JP4836769B2 - Semiconductor light emitting device and manufacturing method thereof - Google Patents

Description

  The present invention relates to a semiconductor light emitting device and a manufacturing method thereof.

  In recent years, semiconductor light-emitting devices using LEDs as light-emitting elements have become widespread, and further improvement in light extraction efficiency and durability has been demanded. As an example of a semiconductor light emitting device, Patent Document 1 discloses an LED package in which a metal film for supplying power to a light emitting element is provided in a horn formed by anisotropic etching on a Si (silicon) wafer. Yes. The metal film in the horn is used not only as an electrode for power supply but also as a reflection film for efficiently extracting light emitted from the light emitting element to the upper part.

That is, the metal film in the horn is formed on the silicon oxide film SiO ₂ as an insulating film formed on the surface of the Si wafer, on an adhesion layer with SiO ₂ such as Ti (titanium) or Cr (chromium), On top, a barrier metal layer made of Ni (nickel), Pt (platinum) or the like for preventing Au (gold) -Sn (tin) eutectic bonding or solder bonding from diffusing into the Si wafer, and the uppermost layer Is constituted by a reflective layer having a high reflectance, and with this configuration, the luminous flux from the LED can be efficiently extracted to the outside.

  Thus, an electrode pattern can be formed by forming a horn on a silicon substrate, forming a metal film in the horn, and etching or lifting off the metal film. Here, as described above, the metal film formed inside the horn also serves as a reflection film that efficiently extracts light emitted from the semiconductor light emitting element to the upper part.

For the silicon substrate on which the electrode pattern is formed in this manner, the semiconductor light emitting device is electrically connected by wire bonding after die bonding, or electrically connected through bumps, and then resin-sealed, A semiconductor light emitting device can be manufactured.
JP 2005-277380 A

  In the semiconductor light emitting device, the reflective layer is made of a metal having a particularly high reflectance.

  In FIG. 1, the graph showing the reflectance with respect to the wavelength of the light of each metal is shown. As shown in FIG. 1, Ag (silver) has the highest reflectance in the visible region, and is used as the main reflective film and electrode material of the LED package, that is, as the material of the reflective layer. As a material for the reflective layer, in addition to Ag, Al or an Ag alloy as described later is also used.

  Further, as described above, Ti or the like is used for the adhesion layer.

  By the way, when Ti is used for the adhesion layer, Ti has very high adhesion to the silicon oxide film in a state where no thermal history is applied, but the adhesion decreases when the thermal history is applied. As a specific example, there is a phenomenon in which peeling occurs when the silicon substrate is diced together with a metal film after being heated in the atmosphere at 285 ° C. for 300 seconds. As described above, when dicing is performed after a thermal history has been passed after the package is mounted, the metal film may be peeled off. It is also conceivable that the adhesion of the film is lowered due to the temperature cycle accompanying the ON / OFF switching of the LED, and peeling occurs. When the metal film is peeled off, the electrode pattern is disconnected, causing the semiconductor light emitting device to be unlit.

  Although the cause of the decrease in the adhesion of the Ti adhesion layer due to heating is not clear, changes in the interface state due to oxidation, nitridation, and carbonization of Ti, and accumulation of thermal stress due to lattice rearrangement, etc. This is expected as a cause of lowering the adhesion.

  An object of this invention is to provide the semiconductor light-emitting device which can prevent the fall of the adhesiveness of the contact | adherence layer by heating, and its manufacturing method.

In order to achieve the above object, an invention according to claim 1 includes an insulating film formed on a surface of a predetermined substrate,
A metal layer formed on the insulating film;
A semiconductor light emitting device,
The metal layer is provided with an adhesion layer for adhesion to the insulating film, and a reflective layer above the adhesion layer,
The reflective layer has a function as a reflective surface for the light emitted from the semiconductor light emitting element,
The adhesion layer is a semiconductor light emitting device formed of a Ti—Ni alloy.

  According to a second aspect of the present invention, in the semiconductor light emitting device according to the first aspect, the adhesion layer formed of the Ti-Ni alloy has a Ti concentration range of 25 to 70 at. It is characterized by%.

  According to a third aspect of the present invention, in the semiconductor light emitting device according to the first or second aspect, the reflective layer is made of a material that has a higher reflectivity with respect to light emitted from the semiconductor light emitting element than the adhesive layer. It is characterized by becoming.

  According to a fourth aspect of the present invention, in the semiconductor light emitting device according to the third aspect, the metal layer is provided with a barrier metal layer on the adhesion layer, and the reflective layer is provided on the barrier metal layer. The barrier metal layer is formed of Ni, Pt or Pd.

  According to a fifth aspect of the present invention, in the semiconductor light emitting device according to the fourth aspect, the adhesion layer formed of the Ti-Ni alloy has a thickness in the range of 15 nm to 2000 nm. It is said.

  According to a sixth aspect of the present invention, in the semiconductor light emitting device according to any one of the first to fourth aspects, the reflective layer is formed of Ag, Al, or an Ag alloy. Yes.

  The invention according to claim 7 is the semiconductor light-emitting device according to claim 6, wherein the Ag alloy is an alloy containing at least one of Bi, Au, Pd, Cu, Pt, and Nd. It is a feature.

The invention according to claim 8 includes: (a) a step of forming an insulating film on the surface of the silicon substrate;
(B) forming an adhesion layer made of a Ti-Ni alloy as a material on the insulating film;
(C) forming a barrier metal layer made of Ni, Pt or Pd on the adhesion layer;
(D) forming a reflective layer made of Ag, Al, or an Ag alloy on the barrier metal layer;
(E) electrically connecting a semiconductor light emitting element to the reflective layer;
A method of manufacturing a semiconductor light emitting device, comprising:

  The invention according to claim 9 is the method of manufacturing a semiconductor light emitting device according to claim 8, wherein the adhesion layer made of the Ti—Ni alloy is formed by sputtering with a Ti—Ni alloy target, or a Ti target and Ni. Binary simultaneous sputtering with target, binary simultaneous vapor deposition with Ti vapor deposition material and Ni vapor deposition material, or alloying by heat treatment after alternating film formation of Ti film and Ni film using any of sputtering, vapor deposition and CVD It is characterized in that it is formed by one of the methods.

