Patent ID: 6218309
Filing Date: 2001-04-17
Classification: H01L

Abstract:
In a plasma processing chamber, a method of etching a trench in a silicon layer, said silicon layer being disposed below a hard mask layer, said method comprising:flowing a first etchant source gas into said plasma processing chamber;forming a first plasma from said first etchant source gas;etching through a first portion of said silicon layer with said first plasma to form an effective top-rounded attribute in a portion of said trench;flowing a second etchant source gas into said plasma processing chamber;wherein said first etchant source gas is evacuated from said plasma processing chamber before flowing said second etchant source gas into said plasma processing chamber;forming a second plasma from said second etchant source gas; andetching through a second portion of said silicon layer with said second plasma, wherein said etching with said second plasma extends said trench into said silicon layer without unduly damaging said top rounded attribute.