JP4477325B2 - Processing method and apparatus using processing beam - Google Patents

Description

  The present invention relates to a single crystal sample processing method and apparatus, and more particularly to a method and apparatus suitable for application to processing such as cutting and dividing of a sample.

  As is well known, single crystal Si is produced by the Czochralski method (CZ method) or the like. According to this manufacturing method, a rod-shaped single crystal Si ingot having a cross-sectional diameter of 200 mmφ or more and a length of 1 m or more (a single crystal Si ingot is referred to as a “silicon ingot”) is produced. In this CZ method, as is well known, polycrystalline silicon melted in a quartz crucible is adjusted to a temperature suitable for single crystal growth, and a single crystal seed crystal is immersed in the melt. Dislocation occurs at this time, but it is made dislocation-free by necking for dislocation-free growth, gradually increasing the diameter while controlling the pulling rate of the seed crystal and the melt temperature, and a shoulder is formed, which is desired. When the diameter is formed, a straight body portion having a constant diameter is formed, and an inverse conical tail portion is formed while gradually reducing the diameter, thereby completing the lifting.

  In the slicing process, a hard and brittle silicon ingot is cut with a slicing machine to produce a thin wafer. Alternatively, as the rotating thin blade (for example, the blade has a thickness of 10 to several tens of μm), the inner peripheral blade is cut by the inner peripheral blade and the outer peripheral blade is cut by the outer peripheral blade. The wafer is then subjected to rough surface polishing (lapping) and mirror polishing (polishing).

  In a substantially cylindrical silicon ingot that is a base material of a semiconductor wafer, when the height direction of the cylinder is the z axis and the two axes that define the plane perpendicular to the z axis are the x and y axes, the vertical direction is the z axis. A single crystal is produced so that the lattice plane (001) plane of the single crystal coincides with the flat surface, and the (100) plane is cut (cut) on the cylindrical side surface. The surface of a semiconductor wafer made of single crystal silicon is a (001) plane (usually used in the (001) plane in many cases). In this case, a number of silicon ingots 10 are cut in a direction perpendicular to the z-axis to produce a substantially disk-shaped wafer. The (100) plane is cut out, and the cut out plane is also called an orientation flat.

  When cutting silicon ingots into wafers, use a wire saw (or inner peripheral cutting machine, outer peripheral cutting machine, ingot rotary cutting machine, horizontal type, vertical type etc.) Cutting margin and thickness are required to some extent. For this reason, the blade of a wire saw is made thin (width 0.2 mm-1.0 mm), and the cutting margin is shortened. In order to cut at high speed, the thin plate needs to have a certain thickness (0.3 mm to 1.0 mm). The wire saw is not a reciprocating motion but a one-way motion.

  For example, from a silicon ingot having a length of 1 m, silicon wafers of 500 pieces (with cutting margin = 1.0 mm and thickness = 1.0 mm) to 2,000 pieces (with cutting margin = 0.2 mm and thickness = 0.3 mm) Is disconnected. It takes a long time to cut the wafer. For example, it takes about 8 hours to cut about 300 wafers.

  An analysis area including semiconductor elements on the substrate is determined, a straight line passing through the analysis area is assumed, a laser beam is irradiated to the position of the straight line, a damaged portion is formed on the substrate, and a force is applied to any part of the substrate. In addition, a substrate cutting method in which the substrate is broken is known (for example, Patent Document 1).

  Also, irradiate the cut surface of the oxide single crystal substrate with a short pulse laser, heat the oxide single crystal substrate on the cut surface, and sublimate and remove the oxide single crystal substrate to cut the oxide single crystal substrate. There is also known a cutting method in which a groove is formed on the planned surface and the groove bottom is stored at the same time, and the oxide single crystal substrate is cleaved along the planned cutting surface by the thermal stress generated at the bottom of the stored groove (for example, a patent) Reference 2). Patent Document 2 explains the mutual relationship among laser energy absorption, heating (thermal stress), melting / sublimation, and removal as a laser processing mechanism, and also explains that thermal stress is controlled by controlling the pulse width. Yes.

  In semiconductor technology, various techniques for preventing misalignment due to charge-up in a processing process using a charged particle beam have been conventionally known (for example, Patent Documents 3 and 4).

