Selective Etch-Stop Deposition for Deep EUV Pattern Transfer

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Solution Overview

Problem

Semiconductor manufacturing faces challenges with extreme ultraviolet lithography (EUV) patterning, including non-uniformities leading to aspect ratio variations, limited pattern transfer due to EUV photoresist (PR) instability during etch processes, and line bending or loss of critical dimension (CD) when trying to create deep patterns.

Innovation Solution

The selective deposition of an etch-stop layer, such as metal oxides like zirconium oxide, aluminum oxide, or hafnium oxide, is applied on top of the EUV PR to protect the pattern during etching, allowing deeper pattern transfer into the underlayer without sacrificing CD or causing line bending, using processes like conformal capping and atomic-layer-deposition to ensure precise growth and protection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of stationary object

If very thick EUV photoresist is used to transfer deep patterns, then pattern depth increases, but line bending and poor selectivity occur due to EUV not penetrating to the bottom

Engineering Contradiction:

Improvepattern depthVSAvoidcritical dimension

Core Design Contradiction:

Length of stationary objectVSManufacturing precision

Solution Approach 1:

A sacrificial gapfill material is deposited into the trenches to act as an intermediary that enables selective etch-stop layer growth on the photoresist surface while preventing unwanted deposition in the trench regions. This mediator allows the etch-stop layer to form only where needed for pattern protection during deep etching

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The protective layer is segmented into two distinct components: an etch-stop layer deposited selectively on the photoresist surface and a sacrificial gapfill material filling the trenches. This segmentation allows the protective function to be localized only to the pattern regions while maintaining open trench structures for subsequent processing

Inventive Principle:

Principle #1Segmentation

2Reliability

If conformal capping with oxide material is performed, then pattern protection is improved, but etch selectivity may be compromised without selective stop-etch layer growth

Engineering Contradiction:

Improvepattern protectionVSAvoidetch selectivity

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The etch-stop layer is applied with local quality by growing it selectively only on the oxide-capped photoresist surfaces exposed at the trench openings. The sacrificial gapfill material prevents etch-stop layer formation in the trench regions, creating spatially differentiated protection that maintains both reliability and manufacturability

Inventive Principle:

Principle #3Local quality

3Measurement precision

If EUV photoresist is used for pattern definition, then lithography resolution is achieved, but the photoresist is quickly consumed during etch processes

Engineering Contradiction:

Improvelithography resolutionVSAvoidphotoresist durability

Core Design Contradiction:

Measurement precisionVSDuration of action of stationary object

Solution Approach 1:

The etch-stop layer is deposited beforehand on the photoresist surface to provide a protective cushion during the etching process. This pre-applied protective layer absorbs the mechanical and chemical stress of deep etching, preventing photoresist consumption and maintaining pattern integrity throughout the etch duration

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

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 method enables deeper etching into the underlayer while maintaining the critical dimension and preventing line bending, allowing for more effective pattern transfer without additional EUV PR thickness, applicable to various substrate structures.

Implementation Method 1

conformal capping with an oxide material

Methodology Applied

Scientific EffectPhysical Vapour Deposition: Physical Vapour Deposition

Implementation Method 2

selective growth of stop-etch material on exposed surfaces

Methodology Applied

Scientific EffectSelective Deposition: Physical Vapour Deposition

Data Source

PatentUS11869770B2Selective deposition of etch-stop layer for enhanced patterning

Publication Date: 2024.01.09 LAM RES CORP

AI summary

Methods, systems, and computer programs are presented for selective deposition of etch-stop layers for enhanced patterning during semiconductor manufacturing. One method includes an operation for adding a photo-resist material (M2) on top of a base material (M1) of a substrate, M2 defining a pattern for etching M1 in areas where M2 is not present above M1. The method further includes operations for conformally capping the substrate with an oxide material (M3) after adding M2, and for gap filling the substrate with filling material M4 after the conformally capping. Further, a stop-etch material (M5) is selectively grown on exposed surfaces of M3 and not on surfaces of M4 after the gap filling. Additionally, the method includes operations for removing M4 from the substrate after selectively growing M5, and for etching the substrate after removing M4 to transfer the pattern into M1. M5 adds etching protection to enable deeper etching into M1.