Patent ID: 7384857

Claim:
A method of forming isolation regions in a semiconductor substrate, comprising: implanting an oxygen reactive agent in first regions below a surface of said semiconductor substrate in a pattern defining active regions and isolation regions; implanting oxygen in said active regions and said isolation regions below said surface of said semiconductor substrate, said oxygen being implanted to a depth sufficient for permitting interaction with the implanted oxygen reactive agent in said first regions; subjecting said semiconductor substrate to an anneal process to grow an oxide layer below said surface of said semiconductor substrate using the implanted oxygen, wherein areas where the implanted oxygen interacts with said oxygen reactive agent have an oxide growth rate different than areas where the implanted oxygen does not interact with the oxygen reactive agent, such that said anneal process results in said oxide layer having greater growth regions and lesser growth regions as determined by the different growth rates; flattening a top surface of said semiconductor substrate such that an upper surface of the greater growth regions of the oxide layer are made substantially flush with said top surface of said semiconductor substrate, and the lesser growth regions of said oxide layer remain below said top surface of said semiconductor substrate; wherein semiconductor substrate regions over the lesser growth regions designate active regions and the greater growth designate isolation regions.