US 6,582,525 B2 · Methods for processing a workpiece using steam and ozone

Abstract

In a method for processing a workpiece to remove material from a first surface of the workpiece, steam is introduced onto the first surface under conditions so that at least some of the steam condenses and forms a liquid boundary layer on the first surface. The condensing steam helps to maintain the first surface of the workpiece at an elevated temperature. Ozone is provided around the workpiece under conditions where the ozone diffuses through the boundary layer and reacts with the material on the first surface. The temperature of the first surface is controlled to maintain condensation of the steam.

Drawings

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Drawings

Claims41

Dependent claims

A method for processing a workpiece to remove material from a first surface of the workpiece, comprising the steps of:

providing steam onto the first surface under conditions so that at least some of the steam condenses and forms a liquid boundary layer on the first surface, with the condensing steam contributing to maintaining the workpiece first surface at an elevated temperature;
introducing gaseous ozone around the workpiece under conditions where the ozone diffuses through the boundary layer and reacts with the material on the first surface to remove the material;
and
controlling the temperature of the first surface to maintain condensation of the steam.

1 more element

Dependencies are inferred from the claim text.

Description9,782 words

Summary1,114 words

#The cleaning of semiconductor wafers is often a critical step in the fabrication processes used to manufacture integrated circuits or the like. The geometries on wafers are often on the order of fractions of a micron, while the film thicknesses may be on the order of 20 Angstroms. This renders the devices highly susceptible to performance degradation due to organic, particulates or metallic/ionic contamination. Even silicon dioxide, which is used in the fabrication structure, can be considered a contaminant if the quality or thickness of the oxide does not meet design parameters.

#Although wafer cleaning has a long history, the era of “modern” cleaning techniques is generally considered to have begun in the early 1970s when RCA developed a cleaning sequence to address the various types of contamination. Although others developed the same or similar processes in the same time frame, the general cleaning sequence in its final form is basically the same.

#The first step of the RCA cleaning sequence involves removal of organic contamination using sulfuric acid and hydrogen peroxide mixtures. Ratios are typically in the range of 2:1 to 20:1, with temperatures in the range of 90-140 degrees Celsius. This mixture is commonly called “piranha.” A recent enhancement to the removal of organic contamination replaces the hydrogen peroxide with ozone that is bubbled or injected into the sulfuric acid line.

Brief description of the drawings7 figures

#FIG. 1 is a schematic block diagram of one embodiment of an apparatus for treating a semiconductor workpiece in which ozone is injected into a line containing a pressurized treatment liquid.

#FIG. 2 is a schematic block diagram of one embodiment of an apparatus for treating a semiconductor workpiece in which the semiconductor workpiece is indirectly heated by heating a treatment liquid that is sprayed on the surface of the workpiece.

#FIG. 3 is a flow diagram illustrating one embodiment of a process flow for treating a semiconductor workpiece with a treatment fluid and ozone.

Detailed description8,432 words

#A novel chemistry, application technique, and system is used to reduce the contamination and speed up processing in the manufacturing of semiconductor wafers, memory disks, photomasks, optical media, and other substrates (collectively referred to here as “wafers”) requiring a high level of clean. Contamination may occur from organics, particles, metal/ions, and silicon dioxide. Cleaning of wafers is achieved by delivery of a chemical stream to the workpiece surface. Ozone is delivered either into the liquid process stream or into the process environment. The chemical stream, which may be in the form of a liquid or vapor, is applied to the wafer in a system which allows for control of the liquid boundary layer thickness. 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.

#Wafers are preferably placed in a standard Teflon wafer cassette, or in a centrifugal process chamber utilizing a “carrierless” rotor design. During processing, the wafers and/or cassette are preferably rotated in the chamber.

#A processing solution is preferably heated and sprayed onto the wafer surface. This heats the surface of the wafer as well as the environment. If the spray is shut off, a thin liquid film remains on the wafer surfaces. However, preferably the liquid spray is continued for the duration of the chemical process step. If the wafer surface is hydrophobic, a surfactant may be added to the liquid chemical to create a thin film of liquid on the surfaces. The boundary layer of the processing solution at the wafer surface is advantageously controlled through the use of the rotation rate, the flow rate of the processing solution, and/or the injection technique (nozzle design) used to deliver the liquid (or steam) stream to the surfaces of the wafers.

Facts

Application

09/929,437Filed 14 Aug 2001 · continuation

Priority

9 May 1997

Published

US 2002/0020436 A121 Feb 2002

Granted

24 Jun 2003

Term ended

9 May 2017

Estimated · how

20 years from earliest known nonprovisional domestic filing plus recorded patent term adjustment. Maintenance-fee lapses, terminal disclaimers and statutory extensions have not been checked. The continuity chain may be incomplete; this is not an enforceability determination.

Classification12 codes

H10P 70/18
Cleaning before device manufacture, i.e. Begin-Of-Line process: by combined dry cleaning and wet cleaning
B08B 3/02
Cleaning by methods involving the use or presence of liquid or steam: cleaning by the force of jets or sprays
B08B 3/08
Cleaning involving contact with liquid: the liquid having chemical or dissolving effect
B08B 7/00
Cleaning by methods not provided for in a single other subclass or

Family

Application08/853,649Parent of this continuation-in-part · filed 9 May 1997

Application09/061,318Parent of this continuation-in-part · filed 16 Apr 1998

PCT/US99/08516Parent of this continuation-in-part · filed 16 Apr 1999

Application09/621,028Parent of this continuation · filed 21 Jul 2000

US 2002/0020436 A1Pre-grant publication · published 21 Feb 2002

Application09/621,028Parent of this continuation-in-part

PCT/US99/08516Parent of this continuation-in-part

Application09/061,318Parent of this continuation-in-part

US 6,240,933 B1Parent of this continuation-in-part

US 6,869,487 B1Related patent

US 6,582,525 B2This patent

From the US filing history. Foreign family members aren’t listed.

Timeline

9 May 1997Priority claimedParent application 08/853,649
14 Aug 2001Application filedUS 09/929,437
21 Feb 2002PublishedUS 2002/0020436 A1
24 Jun 2003GrantedUS 6,582,525 B2
9 Oct 2013Assigned to Oem Group, Inc.assignment of assignor's interest
14 Mar 2016Assigned to Oem Group, LLCchange of name
5 Apr 2016Assigned to Thl Corporate Finance, Inc., AS Collateral Agentsecurity interest
9 May 2017Term endedEstimated

Methods for processing a workpiece using steam and ozone

Life of this patent

Methods for processing a workpiece using steam and ozone

Life of this patent

Life of this patent

Abstract

Drawings

Drawings

Claims41

Description9,782 words

Drawings

Classification12 codes

Life of this patent

Description9,782 words