Protection of porous substrates before treatment

Abstract

A method is provided for treating a surface of a porous material in an environment, the method comprising the steps of contacting a porous material with an organic gas in an environment having a pressure P1 and a temperature T1, wherein the organic gas is such that at the pressure P1 and at the temperature T1 it remains a gas when outside of the porous material but condenses as an organic liquid when in contact with the porous material, thereby filling pores of the porous material with the organic liquid, cooling down the filled porous material to a temperature T2 such that the organic liquid freezes within the pores, thereby sealing the pores with an organic solid, thereby providing a protected porous material, and performing a treatment on the surface.

Description

CROSS-REFERENCE TO RELATED APPLICATION[0001]Any and all priority claims identified in the Application Data Sheet, or any correction thereto, are hereby incorporated by reference under 37 CFR 1.57. This application claims the benefit of European Application No. EP 13184718.8 filed Sep. 17, 2013. The aforementioned application is incorporated by reference herein in its entirety, and is hereby expressly made a part of this specification.TECHNICAL FIELD OF THE INVENTION[0002]A method is provided for protecting porous materials against damages upon etching or modification of a surface thereof. In particular, the method relates to the field of semiconductor devices and to the protecting of low-k dielectrics against plasma induced damages.BACKGROUND OF THE INVENTION[0003]When a porous substrate needs to be treated by etching or modification of a surface thereof, damage of the substrate often occurs. This is particularly true with plasma mediated treatments. This is presumably caused by act...

AI Technical Summary

Benefits of technology

[0010]There is therefore a need in the art for a way to prevent damage to porous substrates upon treatment of the substrate (e.g., via etching or surface modification), which avoids the above drawbacks.

[0011]An object of the embodiments is to provide a method which permits the treatment of a porous material surface while protecting it from excessive damages.

[0012]It is an advantage of embodiments that it may ease the cleaning of the porous material after the treatment.

Problems solved by technology

When a porous substrate needs to be treated by etching or modification of a surface thereof, damage of the substrate often occurs.

Both oxidative and reductive plasmas have such detrimental effects.

These problems for instance occur in the field of microelectronics during integration of low-k dielectrics.

Furthermore, the method is rather complicated, tedious and labour-intensive since it involves synthesising a particular polymer having well defined end-groups, preparing a particular polymer solution, applying it homogeneously on the substrate (this implies good wettability and elaborated application techniques), and heating the solution to evaporate solvent and / or dry the polymer.

Furthermore, polymer deposition typically generates stresses in porous substrates.

Also, the polymer being retained in the pores in the final product, it potentially influences the properties of the dielectrics making them harder to control.

Last but not least, polymers tend to have difficulties completely filling pores and / or entering the smallest pores, resulting in a filling which is not optimally dense (see FIG. 7 (P)).

However, removing a polymer by thermal means implies degrading it and thereby the possibility of leaving polymer residues in the pores.

Also, it is energy intensive.

Furthermore, the other drawbacks proper to the use of polymers remain as mentioned above for US2005 / 0148202.

Although this method is effective at preventing much damage to porous substrates, some damages still occurs.

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