JP5122098B2 - Metallized substrate, semiconductor device - Google Patents

Description

  The present invention relates to a metallized substrate, a manufacturing method thereof, and a semiconductor device. In particular, the present invention relates to a metallized substrate having a large surface reflectance suitable for mounting a semiconductor light emitting element, a manufacturing method thereof, and a semiconductor device configured by mounting a semiconductor light emitting element on the substrate.

Patent Document 1 describes a submount including a submount substrate and a solder layer, in which a solder adhesion layer including a noble metal layer and a transition metal layer is formed between the substrate and the solder layer. Yes. The purpose of the submount is to bond semiconductor light emitting elements with high strength. In addition, since the terminal of the semiconductor element is generally made of gold, it is made of the same material as this, and since gold is difficult to be oxidized and stable, the electrode of the submount is generally made of gold. Is formed. Also in the submount described in Patent Document 1, the electrodes are made of gold (examples in the 26th and 52nd paragraphs).
Japanese Patent No. 3509809

  A semiconductor device is manufactured by mounting semiconductor light emitting elements such as LEDs on a submount substrate and covering them with a glass lens or the like. In this case, a part of the light emitted from the upper part of the semiconductor light emitting element is emitted to the outside as it is, and the other part is reflected by the glass lens and returns to the direction of the submount substrate. In order to increase the luminous efficiency of the semiconductor device, it is necessary to further reflect the returned light and radiate the light to the outside. In addition, part of the light emitted from the side surface of the semiconductor light emitting element may be emitted toward the submount substrate in the obliquely downward direction. The submount substrate is required to reflect such light and increase the light emission efficiency.

  In order to satisfy such a requirement and improve the light reflectance of the submount substrate, the present inventors considered to form the electrode on the surface of the submount substrate with aluminum. This is because aluminum has a higher light reflectance than gold and can efficiently reflect light from the semiconductor light emitting element to the outside. In addition, since aluminum has poor wettability with solder compared to gold, the solder does not spread on the electrode when melted. For this reason, when gold is used as the electrode, the submount should be designed to be large in order to design the wire bonding area so as not to get on the solder wetting and spreading portion in consideration of the amount of solder wetting and spreading. However, when an aluminum electrode is used, it is not necessary.

  In addition, when gold is used as an electrode, even if a submount having a plurality of solders is to be mounted in a lump, the solder spreads out so that the solder height during melting cannot be controlled. For example, even if an LED element having a plurality of electrodes is mounted on one element, a bonding failure occurs in part, and it is difficult to manufacture a uniform light-emitting component. For this reason, bonding using expensive gold bumps is now common. However, when an aluminum electrode is used, the solder does not spread on the electrode when it melts. As a result, the thickness of the solder layer at the time of melting can be kept uniform. It becomes.

  However, since the wettability between aluminum and solder is not good, there is a problem that it is difficult to maintain solderability when forming a solder layer for joining with an element on an aluminum electrode. Further, the surface of the aluminum electrode is easily oxidized, and the aluminum oxide layer formed by oxidation has a large electric resistance. Therefore, there is a problem that the element cannot be connected on the aluminum electrode as it is.

  Therefore, an object of the present invention is to provide a submount substrate, a manufacturing method thereof, and a semiconductor device in which a semiconductor light emitting element is mounted on the submount substrate, which can solve such problems.

  The present invention will be described below. In order to facilitate understanding of the present invention, reference numerals in the accompanying drawings are appended in parentheses, but the present invention is not limited to the illustrated embodiment.

  The first aspect of the present invention includes a ceramic substrate (10), a first active metal layer (20) formed on the ceramic substrate, an aluminum electrode (30) formed on the first active metal layer, and the aluminum electrode. A metallized substrate (100A) comprising a barrier layer (50) formed on at least a part of the surface and a solder layer (60) formed on the barrier layer.

  The metallized substrate of the first aspect of the present invention has an aluminum electrode on the substrate surface. Thereby, the light reflectance can be increased, the light of the mounted semiconductor light emitting element can be efficiently emitted to the outside, and the light emission efficiency of the semiconductor light emitting element can be improved. Further, the aluminum electrode has poor solder wettability, and the molten solder does not spread on the aluminum electrode. As a result, the solder layer can be maintained at a predetermined thickness, and the bondability of the semiconductor light emitting element can be improved. Further, by forming a barrier layer on the aluminum electrode and laminating the solder layer via these layers, the bondability of the solder layer can be improved. In addition, by adopting the method for producing a metallized substrate of the present invention, a barrier layer can be formed directly on an aluminum electrode without using an aluminum oxide layer, so that the electric resistance when joining elements is lowered. Can do.

