JP2018174267A - Optical device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a high quality optical device by considerably suppressing the influence of the stress caused by sealing mold.SOLUTION: An optical device includes a first substrate 1, an active portion 3 formed on the first substrate 1 and capable of receiving or emitting infrared rays, a second substrate 2 disposed on the active portion 3 via a bonding portion 4, and a mold resin 6 that seals at least a part of the first substrate 1 and the second substrate 2. At least one of the first substrate 1 and the second substrate 2 is exposed from the mold resin 6 and translucent to infrared rays that can be the received or emitted by the active portion 3.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an optical device such as an infrared device, and more particularly to an optical device such as an optical sensor or a light emitting device having a sealing structure in a resin mold package.

  In recent years, light emitting devices with high luminous efficiency and light receiving devices with high SNR have been developed to meet various needs. Advanced sensor modules that combine these devices have also been developed. One example is a gas sensor using a NDIR (Non-dispersive infrared) system. Conventional NDIR type gas sensors have used a tungsten lamp as an infrared light source and a thermopile as a light receiving portion.

  However, in order to realize miniaturization and low power consumption, a configuration of an LED (Light Emitting Diode) as a light source and a quantum infrared sensor as a light receiving portion is becoming a standard structure of a future NDIR gas sensor. High sensitivity and high SNR of the light receiving part and high luminous efficiency of the light emitting part can be realized by using, for example, a III-V group narrow gap compound semiconductor material. Optical devices such as quantum-type infrared sensors and LEDs have attracted particular attention because they can achieve a dramatic reduction in power consumption of gas sensor modules. Another major feature of these optical devices is that they can be sealed with a resin mold. The light emitting part and the light receiving part can be easily downsized, and the performance of each (improving the light emission efficiency of the LED and increasing the SNR of the light receiving part) improves the high resolution and high performance of gas sensors that use these devices. SNR can be realized.

In addition to higher performance of the light emitting part and the light receiving part, long-term stability is required for future NDIR type gas sensors. From the viewpoint of long-term stability, there are concerns about signal drift due to stress and heat as specific problems.
An example of a package structure for reducing the stress of a device is disclosed in Patent Document 1.

JP2011-205068A

However, in the sealed mold package of the optical device as described above, the moisture due to the resin used in the mold and the stress due to heat cause fluctuations in the amount of light emitted from the optical device (quantum type infrared sensor, LED) and fluctuations in the light receiving sensitivity. May have an effect. In particular, in the case of a gas sensor that requires a resolution of the order of ppb depending on the specifications, a large error occurs in the measurement result of the gas concentration even if the optical signal level slightly changes due to the influence of disturbance.
The invention disclosed in Patent Document 1 attempts to solve such a problem, but it is necessary to extract light from the light receiving unit or from the light emitting unit from the substrate on which the light receiving unit or the light emitting unit is formed. The invention disclosed in Patent Document 1 cannot be realized.

  This invention is made | formed in view of such a problem, The place made into the objective is to obtain a high quality infrared device by restraining the influence of the stress resulting from a sealing mold significantly.

As a result of intensive investigations to solve the above problems, the present invention has found that the above problems can be solved by the following invention, and has completed the present invention.
The present invention was made to achieve such an object. To achieve the above object, an optical device according to an aspect of the present invention includes a first substrate,
An active part formed on the first substrate and capable of receiving or emitting infrared rays;
A second substrate installed on the active part via an adhesive part;
A mold resin for sealing at least a part of the first substrate and the second substrate;
With
At least one of the first substrate and the second substrate is exposed from the mold resin and has a light-transmitting property with respect to infrared light that the active part can receive or emit.

  According to one embodiment of the present invention, the influence of stress due to a sealing mold can be significantly suppressed, and a high-quality optical device can be obtained.

It is a section lineblock diagram showing a 1st embodiment of an optical device of the present invention. FIG. 2 is a cross-sectional configuration diagram of an example of a first substrate and an active part in FIG. 1. FIG. 3 is a cross-sectional configuration diagram of an example of a semiconductor stacked portion in FIG. 2. It is a section lineblock diagram showing a 2nd embodiment of an optical device of the present invention. It is a section lineblock diagram showing a 3rd embodiment of an optical device of the present invention. It is a section lineblock diagram showing a 4th embodiment of an optical device of the present invention. It is a section lineblock diagram showing a 5th embodiment of an optical device of the present invention. It is a section lineblock diagram showing a 6th embodiment of an optical device of the present invention. It is sectional drawing for demonstrating the assembly process in one Embodiment of the optical device of this invention. It is a section lineblock diagram showing a 7th embodiment of an optical device of the present invention. It is a section lineblock diagram showing an 8th embodiment of an optical device of the present invention.

