CN109671616B - Method for cleaning particles on surface of silicon wafer or lens by laser - Google Patents
Method for cleaning particles on surface of silicon wafer or lens by laser Download PDFInfo
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- CN109671616B CN109671616B CN201910044747.XA CN201910044747A CN109671616B CN 109671616 B CN109671616 B CN 109671616B CN 201910044747 A CN201910044747 A CN 201910044747A CN 109671616 B CN109671616 B CN 109671616B
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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
- H01L21/02041—Cleaning
- H01L21/02098—Cleaning only involving lasers, e.g. laser ablation
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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
- H01L21/02041—Cleaning
- H01L21/02043—Cleaning before device manufacture, i.e. Begin-Of-Line process
Abstract
The invention provides a method for cleaning particles on the surface of a silicon wafer or a lens by laser, which comprises the steps of firstly, coating viscose with adsorption effect on laser on the surface to be cleaned of a workpiece, surrounding particle dirt by the viscose, and solidifying the particle dirt in the viscose after drying; then, irradiating the surface of the viscose layer by using a pulse laser beam, enabling the pulse laser beam to act on the viscose layer to generate shock waves, cracking the viscose layer and particle dirt solidified in the viscose layer under the action of instantaneous heating power of the laser to form fragments with the granularity of 100-300 mu m, and flying away from the surface of a workpiece to separate the particle dirt from the surface to be cleaned of the workpiece; after the workpiece is flushed by high-pressure gas, the workpiece is put into acetone solution for ultrasonic cleaning to remove residues adhered on the surface of the workpiece. Particles on the surface of the workpiece can be effectively cleaned, and the surface of the workpiece is protected from direct ablation of laser, so that the surface of the silicon wafer is prevented from being damaged by the thermal effect of the laser.
Description
Technical Field
The invention relates to the field of surface treatment, in particular to a method for cleaning particles on the surface of a silicon wafer or a lens by laser.
Background
The integrated circuit board silicon wafer usually needs to be cleaned before packaging to remove particle dirt attached to the surface of the silicon wafer in the processing process, so that the performance of the silicon wafer is improved. High power lens lenses typically require cleaning prior to coating to remove particulate contaminants adhering to the lens surface during processing, thereby increasing the damage threshold of the lens. The adhesion mechanism of micro-nano particle dirt on the surface of a workpiece is completely different from that of larger-size particle dirt, plastic deformation can be generated under the self weight, so that the adhesion force is greatly increased, and conventional chemical cleaning and ultrasonic cleaning cannot be removed, so that the cleaning of the micro-nano particle dirt is a difficult problem in the post-treatment process of a silicon wafer or the cleaning of a lens.
The laser cleaning is a novel and efficient cleaning means, and can effectively remove various types of surface dirt, however, the laser directly acts on the surface of the silicon wafer to damage the original surface structure, so that the laser cannot be directly used for cleaning the surface of the silicon wafer. For cleaning of lens materials, because the particulate contaminants adhering to the lens surfaces are generally lens materials, the absorptivity of the particulate contaminants to laser light is very low, so that the particulate contaminants need to be cleaned in a high-power laser full-coverage mode, the cleaning efficiency is low, the production cost is high, and dirt cannot be removed in some cases.
Disclosure of Invention
Aiming at the defects in the prior art, the invention provides a method for cleaning particles on the surface of a silicon wafer or a lens by laser, which can effectively clean the particles on the surface of a workpiece.
The present invention achieves the above technical object by the following means.
A method for cleaning particles on the surface of a silicon wafer or a lens by laser is characterized in that,
firstly, coating viscose with adsorption effect on laser on the surface to be cleaned of a workpiece, surrounding particle dirt by the viscose, and solidifying the particle dirt in the viscose after drying; the viscose can be acrylic epoxy resin, or a mixture formed by mixing acrylic epoxy resin and nano carbon particles according to a volume ratio of 4:1, or a mixture formed by acrylic epoxy resin, nano silicone powder, polyurethane foam stabilizer and nano carbon powder particles;
then, irradiating the surface of the viscose layer by using a pulse laser beam, enabling the pulse laser beam to act on the viscose layer to generate shock waves, cracking the viscose layer and particle dirt solidified in the viscose layer under the action of instantaneous heating power of the laser to form fragments with the granularity of 100-300 mu m, and flying away from the surface of a workpiece to separate the particle dirt from the surface to be cleaned of the workpiece; after the workpiece is flushed by high-pressure gas, placing the workpiece into an acetone solution for ultrasonic cleaning to remove residues adhered on the surface of the workpiece;
the pulse width of the pulse laser beam is 10-300 ns, the diameter of the laser beam reaching the surface of the absorption layer is 50-60 mu m, and the power density is 10 6 ～10 7 GW/cm 2 。
Further, the adhesive having an adsorption effect on the laser consists of an acrylic epoxy layer and an absorption layer coated on the acrylic epoxy layer, the absorption layer being coated before the acrylic epoxy layer is not dried, so that the absorption layer is bonded with the acrylic epoxy layer.
Further, the absorption layer is black amino paint with the thickness of 5-20 mu m; the thickness of the acrylic epoxy resin layer is 50-80 mu m.
Further, the absorption layer is a black adhesive tape, and the black adhesive tape is a black polyester adhesive tape; the thickness of the black polyester adhesive tape is 5-10 mu m; the thickness of the acrylic epoxy resin layer is 30-100 μm.
