FLATTENING OF SURFACE OF SUBSTRATE

PURPOSE:To contrive to enhance precision of abrasion of a semiconductor substrate by a method wherein an abrasion resistant layer formed on the surface part of the substrate other than grooves and having an abrading speed lower than a buried material is utilized as a stopper against mechanical abrasion. CONSTITUTION:A material having hardness higher than an abrasive material to be used for mechanical abrasion is selected to form an Si3N4 film 3 to be formed on an SiO2 film 2 on a P type silicon semiconductor substrate 1. The surfaces of grooves 41, 42 are oxidized to form insulating films 6, and when a burying material 7 consisting of poly-silicon is deposited on the whole of the surface of the substrate 1, a recess 8 is generated on the surface of the brad width groove 42 part. To flatten the surface of the buried material 7 without receiving so much the influence of the recess 8, it is favorable to depend on mechanical abrasion. As an abrasive material, SiO2 powder having higher hardness than the poly-silicon of buried material 7, while having lower hardness than Si3N4 constructing the abrasion resistant layer 3 is used. Accordingly, the layer 3 having a slow abrading speed is made to function as a stopper against abrasion, and high precise abrasion can be attained extending over the whole of the surface of the substrate 1.