JP4458997B2 - Optical semiconductor device - Google Patents

Description

  The present invention relates to an optical semiconductor device including a light receiving element or a semiconductor element having a light receiving portion.

  2. Description of the Related Art Conventionally, an optical semiconductor device including optical semiconductor elements such as photodiodes, line sensors, and image sensors has a configuration in which an optical semiconductor element is accommodated and mounted inside a concave portion of an insulating base having a concave portion on an upper surface. The optical semiconductor element is bonded to the recess of the insulating base via a bonding material. Then, for example, a flat lid is joined to the upper surface of the insulating base via an adhesive.

For the bonding material for bonding the optical semiconductor element and the insulating base, for example, a brazing material made of a metal such as silver or aluminum, an epoxy resin mixed with a filler of an inorganic material such as silica, or a polyimide resin is used. ing. As a conventional method for applying a bonding material, for example, when the optical semiconductor element is rectangular like a line sensor, the bonding material is linearly applied to a portion corresponding to the optical semiconductor element in the recess of the insulating base. Alternatively, a method has been used in which a bonding material is applied in a dot-like manner to a portion corresponding to the optical semiconductor element in the concave portion of the insulating substrate. Then, the optical semiconductor element is positioned and mounted on the bonding material, and the bonding material is spread over the entire bonding surface between the optical semiconductor element and the recess of the insulating base so as to press the optical semiconductor element against the bonding material. Thus, the optical semiconductor element and the insulating base are bonded. Note that a part of the bonding material protruded from a region corresponding to the optical semiconductor element in the concave portion of the insulating base, and the surface of the protruding portion formed a meniscus having an inclined surface shape or a gently curved surface shape.
JP 1999-54444 A

  However, in the conventional optical semiconductor device, particularly when the optical semiconductor element is rectangular like a line sensor, the bonding material for bonding the optical semiconductor element and the insulating base is peeled off from the short side of the optical semiconductor element. There is a risk that the optical semiconductor element may be misaligned. As described above, the cause of the phenomenon in which the bonding material is peeled off from the short side of the optical semiconductor element is examined. The following two causes are considered. The first cause is that stress such as thermal stress due to the difference in thermal expansion coefficient between the optical semiconductor element and the insulating base is concentrated on the short side of the optical semiconductor element. The second cause is that the surface of the bonding material that protrudes from the region corresponding to the optical semiconductor element of the insulating base forms a meniscus having an inclined surface or a gently curved surface. However, it has been insufficient to absorb or disperse the stress concentrated on the short side of the optical semiconductor element.

  And, in order to improve the bonding strength on the short side of the optical semiconductor element, a method of thickly applying the bonding material on the short side of the optical semiconductor element in the region corresponding to the optical semiconductor element of the insulating base may be considered. In this method, the optical semiconductor element may be mounted with an inclination. In particular, in recent years, optical semiconductor elements such as photodiodes, line sensors, and image sensors have been formed very finely in response to demands for finer images and higher accuracy of light detection. It has come to have a big influence.

  Therefore, the present invention has been completed in view of the above problems, and its purpose is to improve the bonding strength on the short side of the optical semiconductor element when a rectangular optical semiconductor element is mounted. It is an object of the present invention to provide a highly reliable optical semiconductor device that meets the recent demands for finer images and higher photodetection accuracy.

An optical semiconductor device according to the present invention includes an insulating base having a recess for accommodating and mounting an optical semiconductor element on an upper surface thereof, and a mounting portion for the optical semiconductor element formed on a bottom surface of the recess, and the insulating base A wiring conductor led out from the mounting portion to a side surface or a lower surface; and a rectangular optical semiconductor element that is mounted and mounted to the mounting portion with a bonding material and an electrode is electrically connected to the wiring conductor; A protruding portion provided on the outer side of the mounting portion on the short side of the optical semiconductor element in parallel with the side surface on the short side of the optical semiconductor element, the upper surface being higher than the upper surface of the optical semiconductor element ; A translucent lid attached to the upper surface of the insulating base so as to close the concave portion, and a longitudinal section between the side surface on the short side of the optical semiconductor element and the protruding portion. surface shape in the plane, the height of the intermediate position before Characterized in that reservoir of the bonding material which is a concave high acquisition than the lower surface of the optical semiconductor element is formed.

  In the optical semiconductor device of the present invention, preferably, in the optical semiconductor element, an electrode is electrically connected to the wiring conductor outside the protrusion on the upper surface of the insulating substrate via a bonding wire, and the protrusion Further, a groove for receiving the bonding wire is formed on the upper surface thereof.