  Hereinafter, the present invention will be described through embodiments. However, the following embodiments do not limit the invention according to the claims. In addition, not all the combinations of features described in the embodiments are essential for the solving means of the invention.

Embodiments of the present invention will be described below with reference to the drawings.
(First embodiment)
FIG. 1 is a cross-sectional configuration diagram for explaining a first embodiment of an optical device according to the present invention. FIG. 2 is a cross-sectional configuration diagram of an example of the first substrate and the active portion in FIG. FIG. 3 is a cross-sectional configuration diagram of an example of the semiconductor stacked portion in FIG.
As shown in FIG. 1, the optical device of the present embodiment includes a first substrate 1, an active portion 3 capable of receiving or emitting infrared rays, and a second substrate 2 installed via an adhesive portion 4. A mold resin 6 is provided which is laminated in order and seals at least a part of the first substrate 1 and the second substrate 2. The first substrate 1 and the active part 3 constitute a photoelectric conversion element (an element having a light receiving function and a light emitting function). The optical device according to the present embodiment basically requires that the first substrate 1, the active portion 3, the bonding portion 4, and the second substrate 2 are laminated in this order, and between the components. A predetermined member or a layered body may be provided as necessary.
At least one of the first substrate 1 and the second substrate 2 is transparent to the infrared rays that are exposed from the mold resin 6 and the active part 3 can receive or emit light.

Hereinafter, each component of this embodiment is demonstrated sequentially.
<First substrate>
The first substrate 1 may be either a substrate having a material containing a semiconductor or an insulating substrate. The first substrate 1 (hereinafter sometimes referred to as the semiconductor substrate 1) is selected so that high quality lamination can be performed when the semiconductor lamination portion 31 is formed. Specific examples include Si, GaAs, and sapphire. Further, when the light extraction port is the first substrate 1, it is necessary to have a high transmittance (for example, 30% or more) with respect to the wavelength. For example, when the semiconductor stacked unit 31 includes a narrow gap semiconductor material (for example, AlInSb) including In, Sb, As, Al, or the like, the first substrate 1 may be semi-insulating GaAs. In this case, it is preferable because high-quality crystal growth is possible and high transmittance is obtained with respect to light having a wavelength of several μm.

<Active part>
The active portion 3 provided on the first substrate 1 includes a semiconductor stacked portion 31, an insulating layer 32, and a wiring layer 33, as shown in FIG.
As shown in FIG. 3, the semiconductor stacked unit 31 includes a first conductive semiconductor layer 311, a first barrier layer 312, an active layer 313, a second barrier layer 314, and a second conductive semiconductor layer 315. The active portion 3 provided in the optical device of the present embodiment is not limited to the laminated structure shown here, and the laminated structure (including the material and the number of layers) is any structure that emits or receives light necessary for the gas sensor. There is no particular limitation.

  Further, the light entrance / exit may be on the side of the first substrate 1 where the semiconductor laminated portion 31 is formed or on the opposite side, but there is no influence of light shielding by the wiring layer 33, so that the light emission efficiency and light receiving sensitivity are considered. The opposite side of the first substrate 1 may be preferred. In this case, it is preferable that the first substrate 1 has a high transmittance (for example, 30% or more) with respect to the wavelength of light emitted and received. Furthermore, in order to increase the light propagation efficiency between the active part 3 of the optical device and the outside, it is more preferable that the transmittance is 40% or 50% or more.

