Method of forming an isolation layer and method of manufacturing a trench capacitor

US6984556B2 · kind B2 · utility

Assignee

• Infineon Technologies AG · DE

Inventors

• Christian Drabe · Dresden, DE
• Jana Haensel · Dresden, DE
• Anke Krasemann · Dresden, DE
• Barbara Lorenz · Dresden, DE
• Thomas Morgenstern · Dresden, DE
• Torsten Schneider · Buxtehude, DE
• Bruno Spuler · Wappingers Falls, US

Key dates

• Filing date: Jun 24, 2002
• Grant date: Jan 10, 2006
• Expiry date: Jun 24, 2022

Classification

• Technology area (CPC H): Electricity
• CPC primary: H01L21/31116
• WIPO field: Semiconductors
• WIPO sector: Electrical engineering

Abstract

A two-step etch process is used to form a vertical collar oxide within the upper portion of a trench capacitor. The first step uses CF4/SiF4/O2 chemistry and ends when the bottom of the collar within the trench is opened although a thin oxide layer still remains on the surface of the PAD-nitride. The second etch step uses C4F8 chemistry to completely remove the remaining silicon oxide layer. The process provides a good uniformity in thickness of the PAD-nitride layer and sufficient collar oxide thickness in the very top section of the collar oxide. The process is applicable for manufacturing deep trench capacitors for DRAM devices.