CN107252982B - A kind of method and device laser machining wafer - Google Patents
A kind of method and device laser machining wafer Download PDFInfo
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- CN107252982B CN107252982B CN201710575454.5A CN201710575454A CN107252982B CN 107252982 B CN107252982 B CN 107252982B CN 201710575454 A CN201710575454 A CN 201710575454A CN 107252982 B CN107252982 B CN 107252982B
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K26/00—Working by laser beam, e.g. welding, cutting or boring
- B23K26/36—Removing material
- B23K26/38—Removing material by boring or cutting
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K26/00—Working by laser beam, e.g. welding, cutting or boring
- B23K26/02—Positioning or observing the workpiece, e.g. with respect to the point of impact; Aligning, aiming or focusing the laser beam
- B23K26/06—Shaping the laser beam, e.g. by masks or multi-focusing
- B23K26/064—Shaping the laser beam, e.g. by masks or multi-focusing by means of optical elements, e.g. lenses, mirrors or prisms
- B23K26/0643—Shaping the laser beam, e.g. by masks or multi-focusing by means of optical elements, e.g. lenses, mirrors or prisms comprising mirrors
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K26/00—Working by laser beam, e.g. welding, cutting or boring
- B23K26/02—Positioning or observing the workpiece, e.g. with respect to the point of impact; Aligning, aiming or focusing the laser beam
- B23K26/06—Shaping the laser beam, e.g. by masks or multi-focusing
- B23K26/064—Shaping the laser beam, e.g. by masks or multi-focusing by means of optical elements, e.g. lenses, mirrors or prisms
- B23K26/0648—Shaping the laser beam, e.g. by masks or multi-focusing by means of optical elements, e.g. lenses, mirrors or prisms comprising lenses
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K26/00—Working by laser beam, e.g. welding, cutting or boring
- B23K26/02—Positioning or observing the workpiece, e.g. with respect to the point of impact; Aligning, aiming or focusing the laser beam
- B23K26/06—Shaping the laser beam, e.g. by masks or multi-focusing
- B23K26/067—Dividing the beam into multiple beams, e.g. multifocusing
- B23K26/0676—Dividing the beam into multiple beams, e.g. multifocusing into dependently operating sub-beams, e.g. an array of spots with fixed spatial relationship or for performing simultaneously identical operations
Abstract
The present invention provides a kind of method and device for laser machining wafer, the method forms groove in the wafer upper surface by changing the relative position between the laser beam and wafer upper surface, the method also includes: the laser beam includes laser beamlets, and the laser spot of the laser beamlets is distributed in three dimensions.The laser spot can be formed the hot spot combination of distributed in three dimensions by the present invention by handling in wafer, it realizes the processing that there is three-dimensional level to wafer upper surface and efficiently removes the Low-K layer of wafer upper surface, and then improve working efficiency, accuracy and the uniformity for separating wafer of the processing method.
Description
Technical field
The present invention relates to technical field of semiconductors more particularly to a kind of method and devices for laser machining wafer.
Background technique
In recent years, with the continuous reduction and the continuous improvement of chip integration of feature sizes of semiconductor devices, metal
The resistance of parasitic capacitance and plain conductor between interconnection line, between multilayer wiring increased dramatically, and result in RC retardation ratio, power consumption
A series of problems, such as increase, limits the development of high-velocity electrons component.After device feature size is less than 90nm, wafer is necessary
Traditional SiO is replaced using advanced low-k materials (hereinafter referred to as " Low-K ") material2Layer (K=3.9~4.2), commonly
Low-K material has the FOx of Dow Corning Corporation and the low K film material of carbonado series of porous SiLK material, Applied Materials
Material, the CORAL of Novellus System, the CDO of Intel and the FCN+ organic layer of NEC Corporation etc..
