JP2014203874A - Flip-chip semiconductor light-emitting element, semiconductor device and manufacturing method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flip-chip semiconductor light-emitting element which is useful in improvement in mounting reliability.SOLUTION: A flip-chip semiconductor light-emitting element comprises: an n-type GaN layer 2, an InGaN/GaN multiquantum well active layer 3 and a p-type GaN layer 4 which are formed on a sapphire substrate 1; a p-side electrode and an n-side electrode 6 which are formed on the p-type GaN layer 4 and the n-type GaN layer 2; an insulation layer 7 which is composed of silicon oxide and formed so as to cover a region other than Au bump adhesion regions of the p-side electrode 5 and the n-side electrode 6; and an uneven surface 1a having large light scattering ability and a flat surface 1b having small light scattering ability, which serve as a light extraction surface and are provided on a top face of the sapphire substrate 1. The flat surface 1b is opposite to at least two boundaries with the p-side electrode 5 and the n-side electrode 6. Boundaries of a conductor pattern of a mounting substrate corresponding to the boundaries with the p-side electrode 5 and the n-side electrode 6 can be checked from above through the flat surface 1b, and as a result, alignment inspection of a semiconductor light-emitting element after face-down mounting with the mounting substrate in an alignment inspection process can be performed promptly and successfully.

Description

  The present invention relates to a flip chip type semiconductor light emitting device, a semiconductor device mounted with the flip chip type semiconductor light emitting device, and a method for manufacturing the same.

  In general, as a method of manufacturing a semiconductor device for mounting a semiconductor element on a mounting substrate, a wire bonding mounting method in which the surface electrode of the semiconductor element and the electrode of the mounting substrate are electrically connected by a wire has been used. A flip-chip mounting method is used in which a flip-chip semiconductor element is face-down mounted on a mounting substrate in which protruding terminals called bumps are bonded in an array (refer to Patent Documents 1 and 2).

  Compared with the wire bonding mounting method, the flip chip mounting method is suitable for mounting high-frequency circuit elements because the wiring length is short and the electrical characteristics are good. Further, it is advantageous in terms of downsizing and thinning, and is suitable for mounting on portable devices. Furthermore, since it has excellent heat dissipation, it is suitable for mounting semiconductor light emitting devices such as light emitting diode (LED) devices and laser diode (LD) devices.

  In the flip chip mounting method described above, as a method of bonding the electrodes of the flip chip type semiconductor light emitting element and the bumps of the mounting substrate, a conductive paste bonding method using a conductive adhesive (paste), eutectic solder and high temperature solder. There are a solder bonding method using, a pressure welding method for applying a load to the bump, an ultrasonic bonding method for applying an ultrasonic wave to the bump, and the like. Among these, the ultrasonic bonding method is generally excellent in cost, bonding reliability, bonding load, bonding pitch accuracy, and the like.

  On the other hand, in the flip-chip type semiconductor light emitting device, in order to improve the light extraction efficiency, a light extraction uneven surface for light scattering is formed on the entire upper surface.

JP 11-340514 A (Patent No. 3531475) JP 2003-110144 A

  However, when the above-described flip-chip type semiconductor light-emitting device is flip-chip mounted on a mounting substrate, it is formed on the entire surface even if the positional relationship between the flip-chip type semiconductor light-emitting device and the mounting substrate is shifted after heating ultrasonic pressure bonding. Due to the light scattering on the light extraction uneven surface, the positional deviation between the flip chip type semiconductor light emitting device electrode and the bump of the mounting substrate, that is, the alignment accuracy between the flip chip type semiconductor light emitting device and the mounting substrate is flip chip type. It cannot be confirmed from the upper surface of the semiconductor light emitting device. Accordingly, the electrodes of the flip-chip type semiconductor light emitting device may be displaced from the bumps of the mounting substrate. As a result, there is a problem in that leakage current is generated and destruction due to current concentration is caused, and reliability after mounting is lowered.

  In order to solve the above-mentioned problems, a flip chip type semiconductor light emitting device according to the present invention is a flip chip type semiconductor light emitting device to be face-down mounted on a mounting substrate, and the mounting substrate of this flip chip type semiconductor light emitting device The light extraction surface on the side not facing the surface is constituted by an uneven surface with large light scattering and a flat surface with small light scattering. Accordingly, after the face-down mounting, the alignment accuracy between the flip chip type semiconductor light emitting device and the mounting substrate is confirmed through a flat surface with a small light scattering of the light extraction surface on the upper surface of the flip chip type semiconductor light emitting device.