JP 2000-216114 A (first and second pages, FIG. 3) JP-A-11-224865 (first and second pages, FIG. 3) JP 2002-57151 A (first page) Japanese Patent Laid-Open No. 11-154479 (FIG. 1) M. Neuberger and S. J. Welles, Silicon Data Sheet DS-162. 17 (Oct. 1969)

  By the way, the conventional cutting method has problems that a cutting margin is required, a surface treatment is required for the surface roughness after cutting, and a cutting time is required. Moreover, it is difficult to cut SiC, diamond, sapphire, and the like.

  Accordingly, an object of the present invention is to provide an apparatus and a method for facilitating cutting and dividing of a workpiece by irradiation with a processing beam.

  Another object of the present invention is to provide a method and an apparatus for improving the processing accuracy of a cut surface and a cut surface while suppressing and reducing an increase in processing time.

  Still another object of the present invention is to provide a method and an apparatus capable of dividing a workpiece into a plurality of dies with high machining accuracy.

  The present invention that achieves the above-described object provides a method for irradiating a processing beam in a cutting / dividing direction of a workpiece to cut / divide a sample. It arrange | positions so that the thermal stress which arises in the said sample with this trace may not be relieved.

  According to the present invention, the fixing jig is arranged on the opposite side along the direction orthogonal to the tracing direction of the machining beam (the cutting / dividing direction of the workpiece) and parallel to the cutting / dividing direction of the workpiece. Fixing jigs are arranged on the opposite sides while maintaining a predetermined gap. According to the present invention, such a configuration easily causes the workpiece to crack.

  According to the present invention, the surface opposite to the semiconductor element formation surface of the single crystal wafer is divided by irradiation with the processing beam.

  According to the present invention, a mask pattern is formed on a semiconductor element formation surface of a single crystal wafer, and the opening is divided by irradiation with a processing beam.

  According to the present invention, the processing beam is one of an electron beam, a laser beam, and an ion beam. The laser beam is a short pulse laser.

  According to the present invention, the sample is grounded to the charged beam to prevent charging.

  According to the present invention, the cylindrical lens is used so that the focal point of the processing beam is linear on the sample.

  According to the present invention, the laser beam may be guided by an optical fiber and irradiated on the sample surface in a linear manner in the cutting / dividing direction.

  According to the present invention, the laser beam may be deflected by an acousto-optic device, guided by an optical fiber, and irradiated on the sample surface in a linear manner in the cutting / dividing direction.

  According to the present invention, after performing laser ablation, cutting with a processing beam is performed.

  According to the present invention, the work fixture fixing jig is arranged at a position where the thermal stress is not relieved, thereby facilitating cutting / dividing by the thermal stress generated by the irradiation of the processing beam and cutting / dividing. Time has been shortened.

  Further, according to the present invention, the cutting / dividing of the semiconductor wafer is facilitated, and cutting by cleaving or the like is performed, so that the cutting allowance by a saw or the like is eliminated, and the cutting accuracy of the cutting / dividing surface can be improved. it can.

  The best mode for carrying out the present invention will be described. In a method for cutting / dividing a workpiece (sample) by scanning the processing beam in the cutting direction, a fixing jig for supporting and fixing the sample is heat generated in the sample along with the trace of the processing beam. Place in a position that does not relieve stress. Fixing jigs (102 and 103 in FIG. 5) are arranged on opposite sides along the direction orthogonal to the tracing direction of the processing beam, and a predetermined gap is maintained on the opposite sides parallel to the cutting / dividing direction of the sample. The fixing jigs (104, 105) are arranged.

  An embodiment of the apparatus according to the present invention comprises means for outputting a machining beam (see FIG. 1) and a sample stage (101 in FIG. 5) on which a sample is arranged, and the machining beam is placed on the surface to be machined. In a processing apparatus that scans / divides a sample by scanning in the cutting / dividing direction, the sample is placed on a sample stage (101) at a position that does not relieve thermal stress generated in the sample due to scanning of the processing beam. And a plurality of fixing jigs for supporting and fixing the sample. More specifically, the first and second fixing jigs (102 and 103 in FIG. 5) disposed in contact with and opposed to opposite sides in the direction orthogonal to the trace direction of the processing beam, and the sample (100) 3rd and 4th fixing jigs (104 and 105 in FIG. 5) which are arranged to face each other with a predetermined gap with respect to the opposite side parallel to the trace direction (cutting / dividing method) of the processing beam. It has.

  In one embodiment of the present invention, the sample is a single crystal silicon wafer, and the surface opposite to the single crystal wafer semiconductor element formation surface is irradiated with the processing beam and divided.

