28 September 2001 Conformal deposition of LPCVD TEOS
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Proceedings Volume 4557, Micromachining and Microfabrication Process Technology VII; (2001) https://doi.org/10.1117/12.442963
Event: Micromachining and Microfabrication, 2001, San Francisco, CA, United States
The step coverage of dielectrics is important for the microelectronics industry and critical to Micro-machined products and High Voltage MEMS drivers. The techniques used to fabricate MEMS structures require void free refill processes and even film deposition along deep trenches to protect against etch chemistries. High voltage drivers used to actuate MEMS devices benefit from dielectric isolation, which reduces the need for large tub formation between devices. It also enables 'system on chip' solutions for MEMs devices and protection against voltage spikes. This paper presents a process developed at Analog Devices Belfast that enables an LPCVD TEOS furnace to perform a highly conformal trench refill without equipment modification. The conformality is over 95% for 20 micrometer deep trenches and maintains a conformality greater than 85% in 50 micrometer deep trenches. This compares with 75% conformality which is considered excellent for 20 micrometer trench refills obtained using previous LPCVD TEOS processing. The process is shown to have benefits in conformality, breakdown voltage, and stress over standard trench fill processes including Ozone TEOS. The densification of the TEOS film has been optimized for electrical parameters using CV and IV techniques, while XPS, FTIR and spectroscopic ellipsometry are used for physical characterization. Stress is a very important parameter for micro-machining and the conformal TEOS has a film stress which is tensile 30 - 40 MPa as deposited and compressive 100 MPa after densification. The breakdown voltage has been measured at 8.5 MV/cm compared to 7.5 - 9 MV/cm for a typical densified TEOS film and the refractive index is 1.456 compared to 1.465 for a thermal oxide. Analog Devices Belfast is part of the Micro-machined Products division and provides SOI and customized SOI for the MEMs and IC market.
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Paul McCann, Paul McCann, Kumar Somasundram, Kumar Somasundram, Stephen Byrne, Stephen Byrne, Andrew Nevin, Andrew Nevin, "Conformal deposition of LPCVD TEOS", Proc. SPIE 4557, Micromachining and Microfabrication Process Technology VII, (28 September 2001); doi: 10.1117/12.442963; https://doi.org/10.1117/12.442963

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