SEMICONDUCTOR DEVICE AND METHOD OF MANUFACTURING THE SAME

A method of manufacturing a semiconductor device, includes; preparing an insulated circuit substrate including a circuit layer having a main surface and a side surface inclined to a normal direction of the main surface; irradiating the side surface of the circuit layer with a laser beam so as to roughen at least a part of the side surface of the circuit layer and provide an oxide film on the roughened side surface of the circuit layer; and bonding a semiconductor chip to the main surface of the circuit layer via a solder layer.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims benefit of priority under 35 USC 119 based on Japanese Patent Application No. 2022-045846 filed on Mar. 22, 2022, the entire contents of which are incorporated by reference herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a semiconductor device and a method of manufacturing the semiconductor device

2. Description of the Related Art

Semiconductor devices are known that have a structure in which a semiconductor chip is bonded onto a circuit layer (a circuit pattern) of an insulated circuit substrate by soldering. To deal with solder wettability to avoid a spread of the solder on the circuit layer, a first means (laser resist) is known that irradiates a flat part of the top surface of the circuit layer with a laser beam along the circumference of the solder-bonded part and oxidizes and roughens the surface so as to decrease the wettability of the solder. A second means is also known that surrounds the circumference of the solder-bonded part by a wire at the flat part of the top surface of the circuit layer so as to physically avoid the spread of the solder. A third means is also known that provides slits at the flat part of the top surface of the circuit layer so as to physically avoid a contact of the soldering material between the respective semiconductor chips.

JP 2005-268821 A discloses a ceramic circuit substrate provided with a projecting part that is a metal-brazed layer extending from an outer edge of a metal plate so as to have an inclined surface along the entire circumference of the end surface of the metal plate, in which the projecting part has a maximum surface roughness Rmax of 5 micrometers to 50 micrometers. JP 2007-311526 A discloses a substrate for a power module integrated with a circuit layer by metal brazing on a surface of a ceramic plate, in which a side surface of the outer surface of the circuit layer extending upward from the surface of the ceramic plate in the substantially vertical direction is provided with an oxide film.

WO 2019/003725 A1 discloses that a surface roughness of a side surface of a metal plate is set in a range of 0.3 micrometers to 1.0 micrometers so as to decrease wettability of brazing material. JP 2021-145081 A discloses a semiconductor device including a conductor part, a semiconductor chip, a soldering material, and hollow parts, in which the hollow parts each have an inclined inner surface that is subjected to surface roughening treatment.

JP 2021-039962 A discloses that a power semiconductor chip is arranged at an upper part of a conductive plate, and the other part of the top surface of the conductive plate not provided with the power semiconductor chip is provided with dotted holes by laser irradiation.

The insulated circuit substrate needs to keep an insulating distance between the lands of the circuit layers. However, the respective semiconductor chips are inevitably arranged at positions adjacent to the edge of the top surface of the circuit layer when the respective semiconductor chips are packaged with high density, which would prevent the insulated circuit substrate from keeping the insulating distance, since the soldering material bonding the semiconductor chips spreads toward grooves between the circuit layers. Further, since the respective semiconductor chips need to be arranged at the positions adjacent to the edge of the top surface of the circuit layer, the conventional first to third means described above for dealing with the wettability of the solder cannot sufficiently ensure a space for roughening the surface, arranging the wires, or providing the slits at the flat part on the top surface of the respective circuit layers.

SUMMARY OF THE INVENTION

In view of the foregoing problems, the present invention provides a semiconductor device having a configuration capable of achieving high-density packaging while decreasing solder wettability to avoid a spread of solder for bonding an insulated circuit substrate and a semiconductor chip to each other, and a method of manufacturing the same.

An aspect of the present invention inheres in a semiconductor device including: an insulated circuit substrate including a circuit layer having a main surface and a side surface inclined to a normal direction of the main surface; a semiconductor chip provided to be opposed to the main surface of the circuit layer; and a solder layer provided to bond the semiconductor chip and the circuit layer to each other, wherein a surface roughness of at least a part of the side surface of the circuit layer is greater than a surface roughness of the main surface of the circuit layer at a position opposed to the semiconductor chip.

