Method and apparatus for forming an anti-reflective coating on a substrate

• US 20030077914A1
• Filed: 10/24/2001
• Published: 04/24/2003
• Est. Priority Date: 10/24/2001
• Status: Active Grant

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Kieu, Hoa Thi, Le, Hien-Minh Huu
• Granted Patent: US 6,750,156 B2
• Time in Patent Office: Days
• US Class Current: 438/763
• CPC Class Codes: C23C 14/083 of refractory metals or yttrium
• CPC Class Codes: C23C 14/56 Apparatus specially adapted for continuous coating; Arrangements for maintaining the vacuum, e.g. vacuum locks
• CPC Class Codes: H01J 37/32706 Polarising the substrate
• CPC Class Codes: H01J 37/3408 Planar magnetron sputtering

Abstract

In a method of depositing a titanium oxide layer on a substrate, a substrate is placed on a support in a process zone of a sputtering chamber. A target containing titanium faces the substrate. A sputtering gas containing an oxygen-containing gas, such as oxygen, and a non-reactive gas, such as argon, is introduced into the process zone. A pulsed DC voltage is applied to the target to sputter titanium from the target. The sputtered titanium combines with oxygen from the oxygen-containing gas to form a titanium oxide layer on the substrate. A multiple layer titanium oxide deposition process may also be implemented.

Claims

1. A method of depositing titanium oxide on a substrate, the method comprising:

(a) placing a substrate in a process zone;

(b) applying a pulsed DC voltage to a target facing the substrate, the target comprising titanium; and

(c) maintaining a sputtering gas at a sub atmospheric pressure in the process zone, the sputtering gas comprising an oxygen-containing gas,

whereby titanium oxide is deposited on the substrate.

2. A method according to claim 1 wherein (b) comprises applying a pulsed DC voltage that is pulsed between a first voltage that is about 0 Volts and a second voltage that is from about 200 to about 800 Volts.

3. A method according to claim 1 wherein (b) comprises applying a pulsed DC voltage that is pulsed so that the DC voltage is off for at least about 5% of the time of each pulse cycle.

4. A method according to claim 3 wherein the pulsed DC voltage is pulsed so that the DC voltage is off for less than about 50% of the time of each pulse cycle.

5. A method according to claim 1 wherein (b) comprises applying a pulsed DC voltage that is pulsed at a frequency of at least about 50 kHz.

6. A method according to claim 5 wherein the pulsed DC voltage is pulsed at a frequency of less than about 300 kHz.

7. A method according to claim 1 maintaining the sputtering gas at a sub atmospheric pressure in the process zone by exhausting the sputtering gas, the exhausting step comprising condensing water vapor prior to cryo-pumping the sputtering gas.

8. A method according to claim 1 comprising setting process conditions in the process zone to deposit titanium oxide on the substrate such that the substrate has a reflectivity of less than about 7% as compared to a reflectivity of about 100% of a silicon layer.

9. A method according to claim 1 wherein the titanium oxide is formed substantially without subsequently annealing the substrate in oxygen.

10. A method according to claim 1 wherein the sputtering gas comprises argon.

11. A method according to claim 10 wherein the oxygen-containing gas is oxygen.

12. A method according to claim 11 wherein the volumetric flow ratio of oxygen to argon is from about 4:

1 to about 9;

1.

13. A method according to claim 11 wherein the volumetric flow ratio of oxygen to argon is changed during the deposition of the titanium oxide layer.

14. A method according to claim 13 wherein the volumetric flow ratio of oxygen to argon is changed from a first volumetric flow ratio to a second volumetric flow ratio that is higher than the first volumetric flow ratio.

15. A method of sputter depositing material on a substrate in a multi-chamber platform comprising first and second sputtering chambers, the method comprising:

(a) in a diffusion barrier deposition stage, forming a diffusion barrier layer on a substrate;

(b) in a conductor deposition stage, transferring the substrate to a support in the first sputtering chamber, providing a target comprising conductor material facing the substrate, and maintaining an energized sputtering gas at a sub atmospheric pressure in the process zone, whereby conductor material that is sputtered from the target is deposited onto the substrate to form a conductor layer; and

(c) in an anti-reflective coating deposition stage, transferring the substrate to a support in a second sputtering chamber, applying a pulsed DC voltage to a target comprising titanium facing the substrate, and maintaining a sputtering gas at a sub atmospheric pressure in the process zone, the sputtering gas comprising oxygen and argon, whereby titanium that is sputtered from the target combines with the oxygen to form an anti-reflective coating of titanium oxide on the substrate.

16. A method according to claim 15 wherein (c) comprises applying a pulsed DC voltage that is pulsed between a first voltage that is about 0 Volts and a second voltage that is from about 200 to about 800 Volts.

