Laser processing method and device for transparent materials

Abstract

A method for processing materials nearly transparent to laser wavelengths involves forming a non-centrosymmetric, non-diffracting beam using an optical element containing at least two zones of birefringent structure that change the Pancharatnam-Berry phase according to a rule specific to that zone. The energy, phase, and polarization distribution depend on the parameters of the light approaching this element. The pulse energy is selected to form a gap extending in the desired direction using the distribution's main maximum, while the secondary maximum forms a chemical change between damage from adjacent pulses. The zone of gap damage and chemical change forms the desired cut line. The workpiece thus processed is placed in a chemically aggressive solution, where the zone affected by the laser light dissolves much faster than the unaffected zone. This allows for cuts with aspect ratios of up to 1 / 50.

Description

[Technical field]

[0001] The present invention is in the field of lasers and relates to processing transparent media, and can be used to cut, split, and otherwise process transparent media, including different types of glass, chemically strengthened glass, sapphire, and other crystalline materials, by using an ultrashort pulsed laser radiation beam. [Background technology]

[0002] Laser methods are used to make holes of very small dimensions or free-form cuts in workpieces of transparent materials. Conventional laser micromachining methods (drilling, cutting, grooving, etc.) generally rely on ablation, which removes material by focusing the energy of a laser pulse on the affected area. When femtosecond lasers are used for this, the edges of the holes or cuts are very clean, and there is virtually no material that cannot be machined by such lasers. However, ablation has a fundamental drawback: it cannot remove material from very narrow gaps or holes with small diameters. This is due to the fact that the material being removed from the bottom of the cut accumulates on the wall above the affected area and gradually blocks the light. This drawback is circumvented by using a split separation, where the laser pulse creates a damaged area along the desired split line. However, this method is very limited when splitting the workpiece along a line of high curvature, and especially when holes need to be drilled. The task becomes more complicated when the workpiece consists of glass, especially when the glass is reinforced. Glass has recently become an increasingly important material used in semiconductor technology (as the basis for semiconductor structures), in the manufacture of microelectromechanical systems, and in the manufacture of microfluidic devices. All of these fields require the ability to create incisions, holes or channels of arbitrary shape. Recently, a combination of laser methods and chemical etching has been used, which greatly expands the capabilities of these methods.

[0003] Known analogues use acid or alkaline etching of the laser-affected material. US20180029924 describes a method for etching holes made with an ultraviolet laser with HF acid, taking advantage of the property that laser-affected material etches faster than unaffected material. The holes thus obtained vary in diameter across the thickness of the workpiece (usually hourglass-shaped), and the holes expand uniformly in all directions during etching. This results in a cut with a width approximately equal to the pitch between the holes during etching of the entire cut line.

[0004] The method proposed in US Patent Publication No. 2018037489 is also non-directional, meaning that the laser drilled holes will expand evenly in all directions during etching. This method is not intended for creating notches or grooves, only circular holes.

[0005] US Patent No. 9,517,963 describes a method using etching to enlarge the laser-drilled holes evenly. In this method, a non-diffracting Bessel beam that is centrally symmetric is used to drill the holes in the glass, resulting in circular and non-directional holes. This method does not offer the option of etching an even cut, but only facilitates the separation of the workpiece along the line connecting the holes. Using the described method, the workpiece is subject to a large inclination at the entrance and exit of the holes, i.e., the shape of the holes deviates significantly from cylindrical, resulting in irregularly shaped and tapered cuts. Also, the laser drilling creates microcracks of unpredictable shape around the holes, which, when spread by the glass-etching acid, enlarge the holes and at the same time reduce the smoothness of the break, and the random nature of the cracks prevents the break from being uniform along the parting line.

[0006] EP 3102358 describes a method in which holes made with a laser are enlarged by etching, and these holes are then used to break the glass along the contours formed by the holes. The directionality of the etching process is not desired or controlled, and the holes are not connected.

[0007] US Patent Publication No. 20160152508 describes a method for separating glass workpieces along lines of holes that are laser drilled and etched wide, where the directionality of the etching process is not desired or controlled and the holes are not connected.

