JP5809965B2 - Semiconductor light emitting device - Google Patents

Description

  The present invention relates to a semiconductor light emitting device for flip chip mounting.

  A semiconductor light-emitting device cut out from a wafer (hereinafter referred to as an LED die unless otherwise specified) may be flip-chip mounted on a circuit board for an interposer, and coated with a covering member such as a resin together with the circuit board to be packaged. . A semiconductor light emitting device in which an LED die is packaged in this manner (hereinafter referred to as an LED device unless otherwise specified) is often soldered to a mother substrate by solder reflow together with other electronic components.

  When the covering member is made of a resin, the coating resin enters the gap between the LED die and the circuit board inside the LED device, and the coating resin that has entered the gap expands and contracts during and after solder reflow. May cause delamination around the bottom.

  FIG. 6 shows a cross-sectional view of a conventional LED device 60 in order to explain the peeled portion. The LED device 60 includes an LED die 69, a circuit board 68, and a covering 61. The LED die 69 includes a sapphire substrate 62, a semiconductor layer 63 formed on the lower surface thereof, and protruding electrodes 64 and 65 connected to the semiconductor layer 63. The circuit board 68 includes internal connection electrodes 66 and 67 on the upper surface, and the internal connection electrodes 66 and 67 are connected to the protruding electrodes 64 and 65, respectively. The coating resin 61 is a translucent resin containing a phosphor, and covers the surface of the circuit board 68 and the LED die 69, and part of the resin enters the gap between the LED die 69 and the circuit board 68.

  As described above, the LED device 60 is subjected to solder reflow when mounted on the mother board. At this time, the coating resin 61 that has entered the gap between the LED die 69 and the circuit board 68 expands. Therefore, in the figure, the interface between the protruding electrode 65 and the semiconductor layer 63 indicated by A, the interface between the protruding electrode 64 and the internal connection electrode 66 indicated by C, and the interface between the internal connection electrode 67 and the circuit board 68 indicated by D. Peeling occurs. Further, immediately after the reflow, when the coating resin 61 that has entered the gap between the LED die 69 and the circuit board 68 contracts rapidly, the interface between the sapphire substrate 62 and the semiconductor layer 63 indicated by B in FIG. Separation occurs inside the semiconductor layer 63. Separation of the protruding electrodes 64 and 65 that occurs in the portions indicated by A and C may cause the LED device 60 to be unlit due to disconnection. In addition, peeling related to the semiconductor layer 63 that occurs in the portion indicated by B results in non-lighting or increased leakage current.

  As described above, a similar case is known for the underfill of a semiconductor element mounted on a flip chip with respect to the peeling related to the coating resin 61 that has entered between the LED die 69 and the circuit board 68. Underfill is an underfill resin disposed between a lower surface of a semiconductor element and a circuit board, and peeling due to expansion and contraction of the underfill is still an ongoing problem. As measures against this, strengthening the adhesive strength of each interface, optimizing the heating profile, adjusting the coefficient of thermal expansion of each member, installing a mechanism to relieve the stress caused by heat, etc. have been proposed. Increases sex. If the semiconductor element has a mechanism to relieve the stress caused by heat, the common use of the semiconductor element itself is a countermeasure against peeling even if the circuit board, underfill material, and manufacturing process are changed. Compared to this, this stress relaxation mechanism is a generalized measure.

For example, FIG. 1A of Patent Document 1 shows a semiconductor chip 102 (semiconductor element) including stress relaxation layers 102a and 102b. FIG. 1A of Patent Document 1 is re-posted in FIG. FIG. 7 is a cross-sectional view of a conventional semiconductor device. This semiconductor device includes a semiconductor chip 1
02 is mounted on a wiring board having a conductive pattern such as a lead frame 101, a stress relaxation layer 102 a is formed at least on the back surface of the circuit formation surface of the semiconductor chip 102, and sealed with an insulating resin 105 so as to cover the semiconductor chip 102 It is characterized by that. The semiconductor chip 102 is flip-chip mounted on the lead frame 101 via bumps 107, and the bottom surface provided with the stress relaxation layer 102 b is sealed with the underfill resin 104. In paragraph 0019 of Patent Document 1, it is described that the stress relaxation layer 102b can prevent disconnection at the connection portion of the semiconductor chip 102, and the stress relaxation layer 102b further includes the semiconductor chip 102, the underfill resin 104, and the like. It is also described that generation of cracks due to the difference in thermal expansion can be prevented.

