JP2007157805A - Led package, method of manufacturing light-emitting device and led package - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To manufacture an LED package having light distribution characteristics without any dark lines originating from a ridgeline formed by a (111) plane of a sloped side of a horn. <P>SOLUTION: Anisotropic etching depending on orientation is performed to a silicon substrate whose surface is a (100) plane, thus forming the horn with the (100) plane as a bottom surface and four (111) planes as sloped sides. Irregularities are formed on the sloped sides of the formed horn. An LED chip is packaged on the bottom surface of the horn. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an LED package, a light emitting device, and an LED package manufacturing method, and more particularly to an LED package in which an LED chip is mounted on a horn formed on a silicon substrate, a light emitting device, and an LED package manufacturing method.

  In recent years, LED packages having a configuration disclosed in, for example, Patent Document 1 below are known. In Patent Document 1, a silicon substrate is anisotropically etched to form a depression called a horn having a (100) bottom surface and a (111) inclined side surface, and a blue LED chip is disposed on the horn bottom surface. A reflective film is formed on the horn slope to improve external light extraction efficiency.

JP 2004-356213 A

  In the LED package according to Patent Document 1, there is a ridge line at the boundary between the surfaces of the horn slope, and there is a problem that a shadow of the ridge line is generated during light emission.

  The objective of this invention is providing the LED package which eliminated the shadow of the ridgeline, and improved the light distribution characteristic, and an LED package manufacturing method.

  According to one aspect of the present invention, a silicon substrate having a (100) plane surface is subjected to anisotropic etching depending on the plane orientation, and the (100) plane is a bottom surface and four (111) planes are inclined. There is provided an LED package manufacturing method including a step of forming a horn as a side surface, a step of forming irregularities on an inclined side surface of the horn, and a step of mounting an LED chip on the bottom surface of the horn.

  According to another aspect of the present invention, a horn composed of a bottom surface of the (100) plane and four inclined sides of the (111) plane is formed by anisotropic etching, and irregularities are formed on the four (111) planes. An LED package including the formed silicon substrate and an LED chip mounted on the bottom surface of the horn is provided.

  A voltage is applied from an external power source to the LED chip mounted in the horn, the LED emits light, and light is extracted outside the horn. Conventionally, a dark line derived from a ridge line existing at the boundary between the surfaces of the inclined side surface of the horn was seen. Luminescence without light can be obtained.

  With reference to FIG. 1 and FIG. 2, the manufacturing method of the LED package by the Example of this application is demonstrated.

  FIG. 1 shows a part of the manufacturing process of the LED package. A single crystal silicon substrate 11 having a thickness of 525 μm is used as a base for mounting the LED chip. The surface of the single crystal silicon substrate 11 is flattened by an optical polishing process.

  First, as shown in FIG. 1A, a silicon oxide film 21 having a thickness of 500 nm is formed on the surface of the (100) silicon substrate 11 by thermal oxidation using, for example, a diffusion furnace.

  Next, as shown in FIG. 1B, a rectangular resist pattern 22 having sides in the [110] direction is formed on the silicon oxide film 21 by photolithography, and then oxidized by buffered hydrofluoric acid (BHF). The silicon film 21 is partially etched away to form a silicon oxide film pattern 21a provided with openings H.

  Thereafter, as shown in FIG. 1C-1, the resist pattern 22 is removed, and a 25% tetramethylammonium hydroxide (hereinafter, TMAH) solution is applied to the silicon substrate 11 using the silicon oxide film pattern 21 a as a mask. To perform anisotropic etching. In this embodiment, the surface of the silicon substrate 11 is a (100) plane, and a horn 11a is formed in the silicon substrate 11 by performing anisotropic etching. The horn 11a has a trapezoidal vertical cross section and a quadrangular horizontal cross section. That is, it consists of a bottom surface that is the (100) plane and four inclined side surfaces that are the (111) plane. The inclined side surface that is the (111) plane has an inclination angle of 54.7 ° with respect to the bottom surface that is the (100) plane.

  At this time, as shown in the plan view of FIG. 1C-2, the horn 11a has ridge lines at the boundaries between the four inclined side surfaces.