[0008] Using the combined laser and chemical processes described above, glass holes can be drilled in pieces of sufficient thickness to obtain glass thickness to diameter ratios of 20 to 30 or more. The main problem with these is that after etching the affected glass with strong acids such as HF, BHF, HF+HNO3, or their mixtures, the resulting holes have shapes that deviate significantly from cylindrical (e.g., "hourglass") and their edges are not straight but have a large slope of 5 to 10% of the diameter, which is unacceptable for most applications. Etching the affected glass with alkalis such as NaOH or KOH results in holes with much more precision than with acids, but the process itself is very slow, taking several hours to etch gaps several micrometers in length. Summary of the Invention [Problem to be solved by the invention]

[0009] An object of the present invention is to improve the processing quality of a transparent material when dividing or cutting the transparent material and to increase the processing accuracy at the same time. [Means for solving the problem]

[0010] In order to solve the above problems, the present invention proposes a method for processing transparent materials by forming a cutting or dividing surface in the material of a workpiece. The method includes two processing steps, namely: A step of forming a cutting or parting surface using a laser without completely separating parts of the workpiece from one another, A.1 TEM 00 Mode coherent ultrashort pulses of generating a beam of laser radiation by a laser; A.2 directing the generated laser radiation beam into an optical system that shapes the set diameter, total pulse energy, and polarization of the laser radiation beam; A.3. subjecting the laser radiation beam formed in step A2 to an optical element which transforms the incident laser radiation beam according to a predetermined rule; A.4 The formed laser radiation beam is radiation localizing a beam radiation at the workpiece, the workpiece being of a material substantially transparent to the beam radiation, predetermined parameters of the laser radiation pulse ensuring that at a focal region of the workpiece being machined, the laser radiation energy density is sufficient to change a property of the workpiece material; A.5 controllably moving the workpiece to be processed relative to the laser radiation beam so that the focal points of the laser radiation beam on the workpiece are respectively moved to generate the required number of damage areas to form cuts and / or parting surfaces of the desired trajectory; and an A stage including step B of completely separating parts of the workpiece from each other based on the locus of the cutting and / or parting planes formed during step A by placing the workpiece in a chemical medium and etching the workpiece material in the damage areas; Including, In step A.3 ,beforeIn the optical element (10) having a birefringent structure for smoothly varying the Pancharatnam-Berry phase (PBP) of the laser radiation beam, the transformation of the laser radiation beam is performed according to the predetermined rule, at least two regions of the structure are formed in the optical element (10) having different PBP transformation rules and orientations with respect to the laser radiation beam approaching the element, the at least two structure regions respectively form at least two sub-beams, and the structure regions are arranged to change the polarization of the laser radiation beam approaching the optical element (10), such as a type of polarization, such as linear, radial or azimuthal, and / or an orientation of a linear polarization plane with respect to a direction of the locus of cuts or cleavages in the element, It has the ability to change the distribution of energy, phase and polarization of the sub-beams depending on the parameters of the radiation, the formed sub-beams interfere with each other to obtain a total non-diffracting laser radiation beam with an eccentrically symmetric distribution of focal lines of the set energy, phase and polarization and with a better elongation in a plane perpendicular to the propagation direction of the laser radiation beam, the desired shape of the distribution can be obtained by changing the parameters of the laser radiation approaching the optical element (10) formed in step A.2, the eccentrically symmetric distribution of the non-diffracting laser radiation beam having an elliptical main energy maximum containing most of the energy of the pulse with density ρ in the plane perpendicular to the propagation of light. ,before and a secondary energy maximum having an elongated shape in the plane of the graph, the total resulting laser radiation beam is localized in the workpiece, each laser radiation pulse forming an elongated general damage area, the damage area being composed of physical changes formed by voids and / or cracks under the influence of the main energy maximum and chemical changes caused in the workpiece material under the influence of the secondary energy maximum, the general damage area of ​​the workpiece being oriented along the locus of the cuts and / or tears by rotating the element (10) about an axis and moving the workpiece to be processed in a controlled manner, whereby the elongated damage areas formed are positioned one after the other in the longitudinal direction with gaps along the locus of the cuts and / or tears due to the physical changes in the material of the workpiece to be processed, On the other hand, in steps A.4 and A.5, the laser is used to expand the damage area caused by the chemical change of the workpiece material to a degree that adjacent common damage areas are adjacent or partially overlap along the locus of the cut. radiation Pulse energy and power, and the speed of movement of the workpiece are selected such that, during the B stage, the chemical medium simultaneously acts on the workpiece material over the entire trajectory of the cut.

[0011] The elongated common damage region that is formed lies in an elliptical surface, the elliptical surface having a substantially constant size perpendicular to the light propagation direction and varying no more than + / - 15% from an average value along said direction.

[0012] The locus of the cutting or splitting plane may include one or more non-diffracting beams. To Thus, a narrow common damage region is formed.