  In the first invention, the second active metal layer (40) is formed on at least a part of the surface of the aluminum electrode, the barrier layer (50) is formed thereon, and the solder layer (60) is formed thereon. Preferably it is formed. With such a configuration, the adhesion of each layer can be further increased, and the bonding strength when the element is mounted can be increased.

  In the first aspect of the present invention, the active metal constituting the first active metal layer (20) and the second active metal layer (40) is one or more selected from the group consisting of titanium, chromium, tungsten, zirconium, hafnium, and tantalum. It is preferable that it is a metal or an alloy. By using such an active metal, adhesion between the ceramic substrate and the aluminum electrode and between the aluminum electrode and the barrier layer can be improved.

  In the first aspect of the present invention, the ceramic substrate (10) is preferably an aluminum nitride substrate. By forming the ceramic substrate with an aluminum nitride substrate having a high thermal conductivity, heat released from the mounted semiconductor light emitting element can be efficiently released to the outside.

  In the first aspect of the present invention, the solder layer (60) preferably does not contain gold. When the solder layer contains gold, when the solder layer melts and the molten solder touches the aluminum electrode, the gold contained in the solder reacts with the aluminum electrode to form a partially brittle alloy There is. This also changes the solder composition. As described above, when the solder contains gold, there is a possibility of adversely affecting the performance when the element is mounted.

  In the first aspect of the present invention, the solder layer (60) is preferably formed of one or more metals selected from the group consisting of tin, silver and lead, or an alloy containing the metal as a main component. As the solder for forming the solder layer, those made of these materials can be used without particular limitation as long as they do not contain gold.

  In the first aspect of the present invention, the barrier layer (50) is preferably formed of any one of platinum, nickel, palladium, copper, cobalt, or silver. A barrier layer formed of these metals has good wettability with molten solder and good adhesion with the solder layer. Moreover, the barrier layer having a predetermined thickness formed of these metals is not dissolved when the solder is melted and is held as a barrier layer. Thereby, it can prevent that a solder reaches | attains a 2nd active metal layer and forms an alloy. If the solder reaches the second active metal layer, the solder and the active metal have poor wettability, which causes a problem that the solder is peeled off from the active metal. Further, the barrier layer is particularly preferably formed of platinum. This is because the solder does not completely dissolve in platinum but partially dissolves, so that the bonding force between the solder and platinum increases, and the solder does not reach the active metal layer below the barrier layer made of platinum. It is.

  In the first aspect of the present invention, an aluminum oxide layer (32) may be formed on the exposed portion of the aluminum electrode (30) where the solder layer (60) is not formed. In the aluminum electrode, the electrode surface is easily oxidized, and an aluminum oxide layer is formed on the electrode surface by being oxidized. Therefore, an aluminum oxide layer is usually formed in a portion where the solder layer is not formed on the aluminum electrode. The aluminum layer may contain silicon in order to increase the corrosion resistance.

  In the first aspect of the present invention, the surface of the aluminum electrode (30) where the solder layer (60) is formed may have a concave shape. When the metallized substrate of the present invention is manufactured, in order to form the barrier layer or the second active metal layer directly on the aluminum electrode, the aluminum oxide layer is etched at the position where the solder layer is formed on the aluminum electrode. Need to be removed. In this etching, a part of the surface of the aluminum electrode may be scraped. In this case, the etched aluminum electrode surface has a concave shape, and a barrier layer or a second active metal layer is formed on the new surface of the aluminum electrode inside the concave shape.

  The second aspect of the present invention comprises the metallized substrate (100A, 100B, 100C) of the first aspect of the present invention, and a semiconductor light emitting element (80) bonded to the solder layer (60) of the metallized substrate. This is a semiconductor device (200). A semiconductor device according to the second aspect of the present invention has various characteristics of the metallized substrate described above.

  The third aspect of the present invention includes a step of forming a first active metal layer (20) on a ceramic substrate (10), a step of forming an aluminum electrode (30) on the first active metal layer, the aluminum electrode A metallization comprising a step of etching at least a part of the surface, a step of forming a barrier layer (50) at the etched portion of the surface of the aluminum electrode, and a step of forming a solder layer (60) on the barrier layer. It is a manufacturing method of a board | substrate (100A).

  The third aspect of the present invention is a method for manufacturing the metallized substrate of the first aspect of the present invention. The aluminum oxide film formed on the surface of the aluminum electrode is removed by etching to expose the aluminum electrode. A barrier layer is formed thereon. Thus, a metallized substrate having an aluminum electrode can be manufactured while keeping the electrical resistance between the terminal of the semiconductor light emitting element and the electrode of the metallized substrate low.

