Method for improving in-plane resistivity uniformity of epitaxial wafer

The invention discloses a method for improving uniformity of in-plane resistivity of an epitaxial wafer. The method comprises the following steps: carrying out heat treatment on a substrate to be made into the epitaxial wafer; the heat treatment comprises the following five steps that S1, heat preservation is conducted for 20-40 min at the temperature of 480-500 DEG C; s2, the temperature is increased to 780-800 DEG C at the speed of 4-6 DEG C/ S3, carrying out heat preservation at 780 to 800 DEG C for 10 to 20 minutes; s4, cooling to 480-500 DEG C at the speed of 3-4 DEG C/min; s5, keeping the temperature at 480 to 500 DEG C for 20 to 40 minutes; the steps S1 to S5 are carried out in an inert atmosphere. According to the epitaxial wafer, the heavily doped red phosphorus substrate of the epitaxial wafer with uneven SRP radial distribution is subjected to heat treatment, so that the radial SRP distribution of the epitaxial wafer is effectively improved, and the problem of abnormal chip BVdss distribution cause