Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
  • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
  • H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
  • H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table or AIIIBV compounds with or without impurities, e.g. doping materials
  • H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
  • H01L21/70—Manufacture or treatment of devices consisting of a plurality of solid state components formed in or on a common substrate or of parts thereof; Manufacture of integrated circuit devices or of parts thereof
  • H01L21/77—Manufacture or treatment of devices consisting of a plurality of solid state components or integrated circuits formed in, or on, a common substrate
  • H01L21/78—Manufacture or treatment of devices consisting of a plurality of solid state components or integrated circuits formed in, or on, a common substrate with subsequent division of the substrate into plural individual devices
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
  • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
  • B23K26/16—Removal of by-products, e.g. particles or vapours produced during treatment of a workpiece
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
  • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
  • B23K26/36—Removing material
  • B23K26/38—Removing material by boring or cutting
  • B23K26/382—Removing material by boring or cutting by boring
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
  • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
  • B23K26/36—Removing material
  • B23K26/40—Removing material taking account of the properties of the material involved
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
  • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
  • B23K26/50—Working by transmitting the laser beam through or within the workpiece
  • B23K26/53—Working by transmitting the laser beam through or within the workpiece for modifying or reforming the material inside the workpiece, e.g. for producing break initiation cracks
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B28—WORKING CEMENT, CLAY, OR STONE
  • B28D—WORKING STONE OR STONE-LIKE MATERIALS
  • B28D1/00—Working stone or stone-like materials, e.g. brick, concrete or glass, not provided for elsewhere; Machines, devices, tools therefor
  • B28D1/22—Working stone or stone-like materials, e.g. brick, concrete or glass, not provided for elsewhere; Machines, devices, tools therefor by cutting, e.g. incising
  • B28D1/221—Working stone or stone-like materials, e.g. brick, concrete or glass, not provided for elsewhere; Machines, devices, tools therefor by cutting, e.g. incising by thermic methods
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B28—WORKING CEMENT, CLAY, OR STONE
  • B28D—WORKING STONE OR STONE-LIKE MATERIALS
  • B28D5/00—Fine working of gems, jewels, crystals, e.g. of semiconductor material; apparatus or devices therefor
  • B28D5/0005—Fine working of gems, jewels, crystals, e.g. of semiconductor material; apparatus or devices therefor by breaking, e.g. dicing
  • B28D5/0011—Fine working of gems, jewels, crystals, e.g. of semiconductor material; apparatus or devices therefor by breaking, e.g. dicing with preliminary treatment, e.g. weakening by scoring
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
  • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
  • H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
  • H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table or AIIIBV compounds with or without impurities, e.g. doping materials
  • H01L21/26—Bombardment with radiation
  • H01L21/263—Bombardment with radiation with high-energy radiation
  • H01L21/268—Bombardment with radiation with high-energy radiation using electromagnetic radiation, e.g. laser radiation
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
  • B23K2101/00—Articles made by soldering, welding or cutting
  • B23K2101/36—Electric or electronic devices
  • B23K2101/40—Semiconductor devices
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
  • B23K2103/00—Materials to be soldered, welded or cut
  • B23K2103/50—Inorganic material, e.g. metals, not provided for in B23K2103/02 – B23K2103/26

Definitions

• the present invention relates to a laser calorie method for cutting a plate-like workpiece along a planned cutting line.
• Patent Document 1 JP-A-2005-129607
• An object of the present invention is to provide a laser processing method capable of performing the following.
• the laser processing method according to the present invention is intended to cut a processing target line by irradiating a laser beam with a converging point inside the plate-shaped processing target. And forming a modified region as a starting point of cutting inside the workpiece along
• the modified region that is the starting point of the cutting is configured to irradiate laser light with the focusing point inside the object to be processed, thereby absorbing multiphoton absorption and other light absorption inside the object to be processed. It is formed by generating.
• the material that forms the object to be processed means the material that forms the object to be processed or the substance that has formed the object to be processed, and specifically, the object to be processed in which the modified region is formed. And chips obtained by cutting an object to be processed, particles generated by the cutting surface force of the chip, and the like.