  Alternatively, the sample is at least one of gallium arsenide (GaAs), silicon carbide (SiC), diamond, sapphire, and GaN.

  In one embodiment of the present invention, a mask pattern may be provided on a semiconductor element formation surface of a single crystal wafer, and the opening of the mask may be irradiated with the processing beam to be divided.

  In one embodiment of the present invention, the processing beam is one of an electron beam, a laser beam, and an ion beam. In one embodiment of the present invention, the processing beam is a pulsed beam. Thermal stress is controlled.

  In one embodiment of the present invention, a sample stage (for example, placed on an XY stage) is set at a ground potential to prevent the sample from being charged by the processing beam made of charged particles such as an electron beam.

  In one embodiment of the present invention, the single crystal material is cleaved (including cleaving) by controlling the electron beam to reciprocate on the plane of the sample at a predetermined speed (scanning frequency: 5 kHz, for example).

  Alternatively, in another embodiment of the present invention, the processing beam is incident, and the output beam is provided with a cylindrical lens (301 in FIG. 11) that is focused on the sample.

  In another embodiment of the present invention, there is provided an optical fiber for guiding a laser beam that forms the processing beam, and the laser beam is irradiated linearly in the cutting / dividing direction on the surface of the workpiece. It is good.

  In the present invention, an acousto-optic device that inputs, deflects, and outputs a laser beam that forms the machining beam is provided, and the laser beam from the acousto-optic device is cut / divided in a plane on the workpiece. It is good also as a structure (refer FIG. 13) irradiated linearly.

  Embodiments of the present invention will be described with reference to the drawings. A method for cleaving (breaking) a single crystal material with an electron beam according to this embodiment will be described. As shown in FIG. 1, an experiment was conducted to break a single crystal of silicon, silicon carbide (SiC), sapphire, etc. (including not only cutting using cleaving etc., but also in general) using an electron beam. Electrons are accelerated from the cathode 201 by the voltage applied to the anode 202 and jump out into the vacuum, and the beam is focused by the focusing coil 204 so as to have a focus, and the deflection coil 205 is controlled to guide the electron beam to a required position. The

As experimental conditions,
Electron beam energy: 60 keV
Beam swing width: 16mm
Frequency: 5 kHz (scanning frequency of the electron beam)
In this way, the electron beam is scanned in the cutting / dividing direction at high speed.

  FIG. 2 schematically shows a cross-sectional view of a phenomenon that occurs when an electron beam is injected into a single crystal material. The depth to which the electron beam penetrates depends on the energy and material of the electron beam. For example, in silicon, the energy of the electron beam is about 22 microns when the energy is 60 keV, and about 200 microns when the energy is 150 keV. The width of the electron beam from which a large output current can be obtained is about 100 to 300 microns in the present experimental apparatus, and the energy of the electron beam is 60 keV, so that the energy of the electron beam is wide and shallow. Is absorbed into the silicon. According to the computer simulation, since the temperature distribution is flattened by heat conduction in a time of several tens of ms, a portion having a high temperature is generated in both the depth direction and the width direction about several times the width of the electron beam. Then, the temperature of that part rises. For this reason, the said part expands thermally.

  Further, since the temperature distribution is not uniform, a large thermal stress is generated in the narrow width of the portion. FIG. 2 schematically shows this force as an expansion force. The distribution of thermal stress by computer simulation is three-dimensional, but FIG. 2 schematically shows an approximate state for simplicity.

  FIG. 2 is a cross-sectional view of an electron beam and a sample (sample: single crystal material). In the experiment, the beam is scanned at a high speed in a direction perpendicular to the paper surface. Therefore, the high temperature region spreads in the direction perpendicular to the paper surface, and the thermal stress is also distributed in that direction. For this reason, the sample is broken in the scanning direction of the beam.

  As shown in FIG. 2, it has been experimentally confirmed that when an electron beam is scanned at high speed, thermal stress acts on the cross section of the sample in the vertical direction along the scanning direction, and cracks such as cleavage occur. .

  If high-speed scanning (for example, scanning frequency: 5 kHz) of the electron beam is not performed, the temperature of the sample increases only in the portion where the electron beam strikes, and the sample does not break on the line.

