Semiconductor wafer, and method for polishing semiconductor wafer
The present invention provides: an InP wafer optimized from the viewpoint of small edge roll-off (ERO) and sufficiently high flatness even in the vicinity of a wafer edge; and a method for effectively producing the InP wafer. The InP wafer having a roll-off value (ROA) of from −1.0 μm to 1.0 μm is obtained by using a method including: performing a first stage polishing under a processing pressure of from 10 to 200 g/cm 2 for a processing time of from 0.1 to 5 minutes, while supplying a polishing solution containing bromine to at least one side of an InP single crystal substrate that will form the InP wafer; and performing a second stage polishing under a processing pressure of from 200 to 500 g/cm 2 for a processing time of from 0.5 to 10 minutes, provided that the processing pressure is higher than that of the first stage polishing by 50 g/cm 2 or higher.
1. An indium phosphide (InP) wafer, the wafer comprising an InP single crystal, wherein the wafer has a roll-off value (ROA) of from −1.0 μm to 1.0 μm, wherein the roll-off value (ROA) is a difference between a value extrapolated in a distance of 1 mm from the edge portion of the wafer in a reference profile function and an actual value of the surface profile, and the reference profile function is obtained from a straight line connecting measurement points at a position of 3 mm and a position of 6 mm from the wafer edge to the central portion side.
2. The InP wafer according to claim 1 , wherein a central portion of the wafer has an arithmetic mean roughness (Ra) of 0.5 nm or less.
3. The InP wafer according to claim 1 , wherein the wafer has a total thickness variation (TTV) of 10 μm or less.
4. The InP wafer according to claim 1 , wherein the wafer has a thickness of 300 μm or more and 1000 μm or less.
5. The InP wafer according to claim 1 , wherein a surface of the wafer has a maximum length of 45 mm or more.
6. The InP wafer according to claim 1 , wherein a surface of the wafer has a maximum length of 50 mm or more.
7. The InP wafer according to claim 1 , wherein a surface of the wafer has a maximum length of 75 mm or more.
8. The InP wafer according to claim 1 , wherein a surface of the wafer has a maximum length of 100 mm or more.
9. A method for producing an indium phosphide (InP) wafer, the wafer comprising an InP single crystal, the method comprising:
performing a first stage polishing under a processing pressure of from 10 to 200 g/cm 2 for a processing time of from 0.1 to 5 minutes, while supplying a polishing solution containing bromine to at least one side of an InP single crystal substrate that will form the InP wafer; and
performing a second stage polishing under a processing pressure of from 200 to 500 g/cm 2 for a processing time of from 0.5 to 10 minutes, provided that the processing pressure is higher than that of the first stage polishing by 50 g/cm 2 or higher.
10. The method for producing the InP wafer according to claim 9 , wherein the polishing is performed by using a rotating surface plate having a polishing pad made of soft foamed polyurethane attached to a surface of the rotating surface plate.
11. The method for producing the InP wafer according to claim 9 , wherein the polishing is performed at a supply flow rate of the polishing solution of from 10 to 500 ml/min and at a rotation speed of the surface plate of from 10 to 100 rpm.