Method for fabrication of ceramic tantalum nitride and imporoved structures based thereon

• US 20010017757A1
• Filed: 01/16/2001
• Published: 08/30/2001
• Est. Priority Date: 02/24/2000
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Conexant Systems Incorporated (Synaptics Incorporated)
• Inventors: Abdul-Ridha, Hadi, Young, David T., Brongo, Maureen R.
• Granted Patent: US 6,836,400 B2
• Time in Patent Office: Days
• US Class Current: 361/311
• CPC Class Codes: C23C 14/0036 Reactive sputtering
• CPC Class Codes: C23C 14/0641 Nitrides C23C14/0617 takes precedence
• CPC Class Codes: H01L 21/28568 the conductive layers comprising transition metals H01L21/28518 takes precedence

Abstract

A method for fabrication of ceramic tantalum nitride and improved structures based thereon is disclosed. According to the disclosed method, an ionized metal plasma (“IMP”) tool is used to create a plasma containing tantalum ions where the plasma is sustained by a mixture of nitrogen and argon gases. The percentage of nitrogen partial flow in the mixture of gases is adjusted so as to result in a layer of tantalum nitride with a nitrogen content of at least 30%. With a nitrogen content of at least 30%, the tantalum nitride becomes ceramic. The ceramic tantalum nitride presents a number of advantages. For example, the fabrication of ceramic tantalum nitride can be easily incorporated into fabrication of semiconductor chips using copper as the interconnect metal. Also, ceramic tantalum nitride can be used as an effective etch stop layer. The reason is that ceramic tantalum nitride does not react with fluoride which is a typical constituent of etchants utilized to etch silicon-based dielectrics such as silicon dioxide. Further, ceramic tantalum nitride can be used as a dielectric in fabrication of a capacitor stack using copper electrodes. Since fabrication of ceramic tantalum nitride is easily assimilated with fabrication of copper, the capacitor stack utilizing ceramic tantalum nitride can be built in a single IMP tool along with the copper electrodes. The result is higher throughput and a reduced risk of contaminating the semiconductor wafer since there is no need to “break vacuum” for a separate fabrication of the dielectric layer.

Claims

1. A method comprising the steps of:

utilizing an ionized metal plasma tool for creating a plasma containing tantalum ions, said plasma being sustained by a mixture of gases containing nitrogen;

depositing a layer of tantalum nitride on a semiconductor wafer wherein a percentage of nitrogen partial flow in said mixture of gases is adjusted so as to cause a nitrogen content in said layer of tantalum nitride to be at least 30%.

2. The method of

claim 1

wherein said mixture of gases contains argon.

3. The method of

claim 1

wherein said percentage of nitrogen partial flow in said mixture of gases is adjusted so as to cause said nitrogen content in said layer of tantalum nitride to be 60%.

4. The method of

claim 1

wherein said percentage of nitrogen partial flow in said mixture of gases is adjusted so as to cause said layer of tantalum nitride to become ceramic.

5. The method of

claim 1

wherein said layer of tantalum nitride is used as a dielectric situated between first and second electrodes of a capacitor.

6. The method of

claim 1

wherein said layer of tantalum nitride is used as an etch stop layer in fabrication of a via structure in said semiconductor wafer.

7. A structure comprising:

a first capacitor electrode;

a second capacitor electrode;

a dielectric comprising ceramic tantalum nitride situated between said first and second capacitor electrodes.

8. The structure of

claim 7

wherein said first capacitor electrode is made of copper.

9. The structure of

claim 7

wherein said second capacitor electrode is made of copper.

10. The structure of

claim 7

wherein said dielectric comprising ceramic tantalum nitride is fabricated using a method comprising the steps of:

utilizing an ionized metal plasma tool for creating a plasma containing tantalum ions, said plasma being sustained by a mixture of gases containing nitrogen;

depositing said dielectric comprising ceramic tantalum nitride on said first capacitor electrode wherein a percentage of nitrogen partial flow in said mixture of gases is adjusted so as to cause a nitrogen content in said dielectric comprising ceramic tantalum nitride to be at least 30%.

11. The structure of

claim 10

wherein said percentage of nitrogen partial flow in said mixture of gases is adjusted so as to cause said nitrogen content in said dielectric comprising ceramic tantalum nitride to be 60%.

12. A method for etching a dielectric in a semiconductor wafer, said method comprising the steps of:

forming a ceramic tantalum nitride layer as an etch stop layer in said dielectric;

etching said dielectric with an etchant wherein said etchant does not react with said ceramic tantalum nitride layer.

13. The method of

claim 12

wherein said dielectric is etched to create a via and wherein said etch stop layer is placed at a bottom of said via.

14. The method of

claim 12

wherein said etchant is a plasma comprising carbon and fluoride.

15. The method of

claim 12

wherein said dielectric comprises silicon dioxide.

16. The method of

claim 12

wherein said step of forming said ceramic tantalum nitride layer includes the steps of:

utilizing an ionized metal plasma tool for creating a plasma containing tantalum ions, said plasma being sustained by a mixture of gases containing nitrogen;

forming said ceramic tantalum nitride layer wherein a percentage of nitrogen partial flow in said mixture of gases is adjusted so as to cause a nitrogen content in said ceramic tantalum nitride layer to be at least 30%.

17. The method of

claim 16

wherein said percentage of nitrogen partial flow in said mixture of gases is adjusted so as to cause said nitrogen content in said ceramic tantalum nitride layer to be 60%.

18. A method comprising the steps of:

forming a ceramic tantalum nitride layer as an etch stop layer in a silicon dioxide dielectric;

etching a via hole in a portion of said silicon dioxide dielectric situated above said ceramic tantalum nitride layer utilizing an etchant comprising fluoride, wherein said ceramic tantalum nitride layer prevents etching a portion of said silicon dioxide dielectric situated below said ceramic tantalum nitride layer.

19. The method of

claim 18

wherein said step of forming said ceramic tantalum nitride layer includes the steps of:

utilizing an ionized metal plasma tool for creating a plasma containing tantalum ions, said plasma being sustained by a mixture of gases containing nitrogen;

forming said ceramic tantalum nitride layer wherein a percentage of nitrogen partial flow in said mixture of gases is adjusted so as to cause a nitrogen content in said ceramic tantalum nitride layer to be at least 30%.

20. The method of

claim 19

wherein said percentage of nitrogen partial flow in said mixture of gases is adjusted so as to cause said nitrogen content in said ceramic tantalum nitride layer to be 60%.