Further, coating a flowing water film on the upper surface of the black adhesive tape; the pulse laser beam irradiates on the surface of the black adhesive tape through the flowing water film, and the whole surface of the silicon wafer is subjected to laser cleaning.
Further, the flowing water film is a deionized water film, the thickness of the flowing water film is 1-1.5 mm, and the flow speed is 1-3 cm/s; the black adhesive tape is a black polyester adhesive tape with the thickness of 5-15 mu m; the thickness of the acrylic epoxy resin is 30-100 mu m.
Further, the thickness of the viscose is 30-100 μm.
Further, after the adhesive is cured, a power density of 1×10 is adopted 5 ～5×10 5 GW/cm 2 The pulsed laser beam irradiation of the (4) ablates the adhesive surface with the adsorption function of the laser to form a regular blind hole array; and then, pulse laser beams are irradiated at the middle positions of the adjacent four blind holes, namely laser cleaning points, so that the laser cleaning is carried out on the whole surface of the workpiece.
Further, the distance d between adjacent blind holes 1 Distance d from adjacent laser cleaning spot 2 The aperture of the blind hole is 40-60 μm and the depth is 20-40 μm with the diameter of 100-300 μm.
Further, the adhesive with adsorption effect on laser is formed by coating the following coating materials,
the volume content of the acrylic epoxy resin in the coating material is 60-70%, the volume content of the nano silicone powder is 5-8%, the volume content of the polyurethane foam stabilizer is 6-8%, and the volume content of the nano carbon powder particles is 20-25%; the thickness of the coating is 30-100 micrometers.
Further, the size of the particle dirt is 0.5-50 μm, and the volume percentage concentration of the acetone solution is 50%.
The working principle of the method for cleaning particles on the surface of a silicon wafer or a lens by laser is as follows:
and (3) coating a viscose coating with an adsorption effect on laser on the surface of the workpiece, wherein after the viscose is coated on the surface of the lens, the particle dirt is surrounded by the viscose, and the particle dirt is solidified in the viscose after being dried. Irradiating the surface of the viscose layer by using a pulse laser beam, wherein the pulse laser beam acts on the viscose layer, the viscose layer has an adsorption effect on the laser and generates shock waves, and under the instant thermal effect of the laser, the viscose layer and particle dirt solidified in the viscose are cracked to form fragments with the granularity of 100-300 mu m and fly away from the surface of a workpiece, so that the particle dirt is separated from the surface to be cleaned of the workpiece; after the workpiece is flushed by high-pressure gas, the workpiece is put into acetone solution for ultrasonic cleaning to remove residues adhered on the surface of the workpiece.
According to the method for cleaning particles on the surface of a silicon wafer or a lens by using laser, the viscose coating with an adsorption effect on the laser can adopt resin glue as a binding material, and a layer of absorption layer is coated on acrylic epoxy resin; or the nano carbon particles are mixed into the binding material, so that the binding material mixed with the nano particles has the performance of absorbing laser. The resin adhesive adopts brittle acrylic epoxy resin, can well cover the particle dirt, is easy to crack after hardening, can form fragments of 100-300 mu m under the action of laser beam heating power and shock waves, and ensures that the particle dirt is peeled off from the surface of the lens, and has good cleaning effect; under the thermal action of the laser beam, the size of the formed stripping object is larger than the diameter of the laser beam when irradiated to the surface of the absorption layer, so that the adjacent laser spots do not need to be overlapped, the distance between the spots is 2-5 times of the diameter of the spots, and the cleaning efficiency can be greatly improved.
Meanwhile, the existence of the viscose coating ensures that the laser beam does not directly act on the surface of the silicon wafer, and protects the surface of the workpiece from direct ablation of laser, thereby avoiding the surface of the silicon wafer from being damaged by the laser thermal effect.
Drawings
FIG. 1 is a schematic diagram of a method for cleaning particles on a lens surface by laser according to an embodiment of the invention.
FIG. 2 is a schematic diagram of one embodiment of a method for laser cleaning particles on a surface of a silicon wafer.
FIG. 3 is a schematic diagram of a method for cleaning particles on a lens surface by laser according to an embodiment of the invention.
Fig. 4 is a schematic diagram of laser blind hole drilling and laser cleaning positions.
FIG. 5 is a schematic diagram of one embodiment of a method for laser cleaning particles on a surface of a silicon wafer.
Description of the drawings:
1 pulse laser beam, 2 black amino paint, 3 acrylic epoxy resin layer, 4 particle dirt, 5 lens, 6 silicon wafer, 7 black adhesive tape, 8 flowing water film and 11 blind hole; and (3) cleaning the point positions by 12 lasers.
Detailed Description
The invention will be further described with reference to the drawings and the specific embodiments, but the scope of the invention is not limited thereto.
According to the method for cleaning particles on the surface of the silicon wafer or the lens by using the laser, firstly, viscose with adsorption effect on the laser is coated on the surface to be cleaned of the workpiece, particle dirt is surrounded by the viscose, and the particle dirt is solidified in the viscose after being dried. Then, irradiating the surface of the viscose layer by using a pulse laser beam, enabling the pulse laser beam to act on the viscose layer to generate shock waves, cracking the viscose layer and particle dirt solidified in the viscose layer under the action of instantaneous heating power of the laser to form fragments with the granularity of 100-300 mu m, and flying away from the surface of a workpiece to separate the particle dirt from the surface to be cleaned of the workpiece; after the workpiece is flushed by high-pressure gas, the workpiece is put into acetone solution for ultrasonic cleaning to remove residues adhered on the surface of the workpiece.