The use of Low-K material also brings some problems.Whether mechanical strength or adhesiveness, Low-K material is all
It is nothing like SiO2, this proposes challenge to scribing process.Most commonly seen problem is, due to lower machine in scribing processes
Tool intensity and adhesion strength, so that Low-K material sticks in saw blade, this not only lowers the efficiency of scribing, while also bringing
Insulating layer is stripped and generates clast from layer on surface of metal and be diffused into other functional areas etc. seriously affect yield after
Fruit.Laser processing has many advantages, such as that non-contact, precision is high, suitable material range is wide, machining path is flexibly controllable, is for crystalline substance
Circle scribing and the robust solution to solve the above problems.It is reported that the wafer that supplier provides has been strictly required in Apple Inc.
Must be using the technique (that is: Laser Grooving technique) of laser cutting Low-K material, this makes Feng Ce factory to such technique
The demand of technology and equipment significantly increases.Strictly speaking, laser beam not instead of " cutting " Low-K material relies on laser energy
The high temperature melt metal layer and interlayer dielectric layer of generation, such laser cutting generate tool stress very little, because without occurring to divide
The problems such as layer or removing.In addition, Hamamatsu Photonics K. K also invented the technology of " stealth cutting ", this technology is to utilize
There is the laser of transmittance wavelength to focus on inside wafer wafer and form modification layer, then makes wafer along modification layer by external force
It splits for individual chip.Using stealthy cutting technique, chip functions area can be made to avoid clast is generated in scribing processes
At pollution, but when being covered with separation layer or other functional layers above wafer, this will will affect the transmission of laser, to influence
Modify the formation of layer.Therefore, when using stealthy cutting, the materials such as upper surface Low-K layers of laser ablation wafer should be also used first
Material.
But when being cut using laser to wafer, since the intensity distribution of laser light source meets Gaussian Profile, i.e.,
Light intensity is most strong in the center energy of hot spot, and hot spot edge energy is then gradually decreased according to the characteristics of Gaussian Profile, therefore is adopted
When with being cut without the Gaussian spot single beam of optical treatment, spot center is easy to produce very strong heat and burns phenomenon,
And then heat-affected zone is larger and damages wafer.
Summary of the invention
A kind of method and device laser machining wafer provided by the invention, can be existed the laser spot by handling
The hot spot combination that distributed in three dimensions is formed in wafer realizes the cutting for have three-dimensional level to wafer upper surface and efficiently by wafer
The Low-K layer of upper surface removes, and then improves the uniform of the working efficiency of the processing method, accuracy and separation wafer
Property.
In a first aspect, the present invention provides a kind of method for laser machining wafer, the method is by changing the laser light
Relative position between beam and wafer upper surface is to form groove in the wafer upper surface, comprising: the laser beam includes
Laser beamlets, the laser spot of the laser beamlets are distributed in three dimensions.
Optionally, the laser beam includes at least two laser beamlets, and the laser of multiple laser beamlet is burnt
Point is distributed in three dimensions.
Optionally, when the relative position between the change laser beam and wafer upper surface so that laser beam is described
When wafer upper surface forms groove, along groove extending direction and in the wafer depth direction perpendicular to the wafer upper surface
On, the laser spot of the multiple laser beamlet is distributed from shallow to deep.
Optionally, the laser spot of the distributed in three dimensions is the focus point for adjusting laser beamlets, makes the laser spot
Gradually deepen on the wafer depth direction perpendicular to the wafer upper surface and forms distributed in three dimensions.
Optionally, on wafer depth direction, the laser spot be distributed from shallow to deep or the laser spot gradually
It is different positioned at the laser beamlets energy where the laser spot of wafer different depth when intensification, and gradually become with the depth
Change.
Optionally, the laser beamlets form the hot spot combination with specific pattern distribution, the hot spot on wafer
Combination includes one or any group in circular light spot, rectangular light spot, square focus spot, elliptical spot or customizable shape polygon
It closes.
Optionally, the laser spot of the distributed in three dimensions includes:
Positioned at the first depth of wafer and the first row laser spot with the first energy is to soften the wafer upper surface；
Positioned at the second depth of wafer and the secondary series laser spot with the second energy is in wafer upper surface shape
At groove；
Positioned at wafer third depth and the third column laser spot with third energy is used to remove the clast in groove.