• a laser processing method includes a cutting start point along a planned cutting line of a workpiece by irradiating a laser beam with a converging point inside the plate-like workpiece. Forming a modified region to be formed inside the workpiece and applying stress to the workpiece through an elastic sheet, and processing along the planned cutting line using the modified region as a starting point for cutting.
• the workpiece in the step of separating the chips from each other, By applying stress to the workpiece through the sheet, the workpiece may be cut into chips along the planned cutting line using the modified region as a starting point for cutting.
• the object to be processed may include a semiconductor substrate, and the modified region may include a melt processing region.
• FIG. 1 is a plan view of an object to be processed in a laser cage by a laser cage method according to the present embodiment.
• FIG. 2 is a cross-sectional view taken along line II-II of the cache object shown in FIG.
• FIG. 3 is a plan view of an object to be processed after laser processing by the laser processing method according to the present embodiment.
• FIG. 4 is a cross-sectional view taken along line IV-IV of the workpiece shown in FIG.
• FIG. 5 is a cross-sectional view taken along line V—V of the workpiece shown in FIG.
• FIG. 6 is a plan view of a workpiece to be cut by the laser processing method according to the present embodiment.
• FIG. 7 is a graph showing the relationship between the peak power density and the crack spot size in the laser processing method according to the present embodiment.
• FIG. 8 is a cross-sectional view of the object to be processed in the first step of the laser processing method according to the present embodiment.
• FIG. 9 is a cross-sectional view of an object to be processed in a second step of the laser processing method according to the present embodiment.
• FIG. 10 is a cross-sectional view of an object to be processed in a third step of the laser processing method according to the present embodiment.
• FIG. 11 is a cross-sectional view of an object to be processed in a fourth step of the laser processing method according to the present embodiment.
• FIG. 12 A part of the silicon wafer cut by the laser cage method according to the present embodiment.
• FIG. 13 is a graph showing the relationship between the wavelength of laser light and the internal transmittance of the silicon substrate in the laser processing method according to the present embodiment.
• FIG. 14 is a plan view of a workpiece to be processed by the laser processing method of the first embodiment.
• FIG. 15 is a partial sectional view taken along line XV—XV shown in FIG.
• FIG. 16 is a partial cross-sectional view of an object to be processed for explaining the laser processing method according to the first embodiment.
• (A) is a state in which an expanded tape is attached to the object to be processed, and (b) is an object to be processed. In this state, the laser beam is irradiated.
• FIG. 17 is a partial cross-sectional view of an object to be processed for explaining the laser processing method according to the first embodiment.
• FIG. 17 In this state, the knife edge is pressed through the wand tape.
• FIG. 18 is a partial cross-sectional view of an object to be processed for explaining the laser processing method according to the first embodiment, where the object to be processed is cut into semiconductor chips.
• FIG. 19 is a schematic diagram for explaining the principle that particles generated randomly from a cut surface of a semiconductor chip are scattered.
• FIG. 20 is a schematic diagram for explaining the principle that particles generated from a cut surface of a semiconductor chip fall due to their own weight.
• the absorption band gap of the material is optically transparent when the photon energy h v force S is smaller than E.
• the intensity of the laser beam is determined by the peak power density (WZcm 2 ) at the focal point of the laser beam.
• WZcm 2 peak power density
• multiphoton absorption occurs when the peak density is 1 X 10 8 (WZcm 2 ) or more.
• the peak power density is calculated by (energy per pulse of laser beam at the focal point) ⁇ (laser beam beam cross-sectional area X pulse width).
• the intensity of the laser beam is determined by the electric field intensity (WZcm 2 ) at the condensing point of the laser beam.
• a surface 3 of a wafer-like (plate-like) workpiece 1 has a scheduled cutting line 5 for cutting the workpiece 1.
• the planned cutting line 5 is a virtual line extending straight.
• the modified region 7 is irradiated with the laser beam L with the focusing point P aligned inside the workpiece 1 under the condition that multiphoton absorption occurs.
• the condensing point P is a part where the laser beam is condensed.
• the planned cutting line 5 is not limited to a straight line, but may be a curved line, or may be a line actually drawn on the workpiece 1 without being limited to a virtual line.
