Process and apparatus for treating a workpiece

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 of 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.

Description

[0001] This Application is a Continuation of U.S. patent application Ser. No. 09 / 621,028, filed Jul. 21, 2000 and now pending and incorporated herein by reference, which is a Continuation-in-Part of U.S. patent application Ser. No. PCT / US99 / 08516, which is a Continuation-in-Part of U.S. patent application Ser. No. 09 / 061,318, filed Apr. 16, 1998 and now abandoned, which is a Continuation-in-Part of U.S. patent application Ser. No. 08 / 853,649, filed May 9, 1997, now U.S. Pat. No. 6,240,933. This Application also is a Continuation-in-Part of U.S. patent application Ser. No. 60 / 145,350, filed Jul. 23,1999.FIELD OF THE INVENTION [0002] 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 ...

AI Technical Summary

Benefits of technology

[0006] 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 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.

[0007] While ozone has a limited solubility in the hot liquid solution, it is still able to diffuse through the solution and react with the surface of the wafer (whether it is silicon, photoresist, etc.) at the liquid / solid interface. Thus diffusion, rather than dissolution, is the primary mechanism used to deliver ozone to the surfaces of the wafers. Water apparently helps to hydrolyze carbon-carbon bonds or accelerate the oxidation of silicon surfaces by hydrolyzing silicon-hydrogen or silicon-hydroxyl bonds. The elevated temperature promotes the reaction kinetics and the high concentration of ozone in the gas phase promotes diffusion of the ozone through the liquid film, even though the increased temperature of the liquid film does not result in a solution having a high concentration of ozone dissolved in it.

[0008] The flow of ozone can be delivered to the process chamber through a vapor generator or the like. Such a generator is filled with water, which is temperature controlled. Thus the ozone gas stream is enriched with water vapor which maintains the boundary layer on each wafer surface at a minimal thickness so that the layer does not inhibit diffusion. At the same time, such delivery assists in preventing the wafers from drying completely during the process.

[0009] A high capacity ozone generator is preferably used to produce a mixed effluent containing a high concentration of ozone in combination with a high flow rate. A higher concentration of ozone increases the quantity of ozone provided to the surface of the wafer. A higher flow rate increases the rate at which fresh reactants are replenished, and spent or exhausted reactants are carried away from the wafer.

[0013] 1) The use of a temperature controlled liquid chemical source delivered to the wafer surface to stabilize the temperature of the wafer and, depending on the liquid utilized, provide a supply of water to support hydrolysis of the carbon-carbon bonds of contaminants at the surface of each wafer.

[0016] 4) The process utilizes a mixed effluent having a higher concentration of ozone in combination with a higher flow rate for increasing the rate at which fresh reactants are supplied to the surface of the wafer.

Problems solved by technology

This renders the devices highly susceptible to performance degradation due to organic, particulates or metallic / ionic contamination.

While this process has been effective for a number of years, it nevertheless has certain deficiencies.

Such deficiencies include the high cost of chemicals, the lengthy process time required to get wafers through the various cleaning steps, high consumption of water due to the need for extensive rinsing between chemical steps, and high disposal costs.

However, such cleaning processes have failed to fully address all of the major cleaning concerns of the semiconductor processing industry.

More particularly, they have failed to fully address the problem of minimizing contamination from one or more of the following contaminants: organics, particles, metals / ions, and silicon dioxide.

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