film 44-n constituting the optical filter 42 is set to be thick enough to be removed by plasma cleaning. By setting the same refractive index as that of the outermost dielectric film 44-n, it is possible to obtain the same optical characteristics regardless of whether it is thick or thin.

  In the present embodiment, the case where the optical filter 42 is plasma-cleaned has been described. However, the present invention can be similarly applied to the case where the optical filter 42 is cleaned by another method.

It is a perspective view of one Example of this invention. 6 is a diagram for explaining a method of manufacturing the semiconductor chip 12. FIG. FIG. 3 is a cross-sectional configuration diagram of the semiconductor chip 12. 6 is a diagram for explaining a mounting method of a semiconductor chip 12; FIG. It is a figure which shows the change of the optical filter 42 by plasma cleaning. It is a figure which shows the optical characteristic of the optical filter. It is sectional drawing of the semiconductor chip 12 before and behind the conventional plasma cleaning. It is a figure which shows the optical characteristic before and behind the conventional plasma cleaning.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical apparatus 11 Circuit board, 12 Semiconductor chip, 13 Wire, 14 Sealing material, 15 Die attachment material 21 Die pad, 22 Bonding pad, 23 Wiring, 24 Terminal part 31 Semiconductor substrate 41 Optical element, 42 Filter, 43-1 43-n, 44-1 to 44-n dielectric film

Claims (1)

A method of manufacturing an optical device having predetermined optical characteristics,
Forming a filter that realizes the predetermined optical characteristics on an optical element mounted on a circuit board;
A cleaning step of plasma cleaning the circuit board on which the optical element on which the filter is formed is mounted;
After the plasma cleaning, a wire bonding step of wire bonding the circuit board and the optical element;
A sealing step of sealing the circuit board on which the optical element is mounted with a sealing material;
The filter has a multilayer film structure, and the thickness of the uppermost layer is set to be thicker than the thickness set in the film of the optical filter in order to obtain desired optical characteristics. ,
The method of manufacturing an optical device, wherein the filter is set to realize the predetermined optical characteristic after being sealed in the sealing step .

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