Example 1
As shown in fig. 1, the cleaning method of the present invention is used to clean a lens 5 made of quartz; the particle dirt 4 on the surface of the lens 5 is made of quartz, and the particle size distribution is 0.5-50 mu m.
Firstly, uniformly coating an acrylic epoxy resin layer 3 with a thickness of about 60 mu m on the surface to be cleaned of the lens 5; coating an absorption layer with the thickness of about 10 mu m on the upper surface of the acrylic epoxy resin layer 3, namely brittle black amino paint 2; drying and hardening the absorption layer and the acrylic epoxy resin layer 3; the absorption layer and the acrylic epoxy layer 3 are sequentially coated on the surface to be cleaned of the lens 5. The pulse laser beam 1 is irradiated on the surface of the absorption layer, the distance between the focused light spots is 100 μm, and the laser cleaning is performed on the whole surface of the lens 5. After the lens 5 was purged with high pressure gas, it was put into a 50% acetone solution for ultrasonic cleaning.
When the single pulse energy of the pulse laser is 1mJ, the frequency is 100KHZ, the pulse width of the emitted pulse laser beam 1 is 10ns, and the power density is 10 6 GW/cm 2 The spot diameter when the pulse laser beam 1 reaches the upper surface of the absorption layer after focusing was 50 μm. The laser cleaning efficiency is 2.4m 2 And/h. DetectedThe particle dirt density of the surface of the lens 5 before laser cleaning was 10.8 particles/cm 2 After laser cleaning, the particle dirt density on the surface of the lens 5 was 0.6 particles/cm 2 。
When the single pulse energy of the pulse laser is 0.5mJ and the frequency is 150KHZ, the pulse width of the emitted pulse laser beam 1 is 100ns and the power density is 5 x 10 6 GW/cm 2 The diameter of the light spot when the pulse laser beam 1 reaches the upper surface of the black amino paint 2 after being focused is 55 mu m; the thickness of the black amino paint 2 is about 10 mu m; the thickness of the acrylic epoxy layer 3 was 60 μm. The laser cleaning efficiency is 4.8m 2 And/h. The detection shows that the particle dirt density of the surface of the lens 5 before laser cleaning is 11.2 particles/cm 2 After laser cleaning, the particle dirt density on the surface of the lens 5 was 1.1 particles/cm 2 。
When the single pulse energy of the pulse laser is 1.5mJ and the frequency is 200KHZ, the pulse width of the emitted pulse laser beam 1 is 300ns and the power density is 10 7 GW/cm 2 The diameter of the spot when the pulse laser beam 1 reaches the upper surface of the black amino paint 2 after focusing is 60 mu m; the thickness of the black amino paint 2 is about 10 mu m; the thickness of the acrylic epoxy layer 3 was 60 μm; the lens 5 is made of quartz. The laser cleaning efficiency is 7.2m 2 And/h. The detection shows that the particle dirt density of the surface of the lens 5 before laser cleaning is 11.8 particles/cm 2 After laser cleaning, the particle dirt density on the surface of the lens 5 was 0.7 particles/cm 2 。
Example two
As shown in fig. 2, the silicon wafer 6 is cleaned by the cleaning method of the present invention; the particle dirt 4 on the surface of the silicon wafer 6 is made of silicon, and the particle size distribution is 0.5-50 mu m.
Firstly, uniformly coating an acrylic epoxy resin layer 3 on the surface to be cleaned of a silicon wafer 6, drying and hardening the acrylic epoxy resin layer 3, and adhering a black adhesive tape 7 on the upper surface of the acrylic epoxy resin layer 3; the black tape 7 and the acrylic epoxy resin layer 3 are sequentially coated on the surface to be cleaned of the silicon wafer 6. The surface of the black adhesive tape 7 is irradiated by a pulse laser beam 1, and the whole surface of the silicon wafer 6 is subjected to laser cleaning; removing the black adhesive tape 7 from the surface of the silicon wafer 6; after the silicon wafer 6 is purged by high-pressure gas, an acetone solution of 50% is put into the silicon wafer for ultrasonic cleaning.
After the acrylic epoxy resin layer 3 is coated on the surface of the silicon wafer 6, the particle dirt 4 is surrounded by viscose, and the particle dirt 4 is solidified in the acrylic epoxy resin layer 3 after being dried; the black adhesive tape 7 is adhered with the brittle acrylic epoxy resin layer 3; the black adhesive tape 7 can be used as an absorption layer to absorb the energy of pulse laser well and provide high-amplitude pulse pressure. The pulse laser beam acts on the black adhesive tape 7 with high absorptivity to the pulse laser beam to generate shock waves, under the action of instantaneous heating power of the laser, the acrylic epoxy resin layer 3 and particle dirt solidified in the acrylic epoxy resin layer 3 are cracked into fragments with the granularity of 100-300 mu m and are peeled off from the surface of a silicon wafer, and peeled dirt fragments are adhered to the lower surface of the black adhesive tape 7, so that the broken splashing of dirt is avoided, and the pollution to the environment is reduced. Another outstanding effect of the black tape 7 is that the broken adhesive can be adhered to the tape so as not to generate splashes, and in addition, the existence of the black tape 7 can prevent the subsequent laser pulse irradiation to the surface of the workpiece substrate caused by the falling of the acrylic epoxy resin layer 3 so as to damage the surface of the workpiece.
