Texas Instruments Corporation

John W Kuehne

Mehrdad M Moslehi

Sunil V Hattangady

Lino A Velo

Tad (Douglas) Grider

An embodiment of the instant invention is a method of fabricating an electronic device over a semiconductor substrate which includes a dielectric layer formed between a first structure and a second structure, the method comprising the steps of: growing an oxide-containing layer (layer,of FIGS.,) on the first structure (substrate,of FIGS.,); forming a silicon-containing layer (layer,of FIG.,) on the oxide-containing layer; oxidizing substantially all of the silicon-containing layer by subjecting it to an ambient comprised of oxygen and nitrogen with a substrate temperature around 700 to 800 C.; and forming the second structure (layer,of FIG.,) on the oxidized silicon-containing layer. Preferably, the step of oxidizing substantially all of the silicon-containing layer is performed by subjecting the silicon-containing layer to an ambient containing: N,O with a wafer temperature around 700 to 800 C.; or NO with a wafer temperature around 700 to 800 C. The nitrogen is, preferably, incorporated between the oxide-containing layer and the first structure and/or between the oxide-containing layer and the oxidized silicon-containing layer.

Stacked/composite gate dielectric which incorporates nitrogen at an interface

Several process flows are proposed for achieving suitable wafer backside structures for integrated RTP-based device processing. The wafer backside conditions proposed here can be adapted for integrated fabrication process flows based on multiple integrated single-wafer and rapid thermal processing (RTP) cycles. These backside conditions ensure repeatable RTP uniformity and accurate pyrometry calibrations and measurements. The use of a highly doped layer near the wafer backside ensures negligible infrared transmission and repeatable RTP-based process uniformity, both for the high-temperature and the lower temperature RTP-based processes such as low-pressure chemical-vapor deposition of silicon. Two backside layers are used (oxide and nitride) to prevent dopant outdiffusion and backside oxide growth due to thermal oxidation. Moreover, the backside silicon nitride layer preserves uniform backside emissivity throughout the entire flow. This is due to the oxidation resistance and also etch resistance of silicon nitride. The backside structures disclosed prevent emissivity variations/drift during RTP and other device fabrication steps throughout an integrated flow.

Conditioning of semiconductor wafers for uniform and repeatable rapid

A method of forming doped wells 24 and 30 in a semiconductor layer is disclosed herein. In a preferred embodiment, an oxide layer 16 is formed on the surface of a silicon layer 14. A nitride layer 18 is then formed on the oxide layer 16 and is patterned and etched to define a first well region 24. The first well region 24 is then doped, for example with phosphorus or boron. A resist layer 26 is formed over the first well region 24 and over a portion of the nitride layer 18 after which a portion of the nitride layer 18 not beneath the resist layer 26 is removed to expose a second well region 30. The second well region 30 is then doped. After the remaining portion the resist layer 26 is removed, an oxide layer 32 is formed over the first 24 and second 30 well regions while the surface 38 over the region 36 separating the well regions is left bare. The semiconductor wafer 10 is then heated in a nitridizing environment (e.g., ammonia ambient) such that dopants tend to diffuse into the silicon layer 14 with enhanced vertical diffusivities but reduced lateral diffusivities.

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Dallas, TX, United States of America

John W Kuehne