  A semiconductor device according to the present invention includes the above-described flip chip type semiconductor light emitting element and a mounting substrate, and the flip chip type semiconductor light emitting element is mounted on the mounting substrate face down.

  Furthermore, the method of manufacturing a semiconductor device according to the present invention includes a light extraction surface forming step of forming an uneven surface having a large light scattering and a flat surface having a small light scattering as a light extraction surface above the flip chip type semiconductor light emitting element, A face-down process in which the lower side of the chip-type semiconductor light-emitting element is face-down mounted on a mounting substrate on which a p-side conductor pattern and an n-side conductor pattern are formed, and the p-side conductor pattern and the n-side conductor of the mounting substrate through a flat surface An alignment inspection process for performing an alignment inspection between the flip chip type semiconductor light emitting element and the mounting substrate by observing the boundary with the pattern, and the flat surface of the flip chip type semiconductor light emitting element is the flip chip type semiconductor light emitting element. It is intended to face at least two boundaries between the p-side electrode and the n-side electrode.

  According to the present invention, the alignment accuracy between the flip-chip type semiconductor light emitting element and the mounting substrate can be confirmed quickly and accurately, and the reliability after mounting can be improved.

It is sectional drawing which shows embodiment of the flip-chip-type semiconductor light-emitting device based on this invention. FIG. 2 is a plan view of an uppermost light extraction surface of the flip chip type semiconductor light emitting device of FIG. 1. FIG. 2 is a plan view of a p-side electrode and an n-side electrode on the lowermost surface of the flip-chip type semiconductor light emitting device of FIG. 1. FIG. 2 is a cross-sectional view of a mounting substrate on which the flip chip type semiconductor light emitting device of FIG. 1 is to be face-down mounted. It is a top view of the conductor pattern of the mounting substrate of FIG. 4 is a flowchart for explaining a method for manufacturing a semiconductor device according to the present invention. It is sectional drawing for demonstrating the bump formation process of FIG. It is sectional drawing for demonstrating the face-down mounting process of FIG. It is a top view for demonstrating the alignment test process of FIG.

  FIG. 1 is a cross-sectional view showing an embodiment of a flip chip type semiconductor light emitting device according to the present invention, and FIGS. 2 and 3 are plan views, p-side electrodes and n of a light extraction surface of the flip chip type semiconductor light emitting device of FIG. It is a top view of a side electrode. 1, 2, and 3 are light emitting diode (LED) elements having a size of 1.0 mm × 1.2 mm and a thickness of 0.1 mm, for example. 1 is a cross-sectional view taken along the line II of FIG. 2 and FIG.

In FIG. 1, a Si-doped n-type GaN layer 2, an InGaN / GaN multiple well (MQW) active layer 3, and an Mg-doped p-type GaN layer 4 are formed on a sapphire substrate 1. A p-side electrode 5 and an n-side electrode 6 made of AgNiTiPtAu are formed on the p-type GaN layer 4 and the n-type GaN layer 2. An insulating layer 7 made of silicon oxide (SiO ₂ ) is formed so as to cover regions other than the Au bump adhesion regions BR1 and BR2 (shown in FIG. 3) of the p-side electrode 5 and the n-side electrode 6.

  Referring also to FIGS. 2 and 3, the upper surface of the sapphire substrate 1 is provided with a concavo-convex surface 1 a having a large light scattering functioning as a light extraction surface and a flat surface 1 b having a small light scattering. Through this flat surface 1b, the boundary of the conductor pattern of the mounting substrate corresponding to the boundary 8 between the p-side electrode 5 and the n-side electrode 6 can be confirmed from above. As a result, in the alignment inspection process described later, The alignment inspection between the semiconductor light emitting element and the mounting substrate can be performed quickly and accurately.

  The flat surface 1b may be provided to face the boundary of at least one n-side electrode 6 or p-side electrode 5 depending on the shape. More desirably, it may be provided opposite to the boundary between at least two n-side electrode 6 or p-side electrode 5. When the top view shape of the semiconductor light emitting device is divided into four quadrants by a diagonal line or a center line, it is preferable that the flat surface 1b belongs to different quadrants because the alignment in the x direction, the y direction, and the θ angle direction can be easily aligned. . For example, as shown in FIG. 2, it may be provided to face two n-side electrodes 6 having the same distance D from the center of gravity O of the semiconductor light emitting element.