  To perform the experiment, it is necessary to fix the sample (in this experiment, a single crystal wafer). In FIG. 3, the wafer sample 100 is fixed by being sandwiched between sample fixing jigs 102 and 103. The sample stage 101 is set to the ground potential. The electron beam is irradiated onto the paper surface while vibrating from side to side on the line at a high speed. The trace position 122 is indicated by a line in the figure. The sample 100 is irradiated with an electron beam by the electron beam generator shown in FIG.

  In the example shown in FIG. 4, the relative positions of the sample fixing jig and the sample 100 are the same, but the direction of the electron beam trace is different. Correspondingly, the sample 100 and the fixing jigs 102 and 103 are matched. And are arranged.

  It has been experimentally confirmed that both FIG. 3 and FIG. 4 break instantaneously along the trace line of the electron beam. In particular, it was confirmed that when the crystal axis and the electron beam trace were perfectly aligned, it was easy to break with a low electron current (low electron beam energy).

  However, even if the crystal axis and the electron beam trace are not perfectly aligned, it has been experimentally observed that the sample is cracked when the sample is thin to some extent.

  The arrangement of these two fixing jigs was compared. This will be described below.

  As shown in FIG. 3, when the sample 100 is fixed, the fixing jig receives the thermal stress (thermal stress generated in the sample by electron beam irradiation) that causes cracking. For this reason, even if cracked, the sample does not move.

  On the other hand, in FIG. 4, the direction of the thermal stress generated in the sample is not supported by the fixing jig. For this reason, when the sample 100 is irradiated with an electron beam, when it breaks, the internal energy and the bonding energy for forming the crystal are released, and the sample 100 breaks into two and flies left and right in the figure. This has been observed in experiments.

  Therefore, the difference due to the difference in the fixture was analyzed for the ease of cracking, such as how far the crystal (sample is a single crystal material) can be broken by reducing the current value of the electron beam. Then, when configured as shown in FIG. 3, the sample 100 certainly does not break and fly, but since the fixing jigs 102 and 103 are in contact with and supported by the sample 100, it is difficult to break. 4, it was found that it was easy to break.

  Therefore, it is preferable that the fragile structure is installed so that the thermal stress is not relieved as shown in FIG. Further, in order to prevent the broken sample pieces from flying, the fixing jigs 104 and 105 are opposed to each other at a predetermined distance from the side of the sample 100 by a small distance necessary for breaking. . Thereby, it is avoided that the broken sample jumps greatly, and it is easy to break. Thus, according to the present embodiment, when the sample 100 is broken, the position of the sample 100 can be prevented from changing greatly. Note that the sample 100 or the sample stage 101 is set to the ground potential in order to finally flow the electron beam current. Depending on the size of the sample 100 or the length of the cutting part, electron beam energy, etc., the upper surface of the sample 100 placed on the sample table 101 corresponds to the cutting / dividing line irradiated with the electron beam. Then, the sample member may be covered with a mask member provided with an opening, and a broken sample piece may be prevented from rebounding upward due to an impact or the like. Further, a shock absorbing buffer member may be provided on the sample facing surface side of the fixing jigs 104 and 105.

  By the way, recently, large silicon wafers exceeding 10 inches have been used. A large-diameter wafer can have a plurality of independent semiconductor integrated circuits (LSIs) formed on its polished surface at once. A production method is employed in which a plurality of independent LSIs are formed on one wafer at a time, and then a silicon wafer is cut for each LSI. In order to apply the present invention to this cutting, an electron beam is injected into the back surface opposite to the main surface on which the LSI circuit is manufactured. This is because there is a possibility of destroying the LSI by a high energy electron beam.

  In FIG. 6, an example in which an electron beam is implanted into the back surface 12 opposite to the semiconductor element forming surface (referred to as “main surface”) side in which the semiconductor element, wiring layer pattern, interlayer insulating film, and the like are incorporated. Show. In FIG. 6, further, in such a case, the back side 12 has a thin several micron wafer sheet 13 (adhesive resin tape for holding the wafer and the diced chips: used in the dicing process to the mounting process). Is pasted). The wafer sheet 13 is made of a material other than silicon such as a polymer material. This part also needs to be cut. In the cutting of the wafer sheet 13, first, the electron beam is scanned relatively slowly, and at the same time, the electron beam acceleration voltage is lowered. As a result, the electron beam is absorbed by the thin film, and the material (adhesive resin) is removed from the portion by scattering or the like. Then, a high-energy electron beam is implanted in accordance with the conditions for silicon cleavage. This completes the cutting.

