METHOD OF CUTTING A SUBSTRATE, METHOD OF CUTTING A WAFER-LIKE OBJECT, AND METHOD OF MANUFACTURING A SEMICONDUCTOR DEVICE

• US 20110021004A1
• Filed: 10/01/2010
• Published: 01/27/2011
• Est. Priority Date: 09/13/2000
• Status: Active Grant

• Current Assignee: Hamamatsu Photonics KK
• Original Assignee: Hamamatsu Photonics KK
• Inventors: Wakuda, Toshimitsu, Uchiyama, Naoki, FUKUYO, Fumitsugu, Fukumitsu, Kenshi
• Granted Patent: US 8,946,589 B2
• Time in Patent Office: Days
• US Class Current: 438/463
• CPC Class Codes: B23K 20/023 Thermo-compression bonding
• CPC Class Codes: B23K 20/16 with interposition of special material to facilitate connection of the parts, e.g. material for absorbing or producing gas
• CPC Class Codes: B23K 20/233 without ferrous layer
• CPC Class Codes: B23K 20/26 Auxiliary equipment
• CPC Class Codes: B23K 2101/40 Semiconductor devices
• CPC Class Codes: B23K 2103/50 Inorganic material, e.g. metals, not provided for in B23K2103/02 – B23K2103/26
• CPC Class Codes: B23K 26/03 Observing, e.g. monitoring, the workpiece
• CPC Class Codes: B23K 26/032 using optical means
• CPC Class Codes: B23K 26/034 Observing the temperature of the workpiece
• CPC Class Codes: B23K 26/046 Automatically focusing the laser beam
• CPC Class Codes: B23K 26/0624 using ultrashort pulses, i.e. pulses of 1ns or less
• CPC Class Codes: B23K 26/066 by using masks
• CPC Class Codes: B23K 26/073 Shaping the laser spot
• CPC Class Codes: B23K 26/0853 Devices involving movement of the workpiece in at least in two axial directions, e.g. in a plane
• CPC Class Codes: B23K 26/16 Removal of by-products, e.g. particles or vapours produced during treatment of a workpiece by a fluid stream B23K26/142
• CPC Class Codes: B23K 26/364 for making a groove or trench, e.g. for scribing a break initiation groove
• CPC Class Codes: B23K 26/40 taking account of the properties of the material involved
• CPC Class Codes: B23K 26/53 for modifying or reforming the material inside the workpiece, e.g. for producing break initiation cracks
• CPC Class Codes: B28D 5/0011 with preliminary treatment, e.g. weakening by scoring
• CPC Class Codes: B65G 2249/04 Arrangements of vacuum systems or suction cups
• CPC Class Codes: C03B 33/023 : the sheet or ribbon being in a horizontal position
• CPC Class Codes: C03B 33/082 : using a focussed radiation beam, e.g. laser C03B33/0855 takes precedence
• CPC Class Codes: C03B 33/102 : involving a focussed radiation beam, e.g. lasers
• CPC Class Codes: C03C 23/0025 : by a laser beam
• CPC Class Codes: G02F 1/1368 : in which the switching element is a three-electrode device G02F1/136277 takes precedence
• CPC Class Codes: H01L 21/6836 : Wafer tapes, e.g. grinding or dicing support tapes adhesive tapes in general C09J7/20
• CPC Class Codes: H01L 21/78 : with subsequent division of the substrate into plural individual devices cutting to change the surface-physical characteristics or shape of semiconductor bodies H01L21/304
• CPC Class Codes: H01L 2221/68327 : used during dicing or grinding
• CPC Class Codes: Y02P 40/57 : Improving the yield, e-g- reduction of reject rates
• CPC Class Codes: Y10T 29/49144 : by metal fusion
• CPC Class Codes: Y10T 83/0341 : Processes

Abstract

A laser beam machining method and a laser beam machining device capable of cutting a work without producing a fusing and a cracking out of a predetermined cutting line on the surface of the work, wherein a pulse laser beam is radiated on the predetermined cut line on the surface of the work under the conditions causing a multiple photon absorption and with a condensed point aligned to the inside of the work, and a modified area is formed inside the work along the predetermined determined cut line by moving the condensed point along the predetermined cut line, whereby the work can be cut with a rather small force by cracking the work along the predetermined cut line starting from the modified area and, because the pulse laser beam radiated is not almost absorbed onto the surface of the work, the surface is not fused even if the modified area is formed.

