KR20160113799A - Grinding method of sapphire wafer using UV mounting process - Google Patents

Grinding method of sapphire wafer using UV mounting process Download PDF

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Publication number
KR20160113799A
KR20160113799A KR1020150039899A KR20150039899A KR20160113799A KR 20160113799 A KR20160113799 A KR 20160113799A KR 1020150039899 A KR1020150039899 A KR 1020150039899A KR 20150039899 A KR20150039899 A KR 20150039899A KR 20160113799 A KR20160113799 A KR 20160113799A
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KR
South Korea
Prior art keywords
pet film
sapphire wafer
sapphire
wafer
vacuum chuck
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KR1020150039899A
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Korean (ko)
Inventor
김영진
김찬호
정주현
Original Assignee
경기대학교 산학협력단
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Priority to KR1020150039899A priority Critical patent/KR20160113799A/en
Publication of KR20160113799A publication Critical patent/KR20160113799A/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer
    • H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic System or AIIIBV compounds with or without impurities, e.g. doping materials
    • H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
    • H01L21/302—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to change their surface-physical characteristics or shape, e.g. etching, polishing, cutting
    • H01L21/304—Mechanical treatment, e.g. grinding, polishing, cutting
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/02002—Preparing wafers
    • H01L21/02005—Preparing bulk and homogeneous wafers
    • H01L21/02008—Multistep processes
    • H01L21/0201—Specific process step
    • H01L21/02024—Mirror polishing
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/005—Processes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/02—Bonding areas; Manufacturing methods related thereto
    • H01L2224/03—Manufacturing methods
    • H01L2224/036—Manufacturing methods by patterning a pre-deposited material
    • H01L2224/03602—Mechanical treatment, e.g. polishing, grinding
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
    • H01L2924/10—Details of semiconductor or other solid state devices to be connected
    • H01L2924/11—Device type
    • H01L2924/12—Passive devices, e.g. 2 terminal devices
    • H01L2924/1204—Optical Diode
    • H01L2924/12041—LED

Abstract

The present invention relates to a mounting and grinding method capable of grinding uniformly both sides of a wafer while maintaining the inherent shape of the wafer, and more particularly, to a mounting and grinding method capable of transmitting ultraviolet (UV) Placing a PET film on a vacuum chuck of a transparent material and holding the PET film in vacuum; Discharging a UV curable resin on a gripped PET film and placing a sapphire wafer thereon; Pressurizing the upper surface of the sapphire wafer with a press to spread the UV cured resin evenly over the entire backside of the substrate; Filling the vacant space with the PET film by the UV curing resin while the sapphire wafer is returned to its original shape by removing the press; Irradiating a UV light source filled in a vacant space between the sapphire substrate and the PET film, curing the UV light source, and performing UV mounting; Polishing and planarizing the front surface of the UV-mounted sapphire wafer; Washing the PET film and the UV cured resin after the front polishing is completed, and inverting the sapphire wafer from which the PET film has been removed, and polishing the back surface by polishing under the same conditions as the front surface.

Description

[0001] The present invention relates to a sapphire wafer grinding method using a UV mounting process,

The present invention relates to a sapphire wafer grinding method using an UV mounting process.

The sapphire wafer is a basic material widely used for LED manufacturing. It is suitable as a base substrate for growing GaN because it has a relatively small coefficient of thermal expansion and a comparatively small amount of lattice mismatch compared to GaN.

In order to develop high-quality LEDs, sapphire single crystals must be free from crystal defects and must be fabricated so that the thickness deviation (TTV) and warping (BOW) of the sapphire substrate are reduced so as to be suitable for epitaxy growth in the wafer processing process. Thereby contributing to improvement of the brightness and reliability of the LED.

FIG. 1 is a view showing a lapping process using a lapping machine in a conventional sapphire wafer processing process. In the lapping process after the cutting process, a wafer is bent in such a manner as to apply pressure in an upper / And then polishing is performed. However, there is a limit to the control of the substrate shape due to the nature of returning to the original characteristics again when the pressing pressure is removed after completion of polishing. In addition, there is a problem in that the reproducibility is largely varied depending on the operator depending on the surface management, so that it is difficult to control the flatness and productivity is deteriorated due to a long processing time.

