JP2001094148A - Sapphire substrate blue led and manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sapphire substrate blue LED, and its manufacturing method, where the action area of a chip is significantly reduced for simplified succeeding substrate polishing process, resulting in an improved product yield. SOLUTION: In the manufacture of the blue LED at least one channel is formed by etching in a sapphire substrate, and GaN thin-film layers of about the same thickness are formed above and below the substrate. The materials of upper and lower GaN thin-film layers are brought into contact with each other in the channel, and an anode and a cathode are formed under the GaN thin-film layer, which is a lower layer, and over an LED epitaxial layer above the substrate. As the installation of the channel is done, a pipe channel through which a current passes the substrate is formed between the anode and the cathode, and an upright LED chip is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a kind of blue light LE
In particular, the present invention relates to a blue light LED using sapphire as a substrate, wherein at least one channel is opened in the sapphire substrate to serve as a conduit for passing electric current, and the thickness of the substrate is formed above and below the substrate. The present invention relates to an upright blue light LED in which an approximate GaN thin film layer is formed, and a thickness and an active area are significantly reduced, and a method of manufacturing the same.

[0002]

2. Description of the Related Art LEDs have been developed since the 1950's and have a long life, small volume, low heat generation, low power consumption, high reaction speed, and the characteristics and advantages of monochromatic light emission. From just a few decades, various household goods and equipment, such as computer peripherals,
It is being used in large quantities in watch displays, billboards, traffic lights, telecommunications, and consumer electronics products, and the range of applications of these products must be surprising. In particular, after the blue light LED was released, red light and green light were produced before and after. Therefore, a full-color complete basic structure combining them was utilized in color variability or a traditional incandescent light source. It has been applied as a substitute for

[0003] At present, the manufacture of blue light LEDs is roughly divided into those using a sapphire substrate and those using a silicon carbide (SiC) substrate. However, compared to silicon carbide substrate LEDs, sapphire substrate LEDs are superior in physical properties such as brightness and contrast, and electrical properties such as electrical conductivity. Is higher.

FIG. 1 shows a cross-sectional structure of a known sapphire substrate LED substrate structure. A GaN thin film layer 12 is formed on a sapphire substrate 10,
An LED epitaxial layer 14 having a pn junction and capable of emitting blue light is formed thereon by sputtering or vapor deposition. Since the sapphire substrate 10 is an insulator, LE
On the D epitaxial layer 14, a first electrode 16 on the same plane
Only the (anode) and the second electrode 18 (cathode) can be selectively formed, thus forming a planar LED.

[0005] Known sapphire substrate LEDs have the following disadvantages. (1) Since the sapphire substrate 10 itself is an insulator and does not have conductive properties, the first and second electrodes 16 of the LED
18 had to be formed by plating on the same plane, the working area was large, and the LED volume could not be reduced, so that it was not possible to effectively achieve the light, thin and short design goals of the product. (2) Since the sapphire substrate 10 itself is an insulator,
Electrostatic action was easily caused during manufacturing, and the defect rate during product production increased relatively. (3) GaN thin film layer 12 (thickness H) on sapphire substrate
11) tends to cause non-uniformity of the stress acting on the substrate at the time of annealing temperature drop, thereby causing cracks in the sapphire substrate, increasing the trouble in the process, and therefore, reducing the thickness H1 of the substrate to less than 280 μm. Could not.

In general, when mass-produced, the substrate thickness H1 is all larger than 300 μm, and H11 is 3 to
4 μm, so that the thickness ratio between H1 and H11 is about 1
00: 1. A sapphire substrate of such a thickness presents a great difficulty in the subsequent dicing process with a diamond cutter or a laser. In other words, after completion of LED manufacturing, a sapphire substrate is further formed of a high-hardness material such as diamond so that subsequent dicing using laser or diamond can be easily performed.
It is necessary to polish over 00 μm, which increases the labor in the process.

For this reason, the sapphire substrate LED is in an upright mode, the thickness of the sapphire substrate is significantly reduced, the production cost is reduced, and the yield of products and the production process are simplified. Have been.

[0008]

SUMMARY OF THE INVENTION It is a primary object of the present invention to provide a sapphire substrate blue light LED and a method of manufacturing the same. More specifically, at least one channel is opened in the sapphire substrate and the upper and lower channels are formed. The present invention is to provide a sapphire substrate blue light LED and a method of manufacturing the same, which can achieve an effect of reducing the working area without an upright type photodiode chip by using a current passage between the electrodes.