Claims

1-44. -44. (canceled)

45. A method of cutting a substrate, comprising steps of:

irradiating a substrate with laser light comprising a pulsed laser light having a pulse width larger than 1 μ

s at a converging point within the substrate, so that the converging point of the pulsed laser light is positioned within the substrate and a peak power of the laser light at the converging point is not less than 1×

10⁸ (W/cm²), in order to form a modified spot within the substrate at the converging point; and

performing the irradiating step at multiple locations along a line along which the substrate is to be cut in order to form a plurality of non-overlapping modified spots within the substrate at converging points of the pulsed laser light, respectively, without melting a pulsed laser light incident surface of the substrate, wherein the modified spots make up a modified region formed only within the substrate which functions as a starting point for cutting the substrate along the line along which the substrate is to be cut,

wherein the modified spots are formed intermittently and in alignment along the line along which the substrate is to be cut, the starting point is formed in the substrate only by the laser irradiation converging within the substrate, and a crack is generated from the modified region functioning as the starting point for cutting and grown from the starting point so that the crack reaches to a front and back surface of the substrate and the substrate is thereby cut.

48. The method according to claim 45, wherein each modified spot is a crack spot and the modified region is a crack region.

50. The method according to claim 45, wherein each modified spot is a molten processed spot and the modified region is a molten processed region.

52. The method according to claim 45, wherein each modified spot is a refractive index change spot and the modified region is a refractive index change region.

56. The method according to claim 45, wherein a plurality of modified regions are formed along each of first lines along which the substrate is to be cut, a plurality of regions are formed along each of second lines along which the substrate is to be cut, the second lines crossing the first lines, and after formation of the modified regions has been performed, the substrate is cut into at least one piece having a chip shape.

46. A method of cutting a substrate, the method comprising steps of:

irradiating a substrate with a laser light comprising a pulsed laser light having a pulse width larger than 1 μ

s at a converging point within the substrate, so that the converging point of the pulsed laser light is positioned within the substrate and a peak power of the laser light at the converging point is not less than 1×

10⁸ (W/cm²), in order to form a modified spot within the substrate at the converging point; and

performing the irradiating step at multiple locations along a line along which the substrate is to be cut in order to form a plurality of crack spots so that the crack spots are aligned along the line along which the substrate is to be cut and spaced from a pulsed laser light incident surface of the substrate by a predetermined distance and a region in which multi-photon absorption is generated by the irradiation of the pulsed laser light is not overlapped with a pre-formed crack spot to form a modified region functioning as a starting point for cutting the substrate without melting the laser light incident surface of the substrate only within the substrate;

wherein the starting point is formed in the substrate only by the laser irradiation converging within the substrate, and a crack is generated from the modified region functioning as the starting point for cutting and grown from the starting point so that the crack reaches to a front and back surface of the substrate and the substrate is thereby cut.

54. The method according to claim 46, wherein a plurality of modified regions are formed along each of first lines along which the substrate is to be cut, a plurality of regions are formed along each of second lines along which the substrate is to be cut, the second lines crossing the first lines, and after formation of the modified regions has been performed, the substrate is cut into at least one piece having a chip shape.

47. A method of cutting a wafer-like object, the method comprising steps of:

irradiating the object with laser light comprising a pulsed laser light having a pulse width larger than 1 μ

s at a converging point within the object, so that the converging point of the pulsed laser light is positioned within the object and a peak power of the laser light at the converging point is not less than 1×

10⁸ (W/cm²), wherein the irradiating step is performed at multiple locations in order to form a plurality of modified spots at converging points of the pulsed laser light along a line along which the object is to be cut in order to form a modified region made up of the modified spots which functions as a starting point for cutting the object;

wherein the modified spots are intermittently formed along the line along which the object is to be cut within the object by making pitch between adjacent modified spots measured along the line along which the object is to be cut in a cross section substantially perpendicular to a thickness direction of the object substantially equal to or larger than a size of a modified spot measured along the line along which the object is to be cut, in order to cut the object only with the modified region functioning as the starting point for cutting the object.