Another aspect of the present invention inheres in a method of a semiconductor device including: preparing an insulated circuit substrate including a circuit layer having a main surface and a side surface inclined to a normal direction of the main surface; irradiating the side surface of the circuit layer with a laser beam so as to roughen at least a part of the side surface of the circuit layer and provide an oxide film on the roughened side surface of the circuit layer; and bonding a semiconductor chip to the main surface of the circuit layer via a solder layer.

DETAILED DESCRIPTION

With reference to the Drawings, first to fourth embodiments of the present invention will be described below.

In the Drawings, the same or similar elements are indicated by the same or similar reference numerals. The Drawings are schematic, and it should be noted that the relationship between thickness and planer dimensions, the thickness proportion of each layer, and the like are different from real ones. Moreover, in some drawings, portions are illustrated with different dimensional relationships and proportions. The embodiments described below merely illustrate schematically devices and methods for specifying and giving shapes to the technical idea of the present invention, and the span of the technical idea is not limited to materials, shapes, structures, and relative positions of elements described herein.

In the embodiment, a “first main electrode region” of a semiconductor chip is assigned to a semiconductor region which is a source region or a drain region in a field-effect transistor (FET) or a static induction transistor (SIT). The first main electrode region is assigned to a semiconductor region which is an emitter region or a collector region in an insulated-gate bipolar transistor (IGBT). The first main electrode region is assigned to a semiconductor region which is an anode region or a cathode region in a static induction (SI) thyristor, a gate turn-off (GTO) thyristor or a diode. A “second main electrode region” of the semiconductor chip is assigned to a semiconductor region which is not assigned as the first main electrode region and will be the source region or the drain region in the FET or the SIT, the emitter region or the collector region in the IGBT, and the anode region or the cathode region in the SI thyristor, the GTO thyristor or the diode. That is, when the “first main electrode region” is the source region, the “second main electrode region” means the drain region. When the “first main electrode region” is the emitter region, the “second main electrode region” means the collector region. When the “first main electrode region” is the anode region, the “second main electrode region” means the cathode region.

Additionally, definitions of directions such as “upper”, “lower”, “upper and lower”, “left”, “right”, and “left and right” in the following description are simply definitions for convenience of description, and do not limit the technological concept of the present invention. For example, when observing an object rotated by 90 degrees, the “upper and lower” are converted to “left and right” to be read, and when observing an object rotated by 180 degrees, the “upper and lower” are read reversed, which should go without saying.

First Embodiment

FIG.1is a plan view illustrating a main part of a semiconductor device according to a first embodiment, andFIG.2is a cross-sectional view taken along line A-A′ inFIG.1.FIG.1omits the illustration of a sealing member7illustrated inFIG.2. As illustrated inFIG.1andFIG.2, the semiconductor device according to the first embodiment is a power module including an insulated circuit substrate10, a semiconductor chip (a power semiconductor chip)5provided to be opposed to one of main surfaces (the top surface) of the insulated circuit substrate10, and a solder layer4interposed between the insulated circuit substrate10and the semiconductor chip5so as to bond the insulated circuit substrate10and the semiconductor chip5together.

The insulated circuit substrate10has a rectangular planar shape, for example. The insulated circuit substrate10is a direct copper bonded (DCB) substrate or an active metal brazed (AMB) substrate, for example. The insulated circuit substrate10includes an insulating substrate1, circuit layers (circuit patterns)2aand2bthat are conductor layers deposited on one of the main surfaces (the top surface) of the insulating substrate1, and a heat-releasing layer3that is a conductive layer deposited on the other main surface (the bottom surface) of the insulating substrate1.

The insulating substrate1is a ceramic substrate made from aluminum oxide (Al2O3), aluminum nitride (AlN), silicon nitride (Si3N4) or boron nitride (BN), or a resin insulating substrate including polymer material, for example. The circuit layers2aand2band the heat-releasing layer3are each conductor foil made from copper (Cu) or aluminum (Al), for example.