The invention described in claim 10 is the method for manufacturing a semiconductor light emitting device according to claim 8, wherein the step (a) includes:
(A-1) forming a horn composed of a bottom surface of (100) plane and four inclined sides of (111) plane by performing anisotropic etching on the silicon substrate;
(A-2) forming an insulating film on the silicon substrate surface on which the horn is formed;
It is characterized by having.

According to invention of Claim 1 thru | or 10, it has the insulating film formed on the surface of the predetermined | prescribed board | substrate, the metal layer formed on this insulating film, and a semiconductor light-emitting device, The said metal layer Is provided with an adhesion layer for adhesion to the insulating film, and the adhesion layer is formed of a Ti-Ni alloy, so that the adhesion of the adhesion layer is reduced by heating. Can be prevented.

  Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings.

  FIG. 2 is a diagram showing a configuration example of a semiconductor light emitting device (for example, an LED package or an LED lamp) according to the present invention. Referring to FIG. 2, the semiconductor light emitting device includes an insulating film (eg, silicon oxide film) 3b formed on the surface of a predetermined substrate (eg, silicon substrate) 3a, and a metal layer 5 formed on the insulating film 3b. And the semiconductor light emitting element 4 (for example, LED chip), the metal layer 5 includes an adhesion layer 3c for adhesion to the insulating film 3b, and a reflective layer above the adhesion layer 3c. 3e, the reflective layer 3e functions as a reflective surface for the light emitted from the semiconductor light emitting device 4, and the adhesion layer 3c is formed of a Ti-Ni alloy. It is characterized by.

  Here, the semiconductor light emitting element 4 and the metal layer 5 can be electrically connected (that is, the semiconductor light emitting element 4 and the reflective layer 3e can be electrically connected as described later). In this case, the metal layer 5 (reflective layer 3e) can also function as an electrode of the semiconductor light emitting element 4. That is, in this case, the reflective layer 3 e functions as a reflective film / electrode for the semiconductor light emitting element 4.

  FIG. 3 is a diagram showing a more specific configuration example of the semiconductor light emitting device of the present invention. Referring to FIG. 3, in the semiconductor light emitting device, in the configuration of FIG. 2, the metal layer 5 is provided with a barrier metal layer 3d on the adhesion layer 3c and emitted from the semiconductor light emitting element 4 on the barrier metal layer 3d. A reflective layer 3e that functions as a reflective surface for the reflected light is provided.

  Here, the surface of a predetermined substrate (for example, a silicon substrate) 3a is not illustrated in FIGS. 2 and 3, but is processed into a horn shape, for example, as will be described later. A layer 3c, a barrier metal layer 3d, and a reflective layer 3e are formed.

  2 and 3, the adhesion layer 3c formed of the Ti—Ni alloy has a Ti concentration range (Ti composition range) of 25 to 70 at. %.

  Further, the adhesion layer 3c formed of the Ti—Ni alloy has a thickness in the range of 15 nm to 2000 nm.

  In the configuration example of FIG. 3, the barrier metal layer 3d is provided to prevent Au (gold) -Sn (tin) eutectic bonding, solder bonding, and the like from diffusing into the silicon substrate 3a. Or it is formed of Pd.

  In the configuration example of FIG. 3, the reflective layer 3 e has high reflectivity, and further has conductivity, and when it has conductivity, it reflects the semiconductor light emitting element 4. By being electrically connected to the layer 3e, the reflective layer 3e functions as a reflective film and electrode for the semiconductor light emitting element 4.

  Specifically, the reflective layer 3e is formed of Ag, Al, or an Ag alloy.

  The Ag alloy is an alloy containing at least one of Bi, Au, Pd, Cu, Pt, and Nd. Specifically, as an Ag alloy, for example, Bi is 0.05 to 0.15 at. %, And an alloy containing at least one of Au, Pd, Cu, Pt, and Nd more than Bi is desirable from the viewpoint of durability.

  As described above, the reflective layer 3e can be formed of Ag, Al, or an Ag alloy, and among these, it is preferable to be formed of an Ag alloy. That is, Ag is a metal having the highest reflectance in the visible light region, and is an optimum metal for the reflective film (reflective layer) of the semiconductor light emitting device in that light can be extracted efficiently. However, Ag is a chemically active metal, has poor corrosion resistance such as sulfidation, and has a defect that aggregation due to heating easily occurs. On the other hand, corrosion resistance and heat resistance can be improved by making the reflective layer 3e (reflective film and electrode) into an Ag alloy (by adding an alloy element to Ag).

  In the configuration examples of FIGS. 2 and 3, since the adhesion layer 3 c is formed of a Ti—Ni alloy, it is possible to prevent a decrease in adhesion of the adhesion layer 3 c due to heating.

  Specifically, by using a Ti—Ni alloy composed of Ti and Ni in an appropriate composition range as the adhesion layer 3c, the adhesion can be remarkably improved as compared with Ti. In addition, in a semiconductor light-emitting device that originally used Ti as the adhesion layer and Ni as the barrier metal layer, the conventional film-forming apparatus and film-forming materials can be used as they are by means of co-evaporation and co-sputtering techniques. There is no need for additional equipment and materials, which is extremely advantageous for industrial applications. As described above, the Ti—Ni adhesion layer 3 c according to the present invention can contribute to providing a highly reliable semiconductor light emitting device as an electronic device simply and at low cost.

  The semiconductor light-emitting device of the present invention is manufactured, for example, by the following steps.