Another object of the present invention is to provide a kind of sapphire substrate blue light LED and a method of manufacturing the same.
Specifically, a GaN thin film layer having the same thickness is formed on each of the upper and lower sides of the sapphire substrate, and the stress formed at the time of annealing cooling is cancelled, thereby significantly reducing the required substrate thickness to 150 μm. Or terribly 100
sapphire substrate blue light LE which prevents cracking of the sapphire substrate, saves resources of the substrate material, and simplifies the process steps of subsequent substrate polishing.
D and its manufacturing method.

Another object of the present invention is to provide a kind of sapphire substrate blue light LED and a method of manufacturing the same, and more specifically, by providing a channel for passing a current through the sapphire substrate, the manufacturing process is improved. It is an object of the present invention to provide a sapphire substrate blue light LED and a method for manufacturing the same, which can substantially improve the yield of products by canceling out the adverse effects of electrostatic formed by the method.

[0011]

According to the first aspect of the present invention, a pn is provided.
LED epitaxial layer capable of emitting blue light with bonding, GaN formed under the LED epitaxial layer
A thin film layer, a sapphire substrate provided below the GaN thin film layer, wherein at least one channel penetrating two sides of the sapphire substrate is opened in the sapphire substrate;
The sapphire substrate in which a part of the GaN thin film layer is present in the channel, a first electrode formed on the LED epitaxial layer, and a conductive layer formed under the sapphire substrate; A portion of the conductive layer material is present in the channel of the sapphire substrate and is in contact with the GaN thin film layer already present in the channel;
A sapphire substrate blue light LE comprising the above conductive layer, which can be a second electrode corresponding to the electrode.
D. The invention according to claim 2 is the sapphire substrate blue light LED according to claim 1, wherein the conductive layer is composed of a nonmetallic conductive material. Claim 3
The sapphire substrate blue light LED according to claim 1, wherein the thickness of the GaN thin film layer is similar to the thickness of the conductive layer. The invention according to claim 4 is the sapphire substrate blue light LED according to claim 1, wherein the conductive layer is a GaN thin film layer. The sapphire substrate blue light LED according to claim 4, wherein the conductive layer serving as the GaN thin film layer and the GaN thin film layer below the LED epitaxial layer have the same thickness. I have. The invention according to claim 6 is characterized in that the channel has a slope.
The sapphire substrate blue light LED according to claim 1 is provided. A seventh aspect of the present invention is the sapphire substrate blue light LED according to the first aspect, wherein the channel has a linear shape. According to an eighth aspect of the present invention, there is provided the sapphire substrate blue light LED according to the first aspect, wherein the thickness of the sapphire substrate is set to be greater than 0 μm and 150 μm or less. According to a ninth aspect of the present invention, there is provided the sapphire substrate blue light LED according to the first aspect, wherein the first electrode is a transparent electrode. The invention according to claim 10 is characterized in that a second electrode is formed below the conductive layer, and a current path is formed between the second electrode and the first electrode via a channel of the sapphire substrate. The described sapphire substrate is a blue light LED. Claim 11
The present invention provides a method for manufacturing a sapphire substrate blue light LED, in each of the following steps (1) to (5):
(1) forming at least one channel penetrating two sides of the sapphire substrate in the sapphire substrate;
(2) forming a GaN thin film layer on a sapphire substrate, and causing a partial material of the GaN thin film layer to exist in a partial space in the channel; (3) forming a conductive layer under the sapphire substrate; (4) forming an LED epitaxial layer having a pn junction on the GaN thin film layer by causing the material of the conductive layer to be present in a partial space of the channel and contacting the GaN thin film layer present in the channel; Steps,
(5) A method of manufacturing a sapphire substrate blue light LED, comprising the steps of: forming a first electrode on the LED epitaxial layer by plating; According to a twelfth aspect of the present invention, there is provided the sapphire substrate blue light LED manufacturing method according to the eleventh aspect, wherein the channel opened in the step (1) has an inclination. The invention of claim 13 is characterized in that in the step (2), a GaN thin film layer is formed on a sapphire substrate by MOVPE.
A sapphire substrate blue light LED according to claim 11 is provided. A fourteenth aspect of the present invention is the method for manufacturing a sapphire substrate blue light LED according to the eleventh aspect, wherein the conductive layer is formed of a nonmetallic conductive material in the step (3). The invention of claim 15 is
The sapphire substrate blue light LED according to claim 11, wherein the thickness of the GaN thin film layer formed in the step (2) and the thickness of the conductive layer formed in the step (3) are approximated. And how to do it. The invention of claim 16 is the method of manufacturing a sapphire substrate blue light LED according to claim 11, wherein the conductive layer is formed of GaN in the step (3).
The invention of claim 17 is the sapphire substrate blue light LED according to claim 16, wherein the thickness of the GaN thin film layer formed in the step (2) and the step (3) is the same. Manufacturing method. Claim 18
The method according to claim 11, wherein the thickness of the sapphire substrate used in the step (1) is set to be larger than 0 μm and equal to or smaller than 150 μm. The invention according to claim 19 is the method for manufacturing a sapphire substrate blue light LED according to claim 11, wherein the first electrode is formed of a transparent material in the step (5). The invention of claim 20 is characterized by comprising, after the step (5), (6) forming a second electrode corresponding to the first electrode under the conductive layer. Item 11. A method for manufacturing a sapphire substrate blue light LED according to item 11.

