Two-step oxidation process for semiconductor wafers

US7517813B2 · kind B2 · utility

Assignee

• X-FAB SEMICONDUCTOR FOUNDRIES GMBH · DE

Inventors

• Ralf Lerner · Erfurt, DE
• Uwe Eckoldt · Hohenfelden, DE

Key dates

• Filing date: Oct 6, 2005
• Grant date: Apr 14, 2009
• Expiry date: Oct 6, 2025

Classification

• Technology area (CPC H): Electricity
• CPC primary: H01L21/76202
• WIPO field: Semiconductors
• WIPO sector: Electrical engineering

Abstract

An efficient method for the thermal oxidation of preferably silicon semiconductor wafers using LOCOS (local oxidation of silicon) processes is described. The mechanical stresses of the wafers are to be reduced. To this end, an oxidation method is proposed that comprises providing a substrate (1) having a front side (12) to be patterned and a rear side (13). The substrate is oxidized in two steps. In a first step the rear side (13) is covered by a layer (4) that inhibits or hampers the oxidation. During a second step of the oxidation the oxidation-hampering layer (4) is no longer present. During both steps an oxide thickness is obtained on the front side (12) that is greater than an oxide thickness obtained on the rear side (13).