[Semiconductor stacking part]
The semiconductor stacked unit 31 includes a first conductive semiconductor layer 311, a first barrier layer 312, an active layer 313, a second barrier layer 314, and a second conductive semiconductor layer 315, and is a member that emits or receives light.
As a specific example, the first conductive semiconductor layer 311 may have a PIN structure such as an n-type semiconductor, the active layer 313 may be a genuine semiconductor, and the second conductive semiconductor layer 315 may be a p-type semiconductor. In this case, in order to increase the light emission efficiency, in order to suppress the diffusion of electrons to the first barrier layer 312 and the second conductivity type semiconductor layer 315 for suppressing the diffusion of holes to the first conductivity type semiconductor layer 311. The second barrier layer 314 may be formed. A known material having a sensitivity or a light emitting function with respect to infrared rays can be applied to the semiconductor stacked unit 31. For example, a semiconductor layer containing In and Sb such as InSb can be used.
The active part 3 has a two-stage mesa structure as shown in FIG. This two-stage mesa structure can be formed by photolithography and etching. As an etching method, wet etching or dry etching may be used.

[Wiring layer]
The active part 3 has a large number of PIN structures, and these PIN structures may be connected to each other. For example, they may be connected in series as shown in FIG. In this case, the wiring layer 33 has a role of realizing this electrical connection. The wiring layer 33 may have a laminated structure formed of Au, Ti, Pt or the like.

[Insulation layer]
Any material can be used for the insulating layer 33 as long as it has insulating properties and can reduce physical / chemical damage. For example, SiO ₂ , SiN, and a laminate thereof can be applied.

<Second substrate>
The second substrate 2 (hereinafter sometimes referred to as the chip 2) is bonded to the active portion 3 side of the first substrate 1 by the bonding portion 4.
The resin mold 6 fixes a part of the first substrate 1, the second substrate 2, and the terminal part 5 by fixing a part of the first substrate 1, a part of the second substrate 2, and the terminal part 5 to each other. Mechanical strength is maintained while being exposed (exposed). Depending on the embodiment, a structure in which the first substrate 1 is not exposed (see FIG. 6) or the second substrate 2 is not exposed (FIG. 4) is also applied.

  In the second embodiment shown in FIG. 4, light is incident / exited only on the side of the first substrate 1 where the active portion 3 is not formed. On the other hand, in the fourth embodiment shown in FIG. 6, the incidence and emission of light are exposed areas of the second substrate 2. Here, the expression “exposed area of the substrate” is used, but the meaning is only optically exposed, and the first interface 71 and the second interface 72 that transmit light of a predetermined wavelength may be provided. Good. By providing these interface portions, it is possible to control (transmittance control) the entire wavelength of light or a part of the wavelength, which may be preferable. Another role of the first interface portion 71 and the second interface portion 72 is chemical and physical protection of the first substrate 1 and the second substrate 2.

The second substrate 2 may have at least one of the following four roles or a combination thereof.
(1) Improvement of mechanical strength of optical device / relaxation of stress By adhering the second substrate 2 to the first substrate 1 via the bonding portion 4, the stress of the surrounding resin can be relaxed. The dimensions of the second substrate 2 and the first substrate 1 and the thickness of the bonding portion 4 need to be optimized according to the respective materials of the first substrate 1 and the second substrate 2.
The Young's modulus of the second substrate 2 necessary for obtaining a sufficient stress relaxation effect is 70 MPa or more. Specific materials for the second substrate 2 include, for example, Si, GaAs, alumina, sapphire, and quartz glass.

(2) Heat radiation effect The heat radiation of the second substrate 2 can exert its effect particularly on a light emitting optical device that easily generates heat.
In order to realize this heat dissipation effect, the thermal conductivity of the second substrate 2 needs to be 5 W / (mK) or more. A specific material of the second substrate 2 in such a case is Cu or the like.

(3) Light guiding effect When the light entrance / exit is provided in the second substrate 2, the second substrate 2 guides light from the outside of the optical device to the active part 3, or light from the active part 3 to the outside of the optical device. Can guide you. In this case, the transmittance of the second substrate 2 is preferably high (for example, 30% or more) in the wavelength band to be handled.

(4) Electromagnetic shielding and magnetic shielding effect The electromagnetic shielding or electromagnetic shielding function of the second substrate 2 can be realized by using an appropriate material for the second substrate 2. For example, an electromagnetic shield can be realized by using a material having high electrical conductivity such as Cu as the material of the second substrate 2, and a magnetic shield can be realized by using a material having a high magnetic inductivity such as Fe or ferrite. Is possible.
The above-mentioned electromagnetic shielding function is particularly effective for an optical device (such as an optical sensor) having a light receiving function that is used in an environment with a lot of disturbance electromagnetic noise, or an optical device (such as an LED) having a light emitting function for suppressing disturbance electromagnetic waves. Can demonstrate.
The magnetic shield function is particularly suitable for optical devices (such as optical sensors) having a light receiving function that are used in an environment with a lot of disturbance magnetic field noise, or optical devices (such as LEDs) having a light emitting function for suppressing disturbance magnetic noise. The effect can be demonstrated.
That is, an optical device having a light receiving function can realize high SNR, and an optical device having a light emitting function can realize low disturbance noise generation.
In order to enhance this effect, the conductivity of the second substrate 2 may be 8 × 10 ³ S / m.

