JP2005210045A - Optical semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical semiconductor device having a translucent lid and an insulating substrate that are firmly bonded with each other and superior air tightness of a hermetic space storing an optical semiconductor element, and capable of allowing the semiconductor element to receive outside light normally without causing distortion over a long period of time with high reliability. <P>SOLUTION: An optical semiconductor device 9 is provided with: an insulating substrate 1 having a recessed portion 1a for storing and mounting an optical semiconductor element 3 in an upper surface; a wiring conductor 2 led outside from the inside of the recessed portion 1a of the insulating substrate 1; the optical semiconductor element 3 that is mounted on the bottom surface of the recessed portion 1a of the insulating substrate 1 and having an electrode 4 connected with the wiring conductor 2 electrically; and a translucent lid 5 fitted onto the upper surface of the insulating substrate 1 through a bonding material 7 in such a manner as to close the recessed portion 1a. In the translucent lid 5, a groove 5a is formed at a location right above the inner surface of the recessed portion 1a of the lower surface, and the bonding material 7 enters the inside of the groove 5a. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an optical semiconductor device including an optical semiconductor element that is a light receiving element such as a photodiode, a line sensor, or an image sensor, or an optical semiconductor element having these light receiving portions.

  An insulating substrate constituting an optical semiconductor device that is a light receiving element such as a conventional photodiode (PD), line sensor, image sensor or the like, or an optical semiconductor element having these light receiving portions, has an optical semiconductor element on the upper surface. A recess is formed to accommodate the. A wiring conductor is led out from the inside to the outside of the recess of the insulating base.

  The optical semiconductor element is accommodated in the recess of the insulating base and is mounted by being bonded to the bottom surface of the recess with a resin adhesive or the like, and an electrode is provided on the outer periphery of the upper surface of the optical semiconductor element. The electrode of the optical semiconductor element and the portion of the wiring conductor exposed inside the recess are electrically connected by a bonding wire made of Au, Al or the like. Moreover, the translucent lid is attached to the upper surface of the insulating base via a bonding material so as to close the recess.

  As described above, the conventional optical semiconductor device has the translucent lid to prevent foreign substances such as dust from entering the internal space of the optical semiconductor device, and the internal space of the optical semiconductor device as a sealed space. Thus, the durability of the optical semiconductor element is improved by preventing moisture in the external atmosphere from entering the optical semiconductor device as much as possible.

  In general optical semiconductor devices, an external connection terminal is disposed on the outer periphery of the insulating base in order to make an electrical connection with an external device, and the external connection terminal is outside the recess of the wiring conductor. And is connected to the electrode pad via a wiring conductor or the like.

  The electrical signal generated by receiving and converting external light through the translucent lid by the optical semiconductor element is used for various devices and the like disposed outside the optical semiconductor device via the wiring conductor and the external connection terminal. Sent to the element.

In an optical semiconductor device having an optical semiconductor element which is a light receiving element such as a conventional PD, line sensor, image sensor or the like, or an optical semiconductor element having these light receiving portions, an insulating base and a translucent lid are bonded. As the bonding material, an epoxy resin, a phenol resin, a cresol resin, a mixture of carbon powder and silicon resin particles in which a silica filler is mixed is generally used. The bonding material is usually used in an amount necessary to bond and attach the translucent lid to the upper surface of the insulating base, and between the translucent lid and the insulating base. And is attached so as to protrude from the outside of the joint surface between the translucent lid and the insulating base to the side of the translucent lid.
JP 10-116940 A

  However, in the conventional optical semiconductor device, the bonding material that joins the insulating base and the translucent lid is interposed between the translucent lid and the insulating base and is insulated from the translucent lid. Since it only protrudes from the outside of the bonding surface with the base to the side of the translucent lid, the bonding between the insulating base and the translucent lid can be effectively strengthened. The bonding strength between the insulating substrate and the light-transmitting lid has become difficult due to the difficulty and recently the bonding area between the insulating substrate and the light-transmitting lid has become smaller with the miniaturization of the optical semiconductor device. There was a problem of tending to be insufficient.

