초록 ▼

A method is disclosed to form a plurality of oxides of different thicknesses with one step oxidation. In a first embodiment, a substrate is provided having a high-voltage cell area and a peripheral low-voltage logic area separated by a trench isolation region. The substrate is first nitrided. Then t

A method is disclosed to form a plurality of oxides of different thicknesses with one step oxidation. In a first embodiment, a substrate is provided having a high-voltage cell area and a peripheral low-voltage logic area separated by a trench isolation region. The substrate is first nitrided. Then the nitride layer over the high-voltage area is removed, and the substrate is wet cleaned with HF solution. The substrate surface is next oxidized to form a tunnel oxide of desired thickness over the high-voltage. In a second embodiment, a sacrificial oxide is used over the substrate for patterning the high voltage cell area and the low-voltage logic area. The sacrificial oxide is removed from the low-voltage area and the substrate is nitrided after cleaning with a solution not containing HF, thus forming a nitride layer over the low-voltage area. Then, the sacrificial oxide is removed from the high-voltage area with an HF dip, and tunnel oxide of desired thickness is formed over the same area. In this manner, oxides of multiple thicknesses are provided for the high-voltage cell area and the low-voltage peripheral logic area with one oxidation step. At the same time, with a judicious use of cleaning and nitridation, any detrimental effects of the native oxide are circumvented.

대표청구항 ▼

[ What is claimed is:] [1.]1. A method of forming multiple oxide thicknesses with one step comprising the steps of:providing a substrate having a first active area and a second active area separated by a trench isolation region;performing nitridation to form a nitride layer over said substrate inclu

[ What is claimed is:] [1.]1. A method of forming multiple oxide thicknesses with one step comprising the steps of:providing a substrate having a first active area and a second active area separated by a trench isolation region;performing nitridation to form a nitride layer over said substrate including over both said first and second active areas, wherein said nitridation is performed using NH.sub.3 in an RTP at a temperature between about 600 to 1000.degree. C.;forming a masking layer over said nitride layer to protect a portion of said nitride layer overlying said second active area;etching of said nitride layer over said first active area not protected by said masking layer;removing said masking layer;wet cleaning said substrate including said first and second active areas; andperforming oxidation over said substrate including over said first and second active areas to form a tunnel oxide in one oxidation step over said first active area.