Indium phosphide substrate and method for producing indium phosphide substrate

A method for producing an indium phosphide substrate comprising a main surface and an orientation flat, wherein:

• the indium phosphide substrate includes a plurality of observation measurement points for evaluating linearity of a ridge line where the main surface is in contact with the orientation flat, said observation measurement points being located on the ridge line 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 each end of the ridge line, a distance of each of the plurality of observation measurement points from a reference line is defined as a deviation of each respective observation measurement point, wherein the reference line is a straight line connecting the start point and the end point, and a maximum deviation of the plurality of observation measurement points, based on the deviation of each respective observation measurement point, is less than 1/1000 of a length of the ridge line, the method comprising the steps of:
• grinding an ingot of indium phosphide at a grinding wheel feed rate of 20 to 35 mm/min using a grinding wheel having a grit size of #270 to #400 to form the orientation flat;
• cutting out at least one wafer having the main surface and the orientation flat from the ground ingot of indium phosphide;
• chamfering an outer circumference portion of the wafer other than end faces of forming the orientation flat;
• polishing at least one surface of the chamfered wafer;
• and
• forming the indium phosphide substrate by etching the polished wafer under the following etching conditions:
• etching conditions:
• when an etching solution composition comprises 85% by mass of aqueous phosphoric acid solution and 30% by mass of hydrogen peroxide solution, the composition has a volume ratio of the aqueous phosphoric acid solution:the hydrogen peroxide of 0.2 to 0.4:0.1, the balance being water so as to add up to 1 as the total etching solution;
• temperature of the etching solution:
• from 60 to 100° C.;
• etching time:
• from 8 to 15 minutes.

A method for producing an indium phosphide substrate comprising a main surface and an orientation flat, wherein:

• the indium phosphide substrate includes a plurality of observation measurement points for evaluating linearity of a ridge line where the main surface is in contact with the orientation flat, said observation measurement points being located on the ridge line 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 each end of the ridge line, a distance of each of the plurality of observation measurement points from a reference line is defined as a deviation of each respective observation measurement point, wherein the reference line is a straight line connecting the start point and the end point, and a maximum deviation of the plurality of observation measurement points, based on the deviation of each respective observation measurement point, is less than 1/1000 of a length of the ridge line, the method comprising the steps of:
• grinding an ingot of indium phosphide to form the orientation flat;
• cutting out at least one wafer having the main surface and the orientation flat from the ground ingot of indium phosphide;
• griding end faces of the orientation flat on the wafer at a grinding wheel feed rate of 60 to 180 mm/min using a grinding wheel having a grit size of #800 to #1200 and chamfering an outer circumference portion other than the orientation flat;
• polishing at least one surface of the chamfered wafer;
• and
• forming the indium phosphide substrate by etching the polished wafer under the following etching conditions:
• etching conditions:
• when an etching solution composition comprises 85% by mass of aqueous phosphoric acid solution and 30% by mass of hydrogen peroxide solution, the composition has a volume ratio of the aqueous phosphoric acid solution:the hydrogen peroxide of 0.2 to 0.4:0.1, the balance being water so as to add up to 1 as the total etching solution;
• temperature of the etching solution:
• from 60 to 100° C.;
• etching time:
• from 8 to 15 minutes.