TWI466318B - The process of vertical non - cutting metal substrate light - emitting diodes - Google Patents

Description

Vertical cut-free metal substrate light-emitting diode process

The invention provides a metal substrate light-emitting diode manufacturing process, in particular to a technical process for providing a vertical cut-free metal substrate light-emitting diode, which uses a thick photoresist to form a plurality of mutually independent copper plating substrates. The copper substrate avoids the problem of metal splash and warpage of the copper substrate when the copper substrate is cut.

Generally, the manufacturing process of the metal substrate light-emitting diode is as shown in the seventh figure. The steps are as follows: 1. Test piece cleaning (70): Before the component process starts, the test piece (sapphire substrate plus GaN LED) is used. Immerse the acetone, shake it with an ultrasonic oscillator, then soak the test piece with isopropyl alcohol, shake it with an ultrasonic oscillator, remove the acetone on the test piece, and finally shake the DI water with the test piece and blow it dry with a nitrogen gun. 2. Mesa independence (71): Growth of cerium oxide (SiO ₂ ) film by plasma enhanced chemical vapor deposition (PECVD) for protection after plasma etching Layer, then use the exposure lithography technology to make the platform pattern, then use the oxide oxide etching (BOE) to etch the platform pattern, and finally remove the photoresist; after defining the platform pattern, use the inductive coupling plasma etching machine Inductively coupled plasma (ICP) etches a gallium nitride epitaxial layer and etches p-type gallium nitride to n-type gallium nitride to expose a sapphire substrate to produce a 1 mm × 1 mm (or larger) platform. After the removal of cerium oxide (SiO ₂ ), the platform is independent. The independence of the platform is mainly to isolate the GaN current. 3. Platform sidewall protection layer (72): The function of the platform sidewall protection layer is to avoid the short circuit and leakage current of the component sidewall caused by the ohmic contact reflective layer, and to avoid the component failure caused by the metal particles or contaminants contaminating the sidewall in the back process. Typically use silicon dioxide (SiO ₂₎ as the sidewall protective layer by plasma assisted chemical vapor deposition (PECVD) to grow silicon dioxide (SiO ₂₎ film, using an exposure lithography patterning, then an oxide etch The liquid (BOE) etches the pattern of the platform, and finally removes the photoresist, that is, completes the sidewall protection layer of the platform. 4. Evaporation of ohmic contact reflective layer (73): p-type contact and reflective metal fabrication in addition to light reflection without being absorbed by the substrate, must also consider ohmic contact with p-GaN, and then electroless copper plating Adhesion; common p-type contact and reflective metals can be platinum (Pt), ITO/Ti/Al/Ti/Au or Ni/Ag series. 5. Tempering treatment (74): p-GaN with high work function metal should be tempered to form an ohmic junction; the furnace tube is heated to 500 ° C and filled with oxygen in a high temperature environment, the test piece is pushed into the furnace tube The heat tempering treatment is carried out, and finally the test piece is taken out to complete the tempering treatment. 6. Electroplated copper substrate (75): a copper metal substrate is prepared by electroplating, and a copper sulfate solution can be used for the electroplating copper process, the test piece to be electroplated is placed at the cathode of the electroplating bath, and the copper source is placed in the electroplating bath. The anode is grown and the metal substrate is grown in a copper sulfate solution. After the electroplating is completed, it is taken out by the plating solution, and then placed in the DI water to be shaken, that is, the electroplated copper substrate is completed. 7. Laser-peeled sapphire substrate (76): A gallium nitride film is grown on a sapphire substrate by MOCVD, and an excimer KrF laser (λ = 248 nm) is generally used to strip the sapphire substrate. 8. Removal of u-GaN (77): After sapphire is stripped, since there is an undoped gallium nitride (u-GaN) layer on the sapphire substrate and the gallium nitride film, dry etching is generally used to remove undoped nitridation. Gallium (u-GaN). 9. n-GaN electrode fabrication (78): After removing u-GaN, an n-type electrode was evaporated using an electron gun (E-GUN). Wherein, the steps of the above-mentioned platform (mesa) and the sidewall protection layer of the platform are not necessarily omitted, but generally, the isolation of the GaN current is still performed.