  Next, as shown in FIG. 1D, the silicon oxide film 21 and the silicon oxide film pattern 21a are once removed, and a silicon oxide film 23 is formed on the entire surface of the silicon substrate 11 by thermal oxidation again.

  Thereafter, as shown in FIG. 1E, a resist pattern 24 is formed on the (100) plane. First, the resist pattern 24 is formed once by a resist spray coating that can apply a resist having a uniform thickness almost the same as that of a normal photolithography process even in a three-dimensional shape having a step of several hundred μm like a horn. Apply resist over the entire surface. Then, pattern exposure is performed with a mask aligner, and the resist on the horn inclined side surface is removed by development processing.

  Next, a portion of the silicon oxide film 23b where the resist pattern 24 is not formed is removed using a buffered hydrofluoric acid (hereinafter referred to as BHF) solution. Then, when the resist pattern 24 is removed by the remover liquid, the hard mask of the silicon oxide film 23a remains on the (100) surface of the silicon substrate 11 as shown in FIG. Note that the silicon oxide film is left on the inclined side surface in the vicinity of the bottom surface in consideration of the overetching of the anisotropic etching performed thereafter.

  Next, a process is performed on the inclined side surface of the horn 11a to make the inclined side surface an uneven diffuse reflection surface. There are two methods for this process, which will be described in order here.

  As a first method, anisotropic etching using, for example, a 5% TMAH solution as an etchant is performed under different conditions from the anisotropic etching performed by forming the horn 11a using the silicon oxide film 23a as a hard mask. There is. By this method, as shown in FIG. 1 (G-1), the horn 11b having an inclined side surface that is an uneven surface having a dimple shape is formed. Here, the dimple is a group of irregularities formed by a smooth curve. The surface roughness of the concavo-convex surface can be adjusted by etching conditions, and is usually set to 0.1 to 1 μm. Due to the formed irregularities, the inclined side surface of the horn 11b becomes a diffuse reflection surface.

  As a second method, there is a method of performing blasting such as sand blasting or dry ice blasting in a state where the (100) surface is protected by a thick film resist further patterned on the silicon oxide film 23a. By this method, rough irregularities are formed on the inclined side surface of the horn. The rough uneven surface is different in surface roughness from the dimple-shaped uneven surface formed by the first method, but the effect is the same diffuse reflection surface.

  An LED chip is mounted on the horn 11b formed by the above method. The process is shown in FIG. As shown in FIG. 2A, after all the silicon oxide film (including the thick film resist in the case of the second method) is once removed, the silicon oxide film is again formed on the surface of the silicon substrate 11 by thermal oxidation. 24 is formed.

  Next, as shown in FIG. 2B, a barrier layer 25 made of Ti, Cu, Ni, Pt or the like is formed on the silicon oxide film 24 on the surface of the silicon substrate 11 by a film forming method such as sputtering. Is deposited.

  Subsequently, a reflective film such as Ag, Au, or Al is formed on the barrier layer 25. Further, a resist pattern 27 having stripe-shaped slits is formed on the reflective film. By performing selective etching of the barrier layer 25, which is a metal layer, and the reflective film using the resist pattern 27 as a mask, as shown in FIG. 2C, the patterned barrier layers 25a and 25b and the reflective film / electrode 26a are formed. 26b is formed.

  As a patterning method, a resist pattern is formed on the silicon oxide film 24, a barrier layer and a reflective film are formed thereon, and finally a barrier layer and a reflective layer laminated on the resist are formed. A technique called “lift-off” may be used in which the film is removed together with the resist pattern and the barrier layer and the reflective film are patterned.

  Next, as shown in FIG. 2D, the lower electrode of the LED chip 31 is die-bonded to the chip mounting portion 26c of the reflective film / electrode 26a defined on the bottom surface of the horn. The LED chip 31 is a single color LED having an emission color of red (R), green (G), or blue (B). For example, in the case of red, aluminum gallium arsenide (AlGaAs) is used for the semiconductor layer. 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. 3, a semiconductor layer 31c (a p-type semiconductor layer 31d, a light-emitting layer 31e, and an n-type semiconductor layer 31f are stacked in this order) is stacked on a gallium arsenide (GaAs) substrate 31b. The metal electrodes 31a and 31g 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 the structure described in FIG. 1 and paragraphs [0017] to [0023] in Japanese Patent Application No. 2005-167319. When the lower electrode of the LED chip 31 having such a configuration is die-bonded, the reflective film cum electrode 26a and the LED chip 31 are electrically and mechanically bonded by Au—Sn eutectic bonding.