(5) Light Reflection Effect This function is applicable particularly when the light entrance / exit is the first substrate 1.
In the case of an optical device having a light receiving function, the light that has not been absorbed by the active portion 3 out of the light incident from the first substrate 1 is reflected by the second substrate 2 and returned to the active portion 3 again. This increases the sensitivity of the optical device.
In the case of an optical device having a light emitting function, light emitted from the active portion 3 to the second substrate 2 side is reflected from the surface of the second substrate 2 to the first substrate 1 side. Efficiency is increased.
It is preferable that the transmittance of the bonding portion 4 is high so that these reflection effects can be exhibited. The transmittance of the bonding portion 4 is, for example, 30% or more.
Specific examples of the material of the second substrate 2 include Si, GaAs, sapphire, alumina, quartz glass, ferrite, copper, aluminum, and the like, or a mixed material containing these materials.

<Adhesive part>
The bonding portion 4 is a member that joins the active portion 3 side of the first substrate 1 to the second substrate 2.
As a material for forming the bonding portion 4, a material containing silicone or polyimide may be used because mass production is easy.
Moreover, it is preferable that the adhesion part 4 is transparent (the transmittance | permeability is 30% or more) with respect to the wavelength to handle depending on a use. Among the materials constituting the bonding part 4, examples of the transparent material include a silicone resin (for example, SEMICOSIL 989 / 1K manufactured by Asahi Kasei Wacker Silicone).

<Terminal part>
The terminal part 5 has a role of an electrical connection function and a support part during assembly. Therefore, the terminal part 5 is arrange | positioned by exposing the upper end part and lower end part to the upper and lower surfaces of an optical device, respectively. The role as a support portion during assembly will be described later with reference to FIG.
Here, the electrical connection means an electrical connection between the active portion 3 and the external circuit. The electrical connection in the optical device is made by a wire 8 provided by a wire bonding process. The wire 8 is connected to the terminal portion 5 and a pad portion (not shown) provided on the first substrate 1.
The thickness of the terminal portion 5 is, for example, 0.5 mm or less.

  The terminal portion 5 is made of a metal material such as copper (Cu) or a copper alloy, iron (Fe) or an alloy containing iron, and is particularly preferably made of copper. For example, nickel (Ni) -palladium (Pd) -gold (Au) plating may be applied to the surface of the terminal portion 5 except the outer surface of the terminal portion 5 exposed from the mold resin 6. Nickel (Ni) -palladium (Pd) -gold (Au) plating is performed on a predetermined surface of the terminal portion 5 formed of copper (Cu) or the like by nickel (Ni) plating, palladium (Pd) plating, and gold (Au ) Multi-layer plating in which plating is sequentially formed. Nickel (Ni) plating contributes to improving the strength of the terminal portion 5, palladium (Pd) plating contributes to improving wire bonding properties of the wire 8, and gold (Au) plating contributes to improving solderability during mounting. In addition, the terminal portion 5 may be plated with silver (Ag) on the surface on which the wire 8 is wire-bonded, and tin (Sn) on the bottom surface (mounting surface) of the terminal portion 5 exposed from the bottom surface of the mold resin 6. Plating may be performed. Silver (Ag) plating contributes to improvement of wire bonding property of the wire 8, and tin (Sn) plating contributes to improvement of solderability at the time of mounting.

<First interface part>
The first interface portion 71 is a layered body formed on the surface opposite to the surface on which the semiconductor stacked portion 31 is formed in the first substrate 1.
Specific examples of the material constituting the first interface 71 include an insulating material transparent to light (for example, TiO ₂ , SiO ₂ , Si ₃ N ₄ , etc.), a material that reflects light (Al, Au, etc.). , Pt, etc.), or a structure that selectively reflects or transmits light by laminating two or more kinds of materials having different refractive indexes.
The first interface 71 may be formed with a thickness of 0.01 μm or more and 10 μm or less, for example. By forming the first interface 71 with a thickness in this range, the light transmittance can be appropriately controlled.