• the condensing point P is moved along the planned cutting line 5 by relatively moving the laser light L along the planned cutting line 5 (that is, in the direction of arrow A in FIG. 1). .
• the modified region 7 is formed inside the workpiece 1 along the planned cutting line 5, and the modified region 7 becomes the cutting start region 8.
• the cutting starting point region 8 means a region that becomes a starting point of cutting (cracking) when the workpiece 1 is cut.
• This cutting starting point region 8 may be formed by continuously forming the modified region 7 or may be formed by intermittently forming the modified region 7.
• the laser beam L is hardly absorbed by the surface 3 of the workpiece 1, so that the surface 3 of the workpiece 1 is not melted.
• the cutting start region 8 is formed inside the workpiece 1, cracks are likely to occur starting from the cutting start region 8, and as shown in FIG. Item 1 can be cut. Therefore, it is possible to cut the workpiece 1 that causes unnecessary cracks in the surface 3 of the workpiece 1 with high accuracy.
• the following two methods are conceivable for cutting the cache object 1 starting from the cutting start region 8. First, after the cutting start region 8 is formed, an artificial force is applied to the processing target 1, so that the processing target 1 is cracked and the processing target 1 is cut from the cutting start region 8. Is the case. This is, for example, cutting when the workpiece 1 is thick.
• the artificial force is applied, for example, by applying a bending stress or a shear stress to the workpiece 1 along the cutting start region 8 of the workpiece 1 or giving a temperature difference to the workpiece 1.
• the other is that by forming the cutting start region 8, it naturally cracks in the cross-sectional direction (thickness direction) of the workpiece 1 starting from the cutting start region 8, resulting in the processing target This is the case where object 1 is cut.
• the thickness of the workpiece 1 is small, this can be achieved by forming the cutting start region 8 by the modified region 7 in one row, and when the thickness of the workpiece 1 is large. This can be achieved by forming the cutting start region 8 by the modified region 7 formed in a plurality of rows in the thickness direction.
• the modified regions formed by multiphoton absorption include the following cases (1) to (3).
• the modified region is a crack region including one or more cracks
• the laser beam is irradiated under the condition that the electric field intensity at the focal point is 1 ⁇ 10 8 (WZcm 2 ) or more and the pulse width is 1 ⁇ s or less.
• the magnitude of the pulse width is a condition that allows a crack region to be formed only inside the workpiece without causing extra damage to the surface of the workpiece while causing multiphoton absorption.
• a phenomenon called optical damage due to multiphoton absorption occurs inside the workpiece.
• This optical damage induces thermal strain inside the workpiece, thereby forming a crack region inside the workpiece.
• the upper limit value of the electric field strength is, for example, 1 ⁇ 10 12 (W / cm 2 ).
• Pulse width is lns ⁇ 200 ns is preferred.
• the formation of the crack region by multiphoton absorption is described in, for example, “Inside of glass substrate by solid-state laser harmonics” on pages 23-28 of the 45th Laser Thermal Processing Workshop Proceedings (December 1998). It is described in “Marking”.
• the present inventor obtained the relationship between the electric field strength and the size of the crack by experiment.
• the experimental conditions are as follows.
• the laser beam quality is TEM, which is highly condensable and can be focused to the wavelength of the laser beam.
• FIG. 7 is a graph showing the results of the experiment.
• the horizontal axis is the peak power density. Since the laser beam is a pulsed laser beam, the electric field strength is expressed by the peak power density.
• the vertical axis shows the size of the crack part (crack spot) formed inside the workpiece by 1 pulse of laser light. Crack spots gather to form a crack region. The size of the crack spot is the size of the maximum length of the crack spot shape.
• the data indicated by the black circles in the graph is when the condenser lens (C) has a magnification of 100 and the numerical aperture (NA) is 0.80.
• the data indicated by white circles in the graph indicate that the magnification of the condenser lens (C) is 50 This is the case when the numerical aperture (NA) is 0.55. From the peak power density of about lO ⁇ WZcm 2 ), it can be seen that a crack spot is generated inside the cache object, and that the crack spot increases as the peak power density increases.
