A kind of laser cutting deviceTechnical field
The invention belongs to semiconductor material or high hard high crisp material laser cutting technique fields, are related to a kind of high-precision sharpLight cutter device is particularly suitable for the material transparent to applied optical maser wavelength, and workpiece is thicker, and requires without heat affected area, nothingThe laser score of chipping, especially requires straightness high, and to the thermo-responsive crisp material of height, there are many various sizes of on waferChip, the directly wafer cutting of spread sheet after needing laser internal to cut.
Background technique
With the progress and development of science and technology, laser has been used as a kind of tool application in all trades and professions.Due to laserHigh brightness high intensity characteristic, and the size of laser facula can focus on micron dimension by focus lamp, therefore laser addsWork technology in the industry for having high-precision processing request by favor, especially for ceramics, monocrystalline silicon and sapphire it is contour,Firmly, in crisp unmanageable cutting technique, laser processing technology is especially welcome.
By taking semicon industry as an example, the slice process of wafer is the first step in rear road assembly technology.The technique is by waferIt is divided into single chip, for subsequent chip bonding, wire bonding and test technology.When chip size is smaller and smaller, integrateHigher and higher, traditional mechanical microtomy production capacity decline is spent, fragment rate rises, and the rejection rate of generation increases.In such caseUnder, laser cutting technique is able to show advantage.Since laser belongs to non-contact type processing, the work of mechanical stress is not generated to waferWith, to wafer damage it is smaller.Therefore laser wafer microtomy obtains development energetically.
Although this technology of laser largely alleviates drawbacks described above, however in laser technology in use, it is hotThe problem of zone of influence is excessive and slag splash is polluted is not properly settled yet, these disadvantages are enough to influence or destroy the performance of chip,Especially transparent material, it is particularly evident to slag pollution problem.After especially carrying out conventional laser processing to high hard high crisp material,Sliver chipping problem is particularly evident.The line light spot laser inscribe either used on the market still puts the cutting of hot spot multilayer,During sliver, if ablation energy is excessive, cutting straight line degree and surface chipping numerical value can be very big, directly affect chip matterAmount；If ablation energy is too small, sliver technique can become complicated, will use dedicated equipment, even if can not protect in this wayHigher straightness and chipping index are demonstrate,proved, in particular for the chip on a wafer there are many size, traditional handicraft will pass throughMultiple pour mask sliver is just able to achieve wafer spread sheet, has not only guaranteed cut quality required precision using the method, but also can be convenient quickSpread sheet.
Summary of the invention
In order to solve the base material transparent for optical maser wavelength, the heat that occurs in conventional laser cutting dicing techniqueThe problems such as the problem of zone of influence is excessive and slag splash is polluted, chipping problem when sliver, straightness difference problem, spread sheet difficulty is big,The present invention proposes a kind of laser cutting device.
The purpose of the present invention is achieved through the following technical solutions: the present invention provides a kind of laser cutting device, including swashsLight device, for issuing laser beam；Precision laser cutting head, the Laser beam propagation that the laser issues to laser accurateIn cutting head, multilayer laser cutting is carried out with for workpiece；Focus lamp is mounted in the precision laser cutting head；Diffraction lightLens module is learned, the laser beam is formed by the diffraction optical lens module and the condenser lens in inside workpieceFocus is cut, wherein the initial position of the cutting focus of later layer and preceding layer cut the initial position of focus in vertical directionIt is not overlapped.
In laser cutting device of the invention, the laser beam passes through the diffraction optical lens module and focus lampAfterwards, focus is formed in the workpiece.
In laser cutting device of the invention, the starting point of the cutting focus of the second layer is located at the cutting focus starting of first layerBetween point and next cutting focus, the starting point of the cutting focus of third layer is located at the cutting focus starting point and second of first layerBetween the cutting focus starting point of layer.The starting point of 4th layer of cutting focus be located at first layer cutting focus starting point itBefore.Next cutting focus of the starting point of 4th layer of cutting focus be located at the next point of the cutting focus starting point of first layer withThe second layer is cut between the starting point of focus.
In laser cutting device of the invention, the starting point of the hot spot of each layer of the cutting focus is according to Cutting Road positionThe difference set and set.
In laser cutting device of the invention, according to the frequency of the laser, the workpiece horizontal motion is adjustedSpeed, to make on the same face adjacent spots that there is certain spacing.
In laser cutting device of the invention, the diffraction optical lens module can be microarray lens or adaptiveEyeglass.