  In the third aspect of the present invention, the method further comprises the step of forming a second active metal layer (40) at the etched portion of the aluminum electrode surface, and the barrier layer (50) on the second active metal layer (40). It is preferable to form a solder layer (60) thereon. By forming the second active metal layer, the adhesion of each layer can be further improved, and the bonding strength of the semiconductor light emitting device can be improved.

  In the third aspect of the present invention, after the step of forming the aluminum electrode (30), the method further includes a step of masking portions other than the surface of the aluminum electrode (30) to be etched by patterning, and each layer (50 formed in the subsequent step) , 60 or 40, 50, 60) are preferably formed in a predetermined pattern by lift-off. The metallized substrate of the present invention can form a solder layer at a predetermined position on the aluminum electrode by patterning such as photolithography.

  Hereinafter, the present invention will be described based on embodiments shown in the drawings.

<Metalized substrate>
FIG. 1 (a) schematically shows one embodiment of the metallized substrate of the present invention. The metallized substrate 100A of the present invention includes a ceramic substrate 10, a first active metal layer 20, an aluminum electrode 30, a barrier layer 50, and a solder layer 60 in this order. The metallized substrate of the present invention may be a submount. In the case of the submount, the back surface of the ceramic substrate 10 (the surface opposite to the surface on which the first active metal layer 20 is formed) Bonded to metallized substrates and heat sinks.

(Ceramic substrate 10)
As the ceramic substrate 10, an aluminum nitride substrate, an aluminum oxide substrate, a silicon carbide substrate, a silicon nitride substrate, or the like can be used. Among these, it is preferable to use an aluminum nitride substrate as the ceramic substrate 10 having high thermal conductivity. By using an aluminum nitride substrate having a high thermal conductivity, heat released from the mounted semiconductor light emitting device 80 can be efficiently released to the outside.

  The ceramic substrate 10 may be formed with a through hole or a via hole that connects the upper surface and the lower surface of the substrate 10. For example, the through-hole is plated inside the through-hole, whereby conduction between the upper and lower surfaces is achieved. The via hole is formed by filling and baking a metal paste inside the through hole.

  The surface roughness of the ceramic substrate 10 is preferably 1 μm or less in terms of Ra, and more preferably 0.05 μm or less because the solder easily comes into contact with the semiconductor element at the time of mounting, and the solder easily spreads. The flatness of the ceramic substrate 10 is preferably 50 μm or less, and more preferably 10 μm or less. By using the ceramic substrate 10 having such surface roughness and flatness, the adhesion with the first active metal layer 20 can be increased, and the bonding strength of the semiconductor light emitting device 80 can be improved. In addition, about surface roughness and flatness, it is the value calculated | required based on JISB0601: 2001.

(First active metal layer 20)
The first active metal layer 20 is a layer formed in order to improve the adhesion between the ceramic substrate 10 and the aluminum electrode 30. As the active metal forming the first active metal layer 20, one or more metals or alloys selected from the group consisting of titanium, chromium, tungsten, zirconium, hafnium, and tantalum can be used. Among these, it is more preferable to use titanium from the viewpoint of exhibiting high adhesion. The reason why the high adhesiveness is expressed is considered that when the ceramic substrate 10 is a nitride, nitrogen and titanium of the ceramic substrate 10 form a nitride. If the thickness of the first active metal layer 20 is too thick, the heat dissipation property may be impaired. If the thickness is too thin, the adhesion may not be ensured. Therefore, the thickness is preferably 0.01 μm or more and 1 μm or less.

(Aluminum electrode 30)
The metallized substrate of the present invention has an aluminum electrode 30. The aluminum electrode 30 has a higher light reflectance than a conventionally used gold electrode. For this reason, the light emitted from the mounted semiconductor light emitting element 80 can be reflected to the outside, and the light emission efficiency of the semiconductor device 200 can be improved. The aluminum electrode 30 generally has poor wettability with solder. Therefore, when the solder is melted, the melted solder does not flow out onto the aluminum electrode 30, the solder layer 60 can be maintained at a predetermined thickness, and the bonding property with the semiconductor light emitting element 80 can be improved. it can. The thickness of the aluminum electrode 30 is preferably 0.1 μm or more and 10 μm or less from the viewpoint of securing wire bonding properties.

(Second active metal layer 40)
The second active metal layer 40 is preferably formed on at least a part of the surface of the aluminum electrode 30. That is, the solder layer 60 for joining the semiconductor light emitting element 80 is formed at a predetermined position of the aluminum electrode 30, but the second active metal layer 40 is formed at the predetermined position where the solder layer 60 is formed. It is preferable that

  FIG. 1B schematically shows the metallized substrate 100B in which the second active metal layer 40 is formed. Similar to the first active metal layer 20, the second active metal layer 40 is a layer for improving adhesion, and the presence of the second active metal layer 40 allows the space between the aluminum electrode 30 and the barrier layer 50. Adhesion can be improved.

