A semiconductor structure including a trench formed in a substrate and a buried isolation collar that extends about sidewalls of the trench. The buried isolation collar is constituted by an insulator formed from a buried porous region of substrate material. The porous region is formed from a buried doped region defined using masking and ion implantation or by masking the trench sidewalls and using dopant diffusion. Advantageously, the porous region is transformed to an oxide insulator by an oxidation process. The semiconductor structure may be a storage capacitor of a memory cell further having a buried plate about the trench and a capacitor node inside the trench that is separated from the buried plate by a node dielectric formed on the trench sidewalls.

Title
Methods for forming semiconductor structures with buried isolation collars and semiconductor structures formed by these methods
Application Number
200610142854
Publication Number
1967798
Application Date
October 27, 2006
Publication Date
May 23, 2007
Inventor
Mandelman Jack A
Cheng Kangguo
Agent
zhanggao
Assignee
Ibm
IPC
H01L 27/02
H01L 27/108
H01L 21/82
H01L 21/8242
H01L 21/762