JP2009-188392A (FIG. 1 (a), paragraph 0019)

  As described above, the stress relaxation layer 102b shown in FIG. 7 is described as contributing to the prevention of cracks due to the difference in thermal expansion between the semiconductor chip 102 and the underfill resin 104. It can be presumed that the bottom surface portion of the semiconductor chip 102 is to be prevented from peeling or breaking. However, the peeling shown in FIG. 6 occurs when the LED die 69 is pushed up or pulled down by the expansion / contraction of the coating resin 61 present at the bottom of the LED die 69. In particular, the peeling that occurs at the portion indicated by B in FIG. 6 occurs due to the shrinkage of the coating resin 61, leading to the destruction of the semiconductor layer 63. That is, even if the stress relaxation mechanism (stress relaxation layer 102b in FIG. 7) shown in Patent Document 1 is applied to the LED device 60 in FIG. 6, it cannot cope with the breakdown due to peeling of the portion shown in FIG.

  Therefore, in order to solve this problem, the present invention provides a semiconductor device that is flip-chip mounted on a circuit board of a semiconductor device. An object is to provide a semiconductor light emitting device.

In order to solve the above problems, a semiconductor light emitting device of the present invention is a semiconductor light emitting device that is flip-chip mounted on a circuit board of a semiconductor light emitting device and covered with a coating resin, and a p-type semiconductor layer and an n-type semiconductor layer, An insulating film covering the semiconductor layer and the n-type semiconductor layer; a p-side protruding electrode and an n-side protruding electrode connected to the p-type semiconductor layer and the n-type semiconductor layer through an opening of the insulating film; and a peeling member provided so as to contact with the insulating film between the p-side protruding electrode and the n-side protruding electrode, the p-side protruding electrode and the n-side protruding electrode protrudes from the insulating layer, the p At least one of the side protruding electrode or the n-side protruding electrode partially overlaps the insulating film in a planar manner, the peeling member does not exist in the peripheral portion of the insulating film, and the p-side protruding electrode and the n-side protruding electrode Side protrusion electrode and flat Characterized in that it does not overlap manner.

  When the semiconductor light emitting device of the present invention is flip-chip mounted on a circuit board and covered with a coating resin, the coating resin enters a gap formed by the protruding electrode and the electrode of the circuit board in the mounting portion. Even if the coating resin contracts rapidly immediately after the solder reflow, the peeling member is peeled off from the semiconductor light emitting element or the coating resin, and stress is not transmitted from the coating resin to the semiconductor layer of the semiconductor light emitting device. As a result, it is possible to prevent the semiconductor layer from being peeled off from the transparent insulating substrate of the semiconductor light emitting device, or to cause peeling / cracking in the semiconductor layer, thereby preventing the entire semiconductor light emitting device from being destroyed.

The peeling member may have a thickness of 0.5 μm to 1 μm.

  One n-side protruding electrode and a plurality of p-side protruding electrodes, the p-side protruding electrode surrounding the n-side protruding electrode, and the peeling member between the n-side protruding electrode and the p-side protruding electrode May be arranged.

  As described above, since the semiconductor light emitting device of the present invention includes the release layer between the protruding electrodes, when the semiconductor light emitting device including the semiconductor light emitting device is mounted on the mother substrate, the semiconductor light emitting device is interposed between the semiconductor light emitting device and the circuit substrate. Even if the coating resin shrinks, partial peeling of the peeling member can prevent the semiconductor light emitting element from being totally destroyed.

The figure which shows the structure of the LED die in 1st Embodiment of this invention. Sectional drawing of the state which mounted the LED die shown in FIG. 1 on the circuit board. The figure which shows the external shape of the LED die in 2nd Embodiment of this invention. Sectional drawing of the state which mounted the LED die shown in FIG. 3 on the circuit board. The figure which shows the positional relationship of the bottom face of the LED die shown in FIG. 3, and the internal connection electrode of the circuit board shown in FIG. Sectional drawing of the conventional LED device. Sectional drawing of the conventional semiconductor 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. Furthermore, the relationship with the invention specific matter described in the claims is described in parentheses.
(First embodiment)

  The LED die 10 (semiconductor light emitting element) in the first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a view showing the structure of the LED die 10, where (a) is a cross-sectional view and (b) is a bottom view. (A) is a sectional view of the LED die 10 drawn along the EE line of (b). As shown in (a), an n-type semiconductor layer 12 is formed under the sapphire substrate 11, and a p-type semiconductor layer 13 is formed on a part of the lower surface of the n-type semiconductor layer 12. The n-type semiconductor layer 12 and the p-type semiconductor layer 13 are covered with an insulating film 14 having two openings. A p-side protruding electrode 16 connected to the p-type semiconductor layer 13 and an n-side protruding electrode 17 connected to the n-type semiconductor layer 12 are provided in the opening of the insulating film 14. The n-side protruding electrode 17 partially overlaps the p-type semiconductor layer 13 via the insulating film 14 in order to increase the planar size. A peeling member 15 is disposed on the lower surface of the insulating film 14 between the p-side protruding electrode 16 and the n-side protruding electrode 17.

