Method for making a chemical contrast pattern using block copolymers and sequential infiltration synthesis

Abstract

A method for making a chemical contrast pattern uses directed self-assembly of block copolymers (BCPs) and sequential infiltration synthesis (SIS) of an inorganic material. For an example with poly(styrene-block-methyl methacrylate) (PS-b-PMMA) as the BCP and alumina as the inorganic material, the PS and PMMA self-assemble on a suitable substrate. The PMMA is removed and the PS is oxidized. A surface modification polymer (SMP) is deposited on the oxidized PS and the exposed substrate and the SMP not bound to the substrate is removed. The structure is placed in an atomic layer deposition chamber. Alumina precursors reactive with the oxidized PS are introduced and infuse by SIS into the oxidized PS, thereby forming on the substrate a chemical contrast pattern of SMP and alumina. The resulting chemical contrast pattern can be used for lithographic masks, for example to etch the underlying substrate to make an imprint template.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]This invention relates generally to the use of block copolymers (BCPs) to make a chemical contrast pattern, and more particularly to the use of the chemical contrast pattern as an etch mask for pattern transfer into a substrate.[0003]2. Description of the Related Art[0004]Directed self-assembly (DSA) of block copolymers (BCPs) has been proposed for making imprint templates. Imprint templates have application in making patterned-media magnetic recording disks and in semiconductor manufacturing, for example, for patterning parallel generally straight lines in MPU, DRAM and NAND flash devices. DSA of BCPs by use of a patterned sublayer for the BCP film is well-known. After the BCP components self-assemble on the patterned sublayer, one of the components is selectively removed, leaving the other component with the desired pattern, which can be used as an etch mask to transfer the pattern into an underlying substrate. The et...

AI Technical Summary

Benefits of technology

[0008]Embodiments of the invention relate to methods that use DSA of BCPs and take advantage of SIS to make a chemical contrast pattern. For the example with PS and PMMA as the BCP components, in contrast to the conventional SIS method, embodiments of the invention remove the PMMA prior to the ALD and makes the PS the active material for the ALD. The inorganic material grown by ALD in the active PS replicates the original pattern without major image quality distortions.

Problems solved by technology

While the conventional SIS method provides a way to use the distinct chemistries of the constituent components of a BCP film to grow materials by ALD on specific locations, the density of active sites where the ALD precursor can bind is extremely low, especially when using the method to achieve dimensions down to a few nanometers.

It has been found that after removal of all of the polymer material (the PS and PMMA in the above example), the amount of inorganic material (alumina in the above example) is not sufficient to make a robust etch mask.

This is because the remaining features may be discontinuous or may have shifted as the PS and PMMA is removed, thus degrading the image quality of the original pattern.

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