Optionally, first depth < second depth≤third depth.
Optionally, first energy < third energy < second energy.
Optionally, first energy range is the 25%-35% of second energy；
The third energy range is the 45%-55% of second energy.
Second aspect, the present invention provide a kind of device for laser machining wafer, comprising:
Laser, for emitting laser beam；
Diffraction optical element, for being split processing to laser beam and forming laser beamlets；
Shaping element array, for carrying out Shape correction to laser beamlets；
Focusing element array, for adjusting the focus point of laser beamlets and making the laser spots of the laser beamlets
Distributed in three dimensions；
Controller, for by changing the relative position between the laser beam and wafer upper surface in the wafer
Upper surface forms groove.
Optionally, the focusing element array includes at least two lens elements and the three-dimensional by laser spot in wafer
It is arranged evenly；Wherein,
The lens element is one or any combination in cylindrical focusing lens, plano-convex lens or biconvex lens.
The method and device of laser processing wafer provided in an embodiment of the present invention, solves laser and carries out to wafer upper surface
When fluting, since adhesion strength is smaller between the Low-K material of wafer upper surface and the base substrate of wafer, it be easy to cause Low-K
The problems such as material falls back and chipping.The embodiment of the present invention is mainly by the way that the laser spot to be reasonably distributed, in turn
Improve the uniformity of the working efficiency of the processing method, accuracy and cut groove.
Laser spot described in the embodiment of the present invention forms distributed in three dimensions in wafer, wherein mainly passes through laser
Focus genesis analysis carries out wafer upper surface in the wafer, first with the laser spot in wafer upper surface surface layer
Softening reduces stress to have the function that improve laser absorption rate in grooving process, improves the absorption of laser energy, avoids
Ablation phenomen is easy to produce when directly slotting using high energy laser and heat affected area is higher；Then and position higher using energy
In the laser spot of wafer upper surface middle part, groove is laser machined and formed to wafer upper surface, and then improves processing
Efficiency and yields, and it flexibly is adapted to wafer upper surface.
Detailed description of the invention
Fig. 1 is the flow chart for the method that one embodiment of the invention laser machines wafer；
Fig. 2 is the schematic diagram of another embodiment of the present invention laser spot；
Fig. 3 is the sectional view of A-A in one embodiment of the invention Fig. 2；
Fig. 4 is the sectional view of A-A in another embodiment of the present invention Fig. 2；
Fig. 5 is the schematic diagram of another embodiment of the present invention laser spot；
Fig. 6 is the structural schematic diagram for the device that one embodiment of the invention laser machines wafer；
Wherein, 1, laser spot, 2, wafer upper surface, 3, substrate, 4, beam-expanding collimation element, 5, reflecting mirror.
Specific embodiment
In order to make the object, technical scheme and advantages of the embodiment of the invention clearer, below in conjunction with the embodiment of the present invention
In attached drawing, technical scheme in the embodiment of the invention is clearly and completely described, it is clear that described embodiment is only
It is only a part of the embodiment of the present invention, instead of all the embodiments.Based on the embodiments of the present invention, ordinary skill
Personnel's every other embodiment obtained without making creative work, shall fall within the protection scope of the present invention.
The embodiment of the present invention provides a kind of method for laser machining wafer, as shown in Figure 1, the method passes through described in change
Relative position between laser beam and wafer upper surface is to form groove in the wafer upper surface, comprising: the laser light
Beam includes laser beamlets, and the laser spot of the laser beamlets is distributed in three dimensions.
The method of laser processing wafer provided in an embodiment of the present invention solves laser and slots to wafer upper surface 2
When, since adhesion strength is smaller between the Low-K layer and the base substrate of wafer of wafer upper surface 2, it be easy to cause Low-K layers to take off
It falls and the problems such as chipping.It for upper surface include Low-K layers of wafer in the present embodiment, by by the laser spot 1
It is reasonably distributed, reaches the Low-K layer effect of efficiently removal wafer upper surface, and then improve the work of the processing method
Efficiency, accuracy and the uniformity for separating wafer.