That is, the semiconductor light emitting device of the present invention is
(A) forming an insulating film (eg, silicon oxide film) 3b on the surface of a predetermined substrate (eg, silicon substrate) 3a;
(B) forming an adhesion layer 3c made of a Ti—Ni alloy on the insulating film 3b;
(C) forming a barrier metal layer 3d made of Ni, Pt or Pd on the adhesion layer 3c;
(D) forming a reflective layer 3e made of Ag, Al, or an Ag alloy on the barrier metal layer 3d;
(E) electrically connecting the semiconductor light emitting element 4 to the reflective layer 3e;
Can be produced.

  Here, the adhesion layer 3c made of the Ti—Ni alloy is formed by sputtering using a Ti—Ni alloy target, binary simultaneous sputtering using a Ti target and a Ni target, or binary using a Ti vapor deposition material and a Ni vapor deposition material. It can be formed by any method of simultaneous vapor deposition, or alloying by heat treatment after alternately forming Ti film and Ni film using sputtering, vapor deposition, or CVD.

  The barrier metal layer 3d and the reflective layer 3e can be formed by sputtering, vapor deposition, or CVD.

In addition, the step (a) specifically includes, for example,
(A-1) performing anisotropic etching on the silicon substrate 3a to form a horn composed of a bottom surface of the (100) plane and four inclined side surfaces of the (111) plane;
(A-2) forming an insulating film 3b on the surface of the silicon substrate 3a on which the horn is formed;
Can be included.

Alternatively, the step (a) includes, for example,
(A-1) performing anisotropic etching on the silicon substrate 3a to form a horn composed of a bottom surface of the (100) plane and four inclined side surfaces of the (111) plane;
(A-2) a step of isotropically etching the inclined side surface of the horn to round the angle of the horn;
(A-3) forming an insulating film 3b on the surface of the silicon substrate 3a on which the horn is formed;
Can be included.

  Here, the step of forming a horn composed of a bottom surface of (100) plane and four (111) inclined side surfaces is performed by, for example, crystal anisotropic etching of a crystalline silicon substrate with an alkaline solution such as KOH or TMAH. Made by processing. In this case, when the crystalline silicon substrate is subjected to crystal anisotropic etching with an alkaline solution such as KOH or TMAH, the bottom surface parallel to {100} and the parallel to {111} having an angle of 54.7 ° at the bottom surface. A horn composed of four slopes is formed.

  In the present invention, by using a Ti—Ni alloy composed of Ti and Ni in an appropriate composition range as the adhesion layer 3c, the adhesion can be remarkably improved as compared with Ti. In addition, in a semiconductor light-emitting device that originally used Ti as the adhesion layer and Ni as the barrier metal layer, the conventional film-forming apparatus and film-forming materials can be used as they are by means of co-evaporation and co-sputtering techniques. There is no need for additional equipment and materials, which is extremely advantageous for industrial applications. As described above, the Ti—Ni adhesion layer 3 c according to the present invention can contribute to providing a highly reliable semiconductor light emitting device as an electronic device simply and at low cost.

  FIG. 4 shows an LED package on which a semiconductor light emitting element is mounted using a flat submount as an example of the semiconductor light emitting device. As shown in FIG. 4, the silicon submount 3 is die-bonded with silver paste on one lead in the resin housing 1 to which the lead frame 2 having two leads is attached.

  FIG. 5 shows a cross-sectional view of the flat silicon submount 3. A silicon substrate 3 a is used as a base for forming the flat silicon submount 3. The surface of the silicon substrate 3a is flattened by an optical polishing process. First, a silicon oxide film 3b as an insulating film is formed on the entire surface of the silicon substrate 3a by thermal oxidation using a diffusion furnace. Thereby, even if the silicon submount 3 is die-bonded to the lead, the insulation between the silicon submount 3 and the lead is maintained. Next, the metal films 3c, 3d and 3e as described above are stacked on the upper surface of the silicon substrate 3a covered with the silicon oxide film 3b.

  After the silicon submount 3 having the above configuration is die-bonded on one lead, the semiconductor light emitting element 4 is also die-bonded on the silicon submount 3.

  FIG. 6 shows a configuration example of the semiconductor light emitting element 4. The semiconductor light emitting element 4 is a monochromatic LED having a light emission color of red (R), green (G), or blue (B). For example, in the case of red, semiconductor layer aluminum gallium arsenide (AlGaAs) is used. Gallium phosphorus (GaP) is used for green, and gallium nitride (GaN) is used for blue. In the case of red, for example, as shown in FIG. 9, a semiconductor layer 4c is formed on a gallium arsenide (GaAs) substrate 4b. In the semiconductor layer 4c, a p-type semiconductor layer 4d, a light emitting layer 4e, and an n-type semiconductor layer 4f are stacked. Furthermore, metal electrodes 4a and 4g are provided at the bottom and top. In the case of green, for example, GaP or the like is used for the substrate, and as in the case of red, a semiconductor layer is stacked on the GaP substrate, and metal electrodes are provided at the bottom and top. In the case of blue, for example, it has a configuration described in FIG. 1 and paragraphs “0017” to “0023” in Japanese Patent Application No. 2005-167319.

  When the lower electrode of the semiconductor light emitting element 4 having the above configuration is die-bonded to the silicon submount 3, the reflective layer 3e on the silicon submount 3 and the lower part of the semiconductor light emitting element 4 are electrically and mechanically connected. Subsequently, the reflective layer 3e on the silicon submount 3 connected to the lower surface of the semiconductor light emitting element 4 is wire bonded to the lead on the side where the silicon submount 3 is not die-bonded. Then, the electrode on the upper surface of the semiconductor light emitting element 4 and the lead on the side where the silicon submount 3 is die-bonded are wire-bonded. Finally, the resin housing is filled with a transparent or phosphor-containing resin to complete the LED package.

