Method of plasma etching of high-K dielectric materials with high selectivity to underlying layers

Abstract

A method of etching high dielectric constant materials using halogen gas and reducing gas chemistry. An embodiment of the method is accomplished using a 20 to 300 sccm of chlorine and 2 to 200 sccm of carbon monoxide, regulated to a total chamber pressure of 2-100 mTorr to etch a hafnium oxide layer.

Description

[0001] This application is a continuation of co-pending U.S. patent application Ser. No. 10 / 092,795, filed Mar. 6, 2002, which is incorporated herein by reference in its entirety.[0002] 1. Field of Invention[0003] The present invention relates generally to a method of dry etching semiconductor wafers. More specifically, the invention relates to a method of etching high K dielectric materials using a gas mixture comprising a halogen gas and a reducing gas.[0004] 2. Description of the Background Art[0005] Field effect transistors that are used in forming integrated circuit generally utilize a polysilicon gate electrodes deposited upon a gate dielectric that separates the electrode from the channel between source and drain regions. In prior art transistor structures, the gate dielectric is typically fabricated of silicon dioxide (SiO.sub.2). However, as integrated circuit transistors have become smaller (on the order of 100 nanometers in width), the thickness of the dielectric material...

AI Technical Summary

Benefits of technology

The present invention provides a method for etching materials with high dielectric constants, such as HfO, using a gas mixture of chlorine and carbon monoxide. This method can be practiced using a decoupled plasma source etch reactor, which maintains the substrate at a temperature of about 100-500 degrees Celsius. The etch process involves using a gas mixture of chlorine and carbon monoxide, with a total chamber pressure of about 4-200 mTorr. The invention can be used to etch hafnium-oxide films, resulting in a smooth and uniform surface with minimal damage. The technical effects of the invention include improved etching efficiency and reduced damage to the substrate.

Problems solved by technology

With such a thin dielectric, electrons can propagate from the polysilicon gate electrode into the transistor channel causing the transistor to operate improperly or become defective.

However, hafnium-oxide is such a stable dielectric material that it is very difficult to etch using conventional oxide etchants to form into gate structures without damaging other layers of material residing on the wafer.

As such, hafnium-oxide has found limited use in semiconductor devices.

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