A thickness of the respective circuit layers2aand2bis set in a range of about 0.1 millimeters or greater and 0.5 millimeters or less, for example, but is not limited to this range. The pattern shape, the arrangement position, and the number of the circuit layers2aand2bare determined as appropriate. The circuit layers2aand2bare arranged separately from each other at an insulating distance W1with a pattern groove interposed. The insulating distance W1is set in a range of about 0.5 millimeters or greater and 1.0 millimeters or less, for example, but is not limited to this range.

Although not illustrated, a metal base or a heat-releasing fin may be provided on the other main surface (the bottom surface) of the insulated circuit substrate10via a compound such as thermal interface material (TIM).

The semiconductor chip5is a semiconductor element such as an insulated gate bipolar transistor (IGBT), a field-effect transistor (FET), a static induction (SI) thyristor, a gate turn-off (GTO) thyristor, or a freewheeling diode (FWD), for example. The semiconductor chip5may be either a unipolar device or a bipolar device. The semiconductor chip5may be a silicon (Si) substrate, or may be a compound semiconductor substrate of a wide-bandgap semiconductor made from silicon carbide (SiC), gallium nitride (GaN), gallium arsenide (GaAs), gallium oxide (Ga2O3), or diamond (C), for example.

When the semiconductor chip5is a MOSFET, for example, the semiconductor chip5includes a first main electrode (a drain electrode) on the bottom surface side, and a control electrode (a gate electrode) and a second main electrode (a source electrode) on the top surface side. The drain electrode of the semiconductor chip5is bonded to the circuit layer2aof the insulated circuit substrate10via the solder layer4. The gate electrode and the source electrode of the semiconductor chip5are electrically connected to external elements via bonding wires, lead frames, or pin-shaped terminals (not illustrated), for example.

WhileFIG.1andFIG.2illustrate the case of using the single semiconductor chip5, the number of the semiconductor chips can be determined as appropriate depending on a current capacity of the power module, for example, and the power module may include two or more semiconductor chips. When including two or more semiconductor chips, the power module may include either the same kind of semiconductor chips or different kinds of semiconductor chips.

As illustrated inFIG.2, the insulated circuit substrate10, the solder layer4, and the semiconductor chip5are sealed with the sealing member7. The sealing member7to be used can be made from resin material such as thermosetting resin having high heat resistance. Specific examples of resin material include epoxy resin, maleimide resin, and cyanate resin.

The insulated circuit substrate10, the solder layer4, the semiconductor chip5, and the sealing member7are housed in a case (not illustrated). The case is made from thermoplastic resin such as polyphenylene sulfide (PPS), polybutylene terephthalate (PBT), polybutylene succinate (PBS), polyamide, and acrylonitrile butadiene styrene (ABS), for example.

The following explanations are made while focusing on one (the circuit layer2a) of the two circuit layers2aand2bof the insulated circuit substrate10on which the semiconductor chip5is deposited. The circuit layer2aincludes a main surface (a top surface)21substantially parallel to the top surface of the insulating substrate1, and a side surface22integrated with the top surface21and inclined at a predetermined angle θ1 to the normal direction of the top surface21. The angle θ1 is set in a range of about greater than 0 degrees and 45 degrees or smaller, for example.

The side surface22of the circuit layer2ais provided with an oxide film6. The oxide film6is formed such that the side surface22of the circuit layer2ais heated by irradiation with a laser beam (the specific explanations are made below). The provision of the oxide film6, which has low wettability of solder, can avoid a spread of the solder layer4provided on the top surface21of the circuit layer2aupon the assembly of the semiconductor device.

A thickness of the oxide film6is greater than that of a native oxide film, and is set to about 2 nanometers or greater, for example. The thickness of the oxide film6may be set to about 10 nanometers or greater, or set to about 50 nanometers or greater. The thickness of the oxide film6may be decreased afterward by hydrogen reduction upon reflow soldering in the process of assembling the semiconductor device. For example, the thickness of the oxide film6immediately after being formed may be about 50 nanometers, and the thickness of the oxide film6after the completion of the semiconductor device may be about 10 nanometers. The oxide film6does not necessarily remain but may be removed by the hydrogen reduction during the reflow soldering in the process of assembling the semiconductor device or by a process that can remove the oxide film6, for example. When the oxide film6does not remain, the side surface22of the circuit layer2amay be in contact with the sealing member7.