The above-described general metal substrate light-emitting diode fabrication process can be simply organized into steps as shown in the eighth figure: (I) The platform (mesa) is independent. (II) Forming a platform sidewall protective layer (65). (III) An ohmic contact reflective layer (66) is deposited. (IV) Electroplated copper substrate (67). (V) Laser stripped sapphire substrate (60). (VI) The undoped gallium nitride layer (61) is removed and a Cr/Au electrode (68) of n-GaN is formed.

However, the above-mentioned conventional metal substrate light-emitting diode manufacturing process still has the following defects:

1. When the next copper substrate is cut, it will cause metal to splash to the sidewall and cause leakage current of the component.

Second, after the sapphire substrate is stripped by laser, the copper substrate is easily warped, causing problems in subsequent processes.

Therefore, in view of the problems existing in the above-mentioned conventional structure, how to develop an innovative structure that is more ideal and practical, and the consumers are eagerly awaiting, It is also the relevant industry to work hard to develop breakthrough goals and directions.

In view of this, the inventor has been engaged in the manufacturing development and design experience of related products for many years. After detailed design and careful evaluation, the inventor has finally obtained the practical invention.

Conventional metal substrate light-emitting diode system In the process, there is a problem that when the next copper substrate is cut, metal is splashed to the side wall to cause leakage current of the element. Second, after the sapphire substrate is stripped by laser, the copper substrate is easily warped, causing problems in subsequent processes.

Vertical cut-free metal substrate The process of the light-emitting diode, thereby avoiding the warpage of the copper substrate after the metal splash and the substrate are peeled off after the subsequent copper substrate cutting, and the steps include the following steps: A. providing a cleaned test piece, the test piece a test piece for growing a gallium nitride-based light-emitting diode (GaN LED) on a substrate; B. vapor-depositing an ohmic contact reflective layer on the gallium nitride-based light-emitting diode; C. on the ohmic contact reflective layer A plurality of electroplated copper regions are defined by a thickness resistor having a thickness of 50-200 μm, and the electroplated copper regions are independent of each other; D. electroplating is used to electroplate only the copper substrate in the number of steps defined in step C. a copper region, forming a plurality of mutually independent copper substrates; E. stripping the substrate of the test piece by laser; F. removing the undoped gallium nitride layer (u-GaN), and n-type gallium nitride An n-GaN electrode was formed on the layer (n-GaN).

The method of the invention defines using thick photoresist A plurality of electroplated copper regions form a plurality of mutually independent copper bases when electroplating copper, and the subsequent copper substrate cutting does not cause metal splashing to the side walls, and since the copper substrates are independent of each other, they are not peeled off. After the sapphire substrate, the copper substrate is warped.

The above-mentioned objects, structures and features of the present invention will be described in detail with reference to the preferred embodiments of the present invention. .

Referring to the first and second figures, the present invention provides a process for a vertical cut-free metal substrate light-emitting diode, thereby preventing metal splash and copper substrate warpage when the copper substrate is cut, which is mainly The method comprises the following steps: (A) providing a test piece: providing a cleaned test piece, which is a test piece of a gallium nitride-based light-emitting diode (GaN LED) grown on a substrate (40); (B) an evaporation test piece An ohmic contact reflective layer: an ohmic contact reflective layer (45) is deposited on the gallium nitride-based light-emitting diode; (C) an electroplated copper region is defined: a thickness of 50-200 μm can be used on the ohmic contact reflective layer (45) The thick photoresist (PR, 46) defines several electroplated copper regions, and the electroplated copper regions are independent of each other; (D) electroplated copper substrate: electroplated copper substrate (47), electroplated only with copper The number of electroplated copper regions defined in step C forms a plurality of mutually independent copper substrates (47); (E) Stripping the substrate: peeling the substrate by laser (40); (F) fabricating the electrode: removing the undoped gallium nitride layer (u-GaN, 41), and n-doping the gallium nitride layer An n-GaN electrode (48) was formed on (n-GaN, 42).

