Method to deposit an impermeable film on porous low-k dielectric film

Abstract

A method for improving the adhesion of an impermeable film on a porous low-k dielectric film in an interconnect structure is disclosed. The method provides an in-situ annealing step before the deposition of the impermeable film to release the volatile trapped molecules such as water, alcohol, HCl, and HF vapor, inside the pores of the porous low-k dielectric film. The method also provides an in-situ deposition step of the impermeable film right after the deposition of the porous low dielectric film without exposure to an atmosphere containing trappable molecules. The method further provides an in-situ deposition step of the impermeable film right after the removal a portion of the porous low-k dielectric film without exposure to an atmosphere containing trappable molecules. By the removal of all trapped molecules inside the porous low-k dielectric film, the adhesion between the deposited impermeable film and the low-k dielectric film is improved. This method is applicable to many porous low-k dielectric films such as porous hydrosilsesquioxane or porous methyl silsesquioxane, porous silica structures such as aerogel, low temperature deposited silicon carbon films, low temperature deposited Si—O—C films, and methyl doped porous silica.

Description

REFERENCE TO RELATED APPLICATIONS [0001] This application is a divisional application of U.S. patent application Ser. No. 10 / 360,133, filed Feb. 4, 2003, (Atty. Docket No. TEGL-01187US0), which is incorporated herein by reference.FIELD OF THE INVENTION [0002] This invention relates generally to integrated circuit processes and fabrication, and more particularly, to a method to deposit an impermeable film on a porous low-k dielectric film. BACKGROUND OF THE INVENTION [0003] The demand for progressively smaller, less expensive, and more powerful electronic products creates a need for smaller geometry integrated circuits (ICs) and larger substrates. It also creates a demand for denser packaging of circuits onto IC substrates. The desire for smaller geometry IC circuits requires that the dimensions of interconnections between the components and the dielectric layers be as small as possible. Therefore, recent research continues to focus on the use of low resistance materials (e.g., coppe...

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Benefits of technology

[0016] Accordingly, a method of improving the adhesion of a subsequently deposited impermeable film onto a porous low-k dielectric film is provided.

[0025] The anneal temperature can be between 50° C. to 500° C. Higher temperatures can drive out moisture in a shorter time, but the higher temperature can damage the porous low-k dielectric films. The anneal time can be between 10 seconds to 2 hours, depending on the anneal temperature and the state of the porous low-k dielectric films. A resistive or a radiative heater can be used for the anneal process. The anneal process can be done in an inert gas ambient such as helium, argon, or nitrogen. The anneal process can also be done in a reactive ambient such as in NH3 or hydrogen. The anneal process can also be done in a sub-atmospheric pressure ambient, typically in a pressure of a few Torr or a few milliTorr.

Problems solved by technology

But our research indicates that these methods can only reduce the amount of moisture absorption, but cannot eliminate it.

Our research indicates that this treatment is not at all effective in improving the adhesion of TiN on the porous low-k dielectric film after exposing to air even for a few hours.

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