Wafer described in the present embodiment includes substrate 3 and the wafer upper surface 2 that the top of substrate 3 is arranged in, on the wafer
Low-K layers are covered in surface.The laser spot 1 is distributed in three dimensions in wafer, is mainly three-dimensional point in wafer upper surface 2
Cloth, wherein mainly through 1 genesis analysis of laser spot in the wafer, first in 2 surface layer of wafer upper surface
Laser spot 1 softens wafer upper surface 2 to reduce the generation of clast, and stress is reduced in grooving process, improves and swashs
The absorption of light energy is avoided and is easy to produce ablation phenomen when directly being slotted using high energy laser and heat-affected zone is high asks
Topic；Then laser spot 1 that is higher using energy and being located at 2 middle part of wafer upper surface, laser machines wafer upper surface 2
And form groove.
In conclusion wafer upper surface 2 is cut using the laser spot 1 with distributed in three dimensions in the present embodiment,
While improving the method working efficiency, accuracy and separating the uniformity of wafer, additionally it is possible to swash by adjusting described
The Energy distribution of the hot spot combination and laser beamlets with setting pattern that photon light beam is formed in crystal column surface, so that swashing
Optical focus 1 can be suitable for wafer upper surface 2 more flexiblely.
Optionally, the present embodiment the method may also include the steps of:
S11, processing is split to laser beam by diffraction optical element and forms laser beamlets；
S12, processing is focused by focusing element array, so that the laser spot of the laser beamlets is three-dimensional point
Cloth；
S13, change the relative position between the laser beam and wafer upper surface to be formed in the wafer upper surface
Groove.
Optionally, as shown in Figure 2-5, the laser beam includes at least two laser beamlets, and multiple laser is sub
The laser spot of light beam is distributed in three dimensions.
Optionally, when the relative position between the change laser beam and wafer upper surface so that laser beam is described
When wafer upper surface forms groove, along groove extending direction and in the wafer depth direction perpendicular to the wafer upper surface
On, the laser spot of the multiple laser beamlet is distributed from shallow to deep.
Specifically, prolonging in the present embodiment along the direction for changing the relative position between the laser beam and wafer upper surface
The laser spot 1 stretched is the column of laser spot；The laser extended on the wafer depth direction perpendicular to the wafer upper surface 2
Focus 1 is the row of laser spot, and then the laser spot array of distributed in three dimensions is formed in wafer, meanwhile, the laser spot
Place laser beamlets can also form the hot spot combination with setting pattern on wafer, for example, the laser of 1*N circular light spot is burnt
Laser spot array, the M* that laser spot array, the M*N square focus spot of more kinds of geometry hot spots of lattice array, 1*N combination combine
The laser spot array of more kinds of geometry hot spots of N combination.Mainly the upward laser spot 1 of row is divided from shallow to deep in the present embodiment
Cloth, and distributed in three dimensions spatially is formed with the upward laser spot 1 of column, and then improve the cutting effect of the laser spot 1.
For example, as shown in Fig. 2, when the laser spot array be 3*3 square focus spot laser spot array when, such as Fig. 3
Shown, the wafer includes substrate 3 and the wafer upper surface 2 above substrate 3, wherein the wafer upper surface 2 has setting
Depth and surface layer, middle part and lower part can be divided into from shallow to deep on 2 set depth of wafer upper surface；First row in the present embodiment
Laser spot 1 is on 2 surface layer of wafer upper surface, to heat and soften upper surface；Second row laser spot 1 is in wafer upper surface 2
Portion processes wafer upper surface 2 and forms groove；Third column laser spot 1 removes groove in the lower part of wafer upper surface 2
Interior clast, and then the clast of Low-K material is avoided to adhere in a groove, influence the effect of wafer；Alternatively, as shown in figure 4,
The laser spots of three column and the laser spot of secondary series are in same depth, while at the middle part of the wafer upper surface 2；Or
Person, as shown in figure 5, the depth of tertial laser spot is in the depth of the laser spot of first row and the laser spot of secondary series
Depth between.