FIG.3is an enlarged cross-sectional view illustrating region B surrounding a part adjacent to the side surface22of the circuit layer2ainFIG.2. As illustrated inFIG.3, the side surface22of the circuit layer2aprovided with the oxide film6is roughened by the irradiation with the laser beam. The side surface22of the circuit layer2ais corrugated, and the oxide film6has the cross section having the corrugated parts.FIG.3schematically illustrates the state in which the side surface22of the circuit layer2ais roughened, and the oxide film6is provided on the roughened surface, but the present embodiment is not intended to be limited to the shape of the side surface22of the circuit layer2aand the shape of the oxide film6as illustrated inFIG.3.

A surface roughness of the side surface22of the circuit layer2aprovided with the oxide film6, which corresponds to a surface roughness of the oxide film6, is greater than a surface roughness of the top surface21of the circuit layer2anot roughened at the position opposed to the semiconductor chip5. An arithmetic mean roughness Ra of the side surface22of the circuit layer2aprovided with the oxide film6is set to about 25 micrometers or greater, for example, and may be set to about 30 micrometers or greater. Roughening the side surface22of the circuit layer2aprovided with the oxide film6decreases the solder wettability, so as to sufficiently avoid or decrease a spread of the solder layer4deposited on the top surface21of the circuit layer2aupon the assembly of the semiconductor device. The greater surface roughness of the side surface22of the circuit layer2ais preferable since the solder layer4is prevented from spreading more reliably.

When the oxide film6does not remain, the surface roughness of the side surface22of the circuit layer2aitself is greater than the surface roughness of the top surface21of the circuit layer2anot roughened at the position opposed to the semiconductor chip5. The arithmetic mean roughness Ra of the side surface22of the circuit layer2aitself is set to about 25 micrometers or greater, for example, and may be set to about 30 micrometers or greater.

As illustrated inFIG.1, the semiconductor chip5has a rectangular shape in the planar pattern, and the right side5athat is one of the sides of the rectangle of the semiconductor chip5is located at the edge of the top surface21of the circuit layer2a. The semiconductor chip5may be arranged such that the right side5ais arranged away from the edge of the top surface21of the circuit layer2aso as to be located on the inner side of the edge of the top surface21of the circuit layer2a. WhileFIG.1illustrates the case in which the solder layer4protrudes to the outside of the semiconductor chip5, the edge of the solder layer4may conform to the edge of the semiconductor chip5, or may be located on the inside of the semiconductor chip5.

The oxide film6is selectively provided at a part of the side surface22of the circuit layer2aopposed to the right side5aof the semiconductor chip5. The oxide film6may be provided in a region longer than the right side5aof the semiconductor chip5, for example. The surface roughness of the roughened side surface22of the circuit layer2aprovided with the oxide film6is greater than the surface roughness of the side surface22of the circuit layer2anot roughened or not provided with the oxide film6. When the oxide film6is not provided, the surface roughness of the roughened side surface22of the circuit layer2aat the position corresponding to the oxide film6illustrated inFIG.1is greater than the surface roughness of the side surface22of the circuit layer2anot roughened at the position not corresponding to the oxide film6.

<Method of Manufacturing Semiconductor Device>

An example of a method of manufacturing (assembling) the semiconductor device according to the first embodiment is described below.

First, as illustrated inFIG.4, the insulated circuit substrate10is prepared. The insulated circuit substrate10includes the insulating substrate1, the circuit layers2aand2bprovided on the top surface side of the insulating substrate1, and the heat-releasing layer3provided on the bottom surface side of the insulating substrate1. The circuit layer2ahas the top surface21and the side surface22integrated with the top surface21and inclined at the predetermined angle θ1 to the normal direction of the top surface21.

