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Single exposure EUV patterning for lower pitches (below 32 nm L/S) proves to be challenging and dependent on a series of factors including exposure tool related parameters such as illumination conditions but also material related parameters such as sensitivity to EUV photons and resist chemistry. While the industry is focused on developing a set of universal exposure conditions that can be applied to all resist systems, material suppliers must constantly enhance the exposure mechanism of the resists in order to support further advance in technology. The multi-trigger concept involves a reaction that will only occur when multiple elements of the resist are initiated concurrently and in close spatial proximity in order to enable the catalytic reactions. In high dose areas the resist behaves like a traditional CAR, whilst in low dose areas, such as line edges, the reaction is second-order increasing the chemical gradient. Effectively there is a dose dependent quenching-like behaviour built into the resist, enhancing chemical contrast and thus resolution, whilst eliminating the materials stochastics impact of a separate quencher reducing roughness. The multi-trigger resist (MTR) presented consists of a novel multi-trigger control molecule and a crosslinker, which represent the resist matrix, together with a photoacid generator (PAG). Here we present results from work focused on the enhancement of the high-opacity MTR resist. The absorptivity of the resist can be increased by replacing the standard crosslinker with a high-opacity crosslinker. The absorptivity of the crosslinking molecule can itself be changed by varying both the number of attached photo-absorption groups and by varying the specific choice of the high opacity group. Other modifications to the crosslinking molecule, which are presented, include reducing the steric hindrance of the molecule by changing the structure. The high-opacity crosslinker molecules have been synthesized and then formulated into the MTR resist. We report results obtained using the new MTR system containing this high-opacity cross-linker with a variation of process conditions, and with formulation variations. The lithographic performance of a formulation containing this crosslinker, at pitch 32nm patterned on an NXE3400 is presented. The sensitivity of the resist can be increased by 25% by varying the length of the crosslinker arm whilst keeping other factors such as the number of high opacity groups constant. Furthermore, we have also investigated increasing the activation energy of the self-quenching aspect of the MTR system. In the case presented, MTR8 has a higher activation energy than MTR2 and MTR4. Having a higher activation energy is predicted to allow the introduction of a post exposed bake (PEB) to increase crosslinking and reduce pattern collapse, whilst simultaneously preserving the self-quenching behaviour. We will present results which show using a higher activation energy molecule (MTR8) results in a minimisation of Z-factor and LWR, when increasing the PEB temperature by 10 degrees compared to MTR4. Pitch 32nm dense line spaces can be patterned at a dose of 49.5mJ/cm2, a line width of 15.5nm and an biased LWR of 3.69nm. Pitch 28nm dense patterns can be patterned at a dose of 59mJ/cm2, a line width of 12.5nm, and a biased LWR of 3.91nm. These resist formulations have also been used to pattern 25nm diameter pillars on a 40nm pitch with a dose of 50mJ/cm2, and a CDU of 2.98nm. High photospeed approaches, which have patterned p24 and p28 lines and p34 hex pillars at sub-30 mJ/cm2 doses are also introduced
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