[0013] The elongated damage caused by the physical change in the workpiece is arranged with a step that exceeds the width of the damage by at least 1.5 times.

[0014] In step B, the workpiece is successively immersed in several selected chemically active liquids, such as solutions of KOH, Na2CO3, HF, and HCl, to transfer and dissolve the products of previous chemical reactions formed and remaining in the damage area of ​​the workpiece into another solution that affects the workpiece.

[0015] According to another embodiment of the present invention, an apparatus for processing transparent materials is proposed, the apparatus comprising: The laser radiation beam is incident on a TEM optical system that changes the pulse energy, light polarization, and diameter. 00 a laser generating an ultrashort pulsed laser radiation beam in mode (2), whereby the laser radiation beam formed by the optical system is localized on a workpiece to be processed via optical elements intended to transform an incident beam according to a predetermined rule, the workpiece material being substantially transparent to the laser radiation beam, and selected parameters of the laser radiation beam pulses formed by the optical system ensure a laser radiation energy density sufficient to change the properties of the workpiece material in a focal region; a controllable positioning mechanism intended to move the workpiece to be processed relative to the laser radiation beam such that the focal point of the laser radiation beam on the workpiece moves, generating the required number of damage zones and forming cuts and / or partings of the desired trajectory in the workpiece; a container containing a chemical medium for etching the workpiece material in the damaged areas, the container being intended to place the workpiece therein and to separate parts of the workpiece from one another according to the locus of the formed cutting and / or parting surfaces; Including, The optical element, located outside the optical system in the path of the laser radiation beam and intended to transform the incident laser radiation beam according to the predetermined rule, has a birefringent structure that uniformly changes the Pancharatnam-Berry phase (PBP) of the perpendicular laser radiation beam, whereby at least two regions of the birefringent structure with different PBP transformation rules and orientations with respect to the laser radiation beam approaching the element are arranged on the workpiece, the structure regions forming at least two interfering sub-beams to generate a total non-diffracting laser radiation beam with a predefined eccentricity-symmetric distribution of focal lines of the energy, phase and polarization, with better elongation in a plane perpendicular to the propagation direction of the laser radiation beam, with a main energy maximum and a secondary energy maximum, the optical element being mounted on a mounting mechanism that rotates around an axis to change the position of the element and to change the birefringent structure formed therein. the fully non-diffracting laser radiation beam formed by the element is localized at the workpiece via focusing optics, and the mechanism rotates the optical element to change the orientation of the formed elongated damage regions along the locus of the cutting line, and the controllable positioning mechanism moves the workpiece in a manner such that the formed elongated common damage regions consisting of physical and chemical changes in the workpiece material are positioned longitudinally one after the other along the locus of cuts and / or tears, with gaps between them due to the physical changes in the workpiece material, and the damage regions caused by the chemical changes in the workpiece material extend along the locus of cuts to an extent that adjacent common damage regions are adjacent or partially overlapping. Effect of the Invention

[0016] The proposed method of laser chemical machining of a workpiece can produce precisely shaped cuts or holes in a time that is more than 10 times faster than known methods such as laser-assisted chemical etching (LACE) or laser-induced chemical etching (LICE).

[0017] The proposed invention allows etching laser-formed thin bond lines in physically and chemically adapted damaged areas, where the overall damage is caused by changes in the structure of the workpiece material, including formation of holes, self-aligned structures, mechanical stresses, and chemical changes associated with rearrangement of chemical bonds and formation of free bonds.

[0018] In the proposed method, the oval cross-section beam at the highest point of intensity creates physical damage (leading to perforation), while the lower intensity area spreads along the direction of the cut line, changing the chemical properties of the material. The resulting overall damage area achieves a maximum cut width-to-depth ratio of 1:100 without deviation from the vertical axis by more than 2°, and increases the processing accuracy by keeping the cut slope below 0.1 μm. The surface irregularities of the etched cuts should not exceed 2 μm, the slope should not exceed 0.1 μm, and the cuts should not have overlaps. Therefore, products made using this method can be used in applications requiring high precision and high perpendicularity, such as guide spacers for test boards for semiconductor devices, and their lifespan can be significantly extended.

