Hard mask films with graded vertical concentration formed using reactive sputtering in a radio frequency deposition chamber

Patent metadata

Field	Value
Publication number	US-10975464-B2
Application number	US-201815948007-A
Country	US
Kind code	B2
Filing date	Apr 9, 2018
Priority date	Apr 9, 2018
Publication date	Apr 13, 2021
Grant date	Apr 13, 2021

Abstract

A method of forming a semiconductor structure includes, in a radio frequency (RF) deposition chamber, depositing a titanium film using physical vapor deposition and forming a graded hard mask film by reactive sputtering the titanium film with nitrogen in the RF deposition chamber. The graded hard mask film is a titanium nitride film with a graded vertical concentration of nitrogen. The method may further include, during deposition of the titanium film and during formation of the graded hard mask film, modulating one or more parameters of the RF deposition chamber, such as modulating an auto capacitance tuner (ACT) current, modulating the RF power, and modulating the pressure of the RF deposition chamber.

First claim

What is claimed is:

1. A method of forming a semiconductor structure comprising:
in a radio frequency (RF) deposition chamber, depositing a titanium film using physical vapor deposition;
forming a graded hard mask film by reactive sputtering the titanium film with nitrogen in the RF deposition chamber; and
modulating an auto capacitance tuner (ACT) current of the RF deposition chamber in a range of 2 to 4 amperes, an RF power of the RF deposition chamber in a range of 3 to 4 kilowatts, and a pressure of the RF deposition chamber in a range of 150 to 200 millitorrs during formation of the graded hard mask film to reduce resulting stress of the graded hard mask film;
wherein the graded hard mask film comprises a titanium nitride film with a graded vertical concentration of nitrogen;
wherein the graded hard mask film comprises:
a first non-zero concentration of nitrogen proximate a bottom surface of the titanium nitride film; and
a second non-zero concentration of nitrogen proximate a top surface of the titanium nitride film, the second non-zero concentration of nitrogen being different than the first non-zero concentration of nitrogen.

2. The method of claim 1 , wherein:
depositing the titanium film comprises depositing the titanium film in the RF deposition chamber with a flow of argon gas having a first flow rate; and
forming the graded hard mask film comprises depositing titanium while reducing the flow of argon gas from the first flow rate to a second flow rate and introducing a flow of nitrogen gas which increases from a third flow rate to a fourth flow rate.

3. The method of claim 2 , wherein the first flow rate of argon gas comprises 400 standard cubic centimeters per minute (sccm) and the second flow rate of argon gas comprises 200 sccm.

4. The method of claim 2 , wherein the third flow rate of nitrogen gas comprises 30-50 sccm and the fourth flow rate of nitrogen gas comprises 300 sccm.

5. The method of claim 2 , wherein the third flow rate comprises a first non-zero flow rate of nitrogen gas and the fourth flow rate comprises a second non-zero flow rate of nitrogen gas.

6. The method of claim 1 , wherein the graded hard mask film comprises a titanium nitride (Ti x N y ) film wherein the concentration of nitrogen varies vertically in a plane perpendicular to a top surface of the titanium film.

7. The method of claim 6 , wherein the value of y is lowest at the top surface of the titanium film and increases as distance from the top surface of the titanium film increases.

8. The method of claim 1 , wherein the graded hard mask film comprises a titanium nitride (TiN) film with varying vertical concentrations of titanium (Ti) and nitrogen (N).

9. The method of claim 8 , wherein the vertical concentration of Ti in the TiN film decreases relative to the concentration of N in the TiN film as distance from a top surface of the titanium film increases.

10. The method of claim 8 , wherein the TiN film comprises a bottom portion disposed adjacent a top surface of the titanium film and an upper portion disposed over the bottom portion.

11. The method of claim 10 , wherein the bottom portion of the TiN film comprises a concentration of Ti:N of approximately 1:0.25 and the upper portion of the TiN film comprises a vertically graded concentration of Ti:N which increases from 1:0.25 to 1:1.

12. The method of claim 1 , wherein the graded hard mask film comprises a continuous change from the first non-zero concentration of nitrogen to the second non-zero concentration of nitrogen as distance from the top surface of the titanium nitride film decreases.

13. The method of claim 12 , wherein the second non-zero concentration is greater than the first non-zero concentration.

Assignees

• IBM

Inventors

• De Silva Ekmini Anuja
• Xu Yongan
• Arceo de la Pena Abraham
• Yang Chih-Chao

Classifications

• H10P14/44 Primary

  Physical vapour deposition [PVD] · CPC title

• H10W20/4446

  Refractory-metal alloys · CPC title

• H10W20/069

  by forming self-aligned vias or self-aligned contact plugs · CPC title

• C23C14/0641

  Nitrides (C23C14/0617 takes precedence) · CPC title

• C23C14/3435

  Applying energy to the substrate during sputtering · CPC title