Wafer polishing method and wafer polishing device

A wafer polishing method of polishing a wafer with a polishing device,

• wherein
• the polishing device comprises:
• a polishing head comprising:
• a head main body part,
• a first ring-shaped member located below the head main body part, and having an opening,
• a plate-shaped member closing the opening on an upper surface side of the first ring-shaped member,
• a membrane closing the opening on a lower surface side of the first ring-shaped member, and
• a second ring-shaped member located below the membrane, and holding a wafer to be polished;
• and
• a polishing pad with which a lower surface of the wafer to be polished and a lower surface of the second ring-shaped member come in contact at the time of polishing,
• a space part formed by closing the opening of the first ring-shaped member by the plate-shaped member and the membrane has a central region and an outer peripheral region partitioned from the central region,
• the wafer polishing method comprises:
• acquiring in-plane thickness distribution information regarding the wafer to be polished or a wafer subjected to the same processing treatment as that for the wafer to be polished,
• determining a difference in pressure between a pressure Pc to be applied to a central part of the wafer to be polished by introducing a gas into the central region and a pressure Pe to be applied to an outer peripheral part of the wafer to be polished by introducing a gas into the outer peripheral region based on the in-plane thickness distribution information,
• determining any one pressure of Pc and Pe, and determining the other pressure based on the determined pressure and the difference in pressure,
• determining a pressure Pg to be applied from the head main body part downward by pressing the head main body part, based on a set value Pr of a contact pressure to be applied to the lower surface of the second ring-shaped member due to contact with the polishing pad at the time of polishing, and
• with the determined Pg, Pc, and Pe applied thereto, bringing the lower surface of the wafer to be polished into contact with the polishing pad to conduct polishing.