Abstract: A crystal wafer is produced from a hexagonal crystal ingot. A separation start point is formed by setting the focal point of a laser beam inside the ingot at a predetermined depth, which depth corresponds to the thickness of the wafer to be produced. The laser beam is applied to the upper surface of the ingot while relatively moving the focal point and the ingot to form a modified layer parallel to the upper surface of the ingot and cracks extending from the modified layer along a c-plane in the ingot, thus forming the separation start point. First the laser beam is scanned from a scanning start point to a scanning end point on the ingot. Then the laser beam is scanned from the scanning end point to the scanning start point. The first and second steps are alternately repeated to separate the cracks from the modified layer.

Abstract: A hexagonal single crystal wafer is produced from a hexagonal single crystal ingot. A separation start point is formed by setting a focal point of a laser beam inside the ingot at a predetermined depth from the upper surface of the ingot, which depth corresponds to a thickness of the wafer to be produced. The laser beam is applied to the upper surface of the ingot while relatively moving the focal point and the ingot to thereby form a modified layer parallel to the upper surface of the ingot and form cracks extending from the modified layer along a c-plane, thus forming a separation start point. The wafer is separated by immersing the ingot in water and then applying ultrasonic vibration to the ingot, thereby separating a plate-shaped member having a thickness corresponding to the thickness of the wafer from the ingot.

Abstract: A hexagonal single crystal wafer is produced from a hexagonal single crystal ingot. A separation start point is formed by setting a focal point of a laser beam inside the ingot at a predetermined depth from the upper surface of the ingot, which depth corresponds to the thickness of the wafer to be produced, and next applying the laser beam to the upper surface of the ingot while relatively moving the focal point and the ingot to thereby form a modified layer parallel to the upper surface of the ingot and form cracks extending from the modified layer along a c-plane, thus forming a separation start point. The focal point is indexed by relatively moving the focal point in the direction where an off angle is formed and the c-plane is inclined downward.

Abstract: A wafer producing method for producing a hexagonal single crystal wafer from a hexagonal single crystal ingot is disclosed. The wafer producing method includes a separation start point forming step of forming a modified layer parallel to the upper surface of the ingot and cracks extending from the modified layer to thereby form a separation start point in the ingot. The separation start point forming step includes a first separation start point forming step of setting the focal point of a laser beam at a first depth which is N times (N is an integer not less than 2) the depth corresponding to the thickness of the wafer from the upper surface of the ingot and next applying the laser beam to the ingot to thereby form a first separation start point composed of a first modified layer and first cracks extending therefrom.

Abstract: A wafer producing method for producing a hexagonal single crystal wafer from a hexagonal single crystal ingot includes a separation start point forming step of setting the focal point of a laser beam inside the ingot at a predetermined depth from the upper surface of the ingot, which depth corresponds to the thickness of the wafer to be produced, and next applying the laser beam to the upper surface of the ingot while relatively moving the focal point and the ingot to thereby form a modified layer parallel to the upper surface of the ingot and cracks extending from the modified layer, thus forming a separation start point. In the separation start point forming step, the laser beam is applied to the ingot plural times with the focal point of the laser beam set at the modified layer previously formed, thereby separating the cracks from the modified layer.

Abstract: A wafer producing method produces a hexagonal single crystal wafer from a hexagonal single crystal ingot. The method includes a separation start point forming step of setting the focal point of a laser beam to the inside of the ingot at a predetermined depth from the upper surface of the ingot, which depth corresponds to the thickness of the wafer to be produced, and next applying the laser beam to the upper surface of the ingot while relatively moving the focal point and the ingot to thereby form a modified layer parallel to the upper surface of the ingot and cracks extending from the modified layer, thus forming a separation start point. The separation start point forming step includes an indexing step of relatively moving the focal point in a direction of formation of an off angle to thereby index the focal point by a predetermined index amount.

Abstract: A hexagonal single crystal wafer is produced from a hexagonal single crystal ingot. The wafer producing method includes a separation start point forming step of setting the focal point of a laser beam to the inside of the ingot at a predetermined depth from the upper surface of the ingot, which depth corresponds to the thickness of the wafer to be produced, and next applying the laser beam to the upper surface of the ingot while relatively moving the focal point and the ingot to thereby form a modified layer parallel to the upper surface of the ingot and cracks extending from the modified layer, thus forming a separation start point. A plate-shaped member having a thickness corresponding to the thickness of the wafer is separated from the ingot at the separation start point after performing the separation start point forming step, thus producing the wafer from the ingot.

Abstract: A wafer processing method divides a wafer into a plurality of individual devices along a plurality of crossing division lines formed on the front side of the wafer. The method includes a functional layer removing step of applying a CO2 laser beam to the wafer along each division line with the spot of the CO2 laser beam, having a width corresponding to the width of each division line set on the upper surface of each division line, thereby removing a functional layer along each division line to form a groove along each division line where the functional layer has been removed, and a groove shaping and debris removing step of applying a laser beam having a wavelength in the ultraviolet region to the wafer along each groove, thereby removing debris sticking to the bottom surface of each groove and also shaping the side walls of each groove.

Abstract: A wafer processing method divides a wafer into a plurality of individual devices along a plurality of crossing division lines formed on the front side of the wafer. The method includes a functional layer removing step of applying a CO2 laser beam to the wafer along each division line with the spot of the CO2 laser beam, having a width corresponding to the width of each division line set on the upper surface of each division line, thereby removing a functional layer along each division line to form a groove along each division line where the functional layer has been removed, and a groove shaping and debris removing step of applying a laser beam having a wavelength in the ultraviolet region to the wafer along each groove, thereby removing debris sticking to the bottom surface of each groove and also shaping the side walls of each groove.

Abstract: A laser beam machining apparatus including a chuck table for holding a wafer, and a laser beam irradiation unit for irradiating the wafer held on the chuck table with a pulsed laser beam. The laser beam machining apparatus further includes a plasma detecting part which includes a plasma receiving part for receiving a plasma generated by irradiation of the work with the laser beam radiated from the laser beam irradiation unit, and a spectrum analyzing part for analyzing the spectrum of the plasma received by the plasma receiving part; and a controller for determining the material of the work on the basis of a spectrum analysis signal from the spectrum analyzing part of the plasma detecting part and for controlling the laser beam irradiation unit.

Abstract: A graphite nanosphere which has a structure wherein a plurality of pyramids of multilayer graphite are arranged without clearance, taking their apexes as a center and the external form thereof is nearly spherical as a whole or as a part; and a method for preparing the graphite nanosphere which comprises irradiating a carbon target with a CO2 laser in an inert gas atmosphere under a pressure of 5 to 10 atm to thereby generate the carbon in an atomic or cluster form having a temperature of no less than 1000° C.

Abstract: A particular material comprising an atom other than carbon is carried around or inside the carbon nanohorn.

Abstract: A novel carbon nanohorn adsorbent which does not necessitate a high-temperature treatments lightweight and chemically stable, and can selectively adsorb molecules based on the molecular sieve effect; and a process for producing the adsorbent. The process comprises oxidizing a single-wall carbon nanohorn aggregate while controlling oxidative conditions to thereby obtain the carbon nanohorn adsorbent, which have, in the tubular parts, pores having a regulated diameter.