Formation method of local air gaps

Abstract

The invention discloses a formation method of local air gaps. The method includes: depositing ultralow dielectric material on a substrate to form an ultralow dielectric film, and removing part of the ultralow dielectric material to form a first metal layer; depositing ultralow dielectric material on the first metal layer to form another ultralow dielectric film, subjecting the ultralow dielectric film to plasma treatment to obtain a transition layer; depositing spin-coating ultralow dielectric material on the transition layer to form a spin-coating dielectric film, removing part of the spin-coating ultralow dielectric material to form a second metal layer, and removing part of the other ultralow dielectric film with the transition layer to form interconnecting vias; etching to remove the spin-coating material on the dielectric films, except for the part outside the second metal layer, and depositing ultralow dielectric material to form air gaps. The formation process of the local gaps is simplified, and subsequent production is facilitated.

Description

technical field [0001] The invention belongs to the field of semiconductor manufacturing, and in particular relates to a method for forming a local air gap. Background technique [0002] In semiconductor chips such as high-performance processors, microcontrollers and communication chips, etc., it is usually necessary to set up a high-speed interconnection structure in an independent chip to perform different functions such as logic operations, data storage and reading, and control. The provision of signals, etc. It can be seen that the interconnection structure will affect the running speed of the chip to a certain extent. For example, due to the signal delay in the interconnection structure, the running speed of the chip is close to the limit. The signal delay in the interconnection structure is proportional to the RC product of the interconnection structure, R represents the interconnection equivalent resistance of the interconnection lines in the interconnection structur...

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Problems solved by technology

The other is a localized air gap formation method, that is, after the interconnection structure is completed, reverse etching is performed, and the feature of air gaps will be formed when the feature size is small by using the plasma gas deposition method. The size of the place will be completely covered, and each layer of interconnection structure will increase the etching, film deposition, CMP (chemical mechanical polishing) and other processes, and the process is more complicated.

For example, in the US patent US7790601B1, it is a method of local air gaps. By additionally introducing a photolithography mask, photolithography, etching, etc. are performed between wires of a specific size, and the process is relatively complicated.

In addition, since the feature size is already the smallest size on the mask plate, the alignment, photolithography, etching, etc. caused by the additionally introduced photolithography mask will bring inconvenience to subsequent production

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