When the single pulse energy of the pulse laser is 1mJ and the frequency is 100KHZ, the pulse width of the emitted pulse laser beam 1 is 10ns and the power density is 10 6 GW/cm 2 The diameter of the spot is 50 μm when the pulse laser beam reaches the upper surface of the black tape 7 after focusing; the black adhesive tape 7 is a black polyester adhesive tape, and the thickness thereof is about 10 mu m; the thickness of the acrylic epoxy layer 3 was 60 μm. The laser cleaning efficiency is 2.4m 2 And/h. Through detection, the particle dirt density of the surface of the silicon wafer 6 before laser cleaning is 9.7 particles/cm 2 After laser cleaning, the particle dirt density on the surface of the silicon wafer 6 is 0.7 particle/cm 2 。
When the single pulse energy of the pulse laser is 0.5mJ and the frequency is 150KHZ, the pulse width of the emitted pulse laser beam 1 is 100ns and the power density is 5 x 10 6 GW/cm 2 The diameter of the spot is 55 μm when the pulse laser beam reaches the upper surface of the black tape 7 after focusing; the black adhesive tape 7 is a black polyester adhesive tape, and the thickness thereof is about 10 mu m; acrylic epoxyThe thickness of the resin layer 3 was 60. Mu.m. The laser cleaning efficiency is 4.8m 2 And/h. Through detection, the particle dirt density of the surface of the silicon wafer 6 before laser cleaning is 11.4 particles/cm 2 After laser cleaning, the particle dirt density on the surface of the silicon wafer 6 is 1.3 particles/cm 2 。
When the single pulse energy of the pulse laser is 1.5mJ and the frequency is 200KHZ, the pulse width of the emitted pulse laser beam 1 is 300ns and the power density is 10 7 GW/cm 2 The diameter of the spot is 60 μm when the pulse laser beam reaches the upper surface of the black tape 7 after focusing; the black adhesive tape 7 is a black polyester adhesive tape, and the thickness thereof is about 10 mu m; the thickness of the acrylic epoxy layer 3 was 60 μm. The laser cleaning efficiency is 7.2m 2 And/h. Through detection, the particle dirt density of the surface of the silicon wafer 6 before laser cleaning is 10.6 particles/cm 2 After laser cleaning, the particle dirt density on the surface of the silicon wafer 6 is 0.8 particle/cm 2 。
Example III
As shown in fig. 3, the silicon wafer 6 is cleaned by the cleaning method of the present invention; the particle dirt 4 on the surface of the silicon wafer 6 is made of silicon, and the particle size distribution is 0.5-50 mu m.
Firstly, uniformly coating an acrylic epoxy resin layer 3 on the surface to be cleaned of a silicon wafer 6; drying and hardening the acrylic epoxy resin layer 3; a black adhesive tape 7 is stuck on the upper surface of the acrylic epoxy resin layer 3, and the black adhesive tape 7 and the acrylic epoxy resin layer 3 are sequentially covered on the surface to be treated of the silicon wafer 6; a flowing water film 8 is coated on the upper surface of the black adhesive tape 7. The pulse laser beam 1 irradiates the surface of the black adhesive tape 7 through the flowing water film 8, and the whole surface of the silicon wafer 6 is subjected to laser cleaning; removing the black adhesive tape 7 from the surface of the silicon wafer 6; after the silicon wafer 6 is purged by high-pressure gas, an acetone solution of 50% is put into the silicon wafer for ultrasonic cleaning.
After the viscose is coated on the surface of the silicon wafer, the particle dirt is surrounded by the viscose, and the particle dirt is solidified in the viscose after being dried; the black adhesive tape 7 is bonded with brittle adhesive; the pulse laser beam is acted on the black adhesive tape 7 with high absorptivity to the pulse laser beam through the flowing water film to generate shock waves, under the instant heating action of the laser, the adhesive and the particle dirt solidified in the adhesive are cracked into fragments with the granularity of 100-300 mu m and are peeled off from the surface of the silicon wafer, and the peeled dirt fragments are adhered to the lower surface of the black adhesive tape 7 and are separated from the surface of the silicon wafer simultaneously with the black adhesive tape 7. A layer of flowing water film 8 is added, and under the constraint of the flowing water film 8, the pulse laser irradiation generates plasma so as to generate pulse pressure, and the pulse pressure is prolonged to 1.25 times and the amplitude is amplified to 2.5 times. The flowing water film 8 can enhance the amplitude of laser shock waves so as to improve the laser cleaning effect, and in addition, the flowing water film can also ensure that the black adhesive tape 7 bonded with dirt fragments is still kept flat after laser cleaning, so that the laser cleaning effect is ensured.