17. A method according to claim 15 wherein (c) comprises applying a pulsed DC voltage that is pulsed so that the pulsed DC voltage is off from about 5% to about 50% of the time of each pulse cycle.

18. A method according to claim 15 wherein (c) comprises applying a pulsed DC voltage that is pulsed at a frequency of from about 50 kHz to about 300 kHz.

19. A method according to claim 15 wherein in (c) the step of maintaining the sputtering gas at a sub atmospheric pressure in the process zone comprises exhausting the sputtering gas, the exhausting step comprising condensing water vapor prior to cryo-pumping the sputtering gas.

20. A method according to claim 15 wherein (c) comprises setting process conditions in the process zone to deposit a titanium oxide layer on the substrate such that the substrate has a reflectivity of less than about 7% as compared to a reflectivity of about 100% of a silicon layer.

21. A method according to claim 15 wherein in (c) the volumetric flow ratio of oxygen to argon is from about 4:

1 to about 9;

1.

22. A method according to claim 15 wherein in (c) the volumetric flow ratio of oxygen to argon is changed during the deposition of the titanium oxide layer from a first volumetric flow ratio to a second volumetric flow ratio that is higher than the first volumetric flow ratio.

23. A method of sputter depositing a stacked layer on a substrate in a multi-chamber platform comprising a load-lock chamber and first and second sputtering chambers, the method comprising:

(a) placing a plurality of substrates in the load-lock chamber;

(b) in a diffusion barrier deposition stage, forming a diffusion barrier layer on one of the substrates;

(c) in a conductor deposition stage, (i) transferring the substrate to a support in the first sputtering chamber, (ii) providing a target facing the substrate, the target comprising a conductor material, (iii) maintaining an energized sputtering gas at a sub atmospheric pressure in the process zone, whereby conductor material that is sputtered from the target is deposited on the substrate; and

(d) in an anti-reflective coating stage, (i) transferring the substrate to a support in the second sputtering chamber, (ii) providing a target comprising titanium facing the substrate, (iii) applying a pulsed DC voltage to the target, the pulsed DC voltage having a frequency of from about 50 kHz to about 300 kHz and being pulsed so that the voltage is off from about 5% to about 50% of the time of each pulse cycle, and (iv) maintaining a sputtering gas at a sub atmospheric pressure in the process zone, the sputtering gas comprising a volumetric flow ratio of oxygen to argon of from about 4;

1 to about 9;

1, whereby titanium that is sputtered from the target combines with the oxygen to form an anti-reflective coating of titanium oxide on the substrate.

24. A method according to claim 23 wherein in (d) the volumetric flow ratio of oxygen to argon is changed during the deposition of the titanium oxide layer from a first volumetric flow ratio to a second volumetric flow ratio that is higher than the first volumetric flow ratio.

25. A method according to claim 24 wherein the second volumetric flow ratio is at least about 1.5 times higher than the first volumetric flow ratio.

26. A sputtering chamber for depositing titanium oxide on a substrate, the chamber comprising:

a substrate support;

a target facing the substrate support, the target comprising titanium;

a pulsed DC source to provide a pulsed DC voltage to the target;

a gas inlet to introduce a sputtering gas into the chamber, the sputtering gas comprising an oxygen-containing gas; and

an exhaust to exhaust the sputtering gas.

27. A chamber according to claim 26 wherein the pulsed DC source provides a pulsed DC voltage that is pulsed between on and off states.

28. A chamber according to claim 26 wherein the pulsed DC source provides a pulsed DC voltage having a pulsing frequency of at least about 50 kHz.

29. A chamber according to claim 28 wherein the pulsed DC source provides a pulsed DC voltage having a pulsing frequency of less than about 300 kHz.

30. A chamber according to claim 26 wherein the pulsed DC source provides a pulsed DC voltage that is pulsed so that the voltage is off for at least about 5% of the time of each pulse cycle.

31. A chamber according to claim 30 wherein the pulsed DC source provides a pulsed DC voltage that is off for less than about 50% of the time of each pulse cycle.

32. A chamber according to claim 26 wherein the exhaust comprises an exhaust port that feeds to a water vapor condenser, and thereafter to a cryo-pump.

33. A chamber according to claim 26 further comprising a controller adapted to set process conditions in the chamber to deposit titanium oxide such that the substrate has a reflectivity of less than about 7% as compared to a reflectivity of about 100% of a silicon layer.

34. A chamber according to claim 26 wherein the gas inlet is connected to gas sources that provide a sputtering gas comprising argon and an oxygen-containing gas that is oxygen.

35. A chamber according to claim 34 comprising a controller to control mass flow controllers to set a volumetric flow ratio of oxygen to argon of from about 4:

1 to about 9;

1.

