Process and apparatus for treating a workpiece such as a semiconductor wafer

• US 6,869,487 B1
• Filed: 07/21/2000
• Issued: 03/22/2005
• Est. Priority Date: 05/09/1997
• Status: Expired due to Term

• Current Assignee: OEM Group, LLC
• Original Assignee: Semitool Incorporated (Applied Materials Incorporated)
• Inventors: Bergman, Eric J.
• Primary Examiner(s): EL ARINI, ZEINAB
• Application Number:
  US09/621,028
• Time in Patent Office: 1,705 Days
• Field of Search: 134/2, 134/3, 134/25.4, 134/30, 134/31, 134/33, 134/41, 134/102.1, 134/102.2, 134/108, 134/111, 134/199, 134/902, 134/18, 134/19
• US Class Current: 134/3
• 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 21/3065 Plasma etching; Reactive-ion etching
• 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: H01L 23/49582 Metallic layers on lead frames
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H05K 3/3426 characterised by the leads
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product
• CPC Class Codes: Y10S 134/902 Semiconductor wafer

Abstract

A novel chemistry, system and application technique reduces contamination of semiconductor wafers and similar substrates and enhances and expedites processing. A stream of liquid chemical is applied to the workpiece surface. Ozone is delivered either into the liquid process stream or into the process environment. The ozone is preferably generated by a high capacity ozone generator. The chemical stream is provided in the form of a liquid or vapor. A boundary layer liquid or vapor forms on the workpiece surface. The thickness of the boundary layer is controlled. The chemical stream may include ammonium hydroxide for simultaneous particle and organic removal, another chemical to raise the pH of the solution, or other chemical additives designed to accomplish one or more specific cleaning steps.

Claims

1. A method for processing a workpiece, comprising the steps of:

providing a liquid at a temperature in the range of about 25-150°

C. onto a surface of the workpiece;

introducing ozone into an environment containing the workpiece at a rate of at least 90 grams per hour;

controlling a thickness of the liquid on the workpiece so as to form a liquid layer that allows for diffusion of the ozone through the layer to the surface of the workpiece; and

reacting the ozone at the surface of the workpiece, to process the workpiece.

2. The method of claim 1 where the ozone is introduced at a rate of at least 130 grams per hour.

3. The method of claim 1 where the ozone is introduced at a flow rate of at least 10 lpm and a concentration of at least 10% by weight.

4. The method of claim 1 wherein the liquid comprises deionized water.

5. The method of claim 4 wherein the deionized water is superheated.

6. The method of claim 1 wherein the liquid includes sulfuric acid, hydrochloric acid, ammonium hydroxide, or deionized water.

7. The method of claim 1 wherein the step of controlling comprises the step of rotating the workpiece.

8. The method of claim 1 wherein the step of controlling comprises the step of rotating the workpiece at a rotation rate equal to or greater than about 300 rpm.

9. The method of claim 1 wherein the step of controlling comprises adding a surfactant to the liquid.

10. The method of claim 1 wherein the step of controlling comprises the step of spraying the liquid onto the surface of the workpiece at a controlled flow rate.

11. The method of claim 1 wherein the liquid includes water and HF at a concentration ratio of between about 50:

1 and 500;

1.

12. The method of claim 1 wherein the liquid includes water and HCl at a concentration ratio of between about 50:

1 and 500;

1.

13. The method of claim 1 wherein the liquid includes water, HF and HCl at a concentration ratio of between about 50:

1;

1 and 500;

1;

1.

14. The method of claim 1 wherein the liquid is at a temperature in the range of 55-120°

C.

15. The method of claim 1 wherein the liquid is range of 75-115°

C.

16. A method for cleaning a surface of a workpiece, comprising the steps of:

providing a heated liquid solution of water and at least one of HF and HCl onto the surface of the workpiece, with the heated solution assisting in maintaining the workpiece at a temperature in the range of about 25-150°

C.;

introducing ozone into an environment containing the workpiece at a rate of at least 90 grams per hour;

controlling a thickness of the heated liquid solution to form a thin liquid boundary layer on the surface of the workpiece to allow diffusion of the ozone through the boundary layer for reaction at the surface of the workpiece, to clean the workpiece.

17. A method for processing a workpiece, comprising the steps of:

providing an aqueous liquid boundary layer onto a surface of the workpiece with the liquid boundary layer at a temperature in the range of 55-120°

C.;

introducing ozone into an environment containing the workpiece at a rate of at least 90 grams per hour;

controlling a thickness of the aqueous liquid boundary layer to allow for diffusion of the ozone through the boundary layer and a reaction at the surface of the workpiece, to process the workpiece.

18. A system for processing a workpiece, comprising:

a process chamber;

means for forming a liquid boundary layer on the workpiece;

an ozone supply system for providing ozone directly or indirectly into the chamber, and having a capacity of at least 90 grams per hour, whereby the ozone can diffuse through the boundary layer to a surface of the workpiece; and

a heater for heating the aqueous liquid to a temperature in the range of 25-150°

C. before the liquid is provided onto the workpiece.

19. The system of claim 18 with the ozone supply system comprising a contactor for receiving the ozone and the liquid.

20. The system of claim 18 further comprising a rotor assembly in the chamber for rotating the workpiece.

21. The system of claim 18 where the ozone supply system generates a flow of ozone at a flow rate of at least 10 lpm and a concentration of at least 10% by weight.

22. The system of claim 18 where the heater comprises a steam boiler.

23. The system of claim 18 further comprising means for controlling a thickness of a liquid layer on the workpiece, including at least one of:

a rotor for rotating the workpiece;

a fluid flow controller or one or more nozzles adapted to generate fine droplets of the liquid.

24. The method of claim 18, wherein the liquid is range of 75-115°

C.

25. The method of claim 18 wherein the liquid is heated to a temperature in the range of 85-105°

C.