Introduction

PLASMA-ENHANCED CHEMICAL VAPOR DEPOSITION (PECVD), also known as plasma-assisted CVD, is an important technique used for depositing films of a wide variety of crystalline and noncrystalline materials. Examples of films that are commonly deposited using the PECVD process are noncrystalline materials such as oxides, nitrides, and oxynitrides of silicon (Ref 1), and crystalline materials such as polycrystalline silicon (Ref 2, 3, 4), epitaxial silicon (Ref 5, 6, 7), and refractory metals and their silicides. All of these materials are extensively used in microelectronic device fabrication, and PECVD is a critical process step in the fabrication of modern silicon devices. PECVD is also used in depositing optical coatings and other crystalline compounds such as titanium nitride, which is used in highly wear-resistant coatings on cutting tools (Ref 8).

Thermally driven atmospheric-pressure and low-pressure chemical vapor deposition (APCVD and LPCVD, respectively) are well understood and established methods for depositing films in integrated circuit (IC) fabrication technology (see the article "Chemical Vapor Deposition of Semiconductor Materials" in this Volume). However, the deposition temperatures in a thermally driven CVD process can be quite high (e.g., 700 to 900 °C, or 1300 to 1650 °F, for LPCVD silicon nitride deposition) (Ref 1, 9) and thus are detrimental to modern silicon devices. Plasma enhancement of the CVD process makes it possible to lower the deposition temperature significantly (e.g., to 250 to 300 °C, or 480 to 570 °F, for PECVD of silicon nitride) (Ref 1, 9) while maintaining a reasonable rate of deposition and film quality. Thus, some of the advantages of PECVD are that:

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