JP3362836B2 - Method for manufacturing optical semiconductor device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical semiconductor element used for a short-wavelength LED, a short-wavelength LD (Laser Diode), an optical sensor, a solar cell and the like, and more particularly to a nitride semiconductor on a transparent substrate. The present invention relates to an optical semiconductor device having high light utilization efficiency and a manufacturing method capable of forming the optical semiconductor device with high mass productivity.

[0002]

2. Description of the Related Art Nitride semiconductors (In _X Ga _Y Al _1-XY N,
0 ≦ X, 0 ≦ Y, and X + Y ≦ 1) can be variously formed from a semiconductor having a narrow band gap to a wide band gap. Therefore, there is an emission wavelength L from blue or ultraviolet to orange.
Promising as ED and LD (Laser Diode).
In addition, optical sensors that utilize the characteristics of nitride semiconductors that can be driven even at high temperatures and solar cells with high electromotive force are examples of optical semiconductor elements.

Since it is difficult to form a single crystal in a semiconductor device using such a nitride semiconductor with high mass productivity, MOCVD is usually performed on a sapphire or spinel substrate having a high refractive index of about 1.8 and a small critical refraction angle. There is no choice but to stack nitride semiconductors by using the method.

A nitride semiconductor layered on sapphire or spinel has a heteroepitaxial structure. The nitride semiconductor has a large lattice constant mismatch with a sapphire substrate and the like, and also has a different coefficient of thermal expansion. The sapphire substrate has a crystal structure called a hexagonal system and does not have a cleavage property by its nature. Furthermore, the Mohs hardness of both sapphire and nitride semiconductors is almost 9
And is a very hard substance. Therefore, GaAs and GaP
Unlike other semiconductors, the substrate and semiconductor layer itself are hard. Further, since it is a hetero-epitaxial structure, it cannot be easily formed into various shapes. Furthermore, when the substrate itself has an insulating property, there are many restrictions on the semiconductor layer side.

LE is an example of such an optical semiconductor device.
A method for manufacturing the D chip will be described with reference to FIGS. FIG. 6A shows a buffer layer in which AlN or the like is formed on a sapphire substrate 601 at low temperature, GaN that acts as an n-type contact layer, InGaN that acts as an active layer, GaAlN that acts as a p-type clad layer, and p-type contact layer. Nitride semiconductor 602 and p in which working GaN is laminated
A semiconductor wafer having a structure having electrodes 620 and 621 formed by exposing the mold and the n-type semiconductor by etching or the like is formed (FIG. 6A). Next, a groove 603 for dividing the semiconductor wafer into LED chip sizes is formed by a dicer (FIG. 6).
(B)). A scribe line 604 is put on the bottom surface of the groove 603 (FIG. 6C). A semiconductor wafer is separated by applying pressure along a scribe line 604 with a roller or the like to manufacture an optical semiconductor element 610 (FIG. 6).
(D)). By supplying electric power to each electrode of the optical semiconductor element 610 thus formed, it is possible to form an LED chip capable of emitting visible light having a relatively short wavelength and ultraviolet light.

[0006]

However, at present, an optical semiconductor element having the above-mentioned structure is not sufficient, because an optical semiconductor element such as a light emitting element having a higher luminous efficiency, a light receiving element having a higher conversion efficiency or a higher sensitivity is required. Development of an optical semiconductor device having more excellent characteristics is required. Therefore, the present invention is to provide an optical semiconductor device having high mass productivity and high light utilization efficiency.

[0007]

The present invention provides a transparent substrate (501).
A semiconductor wafer (50) with a nitride semiconductor (502) laminated on top
(0) is divided and formed by the manufacturing method of the optical semiconductor element (510).
is there. In particular, a transparent film facing the laminated surface of the nitride semiconductor (502).
Do not reach the nitride semiconductor (502) from the back side of the optical substrate.
The first groove (503) and the second groove (513) not used for division
The process of forming the first groove portion (503) and the second groove portion (513)
After the formation, the back side of the transparent substrate is polished to obtain a plurality of layers.
To form the curved shape (504) of the first groove (503)
Dividing the semiconductor wafer (100) along
It is a manufacturing method of an optical semiconductor element.