  The optical semiconductor device of the present invention is preferably characterized in that the bonding material covers a side surface on the long side of the optical semiconductor element.

According to the optical semiconductor device of the present invention, the insulating base in which the concave portion for accommodating and mounting the optical semiconductor element is formed on the upper surface and the mounting portion for the optical semiconductor element is formed on the bottom surface of the concave portion, and the mounting of the insulating base A wiring conductor led out from the side to the side surface or the bottom surface, a rectangular optical semiconductor element in which the mounting portion is bonded and mounted via a bonding material and the electrode is electrically connected to the wiring conductor, and the mounting portion A protrusion provided on the outer side of the short side of the optical semiconductor element in parallel with the side surface of the short side of the optical semiconductor element and having a top surface higher than the upper surface of the optical semiconductor element, and a recess on the upper surface of the insulating substrate. A light-transmitting lid attached so as to close the surface, and the surface shape in the longitudinal section between the side surface on the short side of the optical semiconductor element and the protruding portion has a height at the intermediate position. contact which is a concave high acquisition than the lower surface of the optical semiconductor element Since the material pool is formed, a large pool of bonding material is formed between the projecting portion and the outside of the side surface on the short side of the optical semiconductor element on which the thermal stress acts greatly to insulate the optical semiconductor element. Bonding strength with the substrate can be improved.

Moreover, since the surface shape in the longitudinal section of the pool of the bonding material is a concave shape having a waveform in which the height of the intermediate position is higher than the lower surface of the optical semiconductor element, the stress is absorbed and dispersed along the concave surface. be able to. As a result, it is possible to suppress the peeling of the short side of the rectangular optical semiconductor element, to provide a highly junction reliable optical semiconductor device.

  According to the optical semiconductor device of the present invention, preferably, in the optical semiconductor element, the electrode is electrically connected to the wiring conductor outside the protruding portion on the upper surface of the insulating substrate via the bonding wire, and the protruding portion is Since the groove into which the bonding wire enters is formed on the upper surface, the bonding wire can be fixed in the groove to prevent deformation such as bending, and electrical short-circuiting due to contact between adjacent bonding wires Thus, it is possible to provide an optical semiconductor device that can effectively prevent such problems and has high electrical connection reliability.

  According to the optical semiconductor device of the present invention, preferably, since the bonding material covers the side surface of the long side of the optical semiconductor element, the optical semiconductor element is firmly attached to the insulating substrate over the entire circumference. Thus, an optical semiconductor device with higher reliability can be provided.

  The optical semiconductor device of the present invention will be described below in detail with reference to the drawings. FIG. 1A is a cross-sectional view showing an example of an embodiment of the optical semiconductor device of the present invention, and FIG. 1B is a diagram of a portion indicated by X in the optical semiconductor device of FIG. It is an expanded sectional view. An optical semiconductor device 110 of the present invention is formed on an optical semiconductor element 101, an insulating base 102 on which the optical semiconductor element 101 is mounted, a bonding material 103 that joins the optical semiconductor element 101 and the insulating base 102, and the insulating base 102. And a wiring conductor 104 electrically connected to the optical semiconductor element 101, a lid 105 attached to the insulating base 102, and a protrusion 109.

  The optical semiconductor element 101 has a rectangular shape in plan view. The optical semiconductor element 101 is, for example, a light receiving element such as a PD (Photodiode Device), a line sensor, an image sensor, a CCD (Charge Coupled Device), or a semiconductor element having a light receiving portion such as an EPROM (Erasable and Programmable ROM). is there. The optical semiconductor element 101 has a light receiving portion on the upper surface. In addition, the optical semiconductor element 101 is provided with electrodes 106 for power supply and signal around the light receiving portion on the upper surface.

  The insulating base 102 has a mounting portion on which the optical semiconductor element 101 is mounted on the upper surface. In the example shown in FIG. 1, the insulating base 102 has a concave portion having a mounting portion on the inside on the upper surface. The insulating substrate 102 is made of, for example, ceramics such as alumina sintered body (alumina ceramics), aluminum nitride ceramics, silicon carbide ceramics, silicon nitride ceramics, glass ceramics, resin, or the like.

