Advanced pressure control in time division multiplexed (TDM) plasma etch processes

Shouliang Lai; Russ Westerman; Dave Johnson; John J. Nolan

doi:10.1117/12.521910

30 December 2003 Advanced pressure control in time division multiplexed (TDM) plasma etch processes

Shouliang Lai, Russ Westerman, Dave Johnson, John J. Nolan

Author Affiliations +

Proceedings Volume 5342, Micromachining and Microfabrication Process Technology IX; (2003) https://doi.org/10.1117/12.521910
Event: Micromachining and Microfabrication, 2004, San Jose, California, United States

Abstract

Time division multiplexed (TDM) plasma etch processes have been widely applied to MEMS device manufacturing due to the capability of defining high aspect ratio features at high etch rates and mask selectivity. To etch anisotropic features using F-based chemistry, a TDM process cyclically alternates between etch and passivation steps, which are normally carried out with different gases introduced into a reaction chamber at different flow rates, and during which chamber pressures are maintained at different levels. Conventional process control methods often result in chamber pressure overshoot and/or undershoot, slow pressure response times, and long-term pressure drifts. These are undesirable effects in manufacturing MEMS devices due to the requirements on process stability, reliability and repeatability. At Unaxis USA Inc., a proprietary control technique has been developed for the TDM etch processes to better control chamber pressures and improve process stability. Controls over the movement of a throttle valve are realized through a combination of pre-positioning the valve and regulating it with the proportional, integral and derivative (PID) function mechanisms. Using this technique, we have demonstrated in fast TDM processes that pressure overshoot and undershoot are significantly suppressed, pressure response times are improved, and long-term pressure drifts are eliminated. To this end, this new control technique has been successfully tested in processes where the etch/passivation process steps are alternating at frequencies up to 1 Hz. Applications of this advanced technique in deep silicon etching have demonstrated improved etch performance. As a result, this advanced pressure control technique enables the TDM dry etching technologies for MEMS devices manufacturing to become markedly more reliable and stable.

Citation Download Citation

Shouliang Lai, Russ Westerman, Dave Johnson, and John J. Nolan "Advanced pressure control in time division multiplexed (TDM) plasma etch processes", Proc. SPIE 5342, Micromachining and Microfabrication Process Technology IX, (30 December 2003); https://doi.org/10.1117/12.521910

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

;

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE