JP6102408B2 - Light emitting device and manufacturing method thereof - Google Patents

Description

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

  As a conventional light emitting device, a device in which a light emitting cell is mounted on an AlN substrate is known (for example, see Patent Document 1). Since AlN has high thermal conductivity, the heat dissipation characteristics of the light-emitting device can be improved by using an AlN substrate.

  As another conventional light emitting device, a device in which a light emitting element is mounted on a Si substrate provided with a through wiring is known (for example, see Patent Document 2). This light emitting element is electrically connected to the through electrode, and is connected to the electrode on the back surface of the Si substrate through the through electrode.

JP 2012-129546 A JP 2006-135276 A

  AlN has a high thermal conductivity, but it is necessary to increase the crystal grain size in order to improve the thermal conductivity. The larger the AlN crystal grain size, the easier the AlN crystal particles fall off from the substrate surface in the polishing process or dicing process of the AlN substrate, and the smoothness of the surface decreases. If the smoothness of the substrate surface is low, a problem may occur when a member such as a light emitting element is formed on the substrate.

  For example, since the smoothness of the electrode film formed on the surface of the substrate is also lowered, the void generation rate in the solder is increased when the light emitting element is soldered thereto. For this reason, when the light emitting element is solder-connected on the AlN substrate, although the thermal conductivity of the AlN substrate is high, heat is not easily transmitted from the light emitting element to the AlN substrate due to voids in the solder, so the heat dissipation characteristics of the device are lowered. There is a fear.

  One of the objects of the present invention is to provide a light emitting device excellent in heat dissipation and a method for manufacturing the same that can effectively release heat from the light emitting element to the substrate and from the front surface to the back surface of the substrate. .

  In order to achieve the above object, one embodiment of the present invention provides a method for manufacturing a light-emitting device according to any one of [1] to [5] below.

[1] Forming a plurality of through holes in a region corresponding to the light emitting element mounting portion and the light emitting element non- mounting portion of the element mounting substrate made of a non-conductive material and having a light emitting element mounting portion and a light emitting element non- mounting portion. Forming a conductive member that fills the plurality of through holes and covers the first main surface and the second main surface of the element mounting substrate, and at least the first of the element mounting substrate. A step of flattening a portion covering the first main surface and the second main surface of the conductive member so as not to expose the main surface; and the conductive member in an in-plane direction of the element mounting substrate. And separating the light emitting element on the first main surface side so that the n-side electrode and the p-side electrode of the light emitting element are electrically connected to the separated different portions of the conductive member, respectively. A light emitting device including a step of mounting on the element mounting substrate. Law.

[2] The method for manufacturing a light-emitting device according to [1], wherein the light-emitting element is solder-connected on the element mounting substrate.

[3] The method for manufacturing a light-emitting device according to [1] or [2], wherein a volume occupancy ratio in the element mounting substrate of a portion in the plurality of through holes of the conductive member is 13% or more.

[4] The method for manufacturing a light-emitting device according to any one of [1] to [3], wherein the element mounting substrate is a Si substrate.

[5] The method for manufacturing a light emitting device according to any one of [1] to [4], wherein a plurality of light emitting elements are mounted on the element mounting substrate.

  In order to achieve the above object, another aspect of the present invention provides a light emitting device of the following [6].

[6] A light-emitting device manufactured by the method for manufacturing a light-emitting device according to any one of [1] to [5].

  ADVANTAGE OF THE INVENTION According to this invention, the light-emitting device excellent in heat dissipation which can escape heat effectively from a light emitting element to a board | substrate and from the surface of a board | substrate to a back surface, and its manufacturing method can be provided.

FIG. 1 is a vertical cross-sectional view of the light emitting device according to the first embodiment. 2A to 2D are enlarged vertical cross-sectional views showing the manufacturing process of the conductive member according to the first embodiment. FIGS. 3E to 3G are enlarged vertical sectional views showing the manufacturing process of the conductive member according to the first embodiment. FIG. 4A schematically shows a heat dissipation path of the light emitting device according to the first embodiment. FIG. 4B schematically shows a heat dissipation path of the light emitting device according to the comparative example. FIG. 5A is an enlarged view of the light emitting device according to the first embodiment. FIG. 5B is an enlarged view of the light emitting device according to the comparative example. FIG. 6 is a graph showing the relationship between the volume occupation ratio in the substrate inside the hole of the conductive member and the transient thermal resistance of the substrate. FIG. 7A is a graph showing a temperature distribution during operation of the light emitting device according to the first embodiment. FIG. 7B is a graph showing a temperature distribution during operation of the light emitting device according to the comparative example. FIG. 8 is a schematic top view of the light emitting device for illustrating the measurement position of the temperature distribution of the light emitting device according to the first embodiment and the light emitting device according to the comparative example. FIG. 9 is a vertical cross-sectional view of the light emitting device according to the second embodiment.

[First Embodiment]
(Configuration of light emitting device)
FIG. 1 is a vertical cross-sectional view of a light emitting device 10 according to the first embodiment. The light emitting device 10 includes a substrate 11 having a plurality of through holes, conductive members 12a and 12b formed in and on the plurality of through holes of the substrate 11, and one surface side of the substrate 11 (upper side in FIG. 1). Electrode films 13a and 13b formed on the conductive members 12a and 12b, respectively, and a light emitting element 20 mounted on the substrate 11 so as to be electrically connected to the electrode films 13a and 13b.

  The substrate 11 is made of a nonconductive material such as Si or AlN. The plurality of through holes in the substrate 11 are, for example, cylindrical or polygonal column holes.

  The conductive members 12a and 12b are made of a conductive material such as Cu. The conductive members 12 a and 12 b include a hole interior 12 v that fills the plurality of through holes of the substrate 11, and a front surface portion 12 s that covers the front surface and the back surface of the substrate 11. The surface of the surface portion 12s is flattened by a flattening process such as CMP (Chemical Mechanical Polishing). Note that the surface portion 12s may be formed on at least the main surface of the substrate 11 on the light emitting element 20 side.

  The electrode films 13a and 13b are made of a conductive material such as Au or Ag. The electrode films 13a and 13b are electrically connected to the conductive members 12a and 12b, respectively. The electrode films 13a and 13b are thin films and are thinner than the surface portions 12s of the conductive members 12a and 12b. The light emitting device 10 does not have the electrode films 13a and 13b, and the conductive members 12a and 12b may be used as electrodes.

  The light emitting element 20 is, for example, a flip chip type LED chip as shown in FIG. The light emitting element 20 includes an element substrate 21, a crystal layer 22 including a light emitting layer and a clad layer sandwiching the light emitting layer, and an n-side electrode 23a and a p-side electrode 23b connected to the crystal layer 22.

  The n-side electrode 23a and the p-side electrode 23b of the light emitting element 20 are connected to the electrode films 13a and 13b via the solder layer 14 such as a solder bump, respectively. When the light emitting device 10 does not have the electrode films 13a and 13b, the n-side electrode 23a and the p-side electrode 23b are connected to the surface portion 12s of the conductive members 12a and 12b.

(Manufacture of light emitting devices)
Below, an example of the manufacturing process of the light-emitting device 10 which concerns on this Embodiment is demonstrated.

  FIGS. 2A to 2D and FIGS. 3E to 3G are enlarged vertical sectional views showing manufacturing steps of the conductive members 12a and 12b according to the first embodiment.

  First, as shown in FIG. 2A, silicon oxide films 30 are formed on the principal surfaces on both sides of the substrate 11 which is a Si substrate by thermal oxidation or the like. Here, of the main surfaces on both sides of the substrate 11, a surface on which the light emitting element 20 is mounted is a first main surface 11a, and a main surface on the opposite side is a second main surface 11b.

  Next, as shown in FIG. 2B, a plurality of through holes 31 are formed in the substrate 11 and the silicon oxide film 30 by dry etching using a mask formed by photolithography. The dry etching performed in this step is, for example, deep RIE (Deep-Reactive Ion Etching).

  Next, as shown in FIG. 2C, a silicon oxide film 32 is formed on the inner surface of the through hole 31 and the surface of the silicon oxide film 30 by thermal oxidation or the like. The thickness of the silicon oxide film 32 is, for example, about 1 μm, and the silicon oxide film 32 ensures insulation between the hole interiors 12 v of the conductive members 12 a and 12 b and the substrate 11.

  Next, as shown in FIG. 2D, a barrier layer 33 made of TiN, SiN or the like is formed on the silicon oxide film 32 by sputtering.

  Next, as shown in FIG. 3E, an electrode seed layer 34 made of electroless copper or the like is formed on the barrier layer 33 by sputtering.

  Next, as shown in FIG. 3F, Cu is plated on the electrode seed layer 34 by electrolytic plating to form the conductive member 12. The conductive member 12 is formed so as to fill the plurality of through holes 31 and cover the first main surface 11 a and the second main surface 11 b of the substrate 11.