  Here, a manufacturing method of the insulating substrate 102 when the insulating substrate 102 is made of an alumina sintered body and the bottom plate portion and the side wall portion are integrally formed by firing will be described. First, raw material powders such as alumina and silica are formed into a sheet shape together with an organic solvent and a resin binder to produce a plurality of ceramic green sheets. A part of the ceramic green sheets is punched to produce a frame-shaped ceramic green sheet. Thereafter, the ceramic green sheets are laminated so that the frame-shaped ceramic green sheet is positioned in the upper layer, and fired at a temperature of about 1300 ° C. to 1600 ° C. according to the composition of the raw material powder. Thus, the insulating base 102 is formed. The insulating substrate 102 may be formed by bonding a frame-like alumina sintered body to the outer peripheral portion of the upper surface of the plate-like alumina sintered body.

The bonding material 103 is used for bonding the optical semiconductor element 101 to the bottom surface of the recess of the insulating base 102. Further, the protruding portion 109 is provided in parallel to the side surface on the short side of the optical semiconductor element 101 of the mounting portion, and the bonding material 103 is accumulated between the side surface portion of the optical semiconductor element 101 and the protruding portion 109. It is formed and has a function of reinforcing the strength and reliability of the bonding of the optical semiconductor element 101 and the insulating substrate 102.

That is, the surface shape in the longitudinal cross section between the side surface on the short side of the optical semiconductor element 101 and the protrusion 109 whose upper surface is higher than the upper surface of the optical semiconductor element 101, and the height of the intermediate position is the optical semiconductor element 101. A pool of the bonding material 103 having a corrugated concave shape (curved concave shape) higher than that of the lower surface is formed. With this configuration, the bonding material 103 forms a large pool outside the side surface on the short side of the optical semiconductor element 101 on which thermal stress acts greatly, and the bonding strength between the optical semiconductor element 101 and the insulating base 102 can be improved. it can. Further, since the surface shape in the longitudinal section of the pool of the bonding material 103 between the side surface on the short side of the optical semiconductor element 101 and the protruding portion 109 is a corrugated concave shape, the bonding material 103 is bent (concave shape). Thermal stress can be distributed along the surface. As a result, peeling of the rectangular optical semiconductor element 101 from the short side can be suppressed, and the optical semiconductor device 110 with high bonding reliability can be provided.

  As described above, according to the optical semiconductor device 110 of the present invention, for example, in a rectangular optical semiconductor element 101 such as a line sensor, it is possible to suppress peeling or the like caused by stress concentration on the short side. . Then, external light can be normally received by the optical semiconductor element 101, and normal electrical signals can be transmitted to other external devices and elements.

  As the bonding material 103, a resin adhesive made of a resin such as an epoxy resin, a polyimide resin, an acrylic resin, a silicone resin, or a polyether amide resin can be used.

  The protruding portion 109 is made of, for example, alumina sintered body (alumina ceramics), aluminum nitride ceramics, silicon carbide ceramics, silicon nitride ceramics, glass ceramics, epoxy resin, acrylic resin, silicone resin, or the like. It consists of resin material and glass epoxy resin. The protruding portion 109 may be attached to the insulating base 102 with the same bonding material as the bonding material 103, or a resin adhesive such as an epoxy resin, an acrylic resin, a silicone resin, or a polyether amide resin. It may be glued with. Alternatively, it may be integrally formed with the insulating base 102.

  In FIG. 1, the protruding portion 109 is formed in a plate shape (wall shape). However, the protrusion 109 has an arc shape between the upper surface and the side surface, an inclined upper surface, a trapezoidal shape, or a block shape. Etc.

  As the bonding material 103, epoxy resin, polyimide resin, and polyetheramide resin are suitable when the bonding strength with respect to the insulating substrate 102 is given priority. However, since the bonding material 103 is interposed in a wide area between the insulating base 102 and the optical semiconductor element 101, it is preferable to use a material having a low Young's modulus so that the thermal stress between the two can be easily absorbed.

  The bonding material 103 is elongated in accordance with the shape of the optical semiconductor element 101 and longer than the optical semiconductor element 101 in the long side direction when the optical semiconductor element 101 is mounted on the mounting portion on the bottom surface of the recess of the insulating base 102. In addition, the bonding material 103 is applied to the bottom surface of the recess of the insulating base 102, and the optical semiconductor element 101 is mounted thereon, so that the optical semiconductor element 101 and the insulating base 102 are interposed and bonded together. In addition, the optical semiconductor element 101 is formed so as to cover the side surface on the short side and to have a pool of the bonding material 103 between the protruding portion 109. For example, when the bonding material 103 is made of a resin material, the bonding material 103 is applied by a dispensing method or a screen printing method.