When the single pulse energy of the pulse laser is 1mJ and the frequency is 100KHZ, the pulse width of the emitted pulse laser beam 1 is 10ns and the power density is 10 6 GW/cm 2 The diameter of the spot is 50 μm when the pulse laser beam reaches the upper surface of the black tape 7 after focusing; the flowing water film 8 is deionized water, the thickness is 1mm, and the flow speed is 1cm/s; the black adhesive tape 7 is a black polyester adhesive tape, and the thickness thereof is about 10 mu m; the thickness of the acrylic epoxy layer 3 was 60 μm. The laser cleaning efficiency is 3.6m 2 And/h. Through detection, the particle dirt density of the surface of the silicon wafer 6 before laser cleaning is 13.4 particles/cm 2 After laser cleaning, the particle dirt density on the surface of the silicon wafer 6 is 1.1 particles/cm 2 。
When the single pulse energy of the pulse laser is 0.5mJ and the frequency is 150KHZ, the pulse width of the emitted pulse laser beam 1 is 100ns and the power density is 5 x 10 6 GW/cm 2 The diameter of the spot is 55 μm when the pulse laser beam reaches the upper surface of the black tape 7 after focusing; the flowing water film 8 is deionized water, the thickness is 1.5mm, and the flow speed is 2cm/s; the black adhesive tape 7 is a black polyester adhesive tape, and the thickness thereof is about 10 mu m; the thickness of the acrylic epoxy layer 3 was 60 μm. The laser cleaning efficiency is 5.6m 2 And/h. Through detection, the particle dirt density of the surface of the silicon wafer 6 before laser cleaning is 14.3 particles/cm 2 After laser cleaning, the particle dirt density on the surface of the silicon wafer 6 is 1.0 particle/cm 2 。
When the single pulse energy of the pulse laser is 1.5mJ and the frequency is 200KHZ, the pulse is emittedThe pulse width of the laser beam 1 is 300ns, and the power density is 10 7 GW/cm 2 The diameter of the spot is 60 μm when the pulse laser beam reaches the upper surface of the black tape 7 after focusing; the flowing water film 8 is deionized water, the thickness is 1.5mm, and the flow speed is 3cm/s; the black adhesive tape 7 is a black polyester adhesive tape, and the thickness thereof is about 10 mu m; the thickness of the acrylic epoxy layer 3 was 60 μm. The laser cleaning efficiency is 10.8m 2 And/h. Through detection, the particle dirt density of the surface of the silicon wafer 6 before laser cleaning is 9.9 particles/cm 2 After laser cleaning, the particle dirt density on the surface of the silicon wafer 6 is 0.7 particle/cm 2 。
Example IV
As shown in fig. 4, the cleaning method according to the present invention is used to clean the lens 5 made of quartz; the particle dirt 4 on the surface of the lens 5 is made of quartz, and the particle size distribution is 0.5-50 mu m.
Firstly, uniformly coating a viscose coating with adsorption effect on laser on the surface to be cleaned of the lens 5; the viscose coating is formed by mixing acrylic epoxy resin and nano carbon particles according to the volume ratio of 4:1. Drying and hardening the viscose coating; the pulsed laser beam 1 irradiates on the surface of the viscose coating, and the whole surface of the lens 5 is subjected to laser cleaning. After the lens 5 was purged with high pressure gas, it was put into a 50% acetone solution for ultrasonic cleaning.
The nano carbon particles have good absorption effect on the pulse laser beam with the wavelength of 1064nm, and the acrylic epoxy resin is added with the nano carbon particles, so that the acrylic epoxy resin has good absorption effect on the pulse laser, and the absorption rate of the acrylic epoxy resin mixed with the nano carbon particles on the pulse laser is more than 50%. Meanwhile, the specific surface of the nano carbon particles is large, and the absorption effect of the adhesive layer on the pulse laser can be greatly improved only by adding a small amount of nano carbon particles. The maturity of the coating application can be reduced, compared with the examples three, to single-layer application, and the complexity of the process is reduced.
In this embodiment: when the single pulse energy of the pulse laser is 1mJ and the frequency is 100KHZ, the pulse width of the emitted pulse laser beam 1 is 10ns, the pulse laser beam is carbon dioxide laser with the wavelength of 10.6 mu m, and the pulse laser beam 1 reaches the upper surface of the viscose coating after being focusedThe spot diameter was 50. Mu.m; the main components of the viscose coating are acrylic epoxy resin and nano carbon particles, and the thickness is 60 mu m; the lens 5 is made of quartz; the granular sewage 4 is made of quartz, and the granularity distribution is 0.5-50 mu m. The laser cleaning efficiency is 2.4m 2 And/h. The detection shows that the particle dirt density of the surface of the lens 5 before laser cleaning is 11.4 particles/cm 2 After laser cleaning, the particle dirt density on the surface of the lens 5 was 0.7 particles/cm 2 。
When the single pulse energy of the pulse laser is 0.5mJ and the frequency is 150KHZ, the pulse width of the emitted pulse laser beam 1 is 100ns, the pulse width is carbon dioxide laser, the wavelength is 10.6 mu m, and the diameter of a light spot is 50 mu m when the pulse laser beam 1 reaches the upper surface of the viscose coating after being focused; the main components of the viscose coating are acrylic epoxy resin and nano carbon particles, and the thickness is 60 mu m. The laser cleaning efficiency is 4.8m 2 And/h. The detection shows that the particle dirt density of the surface of the lens 5 before laser cleaning is 12.8 particles/cm 2 After laser cleaning, the particle dirt density on the surface of the lens 5 was 1.2 particles/cm 2 。
When the single pulse energy of the pulse laser is 1.5mJ and the frequency is 200KHZ, the pulse width of the emitted pulse laser beam 1 is 300ns, the pulse width is carbon dioxide laser, the wavelength is 10.6 mu m, and the diameter of a light spot is 50 mu m when the pulse laser beam 1 reaches the upper surface of the viscose coating after being focused; the main components of the viscose coating are acrylic epoxy resin and nano carbon particles, and the thickness is 60 mu m. The laser cleaning efficiency is 7.2m 2 And/h. The detection shows that the particle dirt density of the surface of the lens 5 before laser cleaning is 10.8 particles/cm 2 After laser cleaning, the particle dirt density on the surface of the lens 5 was 0.8 particles/cm 2 。
Example five
As shown in fig. 5, the silicon wafer 6 is cleaned by the cleaning method of the present invention; the particle dirt 4 on the surface of the silicon wafer 6 is made of silicon, and the particle size distribution is 0.5-50 mu m.
