Immersion lithography device and immersion exposure method

Abstract

Immersion lithography system and method using a sealed wafer bottom is disclosed in embodiments of the present invention. In one embodiment, the immersion lithography apparatus including a lens assembly comprising an imaging lens and a wafer stage for retaining a wafer beneath the lens assembly and comprising a seal ring for sealing a gap between a bottom edge of a wafer retained on the wafer stage and the wafer stage. The apparatus further includes a fluid tank for retaining immersion fluid, the fluid tank situated with respect to the wafer stage for enabling full immersion of the wafer retained on the wafer stage in the immersion fluid; a cover disposed over at least a portion of the fluid tank for providing a temperature-controlled, fluid-rich environment within the fluid tank; and at least one directional flow control fluid inlet surrounding the imaging lens for directing immersion fluid toward an edge of the wafer retained on the wafer stage closest to the imaging lens.

Description

technical field [0001] The present invention relates to immersion lithography, and more particularly to an immersion lithography system using a sealed wafer bottom. Background technique [0002] Immersion lithography is a relatively recent development in lithography in which the exposure step is performed by filling a liquid between the wafer surface and the lens. Using immersion lithography creates a larger number of openings than when using the lens in air, thereby increasing resolution. Moreover, in the case of immersion, an enhanced depth-of-focus (DOF) for providing smaller features is provided. Generally speaking, there are two types of immersion lithography system structures, including lens-based (lens-based; LBC) systems and wafer-based (wafer-based; WBC) systems. With a WBC system, the wetting fluid is selectively applied to and removed from a small area between the lens and the wafer, and the wetting group is stationary relative to the lens while the wafer is mov...

AI Technical Summary

Problems solved by technology

[0005] Problems associated with LBC systems include: near the edge of the wafer, the wetted area includes the wafer and the peripheral area of ​​the chuck, so that maintaining fluidity and facilitating fluid removal at the fluid hole can become difficult

The above practices result in fragments of cracked photoresist left behind in case of fluid washout, resulting in particle defects

Also, fluids can seep below the wafer to become a source of contamination and are equally susceptible to contamination

Evaporation of fluid can cause uneven cooling and uneven coverage

[0009] It can be seen that in the existing LBC and WBC systems, there are problems such as fluid temperature and fluid evaporation are difficult to control, and it is easy to cause uneven cooling and coverage of the wafer, as well as pollution.

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