The optical semiconductor element according to claim 2 of the present invention
The manufacturing method is based on the shapes of the first groove part (503) and the second groove part (513).
It is characterized in that it is formed by laser irradiation.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As a result of various experiments, the present inventor has found that an optical semiconductor device having high light utilization efficiency can be formed by forming a transparent substrate on which a nitride semiconductor is laminated into a specific shape. Came to achieve. It has also been found that an optical semiconductor element having the above-described specific shape can be formed relatively easily with good mass productivity simply by adding a polishing step when forming an optical semiconductor element.

According to the present invention, the light-transmissive substrate used for forming a nitride semiconductor is processed into a curved shape, so that the light trapped inside the optical semiconductor element can be efficiently emitted to the outside to improve the light utilization efficiency. It is a thing. Further, by utilizing the groove portion formed at the time of dividing the nitride semiconductor wafer, the curved surface shape described above can be formed with good controllability, so that a nitride semiconductor element having high mass productivity can be formed.

That is, an optical semiconductor device 6 as shown in FIG.
In the shape of the light emitting element of 10, a part of the emission wavelength emitted from the nitride semiconductor layer goes to the back surface side of the substrate. These lights may have a substantially rectangular parallelepiped shape,
Light is not emitted to the outside of the nitride semiconductor device by causing critical angle reflection in the substrate. Some of them cause absorption loss in the substrate even if they are released to the outside. Similarly, it is considered that the light-receiving element cannot be efficiently absorbed by the nitride semiconductor layer due to total reflection of light from the outside.

According to the present invention, as shown in FIG. 2, the back surface side of the optical semiconductor element has a curved surface shape 204 so as to have a lens effect, so that the semiconductor layer 202 emits light and the light directed to the back surface is prevented from being reflected at a critical angle, so that the light is efficiently emitted. Take out. Alternatively, it is possible to prevent the critical angle reflection of the received light wavelength which is about to enter from the back surface side and efficiently collect and capture the light. That is, the critical angle refractive index is increased by changing the shape of the transparent substrate 201 to improve the light utilization efficiency.

Further, according to the present invention, the above-mentioned optical semiconductor element 110 can be formed with high mass productivity by utilizing the groove portion 103 used when dividing the optical semiconductor element 110 from the semiconductor wafer 100 as shown in FIG. . That is,
Translucent substrate 10 used when dividing a semiconductor wafer 100
By polishing the groove portion 103 provided in No. 1, a desired curved surface shape 104 can be formed with good controllability and mass productivity can be improved. Hereinafter, a configuration example of the present invention will be shown.

Specifically, as a light emitting device, a GaN buffer layer is formed on the surface of a sapphire substrate whose back surface is made into a concave lens shape by polishing. N-type GaN contact layer on the buffer layer, undoped InGa
By stacking a light emitting layer made of N, a clad layer made of p-type AlGaN, and a contact layer made of p-type GaN, it is possible to form a light emitting diode having light diffusivity and high light utilization efficiency.

Similarly, as a light receiving element, specifically, a GaN buffer layer is formed on the surface of a spinel substrate having a convex lens shape by polishing the back surface side. It is also possible to form an optical sensor having high photosensitivity by forming a pair of counter electrodes on the n-type GaN on the buffer layer. Hereinafter, the configuration of the present invention will be described in detail.

(Optical semiconductor elements 110, 210, 310,
410, 510) The optical semiconductor device of the present invention means a nitride semiconductor (In _X Ga _Y Al _1-XY N, 0 on a transparent substrate 101.
≦ X, 0 ≦ Y, X + Y ≦ 1) 102 is formed and functions as a photoelectric conversion element. Nitride semiconductor 102
Can be formed on the translucent substrate by using the MOCVD method or the HVPE method. By using a buffer layer of GaN, AlN, GaAlN or the like formed at a low temperature on the transparent substrate, the crystallinity of the nitride semiconductor formed thereon can be further improved. If the nitride semiconductor is formed as it is, a semiconductor having n-type conductivity can be formed. In order to obtain an n-type semiconductor having a desired resistivity or the like, it can be formed by doping an n-type impurity such as Si, Ge, C or Ti.

