Ruthenium silicide wet etch

Abstract

A method of removing ruthenium silicide from a substrate surface which comprises exposing the ruthenium silicide surface to a solution containing chlorine and fluorine containing chemicals. In particular, said solution is designed to react with said ruthenium silicide film such that water-soluble reaction products are formed.

Description

RELATED APPLICATIONS [0001] This application is a continuation of prior application Ser. No. 10 / 421,976 filed Apr. 23, 2003, now U.S. Pat. No. 6,908,569, which is a divisional application of prior application Ser. No. 10 / 165,801 filed Jun. 7, 2002, which is a divisional application of prior application Ser. No. 09 / 799,791 filed Mar. 5, 2001, now U.S. Pat. No. 6,498,110, all of which are hereby incorporated by reference in their entirety.BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] This invention relates to silicon integrated circuit processing and, more particularly, to a process for selectively removing ruthenium silicide from a semiconductor substrate. [0004] 2. Description of the Related Art [0005] Semiconductor devices are typically made up of varying levels of components, each of which are formed from different materials. During the process of fabricating a semiconductor device, the device layers are repeatedly subjected to high temperature processes that...

AI Technical Summary

Benefits of technology

The present invention provides a method for selectively removing ruthenium silicide from a substrate surface without affecting other non-ruthenium areas. This is achieved by using a hypochlorite salt based solution that effectively dissolves ruthenium silicide without significantly affecting other materials on the substrate surface. The method can be performed in a simple and cost-effective manner and can be adapted to selectively remove ruthenium silicide from a substrate surface without masking it, reducing the number of processing steps and the risk of incurring defects.

Problems solved by technology

During the process of fabricating a semiconductor device, the device layers are repeatedly subjected to high temperature processes that can result in diffusion of species between layers.

Diffusion of species of atoms or molecules, such as oxygen, for example, can result in degraded performance of different components of the semiconductor device.

This problem occurs in a number of different semiconductor devices such as interconnects or capacitors.

However, due to the limitations of known manufacturing methods, the typical dielectric layer often suffers from a substantially large concentration of oxygen vacancy defects.

Unfortunately, the presence of oxygen vacancies within the dielectric causes the dielectric layer to have a decreased dielectric constant as well as a decreased electrical resistance.

Furthermore, the problems associated with oxygen vacancies within dielectric materials are becoming more apparent as integrated circuits are formed with increasingly smaller circuit elements.

Furthermore, the dielectric constant and the electrical resistance of these high-k materials are especially sensitive to the presence of oxygen vacancies.

Thus, these capacitor structures are more likely to be formed with an insufficient capacitance for developing a detectable charge as well as an insufficient resistance for maintaining the detectable charge.

Disadvantageously, however, during the annealing operation the oxygen is known to diffuse through the dielectric layer and seep into the underlying bottom electrode, thus adversely affecting the electrical properties of the electrode.

The formation of silicon dioxide in the bottom electrode is undesirable as it has shown to result in open contacts.

This problem is especially prevalent in capacitors having bottom electrodes made of platinum, ruthenium oxide, or other metals that are particularly susceptible to silicon permeation.

However, the CVD process is known to deposit RuSix on the edges and backside of the wafer as well as any other unmasked surfaces such as clamping tools or other equipment used during deposition.

As a consequence, the excessive RuSix deposits have to be removed from the substrate surface prior to completion of wafer processing.

Although a number of etchants have been developed for removing ruthenium metal, there is presently no known chemistry that can effectively remove ruthenium silicide in bulk.

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