Study of Solving the Outgas Induced Defect in Metal Hard Mask All-in-One Etch Process

Abstract

This article introduced the issues when running 55nm BEOL MHM (Metal Hard Mask) AIO (All-In-One) Etch during manufacturing. Two kinds of issues are studied: one is the post etching condensation and another is the particles formed on un-etch wafers. Both issues show slot correlation which depends on wafer position in FOUP (Front Open Unified Pod): lower slots are defect free while upper slots getting worse. Experiments are carried on to study the slot effect as well as Q-time impact. It is identified that F (Fluorine) contained outgas generates the defects which impacted the wafers in the upper slots within FOUP. Compared to tightening Q-time and FOUP splitting, installing Purge Storage is much easier to control for massive production. It’s a kind of “In-situ” degas solution, simple but very effective. Furthermore it could be good reference to other more applications.