Please refer to the third figure. Step D1 can be added between step D and step E. Step F1 can be added to step F1. The step D1 is to glue the free ends of the mutually independent copper substrates (47). Adhesive layer (49) is bonded, and a carrier (50) is adhered to the adhesive layer (49) to increase the structural strength of the test piece after the substrate (40) is peeled off; the step F1 is to remove the adhesive. Adhesive layer (49) and carrier (50). The adhesive layer (49) may be a fluorocarbon rubber, and the carrier (50) may be a sapphire substrate (Sapphire).

A preferred embodiment is provided below:

[Examples]

Please refer to the fourth to sixth figures. The steps of this embodiment are as follows:

a. Test piece cleaning (20): Before the component process begins, the test piece (sapphire substrate plus (GaN LED) is soaked in acetone, shaken with an ultrasonic oscillator, and then the test piece is soaked in isopropyl. The alcohol was shaken with an ultrasonic oscillator to remove the acetone on the test piece. Finally, the test piece was shaken with DI water and dried with a nitrogen gun.

b. evaporation of ohmic contact reflective layer (21): p-type contact and reflective metal fabrication in addition to light reflection without being absorbed by the substrate, must also consider with p-type gallium nitride layer (p-GaN) Ohmic contact, and adhesion of electroless copper afterwards; common p-type contact and reflective metals can be platinum (Pt), ITO/ Titanium/aluminum/titanium/gold (ITO/Ti/Al/Ti/Au) or nickel/silver (Ni/Ag) series, the metal layer used in the present invention is nickel/silver/titanium/gold (Ni/Ag/Ti/Au The following tempering process is carried out in an oxygen atmosphere.

c. tempering treatment (22): p-type gallium nitride layer (p-GaN) with high work function metal should be tempered to form an ohmic junction; the furnace tube is heated to 500 ° C and filled with oxygen high temperature environment The test piece is pushed into the furnace tube for heat tempering treatment, and finally the test piece is taken out to complete the tempering treatment.

d. Define the copper plating area (23): Please refer to the fifth figure to define the copper plating area. It is necessary to achieve a thick photoresist (PR, 30) with a thickness of 50-200 μm to define the required plating area (31). The reason for the photoresist (30) is to ensure the formation of mutually independent copper substrates. If a general photoresist is used, it is still possible for the copper substrate to form a connected region, which is not advantageous for the subsequent process.

E-plated copper substrate (24): Please refer to the sixth figure. The copper metal substrate (32) prepared by electroplating has the advantages of high-speed coating, low cost and easy mass production. We use copper sulfate solution to carry out the electroplating copper process. The test piece to be electroplated is placed at the cathode of the plating bath, the copper block is placed at the anode of the plating bath, and the growth of the metal substrate is performed in the copper sulfate solution. After the electroplating is completed, it is taken out by the plating solution, and then placed in deionized water (D.I water) and washed with an ultrasonic oscillator, that is, the electroplated copper metal substrate (32) is completed.

f. Laser Peeling Sapphire Substrate (25): We used an excimer KrF laser (λ = 248 nm) to strip the sapphire substrate. In the laser peeling test, the test piece must be carried out with the sapphire substrate in the downward direction of the upper copper substrate, and the test piece position is adjusted to the laser focusing surface to ensure uniform laser energy distribution at each point; The shot will decompose GaN into nitrogen and gallium metal. Therefore, after the laser is peeled off, the test piece should be immersed in diluted hydrochloric acid (HCl: H ₂ O = 1:1) to remove the residual gallium metal.

g. Removal of u-GaN (26): After sapphire stripping, an undoped gallium nitride layer (u-GaN) exists in the sapphire substrate and the gallium nitride film, and the undoped gallium nitride electrical property Poor; an inductively coupled plasma etching machine (ICP) is used to remove the undoped gallium nitride layer (u-GaN).

hn-GaN electrode fabrication (27): After removing the undoped gallium nitride layer (u-GaN), the test piece was vapor-deposited using an electron gun (E-GUN) at a vacuum of 3 × 10 ^-6 torr. / Gold (Cr/Au) as an n-GaN electrode.

