AVS 46th International Symposium
    Plasma Science and Technology Division Monday Sessions
       Session PS-MoA

Paper PS-MoA6
Using Optical Emission Spectroscopy (OES) to Monitor Different Parameters for a Contact Hole Etch Process between Wet Clean

Monday, October 25, 1999, 3:40 pm, Room 609

Session: Plasma Diagnostics I
Presenter: D. Knobloch, Infineon Technologies Dresden GmbH & Co. OHG, Germany
Authors: D. Knobloch, Infineon Technologies Dresden GmbH & Co. OHG, Germany
F.H. Bell, Infineon Technologies AG, Munich, Germany
J. Zimpel, Fraunhofer Institute, Germany
K. Voigtlaender, Fraunhofer Institute, Germany
Correspondent: Click to Email
Oxide etch processes in IC-fabrication is gaining more and more importance, since the open area of contact hole processes still decreases and metal etch processes become partly replaced by the dual damascene technology. However, process development and stability issues in a manufacturing environment is still handled by trying to adapt a well known base line process on new applications. A typical example is the use of design of experiments in order to determine the robustness of the process window. We established a plasma monitor module for oxide etch processes to simplify process development, characterize process drifts, investigate process mix, and optimize endpoint detection. The monitor module is based on an optical multi-channel analyzer system that allows simultaneous detection of wavelength ranges between 200-950 nm. The system can be coupled to etch tools via the host net to collect data on a run to run basis. Intelligent data analyses software, such as principa! l component analysis (PCA) and partial least square (PLS) algorithms, is implemented to extract process and equipment relevant parameters. A typical manufacturing issue is the mean time between clean (MTBC) of oxide etch equipment. In general, wet cleans are conducted in case particles or the etch rate non-uniformity exceed certain specifications. Indeed, for the etch chamber under investigation, the decrease of the oxide etch rate at the wafer edge determines the wet clean cycle. We analyzed oxide and silicon surfaces after etching as a function of rf-hours and on different spots of the sample using x-ray photoelectron spectroscopy (XPS). The results show that the etch rate non-uniformity can be correlated to the polymer composition. Moreover, the optical emission data show that analysis of suitable wavelength ranges can be used for physical interpretation of the non-uniformity phenomenon. Furthermore, the influence of process mix on the cleanliness of the etch chamber will be discussed.