  FIG. 7 shows another configuration example of the LED package. That is, FIG. 7 shows an LED package in which the semiconductor light emitting element 4 is mounted as a silicon submount 3 using a horn type silicon submount. As shown in FIG. 7, the configuration is almost the same as the case of using a flat silicon submount 3 as shown in FIG. A silicon submount 3 with a horn is die-bonded to one lead. Metal films 3c, 3d, and 3e are laminated on the upper surface of the silicon submount 3 including the horn. The semiconductor light emitting element 4 is die-bonded to the bottom of the horn of the silicon submount 3 to electrically and mechanically connect the lower surface of the semiconductor light emitting element 4 and the metal film on the silicon submount 3. Next, the metal film on the surface of the silicon submount 3 electrically connected to the lower surface of the semiconductor light emitting element 4 and the lead on which the silicon submount 3 is not die-bonded are wire-bonded. Subsequently, the upper surface of the semiconductor light emitting element 4 and the lead on which the silicon submount 3 is die-bonded are wire-bonded. Finally, the resin housing is filled with a transparent or phosphor-containing resin to complete the LED package.

  FIG. 8 shows a cross-sectional view of the horn type silicon submount 3. A (100) silicon substrate 3a is used as a base for forming the horn type silicon submount 3. The surface of the silicon substrate 3a is flattened by an optical polishing process. First, the horn 22 is formed on the silicon substrate 3a. A silicon oxide film 3b as an insulating film is formed on the entire surface of the silicon substrate 3a on which the horn 22 is formed by thermal oxidation using a diffusion furnace. Thereby, the insulation between the silicon submount 3 and the lead is maintained even if die-bonded to the lead. Next, metal films 3c, 3d, and 3e are laminated on the upper surface of the silicon substrate 3a covered with the silicon oxide film 3b in the same manner as the flat silicon submount 3 is formed.

  FIG. 9 is a diagram showing an example of a specific manufacturing process of the semiconductor light emitting device of the present invention.

  In this example of the manufacturing process, first, as shown in FIG. 9A, a thermal silicon oxide film 21 having a thickness of 500 nm is formed on the surface of the mirror silicon wafer 3a using a diffusion furnace. Next, a resist pattern is formed by a photolithography technique, and the thermally oxidized silicon film 21 is removed by etching using buffered hydrofluoric acid (BHF), thereby forming a pattern of the silicon oxide film 21 as shown in FIG. To do. Using the patterned silicon oxide film 21 as a mask, a horn 22 as shown in FIG. 9C-1 is produced by crystal anisotropic etching using, for example, a 20% TMAH solution. With respect to the obtained horn 22, the bottom of the horn is protected with an oxide film using resist spray coating, and isotropic etching is performed only on the inclination of the horn with a mixed solution of hydrofluoric acid, nitric acid, and water, for example, as shown in FIG. An elliptical inclined surface as shown in C-2) can also be produced.

  After the horn 22 is fabricated, all of the thermally oxidized silicon film 21 is once removed with a BHF solution, and a 500 nm thick thermally oxidized silicon film 3b is again formed on the silicon substrate surface using a diffusion furnace as shown in FIG. 9D. Is made. Subsequently, a resist is applied by resist spray coating, which is a resist coating technique for forming a three-dimensional shape, and a resist pattern 23 as shown in FIG. 9E is formed on the thermally oxidized silicon film 3b by a photolithography technique.

  Next, a three-layer metal film (3c, 3d, 3e) is formed on the front surface and the back surface of the silicon substrate on which the resist pattern 27 is formed on the silicon oxide film 3b, as shown in FIG. First, a Ti—Ni alloy film is produced as an adhesion layer 3c on the thermally oxidized silicon film 3b. As a method for producing an alloy thin film, (1) binary simultaneous sputtering using a Ti target and Ni target, (2) sputtering using an alloy target, (3) binary simultaneous vapor deposition, (4) sputtering or vapor deposition, or CVD. Techniques such as alloying by heat treatment after alternating film formation of the Ti film and Ni film used can be used. Whichever method is used, the composition and film thickness of the Ti—Ni alloy film can be arbitrarily determined. After forming the Ti—Ni thin film, a Ni, Pt, or Pd film is continuously formed as the barrier metal layer 3d, and an Ag, Al, or Ag alloy film is formed as the reflective layer 3e.

  After forming the reflective layer 3e in this way, subsequently, as shown in FIG. 9G, the three-layer stacked metal films (3c, 3d, 3e) are lifted off, thereby forming the reflective film of the semiconductor light emitting device. An electrode pattern that also serves as an electrode can be produced. Although FIG. 9 shows an example of electrode patterning by the lift-off process, it is of course possible to pattern the electrode by wet etching with an acid / alkali solution or a dry etching process such as RIE.

  As shown in FIG. 10 (H-1), the semiconductor light emitting element 4 (for example, an LED chip) is die-bonded to the silicon substrate on which the electrode pattern has been formed, and then electrically connected by wire bonding 25. Alternatively, as shown in FIG. 10 (H-2), a semiconductor light emitting device can be manufactured by electrically connecting via bumps mounted on a semiconductor light emitting element 4 (for example, an LED chip). I can do it. In particular, a blue semiconductor light emitting element is bonded, and a white semiconductor light emitting device is obtained by sealing the inside of the horn with a transparent resin 26 in which a wavelength conversion material such as a phosphor is dispersed as shown in FIG. .

  Examples of the present invention will be described below.

  In Example 1, a metal film was formed on a planar silicon substrate with an oxide film in order to evaluate the adhesion of a Ti—Ni alloy thin film compared to pure Ti and to examine the optimum composition range of the Ti—Ni alloy. Then, the adhesiveness was evaluated by observing the presence or absence of peeling by dicing into a grid pattern.