Wherein, after the test piece cleaning (a. step), the platform independent (mesa) and sidewall protection processes may be performed, and then the ohmic contact reflective layer (b. step) is fabricated, and the platform (mesa) independent process is used. Plasma-assisted chemical vapor deposition (PECVD) growth of cerium oxide (SiO ₂ ) film, used as a protective layer for plasma etching, and then using the exposure lithography technology to create a platform pattern, and then The oxide pattern is etched using a buffer oxide etching (BOE), and finally the photoresist is removed. After the pattern is defined, the gallium nitride epitaxial etch is performed using an inductively coupled plasma (ICP). The structural layer is etched from p-type gallium nitride to n-type gallium nitride to expose the sapphire substrate to form a 1 mm × 1 mm (or larger) platform, and finally the cerium oxide (SiO ₂ ) is removed to complete the platform. Independent, the platform is independent to isolate the GaN current. The sidewall protection process uses cerium oxide (SiO ₂ ) as a sidewall protective layer, and a cerium oxide (SiO ₂ ) film is grown by plasma-assisted chemical vapor deposition (PECVD), and a pattern is formed using exposure lithography. The oxide etchant (BOE) etches the pattern of the platform and finally removes the photoresist, ie the sidewall protection layer of the platform is completed.

Developed a large-area vertical Dicing-free copper substrate gallium nitride light-emitting diode with the help of electroplated copper and laser lift-off technology, combined with the definition of thick film photoresist. The difficulty in cutting the substrate and the problem of metal leakage to the sidewall during copper cutting cause leakage current of the component, and avoid the problem of subsequent process caused by warpage of the copper substrate after the laser peeling off the sapphire substrate.

The present invention has been described with reference to the preferred embodiments of the present invention. However, those skilled in the art can change and modify the present invention without departing from the spirit and scope of the invention. Such changes and modifications shall be covered in the scope defined by the following patent application.

. Conventional part:

(60)‧‧‧Sapphire substrate

(61) ‧‧‧ undoped gallium nitride layer

(62) ‧‧‧n-doped gallium nitride layer

(63) ‧‧‧ gallium nitride light-emitting layer

(64)‧‧‧p-type doped gallium nitride layer

(65)‧‧‧ Platform sidewall protection

(66) ‧ ‧ ohm contact reflective layer

(67)‧‧‧Copper substrate

(68)‧‧‧Cr/Au electrodes

(70)‧‧‧Test strip cleaning

(71) ‧‧‧ platform (mesa) independence

(72) ‧‧‧ Platform sidewall protection

(73)‧‧‧Extruded ohmic contact reflective layer

(74) ‧ ‧ tempering

(75) ‧‧‧Electroplated copper substrate

(76)‧‧‧Laser stripped sapphire substrate

(77)‧‧‧Remove u-GaN

(78) ‧‧‧n-GaN electrode fabrication

. This creative part:

(20)‧‧‧Test strip cleaning

(21)‧‧‧Deposition of ohmic contact reflective layer

(22) ‧ ‧ tempering

(23) ‧‧‧Defining electroplated copper areas

(24)‧‧‧Electroplated copper substrate

(25)‧‧‧Laser stripped sapphire substrate

(26)‧‧‧Remove u-GaN

(27) ‧‧‧n-GaN electrode fabrication

(30)‧‧‧Thick light resistance

(31) ‧‧‧ plating area

(32)‧‧‧ copper metal substrate

(40) ‧‧‧Substrate

(41) ‧‧‧ undoped gallium nitride layer

(42) ‧‧‧n-doped gallium nitride layer

(43) ‧‧‧ gallium nitride light-emitting layer

(44)‧‧‧p-type doped gallium nitride layer

(45) ‧ ‧ ohm contact reflective layer

(46) ‧‧‧Thick light resistance

(47)‧‧‧Copper substrate

(48)‧‧‧n-GaN electrodes

(49)‧‧‧Adhesive layer

(50) ‧ ‧ carrier

First Figure: Flow chart of the manufacturing process of the present invention.

