JP2012084622A - Semiconductor light-emitting element manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that when applying a manufacturing method in which a fluorescent substance layer containing a fluorescent substance having a conversion efficiency greatly varying at around a peak wavelength of light irradiated from a semiconductor layer of an LED element is formed on a wafer on which a number of LED elements are disposed and the wafer is singulated into pieces of LED elements, luminous colors of the individual LED elements vary because peak wavelengths of the individual LED elements take different values within a range of a few nanometers.SOLUTION: A semiconductor light-emitting element manufacturing method comprises the steps of (a) preparing a wafer provided with a light-emitting layer and a connection electrode on one face, (b) obtaining a peak wavelength distribution of the wafer and forming phosphor on the other face of the wafer by adjusting a thickness based on the peak wavelength distribution, and (c) singulating the wafer into pieces of LED elements by cutting the wafer.

Description

  The present invention relates to a method of manufacturing a flip-chip semiconductor light emitting device having a phosphor layer only on an upper surface.

  Among semiconductor light emitting devices (hereinafter referred to as LED elements unless otherwise specified) mounted on a circuit board of a semiconductor light emitting device (hereinafter referred to as an LED device unless otherwise specified), a light emitting layer is connected to one surface of a transparent substrate. There is an LED element including an electrode and having a phosphor layer formed on the other surface (for example, FIG. 4 of Patent Document 1).

  FIG. 5 of Patent Document 1 is shown in FIG. FIG. 5 is a cross-sectional view of a conventional light emitting diode 1 (LED device) having a fluorescent layer 3 on the emission surface of a chip 2 (LED element). The chip 2 is flip-chip mounted on the lead frame 4, and the chip 2 is sealed with a case 5 made of a transparent resin.

  A method for manufacturing such an LED element is shown in FIGS. FIG. 1 of Patent Document 1 shows a state in which the P layer is diffused on one surface of the wafer 2 </ b> A, the light emitting portion 2 a is formed, and the positive electrode 2 b and the negative electrode 2 c are provided. FIG. 2 shows a process of forming the fluorescent layer 3 containing the fluorescent material 3a on the wafer 2A. The fluorescent layer 3 is provided on the other surface, ie, the light exit surface 2d, which has a front-back relationship with the one surface described above. Means for providing the fluorescent layer 3 may be spray coating, spin coating, vacuum deposition, or the like. Finally, the wafer 2A on which the fluorescent layer 3 is formed is cut to obtain individual chips 2 (FIG. 3).

JP-A-10-209505 (FIGS. 1 to 4)

  There are phosphors whose conversion efficiency varies greatly in the vicinity of the peak wavelength of light emitted from the semiconductor layer of the LED element (hereinafter, unless otherwise specified, “peak wavelength” indicates the peak wavelength of light emitted from the semiconductor layer of the LED element). On a wafer on which a large number of LED elements are arranged, the peak wavelength of each LED element takes a different value within a range of several nm. Therefore, when a phosphor layer having a uniform thickness is formed on a wafer, the distance between the individual LED elements is reduced. This causes the problem that the emission color varies.

  Therefore, in order to solve this problem, the present invention provides a case where the phosphor contained in the phosphor layer is easily affected by the peak wavelength when the phosphor layer is formed on the wafer on which the semiconductor layers contained in the LED element are arranged. Even if it exists, it aims at providing the manufacturing method of the semiconductor light-emitting element which can suppress the chromaticity dispersion | variation between LED elements.

In order to solve the above problems, a method for manufacturing a semiconductor light-emitting device according to the present invention is a semiconductor light-emitting device obtained by separating a wafer having a light-emitting layer and a connection electrode on one surface and a phosphor layer on the other surface. In the manufacturing method,
A wafer preparation step of preparing a wafer before forming the phosphor layer;
A characteristic measuring step for obtaining a characteristic distribution of the wafer;
A phosphor layer forming step of forming a phosphor on the other surface of the wafer while adjusting the thickness based on the characteristic distribution;
And a singulation step of cutting the wafer into pieces of the semiconductor light emitting elements.

  It is known that the peak wavelength of each LED element region is smoothly distributed in the plane of the wafer. This is because when the semiconductor layer is formed, the epitaxial growth does not change abruptly even if it is not uniform over the entire wafer. In the present invention, since the thickness of the phosphor layer is adjusted to match the smooth distribution of the peak wavelength, the chromaticity variation of individual LED light elements can be reduced regardless of where the wafer is separated. It is possible to fit in a narrow range. As described above, in the method for manufacturing a semiconductor light emitting device of the present invention, when the phosphor layer is formed on the wafer on which the semiconductor layers included in the LED element are arranged, the phosphor included in the phosphor layer affects the peak wavelength of the LED element. Even if it is easy to receive, it becomes possible to suppress the chromaticity dispersion | variation between LED elements.

