SEMICONDUCTOR SUBSTRATE AND ITS HEAT TREATMENT METHOD

PURPOSE:To obtain a semiconductor substrate without affecting a device due to the deposition of an oxide during heat treatment of a semiconductor process and suppressing the increase in resistivity on the substrate surface. CONSTITUTION:A silicon semiconductor substrate is introduced into an inactive gas atmosphere containing a molecule including the dopant of a silicon semiconductor substrate. Then, the substrate is heated to 1100 deg.C or higher in the inactive gas atmosphere, thus obtaining a semiconductor substrate where the ratio of the average oxygen concentration between grids in the substrate to the average oxygen concentration between grids on the substrate surface is equal to 5 or more and the average oxygen concentration between grids on the substrate surface is equal to 2X10 atoms/cm or less. Also, the difference of average dopant impurity concentration between the inside of the substrate and the substrate surface is equal to or less than 5%.