[0012]

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a sapphire substrate blue light LED and a method of manufacturing the same, which comprises a sapphire substrate blue light LED and a method of manufacturing the same. And forming a GaN thin film layer having an approximate thickness on each of the upper and lower surfaces of the substrate, and bringing the materials of the upper and lower GaN thin film layers into contact in the above-described channel, and placing the anode and the cathode below and below the lower GaN thin film layer. It is characterized in that it is formed on the LED epitaxial layer on the substrate, and the channel is provided between the anode and the cathode to form a conduit for passing current through the substrate, thus forming an upright LED chip.
The present invention, with this structure, greatly reduces the active area of the chip and thereby simplifies the subsequent substrate polishing process and improves product yield.

[0013]

FIG. 2 shows a sectional structure of a preferred embodiment of a sapphire substrate of a blue light LED according to the present invention. The well-known sapphire substrate blue light LED has a G
When the aN thin film layer was formed and subjected to annealing cooling, different stress effects were formed on the sapphire substrate to easily form cracks and breaks in the substrate. For this reason, in the known technique, unless the thickness of the sapphire substrate is increased, the stress resistance of the sapphire substrate cannot be improved to prevent the sapphire substrate from being cracked or damaged. On the other hand, in the present invention, when preparing the sapphire substrate 20, the thickness (H3, H3,
H4), the GaN thin film layers 222 and 224 having the same or substantially the same working area as those of the sapphire substrate 20 during the annealing and cooling. Therefore, no damage is formed on the sapphire substrate 20, and therefore, it is not necessary to increase the thickness (H2) of the sapphire substrate 20 as is well known. According to the experimental results, the thickness of the sapphire substrate used in the present invention is 150 μm or less, and
m or less could be used. As a result, an enormous effect can be obtained in both the amount of material used and the subsequent substrate polishing step.

As shown in FIGS. 3 to 7, the manufacturing method of the present invention includes the following steps: Step 1: Select a sapphire substrate 30 having a thickness of 100 μm or less, and perform chemical etching or mask etching. At least one sapphire substrate 3
A channel 31 is formed that penetrates through 0 and slopes. This is as shown in FIG. Step 2: One GaN thin film layer 32 is formed on the sapphire substrate 30 by an epitaxial method such as the MOVPE method.
2 and a part of the material of the GaN thin film layer 322 is present in the space of the channel 31. This is as shown in FIG. Step 3: Form one conductive layer 326 under the sapphire substrate 30 by an epitaxial method or a sputtering method, which is made of a non-metallic conductive material. In addition, the material of the conductive layer 326 is also present in a part of the space of the channel 31, and the G
The material of the aN thin film layer 322 is connected. GaN thin film layer 3
Since 22 itself is a conductive material, this connection forms a complete conductive circuit. This is as shown in FIG. Step 4: L capable of emitting blue light with a pn junction by sputtering or vapor deposition on the upper layer of the GaN thin film layer 322
An ED epitaxial layer 34 is formed, which can of course have an np junction as shown in parentheses. This is as shown in FIG. Step 5: On the LED epitaxial layer 34 and below the conductive layer 326, the mutually corresponding first electrode 36 and second electrode 36
An electrode 38 is formed. Thus, an upright LED chip is formed. This is as shown in FIG.

