Plasma etching process for refractory metal vias

Claim 2

A process for etching a refractory metal from the surface of a dielectric layer formed on a substrate, said dielectric layer having openings formed therein, said openings exposing regions of said substrate, said refractory metal extending in said openings of said dielectric layer to contact said regions of said substrate, said process comprising the steps of: providing said substrate having said dielectric layer and said refractory metal on it; performing a first plasma etch of said refractory metal in a flow of a first mixture consisting essentially of SF 6 , O 2 , and He, wherein said first mixture contains substantially no Cl 2 with the total pressure of said first mixture being in the range of 600-800 mTorr; then performing a second plasma etch of said refractory metal in a second mixture consisting essentially of SF 6 , Cl 2 , and He, wherein said second mixture contains substantially no O 2 with the total pressure of said second mixture being in the range of 600-800 mTorr; and then performing a third plasma etch of said refractory metal in a flow of a third mixture consisting essentially of Cl 2 and He, wherein said third mixture contains substantially no SF 6 .

Claim 3

The process as described in claim 1 wherein said first etch is performed for a predetermined time, said second etch continues until an end point is detected by measurement of emission lines, and said third etch is performed for a predetermined time.

Claim 4

The process as described in claim 2 wherein said first etch is carried out at a power in the range of 300-500 Watts, said second etch is carried out at a power less than 300 Watts, said third etch is carried out at a power in the range of 150-300 Watts.

Claim 5

The process as described in claim 2 wherein said endpoint is detected by the measurement and integration of emission lines of chlorine, said lines comprising the 772 nm and 775 nm emission lines of chlorine.

Claim 6

The process as described in claim 4 wherein said first etch is carried out at a power in the range of 300-500 Watts, said second etch is carried out at a power less than 300 Watts, said third etch is carried out at a power in the range of 150-300 Watts.

Claim 7

The process as described in claim 4 wherein said flow of said SF 6 in said first etch is in the range of 100-300 Standard Cubic Centimeters per Minute (SCCM), said flow of said O 2 in said first etch is in the range of 10-50 SCCM, said flow of said He in said first etch is in the range of 100-200 SCCM, said flow of said SF 6 in said second etch is in the range of 100-200 SCCM, said flow of said Cl 2 in said second etch is in the range of 50-90 SCCM, said flow of said He in said second etch is in the range of 150-300 SCCM, said flow of said Cl 2 in said third etch is in the range of 100-200 SCCM, and said flow of said He in said third etch is in the range of 30-80 SCCM.

Claim 8

The process as described in claim 6 wherein said first etch is carried out at a power in the range of 300-500 Watts, said second etch is carried out at a power less than 300 Watts, said third etch is carried out at a power in the range of 150-300 Watts.

Claim 9

The process as described in claim 2 wherein said flow of said SF 6 in said first etch is in the range of 100-300 Standard Cubic Centimeters per Minute (SCCM), said flow of said O 2 in said first etch is in the range of 10-50 SCCM, said flow of said He in said first etch is in the range of 100-200 SCCM, said flow of said SF 6 in said second etch is in the range of 100-200 SCCM, said flow of said Cl 2 in said second etch is in the range of 50-90 SCCM, said flow of said He in said second etch is in the range of 150-300 SCCM, said flow of said Cl 2 in said third etch is in the range of 100-200 SCCM, and said flow of said He in said third etch is in the range of 30-80 SCCM.

Claim 10

The process as described in claim 8 wherein said first etch is carried out at a power in the range of 300-500 Watts, said second etch is carried out at a power less than 300 Watts, said third etch is carried out at a power in the range of 150-300 Watts.

Claim 11

The process as described in claim 1 wherein said flow of said SF 6 in said first etch is in the range of 100-300 Standard Cubic Centimeters per Minute (SCCM), said flow of said O 2 in said first etch is in the range of 10-50 SCCM, said flow of said He in said first etch is in the range of 100-200 SCCM, said flow of said SF 6 in said second etch is in the range of 100-200 SCCM, said flow of said Cl 2 in said second etch is in the range of 50-90 SCCM, said flow of said He in said second etch is in the range of 150-300 SCCM, said flow of said Cl 2 in said third etch is in the range of 100-200 SCCM, and said flow of said He in said third etch is in the range of 30-80 SCCM.

Claim 12

The process as described in claim 10 wherein said first etch is carried out at a power in the range of 300-500 Watts, said second etch is carried out at a power less than 300 Watts, said third etch is carried out at a power in the range of 150-300 Watts.

Claim 13

The process as described in claim 1 wherein said first etch is carried out at a power in the range of 300-500 Watts, said second etch is carried out at a power less than 300 Watts, said third etch is carried out at a power in the range of 150-300 Watts.

Claim 14

The process as described in any one of claims 1 through 12 wherein said refractory metal is Tungsten (W).

