# US 10,865,484 B2 · Solution and method for etching titanium based materials

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- Number: US 10,865,484 B2
- Document ID: US10865484B2
- Status: Granted
- Kind: B2
- Application number: 16/089,572
- Filed: 2017-03-29
- Published: 2019-05-02
- Granted: 2020-12-15
- Earliest claimed: 2016-03-29
- Assignees: Technic France
- Applicants: Technic France
- Inventors: Christian Pizzetti; Marine Cazes; Jérôme Daviot; Philippe Vernin
- Web page: https://patentgrep.com/patent/US10865484B2

## CPC

- C23F 1/38: for etching refractory metals
- C09K 13/02: containing an alkali metal hydroxide
- C23G 1/205: {refractory metals}
- H10P 50/667: {by liquid etching only}
- C23F: NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE (working metal by laser beams B23K26/00; desurfacing by applying flames B23K7/00; working of metal by electro-erosion B23H; producing decorative effects by removing surface material, e.g. by engraving, by etching, B44C1/22; electrolytic etching or polishing C25F); INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
- C09K: MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C23G: CLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10

## Abstract

The invention relates to a solution for etching titanium based materials, comprising from about 27 w % to about 39 w % hydrogen peroxide, from about 0.2 w % to about 0.5 w % potassium hydroxide, and at about 0.002 w % to about 0.02 w % 1,2-Diaminocyclohexane-N,N,N,N Tetra acetic Acid (CDTA), the rest being water, said solution comprising no corrosion inhibitor, and said solution having a pH comprised between about 7 and about 8. The invention further relates to a chemical composition for preparing such a solution by mixing said composition with concentrated hydrogen peroxide, said chemical composition comprising potassium hydroxide from about 5 w % to about 30 w %, C.D.T.A. at a concentration ranging from about 1% to about 5% of the potassium hydroxide concentration, the rest being water. The invention also relates to a method of etching a Titanium, Titanium nitride or Titanium Tungsten barrier layer from a microelectronic device, said method comprising contacting the Titanium, Titanium nitride or Titanium tungsten barrier layer with the solution for a time sufficient to remove the Titanium, Titanium nitride or Titanium tungsten barrier layer.

## Claims

### Claim 1

A solution for etching titanium based materials, consisting of from about 27 wt. % to about 39 wt. % of hydrogen peroxide, from about 0.2 wt. % to about 0.5 wt. % of potassium hydroxide, and from about 0.002 wt. % to about 0.02 wt. % of 1,2-Diaminocyclohexane-N,N,N,N Tetra acetic Acid (CDTA), and
the rest being water,
wherein said solution comprises no corrosion inhibitor, and has a pH of between about 7 and about 8.

### Claim 2 (depends on 1)

The solution of claim 1, said etching solution being prepared by mixing (i) a concentrate made of potassium hydroxide at a concentration ranging from about 5 wt. % to about 30 wt. %, C.D.T.A at a concentration ranging from about 1% to about 4% of potassium hydroxide concentration, with (ii) hydrogen peroxide at a starting concentration ranging from about 30 wt. % to about 40 wt. %, so as to reach a pH comprised between about 7 and about 8.

### Claim 3 (depends on 1)

A chemical composition for preparing a solution according to claim 1 by mixing said chemical composition with concentrated hydrogen peroxide, said chemical composition comprising potassium hydroxide from about 5 wt. % to about 30 wt. %, C.D.T.A. at a concentration ranging from about 1% to about 5% of the potassium hydroxide concentration, the rest being water.

### Claim 4 (depends on 1)

A method of etching a Titanium, Titanium nitride or Titanium Tungsten barrier layer from a microelectronic device, said method comprising contacting the Titanium, Titanium nitride or Titanium tungsten barrier layer with the solution of claim 1, for a time sufficient to remove the Titanium, Titanium nitride or Titanium tungsten barrier layer.

### Claim 5 (depends on 4)

The method of claim 4, wherein the solution is prepared using a point of use blending technique to mix concentrated hydrogen peroxide at a starting concentration ranging from 30 wt. % to 40 wt. % with a chemical composition comprising potassium hydroxide from about 5 wt. % to about 30 wt. %, C.D.T.A at a concentration ranging from about 1% to about 5% of the potassium hydroxide concentration, the rest being water, at an appropriate ratio so as to reach a pH comprised between about 7 and about 8.

### Claim 6 (depends on 4)

The method of claim 4, wherein the etching solution is disposed to waste drain right after dispense on the microelectronic device, or redirected to a chemical tank, for several hours or several substrates being etched.

### Claim 7 (depends on 4)

The method of claim 4, wherein the etching solution is heated and contacted with the microelectronic device at a temperature comprised between about 15° C. and about 60° C., preferably between about 20° C. and about 50° C.

### Claim 8 (depends on 1)

A method for preparing an etching solution according to claim 1, comprising mixing a chemical composition comprising potassium hydroxide from about 5 wt. % to about 30 wt. %, C.D.T.A at a concentration ranging from about 1% to about 5% of the potassium hydroxide concentration, the rest being water, with concentrated hydrogen peroxide at a starting concentration ranging from 30 wt. % to 40 wt. % so as to reach a pH comprised between 7 and 8.