  Next, as shown in FIG. 3G, at least the first main surface 11a of the substrate 11 is not exposed, that is, at least the surface portion 12s is formed on the first main surface 11a. A planarization process such as CMP is performed on a portion of the conductive member 12 covering the first main surface 11a and the second main surface 11b of the substrate 11.

  Thereafter, the portion of the conductive member 12 covering the first main surface 11a and the second main surface 11b of the conductive member 12 is etched by dry etching using a mask formed by photolithography, and the conductive member 12 is removed from the substrate 11. The conductive member 12a and the conductive member 12b are formed.

  Then, the light emitting element 20 is mounted on the substrate 11 so that the n-side electrode 23a and the p-side electrode 23b are electrically connected to the conductive members 12a and 12b, respectively.

  Note that the silicon oxide film 30, the silicon oxide film 32, the barrier layer 33, and the electrode seed layer 34 are not shown in FIG.

(Heat dissipation characteristics of light emitting device)
Hereinafter, heat dissipation characteristics of the light-emitting device of this embodiment will be described using a comparative example.

  FIG. 4A schematically shows a heat radiation path of the light emitting device 10 according to the first embodiment. FIG. 4B schematically shows a heat dissipation path of the light emitting device 100 according to the comparative example. 4A and 4B, arrows passing through the conductive member represent main heat dissipation paths for heat generated in the light emitting element 20.

  In the light emitting device 100 according to the comparative example shown in FIG. 4B, the conductive member 101 does not include a portion corresponding to the surface portion 12s, and is configured only by a portion in the through hole corresponding to the hole interior 12v. This is different from the light emitting device 10 according to the first embodiment.

  In the light emitting device 100, the plurality of conductive members 101 are separated and formed in the substrate 11, and heat transfer between the conductive members 101 adjacent to each other with the substrate 11 is small. For this reason, only the conductive member 101 directly under the light emitting element 20 functions as a main heat dissipation path for the heat generated in the light emitting element 20. The thin electrode films 13a and 13b hardly function as a heat dissipation path.

  On the other hand, in the light emitting device 10, since the surface portions 12s of the conductive members 12a and 12b function as a heat dissipation path, the heat generated in the light emitting element 20 is transmitted through the surface portion 12s to the wide hole interior 12v and radiated. . That is, in the light emitting device 10, since the conductive members 12a and 12b have the surface portion 12s, a wide area of the conductive members 12a and 12b functions as a heat dissipation path. For this reason, the light emitting device 10 according to the first embodiment is more excellent in heat dissipation characteristics than the light emitting device 100 according to the comparative example. In addition, if the surface portion 12s of the conductive members 12a and 12b exists at least on the first main surface 11a side of the substrate 11, excellent heat dissipation characteristics can be obtained.

  FIG. 5A is an enlarged view of the light emitting device 10 according to the first embodiment. FIG. 5B is an enlarged view of the light emitting device 200 according to the comparative example. The light emitting devices 10 and 200 shown in FIGS. 5A and 5B respectively have a substrate 11 having a relatively large unevenness on the surface such as an AlN substrate.

  The light emitting device 200 according to the comparative example shown in FIG. 5B is different from the light emitting device 10 according to the first embodiment in that the light emitting device 200 does not include the conductive members 12a and 12b.

  In the light emitting device 200, since the electrode films 13a and 13b are directly formed on the surface of the substrate 11 having the unevenness, the unevenness is also formed in the electrode films 13a and 13b. And it is easy to generate a void in the solder layer 14 formed on the uneven electrode films 13a and 13b. If the solder layer 14 contains voids, the thermal conductivity is lowered, so that the heat generated in the light emitting element 20 is difficult to escape to the substrate 11 side. For this reason, even if the thermal conductivity of the substrate 11 is high, the heat dissipation characteristics of the light emitting device 200 are degraded by the voids in the solder layer 14.

  On the other hand, in the light emitting device 10, since the electrode films 13a and 13b are formed on the planarized surface portion 12s of the conductive members 12a and 12b, the electrode 11 The films 13a and 13b are formed flat. For this reason, generation | occurrence | production of the void in the solder layer 14 can be suppressed, and the heat | fever generate | occur | produced in the light emitting element 20 can be efficiently released to the board | substrate 11 side. As described above, when the light emitting element 20 is soldered on the substrate 11 having an uneven surface, the presence of the conductive members 12a and 12b becomes more important in order to improve the heat dissipation characteristics. If the surface portion 12s of the conductive members 12a and 12b exists at least on the first main surface 11a side of the substrate 11, the generation of voids in the solder layer 14 can be suppressed.