Meanwhile method described in the present embodiment also uses shaping element array that laser beamlets are carried out shaping, makes laser
Beamlet forms the hot spot combination with specific pattern distribution in crystal column surface；For example, first row laser spot 1 in the present embodiment
The laser beamlets at place form three square focus spots on the wafer surface, and on 2 surface layer of wafer upper surface, to heat and soften
Upper surface；Laser beamlets where second row laser spot 1 form three square focus spots on the wafer surface, and on wafer
2 middle part of surface processes wafer upper surface 2 and forms groove；Laser beamlets where third column laser spot 1 are in crystalline substance
Three square focus spots formed on circular surfaces, and the clast in groove is removed in the lower part of wafer upper surface 2, and then avoid Low-
The clast attachment of K material in a groove, influences the effect of wafer；Alternatively, as shown in figure 4, tertial laser spot and second
The laser spot of column is in same depth, while at the middle part of the wafer upper surface 2；Alternatively, as shown in figure 5, tertial
The depth of laser spot is between the depth of the laser spot of first row and the depth of the laser spot of secondary series.In the present embodiment
The method is the rectangular shaping element array of 3*3 customized using shaping element array, and cooperates convex lens that 3*3 may be implemented
The rectangular flat-top hot spot processing effect of array.Rectangular flat-top hot spot can effectively control edge definition, therefore and circular light
Spot compares, and can obtain significantly more efficient machining accuracy, and is not damaged to wafer effective coverage.It rectangular edge can also be more preferable
Control heat affected area diffusion, by processing groove control within predetermined cuts road.Rectangular array processing effect can be more preferable
The large-scale machining area of covering, i.e., increase processing efficiency.It noenergy region among different rectangular sub-light spots also can one
The influence of fixed alleviation fuel factor.
Optionally, the laser spot 1 of the distributed in three dimensions is the focus point for adjusting laser beamlets, makes the laser spot
1 gradually deepens on the wafer depth direction perpendicular to the wafer upper surface 2 and forms distributed in three dimensions.
Specifically, making the motion track institute of the laser spot 1 in the present embodiment by adjusting the focus point of the laser
The plane at place is located on plane locating for 2 surface layer of wafer upper surface or puts down with locating for 2 surface layer of wafer upper surface
Face is overlapped；
The laser is with 2 surface layer of wafer upper surface described in the first energy exposure, to soften 2 surface layer of wafer upper surface；
The focus point for adjusting the laser makes on plane locating for the motion track of the laser spot 1 and the wafer
Plane locating for 2 middle part of surface is overlapped；
The laser is recessed to be formed in the wafer upper surface 2 with 2 middle part of wafer upper surface described in the second energy exposure
Slot.
And then laser beam is in process, so that the focus of laser changes from shallow to deep, makes in change procedure
Laser spot 1 forms distributed in three dimensions, and then improves processing efficiency, effectively avoids the diffusion of heat affected area.
Optionally, on wafer depth direction, the laser spot 1 be distributed from shallow to deep or the laser spot 1 by
When gradually deepening, the laser beamlets energy where the laser spot 1 positioned at wafer different depth is different, and gradually with the depth
Variation.
Optionally, the laser beamlets form the hot spot combination with specific pattern distribution on the wafer surface, described
Hot spot combination includes a kind of in circular light spot, rectangular light spot, square focus spot, elliptical spot or customizable shape polygon or appoints
Meaning combination.
Specifically, hot spot combination is matched to best setting figure according to the feature of groove by the combination of hot spot described in the present embodiment
Case distribution, the uniformity of the Laser beam energy distribution by guaranteeing scribing, so that more equal in the groove that wafer upper surface 2 is formed
Even, heat affected area is smaller and homogeneity is higher, and then improves the processing effect in wafer upper surface 2.