[0019] Because there are no slopes or overlaps, the product can be used for planar crosslinking without further polishing after chemical treatment, which speeds up the production of micro-electromechanical systems (MEMS) and microfluidic devices. [Brief description of the drawings]

[0020] The invention is explained in more detail in the following drawings, which do not limit the scope of the invention. [Figure 1] FIG. 1 shows a partial schematic block diagram of the proposed transparent material processing apparatus, illustrating the formation of the laser beam before it enters the distribution shaping optics. [Diagram 2] FIG. 1 shows a partial schematic diagram of the proposed transparent material processing apparatus, illustrating how the desired distribution is formed and positioned within the workpiece to be processed. [Diagram 3] The coordinates of the birefringent structure formed in the beam conversion element are shown in a polar coordinate system and a rectangular coordinate system. [Figure 4] The regions of PBP change in elements arranged in sectors are shown. [Diagram 5] Regions of PBP change in concentrically arranged elements are shown. [Figure 6] The most common arrangements of PBP-changing zones in the element are shown, and the variation of PBP in different sectors also depends on the distance of the birefringent structure from the center of the element. [Figure 7] We present a particular case where the PBP transformation in two 180° sectors has different dependence on the distance from the center. [Figure 8] 8 shows measurements of the lateral energy distribution produced by the device of FIG. [Figure 9] 9 shows the variation of energy of the distribution of FIG. 8 along the direction of light propagation. [Figure 10] 1 shows directionally controlled damage lines obtained by rotating the element about the axis of the beam. [Figure 11] The extent of physical damage (perforations) and chemical damage (bond dislocations) is identified, showing the damage to this line. [Figure 12] The structures of the most common alkaline earth aluminosilicate glasses are shown. [Figure 13] 1 shows a distribution map of the notch edges measured by atomic force microscopy (AFM). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] The proposed method for processing transparent materials involves the following sequence of operations:

[0022] The processing method of the transparent material has two processing steps. In stage A, the laser is used to create a cutting or parting surface without completely separating the parts of the workpiece. Stage A includes the following steps: A.1-TEM 00A mode coherent ultrashort pulsed laser radiation beam is generated by a laser. A.2 - The generated laser radiation beam is incident on an optical system which forms a set diameter, total pulse energy and light polarization of the laser radiation beam. A.3 - The laser radiation beam formed in step A2 is incident on an optical element which transforms the laser radiation beam according to a predefined rule. This transformation occurs in an optical element in which a birefringent structure is formed which uniformly changes the Pancharatnam-Berry phase (PBP) of the vertically directed laser beam. At least two of the regions of this structure are formed in this optical element, which have different rules of modification of the PBP of these regions and their orientation with respect to the vertically directed laser beam. The at least two said regions of this structure each form at least two sub-beams, the distribution of energy, phase and polarization of which can be changed depending on the parameters of the light directed to the optical element, for example the type of polarization (linear, circular, radial or azimuthal, etc.) and / or the orientation of the linear polarization plane with respect to the direction of the locus of the cuts or splits in the element. The formed sub-beams interfere with each other to obtain a total non-diffracting laser radiation beam with a set off-center symmetric distribution of the focal line of energy, phase and polarization and with a better elongation in a plane perpendicular to the laser radiation beam divergence direction, the desired shape of which can be obtained by changing the parameters of the laser radiation formed in step A.2 and directed to said optical element. The integrated laser radiation beam obtained in step A.4 is localized at the workpiece, and each pulse of laser radiation forms an oval-shaped global damage area consisting of physical and chemical changes in the workpiece material. The workpiece material, where the laser radiation beam is localized, is nearly transparent to the laser radiation beam, and the set parameters of the laser radiation pulses ensure that in the focal area of ​​the workpiece to be processed, the laser radiation energy density is sufficient to change the properties of the workpiece material.In step A5, the workpiece to be processed is moved in a controlled manner by rotating the optical element about its axis, so that the overall damage area of ​​the workpiece is oriented along the locus of the cuts and / or tears, and the elongated damage areas formed are positioned longitudinally one after the other along the locus of the cuts and / or tears with gaps. The energy and power of the laser pulses and the movement speed of the workpiece are selected such that the damage area formed by the chemical change of the workpiece material expands the damage area caused by the physical change of the damage along the locus of the cuts to such an extent that adjacent common damage areas join or overlap. The elongated common damage areas formed are in an elliptical plane, the elliptical plane having an approximately constant size perpendicular to the light propagation direction and more preferably varying within a range of + / - 15% or less from the average value along the aforementioned direction. The locus of the cut or split plane is formed from the elongated common damage area by spreading more than one non-diffracting beam along the locus of the cut or split plane by a distance comparable to the lateral dimension of the beam. The elongated damage resulting from the physical change in the workpiece is arranged with a step that is at least 1.5 times greater than the width of the damage.