  When the bonding of the light-transmitting lid to the insulating base is weakened, the airtightness of the sealed space for storing the optical semiconductor element deteriorates, and moisture in the external atmosphere easily enters the sealed space, so that it is reliable as an optical semiconductor device. It becomes low.

  In particular, optical semiconductor elements such as PDs, line sensors, and image sensors have recently been formed with very fine light-receiving portions in response to demands for finer images and higher detection accuracy as sensors. Therefore, even a slight deterioration in the bonding strength between the insulating base and the translucent lid causes problems such as a decrease in reliability.

  In addition, since the thickness of the light-transmitting lid tends to be reduced in order to increase the light transmittance or reduce the thickness of the optical semiconductor device, the difference in thermal expansion coefficient between the light-transmitting lid and the insulating substrate There is also a problem that the translucent lid is likely to be damaged when a stress such as thermal stress is applied to the translucent lid.

  Accordingly, the present invention has been completed in view of the above problems, and its purpose is to improve the airtightness of the sealed space in which the light-transmitting lid and the insulating base are firmly bonded, and the optical semiconductor element is accommodated. Providing a highly reliable optical semiconductor device that allows optical semiconductor elements to receive external light normally without causing distortion over a long period of time and can send normal electrical signals to external devices and elements It is to be.

  The optical semiconductor device of the present invention includes an insulating base having a recess for accommodating and mounting an optical semiconductor element on an upper surface, a wiring conductor led out from the inside of the recess of the insulating base, and the insulating base An optical semiconductor element mounted on the bottom surface of the recess and having an electrode electrically connected to the wiring conductor, and a translucency attached via a bonding material so as to close the recess on the top surface of the insulating base The translucent lid has a groove formed in a portion of the lower surface of the lower surface immediately above the inner surface of the recess, and the bonding material enters the inside of the groove. It is characterized by.

  The optical semiconductor device of the present invention is preferably characterized in that the bonding material has a Young's modulus of 1000 to 10,000 MPa.

  In the optical semiconductor device of the present invention, preferably, the bonding material has a light transmittance of 50% or less.

  According to the optical semiconductor device of the present invention, the translucent lid is insulated because the groove is formed at a position immediately above the inner surface of the recess on the lower surface and the bonding material enters the groove. The amount of the bonding material interposed between the base and the translucent lid increases, and the bonding material can form an intricate surface in which the horizontal surface and the vertical surface are combined at the groove portion. The flexible lid can be firmly bonded to the insulating substrate via a bonding material. As a result, even if the optical semiconductor device is miniaturized, the airtightness of the sealed space composed of the insulating base and the translucent lid is ensured well, and the optical semiconductor element can receive external light normally over a long period of time. Thus, a highly reliable optical semiconductor device capable of sending a normal electrical signal to an external device or element can be manufactured.

  Further, when stress such as thermal stress due to the difference in thermal expansion coefficient between the insulating base and the light-transmitting lid is applied to the light-transmitting lid, the light-transmitting lid is formed in the groove portion where the bonding material enters. Since the thermal stress can be relaxed by slightly deforming, it is possible to effectively prevent problems such as breakage of the translucent lid.

  In the optical semiconductor device of the present invention, preferably, the bonding material has a Young's modulus of 1000 to 10,000 MP, and has a moderate elasticity that can be slightly deformed but does not cause significant deformation. Therefore, the insulating base and the translucent lid can be more firmly and firmly joined to each other through the joining material by the joining material, and the insulating base and the transparent base can be slightly deformed by the slight deformation of the joining material. The thermal stress generated between the optical lid can be absorbed and alleviated by the bonding material, and it is possible to prevent damage to the translucent lid more effectively over a long period of time. High long-term reliability. An optical semiconductor device can be obtained.