• FIG. 8 Under the condition that multiphoton absorption occurs, the condensing point P is aligned inside the workpiece 1 and the laser beam L is irradiated to form a crack region 9 along the planned cutting line.
• the crack region 9 is a region including one or more cracks.
• the crack region 9 thus formed becomes a cutting start region.
• the crack further grows starting from the crack region 9 (that is, starting from the cutting start region), and as shown in FIG.
• FIG. 11 when the workpiece 1 is cracked, the workpiece 1 is cut.
• a crack that reaches the front surface 3 and the back surface 21 of the workpiece 1 may grow naturally, or may grow when a force is applied to the workpiece 1.
• the focusing point is set inside the workpiece (eg, semiconductor material such as silicon) and the electric field strength at the focusing point is 1 X 10 8 (WZcm 2 ) or more and the pulse width is 1 ⁇ s or less.
• the laser beam is irradiated with.
• the inside of the workpiece is locally heated by multiphoton absorption.
• a melt processing region is formed inside the workpiece.
• the melt treatment region is a region once solidified after melting, a region in a molten state, or a region re-solidified from a molten state, and can also be referred to as a phase-changed region or a region where the crystal structure has changed.
• the melt-processed region can also be referred to as a region in which one structure is changed to another structure in a single crystal structure, an amorphous structure, or a polycrystalline structure.
• a region changed to a single crystal structural force amorphous structure a region changed from a single crystal structure to a polycrystalline structure, a region changed to a structure including a single crystal structural force amorphous structure and a polycrystalline structure.
• the melt processing region has, for example, an amorphous silicon structure.
• the upper limit value of the electric field strength is, for example, 1 ⁇ 10 12 (WZcm 2 ).
• the pulse width is preferably lns to 200 ns.
• the present inventor has experimentally confirmed that the melt processing region is formed inside the silicon wafer. confirmed.
• the experimental conditions are as follows.
• FIG. 12 is a view showing a photograph of a cross section of a part of a silicon wafer cut by a laser cage under the above conditions.
• a melt processing region 13 is formed inside the silicon wafer 11.
• the size in the thickness direction of the melt processing region 13 formed under the above conditions is about 100 ⁇ m.
• FIG. 13 is a graph showing the relationship between the wavelength of the laser beam and the transmittance inside the silicon substrate. However, the reflection component on the front side and the back side of the silicon substrate is removed, and the transmittance only inside is shown. The above relationship was shown for each of the silicon substrate thicknesses t of 50 ⁇ m, 100 ⁇ m, 200 ⁇ m, 500 ⁇ m, and 1000 ⁇ m.
• the thickness of the silicon substrate is 500 m or less, it is found that 80% or more of the laser light is transmitted inside the silicon substrate. Power. Since the thickness of the silicon wafer 11 shown in FIG. 12 is 350 m, the melt processing region 13 by multiphoton absorption is formed near the center of the silicon wafer 11, that is, at a portion of 175 m from the surface. In this case, the transmittance is 90% or more with reference to a silicon wafer having a thickness of 200 m. Therefore, the laser beam is hardly absorbed inside the silicon wafer 11, and almost all is transmitted.
• melt processing region 13 is formed by multiphoton absorption.
• the formation of the melt processing region by multiphoton absorption is, for example, “Evaluation of processing characteristics of silicon by picosecond pulse laser” on pages 72 to 73 of the 66th Annual Meeting Summary (April 2000). It is described in.
• a silicon wafer causes a crack to occur in the cross-sectional direction starting from a cutting start region formed by the melt processing region, and the crack reaches the front and back surfaces of the silicon wafer. , Resulting in disconnection.
• the cracks that reach the front and back surfaces of the silicon wafer may grow spontaneously or may grow when force is applied to the silicon wafer. Then, if the crack grows naturally on the front and back surfaces of the silicon wafer, the crack grows from the state where the melt processing area forming the cutting origin area is melted, and the cutting origin area In some cases, cracks grow when the solidified region is melted from the molten state.
• the melt processing region is formed only inside the silicon wafer, and the melt processing region is formed only inside the cut surface after cutting as shown in FIG.
• the formation of the melt-processed region may be caused not only by multiphoton absorption but also by other absorption effects.
