Phase Shift Mask Pattern Design for Semiconductor Integration

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Solution Overview

Problem

The challenge in semiconductor device fabrication is the collapse or breakage of lower electrodes due to large aspect ratios, and the difficulty in achieving uniform distribution of open regions, leading to poor capacitor formation and potential device failure, especially when using high transmittance phase shift masks.

Innovation Solution

A phase shift mask with main, assist, and dummy patterns arranged in a honeycomb structure, where the dummy patterns have a larger area than the main patterns, is used to improve optical proximity correction and prevent side lobes, ensuring uniform formation of open regions and supporting lower electrodes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the area of unit cells or capacitors is decreased to increase integration, then the integration density is improved, but the required capacitance cannot be achieved and lower electrodes may collapse or break

Engineering Contradiction:

Improveintegration densityVSAvoidlower electrode stability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The support structure is segmented into multiple regions (first support region, second support region, third support region) with different pattern configurations. Each region contains main patterns, assist patterns, and dummy patterns arranged in specific relationships, allowing localized optimization of both capacitance and structural stability without compromising overall integration density

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the support are given different local qualities through varying pattern densities and configurations. The first support region has a specific arrangement of main and assist patterns, while the second and third support regions have different arrangements, allowing each region to be optimized for its specific function while maintaining overall device integration

Inventive Principle:

Principle #3Local quality

2Measurement precision

If high transmittance phase shift masks are used to improve photolithography performance, then the exposure quality is improved, but side lobes occur and uniform distribution of open regions cannot be achieved

Engineering Contradiction:

Improveexposure qualityVSAvoiduniformity of open regions

Core Design Contradiction:

Measurement precisionVSManufacturing precision

Solution Approach 1:

Dummy patterns are预先 formed in the photolithography mask along with the main patterns and assist patterns. These dummy patterns are positioned and sized to preemptively counteract the side lobe effects that would otherwise occur during photolithography exposure, ensuring uniform open region distribution before the actual capacitor formation process begins

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The side lobe effects, which are normally harmful artifacts in photolithography, are converted into beneficial features by strategically placing dummy patterns. These dummy patterns generate their own diffraction patterns that interfere constructively with the main beam, filling in the dark regions caused by side lobes and creating a more uniform exposure distribution across the substrate

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 enhances the reliability of semiconductor devices by preventing lower electrode collapse, improving the uniformity of open regions, and maintaining the integrity of the photolithography process, thereby ensuring the successful formation of capacitors and overall device performance.

Implementation Method 1

phase shift mask includes on a transmissive substrate: main patterns arranged at a first pitch, each of the main patterns having a first area, assist patterns surrounding the main patterns and arranged at the first pitch, each of the assist patterns having a second area smaller than the first area, and dummy patterns surrounding the assist patterns and arranged at the first pitch, each dummy pattern having a third area larger than the first area

Methodology Applied

Scientific EffectOptical interference: Interference

Implementation Method 2

Methodology Applied

Scientific EffectDiffraction: Diffraction

Data Source

PatentUS11327395B2Semiconductor device

Publication Date: 2022.05.10 SAMSUNG ELECTRONICS CO LTD

AI summary

A method for fabricating a phase shift mask includes preparing a transmissive substrate on which a first mask region and a second mask region surrounding the first mask region are defined. In the first mask region, main patterns are formed having a first pitch in a first direction and a second direction perpendicular to the first direction. Each of the main patterns has a first area. In at least one row, assist patterns are formed at the first pitch to surround the main patterns. Each of the assist patterns has a second area less than the first area. In the second mask region, dummy patterns are formed in a plurality of rows. The dummy patterns surround the assist patterns at the first pitch. Each of the dummy patterns has a third area greater than the first area.