On the other hand, the nitride semiconductor is M as a p-type impurity.
It is difficult to achieve p-type by only doping g, Zn, Be, Ca, Sr, and Ba. In order to obtain a p-type semiconductor having a low resistance, it is possible to make it a p-type by annealing at a temperature of 400 ° C. or higher or by irradiating with an electron beam after doping a p-type impurity. A nitride semiconductor is optionally p-type, i
Can be formed as a light-emitting element or a light-receiving element by stacking a plurality of p-type and n-type layers to form a Schottky junction, a MIS junction, a PIN junction, a pn junction, or the like.

As a substrate on which such a nitride semiconductor is formed, silicon carbide, gallium nitride, zinc oxide, sapphire, spinel, etc. may be mentioned. Considering mass productivity and crystallinity of a nitride semiconductor to be formed thereafter. A transparent insulating substrate such as sapphire or spinel is preferable.

The optical semiconductor element 110 can be formed by forming a groove portion 103 in the transparent substrate 101 of the nitride semiconductor wafer 100, and then forming a break line 105 by a laser or a scriber and dividing the break line 105 by an external force. it can. Therefore, the groove 103 may be formed after forming the curved surface shape of the rear surface side 152 of the transparent substrate having a lens effect, or may be formed by utilizing the groove 103.

When the curved surface shape 104 is formed using the groove 103, the optical semiconductor element 110 of the present invention can be easily formed with good mass productivity.

The curved surface 104 having the lens effect on the rear surface 152 side of the transparent substrate may be one in which only the end portion of the transparent substrate 101 is curved to form a square or a rectangle without an edge when observed from the substrate side. Alternatively, the shape may be circular, elliptical, or the like with a remarkable lens effect. In addition, it is possible to select variously those having a lens effect, such as a convex lens shape and a concave lens shape.

When the light-transmissive substrate of the optical semiconductor element 110 has a lens effect, especially the electrode 12 of the optical semiconductor element 110.
0 can be effectively used for reflection of light. Therefore, gold, aluminum, and
Various metal oxides such as platinum, various alloys, and ITO can be selected. When it is made of metal, it can be used as the reflective film 120 having low transmittance and high reflectivity and the transparent electrode 320 having high transmittance by adjusting the film thickness.

Curved shape 3 of optical semiconductor elements 310 and 410
As the reflection films 309 and 409 formed on 04,
Any material can be used as long as it efficiently reflects the light emitted or received by the nitride semiconductor 302, and may be formed of an alloy or a dielectric multilayer film in addition to a metal such as gold, silver, copper or aluminum.

(Grooves 103, 303, 503, 513 formed on the nitride semiconductor wafer) Semiconductor laminated surface side 15
1 to the semiconductor layer 10 from the rear surface 152 of the transparent substrate facing the transparent substrate.
The groove portion 103 that does not reach 2 is polished so that the transparent substrate 10
It is used to form a curved surface 104 on the back surface of 1.
At least a part of the groove 103 can be suitably used for dividing the nitride semiconductor wafer 100 into the nitride semiconductor device 110 later.

In the present invention, the groove portion 103 provided in the transparent substrate 101 can also be used to form the curved surface shape 104. In particular, the curved surface shape 104 can be controlled by the distance between the groove portions 103 provided and the depth of the groove portions.

Specifically, even if the back surface is polished in the same manner, the size of the portion (projection) other than the groove is constant and the width of the groove is changed, or the portion of the groove other than the groove (convex) is constant. The polishing rate varies depending on the size of the (part). If the width of the portion (convex portion) other than the groove portion is constant and the interval between the groove portions is widened, the polishing rate tends to increase as the width increases. Further, the narrower the width of the groove portion (the higher the occupation ratio of the convex portion), the lower the polishing efficiency of the convex portion, but the better the selectivity. Similarly, as the width of the groove is constant and the size of the portion (projection) other than the groove becomes smaller, the polishing rate tends to become faster.

Since it is considered that the difference occurs depending on the polishing pressure distribution due to polishing, the curved surface of the transparent substrate can be formed as desired depending on the width, interval and depth of the groove. The curved surface of the translucent substrate can be formed into a desired curved surface shape by polishing the size and depth of the groove and the like. The curved surface shape of the transparent substrate may be a convex lens shape or a concave lens shape. Further, various curved surfaces such as a perfect circle shape and an elliptical shape can be formed when viewed from the emission observation surface side.

