Plasma etching method using low ionization potential gas

• US 20010012694A1
• Filed: 03/20/2001
• Published: 08/09/2001
• Est. Priority Date: 02/24/1998
• Status: Active Grant

• Current Assignee: John W. Coburn, Kevin G. Donohoe
• Original Assignee: John W. Coburn, Kevin G. Donohoe
• Inventors: Donohoe, Kevin G., Coburn, John W.
• Granted Patent: US 6,475,920 B2
• Time in Patent Office: Days
• US Class Current: 438/689
• CPC Class Codes: H01L 21/31116 by dry-etching
• CPC Class Codes: H01L 21/31144 using masks
• CPC Class Codes: H01L 21/76802 by forming openings in dielectrics

Abstract

An etching method for forming an opening includes providing a substrate assembly having a surface and an oxide layer thereon. A patterned mask layer is provided over the oxide layer exposing a portion of the oxide layer. A plasma including one or more of C_xH_yF_z⁺ ions and C_xF_z⁺ ions and further including xenon or krypton ions is used to etch the oxide layer at the exposed portion to define the opening in the oxide layer while simultaneously depositing a polymeric residue on a surface defining the opening. The etching is continued until the opening in the oxide layer is selectively etched to the surface of the substrate assembly.

Claims

1. An etching method for use in the fabrication of integrated circuits, the method comprising:

providing a substrate assembly having a surface;

providing an oxide layer over the substrate assembly;

providing a patterned mask layer over the oxide layer exposing a portion of the oxide layer;

providing one or more carbon and fluorine containing gases;

providing a low ionization potential gas selected from one of xenon and krypton;

generating a plasma using the one or more carbon and fluorine containing gases and the low ionization potential gas;

etching the oxide layer at the exposed portion to define an opening in the oxide layer while simultaneously depositing a polymeric residue on at least a sidewall of the opening being defined; and

continuing the etching step using the plasma generated using the one or more carbon and fluorine containing gases and the low ionization potential gas until the opening in the oxide layer is etched selectively to the surface.

2. The method of

claim 1

, wherein the surface is a silicon containing surface.

3. The method of

claim 2

, wherein the silicon containing surface is one of silicon, polysilicon, or silicon nitride.

4. The method of

claim 1

, wherein the low ionization potential gas is xenon.

5. The method of

claim 1

, wherein providing the low ionization potential gas includes providing a flow of xenon that is less than about 29 percent of the flow of xenon and a flow of the one or more carbon and fluorine containing gases.

6. The method of

claim 5

, wherein the flow of xenon is less than about 20 percent of the flow of xenon and the flow of the one or more carbon and fluorine containing gases.

7. The method of

claim 1

, wherein the opening is a small high aspect ratio opening having a critical dimension of less than about 1 micron and an aspect ratio greater than about 1.

8. The method of

claim 7

, wherein the opening is a via.

9. The method of

claim 7

, wherein the opening is a contact hole.

10. An etching method for forming a contact opening, the method comprising:

providing a substrate assembly having a silicon containing surface;

providing an oxide layer on the surface;

providing a patterned mask layer over the oxide layer exposing a portion of the oxide layer;

providing a plasma including one or more of C_xH_yF_z⁺ ions and C_xF_z⁺ ions and further including Xe⁺ ions;

etching the oxide layer at the exposed portion to define the contact opening in the oxide layer while simultaneously depositing a polymeric residue on a surface defining the contact opening; and

continuing the etching step using the plasma until the contact opening in the oxide layer is selectively etched to the silicon containing surface.

11. The method of

claim 10

, wherein the silicon containing surface is one of silicon, polysilicon, and silicon nitride.

12. The method of

claim 10

, wherein providing the plasma includes providing a flow of one or more gases selected from fluorocarbon gases and hydrofluorocarbon gases and providing a flow of xenon to a processing chamber.

13. The method of

claim 12

, wherein the flow of xenon is less than about 29 percent of the flow of xenon and the flow of the one or more gases selected from fluorocarbon gases and hydrofluorocarbon gases.

14. The method of

claim 13

, wherein the flow of xenon is less than about 20 percent of the flow of xenon and the flow of the one or more gases selected from fluorocarbon gases and hydrofluorocarbon gases.

15. The method of

claim 10

, wherein the contact opening has a critical dimension of less than about 1 micron and an aspect ratio of greater than about 1.

