US5880033A — Method for etching metal silicide with high selec…

Claim 1

Independent Claim 109 words

A method for etching a substrate comprising metal silicide and polysilicon layers, the method comprising the steps of: (a) placing the substrate in a plasma zone; (b) introducing into the plasma zone, a process gas comprising Cl 2 , O 2 and N 2 and forming a plasma from the process gas, wherein the volumetric flow ratio of Cl 2 , O 2 , and N 2 is selected to etch the metal silicide layer at a first etch rate that is at least 1.2 times higher than a second rate of etching of the polysilicon layer, while providing substantially anisotropic etching of the metal silicide and polysilicon layers.

Claim 2

Independent Claim 109 words

A method for etching a substrate comprising metal silicide and polysilicon layers, the method comprising the steps of: (a) placing the substrate in a plasma zone; (b) introducing into the plasma zone, a process gas comprising Cl 2 , O 2 and N 2 and forming a plasma from the process gas, wherein the volumetric flow ratio of Cl 2 , O 2 , and N 2 is selected to etch the metal silicide layer at a first etch rate that is at least 1.2 times higher than a second rate of etching of the polysilicon layer, while providing substantially anisotropic etching of the metal silicide and polysilicon layers.

Claim 3

Dependent Claim 51 words

The method of claim 1, wherein the volumetric flow ratio of Cl 2 , O 2 , and N 2 is selected to etch the metal silicide and polysilicon layers to form etched features that have sidewalls that form angles of at least about 88° with a surface of the substrate.

Claim 4

Dependent Claim 22 words

The method of claim 1, wherein the volumetric flow ratio of O 2 :N 2 is from about 0.25:1 to about 5:1.

Claim 5

Dependent Claim 22 words

The method of claim 3, wherein the volumetric flow ratio of O 2 :N 2 is from about 0.5:1 to about 3:1.

Claim 6

Dependent Claim 33 words

The method of claim 1, wherein the ratio of the volumetric flow of Cl 2 to the combined volumetric flow of O 2 and N 2 is from about 5:1 to about 20:1.

Claim 7

Dependent Claim 33 words

The method of claim 5, wherein the ratio of the volumetric flow of Cl 2 to the combined volumetric flow of O 2 and N 2 is from about 7:1 to about 15:1.

Claim 8

Dependent Claim 22 words

The method of claim 1, wherein the process gas consists essentially of Cl 2 , O 2 , and N 2 .

Claim 9

Dependent Claim 20 words

The method of claim 1, wherein the flow rate of Cl 2 is from about 20 to about 800 sccm.

Claim 10

Dependent Claim 20 words

The method of claim 1, wherein the flow rate of N 2 is from about 4 to about 60 sccm.

Claim 11

Dependent Claim 20 words

The method of claim 1, wherein the flow rate of O 2 is from about 0.1 to about 40 sccm.

Claim 12

Dependent Claim 36 words

The method of claim 1, wherein in step (b), the plasma is formed by applying a current at a power level of about 200 to 2000 Watts to an inductor coil adjacent to the plasma zone.

Claim 13

Dependent Claim 37 words

The method of claim 1, wherein in step (b), the plasma is attracted to the substrate by applying a voltage at a power level of about 5 to 500 Watts to process electrodes in the plasma zone.

Claim 14

Dependent Claim 18 words

The method of claim 1, wherein the plasma zone is maintained at a pressure 0.1 to 100 mTorr.

Claim 15

Independent Claim 180 words

A method of etching a substrate comprising metal silicide and polysilicon layers, the method comprising the steps of: (a) placing the substrate in a process chamber comprising (i) process electrodes therein, and (ii) an inductor coil adjacent to the process chamber; (b) introducing into the process chamber, process gas comprising Cl 2 , O 2 , and N 2 ; and (c) ionizing the process gas to form plasma ions that energetically impinge on the substrate by (i) applying RF current at a first power level to the inductor coil, and (ii) applying a RF voltage at a second power level to the process electrodes, wherein the volumetric ratio of Cl 2 , O 2 , and N 2 , and a power ratio P r of the first power level to the second power level are selected so that the metal silicide layer is etched at a first etch rate that is at least 1.2 times higher than a second rate of etching of the polysilicon layer, while providing substantially anisotropic etching of the metal silicide and polysilicon layers.

Claim 16

Independent Claim 180 words

A method of etching a substrate comprising metal silicide and polysilicon layers, the method comprising the steps of: (a) placing the substrate in a process chamber comprising (i) process electrodes therein, and (ii) an inductor coil adjacent to the process chamber; (b) introducing into the process chamber, process gas comprising Cl 2 , O 2 , and N 2 ; and (c) ionizing the process gas to form plasma ions that energetically impinge on the substrate by (i) applying RF current at a first power level to the inductor coil, and (ii) applying a RF voltage at a second power level to the process electrodes, wherein the volumetric ratio of Cl 2 , O 2 , and N 2 , and a power ratio P r of the first power level to the second power level are selected so that the metal silicide layer is etched at a first etch rate that is at least 1.2 times higher than a second rate of etching of the polysilicon layer, while providing substantially anisotropic etching of the metal silicide and polysilicon layers.