Sectional drawing of the LED apparatus provided with the LED element manufactured by embodiment of this invention. The characteristic distribution map of the wafer used in the embodiment of the present invention. Explanatory drawing of the manufacturing method of the LED element in embodiment of this invention. Explanatory drawing of the manufacturing method of the LED apparatus in embodiment of this invention. Sectional drawing of the conventional LED device.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to FIGS. In the description of the drawings, the same or equivalent elements will be denoted by the same reference numerals, and redundant description will be omitted. For the sake of explanation, the scale of the members is changed as appropriate.

  FIG. 1 is a cross-sectional view of an LED device 10 (semiconductor light emitting device) in which an LED element 21 (semiconductor light emitting device) manufactured by the method of this embodiment is mounted on a circuit board 22. In the LED device 10, an LED element 21 is flip-chip mounted on a circuit board 22. The electrode 17 formed on the upper surface of the plate material 20 in the circuit board 22 is connected to the electrode 19 formed on the lower surface of the plate material 20 through the through hole 18. In the LED element 21, a semiconductor layer 13 is formed on the lower surface of the sapphire substrate 12 (transparent substrate), and a phosphor layer 15 is formed on the upper surface. The semiconductor layer 13 is a diode provided with a light emitting layer, and the two attached bumps 14 correspond to an anode and a cathode, respectively. The bumps 14 are connected to the electrodes 17 by metal eutectic bonding. The upper surface of the circuit board 22 and the LED element 21 are sealed with the resin layer 11.

  The semiconductor layer 13 of the LED element 21 is a blue light emitting diode, and the phosphor layer 15 includes a silicate green phosphor and a nitride red phosphor. The blue light emitted from the semiconductor layer 13 causes the fluorescent layer 15 to emit green light and red light. As a result, the blue light of the semiconductor layer 13 and the green light and red light from the phosphor layer 15 are mixed to obtain white light. The emission efficiency of the green phosphor changes greatly at the peak wavelength of blue light (exactly, the emission spectrum). For this reason, the amount of the green phosphor (the thickness of the phosphor layer 15) is finely adjusted according to the peak wavelength.

The resin layer 11 is made of a transparent silicone resin containing a scattering material and has a thickness of several hundreds of μm. The phosphor layer 15 is finely tuned in the range of 100 μm to 150 μm. The sapphire substrate 12 has a thickness of 80 to 120 μm. However, if the sapphire substrate 12 is further thinned, the light emitted from the side surface of the sapphire substrate 12 decreases, the light traveling upward increases, and the wavelength conversion efficiency and the light emission efficiency are improved. The semiconductor layer 13 has a thickness of about 7 μm, and the bump 14 has a thickness of 10 if formed by electrolytic plating.
˜30 μm. The plate member 20 has a thickness of several hundreds of micrometers and is selected from resin, ceramic, and metal in consideration of thermal conductivity. The electrodes 17 and 19 are formed by laminating a nickel layer and a gold layer on a copper foil of about 20 μm, for example. When the plate material 20 is resin, the through hole 18 is preferably filled with a metal paste to improve thermal conductivity.

  FIG. 2 is a characteristic distribution diagram showing a peak wavelength distribution of the wafer 23 in which a large number of LED elements 21 (not provided with the phosphor layer 15) used in the present embodiment are arranged. A dotted line on the outer peripheral portion of the wafer 23 is obtained by connecting the LED elements 21 having a wavelength of λ1, and is like a contour line. Similarly, the inner dotted line and the innermost dotted line are obtained by connecting the LED elements 21 having wavelengths of λ2 and λ3, respectively. Since the spread of the peak wavelength is approximately in the range of several nm in one wafer, for example, the wavelength λ1 is 445 nm, the wavelength λ2 is 446 nm, and the wavelength λ3 is 447 nm. Also, a distribution in which the wavelength changes smoothly between the wavelength λ1 and the wavelength λ2, for example.

  FIG. 3 is an explanatory diagram of a process for manufacturing the LED element 21. (A) is a wafer preparation process for preparing the wafer 23 before forming the phosphor layer 15. A plurality of semiconductor layers 13 are formed on the lower surface of the wafer 23 based on the sapphire substrate 12, and bumps 14 are attached to the semiconductor layers 13 in each LED element region. A nozzle 31 for applying a phosphor is shown on the upper surface of the wafer 23. In addition, the semiconductor layer 13 included in each LED element 21 in the state of the wafer 23 is inspected for quality determination such as leakage, and the light emission characteristics such as the peak wavelength are also measured. That is, the characteristic distribution of the wafer 23 is measured in this inspection process (characteristic measurement process).