<Second interface>
The second interface portion 72 is a layered body formed on the surface of the second substrate 2 opposite to the surface facing the first substrate 1.
As a specific example of the material constituting the second interface portion 72, similarly to the first interface portion 71, an insulating material transparent to light (for example, TiO ₂ , SiO ₂ , Si ₃ N ₄ , etc.), A thin film containing a material that reflects light (Al, Au, Pt, or the like), or a structure that selectively reflects or transmits light by laminating two or more kinds of materials having different refractive indexes.
The second interface part 72 may be formed with a thickness of 0.01 μm or more and 10 μm or less, for example. By forming the second interface portion 72 with a thickness in this range, the light transmittance can be appropriately controlled.

<Third interface>
The third interface portion 73 is a layered body provided between the second substrate 2 and the bonding portion 4. Although the material which comprises the 3rd interface part 73 may be the same as that of the 1st interface part 71, in order to improve an electromagnetic shielding effect or a magnetic shielding effect, a material with good electroconductivity may be sufficient. Examples of the highly conductive material constituting the third interface portion 73 include TiO ₂ and SiO ₂ .
The third interface part 73 may be formed with a thickness of 0.01 μm or more and 10 μm or less, for example. By forming the third interface portion 73 with a thickness in this range, the electromagnetic shielding effect or the magnetic shielding effect can be appropriately controlled.

<Mold resin>
The mold resin 6 is a member that joins the first substrate 1, the second substrate 2, and the terminal portion 5.
The material constituting the mold resin 6 may be an epoxy resin used in general semiconductor devices because of the advantages of mass productivity and mechanical strength. However, in order to suppress the influence of stress due to moisture absorption by the optical sensor, Are preferred.
In particular, in the case of an optical device having an active portion 3 formed of a narrow gap semiconductor, the leakage current in the structure of the optical device fluctuates due to the stress even with a slight stress, and the electrical characteristics tend to fluctuate. An appropriate resin that is small in stress due to temperature may be selected as the mold resin 6.

The thickness of the mold resin 6 is, for example, 0.5 mm or less.
Moreover, the material which comprises the mold resin 6 may contain the filler, the impurity inevitably mixed in addition to resin materials, such as an epoxy resin. The mixing amount of the filler in this material is preferably 50 volume% or more and 99 volume% or less, more preferably 70 volume% or more and 99 volume% or less in the material constituting the mold resin 6, and 85 volume%. More preferably, it is 99 volume% or less.
Thus, according to the optical device of the first embodiment, the light that handles the first substrate 1, the second substrate 2, the bonding portion 4, the first interface portion 71, the second interface portion 72, and the third interface portion 73. On the other hand, if the dimensions and materials have a high transmittance, the light entrance / exit can be made on the first substrate 1 side and the second substrate 2 side.

(Second Embodiment)
FIG. 4 is a cross-sectional configuration diagram showing a second embodiment of the optical device.
As shown in FIG. 4, in the optical device of the second embodiment, a member such as the second interface portion 72 in the first embodiment is not provided, and the second substrate 2 is covered with the mold resin 6. Different from the first embodiment. For this reason, light entry / exit is impossible on the second substrate 2 side, and light entrance / exit is only on the first substrate 1 and first interface 71 side.
As in the second embodiment, depending on the application, this structure is preferable particularly when only one light entrance is used.

In the present embodiment, the third interface 73 may have a reflection effect in order to increase the light receiving efficiency or the light emitting efficiency. In this case, the material of the outermost surface of the third interface portion 73 (interface with the bonding portion 4) is not limited as long as it is a material having high reflectivity such as Au. The reflectance of the material constituting the third interface portion 73 is preferably 30% or more.
In order to increase the light transmittance, it is desirable that the transmittance of the bonding portion 4 is also high, and the thickness of the bonding portion 4 is preferably thin. The specific thickness of the bonding portion 4 is preferably 100 μm or less, more preferably 50 μm or less, and even more preferably 10 μm or less.

