Specific embodiment
Hereinafter, being said referring to attached drawing to laser processing device used in the processing method in the chip of present embodimentIt is bright.Fig. 1 is the perspective view of the laser processing device of present embodiment.Fig. 2 is the block diagram of laser beam producing unit.As long as in addition,Laser processing device is the structure that chip can be processed from the hexagonal crystal single crystal rod of present embodiment, is not limited toStructure shown in FIG. 1.
As shown in Figure 1, laser processing device 1 is configured to make the laser processing unit for irradiating laser beam and remains ingot 60The holding workbench 21 of (referring to Fig. 3) is relatively moved and is laser machined to ingot 60.
It is provided with movable workbench unit 11 on the base station 10 of laser processing device 1, which makesWorkbench 21 is kept to move in X-direction and Y direction relative to laser processing unit.Movable workbench unit 11 includesA pair of guide rails 12, they are configured on base station 10, parallel with X-direction；And the X-axis workbench 14 of motor drive, withThe mode that can be slided is arranged in a pair of guide rails 12.Also, movable workbench unit 11 includes a pair of guide rails 13, they matchIt sets on the upper surface of X-axis workbench 14, it is parallel with Y direction；And the Y-axis workbench 15 of motor drive, with canThe mode of sliding is arranged in a pair of guide rails 13.
Nut portions (not shown) are respectively formed in the back side of X-axis workbench 14 and Y-axis workbench 15, these nut portionsIt is screwed togather with ball-screw 16,17.Also, by make with the one end of ball-screw 16,17 link drive motor 18,19 intoRow rotation driving, keeps workbench 21 to move in X-direction and Y direction along guide rail 12,13.Also, in Y-axis workbenchThe holding workbench 21 kept to ingot 60 is provided on 15.Retaining surface is formed on the upper surface for keeping workbench 2122。
On base station 10, is erect at the rear for keeping workbench 21 and be provided with standing wall portion 25, installed in the standing wall portion 25There are laser beam irradiation means (laser beam irradiation unit) 30.Laser beam irradiation means 30 include: laser beam shown in Fig. 2 generates singleMember 34, is accommodated in shell 32；And condenser (laser head) 36, it is mounted on the front end of shell 32.Before shell 32End is equipped with shooting unit 38, which arranges along the x axis with condenser 36, has microscope and camera.
As shown in Fig. 2, laser beam producing unit 34 include vibrate YAG laser out or YVO4 laser laser oscillator 40,Repetition rate setup unit 42, pulse width adjustment unit 44 and power adjustment unit 46.Although being not particularly illustrated, laserOscillator 40 has Brewster window, and the laser beam projected from laser oscillator 40 is the laser beam of linear polarization.
The pulse laser beam of defined power is adjusted to by optically focused by the power adjustment unit 46 of laser beam producing unit 34The reflecting mirror 48 of device 36 reflects, and focal point is then located in by collector lens 50 the conduct quilt for being fixed on and keeping workbench 21The inside of the ingot 60 of machining object and irradiate.
Fig. 1 is returned to, the left side in Fig. 1 of base station 10 is provided with column 52, by being formed in the opening 53 of the column 52 with energyThe mode enough gone up and down is equipped with pressing mechanism 54.
Then, the hexagonal crystal single crystal rod 60 as workpiece is illustrated referring to Fig. 3.(A) of Fig. 3 is hexagonal crystalThe perspective view of single crystal rod, (B) of Fig. 3 are the main views of the hexagonal crystal single crystal rod of Fig. 3 (A).Hexagonal crystal single crystal rod is (hereinafter referred to asFor ingot) it 60 is made of SiC, GaN, lithium tantalate, lithium niobate, sapphire etc..
Ingot 60 has the first face (upper surface) 61a and the second face (back side) positioned at the side opposite with the first face 61a61b.Also, ingot 60 has circumferential lateral surface 61c, and circumferential lateral surface 61c is connected with the outer rim of the first face 61a and the second face 61b, withFirst face 61a and the second face 61b vertical side upwardly extends.The positive 61a of ingot 60 becomes the shadow surface of laser beam, therefore is groundWear into mirror surface.
The circumferential lateral surface 61c of ingot 60 has the first directional plane 63 and second orientation vertical with the first directional plane 63 flatFace 65.The length of first directional plane 63 is formed as longer than the length of the second directional plane 65.First directional plane 63 and secondThe crystal orientation of the expression ingot 60 of directional plane 65.