  Also, when LSIs are incorporated on both sides, or when it is necessary to drive a beam from the LSI side, the part that is not exposed to the electron beam can be protected with epoxy resin and then the beam can be driven and cut. desirable. Epoxy resin is an insulator and it is difficult for current to flow. Of course, it may be covered with a sheet-like insulator.

  When it is necessary to cut the copper wiring on the wiring layer of the semiconductor integrated circuit, the electron beam conditions (acceleration voltage, current, irradiation time, scanning frequency, etc.) are adapted to the wiring material and the film thickness of the wiring layer. ) Is set, and the cutting portion is removed in advance by an electron beam welder or the like, and then the beam is struck in two or three stages in accordance with the cleavage conditions of silicon to perform cutting. As is well known, the electron beam welder can be operated under the above conditions as a surface treatment.

  Next, various beams for cleavage are compared. In the above embodiment, the explanation was made on the cleavage of silicon or the like by the electron beam used in the experiment.

  However, as described with reference to FIGS. 2A and 2B, a laser or ion beam may be used in the case where the process is applied to cracking a single crystal including cleavage (including an amorphous material such as glass). This will be described below.

  The motion of charged particles in matter loses its kinetic energy due to the interaction of matter with electrons and nuclei. Then, it obtains the necessary number of charges from the surrounding materials, becomes neutral, and finally stops.

  FIG. 7 schematically shows such a state. For the same energy, the electron range is much longer (100 times or more). In addition, light has an absorptance determined by the characteristics of the material. In order to cleave a thick sample, the beam needs to penetrate deeply into the material. This is because cleaving occurs, resulting in an image that breaks the material with deep nails.

  In fact, in an experiment using a material with a thick electron beam, it was observed that the sample was not broken and a part of the surface was broken. This is because the nail is shallow and only the shallow part is broken.

  Now, in order for the electron beam to penetrate deeply into the material, the energy (= acceleration voltage) of the electron beam needs to be high. Furthermore, it is important that the width of the electron beam is narrow in order to control the thin and accurate cracking. However, as shown in FIG. 7, since the electrons are extremely light, they are scattered with electrons and nuclei in the material, and their orbits are greatly changed.

  For this reason, as shown in FIG. 8, even if the spread due to thermal conduction is removed from the original electron beam width, the energy of electrons is absorbed in a wide range, and the temperature of the substance is increased. Therefore, the accuracy of the split position tends to be wider than the beam width.

  On the other hand, when a laser beam is used, a highly uniform material such as a single crystal does not scatter in a substance, and light travels straight. The distance varies depending on the wavelength and the material, and is expressed in a form using an absorption coefficient. Therefore, when the laser beam is perpendicularly incident on both surfaces, as shown in FIG. 9, the laser beam is originally absorbed in the material with the same width as the laser beam width, and the temperature of the portion increases. . Heat conduction is excluded. All lasers are pulsed. This is because even in experiments using an electron beam so far, a large temperature difference is caused by irradiating the beam (short pulse laser) in a pulsed manner, and this causes a crack. Therefore, it is considered that the accuracy of the split position is almost the same as the beam width, and the control is easier to perform than the electron beam. Furthermore, since the current electron beam power and laser beam power are comparable, almost the same effect can be obtained.

  In the case of an ion beam, since the range is extremely short at a normal acceleration voltage, the beam is localized only near the surface of the material and does not penetrate deeply. Measures such as greatly increasing the acceleration voltage are taken against cracking phenomena such as cleavage.

  Next, the light transmittance of various materials will be described. FIG. 10 shows the light transmittance for various materials (spinel, sapphire, magnesium fluoride, silicon) for a thickness of 2 mm. Si has a transmittance of 55% for a thickness of 2 mm from a wavelength of 1.1 microns to 6.5 microns.

Therefore, the absorption coefficient α is
α = - (1/2) ln ( 0.55) = 0.298nm -1 ... (1)
This indicates that light penetrates approximately 2-3 mm in the infrared region. Although it is an amount related to the range of charged particles such as electrons, the electron energy corresponds to about 1.5 MeV compared to the electron range, which corresponds to the injection of an electron beam with a high energy density.