(Third embodiment)
FIG. 5 is a cross-sectional configuration diagram showing a third embodiment of the optical device.
As a modified example of the second embodiment, the third embodiment of the optical device may have a reflective effect on the second interface portion 72 shown in FIG. 5 in order to increase the light receiving efficiency or the light emitting efficiency. That is, the second interface portion 72 is a reflective film. In this case, the material of the outermost surface of the second interface portion 72 (interface with the second substrate 2) is not limited as long as it is a material having high reflectivity such as Au. The reflectance of the material constituting the second interface part 72 is preferably 30% or more.

(Fourth embodiment)
FIG. 6 is a cross-sectional configuration diagram showing a fourth embodiment of the optical device.
As shown in FIG. 6, in this embodiment, the second interface portion 72 in the first embodiment is not provided, the second substrate 2 is exposed on the upper surface, and the first substrate 1 is covered with the mold resin 6. This is different from the first embodiment. Thus, since the 1st board | substrate 1 is covered with the mold resin 6, this embodiment is effective in the use in which incident and emission of light are performed via the 2nd board | substrate 2. FIG.
In this case, the first interface portion 71 may have a structure with good reflectivity or a film containing a material with good reflectivity (for example, Au or Al).

(Fifth embodiment)
FIG. 7 is a cross-sectional configuration diagram showing a fifth embodiment of the optical device.
As shown in FIG. 7, in this embodiment, the first substrate 1 in the first embodiment is extended from one end portion of the opposing lead frame (a part of the terminal portion 5) in the opposing direction. It differs from the first embodiment in that it is formed on the extended portion 5A. This embodiment is also effective in applications where light is incident and emitted through the second substrate 2. In this case, since the mechanical strength is also increased, the first substrate 1 and the active portion 3 are less likely to be deformed even if resin moisture absorption or heat stress occurs. May be preferable depending on the application. Further, when the optical device is mounted on a circuit board (not shown), the bottom surface of the extending portion 5A and the circuit board are soldered to dissipate heat generated in the optical device to the circuit board via the solder. This is preferable because it can be performed. In this case, it is preferable that a metal pad (not shown) is formed in a portion facing the extending portion 5A of the circuit board. Solder connectivity between the extended portion 5 and the circuit board can be improved, leading to improved heat dissipation.
Although not shown, in the present embodiment, an adhesive member (for example, silver paste, resin epoxy, or the like) may be provided between the first substrate 1 and the extending portion 5A.

(Sixth embodiment)
FIG. 8 is a cross-sectional configuration diagram showing a sixth embodiment of the optical device.
As shown in FIG. 8, the sixth embodiment is different from the first embodiment in that a recess 9 is formed in the mold resin 6 in the first embodiment.
This structure is preferable when it is desired to reduce the resin content of the optical device and further reduce the stress caused by the resin. In this case, when the optical device is operated in an environment with a large humidity fluctuation, it is sometimes preferable because the fluctuation in stress due to resin moisture absorption can be suppressed.
The configuration in which the recess 9 is formed in the mold resin 6 described in the sixth embodiment is the optical device of the fourth embodiment in which the first substrate 1 described above is covered with the mold resin 6, and the first substrate 1 is the lead frame. You may apply to the resin mold 6 of the optical device of 5th Embodiment formed in a (part of terminal part 5) shape.

By controlling the depth H2 of the recess 9 formed on the upper surface of the mold resin 6, the amount of the mold resin 6 inside the optical device (photosensor) can be controlled. Thereby, the stress caused by the resin stress due to moisture absorption can be suppressed, and an optical device with good moisture resistance can be realized.
The specific dimension of H2 is preferably 10 μm or more and 500 μm or less, more preferably 10 μm or more and 100 μm or less, and further preferably 10 μm or more and 50 μm or less. This size may be optimized according to the size of each part of the optical device.

