A dry single-wafer process for the stripping of As+ ion-implanted photoresists has been developed. The process utilizes a combination of reactive ion etching (RIE) and remote microwave plasma chemical processing. The implanted arsenic is removed through conversion to a volatile compound after removal of the organic matrix.

The objective of this study is to develop a via post-strip cleaning process which would utilize non-hydroxylamine (HDA) based solvent, thereby reducing possibility of corrosion in the via and also reducing the cost of chemicals and waste disposal expenses. The work resulted in the development of a 100% solvent-less process which matches the performance of HDA-based solvents but totally eliminates chemical costs and waste-disposal expenses; removes the hazards of working with hot hazardous solvents; avoids corrosion which is common with HDA-based solvents; and thereby facilitates more efficient utilization of costly clean-room space. The new ash process in combination with a post-ash DI water rinse has been demonstrated to be effective at removing polymer inside vias and achieving via resistances comparable to standard oxygen ash + HDA wet solvent stripping.

Using a combined microwave downstream plasma and low damage NE, we have successfully developed a dry process that removes both the photoresist and the remaining polymer residue after a via etch step.An ion assisted plasma process containing oxygen and fluorine was successfilly developed. It was found that the ion-assisted process converted the Ti, Si and their oxide containing residues to water-soluble compounds. Thus, a room temperature DI water rinse after the dry process removed the entire sidewall residue. The process is carried out at room temperature to avoid any undercutting of the TiN layer.SEM micrographs show that the via sidewall is free of any residue. The electrical data shows via resistance equal to or lower than samples cleaned with the standard process using oxygen plasma followed by a solvent clean. This process has been shown to be a reliable and cost-effective alternative to solvent based processing. Failure due to the narrow window of the solvent process is eliminated and equivalent or improved yield

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Articles you may be interested inEtching of thin metal films using a ballistic model J. Vac. Sci. Technol. A 10, 912 (1992); 10.1116/1.577694 Summary Abstract: Plasmaenhanced beam deposition of thin dielectric films Abstract: Etching in reactive plasmas