  FIG. 6 is a graph showing the relationship between the volume occupancy ratio (hereinafter referred to as “volume occupancy ratio”) in the substrate 11 of the holes 12 v inside the conductive members 12 a and 12 b and the transient thermal resistance of the substrate 11. Here, the thing obtained by dividing the heat generated when a single pulse is applied to the substrate 11 by the applied electric power is the thermal resistance value, and the thermal resistance value expressed in units of pulse time is the transient thermal resistance.

  In FIG. 6, the measured values of the transient thermal resistivity when the volume occupancy is 0%, 7.07%, 14.4%, and 19.6% are plotted with marks “◇”, respectively. The mark “◆” represents the average value of “◇” in each volume occupancy, and the dotted line is derived from the coordinates of “♦” at the volume occupancy 7.07%, 14.4%, 19.6%. Approximated straight line.

  The substrate 11 of the light emitting device 10 whose transient thermal resistivity is measured is a Si substrate, and the conductive members 12a and 12b are made of Cu. The volume occupancy of 19.6% is almost the upper limit in the manufacturing process, and it is difficult to form the hole interior 12v with a volume occupancy higher than this.

  Further, at the right end of FIG. 6, measured values of transient thermal resistivity of the light emitting device according to the comparative example are plotted with a mark “◯”. The mark “●” represents the average value of “◯”. The light emitting device according to this comparative example has an AlN substrate, does not have the conductive members 12a and 12b, and has the same structure as the light emitting device 200 shown in FIG.

  Note that the area of the substrate 11 of the light emitting device 10 in which the transient thermal resistivity was measured is the same as the area of the AlN substrate of the light emitting device according to the comparative example.

  FIG. 6 shows that when the volume occupancy of the light emitting device 10 increases, the transient thermal resistivity decreases, and when the volume occupancy is approximately 13% or more, the average value of the transient thermal resistivity is a light emitting element according to a comparative example. It shows that it becomes below the average value of the transient thermal resistivity. That is, by setting the volume occupancy ratio of the hole interior 12v in the substrate 11 to 13% or more, the transient thermal resistance of the substrate 11 including the conductive members 12a and 12b is the transient thermal resistance of the AlN substrate having high thermal conductivity. It shows that it becomes below the rate.

  FIG. 7A is a graph showing a temperature distribution during operation of the light emitting device 10 according to the first embodiment. FIG. 7B is a graph showing a temperature distribution during operation of the light emitting device according to the comparative example.

  FIG. 8 is a schematic top view of the light emitting device for illustrating the measurement positions of the temperature distribution of the light emitting device 10 according to the first embodiment and the light emitting device according to the comparative example. The measured values in FIGS. 7A and 7B are obtained by measuring the temperature distribution on the straight line represented by the arrow in FIG. In FIG. 8, the conductive members 12a and 12b are not shown.

  Here, the substrate 11 of the light-emitting device 10 whose temperature distribution was measured is a square Si substrate having a side length of 3.5 mm. The conductive members 12a and 12b are made of Cu, and the volume occupancy ratio of the inside 12v of the hole in the substrate 11 is 19.6%.

  The light emitting device according to the comparative example has the same structure as the light emitting device 200 shown in FIG. 5B, and has a square AlN substrate having a side length of 3.5 mm as the substrate 11. Note that the conductive members 12a and 12b are not provided.

  The light emitting device 10 and the light emitting device according to the comparative example both have the same square LED chip having a side length of 1 mm as the light emitting element 20. The light emitting device 10 and the light emitting device according to the comparative example are both installed on an Al substrate 35 having electrodes on the surface, and power is supplied to the light emitting element 20 through the electrodes of the Al substrate 35.

  7A, 7 </ b> B, and 8 </ b> A, 8 </ b> A and 8 </ b> B represent the positions of both ends of the light emitting element 10 on a straight line that is a temperature distribution measurement region, and C and D represent the positions of both ends of the substrate 11. Represent.

  FIGS. 7A and 7B show that the temperature of the light emitting device 10 is generally lower than the temperature of the light emitting device according to the comparative example. This indicates that the light-emitting device 10 has a heat dissipation characteristic that is equal to or better than that of a light-emitting device having an AlN substrate with high thermal conductivity.

  Further, the temperature T shown in FIGS. 7A and 7B is an intermediate temperature between the temperature at the points C and D and the temperature at the points A and B. In the case where a plurality of light emitting elements 20 are installed side by side, if the portions of the temperature distribution curve of adjacent light emitting elements 20 that are higher than the temperature T overlap, the superposed temperature exceeds the junction temperature of the light emitting elements 20. For this reason, the distance between the position of the point A and the position where the temperature is T (the distance between the position of the point B and the position where the temperature is T) may be set to the minimum value of the interval between the adjacent light emitting elements 20. Desired.