FIG. 9A is a cross-sectional view for explaining a first example of a manufacturing process in an embodiment of the optical device of the present invention. In FIG. 9A, the configuration of the sixth embodiment will be described as an example.
First, a lead frame 1000 on which nickel (Ni) -palladium (Pd) -gold (Au) plating is applied is prepared. The lead frame 1000 is a metal frame that is later cut to become the terminal portion 5 of the optical device, and may be formed of a metal material such as Cu or Ni used in a general semiconductor package process.
Next, the lead frame 1000 is placed on the surface of the adhesive sheet 1003. As the pressure-sensitive adhesive sheet 1003, one having an insulating pressure-sensitive adhesive layer on one surface is used. With this adhesive layer, the adhesive sheet 1003 and the lead frame 1000 are joined. Subsequently, the first substrate 1 having the active portion 3 formed on one surface is placed in the opening of the lead frame 1000. The first substrate 1 is placed on the pressure-sensitive adhesive sheet 1003 so that the surface opposite to the active portion 3 formation surface faces the pressure-sensitive adhesive sheet 1003. That is, the adhesive sheet 1003 has a role of maintaining the positional relationship between the lead frame 1000 and each photoelectric conversion element (the first substrate 1 and the active part 3).

Subsequently, the active portion 3 and a predetermined portion of the lead frame 1000 are connected by the wire 8. In FIG. 9A, the wire 8 is described so as to connect the first substrate 1 and the lead frame 1000. However, in actuality, the wire 8 is formed on the first substrate 1 as shown in FIG. The wiring layer 33 and the lead frame 1000 are connected.
Subsequently, the second substrate 2 is placed on the active portion 3 via the bonding portion 4. A second interface portion 72 and a third interface portion 73 are previously formed on both surfaces of the second substrate 2 in advance. The second substrate 2 is placed on the active portion 3 so that the bonding portion 4 and the third interface portion face each other.

  The adhesive sheet 1003 to which the laminated body including the lead frame 1000 and the first substrate 1, the active portion 3, and the second substrate 2 is bonded is provided with a recess (not shown) equal to the total thickness of the adhesive sheet 1003 and the lead frame 1000. It mounts on the lower metal mold | die 1001 which has. Subsequently, the upper mold 1001 is pressed against the lower mold 1001 with a desired pressure. At this time, the lead frame 1000 and a large number of laminated bodies are sandwiched between the lower mold 1001 and the upper mold 1002 while being accommodated in the recesses of the lower mold 1001. Later, the lead frame 1000 serving as the terminal portion 5 serves as a support for the upper mold 1002. For this reason, the stress applied to the second substrate 2 and the first substrate 1 from the upper mold 1002 can be reduced, and damage to the second substrate 2 and the first substrate 1 can be suppressed. Thereby, mass production of high quality optical devices can be realized. At this time, the height H determines the final dimension of the optical device.

Next, molten resin is poured into the space between the lower mold 1001 and the upper mold 1002 and cooled. Thereby, the mold resin 1006 is formed. At this time, as shown in FIG. 9A, a resin material is poured by sandwiching a sheet 1004 which is a soft material between the upper mold 1002 and the lead frame 1000, thereby forming a mold resin 6 having a recess 9. It becomes possible. Further, as shown in FIG. 9B, the recess 9 can be formed by making the shape of the upper mold 1002 into a shape in which the position corresponding to the recess 9 protrudes.
Next, the mold resin 1006 is taken out from the lower mold 1001 and the upper mold 1002, and a dicing tape (not shown) is attached to the surface after the adhesive tape 1003 is peeled off. Finally, the lead frame 1000 portion is cut from the surface opposite to the surface on which the dicing tape is applied using a dicing blade. Thereby, the separated optical device (optical device shown in FIG. 8) is obtained.

(Seventh embodiment)
FIG. 10 is a cross-sectional configuration diagram illustrating a seventh embodiment of the optical device.
As shown in FIG. 10, the seventh embodiment has a configuration in which the first interface part 71 to the third interface part 73 in the first embodiment are not provided.
In the seventh embodiment, infrared rays may be extracted from either the first substrate (semiconductor substrate) 1 side or the second substrate (chip) 2 side.

(Eighth embodiment)
FIG. 11 is a cross-sectional configuration diagram showing an eighth embodiment of an optical device.
As shown in FIG. 11, the eighth embodiment has a configuration in which the first interface portion 71 to the third interface portion 73 in the first embodiment (FIG. 1) are not provided. In the optical device of the eighth embodiment, the first substrate (semiconductor substrate) 1 is formed on a heat dissipation layer 2000 formed of a heat dissipation material (Ag paste). Further, the heat dissipation layer 2000 is exposed from the bottom surface (mounting surface of the optical device) of the resin mold 6 and is connected to the circuit board 2001 and the solder 2002 when mounting the optical device. A metal pad 2003 is preferably formed in a partial region of the circuit board 2001 connected to the heat dissipation layer 2000 via the solder 2002. This is because the solder connectivity between the heat dissipation layer 2000 and the circuit board 2001 can be improved, leading to an improvement in heat dissipation. Although not shown in FIG. 11, a layer for improving the adhesion between the first substrate 1 and the heat dissipation layer 2000 may be provided between the first substrate 1 and the heat dissipation layer 2000. The layer for improving adhesion is preferably a metal thin film formed on the back surface of the first substrate, for example. The metal thin film is formed, for example, by vapor deposition or sputtering.
In the seventh embodiment, infrared rays can be extracted from the second substrate (chip) 2 side and heat can be radiated from the first substrate (semiconductor substrate) 1 side.