Claim 15

A process for filling openings in a dielectric formed on a substrate, said openings exposing an underlying region on said substrate, said process comprising the steps of: providing said substrate having a dielectric on it; depositing a refractory metal on said dielectric and said underlying region to cover said dielectric and said underlying region; etching said refractory metal covering said dielectric, said etch comprising the steps of: performing a first plasma etch of said refractory metal in a flow of a first mixture consisting essentially of SF 6 , O 2 , and He, wherein said first mixture contains substantially no Cl 2 with the total pressure of said first mixture being in the range of 600-800 mTorr; then performing a second plasma etch of said refractory metal in a flow of a second mixture consisting essentially of SF 6 , Cl 2 , and He, wherein said second mixture contains substantially no O 2 with the total pressure of said second mixture being in the range of 600-800 mTorr; and then performing a third plasma etch of said refractory metal in a flow of a third mixture of process gases consisting essentially of Cl 2 and He, wherein said third mixture contains substantially no SF 6 .

Claim 16

A process for filling openings in a dielectric formed on a substrate, said openings exposing an underlying region on said substrate, said process comprising the steps of: providing said substrate having a dielectric on it; depositing a refractory metal on said dielectric and said underlying region to cover said dielectric and said underlying region; etching said refractory metal covering said dielectric, said etch comprising the steps of: performing a first plasma etch of said refractory metal in a flow of a first mixture consisting essentially of SF 6 , O 2 , and He, wherein said first mixture contains substantially no Cl 2 with the total pressure of said first mixture being in the range of 600-800 mTorr; then performing a second plasma etch of said refractory metal in a flow of a second mixture consisting essentially of SF 6 , Cl 2 , and He, wherein said second mixture contains substantially no O 2 with the total pressure of said second mixture being in the range of 600-800 mTorr; and then performing a third plasma etch of said refractory metal in a flow of a third mixture of process gases consisting essentially of Cl 2 and He, wherein said third mixture contains substantially no SF 6 .

Claim 17

The process as described in claim 14 wherein said flow of said SF 6 in said first etch is in the range of 100-300 Standard Cubic Centimeters per Minute (SCCM), said flow of said O 2 in said first etch is in the range of 10-50 SCCM, said flow of said He in said first etch is in the range of 100-200 SCCM, said flow of said SF 6 in said second etch is in the range of 100-200 SCCM, said flow of said Cl 2 in said second etch is in the range of 50-90 SCCM, said flow of said He in said second etch is in the range of 150-300 SCCM, said flow of said Cl 2 in said third etch is in the range of 100-200 SCCM, and said flow of said He in said third etch is in the range of 30-80 SCCM.

Claim 18

The process as described in claim 15 wherein said first etch is carried out at a power in the range of 300-500 Watts, said second etch is carried out at a power less than 300 Watts, said third etch is carried out at a power in the range of 150-300 Watts.

Claim 19

The process as described in claim 14 wherein said first etch is carried out at a power in the range of 300-500 Watts, said second etch is carried out at a power less than 300 Watts, said third etch is carried out at a power in the range of 150-300 Watts.

Claim 20

The process as described in claim 14 wherein said first etch is performed for a predetermined time, said second etch continues until an end point is detected by measurement of emission lines, and said third etch is performed for a predetermined time.

Claim 21

The process as described in claim 18 wherein said first etch is carried out at a power in the range of 300-500 Watts, said second etch is carried out at a power less than 300 Watts, said third etch is carried out at a power in the range of 150-300 Watts.

Claim 22

The process as described in claim 18 wherein said flow of said SF 6 in said first etch is in the range of 100-300 Standard Cubic Centimeters per Minute (SCCM), said flow of said O 2 in said first etch is in the range of 10-50 SCCM, said flow of said He in said first etch is in the range of 100-200 SCCM, said flow of said SF 6 in said second etch is in the range of 100-200 SCCM, said flow of said Cl 2 in said second etch is in the range of 50-90 SCCM, said flow of said He in said second etch is in the range of 150-300 SCCM, said flow of said Cl 2 in said third etch is in the range of 100-200 SCCM, and said flow of said He in said third etch is in the range of 30-80 SCCM.

Claim 23

The process as described in claim 20 wherein said first etch is carried out at a power in the range of 300-500 Watts, said second etch is carried out at a power less than 300 Watts, said third etch is carried out at a power in the range of 150-300 Watts.

Claim 24

The process as described in claim 18 wherein said endpoint is detected by the measurement and integration of emission lines of chlorine, said lines comprising the 772 nm and 775 nm emission lines of chlorine.

Claim 25

The process as described in claim 22 wherein said first etch is carried out at a power in the range of 300-500 Watts, said second etch is carried out at a power less than 300 Watts, said third etch is carried out at a power in the range of 150-300 Watts.

Claim 26

The process as described in claim 22 wherein said flow of said SF 6 in said first etch is in the range of 100-300 Standard Cubic Centimeters per Minute (SCCM), said flow of said O 2 in said first etch is in the range of 10-50 SCCM, said flow of said He in said first etch is in the range of 100-200 SCCM, said flow of said SF 6 in said second etch is in the range of 100-200 SCCM, said flow of said Cl 2 in said second etch is in the range of 50-90 SCCM, said flow of said He in said second etch is in the range of 150-300 SCCM, said flow of said Cl 2 in said third etch is in the range of 100-200 SCCM, and said flow of said He in said third etch is in the range of 30-80 SCCM.

Claim 27

The process as described in claim 24 wherein said first etch is carried out at a power in the range of 300-500 Watts, said second etch is carried out at a power less than 300 Watts, said third etch is carried out at a power in the range of 150-300 Watts.

Claim 28

The process as described in any one of claims 14-25 wherein said refractory metal is Tungsten (W).