FORMATION OF CONTROLLED UPPER INSULATION LAYER AT TRENCH OF VERTICAL TRANSISTOR

摘要

PROBLEM TO BE SOLVED: To control the thickness of an insulation layer at a trench by growing an oxide deposition layer selectively at high rate above a conductive material and then removing the oxide deposition layer selectively except a part touching the conductive material in order to form an insulation layer on the conductive material in the trench. SOLUTION: A pad stack 16 is formed by laminating a pad oxide layer 18 and a pad nitride layer 20 sequentially on a substrate 12 and a deep trench 14 is made through the stack 16. After the trench 14 is filled with a conductive filler 24 to leave a recess 26, a nitride liner 36 is deposited on the inside of the recess to cover the pad stack 16. Subsequently, the nitride liner 36 is removed from the entire surface except for the side-wall of the trench 14 and an oxide deposition layer 40 is grown selectively at high rate. Thereafter, the oxide deposition layer 40 is removed except a part touching the conductive filler 24 in order to form an insulation layer 44 on the conductive filler 24.