Lam Research Corporation

Timothy M Ebel

William Reid Harshbarger

David R Pirkle

Mathias Fecher

Larry Williams

A method for simultaneously stripping a photoresist mask employed for etching, in a low pressure, high density plasma processing chamber, a contact hole through an oxide layer to a silicon layer of a substrate and soft etching a surface of the silicon layer at a bottom of the contact hole. The technique of simultaneously stripping and soft etching is configured to substantially remove the photoresist mask and reducing a contact resistance at the bottom of the contact hole simultaneously. The method includes flowing an etchant source gas comprising a fluorocarbon and O,into the plasma processing chamber after the contact hole is formed but prior to filling the contact hole with a substantially conductive material. There is also included forming a plasma from the etchant source gas. Additionally, there is included employing the plasma for simultaneously stripping and soft etching for a predefined duration sufficient to lower a contact resistance between the silicon substrate and the substantially conductive material that is subsequently deposited into the contact hole to a predefined acceptable level.

Techniques for forming contact holes through to a silicon layer of a substrate

A method for cleaning and conditioning a plasma processing chamber wherein oxide residues have been previously formed on interior surfaces of the chamber. The method includes introducing a cleaning gas including a fluorine-based gas into the chamber followed by performing a plasma cleaning step. The plasma cleaning step is performed by activating the cleaning gas mixture and forming a plasma cleaning gas, contacting interior surfaces of the chamber with the plasma cleaning gas and removing oxide residues on the interior surfaces. The cleaning step is followed by coating the interior surfaces with silicon dioxide to adhere loose particles to the interior surfaces and a conditioning step wherein uncoated interior surfaces are treated to remove fluorine therefrom. An advantage of the cleaning and conditioning method is that it is not necessary to open the chamber. Also, it is possible to remove oxide residues during the cleaning step and remove fluorine remaining after the cleaning step during the conditioning step. The conditioning step is carried out by introducing a hydrogen-containing gas into the chamber as a purge gas or the chamber can be pressurized by the hydrogen-containing gas followed by evacuating the chamber.

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San Jose, CA, United States of America

Timothy M Ebel