In laser cutting device of the invention, the diffraction optical lens module is made of multiple diffraction optical lens.
In laser cutting device of the invention, the multilayer laser cutting is primary formation or is successively formed.
Laser cutting device influence area of the invention is small, the laser cutting device of no slag splash pollution, high yield rate,Production efficiency greatly improves compared with the prior art.Cutting Road is formed in inside workpiece.According to the difference of material thickness, Cutting RoadQuantity can increase with the increase of thickness.
Detailed description of the invention
Fig. 1 is laser cutting device schematic diagram of the invention；
Fig. 2 is the laser action movement rail of inside workpiece formation after the completion of laser cutting device multilayer cutting of the inventionMark schematic diagram；
4 laser spots are formed by diffraction lens module when Fig. 3 is laser cutting device multilayer cutting of the inventionDistribution and machining sketch chart；
Fig. 4 is successively cutting, the machining sketch chart of every layer of laser spot difference starting point；
The meaning respectively marked in figure is as follows:
1: laser；
2: optical path；
3:45 degree reflecting mirror；
4: diffraction lens module, 4a, 4b, 4c and 4d are respectively different diffraction eyeglasses；
5: precise laser cutting head；
6: focus lamp；
7: workpiece；
8: focus point；
9:CCD camera；
10: laser beam；
M: the movement of workpiece；
D: the horizontal distance between focus point；
D1, d2, d3: being respectively the horizontal distance that diffraction eyeglass forms four focuses
Specific embodiment
The present invention will be described in detail with reference to the accompanying drawing:
Fig. 1 shows laser cutting device schematic diagrames of the present invention, and form as follows: optical path 2 issues laser 1Laser beam 10 changes direction into 45 degree of reflecting mirrors 3 are crossed, will be in 10 guided laser accurate cutting head 5 of laser beam；Pass through diffraction lightLaser beam 10 after learning lens module 4 and focus lamp 6 forms one group of focus point 8 in the inside of workpiece 7, i.e. cutting focus；WhenWhen workpiece 7 moves M relative to laser beam 10, laser acts on simultaneously in inside；By adjusting the speed and laser frequency of movement MRate, which carries out matching, makes focus point have certain spot separation, when needing different the cutting number of plies or cutting to be spaced, can pass throughThe corresponding diffraction eyeglass of diffraction lens module 4 is selected to realize.Wherein, fortune of the laser focus point between different layers in workpiece 7The vertical direction of dynamic M is not overlapped.By taking the focus point of the initial position for the laser beam 10 that workpiece 7 is cut as an example, later layer is cutThe initial position for cutting focus is not overlapped in vertical direction with the initial position of preceding layer cutting focus, and CCD camera 9 is used for workCutting position on part carries out identification positioning.
Diffraction lens module 4 of the invention can be the diffraction eyeglass of simple function, be also possible to more specification diffraction eyeglasses4a, 4b, 4c and 4d composition, each diffraction eyeglass can independently constitute a kind of focusings and cut focus, to adapt to different focusingCutting requirement reduces component number, improves the efficiency of part replacement.The laser beam that laser issues passes through diffractionAfter optical mirror slip module and focus lamp, the focus of one or more different heights is formed in inside workpiece, it is different by selectingDiffraction optical lens, thus corresponding different focus position and focus point energy.
Fig. 2 is the schematic diagram that laser action is formed by focus point in workpiece, is listed in figure a kind of with certain thickFocus distribution schematic diagram is cut in inside when the cutting of the material of degree, for forming 4 layers of cutting, needs to cut in inside workpieceForm 4 layers of Cutting Road, in the present embodiment, the cutting focus spacing in each Cutting Road is adjacent in horizontal direction for 8 micronsThe distance between focus point D is determined by the speed and laser frequency of relative motion.
Fig. 3 another embodiment of the present invention, shows in cutting process, and workpiece 7 moves, and laser pulse issues to form cuttingThe process in road.Diffraction lens module 4 as shown in the figure is formed for four cutting focuses, when topmost one (the 4th) of settingStarting point is relative zero, then first of starting point d1 is positive 2 microns, second starting point d3 is positive 6 microns, and third road starting point d2 isPositive 4 microns.The positional relationship of this 4 hot spots can be realized by the shaping of diffraction eyeglass, can also be cut from level to level, definitionThe position coordinates of first cut point are realized.
