Resist Pattern Overhang Formation for Accurate Recess Etching

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Solution Overview

Problem

Existing methods for forming resist patterns in semiconductor manufacturing face challenges in achieving high accuracy due to potential position shifts and dimensional variations during etching steps, leading to undesired exposure and incomplete processing of recesses.

Innovation Solution

A method utilizing a multi-gradation mask with light shielding, translucent, and semi-translucent features to form a resist pattern with an overhang portion, which helps maintain pattern accuracy by preventing exposure of unintended areas even with position shifts or dimensional variations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a conventional resist patterning method is used, then the manufacturing process is simple, but position shifts and dimensional variations occur during etching, leading to low accuracy in recess formation

Engineering Contradiction:

Improveaccuracy of recess formationVSAvoidcomplexity of mask structure

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The mask is divided into three distinct regions with different light transmittance characteristics: a first region (light shielding feature), a second region (partial translucent feature), and a third region (translucent feature). This segmentation allows each region to contribute differently to the resist pattern formation, enabling precise control over the overhang portion geometry and preventing position shifts during etching.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different portions of the mask are assigned different optical properties (light shielding, partial translucency, full translucency) to create specific exposure patterns in the resist. The second region's partial translucency is specifically designed to generate the overhang portion with controlled dimensions, while other regions serve different functions, achieving local optimization of the patterning process.

Inventive Principle:

Principle #3Local quality

2Manufacturing precision

If the resist pattern is formed without an overhang portion, then the process is straightforward, but exposure errors occur and hole dimensions are inaccurate

Engineering Contradiction:

Improvehole dimension accuracyVSAvoidease of resist pattern formation

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The overhang portion is formed in advance during the resist patterning step by using the second region with partial translucent feature. This preliminary formation of the overhang structure prevents exposure errors during subsequent etching operations, as the overhang acts as a protective feature that compensates for potential position shifts, thereby ensuring accurate hole dimensions without requiring additional corrective steps.

Inventive Principle:

Principle #10Preliminary action

3Reliability

If the transmittance of the semi-translucent portion is not controlled, then the mask is easier to manufacture, but the overhang amount cannot be maintained, leading to exposure errors

Engineering Contradiction:

Improveconsistency of overhang amountVSAvoidcomplexity of transmittance control

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The optical parameters of the second region are precisely controlled, specifically its light transmittance characteristics. By adjusting the transmittance of this partial translucent region, the amount of overhang formed in the resist pattern can be precisely controlled. This parameter control ensures that the overhang portion maintains consistent dimensions, preventing exposure errors and ensuring reliable patterning results.

Inventive Principle:

Principle #35Parameter changes

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

The method ensures high-accuracy processing of patterns by maintaining the integrity of recess shapes, particularly in forming contact holes for three-dimensional memory devices, by using a multi-gradation mask to create an overhang portion that compensates for potential shifts and variations.

Implementation Method 1

The resist layer is patterned with light through a multi-gradation mask. The multi-gradation mask has a partial translucent feature corresponding in position to an outer perimeter of the recess, a light shielding feature corresponding in position to the recess, and a translucent feature surrounding the partial translucent feature.

Methodology Applied

Scientific EffectPhotoresist exposure: Photopolymerisation

Data Source

PatentUS12613462B2Resist pattern forming method and semiconductor device manufacturing method

Publication Date: 2026.04.28 KIOXIA CORP

AI summary

A method of forming a resist pattern includes applying a photoresist to first and second regions of a processing target to form a resist layer. The processing target includes a stacked body of alternately stacked first and second layers. The first region includes an upper surface of the stacked body, and the second region includes a recess extending into the stacked body from the upper surface. The resist layer is then patterned with light passed through a multi-gradation mask including a partial translucent feature at an outer perimeter of the recess, a light shielding feature corresponding in position to the recess, and a translucent feature surrounding the partial translucent feature. A resist pattern is formed including an overhang portion extending above a portion of the recess.