  In the optical semiconductor device of the present invention, preferably, since the bonding material has a light transmittance of 50% or less, it is possible to more reliably prevent external light from entering the recess through the bonding material. Therefore, it is possible to provide an optical semiconductor device that can perform normal light reception more reliably and has excellent light reception accuracy.

  The optical semiconductor device of the present invention will be described in detail below. FIG. 1 is a cross-sectional view showing an example of an embodiment of an optical semiconductor device of the present invention. In FIG. 1, 1 is an insulating substrate, 2 is a wiring conductor, 3 is an optical semiconductor element, 4 is an electrode of the optical semiconductor element 3, 5 is a translucent lid, and 5a is formed on the lower surface of the translucent lid 5. 6 is an adhesive for bonding and mounting the optical semiconductor element 3 to the insulating substrate 1, 7 is a bonding material, and 8 is a bonding wire. An optical semiconductor device 9 is mainly composed of the insulating base 1, the wiring conductor 2, the optical semiconductor element 3, the translucent lid 5, the bonding material 7, and the bonding wire 8.

  The insulating substrate 1 of the present invention is mounted with the optical semiconductor element 3 accommodated in a recess 1a formed on the upper surface thereof and bonded to the bottom surface of the recess 1a with an adhesive 6. The optical semiconductor element 3 is provided with a light receiving portion on the upper surface, and electrodes 4 for power supply and signals are provided on the outer peripheral portion of the upper surface of the optical semiconductor element 3. The wiring conductor 2 is led out from the inside to the outside of the recess 1a, and the wiring conductor 2 exposed to the inside of the recess 1a and the electrode 4 of the optical semiconductor element 3 are electrically connected by a bonding wire 8 made of Au, Al or the like. It is connected to the. Further, a bonding material 7 made of a resin adhesive or the like is applied to the entire circumference around the recess 1a on the upper surface of the insulating base 1, and the translucent lid 5 made of glass, quartz, sapphire, transparent resin, or the like is bonded. To be attached.

  The insulating substrate 1 in the present invention is made of an alumina sintered body (alumina ceramics), aluminum nitride ceramics, silicon carbide ceramics, silicon nitride ceramics, glass ceramics or other ceramics, resin, or the like. The insulating substrate 1 may be provided with a separate frame-shaped side wall portion on the outer peripheral portion of the upper surface of the bottom plate portion, or the bottom plate portion and the side wall portion of the insulating substrate 1 may be integrally formed. .

  When the insulating substrate 1 is made of, for example, an alumina sintered body, raw powders such as alumina and glass are formed into a sheet shape together with an organic solvent, a binder and the like to produce a plurality of ceramic green sheets (hereinafter also referred to as green sheets). Next, a predetermined one of the green sheets is punched into a frame shape, and then a plurality of green sheets are laminated so that the frame-shaped green sheet is positioned in the upper layer and about 1300 to It is formed by firing at a temperature of 1600 ° C.

  On the top surface of the insulating base 1, a recess 1a for accommodating the optical semiconductor element 3 and placing it on the bottom surface is formed. The wiring conductor 2 is led out from the inside of the recess 1a. The electrode 4 of the optical semiconductor element 3 is connected to the part exposed inside the recess 1a through the bonding wire 8, so that the optical semiconductor element 3 mounted on the insulating base 1 has the electrode 4 and the bonding wire 8 And electrically connected to an external electric circuit via the wiring conductor 2.

  The wiring conductor 2 is formed of a metallized conductor such as tungsten, molybdenum, copper, or silver. For the wiring conductor 2, for example, a predetermined through hole is formed in advance on a green sheet to be the insulating base 1, and a metal paste such as tungsten, molybdenum, copper, silver is printed and applied to the surface of the green sheet and the inner surface of the through hole. It is formed by filling.