Claim 17

Dependent Claim 22 words

The method of claim 14, wherein the volumetric flow ratio of O 2 :N 2 is from about 0.25:1 to about 5:1.

Claim 18

Dependent Claim 22 words

The method of claim 15, wherein the volumetric flow ratio of O 2 :N 2 is from about 0.5:1 to about 3:1.

Claim 19

Dependent Claim 33 words

The method of claim 14, wherein the ratio of the volumetric flow of Cl 2 to the combined volumetric flow of O 2 and N 2 is from about 5:1 to about 20:1.

Claim 20

Dependent Claim 33 words

The method of claim 17, wherein the ratio of the volumetric flow of Cl 2 to the combined volumetric flow of O 2 and N 2 is from about 7:1 to about 15:1.

Claim 21

Dependent Claim 28 words

The method of claim 14, wherein the power ratio P r of the first power level to the second power level is from about 0.1:1 to about 100:1.

Claim 22

Dependent Claim 18 words

The method of claim 14, wherein the first power level is from about 200 to about 2000 Watts.

Claim 23

Dependent Claim 17 words

The method of claim 14, wherein the second power level is about 5 to about 500 Watts.

Claim 24

Independent Claim 186 words

A method of etching a substrate surface comprising metal silicide and polysilicon layers, the method comprising the steps of: (a) placing the substrate surface facing a plasma zone comprising a ceiling having an apex with a height H of about 100 mm to about 175 mm above the substrate surface, the plasma zone having process electrodes and an inductor coil for energizing a plasma; and (b) energizing a quasi-remote plasma in the plasma zone by introducing into the plasma zone, a process gas comprising Cl 2 , O 2 , and N 2 , and applying RF current at a first power level to the inductor coil and RF voltage at a second power level to the process electrodes, wherein the volumetric ratio of Cl 2 , O 2 , and N 2 , and the power ratio P r of the first power level to the second power level are selected to form a quasi-remote plasma for anisotropically etching the metal silicide layer at a first etch rate that is at least 1.2 times higher than a second rate of etching of the polysilicon layer.

Claim 25

Independent Claim 186 words

A method of etching a substrate surface comprising metal silicide and polysilicon layers, the method comprising the steps of: (a) placing the substrate surface facing a plasma zone comprising a ceiling having an apex with a height H of about 100 mm to about 175 mm above the substrate surface, the plasma zone having process electrodes and an inductor coil for energizing a plasma; and (b) energizing a quasi-remote plasma in the plasma zone by introducing into the plasma zone, a process gas comprising Cl 2 , O 2 , and N 2 , and applying RF current at a first power level to the inductor coil and RF voltage at a second power level to the process electrodes, wherein the volumetric ratio of Cl 2 , O 2 , and N 2 , and the power ratio P r of the first power level to the second power level are selected to form a quasi-remote plasma for anisotropically etching the metal silicide layer at a first etch rate that is at least 1.2 times higher than a second rate of etching of the polysilicon layer.

Claim 26

Dependent Claim 33 words

The method of claim 22 wherein the ratio of the volumetric flow of Cl 2 to the combined volumetric flow of O 2 and N 2 is from about 5:1 to about 20:1.

Claim 27

Dependent Claim 22 words

The method of claim 23 wherein the volumetric flow ratio of O 2 :N 2 is from about 0.25:1 to about 5:1.

Claim 28

Dependent Claim 22 words

The method of claim 22 wherein the process gas consists essentially of Cl 2 , O 2 , and N 2 .

Claim 29

Dependent Claim 66 words

The method of claim 25 wherein the plasma zone comprises a volume of about 10,000 to about 50,000 cm 3 , and wherein the flow rate of Cl 2 is from about 20 to about 800 sccm, the flow rate of N 2 is from about 4 to about 60 sccm, and the flow rate of O 2 is from about 0.1 to about 40 sccm.

Claim 30

Dependent Claim 49 words

The method of claim 22 wherein the plasma is energized by applying a current at a power level of about 200 to about 2000 Watts to the inductor coil, and applying a voltage at a power level of about 5 Watts to about 500 Watts to the process electrodes.

Claim 31

Dependent Claim 40 words

The method of claim 22 wherein the plasma zone comprises a multi-radius dome ceiling and the quasi-remote plasma is formed between the substrate surface and the dome ceiling to provide a uniform distribution of plasma ions across the substrate surface.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	2002-03-08	2002-09-07	2003-03-09	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	2006-03-08	2006-09-07	2007-03-09	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2010-03-08	2010-09-07	2011-03-09	$7700.00	Window Closed / Lapsed

Method for etching metal silicide with high selectivity to polysilicon

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