  In the experiment, it is assumed that the relationship between the electron range and the thickness of the Si wafer to be broken is about 100 times. Therefore, considering the penetration thickness of 2-3 mm, there is a possibility that 200 to 300 mm of Si can be broken. There is. Each material such as SiC, sapphire, GaAs, and GaN absorbs light significantly. Therefore, the optimum light wavelength is used as the sample material. This is due to the following reason. If light absorption is too large, energy is absorbed only near the surface and does not result in significant thermal stress to break the sample. On the other hand, if the light absorption is too small, the temperature of the entire sample in the portion through which the light passes increases, so that the thermal stress is reduced.

  Next, the focus of the laser beam in the present embodiment will be described. FIG. 11 is a schematic diagram for explaining the focal structure and cutting direction of a laser beam. In the embodiment, as shown in FIG. 1, in the electron beam cutting experiment, the electron beam is vibrated at high speed in the cutting direction. Since the focal point of the electron beam is a spot (spot), the electron beam is reciprocated in the cutting direction. As a result, the temperature was increased substantially uniformly along the planned cutting line.

  When the processing beam is a laser beam, the focal point on the sample surface can be made linear by using an optical system such as the cylindrical lens 301. For this reason, it is not necessary to vibrate (reciprocate) the beam at high speed. Of course, depending on the type of beam, an optical element (such as a mirror) may be used to vibrate at high speed. In the example shown in FIG. 11, one of the lenses 301 is shown, but it is preferable to adjust the focal length depending on the thickness of the sample. In this case, a plurality of cylindrical lenses 301 may be prepared to produce a lens system. The cross section of the laser beam is usually circular. For this, it is necessary to make the cross section rectangular using an aperture. Further, the laser oscillation itself may be changed from a circular shape to a rectangular shape. Specifically, in the case of a laser using a discharge such as a carbon dioxide laser, a method in which the discharge electrode is made rectangular and the mirror system for making the resonator is made rectangular, or in the case of a solid-state laser such as a YAG laser, an oscillation unit or an amplifier unit is used. The cross section of the laser beam becomes rectangular by making the crystal or glass used in the process into a rectangle.

  In addition, it is not necessary to vibrate the electron beam at high speed by making the structure of the electron gun straight and using a cylindrical lens system for the lens system of the electron beam on the way.

  Next, an optical guide for a laser beam will be described. FIG. 12 shows a known typical configuration of an apparatus for conducting laser welding by guiding a laser beam through an output fiber 403. Positioning with high accuracy is required, and a CCD camera 407 is provided, and the operator confirms the welding position on the display 410.

  FIG. 13 shows an apparatus for irradiating a single laser beam 521 divided into a plurality of pieces. A known configuration is used in which one laser beam is processed by being divided into a plurality of optical fibers.

  As shown in FIG. 11, in order to create a linear focal point, a beam may be divided into a plurality of beams and guided by an optical fiber, and the beams may be arranged and irradiated in a linear shape.

  Further, as shown in FIG. 13, the laser beam 521 is divided into a plurality of beams by a known acousto-optic modulator (modulator) 501, deflected by a known acousto-optic deflector (deflector) 502, and linearized on the sample surface. You may make it irradiate. Note that the position accuracy of these known devices is about 0.5 microns, and the current devices can sufficiently perform their functions. Also known is a device in which a plurality of lasers are arranged in a line and a laser beam is oscillated in a line without using an optical system or a modulator.

  FIG. 14 shows laser beam ablation. As is well known, ablation is a phenomenon in which when a sample surface is irradiated with a beam with a high energy density, the material irradiated with the beam explodes as a fragment with a large energy, and the material surface melts and partially gasses. In some cases, it becomes plasma and scatters. 14A to 14C are diagrams schematically showing the passage of time. FIG. 14A shows the temperature of the irradiated portion 123 when the sample 100 is irradiated with the laser for a short time. Rises. FIG. 14B schematically shows a state in which the irradiated atoms on the surface of the sample are heated and scattered. FIG. 14C shows a state in which the surface atomic layer has disappeared. The laser irradiation time is within 1 second and is performed in a short time. Depending on the absorption coefficient of the laser beam, it is known that about tens of microns on the surface can be easily removed. As described with reference to FIG. 6 by cutting with an electron beam, when a surface such as a large-diameter silicon wafer is provided with a wiring such as copper or a plastic film, the portion is removed by laser ablation. Is done.

In the above, the method performed using the cutting | disconnection (cleaving) phenomenon (cleavage etc.) of the single crystal material and glass material using an electron beam and a laser beam was demonstrated. Compared to the conventional method using a “saw”,
・ Short cutting time
・ There is no cutting allowance,
-The surface roughness of the cut surface is excellent.
・ With no saw, the blade is not chipped or worn like a saw.
Therefore, it can be said that this is an innovative processing technology. As described above, almost the effect has been confirmed in experiments.