Next, as illustrated inFIG.5, the side surface22of the circuit layer2ais irradiated with a laser beam L1so as to roughen and heat the side surface22of the circuit layer2ato provide the oxide film6on the roughened side surface22of the circuit layer2a. This step leads the surface roughness of the roughened side surface22of the circuit layer2aprovided with the oxide film6to be greater than the surface roughness of the top surface21of the circuit layer2anot roughened at the position opposed to the semiconductor chip5. The oxide film6is provided to have the thickness that is sufficient for the reflow soldering described below and is about 10 nanometers or greater, for example, or may be about 50 nanometers or greater. The thickness of the oxide film6can be adjusted by the regulation of irradiating power of the laser beam for providing the oxide film6.

The laser beam L1may be a fiber laser, a YAG laser, or a carbon dioxide (CO2) laser, for example. The regulation of the irradiation power of the laser beam L1can adjust the thickness of the oxide film6. The regulation of the irradiation power or a spot diameter of the laser beam L1can also adjust the surface roughness of the side surface22of the circuit layer2a.

An irradiation angle θ2 of the laser beam L1to the normal direction of the top surface21of the circuit layer2ais set in a range of about 0 degrees or greater and 45 degrees or smaller. The laser beam L1may be emitted in the normal direction of the top surface21of the circuit layer2a, or may be emitted in a direction inclined toward the normal direction of the side surface22of the circuit layer2awith respect to the normal direction of the top surface21of the circuit layer2a.

The laser beam L1may be emitted to the side surface22of the circuit layer2ain the substantially orthogonal direction. When the angle θ1 of the side surface22inclined to the normal direction of the top surface21of the circuit layer2ais 45 degrees, for example, the irradiation angle θ2 of the laser beam L1to the normal direction of the top surface21of the circuit layer2ais set to 45 degrees. The laser beam L1may be emitted in a direction inclined to the side surface22of the circuit layer2a. When the angle θ1 of the side surface22inclined to the normal direction of the top surface21of the circuit layer2ais 45 degrees, for example, the irradiation angle θ2 of the laser beam L1may be set to 0 degrees so that the laser beam L1is emitted in the normal direction of the top surface21of the circuit layer2a.

Alternatively, the pulsed laser beam L1may be led to scan the side surface22of the circuit layer2ato intermittently form dotted holes so as to continuously provide the oxide film6around the dotted holes. Alternatively, the laser beam L1may be led to scan the side surface22of the circuit layer2anot in the pulsed state but straightly to form a line-shaped groove so as to continuously provide the oxide film6around the groove. Alternatively, the laser beam L1may be led to straightly scan the side surface22of the circuit layer2aonce in the upper-lower direction inFIG.1or may be led to scan several times in parallel, or may be led to scan the side surface22of the circuit layer2ain a zigzag state in the planar pattern inFIG.1.

Next, a soldering material for forming the solder layer4is put on the top surface21of the circuit layer2aof the insulated circuit substrate10. The soldering material may be a plate-like preform material or cream solder, for example. The semiconductor chip5is further deposited on the top surface21of the circuit layer2aof the insulated circuit substrate10via the soldering material.

Next, the stacked body of the insulated circuit substrate10, the soldering material, and the semiconductor chip5is put into a heating furnace. Heating and melting the soldering material in the heating furnace forms the solder layer4so as to bond the insulated circuit substrate10and the semiconductor chip5to each other. Roughening the side surface22of the circuit layer2aprovided with the oxide film6can decrease the solder wettability to avoid a spread of the solder layer4toward the side surface22of the circuit layer2a. The heating conditions are preferably set to a temperature in a range of about 280 degrees or higher and 350 degrees or lower under the hydrogen atmosphere, and a time for a bonding-peak temperature in a range of about 1 minute or longer and 10 minutes or shorter, for example, so as to decrease the wettability of the solder layer4to sufficiently avoid the spread of the solder layer4.