  A pure Ti or Ti—Ni thin film was produced as an adhesion layer on a 3 cm square silicon substrate with an oxide film by sputtering with a Ti target alone, or by binary simultaneous sputtering with a Ti target and a Ni target, respectively. The Ti—Ni alloy composition ratio was adjusted by changing the DC output ratio during sputtering. In both cases, the thickness of the adhesion layer is 25 nm, and the argon pressure is 1.0 Pa. A Ni film is formed on the adhesion layer by sputtering to a thickness of 250 nm at an argon pressure of 0.2 Pa and a DC output of 1 kW, and an Ag alloy film is formed to a thickness of 300 nm at an argon pressure of 1.0 Pa and a DC output of 500 W by sputtering. The metal film was produced by forming a film. Ag-Bi-Au was used as the Ag alloy, but it contains at least one of Bi, Au, Pd, Cu, Pt, and Nd, such as Ag-Pd-Cu and Ag-Bi-Nd. Anything is acceptable. A highly reflective metal such as Ag or Al is also preferably used. The silicon substrate with a metal film was diced into a 1 mm square lattice at 5 nm / sec, and the presence or absence of peeling was observed visually or with an optical microscope. Further, the silicon substrate with a metal film was placed on a 300 ° C. hot plate, heated for 300 seconds in the air at room temperature, and then similarly peeled by dicing.

  The results of observation of peeling are shown in the following table (Table 1).

  From Table 1, peeling was observed in the metal film using pure Ti when heated to the atmosphere, whereas the Ti concentration was 25 to 70 at. In the Ti—Ni alloy film in the range of%, no peeling was observed, and the adhesion was improved. If the Ti concentration in the Ti-Ni alloy is too small, the adhesion is lowered, and if too much, the adhesion is lowered.

  In Example 2, in order to examine the optimum film thickness of the Ti—Ni alloy film, adhesion evaluation by dicing was performed using the same method as in Example 1.

  A Ti—Ni thin film as an adhesion layer was formed on a 3 cm square silicon substrate with an oxide film by a dual simultaneous sputtering using a Ti target and a Ni target. The thickness of the adhesion layer was 10 to 25 nm. The Ti concentration in the Ti—Ni alloy is 32 at. %, The argon pressure is 1.0 Pa. On top of the adhesion layer, a Ni film is formed by sputtering to a thickness of 250 nm at an argon pressure of 0.2 Pa and a DC output of 1 kW, and an Ag film is formed to a thickness of 300 nm at an argon pressure of 1.0 Pa and a DC output of 500 W, respectively. The metal film was produced by forming a film. The silicon substrate with a metal film was diced into a 1 mm square lattice at 5 nm / sec, and the presence or absence of peeling was observed visually or with an optical microscope. Further, the silicon substrate with a metal film was placed on a 300 ° C. hot plate, heated for 300 seconds in the air at room temperature, and then similarly peeled by dicing.

  The results of observation of peeling are shown in the following table (Table 2).

  From Table 2, peeling was seen when the film thickness of Ti—Ni was as thin as 10 nm. Therefore, it is considered that the film thickness in the range of 15 nm to 2000 nm is desirable when Ti—Ni is used as the adhesion layer.

  That is, even if the Ti—Ni film thickness was 2000 nm, no significant change was observed in the reflectance characteristics compared to the case of 20 nm. If the barrier metal layer is formed, the adhesion layer has a thickness of 15 to 2000 nm, particularly 20 to 300 nm. It is done.

  In the above example, the barrier metal layer made of the Ni film is provided on the adhesion layer (Ti—Ni alloy), but the Ag alloy reflection layer is provided on the adhesion layer (Ti—Ni alloy) without providing the Ni film. Even in this case, the result of the peeling observation is the same. That is, instead of providing the Ni barrier metal layer separately from the adhesion layer (Ti—Ni alloy), it can also be an adhesion layer / barrier metal layer made of Ti—Ni alloy. In this case, it is made of Ti—Ni alloy. A reflection layer is formed on the adhesion layer / barrier metal layer.

Thus, according to the present invention, the following was confirmed. That is,
(1) By using a Ti—Ni alloy film instead of the Ti film as the metal film adhesion layer 3c, the adhesion with the insulating film (specifically, for example, a silicon oxide film) 3b is improved. The Ti concentration of the Ti—Ni alloy film is 25 at. % To 70 at. %, And the film thickness is preferably in the range of 15 nm to 2000 nm.
(2) Since the adhesion layer 3c is formed using Ti and Ni used in the conventional structure of the metal film, it is not necessary to introduce new equipment, and it is not necessary to introduce a new target and vapor deposition material (alloy sputtering method). When using, a new alloy target is required). As a result, the adhesiveness can be remarkably improved without adding a process compared to the conventional case.

  The case where the reflective layer 3e is formed of an Ag alloy layer will be described in detail. Note that an Ag-Bi alloy is used as the Ag alloy.

  First, an endurance test was performed on two types of samples, Ag-Bi (0.07 atomic%, 0.14 atomic%)-Nd (neodymium) film (film thickness: 0.1 μm). In both samples, the Nd content is 0.2 atomic% and Ag is 99 atomic% or more. The measurement was performed using an n & k analyzer manufactured by n & k Technology, Inc. (US), and the patented n & k method (AR Furouhi and I. Bloomer, Method and Apparatus for Measuring Optical Constants of Materials. U.S. 4). , 905, 170; 1990).

  FIG. 11A shows the vertical reflectance after the lapse of time of Ag-Bi (0.07 atomic%)-Nd, and FIG. 11B shows the vertical reflectance after the lapse of time of Ag-Bi (0.14 atomic%)-Nd. . As shown to FIG. 11A and FIG. 11B, it turned out that durability is so good that the content rate of Bi contained in Ag is large.

  In order to derive a preferable content of Bi, the following experiment was performed. On the glass substrate, the following five types of films were formed by sputtering while changing the target material. In all samples, the film thickness was 0.1 μm.

Sample A Ag—Bi—Nd alloy film (Bi atomic% = 0.07)
Sample B Ag—Bi—Nd alloy film (Bi atomic% = 0.14)
Sample C Ti / Ag—Bi—Nd alloy film (Bi atomic% = 0.14, Ti film thickness: 0.05 μm)
Sample D Ti / Ag—Bi—Nd alloy film (Bi atomic% = 0.22, Ti film thickness: 0.05 μm)
Sample E Ti / Ag—Bi—Nd alloy film (Bi atomic% = 0.24, Ti film thickness: 0.05 μm)
The initial vertical reflectivity of each of the five samples was measured using an n & k analyzer.

