Development of Low Temperature Deposition Process of Silicon Oxide Film by Low Frequency Plasma CVD (TEOS+O_2)

氧化硅薄膜已被用于集成电路的制造，作为金属氧化物半导体结构的绝缘层或作为钝化层。最初，用于集成电路的氧化硅薄膜是通过硅衬底的热氧化或热化学气相沉积（CVD）制备的。近年来，人们开发了低压CVD、等离子体氧化、溅射、等离子体CVD等多种制备方法。在这些方法中，等离子体CVD可以在相对较低的衬底温度下沉积高质量的氧化硅薄膜。此外，利用TEOS（四乙氧基硅烷）等离子体气相沉积技术制备了台阶覆盖度良好的氧化硅薄膜。本文以TEOS为硅源，采用低频（50Hz）等离子体气相沉积技术制备了氧化硅薄膜。在本工作中发现，当用TEOS和氧气混合物沉积氧化硅薄膜时，即使使用低频（50Hz）等离子体CVD，也需要在沉积时加热衬底以获得可接受的电性能。底片在200度下沉积。从等离子体中提取3% TEOS的C混合物，发现是高质量的绝缘薄膜；电阻率为10^<16> ω cm，击穿强度为7 × 10^6 V/cm。此外，俄歇电子能谱分析表明，尽管TEOS分子中存在碳原子，但薄膜中未检测到碳原子。通过对TEOS和氧气混合等离子体的发射光谱分析，观察到CO和CO_2分子的强发射。

Silicon oxide films have been used in the fabrication of integrated circuits as the insulation layr of metal-oxide-semiconductor structures or as a passivation layr. In the beginning, silicon oxide films used in integrated circuits were prepared by thermal oxidation of silicon substrates or thermal chemical vapor deposition (CVD). Recently, many kinds of methods to prepare the films, such as low pressure CVD, plasma oxidation, sputtering, and plasma CVD have been developed. Among these methods, plasma CVD can deposit high quality silicon oxide films at comparatively low substrate temperatures. Moreover, silicon oxide films with good step coverage are deposited by plasma CVD using TEOS (Tetraethoxysilane). In this work, the silicon oxide films was deposited using TEOS as a silicon source by using a low frequency (50Hz) plasma CVD.It is found in the present work that the substrate heating at deposition is required to obtain acceptable electrical properties when silicon oxide films are deposited from a TEOS and oxygen mixture, even by low frequency (50Hz) plasma CVD.The films deposited at 200。C from the plasma of a 3% TEOS mixture were found to be high quality insulating films ; the resistivity was 10^<16>OMEGA cm and the breakdown strength 7X10^6 V/cm. Moreover, Auger electron spectrum analysis revealed that carbon atoms were not detected from the films in spite of the presence of carbon atoms in the TEOS molecule. With optical emission spectrum analysis of the TEOS and oxygen mixture plasma, strong emissions from the CO and CO_2 molecules were observed.