# US 10,870,799 B2 · Etching solution for selectively removing tantalum nitride over titanium nitride during manufacture of a semiconductor device

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- Number: US 10,870,799 B2
- Document ID: US10870799B2
- Status: Granted
- Kind: B2
- Application number: 16/108,529
- Filed: 2018-08-22
- Published: 2019-03-21
- Granted: 2020-12-22
- Earliest claimed: 2017-08-25
- Assignees: Versum Materials US, LLC
- Applicants: Versum Materials US, LLC
- Inventors: Wen Dar Liu; Yi-Chia Lee
- Web page: https://patentgrep.com/patent/US10870799B2

## CPC

- C09K 13/08: containing a fluorine compound
- C09K 13/06: with organic material
- H10D 84/0128: {Manufacturing their channels}
- H10D 84/0135: {Manufacturing their gate conductors}
- H10D 84/0158: {the components including FinFETs}
- H10D 84/038: {using silicon technology, e.g. SiGe}
- H10P 50/642: {Chemical etching}
- H10P 50/667: {by liquid etching only}
- C09K: MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10

## Abstract

Described herein is an etching solution comprising water; phosphoric acid solution (aqueous); a fluoride ion source; and a water-miscible organic solvent. Such compositions are useful for the selective removal of tantalum nitride over titanium nitride from a microelectronic device having such material(s) thereon during its manufacture.

## Claims

### Claim 1

An etching composition suitable for the selective removal of tantalum nitride over titanium nitride from a microelectronic device, which comprises:
from about 40% to about 80% by weight water;
from about 10% to about 50% by weight phosphorous-containing inorganic acid or salt thereof (neat);
from about 0.1% to about 6% by weight fluoride ion source (neat); and
from about 12% to about 35% by weight water-miscible organic solvent, wherein said etching solution is substantially free of oxidizing agents.

### Claim 2 (depends on 1)

The etching composition of claim 1 wherein the water-miscible solvent is selected from the group consisting of ethylene glycol, propylene glycol, butyl diglycol, 1,4-butanediol, tripropylene glycol methyl ether, propylene glycol propyl ether, diethylene gycol n-butyl ether, hexyloxypropylamine, poly(oxyethylene)diamine, dimethylsulfoxide, tetrahydrofurfuryl alcohol, glycerol, alcohols, sulfoxides, or mixtures thereof.

### Claim 3 (depends on 1)

The etching composition of claim 1 wherein the water-miscible solvent is selected from the group consisting of butyl diglycol, glycerol or propylene glycol or mixtures thereof.

### Claim 4 (depends on 1)

The etching composition of claim 1 wherein the fluoride ion source is selected from the group consisting of hydrofluoric acid, ammonium fluoride, quaternary ammonium fluorides such as, for example, fluoroborates, fluoroboric acid, tetrabutylammonium tetrafluoroborate, aluminum hexafluoride, and a fluoride salt of an aliphatic primary, secondary or tertiary amine having the formula:
R1NR2R3R4F,
wherein R1, R2, R3 and R4 individually represent H or a (C1-C4) alkyl group.

### Claim 5 (depends on 4)

The etching composition of claim 4 wherein the fluoride ion source is selected from the group consisting of ammonium fluoride, ammonium bifluoride, tetramethylammonium fluoride, tetraethylammonium fluoride, methyltriethylammonium fluoride, and tetrabutylammonium fluoride and mixtures thereof.

### Claim 6 (depends on 5)

The etching composition of claim 5 wherein said fluoride ion source comprises ammonium fluoride.

### Claim 7 (depends on 1)

The etching composition of claim 1 wherein the phosphorous-containing inorganic acid is selected from the group consisting of phosphoric acid (H3PO4), hypophosphorus acid (H3PO2), phosphorus acid (H3PO3), hypophosphoric acid (H4P2O6), metaphosphoric acid (HPO3), peroxophosphoric acid (H3PO5), pyrophosphoric acid (H4P2O7), tripolyphosphoric acid (H5P3O10), tetrapolyphosphoric acid (H6P4O13), trimetaphosphoric acid (H3P3O9), and phosphoric anhydride (P4O10), and salts thereof and mixtures thereof.

### Claim 8 (depends on 1)

The etching composition of claim 1 wherein the phosphorous-containing inorganic acid comprises phosphoric acid (H3PO4).