16. A method for selectively etching silicon dioxide against a silicon containing layer, the method comprising:

placing a substrate assembly into an etch zone, the substrate assembly including a silicon containing surface, a silicon dioxide layer formed on the silicon containing surface, and a patterned mask layer formed over the silicon containing surface exposing a portion of the silicon dioxide layer;

generating a plasma in the etch zone, the plasma including one or more of C_xH_yF_z⁺ ions and C_xF_z⁺ ions and further including ions of a low ionization potential gas selected from xenon and krypton, wherein the plasma selectively etches the silicon dioxide layer at the exposed portion to define an opening in the silicon dioxide layer while simultaneously depositing a polymeric residue on at least one surface defining the opening, and further wherein the plasma etches the silicon dioxide layer until the opening in the silicon dioxide layer is completely etched to the silicon containing surface.

17. The method of

claim 16

, wherein the silicon containing surface is one of silicon, polysilicon, and silicon nitride.

18. The method of

claim 16

, wherein the low ionization potential gas is xenon.

19. The method of

claim 18

, wherein providing the low ionization potential gas includes providing a flow of xenon that is less than about 29 percent of the flow of xenon and a flow of the one or more carbon and fluorine containing gases.

20. The method of

claim 19

, wherein the flow of xenon is less than about 20 percent of the flow of xenon and the flow of the one or more carbon and fluorine containing gases.

21. The method of

claim 16

, wherein the opening is a small high aspect ratio opening having a critical dimension less than about 1 micron and an aspect ratio of greater than about 1.

22. An etching method for use in the fabrication of integrated circuits, the method comprising:

providing an oxide material comprising at least one exposed oxide region and at least one non-exposed oxide region;

providing at least one reactive gas component, wherein the at least one reactive gas component comprises at least carbon and flourine;

providing a low ionization potential gas, wherein the low ionization potential gas comprises at least one of xenon and krypton; and

etching the at least one exposed oxide region with a plasma generated using the at least one reactive gas component and the low ionization potential gas to define an opening in the oxide material and to deposit a polymeric residue on at least a sidewall of the opening being defined.

23. The method of

claim 22

, wherein providing the at least one exposed oxide region comprises:

providing a substrate assembly having a surface;

providing the oxide material on the substrate assembly surface; and

providing a patterned mask layer over the oxide material.

24. The method of

claim 23

, wherein the surface is a silicon containing surface.

25. The method of

claim 24

, wherein the silicon containing surface is one of silicon, polysilicon, or silicon nitride.

26. The method of

claim 22

, wherein etching the at least one exposed oxide region comprises defining the opening and simultaneously depositing the polymeric residue on the at least a sidewall of the opening being defined.

27. The method of

claim 22

, wherein the low ionization potential gas is xenon.

28. The method of

claim 22

, wherein providing the low ionization potential gas includes providing a flow of xenon that is less than about 29 percent of the flow of xenon and a flow of the at least one reactive gas component.

29. The method of

claim 28

, wherein the flow of xenon is less than about 20 percent of the flow of xenon and the flow of the at least one reactive gas component.

30. The method of

claim 22

, wherein the opening is a small high aspect ratio opening having a critical dimension of less than about 1 micron and an aspect ratio greater than about 1.

31. The method of

claim 22

, wherein the opening is a via.

32. The method of

claim 22

, wherein the opening is a contact hole.

33. An etching method for forming a contact opening, the method comprising:

providing an oxide material comprising at least one exposed oxide region and at least one non-exposed oxide region;

providing a plasma, wherein the plasma comprises low ionization potential gas ions and reactive gas ions, wherein the low ionization potential gas ions comprise at least one of xenon ions and krypton ions, wherein the reactive gas ions comprise at least ions from a group consisting of ions comprising carbon, hydrogen, and flourine, and ions comprising carbon and fluorine; and

etching the at least one exposed oxide region of the oxide material using the plasma to define the contact opening in the oxide material and to deposit a polymeric residue on a surface defining the contact opening.

34. The method of

claim 33

, wherein providing the at least one exposed oxide region comprises:

providing a substrate assembly having a surface;

providing the oxide material on the substrate assembly surface; and

providing a patterned mask layer over the oxide material.

35. The method of

claim 34

, wherein etching the at least one exposed oxide region comprises defining the contact opening in the oxide material to the substrate assembly surface.

36. The method of

claim 33

, wherein etching the at least one exposed oxide region comprises defining the opening and simultaneously depositing the polymeric residue on the surface defining the contact opening.