When the groove is formed by a dicer,
The width of the groove is preferably 15 to 35 μm, more preferably 20 to 25 μm. When the width of the groove is narrower than 15 μm, the dicing edge of the dicer becomes large and it is difficult to form the groove uniformly. Also, the larger the width of the groove, the smaller the number of nitride semiconductor elements that can be divided from the semiconductor wafer, and the worse the mass productivity. Further, the depth of the groove portion used for separating the semiconductor wafer is preferably 20 μm or more in order to divide the semiconductor wafer into smooth end faces. In particular, it is preferable that the gap between the bottom surface of the groove and the surface on the semiconductor laminated surface side be substantially uniform within the range of 30 to 100 μm.

In order to make the width of the groove smaller and deeper, the groove can be formed on the sapphire substrate or spinel substrate by a laser processing machine. As such a laser processing machine, a YAG laser, an excimer laser or a CO ₂ laser can be preferably used. In particular, the YAG laser can form the groove portion with little deterioration of heat. Further, since the CO ₂ laser can improve the output, it is excellent in forming a larger and deeper groove. The shape of the laser-irradiated surface irradiated by the laser processing machine can be adjusted to a desired shape such as a perfect circle, an ellipse or a rectangle by passing it through a filter.

When the groove is formed by a laser processing machine, the laser irradiation device itself may be moved, or only the laser to be irradiated may be scanned by a mirror or the like to form the groove. Further, by moving the stage for holding the semiconductor wafer in various directions in the horizontal direction, it is possible to form the groove portion having a desired depth in the desired vertical and horizontal directions.

(Polishing) When a substrate having a rectangular cross-sectional shape is polished, the rectangular edge portion is particularly polished, resulting in a shape in which the corners are reduced. Semiconductor wafer 100
The groove portion 103 that does not reach the semiconductor layer 102 is formed from the back surface side 152 of the substrate, and then the back surface side 152 of the semiconductor wafer is formed.
By polishing, the curved surface shape 104 is formed on the rear surface of the translucent substrate other than the groove 103.

The light-transmissive substrate 101 can be polished by applying a constant pressure to the semiconductor wafer 100 and using a slurry. Various slurries are used for polishing, and silica and diamond are preferable.
When the groove is used for dividing a semiconductor wafer, the average grain size of the abrasive grains is 6 μm or less in order to form the curved surface of the transparent substrate because the width and depth of the groove are limited as described above. It is preferably used, and more preferably an average particle size of 3 μm. Hereinafter, specific examples of the present invention will be described in detail, but it goes without saying that the present invention is not limited to these examples.

[0033]

Example (Reference Example 1) A nitride semiconductor wafer 100 was formed by stacking nitride semiconductors 102 using a sapphire having a thickness of 200 μm and washed and using a translucent substrate 101 by MOCVD. The nitride semiconductor was formed as a multilayer film so as to function as a light emitting element which is the optical semiconductor element 110 after dividing the substrate. First, NH ₃ (ammonia) gas, TMG (trimethylgallium) gas, and hydrogen gas as a carrier gas were caused to flow at 510 ° C. to form GaN serving as a buffer layer having a thickness of about 200 Å.

Next, after stopping the inflow of TMG gas, the temperature of the reactor was raised to 1150 ° C. and NH 3 (ammonia) gas, TMG gas, and SiH ₄ as a dopant gas were added again.
G having a thickness of about 4 μm that acts as an n-type contact layer by flowing a (silane) gas and hydrogen gas as a carrier gas
An aN layer was formed.

In the active layer, only the carrier gas is once kept and the temperature of the reactor is kept at 800 ° C., then NH ₃ (ammonia) gas, TMG gas, TMI (trimethylindium) as a source gas and hydrogen gas as a carrier gas. To deposit an undoped InGaN layer having a thickness of about 3 nm.

In order to form a clad layer on the active layer, the flow of the raw material gas was stopped and the temperature of the reactor was maintained at 1050 ° C., and then NH ₃ (ammonia) gas was used as the raw material gas.
TMA (trimethylaluminum) gas, TMG gas,
Cp ₂ Mg (cyclopentadiermagnesium) gas as a dopant gas and hydrogen gas as a carrier gas were caused to flow, and GaAl having a thickness of about 0.1 μm was used as a p-type cladding layer.
An N layer was formed.