  FIG. 12 shows a graph representing the initial vertical reflectance of the sample. As shown in FIG. 12, as the Bi content increases, the initial vertical reflectance deteriorates. It has been found that the Bi content is preferably 0.14 atomic% or less for use as a reflective film.

  As a result of the above two experiments, when the Bi content is greater than 0.07 atomic% and within a range of 0.14 atomic% or less, the practical initial reflectance as an LED package is set to a high level and durability is ensured. It turns out that you can. As the silver alloy layer in the semiconductor light emitting device, it is considered that the Bi content is preferably in the range of 0.05 to 0.15 atomic%.

  One or more of Au, Pd, Pt, and Cu (copper) are added as additive elements to the Ag—Bi alloy. The total addition amount is preferably 0.5 to 5.0 atomic%, more preferably 1.0 to 2.0 atomic%. Further, a rare earth element may be added as an additive element. For example, when Nd is added, the addition amount is preferably 0.1 to 1.0 atomic%. More preferably, the content is 0.1 to 0.5 atomic%. This is because the initial reflectivity and the electrical resistivity are lowered when the amount is larger than these addition amounts. In the Ag-Bi alloy containing Bi in the above preferred range, it is better to add at least one of Au, Pd, Cu, Pt, and Nd with an atomic percentage higher than the atomic percentage of the Bi addition amount. A favorable trend was shown. Note that the Ag content in the above-described Ag alloy is 94% or more in atomic%.

  FIG. 13 is a graph showing the dependence of the reflectance of the deposited Ag—Bi alloy on the pressure of the atmosphere during film formation. FIG. 13 shows an example in which Ag—Bi—Au (thickness: 0.1 μm) is formed on a silicon substrate. The vertical axis represents reflectance and the horizontal axis represents light wavelength. When the atmosphere during film formation is 0.5 Pa, the reflectance in the visible region is close to 100%, whereas in the case of 1 Pa, the reflectance decreases as the wavelength becomes shorter even in the visible region. Therefore, it is desirable that the pressure of the atmosphere during film formation is lower than at least 1 Pa.

  Under the above conditions, an Ag alloy is formed as the reflective layer. The film thickness is preferably 0.1 to 0.6 μm.

  Next, the thickness range of the barrier metal layer and the film forming conditions will be described. For example, when Ni is used as the barrier metal layer, the thickness of Ni is preferably a thickness that can achieve both the function of preventing the diffusion of solder used in die bonding and the maintenance of the high reflectivity of the Ag-Bi alloy.

In order to investigate the minimum film thickness necessary for preventing the diffusion of solder, the following experiment was conducted. First, the following were sequentially formed on a silicon wafer with a silicon oxide film. In the following, for convenience of explanation, it is assumed that the adhesion layer is formed of Ti.
Ti (thickness 0.1 μm) / Ni (thickness 0.5 μm) / Ag—Bi—Nd (thickness 0.1 μm)
And after potting Ag-Sn-Cu lead-free solder on the above film, the lead-free solder is melted by using a reflow furnace. At this time, how deep the lead-free solder is with respect to Ni as a barrier layer. It was observed by a secondary ion mass spectrometer (SIMS) whether it was diffused.

  As a result, it was found that the diffusion distance was about 0.5 μm. Therefore, the thickness of the Ni layer is preferably 0.5 μm or more.

  Further, when a similar experiment was performed on Au—Sn eutectic solder, it was found that the Ni layer had a thickness of 0.1 μm or more.

  Next, in order to investigate the range of film thickness for maintaining high reflectance, the following experiment was conducted. On the silicon wafer with the silicon oxide film, the following metal films were formed for each of three types of Ni film thickness, and the vertical reflectance was measured using an n & k analyzer.

Sample: Ti (thickness 0.1 μm) / Ni (thickness 0.1 μm, 0.5 μm, 2 μm) / Ag-Bi-Nd (thickness 0.1 μm)
FIG. 14 is a graph showing the reflectance of the metal film. As shown in FIG. 14, the reflectance hardly changed when Ni was 0.1 μm and 0.5 μm, but the reflectance was lowered when Ni was 2 μm.

  When an LED that emits red or green is used as the LED chip, the Ni film thickness may be 2 μm. However, in consideration of use in a short wavelength region, it has been found that it is preferably thinner than 2 μm.

  From the above experiment, it was found that the preferable thickness range of the Ni layer was 0.1 to 2 μm.

  Subsequently, the conditions of the atmospheric pressure when forming the Ni layer will be described. The following experiment was conducted to examine the conditions.

  The following metal film was formed by sputtering on a silicon wafer with a silicon oxide film. At that time, the film was formed in two cases where the pressure of argon, which is the film forming condition of Ni, was 0.2 Pa and 1.0 Pa. The vertical reflectance of this sample was measured using an n & k analyzer.

Sample: Ti (film thickness 0.1 μm) / Ni (film thickness 0.2 μm) / Ag—Bi—Au (film thickness 0.1 μm)
FIG. 15 shows a graph representing the vertical reflectance of the sample. For comparison, pure Ag vertical reflectivity data is also shown. As shown in FIG. 15, when the argon pressure was 0.2 Pa, the formed film had substantially the same reflectance as that of pure Ag. Further, even when the argon pressure is 1 Pa, the reflectance of 400 nm or less decreases, but it can be seen that if the wavelength is in the range of 450 nm to 1000 nm, the reflectance is 90% or more and it can be used as a reflective curtain. Therefore, the preferable range of the argon pressure during Ni film formation is 0.2 to 1 Pa.