  Next, a bottom view of (b) will be described. When the LED die 10 is viewed from the bottom side, the insulating film 14 can be seen on the outer periphery. A p-side protruding electrode 16 and an n-side protruding electrode 17 are provided in a region inside the insulating film 14, and a peeling member 15 is provided between the p-side protruding electrode 16 and the n-side protruding electrode 17. Note that since the p-type semiconductor layer 13 and the n-type semiconductor layer 12 shown in (a) are covered with the insulating film 14, the p-type semiconductor layer 13 and the n-type semiconductor layer 12 are not shown directly. There is no peeling member 15 in the periphery of the resulting semiconductor layer.

The sapphire substrate 11 is a transparent insulating substrate and has a thickness of 80 to 120 μm. The n-type semiconductor layer 12 includes a GaN buffer layer and an n-type GaN layer and has a thickness of about 5 μm. The p-type semiconductor layer 13 includes a metal multilayer film including a reflective layer, an atomic diffusion preventing layer, and the like and a p-type GaN layer, and has a thickness of about 1 μm. Although not shown, the light emitting layer is at the boundary between the p-type semiconductor layer 13 and the n-type semiconductor layer 12, and the planar shape is substantially the same as that of the p-type semiconductor layer 13. The insulating film 14 is made of SiO2, and has a thickness of about several hundred nm to 1 μm. The p-side and n-side protruding electrodes 16 and 17 are bumps having Au or Cu as a core, and are formed by electrolytic plating and have a thickness of about 10 to 30 μm. The p-side and n-side protruding electrodes 16 and 17 may be solder bumps formed by printing and heat treatment. The peeling member 15 is a polyimide resin, and can be easily peeled when the thickness is about 0.5 to 1 μm. The peeling member 15 is formed by printing or spraying on the wafer before cutting into the LED die 10 using a mask. Further, the release member 15 may be a release agent mainly composed of a silicone resin.

  The LED device 20 will be described with reference to FIG. FIG. 2 is a cross-sectional view of the LED device 20. In the LED device 20, the LED die 10 is flip-chip mounted on a circuit board 28 and covered with a fluorescent resin 21 (covering resin) together with the upper surface of the circuit board 28. Internal connection electrodes 22 and 25 and external connection electrodes 24 and 27 are formed on the upper and lower surfaces of the circuit board 28, respectively. The internal connection electrodes 22 and 25 are connected to the p-side and n-side protruding electrodes 16 and 17 of the LED die 10 and further connected to the external connection electrodes 24 and 27 through the through-hole electrodes 23 and 26.

  The material of the circuit board 28 is selected from ceramics, metal, and resin in consideration of reflectivity, thermal conductivity, heat resistance, light resistance, and the like. The internal connection electrodes 22 and 25 and the external connection electrodes 24 and 27 are Ni and Au plated copper foils. In particular, when the circuit board 28 is made of resin, the internal connection electrodes 22 and 25 should be about 30 to 50 μm thick and the through-hole electrodes 23 and 26 should be filled with a metal paste in order to increase thermal conductivity. . The diameters of the through-hole electrodes 23 and 26 are about 100 to 200 μm. The fluorescent resin 21 is obtained by kneading a phosphor in a silicone resin.

  Next, a mechanism for preventing destruction of the LED die 10 by the peeling member 15 will be described with reference to FIG. When heated by solder reflow or the like and then cooled, the fluorescent resin 21 present under the peeling member 15 first tries to expand and then contracts. If the interface included in the LED die 10 or the circuit board 28 can withstand the expansion of the fluorescent resin 21, the peeling member 15 peels from the insulating film 14 or the fluorescent resin 21 when contracting. As a result, the p-type and n-type semiconductor layers 13 and 12 do not peel at the bottom surface of the LED die 10. In this embodiment, the release member 15 is made of polyimide resin. However, since the adhesive force is weak at the interface between the previously cured silicone resin and the newly applied silicone resin, the release member 15 should be made of silicone resin. Is also possible.