Finally, the temperature of the reactor was maintained at 1050 ° C. and NH ₃ (ammonia) gas and TMG were used as raw material gases.
Gas, Cp ₂ Mg gas as a dopant gas, and hydrogen gas as a carrier gas were caused to flow to form a GaN layer having a thickness of about 0.5 μm as a p-type contact layer (the p-type nitride semiconductor layer is annealed at 400 ° C. or higher). It has been processed.)

RIE (Reacti
A semiconductor wafer in which a plurality of island-shaped nitride semiconductor layers 102 are formed by forming an etching surface 130 until the boundary surface with the sapphire substrate 101 where the groove 103 is formed is exposed from the nitride semiconductor surface side 151 by ve ion etching. 100 is used. A mask is formed so that each pn semiconductor is exposed during etching, and is removed after etching. Further, in each pn semiconductor layer, a p-type electrode 120,
A metal electrode is formed as the n-type electrode 121 by a sputtering method. In order to extract light from the sapphire substrate side 152, the electrode provided on the semiconductor is made non-transparent or has a low transmittance with respect to the emission wavelength (FIG. 1A).

After polishing the formed sapphire substrate 101 of the nitride semiconductor wafer 100 to 100 μm, the sapphire substrate 101 rear surface side 15 of the semiconductor wafer 100 is polished.
It was fixed using a vacuum chuck on a table that could be freely driven in the horizontal direction so that 2 was on the top (not shown).

By moving the stage at a blade rotation speed of 30,000 rpm and a cutting speed of 3 mm / sec, a width of about 25 μm and a depth of about 2 are formed on the bottom surface of the sapphire substrate 101.
Grooves of 0 μm are formed substantially vertically and horizontally to form the groove portions 103. The groove 103 is formed substantially parallel to the etching surface 130 when viewed from the back surface side 152 of the sapphire substrate of the nitride semiconductor wafer 101, and each of them is formed to have a size of 300 μm square to become the optical semiconductor element 110 afterwards (FIG. 1 (B)).

Next, the back surface side 152 of the sapphire substrate is polished by using a single-side polishing machine and a diamond slurry having an average particle diameter of 3 μm serving as a polishing agent to form a curved surface shape 104 acting as a lens (FIG. C)).

After cleaning the semiconductor wafer 100, a scribe line 105 is formed by a scriber in the groove portion 103 used to form the curved surface shape 104 (FIG. 1).
(E)).

A load can be applied along the groove 103 by a roller (not shown) to cut and separate the nitride semiconductor wafer 100 (FIG. 1 (E)).

As described above, an LED chip can be formed as the flip-chip type optical semiconductor element 110 in which the transparent substrate has a curved surface shape having a lens effect.

A mounting example of this LED chip is shown in FIG.
The surface side on which the nitride semiconductor layer 202 is laminated is fixed downward to the electrode 207 on the mounting substrate 208 by using Ag containing resin which is the conductive paste 206 as a mount member. Curved surface shape 20 formed on the back surface side of the transparent substrate 201
4 functions as a lens, and the light amount of the optical semiconductor element 210 can be effectively used. Further, by depositing Au in a thick film, the reflectance of the p-type electrode 220 with respect to the emission wavelength is increased. As a result, the emission wavelength emitted downward from the semiconductor light emitting layer is reflected by the p-type electrode 220 and can be efficiently extracted from the optical semiconductor element. Further, by lowering the transmittance of the p-type electrode with respect to the emission wavelength, it becomes possible to prevent deterioration of the mount member 206 due to the emission wavelength emitted from the optical semiconductor element.

Also, the optical connectivity with the optical fiber 209 can be improved. Further, as shown in FIG. 7, since the end surface of the groove has a curved surface, the scribe line 702 in which the blade edge of the scriber is displaced from the groove and distorted is not formed when the scriber is driven. That is, the desired scribe line 701 can be formed along the periphery of the groove that can guide the blade edge of the scriber. Further, since the groove portion is also used for dividing the nitride semiconductor wafer, the process of dividing the nitride semiconductor wafer can be simplified.