36. A chamber according to claim 34 comprising a controller to control mass flow controllers to change the volumetric flow ratio of oxygen to argon during deposition of the titanium oxide.

37. A chamber according to claim 36 wherein the controller controls the mass flow controllers to change the volumetric flow ratio of oxygen to argon from a first volumetric flow ratio to a second volumetric flow ratio that is higher than the first volumetric flow ratio.

38. A sputtering chamber for depositing titanium oxide on a substrate, the chamber comprising:

a substrate support;

a target facing the substrate support, the target comprising titanium;

a pulsed DC source to apply a pulsed DC voltage to the target;

a sputtering gas supply comprising an oxygen input to receive oxygen from an external source and an argon input to receive argon from another external source, and mass flow controllers adapted to control the oxygen and argon flow rates from the inputs into the chamber;

an exhaust to exhaust gas from the chamber; and

a controller comprising a computer having computer readable program code embodied in a computer readable medium, the computer readable program code comprising;

voltage source program code to operate the pulsed DC source to apply the pulsed DC voltage to the target; and

gas flow program code to operate the mass flow controllers to control the gas flow rates to maintain a volumetric flow ratio of oxygen to argon of from about 4;

1 to about 9;

1,

whereby titanium that is sputtered from the target and the oxygen combine to deposit titanium oxide on the substrate.

39. An apparatus according to claim 38 wherein the pulsed DC source provides a pulsed DC voltage that is pulsed between a first voltage that is about 0 Volts and a second voltage that is from about 200 to about 800 Volts.

40. An apparatus according to claim 38 the pulsed DC source provides a pulsed DC voltage having a pulsing frequency of from about 50 kHz to about 300 kHz.

41. An apparatus according to claim 38 wherein the pulsed DC source provides a pulsed DC voltage that is off from about 5% to about 50% of the time of each pulse cycle.

42. An apparatus according to claim 38 wherein the exhaust comprises an exhaust port that feeds to a water vapor condenser, and thereafter, to a cryo-pump.

43. An apparatus according to claim 38 wherein the controller is adapted to set process conditions in the chamber to deposit titanium oxide such that the substrate has a reflectivity of less than about 7% as compared to a reflectivity of about 100% of a silicon layer.

44. An apparatus according to claim 38 wherein the gas flow program code operates the mass flow controllers to change the volumetric flow ratio of oxygen to argon during the deposition of the titanium oxide.

45. An apparatus according to claim 44 wherein the gas flow program code operates the mass flow controllers to change the volumetric flow ratio of oxygen to argon from a first volumetric flow ratio to a second volumetric flow ratio that is higher than the first volumetric flow ratio.

46. An apparatus for depositing material on a substrate, the apparatus comprising:

a platform that interconnects a plurality of chambers so that a substrate may be transferred from one chamber to another chamber;

a load-lock chamber on the platform to receive a cassette of substrates;

a first sputtering chamber mounted on the platform, the first sputtering chamber comprising (i) a substrate support, (ii) a target facing the substrate support, the target comprising a conductor material, (iii) a gas inlet to provide a gas into the chamber, (iv) a gas energizer to energize the gas, and (v) an exhaust to exhaust the gas, whereby conductor material is sputtered from the target and onto the substrate; and

a second sputtering chamber mounted on the platform, the second sputtering chamber comprising (i) a substrate support, (ii) a target facing the substrate support, the target comprising titanium, (iii) a pulsed DC source to bias the substrate support with a pulsed DC voltage, (iv) a gas inlet to introduce a gas into the chamber, the gas comprising an oxygen-containing gas and argon, and (v) an exhaust to exhaust the gas, whereby titanium that is sputtered from the target and the oxygen-containing gas combine to deposit titanium oxide on the substrate.

47. An apparatus according to claim 46 wherein the pulsed DC source provides a pulsed DC voltage that is pulsed between a first voltage that is about 0 Volts and a second voltage that is from about 200 to about 800 Volts.

48. An apparatus according to claim 46 wherein the pulsed DC source provides a pulsed DC voltage having a pulsing frequency of from about 50 kHz to about 300 kHz.

49. An apparatus according to claim 46 wherein the pulsed DC source provides a pulsed DC voltage that is pulsed so that the voltage is off from about 5% to about 50% of the time of each pulse cycle.

50. An apparatus according to claim 46 wherein in the second sputtering chamber, the exhaust comprises an exhaust port that feeds to a water vapor condenser, and thereafter to a cryo-pump.

51. An apparatus according to claim 46 comprising a controller adapted to set process conditions in the second sputtering chamber to deposit titanium oxide having a reflectivity of less than about 7% as compared to a reflectivity of about 100% of a silicon layer.

