Method for improving uniformity of pattern critical dimensions in photoetching process

Abstract

The invention discloses a method for improving the uniformity of pattern critical dimensions in a photoetching process. The method comprises the following steps: 1, measuring the influence of various local pattern densities on the pattern critical dimensions in corresponding pattern periods in various pattern periods, and establishing a photoetching process regulation rule according to a measurement result; 2, making local pattern density statistics on local-layer patterns of a designed product layout; 3, regulating photomask critical dimensions corresponding to each pattern of the local-layer patterns according to a local pattern density distribution of the local-layer patterns and the photoetching process regulation rule. According to the method, the influence of changes of the local pattern densities in the layout on the pattern critical dimensions can be eliminated, each pattern critical dimension under the various local pattern densities tend to be the same as a design requirement, and the uniformity of the pattern critical dimensions is improved.

Description

technical field [0001] The invention relates to a method for manufacturing a semiconductor integrated circuit, in particular to a method for improving the uniformity of key dimensions of patterns in a photolithography process. Background technique [0002] The resolution limit of the lithography process: P=k1×NA / λ, P is the half cycle of the pattern, that is, the resolution limit, k1 is the lithography process coefficient, NA is the numerical aperture of the exposure equipment, and λ is the wavelength of the exposure light source. [0003] As the critical dimension (CD) of the pattern gets smaller and smaller, approaching the exposure limit or resolution limit, the influence of environmental factors of various non-lithographic processes begins to become larger and larger. The effect becomes more and more obvious when k1<0.4. [0004] Usually, the loading effect caused by the pattern density is considered to have no effect on the lithography process, but when the CD becom...

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Problems solved by technology

[0010] And when CD is getting smaller and smaller, the corresponding k1 is getting smaller and smaller, and the change of CD caused by local pattern density will become larger and larger, the existing two adjustment methods of redundant pattern filling and optical proximity effect correction cannot Eliminate the influence of local pattern density on CD variation, that is, in the existing process, local pattern density will have an impact on the CD of the actual pattern structure finally formed on the wafer

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