Ingot 60 includes c-axis 68, and the vertical line 67 relative to positive 61a tilts deflecting angle to 65 direction of the second directional planeα；And the face c 69, it is vertical with c-axis 68.The face c 69 tilts deviation angle alpha relative to the positive 61a of ingot 60.In general, in hexagonal crystal listIn brilliant ingot 60, the direction vertical with the shorter extending direction of the second directional plane 65 is the inclined direction of c-axis.
The numerous face c 69 is set with according to the molecular level of ingot 60 in ingot 60.In the present embodiment, deviation angle alpha is setIt is set to 4 °.However, deviation angle alpha is not limited to 4 °, such as it can freely be set in the range of 1 °~6 ° and produce ingot 60.
Then, it is illustrated referring to generation method of the Fig. 4 to Figure 11 to the chip of present embodiment.Fig. 4 is flag activationThe explanatory diagram of forming step, Fig. 5 to Fig. 9 are the explanatory diagrams that separation start forming step is shown respectively, and Figure 10 and Figure 11 are differenceThe explanatory diagram of chip strip step is shown.In addition, the only an example of step shown in above-mentioned each figure, is not limited to the knotStructure.
As shown in figure 4, firstly, implementing label forming step to ingot 60.In label forming step, first in ingot 60 is fixedStripe shape label 71 is formed in plane 63 and tilts linear label 72.Stripe shape label 71 and the linear label of inclination72 generation type is not particularly limited, and may be exemplified out the units such as laser marker or ink-jet printer.Stripe shapeLabel 71 extends to the second face 61b from the first face 61a, in the direction vertical with the direction for cutting out wafer W (referring to Fig.1 1)Extend on (that is, direction parallel with the direction perpendicular to each face 61a, 61b).Stripe shape label 71 is same as bar code,Can obtain various information according to the thickness of line and interval, stripe shape label 71 as ingot 60 ID and include being capable of areaSeparate the identification information of multiple ingots.
Linear label 72 is tilted to be formed side by side on the first directional plane 63 with stripe shape label 71.Inclination is linearLabel 72 tilts to always the second face 61b from the first face 61a, in the present embodiment, tilts linear label 72 with approach theTwo face 61b and be formed obliquely on the direction being gradually distance from relative to adjacent stripe shape label 71.In addition, parallaxThe inclined direction of shape label 72 is also possible to the direction inverted upside down in Fig. 4.
After implementing label forming step, implement separation start forming step.It is first in the forming step of separation startIt is first, as shown in figure 5, be for example aligned ingot 60 along the x axis according to the second directional plane 65 of ingot 60 using wax or bonding agentMode, which is fixed on, to be kept on workbench 21.In the fixation, as shown in fig. 6, making and being formed with the Y1 of deviation angle alpha (referring to Fig. 3)The vertical direction in direction (i.e. the direction arrow A) is aligned with X-axis.Laser beam is set to hang down along with the direction for being formed with deviation angle alpha as a result,The straight direction A is scanned.In other words, using the A direction vertical with the direction Y1 of deviation angle alpha is formed with as holding workbench 21Processing direction of feed.
Before and after ingot 60 is fixed, the wavelength of laser beam is set as to the wavelength for having permeability for ingot 60(such as wavelength of 1064nm).Then, as shown in fig. 7, the focal point of laser beam LB is being located in the first face apart from ingot 60 (justFace) 61a be equivalent to the wafer W to be generated (referring to Fig.1 1) thickness depth D1.Later, make the focal point and ingot of laser beam LB60 relatively move on X-direction (direction A) and irradiate laser beam LB from the first face side 61a.Then, in ingot 60 formed withFirst face 61a parallel modification layer 75, and the crackle 76 propagated from modification layer 75 along the face c 69 (referring to Fig. 3) is formed, theseModification layer 75 and crackle 76 are formed as separation start (referring to Fig. 8).Modification layer 75 refers to and makes because of the irradiation of laser beam LBDensity, refractive index, mechanical strength or other physical characteristics of the inside of ingot 60 become state different from surrounding and intensity is than weekEnclose the region of reduction.Layer 75 e.g. fused region, slit region, insulation breakdown region, refractive index change regions are modified,It is also possible to their mixed regions.
Separation start forming step includes following step: modification layer forming step irradiates laser beam LB as described aboveAnd form modification layer 75 and crackle 76；And indexing steps, move focal point relatively in the Y direction for be formed with deflecting angleIt is dynamic and indexable according to the progress of the amount of regulation.