Firstly, uniformly coating a viscose coating with adsorption effect on laser on the surface to be cleaned of a silicon wafer 6; and drying and hardening the viscose coating with the adsorption effect on the laser. Using a power density of 1X 10 5 GW/cm 2 Pulse laser beam 1 irradiation of (2)On the surface of the adhesive coating with adsorption effect on laser, a regular array of blind holes 11 is formed by ablating the surface of the adhesive coating with adsorption effect on laser, the aperture of the blind holes is about 50 mu m, the depth is 30 mu m, and the interval d between the blind holes 1 100 μm; by 5X 10 6 GW/cm 2 The pulse laser beam 1 irradiates the middle position of the adjacent four blind holes 11, namely, the laser cleaning points 12, and the distance d between the adjacent laser cleaning points 12 2 The surface of the entire silicon wafer 6 was laser-cleaned to 100 μm. After the silicon wafer 6 is flushed by high-pressure gas, the silicon wafer is put into a 50% acetone solution for ultrasonic cleaning.
In the embodiment, the micro blind holes distributed regularly are ablated on the viscose coating by adopting a low-power density laser, and then the viscose layer is cleaned by adopting a high-power density pulse laser. Because the existence of the micro blind holes regularly distributed on the surface of the viscose layer, when the laser cleaning with high power density is performed, stress concentration can be generated at the edge of the hole due to the existence of the blind hole array, and the viscose layer can be broken by taking the micro blind holes as the edge, so that the viscose layer is peeled off from the surface of a workpiece in a fixed size, and particle dirt is taken away. The surface of the workpiece is cleaned by controllable technological parameters, so that the cleaning efficiency is improved on one hand; on the other hand, the damage to the surface of the workpiece caused by the fact that the subsequent laser pulse irradiates the surface of the workpiece due to the fact that the viscose layer falls off from the workpiece in advance is avoided.
In this embodiment: when the single pulse energy of the pulse laser is 1mJ and the frequency is 100KHZ, the pulse width of the emitted pulse laser beam 1 is 10ns, the wavelength is 10.6 mu m, and the diameter of a light spot is 50 mu m when the pulse laser beam 1 reaches the upper surface of the viscose coating with adsorption effect on laser after being focused; the main components of the adhesive are acrylic epoxy resin and nano carbon particles, and the thickness is 60 mu m; the granular sewage 4 is made of silicon, and the granularity distribution is 0.5-50 mu m. The particle dirt density of the surface of the silicon wafer 6 before laser cleaning is 11.7 particles/cm 2 After laser cleaning, the particle dirt density on the surface of the silicon wafer 6 is 0.6 particle/cm 2 The surface of the silicon wafer 6 is free from laser ablation damage.
When the single pulse energy of the pulse laser is 0.5mJ and the frequency is 150KHZ, the pulse width of the emitted pulse laser beam 1 is 100ns, and the pulse laser beam is carbon dioxide laser, waveThe length of the laser beam is 10.6 mu m, and the diameter of a light spot is 50 mu m when the pulse laser beam 1 reaches the upper surface of the viscose coating with adsorption effect on the laser after being focused; the main components of the viscose coating with adsorption effect on laser are acrylic epoxy resin and nano carbon particles, and the thickness is 60 mu m. Using a power density of 3X 10 5 GW/cm 2 The pulsed laser beam 1 of (2) irradiates the surface of the viscose coating with adsorption to the laser, ablates the surface of the viscose coating with adsorption to the laser to form a regular array of blind holes 11, the aperture of the blind holes is about 50 μm, the depth is 30 μm, and the interval d between the blind holes 1 200 μm; by 1X 10 7 GW/cm 2 The pulse laser beam 1 irradiates the middle position of the adjacent four blind holes 11, namely, the laser cleaning points 12, and the distance d between the adjacent laser cleaning points 12 2 The surface of the entire silicon wafer 6 was laser-cleaned to 200 μm. The particle dirt density of the surface of the silicon wafer 6 before laser cleaning is 12.5 particles/cm 2 After laser cleaning, the particle dirt density on the surface of the silicon wafer 6 is 1.1 particles/cm 2 The surface of the silicon wafer 6 is free from laser ablation damage.
When the single pulse energy of the pulse laser is 1.5mJ and the frequency is 200KHZ, the pulse width of the emitted pulse laser beam 1 is 300ns, the pulse laser beam is carbon dioxide laser with the wavelength of 10.6 mu m, and the diameter of a light spot is 50 mu m when the pulse laser beam 1 reaches the upper surface of the viscose coating with the adsorption effect on the laser after being focused; the main components of the viscose coating with adsorption effect on laser are acrylic epoxy resin and nano carbon particles, and the thickness is 60 mu m. Using a power density of 5X 10 5 GW/cm 2 The pulsed laser beam 1 of (2) irradiates the surface of the viscose coating with adsorption to the laser, ablates the surface of the viscose coating with adsorption to the laser to form a regular array of blind holes 11, the aperture of the blind holes is about 50 μm, the depth is 30 μm, and the interval d between the blind holes 1 300 μm; by 5X 10 7 GW/cm 2 The pulse laser beam 1 irradiates the middle position of the adjacent four blind holes 11, namely, the laser cleaning points 12, and the distance d between the adjacent laser cleaning points 12 2 The surface of the entire silicon wafer 6 was laser-cleaned to 300 μm. The particle dirt density of the surface of the silicon wafer 6 before laser cleaning is 10.4 particles/cm 2 After laser cleaning, the surface of the silicon wafer 6The density of the granular dirt is 0.7 particle/cm 2 The surface of the silicon wafer 6 is free from laser ablation damage.