52. An apparatus according to claim 46 wherein in the second sputtering chamber, the gas inlet provides an oxygen-containing gas that is oxygen.

53. An apparatus according to claim 52 comprising a controller that controls mass flow controllers to set a volumetric flow ratio of oxygen to argon of from about 4:

1 to about 9;

1.

54. An apparatus according to claim 53 wherein the controller controls the mass flow controllers to change the volumetric flow ratio of oxygen to argon during the deposition of the titanium oxide layer.

55. An apparatus according to claim 54 wherein the controller controls the mass flow controllers to change the volumetric flow ratio of oxygen to argon from a first volumetric flow ratio to a second volumetric flow ratio that is higher than the first volumetric flow ratio.

56. An apparatus according to claim 55 wherein the controller controls the mass flow controllers to provide a second volumetric flow ratio that is at least about 1.5 times higher than a first volumetric flow ratio.

57. A method of depositing titanium oxide on a substrate, the method comprising:

(a) placing a substrate in a process zone;

(b) electrically biasing a target facing the substrate, the target comprising titanium;

(c) introducing a sputtering gas into the process zone, the sputtering gas comprising a first volumetric flow ratio of an oxygen-containing gas and argon;

(d) changing the first volumetric flow ratio to a second volumetric flow ratio;

(e) exhausting the sputtering gas,

whereby multiple layers of titanium oxide are deposited on the substrate.

58. A method according to claim 57 comprising changing the first volumetric flow ratio to the second volumetric flow ratio so that the multiple layers of titanium oxide have different stoichiometries.

59. A method according to claim 57 wherein the volumetric flow ratio of oxygen-containing gas to argon is changed from a first volumetric flow ratio to a second volumetric flow ratio that is higher than the first volumetric flow ratio.

60. A method according to claim 57 wherein (b) comprises applying a pulsed DC voltage to the target that is pulsed between a first voltage that is about 0 Volts and a second voltage that is from about 200 to about 800 Volts.

61. A method according to claim 60 wherein (b) comprises applying a pulsed DC voltage that is pulsed so that the DC voltage is off for at least about 5% of the time of each pulse cycle.

62. A method according to claim 60 wherein the pulsed DC voltage is pulsed so that the DC voltage is off for less than about 50% of the time of each pulse cycle.

63. A method according to claim 60 wherein (b) comprises applying a pulsed DC voltage that is pulsed at a frequency of from about 50 kHz to about 300 kHz.

64. A method according to claim 57 wherein (e) comprises condensing water vapor prior to cryo-pumping the sputtering gas.

65. A method according to claim 57 wherein the oxygen-containing gas is oxygen.

66. A method according to claim 57 wherein the first and second volumetric flow ratios of oxygen to argon are from about 4:

1 to about 9;

1.

67. A sputtering chamber for depositing titanium oxide on a substrate, the chamber comprising:

a substrate support;

a target facing the substrate support, the target comprising titanium;

a voltage source to apply a voltage to the target;

a sputtering gas supply comprising an oxygen input to receive an oxygen-containing gas from an external source and an argon input to receive argon from another external source, and mass flow controllers adapted to control the oxygen-containing gas and argon flow rates from the inputs into the chamber;

an exhaust to exhaust gas from the chamber; and

a controller comprising a computer having computer readable program code embodied in a computer readable medium, the computer readable program code comprising gas flow program code to operate the mass flow controllers to control the gas flow rates to provide a sputtering gas comprising first volumetric flow ratio of oxygen-containing gas to argon for a first time period, and a second volumetric flow ratio of oxygen-containing gas to argon for a second time period,

whereby titanium that is sputtered from the target and the oxygen combine to deposit multiple layers of titanium oxide on the substrate.

68. An apparatus according to claim 67 wherein the gas flow program code operates the mass flow controllers to change the first volumetric flow ratio to the second volumetric flow ratio so that the multiple layers of titanium oxide have different stoichiometries.

69. An apparatus according to claim 67 wherein the gas flow program code operates the mass flow controllers to change the first volumetric flow ratio to a second volumetric flow ratio that is higher than the first volumetric flow ratio.

70. An apparatus according to claim 67 wherein the voltage source provides a pulsed DC voltage that is pulsed between a first voltage that is about 0 Volts and a second voltage that is from about 200 to about 800 Volts.

71. An apparatus according to claim 70 wherein the voltage source provides a pulsed DC voltage having a pulsing frequency of from about 50 kHz to about 300 kHz.

72. An apparatus according to claim 70 wherein the voltage source provides a pulsed DC voltage that is off from about 5% to about 50% of the time of each pulse cycle.

73. An apparatus according to claim 70 wherein the exhaust comprises an exhaust port that feeds to a water vapor condenser, and thereafter, to a cryo-pump.