Method and system for selectively etching a dielectric material relative to silicon
AssigneeTokyo Electron Limited
InventorJulie A. Cook
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Abstract
A method and system for selectively and uniformly etching a dielectric layer with respect to silicon and polysilicon in a dry plasma etching system are described. The etch chemistry comprises the use of fluorohydrocarbons, such as CH2F2 and CHF3. High etch selectivity and acceptable uniformity can be achieved by selecting a process condition, including the flow rate of CH2F2 and the power coupled to the dry plasma etching system, such that a proper balance of active etching radicals and polymer forming radicals are formed within the etching plasma.
Claims26
A method of reducing a recess in a spacer etch process, comprising:
- disposing a silicon substrate having a spacer dielectric layer overlying a polysilicon feature on a substrate holder in a dry plasma etching system;
- selecting a process condition to have an etch selectivity between said spacer dielectric layer and said silicon substrate of greater than or equal to approximately 5-to-1, comprising:
- setting a pressure in said dry plasma etching system;
- introducing a process gas comprising a first flow rate of a noble gas, a second flow rate of CHF3, and a third flow rate of CH2F2;
- and
- setting a power to be coupled to an electrode in said dry plasma etching system to form plasma from said process gas;
- applying said process condition to said dry plasma etching system;
- and
- exposing said substrate to said process condition.
A computer readable medium containing program instructions for execution on a computer system, which when executed by the computer system, cause the computer system to perform the following steps:
- disposing a silicon substrate having a spacer dielectric layer overlying a polysilicon feature on a substrate holder in a dry plasma etching system;
- selecting a process condition to have an etch selectivity between said spacer dielectric layer and said silicon substrate of greater than or equal to approximately 5-to-1, comprising:
- setting a pressure in said dry plasma etching system;
- introducing a process gas comprising a first flow rate of a noble gas, a second flow rate of CHF3, and a third flow rate of CH2F2;
- and
- setting a power to be coupled to an electrode in said dry plasma etching system to form plasma from said process gas;
- applying said process condition to said dry plasma etching system;
- and
- exposing said substrate to said process condition.
A method of uniformly etching silicon oxide relative to silicon on a substrate placed in a dry plasma etching system, comprising:
- placing said substrate having said silicon oxide (SiOx) film on a substrate holder in said dry plasma etching system;
- introducing a reactive process gas to a process space in said dry plasma etching system, said reactive process gas comprising CH2F2 and CHF3;
- applying a first radio frequency (RF) signal to an electrode in said dry plasma etching system, wherein said first RF signal comprises a frequency greater than 20 MHz;
- selecting a ratio of a flow rate of said CH2F2 to a RF power coupled to said electrode that is substantially equal to or less than a value of 0.0071 sccm per Watt;
- and
- etching said silicon oxide film.
A computer readable medium containing program instructions for execution on a computer system, which when executed by the computer system, cause the computer system to perform the following steps:
- placing said substrate having said silicon oxide (SiOx) film on a substrate holder in said dry plasma etching system;
- introducing a reactive process gas to a process space in said dry plasma etching system, said reactive process gas comprising CH2F2 and CHF3;
- applying a first radio frequency (RF) signal to an electrode in said dry plasma etching system, wherein said first RF signal comprises a frequency greater than 20 MHz;
- selecting a ratio of a flow rate of said CH2F2 to a RF power coupled to said electrode that is substantially equal to or less than a value of 0.0071 sccm per Watt;
- and
- etching said silicon oxide film.
A dry plasma etching system, comprising:
- a process chamber configured to define a process space;
- a substrate holder coupled to said process chamber and configured to support a substrate in said process space;
- a process gas supply system coupled to said process chamber and configured to introduce a reactive process gas to a process space in said dry plasma etching system, said reactive process gas comprising CH2F2 and CHF3;
- a vacuum processing system coupled to said process chamber and configured to evacuate said process space;
- a power system coupled to an electrode in said process chamber and configured to couple radio frequency (RF) power to said process gas in order to form plasma in said process space;
- and
- a controller coupled to said process gas supply system and said power system and configured to set a ratio of a flow rate of said CH2F2 to a RF power coupled to said electrode that is substantially equal to or less than a value of 0.0071 sccm per Watt.
Dependencies are inferred from the claim text.