  In addition, the optical semiconductor element 3 is provided with a light receiving portion at the center of the upper surface thereof, and an electrode 4 for power supply or signal is provided on the outer peripheral portion around the light receiving portion on the upper surface. The optical semiconductor element 3 includes a light receiving element such as a PD, a line sensor, an image sensor, a CCD (Charge Coupled Device), an EPROM (Erasable Programmable ROM), or an optical semiconductor element having these light receiving portions.

  This optical semiconductor element 3 is placed on the bottom surface of the recess 1a of the insulating substrate 1 and is bonded by an adhesive 6 made of resin adhesive, brazing material, low melting point glass or the like. Is provided with an electrode 4. The electrode 4 of the optical semiconductor element 3 and the portion exposed inside the recess 1a of the wiring conductor 2 are electrically connected by a bonding wire 8 made of Au, Al or the like.

  The bonding wire 8 preferably has a length of 0.3 to 3 mm. If it is less than 0.3 mm, the bonding wire 8 is too short and it is difficult to form a sufficient loop, so that it is difficult to reliably connect the electrode 4 of the optical semiconductor element 3 and the wiring conductor 2, resulting in poor connection. It tends to occur. If it exceeds 3 mm, the bonding wire 8 tends to be too long and the loop tends to become unnecessarily high. Unnecessary inductance is generated in the bonding wire 8, and high-frequency signal transmission is likely to deteriorate and the cost is increased.

  Further, the connection between the electrode 4 of the optical semiconductor element 3 and the wiring conductor 2 is not limited to the bonding wire 8, and a strip-shaped connection line such as a so-called ribbon may be used.

  Further, the translucent lid 5 is bonded and attached to the upper surface of the insulating substrate 1 via a bonding material 7 made of a resin adhesive or the like, whereby the recess 1a in which the optical semiconductor element 3 is accommodated and mounted. Is hermetically sealed. For example, when the bonding material 7 is made of a resin adhesive, the bonding material 7 is made of an acrylic resin, an epoxy resin, a phenol resin, a cresol resin, a silicone resin, a polyether amide resin, or the like. The bonding material 7 may be mixed with a dark pigment or dye such as black, brown, dark brown, dark green, or dark blue in order to block the extraneous light from entering. Further, the bonding material 7 may be made of an inorganic material such as glass or a filler powder made of an inorganic material added to a resin adhesive.

  Further, an optical film for blocking ultraviolet rays may be formed on at least one of the upper and lower surfaces of the translucent lid 5.

  The optical semiconductor device 9 is used as a part of an optical device such as an image recognition device or a sensor or an electronic device. For example, it is mounted at a predetermined position on an electric circuit board constituting an optical device or an electronic device, receives external light and converts it into an electric signal by the optical semiconductor element 3, and the electric signal constitutes an electric device constituting the optical device or the electronic device. Supply to the circuit board.

  When mounting the optical semiconductor device 9 on the external electric circuit board, it is necessary to store a plurality of optical semiconductor devices 9 in a transfer tray or the like and transfer them to the mounting device together. It is necessary to hold the semiconductor device 9 with a holding device such as a chuck and align it with a predetermined position on the external electric circuit board. In addition, the optical semiconductor device 9 is put into and out of the tray by a manual method or a method using equipment such as an automatic transfer device.

  In the optical semiconductor device 9 of the present invention, the translucent lid 5 has a groove 5a formed in a portion immediately below the inner surface of the recess 1a on the lower surface thereof, and a bonding material 7 has entered the groove 5a. .

According to the optical semiconductor device of the present invention, the groove 5a is formed at a position immediately above the inner surface of the recess 1a on the lower surface of the translucent lid 5, and the bonding material 7 is inserted inside the groove 5a. Further, the amount of the bonding material 7 interposed between the insulating base 1 and the translucent lid 5 is increased, and the bonding material 7 forms an intricate surface in which the horizontal surface and the vertical surface are combined at the portion of the groove 5a. The translucent lid 5 can be firmly bonded to the insulating substrate 1 via the bonding material 7. As a result, even if the optical semiconductor device 9 is reduced in size, the hermeticity of the sealed space composed of the insulating base 1 and the translucent lid 5 is ensured, and external light is normally supplied to the optical semiconductor element 3 over a long period of time. It is possible to manufacture a highly reliable optical semiconductor device 9 that can receive light and transmit a normal electrical signal to an external device or element.