[0023] Then, in step B, the parts of the workpiece are completely separated from each other based on the locus of the cutting and / or parting planes formed in step A, by placing the workpiece in a chemical medium and etching the workpiece material in the damage areas. Due to the adjacent or overlapping common damage areas formed along the locus of the cuts or slits, the chemical medium simultaneously affects the workpiece along the entire locus of the cutting or parting planes, and the affected workpiece material in this locus dissolves much faster than the unaffected parts of the workpiece. After keeping the workpiece in the solution for the required time, the reagent dissolves the workpiece material along the cutting line and widens the cutting line slightly perpendicular to the cutting line, separating the parts of the workpiece from each other. The chemical medium in which the workpiece is placed after treatment with the laser radiation beam in step A can be a solution of KOH, but it is more preferable to successively place the workpiece in several solutions of chemically active liquids such as KOH, Na2CO3, HF, and HCI. After removing the workpiece from one chemical medium solution, the workpiece is placed in a solution of another chemical medium, which dissolves the products of the previous chemical reaction that formed and remain in the damaged area of ​​the workpiece, and thus the workpiece is placed in the solutions of the different chemical media until the parts of the workpiece are very precisely separated from each other without lateral cracks.

[0024] A laser (1) is used to split the transparent material in the proposed way (Figure 1) TEM 00 Mode ultrashort (duration 100 fs to 10 ps) optical pulses are generated, which have a cross-sectional energy distribution described by the Gaussian equation (2).

[0025]

number

[0026] where I(r) is the light intensity at a point on the beam having distance r from the beam axis, I(0) is the light intensity at the beam axis, and ω0 is the distance from the axis to the point where I(r)=1(0) / e.

[0027] The light intensity of the beam is controlled by a variable wavelength attenuator (3), which consists of a half-wave plate (4) and a polarizer (5) whose polarization plane is configured to pass all of the light coming from the laser without the plate (4) in the optical path. By rotating the direction of the slow axis of the plate with respect to the polarization plane of the laser light, the direction of polarization of the light passing through the plate is rotated accordingly, and the polarizer (5) passes only the light component parallel to the polarization of the light emitted by the laser, allowing between 0% and 100% of the light from the laser to pass depending on the rotation angle of the plate (3).

[0028] The diameter of the light beam passing through the attenuator is set by an adjustable extender (6) consisting of a pair of negative (7) and positive (8) lenses. By adjusting the distance between these lenses, the required diameter of the beam leaving the extender is obtained.

[0029] If a light beam needs to be given an elliptical polarization, a quarter wave plate (9) is placed in its path, and the angle between its slow axis and the plane of polarization of the light directed at the plate sets the ellipticity and the direction of rotation (left or right) of the circular polarization.

[0030] An optical element (10), consisting of a flat workpiece of transparent material with a structure formed thereon that changes the Pancharatnam Berry phase (PBP) of light, is placed in the path of the laser light beam.

[0031] The diameter of the laser beam is selected so that the beam completely fills the working area of ​​the beam-forming element, i.e. the distance R from the beam axis. E The light intensity at is I(R E )≦I(0) / e 2 or less, in other words, the radius of the element must be at least twice the Gaussian beam radius in equation [1]. That is,

[0032]

number

[0033] By placing a beam-shaping element (10) with different PBPs depending on the cross-section in the laser beam (11), the polarization plane is rotated according to a predetermined rule at different positions in the element, introducing the required phase delay. The element is attached to a rotation mechanism (12), which allows changing the position of the element and at the same time the structures recorded on it, with respect to the polarization plane directed at the element. The light beams (13) emanating from the various parts of the element can interfere with each other in a constructive and destructive way to form the desired distribution (14) of energy, phase and polarization. The shaped distribution (18) is transmitted to the workpiece (19) through focusing optics (15, 16, 17). At least a part of the focusing optics forms a 4f scheme, which is used to add an additional amplitude function to the Fourier plane (16), such as to form the required distribution in the focal line while filtering out unwanted amplitude spectral elements. The position of the focal region in axis Z is determined by a height adjustment mechanism (20), and the workpiece itself can be moved in the XY plane by a positioning mechanism (21).

[0034] The element (10) forms one or more zones, in each of which the Pancharatnam-Berry phase (PBP) varies smoothly according to a rule established for that zone.

[0035] At each point in the cross section, the PBP value is set by the nanoplatelet-like periodic structure (23) formed in the workpiece body (Figure 3), and its orientation within the element is described by its dependence in Cartesian coordinates.