### Claim 9 (depends on 1)

The etching composition of claim 1 wherein the composition comprises
from about 50% to about 80% by weight water;
from about 10% to about 30% by weight of said phosphorous-containing inorganic acid or salt thereof (neat); and
from about 0.6% to about 5% by weight fluoride ion source (neat).

### Claim 10 (depends on 1)

The etching composition of claim 1 wherein the composition comprises
from about 50% to about 70% by weight water;
from about 10% to about 25% by weight of said phosphorous-containing inorganic acid or salt thereof (neat);
from about 1% to about 5% by weight fluoride ion source (neat); and
from about 20% to about 30% by weight water-miscible organic solvent.

### Claim 11 (depends on 1)

The etching composition of claim 1 wherein the composition comprises
from about 55% to about 65% by weight water;
from about 10% to about 20% by weight of said phosphorous-containing inorganic acid or salt thereof (neat);
from about 1% to about 5% by weight fluoride ion source (neat); and
from about 20% to about 30% by weight water-miscible organic solvent.

### Claim 12 (depends on 1)

The etching composition of claim 1 wherein the composition provides a tantalum nitride over titanium nitride etch selectivity of at least 5.

### Claim 13

A method of selectively enhancing the etch rate of tantalum nitride relative to titanium nitride on a microelectronic device comprising tantalum nitride and titanium nitride, the method comprising the steps of:
contacting the microelectronic device comprising tantalum nitride and titanium nitride with an etching composition comprising from about 40% to about 80% by weight water; from about 10% to about 50% by weight phosphorous-containing inorganic acid or salt thereof (neat); from about 0.1% to about 6% by weight fluoride ion source (neat); and from about 12% to about 35% by weight water-miscible organic solvent; wherein said etching solution is substantially free of oxidizing agents; and
rinsing the microelectronic device after the tantalum nitride is at least partially removed, wherein the selectivity of the etch for tantalum nitride over titanium nitride is greater than 3.

### Claim 14 (depends on 13)

The method of claim 13 further comprising the step of drying the microelectronic device.

### Claim 15 (depends on 13)

The method of claim 13 wherein the selectivity of the etch for tantalum nitride over titanium nitride is between about 9 and about 125.

### Claim 16 (depends on 13)

The method of claim 13 wherein the contacting step is performed at a temperature of from about 25° C. to about 150° C.

### Claim 17 (depends on 13)

The method of claim 13 wherein the water-miscible solvent is selected from the group consisting of ethylene glycol, propylene glycol, butyl diglycol, 1,4-butanediol, tripropylene glycol methyl ether, propylene glycol propyl ether, diethylene gycol n-butyl ether, hexyloxypropylamine, poly(oxyethylene)diamine, dimethylsulfoxide, tetrahydrofurfuryl alcohol, glycerol, alcohols, sulfoxides, or mixtures thereof.

### Claim 18 (depends on 13)

The method of claim 13 wherein the fluoride ion source is selected from the group consisting of hydrofluoric acid, ammonium fluoride, quaternary ammonium fluorides such as, for example, fluoroborates, fluoroboric acid, tetrabutylammonium tetrafluoroborate, aluminum hexafluoride, and a fluoride salt of an aliphatic primary, secondary or tertiary amine having the formula:
R1NR2R3R4F,
wherein R1, R2, R3 and R4 individually represent H or a (C1-C4) alkyl group.

### Claim 19 (depends on 13)

The method of claim 13 wherein the fluoride ion source is selected from the group consisting of ammonium fluoride, ammonium bifluoride, tetramethylammonium fluoride, tetraethylammonium fluoride, methyltriethylammonium fluoride, and tetrabutylammonium fluoride.

### Claim 20 (depends on 13)

The method of claim 13 wherein the phosphorous-containing inorganic acid is selected from the group consisting of hypophosphorus acid (H3PO2), phosphorus acid (H3PO3), hypophosphoric acid (H4P2O6), metaphosphoric acid (HPO3), peroxophosphoric acid (H3PO5), pyrophosphoric acid (H4P2O7), tripolyphosphoric acid (H5P3O10), tetrapolyphosphoric acid (H6P4O13), trimetaphosphoric acid (H3P3O9), and phosphoric anhydride (P4O10), and salts thereof and mixtures thereof.

### Claim 21 (depends on 1)

The etching composition of claim 1 wherein the composition is substantially free of hydrogen fluoride.

### Claim 22 (depends on 3)

The etching composition of claim 3 wherein the phosphorous-containing inorganic acid comprises phosphoric acid (H3PO4) and wherein said fluoride ion source comprises ammonium fluoride.