Taiwan Semiconductor Manufacturing Comp. Ltd.

Chi-Fu Ni

Yu-Jen Yu

Hui-Hua Chang

A method of testing a dry oxidation furnace for leaks which permit the entry of moisture into the oxidizing ambient is described. Such moisture, when present in sufficient concentration, can cause a high degree of boron depletion in silicon at p-type contact interfaces in the manufacture of p-channel MOSFETs. The depleted silicon presents a high resistance component to the contact thereby compromising its performance. A test wafer is subjected to a non-oxidizing ambient in the furnace according to a prescribed procedure. Measurements of the thickness of an oxide layer on the test wafer before and after the procedure indicate the presence of a leak of sufficient proportions to cause a deterioation of contact performance if the oxide grown during the test procedure exceeds between about 25 to 35 Angstroms. The procedure is also useful as a simple means of monitoring an oxidation furnace to provide a record of performance and signal the development of trends which suggest appropriate remedial maintenance.

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Hsin-Chu, Taiwan

Chi-Fu Ni