  Further, when stress such as thermal stress due to the difference in thermal expansion coefficient between the insulating base 1 and the translucent lid 5 acts on the translucent lid 5, the groove 5 a portion into which the bonding material 7 has entered. Since the thermal stress can be relieved when the translucent lid 5 is slightly deformed, problems such as breakage of the translucent lid 5 can be effectively prevented.

  In this case, since the bonding material 7 enters the inside of the groove 5a, the mechanical strength of the translucent lid 5 is lowered at the portion where the groove 5a is formed, so that it is easily deformed or easily broken. It is possible to effectively prevent the translucent lid 5 from being damaged at the site of the groove 5a. For example, although simply providing the groove 5a can effectively absorb and relax the stress as described above, the translucent lid 5 has problems such as breakage and breakage at the portion where the groove 5a is formed. May be easier.

  The translucent lid 5 having such a groove 5a is made of translucent glass, resin, quartz, sapphire, or the like. When the translucent lid 5 is made of glass, for example, a plate-like glass material is used as the predetermined translucent lid 5. After being cut into the above dimensions, it can be manufactured by a method such as a method of forming a groove 5a by polishing the lower surface of the insulating substrate 1 immediately above the inner surface of the recess 1a.

  The groove 5a is preferably formed so that its inner end is 0.1 to 0.5 mm inward from the portion directly above the inner surface of the recess 1a. If it is less than 0.1 mm, the bonding material 7 does not sufficiently enter the groove 5a, so that the adhesive force at the upper part of the inner surface of the recess 1a is reduced. If the thickness exceeds 0.5 mm, the bonding material 7 is likely to partially flow out to the central portion side of the lower surface of the translucent lid 5, which may hinder the passage of external light through the translucent lid 5. .

  The width of the groove 5a is preferably 0.5 mm or more. If the width of the groove 5a is less than 0.5 mm, it tends to be difficult to effectively improve the bonding property of the bonding material 7 to the translucent lid 5. The width of the groove 5a does not need to be the same over the entire lower surface of the translucent lid 5, and the width is widened at the corners of the translucent lid 5 to allow more bonding material 7 to enter. Thus, it may be more strongly bonded.

  The depth of the groove 5a is preferably 0.1 to 0.5 mm. If the depth is less than 0.1 mm, sufficient bonding material 7 cannot be obtained, so that it cannot be firmly bonded. If it exceeds 0.5 mm, the mechanical strength of the translucent lid 5 may be weakened. The translucent lid 5 has a thickness of about 0.5 to 1.2 mm.

  In addition, it is preferable to form the groove | channel 5a so that a longitudinal cross-sectional shape may be circular arc shape or elliptical arc shape. If the longitudinal cross-sectional shape of the groove 5a is an arc shape, an elliptical arc shape, or the like, the inner surface of the groove 5a is formed by a smooth curved surface, so that the bonding material 7 is formed in the groove 5a. It is easy to enter without causing defects such as voids, and the reliability of bonding and attachment between the insulating substrate 1 and the translucent lid 5 can be further improved.

  In this case, the bonding material 7 may have a Young's modulus of 1000 to 10,000 MPa. When the bonding material 7 has a Young's modulus of 1000 to 10,000 MPa and has a moderate elasticity that can be slightly deformed but does not cause a large displacement, it is insulated by the bonding material 7. The base body 1 and the translucent lid body 5 can be firmly and firmly bonded via the bonding material 7, and the insulating base body 1 and the translucent lid body 5 can be obtained by slightly deforming the bonding material 7. The optical semiconductor with high long-term reliability that can absorb and relieve the thermal stress generated between them and the bonding material 7 and can more effectively prevent the translucent lid 5 from being damaged over a long period of time. It can be the device 9.