Since the LED epitaxial layer 34, the GaN thin film layer 322, and the conductive layer 326 are all composed of a conductive material, the conductive material and the channel 31 are interposed between the first electrode 36 and the second electrode 38. Provides one complete current path, shown in phantom in the figure.
The upright blue light LED thus formed is turned into an upright blue light LED chip after the subsequent dicing, in which the first electrode 36 and the second electrode 38 are on different planes,
The working area of the LED epitaxial layer 34 is relatively reduced, and the use of materials can be saved.

FIG. 8 shows another embodiment of the present invention. In this embodiment, the technique shown in FIG. 2 is combined. As shown in this embodiment, the conductive layer 32
The non-metallic conductive material of No. 6 can select the same material as the GaN thin film layer 322, and the thicknesses H3 and H4 of the upper and lower two layers can be similar or completely the same. Thereby, the upper and lower Ga
The stress generated at the time of annealing cooling of the N thin film layers 322 and 324 is cancelled, and the sapphire substrate 30 is prevented from being broken. Thus, the thickness of the sapphire substrate can be greatly reduced, which is relatively convenient in material management.

In addition, the channel 31 having the slope shown in the above-mentioned step 1 is surely brought into contact in the channel 31 when the GaN thin film layer 322 and the conductive layer 326 are formed in the steps 2 and 3. Although it is advantageous to do so, it is also possible for the process to have the channel 31 in a linear manner, in which case a current also flows between the upper and lower electrodes. Of course, the first electrode 36 on the LED epitaxial layer 34 can be made of a transparent material to be a transparent electrode in order to increase the light emission luminance. Further, since the conductive layer 326 or the GaN thin film layer 324 itself is made of a conductive material, it is possible to substitute the conductive layer 326 or the GaN thin film layer 324 without providing the second electrode 38.

[0018]

In summary, the sapphire substrate blue light LED and the method of manufacturing the same according to the present invention are the sapphire substrate blue light LED and the method of manufacturing the same, wherein at least one channel is formed in the sapphire substrate by etching. Forming a GaN thin film layer having an approximate thickness on the upper and lower surfaces of the substrate, and bringing the materials of the upper and lower GaN thin film layers into contact with each other in the channel, and connecting the anode and the cathode to the lower Ga
Formed on the LED epitaxial layer under the N thin film layer and on the substrate, the installation of the channel formed a conduit between the anode and cathode to allow current to pass through the substrate, thus forming an upright LED chip It is characterized by the following. The present invention, by virtue of this feature, provides the effect of significantly reducing the active area of the chip and thereby simplifying the subsequent substrate polishing process and improving the product yield, and thus the invention is novel, inventive and inventive. It can be said that the invention has industrial utility value.

However, the above-described embodiment is a description of a preferred embodiment of the present invention, and does not limit the scope of the present invention. It belongs to the claims. For example, an impurity layer, for example, AlGaInP is added between the LED epitaxial layer and the GaN thin film layer,
Alternatively, on top of another thin film layer, for example, SiC,
AlN, SiO ₂ , InGaN, SnO ₂ , AlInG
A configuration in which the aP layer is increased is possible.

[Brief description of the drawings]

FIG. 1 is a structural sectional view of a well-known sapphire substrate blue light LED.

FIG. 2 is a structural sectional view of a preferred embodiment of the sapphire substrate of the present invention.

FIG. 3 is a structural sectional view of a manufacturing step of the LED of the present invention.

FIG. 4 is a structural sectional view of a manufacturing step of the LED of the present invention.

FIG. 5 is a structural sectional view of a manufacturing step of the LED of the present invention.

FIG. 6 is a structural sectional view of a manufacturing step of the LED of the present invention.

FIG. 7 is a structural sectional view of a manufacturing step of the LED of the present invention.

FIG. 8 is a structural sectional view of another embodiment of the LED of the present invention.

