EUV lithography is the most promising new technology for the next node of semiconductor devices. Unfortunately, the
high energy photons are likely to generate more contamination than observed with ArF or KrF light which can reduce the
transmission of the EUV optics. Resist outgassing is considered to be an important contamination source, however, not
enough is known about the way a resist composition influences the contamination growth rate, while this information is
crucial to guide the development of EUV resists.
To reduce the knowledge gap, FUJIFILM and imec started a joint effort aimed at systematically exploring the
contribution of the different resist components and at understanding the effect of chemical modifications of the different
components on the contamination tendency of resists. The project focuses on (1) the identification and quantification of
the outgassing components from resist by RGA measurements, (2) on the quantification of the resist related
contamination rate by witness sample (WS) testing, and (3) on the correlation between these two results knowing the
details of the resist chemistry.
To explore the effect of the resist composition upon contamination growth, the following approach was followed. The
focus was put on chemically amplified resists (CAR), since this chemistry is mostly used in EUV lithography. Both
PAG blended as well as PAG bound systems were explored, and the following resist components are individually varied:
polymer matrix, blocking groups, PAG type and concentration. In this way the total contamination of a resist can be
divided into the separate contributions of the different resist components upon the contamination growth rate, which is a
huge step forward in the understanding of optics contamination due to resist.