In indexing steps, move ingot 60 along the direction arrow Y1, so that the focal point to laser beam LB is being formed with partiallyThe direction of the digression and face c 69 (referring to Fig. 3) is to carry out indexing according to the amount of regulation on the direction arrow Y2 of descending.When with thisWhen mode sets direction of index, although the modification layer 75 and crackle 76 that are formed on the face c 69 linearly are modifying the two of layer 75Lateral edge the face c 69 propagate and formed, crackle 76 will not interfere the irradiation of the laser beam LB next irradiated.
Also, separation start forming step includes following indexing amount setting procedure: to from linear modification layer 75 along cFace direction is propagated and the width of the crackle 76 of formation is measured, and is set to the indexing amount of focal point.
In indexing amount setting procedure, as shown in fig. 7, will be square along the face c 69 (referring to Fig. 3) from linear modification layer 75To propagation and be formed in modification layer 75 side crackle 76 width be set as W1 in the case where, answer indexing defined amount W2 quiltIt is set as twice of value of width W1 or more and width W1 or less (W1≤W2≤2 × W1).
Here, it is preferred that the laser processing condition of embodiment is set in the following way.
Light source: Nd:YAG pulse laser
Wavelength: 1064nm
Repetition rate: 80kHz
Average output: 3.2W
Pulse width: 4ns
Spot diameter: 10 μm
The numerical aperture (NA) of collector lens: 0.45
Indexing amount: 400 μm
In above-mentioned laser processing condition, in Fig. 7, from modification layer 75 along the crackle 76 of the face c 69 (referring to Fig. 3) propagationWidth W1 be set to substantially 250 μm, indexing amount W2 is set to 400 μm.
The average output of laser beam LB is not limited to 3.2W, in the processing method of present embodiment, by average outputGood result can be obtained by being set as 2W~4.5W.In the case where average output is 2W, the width W1 of crackle 76 is substantially100 μm, in the case where average output is 4.5W, substantially 350 μm of the width W1 of crackle 76.
In the case where the case where average output is less than 2W and bigger than 4.5W, good change can not be formed in the inside of ingot 60Matter layer 75, therefore the average output of the laser beam LB preferably irradiated is in the range of 2W~4.5W, in the present embodimentThe laser beam LB that average output is 3.2W is irradiated to ingot 60.In Fig. 7, the first face of focal point distance of modification layer 75 will be formedThe depth D1 of 61a is set as 500 μm.
(A) of Fig. 9 and (B) of Fig. 9 are illustrated for the scanning direction of the laser beam to separation start forming stepSchematic diagram.As shown in (A) of Fig. 9, according to toward road X1 and return road X2 implement separation start forming step, when along toward road X1 in ingotFormd in 60 the laser beam of modification layer 75 focal point be indexed according to the amount of regulation after, formed in ingot 60 along returning road X2Modify layer 75.
Also, in the forming step of separation start, laser beam focal point answer indexing defined amount W2 be setIn twice of value situation below for the width W1 or more and width W1 of crackle 76, preferably the focal point of laser beam is positioned inThe indexing amount W2 of focal point in ingot 60 and before forming initial modification layer 75 is set as width W1 or less.
For example, as shown in (B) of Fig. 9, the case where the defined amount that the focal point to laser beam carries out indexing is 400 μmUnder, 200 μm are measured according to indexing the scanning of laser beam is performed a plurality of times until forming initial modification layer 75 in ingot 60.
Sky is swept in the scanning of initial laser beam, forms initial modification layer 75 in the inside of ingot 60 specifyingLater, it is set as 400 μm of indexing amount and forms modification layer 75 in the inside of ingot 60.
After implementing separation start forming step, implement chip strip step, by applying external force from by modifyingThe plate object that the thickness for being equivalent to wafer W to be formed is separated from ingot 60 is played in the separation start that layer 75 and crackle 76 are constituted,To generate wafer W.Such as pressing mechanism 54 shown in (A) by Figure 10 implements chip strip step.Pressing mechanism 54Include: head 56 is moved along the vertical direction by the mobile mechanism being built in column 52 (referring to Fig.1)；And press sectionPart 58, relative to head 56 as shown in Figure 10 B as rotate along the direction arrow R.
As shown in (A) of Figure 10, pressing mechanism 54 is located in the top for being fixed on the ingot 60 for keeping workbench 21, is such as schemedShown in 10 (B), pressing component 58 drops to head 56 crimped with the first face (front) 61a of ingot 60 until.
