Plasma reactor and shields generating self-ionized plasma for sputtering

• US 6,398,929 B1
• Filed: 10/08/1999
• Issued: 06/04/2002
• Est. Priority Date: 10/08/1999
• Status: Expired due to Fees

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Chiang, Tony P., Ding, Peijun, Fu, Jianming, Cong, Yu D., Tang, Howard H., Tolia, Anish
• Primary Examiner(s): MCDONALD, RODNEY GLENN
• Application Number:
  US09/414,614
• Time in Patent Office: 970 Days
• Field of Search: 204/298.11
• US Class Current: 204/298.11
• CPC Class Codes: C23C 14/046 Coating cavities or hollow spaces, e.g. interior of tubes; Infiltration of porous substrates
• CPC Class Codes: C23C 14/345 using substrate bias
• CPC Class Codes: C23C 14/3457 using other particles than noble gas ions C23C14/0036, C23C14/46 take precedence
• CPC Class Codes: C23C 14/35 by application of a magnetic field, e.g. magnetron sputtering C23C14/3457 takes precedence
• CPC Class Codes: C23C 14/358 Inductive energy
• CPC Class Codes: C23C 14/564 Means for minimising impurities in the coating chamber such as dust, moisture, residual gases
• CPC Class Codes: H01J 2237/3327 Coating high aspect ratio workpieces
• CPC Class Codes: H01J 37/321 the radio frequency energy being inductively coupled to the plasma
• CPC Class Codes: H01J 37/3402 using supplementary magnetic fields
• CPC Class Codes: H01J 37/3408 Planar magnetron sputtering
• CPC Class Codes: H01J 37/3441 Dark space shields
• CPC Class Codes: H01L 21/2855 by physical means, e.g. sputtering, evaporation H01L21/28518 - H01L21/28537 and H01L21/28568 take precedence
• CPC Class Codes: H01L 21/76843 formed in openings in a dielectric
• CPC Class Codes: H01L 21/76862 Bombardment with particles, e.g. treatment in noble gas plasmas; UV irradiation
• CPC Class Codes: H01L 21/76865 Selective removal of parts of the layer H01L21/76844 takes precedence
• CPC Class Codes: H01L 21/76868 Forming or treating discontinuous thin films, e.g. repair, enhancement or reinforcement of discontinuous thin films
• CPC Class Codes: H01L 21/76871 Layers specifically deposited to enhance or enable the nucleation of further layers, i.e. seed layers
• CPC Class Codes: H01L 21/76873 for electroplating
• CPC Class Codes: H01L 21/76876 for deposition from the gas phase, e.g. CVD
• CPC Class Codes: H01L 21/76877 Filling of holes, grooves or trenches, e.g. vias, with conductive material
• CPC Class Codes: H01L 2221/1089 : Stacks of seed layers

Abstract

A DC magnetron sputter reactor for sputtering copper, its method of use, and shields and other parts promoting self-ionized plasma (SIP) sputtering, preferably at pressures below 5 milliTorr, preferably below 1 milliTorr. Also, a method of coating copper into a narrow and deep via or trench using SIP for a first copper layer. SIP is promoted by a small magnetron having poles of unequal magnetic strength and a high power applied to the target during sputtering. The target power for a 200 mm wafer is preferably at least 10 kW; more preferably, at least 18 kW; and most preferably, at least 24 kW. Hole filling with SIP is improved by long-throw sputtering in which the target-to-substrate spacing is at least 50% of substrate diameter, more preferably at least 80%, most preferably at least 140%. The SIP copper layer can act as a seed and nucleation layer for hole filling with conventional sputtering (PVD) or with electrochemical plating (ECP). For very high aspect-ratio holes, a copper seed layer is deposited by chemical vapor deposition (CVD) over the SIP copper nucleation layer, and PVD or ECP completes the hole filling. The copper seed layer may be deposited by a combination of SIP and high-density plasma sputtering. For very narrow holes, the CVD copper layer may fill the hole. Preferably, the plasma is ignited in a cool process in which low power is applied to the target in the presence of a higher pressure of argon working gas. After ignition, the pressure is reduced, and target power is ramped up to a relatively high operational level to sputter deposit the film.