[0036]

number

[0037] In the formula, θ iis a function f i is the rotation angle of the periodic structure with respect to the coordinate axes of the i-th zone, represented by

[0038] Alternatively, it can be represented by the dependence in polar coordinates.

[0039]

number

[0040] Where: JPEG0007640090000005.jpg627 and φ i are the polar coordinates of the periodic structure in the cross section of the element.

[0041] To obtain an axially symmetric (circular or elliptical) distribution, these zones can be placed in both sectors (Figure 4).

number

[0042] In the formula, R E is the radius of the element, and φ min,i ,φ max,i are the start and end angles of the sector in polar coordinates.

[0043] Both concentric rings (Fig. 5)

number

[0044] (In the formula, γ min,i , γ max,i are the values ​​of the start and end radii of the ring) and the ring divided into sectors (Figure 6)

number

[0045] In each particular case, two zones with sectors 0<φ1≦π and π≦φ2≦2π are formed in the element, and the variation of the PBP is formed in each sector by a ring. In each zone, the variation of the PBP is represented by a function specific to that ring (Figure 7).

number

[0046] In the formula, θ ij,φn is the orientation angle of the PBF in the nth sector and ring i or j, where i and j are the numbers of rings in the first or second sector, respectively (Figure 7).

[0047] The PBP element produces a non-diffracting beam if the function is chosen as follows:

number

number

[0048] In the formula, r e is the radius of the element and a is a coefficient that determines the convergence angle of the sub-beams.

[0049] By placing an element (10) represented by functions [9] and

[10] in a laser light beam, an elliptical symmetric distribution is formed behind the element (Fig. 8) with one or more maxima in the light propagation direction (Fig. 9). The intensity distribution between the maxima is determined by the nature of the polarization of the light directed at the element (linear, circular or elliptical). A main maximum (24) is formed in the distribution, where most of the beam energy is concentrated, and elliptical secondary maxima (25) are also formed around it. The direction of the vertical axis (26) of the distribution ellipse (Fig. 8) depends on the orientation of the sector of the element in the plane perpendicular to the direction of light propagation.

[0050] By concentrating the distribution generated by the element on the glass, the pulse power density is limited to a limit value ρ rib Hollow damage regions form in the glass body after ρ is exceeded. The shape of these regions mimics the intensity distribution in the focal region. For example, borosilicate glasses with high alkaline earth element content (6% to 10%) have a ρ rib ≒1×10 15 Wcm -3 and for glasses without alkaline earth elements, this limit is ρ rib ≒5×10 14 Wcm -3 The energy distribution is ρ only at the main maximum (24). rib It is formed so as to exceed

[0051] By simultaneously moving the glass workpiece (19) in the XY plane perpendicular to the light propagation direction and changing the position of the longitudinal axis of the distribution ellipse by the rotation mechanism (12), the elliptical damage region (27) is positioned along the desired cutting line (28). The power density ρ of the overlapping submaxima (25) of adjacent pulses is determined to be the crack initiation threshold characteristic of that particular glass. ρsk If exceeded, the resulting chemical changes (29) (Figure 10) also generate physical stresses, binding together areas of physical damage.

[0052] Areas with altered physicochemical properties of the glass form around the damaged area (30, Fig. 11). Glass is a network of oxide structures mixed with alkali and / or alkaline earth metal cations. In each case, aluminosilicate glasses with an Al / Si content of more than 1 / 3 (Fig. 12) consist of tetrahedra of oxygen atoms with a silicon (31) or aluminum (32) atom at the center. Some of the vertices of these tetrahedra are connected by bridges of bridging oxygen (BO), which are classified according to the type of bond as BO1 (33), which connects Si-O-Si tetrahedra, and BO2 (34), which connects Si-O-Al tetrahedra. Free oxygen atoms at the corners are called non-bridging oxygen (NBO) (35). These relatively regular structures are relatively freely interposed with cations of alkali metals (AM, 36) and alkaline earth metals (EM, 37), whose presence affects the formation of oxygen bridges and the ratio of the amount of BO1 / BO2 bridges. For atomic weight AM / Al ≈ 1, the ratio of the amount of different types of bridges is BO2 / BO1 ≈ 3, NBO / BO2 = 0, whereas in glass workpieces with AM / Al ≈ 0.2, this ratio is known to be BO2 / BO1 ≈ 0.3, and non-bridging oxygen bonds of NBO / (BO1 + BO2) ≈ 0.1 are also observed.

