Method for improving boundary effect of metal work function

Abstract

The invention provides a method for improving a metal work function boundary effect. The method comprises the steps of: depositing a first TiN layer on a first Fin structure, a second Fin structure, a third Fin structure and a fourth Fin structure; distributing the first TiN layers on the second Fin structure and the third Fin structure continuously; removing the first TiN layer on the third Fin structure; locating and pushing the edge of the removed first TiN layer at the center line of the second Fin structure and the third Fin structure towards the second Fin structure by a first distance; depositing second TiN layers, wherein the second TiN layers on the second and third Fin structures are continuously distributed; removing the second Fin structure and the second and first TiN layers on the second Fin structure; and removing the part, close to the second Fin structure, of the second TiN layer between the second Fin structure and the third Fin structure, and pushing the edge of the removed second TiN layer towards the second Fin structure by a second distance from the center line of the second Fin structure and the third Fin structure. By adopting the method provided by the invention, the thickness of the TiN layer at the edge of the bottom of the Fin structure of the P-type tube with the ultralow threshold voltage can be thinner; and during etching, the TiN layer is not easy to have a bottom cutting phenomenon, so that the metal boundary effect is reduced, and the threshold voltage of the device is increased.

Description

technical field [0001] The invention relates to the technical field of semiconductors, in particular to a method for improving the boundary effect of metal work function. Background technique [0002] The current of 14nm FinFET in the prior art is prone to metal boundary effect (MBE, Metal boundary effect), especially between the Fin of N-type SRAM and P-type SRAM, because during the manufacturing process, the Fin side of P-type SRAM is covered The bottom of the TiN will appear cut off at the bottom of the edge, such as figure 1 as shown, figure 1 It is a structural schematic diagram showing a cut-off phenomenon (TiN undercut) at the bottom of the side of the Fin structure in the prior art; and the increase of the metal boundary effect will lead to a gradual decrease in the threshold voltage of the P-type SRAM. [0003] Therefore, it is necessary to increase the threshold voltage of 14nm FinFET, and its metal boundary effect must be reduced. Contents of the invention ...

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Problems solved by technology

[0004] In view of the shortcomings of the prior art described above, the purpose of the present invention is to provide a method for improving the metal work function boundary effect, which is used to solve the problem in the prior art that the threshold voltage of 14nm FinFET decreases with the increase of the metal boundary effect

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