  As in the embodiment shown in FIG. 1A, the barrier layer 50 can be formed directly on the aluminum electrode 30 without forming the second active metal layer 40. From the viewpoint of improving the bonding strength of the semiconductor light emitting device 80, it is preferable to form the second active metal layer 40 between the aluminum electrode 30 and the barrier layer 50. The active metal forming the second active metal layer 40 is the same as that forming the first active metal layer 20. The preferred thickness of the second active metal layer 40 is the same as the preferred thickness of the first active metal layer 20.

(Barrier layer 50)
The barrier layer 50 is a layer for improving the adhesion between the aluminum electrode 30 and the solder layer 60. Since the aluminum electrode 30 has poor solder wettability, the solder layer 60 cannot be formed directly on the aluminum electrode 30. Therefore, the solder layer 60 is formed through the barrier layer 50. When the second active metal layer 40 is formed on the aluminum electrode 30 and the barrier layer 50 is formed on the second active metal layer 40 (in the case of 100B in FIG. 1B), the barrier layer 50 Also has a role as a diffusion barrier. That is, the barrier layer 50 prevents the molten solder from diffusing into the second active metal layer 40 when the solder is melted. If the solder diffuses to the second active metal layer 40, the solder and the active metal layer have poor wettability, which causes a problem that the solder is peeled off from the active metal. Thereby, the bonding strength between the layers is greatly reduced, and the bonding strength of the semiconductor light emitting element 80 is reduced. The barrier layer 50 prevents such a situation.

  The barrier layer 50 is preferably formed of any one of platinum, nickel, palladium, copper, cobalt, or silver. In particular, the barrier layer 50 is particularly preferably formed of platinum. This is because the solder does not completely dissolve in platinum but partially dissolves, so that the bonding force between the solder and platinum increases, and the solder does not reach the active metal layer below the barrier layer made of platinum. It is. The thickness of the barrier layer 50 is preferably 0.1 μm or more and 5 μm or less. When the thickness of the barrier layer 50 is too thin, depending on the melting temperature and the melting holding time of the solder layer 40 to be formed, the barrier layer 50 is dissolved at the time of melting the solder, so that the function as the barrier layer cannot be performed. There is. Further, even if the thickness of the barrier layer 50 is not less than the above-mentioned thickness, there is no difference in barrier properties, which is not economical.

(Solder layer 60)
It is preferable that the solder forming the solder layer 60 does not contain gold. When the solder forming the solder layer 60 includes gold, when the solder in the molten solder comes into contact with the aluminum electrode, the gold and aluminum may form a brittle alloy. As a result, the composition of the solder changes, causing an effect such as a decrease in the solder melting and holding time, thereby affecting the performance when the semiconductor light emitting element 80 is mounted.

  As the solder, one or more metals selected from the group consisting of tin, silver, and lead, or an alloy containing the metal as a main component can be used. For example, various known solders such as tin-silver-copper solder, tin-antimony solder, tin-copper solder, and tin-zinc solder can be used. The solder layer 60 may be formed of a plurality of layers made of these metals or alloys. For example, when it is desired to form a silver-tin solder, the first layer may be formed of two layers in a state before melting, such as silver and the second layer of tin. The thickness of the solder layer 60 is preferably 0.1 μm or more and 10 μm or less.

(Aluminum oxide layer 32)
As shown in the schematic diagram of FIG. 1C, an aluminum oxide layer 32 may be formed on the surface of the aluminum electrode 30 where the solder layer 60 is not formed. The surface of the aluminum electrode 30 is easily oxidized, and an aluminum oxide layer 32 is formed on the surface. Since the aluminum oxide layer 32 has a high electric resistance, if the semiconductor light emitting device 80 is mounted via the solder layer 60 in a state where the aluminum oxide layer 32 is formed on the aluminum electrode 30, the terminals of the semiconductor light emitting device 80 are provided. And the electrode 30 become very large in resistance. For this reason, in this invention, the etching demonstrated below is performed with respect to the predetermined location which forms the solder layer 60 on the surface of the aluminum electrode 30, and the aluminum oxide layer 32 in this predetermined location is removed.

  Therefore, as shown in FIG. 1C, the aluminum oxide layer 32 remains as it is at a place other than the formation of the solder layer 60 on the surface of the aluminum electrode 30. Therefore, usually, an aluminum oxide layer 32 is formed on the exposed portion of the metallized substrate of the present invention where the solder layer is not formed.

