Selective Sidewall Etching for Homogeneous Trench Fill

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Solution Overview

Problem

Existing semiconductor fabrication methods using bottom-up fill techniques face challenges in maintaining consistent crystalline structures and electrical properties within fill structures, particularly where trench bottoms and sidewalls have different crystalline structures, leading to localized variations in electrical resistivity.

Innovation Solution

A method involving a semiconductor processing system that deposits a film within a recess with a bottom segment overlaying the bottom surface and a sidewall segment on the sidewall surface, where the sidewall segment is removed more rapidly than the bottom segment, using gases like dichlorosilane, hydrochloric acid, and hydrogen, and controlling deposition and removal rates and pressures to achieve a consistent crystalline structure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If bottom-up fill techniques are used to deposit film into trenches, then the trench can be filled from the bottom surface upwards, but the interface where opposing surfaces converge creates localized variations in electrical resistivity due to different crystalline structures

Engineering Contradiction:

Improvetrench fill capabilityVSAvoidelectrical property consistency

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent applies local quality by selectively removing the sidewall segment of the film while retaining the bottom segment, creating a localized modification at the trench interface. This selective removal eliminates the crystalline structure variation at the critical interface region where electrical property consistency is needed, while preserving the beneficial bottom-up fill approach for overall trench filling.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent segments the film into distinct portions: a bottom segment overlaying the trench bottom surface and a sidewall segment on the sidewall surface. This segmentation allows independent treatment of each segment, enabling selective removal of the problematic sidewall segment while retaining the bottom segment, thereby resolving the electrical property variation issue at the interface.

Inventive Principle:

Principle #1Segmentation

2Productivity

If the sidewall segment is removed more rapidly than the bottom segment, then cycle time is reduced and throughput is improved, but process complexity increases due to differential removal rate control

Engineering Contradiction:

ImprovethroughputVSAvoidprocess control complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent implements parameter changes by controlling the removal process to achieve different removal rates for the sidewall segment versus the bottom segment. By adjusting process parameters such as gas flow rates, temperature, or chemical composition during the removal step, the system achieves faster sidewall segment removal while maintaining bottom segment retention, thereby improving throughput despite increased process control requirements.

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

This approach reduces cycle time, improves throughput, and ensures a homogenous crystalline structure throughout the fill, minimizing electrical property variations and enhancing the reliability of semiconductor devices.

Implementation Method 1

A film is deposited within the recess and onto the bottom surface and the sidewall surface of the recess

Methodology Applied

Scientific EffectChemical vapor deposition: Chemical Vapour Deposition

Implementation Method 2

The sidewall segment of the film is removed while at least a portion bottom segment of the film is retained within the recess

Methodology Applied

Scientific EffectSelective etching:

Data Source

PatentUS20230005744A1Forming structures with bottom-up fill techniques

Publication Date: 2023.01.05 ASM IP HLDG BV

AI summary

A method of forming a structure includes supporting a substrate within a reaction chamber of a semiconductor processing system, the substrate having a recess with a bottom surface and a sidewall surface extending upwards from the bottom surface of the recess. A film is deposited within the recess and onto the bottom surface and the sidewall surface of the recess, the film having a bottom segment overlaying the bottom surface of the recess and a sidewall segment deposited onto the sidewall surface of the recess. The sidewall segment of the film is removed while at least a portion bottom segment of the film is retained within the recess, the sidewall segment of the film removed from the sidewall surface more rapidly than removing the bottom segment of the film from the bottom surface of the recess. Semiconductor processing systems and structures formed using the method are also described.