Claims

1. A pair of shields for use in a plasma sputtering reactor, comprising a first generally circularly symmetric shield and a second generally circularly symmetric shield both referenceable to a common axis:

wherein said first shield comprises

a first flange portion extending radially outwardly from said axis;

a first cylindrical portion extending along said axis for a first length, having a first diameter, and being connected to said first flange portion,

a second cylindrical portion extending along said axis for a second length, and having a second diameter smaller than said first diameter,

a first transition portion connecting said first and second cylindrical portions,

a bowl portion connected to said second cylindrical portion and extending radially of said axis, and

a third cylindrical portion extending along said axis for a third length smaller than said second length, having a third diameter smaller than said second diameter, and being connected to said bowl portion;

wherein said second shield comprises

a second flange portion extending radially outwardly from said axis,

a fourth cylindrical portion extending along said axis for a fourth length larger than said first length and having a fourth diameter smaller than said first diameter,

a fifth cylindrical portion extending along said axis for a fifth length smaller than said second length and having a fifth diameter smaller than said second diameter and larger than said third diameter, and

a second transition portion connecting said fourth and fifth cylindrical portions; and

wherein said first and second shields are positionable along said axis to form a convolute channel between (a) said first and fourth cylindrical portions, (b) said first and second transition portions, and (c) said second and fifth cylindrical portions.

2. The pair of shields of claim 1, wherein said second length is at least 2 cm.

3. The pair of shields of claim 2, wherein said second length is no more than 3 cm.

4. The pair of shields of claim 1, wherein the portion of the convolute channel between said second and fifth cylindrical portions has an aspect ratio of at least 8:

1.

5. The pair of shields of claim 1, wherein said convolute channel is formed with at least two bends of at least 90°

adjacent to said two transition portions.

6. A plasma sputter reactor, comprising:

a metallic vacuum chamber containing a pedestal aligned to a chamber axis and having a support surface for supporting a substrate to be sputter deposited;

a target of a material to be sputter deposited on said substrate and electrically isolated from said vacuum chamber;

a first electrically conductive shield generally symmetric about said axis, supported on and electrically connected to said chamber, and extending away from said target along a wall of said chamber to an elevation behind said support surface;

an electrical isolator supported by said chamber;

a second electrically conductive shield generally symmetric about said axis, supported on said isolator, electrically isolated from said chamber and from said target, and extending from said target along and inside of a portion of said first shield;

wherein a channel is formed between said first and second shields having an aspect ratio of at least 4;

1, having a width of between 2.5 and 3 mm, and extending from a lower tip of said second shield to an area exposed to said isolator.

7. The reactor of claim 6, wherein said material of said target primarily comprises copper.

8. The reactor of claim 6, wherein said channel has an aspect ratio of at least 8:

1.

9. The reactor of claim 6, wherein said channel includes two bends of at least 45°

.

10. The reactor of claim 9, wherein said bends are 90°

bends so as to form a horizontally extending portion of said channel between said two shields.

11. A plasma sputter reactor, comprising:

a metallic vacuum chamber containing a pedestal aligned to a chamber axis and having a support surface for supporting a substrate to be sputter deposited;

a target comprising a material to be sputter deposited on said substrate and electrically isolated from said vacuum chamber;

a first electrically conductive shield generally symmetric about said axis, supported on and electrically connected to said chamber, and extending away from said target along a wall of said chamber to an elevation behind said support surface;

an electrical isolator supported by said chamber;

a second electrically conductive shield generally symmetric about said axis, supported on said isolator, electrically isolated from said chamber and from said target, and extending from said target along and inside of a portion of said first shield, wherein a second shield terminates on a side of said target toward said pedestal at a distance of at least 2 cm from a face of said target.