(Concave shape 34)
As described above, etching is performed on a predetermined portion where the solder layer 60 on the surface of the aluminum electrode 30 is formed. The etching removes the aluminum oxide layer 32 on the surface and also removes a part of the aluminum electrode 30. Thereby, the surface of the aluminum substrate 30 on which the solder layer 60 is formed may be concave. Since the purpose of etching is to remove the aluminum oxide layer 32, it is not always necessary to scrape the surface of the aluminum substrate 30, but the removal of the aluminum oxide layer 32 is ensured and connection reliability is ensured. In view of this, it is preferable that a concave shape 34 having a depth of 0.01 μm to 0.2 μm is formed in a predetermined portion where the solder layer 60 on the surface of the aluminum electrode 30 is formed.

  As a specific method of etching, it is more preferable to use an etching method using a vacuum apparatus that does not use liquid because only a predetermined portion can be etched. As a method of etching only a predetermined portion, after forming the aluminum electrode 30, using a photolithography technique, first, a photoresist is applied to the entire surface, and then a predetermined pattern is exposed and developed to form solder. A resist opening is formed only in the portion. After that, the opening can be etched by irradiating the substrate with argon ions or the like with a dry etching apparatus (also referred to as an ion milling apparatus).

  In the etching method using a liquid, the resist is dissolved in an alkali, so an acidic etching solution must be used. However, since aluminum is generally easily dissolved in an acid, it is difficult to control the amount of dissolution.

  The barrier layer 50 and the solder layer 60 are sequentially formed in the concave shape 34, or the second active metal layer 40, the barrier layer 50, and the solder layer 60 are formed in this order to form the metallized substrate of the present invention. Is done.

<Semiconductor Device 200>
FIG. 1D conceptually shows the semiconductor device 200. The semiconductor device 200 can be obtained by heating the solder layer 60 of the metallized substrates 100 </ b> A, 100 </ b> B, 100 </ b> C to a predetermined temperature and mounting the semiconductor light emitting element 80 on the molten solder layer 60.

(Semiconductor light emitting element 80)
Examples of the material of the semiconductor light emitting element 80 include compound semiconductors such as GaAs, InP, GaN, AlGaN, and AlGaNIn, and those obtained by depositing the compound on sapphire or a silicon substrate. Further, the semiconductor light emitting element 80 may be a laser diode. The light emitting portion may be either the upper surface or the lower surface of the semiconductor light emitting element 80. However, when the light emitting portion is located on the lower surface, the heat generated from the light emitting portion is efficiently transmitted to the outside through the metallized substrate. Has the advantage that it can be released.

<Method for manufacturing metallized substrate>
2A to 2E are process diagrams showing an outline of the method for manufacturing a metallized substrate of the present invention. In FIG. 2, a method for manufacturing the metallized substrate 100C is shown as a representative.

  First, as shown in FIG. 2A, the first active metal layer 20 and the aluminum electrode 30 are formed in order on the ceramic substrate 10. The ceramic substrate 10 can be obtained by a normal method of firing a ceramic green sheet. When a through hole or a via hole is formed in the ceramic base plate 10, it can be formed by a normal method at this stage.

  When the metallized substrate of the present invention is a submount substrate, since the length and width of the substrate are about several millimeters, a base material having a length and width of about 50 mm including a plurality of submount substrates is usually used. After forming and forming a metallized layer on the base material, the submount substrate is manufactured by cutting. Hereinafter, a method of manufacturing a submount substrate by finally cutting an aluminum nitride substrate having a width of 50 mm, a length of 50 mm, and a thickness of 0.4 mm as the ceramic substrate 10 will be described.

  The surface of the aluminum nitride substrate 10 is preferably polished so as to have a preferable surface roughness. The surface roughness Ra is preferably 1 μm or less, more preferably 0.05 μm or less. The polishing method can be performed by a normal method, and for example, polishing can be performed using a grindstone.

  Thereafter, the first active metal layer 20 and the aluminum electrode 30 are sequentially formed on the surface of the aluminum nitride substrate 10. The first active metal layer 20 and the aluminum electrode 30 can be formed by a general thin film forming method. Examples of the thin film forming method include a sputtering method and a vacuum deposition method. In the manufacturing method of the present embodiment, the first active metal layer 20 and the aluminum electrode 30 were formed by sputtering. The first active metal layer 20 was 0.06 μm thick. The aluminum electrode 30 was 1.5 μm thick. As described above, the surface of the aluminum electrode 30 is easily oxidized. FIG. 2A shows a form in which an aluminum oxide layer 32 is formed on the surface of the aluminum electrode 30.