37. The method of

claim 33

, wherein the low ionization potential gas ions comprise xenon ions.

38. The method of

claim 33

, wherein providing the plasma comprises providing a flow of at least one of fluorocarbon gases and hydrofluorocarbon gases and providing a flow of xenon to a processing chamber.

39. The method of

claim 38

, wherein the flow of xenon is less than about 29 percent of the flow of xenon and the flow of at least one of fluorocarbon gases and hydrofluorocarbon gases.

40. The method of

claim 39

, wherein the flow of xenon is less than about 20 percent of the flow of xenon and the flow of the at least one of fluorocarbon gases and hydrofluorocarbon gases.

41. The method of

claim 33

, wherein the contact opening has a critical dimension of less than about 1 micron and an aspect ratio of greater than about 1.

42. A method for selectively etching silicon dioxide against a silicon containing layer, the method comprising:

providing a substrate assembly in an etch zone, wherein the substrate assembly comprises a silicon containing surface, a silicon dioxide layer formed on the silicon containing surface, and a patterned mask layer formed to expose a portion of the silicon dioxide layer;

generating a plasma in the etch zone, wherein the plasma comprises low ionization potential gas ions and reactive gas ions, wherein the low ionization potential gas ions comprise at least one of xenon ions and krypton ions, wherein the reactive gas ions comprise at least ions from a group consisting of ions comprising carbon, hydrogen, and flourine, and ions comprising carbon and fluorine, and further wherein the plasma etches the silicon dioxide layer at the exposed portion to define an opening in the silicon dioxide layer to the silicon containing surface and deposits a polymeric residue on at least one surface defining the opening.

43. The method of

claim 42

, wherein etching the silicon dioxide layer comprises defining the opening and simultaneously depositing the polymeric residue on the at least one surface defining the opening.

44. The method of

claim 42

, wherein the low ionization potential gas ions comprise xenon ions.

45. The method of

claim 42

, wherein generating the plasma comprises providing a flow of at least one of fluorocarbon gases and hydrofluorocarbon gases and providing a flow of xenon to a processing chamber.

46. The method of

claim 45

, wherein the flow of xenon is less than about 29 percent of the flow of xenon and the flow of the at least one of fluorocarbon gases and hydrofluorocarbon gases.

47. The method of

claim 46

, wherein the flow of xenon is less than about 20 percent of the flow of xenon and the flow of the at least one of the fluorocarbon gases and hydrofluorocarbon gases.

48. An etching method for forming an opening, the method comprising:

providing an oxide material comprising at least one exposed oxide region and at least one non-exposed oxide region;

providing a plasma, wherein the plasma comprises at least Xe⁺ ions and reactive gas ions, wherein the reactive gas ions comprise at least ions from a group consisting of ions comprising carbon, hydrogen, and flourine, and ions comprising carbon and fluorine, and further wherein the plasma comprises a larger fraction of Xe⁺ ions relative to the reactive gas ions; and

etching the at least one exposed oxide region.

49. The method of

claim 48

, wherein providing the at least one exposed oxide region comprises:

providing a substrate assembly having a surface;

providing the oxide material on the substrate assembly surface; and

providing a patterned mask layer over the oxide material.

50. The method of

claim 49

, wherein the surface of the substrate assembly is a silicon containing surface.

51. The method of

claim 50

, wherein the silicon containing surface is one of silicon, polysilicon, and silicon nitride.

52. The method of

claim 48

, wherein providing the plasma comprises providing a flow of at least one of fluorocarbon gases and hydrofluorocarbon gases and providing a flow of xenon to a processing chamber.

53. The method of

claim 52

, wherein the flow of xenon is less than about 29 percent of the flow of xenon and the flow of the at least one of fluorocarbon gases and hydrofluorocarbon gases.

54. The method of

claim 53

, wherein the flow of xenon is less than about 20 percent of the flow of xenon and the flow of the at least one of fluorocarbon gases and hydrofluorocarbon gases.

55. The method of

claim 48

, wherein the opening has a critical dimension of less than about 1 micron and an aspect ratio of greater than about 1.

56. The method of

claim 48

, wherein etching the at least one exposed oxide region comprises defining an opening in the oxide material and depositing a polymeric residue on at least a sidewall of the opening being defined.

57. The method of

claim 56

, wherein etching the at least one exposed oxide region comprises defining the opening and simultaneously depositing the polymeric residue on the at least a sidewall of the opening being defined.