Therefore, hot spot described in the present embodiment combination mainly according to the groove of the formation needed for the wafer upper surface 2, with
And effect determines the hot spot of specific setting pattern distribution, then according to setting pattern distribution, is split processing to laser beam
Multiple laser beamlet is formed afterwards, Shape correction, focus processing, Jin Er are then carried out respectively to the laser beamlets after beam splitting
Crystal column surface forms the hot spot combination with setting pattern distribution, has the laser sub-light of hot spot combination finally by adjustment
The spatial position that beam corresponds to laser spot 1, which is realized, to carry out processing to wafer upper surface 2 and forms groove in wafer upper surface 2, into
And under the premise of avoiding Low-K layers of peeling in process, the flatness of the groove is improved, and then improve the property of wafer
Energy.
For example, circular light spot can be used and softened due to not high to the flatness requirement of groove in softening process；
Since the flatness requirement in grooving process for bottom portion of groove, two sides is high, the uniform rectangular light spot of Energy distribution is used
It slots；Debris removal is carried out since elliptical spot since the distribution of clast is big, can be used during debris removal；So that
Groove is more flat, and heat affected area is smaller and homogeneity is high, effectively prevents the appearance of chipping, micropore and burr phenomenon.
Optionally, the laser spot of the distributed in three dimensions includes:
Positioned at the first depth of wafer and the first row laser spot 1 with the first energy is to soften the wafer upper surface
2；
Positioned at the second depth of wafer and the secondary series laser spot 1 with the second energy is in the wafer upper surface 2
Form groove；
Positioned at wafer third depth and the third column laser spot 1 with third energy is used to remove the clast in groove.
Optionally, first depth < second depth≤third depth.
Optionally, first energy < third energy < second energy.
Optionally, first energy range is the 25%-35% of second energy；
The third energy range is the 45%-55% of second energy.
Preferably, first energy range is the 30%-34% of second energy；
The third energy range is the 50% of second energy；
It is furthermore preferred that first energy is the 33% of second energy.
Alternatively, swashing where the laser spot 1 in the present embodiment when perpendicular to the visual angle of the wafer upper surface 2
Photon light beam has the hot spot combination for setting topological pattern in crystal column surface, for example, strip, H-shaped, sphere of movements for the elephants shape.
Wherein, as shown in figure 5, for when perpendicular to the visual angle of the wafer upper surface 2, the topology pattern is H-shaped
When, shaping element array used is the rectangular shaping element array of " H " type customized, and cooperates convex lens that " H " type may be implemented
The rectangular flat-top hot spot processing effect of array.The nanosecond laser as used in device generates biggish heat affecting effect to Low-K layers,
The fuel factor that may cause material reduces machining accuracy, and the diffusion of heat affected area is also possible to the effective of damage wafer
Region, to reduce product qualification rate.Therefore, the combination of " H " type array hot spot is beamed by what laser beam customized.So that pre-
The processing fuel factor at Cutting Road edge is determined more to diffusion among processing groove, that is, remains processing efficiency, and effective control
Damage of product situation.Also, the processing effect of a branch of sub-light spot is remained in the intermediate region of Cutting Road, it can be to centre one
Certain processing effects such as partial region realization.It is remaining it is therefore possible to greatly reduce in subsequent blade dividing processing
The Low-K layers of resistance to blade, and the groove for being located at the laser processing in bosom can effectively hold onto the movement rail of blade
Mark, to improve blade running precision.
The embodiment of the present invention also provides a kind of device for laser machining wafer, as shown in fig. 6, described device includes:
Laser, for emitting laser beam；
Diffraction optical element, for being split processing to laser beam and forming laser beamlets；
Shaping element array, for carrying out Shape correction to laser beamlets；
Focusing element array, for adjusting the focus point of laser beamlets and making the laser spots of the laser beamlets
Distributed in three dimensions；
Controller, for by changing the relative position between the laser beam and wafer upper surface in the wafer
Upper surface forms groove.