  A case where an electron beam is used and a case where a laser beam is used will be described. When an experiment to break a silicon single crystal using an electron beam is performed, it has been confirmed by experiments that the beam does not go to the target on the sample and that the beam sways. This is presumed that because the sample has high electrical insulation, the surface of the sample is charged, and the repulsive force caused by this causes the beam to deviate from the target position or sway, not straight. For this reason, a method is adopted in which a conductive material such as gold is applied to the sample surface, coated, or the electrode is brought close to the surface of the sample. In particular, it is very convenient to install a metal with a slit-shaped window near the sample surface, since the portion hidden in the window is protected from a high-energy electron beam.

  When a laser is used, the above charge charging phenomenon does not occur. However, since a plasma may be generated even when a laser beam is used, it is effective to install a metal protective plate having a slit-like window near the surface.

  Further, when cutting a thick material, it is necessary to insert a beam deeply. Depending on the material of the sample, a laser is effective. In Si, if light with a wavelength of several microns is used, the electron beam energy corresponds to 1.5 MeV, and it is quite technically difficult to obtain a current of several tens of mA at such a high voltage. The laser is easy to use.

  However, materials such as SiC, sapphire, and GaN, which are currently difficult to cut because they are harder than silicon, have high transmittance in the visible to infrared region, so it is necessary to select the laser wavelength well. is there. However, various optical elements that convert the laser wavelength are manufactured and sold, and it is preferable to change the wavelength according to the material.

  Although the present invention has been described with reference to the above-described embodiment, the present invention is not limited to the configuration of the above-described embodiment, and can be made by those skilled in the art within the scope of the principle of the present invention. Of course, various modifications and corrections are included.

  The present invention is suitable for application to cutting processing of SiC, sapphire, GaN, etc., as well as a cutting machine for cutting an ingot into a wafer, a dicing apparatus, a breaking apparatus that breaks along the groove and divides it into individual dies. Is done.

It is a figure which shows the structure of one Example of this invention. It is a figure explaining the phenomenon when an electron beam is irradiated to a single crystal material. It is a figure which shows an example of arrangement | positioning of a sample fixing jig. It is a figure which shows an example of arrangement | positioning of a sample fixing jig. It is a figure which shows an example of arrangement | positioning of the sample fixing jig by a present Example. It is a figure explaining a mode that a semiconductor wafer is cut. It is a figure which compares the various beams used for cleavage. It is a figure explaining the temperature rise by the electron beam irradiation to a single crystal material. It is a figure explaining the temperature rise by the laser beam irradiation to a single crystal material. It is a figure which shows the transmittance | permeability of the light (wavelength) of various materials. It is a figure explaining the focal structure of the laser beam by a present Example. It is a figure which shows the structure of a well-known laser fine welding apparatus. It is a figure which shows the structure of a well-known laser beam deflection | deviation. It is a figure explaining laser ablation.

Explanation of symbols

11 Silicon wafer (substrate)
12 Back surface 13 Wafer sheet 21 Electron beam 100 Sample 101 Sample stage 102, 103, 104, 105, 106 Fixing jig 201 Cathode 202 Anode 203 Electron beam 204 Focusing coil 205 Deflection coil 206 Sample 301 Cylindrical lens 401 Laser light source 402 Illumination light source 403 Optical fiber 404 Processing head 406 XY stage 407 CCD camera 408 Monitoring optical system 409 Image capturing device 410 Video (video) display 411 Work 501 Acoustic light modulator (modulator)
502 Acoustic light deflector 511 Sample 521 Laser beam

Claims (28)