The thickness of the oxide film6is preferably kept at about 10 nanometers or greater during the period from the point at which the heating treatment in the heating furnace is started to the point at which the spread of the solder layer4is completely stopped. Keeping the thickness of the oxide film6at about 10 nanometers or greater can decrease the wettability of the solder layer4to sufficiently avoid the spread of the solder layer4. The greater thickness of the oxide film6is preferable so as to avoid the spread of the solder layer4more reliability. Upon the heating treatment under the hydrogen atmosphere, which reduces the oxide film6, the thickness of the oxide film6immediately after being formed is preferably set to 50 nanometers or greater, for example, in view of the reduced amount of the oxide film6. Setting the thickness of the oxide film6to 50 nanometers or greater can keep the thickness sufficient to avoid the spread of the solder layer4when the heating treatment is executed under the hydrogen atmosphere afterward. A step of removing the oxide film6may be executed after the formation of the solder layer4.

Next, bonding wires, lead frames, or pin-shaped terminals are connected to the semiconductor chip5. The stacked body of the insulated circuit substrate10, the solder layer4, and the semiconductor chip5is placed inside a case, and the case is then filled with the sealing member7so as to seal the insulated circuit substrate10and the semiconductor chip5together. A heat-releasing base or a heat-releasing fin is attached to the bottom surface side of the insulated circuit substrate10. The semiconductor device according to the first embodiment is thus completed through the procedure as described above.

COMPARATIVE EXAMPLES

A semiconductor device of a comparative example is described below with reference toFIG.6toFIG.9. The semiconductor device of the comparative example illustrated inFIG.6andFIG.7having a structure with no measures taken to deal with the solder wettability differs from the semiconductor device according to the first embodiment in which the side surface22of the circuit layer2ais not provided with the oxide film or not roughened. The semiconductor device of the comparative example with the structure not dealing with the solder wettability illustrated inFIG.6causes the solder layer4to spread toward the pattern groove between the circuit layers2aand2bthrough the side surface22of the circuit layer2aduring the assembly, which cannot sufficiently keep the insulating distance W1, resulting in a short circuit between the circuit layers2aand2b. The semiconductor device of the comparative example illustrated inFIG.7also causes a projection on the side surface22of the circuit layer2abecause of the spread of the solder layer4, which cannot sufficiently keep the insulating distance W1either.

In contrast to the semiconductor device of the comparative example illustrated inFIG.6andFIG.7, the semiconductor device and the method of manufacturing the semiconductor device according to the first embodiment can decrease the solder wettability to sufficiently avoid the spread of the solder layer4on the side surface22of the circuit layer2a, since the side surface22of the circuit layer2aprovided with the oxide film6is roughened during the reflow soldering of the solder layer4.

A semiconductor device of another comparative example illustrated inFIG.8having a structure with no measures taken to deal with the solder wettability differs from the semiconductor device according to the first embodiment in which the side surface22of the circuit layer2ais not provided with the oxide film or not roughened. The semiconductor device of the comparative example with the structure not dealing with the solder wettability illustrated inFIG.8needs to arrange the semiconductor chip5at a position away from the edge of the top surface21of the circuit layer2awith a predetermined distance W2kept in order to avoid the spread of the solder layer4toward the side surface22of the circuit layer2a, which impedes the packaging with high density.

In contrast to the semiconductor device of the comparative example illustrated inFIG.8, the semiconductor device and the method of manufacturing the semiconductor device according to the first embodiment can decrease the solder wettability to sufficiently avoid the spread of the solder layer4on the side surface22of the circuit layer2a, since the side surface22of the circuit layer2aprovided with the oxide film6is roughened during the reflow soldering of the solder layer4. This configuration can arrange the semiconductor chip5immediately close to the edge of the top surface21of the circuit layer2a, so as to achieve the packaging at high density. When the semiconductor chip5is not necessarily arranged immediately close to the edge of the top surface21of the circuit layer2a, the flexibility of the arrangement of the semiconductor chip5can be increased.

