Showing papers by "Hans Norström published in 1987"

Oxide Breakdown due to Charge Accumulation during Plasma Etching

Abstract: L'accumulation de charge sur un oxyde de grille isolant peut provoquer une disruption electrostatique. L'exposition d'une pastille contenant des dispositifs MOS a une decharge de plasma pendant la fabrication des structures de grille en polycristal peut entrainer une degradation du dispositif due a l'accumulation de charge. A 13,56 MHz la charge pouvant etre transferee sur la pastille est si petite qu'il est peu vraisemblable que la grille atteigne la disruption. Cependant, si la frequence est basse ou si l'alimentation est continue, les oxydes peuvent subir la disruption. Ils presentent aussi un accroissement de la densite d'etats a l'interface oxyde-semiconducteur. Une distribution de densite d'etats similaire est aussi trouvee si le courant d'une source constante traverse l'oxyde. Ce courant a la meme valeur que celui qui parcourt les echantillons dans le plasma. On conclut que l'accumulation de charge est la cause principale de defaillance par disruption electrique dans la gravure par plasma

Dry etching of n‐ and p‐type polysilicon: Parameters affecting the etch rate

Abstract: The etch rate of doped polycrystalline silicon films (polysilicon) was studied as a function of dopant concentration, degree of dopant activation, and dopant type, in a parallel‐plate reactor, using a CFCl3 plasma. The significant difference in etch rate between n‐doped and p‐ or undoped polysilicon observed indicates that the electrical activity of the bulk (and surface) plays an important role when etching at a plasma frequency of 13.56 MHz. However, at lower frequencies this difference in etch rate for n‐ and p‐doped polysilicon is less pronounced.

A comparison of different methods for removal of damage caused by reactive sputter etching of silicon

Abstract: The influence of etch time and power density on damage introduced in silicon by reactive sputter etching has been investigated. The induced damage was characterized by Schottky barrier height measurements, backscattering–channeling technique, and transmission electron microscopy. The study also comprises three methods for removal of the damage. It was found that the surface could be fully restored by means of thermal oxidation or plasma oxidation followed by a HF dip. These results were verified both by electrical measurements and by backscattering–channeling technique. The rapid thermal annealing treatment seems to fully restore the surface etched at a power density of 0.5 W/cm2 or lower. For higher power densities, the surface is not fully restored, but a considerable improvement is found.