  In the LED die 10 of this embodiment, even if the fluorescent resin 21 contracts on the bottom surface of the LED die 10, the LED die 10 bottom surface and the fluorescent resin 21 are separated by the peeling member 15 to prevent the LED device 20 from being broken. It was. As another means for preventing destruction due to peeling, the peeling member 15 may be disposed between the circuit board 28 and the fluorescent resin 21 in FIG. However, in this case, when the circuit board 28 is replaced with another circuit board, the shape and arrangement position of the peeling member must be redesigned. In other words, the provision of the peeling member 15 on the LED die 10 side as in the present embodiment is more versatile because the redesign of the peeling member 15 is not required for changing the circuit board.

  As another means for preventing peeling of the bottom surface of the LED die 10 at the time of flip chip mounting, the thicknesses of the p-side and n-side protruding electrodes 16 and 17 or the internal connection electrodes 22 and 25 of the circuit board 28 are reduced. The amount of expansion / contraction of the fluorescent resin 21 on the bottom surface may be reduced. A high effect can be obtained by combining the means of this embodiment and these means. However, if the p-side and n-side protruding electrodes 16 and 17 are thinned, the margin for dust and stress is reduced. As described above, when the thickness of the internal connection electrodes 22 and 25 is reduced, the thermal conductivity may be deteriorated.

  As shown in FIG. 1B, there is no peeling member in the periphery of the bottom surface of the LED die 10. Even if there is a peeling member on the entire bottom surface excluding the p-side and n-side protruding electrodes 16 and 17, the function of preventing breakage can be maintained. However, if there is no peeling member around the bottom surface of the LED die 10, the adhesion between the fluorescent resin 21 and the insulating film 14 is improved, so that the protection against harmful substances such as moisture entering from the outside can be enhanced.

The method of providing the peeling member 15 on the bottom surface of the LED die 10 as in this embodiment is also effective for a semiconductor element in which a large number of elements are formed on a silicon substrate. However, since the LED die 10 has a semiconductor layer formed on the lower surface of the sapphire substrate 11, the semiconductor layer is easily peeled off or broken, so that the effect of the peeling member 15 appears greatly.
(Second Embodiment)

  When the planar size of the LED die is increased, a plurality of p-side protruding electrodes may be arranged around the n-side protruding electrode in order to level the current distribution and improve the light emission efficiency. Therefore, an LED die 30 in which a small n-side protruding electrode 37 is surrounded by four p-side protruding electrodes 36a to 36d will be described as a second embodiment of the present invention with reference to FIGS.

  First, the structure of the LED die 30 will be described with reference to FIG. 3A and 3B are diagrams showing the structure of the LED die 30, wherein FIG. 3A is a cross-sectional view and FIG. 3B is a bottom view. Note that (a) is a cross-sectional view of the LED die 30 drawn along the FF line of (b). As shown in (a), an n-type semiconductor layer 32 is formed under the sapphire substrate 31, and a p-type semiconductor layer 33 is formed on a part of the lower surface of the n-type semiconductor layer 32. The p-type semiconductor layer 33 has an opening at the center. The n-type semiconductor layer 32 and the p-type semiconductor layer 33 are covered with an insulating film 34, and three openings can be seen in the insulating film 34. The p-side protruding electrodes 36 a and 36 b are connected to the p-type semiconductor layer 33 in the left and right openings of the insulating film 34, and the n-side protruding electrode 37 is connected to the n-type semiconductor layer 32 in the central opening. A peeling member 35 is disposed between the p-side protruding electrodes 36 a and 36 b and the n-side protruding electrode 37 and on the lower surface of the insulating film 34. Note that a peeling member enters a gap between the n-side protruding electrode 37 and the insulating film 34.

  Next, a bottom view of (b) will be described. When the LED die 30 is viewed from the bottom side, the insulating film 34 can be seen on the outer periphery. There are four p-side protruding electrodes 36a, 36b, 36c, 36d at the corners of the inner region of the insulating film 34, and an n-side protruding electrode 37 at the center of the bottom surface. The p-side protruding electrodes 36 a to 36 d surround the n-side protruding electrode 37, and the peeling member 35 is provided between the p-side protruding electrodes 36 a to 36 d and the n-side protruding electrode 37. Each member of the LED die 30 has the same material and thickness as the LED die 10 shown in FIG.