Reference Example 2 A nitride semiconductor wafer 300 was formed by stacking nitride semiconductors 302 using the MOCVD method with sapphire having a thickness of 200 μm and washed as a transparent substrate 301. The nitride semiconductor 302 was formed as a multilayer film so as to function as a light emitting device 310 which is an optical semiconductor device after dividing the transparent substrate 301. First,
NH ₃ (ammonia) as a source gas at 510 ° C.
Gas, TMG (trimethylgallium) gas, and hydrogen gas, which is a carrier gas, were caused to flow to form GaN having a thickness of about 200 Å which functions as a buffer layer.

Next, after the inflow of TMG gas was stopped, the temperature of the reactor was raised to 1150 ° C. and NH 3 (ammonia) gas, TMG gas, and SiH ₄ as a dopant gas were added again.
G having a thickness of about 4 μm that acts as an n-type contact layer by flowing a (silane) gas and hydrogen gas as a carrier gas
An aN layer was formed.

In the active layer, only the carrier gas is once kept and the temperature of the reactor is kept at 800 ° C., then NH ₃ (ammonia) gas, TMG gas, TMI (trimethylindium) as a source gas and hydrogen gas as a carrier gas. To deposit an undoped InGaN layer having a thickness of about 3 nm.

In order to form a clad layer on the active layer, the flow of the raw material gas was stopped and the temperature of the reactor was maintained at 1050 ° C., and then NH ₃ (ammonia) gas was used as the raw material gas.
TMA (trimethylaluminum) gas, TMG gas,
Cp ₂ Mg (cyclopentadiermagnesium) gas as a dopant gas and hydrogen gas as a carrier gas were caused to flow, and GaAl having a thickness of about 0.1 μm was used as a p-type cladding layer.
An N layer was formed.

Finally, the temperature of the reactor is maintained at 1050 ° C., NH ₃ (ammonia) gas and TMG are used as raw material gases.
Gas, Cp ₂ Mg gas as a dopant gas, and hydrogen gas as a carrier gas were caused to flow to form a GaN layer having a thickness of about 0.5 μm as a p-type contact layer (the p-type nitride semiconductor layer is annealed at 400 ° C. or higher). It has been processed.)

RIE (Reacti
by ve ion etching, etching is performed from the front surface side 351 where the nitride semiconductor is laminated until the boundary surface with the sapphire substrate where the groove is formed is exposed to form an etching surface 320 to form a plurality of island-shaped nitride semiconductor layers. The semiconductor wafer 300 is used. A mask is formed so that each pn semiconductor is exposed during etching, and is removed after etching. Further, the p-type electrode 3 is formed on each pn semiconductor layer.
Electrodes are formed as the 20 and n-type electrodes 321 by a sputtering method. P-type electrode 32 from the semiconductor surface side
In order to extract light through 0, the thickness of the p-type electrode 320 is set to A
u is formed as thin as 1000 angstrom (FIG. 3 (A)).

After polishing the sapphire substrate 301 of the nitride semiconductor wafer 300 thus formed to 100 μm, the sapphire substrate back surface side 3 of the semiconductor wafer 300 is polished.
It was fixed using a vacuum chuck on a table that could be freely driven in the horizontal direction so that 52 was on the top (not shown).

By moving the stage at a blade rotation speed of 30,000 rpm and a cutting speed of 3 mm / sec, a width of about 25 μm and a depth of about 2 are formed on the bottom surface of the sapphire substrate 301.
Grooves having a thickness of 0 μm are formed substantially vertically and horizontally to form groove portions 303. The groove portion 303 is formed substantially parallel to the etching surface 330 when viewed from the back surface side 352 of the sapphire substrate of the semiconductor wafer 300, and each of them is formed after that.
It is formed in a size of 300 μm square, which is 10 (FIG. 3B).

Next, the back surface 352 of the sapphire substrate 301 is polished by using a single-sided polishing machine and a diamond slurry having an average particle diameter of 3 μm, which serves as a polishing agent, so that the transparent substrate 301 has a curved surface shape 304 having a lens effect. Form.

After cleaning the semiconductor wafer 300, a reflective film 309 of Al is formed on the rear surface 352 of the transparent substrate, which is the entire rear surface of the nitride semiconductor wafer, by a vacuum evaporation method (FIG. 3C).