In a processing method of a workpiece using a processing beam,
With respect to the opposite side of the workpiece, the first and second fixing jigs are arranged oppositely in contact with the opposite sides in the direction orthogonal to the trace direction of the processing beam, and the processing beam The third and fourth fixing jigs are arranged opposite to each other with a predetermined gap between the opposing sides in the direction parallel to the trace direction,
A processing method characterized by cutting / dividing the workpiece by irradiation of the processing beam in the trace direction .   2. The processing according to claim 1, wherein the workpiece is a single crystal wafer, and is divided by irradiating the processing beam on a surface opposite to a surface on which the single crystal wafer semiconductor element is formed. Method. The processing method according to claim 2 , wherein a mask pattern is formed on a semiconductor element formation surface of the single crystal wafer, and the processing beam is divided by irradiation with the processing beam.   The processing method according to claim 1, wherein the processing beam is one of an electron beam, a laser beam, and an ion beam.   The processing method according to claim 1, wherein the processing beam is a pulsed beam.   The processing method according to claim 1, wherein the workpiece is set to a ground potential and charging by the processing beam made of charged particles is prevented.   The processing method according to claim 1, wherein the processing beam is scanned so as to reciprocate on a plane of the workpiece at a predetermined speed.   The processing method according to claim 1, wherein the processing beam is controlled to be linear at an irradiation position where the processing beam is a focal point.   The processing method according to claim 1, wherein a cylindrical lens is used so that a focal point of the processing beam is linear on the workpiece.   2. The processing according to claim 1, wherein a laser beam forming the processing beam is guided by an optical fiber, and the laser beam is irradiated linearly in a cutting / dividing direction on the surface of the workpiece. Method.   2. The laser beam is irradiated linearly in a cutting / dividing direction on the surface of the workpiece by deflecting a plurality of laser beams forming the processing beam with an acousto-optic device. The processing method as described in.   2. The processing method according to claim 1, wherein after the ablation of the workpiece surface by laser irradiation, cutting by the processing beam irradiation is performed.   The processing method according to claim 1, wherein the workpiece is cut by cleavage.   The workpiece is at least one of single crystal silicon (Si), gallium arsenide (GaAs), silicon carbide (SiC), diamond, sapphire, and GaN. Processing method. A conductive member is provided on the surface of the workpiece,
The conductive member is grounded;
The processing method according to claim 1, wherein a charge on the surface of the workpiece is discharged and an electron beam is irradiated. Place a conductive mask on the surface of the workpiece,
The mask is grounded;
Discharging the surface of the workpiece,
The processing method according to claim 1, wherein a processing beam is irradiated from the mask window. A device for outputting a processing beam for irradiating a workpiece;
A pedestal for placing the workpiece,
An apparatus for cutting / dividing the workpiece by irradiating the processing beam in a trace direction that forms a cutting / dividing direction of the workpiece,
On the table, with respect to the opposite side of the workpiece, first and second fixing jigs disposed opposite to each other in contact with opposite sides in a direction orthogonal to the trace direction of the processing beam;
Third and fourth fixing jigs arranged opposite to each other with a predetermined gap between opposite sides of the processing beam in a direction parallel to the trace direction;
A processing apparatus characterized by comprising: 18. The processing according to claim 17 , wherein the workpiece is a single crystal wafer, and the surface opposite to the surface on which the single crystal wafer semiconductor element is formed is irradiated with the processing beam to be divided. apparatus. The workpiece, a silicon single crystal (Si), gallium arsenide (GaAs), silicon carbide (SiC), diamond, sapphire, is at least one of GaN, claimed in claim 17, characterized in Processing equipment. 18. The processing apparatus according to claim 17 , wherein a mask pattern is provided on a semiconductor element forming surface of the single crystal wafer, and the opening of the mask is divided by irradiation with the processing beam. The processing apparatus according to claim 17 , wherein the processing beam is one of an electron beam, a laser beam, and an ion beam. The processing apparatus according to claim 17 , wherein the processing beam is a pulsed beam. The processing apparatus according to claim 17 , wherein the stage is set to a ground potential to prevent charging by the processing beam made of charged particles of the workpiece. The processing apparatus according to claim 17 , further comprising means for scanning the processing beam so as to reciprocate on a plane of the workpiece at a predetermined speed. 18. The processing apparatus according to claim 17 , further comprising means for controlling a beam path so that the processing beam is irradiated so as to be linear on the workpiece. The processing apparatus according to claim 17 , wherein the processing beam is incident, and the output beam includes a cylindrical lens having a focal point that is linear on the workpiece. An optical fiber that guides the laser beam forming the processing beam;
The processing apparatus according to claim 17 , wherein a laser beam is irradiated linearly in a cutting / dividing direction on a surface of the workpiece. An acousto-optic device that inputs and deflects and outputs a laser beam that forms the beam for processing is provided, and the laser beam from the acousto-optic device is linear on the surface of the workpiece in a cutting / dividing direction. The processing apparatus according to claim 17 , wherein the processing apparatus is irradiated.

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