Patent ID: 6303511
Filing Date: 2001-10-16
Classification: H01L

Abstract:
A wafer flattening process comprising:a plasma generating step for causing plasma discharge of a gas in a discharge tube to produce an activated species gas and spraying that activated species gas from a nozzle of the discharge tube, wherein the gas is one of a gas of a halogen compound or a mixed gas including a halogen compound; anda local etching step for locally etching a relatively thick portion present on the surface of a wafer by the activated species gas sprayed from the nozzle while moving the nozzle of the discharge tube relatively along the surface of the wafer, whereinthe distance from a center of a plasma discharge location of the gas to the surface of the wafer is a distance larger than 3000 times the mean free path of the ions produced in the activated species gas and smaller than 6000 times said mean free path, whereby the ions in the activated species gas are extinguished by repeated collision within the activated species gas or their lifetime and whereby the wafer is etched to an etching depth.