  Further, the upper electrode of the LED chip 31 and the connecting portion 26d of the reflective film / electrode 26b are wire-bonded by a bonding wire 31w such as Au and are electrically joined. The reflective film and electrodes 26a and 26b extend from the bottom of the horn 11b to the surface of the silicon substrate 11 via the inclined side surface.

  Next, as shown in FIG. 2E-1, the inside of the horn 11 b is molded with a transparent resin 40. Thus, the LED package is completed. When viewed from above, it is as shown in FIG. Moreover, an LED package with an optical lens can also be created by placing an optical lens of a size that encloses a horn opening prepared in advance on the top of the horn before the resin is cured.

  When evaluating the light distribution pattern of the light emitted by feeding the completed LED package, since the inclined side surface of the horn 11b is a diffuse reflection surface, the dark line derived from the ridge line is not observed, and the light distribution characteristic is conventional. More uniform.

  In addition, when forming the diffuse reflection surface, a protective film such as a silicon oxide film 23a or a thick film resist is provided on the bottom surface of the horn to protect the bottom surface, thereby maintaining a flat state in which the difference in unevenness on the bottom surface is ± 10 nm or less. , Au—Sn eutectic bonding can be performed with sufficient bonding strength. When there is no protective film, the difference in the irregularities on the bottom surface becomes ± several μm or more, and the reliability of the Au—Sn eutectic bond is remarkably lowered.

  With reference to FIGS. 4 and 5, another configuration example of the LED package will be described.

  In the above-described embodiment, there is a form of an LED package on which LED chips having three types of RGB emission colors are mounted. The horn is formed in the same manner as in the above embodiment, and the reflective film and electrode are patterned so that three LED chips are mounted.

  As an arrangement method of the three types of LED chips 32a, 32b, 32c, as shown in FIG. 4 (A), the reflective film / electrode is divided into four as 27a-27d, and the bottom of 27a, 27b, 27c is formed. There is a method of mounting the LED chips 32a, 32b, and 32c one by one and mounting them in series. That is, the lower electrodes of the LED chips 32a, 32b, and 32c are die-bonded to the bottoms of the reflective film and electrodes 27a, 27b, and 27c, respectively, and are electrically and mechanically bonded. Next, the upper electrodes of the LED chips 32a, 32b, and 32c are electrically connected by wire bonding to the bottoms of the reflective film and electrodes 27b, 27c, and 27d, respectively. The reflective film and electrodes 27a and 27d are connected to an external power source, and a circuit is formed so that a forward bias is applied to the LED chips 32a, 32b, and 32c. Similar to the first or second embodiment, a resin is molded into a horn on which an LED chip is mounted to complete an LED package.

  By simultaneously supplying power to the three LED chips 32a, 32b, and 32c, white light emission as a mixed color of RGB light emission can be obtained. It is possible to supply a white LED light-emitting device with high external light extraction efficiency with little loss of absorption and scattering due to the wavelength conversion material.

  As another arrangement method of the three types of LED chips, as shown in FIG. 4B, one of the reflective film / electrodes 28a to 28d divided into four is connected to the ground. Three LED chips 33a, 33b, 33c are arranged on the reflective film / electrode 28a on the bottom surface of the horn, and the electrodes on the bottom surfaces of the LED chips 33a, 33b, 33c and the reflective film / electrode 28a are machined by die bonding or the like. Connect electrically.

  The electrodes on the upper portions of the three LED chips 33a, 33b, and 33c are connected to the reflective film and electrodes 28b, 28c, and 28d by wire bonding. Similar to the first or second embodiment, a resin is molded into a horn on which an LED chip is mounted to complete an LED package.