  Next, as shown in FIG. 2B, the surface of the aluminum electrode 30 other than the formation of the solder layer 60 (strictly speaking, the surface of the aluminum oxide layer 32) is masked by patterning. The patterning can be performed, for example, by a photolithography method, and can be performed by forming the resist layer 70 on the surface of the aluminum electrode 30 except for the solder layer 60. In this embodiment, a negative photoresist is used to expose a portion where the solder layer 60 is not formed and develop a non-exposed portion to form a resist layer 70 having a predetermined pattern. By using a negative resist in this manner, a so-called reverse taper type resist pattern can be formed in which the opening is narrower on the upper side and wider on the substrate side. It becomes easy to enter, and even if a solder layer having a thickness of 3 μm or more is formed, lift-off can be easily performed.

  Next, etching is performed using an ion milling apparatus to remove the surfaces of the aluminum oxide layer 32 and the aluminum electrode 30 at portions other than where the resist layer 70 is formed, as shown in FIG. By this etching, the new surface of the aluminum electrode 30 is exposed. Etching may be either wet etching or dry etching, but it is preferable to employ dry etching from the viewpoint of precision workability. Among them, it is preferable to employ sputter etching, particularly ion milling. Because sputter etching and ion milling are purely physical processes, etching can be performed selectively at a predetermined position on the substrate, which is superior in precision workability. is there.

  The surface of the aluminum oxide layer 32 and the aluminum electrode 30 is removed by etching, and thereby a concave shape 34 may be formed on the surface of the aluminum electrode 30. The depth of the concave shape 34 is, for example, 0.01 μm to 0.2 μm.

  Next, as shown in FIG.2 (d), each layer is laminated | stacked in order. The new surface of the aluminum electrode 30 exposed by the etching process is oxidized over time, and the aluminum oxide layer 32 is formed again on the surface. Therefore, it is most preferable to form the second active metal layer 40 or the barrier layer 50 in the same apparatus as that in which the above etching is performed, that is, under the condition that the new surface of the aluminum electrode 30 is not exposed to the outside air.

  In the present embodiment, the second active metal layer 40, the barrier layer 50, and the solder layer 60 are formed in a device different from the device that performs the etching. Therefore, although the new surface of the aluminum electrode 30 is exposed to the outside air for several hours, there is no problem that the resistance between the terminal electrodes of the element increases. Even if the inventors made the new surface of the aluminum electrode 30 come into contact with the outside air, there was no problem that the resistance was particularly increased within 24 hours depending on the atmosphere. However, an increase in resistance was confirmed for those that passed 48 hours or more.

  In the form shown in FIG. 2D, the second active metal layer 40, the barrier layer 50, and the solder layer 60 are formed in order, but the formation of the second active metal layer 40 is optional. However, when the second active metal layer 40 is formed, there is an effect that adhesion between the aluminum electrode 30 and the barrier layer 50 can be improved. In FIG. 2D, the second active metal layer 40, the barrier layer 50, and the solder layer 60 are also formed on the resist 70 other than the concave portion 34. In the present embodiment, titanium is used for the second active metal layer 40, platinum is used for the barrier layer 50, and a silver-tin alloy (3.5% by mass of silver and 96.5% by mass of tin) is used for the solder layer 60. Each layer was formed by vacuum deposition. The thickness of each layer was a titanium layer of 0.06 μm, a platinum layer of 0.2 μm, and a silver-tin alloy layer of 6 μm.

  Thereafter, lift-off for removing the excess metallized layer and the resist is performed. By this lift-off, a predetermined solder pattern 60 can be formed on the aluminum electrode 30 as shown in FIG. The lift-off can be performed by immersing the substrate in a general solution for removing the resist layer 70. In this embodiment, the substrate was immersed in acetone for 60 minutes, the resist layer 70 and the metallized layer thereon were removed, rinsed with IPA, and then dried. The base material substrate formed as described above was finally cut and separated into a desired size to obtain a submount substrate 100.

  The semiconductor device 200 is formed by mounting the semiconductor light emitting element 80 on the submount substrate 100. Specifically, it can be formed by melting the solder layer 60 of the submount substrate 100 by heating and mounting the semiconductor light emitting element thereon. At this time, the molten solder layer 60 does not wet and spread on the aluminum substrate. For this reason, the bondability of the semiconductor light emitting device can be improved. Further, since the solder layer 60 is formed on the aluminum electrode 30 via the barrier layer 50, and in some cases, the second active metal layer 40 and the barrier layer 50, the semiconductor light emitting element 80 is joined to the solder layer 60. The bonding strength of the semiconductor light emitting device can be increased.

  EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

<Example 1>
100 parts by weight of aluminum nitride powder, 5.0 parts by weight of yttrium oxide, 1.0 part by weight of tetraglycerin monooleate as a surfactant, 50 parts by weight of toluene as a solvent, 13 parts by weight of poly n-butyl methacrylate as a binder, and as a plasticizer A white slurry was obtained by mixing 4.2 parts by mass of dibutyl phthalate and 5 parts by mass of butyl acetate with a ball mill.

