## EXTREME ULTRAVIOLET PHOTOLITHOGRAPHY METHOD WITH INFILTRATION FOR ENHANCED SENSITIVITY AND ETCH RESISTANCE 

This application claims the benefit of U.S. Provisional Application 62/752,692 entitled "Lithography Process with Improved Sensitivity and Etch Resistance," filed Oct. 30, 2018, herein incorporated by reference in its entirety. 

The semiconductor integrated circuit (IC) industry has experienced exponential growth. Technological advances in IC materials and design have produced generations of ICs where each generation has smaller and more complex cir› cuits than the previous generation. In the course of IC evolution, functional density (i.e., the number of intercon› nected devices per chip area) has generally increased while geometry size (i.e., the smallest component ( or line) that can be created using a fabrication process) has decreased. This scaling down process generally provides benefits by increas› ing production efficiency and lowering associated costs. Such scaling down has also increased the complexity of processing and manufacturing ICs. For example, as the semiconductor fabrication continues to shrink pitches below 20 nm nodes, traditional i-ArF were confronted a huge challenge. The optical restriction leads to resolution and lithography performance that camiot meet targets. Extreme ultraviolet (EUV) lithography has been utilized to support critical dimension (CD) requirements of smaller devices. EUV lithography employs scamiers using radiation in the EUV region, having a wavelength of about 1 nm to about 100 nm. Some EUV scamiers provide 4x reduction projec- tion printing onto a resist film coated on a substrate, similar to some optical scanners, except that the EUV scanners use reflective rather than refractive optics. EUV lithography has imposed a complex set of requirements upon the photoresist film. The photo acid generator (PAG) in ArF resist absorbs 193 nm wave and generates photoacid, and the acid has 1000 times chemical amplifier reaction (CAR) and deprotects acid labile group. However, the existing photoresist is not sen› sitive to EUV. Due to low source power of EUV tool and other factors, photoresist is not efficient to generate enough acid for desired resolution, leading to various patterning issues, such as line width roughness and CD uniformity. What are needed are a photoresist and a method of lithog› raphy patterning to have improvements in this area. 

## BRIEF DESCRIPTION OF THE DRAWINGS 

The present disclosure is best understood from the fol› lowing detailed description when read with the accompany› ing figures. It is emphasized that, in accordance with the standard practice in the industry, various features are not drawn to scale and are used for illustration purposes only. In fact, the dimensions of the various features may be arbi› trarily increased or reduced for clarity of discussion. 

FIG. 1 illustrates a flowchart of a lithography patterning method in accordance with some embodiments. 

FIGS. 2, 3 and 4 illustrate flowcharts of a lithography patterning method in accordance with various embodiments. 

FIGS. SA, SB, SC, SD, SE, SF and SG illustrate cross› sectional views of a semiconductor structure at various fabrication stages, in accordance with some embodiments. 

## BACKGROUND 

FIGS. 6A and 6B illustrate cross-sectional views of a semiconductor structure at various fabrication stages, in accordance with some embodiments. 

FIG. 7 illustrates a cross-sectional view of a semiconduc- tor structure at various fabrication stages, in accordance with some embodiments. 

FIG. 8 illustrates a photoresist material of FIG. SA in accordance with some embodiments. 

The following disclosure provides many different embodiments, or examples, for implementing different fea- tures of the provided subject matter. Specific examples of components and arrangements are described below to sim› plify the present disclosure. These are, of course, merely examples and are not intended to be limiting. For example, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact and may also include embodiments in which addi› tional features may be formed between the first and second features, such that the first and second features may not be in direct contact. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed. 

Moreover, the formation of a feature on, connected to, and/or coupled to another feature in the present disclosure that follows may include embodiments in which the features are formed in direct contact, and may also include embodi› ments in which additional features may be formed interpos› ing the features, such that the features may not be in direct contact. In addition, spatially relative terms, for example, "lower," "upper," "horizontal," "vertical," "above," "over," "below," "beneath," "up," "down," "top," "bottom," etc. as well as derivatives thereof (e.g., "horizontally," "down› wardly," "upwardly," etc.) are used for ease of the present disclosure of one features relationship to another feature. The spatially relative terms are intended to cover different orientations of the device including the features. Still further, when a number or a range of numbers is described with "about," "approximate," and the like, the term is intended to encompass numbers that are within a reasonable range including the number described, such as within +/-10% of the number described or other values as understood by person skilled in the art. For example, the term "about 5 nm" encompasses the dimension range from 4.5 nm to 5.5 nm. 

The present disclosure is generally related to methods for semiconductor device fabrication, and more particularly to a lithography patterning process associated extreme ultravio› let (EUV) radiation. In lithography patterning, after a pho- toresist ( or simply resist) film is exposed to a radiation, such as a EUV radiation, it is developed in a developer (a chemical solution). The developer removes portions (such as exposed portions as in a positive-tone photoresist or unex› posed portions as in a negative-tone photoresist) of the photoresist film, thereby forming a photoresist pattern which may include line patterns and/or trench patterns. The pho› toresist pattern is then used as an etch mask in subsequent etching processes, transferring the pattern to an underlying material layer. Alternatively, the photoresist pattern is then used as an ion implantation mask in subsequent ion implan› tation processes applied to the underlying material layer, such as an epitaxial semiconductor layer. 

## DETAILED DESCRIPTION 