Patent Document 1 discloses a method of flattening a sapphire substrate by removing residual stress inside the sapphire substrate by a heat treatment to perform planarization of the surface.

1. Korean Patent Publication No. 10-2014-0118754

In order to solve the above problems, it is an object of the present invention to provide a mounting and grinding method capable of grinding a wafer while retaining the inherent shape of the wafer and having a uniform shape on both sides, instead of polishing by applying physical pressure.

A method for grinding sapphire wafers using a UV mounting process according to the present invention is a method for grinding a PET film on a vacuum chuck of a transparent material mounting apparatus capable of transmitting ultraviolet (UV) ; A step of discharging a UV curable resin containing an oligomer, a monomer and a photopolymerization initiator in a ratio of 5: 4: 1 on a gripped PET film, and placing a sapphire wafer thereon; Pressurizing the upper surface of the sapphire wafer with a pressure of 0.02 kg / cm 2 to 0.03 kg / cm 2 to spread the UV cured resin evenly over the entire backside of the substrate; Filling the vacant space with the PET film by the UV curing resin while the sapphire wafer is returned to its original shape by removing the press; Irradiating a UV light source under a vacuum chuck of the mounting equipment with a UV light curing resin filled in a vacant space between the sapphire substrate and the PET film at a light intensity of 200 to 300 mW and UV-curing the UV light source; Loading a UV-mounted sapphire wafer onto a vacuum chuck of a grinding machine and polishing and planarizing the diamond wheel by descending at a three-step descent rate; Washing the surface of the sapphire wafer after the front surface polishing is completed, removing the PET film, and inverting the sapphire wafer from which the PET film has been removed, and polishing the back surface by polishing under the same conditions as the front surface.

The vacuum chuck of the mounting equipment is quartz glass or soda glass, and the thickness of the PET film is 50 to 100 μm.

The UV curable resin may further include a photopolymerization accelerator, a leveling agent, a stabilizer or a defoaming agent.

The diamond wheel is characterized by setting an aircut of 100 [mu] m or more.

The three-step descending speed is set to 2.0 .mu.m / sec, 1.0 .mu.m / sec, and 0.5 .mu.m / sec, and the application time is set to a ratio of 2: 1: 1.

Since the sapphire wafer grinding method using the UV mounting process according to the present invention maintains the original shape of the sapphire wafer and processes it, it is possible to ensure the reproducibility of the product since both sides can have a uniform shape after the completion of the process, Uniformity can be maintained, process quality unstable by a worker can be solved, and productivity can be improved.

In addition, it can contribute to the improvement of the LED chip yield and the production of high quality LED in the after-defense industry.

FIG. 1 is a view showing a lapping process in a sapphire wafer processing process according to a conventional technique.
2 is a flow chart of a sapphire wafer grinding method using a UV mounting process according to the present invention.
Figure 3 shows the UV mounting process according to the invention.
4 shows a photograph in which a sapphire wafer for LED is mounted on a transparent vacuum chuck and a vacuum chuck.
5 shows a grinding method of a sapphire wafer using UV mounting according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The embodiments of the present invention are for describing one invention, and the scope of rights is not limited to the illustrated embodiments, For the sake of clarity, only the core contents are enlarged and omitted, so that they should not be construed to be limited to drawings.

2 is a flow chart of a sapphire wafer grinding method using a UV mounting process according to the present invention.

A sapphire crystal ingot grown by a czochralski method or the like is cut, and the edge of the cut wafer is round-polished by an edge grinding process. Edge grinding serves to significantly reduce wafer breakage in subsequent processes. The thickness of the cut sapphire wafer is about 1600 to 2000 um, which may vary depending on the final substrate specification.

Figure 3 shows the UV mounting process according to the invention. The parameters of the UV mounting process for 6 to 8 inch large diameter sapphire substrates include the pressure applied to the substrate, the composition and viscosity of the cured resin, the amount of cured resin discharged according to the area, the wavelength and amount of UV irradiation, have.

3 (a) shows a state in which the PET film 3 is placed on a vacuum chuck 11 of a mounting apparatus and held by vacuum, and the cured resin 2 is discharged onto the gripped PET film, and the sapphire wafer 1 is placed thereon.

The vacuum chuck 11 of the mounting equipment can be made of quartz glass or soda glass as a transparent material through which UV can be transmitted. The PET film is preferably 50 to 100 탆 in thickness to such an extent that it is easy to transmit UV and can be separated from the sapphire wafer. 4 shows a photograph in which a sapphire wafer for LED is mounted on a transparent vacuum chuck and a vacuum chuck.

The UV curing resin is a resin which undergoes radical polymerization and Lewis acid in the photopolymerization initiator when UV is irradiated to cause a polymerization reaction to form a crosslinking curing resin. The prepolymer having a polymerizable functional group of a double bond, a monomer as a reactive diluent, Photoinitiators are the main ingredients. UV curing resins are environmentally friendly because they have a very short curing time and are free from solvents as compared with thermosetting resins.

The prepolymer oligomer is used to shorten the curing time and reinforce various physical properties, such as bisphenol A epoxy diacrylate.

As the monomer, 2-hydroxyl methylacrylate, 1,6-hexanediol diacrylate and dipentaerythritol hexaacrylate having 1, 2, and 6 acrylic groups, respectively, are used.

Examples of the photopolymerization initiator include benzoin ether, benzophenone, and acetophenone. Examples of the photopolymerization initiator include hydroxy dimethyl acetophenone, 2,4,6-trimethylbenzoyldiphenyl-phosphineoxide, and 2,4-diethylthioxanthone. .

In the present invention, an oligomer, a monomer, and a photopolymerization initiator are used in a ratio of 5: 4: 1. In addition, photopolymerization accelerators, leveling agents, stabilizers, antifoaming agents and the like can be used.

4-dimethylamino benzoate (EDMAB) or hydrophilic aliphatic 2-dimethylaminoethyl methacrylate (DMAEMA), which is relatively hydrophobic, is used together with a photopolymerization initiator, ) May be used.

As the leveling agent, talc and the like can be used to give dimensional stability and smoothness after curing.

The viscosity of the UV curable resin is preferably 700 to 1000 cps, and the discharge amount is preferably 0.05 g / cm 2 to 0.06 g / cm 2. The higher the viscosity of the UV curable resin, the more difficult it is to spread evenly over the entire surface of the sapphire substrate and the PET film. If the viscosity is low, the PET film and the sapphire substrate are separated from each other.

3 (b) presses the press 12 to cause the UV cured resin to diffuse and evenly spread over the entire backside of the substrate. The pressing force is applied to the pressure level of 0.02 kg / cm 2 to 0.03 kg / cm 2 so that the bent sapphire wafer can be spread.

3 (c) shows a process of lifting the press after pressurization and filling the vacant space with the UV curable resin as the sapphire wafer returns to its original shape.

Fig. 3 (d) shows a UV light source 13 irradiated under a vacuum chuck to the UV curable resin filled in the vacant space between the sapphire substrate and the PET film to cure. At this time, depending on the type of the photopolymerization initiator, the wavelength range of 375 nm increases the adhesion efficiency, and the amount of light is at least 100 mW. Curing is completed in 10 seconds at a light intensity of 200 to 300 mW based on an 8-inch sapphire substrate.

5 shows a grinding method of a sapphire wafer using UV mounting according to the present invention.

5 (a) shows a state in which a sapphire wafer having been UV-mounted is loaded on a grinding machine. The sapphire wafer 1 having the thickness deviation TTV or the bending BOW is restored to its original shape by removing the pressure of the press and is mounted on the PET film 3 in a state of a thickness deviation or warp, And is loaded on the vacuum chuck 14 (work chuck).

FIG. 5 (b) shows a state in which the front surface grinding is completed. In the grinding equipment, the convex portion or protruding portion of the diamond wheel is polished and flat. The thickness of the cut sapphire wafer is about 1600 to 2000 um, which may vary depending on the final substrate specification.

In the case of wafers cut to the same target, aircut is set considering the difference in thickness between wafers. A proper aircut causes the wheel to drop more than 100um and then lower the wheel. The diamond wheel is rotated at 300 rpm while the diamond wheel is rotated at 1500 rpm. The diamond wheel is set at a three-step descent rate of 2.0 μm / sec, 1.0 μm / sec and 0.5 μm / sec. The application time of the wheel feed speed based on the thickness to be polished is set at a ratio of 2: 1: 1.

