# US 2014/0154889 A1 · Dry-etch for selective tungsten removal

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- Number: US 2014/0154889 A1
- Document ID: US20140154889A1
- Status: Published application
- Kind: A1
- Application number: 13/840,206
- Filed: 2013-03-15
- Published: 2014-06-05
- Earliest claimed: 2012-11-30
- Assignees: Applied Materials, Inc.
- Applicants: Applied Materials, Inc.
- Inventors: Xikun Wang; Ching-Mei Hsu; Nitin K. Ingle; Zihui Li; Anchuan Wang
- Web page: https://patentgrep.com/patent/US20140154889A1

## CPC

- H10P 50/242: {of Group IV materials}
- H01J 37/32357: {Generation remote from the workpiece, e.g. down-stream}
- H10P 50/267: {using plasmas}
- H10P 70/125: {with gaseous HF}
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
- H01J: ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS (spark-gaps H01T; electric arc lamps H05B31/00; particle accelerators H05H)

## Abstract

Methods of selectively etching tungsten relative to silicon-containing films (e.g. silicon oxide, silicon carbon nitride and (poly)silicon) as well as tungsten oxide are described. The methods include a remote plasma etch formed from a fluorine-containing precursor and/or hydrogen (H2). Plasma effluents from the remote plasma are flowed into a substrate processing region where the plasma effluents react with the tungsten. The plasma effluents react with exposed surfaces and selectively remove tungsten while very slowly removing other exposed materials. Sequential and simultaneous methods are included to remove thin tungsten oxide which may, for example, result from exposure to the atmosphere.

## Claims

### Claim 1

A method of etching a patterned substrate in a substrate processing region of a substrate processing chamber, wherein the patterned substrate has a exposed tungsten region and an exposed second material region, the method comprising:
flowing a fluorine-containing precursor into a remote plasma region fluidly coupled to the substrate processing region while forming a plasma in the plasma region to produce plasma effluents; and
etching the exposed tungsten from the substrate by flowing the plasma effluents into the substrate processing region through through-holes in a showerhead.

### Claim 2 (depends on 1)

The method of claim 1 wherein the exposed tungsten region has a thickness of at least 5 nm.

### Claim 3 (depends on 1)

The method of claim 1 wherein the exposed tungsten region consists of tungsten.

### Claim 4 (depends on 1)

The method of claim 1 wherein etching the exposed tungsten region comprises etching the exposed tungsten region comprises etching tungsten with a tungsten etch rate greater than ten times the etch rate of the exposed second material region.

### Claim 5 (depends on 1)

The method of claim 1 wherein the operation of etching the tungsten comprises etching tungsten faster than silicon by a ratio of about 100:1 or more, faster than silicon oxide by a ratio of about 15:1 or more, faster than silicon carbon nitride by a ratio of about 3:1 or more or faster than tungsten oxide by a ratio of about 10:1 or more.

### Claim 6 (depends on 1)

The method of claim 1 wherein the fluorine-containing precursor comprises nitrogen trifluoride.

### Claim 7 (depends on 1)

The method of claim 1 wherein the fluorine-containing precursor comprises a partially fluorinated hydrocarbon.

### Claim 8 (depends on 1)

The method of claim 1 wherein the fluorine-containing precursor comprises methyl fluoride.

### Claim 9 (depends on 1)

The method of claim 1 further comprising a pretreatment step which occurs prior to etching the exposed tungsten region, wherein the pretreatment step comprises flowing hydrogen (H2) into the remote plasma region and flowing the produced plasma effluents into the substrate processing region to remove a thin tungsten oxide layer overlying a near-surface tungsten region to create the exposed tungsten region.

### Claim 10 (depends on 1)

The method of claim 1 wherein the fluorine-containing precursor comprises carbon tetrafluoride.

### Claim 11 (depends on 1)

The method of claim 1 wherein flowing a fluorine-containing precursor and hydrogen (H2) results in an atomic flow ratio (H:F) of greater than 1:1 entering the substrate processing region.

### Claim 12 (depends on 1)

The method of claim 1 wherein flowing a fluorine-containing precursor and hydrogen (H2) results in an atomic flow ratio (H:F) of less than 15:1 entering the substrate processing region.

### Claim 13 (depends on 1)

The method of claim 1 wherein a pressure within the substrate processing region is between about 0.01 Torr and about 50 Torr during the etching operation.

### Claim 14 (depends on 1)

The method of claim 1 wherein forming a plasma in the plasma region to produce plasma effluents comprises applying RF power between about 10 watts and about 400 watts to the plasma region.

### Claim 15 (depends on 1)

The method of claim 1 wherein a temperature of the substrate is greater than or about −30° C. and less than or about 400° C. during the etching operation.