Example six
In this embodiment, the adhesive coating layer having an adsorption effect on laser is formed by coating the following coating materials, wherein the coating materials comprise acrylic epoxy resin, nano silicone powder, polyurethane foam stabilizer and nano carbon powder particles, the volume content of the acrylic epoxy resin is 60-70%, the volume content of the nano silicone powder is 5-8%, the volume content of the polyurethane foam stabilizer is 6-8%, and the volume content of the nano carbon powder particles is 20-25%; the thickness of the coating is 30-100 micrometers.
Firstly, uniformly mixing 65% of acrylic epoxy resin, 5% of nano silicone powder, 6% of polyurethane foam stabilizer and 24% of nano carbon powder particles; uniformly coating the mixture of acrylic epoxy resin, nano silicone powder, polyurethane foam homogenizing agent and nano carbon powder particles on the surface to be treated of the silicon wafer, wherein the thickness of the coating is 30-100 microns; then placing the silicon wafer to be treated coated with the auxiliary coating into deionized water, pressurizing to 2-3 MPa, and simultaneously, irradiating and drying the auxiliary coating by using ultraviolet rays, wherein the irradiation time of the ultraviolet rays is 30-50 min; and taking out the silicon wafer from the deionized water, and drying for standby.
The pulse width is 10-300 ns, the frequency is 100KHZ, and the power density is 10 6 ～10 7 GW/cm 2 And (3) irradiating pulse laser on the surface of the auxiliary coating, cleaning the whole surface of the silicon wafer, and removing the particle dirt solidified in the auxiliary coating along with the auxiliary coating from the surface of the silicon wafer. The laser cleaning efficiency is 2.4m 2 And/h. Through detection, the particle dirt density of the surface of the silicon wafer before laser cleaning is 17.5 particles/cm 2 After laser cleaning, the particle dirt density on the surface of the silicon wafer is 1.3 particles/cm 2 。
The acrylic epoxy resin has excellent viscosity and can be well adhered to the surface of a silicon wafer and the surface of particle dirt; the particle dirt is usually silicon, the nano silicone powder and the particle dirt have good adsorption effect, and the effect of curing the particle dirt by the coating can be better due to the effect of the nano silicone powder and the acrylic epoxy resin; the polyurethane foam homogenizing agent can well remove bubbles in the coating, so that the coating can obtain a good particle dirt curing effect; the workpiece to be treated coated with the auxiliary coating is placed in deionized water, pressurized to 2-3 MPa, and the auxiliary coating is dried by ultraviolet irradiation, so that more than 99% of bubbles in the coating can be removed, and the effect of curing granular dirt by the coating is excellent; the addition of the nano carbon powder particles makes the coating no longer transparent to laser, can protect the matrix from being damaged by laser irradiation, and can improve the laser absorptivity of the coating, thereby improving the laser cleaning effect; after the auxiliary coating is dried, the auxiliary coating can be cracked and peeled off from the surface of the silicon wafer under the action of laser. After laser cleaning, the coating residue attached to the surface of the silicon wafer is easily dissolved in organic solvents such as acetone and the like and is easily removed.
The examples are preferred embodiments of the present invention, but the present invention is not limited to the above-described embodiments, and any obvious modifications, substitutions or variations that can be made by one skilled in the art without departing from the spirit of the present invention are within the scope of the present invention.
Claims (11)
1. A method for cleaning particles on the surface of a silicon wafer or a lens by laser is characterized in that,
firstly, coating viscose with adsorption effect on laser on the surface to be cleaned of a workpiece, surrounding the particle dirt (4) by the viscose, and solidifying the particle dirt (4) in the viscose after drying; the viscose can be acrylic epoxy resin, or a mixture formed by mixing acrylic epoxy resin and nano carbon particles according to a volume ratio of 4:1, or a mixture formed by acrylic epoxy resin, nano silicone powder, polyurethane foam stabilizer and nano carbon powder particles;
then, irradiating the surface of the viscose layer by using a pulse laser beam (1), wherein the pulse laser beam (1) acts on the viscose layer to generate shock waves, and under the action of instantaneous heating power of laser, the viscose layer and particle dirt (4) solidified in the viscose are cracked to form fragments with the granularity of 100-300 mu m and fly away from the surface of a workpiece to separate the particle dirt (4) from the surface to be cleaned of the workpiece; after the workpiece is flushed by high-pressure gas, placing the workpiece into an acetone solution for ultrasonic cleaning to remove residues adhered on the surface of the workpiece;
the pulse width of the pulse laser beam (1) ranges from 10ns to 300ns, the diameter of the laser beam reaching the surface of the absorption layer ranges from 50 mu m to 60 mu m, and the power density ranges from 10 6 ～10 7 GW/cm 2 。
2. A method for cleaning silicon wafer or lens surface particles by laser according to claim 1, characterized in that the adhesive having an adsorption effect on the laser consists of an acrylic epoxy layer (3) and an absorption layer coated on the acrylic epoxy layer (3), which absorption layer is coated before the acrylic epoxy layer (3) is not dried, whereby the absorption layer is bonded to the acrylic epoxy layer (3).
