AVS 45th International Symposium
    Manufacturing Science and Technology Group Thursday Sessions
       Session MS-ThM

Paper MS-ThM9
Improvement of Process and Equipment Performance Using Online and Real Time Optical Emission Spectroscopy

Thursday, November 5, 1998, 11:00 am, Room 317

Session: Sensors and Support Technology
Presenter: D. Knobloch, Siemens Microelectronics Center GmbH & Co. OHG, Germany
Authors: D. Knobloch, Siemens Microelectronics Center GmbH & Co. OHG, Germany
F.H. Bell, Siemens AG, Germany
J. Zimpel, Fraunhofer Institute, Germany
A. Steinbach, Siemens Microelectronics Center GmbH & Co. OHG, Germany
Correspondent: Click to Email
The semiconductor industry is continually driven towards the use of larger wafers (200 mm and larger) and smaller device dimensions (0.18 mm). More and more sophisticated technologies are necessary to improve overall production performance and reduce manufacturing costs. Intelligent process and equipment control applied to plasma processing is an excellent candidate to improve productivity, and thus profitability. We use optical emission spectroscopy to characterise etching processes for 64Mbit DRAM fabrication by in-situ analysis of plasma conditions. Parameters to be optimised include: increased wafer throughput and wafer yield, reliable processes, reduction of monitor wafers, optimisation of cleaning procedures. Four MxP@super +@ oxide etch chambers mounted on a Centura platform are equipped with optical multichannel analysers (200 - 950nm). The dynamic evolution of the spectra can be recorded every 20msec during wafer processing. The spectrometers are coupled to the etch chambers via the fab host computer allowing in-situ and real time process and equipment control. Intelligent data reduction techniques, such as principal component analysis (PCA), are used to extract process and equipment related wavelength ranges. Every process parameter, such as pressure, power and gas flows, shows a typical optical signature. Therefore, the cause of process variations can be determined. Furthermore, even without variation in the external parameters, the plasma processes are plagued by process drift phenomena: the process performance (e.g. etch rate, uniformity, selectivity) varies continually as a function of time. These phenomena are linked to the chemistry occuring at the reactor walls and the influence of thin films deposited by the plasma. These drifts can be correlated to changes of certain wavelength ranges in the optical emission spectra. Major benefits of this technique are early process fault detection and optimisation of chamber cleaning cycles. @FootnoteText@ The presented work was part of a project funded by the saxonian department of economy (SMWA), project number: PT2648.