  Next, the LED device 40 will be described with reference to FIG. FIG. 4 is a cross-sectional view of the LED device 40. In the LED device 40, the LED die 30 is flip-chip mounted on the circuit board 48 and covered with a fluorescent resin 41 (covering resin) together with the upper surface of the circuit board 48. Internal connection electrodes 42 and 45 and external connection electrodes 44 and 47 are formed on the upper and lower surfaces of the circuit board 48, respectively. The internal connection electrode 42 is connected to the p-side protruding electrodes 36 a and 36 b of the LED die 30, and the internal connection electrode 45 is connected to the n-side protruding electrode 37. Although the internal connection electrode 42 is separated in the drawing, it is connected in front of the drawing. Further, the internal connection electrode 42 and the external connection electrode 44 are connected by a through-hole electrode 43, and the internal connection electrode 45 and the external connection electrode 47 are connected through a through-hole electrode (not shown). The material and thickness of the circuit board 48 and the electrode formed on the circuit board 48 are the same as the material and thickness of the circuit board 28 and the electrode formed on the circuit board 28 shown in FIG.

Next, a mechanism for preventing the destruction of the LED die 30 by the peeling member 35 will be described with reference to FIG. FIG. 5 is a bottom view of the LED device 40 shown in FIG. 4 with the external connection electrodes 44 and 47, the through-hole electrode 43, and the circuit board 48 removed, and the LED die 30 and its peripheral portion are connected to the internal connection electrodes. It was seen over 42,45. In the drawing, the outer shape of the LED die 30, the outer shapes of the p-side protruding electrodes 36a to 36d, the n-side protruding electrode 37, and the peeling member 35 are indicated by dotted lines. In FIG. 5, the p-side internal connection electrode 42 occupies a large area, and there is a central portion and a cutout portion thereabove. The notch has an n-side internal connection electrode 45. In the drawing, the peeling member 35 can be seen from the notch, and the insulating film 34 and the fluorescent resin 41 can be seen on the upper part. Note that the fluorescent resin 41 existing between the LED die 30 (see FIG. 4) and the circuit board 48 (see FIG. 4) in the notch is not shown.

  When heated by solder reflow, the fluorescent resin (not shown) in the region seen from the notch expands greatly due to the absence of the internal connection electrodes 42 and 45, and when cooled, the fluorescent resin contracts greatly. At this time, peeling may occur in the peeling member 35, but the semiconductor layers (the n-type semiconductor layer 32 and the p-type semiconductor layer 33, see FIG. 4) are not destroyed. Even in the area around the LED die 30 where the insulating film 34 can be seen, the internal connection electrodes 42 and 45 are not present, so that the fluorescent resin 21 (not shown) tends to expand and contract. The stress disperses because it is close to the region without the bottom surface.

10, 30 ... LED die (semiconductor light emitting element),
11, 31 ... sapphire substrate,
12, 32 ... n-type semiconductor layer,
13, 33 ... p-type semiconductor layer,
14, 34 ... insulating film,
16, 36a, 36b, 36c, 36d ... p-side protruding electrode,
17, 37 ... n-side protruding electrode,
20, 40 ... LED device (semiconductor light emitting device),
21, 41 ... fluorescent resin (coating resin),
22, 25, 42, 45 ... internal connection electrodes,
23, 26, 43 ... through-hole electrodes,
24, 27, 44, 47 ... external connection electrodes,
28, 48 ... Circuit board.

Claims (3)

In a semiconductor light emitting device that is flip-chip mounted on a circuit board of a semiconductor light emitting device and covered with a coating resin,
a p-type semiconductor layer and an n-type semiconductor layer;
An insulating film covering the p-type semiconductor layer and the n-type semiconductor layer;
A p-side protruding electrode and an n-side protruding electrode connected to the p-type semiconductor layer and the n-type semiconductor layer through the opening of the insulating film;
A peeling member provided so as to contact the insulating film between the p-side protruding electrode and the n-side protruding electrode;
The p-side protruding electrode and the n-side protruding electrode protrude from the insulating film, and at least one of the p-side protruding electrode or the n-side protruding electrode partially overlaps the insulating film in a plane,
The semiconductor light emitting element, wherein the peeling member does not exist in a peripheral portion of the insulating film and does not overlap with the p-side protruding electrode and the n-side protruding electrode in a planar manner. The semiconductor light emitting element according to claim 1, wherein the peeling member has a thickness of 0.5 μm to 1 μm. One n-side protruding electrode and a plurality of p-side protruding electrodes, the p-side protruding electrode surrounding the n-side protruding electrode, and the peeling member between the n-side protruding electrode and the p-side protruding electrode The semiconductor light emitting element according to claim 1, wherein the semiconductor light emitting element is arranged.

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