  The barrier metal layer thus formed improves the reliability of the Ag alloy layer as the reflective layer under high temperature and high humidity. In order to confirm the effect, a film in which Ti (0.05 μm) / Ag—Bi—Nd (0.1 μm) is laminated on a silicon substrate, and Ti (0.05 μm) / Ni (2 μm) / Ag—Bi Two kinds of films in which —Nd (0.1 μm) was laminated were formed. And it left to stand under 60 degreeC90RH%, and measured the relationship between leaving time and a reflectance.

  FIG. 16 shows the reflectance of the Ag alloy formed under the above film forming conditions. Immediately after the start of measurement, the reflectivity was 95% or more in the wavelength range of 500 to 1000 nm, but after that, the film without the Ni layer decreased to about 70% after 360 hours. On the other hand, the film having the Ni layer maintained a reflectance of 90% or more even after 1000 hours.

  Subsequently, the thickness range of the adhesion layer and the film forming conditions will be described. For example, Ti is used as the adhesion layer. In order to examine the thickness of Ti for preventing the barrier metal (Ni) layer and the Ag alloy layer from peeling from the silicon substrate, the following experiment was conducted.

First, the following metal film was sputter-deposited on a silicon wafer with a silicon oxide film by setting the atmospheric pressure during Ti film formation to two types of 0.5 Pa and 1 Pa. Then, a peel test was performed on each sample using a scotch tape.
Ti (0.05 μm) / Ni (0.5 μm) / Ag-Bi-Nd (0.1 μm)
When the atmospheric pressure at the time of forming the Ti layer was 0.5 Pa, the metal film was peeled off, but at 1 Pa, it was not peeled off.

  Next, a peeling experiment was performed by changing the thickness of the Ni layer of the metal film to 2 μm while setting the atmospheric pressure during Ti film formation to 1 Pa. As a result, the metal film was peeled off.

  Therefore, when a peeling experiment was performed with a Ti film thickness of 0.1 μm, the metal film did not peel off.

  From the above results, it was found that the thickness of the Ti adhesion layer is 0.05 μm or more, and the pressure during sputtering film formation is preferably larger than 0.5 Pa. Furthermore, considering the surface roughness, the pressure is preferably 1 Pa or less.

  As described above, as a result of developing the barrier metal layer and the adhesion layer for maintaining high reflectivity as a reflective film without peeling off the film by bonding at the time of die bonding, Ag-Bi excellent as a reflective film It has become possible to use a base alloy as an electrode and reflection film for die bonding of a semiconductor light emitting device. As a result, a silicon package having 30 to 50% higher light extraction efficiency than the conventional LED package could be realized. Since this package has good thermal conductivity in addition to high reflectivity, it exhibits excellent characteristics as a power LED package exceeding 1 W. Moreover, by introducing a barrier metal layer and an adhesion layer that promote high durability of the Ag-Bi alloy, it has become possible to supply an LED package that is extremely practically stable and does not deteriorate the reflective film due to aging.

  The LED package manufactured according to the present invention can be used as various light emitting devices, for example, as shown in FIG. That is, in FIG. 17, the LED package produced for the LED light emitter 31 is used, and the power supply to the LED package is controlled by the switch 32. With the handle 33, the LED light emitter 31 can be directed in a desired direction.

  As mentioned above, although this invention was demonstrated, this invention is not restrict | limited to these.

  For example, the reflective layer 3e is divided into a plurality of regions and these are referred to as reflective portions. Then, by electrically connecting each region of the reflective portion to the semiconductor light emitting element 4, for example, a semiconductor light emitting device of RGB mixed colors can be produced.

  Further, the semiconductor light emitting element 4 is not limited to being mounted on the reflective layer 3e. For example, a form in which the semiconductor light emitting element 4 is mounted on an insulating material and connected to a peripheral electrode by a wire is also possible. . That is, in the above description, the reflective layer 3e has a function as a reflective film and electrode, but may have only a function as a reflective film.

  Furthermore, when the horn is formed on the silicon substrate 3a, the process of rounding the corners of the horn has been described. However, a horn having no roundness is also a practical form.

Further, as shown in FIG. 18, a Ti coat layer 3f having a thickness smaller than that of the reflective layer 3e may be formed on the reflective layer 3e. Here, the Ti coat layer 3f is formed of Ti, but a thin film thickness in which Ti is oxidized, nitrided, or carbonized in a part thereof is also included in the Ti coat layer 3f. That, Ti coating layer 3f are either those formed by Ti, or, Ti and oxygen, nitrogen, at least one of Ti compound of carbon (e.g., such as TiO _x or _TiO x _{N y)} Ti It is included in a part of

  The Ti coat layer 3f is specifically a thin film having a thickness of about 0.35 nm to 2 nm.

  As described above, since the Ti coat layer 3f is thinner than the reflective layer 3e, the Ti coat layer 3f affects the reflectance of the reflective layer 3e with respect to light from the semiconductor light emitting element 4. (That is, the light transmittance of the Ti coat layer 3f can be kept high, the reflectance of the reflective layer 3e with respect to the light from the semiconductor light emitting element 4 is not lowered), and the electrode has high conductivity (small resistance). In addition, the Ti coating layer 3f is provided, whereby the surface of the reflective layer 3e can be protected. That is, the Ti coat layer 3f functions as a surface protective layer that prevents a decrease in the reflectance of the reflective layer 3e due to sulfurization or heat. More specifically, when Ag or an Ag alloy is used as the material of the reflective layer 3e, when the Ti coat layer 3f is not provided, the reflectance of the Ag or Ag alloy decreases due to sulfidation, heat, etc. By using the coat layer 3f, it is possible to prevent a decrease in reflectance due to sulfurization or heat of Ag or an Ag alloy. In addition, when Al is used as the material of the reflective layer 3e, the Al has less decrease in reflectance due to sulfidation or heat compared to Ag, but nevertheless, by using the Ti coat layer 3f, Al sulfidation or heat It is possible to prevent a decrease in reflectance due to the above.

