Electroplating bath containing wetting agent for defect reduction

• US 7,232,513 B1
• Filed: 06/29/2004
• Issued: 06/19/2007
• Est. Priority Date: 06/29/2004
• Status: Expired due to Fees

• Current Assignee: Novellus Systems Incorporated (Lam Research Corporation)
• Original Assignee: Novellus Systems Incorporated (Lam Research Corporation)
• Inventors: Reid, Jonathan D., Webb, Eric G., Takada, Yuichi, Sukamto, John H.
• Primary Examiner(s): Wong; Edna
• Application Number:
  US10/879,613
• Time in Patent Office: 1,085 Days
• Field of Search: 205/238, 205/239, 205/261, 205/296, 205/80, 205/81, 205/123, 205/297, 205/298
• US Class Current: 205/298
• CPC Class Codes: C25D 3/38 of copper
• CPC Class Codes: C25D 5/04 Electroplating with moving electrodes
• CPC Class Codes: C25D 5/18 Electroplating using modulated, pulsed or reversing current
• CPC Class Codes: C25D 5/627 Electroplating characterised by the visual appearance of the layers, e.g. colour, brightness or mat appearance

Abstract

An electroplating solution contains a wetting agent in addition to a suppressor and an accelerator. In some embodiments, the solution has a cloud point temperature greater than 35° C. to avoid precipitation of wetting agent or other solute out of the plating solution. In some embodiments, the wetting agent decreases the air-liquid surface tension of the electroplating solution to 60 dyne/cm² or less to increase the wetting ability of the solution with a substrate surface. In some embodiments of a method for plating metal onto substrate surface, the electroplating solution has a measured contact angle with the substrate surface less than 60 degrees.

Claims

1. An electroplating solution, comprising:

copper metal ions;

sulfuric acid at a concentration of about 10 grams per liter;

chloride ions at a concentration of about 50 milligrams per liter;

an accelerator at a concentration of about 30 parts per million (ppm), said accelerator consisting essentially of bis-(3-sulfopropyl)-disulfide (SPS);

a leveler at a concentration of about 2 ppm, said leveler consisting essentially of poly(vinyl pyrrolidone) (PVP) having an average molecular weight in a range of about from 3000 to 5000;

a suppressor at a concentration of about 200 ppm; and

a wetting agent at a concentration in a range of about from 80 ppm to 200 ppm;

wherein

said suppressor consists essentially of a formulation having an average molecular weight of about 2500 and a molar ratio of polypropylene glycol (PPG) to polyethylene glycol (PEG) of about 0.5; and

said wetting agent consists essentially of a block co-polymer of polyethylene glycol and polypropylene glycol having an average molecular weight of about 5900 and a molar ratio of polyethylene glycol (PEG) to polypropylene glycol (PPG) of about 0.4;

0.6.

2. An electroplating solution as in claim 1, wherein:

said electroplating solution has an air-liquid surface tension not exceeding 60 dyne/cm².

3. An electroplating solution as in claim 2, wherein said air-liquid surface tension does not exceed 50 dyne/cm².

4. An electroplating solution as in claim 2, wherein said air-liquid surface tension does not exceed 45 dyne/cm².

5. An electroplating solution as in claim 2, wherein said air-liquid surface tension does not exceed 40 dyne/cm².

6. An electroplating solution as in claim 1, wherein:

said electroplating solution has a cloud-point temperature greater than 35°

C.

7. An electroplating solution as in claim 6, wherein said electroplating solution has a cloud-point temperature greater than 50°

C.

8. An electroplating solution as in claim 6, wherein said electroplating solution has a cloud-point temperature greater than 70°

C.

9. An electroplating solution as in claim 1, wherein said wetting agent is present in said electroplating solution at a concentration not less than 100 ppm.

10. An electroplating solution as in claim 9, wherein said wetting agent is present in said electroplating solution at a concentration of about 200 ppm.

11. A method of electroplating metal onto a substrate surface, comprising the steps of:

immersing a substrate into an electroplating solution; and

generating a current in said electroplating solution between an anode and said substrate surface, said substrate surface functioning as a cathode;

wherein said electroplating solution comprises;

copper metal ions;

sulfuric acid at a concentration of about 10 grams per liter;

chloride ions at a concentration of about 50 milligrams per liter;

an accelerator at a concentration of about 30 parts per million (ppm), said accelerator consisting essentially of bis-(3-sulfopropyl)-disulfide (SPS);

a leveler at a concentration of about 2 ppm, said leveler consisting essentially of poly(vinyl pyrrolidone) (PVP) having an average molecular weight in a range of about from 3000 to 5000;

a suppressor at a concentration of about 200 ppm; and

a wetting agent at a concentration in a range of about from 80 ppm to 200 ppm;

wherein

said suppressor consists essentially of a formulation having an average molecular weight of about 2500 and a molar ratio of polypropylene glycol (PPG) to polyethylene glycol (PEG) of about 0.5; and

said wetting agent consists essentially of a block co-polymer of polyethylene glycol and polypropylene glycol having an average molecular weight of about 5900 and a molar ratio of polyethylene glycol (PEG) to polypropylene glycol (PPG) of about 0.4;

0.6.

12. A method as in claim 11, wherein a measured liquid-solid contact angle of said electroplating solution with said substrate surface is less than 60 degrees.

13. A method as in claim 12, wherein said measured liquid-solid contact angle is less than 50 degrees.

14. A method as in claim 13, wherein said measured liquid-solid contact angle is less than 45 degrees.

15. A method as in claim 14, wherein said measured liquid-solid contact angle is less than 40 degrees.

16. A method as in claim 11, wherein said substrate surface comprises a metal seed layer.