The grinding diamond wheel can maintain the surface roughness (Ra) value at 0.6 ~ 0.8um level by ensuring the back surface roughness of the lapping level by using metal diamond of # 325 mesh.

Figure 5 (c) shows the backside polishing of the sapphire wafer. After the front grinding is completed, clean, rinse and dry, and then remove the PET film. The PET film can be physically removed, and only the wafer is separated with the UV cured resin adhered to the PET film. Types of Cured Resin and PET Film The UV cured resin may remain on the wafer depending on the conditions such as the UV wavelength and the light amount condition. In the present invention, however, the UV cured resin does not remain on the sapphire wafer. The back side of the sapphire wafer from which the PET film has been removed is turned upside down and loaded on a vacuum chuck of the grinding machine, and polished and planarized under the same conditions as the front side.

The grinding process is performed on a cassette basis, and the front grinding product is prepared as a rear grinding atmosphere by removing the PET film before the next cassette is inserted.

FIG. 5 (d) shows a sapphire wafer having both front and rear surfaces polished and a flat sapphire wafer from which a thickness deviation and warped state are removed.

Since the sapphire wafer grinding method using the UV mounting process according to the present invention maintains the original shape of the sapphire wafer and processes it, it is possible to ensure the reproducibility of the product since both sides can have a uniform shape after the completion of the process, Uniformity can be maintained, process quality unstable by a worker can be solved, and productivity can be improved.

In addition, it can contribute to the improvement of the LED chip yield and the production of high quality LED in the after-defense industry.

1: sapphire wafer 2: UV cured resin
3: PET film 11: vacuum chuck of mounting equipment
12: Press 14: Vacuum chuck of the grinding machine

Claims (5)

Placing a PET film on a vacuum chuck of a transparent material capable of transmitting ultraviolet (UV) light and holding the PET film in vacuum;
A step of discharging a UV curable resin containing an oligomer, a monomer and a photopolymerization initiator in a ratio of 5: 4: 1 on a gripped PET film, and placing a sapphire wafer thereon;
Pressing the upper surface of the sapphire wafer with a press at a pressure of 0.02 kg / cm 2 to 0.03 kg / cm 2 to spread the UV cured resin evenly over the entire backside of the substrate;
Filling the vacant space with the PET film by the UV curing resin while the sapphire wafer is returned to its original shape by removing the press;
Irradiating a UV light source under a vacuum chuck of the mounting equipment with a UV light curing resin filled in a vacant space between the sapphire substrate and the PET film at a light intensity of 200 to 300 mW and UV-curing the UV light source;
Loading a UV-mounted sapphire wafer on a vacuum chuck of a grinding machine, lowering the diamond wheel at a descending rate of three steps to polish and planarize the front surface;
Washing after completion of the front grinding and removing the PET film, and
A step of polishing the back side of the sapphire wafer from which the PET film has been removed so as to be polished and loading the sapphire wafer on a vacuum chuck of a grinding machine and polishing and planarizing the sapphire wafer under the same conditions as the front side. The method according to claim 1,
Wherein the vacuum chuck of the mounting equipment is quartz glass or soda glass and the thickness of the PET film is 50 to 100 um. The method according to claim 1,
Wherein the UV curable resin further comprises a photopolymerization accelerator, a leveling agent, a stabilizer or a defoaming agent. The method according to claim 1,
Wherein the diamond wheel has an aircut of at least 100 um. ≪ RTI ID = 0.0 > 15. < / RTI > The method according to claim 1,
Wherein the three-step descending speed is set to 2.0 μm / sec, 1.0 μm / sec, and 0.5 μm / sec, and the application time is set to a ratio of 2: 1: 1, respectively.
KR1020150039899A 2015-03-23 2015-03-23 Grinding method of sapphire wafer using UV mounting process KR20160113799A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20180056187A (en) * 2016-11-18 2018-05-28 일진디스플레이(주) manufacturing apparatus of sapphire wafer

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20140118754A (en) 2013-03-27 2014-10-08 가부시기가이샤 디스코 Method for smoothing a sapphire substrate

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20140118754A (en) 2013-03-27 2014-10-08 가부시기가이샤 디스코 Method for smoothing a sapphire substrate

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20180056187A (en) * 2016-11-18 2018-05-28 일진디스플레이(주) manufacturing apparatus of sapphire wafer

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