  In the configuration example of FIG. 18, the Ti coat layer 3 f and the reflective layer 3 e can be electrically connected to the semiconductor light emitting element 4, and the reflective layer 3 e functions as a reflective film and electrode for the semiconductor light emitting element 4. be able to. Specifically, for example, the semiconductor light emitting element 4 can be electrically connected to the reflective layer 3e via the Ti coat layer 3f (the semiconductor light emitting element 4 is bonded to the Ti coat layer 3f (wire bonding, die bonding, etc.). (As a specific example, a semiconductor light emitting device having a back electrode can be directly die-bonded to the Ti coat layer 3f)), or a part of the Ti coat layer 3f, for example It is also possible to provide a structure in which the semiconductor light emitting element 4 is directly wire-bonded to the reflective layer 3e (a structure in which the semiconductor light-emitting element 4 is directly electrically connected to the reflective layer 3e), for example, by providing an opening.

  It will be apparent to those skilled in the art that other various modifications, improvements, combinations, and the like can be made.

The present invention includes a single color LED, a phosphor-excited white LED (general illumination, strobe, backlight, etc.), an RGB mixed color white LED, a dimming circuit mounted LED, a light receiving / emitting integrated photo sensor, a photo interrupter, a photo coupler, etc. Is available.

It is a figure which shows the graph showing the reflectance with respect to the wavelength of the light of various metals. It is a figure which shows the structural example of the semiconductor light-emitting device based on this invention. It is a figure which shows the more specific structural example of the semiconductor light-emitting device concerning this invention. It is a figure which shows the LED package which mounted the LED chip using the flat submount. It is sectional drawing of the silicon submount of FIG. It is a figure which shows the structural example of a semiconductor light-emitting device. It is a figure which shows the LED package which mounted the LED chip using the submount with a horn. It is sectional drawing of the silicon submount of FIG. It is a figure which shows the example of a manufacturing process of the semiconductor light-emitting device concerning this invention. It is a figure which shows the example of a manufacturing process of the semiconductor light-emitting device concerning this invention. A is a graph showing the vertical reflectance after the lapse of time of Ag-Bi (0.07 atomic%)-Nd, and B is the vertical reflectance after the lapse of time of Ag-Bi (0.14 atomic%)-Nd. FIG. It is a figure which shows the graph showing the initial stage vertical reflectance of five types of Ag-Bi type alloy samples. It is a figure showing the dependency of the reflectance of an Ag-Bi system alloy to the pressure of the atmosphere at the time of film formation. It is a figure which shows the graph showing the reflectance of three types of samples. It is a figure which shows the graph showing the vertical reflectivity of two types of samples. It is a figure which shows the reflectance of Ag alloy formed into a film on the predetermined film-forming conditions. It is a figure which shows the usage example of a LED package. It is a figure which shows the other specific structural example of the semiconductor light-emitting device concerning this invention.

Explanation of symbols

3a Substrate 3b Insulating film 3c Adhesion layer 3d Barrier metal layer 3e Reflective layer 3f Ti coat layer 4 Semiconductor light emitting element 22 Horn

Claims (10)

An insulating film formed on the surface of a predetermined substrate;
A metal layer formed on the insulating film;
A semiconductor light emitting device,
The metal layer is provided with an adhesion layer for adhesion to the insulating film, and a reflective layer above the adhesion layer,
The reflective layer has a function as a reflective surface for the light emitted from the semiconductor light emitting element,
The adhesion layer is formed of a Ti—Ni alloy. 2. The semiconductor light emitting device according to claim 1, wherein the adhesion layer formed of the Ti-Ni alloy has a Ti concentration range of 25 to 70 at. %, A semiconductor light emitting device. 3. The semiconductor light emitting device according to claim 1, wherein the reflective layer is made of a material having a reflectance higher than that of the adhesion layer with respect to light emitted from the semiconductor light emitting element. 4. The semiconductor light emitting device according to claim 3, wherein the metal layer is provided with a barrier metal layer on the adhesion layer, the reflective layer is provided on the barrier metal layer, and the barrier metal layer includes Ni, Pt. Or a semiconductor light emitting device formed of Pd. 5. The semiconductor light emitting device according to claim 4, wherein the adhesion layer formed of the Ti-Ni alloy has a thickness in the range of 15 nm to 2000 nm. 5. The semiconductor light emitting device according to claim 1, wherein the reflective layer is made of Ag, Al, or an Ag alloy. 7. The semiconductor light emitting device according to claim 6, wherein the Ag alloy is an alloy containing at least one of Bi, Au, Pd, Cu, Pt, and Nd. (A) forming an insulating film on the surface of the silicon substrate;
(B) forming an adhesion layer made of a Ti-Ni alloy as a material on the insulating film;
(C) forming a barrier metal layer made of Ni, Pt or Pd on the adhesion layer;
(D) forming a reflective layer made of Ag, Al, or an Ag alloy on the barrier metal layer;
(E) electrically connecting a semiconductor light emitting element to the reflective layer;
A method of manufacturing a semiconductor light emitting device, comprising: 9. The method of manufacturing a semiconductor light-emitting device according to claim 8, wherein the adhesion layer made of the Ti-Ni alloy is formed by sputtering with a Ti-Ni alloy target, or dual simultaneous sputtering with a Ti target and a Ni target, or Ti. Forming by either simultaneous vapor deposition using vapor deposition material and Ni vapor deposition material, or alloying by heat treatment after alternating deposition of Ti film and Ni film using sputtering, vapor deposition, or CVD A method for manufacturing a semiconductor light emitting device. 9. The method of manufacturing a semiconductor light emitting device according to claim 8, wherein the step (a) includes:
(A-1) forming a horn composed of a bottom surface of (100) plane and four inclined sides of (111) plane by performing anisotropic etching on the silicon substrate;
(A-2) forming an insulating film on the silicon substrate surface on which the horn is formed;
A method of manufacturing a semiconductor light emitting device, comprising:

Images