Preparation method of Cu (C) film with high heat stability and low resistivity

Abstract

The invention relates to a preparation method of a Cu (C) film with high heat stability and low resistivity, belonging to the field of new materials. In the preparation method, the enthalpy of mixing and the atomic size are used as criteria of adding elements, a phase diagram is matched, C is selected as a doped element, and a solid solution model is used as a theoretical basis, thereby sputtering a Cu (4at%C) film on an Si substrate. The preparation method of the film comprises a substrate cleaning process, a vacuum pumping process of equipment and a sputtering process, wherein the sputtering power is 340W, the sputtering time is 20min, the argon gas flow is 220sccm, the working air pressure is 0.6Pa, and the thickness of the obtained Cu (C) film is 250nm. As a proper amount of element Cis added into the Cu film and a self-passivation amorphous layer is formed, the diffusion between Cu and Si can be effectively blocked; after the film is treated by vacuum annealing, the Cu film withlow resistivity can be obtained; and heat stability of the Cu film is improved by adding C.

Description

technical field [0001] The invention relates to a preparation method of a C-doped Cu thin film with high thermal stability and low resistivity, belonging to the field of new materials. Background technique [0002] Copper has high electrical conductivity and good resistance to electromigration, and is widely used as an interconnect metal in advanced VLSI. However, copper can react with silicon at a relatively low temperature (about 200°C), resulting in device damage. Therefore, it is necessary to add a diffusion barrier layer between copper and silicon to block the diffusion between copper and silicon. With the gradual reduction of the feature size of the device, the thickness of the diffusion barrier layer is required to be reduced accordingly. Referring to the international semiconductor development route, for the 32nm and 22nm processes, the thickness of the diffusion barrier layer is required to be 7nm and 4nm respectively. In order to achieve the diffusion barrier effe...

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Problems solved by technology

However, the interface between the self-passivation layer and the Si substrate is often not smooth, and the thickness of the film layer is usually uncontrollable, which will lead to unstable conductivity.

The third is non-metallic atoms with small atomic size. Because there are few studies, the results of this type of atoms are not very comprehensive. At present, some small atoms also have the effect of improving thermal stability, but the mechanism is not very clear, and the performance test is not very clear. very stable

[0005] Because the barrier performance mechanism of the added elements is not yet clear, there is no direct basis for the selection of the added elements, and there is no obvious basis for the amount of the added elements. The literature reports the resistance and stability performance measurement results under a certain amount of addition. There is no Determine if this addition is the optimal value

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