[Explanation of symbols]

Reference Signs List 10 sapphire substrate 12 GaN thin layer 14 LED epitaxial layer 16 first electrode 18 second electrode 20 sapphire substrate 222 GaN thin layer 224 GaN thin layer 30 sapphire substrate 31 channel 322 GaN thin layer 324 GaN thin layer 326 conductive layer 34 LED epitaxial layer 36 first electrode 38 second electrode

Claims (20)

[Claims] 1. An L having a pn junction and capable of emitting blue light.
An ED epitaxial layer, a GaN thin film layer formed below the LED epitaxial layer, a sapphire substrate provided below the GaN thin film layer, wherein at least one sapphire substrate penetrates two sides of the sapphire substrate. The sapphire substrate, wherein one channel is opened, and a part of the GaN thin film layer is present in the channel, a first electrode formed on the LED epitaxial layer, and a conductive film formed under the sapphire substrate A part of the material of the conductive layer is present in the channel of the sapphire substrate and is in contact with the GaN thin film layer already present in the channel, and the conductive layer corresponds to the first electrode. A sapphire substrate blue light LED comprising the above conductive layer, which can be used as a second electrode. 2. The sapphire substrate blue light LED according to claim 1, wherein the conductive layer is composed of a non-metallic conductive material. 3. The sapphire substrate blue light LED according to claim 1, wherein the thickness of the GaN thin film layer is similar to the thickness of the conductive layer. 4. The sapphire substrate blue light LED according to claim 1, wherein the conductive layer is a GaN thin film layer. 5. A conductive layer formed of the GaN thin film layer and LE
The sapphire substrate blue light LED according to claim 4, wherein the GaN thin film layer under the D epitaxial layer has the same thickness. 6. The sapphire substrate blue light LE according to claim 1, wherein the channel has a slope.
D. 7. The sapphire substrate blue light L according to claim 1, wherein the channel has a linear shape.
ED. 8. The sapphire substrate blue light LED according to claim 1, wherein the thickness of the sapphire substrate is greater than 0 μm and 150 μm or less. 9. The sapphire substrate blue light LE according to claim 1, wherein the first electrode is a transparent electrode.
D. 10. The method according to claim 1, wherein a second electrode is formed under the conductive layer, and a current path is formed between the second electrode and the first electrode through a channel of the sapphire substrate. Sapphire substrate blue light LED. 11. A method for manufacturing a sapphire substrate blue light LED, wherein each of the following steps (1) to (5) is performed: (1) at least one channel penetrating two sides of the sapphire substrate into the sapphire substrate; (2) forming a GaN thin film layer on a sapphire substrate, and causing a partial material of the GaN thin film layer to exist in a partial space in the channel; (3) a conductive layer below the sapphire substrate Forming the conductive layer material in a partial space of the channel and contacting the GaN thin film layer existing in the channel; (4) LED epitaxial having a pn junction on the GaN thin film layer Forming a first electrode by plating on the LED epitaxial layer; and (5) forming a first electrode on the LED epitaxial layer by plating. A method for manufacturing a sapphire substrate blue light LED. 12. The method according to claim 1, wherein the channel opened in the step (1) has a slope.
2. The method for producing a sapphire substrate blue light LED according to 1. 13. The method according to claim 2, wherein GaN is used in the step (2).
The method of claim 11, wherein the thin film layer is formed on the sapphire substrate by MOVPE. 14. The method according to claim 11, wherein the conductive layer is formed of a non-metallic conductive material in the step (3). 15. The sapphire substrate according to claim 11, wherein the thickness of the GaN thin film layer formed in the step (2) and the thickness of the conductive layer formed in the step (3) are approximated. A method for manufacturing a blue light LED. 16. The method of claim 11, wherein the conductive layer is formed of GaN in the step (3). 17. The sapphire substrate blue light LED according to claim 16, wherein the thickness of the GaN thin film layer formed in the step (2) and the step (3) is the same. Method. 18. The method according to claim 11, wherein the thickness of the sapphire substrate used in the step (1) is greater than 0 μm and 150 μm or less. 19. The method as claimed in claim 11, wherein the first electrode is formed of a transparent material in the step (5). 20. The method according to claim 11, further comprising: (6) forming a second electrode corresponding to the first electrode under the conductive layer after the step (5). 3. The method for producing a sapphire substrate blue light LED according to item 1.