Gas pulsing for etch profile control

A method of etching oxide using a polymer, the method comprising:

• disposing a patterned semiconductor substrate in a high density plasma etcher, said substrate comprising a silicon layer with a gate stack structure disposed thereon, said gate stack structure being encapsulated by silicon nitride, and layered with an oxide;
• providing a hydrofluorocarbon gas into said high density etcher;
• selectively removing portions of said oxide by pulsing a fluorocarbon gas;
• wherein:
• said pulsing imparts a time varying flow rate to said fluorocarbon gas for a plurality of periods of said time varying flow rate, wherein said hydrofluorocarbon gas is pulsed in a range from about 0 sccm to about 25 sccm and is at least intermittently at a higher concentration than said fluorocarbon gas;
• said hydrofluorocarbon gas removes portions of said oxide;
• and
• said fluorocarbon gas forms a protective layer;
• and
• wherein the pulsing of said fluorocarbon gas causes said hydrofluorocarbon gas to have cyclical concentrations within said high density etcher.

A etching method comprising:

• forming a photoresist pattern on a microelectronics substrate that includes both an oxide layer and a nitride layer disposed on a silicon layer;
• providing an etch chamber and said microelectronics substrate disposed therein;
• pulsing into said etch chamber at least one gas suitable for forming a deposit on at least a portion of said microelectronics substrate, wherein:
• said deposit is selected from the group consisting of an oxide film, a resist, a multi-layer resist, a metal, a metal alloy, an aluminum alloy, a refractory metal, tungsten, an electrical conductor, polysilicon, and at least one polysilicide;
• said at least one gas comprises a gas selected from the group consisting of a halogenated hydrocarbon, and a fluorocarbon;
• said pulsing imparts a time varying flow rate to said gas for a plurality of periods of said time varying flow rate;
• said pulsing is applied at a duty cycle range selected from the group consisting of:
• from about 20% to about 80% duty cycle;
• from about 30% to about 70% duty cycle;
• and
• from about 40% to about 60% duty cycle;
• said time varying flow rate varies within a range selected from the group consisting of:
• between a high flow rate value of about 30 sccm to a low flow rate value of about 15 sccm;
• between a high flow rate value of about 27 sccm to a low flow rate value of about 18 sccm;
• between a high flow rate value of about 25 sccm to a low flow rate value of about 20 sccm;
• between a high flow rate value of about 20 sccm to a low flow rate value of about 30 sccm;
• and
• between a high flow rate value of about 15 sccm to a low flow rate value of about 20 sccm;
• etching said microelelectronics substrate with said a second gas during said pulsing, wherein:
• wherein said second gas is at least intermittently at a higher concentration than said first gas;
• said etching halts on said silicon layer;
• said second gas is selected from the group consisting of a polymer forming gas, a polymer etching gas, and a fluorocarbon;
• and
• said second gas selectively removes at least a portion of said oxide layer.

An etching method comprising:

• exposing a substrate to a plurality of gases, wherein at least one of said gases is pulsed and said pulsing imparts a time varying flow rate to said at least one gas for a plurality of periods of said time varying flow rate;
• and wherein
• at least one of said gases comprises an etchant gas selected from the group consisting of a hydrofluorocarbon and a fluorocarbon;
• and
• at least one of said gases comprises a polymer forming gas for depositing a protective layer, wherein said etchant gas is at least intermittently at a higher concentration than said polymer forming gas.

A method to control etch profile while etching a microelectronics substrate, the method comprising:

• providing an etch chamber and a microelectronics substrate disposed therein;
• pulsing into said etch chamber a carbon containing polymer gas suitable for;
• forming a deposit on at least a portion of said microelectronics substrate;
• and
• etching said microelelectronics substrate;
• wherein said pulsing imparts a time varying flow rate to said gas for a plurality of periods of said time varying flow rate, thereby causing said gas to alternately form a deposit on at least a portion of said microelectronics substrate and etch said microelelectronics substrate and wherein said pulsing is applied so that said carbon containing polymer gas does not reach steady state concentration within said etch chamber in said plurality of periods.

A method to provide increased gas flow rate tolerances while etching a microelectronics substrate, the method comprising:

• providing an etch chamber and a microelectronics substrate disposed therein;
• providing at least one gas for introduction into the etch chamber, the at least one gas capable of both etching the microelelectronics substrate and forming a deposit on a side surface of the microelectronics substrate, wherein use of the at least one gas at a uniform flow rate provides a desired etch profile in the microelectronics substrate at a flow rate selected within a first process window;
• and
• pulsing into the etch chamber the at least one gas wherein the pulsing imparts a time varying flow rate to the gas for a plurality of periods of the time varying flow rate, wherein the pulsing provides for the alternating steps of:
• etching the microelelectronics substrate with the at least one gas;
• and
• forming a deposit with the at least one gas on a side surface of the microelectronics substrate, the deposit preventing additional etching of the side surface of the microelelectronics substrate underneath the deposit;
• wherein the pulsing enables the selection of flow rates from within a second process window that is larger than the first process window while still providing the desired etch profile in the microelectronics substrate.