Provided is an indium phosphide substrate having good accuracy of flatness of the orientation flat, and a method for producing the indium phosphide substrate. An indium phosphide substrate having a main surface and an orientation flat, wherein a difference between maximum and minimum values of a maximum height Pz in each of four cross-sectional curves is less than or equal to 1.50/10000 of a length in a longitudinal direction of an orientation flat end face, wherein the four cross-sectional curves are set at intervals of one-fifth of a thickness of the substrate on a surface excluding a width portion of 3 mm inward from both ends of the orientation flat end face in the longitudinal direction of the orientation flat end face, and the maximum height Pz in each of the four cross-sectional curves is measured in accordance with JIS B 0601:2013.

A grinding apparatus includes a holding table that holds a wafer, a grinding unit that grinds an exposed surface of the wafer held by the holding table, a detecting unit that detects a physical quantity used for determination of the state of exposure of a separation surface of the wafer, and a control unit having an exposure determining unit that determines the state of exposure of the separation surface on the basis of the physical quantity detected by the detecting unit.

A grinding wheel for grinding a workpiece containing a ductile material, the grinding wheel including an annular wheel base having a fixed end adapted to be fixed to a lower end of a spindle and having a free end adapted to face the workpiece to be ground, and a plurality of grindstones each shaped as a rectangular plate, disposed on the free end of the annular wheel base, and arrayed at predetermined intervals with respective longer sides disposed along circumferential directions of the wheel base. Each of the grindstones includes an electroformed grindstone shaped as a rectangular plate and made up of abrasive grains secured together by nickel plating, and has a thickness of 1 mm or smaller and a value ranging from 5 inclusive to 35 exclusive that is represented by a ratio of a height from the free end to the thickness.

Provided is an indium phosphide substrate having good linearity accuracy of a ridge line where the main surface is in contact with the orientation flat, and a method for producing the indium phosphide substrate. An indium phosphide substrate having a main surface and an orientation flat, wherein a maximum value of deviation is less than 1/1000 of a length of a ridge line where the main surface is in contact with the orientation flat, when a plurality of measurement points are set at intervals of 2 mm from a start point to an end point at the ridge line, except for a length portion of 3 mm inward from both ends of the ridge line, and based on a reference line which is a straight line connecting the start point and the end point, a distance of each measurement point from the reference line is defined as the deviation of each measurement point.

An edge trimming method for cutting an outer peripheral portion of a workpiece having a chamfered part on the outer peripheral portion. The method includes a cut in step of relatively moving a rotating cutting blade and a chuck table to cause the blade to cut into the outer peripheral portion, a cutting step of, after the cut in step, rotating the chuck table and causing the outer peripheral portion to be cut, to form an annular step, and a moving step of, after the cutting step, moving the blade in a direction of its axis of rotation to form another annular step adjacent to the first-mentioned annular step. The cut in, cutting, and moving steps are repeated in this order, and a stepped oblique region is formed on the outer peripheral portion, with a thickness increasing from an outermost peripheral edge toward an inner side of the workpiece.

A grinding method for grinding a workpiece includes a first grinding step of grinding the workpiece in such a manner that an outer circumferential part of the workpiece becomes thinner than a central part of the workpiece, a measurement step of measuring the thickness of the workpiece at the outer circumferential part, and a second grinding step of grinding the workpiece. In the second grinding step, the grinding is started from the central part of the workpiece and the grinding is ended when the workpiece reaches a finished thickness decided based on the thickness of the workpiece at the outer circumferential part measured in the measurement step.

A wafer manufacturing apparatus includes an ingot grinding unit for grinding an upper surface of an ingot to planarize the upper surface of the ingot, a laser applying unit for forming peel-off layers in the ingot at a depth therein, which corresponds to the thickness of a wafer to be produced from the ingot, from the upper surface of the ingot, a wafer peeling unit for holding the upper surface of the ingot and peeling off a wafer from the ingot at the peel-off layers, a tray having an ingot support portion and a wafer support portion, and a belt conveyor unit for delivering the ingot supported on the tray between the ingot grinding unit, the laser applying unit, and the wafer peeling unit.

A double-side polishing method including: disposing a wafer between a polishing pad attached to an upper surface of a lower turn table and a polishing pad attached to a lower surface of an upper turn table provided above the lower turn table; and polishing both sides of the wafer. An absolute value of a difference between a gap at inner circumferential portions of the two polishing pads and a gap at outer circumferential portions thereof is defined as a pad gap. The pad gap is larger when the both sides of the wafer are polished than when the two polishing pads are dressed. This provides a double-side polishing method that simultaneously achieves enhancement of quality level (processing precision) and extension of cloth life.

A stacked wafer processing method for processing one wafer of a stacked wafer having at least two layers laminated, includes a sheet laying step of laying a thermocompression bonding sheet on an upper face of the one wafer, a thermocompression bonding step of thermocompression-bonding the thermocompression bonding sheet to an outer peripheral portion of the one wafer where a chamfered portion is formed, a modified layer forming step of irradiating the stacked wafer with a laser beam having a transmission wavelength to the thermocompression bonding sheet and the one wafer from the thermocompression bonding sheet side with a focal point of the laser beam positioned inside the outer peripheral portion of the one wafer, thereby continuously forming a modified layer inside the one wafer, and a chamfered portion removing step of expanding the thermocompression bonding sheet to break the chamfered portion, thereby removing the chamfered portion from the one wafer.

A wafer processing method includes a holding step of holding a wafer on a chuck table; a dressing step of cutting a peripheral marginal area of the wafer by a cutting blade mounted to a cutting unit to condition a state of a cutting edge; and a dividing step of cutting streets by the cutting blade mounted to the cutting unit to divide the wafer into individual device chips.