Second figure: Schematic diagram of the simplified process of the present invention.

Third: A simplified process schematic diagram of the present invention using an adhesive layer.

Fourth Figure: A flow chart for manufacturing an embodiment of the present invention.

Fifth Figure: An SEM image of a post-electrode region defining element in accordance with an embodiment of the present invention.

Figure 6 is a SEM image of a post-copper copper element in accordance with one embodiment of the present invention.

Figure 7: Flow chart of the fabrication of a conventional metal substrate light-emitting diode.

Figure 8: Schematic diagram of a simplified process for a conventional metal substrate light-emitting diode.

(40) ‧‧‧Substrate

(41) ‧‧‧ undoped gallium nitride layer

(42) ‧‧‧n-doped gallium nitride layer

(43) ‧‧‧ gallium nitride light-emitting layer

(44)‧‧‧p-type doped gallium nitride layer

(45) ‧ ‧ ohm contact reflective layer

(46) ‧‧‧Thick light resistance

(47)‧‧‧Copper substrate

(48)‧‧‧n-GaN electrodes

Claims (8)

The invention relates to a process of a vertical cut-free metal substrate light-emitting diode, thereby avoiding the warpage of the copper substrate after the metal splash and the substrate are peeled off after the subsequent copper substrate cutting, and the steps include the following steps: A. providing a cleaning a test piece for growing a gallium nitride-based light-emitting diode (GaN LED) on a substrate; B. depositing an ohmic contact reflective layer on the gallium nitride-based light-emitting diode C. On the ohmic contact reflective layer, a plurality of electroplated copper regions are defined by a thick photoresist having a thickness of 50-200 μm, and the electroplated copper regions are independent of each other; D. electroplating copper is used in C The number of the electroplated copper regions defined by the step forms a plurality of mutually independent copper substrates; D1. The free ends of the mutually independent copper substrates are bonded by an adhesive layer, and a carrier is adhered to the adhesive layer. To increase the structural strength of the test piece after peeling off the substrate; E. peeling off the substrate of the test piece by laser; F. removing the undoped gallium nitride layer (u-GaN), and n-type nitriding An n-GaN electrode is formed on the gallium layer (n-GaN); F1. the adhesive layer is removed from the carrier. The process of the vertical cut-free metal substrate light-emitting diode according to claim 1, wherein the adhesive layer is fluororubber, The carrier is a sapphire substrate. The process of the vertical cut-free metal substrate light-emitting diode according to claim 1 or 2, wherein a step A1 is added between the step A and the step B, and the step A1 is performed on the test piece. The process of platform independence (mesa), and then the process of sidewall protection. The method of claim 1 , wherein the substrate of the test piece of the step A is a sapphire substrate. The process of the vertical cut-free metal substrate light-emitting diode according to claim 1, wherein the ohmic contact reflective layer of the step B is a Pt metal, an ITO/Ti/Al/Ti/Au metal, Ni/Ag metal or Ni/Ag/Ti/Au metal. The process of the vertical cut-free metal substrate light-emitting diode according to claim 4, wherein the step E uses an excimer KrF laser (λ=248 nm) to peel off the sapphire substrate. The process of the vertical cut-free metal substrate light-emitting diode according to claim 1, wherein the step F uses an inductively coupled plasma etching machine (ICP) to remove the undoped gallium nitride system. Layer (u-GaN). The process of the vertical cut-free metal substrate light-emitting diode according to claim 1, wherein the n-GaN electrode in the step F is a Cr/Au metal.