[0053] When a laser pulse impinges on such a glass workpiece, a large change in the BO / NBO ratio is observed. For most glasses, the energy density of the laser pulse is 2×10 3 J / cm 2 It has been found that when the ratio exceeds 0.3, the BO / NBO ratio is about 0.3, i.e., the amount of BO bridges is reduced by more than three times compared to the glass not affected by the laser. When the glass is affected by the laser light, the BO bridges are broken and oxygen deficiency centers (ODCs) with excess silicon ≡Si-Si≡ or aluminum ≡Al-Al≡ (ODC I), or free bonds =Si 0 ir=Al 0Oxygen deficiency defects (ODC II) with ≡Si-O° or ≡Al-O° are formed in the structure. Also, Non Bridging Oxygen Deficiency Centers (NBOHC) such as ≡Si-O° or ≡Al-O° are formed in the structure. Both of these defects are significantly more chemically active than the unaffected glass, so when the affected workpiece is placed in an alkaline solution, hydroxyl anions react with the open bonds and form soluble products such as: (Number 11) [-Si-O-Si-]+OH - →[-SiO] - +[-Si-OH]

[11] (Number 12) [-Al-O-Al-]+OH - →[-AlO] - +[-Al-OH]

[12]

[0054] The oxides of the network-modifying alkaline earth metals (Ca, Mg, Ba, Zn), which form when the metals combine with free oxygen, do not react directly with alkalis but can dissolve in them, while the alkali metals (Li, Na, K) enter the solution in the form of their hydroxides.

[0055] The above process allows the areas of the glass affected by the submaxima of the pulse to dissolve in the alkali up to 1000 times faster than the unaffected areas. This means that by creating areas with a high content of free oxygen or active silicon-aluminum bonds at the desired cut line, the alkali essentially dissolves only the area of ​​the cut without touching the workpiece material, and no workpiece material needs to be removed. This results in a very precise cut. As can be seen in Figure 13, the edges of the cut are only beveled by 0.05 μm to 0.1 μm (50 nm to 100 nm).

Claims

1. A method for processing a transparent material by forming a cutting or parting surface in the material of a workpiece, comprising two processing steps: A step of forming a cutting or parting surface using a laser without completely separating parts of the workpiece from one another, A.1 TEM 00 generating a coherent ultrashort pulsed laser radiation beam of a mode by a laser; A.2 Incident the generated laser radiation beam into an optical system that shapes the laser radiation beam into a set diameter, total pulse energy, and polarization of light; A.

3. A step of directing the laser radiation beam formed in step A2 to an optical element which transforms the incident laser radiation beam according to a predetermined rule; A.4 localizing the formed laser radiation beam on the workpiece, which is a material that is substantially transparent to the laser radiation beam, and predetermined parameters of a laser radiation pulse ensure that at a focal region of the workpiece to be processed, the laser radiation energy density is sufficient to change the properties of the workpiece material; A.5 Controllably moving the workpiece to be processed relative to the laser radiation beam so that the focal points of the laser radiation beam on the workpiece are respectively moved to generate the required number of damage areas to form cuts and / or parting surfaces of the desired trajectory; and a stage A comprising: step B of completely separating parts of the workpiece from each other based on the locus of the cutting and / or parting planes formed during step A by placing the workpiece in a chemical medium and etching the workpiece material in the damaged areas; Including, In step A.3, in an optical element (10) with a birefringent structure for smoothly changing the Pancharatnam-Berry phase (PBP) of the laser radiation beam, the transformation of the laser radiation beam is performed according to the predetermined rule, at least two regions of the structure are formed in the optical element (10) with different PBP transformation rules and orientations with respect to the laser radiation beam approaching the element, at least two of the structure regions respectively form at least two sub-beams, the structure regions being capable of changing the distribution of energy, phase and polarization of the sub-beams depending on the parameters of the laser radiation beam approaching the optical element (10), such as the type of polarization, such as linear, radial or azimuthal, and / or the orientation of the linear polarization plane with respect to the direction of the locus of the cutting and / or splitting surfaces in the element, the formed sub-beams interfere with each other to obtain a non-diffracting laser radiation beam with an eccentrically symmetric distribution of the focal lines of the set energy, phase and polarization and with a better elongation in a plane perpendicular to the propagation direction of the laser radiation beam, and in step A. a desired shape of the distribution can be obtained by changing the parameters of the laser radiation beam approaching the optical element (10) formed in accordance with claim 2, the off-center symmetric distribution of the non-diffracting laser radiation beam having in the plane perpendicular to the light propagation a main energy maximum of elliptical shape containing most of the energy of the pulse with a density ρ and a secondary energy maximum of elongated shape in the plane, the resulting non-diffracting laser radiation beam is localized in the workpiece, each laser radiation pulse forming an elongated damage zone, the damage zone consisting of physical changes formed by voids and / or cracks under the influence of the main energy maximum and chemical changes caused in the workpiece material under the influence of the secondary energy maxima, the damage zone of the workpiece being oriented along the locus of the cutting and / or parting surface by rotating the optical element (10) about an axis and moving the workpiece to be processed in a controlled manner, whereby the damage zones formed are positioned one after the other in the longitudinal direction with gaps along the locus of the cutting and / or parting surface by physical changes in the material of the workpiece to be processed, Meanwhile, in steps A.4 and A.5, the energy and power of the laser radiation pulses and the movement speed of the workpiece are selected such that the damage areas caused by the chemical changes in the workpiece material expand the damage areas caused by the physical changes in damage along the locus of the cutting and / or parting surface to such an extent that adjacent damage areas are adjacent or partially overlap, and in step B, the chemical medium acts simultaneously on the workpiece material over the entire locus of the cutting and / or parting surface.