  From this, the minimum value of the interval when mounting the plurality of light emitting elements 20 in the light emitting device 10 is set to 0.3 mm, and the minimum interval when mounting the plurality of light emitting elements 20 in the light emitting device according to the comparative example is set. The value is set to 0.1 mm. From here, the minimum value of the ratio of the interval between the light emitting elements 20 in the light emitting device 10 to the width of the light emitting element 20 is set to 0.3, and the light emitting elements in the interval between the light emitting elements 20 in the light emitting device according to the comparative example are set. The minimum value of the ratio to the width of 20 can be set to 0.1.

  As described above, the minimum value of the interval when mounting the plurality of light emitting elements 20 in the light emitting device 10 is small from that of the light emitting device having the AlN substrate having high thermal conductivity. This result indicates that a plurality of light emitting elements 20 can be arranged in the light emitting device 10 with a sufficiently high density.

[Second Embodiment]
In the second embodiment, a plurality of light emitting elements 20 are mounted on the substrate 11. The description of the same points as in the first embodiment will be omitted or simplified.

  FIG. 9 is a vertical cross-sectional view of the light emitting device 300 according to the second embodiment. The light emitting device 300 includes a substrate 11 having a plurality of through holes, conductive members 12c, 12d, and 12e formed in and on the plurality of through holes of the substrate 11, and one surface side of the substrate 11 (see FIG. 1). Electrode films 13c, 13d, and 13e formed on the upper conductive members 12c, 12d, and 12e, and a light-emitting element 20a mounted on the substrate 11 so as to be electrically connected to the electrode films 13c and 13d, And a light emitting element 20b mounted on the substrate 11 so as to be electrically connected to the electrode films 13d and 13e.

  The distance D between the light emitting element 20a and the light emitting element 20b is, for example, when the volume occupancy in the substrate 11 in the holes 12v of the conductive members 12c, 12d, and 12e is 19.6%. , 20b is set so that the minimum value of the ratio to the width is 0.3.

(Effect of embodiment)
According to the above embodiment, the heat dissipation characteristics of the light emitting device can be greatly improved by providing the conductive member having the surface portion 12s and the hole interior 12v. In addition, since the light-emitting device has excellent heat dissipation characteristics, a plurality of light-emitting elements can be arranged with a sufficiently high density.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the invention.

  Moreover, said embodiment does not limit the invention which concerns on a claim. In addition, it should be noted that not all the combinations of features described in the embodiments are essential to the means for solving the problems of the invention.

DESCRIPTION OF SYMBOLS 10, 300 Light-emitting device 11 Board | substrate 11a 1st main surface 11b 2nd main surface 12, 12a, 12b, 12c, 12d, 12e Conductive member 12s Surface part 12v Inside of hole 14 Solder layer 20, 20a, 20b Light-emitting element 23a n Side electrode 23b P side electrode 31 Through hole

Claims (6)

Forming a plurality of through holes in a region corresponding to the light emitting element mounting portion and the light emitting element non- mounting portion of an element mounting substrate made of a non-conductive material and having a light emitting element mounting portion and a light emitting element non- mounting portion; ,
Forming a conductive member that fills the plurality of through holes and covers the first main surface and the second main surface of the element mounting substrate;
Applying a planarization process to a portion covering the first main surface and the second main surface of the conductive member so as not to expose at least the first main surface of the element mounting substrate;
Separating the conductive member in an in-plane direction of the element mounting substrate;
The light emitting element is placed on the element mounting substrate on the first main surface side so that the n-side electrode and the p-side electrode of the light emitting element are electrically connected to different separated portions of the conductive member, respectively. Mounting process,
A method for manufacturing a light-emitting device including: The light emitting element is solder-connected on the element mounting substrate.
The manufacturing method of the light-emitting device of Claim 1. The volume occupancy in the element mounting substrate of the portions in the plurality of through holes of the conductive member is 13% or more.
The manufacturing method of the light-emitting device of Claim 1 or 2. The element mounting substrate is a Si substrate;
The manufacturing method of the light-emitting device of any one of Claims 1-3. Mounting a plurality of light emitting elements on the element mounting substrate;
The manufacturing method of the light-emitting device of any one of Claims 1-4.   The light-emitting device manufactured by the manufacturing method of the light-emitting device of any one of Claims 1-5.

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