Directional chemical oxide etch technique

US9472415B2 · kind B2 · utility

Assignee

• International Business Machines Corporation · US

Inventors

• Emre Alptekin · Fishkill, US
• Sivananda K. Kanakasabapathy · Niskayuna, US
• Ahmet S. Ozcan · Pleasantville, US
• Viraj Y. Sardesai · Poughkeepsie, US
• Cung D. Tran · Newburgh, US

Key dates

• Filing date: Apr 30, 2014
• Grant date: Oct 18, 2016
• Expiry date: Jul 5, 2034

Classification

• Technology area (CPC H): Electricity
• CPC primary: H01L21/76897
• WIPO field: Semiconductors
• WIPO sector: Electrical engineering

Abstract

A method of forming a trench in an oxide layer; where the oxide layer is formed on top of a nitride layer. The trench is formed using an iterative etching technique until the nitride layer is exposed, each iterative etching step includes; using an isotropic etching technique to remove a portion of the oxide layer, the isotropic etching technique produces a byproduct that remains along a sidewall and a bottom of the trench, then using an anisotropic etching technique to remove the salt from the bottom of the trench, leaving salt on the sidewalls of the trench.