  The area of the flat surface 1b is preferably 10% or less with respect to the entire area of the semiconductor light emitting device when viewed from above. This is because the light extraction efficiency of the semiconductor light emitting device cannot be increased if the value exceeds this.

  4 is a cross-sectional view of a mounting substrate on which the semiconductor light emitting device of FIGS. 1 to 3 is mounted face down, and FIG. 5 is a top view of the mounting substrate of FIG. 4 is a cross-sectional view taken along line IV-IV in FIG.

  As shown in FIGS. 4 and 5, a p-side conductor pattern 12 and an n-side conductor pattern 13 connected to the p-side electrode 5 and the n-side electrode 6 of the semiconductor light emitting element are formed on the mounting substrate 11. ing. In this case, the p-side conductor pattern 12 and the n-side conductor pattern 13 are electrically separated. The boundary 8 between the p-side electrode 5 and the n-side electrode 6 in FIG. 3 faces the boundary 14 between the p-side conductor pattern 12 and the n-side conductor pattern 13. The p-side conductor pattern 12 is provided with a bump bonding region R1 to which an after-mentioned Au bump B1 is bonded, while the n-side conductor pattern 13 is provided with a bump bonding region R2 to which an after-mentioned Au bump B2 is bonded. Is provided.

  Next, a method of manufacturing a semiconductor device including the flip-chip type semiconductor light emitting device of FIGS. 1, 2, and 3 and the mounting substrate of FIGS. 4 and 5 will be described with reference to FIG.

  First, in step 601, the flip chip type semiconductor light emitting device of FIGS. 1, 2, and 3 before the formation of the uneven surface 1a having a large light scattering as the light extraction surface and the flat surface 1b having a small light scattering is used as a normal one. Form by the method. That is, the n-type GaN layer 2, the InGaN / GaN MQW active layer 3 and the p-type GaN layer 4 are formed on the sapphire substrate 1 by the epitaxial growth method, and then the p-side electrode 5 and the n-side electrode 6 are formed.

  Next, in step 602, a silicon oxide pattern is formed on the sapphire substrate 1 by a CVD method / etching method. This silicon oxide pattern has an annular shape with a width of 20 μm, which is the difference between a circle with a diameter of 120 μm and a circle with a diameter of 140 μm with respect to the center of the two n-side electrodes 6 corresponding to the flat surface 1b. Next, the uneven surface 1a is formed by wet etching with buffered hydrofluoric acid using this silicon oxide pattern as a mask. Next, the silicon oxide pattern is removed to expose the flat surface 1b. The uneven surface 1a can also be formed by a lift-off method, a press method such as imprint, or a wet blast method.

  On the other hand, at step 603, as shown in FIG. 7, Au bumps B1 and B2 (B2 in FIG. 7) are formed on the bump bonding region R1 of the p-side conductor pattern 12 and the bump bonding region R2 of the n-side conductor pattern 13 of the mounting substrate 11. (Only shown) is bonded by a pressure ultrasonic method. In this case, ten Au bumps B1 are provided for the p-side conductor pattern 12, and six Au bumps B2 are provided for the n-side conductor pattern 13. The Au bumps B1 and B2 after mounting the semiconductor light emitting element have a diameter of about 80 μm and a height of about 20 μm. The diameters and heights of the Au bumps B1 and B2 vary depending on the crushing amount when the semiconductor light emitting device is mounted, but may be higher than 20 μm, for example, about 30 μm.

  Next, referring to Steps 604 to 606, as shown in FIG. 8, a flip-chip type semiconductor light emitting device in which the uneven surface 1a and the flat surface 1b are formed on the mounting substrate 11 on which the Au bumps B1 and B2 of FIG. 7 are formed. Implement face down. Hereinafter, steps 604 to 607 will be described in detail.

  In step 604, the n-side electrode 6 of the flip-chip type semiconductor light emitting element, the Au bump B2 of the mounting substrate, and the n-side conductor pattern 13 are recognized.

  Next, in step 605, based on the result of image recognition in step 604, as shown in FIG. 8, the flip chip type semiconductor light emitting element is superimposed on the mounting substrate.

  Next, in step 606, heating and pressure bonding are performed with ultrasonic waves, and the face-down mounting process is completed. At this time, the positional relationship between the flip chip type semiconductor light emitting element and the mounting substrate may be shifted.