  For the bonding material 103, as shown in FIG. 1B, in the longitudinal section of the covering portion 103a on the side surface on the short side of the optical semiconductor element 101, in order to make the surface shape in the longitudinal section a corrugated concave shape, for example, The following means can be used.

That is, the protrusion 109 is first attached to the insulating base 102 in advance, the bonding material 103 is applied to the inside of the protrusion 109 in the recess of the insulating base 102, and the optical semiconductor element 101 is mounted thereon and attached. Let At this time, by appropriately setting the distance from the side surface on the short side of the optical semiconductor element 101 to the protruding portion 109, the bonding material 103 adheres to the side surface on the short side of the optical semiconductor element 101 by surface tension. At the same time, the cross-sectional shape is convex upward. Further, at the intermediate position between the side surface and the protruding portion 109 that is a distance from the side surface on the short side of the optical semiconductor element 101, the bonding material 103 has a cross-sectional shape that protrudes downward due to its own weight. Furthermore, on the inner side surface of the protruding portion 109, the bonding material 103 adheres due to surface tension and the cross-sectional shape becomes a convex shape. In other words, by appropriately setting the distance from the side surface on the short side of the optical semiconductor element 101 to the protruding portion 109, the surface shape in the longitudinal section has a height at the intermediate position higher than the lower surface of the optical semiconductor element 101. A pool of the bonding material 103 having a concave shape with a high waveform can be formed.

  For example, the distance from the side surface on the short side of the optical semiconductor element 101 to the protrusion 109 is such that the thickness of the bonding material 103, that is, the thickness of the bonding material 103 between the optical semiconductor element 101 and the insulating base 102 is 20 to 80 μm. In this case, 0.3 to 1.7 mm is preferable. If the distance is less than 0.3 mm, the distance is too small, so that the cross-sectional shape of the bonding material 103 does not become a corrugated concave shape. If the distance exceeds 1.7 mm, the distance is too large and the cross-sectional shape of the bonding material 103 becomes a flat shape. In both cases, effective dispersion of stress due to the cross-sectional shape cannot be expected.

  Further, in the optical semiconductor device 110 of the present invention, the optical semiconductor element 101 has the electrode 106 electrically connected to the wiring conductor 104 outside the protrusion 109 on the upper surface of the insulating base 102 via a bonding wire. 109 is preferably provided with a groove (not shown) into which the bonding wire 107 is inserted. As a result, the bonding wire 107 can be fixed in the groove to prevent the occurrence of deformation such as bending, and problems such as electrical shorting due to contact between adjacent bonding wires 107 are effectively prevented, An optical semiconductor device with high electrical connection reliability can be provided.

  Therefore, for example, even in the case where the pitch of the electrodes 106 of the optical semiconductor element 101 is finer and the bonding wire 107 is longer in design (becomes a long wire), the adjacent bonding wires 107 are bent due to bending or deformation of the bonding wires 107. It is possible to effectively prevent a short circuit failure due to contact with the bonding wire 107 and a defective shape of the bonding wire 107, and to further improve the long-term reliability of the optical semiconductor device 110.

  The groove on the upper surface of the protruding portion 109 may have any shape that allows the bonding wire 107 to enter, for example, has a linear shape in plan view, and has dimensions (width and depth) into which the bonding wire 107 can enter. For example, the vertical cross-sectional shape can be various shapes such as an arc shape, a quadrangular shape, and a triangular shape. Further, depending on the loop shape or the like of the bonding wire 107, the depth and width may change midway. In addition, the groove is preferably formed on a straight line connecting the electrode 106 and the bonding portion of the wiring conductor 104.

  In the optical semiconductor device 110 of the present invention, the bonding material 103 preferably covers the side surface of the long side of the optical semiconductor element 101. As a result, the optical semiconductor element 101 can be firmly bonded to the insulating base 102 over the entire periphery, and the optical semiconductor device 110 with higher reliability can be provided.

  The wiring conductor 104 is formed from the upper surface to the lower surface of the insulating base 102 and is electrically connected to the electrode of the optical semiconductor element 101 via the bonding wire 107. The wiring conductor 104 may be formed from the upper surface to the side surface of the insulating base 102. The wiring conductor 104 is made of a metal material such as tungsten, molybdenum, manganese, copper, silver, palladium, platinum, or gold, and is disposed on a predetermined portion of the insulating base 102 in the form of a metallized layer, a plating layer, a vapor deposition layer, a metal foil layer, or the like. It is formed. When the wiring conductor 104 is made of, for example, a tungsten metallized layer, the wiring conductor 104 is formed by printing a metal paste obtained by kneading tungsten powder together with an organic solvent and a resin binder on a ceramic green sheet serving as the insulating substrate 102 by a screen printing method or the like. The Note that the lead conductors made of Fe—Ni—Co alloy, copper, copper alloy, or the like may be attached to the portion of the wiring conductor 104 led to the lower surface or side surface of the insulating base 102 by brazing or the like. Further, a plating layer such as gold plating or tin plating may be deposited on the exposed surface of the wiring conductor 104.