The device of laser processing wafer provided in an embodiment of the present invention by diffraction optical element, shaping element array and gathers
Laser spot 1 is processed as distributed in three dimensions by burnt element arrays, wherein mainly by 1 genesis analysis of laser spot in the crystalline substance
In circle, wafer upper surface 2 is softened first with the laser spot 1 in 2 surface layer of wafer upper surface to reach to improve and swash
The effect of absorptivity, and stress is reduced in grooving process, the absorption of laser energy is improved, is avoided using high energy laser
It is easy to produce ablation phenomen when directly slotting and heat-affected zone is high；Then it utilizes energy higher and is located in wafer upper surface 2
The laser spot 1 in portion, while also wafer upper surface 2 is laser machined and is formed recessed by controller control described device
Slot.
In conclusion in the present embodiment using with distributed in three dimensions hot spot combination laser spot 1 to wafer upper surface 2 into
Row cutting not only improves the method working efficiency, accuracy and the uniformity for separating wafer, also enables laser spot 1
It is enough to be suitable for wafer upper surface 2 more flexiblely.
Also, the focusing element array includes at least two lens elements and divides by three-dimensional of the laser spot in wafer
Cloth arrangement；Wherein,
The lens element is one or any combination in cylindrical focusing lens, plano-convex lens or biconvex lens.
Described device further include:
Beam-expanding collimation element 5, laser beam expanding, collimation for emitting the laser, forms source of parallel light；
Reflecting mirror 6 makes the source of parallel light inject the diffraction optical element for changing the source of parallel light direction.
Described device further includes the Gripping platform for clamping wafer and the space bit for adjusting the laser spot 1
The mobile platform set.
Wherein, diffraction beam splitter described in the present embodiment mostly uses two-value phase grating to be divided into light beam any number of more
Light beam, wherein traditional Dammann grating is having based on scalar diffraction theory design as typical two-value phase grating
The two-value phase grating of special aperture function.Its Fraunhofer diffraction pattern sample generated to incident light wave is certain amount dot matrix
Isocandela hot spot.Completely avoid general amplitude grating diffraction pattern luminous intensity due to caused by sinc function intensity envelope not
It is uniformly distributed.Even if however when removing the Low-K layer still retained after the Low-K layer for removing edge, due to from Low-K layers
It is applied to the physical resistance of blade, it is impossible to ensure the predetermined movement speed of blade.Therefore, in the present embodiment, diffraction point is used
Laser beam beam splitting is become the multiple laser beamlet of different light intensity by optical element.Therefore it can guarantee predetermined cuts road edge
In the case where Low-K layers of removal, the effect for being equal to edge processing is realized to intermediate a part of region.It is therefore possible to subsequent
Blade slot treatment in greatly reduce the Low-K layers of resistance to blade of residue, and positioned at bosom 0 grade of diffraction photoetching
The channel of erosion can effectively hold onto the motion profile of blade, to improve blade running precision.And multi beam parallel laser
Light beam may be implemented by customizing shaping element to single being customized of laser beamlets plastics design.Wherein, the shaping
Element is the array of diffraction elements according to laser beamlets Array Design.Finally, fraction of laser light beamlet passes through according to lasertron
The focusing element array of beam array design, focuses on the position in Low-K layer surface predetermined cuts road in different forms respectively.
Mainly by forming the laser spot of distributed in three dimensions in wafer upper surface 2 in the present embodiment, implementation levelization cutting be can be improved
The homogeneity of fuel factor improves product conjunction so as to avoid fuel factor in laser processing to the damage in wafer effective coverage
Lattice rate.
The device of the present embodiment can be used for executing the technical solution of above method embodiment, realization principle and technology
Effect is similar, and details are not described herein again.
The above description is merely a specific embodiment, but scope of protection of the present invention is not limited thereto, any
In the technical scope disclosed by the present invention, any changes or substitutions that can be easily thought of by those familiar with the art, all answers
It is included within the scope of the present invention.Therefore, protection scope of the present invention should be subject to the protection scope in claims.
Claims (11)
1. a kind of method for laser machining wafer, the method is by changing the phase between the laser beam and wafer upper surface
To position to form groove in the wafer upper surface characterized by comprising the laser beam includes at least two laser
Beamlet, and the laser spot of multiple laser beamlet forms distributed in three dimensions.