• the focusing point inside the workpiece eg glass
• the pulse width is 1 X 10 8 (W / cm 2 ) or more and the pulse width is Ins or less.
• the energy due to photon absorption does not convert to thermal energy, and a permanent structural change such as ionic valence change, crystallization or polarization orientation is induced inside the workpiece, and a refractive index change region is formed.
• the upper limit value of the electric field strength is, for example, 1 ⁇ 10 12 (WZcm 2 ).
• the pulse width is preferably less than Ins, more preferably less than lps.
• the formation of the refractive index change region by multiphoton absorption is described in, for example, “Femtosecond Laser Irradiation in Glasses” on pages 105 to 111 of the 42nd Laser Thermal Processing Workshop Papers (November 1997). Photo-induced structure formation ”.
• the cases of (1) to (3) have been described as the modified regions.
• the cutting origin region is as follows. Once formed, the workpiece can be cut with a smaller force and with higher accuracy, starting from the cutting start region.
• the cutting origin region in the direction along the (111) plane (first cleavage plane) or the (110) plane (second cleavage plane). is preferably formed.
• the cutting start region in the direction along the (110) plane is preferable to form the cutting start region in the direction along the (110) plane.
• the field of a substrate having a hexagonal crystal structure such as sapphire (Al 2 O 3).
• the cutting origin region in the direction along the (1120) plane (8 planes) or (1100) plane (M plane) with the (0001) plane (C plane) as the main plane. .
• the direction in which the above-described cutting start region is to be formed (for example, the direction along the (111) plane in the single crystal silicon substrate) or! Is orthogonal to the direction in which the cutting start region is to be formed. If an orientation flat is formed on the substrate along the direction, it is possible to easily and accurately form the cutting start area along the direction in which the cutting start area is to be formed on the basis of the orientation flat. become.
• the workpiece 1 includes a silicon wafer (semiconductor substrate) 11 having a thickness of 625 ⁇ m and a plurality of functional elements 15 on the surface 3 of the silicon wafer 11. And a functional element layer 16 formed.
• the functional element 15 is formed by crystal growth, for example.
• the cache object 1 configured as described above is cut for each functional element 15 as follows. First, as shown in FIG. 16 (a), an expanded tape (sheet) 23 is attached to the back surface 21 of the silicon wafer 11. Subsequently, as shown in FIG. 16B, the workpiece 1 is fixed on a mounting table (not shown) of the laser processing apparatus with the functional element layer 16 facing upward. Then, the surface 3 of the silicon wafer 11 is used as a laser beam incident surface, the condensing point P is aligned inside the silicon wafer 11 and the laser beam L is irradiated, and it passes between adjacent functional elements 15 and 15 by the movement of the mounting table. The condensing P is scanned along the planned cutting line 5 (see the broken line in Fig. 14) set in a grid.
• the scanning of the condensing point P along the planned cutting line 5 is performed a plurality of times (for example, 19 times) on the single cutting planned line 5, but from the surface 3 where the converging point P is aligned.
• the back surface 21 side force is also formed in order, so that a plurality of rows of the melt processing regions 13 are formed one by one inside the silicon wafer 11 along the planned cutting line 5.
• the surface 3 on which the laser beam L is incident and the condensing point P of the laser beam L are formed when forming each melt treatment region 13. During this period, the melt processing region 13 does not exist.
• each melt processing region 13 can be reliably formed inside the silicon wafer 11 along the planned cutting line 5.
• cracks may occur from the melt treatment region 13 to the front surface or the back surface of the workpiece 1.
• cracks may be mixed in the melt processing region 13.
• the number of rows of the melt processing region 13 formed inside the silicon wafer 11 with respect to one line 5 to be cut varies depending on the thickness of the silicon wafer 11 and is limited to a plurality of rows. It may not be a single row.
• the soft X-ray irradiation type static eliminator is known as described in Japanese Patent No. 2951477 and Japanese Patent No. 2749202.
• a product name “PhotoIonizer” product number L9490 manufactured by Hamamatsu Photonics Co., Ltd.
• the forming substance (dissolving material) of the workpiece 1 is dissolved.