2. 2. The method of claim 1, wherein the damage region formed is in an elliptical surface, the elliptical surface being of approximately constant size perpendicular to the direction of propagation of the light and varying no more than + / - 15% from an average value along the trajectory.

3. 3. The method of claim 1 or 2, characterized in that the locus of cuts or separations is formed from the damage area by more than one of the non-diffracting laser radiation beams.

4. In step B, KOH, Na ２ CO ３ 4. The method according to claim 1, characterized in that the workpiece is successively immersed in several selected chemically active liquids, such as solutions of fluorine, HF, HCl, etc., in order to transfer and dissolve the products of previous chemical reactions formed and remaining in the damage area of ​​the workpiece into another solution that affects the workpiece.

5. A transparent material processing device, comprising: The TEM is incident on an optical system that changes the pulse energy, light polarization, and diameter of the laser radiation beam. 00 a laser (1) for generating an ultrashort pulsed laser radiation beam in a mode (2), whereby the laser radiation beam formed by the optical system is localized on a workpiece (19) to be processed via optical elements intended to transform an incident beam according to a predetermined rule, the workpiece material being substantially transparent to the laser radiation beam, and selected parameters of the laser radiation beam pulses formed by the optical system ensure a laser radiation energy density sufficient to change the properties of the workpiece material in the focal region; a controllable positioning mechanism intended to move the workpiece to be processed relative to the laser radiation beam such that the focal point of the laser radiation beam on the workpiece moves, to generate the required number of damage areas and to form cuts and / or partings of the desired trajectory in the workpiece; a container containing a chemical medium for etching the workpiece material in the damaged areas, the container being intended to place the workpiece therein and to separate parts of the workpiece from one another according to the locus of the cut and / or parting surfaces formed; Including, The optical element (10), located outside the optical system in the path of the laser radiation beam and intended to transform the incident laser radiation beam according to the predetermined rule, has a birefringent structure that uniformly changes the Pancharatnam-Berry phase (PBP) of the laser radiation beam, whereby at least two regions of the birefringent structure with different PBP transformation rules and orientations with respect to the laser radiation beam approaching the element are arranged on the optical element (10), the structure regions form at least two interfering sub-beams to obtain a non-diffracting laser radiation beam with a predefined eccentrically symmetric distribution of the focal lines of the energy, phase and polarization, with better elongation in a plane perpendicular to the propagation direction of the laser radiation beam, and generate a non-diffracting laser radiation beam with a main energy maximum and a secondary energy maximum, the optical element (10) being mounted on a mounting mechanism (12) that rotates around an axis to change the position of the optical element (10) and to change the birefringent structure formed therein. the non-diffracting laser radiation beam formed by the optical element (10) is localized at the workpiece via focusing optics (15, 16, 17); the mechanism (12) rotates the optical element (10) to change the orientation of the formed damage areas along the locus of the cutting and / or splitting surface; the controllable positioning mechanism moves the workpiece in such a manner that the formed damage areas, consisting of physical and chemical changes in the workpiece material, are positioned one after the other in the longitudinal direction along the locus of the cutting and / or splitting surface with gaps due to the physical changes in the workpiece material; and the damage areas caused by chemical changes in the workpiece material extend along the locus of the cutting and / or splitting surface to such an extent that adjacent damage areas are adjacent or partially overlap each other.

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