A vertical LPCVD apparatus for 6 in. wafers with a new concept has been developed. The evaluation of the apparatus through depositions of polysilicon and Si3N4 has been carried out. This apparatus has three major advantages in comparison with that of the horizontal LPCVD, i.e., the high uniformity, low particulate generation, and nearly oxygen contamination-free deposition can be achieved. It was confirmed that the uniformity within a wafer and within a batch for polysilicon film thickness using this apparatus was -+ 0.5% and _+ 2%, and that of deposited Si3N4 film thickness was -+ 1% and _+ 3%, respectively. In a particle evaluation, the number of particles per square centimeter for particles larger than 0.2 ~tm in diam was less than ca. 1/6 of that obtained using a conventional horizontal LPCVD apparatus, when Si3N4 was deposited. Thus, this apparatus may be more suitable than the horizontal LPCVD for the fabrication of ultra large scale integrated circuit (ULSI) chips such as 16 Mbit D-RAMs.

SUMMARYThis paper describes a high-speed parallel clustering method that is suitable for use as a preprocessor for motion picture compression and coding. In the parallel clustering process, plural pixels are sampled in one frame of an image. Clusters are gathered according to their characteristics, among them, colors, motion vectors, etc., as a way to organize clusters or modify cluster-parameters in parallel. This operation is repeated until the frame is segmented optimally by a set of clusters. We propose the subframe parallel approach in order to enhance the parallelism of the clustering method and avoid load-imbalance in parallel tasks. The effectiveness of this approach is also presented and it is shown that a real-time clustering of motion picture images is available in most cases.

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