Voltages V ₁ , V ₂ , and V ₃ are applied to the reflective film / electrodes 28b, 28c, and 28d, respectively, and power is supplied to the three LED chips 33a, 33b, and 33c having different operating voltages. Can do. Even in such LED chip mounting form, white light emission with high external light extraction efficiency as a mixed color of RGB light emission with little loss of absorption and scattering by the wavelength conversion material can be obtained. In addition, since voltage can be applied to each of RGB independently, selective emission of various emission colors is possible by combining these LEDs.

  FIG. 5 is a cross-sectional view showing another mounting example of the LED chip. The same components as those in the previous embodiment are denoted by the same reference numerals, and description thereof is omitted. When a GaN-based LED is formed on an insulating substrate such as sapphire, it is not easy to form one electrode on the bottom surface of the LED chip. Therefore, as shown in FIG. 5A, the LED chip 34 is mounted on the bottom surface of the horn 11b of the silicon substrate 11. The LED chip 34 includes a GaN-based semiconductor in which an n-type semiconductor layer 34b, a light-emitting layer 34c, and a p-type semiconductor layer 34d are sequentially stacked on a substrate 34a, and a p-type semiconductor layer 34d on the surface thereof. In addition to the electrode 34f, an exposed surface is formed so that a part of the n-type semiconductor layer 34b is exposed from the p-type semiconductor layer 34d side, and an n-type electrode 35e is provided on the exposed surface.

  The LED chip 34 is fixed to the silicon substrate 11 so that the translucent substrate 34 a is interposed between the n-type semiconductor layer 34 b and the silicon substrate 11 covered with the silicon oxide film 24. Further, the reflective film and electrodes 26a, 26b, the p-type electrode 34f, and the n-type electrode 34e formed from the inclined side surface of the horn 11b to the upper surface of the silicon substrate 11 are electrically connected by bonding wires 34w. The wire bonding portion may be the inclined side surface of the horn 11b.

  FIG. 5B is a cross-sectional view illustrating still another mounting example of the LED chip. Similar to the mounting example shown in FIG. 5A, the same reference numerals are given to the same components as those in the previous embodiment, and the description thereof is omitted. The LED package shown in FIG. 5B is formed so as to include chip mounting portions 26c and 26e on the bottom surface of the horn 11b, in which the reflective film and electrodes 26a and 26b are abutted with each other with a gap therebetween. On these chip mounting portions 26c and 26e, a so-called flip chip type LED chip 35 is mounted and electrically connected so as to place electrode portions provided on both side edges of the lower surface thereof.

  Also in the LED package as shown in FIG. 5, the same effects as those of the above-described embodiment can be obtained.

  As described above, the (111) plane of the silicon substrate 11 having the horn composed of the (100) bottom surface and the four (111) inclined side surfaces is a diffusive reflective surface having irregularities, so that there is no dark line derived from the ridge line. Luminescence can be obtained.

  The LED package manufactured by such a method can be used as various light emitting devices, for example, as shown in FIG. The LED package produced for the LED light emitter 51 is used, and the power supply to the LED package is controlled by the switch 52. The LED emitter 51 can be directed in a desired direction with the handle 53.

  Although the present invention has been described with reference to the embodiments, the present invention is not limited thereto.

  For example, a potassium hydroxide solution or the like may be used as an etchant for anisotropic etching for forming the horn 11a.

  As a form of the LED package, as shown in FIG. 7, the reflective film and electrodes 26a and 26b may extend to the back surface of the silicon substrate. The extended reflection film and electrodes 26a and 26b serve as electrode pads and are mounted on an electronic circuit or the like.

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

(A)-(G-2) are sectional drawing and top view which show the manufacturing process which forms a horn without a ridgeline in a silicon substrate. (A)-(E-2) are sectional drawing and top view which show the manufacturing process of the LED package which mounted the LED chip on the single crystal silicon substrate in which the horn without a ridgeline was formed. It is sectional drawing which showed the structural example of the LED chip. (A), (B) is the top view which showed the example of the LED package which mounted 3 types of LED. (A), (B) is sectional drawing showing the other mounting example of the LED chip. It is the light-emitting device using the LED package produced by the Example of this application. It is sectional drawing which showed the structural example of the LED package.