  (B) is a phosphor layer forming step of applying (forming) the phosphor on the upper surface of the wafer 23 while adjusting the coating amount (thickness) based on the above-described characteristic distribution. The phosphor layer 15 is thickest on the third semiconductor layer 13 from the right in the drawing. This corresponds to a region where the LED element 21 having a wavelength of about λ3 in FIG. 2 is present. That is, as the peak wavelength of the LED element 21 becomes longer, the luminous efficiency of the green phosphor decreases, and the phosphor layer 15 is made thicker to compensate for this. The thickness adjustment of the phosphor layer 15 is determined by the amount of ink (containing phosphor) ejected from the nozzle 31, and the thickness of the phosphor layer 15 is also corresponding to the smooth distribution of the peak wavelength as described above. It is gradually changing. The discharge amount is controlled in accordance with the ink jet printing method (see, for example, Japanese Patent Laid-Open No. 11-46019). Since the phosphor layer 15 needs to be able to withstand the temperature (about 300 ° C.) applied when the LED element 21 is mounted on the circuit board 22, it becomes glassy (inorganic) when organopolysiloxane or the like is sintered. Ink in which a binder that can withstand the above, a phosphor having a particle size of several μm, and a catalyst are mixed in a solvent is used. When the ink is applied, it is sintered at 150 ° C.

  (C) is a singulation process for cutting the wafer 23 to separate the LED elements 21 (hereinafter, the LED elements 21 will be provided with the phosphor layer 15). When the wafer 23 is attached to a dicing sheet, cut by a dicing apparatus, and the dicing sheet is expanded, each LED element 21 can be picked up. Each LED element 21 has a small chromaticity variation because the thickness of the phosphor layer 15 is adjusted in accordance with the peak wavelength.

FIG. 4 is an explanatory diagram of a manufacturing method of the LED device 10 in which the LED element 21 is mounted on the circuit board 22. (A) is a mounting process in which the LED elements 21 are flip-chip mounted on the collective substrate 22a connected to the circuit substrate 22. The collective substrate 22a is provided with a large number of circuit board regions on a large plate member 20 (see FIG. 1). Each circuit board region has an electrode 17 (see FIG. 1), a through hole 18 (see FIG. 1), and an electrode 19 (see FIG. 1). 1) is formed. The LED elements 21 may be arranged on the collective substrate 22a one by one, or the LED elements 21 are arranged on the adhesive sheet in advance according to the electrode pitch of the collective substrate 22a, and this adhesive sheet is stacked on the collective substrate 22a. Many LEDs
The elements 21 may be collectively arranged on the collective substrate 22a. When the placement of the LED element 21 is completed, the LED element 21 is pressurized and heated to be joined to the electrode 17.

  (B) is a transparent resin coating step of coating a transparent resin. When the resin layer 11 made of silicone resin is applied, it is cured by heating at about 150 ° C. (C) is an LED device singulation process for separating the LED device 10 into single pieces from the collective substrate 22a. The collective substrate 22a is cut by a dicing device to divide the LED device 10 into individual pieces.

  In the present embodiment, the phosphor layer 15 is formed by coating in the phosphor layer forming step. As a method for forming the phosphor layer, the phosphor layer may be once formed flat and thick, and the thickness of the phosphor layer may be adjusted by polishing or grinding.

10 ... LED device (semiconductor light-emitting device),
11 ... resin layer,
12 ... Sapphire substrate (transparent substrate),
13 ... semiconductor layer,
14 ... Bump,
15 ... phosphor layer,
17, 19 ... electrodes,
18 ... Through hole,
20 ... plate material,
21 ... LED element (semiconductor light emitting element),
22 ... circuit board,
22a ... collective board,
23 ... wafer,
31 ... Nozzle.

Claims (1)

In a method for manufacturing a semiconductor light emitting device obtained by separating a wafer having a light emitting layer and a connection electrode on one surface and a phosphor layer on the other surface,
A wafer preparation step of preparing a wafer before forming the phosphor layer;
A characteristic measuring step for obtaining a characteristic distribution of the wafer;
A phosphor layer forming step of forming a phosphor on the other surface of the wafer while adjusting the thickness based on the characteristic distribution;
A method for manufacturing a semiconductor light emitting device, comprising: a step of cutting the wafer into pieces to separate the semiconductor light emitting devices.

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