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

氧化硅薄膜在集成电路制造中已被用作金属氧化物半导体结构的绝缘层或钝化层。最初，用于集成电路的氧化硅薄膜是通过硅衬底热氧化或热化学气相沉积(CVD)来制备的。近年来，制备薄膜的方法有很多种，如低压CVD、等离子体氧化、溅射、等离子体CVD等。在这些方法中，等离子体CVD可以在较低的衬底温度下沉积出高质量的氧化硅薄膜。此外，采用正硅酸乙酯(TEOS)等离子体化学气相沉积(CVD)方法制备了阶跃覆盖率良好的氧化硅薄膜。在这项工作中，以TEOS为硅源，使用低频(50 Hz)等离子体CVD沉积了二氧化硅薄膜。本工作发现，当从TEOS和氧气的混合物中沉积二氧化硅薄膜时，需要在沉积时对衬底进行加热以获得可接受的电学性能，即使是在低频(50 Hz)等离子体CVD中也是如此。C是高质量的绝缘膜，其电阻率为10×10~(-6)欧米伽厘米，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，但薄膜中没有检测到碳原子。通过对TEOS和氧气混合等离子体的光发射光谱分析，观察到CO和CO2分子的强烈发射。

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.