<Effect of the present invention>
As described above, according to the present invention, a high-quality infrared device can be obtained by greatly suppressing the influence of stress caused by the sealing mold.

  As mentioned above, although embodiment of this invention was described, the technical scope of this invention is not limited to the technical scope as described in embodiment mentioned above. It is possible to add various changes or improvements to the above-described embodiments, and it is possible to add such changes or improvements to the technical scope of the present invention. it is obvious.

  The optical device in the present invention can be used for a gas sensor because of its features of high sensitivity, high luminous efficiency, low noise, miniaturization, and high reliability. Furthermore, the NDIR gas sensor using the optical device of the present invention can be applied to air monitoring.

1 First substrate (semiconductor substrate)
2 Second substrate (chip)
DESCRIPTION OF SYMBOLS 3 Active part 31 Semiconductor laminated part 311 1st conductivity type semiconductor layer 312 1st barrier layer 313 Active layer 314 2nd barrier layer 315 2nd conductivity type semiconductor layer 32 Insulating layer 33 Wiring layer 4 Adhesion part 5 Terminal part 6 Mold resin 71 First interface 72 Second interface 73 Third interface 8 Wire 9 Recess 1000 Lead frame 1001 Lower mold 1002 Upper mold 1003 Adhesive sheet 1004 Sheet 2000 Heat dissipation layer 2001 Circuit board 2002 Solder 2003 Metal pad

Claims (14)

A first substrate;
An active part formed on the first substrate and capable of receiving or emitting infrared rays;
A second substrate installed on the active part via an adhesive part;
A mold resin for sealing at least a part of the first substrate and the second substrate;
With
At least one of the first substrate and the second substrate is an optical device that is exposed from the mold resin and has translucency with respect to infrared rays that the active part can receive or emit.   The optical device according to claim 1, wherein the first substrate and the second substrate have a transmittance of 30% or more for the infrared light.   The optical device according to claim 1, wherein at least a part of the first substrate is exposed from the mold resin.   The optical device according to claim 1, wherein at least a part of the second substrate is exposed from the mold resin.   The optical device according to claim 1, wherein a surface of the second substrate opposite to the interface with the bonding portion is covered with the mold resin.   6. The optical device according to claim 1, wherein both the first substrate and the second substrate are exposed from the mold resin. Comprising a plurality of lead terminals arranged around the active part in plan view;
The optical device according to claim 1, wherein the optical device is exposed from the mold resin at the lead terminal, the bottom surface of the mold resin, and the top surface of the mold resin.   The optical device according to claim 1, wherein the second substrate is exposed from the mold resin.   9. The optical device according to claim 1, wherein, on the upper surface of the mold resin, the second substrate peripheral portion of the mold resin has a dent recessed from the surface of the second substrate. The second substrate has a reflective film having a reflectivity of 30% or more with respect to infrared rays that the active part can receive or emit light at an interface with the adhesive part,
The optical device according to any one of claims 1 to 9, wherein infrared light can be incident or emitted through the first substrate. The second substrate has a reflective film having a reflectance of 30% or more with respect to infrared light that the active part can receive or emit on the surface opposite to the interface with the adhesive part,
The optical device according to any one of claims 1 to 10, wherein infrared light can be incident or emitted through the first substrate.   The optical device according to claim 1, wherein the second substrate has a thermal conductivity of 5 W / (mK) or more.   The optical device according to any one of claims 1 to 12, wherein a Young's modulus of the second substrate is 70 MPa or more. The optical device according to any one of claims 1 to 13, wherein the conductivity of the second substrate is 8 × 10 ³ S / m or more.

Images