JPS6267887A - Semiconductor light emitting device - Google Patents

Abstract

PURPOSE:To reduce the cost by forming a thick polyimide system resin layer on the LED chip surface, and fixing a lens in a recess provided in the polyimide system resin layer, thereby enabling a ball lens to be attached with high positional precision and good reproducibility. CONSTITUTION:On an n-side ohmic electrode 18 a polyimide resin film 19 having a thickness of about 50mum is formed, and a recess 20 aligning with the window for taking out light is formed in the polyimide resin film. In the position of this recess 20, a ball lens 21 is set utilizing the step thereof, and is bonded and fixed through a transparent resin 22. This eliminates the need for thickening the metal electrode 18 or growing a GaAs layer of a thick film thickness, thereby greatly reducing the cost.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a semiconductor light emitting device, and more particularly to an improvement in a light emitting diode that uses a ball lens to provide narrow directivity.

[Technical background of the invention]

Light emitting diodes (LEDs) used as light sources for optical communications and LEDs used as light sources for automatic focusing mechanisms of cameras are required to have narrow directivity, so a ball lens is attached to the light extraction surface of the LED chip.

In this case, it is important to achieve accurate alignment when attaching the ball lens.

Therefore, in order to improve the positional accuracy of the ball lens with respect to the light emitting part of the LED chip, a structure shown in FIG. 2 has been conventionally adopted (Japanese Patent Laid-Open No. 6O-9181).

In the figure, 1 and 2 are p-type GaALAs layers, and 3.4 is an ILll GaAAAs layer. A SlO□ film 5 is formed on the back surface of the p-type GaAAAs layer 1, and an Au film 5 is further formed in ohmic contact with the pfji layer 1 through a contact hole.
A Zn electrode 6 is formed. Further, an electrode 7 is directly formed on the surface of the p-type QaAtAs layer 4, and a light extraction hole 8 is formed in the electrode 7. A ball lens 10 is fixed to the light extraction hole 8 with a transparent resin layer 9 interposed therebetween.

In the above case, since the light emitting area of the chip is limited by the contact portion of the electrode 6, the light extraction hole 8 is formed accordingly. In order to improve the accuracy of the mounting position of the ball lens, the electrode 7 on the light extraction side is formed thick to about 40 μm, and the recess step of the light extraction hole 8 is increased.
0 is securely fixed at that position.

In another conventional example, instead of increasing the thickness of the light extraction side electrode 7, a GaAa epitaxial layer of 40 μm is formed.
The lens is grown thickly around m, and a recess is created by etching the lens set position using PEP.

[Problems with background technology]

In the structure of JP-A-60-9181 shown in FIG. 2, a gold/germanium layer/silver plating layer/gold plating layer are sequentially formed as the electrode 7 on the light extraction side. At this time, the film thicknesses were 30 μm for the silver plating layer and 10 μm for the gold plating layer, which were significantly thicker than the approximately 2 μm for a normal ohmic electrode, which caused the problem of a significant increase in cost.

On the other hand, a method in which a thick GaA epitaxial growth layer is formed instead of increasing the thickness of the electrode 7 has the following problems.

That is, by liquid phase epitaxial growth, G
When forming the aAs layer, variations of ±5 μm or more usually occur, so if the GaAa epitaxial layer is thin, the ball lens will not be stable, the optical output will decrease, and the yield will deteriorate.

Furthermore, the liquid phase epitaxial growth process must be performed more than once than in the normal case, which increases costs.

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and provides a structure that allows a ball lens to be attached to the surface of an LED chip with high positional accuracy and good reproducibility, and also achieves a reduction in manufacturing costs.

[Summary of the invention]

In the semiconductor light emitting device according to the present invention, in order to fix the ball lens on the surface of the LED chip, a thick polyimide resin layer with a thickness of 50 μra is formed, and the ball lens is fixed in the recess provided in the polyimide resin layer. .

