Resist Pattern Formation via Dual-Exposure and Baking

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Solution Overview

Problem

Current methods for forming fine resist patterns using extreme ultraviolet (EUV) lithography struggle with reducing the roughness of the resist patterns, which affects the precision and quality of semiconductor devices.

Innovation Solution

A method involving the sequential irradiation of a resist film with a first radiation followed by baking, and then batch exposure to a second radiation with a longer wavelength, which enhances the solubility contrast and reduces roughness by forming a metal hydroxide from the metal oxide photoresist material, thereby improving the development process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If EUV lithography with chemically amplified resist material is used, then fine resist patterns can be formed, but the roughness of the resist patterns cannot be sufficiently reduced

Engineering Contradiction:

Improveresist pattern roughnessVSAvoidprocess complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The exposure process is segmented into two distinct stages: first exposure with extreme ultraviolet light to form the initial pattern, and second exposure with ultraviolet light to enhance the pattern definition. This segmentation allows each exposure stage to perform a specific function, with the first exposure creating the base pattern and the second exposure refining the pattern edges to reduce roughness.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The first exposure with extreme ultraviolet light performs a preliminary action by forming the initial resist pattern before the second ultraviolet exposure refines it. This preliminary pattern formation enables the subsequent UV exposure to focus specifically on enhancing pattern definition and reducing roughness without needing to create the entire pattern from scratch.

Inventive Principle:

Principle #10Preliminary action

2Manufacturing precision

If chemically amplified resist material is used, then resist patterns can be formed, but the development contrast is insufficient

Engineering Contradiction:

Improvedevelopment contrastVSAvoidacid catalyst amount

Core Design Contradiction:

Manufacturing precisionVSQuantity of substance

Solution Approach 1:

Ultraviolet light acts as an intermediary in the second exposure stage, converting the metal oxide photoresist material to metal hydroxide in the exposed regions. This intermediary chemical transformation creates a distinct solubility difference between exposed and unexposed areas, thereby enhancing development contrast without requiring additional acid catalysts.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The chemical state of the photoresist material is changed by converting metal oxide to metal hydroxide through ultraviolet light exposure. This parameter change in the chemical composition creates regions with different solubility characteristics, improving development contrast by making the difference between exposed and unexposed areas more pronounced.

Inventive Principle:

Principle #35Parameter changes

3Manufacturing precision

If non-chemically amplified resist material is used, then fine resist patterns can be formed, but the roughness reduction is insufficient

Engineering Contradiction:

Improveresist pattern roughnessVSAvoidprocess ease

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The dual-exposure process maintains continuous useful action by ensuring that both the extreme ultraviolet and ultraviolet exposures contribute meaningfully to pattern formation. The first exposure creates the pattern, and the second exposure continuously refines it, ensuring that each step adds value and the process remains efficient despite the additional exposure stage.

Inventive Principle:

Principle #20Continuity of useful action

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach effectively reduces the roughness of the resist patterns, enhancing the precision and quality of the semiconductor devices by improving the development contrast and sensitivity.

Implementation Method 1

irradiating a part of a resist film containing a resist material with a first radiation

Methodology Applied

Scientific EffectPhotochemical reaction: Photopolymerisation

Implementation Method 2

baking the resist film

Methodology Applied

Scientific EffectThermal heating: Heating

Implementation Method 3

irradiating an entire region including the part irradiated with the first radiation and other parts in the resist film with a second radiation in a batch

Methodology Applied

Scientific EffectPhotochemical transformation: Photopolymerisation

Data Source

PatentUS20240126175A1Method for forming resist pattern, method for producing semiconductor device, substrate processing device, and storage medium

Publication Date: 2024.04.18 TOKYO ELECTRON LTD

AI summary

Disclosed is a method for forming a resist pattern including, in the following order, irradiating a part of a resist film containing a resist material with a first radiation, baking the resist film, irradiating the entire region including the part irradiated with the first radiation and other parts in the resist film with a second radiation in a batch, and forming a resist pattern by development for removing a part of the resist film.