  Next, the obtained slurry was used to form a sheet by a doctor blade method to produce green sheets for an insulating substrate each having a thickness of 0.6 mm. The obtained green sheet was heated and degreased at 850 ° C. for 2 hours while flowing hydrogen gas containing moisture at 10 (l / min). In addition, the temperature increase rate at the time of degreasing was 2.5 degree-C / min. After degreasing, the degreased body was placed in a container made of aluminum nitride and heated in a nitrogen atmosphere at 1800 ° C. for 5 hours to obtain a sintered body of □ 50 mm and thickness 0.6 mm.

  The obtained sintered body was polished using a lapping polishing apparatus and a buff polishing apparatus to obtain a mirror-finished substrate having a substrate thickness of 0.3 mm, a surface roughness (Ra) of 0.03 μm, and a warp of the entire substrate of 80 μm. The obtained mirror-finished substrate is washed with an acid / organic solvent and then dried, and a 0.06 μm titanium thin film (first active metal layer) and a 1.2 μm aluminum thin film are sequentially formed on the surface of the substrate by sputtering. A single-sided metallized substrate was produced.

  Thereafter, a negative resist is applied to the surface, exposed using a predetermined chrome mask, and then developed using a resist developer, thereby producing a resist patterning substrate having a plurality of openings having a width of 200 μm and a length of 1 mm. did.

  The obtained resist patterning substrate was etched for 1 minute using an argon milling apparatus. After part of the substrate was broken and the resist was removed, the difference in level between the resist opening and the resist non-opening was measured using a stylus-type shape measuring machine.

  For the remaining substrate on which the resist pattern is formed, using an ion beam vacuum deposition machine, a 0.06 μm titanium thin film (second active metal layer) and a 0.2 μm platinum thin film are sequentially formed, and then Using a binary ion beam, a 4 μm solder layer composed of 3.5% by mass of silver and the remaining tin was formed. Thereafter, the resist was removed with acetone to obtain a metallized substrate having a solder pattern with a width of 200 μm and a length of 1 mm.

  The resistance between the aluminum electrodes measured from the solder surface of the obtained metallized substrate by a four-terminal method was 30 mΩ. Further, after heating the obtained metallized substrate for 30 seconds at 245 ° C. while flowing nitrogen gas as an assist gas, the area of the solder layer surface was confirmed, and wetting from the side edge of the solder layer to the aluminum electrode layer surface The spread could hardly be confirmed and was almost the same as before the deposition. The width from the side edge of the solder layer to the periphery of the solder wetted on the aluminum electrode surface was 10 μm or less.

  Further, a 0.06 μm titanium thin film, a 0.2 μm platinum thin film, and a 0.6 μm gold thin film were sequentially applied to an aluminum nitride substrate having a thickness of 0.2 mm and a surface roughness of 0.04 μm. The dummy chip for joining was produced by cutting into 2 mm and a length of 1 mm. After mounting the bonding dummy chip on the solder layer of the metallized substrate produced as described above, the dummy chip was bonded by heating the metallized substrate at 245 ° C. for 30 seconds while flowing nitrogen gas as an assist gas. Then, the dummy chip portion was pushed in the transverse direction at a speed of 10 mm / second until the shear strength was measured, and the shear strength was 20 MPa (breaking strength / joining area). The failure mode was between solder and solder.

<Example 2>
A metallized substrate was produced and evaluated in the same manner as in Example 1 except that the second active metal layer was not formed. The solder spread on the surface of the aluminum electrode layer after melting was 10 μm or less, the shear strength was 16 MPa, and the resistance between the solder and the aluminum electrode was 30 mΩ.

<Examples 3 to 8>
Except for the thickness, composition, etc. shown in Table 1, the first active metal layer, electrode, etching time (etching amount), second active metal layer, barrier layer, and solder layer were the same as in Example 1, A metallized substrate was produced. Evaluation similar to Example 1 was performed with respect to each metallized board | substrate. Note that the solder melting condition was 20 ° C. higher than the solder melting point.

<Comparative Example 1>
A platinum layer and a gold layer are formed as electrode layers on titanium, which is the first active metal layer, and the electrode layers are not etched. Otherwise, a metallized substrate is fabricated and evaluated in the same manner as in Example 1. went. The solder spread on the surface of the gold electrode layer after melting was 40 to 80 μm, and the solder spread on the surface of the gold electrode.

<Comparative example 2>
A metallized substrate with solder was prepared and evaluated in the same manner as in Example 7 except that the barrier layer was not formed. The shear strength was as low as 2 MPa.