3. A method of cleaning particles on the surface of a silicon wafer or lens with a laser according to claim 2, wherein the absorbing layer is black amino paint (2) with a thickness of 5-20 μm; the thickness of the acrylic epoxy resin layer (3) is 50-80 mu m.
4. The method for cleaning particles on the surface of a silicon wafer or lens by using laser according to claim 2, wherein the absorption layer is a black adhesive tape (7), and the black adhesive tape (7) is a black polyester adhesive tape; the thickness of the black polyester adhesive tape is 5-10 mu m; the thickness of the acrylic epoxy resin layer (3) is 30-100 mu m.
5. A method of cleaning silicon wafer or lens surface particles according to claim 4, characterized in that a flowing water film (8) is coated on the upper surface of the black tape (7); the pulse laser beam (1) irradiates the surface of the black tape through the flowing water film (8) to clean the whole surface of the silicon wafer by laser.
6. The method for cleaning particles on the surface of a silicon wafer or lens according to claim 5, wherein the flowing water film (8) is a deionized water film with a thickness of 1-1.5 mm and a flow rate of 1-3 cm/s; the black adhesive tape (7) is a black polyester adhesive tape with the thickness of 5-15 mu m; the thickness of the acrylic epoxy resin is 30-100 mu m.
7. The method of cleaning particles on the surface of a silicon wafer or lens by laser light according to claim 1, wherein the thickness of the adhesive is 30-100 μm.
8. The method of cleaning particles on a silicon wafer or lens surface using a laser as claimed in claim 7, wherein the adhesive has a power density of 1X 10 after curing 5 ～5×10 5 GW/cm 2 The pulsed laser beam (1) irradiates on the adhesive surface with adsorption effect of laser to ablate and form a regular blind hole (11) array; and then, the pulse laser beam (1) is irradiated at the middle position of the adjacent four blind holes (11), namely, the laser cleaning point position (12), and the laser cleaning is carried out on the whole surface of the workpiece.
9. A method for cleaning particles on the surface of a silicon wafer or lens by means of a laser as claimed in claim 8, characterized in that the distance d between adjacent blind holes (11) 1 Distance d from adjacent laser cleaning spot (12) 2 The aperture of the blind hole (11) is 40-60 μm and the depth is 20-40 μm with the diameter of 100-300 μm.
10. The method for cleaning particles on the surface of a silicon wafer or lens according to claim 1, wherein the adhesive having an adsorption effect on the laser is formed by coating a coating material,
the volume content of the acrylic epoxy resin in the coating material is 60-70%, the volume content of the nano silicone powder is 5-8%, the volume content of the polyurethane foam stabilizer is 6-8%, and the volume content of the nano carbon powder particles is 20-25%; the thickness of the coating is 30-100 micrometers.
11. A method for cleaning particles on the surface of a silicon wafer or lens by laser according to claim 1, wherein the size of the particle dirt (4) is 0.5-50 μm and the volume percentage concentration of the acetone solution is 50%.
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| Application Number | Priority Date | Filing Date | Title |
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| CN2018101773700 | 2018-02-28 | ||
| CN201810177370.0A CN108405487A (en) | 2018-02-28 | 2018-02-28 | A kind of lossless laser cleaning method |
| CN2018101722111 | 2018-03-01 | ||
| CN201810172211.1A CN108325949A (en) | 2018-03-01 | 2018-03-01 | A kind of laser cleaning particulate dirt method |
| CN201810175276.1A CN108580441A (en) | 2018-03-02 | 2018-03-02 | A kind of method of laser cleaning lens |
| CN2018101752761 | 2018-03-02 | ||
| CN2018101796740 | 2018-03-05 | ||
| CN201810179674.0A CN108467664A (en) | 2018-03-05 | 2018-03-05 | A kind of laser cleaning assistant coating formula and coating cleaning |
| CN201810181249.5A CN108538708A (en) | 2018-03-06 | 2018-03-06 | A kind of technique of laser cleaning silicon chip |
| CN2018101812495 | 2018-03-06 | ||
| CN201810182672.7A CN108538709A (en) | 2018-03-06 | 2018-03-06 | A kind of efficient laser cleaning silicon chip technique |
| CN2018101826727 | 2018-03-06 |
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| CN114054420B (en) * | 2021-10-26 | 2023-07-18 | 中国电子科技集团公司第四十七研究所 | Method for removing silicone oil sticky dirt on surface of silicon-based chip |
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| JPH07142440A (en) * | 1993-11-19 | 1995-06-02 | Fujitsu Ltd | Particle removing method and semiconductor production system having particle removing means |
| US8546172B2 (en) * | 2008-01-18 | 2013-10-01 | Miasole | Laser polishing of a back contact of a solar cell |
| CN101219430B (en) * | 2008-01-25 | 2010-06-02 | 清华大学 | Watt level full solid state ultraviolet laser cleaning machine and laser cleaning method |
| DE102008049511A1 (en) * | 2008-09-29 | 2010-04-08 | Giesecke & Devrient Gmbh | Security feature for securing valuables |
| US9779932B2 (en) * | 2015-12-11 | 2017-10-03 | Suss Microtec Photonic Systems Inc. | Sacrificial layer for post-laser debris removal systems |
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