In laser cutting device of the invention, after workpiece 7 places, CCD camera 9 carries out the cutting position on workpiece 7After automatic identification positioning, issuing signal makes laser 1 go out light；The laser beam 10 that laser 1 issues passes through diffraction optical lensAfter module 4 and focus lamp 6, focus point 8 is formed in workpiece 7；7 relative laser light beam 10 of workpiece carries out horizontal motion M, phaseHorizontal distance D between adjacent focus point is determined by horizontal motion speed and laser frequency, after the completion of moving M, in workpieceInterior and intermediate formation multilayer Cutting Road burst point；It is separate since the laser energy only at focus point 8 is just enough to destroy workpiece materialThe position of focus point 8 not will receive the destruction of laser.Since each layer in cutting process of burst point is not at upper one layerBurst point upright position takes in the middle position of upper one of burst point 1 and burst point 2, there is some advantages in this way: 1, between different layersNot in the same vertical direction, the thermal stress of such moment will not be superimposed excessively burst point, lead to chipping.2, quick-fried between different layersPoint fall in this in process layer burst point will not in the micro-crack of one layer of burst point, make burst point not in the same vertical directionLose due effect.3, the burst point between different layers can increase the cutting number of plies not in the same vertical direction, increase burst pointQuantity directlys adopt spread sheet machine and realizes a sliver.
As shown in Figure 1, focus point 8 of the invention is customization hot spot, when focus point 8 is acted on workpiece 7, focus point 8Thus hot spot range, which is respectively formed 4 height focus points different with horizontal position, causes workpiece to be easier sliver.Improve productSliver effect.
In laser cutting device of the invention, have to the starting point of Cutting Road required.It is successively cut if it is single hot spot,Such as Fig. 4, it is desirable that the starting point hot spot of second 8b is fallen between two focus points of first Cutting Road 8a, third road 8c starting point lightSpot falls in the centre of first of starting point and second starting point, and the starting point of the 4th 8d falls in a quarter spacing before first of starting pointPosition (second point for being equivalent to the 4th falls in third road).The position of starting point mentioned here refers to machining starting point X-axis sideTo position, and z, to position, the height of each Cutting Road is set according to by cutting material thickness.
It should be noted that either once forming multilayer cutting or successively forming multilayer cutting, different height and waterThe cutting focus that prosposition is set is located in same vertical plane, i.e. same group of all score roads of the workpiece M direction of motion are respectively positioned onIn same vertical plane.And the position of cutting focus in this application is for example, all cuttings in actual processingCutting focus in road is continuously, to meet the cutting focal position relationship of the application i.e. with opposite one group of cutting focusIt can.
In laser cutting device of the invention, the selection of laser 1 is related with the material of workpiece 7, it is desirable that selected laser 1Wavelength workpiece 7 is transmissive to, can make laser beam 10 penetrate workpiece 7, also form focus point in the surface of workpiece.LaserThe wave-length coverage of device is in 200nm to 2000nm, and pulse duration range is in 10fs to 200ns.Have to the energy of laser required, it is desirable thatThe focal point that inside is formed, the energy density of laser beam can destroy workpiece material just, form internal explosion.
In laser cutting device of the invention, the position of focus point and energy correspond to different diffraction optical lens and gatherJiao Jing.According to the thickness of practical work piece, different diffraction optical lens and focus lamp are selected, are located at multiple focuses in workpiecePortion.After the laser beam that laser issues is by diffraction optical lens and focus lamp, one or more is formed not in inside workpieceLevel focus, platform movement drive wafer, laser are made to form one or more Cutting Road in material internal, this Cutting Road isIt is formed by many evenly spaced laser burst points.
Embodiment of above is only technical solution to illustrate the invention and illustrating for doing, and is not used to limit this hairBright specific protection scope, the present invention may be 35 or more multiple tracks, and emphasis of the invention is the Cutting Road of eachBurst point not on same vertical line, in this way can be excessive to avoid ablation energy, the overlapping of burst point stress cracking leads to surfaceThe problems such as back side chipping.The present invention can also improve the area that laser inscribe forms burst point, more while guaranteeing cut qualityBe conducive to wafer spread sheet.
Diffraction optical lens in the above embodiment of the present invention are also possible to microarray lens, or are also possible to adaptiveEyeglass or other structures known in the art for realizing phase same-action.
It is emphasized that this laser cutting device does not do limitation in any form, it is all according to the present inventionThe simple modification that technical spirit carries out, equivalent variations and modification, all of which are still within the scope of the technical scheme of the invention.