The polyimide resin layer can be easily formed into a thick film using a spinner, and can be cured at a low temperature of 300° C. or lower. Furthermore, the recess for fixing the ball lens can be easily formed using PEP. Therefore, compared to the case where the electrode metal film is made thicker to form a recess sufficient to securely fix the ball lens or a new thick epitaxial layer is formed, the cost is significantly reduced. It also has good reproducibility.

Note that when a transparent resin layer is used as the polyimide resin layer, light leakage occurs, resulting in poor directivity. Therefore, it is desirable to further coat a non-light-transmitting resin film thereon or evaporate a metal such as aluminum to prevent light leakage, if necessary.

[Embodiments of the invention]

FIG. 1 is a sectional view of an LED according to an embodiment of the present invention. In the figure, 1 is a p-type QaAs+ substrate. The G
&AJ On the substrate is an n-type GaAs layer 1 with a thickness of about 5 μm.
2 was grown using a liquid phase epitaxial growth source (LPE). A pm region 13 is formed in this n Wjl GaAs layer 12 by selective diffusion of an accessor impurity such as Zn using a mask such as SIN (F). 2nd base area 1
The A-shaped head region 12 around the 3rd layer functions as a current narrowing layer. On this GaAs layer 12°13, p-GaAtAs
Cladding layer 14, p-type GaAtAa active layer 15, n-type G
The aALAs cladding layer 16 is formed by laminating layers using LPE.

After forming the stacked structure of semiconductor layers as described above, AuB
A p-side ohmic electrode 17 made of * and an n-side ohmic electrode 18 made of AuG are formed. this house,
A light extraction window is formed in the n-side ohmic electrode 18 at a position corresponding to the p-type head region 13 using PEP.

A polyimide resin film 19 having a thickness of about 50 μm is formed on the n-side ohmic electrode 18, and a recess 20 aligned with the light extraction window is formed in the polyimide resin film. This polyimide resin film 19 was formed as follows. First, a polyimide resin is applied to a thickness of about 50 μm using a spinner, and after baking at a predetermined temperature, a recess 20 is formed in PEP. Subsequently, it was cured at around 300°C.

In addition, if light leakage occurs, d
After a non-transparent resin is further applied on the IJ imide resin film 19 or a metal such as aluminum is vapor-deposited, the recesses 20 are formed using PEP over the IJ imide resin film 19.

A ball lens 21 is set at the position of the recess 20 of the polyimide resin film 19 formed as described above, making use of the step, and is further adhesively fixed via a transparent resin 22.

In the LED of the above embodiment, there is no need to thicken the metal electrode 18 or grow a thick GaAs layer as in the conventional case, so the cost can be significantly reduced.

Furthermore, by using spinner coating, the polyimide resin film 19 can be formed with a large film thickness and uniformity, so that the alignment accuracy of the ball lens 21 can be further improved compared to the conventional method.

〔Effect of the invention〕

As detailed above, according to the present invention, it is possible to improve the positional accuracy and reproducibility of the ball lens attached to the chip surface in order to obtain narrow directivity of a semiconductor light emitting device, and to reduce costs. It is possible to obtain a remarkable effect.

[Brief explanation of drawings]

FIG. 1 is a sectional view of an LED with a ball lens according to an embodiment of the present invention, and FIG. 2 is a sectional view of a conventional LED with a ball lens. 11- p dispersed GmAm substrate, 12- rs type GaAs
layer, I J ・p mt GmAm region, 14-p type G
ajktAl cladding layer, 15...p base GO shi As
Active layer, 16...n GaAtAm cladding layer, 17
．． 18... Electrode, 19... Polyimide resin film, 2o
...dent, 2z...ball lens, 22...transparent resin adhesive layer.

Claims (1)

[Claims] A relatively thick polyimide resin film is formed on the light extraction side surface of the light emitting diode chip, a recess is formed in the polyimide resin film at a position corresponding to the light emitting area of the light emitting diode, and a recess is formed on the recess. A semiconductor light emitting device characterized by having a ball lens installed and fixed.