Methods of forming bulb-shaped trenches in silicon

摘要

A method of creating a trench having a portion of a bulb-shaped cross-section in silicon is disclosed. The method comprises forming at least one trench in silicon and forming a liner in the at least one trench. The liner is removed from a bottom surface of the at least one trench to expose the underlying silicon. A portion of the underlying exposed silicon is removed to form a cavity in the silicon. At least one removal cycle is conducted to remove exposed silicon in the cavity to form a bulb-shaped cross-sectional profile, with each removal cycle comprising subjecting the silicon in the cavity to ozonated water to oxidize the silicon and subjecting the oxidized silicon to a hydrogen fluoride solution to remove the oxidized silicon. A semiconductor device structure comprising the at least one trench comprising a cavity with a bulb-shaped cross-sectional profile is also disclosed.

主权项

1. A method of forming a bulb-shaped trench in silicon, comprising:
forming at least one trench in silicon; forming a liner in the at least one trench; removing the liner from a bottom surface of the at least one trench to expose the underlying silicon; removing a portion of the underlying silicon to form a cavity in the silicon; and conducting at least one removal cycle to remove silicon in the cavity to form a cavity having a bulb-shaped cross-sectional profile, each removal cycle comprising:
subjecting the silicon in the cavity to ozonated water to oxidize exposed silicon within the cavity; andsubjecting the oxidized silicon and the liner to a hydrogen fluoride solution to remove the oxidized silicon in the cavity without removing the liner from sidewalls of the at least one trench.