A semiconductor device of still another comparative example illustrated inFIG.9differs from the semiconductor device according to the first embodiment in that the top surface21of the circuit layer2ais irradiated with a laser beam so as to be roughened and provided with the oxide film8in order to deal with the solder wettability. The semiconductor device of the comparative example illustrated inFIG.9needs to keep a predetermined distance (space) W3for forming the oxide film8on the top surface21of the circuit layer2a, which prevents the arrangement of the semiconductor chip5at the edge of the top surface21of the circuit layer2aand impedes the packaging with high density. The semiconductor device of the comparative example, if provided with wires or slits on the top surface21of the circuit layer2ato deal with the solder wettability, also has the same problems as in the case described above.

In contrast to the semiconductor device of the comparative example illustrated inFIG.9, the semiconductor device and the method of manufacturing the semiconductor device according to the first embodiment can decrease the solder wettability to sufficiently avoid the spread of the solder layer4on the side surface22of the circuit layer2a, since the side surface22of the circuit layer2aprovided with the oxide film6is roughened during the reflow soldering of the solder layer4. This configuration can arrange the semiconductor chip5immediately close to the edge of the top surface21of the circuit layer2a, so as to achieve the packaging at high density.

Further, the semiconductor device and the method of manufacturing the semiconductor device according to the first embodiment can improve the adhesion between the side surface22of the circuit layer2aand the sealing member7in the direction parallel to the top surface21of the circuit layer2aand in the normal direction of the top surface21due to the anchor effect since the side surface22of the circuit layer2aprovided with the oxide film6is roughened, so as to avoid the separation of the sealing member7.

Second Embodiment

A semiconductor device according to a second embodiment differs from the semiconductor device according to the first embodiment in that the oxide film6is selectively provided at a part of the side surface22of the circuit layer2atoward the top surface21, as illustrated inFIG.10. The oxide film6is provided at the upper part of the side surface22of the circuit layer2a, but is not provided at the lower part of the side surface22of the circuit layer2a. The upper part of the side surface22of the circuit layer2aprovided with the oxide film6is roughened, while the lower part of the side surface22of the circuit layer2ais not roughened. The other configurations of the semiconductor device according to the second embodiment are substantially the same as those of the semiconductor device according to the first embodiment, and overlapping explanations are not repeated below. The semiconductor device according to the second embodiment may have a configuration in which the oxide film6is removed after the formation of the solder layer4so as not to remain on the side surface22of the circuit layer2a, as in the case of the first embodiment.

A method of manufacturing the semiconductor device according to the second embodiment differs from the method of manufacturing the semiconductor device according to the first embodiment in selectively irradiating a part of the side surface22of the circuit layer2atoward the top surface21with the laser beam. The other steps of the method of manufacturing the semiconductor device according to the second embodiment are substantially the same as those of the method of manufacturing the semiconductor device according to the first embodiment, and overlapping explanations are not repeated below.

The second embodiment, which has the structure in which the oxide film6is selectively provided at a part of the side surface22of the circuit layer2atoward the top surface21, can achieve the effects similar to those in the first embodiment. The second embodiment can also reduce the influence of the laser beam on the insulating substrate1, since the side surface22of the circuit layer2ais selectively irradiated with the laser beam at a part toward the top surface21. The oxide film6may be selectively provided at a part of the side surface22of the circuit layer2aon the side opposite to the top surface21(toward the insulating substrate1), or may be provided in the middle of the side surface22of the circuit layer2a.

Third Embodiment

A semiconductor device according to a third embodiment differs from the semiconductor device according to the first embodiment in that the oxide film6is provided along a region from the side surface22of the circuit layer2acontinuously to a part of the top surface21of the circuit layer2a, as illustrated inFIG.11. The semiconductor chip5is arranged at a position separated from the edge of the top surface21of the circuit layer2a. The other configurations of the semiconductor device according to the third embodiment are substantially the same as those of the semiconductor device according to the first embodiment, and overlapping explanations are not repeated below. The semiconductor device according to the third embodiment may have a configuration in which the oxide film6is removed after the formation of the solder layer4so as not to remain on the side surface22of the circuit layer2a, as in the case of the first embodiment.