12. The reactor of claim 11, wherein said distance is greater than 5 cm from said face of said target.

13. The reactor of claim 12, wherein said distance is no more than 7 cm from said face of said target.

14. The reactor of claim 11, wherein said distance is at least 5 cm from said face of said target.

15. The reactor of claim 11, wherein said electrical isolator is generally symmetric about axis with an axial height greater than a radial width.

16. The reactor of claim 11, wherein said target includes a flange portion and further comprising a second isolator supported on and sealed to said vacuum chamber;

wherein said second shield extends along the side of a target portion of said target, and

wherein a radial annularly symmetric gap of no more than 2 mm is formable between a radially outer portion of said second shield and a radially inner portion of said second isolator, thereby aligning a dark space between said second shield and said target portion.

17. The reactor of claim 11, wherein said target includes a target portion primarily comprising copper.

18. A plasma sputter reactor, comprising:

a metallic vacuum chamber containing a pedestal aligned to a chamber axis and having a support surface for supporting a substrate to be sputter deposited;

a target comprising a material to be sputter deposited on said substrate and electrically isolated from said vacuum chamber;

a first electrically conductive shield generally symmetric about said axis, supported on and electrically connected to said chamber, and extending away from said target along a wall of said chamber to an elevation behind said support surface;

an electrical isolator supported by said chamber;

a metallic clamp ring fixing said first shield to said metallic vacuum chamber; and

;

a second electrically conductive shield generally symmetric about said axis, supported on said isolator, electrically isolated from said chamber and from said target, and extending from said target along and inside of a portion of said first shield, wherein second shield terminates on a side of said target toward said pedestal at a distance of at least 2 cm from a face of said target.

19. The reactor of claim 18, wherein said first shield has a tab extending toward said pedestal from a side of said first shield adjacent said target and wherein said isolator has a second recess on an outer corner on a side facing away from said pedestal accommodating said tab, thereby aligning said first shield with respect to said isolator.

20. The plasma sputter reactor of claim 18, wherein said metallic clamp ring has a rim extending on a radially inner side toward said target, wherein said electrical isolator has a recess on an inner corner on a side facing said pedestal accommodating said rim, thereby aligning said isolator with respect to said clamp ring.

21. A plasma sputter reactor, comprising:

a metallic vacuum chamber containing a pedestal aligned to a chamber axis and having a support surface for supporting a substrate to be sputter deposited;

a target comprising a material to be sputter deposited on said substrate and electrically isolated from said vacuum chamber;

a first electrically conductive shield generally symmetric about said axis, supported on and electrically connected to said chamber, and extending away from said target along a wall of said chamber to an elevation behind said support surface;

an electrical isolator supported by said chamber;

a second electrically conductive shield generally symmetric about said axis, supported on said isolator, electrically isolated from said chamber and from said target, and extending from said target along and inside of a portion of said first shield, wherein a second shield terminates on a side of said target toward said pedestal at a distance of at least 2 cm from a face of said target;

wherein a convolute channel having two 90°

bends is formed between said first and second shields.

22. A plasma sputter reactor, comprising:

a metallic vacuum chamber containing a pedestal aligned to a chamber axis and having a support surface for supporting a substrate to be sputter deposited;

a target comprising a material to be sputter deposited on said substrate and electrically isolated from said vacuum chamber;

a first electrically conductive shield generally symmetric about said axis, supported on and electrically connected to said chamber, and extending away from said target along a wall of said chamber to an elevation behind said support surface;

an electrical isolator supported by said chamber;

a second electrically conductive shield generally symmetric about said axis, supported on said isolator, electrically isolated from said chamber and from said target, and extending from said target along and inside of a portion of said first shield, wherein a second shield terminates on a side of said target toward said pedestal at a distance is at least 5 cm and no more than 10 cm from said face of said target.