Processing a workpiece using water, a base, and ozone

• US 20050133067A1
• Filed: 12/06/2004
• Published: 06/23/2005
• Est. Priority Date: 05/09/1997
• Status: Active Grant

• Current Assignee: OEM Group, LLC
• Original Assignee: Semitool Incorporated (Applied Materials Incorporated)
• Inventors: Bergman, Eric J.
• Granted Patent: US 7,163,588 B2
• Time in Patent Office: Days
• US Class Current: 134/26
• CPC Class Codes: B08B 2203/005 the liquid being ozonated
• CPC Class Codes: B08B 2203/007 Heating the liquid
• CPC Class Codes: B08B 2230/01 Cleaning with steam
• CPC Class Codes: B08B 3/00 Cleaning by methods involving the use or presence of liquid or steam B08B9/00 takes precedence
• CPC Class Codes: B08B 3/02 Cleaning by the force of jets or sprays
• CPC Class Codes: B08B 3/044 using agitated containers in which the liquid and articles or material are placed by means of ultrasonic vibrations B08B3/12; cleaning casks or barrels by agitating B08B9/0817; mixers with shaking, oscillating or vibrating mechanisms B01F31/00
• CPC Class Codes: B08B 3/08 the liquid having chemical or dissolving effect substances used, see the relevant classes
• CPC Class Codes: B08B 7/00 Cleaning by methods not provided for in a single other subclass or a single group in this subclass
• CPC Class Codes: H01L 21/02052 Wet cleaning only H01L21/02085 takes precedence
• CPC Class Codes: H01L 21/02054 combining dry and wet cleaning steps H01L21/02085 takes precedence
• CPC Class Codes: H01L 21/6704 for wet cleaning or washing
• CPC Class Codes: H01L 21/67051 using mainly spraying means, e.g. nozzles
• CPC Class Codes: Y10S 134/902 Semiconductor wafer

Abstract

Contaminants such as photoresist are quickly removed from a wafer having metal features, using water, ozone and a base such as ammonium hydroxide. Processing is performed at room temperature to avoid metal corrosion. Ozone is delivered into a stream of process liquid or into the process environment or chamber. Steam may alternatively be used. A layer of liquid or vapor forms on the wafer surface. The ozone moves through the liquid layer via diffusion, entrainment, jetting/spraying or bulk transfer, and chemically reacts with the photoresist, to remove it.

Claims

1. A method for cleaning at least one workpiece, comprising:

placing the workpiece into a chamber;

applying a liquid onto the workpiece, with the liquid including water and ammonium hydroxide; and

providing ozone in the chamber.

2. The method of claim 1 with the cleaning liquid having a concentration of ammonium hydroxide ranging from about 1500:

1 to 3000;

1.

3. The method of claim 1 further comprising heating one or more of the liquid, the workpiece, and the chamber.

4. The method of claim 1 further comprising forming the liquid into a layer on the workpiece and controlling the thickness of the liquid layer by one or more of rotating the workpiece, adding a surfactant, or controlling the flow rate of the liquid.

5. The method of claim 1 where the liquid is applied to the workpiece by spraying the liquid onto the surface of the workpiece at a controlled flow rate.

6. A method for removing photoresist from a surface of a workpiece, comprising:

applying a liquid onto a surface of the workpiece having a coating of photoresist, with the liquid including water and a base at a water to base concentration ranging from about 1000;

1 to 5000;

1;

forming the liquid into a layer on the workpiece;

controlling the thickness of the liquid layer; and

providing ozone to the liquid layer, with the ozone oxidizing the photoresist in the presence of the liquid, and removing the photoresist.

7. The method of claim 6 further comprising heating the liquid to about 30-100°

C.

8. The method of claim 6 where the liquid is applied to the photoresist by spraying the liquid at a controlled flow rate.

9. The method of claim 6 further including placing the workpiece into a chamber, closing the chamber, and providing ozone into the chamber as a gas separate from the liquid.

10. The method of claim 6 further including placing the workpiece into a chamber, closing the chamber, and providing ozone into the chamber along with the liquid.

11. The method of claim 6 where the photoresist is a negative photoresist.

23. The method of claim 6 wherein the workpiece has one or more metal features and with the liquid at about 15-29°

C. to avoid substantial corrosion of the metal features.

27. The method of claim 6 where the base comprises tetra-methyl ammonium hydroxide, KOH or NaOH.

12. A method for reducing corrosion of metal features on a wafer during cleaning of the wafer, comprising:

contacting the wafer with a liquid including water and ammonium hydroxide;

contacting the wafer with ozone; and

with the ammonium hydroxide acting to reduce corrosion of the metal features, in the presence of water and ozone.

13. The method of claim 12 further comprising:

placing the wafer into a chamber;

forming the heated liquid into a liquid layer on the wafer;

controlling the thickness of the liquid layer; and

introducing ozone into the chamber.

14. The method of claim 12 further including heating the liquid to 30-100°

C.

15. The method of claim 12 with the concentration of ammonium hydroxide weight in the liquid ranging from about 20:

1 to about 250;

1.

16. The method of claim 12 wherein at least one of the metal features comprises NiCr.

17. The method of claim 12 wherein at least one of the metal features comprises silver.

18. The method of claim 12 wherein the workpiece includes one or more MEMS devices.

19. The method of claim 12 further comprising spinning the workpiece.

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36. A method for cleaning a workpiece having an NiCr film, comprising:

placing the workpiece into a chamber;

heating a liquid including water and ammonium hydroxide to a temperature ranging from about 30-100°

C.;

introducing the liquid onto the workpiece; and

introducing ozone to the workpiece.