  Finally, in step 607, alignment inspection between the flip chip type semiconductor light emitting element and the mounting substrate is performed. That is, the alignment in the X direction, the Y direction, and the θ angle direction between the n-side electrode 6 of the flip chip type semiconductor light emitting element and the Au bump B2 on the mounting substrate 11 is inspected with a microscope from the flat surface 1b of the light extraction surface. At this time, the alignment inspection is actually performed based on whether or not the boundary between the conductor patterns 12 and 13 of the mounting substrate 11 can be observed at the correct position with respect to the flat surface 1b of the flip-chip type semiconductor light emitting device. As a result, as shown in FIG. 9A, if the boundary 14 of the conductor patterns 12 and 13 is observed at the correct position with respect to the flat surface 1b, the Au bump B2 is formed on the n-side electrode 6 of the flip-chip type semiconductor light emitting device. It is considered that they are correctly facing each other. As a result, it is determined that the alignment inspection has passed, and the process proceeds to a subsequent process in step 608. On the other hand, as shown in FIGS. 9B and 9C, if the boundary 14 of the conductor patterns 12 and 13 is shifted from the flat surface 1b and observed at an incorrect position, the Au bump B2 is flip-chip type semiconductor light emitting device. The n-side electrode 6 is considered not to be correctly opposed. As a result, the alignment inspection is rejected, and in step 609, the crimped body between the flip chip type semiconductor light emitting element and the mounting substrate is discarded.

  In the above embodiment, the uneven surface and the flat surface of the light extraction surface are formed on the sapphire substrate. However, when the sapphire substrate is removed, the uneven surface and the flat surface of the light extraction surface are formed on the n-type GaN layer. Form a surface. Further, the growth substrate can be a GaN substrate instead of the sapphire substrate.

  Further, the present invention can be applied to various modifications within the obvious range of the above-described embodiment.

1: Sapphire substrate 2: n-type GaN layer 3: InGaN / GaN multiple well (MQW) active layer 4: p-type GaN layer 5: p-side electrode 6: n-side electrode 7: insulating layer 8: boundary 11: mounting substrate 12 : P-side conductor pattern 13: n-side conductor pattern 14: boundary
B1, B2: Bump
BR1, BR2: Bump adhesion area
R1, R2: Bump bonding area

Claims (7)

A flip chip type semiconductor light emitting device to be mounted face down on a mounting substrate,
A flip chip type semiconductor light emitting device comprising a light extraction surface on the side not facing the mounting substrate of the flip chip type semiconductor light emitting device, having an uneven surface with large light scattering and a flat surface with small light scattering.   2. The flip chip type semiconductor light emitting device according to claim 1, wherein the flat surface is formed to face at least one boundary of the p side electrode or the n side electrode of the flip chip type semiconductor light emitting device.   3. The flip-chip type semiconductor light emitting device according to claim 2, wherein the flat surface is formed to face at least two boundaries of the p-side electrode and the n-side electrode of the flip-chip type semiconductor light emitting device.   The semiconductor light-emitting element is a quadrangle when viewed from the normal direction of the mounting substrate, and when divided into four quadrants by its diagonal or center line, the boundary between the two locations belongs to different quadrants. 4. The flip-chip type semiconductor light emitting device according to 3.   2. The flip-chip type semiconductor light emitting device according to claim 1, wherein an area of the flat surface is 10% or less with respect to an area of the semiconductor light emitting device when viewed from a normal direction of the mounting substrate. The flip-chip type semiconductor light emitting device according to any one of claims 1 to 5,
A mounting substrate, and
The flip chip type semiconductor light emitting element is a semiconductor device mounted face down on the mounting substrate. A light extraction surface forming step of forming an uneven surface having a large light scattering and a flat surface having a small light scattering on the upper side of the flip-chip type semiconductor light emitting element;
A face-down process of face-down mounting the flip-chip type semiconductor light emitting device on a mounting substrate on which a p-side conductor pattern and an n-side conductor pattern are formed;
An alignment inspection step of performing an alignment inspection between the flip-chip type semiconductor light emitting element and the mounting substrate by observing a boundary between the p-side conductor pattern and the n-side conductor pattern of the mounting substrate through the flat surface; Comprising
A method of manufacturing a semiconductor device, wherein the flat surface of the flip-chip type semiconductor light-emitting element faces at least two boundaries between a p-side electrode and an n-side electrode of the flip-chip type semiconductor light-emitting element.

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