Internal plasma grid applications for semiconductor fabrication

摘要

The embodiments disclosed herein pertain to improved methods and apparatus for etching a semiconductor substrate. A plasma grid assembly is positioned in a reaction chamber to divide the chamber into upper and lower sub-chambers. The plasma grid assembly may include one or more plasma grids having slots of a particular aspect ratio, which allow certain species to pass through from the upper sub-chamber to the lower sub-chamber. In some cases, an electron-ion plasma is generated in the upper sub-chamber. Electrons that make it through the grid to the lower sub-chamber are cooled as they pass through. In some cases, this results in an ion-ion plasma in the lower sub-chamber. The ion-ion plasma may be used to advantage in a variety of etching processes.

主权项

1. A method of reflowing photoresist, the method comprising:
receiving a substrate in a reaction chamber, the substrate having photoresist patterned thereon, wherein the reaction chamber comprises a grid structure dividing the interior of the reaction chamber into an upper sub-chamber proximate a plasma generator and a lower sub-chamber proximate a substrate holder; flowing a first plasma generating gas into the upper sub-chamber; generating a first plasma in the upper sub-chamber from the first plasma generating gas, the first plasma having a first electron density, and generating a second plasma in the lower sub-chamber, wherein the second plasma is an ion-ion plasma that has a second electron density at least about 10 times lower than the first electron density; exposing the substrate to the second plasma to smooth the photoresist; flowing a second plasma generating gas into the upper sub-chamber; generating a third plasma in the upper sub-chamber from the second plasma generating gas, the third plasma having a third electron density, and generating a fourth plasma in the lower sub-chamber, wherein the fourth plasma is an ion-ion plasma that has a fourth electron density at least about 10 times lower than the third electron density; and exposing the substrate to the fourth plasma, wherein before exposing the substrate to the second plasma the photoresist has an initial line width roughness, wherein after exposing the substrate to the fourth plasma the photoresist has a final line width roughness, and wherein the final line width roughness is about 75% or less of the initial line width roughness.