49. The method according to claim 47, wherein each modified spot is a crack spot and the modified region is a crack region.

51. The method according to claim 47, wherein each modified spot is a molten processed spot and the modified region is a molten processed region.

53. The method according to claim 47, wherein each modified spot is a refractive index change spot and the modified region is a refractive index change region.

55. The method according to claim 47, wherein a plurality of modified regions are formed along each of first lines along which the substrate is to be cut, a plurality of regions are formed along each of second lines along which the substrate is to be cut the second lines crossing the first lines, and after formation of the modified regions has been performed, the substrate is cut into at least one piece having a chip shape.

57. A method of manufacturing a semiconductor device formed using a substrate cutting method, the manufacturing method comprising the steps of:

irradiating a substrate with laser light comprising a pulsed laser light having a pulse width larger than 1 μ

s at a converging point within the substrate, so that the converging point of the pulsed laser light is positioned within the substrate and a peak power of the laser light at the converging point is not less than 1×

10⁸ (W/cm²) in order to form a modified spot within the substrate at the converging point; and

performing the irradiating step at multiple locations along a line along which the substrate is to be cut to form a plurality of non-overlapping modified spots within the substrate at converging points of the pulsed laser light, respectively, without melting a pulsed laser light incident surface of the substrate, wherein the modified spots make up a modified region which functions as a starting point for cutting the substrate along the line along which the substrate is to be cut;

wherein the modified spots are formed intermittently and in alignment along the line along which the substrate is to be cut, the starting point is formed in the substrate only by the laser irradiation converging within the substrate, and a crack is generated from the modified region functioning as the starting point for cutting and grown from the starting point so that the crack reaches to a front and back surface of the substrate and the substrate is thereby cut in order to provide at least one manufactured semiconductor device.

59. The method according to claim 57, wherein each modified spot is a molten processed spot and the modified region is a molten processed region.

62. The method according to claim 57, wherein a plurality of modified regions are formed along each of first lines along which the substrate is to be cut, a plurality of regions are formed along each of second lines along which the substrate is to be cut, the second lines crossing the first lines, and after formation of the modified regions has been performed, the substrate is cut into at least one piece having a chip shape.

58. A method of manufacturing a semiconductor device formed using a substrate cutting method, the manufacturing method comprising the steps of:

irradiating a substrate with laser light comprising a pulsed laser light having a pulse width larger than 1 μ

s at a converging point within the substrate, so that the converging point of the pulsed laser light is positioned within the substrate and a peak power of the laser light at the converging point is not less than 1×

10⁸ (W/cm²), wherein the irradiating step is performed a multiple locations in order to form a plurality of modified spots at converging points of the pulsed laser light along a line along which the object is to be cut in order to form a modified region made up of the modified spots which functions as a starting point for cutting the object;

wherein the modified spots are intermittently formed along the line along which the object is to be cut within the object by making pitch between adjacent modified spots measured along the line along which the object is to be cut in a cross section substantially perpendicular to a thickness direction of the object substantially equal to or larger than a size of a modified spot measured along the line along which the object is to be cut, in order to cut the object only with the modified region functioning as the starting point for cutting the object so that the substrate is cut in order to provide at least one manufactured semiconductor device.

60. The method according to claim 58, wherein each modified spot is a molten processed spot and the modified region is a molten processed region.

61. The method according to claim 58, wherein a plurality of modified regions are formed along each of first lines along which the substrate is to be cut, a plurality of regions are formed along each of second lines along which the substrate is to be cut, the second lines crossing the first lines, and after formation of the modified regions has been performed, the substrate is cut into at least one piece having a chip shape.