• Soft X-rays are applied to the processing object 1 in which the fusion treatment region 13 is formed, the semiconductor chip 25 obtained by cutting the processing object 1, and particles generated by the cutting surface force of the semiconductor chip 25). (See Fig. 17 (a), (b) and Fig. 18).
• particles generated from the cut surface of the semiconductor chip 25 obtained by cutting the workpiece 1 along the planned cutting line 5 from the melting processing region 13 as a starting point of cutting are not randomly scattered. It will fall onto the expanded tape 23. Therefore, according to the laser processing method of the first embodiment, it is possible to reliably prevent particles from adhering to the semiconductor chip 25 obtained by cutting the workpiece 1.
• the laser processing method according to the second embodiment includes a knife through the expanded tape 23 against the back surface 21 of the silicon wafer 11 in a state where the soft X-ray is irradiated and the expanded tape 23 is expanded. This is different from the laser processing method of the first embodiment in that the edge 41 is not pressed.
• the expanded tape 23 is attached to the back surface 21 of the silicon wafer 11. Then, as shown in FIG. 16 (b), the surface 3 of the silicon wafer 11 is used as the laser light incident surface, and the laser beam L is irradiated with the focusing point P inside the silicon wafer 11, and a plurality of rows are melted. The region 13 is formed inside the silicon wafer 11 along the cutting line 5.
• the number of particles in Tables 1 and 2 below is 19 rows in a silicon wafer 11 having a thickness of 625 ⁇ m and an outer diameter of 100 mm, with respect to one line 5 to be cut. This is a result of measurement using a particle of 2 m or more when the processing region 13 is formed and a semiconductor chip 25 of 2 mm ⁇ 2 mm is obtained.
• the present invention is not limited to the laser processing methods of the first and second embodiments described above.
• the workpiece 1 may be cut into a plurality of semiconductor chips 25.
• the laser beam L is irradiated with the condensing point P inside the silicon wafer 11, and after the melt processing region 13 is formed inside the silicon wafer 11 along the planned cutting line 5, it is processed by a heating means or the like.
• the force with the front surface 3 of the silicon wafer 11 as the laser light incident surface can be used with the back surface 21 of the silicon wafer 11 as the laser light incident surface.
• the workpiece 1 is cut into a plurality of semiconductor chips 25 as follows as an example. That is, a protective tape is attached to the surface of the functional element layer 16, and the protective tape holding the workpiece 1 is fixed to the mounting table of the laser processing apparatus in a state where the functional element layer 16 is protected by the protective tape.
• the laser beam L is irradiated with the condensing point P inside the silicon wafer 11 with the back surface 21 of the silicon wafer 11 as the laser beam incident surface, and the laser beam L is irradiated.
• a melt processing region 13 is formed inside the silicon wafer 11 along the line 5.
• the protective tape fixed to the mounting table is separated together with the workpiece 1.
• expand tape 23 is applied to the back surface 21 of the silicon wafer 11, the protective tape is peeled off from the surface of the functional element layer 16, and then the expanded material is irradiated with soft X-rays on the material to be processed 1.
• the tape 23 is expanded so that the workpiece 1 is cut along the scheduled cutting line 5 with the melt processing region 13 as a starting point of cutting, and a plurality of semiconductor chips 25 obtained by cutting are separated from each other.
• the forming material of the processing object 1 is formed.
• the material forming the workpiece 1 may be neutralized by some method, such as using a corona discharge type static eliminator.
• particles generated from the cut surface of the semiconductor chip 25 obtained by cutting the workpiece 1 along the planned cutting line 5 with the melt processing region 13 as the starting point of cutting are the workpiece 1 Since the static electricity is removed from the forming material force of the film, it will fall on the expanded tape 23 which does not scatter randomly. Accordingly, in this case as well, it is possible to reliably prevent particles from adhering to the semiconductor chip 25 obtained by cutting the workpiece 1.
• the melt processing region is formed inside the processing object such as the semiconductor material, but glass, piezoelectric material, etc.
• Other modified regions such as a crack region and a refractive index change region may be formed inside a workpiece made of the above material.

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• 2005
  • 2005-11-18 JP JP2005334734A patent/JP4237745B2/ja not_active Expired - Lifetime
• 2006
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