After forming the reflection film 309, a break line 305 having a depth of 5 μm is formed on the bottom surface of the groove 303 by laser irradiation (FIG. 3D).

Then, a weighted roller is run along the groove 303 to cut the semiconductor wafer 300 to form an LED chip which is an optical semiconductor element 310 (FIG. 3).
(E)).

Since the groove 303 and the scribe line 305 are formed by a laser, compared with a machine such as a scriber for mechanically forming the groove, variation in machining accuracy due to wear and deterioration of the cutter, and cost required for cutting edge replacement. It can be reduced. Further, since the groove portion 303 is also used for dividing the nitride semiconductor wafer 300, it is possible to reduce the step of dividing the semiconductor wafer. Further, since the break line is formed on the translucent substrate provided with the reflection film by laser irradiation, the blade does not become clogged with the metal such as Al forming the reflection film 309 when the break line is formed. .

An example of mounting the optical semiconductor element 410 is shown in FIG. The optical semiconductor element is mounted on the mounting substrate 408 by using a mounting member such as epoxy resin.
Mounting is completed by wire bonding the 0 electrode and the external electrode provided on the mounting substrate 408 (not shown). Since the back surface side of the light transmissive substrate of the optical semiconductor element 410 has a curved surface shape, it becomes possible to efficiently collect the emission wavelength and take it out to the outside. Further, since the reflection film 409 reduces the amount of light incident on the mount member 406, it is possible to reduce deterioration of the die bond member 406 caused by the wavelength of light emitted from the optical semiconductor element 410 and the outside.
In particular, the effect is great when the optical semiconductor element used outdoors or the emission wavelength is in the ultraviolet range.

Comparative Example 1 An LED chip was formed in the same manner as in Reference Example 1 , except that the polishing step was not performed and the surface did not have a curved surface. The formed LED chip is referred to as Reference Example 1 and
And the LED chip of Reference Example 2 . LE of Reference Example 1
When compared with the D chip, the light amount of Reference Example 1 is improved by about 1.3 times as compared with the LED chip of Comparative Example 1 having no curved surface. Ginseng Similarly was compared with LED chips of Example 2
The light amount of the consideration example 2 is improved by about 1.2 times as compared with the LED chip of the comparison example 1 having no curved surface.

Example 1 A semiconductor wafer 500 was formed in the same manner as in Reference Example 1 except that the groove 503 was formed by a laser and the groove 513 not used for dividing the optical semiconductor element was also formed (see FIG. A)). The laser (356 nm) is 1 from the YAG laser irradiation device.
By moving the stage while irradiating at 6 J / cm ² , a groove having a width of about 30 μm and a depth of about 5 μm is formed vertically and horizontally on the bottom surface of the sapphire substrate 501 to form a groove portion 503. The groove portion 503 is adjusted and formed so that the distance between the bottom surface and the surface of the semiconductor layer surface is substantially uniform within 95 μm. The groove 513 not used for division is formed shallower than the groove 503.

A curved surface shape 504 is formed on the back surface of the semiconductor wafer by polishing the back surface side 552 of the transparent substrate 501. Optical semiconductor element 510 formed later by polishing
A curved surface shape that functions as four lenses is formed for each of the two (FIG. 5C).

Next, the break line 505 is formed only on the bottom surface of the groove portion 503 corresponding to the size of the optical semiconductor element 510. At this time, the laser output is adjusted so that the depth of the break line 505 formed by the laser is 3 μm or more (FIG. 5D).

Subsequently, a load is applied by a roller along the groove 503 to cut the semiconductor wafer 500 and separate the optical semiconductor element 510 (FIG. 5 (E)).

Grooves 503 and 513, break line 5
Since the layer No. 05 is formed by a laser, it is possible to reduce consumption of the cutter, variation in processing accuracy due to deterioration, and cost to replace the cutting edge.

[0067]

EFFECTS OF THE INVENTION The optical semiconductor element has a curved surface on the back surface side of the substrate, and can extract light that could not be extracted to the outside of the optical semiconductor element due to critical angle reflection in the related art. Alternatively, the light that could not be captured can be captured, and the light utilization efficiency of the optical semiconductor element is improved.

