High aspect ratio contacts

A process for etching an insulating layer, comprising:

• exposing the insulating layer in a plasma etch reactor to a plasma of a heavy ion gaseous etchant comprising,
• a first inert gas;
• and
• a first reactive gas, to etch an opening to an aspect ratio of less than approximately 15:1;
• exchanging the heavy ion gaseous etchant for a light ion gaseous etchant comprising,
• a second inert gas;
• and
• a second reactive gas, once the aspect ratio of the etched opening reaches approximately 15:1 to further etch the opening to an aspect ratio of at least 20:1;
• and
• wherein the light ion gaseous etchant has a lower mean molecular weight of the mixture of the second inert gas and the second reactive gas than the mean molecular weight of the first inert gas and the first reactive gas in the heavy ion gaseous etchant.

A process for etching an insulating layer, comprising:

• exposing the insulating layer in a plasma etch reactor to a plasma of a heavy ion reactive gas etchant to etch an opening to an aspect ratio of less than approximately 15:1;
• exchanging the heavy ion reactive gas etchant for a light ion reactive gas etchant once the aspect ratio of the etched opening reaches approximately 15:1 to further etch the opening to an aspect ratio of at least 20:1;
• and
• wherein the light ion reactive gas has a lower molecular weight than the heavy ion reactive gas.

A process for etching an insulating layer, comprising:

• first exposing the insulating layer to a second plasma of a second gaseous etchant comprising Ar, Xe, and combinations thereof to etch an opening up to an aspect ratio of approximately 15:1;
• and
• second exposing the insulating layer to a first plasma of a first gaseous etchant having at least fifty percent He to etch the opening having an aspect ratio of at least 15:1, thereby increasing the aspect ratio to greater than 15:1,
• wherein the first gaseous etchant has a lower molecular weight than the second gaseous etchant.

An etching process, comprising:

• supplying a gaseous etchant to a plasma etch reactor;
• etching a surface of an insulating layer with a plasma of the gaseous etchant to create an opening;
• adding at least fifty percent helium (He) to the gaseous etchant once the opening has reached an aspect ratio of at least 15:1;
• and
• forming the opening using the gaseous etchant with at least fifty percent helium (He) added to have a bottom and a side in the insulating layer that allows an axis perpendicular to the insulating layer to pass through the opening to the bottom uninterrupted by the side of the opening and having an aspect ratio of at least 20:1.

A method for operating an etch reactor, comprising:

• alternatively supplying a light ion gaseous etchant having at least fifty percent He to the etch reactor, and a heavy ion gaseous etchant comprising Ar, Xe, and combinations thereof, the light ion gaseous etchant having a lower molecular weight than the heavy ion gaseous etchant;
• supplying an insulating layer;
• first etching an opening to an aspect ratio of less than 15:1 with a first plasma of the heavy ion gaseous etchant;
• and
• second etching with a second plasma of the light ion gaseous etchant the opening having a bottom and a side in the insulating layer that allows an axis perpendicular to the insulating layer to pass through the opening to the bottom uninterrupted by the side of the opening, and having an aspect ratio of at least 15:1, thereby increasing the aspect ratio to greater than 15:1.