<Comparative Example 3>
Evaluation was performed by forming lead-tin solder directly on the aluminum electrode without etching. The resistance between the solder and the electrode was as high as 180 mΩ, and the shear strength was as low as 1 MPa. The manufacturing conditions of Examples 1 to 8 and Comparative Examples 1 to 3 described above are summarized in Table 1, and the evaluation results are summarized in Table 2.

  While the present invention has been described in connection with embodiments that are presently the most practical and preferred, the present invention is not limited to the embodiments disclosed herein. However, the invention can be changed as appropriate without departing from the scope or spirit of the invention that can be read from the claims and the entire specification, and a metallized substrate, a semiconductor device, and a method for manufacturing the metallized substrate accompanying such a change are also disclosed in the present invention. It should be understood as encompassed within the technical scope.

It is a conceptual diagram which shows the structure of the metallized board | substrate of this invention. It is explanatory drawing of each process of the manufacturing method of the metallized board | substrate of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Ceramic substrate 20 1st active metal layer 30 Aluminum electrode 40 2nd active metal layer 50 Barrier layer 60 Solder layer 70 Resist layer 80 Semiconductor light emitting element 100A, 100B, 100C Metallized substrate 200 Semiconductor device

Claims (13)

A ceramic substrate, a first active metal layer formed on the ceramic substrate, an aluminum electrode having a concave shape formed on the first active metal layer and formed by etching;
A metallized substrate comprising a barrier layer formed in the concave shape on the surface of the aluminum electrode, a solder layer formed on the barrier layer, and a semiconductor light emitting device bonded to the solder layer of the metallized substrate A semiconductor device comprising and comprising. A ceramic substrate, a first active metal layer formed on the ceramic substrate, an aluminum electrode having a concave shape formed on the first active metal layer and formed by etching;
A metallization comprising: a second active metal layer formed in the concave shape on the surface of the aluminum electrode; a barrier layer formed on the second active metal layer; and a solder layer formed on the barrier layer. A semiconductor device comprising a substrate and a semiconductor light emitting element bonded to a solder layer of the metallized substrate. The active metal constituting the first active metal layer and the second active metal layer is one or more metals or alloys selected from the group consisting of titanium, chromium, tungsten, zirconium, hafnium, and tantalum. 2. The semiconductor device according to 2 . The semiconductor device according to claim 1, wherein the ceramic substrate is an aluminum nitride substrate . The semiconductor device according to claim 1, wherein the solder layer does not contain gold . The semiconductor device according to claim 1, wherein the solder layer is formed of one or more metals selected from the group consisting of tin, silver, and lead, or an alloy containing the metal as a main component . The semiconductor device according to claim 1, wherein the barrier layer is formed of any one of platinum, nickel, palladium, copper, cobalt, or silver . The semiconductor device according to claim 1, wherein an aluminum oxide layer is formed on a surface exposed portion of the aluminum electrode where a solder layer is not formed . The semiconductor device according to claim 1, wherein a depth of the concave shape on the surface of the aluminum electrode is 0.01 μm to 0.2 μm . The semiconductor device according to claim 1, wherein the barrier layer has a thickness of 0.1 μm to 5 μm . Forming a first active metal layer on the ceramic substrate;
Forming an aluminum electrode on the first active metal layer;
Etching at least part of the surface of the aluminum electrode;
Forming a barrier layer on the etched surface of the aluminum electrode surface;
Forming a solder layer on the barrier layer;
With
A ceramic substrate, a first active metal layer formed on the ceramic substrate, an aluminum electrode formed on the first active metal layer and having a concave shape formed by etching, and formed in the concave shape on the surface of the aluminum electrode A method for producing a metallized substrate comprising a barrier layer formed on the barrier layer and a solder layer formed on the barrier layer . Forming a first active metal layer on the ceramic substrate;
Forming an aluminum electrode on the first active metal layer;
Etching at least part of the surface of the aluminum electrode;
Forming a second active metal layer on the etched surface of the aluminum electrode surface;
Forming a barrier layer on the second active metal layer;
Forming a solder layer on the barrier layer;
With
A ceramic substrate, a first active metal layer formed on the ceramic substrate, an aluminum electrode formed on the first active metal layer and having a concave shape formed by etching, and formed in the concave shape on the surface of the aluminum electrode A method for producing a metallized substrate , comprising: the second active metal layer formed, a barrier layer formed on the second active metal layer, and a solder layer formed on the barrier layer . After the step of forming the aluminum electrode,
The method for producing a metallized substrate according to claim 11 or 12 , further comprising a step of masking a portion other than the surface of the aluminum electrode to be etched by patterning, and forming each layer formed in the subsequent step into a predetermined pattern by lift-off.

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