A method of manufacturing the semiconductor device according to the third embodiment differs from the method of manufacturing the semiconductor device according to the first embodiment in irradiating a part of the top surface21of the circuit layer2awith the laser beam in addition to the side surface22of the circuit layer2a. The other steps of the method of manufacturing the semiconductor device according to the third embodiment are substantially the same as those of the method of manufacturing the semiconductor device according to the first embodiment, and overlapping explanations are not repeated below.

The third embodiment with the structure in which the oxide film6is provided along the region from the side surface22of the circuit layer2acontinuously to a part of the top surface21of the circuit layer2a, which slightly decreases the flexibility of the arrangement of the semiconductor chip5, can achieve the effects similar to those in the first embodiment. The third embodiment can also avoid the spread of the solder layer4with higher reliability, since the part of the top surface21of the circuit layer2ais provided with the oxide film6, and the surface roughness of the part of the top surface21of the circuit layer2aprovided with the oxide film6is greater than the surface roughness of the top surface21of the circuit layer2anot provided with the oxide film6.

Fourth Embodiment

A semiconductor device according to a fourth embodiment differs from the semiconductor device according to the first embodiment in the range provided with the oxide film6in the planar pattern, as illustrated inFIG.12. The oxide film6is selectively provided at parts of the side surface22of the circuit layer2aopposed to the right side5aand the lower side5bthat are two continuous sides of the rectangle of the semiconductor chip5. The semiconductor chip5is arranged adjacent to a corner of the top surface21of the circuit layer2a. The right side5aand the lower side5bof the semiconductor chip5are separated from the edge of the top surface21of the circuit layer2awith predetermined distances W4and W5kept. The predetermined distances W4and W5may be the same as or different from each other. The other configurations of the semiconductor device according to the fourth embodiment are substantially the same as those of the semiconductor device according to the first embodiment, and overlapping explanations are not repeated below. The semiconductor device according to the fourth embodiment may have a configuration in which the oxide film6is removed after the formation of the solder layer4so as not to remain on the side surface22of the circuit layer2a, as in the case of the first embodiment.

A method of manufacturing the semiconductor device according to the fourth embodiment differs from the method of manufacturing the semiconductor device according to the first embodiment in selectively irradiating the parts of the side surface22of the circuit layer2aopposed to the right side5aand the lower side5bof the semiconductor chip5with the laser beam. When the side surface22of the circuit layer2ais irradiated with the laser beam in the normal direction of the top surface21of the circuit layer2a, for example, the laser beam may be emitted continuously toward the parts opposed to the right side5aand the lower side5bof the semiconductor chip5. When the side surface22of the circuit layer2ais irradiated with the laser beam in the direction inclined to the normal direction of the top surface21of the circuit layer2a, for example, the laser beam may be emitted two times at different irradiation angles toward the side surface22of the circuit layer2ain the substantially perpendicular direction corresponding to the part opposed to the right side5aand the part opposed to the lower side5aof the semiconductor chip5. The other steps of the method of manufacturing the semiconductor device according to the fourth embodiment are substantially the same as those of the method of manufacturing the semiconductor device according to the first embodiment, and overlapping explanations are not repeated below.

The fourth embodiment, which has the structure in which the oxide film6is selectively provided at the parts of the side surface22of the circuit layer2aopposed to the right side5aand the lower side5bthat are two continuous sides of the rectangle of the semiconductor chip5, can achieve the effects similar to those in the first embodiment.

OTHER EMBODIMENTS

As described above, the invention has been described according to the first to fourth embodiments, but it should not be understood that the description and drawings implementing a portion of this disclosure limit the invention. Various alternative embodiments of the present invention, examples, and operational techniques will be apparent to those skilled in the art from this disclosure.

The configurations disclosed in the first to fourth embodiments may be combined as appropriate within a range that does not contradict with the scope of the respective embodiments. As described above, the invention includes various embodiments of the present invention and the like not described herein. Therefore, the scope of the present invention is defined only by the technical features specifying the present invention, which are prescribed by claims, the words and terms in the claims shall be reasonably construed from the subject matters recited in the present Specification.