Immersion flow field sealing method based on hydrophilic-hydrophobic alternate surface

Abstract

The invention discloses an immersion flow field sealing method based on a hydrophilic-hydrophobic alternate surface. The immersion flow field sealing method comprises two-stage hydrophilic-hydrophobic sealing, wherein the first-stage hydrophilic-hydrophobic sealing is arranged between a recovery runner of an immersion unit and the outer edge boundary of the immersion unit, and close to the recovery runner; the second-stage hydrophilic-hydrophobic sealing is arranged between a hydrophobic ring of the first-stage hydrophilic-hydrophobic sealing and the outer edge boundary of the immersion unit, and close to the outer edge boundary of the immersion unit. The immersion flow field sealing method adopts the two-stage hydrophilic-hydrophobic sealing manner to achieve a good sealing effect on the overflown immersion liquid at the flow field boundary and the independently leaked liquid drops; the problems that the airflow is not uniform, the pressure is concentrated and the advancing meniscus sucks bubbles can be solved; the system vibration due to gas sealing can be reduced; meanwhile, the proportion of the gas sealing method in the whole flow field sealing can be lowered; on the premise of ensuring the exposure quality, the scanning speed of a photoetching machine can be increased, and the capacity of the photoetching system can be improved; the immersion flow field sealing method can be directly applied to the conventional photoetching machine to simplify the system structure and lower the manufacturing cost.

Description

technical field [0001] The invention relates to a sealing method for an immersion flow field, in particular to a sealing method for an immersion flow field based on alternating hydrophilic and hydrophobic surfaces. Background technique [0002] Modern lithography equipment is based on optical lithography, using an optical system to accurately project and expose the pattern on the mask onto a substrate (such as a silicon wafer) coated with photoresist. It includes an ultraviolet light source, an optical system, a projection mask composed of chip patterns, an alignment system and a substrate covered with photosensitive photoresist. [0003] The immersion lithography (Immersion Lithography) system increases the numerical aperture (NA) of the projection lens by filling the gap between the projection lens and the substrate with a liquid with a high refractive index, thereby improving the resolution and focus of the lithography. deep. A common approach is to confine the liquid t...

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Problems solved by technology

[0005] 1) Problems such as uneven flow and pressure concentration at the gas sealing boundary. On the one hand, uneven air flow is not conducive to liquid sealing, causing leakage during the scanning process; on the other hand, air bubbles may be generated. If the air bubbles enter the exposure field, it will affect the imaging quality; at the same time , when the liquid is filled and the sealing gas is recovered, a gas-liquid two-phase flow will be formed, which will cause system vibration and affect the stable operation of the exposure system

[0006] 2) The immersion flow field is sealed by air sealing. When the scanning speed increases, the air sealing pressure needs to be increased at the same time to ensure the sealing effect. However, although the higher air sealing pressure controls the problem of liquid leakage, it consumes more energy. And it increases the possibility of entrainment of liquid bubbles at the advancing contact angle; at the same time, the excessive pressure around the slit flow field will cause damage to some components of the immersion lithography system, such as the projection objective lens, resulting in reduced exposure quality and exposure defect

However, this method has a very limited contribution to the improvement of the scanning speed of immersion lithography, and it is usually used together with the hermetic sealing method

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