When making pressing component 58 along the arrow side R in the state that pressing component 58 is crimped on the first face 61a of ingot 60To distorting stress when rotation, is generated in ingot 60, ingot 60 modifies the separation start of layer 75 and crackle 76 (referring to Fig. 7) from being formed withIt disconnects.Wafer W shown in Figure 11 is separated from ingot 60 as a result, cuts out wafer W from ingot 60.In addition, being removed from ingot 60Out after wafer W, preferably the parting surface of the parting surface of wafer W and ingot 60 is ground and is processed into mirror surface.
As shown in figure 11, from multiple wafer Ws that ingot 60 separates, on the first directional plane 63 of each wafer WIt is formed with stripe shape label 71.It, also can be in each wafer W although cutting out multiple wafer Ws from single ingot 60 and being removedIt is upper to form identical stripe shape label 71.The striped of wafer W is read using detection devices such as barcode readers as a result,Pattern shape label 71 is capable of detecting when that wafer W is cut out from which ingot 60 so as to obtain the ID of the ingot 60 as the source that cuts out's.
Also, linear label 72 is tilted being also formed with from multiple wafer Ws that single ingot 60 is cut out.Due in ingot 60The linear label 72 of middle inclination is formed in the inclined direction as described above, so the linear label 72 of the inclination in each wafer WForming position is respectively different on the extending direction (left and right directions in Figure 11) of the first directional plane 63.For example, in Figure 11,First wafer W cut out slave stripe shape label 71 to the distance a1 and second crystalline substance cut out for tilting linear label 72Piece W's is different from stripe shape label 71 to the distance a2 for tilting linear label 72.Therefore, after according to removing is formed inWafer W the first directional plane 63 on stripe shape label 71 and tilt the relative position of linear label 72, Neng GoujianMeasuring wafer W is which cuts out from which ingot 60.
As described above, ingot 60 according to the present embodiment can be identically formed respectively in the multiple wafer Ws cut outA part of the stripe shape label 71 of ingot 60.The all wafers W cut out as a result, from ingot 60 can be shown based on stripedThe ID of the ingot 60 of pattern shape label 71.Even if implementing the various processing such as grinding or grinding to wafer W after cutting out as a result, and inciting somebody to actionThe wafer W cut out from multiple ingots 60 mixes, and is also capable of detecting when that wafer W is cut out from which ingot, can easily reallyProtect the trackability of the wafer W.
Also, it is linear that the different inclination in position in the present embodiment, can be respectively formed in the multiple wafer Ws cut outLabel 72.As a result, by the position of the linear label 72 of inclination of detection wafer W, it is capable of detecting when to cut out wafer W in ingot 60Sequentially.
Also, as shown in fig. 7, direction of index is set as the direction arrow Y2, although in the two sides of modification layer 75 along the face c 69(referring to Fig. 3) forms crackle 76, and crackle 76 will not interfere the irradiation for being used to form the laser beam LB of next modification layer 75.ByThis, can easily separate from ingot 60 from the separation start being made of modification layer 75 and crackle 76 and be equivalent to wafer WThe plate object of thickness and generate wafer W.
In addition, the forming position about stripe shape label 71 and the linear label 72 of inclination, can also be formed in secondOn directional plane 65, perhaps it is formed on the circumferential lateral surface 61c other than directional plane 63,65 or is formed in without orientationOn the circumferential lateral surface 61c of the ingot 60 of plane 63,65.But from the viewpoint of workability, formed on directional plane 63,65Each label 71,72 is advantageous.
Also, in the present embodiment, it is configured to implement separation start forming step and crystalline substance using laser processing devicePiece strip step, but it is not limited to the structure.These steps can also be implemented using dedicated device respectively.
Also, present embodiment and variation are illustrated, but as other embodiments of the invention, it can also be withAbove embodiment and variation are globally or locally combined.
Also, embodiments of the present invention and variation are not limited to the above embodiment, and can also not depart from thisIt makes various changes, replace, deform in the range of the purport of the technical idea of invention.In addition, if improving or spread out because of technologyThe other technologies that bear and can realize technical idea of the invention using other modes, then also can be used this method come it is realIt applies.Therefore, cover can be comprising all embodiments within the scope of the technical idea of the present invention for claims.
Also, in the present embodiment, the structure for applying the present invention to ingot is illustrated, but can be applied canBy in machined object of the modification layer to carry out good segmentation.
As described above, the present invention has the effect for the trackability that can readily insure that the chip after cutting outFruit, it is especially useful to the ingot for cutting out multiple plate objects such as chip using laser processing.