Abstract
As chamber conditions gradually change with wafer processing, periodic wet cleaning is an inevitable event in semiconductor manufacturing. Since the chamber conditions are initialized during the wet cleaning, a chamber conditioning process called chamber seasoning follows the wet cleaning step. In this paper, a systematic procedure to optimize chamber seasoning for plasma etching is proposed, and the effectiveness is demonstrated in a semiconductor manufacturing environment. In order to quantitatively analyze plasma conditions for chamber seasoning and to achieve the optimum conditions objectively, a normalization technique for optical emission spectroscopy called a self-background normalization technique and a computational optimization process is suggested. By applying the optimized chamber seasoning conditions, a plasma reactor which is suffering from a serious etch rate drift after wet cleaning returns to a production ready status. Also, the etch rate of Si, which is an index for production readiness, is perfectly matched to 37.8 A/s for production. Hopefully, the proposed methodology in this paper will be disseminated to semiconductor manufacturers who experience similar issues after wet cleaning.
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