Performance of a New Vertical LPCVD Apparatus

Abstract

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.