  The lid 105 is attached to the upper surface of the insulating base 102 via an adhesive 108 so as to form a space in which the optical semiconductor element 101 is accommodated. The lid 105 is entirely or partially made of a light transmissive member. In the optical semiconductor device 110 of FIG. 1, the lid 105 is formed by forming a translucent material such as glass, quartz, sapphire, or transparent resin into a plate shape. Although not shown, when the insulating base 102 is a flat plate, a concave lid may be used. In this case, a part of the concave lid is made of a translucent member. Further, an optical film for blocking ultraviolet rays may be formed on at least one of the upper surface and the lower surface of the lid 105.

  The adhesive 108 is made of, for example, a resin adhesive such as an acrylic resin, an epoxy resin, a phenol resin, or a cresol resin. The adhesive 108 may be mixed with dark pigments or dyes such as black, brown, dark brown, dark green, and dark blue for the purpose of blocking extraneous external light. Further, the adhesive 108 may be made of an inorganic material such as glass or a filler powder made of an inorganic material added to a resin adhesive.

  When the adhesive 108 is made of a transparent resin adhesive, it is preferable that the refractive index of the adhesive 108 is equal to the refractive index of the transparent lid 105. In this case, reflection and scattering of light at the interface between the adhesive 108 and the lid 105 can be suppressed, and it is possible to suppress extra reflected light and scattered light from entering the optical semiconductor element 101. Become. Moreover, when the adhesive material 108 consists of a transparent resin adhesive, it is preferable that the volume of the bubble contained in the inside is 30 volume% or less. When the volume of the bubbles exceeds 30% by volume, the bonding force of the adhesive 108 is reduced, and extra reflected light or scattered light may enter the optical semiconductor element 101 due to the bubbles. In order to reduce the ratio of the bubbles contained in the adhesive material 108, there are a method of handling the adhesive material 108 in a decompression chamber or a vacuum device, a method of vacuum degassing the bubbles contained in the adhesive material 108 in advance, and the like.

  Further, a light-shielding resin film may be attached to the outer peripheral portion of the lid 105. With such a configuration, it is possible to prevent extraneous external light from entering the semiconductor element 101.

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the present invention.

(A) is sectional drawing which shows an example of embodiment of the optical semiconductor device of this invention, (b) is an expanded sectional view of the X section of the optical semiconductor device of (a).

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 ... Optical semiconductor element 102 ... Insulating base | substrate 103 ... Bonding material 104 ... Wiring conductor 105 ... Cover body 106 ... Electrode 107 ... Bonding wire 108 ... Adhesive material 109- ..Projecting part 110 ... optical semiconductor device

Claims (3)

A concave portion for accommodating and mounting the optical semiconductor element is formed on the upper surface, and an insulating base having the mounting portion for the optical semiconductor element formed on the bottom surface of the concave portion, from the mounting portion of the insulating base to the side surface or the lower surface A lead-out wiring conductor, a rectangular optical semiconductor element that is mounted and bonded to the mounting portion via a bonding material, and an electrode is electrically connected to the wiring conductor, and the optical semiconductor of the mounting portion Protruding portions provided on the outer side on the short side of the element in parallel with the side surface on the short side of the optical semiconductor element, the upper surface being higher than the upper surface of the optical semiconductor element, and the upper surface of the insulating base A translucent lid attached so as to close the concave portion, and the surface shape in the longitudinal section between the side surface on the short side of the optical semiconductor element and the protruding portion is an intermediate position From the lower surface of the optical semiconductor element The optical semiconductor device, characterized in that concave and has been reservoir of the bonding material of high wave is formed.   In the optical semiconductor element, an electrode is electrically connected to the wiring conductor outside the protruding portion on the upper surface of the insulating substrate via a bonding wire, and the protruding portion is a groove into which the bonding wire enters the upper surface. The optical semiconductor device according to claim 1, wherein: is formed.   The optical semiconductor device according to claim 1, wherein the bonding material covers a side surface on a long side of the optical semiconductor element.

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