Explanation of symbols

11 Silicon substrate 11a, 11b Horn 21, 21a, 23, 23a, 23b, 24 Silicon oxide film 22, 24, 27 Resist pattern 25, 25a, 25b Barrier layer 26 Reflective film 26a, 26b, 27a, 27b, 27c, 27d, 28a, 28b, 28c, 28d Reflective film and electrode 26c, 26e Chip mounting part 26d Connection part 31, 32a, 32b, 32c, 33a, 33b, 33c, 34, 35 LED chip 31a, 31g Metal electrode 31b, 34a Substrate 31c Semiconductor Layers 31d, 34d p-type semiconductor layers 31e, 34c light-emitting layers 31f, 34b n-type semiconductor layers 31w, 34w bonding wires 34e n-type electrodes 34f p-type electrodes 40 transparent resin 51 LED light emitters 52 switches 53

Claims (12)

(A) A silicon substrate whose surface is a (100) plane is subjected to anisotropic etching depending on the plane orientation to form a horn having a (100) plane as a bottom surface and four (111) planes as inclined side surfaces. And a process of
(B) forming irregularities on the inclined side surface of the horn;
(C) A method of manufacturing an LED package, including a step of mounting an LED chip on the bottom surface of the horn. The step (b)
(B-1) forming an oxide film on the surface of the silicon substrate including the horn;
(B-2) forming a resist pattern on the (100) surface of the silicon substrate having an oxide film formed on the surface;
(B-3) removing the oxide film on the inclined side surface of the horn with a buffered hydrofluoric acid solution and leaving the oxide film on the (100) surface of the silicon substrate containing the horn; and (b-4) the above (100) Using the remaining oxide film as a mask, the (111) surface of the horn is subjected to anisotropic etching under different conditions from the anisotropic etching performed in the step (a) to make the (111) surface smooth. A method for manufacturing an LED package according to claim 1, further comprising a step of forming dimple-shaped irregularities configured by curves. The step (b)
(B-1) forming an oxide film on the surface of the silicon substrate including the horn;
(B-2) forming a resist pattern on the (100) surface of the silicon substrate having an oxide film formed on the surface;
(B-3) removing the oxide film on the inclined side surface of the horn with a buffered hydrofluoric acid solution and leaving the oxide film on the (100) surface of the silicon substrate containing the horn; and (b-4) the above (100) And a blasting process is performed on the (111) surface of the horn to form a rough diffused reflection surface on the (111) surface, using the remaining oxide film as a mask. LED package manufacturing method. The step (c)
(C-1) forming an insulating film on the inner surface of the horn including the bottom surface and the inclined side surface;
(C-2) forming an electrode that also serves as a reflective film and is divided into at least two regions on the insulating film;
(C-3) electrically and mechanically connecting one terminal of at least one LED chip on at least one of the electrodes, and further connecting an electrode different from the electrode and the other terminal of the LED chip The manufacturing method of the LED package in any one of Claim 1 to 3 including the process to connect. After step (c)
The manufacturing method of the LED package in any one of Claim 1 to 4 including the process of filling the resin material in the said horn and forming a resin mold. By anisotropic etching, a horn composed of a bottom surface of (100) plane and four (111) plane inclined side surfaces is formed, and further, a silicon substrate having irregularities formed on four (111) planes;
An LED package including an LED chip mounted on the bottom surface of the horn; The unevenness is
7. The LED package according to claim 6, wherein the LED package is a dimple-shaped concavo-convex having a smooth curve formed by subjecting the (111) plane to anisotropic etching under conditions different from those of the anisotropic etching. The unevenness is
The LED package according to claim 6, wherein the LED package is a diffuse reflection surface having rough irregularities formed by blasting the (111) surface. An insulating film formed on the inner surface of the horn including the bottom surface and the inclined side surface;
An electrode formed on the insulating film and divided into at least two regions serving also as a reflective film;
The LED chip according to any one of claims 6 to 8, further comprising: an LED chip having one terminal electrically and mechanically connected to at least one of the electrodes, and the other terminal connected to another electrode. The described LED package.   The LED package according to claim 9, wherein the electrode extends to the back side of the silicon substrate. further,
The LED package according to claim 6, further comprising a resin mold formed by filling the horn with a resin material.   A light emitting device using the LED package according to claim 6.

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