By forming the reflective film on the back surface of the transparent substrate having a curved surface, the back surface side of the transparent substrate has the same effect as the parabona antenna with respect to the emission wavelength or the reception wavelength. Therefore, it becomes possible to efficiently extract light from the optical semiconductor element or to extract light.

Further, in the case of a flip-chip type in which the optical semiconductor element is mounted with the semiconductor layer surface side facing down, the back surface of the curved substrate has the effect of a lens. Further, since the p-type electrode functions as a reflecting mirror, it becomes an optical semiconductor element having high light emitting efficiency or light receiving efficiency.

By using the manufacturing method of the present invention, it becomes possible to easily manufacture an optical semiconductor element having a high light utilization efficiency.

Further, by forming the groove portion with a laser, it becomes possible to reduce the processing cost which has been caused by deterioration and replacement of the scribe cutter as in the prior art. By dividing the wafer along the groove, it becomes possible to obtain an optical semiconductor element having a uniform shape relatively easily and with high yield.

[Brief description of drawings]

FIG. 1 is a schematic view showing a method for processing an optical semiconductor wafer in Reference Example 1 .

FIG. 2 is a schematic view showing a mounting example of an optical semiconductor element in Reference Example 1 .

FIG. 3 is a schematic diagram showing a method for processing an optical semiconductor wafer in Reference Example 2 .

FIG. 4 is a schematic diagram showing a mounting example of an optical semiconductor element in Reference Example 2 .

FIG. 5 is a schematic diagram showing a method for processing an optical semiconductor wafer in Example 1 .

FIG. 6 is a schematic view showing a method of processing an optical semiconductor wafer shown for comparison with the present invention.

FIG. 7 is a schematic explanatory view showing one of the effects of the present invention.

[Explanation of symbols]

100, 300, 500 ... Nitride semiconductor wafer 101, 201, 301, 401, 501 ... Translucent substrate 102, 202, 302, 402, 502 ... Nitride semiconductor 103, 303 ... Transparency Grooves 104, 204, 304, 504 provided on the light-transmitting substrate ... Curved shapes 105, 305, 505 provided on the back surface side of the light-transmitting substrate ... Break lines 110, 210, 310, 410, 510 ... Optical semiconductor element 120, 220, 320, 420 ... P-type electrode 121, 321, 421 ... N-type electrode 130, 330 ... Etching surface 151, 351, 551 ... First Main surface 152, 352, 552 ... Second main surface 206, 406 ... Mount member 207 ... Electrode 208, 408 on mounting board ... Mounting board 209 ... Fiber end portions 309, 409 ... Reflective film 503 ... Grooves 513 used for division of optical semiconductor element 513 ... Grooves not used for division of optical semiconductor element 600 ... Semiconductor wafer 601 ... Translucent Substrate 602 ... nitride semiconductor 603 ... groove 604 ... scribing line 610 ... optical semiconductor element 620 ... p-type electrode 621 ... n-type electrode 701 ... along groove Formed scribe line 702 ... Distorted scribe line

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-8-298344 (JP, A) JP-A-6-45646 (JP, A) JP-A-7-131069 (JP, A) JP-A-8- 102549 (JP, A) Actual development Sho 57-106246 (JP, U) Japanese Patent Sho 51-18788 (JP, B1) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01L 33/00

Claims (2)

(57) [Claims] 1. A nitride semiconductor (502) on a transparent substrate (501 ).
Is a method for manufacturing an optical semiconductor element (510) formed by dividing a laminated semiconductor wafer (500) , wherein the nitride semiconductor (502) is laminated from the rear surface side of the transparent substrate facing the laminated surface side. The first that does not reach the nitride semiconductor (502)
A step of forming a groove part (503) and a second groove part (513) , and the second groove which is not used for division with the first groove part (503)
A step of forming a plurality of curved surface shapes (504) by polishing the back surface side of the translucent substrate (501) after forming the part (513) , and a semiconductor wafer ( ) along the first groove part (503). 500) is divided, and the manufacturing method of the optical-semiconductor element characterized by the above-mentioned. 2. The first groove portion (503) and the second groove portion (51)
The method for manufacturing an optical semiconductor device according to claim 1, wherein the formation of 3) is performed by laser irradiation.