2. the method according to claim 1, wherein when changing between the laser beam and wafer upper surface
Relative position so that laser beam the wafer upper surface formed groove when, along groove extending direction and perpendicular to described
On the wafer depth direction of wafer upper surface, the laser spot of the multiple laser beamlet is distributed from shallow to deep.
3. method according to claim 1 or 2, which is characterized in that the laser spot of the distributed in three dimensions is adjustment laser
The focus point of beamlet deepens the laser spot gradually simultaneously on the wafer depth direction perpendicular to the wafer upper surface
Form distributed in three dimensions.
4. according to the method described in claim 2, it is characterized in that, the laser spot is by shallow on wafer depth direction
When gradually deepening to deep distribution or the laser spot, positioned at the laser beamlets energy where the laser spot of wafer different depth
Amount is different, and gradually changes with the depth.
5. according to the method described in claim 4, it is characterized in that, the laser beamlets are formed on wafer has specific pattern
The hot spot combination of case distribution, the hot spot combination is including a kind of in circular light spot, rectangular light spot, square focus spot, elliptical spot
Or any combination.
6. according to the method described in claim 5, it is characterized in that, the laser spot of the distributed in three dimensions includes:
Positioned at the first depth of wafer and the first row laser spot with the first energy is to soften the wafer upper surface；
Positioned at the second depth of wafer and the secondary series laser spot with the second energy is recessed to be formed in the wafer upper surface
Slot；
Positioned at wafer third depth and the third column laser spot with third energy is used to remove the clast in groove.
7. according to the method described in claim 6, it is characterized in that, first depth < second depth≤third
Depth.
8. method according to claim 6 or 7, which is characterized in that first energy < third energy < the second energy.
9. according to the method described in claim 6, it is characterized in that, first energy range is second energy
25%-35%；
The third energy range is the 45%-55% of second energy.
10. a kind of device for laser machining wafer characterized by comprising
Laser, for emitting laser beam；
Diffraction optical element, for being split processing to laser beam and forming laser beamlets；
Shaping element array, for carrying out Shape correction to laser beamlets；
Focusing element array, for adjusting the focus point of laser beamlets and keeping the laser spot of the laser beamlets three-dimensional
Distribution；Wherein, the laser beam includes at least two laser beamlets, and the laser spot of multiple laser beamlet is formed
Distributed in three dimensions；
Controller, for by changing the relative position between the laser beam and wafer upper surface with the table on the wafer
Face forms groove.
11. device according to claim 10, which is characterized in that the focusing element array includes at least two lens cells
Part is simultaneously arranged by distributed in three dimensions of the laser spot in wafer；Wherein,
The lens element is one or any combination in cylindrical focusing lens, plano-convex lens or biconvex lens.
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| CN108515273B (en) * | 2018-03-29 | 2020-10-13 | 大族激光科技产业集团股份有限公司 | Cutting device and cutting method for LED wafer |
| CN109396660A (en) * | 2018-09-25 | 2019-03-01 | 力成科技（苏州）有限公司 | Multiple light courcess laser slotting technique |
| CN113369677B (en) * | 2021-05-31 | 2022-05-31 | 深圳赛意法微电子有限公司 | Wafer cutting method and cutting equipment |
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| JP4750427B2 (en) * | 2005-01-13 | 2011-08-17 | 株式会社ディスコ | Wafer laser processing method |
| JP4648044B2 (en) * | 2005-03-15 | 2011-03-09 | 株式会社ディスコ | Laser processing equipment |
| CN101138807A (en) * | 2007-10-16 | 2008-03-12 | 友达光电股份有限公司 | Cutting equipment and cutting manufacturing technology |
| GB2512291B (en) * | 2013-03-22 | 2015-02-11 | M Solv Ltd | Apparatus and methods for forming plural groups of laser beams |
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Effective date of registration: 20190604 Address after: 100176 Beijing Daxing District Beijing Economic and Technological Development Zone Patentee after: Beijing Zhongke Radium Electronics Co., Ltd. Address before: No. 3, North Tu Cheng West Road, Chaoyang District, Beijing Patentee before: Institute of Microelectronics, Chinese Academy of Sciences |