A shallow trench isolation approach for improved STI corner rounding

Abstract

A method for performing shallow trench isolation during semiconductor fabrication that improves trench corner rounding is disclosed. The method includes etching trenches (34) into a silicon substrate (24) between active regions (30), and performing a double liner oxidation process (56) and (60) on the trenches (34). The method further includes performing a double sacrificial oxidation process (72) and (76) on the active regions (30), wherein corners (35) of the trenches (34) are substantially rounded by the four oxidation processes.

Description

technical field [0001] The present invention relates to semiconductor processing and, in particular, to methods of performing trench isolation during the manufacture of semiconductor components. Background technique [0002] Shallow Trench Isolation (STI) technology uses shallow, refilled trenches to isolate devices that are the same type as LOCOS isolation instead of LOCOS isolation. The process begins by depositing a layer of pad oxide on the silicon substrate and patterning a nitride mask to define an active area on the silicon substrate. The shallow trenches are then etched into the silicon substrate through the openings in the silicon nitride mask between the active areas. A liner oxidation process is performed on the recess where the thin layer oxide is grown. Next, an oxide (such as silicon dioxide) is deposited on the silicon substrate, and then etched back so that only the oxide remains in the trenches, the top surface of which is level with the nitride mask. Aft...

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Problems solved by technology

However, neither of these two methods sufficiently rounds the trench corners 16 to reduce leakage to an acceptable level.

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