Immersion lithography method and processing system

Abstract

A method of performing immersion lithography on a semiconductor substrate includes providing a layer of resist onto a surface of the semiconductor substrate and exposing the resist layer using an immersion lithography exposure system. The immersion lithography exposure system utilizes a fluid during exposure and may be capable of removing some, but not all, of the fluid after exposure. After exposure, a treatment process is used to remove the remaining portion of fluid from the resist layer. After treatment, a post-exposure bake and a development step are used.

Description

technical field [0001] The invention relates to a manufacturing method of a semiconductor device, in particular to a method and system for removing photoresist residues on a semiconductor substrate. Background technique [0002] Photolithography is the technique of projecting a pattern on a mask onto a substrate such as a semiconductor wafer. In the field of semiconductor lithography technology, it is necessary to minimize the feature size of the pattern on the semiconductor wafer under the resolution limit or critical dimension, and the current critical dimension has reached below 65nm. [0003] Semiconductor photolithography generally includes coating photoresist on the top surface of a semiconductor wafer (such as a thin layer stack structure), exposing the photoresist to form a pattern; exposing the exposed photoresist and then baking it to make the polymer-based The substance is cracked; the cracked polymer photoresist is moved to the developing tank, and the exposed p...

AI Technical Summary

Problems solved by technology

[0005] The immersion exposure step can use deionized water or other suitable immersion exposure liquid between the wafer and the lens. Although the exposure time is very short, the contact of the liquid with the light-sensitive layer (such as photoresist) will cause problems, such as after processing. Small droplets left behind, and / or residue from liquid and photoresist can adversely affect photoresist patterning, feature size, and other aspects. At least three different defect mechanisms have been identified

[0006] The first defect mechanism is contamination of the immersion liquid with soluble species from the photoresist, which can cause problems in subsequent processing

The second defect mechanism is that the liquid has an adverse effect on the photoresist, causing uneven heat absorption and evaporation during post-exposure baking, which will cause different temperature distributions in different parts of the wafer

The third defect mechanism is that the liquid diffuses into the photoresist and limits the chemical amplification reaction (CAR) used in the subsequent photolithography process

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