  If the Young's modulus of the bonding material 7 is less than 1000 MPa, the bonding material 7 may be too flexible to obtain sufficient mechanical strength. If the Young's modulus exceeds 10,000 MPa, the bonding material 7 tends to be too hard, and thus the action of absorbing stress such as thermal stress tends to be reduced.

  Further, the optical semiconductor device 9 of the present invention is preferably such that the bonding material 7 has a light transmittance of 50% or less. Thereby, it is possible to more reliably prevent external light from entering the recess 1a through the bonding material 7, and to perform normal light reception more reliably, and an optical semiconductor device excellent in light reception accuracy. 9 can be provided. When the light transmittance of the bonding material 7 exceeds 50%, for example, when the thickness of the bonding material 7 is increased in order to more effectively relieve stress, external light enters the recess 1a. There is a risk of incident light.

  Further, when the bonding material 7 is made of a transparent resin adhesive, the refractive index of the bonding material 7 may be the same as that of the translucent lid 5. In this case, it is possible to effectively suppress the occurrence of light reflection or scattering at the interface between the bonding material 7 and the translucent lid 5, and extra reflected light or scattered light is generated in the optical semiconductor element 3. The incident can be prevented. Moreover, when the joining material 7 consists of a transparent resin adhesive, it is good for the volume of the bubble contained in the inside to be 30 volume% or less. If the volume exceeds 30% by volume, the bonding force of the bonding material 7 may be reduced, and light may be scattered by bubbles to cause extra scattered light to enter the optical semiconductor element 3 in some cases. In order to reduce the ratio of bubbles contained in the bonding material 7, there are a method of using the bonding material 7 in a decompression chamber or a vacuum apparatus, a method of previously degassing bubbles contained in the bonding material 7, and the like.

  In the optical semiconductor device 9 of the present invention, it is preferable that the bonding material 7 has a lower surface continuous with the lower surface of the translucent lid 5. In this case, it is possible to prevent the bonding material 7 from spreading on the lower surface of the translucent lid 5 and preventing the normal passage of external light and deteriorating the light receiving characteristics of the optical semiconductor element 3.

  Note that the above-described light is visible light having a wavelength of 380 to 770 nm.

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present invention. For example, the translucent lid 5 does not have to be uniformly translucent on the entire surface, and the portion through which external light received by the light receiving portion of the optical semiconductor element 3 passes is excellent in translucency. In addition, the outer peripheral portion whose upper surface is covered with the bonding material 7 may be made of ceramics, resin, metal, or the like that makes the bonding with the bonding material 7 strong.

It is sectional drawing which shows an example of embodiment of the optical semiconductor device of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Insulating base | substrate 1a ... Recessed part 2 ... Wiring conductor 3 ... Optical semiconductor element 4 ... Electrode 5 ... Translucent cover 5a ... Groove 7 ... Bonding material 9 ... Optical semiconductor devices

Claims (3)

An insulating base having a recess for accommodating and mounting an optical semiconductor element on the top surface, a wiring conductor led out from the inside of the recess of the insulating base, and mounted on the bottom surface of the recess of the insulating base An optical semiconductor element in which an electrode is electrically connected to the wiring conductor; and a translucent lid attached to the upper surface of the insulating base via a bonding material so as to close the recess. In the optical semiconductor device, a groove is formed in a portion of the translucent lid body immediately above the inner side surface of the concave portion, and the bonding material enters the groove. The optical semiconductor device according to claim 1, wherein the bonding material has a Young's modulus of 1000 to 10,000 MPa. The optical semiconductor device according to claim 1, wherein the bonding material has a light transmittance of 50% or less.

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